WO2016135286A1

WO2016135286A1 - Method for stimulating dendritic cells (dcs)

Info

Publication number: WO2016135286A1
Application number: PCT/EP2016/054079
Authority: WO
Inventors: Thomas Felzmann; Alexander Dohnal
Original assignee: Activartis Biotech Gmbh
Priority date: 2015-02-26
Filing date: 2016-02-26
Publication date: 2016-09-01

Abstract

The invention discloses a method for stimulating dendritic cells (DCs), wherein immature DCs or precursor cells thereof are stimulated and matured comprising exposure to an antigen and an MK2 and/or JAK1 inhibitor.

Description

Method for Stimulating Dendritic Cells (DCs)

The present invention relates to a method for producing den^¬ dritic cells (DC) and uses thereof.

During the last years the dendritic cell (DC) has been recognised as the central regulator of immunity. Human DCs are generated by in vitro differentiation from haematopoietic stem cells or peripheral blood monocytes in the presence of growth factors, typically interleukin (IL) 4 and granulocyte-macrophage colony-stimulating factor (GM-CSF) . Recent evidence suggests that DCs have the capacity to flexibly respond to the encounter of microbial, traumatic, or metabolic stress. Thus, DCs do not only differentiate into one subtype that fulfils a particular function, e.g. activation or tolerance, type 1 or type 2 T- helper lymphocyte (T_H1, T_H17) polarisation, but assume distinct functional states in a time-kinetic fashion appropriate to the challenges encountered in a given environment. DCs are essential mediators between innate and adaptive immunity. They elicit cy- tokine-driven immune responses upon invasion of pathogens.

A switch of DCs from tolerance maintenance to immune stimulation, referred to as maturation, may be initiated by pathogen- or damage-associated microbial patter, PAMP or DAMP (Medzhitov et al., Science 296 (2002), 298-300), DAMP (Schreiber et al., Science 331 (2011), 1565-1570)), pro-inflammatory cytokines (Jonuleit et al., Eur. J. Immunol. 27 (1997), 3135-3142), or CD40/CD40L signalling (Macagno et al . , Trends Immunol. 28 (2007), 227-233) . PAMP recognition, like binding of lipopolysac- charide (LPS) to Toll-like receptor (TLR) -4 on DCs, must be stringently regulated, as excessive expression of signalling components as well as pro-inflammatory cytokines can have devastating effects on the host, resulting in chronic inflammatory diseases or autoimmune disorders. Therefore it is essential that negative regulators act on multiple levels within the TLR signalling cascade involving interferon regulatory factors (IRF) and NF-kappaB transcription factors, the mitogen-activated pro^¬ tein kinase (MAPK) pathways and the JAK/STAT signalling pathway.

On a systemic signalling level the Erkl/2 and p38 MAPKs are critical for both, pro- and anti-inflammatory immune responses. They direct the production of cytokines, which are essential for the differentiation of naive CD4⁺ helper T cells into T_H1, T_H17 or regulatory (Treg) cell subsets. The mitogen- and stress- activated kinases (Msks) and MAPK-activated protein kinases (MKs) , the downstream substrates of Erkl/2 and p38, regulate TLR-driven inflammation on a more distinguished signalling level. Thereby MK2 contributes to inflammation due to its essential role in the expression of TNF-alpha, IL-lbeta and IL-6 in macrophages. However, recent observations indicate an additional anti-inflammatory function of MK2 by regulating IL-10-mediated signal transducer and activator of transcription (STAT) -3 activation in DCs .

In the early phases of the maturation process initiated by the encounter of TLR agonistic danger molecules, DCs acquire a pro-inflammatory mode of action, which is characterized by the secretion of TNF-alpha, IL-1 and IL-12, molecules critical for the regulation of adaptive immune responses. IL-12 is released for approximately one day after a DCs exposure to LPS or other danger signals. During that phase DCs trigger T_H1 responses and as a consequence initiate CD8⁺ killer T cell dominated immune responses in vitro and in vivo. In addition to their effector cell priming capacity, DCs assume an anti-inflammatory mode of action approximately one day after the initiation of LPS stimulation. This phase is characterised by enhanced activity of the trypto^¬ phan metabolising enzyme indoleamine 2,3 dioxygenase (IDO) and a high secretion level of IL-10, which supports an antiinflammatory DC phenotype mediated by the autocrine IL-10/STAT3 signalling cascade. Both, IDO and IL-10 expressed in DCs contribute to the priming of Treg cells.

IL-12 release ceases after about 24 hours indicating that the encounter between DCs and T-lymphocytes needs to take place within that time window to allow efficient type 1 polarisation and activation of cytotoxic T lymphocytes (CTL) . In contrast, the expression of co-stimulatory molecules reaches its maximum after 2 days. Since per definition a mature DC is characterised only phenotypically by maximum expression of co-stimulatory molecules but not functionally, the IL-12 releasing type 1 po^¬ larising DC is sometimes referred to as semi-mature (sm) DC (WO 2009/074341 Al) .

After approximately 2 days the DC reaches the stage of so called maturity. During the second day of its differentiation the DCs lose their immune stimulatory capacity and acquire im- mune suppressive properties by up-regulation of molecules that mediate negative regulatory feedback loops. The biological significance of this differentiation phase is the necessity of keeping immune responses under strict control. An activated immune cell, particularly a CTL that is enabled for the killing of other cells, poses a considerable threat to an organism. This is exemplified by the pathological consequences of immune responses that dodged their control: autoimmune disease such as type I diabetes or multiple sclerosis. Therefore, the same DC that during day 1 after encountering a maturation signal primes immune responses will dampen this same immune response during day 2 of their differentiation process. Therefore, fully mature DCs are in fact not as originally thought immune stimulatory but rather immune suppressive cells and therefore inadequate for therapeutic interventions aimed at immune stimulation such as their use in cancer immunotherapy or the treatment of microbial diseases.

It is important to distinguish between immature (tolerance maintaining), semi-mature DCs (immune stimulatory), and mature (immune suppressive) DCs (Figure 1; for details, see e.g. WO 2009/074341 Al ) . An iDC maintains tolerance against auto- antigens. An smDC has encountered one of the maturation stimuli described above and has irreversibly committed to differentia^¬ tion into mDCs within approximately 2 days. Importantly, only during the first one of those 2 days it is enabled for IL-12 release, initiation of type I immune polarisation, and conse^¬ quently support of a CTL mediated immune response. Once a maturing DC enters the second phase of differentiation after one day it acquires immune suppressive properties. It is a convention among immunologists to characterise an mDC by the expression of membrane molecules such as CD80, CD83, or CD86. However, in contrast to IL-12 that reaches maximum expression within a few hours and is lost after 24 hours, these membrane molecules reach their maximum expression only after 48 hours. In order to clearly distinguish the IL-12 secreting DCs that are described herein from what is conventionally understood by the name mature DC, the term semi-mature DCs was chosen. This, very importantly, shall not imply some kind of functional deficiency but only a certain differentiation stage at the time kinetic scale. The smDC is functionally different from an iDC as well as from an mDC . The DCs immune suppressive mode of action is initiated via JAK/STAT signalling. In DCs, the JAK/STAT pathway is closely connected to the MAPK signalling pathway (Figure 12-13) . Cyto^¬ kines produced in response to signalling along the MAPK pathway bind in an autocrine loop to cytokine receptors on DCs. Signalling in the MAPK pathway is therefore continued through the JAK/STAT pathway. The expression of immune stimulatory cytokines triggered by MAPK signalling dominates early after the DCs encounter a danger signal . Via the MK2 arm of the MAPK pathway the expression of immune suppressive cytokines is initiated. They do not act directly but via autocrine binding to cytokine receptors on DCs and signalling through the JAK/STAT pathway. Ultimately, immune suppressive cytokines released from the DCs as a conse^¬ quence of JAK/STAT signalling terminate the immune response. However, the autocrine loop causes a delay such that for about 1 day after encountering a danger signal the DCs feature an immune stimulatory mode of action, whereas after this 1 day delay the immune suppressive mode of action becomes dominant. Hence, the MAPK and JAK/STAT pathways represent a functional unit in DCs .

The use of DCs in cellular immune therapy, especially in cancer therapy has been suggested in the past. However, only a few proposals showed clinical effectiveness (WO 2004/024900 Al, WO 2009/074341 Al ) . There is still an urgent need for steady improvements of such therapies based on DCs.

It is an object of the present invention to provide a method for producing DCs based on activation with a specific cocktail enabling improved properties of such cells, specifically for medical use. These DCs may be used to produce pharmaceutical preparations .

Therefore, the present invention provides a method for producing and/or stimulating dendritic cells (DCs) , wherein immature DCs or precursor cells thereof are stimulated and matured comprising exposure to an antigen, a maturation agent, preferably from the group of Toll-like receptor agonists, and an in^¬ hibitor selected from the group consisting of an MK2 inhibitor, a JAK1 inhibitor or a combination of a JAK1 inhibitor and a MK2 inhibitor, wherein the stimulation and/or maturation agent pref^¬ erably comprises LPS.

The present invention provides a method for stimulating DCs, wherein immature DCs or precursor cells thereof are stimulated and matured comprising exposure to an antigen, a danger signal, especially the TLR agonist LPS in the presence of IFN-gamma, and substances that disrupt the immune suppressive signalling via the MAPK and JAK/STAT pathways. Small molecule kinase inhibitors may be used to block the immune suppressive signalling. Lipopolysaccharides (LPS) , also known as lipoglycans and en^¬ dotoxins, are large molecules consisting of a lipid and a polysaccharide composed of O-antigen, outer core and inner core joined by a covalent bond; they are found in the outer membrane of bacteria, and elicit strong immune responses in animals. LPS stimulates cells of the innate immune system by the Toll-like receptor 4 (TLR4) . LPS may be provided by a preparation of dead or living microorganisms, including BCG (Bacillus Calmette- Guerin) or by a fraction or extraction of such microorganisms, e.g. E. coli. For example, LPS may be extracted from E. coli preparations by phenolic extraction (e.g. "hot phenolic extraction" of lysed bacteria (optionally treated with proteinases, DNases and RNases so as to eliminate proteins and nucleic acids; see e.g. Rezannia et al., Avicenna J. Med. Biotechnol. 3 (2011) : 3-9) ) . There are also commercially available LPS preparations and commercially available LPS extraction kits. LPS-activated or LPS-stimulated DCs are therefore well available in principle to a person skilled in the art.

With the present invention it was shown for the first time that direct blocking of MK2 or JAK1 activity with MK2 or JAK1 inhibitors enables DCs (which have preferably been activated/stimulated with LPS) to strengthen pro-inflammatory effector mechanisms by promoting IL- lalpha-mediated T_H1 and T_H17 and blocking Treg responses. Further, MK2 or JAK1 deficient DCs trigger enhanced CTL activity. The data obtained in connection with the present invention show that MK2 and JAK1 exert a profound anti-inflammatory effect that prevents DCs from prolonging excessive effector T cell function, which is disrupted by MK2 or JAK1 inhibitors.

From that it was shown that blocking MK2 or JAK1 enhances immune responses, which can specifically be used in (i) cancer immune therapy; or in (ii) anti-microbial prophylactic or thera^¬ peutic vaccinations .

For example, antigen charged and TLR agonist matured (LPS, R848, etc.) DCs are manipulated ex vivo with an MK2 or JAK1 blocking agent (a small molecule kinase inhibitor) in order to enhance its immune stimulatory potential upon returning to the organism. But it is also possible to directly apply the maturation agent, and MK2 or JAK1 inhibitor, preferably as adjuvant combination, directly to an organism more similar to a conventional vaccine. This might be done in form of a ready to use vaccination kit. The kit may comprise one or more antigens (e.g. in the case of pathogen vaccination) ; the antigen may also directly be present in the patient to be treated, e.g. in the case of tumour vaccination.

In the example section below it is shown that LPS provides a significantly improved effect for the DCs according to the pre^¬ sent invention concerning MK2 blockade compared to DCs treated with other stimulation/maturation substances, especially compared to R848 and poly(I:C) treated DCs. In contrast to LPS and R848, poly(I:C) did not trigger MK2 phosphorylation in DCs. Also IL-12 secretion was enhanced in MK2 -inhibitor-3 (MK2-I3) , a small molecule inhibitor of MK2 , treated LPS-DCs, but not in R848 and poly(I:C) matured DCs. As for IL-lalpha or IL-12, IL-10 was reduced in MK2-blocked DCs matured with LPS and to a lesser extent R848; poly(I:C) activation did not affect IL-10 expres^¬ sion. IL-17 secreting T-cells were found increased in MK2- inhibited LPS-DCs, but not at a significant rate in R848-DCs; poly(I:C) was not considered in further experiments. MK2-I3 treated LPS-DCs and to a lower extent R848-DCs were found to support IFN-gamma secretion. The IL-10 secretion from Tregs was lower when contacted with MK2-I3 treated LPS-DCs compared to controls; the same trend was observed in R848-DCs but at a lower extent. Accordingly, the effect of MK2 -blockade of DCs undergoing LPS-mediated maturation is strongest and, consequently, LPS- DCs are most preferred in the present invention. R848 maturation of MK2-targeted DCs shows a similar trend but considerable weaker compared to LPS and is, therefore less preferred. Poly(I:C) was the least active maturation agent and could not support the modulation of the characteristics of DCs by MK2- blockade. However, other stimulating substances, such as R848 and poly(I:C) may be used in combination with LPS to achieve the advantageous effects of LPS treated DCs.

The method according to the present invention is a method for specifically targeting T-lymphocyte subsets with specifically advantageous effects, including

increasing T_H17-mediated immunity;

increasing T_Hl-mediated immunity;

enhancing CTL activity; and

reducing the activity of immune suppressive Tregs.

DCs derived from precursor cells such as peripheral blood monocytes or blood stem and progenitor cells can be differentiated using cytokines, preferably a combination of IL-4 and GM- CSF, but also either of these cytokines alone, or each one with IL-3, IL-13, type I/II interferons, TNF-alpha, PG-E2, IL- lalpha/beta .

Many immunosuppressive effector mechanisms are now referred to as immune checkpoint inhibitors (ICP) . On a conceptual level one may describe these ICP mechanisms as originating from immune regulatory cells of the innate immune system, e.g. dendritic cells (DC) , and directed at immune effector cells of the adaptive immune system, mainly activated T- or B-lymphocytes .

Conventionally, ICP effector mechanisms include:

Membrane molecules: Programmed death (PD) family molecules,

CTLA-4, B7-H1

Cytokines: IL-10, TGF-β, etc.

Enzymes: IDO metabolising tryptophan, which is needed by activated T-cells.

According to the present invention an additional category of molecules involved in ICP mechanisms is added:

Small molecule kinase inhibitors: Blocking signalling molecules in DCs that initiate ICP mechanisms, MK2 of the MAPKAP kinase pathway, JAKl of the JAK/STAT pathway.

MAPKAP kinase and JAK/STAT pathways in DCs are involved in coordinating their time kinetic immunostimulatory and immunosuppressive features: Immediately after exposure of a DC to a danger signal, e.g. the microbial danger-associated pattern molecule lipopolysaccharide (LPS), the DC switches from a tolerance maintaining into a potently immunostimulatory mode of action that is followed approximately one day later by a second switch of the DC into an immunosuppressive mode of action during which the ICP mechanisms become active. This second switch is initi^¬ ated by the class of signalling molecules described in the present invention; or in other words: The signalling molecules of the present invention lead to the DCs second switch from the immunostimulatory in the immunosuppressive mode of action, the secreted and membrane ICP molecules are effector molecules that execute the immunosuppression once their expression is up- regulated at the ICP.

From this evidence it can be concluded that the molecules of the present invention share several unique features that distin^¬ guishes them from secreted or membrane ICP molecules:

In contrast to the above-described ICP effector molecules that act in-between immune cells, the class of intra-cellular molecules described in the present invention are - as suggested by the available experimental evidence - not effector molecules but signal transduction molecules in DCs: The MK2 molecule is a component of the MAPKAP kinase signalling pathway, the JAK1 molecule is a component of the JAK/STAT signalling pathway (see also : Figure 15 ) :

MK2 and JAK1 are kinases in functionally connected signalling pathways

It appears not meaningful, to consider one without the other Outcome of MK2 inhibition and JAK1 inhibition is the same The inhibitors of MK2 and JAK1 are both small molecule kinase inhibitors.

According to the definitions of the European drug agency EMA the present invention represents a cellular advanced therapy medicinal product (ATMP) . According to a specifically preferred embodiment, this ATMP may be characterised as being e.g. a DC that is activated via a 6 hours exposure to a cocktail comprised of LPS, IFN-γ, IL-4, GM-CSF, and small molecule kinase inhibitors targeting MK2 and/or JAK1. The ATMP according to the present invention may be applied to a patient after 6 hours treatment with the cocktail described above, but used only after the cocktail is eliminated before inoculation; no component of the cocktail enters the patient so that only the DCs pre-treated in vitro during the manufacturing procedure is the ATMP' s active ingredient .

The prior art before the present invention did not contain any reference to ICP inhibition (ICPI) nor were small molecule kinase inhibitors for ICP blockade suggested therein.

For example, Franks et al. (Int. J. Cancer 134 (3) (2013) : 575-586) shows the use of myDCs derived from peripheral blood versus differentiated in vitro from monocytes. The authors themselves state that myDCs are different from moDCs; according to the nomenclature of Franks et al . , the present invention applies moDCs (see e.g. Franks et al, page 134, right column, upper paragraph) . Such moDCs of Franks et al. are actually macro^¬ phages, as IL-4 is missing from the maturation cocktail. Franks et al. use two types of DCs: (i) monocyte derived DCs (moDCs) and peripheral blood myeloid DCs (myDCs) . The moDCs were differ^¬ entiated from monocytes in vitro using IL-4/GM-CSF.

For activation/maturation of moDCs it appears that they had a completely different cocktail. polyI:C and R848 was used in Franks et al whereas according to the present invention, LPS is used; there appears to be no IL-4 and no IFN-γ in the maturation cocktail, which has to be considered as being of critical impor^¬ tance (see e.g. Fig. 12) . IL-4 is added to the DC differentiation culture in order to prevent the monocytes from differentiating into macrophages. In the maturation culture, IL-4 is important for stabilisation of the DC phenotype as they still may switch into macrophages. IFN-γ is a co-factor for TLR-mediated stimulation of DCs, e.g. enhancing the production of IL-12.

The myDCs were selected from peripheral blood using a selec^¬ tion method based on CDllc monoclonal antibodies coupled to magnetic beads. myDCs do not require a differentiation culture as they are already DCs. Hence, Franks et al . used them immediately for activation/maturation experiments. Physiologically in vivo differentiated myDCs have a stable phenotype and do not switch into macrophages. Conseguently, IL-4 is not needed.

The observations of Franks et al . are consistent with the notion that what is called moDCs in Franks et al. are in fact macrophages. The response to MK2 blockade was the same as described in several earlier papers by Gaestel et al . (Nat. Rev. Drug Disc. 8 (2009): 480-499) and Gaestel (Nat. Rev. Mol. Cell Biol. 7 (2006): 120-130): the main function of MK2 was found to be immunostimulatory and blocking MK2 reduced the stimulatory capacity. In contrast, myDCs appear to act like genuine DCs, which is not surprising given that they were differentiated un^¬ der physiologic conditions instead of artificial cell culture conditions. The function of MK2 in DCs is the opposite from its function in other immune cells: it acts immunosuppressive and blockade of MK2 improves the stimulatory capacity of myDCs.

The DCs according to the present invention are optimised for resembling physiologic DCs. It, therefore, was observed that these DCs responded to MK2 inhibition in the same way as the myDCs of Franks et al . : the immunostimulatory capacity was improved showing that the LPS-containing cocktail used for the present invention assures that the cells resemble DCs with regard to the function of MK2 and its response to MK2 blockade.

Together this shows that all components of the DC activa^¬ tion/maturation cocktail are of critical importance for in vitro differentiated DCs in order to resemble physiologic DCs as closely as possible. In particular, this holds true with regard to the immunosuppressive function of MK2 and the improvement of immunostimulation using MK2 inhibitors. This also explains the capacity of MK2 blockade as a method for ICPI in a novel ATMP that is based on DCs.

The differences between Franks et al. and the present invention for producing monocyte derived DCs (moDCs) can be summarised as follows:

Franks et al. Present invention

RPMI + 10% FCS CellGro myDC & moDC; moDCs probably DCs characteristics like macrophages as no IL-4 for stamyDCs but in vitro production bilising DC phenotype in the comparable to moDCs, except Franks et al. Present invention maturation culture for IL-4 in the maturation

cocktail

PBMCs from density centrifuga- PBMCs from leukocyte aphaere- tion sis

myDCs from CDllc selection Monocytes from elutriation Monocytes from CD14 selection IL-4/GM-CSF 6 days lxloVml IL-4/GM-CSF 5-6 days 0,5xl0⁶/ml

moDCs ,

Charging: 1 hour with lysate Charging: 2 hours with lysate Maturation: GM-CSF Maturation: IL-4/GM-CSF/IFN-y TLR agonist: polyl : C/R848 , TLR agonist: LPS, 6 hours 24 hours p38 inhibitors: U0126, SB203580, p38 inhibitors: SB203580, SP600125 (10 μΜ) ; BIRB0796 (0,1- BIRB0796 (as control)

1 μΜ) , MK2-I3

MK2-I3 (1-3 μΜ)

Pre-treatment 1 hour before

maturation

MK2 has different functions in DCs at different time points, e.g. immediately after TLR agonist contact versus, 12-24 hours later; we studied MK2 function at later time points. For p38 blockade SB203580 (same as done as control reagent in the example section, below) and BIRB0796 used, for MK2 blockade MK2-I3. MK2-I3 is used in only one experiment in Franks et al.: Fig^¬ ure 2d(i) & (ii) of Franks et al . ; blocking p38 with BIRB0796 or MK2 with MK2-I3 has opposite functions in myDCs (enhanced IL-12 secretion) and moDCs (reduced IL-12 secretion) , IL-10 secretion is not significantly changed; given is only fold change, no absolute IL-12 concentrations. But: Figure 2a (i) of Franks et al . shows IL-12 secretion (upper two bar graphs) on very different scales; up to 10 ng/ml for myDCs, up to 80 ng/ml for moDCs; it is therefore to be assumed that further improvement when starting from such a high level in moDCs is more difficult compared to starting from a lower level as in myDCs. In fact, as shown in the example section below and Fig. 12, the opposite from the findings of Franks et al. (or the interpretation of these find^¬ ings by those authors) can be observed: Franks et al. claim reduction in stimulatory capacity when MK2 is blocked in moDCs whereas the present invention achieves an improvement of stimulatory capacity when MK2 is blocked in moDCs. There is neither a potential use of ICP inhibitors in DC cancer vaccination disclosed in an enabling manner in Franks et al nor is any evidence presented. Quite in contrast, the examples performed in the course of the present invention show the advantageous properties of DCs in a clinical preparation.

Zaru et al. (Nat. Immunol. 8 (11) (2007): 1227-123) report that the MAPK-activated kinase Rsk controls an acute TLR signalling response in DCs. Davis et al . (Chem. Cent. J. 7 (1) (2013) : DOI: 10.1186/1752-153X-7-18) describe the effect of small- molecule inhibition of MAPKAPK2 on cell ageing phenotypes of fibroblasts from human Wernersyndrome . Schlapbach et al . (Fut. Med. Chem. 1 (7) (2009) : 1243-1257) disclose low-molecular weight MK2 inhibitors. Goh et al . (Rheumatol. 51 (1) (2011): 7- 23) review the activation of TLRs in rheumatoid arthritis. Gur- gis et al. (Mol. Pharmacol. 85 (2) (2013): 345-356) report the role and targeting of MAPKAPK2 in neuroinflammation . Bain et al. (Biochem. J. 408 (3) (2007) : 297-315) disclose an update on the selectivity of protein kinase inhibitors. Vacchelli et al. (On- coimmunol . 2 (10) (2013): e25771-l-15) review DC-based interventions for cancer therapy. Dudek et al . (Front. Immunol. 4 (2013): DOI: 10.3389/fimmu .2013.00438 ) discloses the use of im^¬ mature, semi-mature and fully mature DCs on the way towards a DC-cancer cells interface that augments anticancer immunity.

McGuire et al . (Mol. Cel. Biol. 33 (21) (2013): 4152-4165) discloses the use of macrophages but not DCs. However, only DCs, but not macrophages, are considered antigen presenting cells that prime naive T-cells. Several authors (Gaestel et al., Gaestel) claim that MK2 in macrophages is immunostimulatory, hence blockade would cause reduced immunity. DCs and macrophages are closely related; one has to assume that MK2 has the same features in both cell types; thus, it is not obvious that in fact MK2 in DCs is immunosuppressive. However, according to the present invention, the functional connection of MAPKAP kinase signalling pathways with JAK/STAT kinase signalling pathway was investigated, whereas McGuire et al. investigated the connection with Alk signalling pathway and PIP3.

Ishida et al. (WBRC 312 (3) (2004): 722-727) also did not use DCs nor TLR agonist, but only a p38 inhibitor, no MK2 or JAK1 inhibitor. Moreover, activity against HCV was investigated in Ishida et al ..

Mourey et al. (J. Pharmacol. Ex. Therap. 333 (2010): 797- 807) used the U937 cell line or PBMCs but did not include any information regarding DCs. LPS is only applied to PBMCs, not to DCs. Mourey et al . disclose the immunostimulatory properties of MK2 ; hence MK2 blockade is immunosuppressive in PBMCs which is in line with the majority of publications on MK2 activity in non-DC immune cells (Gaestel et al.) .

As MK2 acts immunosuppressive in DCs, the present invention applies MK2 blockade as immunostimulatory.

Moens et al. (Genes 4 (2) (2013): DOI : 10.3390/genes4020101) explicitly refers in paragraph 5.1, page 108 to the immunostimulatory role of MK2 in inflammation. In this document, no DCs but only macrophages are applied and only p38 small molecule kinase inhibitors are mentioned.

Accordingly and in contrast to the prior art documents dis^¬ closed above, the function of a cell needs to be described in a dynamic fashion; freezing one event such as MK2 activity taking place at a certain time during this cell's functional differen^¬ tiation following an external stimulus such as a TLR agonistic molecule is highly artificial and does not represent a physiologic picture; no reference is made in any of these documents to the exact kinetic status of tested cells and no evidence for MK2 function in DCs was made available (except in Franks et al.; however, therein with the opposite conclusion with respect to the present invention) .

The present invention therefore provides a strategy that opposes the current understanding of MK2, because MK2 in immune cells except DCs is immunostimulatory and MK2 in DCs is immuno^¬ suppressive .

Hence, it was very surprising to use MK2 (and JAK1) inhibition to improve the immunostimulatory capacity of DCs according to the present invention.

Moreover, every single functional component of the activa- tion/maturation cocktail, i.e. LPS, IFN-gamma, IL-4, GM-CSF, and the small molecule kinase inhibitors targeting MK2 and/or JAK1, is relevant and therefore specifically preferred.

According to the present invention, this cocktail is usually removed before application to a patient. According to a preferred embodiment, only 6 hours of treating DCs with this cocktail is sufficient for initiating an immunostimulatory mode of action but preventing the DCs' switch into the immunosuppressive mode of action.

According to a preferred embodiment, stimulation and matura^¬ tion of the DCs therefore comprises exposure of the cells to cytokines, preferably a combination of IL-4 and/or GM-CSF or GM- CSF alone.

The DCs according to the present invention may be charged with antigens derived from microorganisms such as bacteria, viruses, or fungi; or any type of autologous and/or allogeneic tu^¬ mour or tumour cell lines including tumour stem and/or progenitor cells, in the form of synthetic peptides, recombinant proteins, cellular extracts; synthetic, recombinant or tumour ex^¬ tracted RNA or DNA, or combinations thereof; even intact tumour cells .

Preferably, the DCs are exposed to agents that switch the DCs from their default tolerance maintenance to a proinflammatory mode of action. This step is usually referred to as maturation. Maturation is performed by contacting the (differentiated from monocytes and antigen-pulsed) DCs with a maturation agent. The maturation agent can comprise a single maturation molecule or a combination of such molecules, including cell ex^¬ tracts. For example, the stimulation and/or maturation agent could comprise a natural or a synthetic agonist of a Toll-like receptor (TLR) including LPS, especially microorganisms dead or living, intact or fragmented (e.g. BCG) , resiquimod (R848), imi- quimod, poly(I:C), flagellin, or combinations thereof; in the presence of type I/II interferons, especially IFN-gamma, IL-4, GM-CSF, but also other pro-inflammatory cytokines. The matura^¬ tion agent can also comprise a cocktail of inflammatory cytokines that may include TNF-alpha, IL-1, prostaglandins, interferons but also other pro-inflammatory cytokines alone or to^¬ gether with TLR agonists. For maturation also the CD40 molecule on the DCs can be engaged by using synthetic or recombinant CD40L molecules, cells engineered to express CD40L molecules, T- cells or T-cell lines stimulated to express CD40L molecules, stimulatory monoclonal antibodies directed at CD40, or any other means of transmitting a signal via CD40 to the DC. Maturation can also be effected by danger signals derived from physical, chemical, microbial stress signals, or from necrotic or apop- totic cells releasing danger associated molecules such as heat shock proteins or other molecules signalling cellular destruction or distress.

Differentiation from monocytes, pulsing (loading) and matu^¬ ration (stimulation) may be done in subsequent steps of varying length and using various concentrations of the indicated agents, or in combination of some or all steps of DC manufacturing. Such steps and variations are well available for a person skilled in the art and can easily be adapted for the specific antigen to be applied to the cells/patient according to the present invention. (Jonuleit et al . (1997) Eur J Immunol 27: 3135-3142; Kalinski et al. (1999) Immunol Today 20: 561-567; Dohnal et al. (2009) J Cell Mol Med 13: 125-135; Boullart et al. (2008) Cancer Immunol Immunother 57: 1589-1597; Mills et al. (2009) BMC Cancer 9: 34; Bender et al . (1996) J Immunol Methods 196: 121-135; Thurner et al. (1999) J Immunol Methods 223: 1-15; Stift et al. (2003) J Clin Oncol 21: 135-142; Shankar et al. (2003) J Transl Med 1: 7; Rieser et al. (1997) J Exp Med 186: 1603-1608).

Preferably, stimulation and maturation of the DCs comprises exposure of the cells to an agonist of a Toll-like receptor, preferably LPS, especially dead or living intact bacteria, e.g. BCG, or bacterial fragments; resiquimod, imiquimod, flagellin, lipoteichoic acid, polylrC, double-stranded RNA, CpG oligoden- dronucleotids , alone or in combination; in the presence of proinflammatory cytokines (interferons, TNF-alpha, IL-1, IL-6, IL- 4, GM-CSF, etc.); synthetic or recombinant CD40L molecules or cells naturally or via genetic engineering expressing CD40L; material from necrotic cells or tissue as DAMP; and again all potential combinations thereof.

The central aspect of the present invention is the application of an inhibitor, which directly addresses and inhibits MK2 or JAK1. Various MK2 and JAK1 inhibitors are now available for a magnitude of purposes. However, these MK2 and JAK1 inhibitors have not yet been used in the production of antigen pulsed, ma- tured DCs for immune therapy. The MK2 and JAK1 inhibitor according to the present invention is preferably a small molecule.

In the fields of pharmacology and biochemistry, a small molecule is a low molecular weight organic compound, which is by definition not a polymer. The term small molecule, especially within the field of pharmacology, is usually restricted to a molecule that also binds with high affinity to a biopolymer such as protein, nucleic acid, or polysaccharide and in addition alters the activity or function of the biopolymer. The upper molecular weight limit for a small molecule is (approximately) 1000 Daltons, which allows for the possibility to rapidly diffuse across cell membranes so that they can reach intracellular sites of action.

Small MK2 inhibitor molecules can be natural or artificial. In a comparison of a series of MK2 inhibitors, only the molecule MK2-I3 showed satisfactory performance in blocking the activity of MK2 and was selected for further experiments (Figure 2) . Preferably, the MK2 inhibitor is selected from the group listed below. For the inhibition of JAK1 signalling, Ruxolitinib was used .

Examples of small molecule MK2 inhibitors are disclosed in WO 2011/041784 Al . Further examples of MK2 inhibitors are dis^¬ closed in WO 2011/073119 Al, especially the compounds described to have a pEC50 of at least 6.5 and a solubility of at least 20 mg determined according to the assay described in WO 2011/073119 Al . Further examples of MK2 inhibitors are disclosed in WO 2005/009370 A2, WO 2004/054505 A2 and WO 2004/058762.

In further examples of the present invention, the MK2 or JAK1 inhibitor may be a nucleobase oligomer containing a sequence complementary to at least 10 consecutive nucleotides of a nucleic acid sequence encoding a MK2 or JAK1 protein. In additional examples of the above methods, the MK2 inhibitor is a peptide containing the amino acid sequence of [L/F/I] XR [Q/S/T] L [S/T] [hydrophobic] (SEQ.ID.NO. 1), where the peptide contains no more than about 10 amino acids so that the molecular weight is 1000 Da or below (e.g., a peptide containing the amino acid sequence of LQRQLSI (SEQ.ID.NO. 2)). In further examples of the above methods, the MK2 inhibitor may be attached to a peptide that contains a covalently-linked moiety capable of translocating across a biological membrane (e.g., a moiety that contains a penetratin peptide or a TAT peptide) .

Preferred low molecular weight MK2 inhibitors to be used according to the present inventions are those disclosed in Schlap- bach et al . , Fut . Med. Chem. 1 (2009), 1243-1257 (especially those with the formulae 1-18, 21-83 disclosed in this article) .

Preferred JAK1 inhibitors are disclosed in Menet et al. (Prog. Med. Chem. 52 (2013), 153-223), especially those with the formulae 1-15 disclosed in this article.

Further preferred JAK1 inhibitors are disclosed recently in WO 2011/086053 A, WO 2012/085176 A, WO 2010/135650 A, WO 2011/028685 A, WO 2011/112662 A, US 2011/294826 A, WO 2011/045702 A, WO 2012/022265 A, WO 2012/054364 A, WO 2010/010187 A, and WO 2012/037132 A.

Those compounds can be used as defined above or e.g. as a pharmaceutical acceptable salt, pro-drug, stereoisomer, enanti- omer, or isoform thereof.

Preferably, the antigen the DCs are exposed to (pulsed) may be synthetic peptides, recombinant proteins, intact or lysed autologous or allogeneic tumour cells, synthetic RNA molecules or RNA derived from autologous or allogeneic tumour cells, recombinant viral or plasmid DNA molecules that code for an antigen .

According to a preferred embodiment of the present method, immature DCs are differentiated from monocytes or precursor cells thereof using cytokines, preferably by one or more of IL- 4, GM-CSF, IL-3, IL-13, type I/II interferons, especially IL-4 and GM-CSF, followed by pulsing with an antigen, wherein pulsing with the antigen is preferably conducted for 10 min to 4 h, more preferred for 20 min to 3 h, especially for 30 min to 2 h.

Preferably, immature DCs or precursor cells thereof are stimulated by cytokines followed by pulsing with an antigen and matured with a maturation agent for 1 to 20 h, preferably for 2 to 12 h, especially for 3 to 8 h.

According to a preferred embodiment, after pulsing with an antigen immature DCs are matured by a maturation agent selected from the group consisting of pathogen associated microbial patterns (PAMPs) , preferably lipopolysaccharide (LPS) , especially dead or living microorganisms or fragments thereof; lipoteichoic acid, resiquimod (R848), imiquimod, poly(I:C), double-stranded RNA molecules, microbial CpG oligonucleotides, flagellin, etc.. TLR-mediated maturation is preferably done in the presence of type I/II interferons, preferably pro-inflammatory cytokines, especially IFN-gamma, IL-4, or GM-CSF; a mixture of inflammatory cytokines including TNF-alpha, IL-1, or prostaglandins; synthetic or recombinant CD40L molecules, cells engineered to express CD40L molecules, T-cells stimulated to express CD40L molecules, stimulatory monoclonal antibodies directed at CD40; physical, chemical or microbial stress signals, danger associated molecules from necrotic or apoptotic cells, preferably cellular destruction or distress signalling molecules, especially heat shock proteins .

Optimised methods for generating DCs according to the present invention are disclosed in WO 2004/024900 Al, WO 2009/074341 Al, Felzmann et al. (2001) Cancer Letters 168: 145- 154; Lehner et al . (2001) Blood 98: 736-742; Felzmann et al. (2002) Onkologie 25: 456-464; Felzmann et al. (2003) Cytotherapy 5: 391-398; Felzmann et al (2003) Hum Immunol 64: 762-770; Felzmann et al . (2005) Cancer Immunol Immunother 54: 769-780; Hutt- ner et al. (2005) Cancer Immunol Immunother 54: 67-77; Wimpiss- inger et al. (2006) J Clin Oncol 24: 14585; Dohnal et al . (2007) Cytotherapy 9: 755-770; Dohnal et al. (2009) J Cell Mol Med 13: 125-135; Dohnal et al. (2009) J Cell Mol Med 13: 1741- 1750; Jurgens et al. (Blood) 114: 3235-3243; Traxlmayr et al . (2010) J Immunother 33: 40-52.

These methods may be applied with the present invention by including an MK2 or JAK1 inhibitor in the generation of the DCs in combination with the maturation agent for 1 to 20 h, preferably for 2 to 12 h, especially for 3 to 8 h.

A preferred stimulation and/or maturation cocktail comprises LPS, preferably LPS in combination with IFN-gamma and/or IL-4 and/or GM-CSF.

According to another aspect, the present invention also relates to a composition comprising

an MK2 or JAK1 inhibitor with a molecular weight of below 1000 Da, and

an agent from the group of pathogen associated microbial pattern (PAMP) molecules, preferably LPS, in combination with IFN-gamma and/or IL-4 and/or GM-CSF.

Besides using the rationale of the present invention for the generation of DCs, it is also possible to apply the MK2 or JAK1 inhibitor for immune therapy purposes directly to the patient. The combination of DC immunotherapy with the systemic application of one or more MK2 or JAK1 inhibitors is possible either in a healthy organism as a prophylactic measure or in a diseased organism as a therapeutic intervention. The MK2 or JAK1 inhibitor may be already present during the ex vivo manufacturing of the DCs. It may be applied to the patient together with the DCs; or it may be infused intravenously, injected intradermally or subcutaneously, or it may be applied directly into diseased tissue (tumour tissue, the site of a microbial infection) , or com^¬ binations thereof. The MK2 or JAK1 inhibitor may be applied only once or there may be repeated administrations, and also a continuous supply via any of the routes outlined above for single injections of the MK2 inhibitor.

Another route of administration is directly into diseased tissue; in case of a tumour intra-tumoural ; into the site of a microbial infection. This may be done alone or in combination with an application along the other routes described above.

Preferably, DCs produced in vitro from monocytes or other precursor cells by exposure to cytokines, e.g. IL-4 and GM-CSF;

Loaded with one or more synthetic, recombinant, or di^¬ rectly from diseased tissue derived antigen (microbial antigen, tumour antigen) ;

Exposed to one or more maturation stimuli derived from the group of PAMP or DAMP molecules, cytokine cocktails, or cells expressing CD40L naturally or by genetic engineering; and

In the presence of a molecule from the group of MK2 or JAK1 inhibitors, which may be present during the entire manufacturing procedure from the stage of the monocyte until the application to the patient; preferably from the exposure of the DCs to the antigen until application to the patient; most preferred from the addition of the maturation agents to the patient.

Furthermore, it is in principle only necessary to apply the MK2 or JAK1 inhibitor together with a PAMP without ex vivo manufactured, antigen pulsed, and matured DCs. The maturation agent/inhibitor combination may be applied via any of the routes for administration and according to administration schedule given for the application of the MK2 or JAK1 inhibitor alone. The maturation agent and MK2 or JAK1 inhibitor molecules will reach the diseased tissue where it interacts with resident DCs, which continuously take up material from surrounding dead cells but lack a danger signal to become activated and to modulate an immune responses, which the MK2 or JAK1 inhibitor further increases .

The immune modulatory molecules of the present invention may be targeted into diseased tissue using various strategies. They may be bound to functionalised nano-particles, natural or syn^¬ thetic polymers, or the likes, to proteins including but not limited to poly- or mono-clonal antibodies or other molecules such as transferrin, that bind to cellular receptors in the dis^¬ eased tissue. A combination of these methods may be used as well, e.g. the functionalised nano-particles or polymers carrying the immune modulatory molecules according to the present in^¬ vention and also a targeting molecule such as an antibody or ligand for a cellular receptor that directs the particles or polymers with its load into the diseased tissue.

Usually, at the site of administration or action of the inhibitor and PAMP, the necessary inflammation promoting cytokines are present. However, it may also be applied together with the composition according to the present invention. The same holds true for an antigen, especially if the patient is a tumour patient and the treatment is a tumour treatment. In this case, the (tumour) antigen is already there, the composition according to the present invention thereby safeguards an appropriate immune therapy at the site of the tumour. In other treatments, for ex^¬ ample in prophylactic treatments for microbial pathogens, the antigen may also be applied together with the composition of the present invention. Also, when the immune modulatory molecules described here reach the diseased tissue by the routes of administration and means outlined about, they will find the respective antigens - in addition to tumour antigens in tumour tissue, microbial antigens from an infection - as well as tissue resident or infiltrating immune cells, most importantly DCs, that may be manipulated according to the present invention.

According to the present invention, an antigen may be ap^¬ plied together with any type of adjuvant, including aluminium hydroxide, complete or incomplete Freund Adjuvant, or one or more of the molecules from the list above that is characterised by being a natural or synthetic agonist of a TLR, a cocktail of pro-inflammatory cytokines, a molecular or cellular agent triggering CD40 mediated signalling in DC, or a danger associated molecular pattern (DAMP) such as cellular material derived from dead cells or components thereof, e.g. heat shock proteins.

In another embodiment of the present invention, the DCs are applied separately from the MK2 or JAK1 inhibitor.

The present invention therefore also relates to a vaccination kit comprised of a natural or synthetic antigen (microbial, tumour) together with the adjuvant combination of maturation agent (LPS, R848 and the likes) and an MK2 or JAK1 inhibitor. Application routes and schedules may be as described above; all components of a vaccination kit may be applied via the same or via different routes, at the same or at different time points.

A preferred embodiment of the present invention relates to a composition comprising inflammation-modulating secreted or membrane bound molecules such as cytokines, especially interferon- gamma (INF-gamma) . Although such inflammation promoting molecules may be present in the patient to be treated, providing the inflammation-modulating molecule in the composition safeguards the presence of this molecule at the site of need.

Preferably, the MK2 inhibitor in the composition is selected from the group consisting of 2- (2-Quinolin-3-ylpyridin-4-yl) - 1,5,6, 7-tetrahydro-4H-pyrrolo- [3,2-c]pyridin-4-one, C2iHi_{6 4}0 · H₂0. The JAK1 inhibitor is selected from the group consisting of ruxolitinib .

In a preferred embodiment of the present composition, the PAMP is a Toll-like receptor (TLR) agonist, preferably LPS, re- siquimod (R848), imiquimod, poly(I:C), flagellin, CpG oligonucleotide molecules, dead or living microorganisms, or combinations thereof.

The preferred use of the composition according to the present invention is 100 ng/ml LPS (E. coli strain 0111:B4, Calbio- chem) , 2.5 pg/ml R848 (Santa Cruz Biotech.) or 2 pg/ml poly(I:C) (Sigma) 10 μΜ MK2-I3 or SB203580 (both from Sigma) .

An embodiment of the present invention is its use in the treatment of neoplastic disease, including brain cancer, espe^¬ cially glioblastoma multiforme (GBM) ; bone, connective tissue, muscle, Ewing' s sarcoma, etc.; carcinomas such as kidney cancer including Wilm's tumour, or liver cancer. Most preferably, in the treatment of cancer, the therapeutic combination of this invention - antigen-loaded DCs exposed to a maturation cocktail in the presence of the MK2 or JAK1 inhibitor - is applied at least 10 times and subsequently every 3 months as boost immunisations. Most preferred is a combined application into regional or other lymph nodes in combination with 1-5 applications into the dis^¬ eased tissue. The amount of DCs for each application is 1- 10 million.

In the most preferred method, monocytes are differentiated into immature DCs in the presence of IL-4 [317 U/ml] and GM-CSF [1000 U/ml] for 6 days at 37°C und 5% C0₂. The immature DCs are charged with 10 micro-g/ml tumour cell lysate for 2 hours. LPS [200 U/ml] and IFN-gamma [50 ng/ml] is added and the DCs are cultivated for another 6 hours.

The invention is further described by the following examples and the figures, yet without being restricted thereto.

Figure 1 depicts the three stages of a DCs mode of action: tolerance maintenance, immune stimulation, and immune suppres^¬ sion. IL-12 is released during the first day after encountering LPS. The signalling molecule MK2 is a key factor in switching the DC from its pro- into an anti-inflammatory mode of action. Blocking MK2 broadens the immune stimulatory time window by preventing the DCs switch into the immune suppressive phenotype.

Figure 2 TNF-alpha secretion profiles of LPS/IFN-gamma ac^¬ tivated DCs treated with Hsp25k-I (a), MK2-I3 (b) , MK2a-I (c) and SB 203580 (d) for 6 hours and 48 hours. The used concentration of the inhibitor in pg/ml/10⁶ cells is depicted on the x- axis, the y-axis shows the amount of secreted TNF-alpha in pg/ml .

Figure 3 shows that JAK1 and MK2 expression and MK2 phosphorylation is enhanced in LPS stimulated DCs. (a) Inflammatory and T_H1 or T_H17 in comparison to TH2 or Treg supporting gene clusters are shown derived from differential gene expression analysis of LPS/IFN-gamma matured human DCs in relation to un^¬ stimulated DCs over time, from 6 to 48 hours. The heat map is calculated on a log2 basis, (b) MK2 (ΜΆΡΚΆΡΚ2) protein expression kinetics after LPS stimulation of human (left blot) or mouse (right blot) DCs. (c) Phosphorylation of MK2 shortly after LPS stimulation of human DCs (upper left blot) and mouse DCs af- ter LPS (upper right blot), R848 (lower left blot) or poly(I:C) (lower right blot) treatment, (c) JAK1 protein expression kinetics after LPS stimulation of human DCs. hMK2 : human MK2, mMK2 : mouse MK2.

Figure 4 shows that MK2 deficient DCs increase IL- lalpha/p38 signalling, (a) TNF-alpha and IL-lalpha secretion kinetics as well as IL-lbeta, IL-6 and IL-23 secreted from T com^¬ pared to MK2^_/" DCs 24 hours after LPS activation. (b-c) TNF- alpha, IL-1 and IL-6 secreted from (b) MK2-I3 treated DCs after LPS, R848 or poly(I:C) activation or from (c) SB203580 treated DCs stimulated with LPS. Cytokines were measured 48 h after activation, (d-e) p38 phosphorylation of MK2-I3 treated LPS-DCs isolated from in vitro cultures supplemented with a blocking IL- lalpha antibody analysed by (d) western blotting and (e) p-p38 ELISA. OD values of p-p38 normalized to p38 protein measured after 6 h of LPS activation are shown, (f) MK2 and p38 phosphorylation of MK2-I3 treated IL-lalpha stimulated DCs. (g) IL-lbeta secretion from WT compared to MK2-/- LPS-DCs in the presence of a blocking IL-lalpha antibody. (h) Model showing MK2-regulated IL-lalpha/p38 signalling. Mean ± SEM is shown. *P < 0.05, ***P < 0.001 (Student's t-test) .

Figure 5 shows that MK2 deficient DCs prolong IL-12 secre^¬ tion and reduce IL-10/STAT3 signalling. (a) Kinetics of IL-12 secreted from WT compared MK2-/- LPS-DCs. (b) IL-12 secreted from MK2-I3 treated DCs 48 h after the activation with LPS, R848 or poly(I:C). (c) IL-12 secretion from WT vs. MK2-/- LPS-DCs in the presence of a blocking IL-lalpha antibody. (d-e) Erkl/2 phosphorylation of MK2-I3 treated LPS-DCs analysed by (d) west^¬ ern blotting and (e) p-Erkl/2 ELISA. OD values of p-Erkl/2 normalised to Erkl/2 protein measured after 6 h of LPS activation are shown, (f) Model showing MK2 -regulated IL-12 expression, (g) Kinetics of IL-10 secreted from WT compared MK2-/- LPS-DCs. (h) IL-10 secreted from MK2-I3 treated DCs 48 hours after LPS, R848 or poly(I:C) activation. (i) IL-10 secretion of WT vs. MK2-/- LPS-DCs isolated from in vitro cultures supplemented with a blocking IL-lalpha antibody, (j-k) STAT3 phosphorylation of MK2- 13 treated LPS-DCs isolated from in vitro cultures supplemented with a blocking IL-lalpha antibody analysed by (j) western blot^¬ ting or (k) p-STAT3 ELISA. OD values of p-STAT3 normalized to STAT3 protein measured after 6 h of LPS activation are shown. (1) Model showing MK2-regulated IL10/STAT3 signalling. Mean + SEM is shown. *P < 0.05 (Student's t-test) .

Figure 6 shows that MK2-/- DCs mediate T_H17 differentiation . (a-b) T_H17 cell priming capacity of ovalbumin (OVA) -peptide pulsed, MK2-I3 treated DCs activated with (a) LPS or R848 for 6 h or (b) LPS for 24 h. After 3 days of DC co-cultures with OVA- specific OT-II cells IL-17 producing cells were analysed in ELISPOT assays by (a) OVA-peptide and (b) OVA-peptide, LCMV- peptide and anti-CD3 re-stimulation. Spot number of IL-17 producing cells after OVA-peptide re-stimulation in one representa^¬ tive ELISPOT is shown on top right in the counted area. IL-17 producing cells in 100.000 cells isolated from DC/OT-II cell in vitro cultures are presented, (c-d) T_H17 T cell priming capacity of OVA-peptide pulsed MK2-/- LPS-DCs measured in co-cultures with OT-II cells supplemented with a blocking IL-lalpha antibody. IL-17 producing CD4+ OT-II cells are presented as (c) per^¬ centage in the dot plots and (d) cumulative results showing the number of IL-17+ cells in 100.000 cultured cells, (e) After immunization of OT-II mice with OVA-peptide pulsed LPS-DCs derived from MK2-/- or WT bone marrow T_H17 factors determining a specific polarization in CD4+ OT-II cells were analysed in draining lymph nodes (LN) . Anti-CD3 re-stimulated OT-II cells were analysed for intracellular cytokines. (f) The T_H17 transcription factor ROR- gammat and cytokine IL-17 vs. IL-10 are presented as percentage of CD4+ OT-II cells in the dot plots or (g) cumulative results (n=5 for each group) . Mean + SEM is shown. NS, not significant *P < 0.05, **P < 0.01 (Student's t-test).

Figure 7 shows that MK2-/- DCs mediate T_H17 differentiation . (a-b) T_H1 cell priming capacity of OVA-peptide pulsed, MK2-I3 treated DCs activated with (a) LPS or R848 for 6 h or (b) LPS for 24 h. IFN-gamma producing cells were analysed in DC co- cultures with OT-II cells in ELISPOT assays by (a) OVA-peptide and (b) OVA-peptide, LCMV-peptide and anti-CD3 re-stimulation. Spot number of IFN-gamma producing cells after OVA-peptide re- stimulation in one representative ELISPOT is shown on top right in the counted area. IFN-gamma producing cells in 100.000 cells isolated from DC/OT-II cell in vitro cultures are presented, (c- d) T_H1 factors measured in co-cultures of MK2-I3 treated, 6 h ac^¬ tivated LPS-DCs with OT-II cells. (c) IL-12Rbeta2 expressing CD4+ OT-II cells shown as percentage in the plot. Cumulative re- suits are presented as absolute cell numbers in DC/OT-II cell co-cultures. (d) IL-12 secreted in the co-cultures. (e-f) T_H1 cell priming capacity of MK2-/- LPS-DCs measured in co-cultures with CD4+ OT-II cells supplemented with a blocking IL-lalpha antibody. IFN-gamma producing OT-II cells are presented as (e) percentage in the dot plots or (f) cumulative results, (g-i) After immunization of OT-II mice with OVA-peptide pulsed LPS-DCs derived from WT or MK2-/- bone marrow TH1 factors were analysed in draining lymph nodes (LN) . (h) The TH1 transcription factor Tbet or cytokine IL-2 vs. IL-10 are presented as percentage of OT-II cells in the dot plot or (i) cumulative results (n=5 for each group) . (j-k) Stimulatory potential of LPS-DCs derived from WT or MK2-/- bone marrow in co-cultures with CD8+ OT-I cells. Proliferation of CD25+ OT-I cells is presented as (j) percentage in the dot plots or (k) cumulative results (n=7) by calculating the absolute number of CFSElow OT-I cells. (1-n) Killer cell ac^¬ tivity determined in WT mice immunized with OVA 257-264 (SIIN- FEKL) and OVA 323-399 pulsed WT or MK2-/- LPS-DCs. Reduction of CFSEhigh OVA (SIINFEKL) compared to CFSElow control peptide loaded target splenocytes is presented as (m) percentage in the histograms or (n) cumulative results (n=5 for each group) . Mean ± SEM is shown. *P < 0.05, **P < 0.01, ***P < 0.001 (Mann-Whitney U or Student's t-test) .

Figure 8 shows that MK2 deficient DCs impair Treg differentiation, (a-b) Treg priming capacity of OVA-peptide pulsed, MK2- 13 treated DCs activated with (a) LPS or R848 for 6 h or (b) LPS for 24 h. IL-10 producing cells were analysed in DC co-cultures with OT-II cells in ELISPOT assays by (a) OVA-peptide and (b) OVA-peptide, LCMV-peptide and anti-CD3 re-stimulation. Spot number of IL-10 producing cells after OVA-peptide re-stimulation in one representative ELISPOT is shown on top right in the counted area. IL-10 producing cells in 100.000 cells isolated from DC/OT-II cell in vitro cultures are presented, (c-d) Treg priming capacity of MK2-/- LPS-DCs measured in co-cultures with CD4+ OT-II cells supplemented with a blocking IL-lalpha antibody. IL- 10 producing IL-2+ OT-II cells are presented as (c) percentage in the dot plots or (d) cumulative results, (e-g) WT Ly5.1 mice were immunized with CD4+ OT-II cells together with OVA-peptide pulsed LPS-DCs derived from MK2-/- or WT bone marrow. The negative control group was transplanted with OT-II cells alone. On day 3 the draining lymph nodes (LN) were analysed for intracellular FOXP3 expression in activated CD25+ cells within the transplanted Ly5.2+ OT-II cell or the endogenous Ly5.1+ CD4+ T cell population and presented as (b) percentage in the dot plots top right or (c) cumulative results (n=5 for each group) . Mean ± SEM is shown. NS, not significant, *P < 0.05, **P < 0.01 (Student' s t-test) .

Figure 9 shows that MK2 deficient tissue derived DCs mediate inflammation, (a) T_H1 and (b) T_H17 priming capacity of CDllc+ splenic DCs treated with MK2-I3 before LPS activation. (a) IFN- gamma and (b) T_H17 producing cells were analysed in OVA-peptide charged DC co-cultures with OT-II cells in ELISPOT assays by OVA-peptide, LCMV-peptide and anti-CD3 re-stimulation. Cytokine producing cells in 100.000 cells isolated from DC/OT-II cell in vitro cultures are presented. (c-e) WT mice were transplanted with CD4+ OT-II cells followed by intra-dermal injection of OVA- peptide/LPS with or without MK2-I3 (n=4) . On day 7 draining LNs were re-stimulated with OVA-peptide or anti-CD3 and analysed for (d) IFN-gamma release by ELISPOT. (e) IL-10 production of OVA- peptide stimulated LN cells isolated from mice injected with a blocking anti-IL-lalpha antibody in addition to MK2-I3. Spot number of cells producing cytokines after OVA-peptide re- stimulation in one representative ELISPOT is shown on top right in the counted area. IFN-gamma and IL-10 producing cells in 100.000 cells isolated from draining LNs are presented. Mean ± SEM is shown. NS, not significant, *P < 0.05, **P < 0.01 (Student' s t-test) .

Figure 10 shows that the inhibition of MK2 activity can be superior over a blockade of MK2 transcription to support DC- mediated CD8+ T cell expansion. (A-B) Sixteen hours prior to LPS/ IFN-gamma activation human monocyte derived DCs were trans- fected with MK2-specific siRNA (MK2-) , non-targeting control siRNA (NTC) or left untreated (UT) . (A) Twenty-four hours after supplementing the siRNA treated DC cultures with LPS/IFN-gamma cell viability and IL-10 secretion was measured by flow cytometry (left panel) and ELISA of supernatants (right panel), respectively. (B) Six hours after supplementing the siRNA treated DC cultures with LPS/IFN-gamma DCs were co-cultured with CFSE labeled, allogeneic CD8+ T cells isolated from peripheral blood by magnetic cell sorting. On day 6 CFSE diluted in proliferating CD8+ T cells was measured by flow cytometry. Shown is the cell number of proliferating T cells per cell culture well at a 1:1 and 1:4 DC : T cell ratio. (C-D) Human DCs were stimulated with LPS /IFN-gamma in the presence of MK2-I3 kinase inhibitor or DMSO solvent referring to the vehicle control. (C) Twenty-four hours after supplementing the DC cultures with LPS/IFN-gamma cell viability at 0,5 micro-g /ml MK2-I3 and dosage dependent IL-10 se^¬ cretion was measured by flow cytometry (left panel) and ELISA of supernatants (right panel), respectively. (D) Six hours after LPS/IFN-gamma activation in the presence of 0,5 micro-g /ml MK2- 13 or vehicle control DCs were co-cultured with CFSE labeled, allogeneic CD8+ T cells isolated from peripheral blood by magnetic cell sorting. On day 6 CFSE diluted in proliferating CD8+ T cells was measured by flow cytometry.

Figure 11 shows that inhibition of JAK1 activity and JAK1 gene knock down sup-ports DC-mediated TH1 immune responses. (A- B) DC isolated from conditional knock out mice having a mutated inactive JAK1 gene in DCs (JAK^DeltaDC, n = 3) and wild-type litter- mate controls (n = 3) were stimulated with LPS and analysed for IL-12 secretion and their capacity to polarize CD4+ T cells towards TH1 immunity. (A) IL-12 secreted over 24 h of LPS stimulation. (B) Four hours after LPS maturation 323-399 OVA-peptide loaded DCs generated with bone marrow from knock out and wild- type control mice were co-cultured with ovalbumin-specific CD4+ cells using whole splenocytes from OT-II mice. On day 3 spleno- cytes were re-stimulated with Ova-peptide, gp61 control peptide or a-CD3 and analysed for IFN-gamma release by ELISPOT assays. Spot number referring to IFN-gamma producing cells after 323-399 OVA-peptide re-stimulation in one representative ELISPOT is shown on top right in the counted area. IFN-gamma producing cells in 100.000 cells isolated from in vitro priming cultures are presented. (C) Four hours after LPS activation in the presence of 1 and 10 micro-M Ruxolitinib or vehicle control OVA 257- 264 (SIINFEKL) -loaded DCs were co-cultured with CFSE labelled CD8+ T cells isolated from OT-I mice by magnetic cell sorting. On day 3 CFSE diluted in proliferating CD8+ T cells was measured by flow cytometry. Mean ± SEM is shown. *P < 0.05, ***p < 0.001 (Student's t-test) .

Figure 12 shows the effects of MK2 inhibition in human DCs. A. This depicts a Western blot that demonstrates that the phos- phorylation of HSP27, a down-stream target of MK2, is prevented in the presence of MK2-I3; the effect of MK2-I3 on the phosphorylation of p38, which is upstream of MK2, is not affected by MK2-I3. B. In a stimulation culture of DCs and T-cells, the secretion of IL-12 in the presence of 10-30 μΜ MK2-I3 is greatly enhanced on days 1 & 2; at later time points the effect becomes weaker. C & D. During the DC maturation, treatment of DCs with 10-30 μΜ MK2-I3 results in a delay of the onset of IL-10 secretion (C) , and a clearly enhanced secretion of IL-12 (D) .

Figure 13 shows that MyD88 -dependent activation of the p38/MK2 axis balances DC-mediated inflammation. P38 drives the secretion of pro- and anti-inflammatory factors, such as IL- lalpha and IL-10. MK2 , which acts as a negative regulator of primary LPS- and secondary IL-lalpha-driven p38 signalling, therefore dampens p38-mediated IL-1 but also IL-10 secretion. However decreasing IL-10 secretion is resumed by secondary IL- 10/JAK/STAT3 signalling leading to a dominant anti-inflammatory DC phenotype. Hence, inhibition of MK2 strengthens IL-lalpha/p38 but down-modulates IL-10/JAK/STAT3 signalling. MyD88 : Myeloid differentiation primary response gene 88, IRAK: IL-1R associated kinase, TRAF: TNF receptor associated factor, MAPKK: MAPK kinases, MAPKAPK: MAPK-activated protein kinase.

Figure 14 schematically represents the functional linkage of the MAP kinase pathway and the JAK/STAT pathway (a); and shows at which steps the MK2 and JAK1 inhibitors interfere with sig^¬ nalling along the MAP kinase and JAK/STAT pathways (b) .

Figure 15 shows ICP inhibition (ICPI) : MK2 and JAK1 interfere with signalling inside a cell; the other ICP inhibitors block the effector molecules at the end of the signalling cascade .

EXAMPLES FOR MK2 or JAK1 INHIBITION:

In accordance with the time-dependent phenotypic changes of maturing DCs, the present examples show the effectiveness of stimulating DCs in the presence of an antigen, a cocktail of maturation agents, and an MK2 or JAK1 inhibitor. It is further shown in the present examples that LPS exposure causes accumulation of MK2 or JAK1 protein in DCs up to approximately one day following stimulation. At that time the anti-inflammatory IL- 10/STAT3 signalling molecules are strongly induced. Based on this observation the potential regulatory function of MK2 in LPS-activated DCs was analysed. MK2-mediated regulation of effector T cell functions is primarily executed via negative feed^¬ back signalling on p38 and positive cross-regulation of ERK1/2 activity. Down-modulation of p38 predominantly impairs the autocrine IL-l/p38 axis, which terminates I L-1 and I L-12 secretion. In addition, secondary IL-10/STAT3 signalling is enhanced depending on I L-lalpha secreted from DCs. Thus, MK2 inhibits T_H1 and T_H17 effector mechanisms and directs the differentiation of CD4+ naive T cells towards Treg cells. Based on the findings that MK2 is a key regulator of inflammatory mechanisms active in DCs, also a mechanism for the present method for stimulation of DCs and its effectiveness for the treatment of diseases, espe^¬ cially tumour diseases, is revealed by the present invention.

MATERIALS AND METHODS

Mice and human sources for DC preparation

Ly5.1 {B6.SJL-PtprcaPepcb/BoyJ) or Ly5.2 (C57BL/6J) and OT- I (C57BL/6-Tg (TcraTcrb) llOOMjb/Crl) or OT-II (C57BL/6-

Tg (TcraTcrb) 425Cbn/Crl) transgenic mice, purchased from the Research Institute for Laboratory Animal Breeding, University of Vienna (Himberg, Austria) were housed at the animal care unit of the Department of Pharmacology, Medical University of Vienna, Austria. The in vivo mouse experiments were approved by the institutional review board of the Medical University of Vienna. Dendritic cells were generated from MK2 deficient (Kotlyarov et al., Nat. Cell. Biol. 1 (1999), 94-97) and wild-type C57BL/6 mice as previously described (Huttner et al., Cancer Immunol. Immunother. 54 (2005), 67-77) . Briefly, murine bone marrow cells were harvested from femur and tibias and re-suspended in IMDM medium (GIBCO) supplemented with 10% foetal calf serum (PAA), non-essential amino acids, Penicillin/ Streptomycin (GIBCO) and 0.0002% beta-Mercaptoethanol (Sigma) . Bone-marrow cells were plated at a density of 0.3-0.5xl0⁶ cells/ml cm² with 50 U/ml recombinant murine IL-4 (eBioscience) and 1500 U/ml recombinant murine GM-CSF (BD Pharmingen) . For in vivo applications and in vitro assays DCs were pulsed with of the MHC-I peptide OVA 257-264 (SIINFEKL ( SEQ . ID . NO .7 ) , H2-K^b) and/or the MHC-II peptide OVA 323-399 (both from Bachem) for 1 hour prior to maturation. Then peptide-pulsed DCs were stimulated with 100 ng/ml LPS (E. coli strain 0111 :B4, Calbiochem) for 4 hours. The use of human peripheral blood from healthy adult volunteers was approved by the institutional review board of the St. Anna Chil^¬ dren's Cancer Research Institute and conducted according to the Declaration of Helsinki. Monocytes and T cells were isolated as described previously (Traxlmayr et al., J. Immunother. 33 (2010), 40-52) . Briefly, leukocytes were collected from healthy volunteers using an Amicus leukocyte apheresis device (Baxter) . Monocytes and T cells were fractionated from leukocyte apheresis product using the Elutra cell separator (Gambro) following the instructions of the manufacturer. Monocytes were differentiated into DCs following a previously optimized protocol (Dohnal et al., J. Cell. Mol. Med. 13 (2009), 125-135), using CellGro DC medium (Cellgenix) supplemented with 1000 U/ml recombinant human GM-CSF and 300 U/ml recombinant human IL-4 (both from Peprotec) . For cytokine profiling and in vitro proliferation assays DCs were transfected with 100 pmol/10⁶ DCs with MK2-specific (siRNA pool: cgaaugggccaguaugaau (SEQ. ID. NO.3) , guuauacaccguacuaugu (SEQ. ID. NO.4) , ggcaucaacggcaaaguuu ( SEQ . ID . O .5 ) , ccaccagcca- caacucuuu (SEQ. ID. NO.6) ) or non-targeting control (NTC) siRNA (all reagents from Dharmacon) 16 hours prior to the stimulation with 1000 ng/ml LPS (Calbiochem) and/or 1000 U/ml human IFN- gamma (Imukin, Boehringer Ingelheim Austria) . For MK2, p38 or JAK1 inhibition DCs were treated with 10 micro-M MK2-I3 (2- (2- Quinolin-3-ylpyridin-4-yl ) -1, 5, 6, 7-tetrahydro-4H-pyrrolo- [3,2- c] pyridin-4-one; C₂iH₁₆N₄0 · H₂0) , the p38 inhibitor SB203580 (both from Sigma) or the JAK1 inhibitor Ruxolitinib 30 min prior LPS stimulation for 4 hours and further phenotyped or co- cultured with CD4⁺ OT-II cell. IL-lalpha blocking experiments were performed with 100 ng/ml anti-mouse IL-lalpha or Armenian hamster IgG isotype control antibodies (eBioscience) .

Gene expression and protein phosphorylation

Gene expression profiling was performed as previously described using human DCs stimulated with LPS and IFN-gamma (GEO: GSE11327) (Dohnal et al., J. Cell. Mol. Med. 13 (2009), 1741- 1750) . Protein expression and phosphorylation were analyzed in LPS and/or IFN-gamma stimulated DCs lysed in RIPA buffer supple^¬ mented with protease and phosphatase inhibitors (Roche Applied Science) and subsequently diluted with SDS sample buffer. Pro- tein lysates derived from 10⁶ DCs were separated by electrophoresis using 10% acrylamide gels and then transferred onto nitrocellulose membranes (Whatman) . Membranes were probed with the following antibodies: MK-2, MK-2 phosphorylated at Thr334, p38, p38 phosphorylated at Thrl80/Tyrl82, p44/42 MAP kinase (ERK1/2), p44/42 MAPK (ERK1/2) phosphorylated at Thr202 /Tyr204 , STAT3 , STAT3 phosphorylated at Tyr705, HSP27, HSP27 phosphorylated at Ser82, (all from Cell Signalling) and GAPDH (Ambion) followed by peroxidase- or DyLight 800-conjugated anti-rabbit or anti-mouse IgG (Pierce) .

CD4⁺ T cell and DC phenotyping.

Ly5.1 C57BL/6 and OT-II mice were immunized close to the inguinal lymph nodes with 5xl0⁶ SIINFEKL ( SEQ . ID . O .7 ) pulsed, LPS-stimulated DCs with or without 10⁶ OT-II cells, which were purified by negative depletion using CD4⁺ MACS (Miltenyi) . On day 3 T cells were isolated from in vitro cultures or lymph nodes and analysed directly for the expression of transcription factors by intracellular staining. Further cells were re-stimulated with PMA/ionomycine (Sigma) treatment together with Golgi-plug or Golgi-Stop (BD Biosciences) and analysed for intracellular cytokines. The following antibodies were used for transcription factor and cytokine staining: Anti-mouse CD4 - PerCP (clone RM4- 5, BD Pharmingen) , Anti-mouse Ly5.2 - FITC (clone 104), valpha2 TCR-PE (clone B20.1), CD25 - PE-Cy7 (clone PC61.5), Foxp3 - eFlourTM 450 (clone FJK-16s), RORgammat - PE (clone AFKJS-9) , T- bet - PerCP-Cy5.5 (clone 4B10), IL-2 - eFlour® 450 (clone JES6- 5H4), IL-10 - Alexa Flour® 647 (clone JES5-16E3), IL-17A - PE- Cy7 (clone 17B7), IFN-gamma PE (clone XMG1.2, all from eBio- science) . T cell and DC supernatants were analysed using the Flow Cytomix system (eBioscience) following the manufacturer's protocol. FACS acguisition was performed on a LSR 2 flow cytome- ter (BD Biosciences) . Further analysis was performed using FlowJo software Version 6.7.1 (Treestar) .

T cell proliferation assay.

Murine OT-II or OT-I splenocytes and human peripheral blood leucocytes from Elutra products were enriched for CD4⁺ or CD8⁺ T cells by negative depletion using MACS (Miltenyi) . Both mouse and human T cells were labelled with a proliferation tracker (CFSE, Sigma) at a final concentration of 7 micro-M. Mouse T cells (50,000/200 μΐ) were co-cultured with OVA 257-264 (SIIN- FEKL) loaded LPS-stimulated DCs (25,000/200 micro-1) and ana^¬ lysed after 3 days. Human T cells (50,000/200 μΐ) were co- cultured with allogeneic LPS-stimulated DCs (25,000/200 μΐ) and analysed after 6 days for CFSE. The absolute number of proliferating T cells was assessed by CFSE dilution using the Trucount™ system (BD Biosciences) and the following antibodies: Anti-mouse CD4 - PerCP-Cy5.5 (clone RM4-5) , CD8a - APC-eFlour^® 780 (clone 53-6.7), CD25 - PE-Cy7 (clone PC61.5, all from eBioscience) , anti-human CD8 APC-Cy7 (clone SK-1, BD Biosciences), anti-human CD25 - Alexa Fluor^® 647 (clone MEM181, AbD Serotec) .

In vitro and in vivo ELISPOT

For in vivo experiments CD4+ OT-II transplanted wild type mice were immunized with a mixture of LPS (10 micro-g/mouse) / OVA 323-399 peptide (2 g/mouse) / MK2-I3 (20 ug/mouse)/ anti-IL- lalpha (400 ng/mouse) . Control mice were injected with vehicle (DMSO, Sigma) and Armenian hamster IgG isotype control antibod^¬ ies (eBioscience) . 100.000 cells from DC/OT-II splenocyte co- cultures or draining lymph node cells from immunized mice were re-stimulated with 1 micro-g/ml OVA 323-399 peptide or LCMV- peptide 61-80 (AnaSpec) or 5 micro-l/ml anti-CD3/CD28 Dynabeads (Gibco) in 96-well MultiScreenHTS-IP Filter Plates (MSIPS4W10, Millipore) using CTL Test serum-free medium (C.T.L.) . IL-17, IFN-gamma and IL-10 ELISPOTs were performed according to the manufacture's protocol (MAbtech) using BCIPO/NBT Liquid Substrate System (Sigma) .

Cytotoxic assay in vivo.

Killing of target cells was performed according to a previously described protocol (Simma et al., Cancer Res. 69 (2009), 203-211) . Briefly, mice were immunized close to the inguinal lymph nodes with OVA 257-264 (SIINFEKL) and OVA 323-399 peptide pulsed, LPS-stimulated DCs. Syngeneic target cells were prepared by combining splenocytes loaded with 2.5 μΜ CFSE and l g/ml of OVA 257-264 with splenocytes loaded with 0.25 micro-M CFSE and lpg/ml mTRP 2181-188 (VYDFFVWL (SEQ. ID. NO.12) ; H2 -K^b, derived from murine tyrosine-related protein-2; Bachem) control peptide. On day 4, 10⁷ target cells were administered by tail vein injec- tion. Six hours later draining lymph nodes were analysed for CFSE positive target cells. Reduction of OVA 257-264 pulsed cells (%) = [1 - (% CFSE^higl7 % CFSE^l0W) ] x 100 was calculated and expressed as killing (%) in relation to PBS injected control mice .

Western Blot

After 6 hours stimulation and co-cultivation with the maturation cocktail containing the MK2 inhibitor, DCs were harvested and centrifuged for 7 minutes at 4°C at 460g. The cells were then re-suspended in Lysis buffer (50% PBS, 50% 2X SDS Loading Buffer) at a concentration of 30,000 cells/μΐ and incubated for 10 min at 95°C. Debris was removed by centrifugation for 10 min at 4°C, in a microfuge at full speed and frozen at -80°C.

For the Western blot, 6 hours matured DCs with and without inhibitor were thawed and plated in DC medium (Cellgro) with GM- CSF and IL-4, supernatant and cells was harvested at different time points .

In order to detect, HSP27, p38 and GAPDH, the DCs proteome was separated using first 10% stacking and then a 10% separating acrylamide gel. The protein samples were slowly thawed on ice and loaded (5 μΐ = 150, 000 DCs) onto the gel. To determine the size of separated proteins, the gel was also loaded with 5 μΐ marker. The gel was first run at 30 mA const, in lx Laemmli Buffer until the samples reached the separating gel, and then it was run at 60 mA const, until the marker was well separated.

Successful blotting on nitrocellulose membrane was controlled by Ponceau S staining for 5 min at RT . Proteins were probed with the following antibodies: pHSP27, HSP27, p-p38, p38 from Cell Signalling and GAPDH from Ambion, followed by peroxidase- or DYLight 800-conjugated anti rabbit or anti mouse IgG.

Statistical analysis.

Two-tailed paired and unpaired student' s t-test as well as Mann-Whitney U was used to determine exploratory P values using GraphPad Prism version S.02 for Windows (GraphPad Software, San Diego, CA) . All data are given as mean ± SEM.

Accession code.

Gene expression omnibus (GEO): GSE11327 RESULTS

Induction of MK2 and JAK1 in DCs during a late phase of anti^¬ inflammatory gene expression

LPS is known to induce a variety of immunologically active genes enabling DCs to crosstalk via membrane bound molecules or soluble cytokines in a pro- but also in an anti-inflammatory mode. As recently described, human monocyte derived DCs were stimulated with LPS together with IFN-gamma, which strongly induced pro-inflammatory genes. Indeed, robust induction of IL-1, IL-12, TNF and IL-6 was observed over a time period from 6 to 48 hours after LPS exposure. Moreover, only after 12 hours DCs acquired anti-inflammatory properties as indicated by the up- regulation of IL-10, GM-CSF {CSF-2) , G-CSF (CSF-3) , TSLP and STAT3, a downstream signalling molecule of IL-10 in the JAK/STAT cascade (Fig. 3a) . A similar transcription profile hinted at MK2 (MAPKAPK2) and JAK1 as a critical factor in DC-mediated antiinflammatory mechanisms, since MK2 and JAK1 showed peak expression after 24 hours of LPS/IFN-gamma stimulation. In order to exclude IFN-gamma driven induction of MK2, human and mouse DCs were initially stimulated with LPS alone. LPS, as a TLR4 agonist, and not IFN-gamma appeared to be the dominant signal for the up-regulation of the MK2 protein as well as for the induction of the p38/MK2 signalling pathway shown by the phosphorylation of MK2 in human and mouse DCs (Fig. 3b-c) . Among other TLR ligands, R848 (TLR7/8) but not poly(I:C) (TLR3) induced MK2 phosphorylation (Fig. 3c) . Thus, MK2 is predominantly activated via the MyD88 dependent pathway of TLR signalling; since TLR3 molecules use Toll/Interleukin-1 receptor (TIR) domain- containing adaptor molecules for signal transduction.

Immediate MK2 phosphorylation after 30 minutes of LPS and R848 stimulation showed its essential role in early TNF-alpha translation and therefore supporting the contribution of MK2 to inflammation. Up-regulation of MK2 protein expression during the late phase of DC maturation mediates a time-delayed anti^¬ inflammatory function, as shown below.

DCs require MK2 to attenuate IL-lalpha/p38 signalling

Cytokines released from DCs play an essential role in the differentiation of CD4⁺ T cells. Thus MK2 regulated cytokines in DCs and their role in MAPK signalling were initially explored (Fig. 4) . While cell viability and surface marker expression on LPS-activated (LPS) -DCs was only slightly affected, cytokine se^¬ cretion was significantly different under MK2 deficient conditions in DCs. MK2^{_ ~} compared to wild type LPS-DCs secreted significantly lower levels of TNF-alpha as it was described for MK2^~ ^_ splenocytes or macrophages (Fig. 4a) . In contrast MK2^{_ ~} LPS- DCs increased IL-lalpha secretion up to 3-fold from 6 to 24 hours after LPS activation. As signalling via p38 drives the expression of T_H17 supporting cytokines, IL-6 and IL-lbeta which, as IL-lbeta, were secreted significantly higher from MK2^{_ ~} LPS- DCs, were further analysed (Fig. 4a) . IL-23 was not affected. By blocking MK2 activity using the MK2-I3 inhibitor again decreased TNF-alpha and increased IL-lalpha and IL-lbeta secreted from LPS- and R848-activated DCs was observed (Fig. 4b) . In response to poly(I:C) inhibition of MK2 only slightly affected cytokine expression. IL-lbeta was reduced indicating a different function of MK2 in TLR3-mediated signalling. The specificity of MK2 blockade with MK2-I3 was shown by the inhibition of Hsp27, the direct downstream target of MK2. In contrast to the inhibition of MK2, a blockade of the upstream signalling molecule p38 strongly reduced IL-lalpha and IL-6 secreted from LPS-DCs (Fig. 4c) . However, IL-lbeta secretion was increased under p38 deficient conditions.

A proposed negative effect of MK2 on p38-mediated induction of IL-1 was further investigated. MK2-I3 treated DCs strongly increased p38 phosphorylation shortly, starting from 15 min, after LPS activation (Fig. 4d-e) . By blocking IL- lalpha-binding on DCs up to 6 hours after LPS activation enhanced secondary IL- lalpha/p38 signalling by blocking MK2 was impaired. As for LPS, increased p38 signalling was observed in response to IL-lalpha when MK2 activity was blocked (Fig. 4f) . Further it could be demonstrated that the increase of IL-lbeta secretion from MK2^{_ ~} LPS-DCs was impaired by IL-lalpha inhibition (Fig. 4g) .

This observation identifies MK2 as a negative feedback regu^¬ lator of primary LPS/p38 and secondary IL-lalpha/p38 signal transduction, which prevents DCs from secreting excessive IL-1 (Fig. 4h) . Since IL-lbeta secretion is not triggered by the MyD88/p38 axis an additional pathway seems to be involved in the regulation of IL-lalpha-mediated IL-lbeta expression. MK2 positively cross-regulates Erkl/2 signalling and abbreviates IL-12 secretion in DCs

MAPK signalling is described to regulate T_H1 immunity. Thus, negative feedback signalling of MK2 on MyD88 dependent p38 signalling guided us to investigate the influence of MK2 on T_H1 factors. In the first 6 hours of LPS-driven DC maturation MK2 pro^¬ motes the secretion of the T_H1 polarizing cytokine IL-12 (Fig. 5a) . However, with proceeding maturation the decline of secreted IL-12 was less abundant in DCs lacking MK2. So yet higher IL-12 levels were detected 48 hours after LPS-activation in the super- natants of MK2-I3 treated LPS-DCs (Fig. 5b). R848 and poly(I:C) activated DCs showed no difference in IL-12 secretion in the ab^¬ sence of active MK2 compared to WT . As for IL-lbeta the role of secondary IL-lalpha signalling for IL-12 production was investigated. IL-12 secreted from DCs deficient for MK2 was diminished when IL-lalpha signalling was blocked (Fig. 5c) .

The interplay of p38 and Erkl/2 modulates T_H1 differentiation by regulating IL-12 expression. In contrast to p38, inhibition of MK2 led to a strong decline of LPS-induced ERK1/2 signalling, which is described to down-modulate T_H1 immunity (Fig. 5d-e) . Thus, MK2 is considered as a molecular switch in MAPK signalling by regulating p38 and Erkl/2 activity and, as a consequence, IL-12-mediated T_H1 cell differentiation (Fig. 5f) .

DCs require MK2 to increase IL-10/STAT3 signalling depending on IL-lalpha

Having investigated the modulating effect of MK2 on pro^¬ inflammatory cytokines there was further interest in possible MK2-mediated anti-inflammatory mechanisms, such as the IL- 10/STAT3 signalling cascade. A strong decline of IL-10 secreted from MK2^{_ ~} compared to wild type DCs was observed in response to LPS (Fig. 5g) . Further IL-10 was reduced in MK2-I3, but also SB203580, a p38 inhibitor, treated DCs up to 48 hours after LPS or - to a lesser extent - R848 activation (Fig. 5h) . As for IL- lalpha or IL-12, poly(I:C) activation did not affect IL-10 expression. An essential function of IL-lalpha was already shown in MK2-mediated cytokine regulation. Thus, autocrine IL-lalpha was again blocked, which restored IL-10 secretion from MK2^{_ ~} LPS-DCs (Fig. 5i) . In addition a down modulation of STAT3 activ- ity was observed when MK2 was inhibited, which could also be restored upon blocking of IL-lalpha-binding to DCs (Fig. 5j-k) . Notably the blockade of IL-lalpha secreted from LPS-DCs also re^¬ duced STAT3 signalling, pointing at a dual function of autocrine IL-lalpha. Thus, IL-lalpha either promotes or blocks IL- 10/STAT3-mediated anti-inflammatory mechanisms depending on MK2 activity (Fig. 51) . Increased MK2-mediated secondary IL-lalpha feedback signalling predominantly blocks IL-10/STAT3 signalling.

MK2 attenuates DC-driven T_H17 cell expansion

The increase of T_H17 promoting cytokines released from MK2 deficient DCs lead to investigate T_H17 responses triggered by DCs. DCs in response to TLR4 and TLR7/8 signalling were analysed for their potential to differentiate CD4 cells towards T_H17 cells (Fig. 6a-b) . OT-II splenocytes were enriched 2-fold for ovalbumin (OVA) -specific IL-17 secreting cells in in vitro cultures with MK2-I3 treated LPS-DCs pulsed with OVA-peptide (Fig. 6a) . The same trend was observed for R848 activated DCs, but without any significance. When in vitro primed OT-II cells were re- stimulated with LCMV-peptide, which were used as a control- peptide, no IL-17 spots were detectable in the ELISPOT assays. Differential gene expression of MK2 in LPS-DCs over the time further lead to exploration of the stimulatory potential of DCs that were activated for 24 hours when MK2 showed peak expression (Fig. 3a) . As in in vitro cultures with 6 hours activated LPS- DCs, more IL-17 producing OT-II cells were detected after ovalbumin re-stimulation when MK2 was blocked in DCs (Fig. 6b) . Compared to 6 hours matured DCs an even 5-fold increase of OVA- specific T_H17 cells was observed indicating MK2 as strong modulator of T_H17 responses triggered at 24 hours after DC activation. Notably 24 hours matured DCs induced a stable T_H17 phenotype in OT-II cells, which was shown by the detection of IL-17 producing cells after control-peptide stimulation without boosting the T_H17 cells with OVA peptide.

IL-lalpha was revealed as one important factor in MK2- mediated control of T_H17 immunity. Like MK2-I3 treated LPS-DCs, also MK2^{_ ~} LPS-DCs showed increased priming potential of T_H17 cells in co-cultures with OT-II cells (Fig. 6c-d) . Inhibition of IL-lalpha signalling in the in vitro cultures again decreased the number of IL-17 producing OT-II cells. Next the impact of MK2 on the induction of T_H17 cells in vivo was tested. By immunising OT-II mice with OVA-pulsed LPS- DCs, T_H17 cells among OVA-specific CD4⁺ OT-II cells isolated from draining lymph nodes were analysed (Fig. 6e) . Activated CD4⁺ OT- II cells expressing the Valpha2⁺ T cell receptor were strongly accumulated in draining lymph nodes after the injection of LPS- DCs . In immunised OT-II mice the mean of RORgammat expressing CD4⁺ OT-II cells was 2-fold higher after MK2^{_ ~} compared to wild type LPS-DC injection (Fig. 6f-g) . This correlated with the enrichment of IL-17 producing OT-II cells in the lymph nodes of mice immunised with MK2^{_ ~} LPS-DC. The absence of MK2 significantly increased the percentage of IL-17⁺ IL-1CT OT-II cells. Although the number of IL-17 expressing OT-II cells in the lymph nodes was below 1%, notable amounts of IL-17 with up to 700 pg/ml were detected, showing 2-fold enrichment in cultivated lymph nodes from MK2^{_ ~} LPS-DCs immunized mice (Fig. 6h) . The percentage of IL17^" IL-10⁺ OT-II cells was similar in lymph nodes from mice treated with MK2^{_ ~} or wild type LPS-DCs (Fig. 6f-g) . IL-17⁺IL-10⁺ double positive cells were not detected. Based on the enrichment of T_H17 cells in mice after the encounter with MK2 deficient DCs, MK2 evidently attenuates T_H17 responses.

MK2 attenuates DC-driven T_H1 cell expansion and in vivo cytotoxicity

In addition to MK2-driven control of T_H17 immunity by DCs, MK2 also modifies the differentiation of T_H1 cells. Again DCs in response to TLR4 and TLR7/8 signalling for 6 and 24 hours were analysed for their potential to differentiate CD4 cells towards T_H1 cells (Fig. 7a-b) . OT-II splenocytes were strongly, almost 10-fold, enriched for OVA-specific IFN-gamma secreting cells in in vitro cultures with MK2-I3 treated DCs independent of the maturation time (Fig. 7a-b) . The same trend was observed for R848 activated DCs. Without boosting the cultures with OVA- peptide by using the control peptide only IFN-gamma producing cells were also detected, but to a smaller extend and again en^¬ riched in cultures with MK2 deficient DCs. Further strengthened IL-12-mediated T_H1 differentiation in in vitro cultures containing MK2 deficient LPS-DCs was clearly shown. IL-12Rbeta2 on CD4⁺ OT-II cells and IL-12 was strongly accumulated in in vitro cultures containing MK2-I3 treated LPS-DCs (Fig. 7c-d) . Since IL- lalpha-dependent increase of IL-12 secreted from LPS-DCs was shown, the role of IL-lalpha for T_H1 differentiation was analysed next. In co-cultures of OT-II cells with MK2^_/" LPS-DCs, IFN- gamma producing CD4⁺ T cells were also expanded to a higher level compared to wild type LPS-DCs (Fig. 7e-f) . Inhibition of IL- lalpha signalling in the in vitro cultures decreased the number of IFN-gamma producing OT-II cells.

Next T_H1 factors in lymph nodes from OT-II mice immunised with LPS-DCs were analysed (Fig. 7g-i) . When mice were immunised with MK2^_/" LPS-DCs the mean percentage of Tbet positive CD4⁺ OT- II cells was 2-fold increased, up to 40%. This correlated with the enrichment of IL-2 expressing cells in CD4+ cells, from 42 to 57% IL-2⁺ IL-10^" cells, when MK2 was absent in LPS-DCs. In ad^¬ dition, IL-2 secreted from cultured lymph node cells of MK2^{_ ~} LPS-DCs injected mice was, with up to 15 ng/ml, also strongly enriched. The percentage of IL-2⁺ IL-10⁺ and IL-2^" IL10⁺ OT-II cells was similar and below 0.4% in lymph nodes from mice treated with MK2^_/" or wild type LPS-DCs.

Based on the T_H1 modifying properties of MK2, the effect of MK2 signalling on CD8⁺ cytotoxic T cells was further investigated. DCs deficient for MK2 had a strong stimulatory potential for CD8⁺ T cells (Fig. 7j-k) . CD8⁺ OT-I cells proliferated up to 100-fold stronger in priming cultures with MK2^{_ ~} LPS-DCs compared to wild type LPS-DCs. Proliferation of CD8⁺ T cells was also increased in in vitro cultures of allogeneic T cells with MK2-silenced in comparison to control-silenced human LPS-DCs.

The strong MK2-dependent induction of CD8⁺ T cells lead to further testing of the potential to strengthen killer cell responses with MK2 deficient LPS-DCs in vivo. Wild type mice were immunised with OVA (SIINFEKL) -pulsed MK2^_/" or wild type LPS-DCs (Fig. 71) . After 4 days the draining lymph nodes were analysed for the reduction of CFSE^high SIINFEKL-loaded target cells in relation to CFSE^low irrelevant peptide loaded control splenocytes, which were injected 6 hours before. In vivo T cell priming with wild type LPS-DCs led to a 14% reduction of CFSE^high SIINFEKL- pulsed target cells (Fig. 7m-n) . Immunisation with MK2^{_ ~} LPS-DCs had a yet stronger effect resulting in 22% reduction of OVA- pulsed target cells. Control mice inoculated with PBS showed a decline of 8%. In vivo application of 6 hours activated LPS-DCs generally induces a strong cytotoxic response. For that reason cytotoxicity was measured already 6 hours after target cell injection. With extended killing time 90% antigen specific reduction of target splenocytes was observed.

In summary it was demonstrated that MK2 deficient DCs in response to LPS or R848 strengthen antigen-specific cytotoxicity and primarily associated T_H1 immunity.

MK2 mediates DC-driven Treg expansion

Anti-inflammatory feedback loops were increased due to enhanced STAT3 signalling via IL-10 in MK2 deficient DCs. These observations lead to investigation of Treg priming properties of MK2 deficient DCs. As for T_H1 and T_H17 cells, DCs in response to TLR4 and TLR7/8 signalling for 6 and 24 hours were analysed for their potential to differentiate CD4 cells towards Treg cells (Fig. 8a-b) . OT-II splenocytes showed decreased levels of OVA- specific IL-10 secreting cells in in vitro cultures with MK2-I3 treated DCs independent of the maturation time (Fig. 8a-b) . The same trend was observed for R848 activated DCs, albeit to a lower extent. Without boosting the cultures with OVA-peptide by using the control peptide only also IL-10 producing cells were detected, but to a smaller extend and again decreased in cultures with MK2 deficient DCs. MK2^{_ "} LPS-DC in co-cultures with OT-II cells also showed an impaired capacity for differentiating CD4⁺ T cells into IL-10 producing Tregs (Fig. 8c-d) . As antiinflammatory IL-10/STAT3 signalling could be restored in MK2- deficient DCs by blocking autocrine IL-lalpha, inhibition of IL- lalpha signalling in the in vitro cultures again strongly enhanced the number of IL-10 producing OT-II cells.

Next the impact of MK2 on the induction of CD25 FOXP3 expressing Treg cells in vivo was tested. Transplanted CD4⁺ OT-II cells were characterised after immunising wild type mice with OVA-peptide pulsed LPS-DCs (Fig. 8e-g) . The draining lymph nodes were strongly enriched for OT-II (Ly5.2⁺) cells in recipient wild type mice immunised with LPS-DCs (Fig. 8f) .

MK2^{_ "} LPS-DCs differentiated CD4+ (Ly5.2+) cells with 4% into less FOXP3⁺ CD25⁺ cells compared to 13% that were induced when we injected wild type LPS-DCs. Endogenous CD4⁺ (Ly5.1⁺) T cells from immunised wild type mice showed no significant dif^¬ ferences of FOXP3 expressing cells in activated CD25⁺ T cells that were induced with MK2^{_ ~} compared to wild type LPS-DCs. In summary these data show that MK2 expressed in DCs induces an antigen specific shift from a helper T_H1 or T_H17 to a regulatory T cell phenotype during CD4⁺ T cell differentiation.

Tissue derived antigen presenting cells require MK2 to attenuate inflammation

Finally it was investigated whether MK2 regulates inflamma^¬ tion triggered by tissue derived DCs. CDllc⁺ DCs from splenocytes of wild type mice were positively selected. A blockade of MK2 resulted in a strengthened T_H1 and T_H17 polarising DC phenotype after LPS encounter, which could be shown in ELISPOTs by doubling OVA-specific IFN-gamma and IL-17 producing cells in co- cultures of OT-II cells with MK2-I3 treated LPS-DCs (Fig. 9a-b) . IFN-gamma and IL-17 producing cells were also detected in control-stimulated DC/OT-II co-cultures with LCMV-peptide, but to a lesser extend compared to OVA-peptide boosting. Again IFN-gamma and IL-17 secreting cells were strongly increased in the presence of MK2-I3 without OVA re-stimulation, demonstrating the strong T_H1 priming capacity of MK2 deficient DCs. MK2-I3 treated splenic DCs also acquired a stronger capacity to differentiate T_H17 cells in vitro.

Next the in vivo function of MK2 in circulating DCs was investigated by directly immunising mice with LPS/OVA after transplanting CD4⁺ OT-II cells (Fig. 9b-e) . A reduced number of OVA- specific IFN-gamma but also IL-10 producing cells in lymph nodes were observed when systemic MK2 knockout mice were injected (Fig. 9b-c) . In contrast, local administration of LPS/OVA plus MK2-I3 by intra-dermal injection of wild type mice strongly en^¬ riched IFN-gamma secreting cells in draining lymph nodes (Fig. 9d-e) . IFN-gamma positive cells were enriched in lymph nodes of MK2-I3 treated mice after OVA-peptide and anti-CD3 re- stimulation in the ELISPOT assay. The lymph nodes did not respond to LCMV-peptide. In addition OVA-specific IL-10 secreting cells were decreased in mice after MK2-I3 treatment (Fig. 9e) . Supplemental injection of a blocking IL-lalpha antibody again increased the number of IL-10 secreting cells.

Inhibition of MK2 activity in comparison to RNAi leads to stronger CD8+ T cell proliferation

LPS-activated DCs either treated with MK2 specific siRNA or the MK2 inhibitor MK2-I3 were analysed for viability, IL-10 secretion and the potential to stimulate CD8+ T cells. Viability was slightly reduced when LPS-DCs were treated with MK2-specific (MK2- conditions) and control siRNA (NTC) in comparison to untreated LPS-DCs (Fig. 10A) . Furthermore MK2 specific silencing led to a reduction of IL-10 secreted from LPS-DCs that were generated with monocytes from 5 different donors. Equally treated DCs induced a 2-fold higher proliferation in CD8+ T cells when MK2 activity was blocked.

JAK1 attenuates DC-driven T_H1 cell expansion

In summary, these data provide evidence that MK2 balances T_H1 and T_H17 effector mechanisms towards regulatory, anti^¬ inflammatory functions in vitro and in vivo by modulating MAPK and JAK/STAT signalling depending on IL-lalpha secreted from LPS-stimulated DCs (Fig. 11) . MK2-mediated control of the IL- 10/STAT3 axis promotes an anti-inflammatory DC phenotype, which contributes to the stabilisation of Treg cells.

Unstable DC phenotype without IL-4 in the maturation cocktail

DCs and macrophages are closely related cells belonging to the myeloid lineage of blood cells. In the bone marrow starting from haematopoietic stem cells (HSC) the myeloid lineage undergoes a differentiation process until the stage of monocytes. The monocytes leave the bone marrow and circulate for some time in the peripheral blood. Eventually, they enter the various tissues and take their final differentiation into either DCs or macrophages. Whether a DC or a macrophage results from this last dif^¬ ferentiation step depends on the inflammatory status of the tissue microenvironment . If inflammatory cytokines are produced and released consistent with the notion that an inflammation is going on in the tissue, the monocytes acquire the macrophage phenotype. Macrophages are potent phagocytes that pick up necrotic cells, microorganisms, and antigen/antibody immune complexes. They can present antigens to primed T cells, but cannot prime naive T cells, which only respond to signals from DCs.

In the absence of inflammation the monocytes differentiate into DCs. Like macrophages, they are potent phagocytes. However, they act as sentinels in healthy tissue and take up apoptotic cells that underwent programmed cell death in the course of the continuous tissue regeneration. The phagocytosed material from apoptotic cells is processed and presented to T cells. The presentation of antigens by a tissue-resident DC that didn't encoun^¬ ter a maturation inducing danger signal causes the T cells to differentiate into immunosuppressive Tregs . This is referred to as peripheral tolerance as it complements the main central tolerance-inducing mechanisms that take place in the thymus. If DCs encounter a danger signal, they switch from the tolerance maintaining into an immunostimulatory mode of action. In contrast to macrophages, DCs in the immunostimulatory mode of action have the capacity to prime naive T cells as well as other T cells.

In spite of the close relation between DCs and macrophages, some of their function is opposite. This is the case in MK2 sig^¬ nalling. Several investigators have reported that in macrophages MK2 is involved in immunostimulatory signalling. Here we report that in DCs the opposite happens and MK2 signalling is immuno^¬ suppressive. Hence it is of crucial importance to make sure that in vitro from monocytes differentiated DCs assume a genuine DC phenotype and not the closely related macrophage phenotype; in fact, it is a frequent mix-up in the literature to talk about DCs that actually resemble more closely the macrophage phenotype. Maintaining a DC phenotype may be accomplished by adding IL-4 to the differentiation culture, which is standard in most protocols for DC manufacturing. But IL-4 needs also to be present in the maturation cocktail that is applied to the DCs in order to trigger their switch from the immature state, which resembles the phenotype of tissue-resident DCs, into the mature stage that primes T cells. Typically, this is accomplished by exposing immature DCs to a microbial danger signal.

In vitro differentiated DCs do not have a stable phenotype, which is a consequence of the artificial conditions in the differentiation culture. Even when monocytes differentiate into immature DCs, they revert into a macrophage phenotype if IL-4 is removed from the culture. This is different when experiments are performed using physiologic DCs. Less than 1% of circulating im^¬ mune cells are DCs. Methods have been developed to enrich these DCs from the blood and use them for experimentation. They so far have not been used in a clinical setting as the number of DCs collected from peripheral blood does not suffice for the manufacturing of a DC cancer vaccine. Table 1 gives the expression of typical DC/macrophage cell surface molecules. In this experiment, either IL-4 or GM-CSF was left out of the DC maturation cocktail. Of importance is that without IL-4 the expression of the CD14 molecule is clearly increased. CD14 is highly expressed on monocytes but is supposed to be down-regulated when monocytes differentiate into DCs, as may be seen in the expression on DCs exposed to the standard maturation cocktail or a maturation cocktail without GM-CSF but with IL-4. This shows that without IL-4 immature DCs during the 6 hours exposure to the maturation cocktail lost their DC pheno^¬ type and started resembling macrophages.

Table 1: Immunophenotype and IL-12 secretion from DCs in the presence and absence of IL-4 in the maturation culture.

IL-12 (ng/ml) 117 44 116

Another feature of DCs is the capacity for secreting IL-12 in large amounts, which is needed to polarise a type 1 immune response based on cytolytic T cells needed to kill tumour cells. Without IL-4 in the maturation cocktail, the amount of IL-12 secreted was clearly reduced also suggesting that they lost their DC phenotype and became macrophages .

DCs that are maturated under conditions that protect them from loosing their DC phenotype most closely resemble the characteristics of physiologic DCs collected directly from an organ^¬ ism. Conditions that permit monocyte-derived DCs to loose their DC phenotype, most importantly the lack of IL-4 in the maturation cocktail, will have features that more closely resemble macrophages. As it has been reported that MK2 acts in opposite ways in DCs and macrophages, and as we show here that monocyte- derived DCs that are matured without IL-4 switch to a macrophage phenotype, we expect that MK2 blockade resembles the results ob^¬ served in macrophages, which is reduced immunostimulatory capacity, and not in DCs, which is characterised by enhanced immunostimulatory capacity. IL-4 in the maturation culture is critically needed for maintaining the DC phenotype and MK2's immuno^¬ suppressive role, and only in this situation it makes sense to use an MK2 inhibitor in order to enhance the DCs' stimulatory capacity. This combines the favourable features of the DCs, e.g. priming of naive T cells, but also disrupting the MAPKAP kinase and JAK/STAT kinase pathways that carry the signal for an up- regulation of immune checkpoint mechanisms thus delaying or even preventing the DCs from acquiring an immunosuppressive mode of action .

Confirmatory experiments in human DCs and first steps for clinical grade manufacturing

The in vitro and in vivo experiments described above were mainly done in the mouse system. In order to take this next generation of improved DC cancer vaccine technology into a clinical application, the effect of MK2 blockade in murine DCs needs to be confirmed using human DCs. Also an optimal concentration of the MK2 inhibitor MK2-I3 was established (Figure 12A) . It was observed that MK2-I3 prevented the phosphorylation of HSP27, a molecule that is known to be downstream of MK2 signalling suggesting that the MK2 blockade disrupted the corresponding signalling cascade. The phosphorylation of the p38 signalling molecule, that is upstream of MK2, was not affected by MK2 inhibition.

The secretion of IL-12 was clearly increased in DCs with disrupted MK2 signalling. This was observed during the maturation culture (Figure 12D) , but also when DCs were co-cultivated with T-cells for testing the DCs capacity to activate T-cells (Figure 12B) . This effect was most strongly observed on days 1 & 2 of the DC/T cell co-culture. Furthermore, the secretion of IL- 10, an important immune checkpoint molecule, was delayed in the presence of MK2-I3 (Figure 12C) . This permits the DCs to act im^¬ munostimulatory for a longer time thereby further improving their capacity to prime T cells. Importantly, immature DCs were in contact with the maturation cocktail comprised of LPS , IFN-γ, IL-4, GM-CSF and MK2-I3, for 6 hors only (Figures 12C & D) . Further maturation for 24 and 48 hours was done without the cocktail present. Also, the 6 days DC/T cell stimulation co-culture was set up after 6 hours of DC maturation without adding the maturation cocktail to the co- culture (Figure 12B) . This suggests that after initiation of maturation the DC phenotype stabilises, which is an important feature as the DCs are inoculated after 6 hours maturation into a patient. No matter at which location the DCs are inoculated, intravenously, subcutaneously, intradermally, intranodally, in- tratumourally, or combinations thereof, the DCs cannot maintain the contact with the maturation cocktail. If the DC phenotype would not be stable at this point, the maturation cocktail or critical components thereof would have to be applied to the patients as systemic treatment. This would greatly complicate DC cancer vaccination and introduce numerous risk factors for the patients .

The effects of MK2 inhibition seemed to reach their maximum at an MK2-I3 concentration of 10 μΜ, and were not further increased at a concentration of 30 μΜ (Figure 12) .

From these experiments and the experiments without IL-4 we conclude, that every single component of the maturation cocktail, maybe with the exception of GM-CSF, makes critical contributions to the maturation process. The danger molecule LPS might be replaced by other danger molecules such as Toll-like receptor agonistic molecules, BCG, or other microbial preparations, but the presence of a danger molecule is essential in the maturation cocktail. IFN-γ critically improves the maturation process and enhances the secretion of IL-12. Finally, IL-4 as demonstrated above assures that the DC phenotype remains stable until the DCs are irreversibly committed to switching from the tolerance maintaining immature DC phenotype into an immunostimulatory DC phenotype, which takes around 6 hours. And finally, the MK2 inhibitor improves the immunostimulatory capacity of the DCs as shown in Figure 12.

These experiments are focused on MK2 inhibition, as this is the first inhibitor we plan to study in a clinical pilot trial. Not as much work was done in human test systems with JAK1 inhibition. However, based on results from the mouse system it ap- pears reasonable to assume that JAK1 inhibition would be able to replace MK2 inhibition in the maturation cocktail. It might even be possible to combine the inhibition of MK2 and JAK1 in order to generate synergistic effects.

The critical process is disruption of the MAPKAP kinase and the JAK/STAT kinase pathways in DCs applied to cancer patients as a next generation of improved DC cancer vaccines. It should not make any difference, at which step these signalling pathways are disrupted. As long as no stimulus comes through that would cause an activation of immune checkpoint mechanisms, the immu- nostimulatory capacity of a DC should be maintained or improved. We suggest, therefore, that other molecules of the MAPKAP kinase and JAK/STAT kinase pathways could be targeted resulting in a similar improvement of the DCs' potency in cancer immunotherapy.

Discussion

Previous studies have shown that down modulation of p38- activated MK2 results in reduced protein biosynthesis of several inflammatory cytokines in macrophages suggesting that MK2 mediates pro-inflammatory properties. Based on the present examples, an unexpected regulatory function of MK2 by stabilising an antiinflammatory phenotype in human and mouse DCs in response to LPS is shown. This leads to LPS-induced inhibition of T_H1, T_H17 and killer cell responses mediated by IL-lalpha/p38 and Erkl/2 sig^¬ nalling in DCs. Consistent with this observation, MK2 promotes IL-10/STAT3 signalling in DCs and the expansion of Treg cells.

A conversion from a regulatory to a T_H1 and T_H17 promoting phenotype was observed in LPS-DCs derived from bone marrow of MK2^{_ ~} mice but also in splenic DCs treated with MK2-I3 inhibitor. Such DCs induce an enhanced antigen-specific killer cell response in the lymph nodes of wild-type mice. Along with previous studies also a decreased T cell stimulatory potential in directly LPS-injected MK2^{_ ~} mice was observed. However, local injection of LPS together with MK2-I3 into wild type mice strongly increased T_H1 immunity. MK2 was revealed as being essential for protein biosynthesis of TNF-alpha and systemic LPS-induced shock in mice. Additionally, MK2 knockout mice showed a higher suscep^¬ tibility for Listeria monocytogenes infection, which suggested MK2 as a key molecule in inflammation and host defence. Accord- ing to the present invention, locally distinct pro-inflammatory responses depending on the investigated tissues were induced in disease models propagating cutaneous or lung inflammation in MK2 deficient mice. The heterogeneous response may result from variable expression patterns in different cell types and context dependency of MK2. A defect in immune regulation in tissue- specific DCs may therefore explain local accumulation of inflam^¬ matory factors in MK2 knock-out mice and the increase of T_H1 immunity when LPS/MK2-I3 was injected locally.

DCs initiate pro- and anti-inflammatory immune responses de^¬ pending on the maturation stimuli and time. In this context LPS is reported to trigger a variety of DC-mediated effector but also regulatory mechanisms involving CD4⁺ T_H1 or Treg cells. With the present invention, it was demonstrated that the expression kinetics of MK2 in LPS-stimulated DCs correlates with that of known anti-inflammatory genes like IL-10 or STAT3, both showing strongest expression after 24 hours. At this time, TNF-alpha secretion is diminished showing that MK2 has additional time delayed functions apart from LPS-mediated TNF-alpha regulation as shown in earlier studies. With the present invention it is shown that MK2 is essential for p38-mediated IL-10 secretion from LPS- DCs, as it was recently described for macrophages, where IL-10 expression essentially requires the presence of MK2. The inhibitor studies according to the present invention using the p38 inhibitor SB203580 and the MK2 inhibitor MK2-I3 revealed that the LPS/p38/MK2 signalling route predominantly induces IL-10. This observation correlates with reports that describe p38 as being associated with increased IL-10 and the induction of tolerance. Thus, inhibition of p38 can attenuate Treg induction. Further it was shown that DCs sustain IL-10 secretion via secondary IL- lalpha/p38 /MK2 signalling. By blocking IL-lalpha reduced secondary IL-10/STAT3 signalling in LPS-DCs was observed, assigning IL-lalpha autocrine anti-inflammatory functions. In contrast paracrine effects of IL-lalpha on T cells contribute to T_H1 and T_H17 T cell differentiation. Inhibition of MK2 reduces IL- 10/STAT-3 signalling although IL-lalpha secretion is strongly enhanced. Additional blockade of IL-lalpha restores IL-10/STAT3 signalling and the differentiation of IL-10 producing T cells. MK2 deficiency reverts autocrine binding of anti-inflammatory IL-lalpha into a pro-inflammatory signalling route. In line with this observation a prolonged T_H1 and T_H17 promoting DC phenotype stabilised by increased IL-lalpha/p38 signalling in the absence of MK2 was found. As a consequence, by blocking MK2, LPS-DCs ex^¬ pand T_H1 and T_H17 cells by preventing the induction of Treg cells in vivo. In the present examples it was observed that IL-lalpha is only marginally expressed in LPS-activated macrophages compared to LPS-activated DCs. Thus, impaired autocrine IL- lalpha/p38 signalling may even decrease T_H17 cytokines in macrophages .

The interplay of p38, Erkl/2 and JNK signalling represents a sensitive integrated circuit, which regulates phenotypic changes in DCs by changing the cytokine profile. MK2 is a central switch by negatively regulating p38 and promoting Erkl/2 signalling. Inhibition of MK2 activity triggers IL-12 but also IL-1 production, hence, T_H1 and T_H17 mediated responses. Together with reduced Erkl/2 phosphorylation increased IL-lbeta secretion in the absence of MK2 activity was found. IL-23 was not affected.

In summary, MK2 deficiency strongly increases T_H1 immunity and in vivo cytotoxicity, which can be explained by three domi^¬ nant molecular mechanisms: (i) increased IL-lalpha/p38 signalling, (ii) impaired autocrine IL-10/STAT3 signalling, and (iii) disrupted Erkl/2 signalling, which over all boost IL-12 secreted from LPS activated DCs. Autocrine feedback signalling of IL-10 via the JAK1-STAT3 signalling cascade is known to stabilize a regulatory DC phenotype by down regulating IL-12 secretion and consequently T_H1 responses. Additionally, recent studies have shown that increased activity of the Erkl/2 signalling pathway attenuates IL-12 and T_H1 immunity.

Notably, strong induction of T_H1 cells was observed after the injection of MK2 deficient LPS-DCs into WT mice, which was associated with high secretion of IL-2 but not IL-10 from CD4⁺ T cells. Pleiotropic functions of IL-2 also suggest that the ability of IL-2 to drive the differentiation into Treg cells depends on the cellular source of IL-2. Neither IL-2/IL-10 double nor IL-10 single positive OT-II cells are enriched after injecting MK2^{_ ~} LPS-DCs, which excludes the possibility of paracrine activation of Treg cells by IL-2 secreting T_H1 cells.

The relevance of MK2 blockade for the immunologic control of tumour growth is demonstrated in conditional jy[K2^DeltaDC knockout mice. An experimental tumour was controlled only in the knockout but not in control mice. This further suggests the therapeutic utility of MK2 inhibition in DCs in the context of cancer immunotherapy .

The early and primary phase of cytokine regulation by MK2 has been well characterized. Late expression of MK2 and secondary events in the complex autocrine signalling network of DC- derived cytokines stabilizes a regulatory, anti-inflammatory phenotype in DCs. Differential regulation of IL-lalpha and IL-10 by LPS/p38/MK2 signal transduction lead to secondary involvement of the IL-lalpha/p38 and the IL-10/STAT3 cascade which shifts the balance from T_H17 and T_H1 towards Treg immune responses. Therefore, MK2 appears to play an essential homeostatic role in limiting the extent and duration of a stimulatory immune reaction. In addition to the mouse system, evidence is also provided for an analogue function of MK2 in human DCs. This correlates with an enhanced stimulatory potential of MK2 deficient DCs for CD8⁺ effector T cells. Thus, MK2-driven secondary antiinflammatory responses can be used in tumour- or pathogen antigen-models for further clinical intervention where MK2-specific inhibition is used to modulate immune regulation.

Of note are the effects of MK2 blockade on LPS versus R848 and poly(I:C) treated DCs. In contrast to LPS and R848, poly(I:C) did not trigger MK2 phosphorylation in DCs. Also IL-12 secretion was enhanced in MK2-I3 treated LPS-DCS, but not in R848 and poly(I:C) matured DCs. As for IL-lalpha or IL-12, IL-10 was reduced in MK2-blocked DCs matured with LPS and to a lesser extent R848; poly(I:C) activation did not affect IL-10 expression. IL-17 secreting T-cells were found increased MK2-inhibited LPS-DCs, but not at a significant rate in R848-DCs; poly(I:C) was not considered in further experiments. MK2-I3 treated LPS- DCs and to a lower extent R848-DCs were found to support IFN- gamma secretion. The IL-10 secretion from Tregs was lower when contacted with MK2-I3 treated LPS-DCs compared to controls; the same trend was observed in R848-DCs but at a lower extent.

From these investigations we conclude that the effect of MK2-blockade of DCs undergoing LPS-mediated maturation is strongest and, consequently, LPS-DCs are most preferred in the present invention. R848 maturation of MK2-targeted DCs shows a similar trend but is considerably weaker compared to LPS and is, therefore less preferred. Poly(I:C) was the least active matura- tion agent and could not support the modulation of the characteristics of DCs by MK2-blockade .

The present invention relates to the following preferred embodiments :

1. Method for producing and/or stimulating dendritic cells (DCs) , wherein immature DCs or precursor cells thereof are stimulated and matured comprising exposure to an antigen, a maturation agent, preferably from the group of Toll-like recep^¬ tor agonists, and an inhibitor selected from the group consisting of an MK2 inhibitor, a JAK1 inhibitor or a combination of a JAK1 inhibitor and a MK2 inhibitor, wherein the stimulation and/or maturation agent preferably comprises LPS.

2. Method according to embodiment 1 wherein production of the DCs comprises exposure of the cells to cytokines, via differentiation from precursor cells including monocytes or haematopoietic stem or precursor cells in the presence of a cytokine or a cytokine cocktail, wherein said cytokine cocktail is preferably comprised of at least two cytokines, selected from the group of GM-CSF, IL-4, IL-3, IL-13 type I/II interferons, TNF-alpha, PG- E2 and IL- lalpha/beta, and/or TGFbeta, especially a combination of IL-4 and GM-CSF.

3. Method according to embodiments 1 or 2, wherein stimulation and maturation of the DCs comprises exposure of the cells to an agonist of a Toll-like receptor, preferably LPS, especially dead or living microorganisms such as BCG; resiquimod (R848), imiquimod, poly(I:C), flagellin, double stranded RNA, CpG oligonucleotides, type I/II interferons, preferably pro-inflammatory cytokines, especially IFN-gamma, IL-4, or GM-CSF; a mixture of inflammatory cytokines including TNF-alpha, IL-1, or prostaglandins; synthetic or recombinant CD40L molecules, cells engineered to express CD40L molecules, T-cells stimulated to ex^¬ press CD40L molecules, stimulatory monoclonal antibodies directed at CD40; physical, chemical or microbial stress signals, danger associated molecules from necrotic or apoptotic cells, preferably cellular destruction or distress signalling molecules, especially heat shock proteins. 4. Method according to any one of embodiments 1 to 3, wherein the MK2 inhibitor is selected from the group consisting of aminocyanopyrimidines , pyrazolo [ 1 , 5-alpha ] pyrimidines , pyrrolopyri- dones, pyrrolo-amides, pyrrolo-nitriles , carbolines, especially tetrahydro-beta-carboline-l-carboxylic acids , indolopyraz inones , squarates, indazole carboxamides , thienopyridines , furanopyri- dine, indazoles, dihydro-pyrimido [ 6, 1-alpha] isoquinolin-ones , 2- (2-Quinolin-3-ylpyridin-4-yl) -1,5, 6, 7-tetrahydro-4H-pyrrolo-

[3, 2-c] pyridin-4-one, arylamides, rottlerin, ( + ) -makassaric acid, (+) -subersic acid, phaeochromycin A, and phaeochromycin C.

5. Method according to any one of embodiments 1 to 4, wherein the JAK1 inhibitor is selected from the group consisting of ruxolitinib, tofacitinib, baricitinib, piperidin-4-yl azetidine derivatives, cycloamino and cycloalkylamino analogues containing a pyrrolopyridine ring system, (R) -3- (4- (7H-pyrrolo [2, 3-d] pyrimidin-4-yl) -lH-pyrazol-1- yl) -3-cyclopentylpropanenitrile, C-2 Methyl Imidazopyrrolopyridines , and tricyclic pyrazone.

6. Method according to any one of embodiments 1 to 5, wherein exposure of the cells to the antigen comprises exposure of the antigen together with an adjuvant to the cells, especially KLH, recall antigens such as tetanus toxoid or diphtheria toxin, or BCG.

7. Method according to any one of embodiments 1 to 6, wherein the antigen is selected from microbial antigens, especially bac^¬ terial, viral, or fungal antigens; tumour antigens, especially synthetic tumour antigen peptides, recombinant tumour antigen proteins, cellular extracts of tumour cells, DNA in viral and non-viral vectors or synthetic or cell-derived RNA molecules encoding any of these antigens, or combinations thereof.

8. Method according to any one of embodiments 1 to 7, wherein immature DCs are differentiated from autologous or allogeneic monocytes or precursor cells thereof including haematopoietic stem cells are stimulated by cytokines, preferably by one or more of IL-4, GM-CSF, IL-3, IL-13, type I/II interferons, TNF- alpha, PG-E2 and IL-lalpha/beta, especially IL-4 and GM-CSF. 9. Method according to embodiment 8, wherein the stimulation by cytokines is performed for 3-9 days, preferably for 4-8 days, especially for 5-7 days.

10. Method according to embodiment 8 or 9, wherein the stimulation is followed by pulsing with an antigen, wherein pulsing with the antigen is preferably conducted for 10 min to 5 h, more preferred for 20 min to 4 h, especially for 30 min to 2 h.

11. Method according to any one of embodiments 1 to 10, wherein immature DCs are charged with an antigen followed by treatment with a maturing agent for 1 to 20 h, preferably for 2 to 12 h, especially for 3 to 8 h.

12. Method according to any one of embodiments 1 to 11, wherein immature DCs are treated with a maturation agent selected from the group consisting of pathogen associated molecule patterns (PAMPs) , preferably LPS, especially dead or living microorgan^¬ isms including BCG; resiquimod (R848), imiquimod, poly(I:C), flagellin, double stranded RNA, CpG oligo-nucleotides , type I/II interferons, preferably pro-inflammatory cytokines, especially IFN-gamma, IL-4, or GM-CSF; a mixture of inflammatory cytokines including TNF-alpha, IL-1, IL-6, or prostaglandins; synthetic or recombinant CD40L molecules, cells engineered to express CD40L molecules, T-cells stimulated to express CD40L molecules, stimulatory monoclonal antibodies directed at CD40; physical, chemical or microbial stress signals, danger associated molecules from necrotic or apoptotic cells, preferably cellular destruction or distress signalling molecules, especially heat shock proteins .

13. Method according to any one of embodiments 1 to 12, wherein immature DCs or precursor cells thereof are stimulated and/or matured by a stimulation and/or maturation agent comprising LPS, preferably LPS in combination with IFN-γ.

14. Method according to any one of embodiments 1 to 13, wherein the produced and/or stimulated DCs are used for intradermal, subcutaneous, intramuscular, intravenous application; for direct inoculation into primary or metastatic tumour tissue; for introduction into lungs, gastro-intestinal tract, urogenital tract; for epidural application, or combinations thereof.

15. Composition comprising

an inhibitor selected from the group consisting of an MK2 inhibitor with a molecular weight of below 1000 Da, a JAK1 in^¬ hibitor with a molecular weight of below 1000 Da or a combination of a JAK1 inhibitor with a molecular weight of below 1000 Da and an MK2 inhibitor with a molecular weight of below 1000 Da and

a pathogen associated molecule pattern (PAMP) , preferably

LPS .

16. Composition according to embodiment 15, further comprising an inflammation promoting cytokine, especially interferon-gamma (INF-gamma) .

17. Composition according to embodiments 15 or 16, wherein the MK2 inhibitor is selected from the group consisting of amino- cyanopyrimidines , pyrazolo [ 1 , 5-alpha ] pyrimidines , pyrrolopyrido- nes, pyrrolo-amides , pyrrolo-nitriles , carbolines, especially tetrahydro-beta-carboline-l-carboxylic acids , indolopyraz inones , squarates, indazole carboxamides , thienopyridines , furanopyri- dine, indazoles, dihydro-pyrimido [ 6, 1-alpha] isoquinolin-ones , 2- (2-Quinolin-3-ylpyridin-4-yl) -1,5,6, 7-tetrahydro-4H-pyrrolo-

18. Composition according to embodiments 15 to 17, wherein the JAK1 inhibitor is selected from the group consisting of ruxolit- inib, tofacitinib, baricitinib, piperidin-4-yl azetidine derivatives, cycloamino and cycloalkylamino analogues containing a pyrrolopyridine ring system, (R) -3- (4- (7H-pyrrolo [2, 3-d] pyrimidin-4-yl) -lH-pyrazol-1- yl) -3-cyclopentylpropanenitrile, C-2 Methyl Imidazopyrrolopyridines , and tricyclic pyrazone.

19. Composition according to any one of embodiments 15 to 18, wherein the PAMP is a Toll-like receptor (TLR) agonist, preferably LPS, especially dead or living microorganisms; resiquimod (R848), imiquimod, poly(I:C), flagellin, or combinations thereof .

20. Composition according to any one of embodiments 15 to 19, further comprising an antigen, wherein the antigen is selected from microbial antigens, especially bacterial, viral, or fungal antigens; tumour antigens, especially synthetic tumour antigen peptides, recombinant tumour antigen proteins, cellular extracts of tumour cells, DNA in viral and non-viral vectors or synthetic or cell-derived RNA molecules encoding any of these antigens, or combinations thereof.

21. Composition according to any one of embodiments 15 to 20, for use in tumour treatment.

22. Composition according to any one of embodiments 15 to 21, for direct inoculation into primary or metastatic tumour tissue; for intradermal, subcutaneous, intramuscular, intravenous application; for introduction into lungs, gastro-intestinal tract, urogenital tract; for epidural application, or combinations thereof .

Claims

Claims :

1. Method for producing and/or stimulating dendritic cells (DCs) , wherein immature DCs or precursor cells thereof are stimulated and matured comprising exposure to an antigen, a maturation agent, preferably from the group of Toll-like receptor agonists, and an inhibitor selected from the group consist^¬ ing of an MK2 inhibitor, a JAK1 inhibitor or a combination of a JAK1 inhibitor and a MK2 inhibitor, wherein the stimulation and/or maturation agent comprises LPS.

2. Method according to claim 1 wherein production of the DCs comprises exposure of the cells to cytokines, via differentia^¬ tion from precursor cells including monocytes or haematopoietic stem or precursor cells in the presence of a cytokine or a cytokine cocktail, wherein said cytokine cocktail is preferably com^¬ prised of various combinations of GM-CSF, IL-4, IL-3, IL-13 type I/II interferons, TNF-alpha, PG-E2 and IL-lalpha/beta, and/or TGFbeta, preferably a combination of IL-4 and GM-CSF.

3. Method according to claims 1 or 2, wherein stimulation and maturation of the DCs comprises exposure of the cells to an ago^¬ nist of a toll-like receptor, preferably LPS, especially dead or living microorganisms such as BCG resiquimod (R848), imiquimod, poly(I:C), flagellin, double stranded RNA, CpG oligo^¬ nucleotides, type I/II interferons, preferably pro-inflammatory cytokines, especially IFN-gamma, IL-4, or GM-CSF; a mixture of inflammatory cytokines including TNF-alpha, IL-1, or prostaglandins; synthetic or recombinant CD40L molecules, cells engineered to express CD40L molecules, T-cells stimulated to express CD40L molecules, stimulatory monoclonal antibodies directed at CD40; physical, chemical or microbial stress signals, danger associated molecules from necrotic or apoptotic cells, preferably cellular destruction or distress signalling molecules, especially heat shock proteins.

4. Method according to any one of claims 1 to 3, wherein the MK2 inhibitor is selected from the group consisting of amino- cyanopyrimidines , pyrazolo [ 1 , 5 -alpha ] pyrimidines , pyrrolopyrido- nes, pyrrolo-amides , pyrrolo-nitriles , carbolines, especially tetrahydro-beta-carboline-l-carboxylic acids , indolopyraz inones , squarates, indazole carboxamides , thienopyridines , furanopyri- dine, indazoles, dihydro-pyrimido [ 6, 1-alpha] isoquinolin-ones , 2- (2-Quinolin-3-ylpyridin-4-yl) -1,5,6, 7-tetrahydro-4H-pyrrolo- [3, 2-c] pyridin-4-one, arylamides, rottlerin, ( + ) -makassaric acid, (+) -subersic acid, phaeochromycin A, and phaeochromycin C.

5. Method according to any one of claims 1 to 4, wherein the JAK1 inhibitor is selected from the group consisting of ruxolit- inib, tofacitinib, baricitinib, piperidin-4-yl azetidine deriva^¬ tives, cycloamino and cycloalkylamino analogues containing a pyrrolopyridine ring system, (R) -3- (4- (7H-pyrrolo [2, 3-d] pyrimidin-4-yl) -lH-pyrazol-1- yl) -3-cyclopentylpropanenitrile, C-2 Methyl Imidazopyrrolopyridines , and tricyclic pyrazone.

6. Method according to any one of claims 1 to 5, wherein the antigen is selected from microbial antigens, especially bacterial, viral, or fungal antigens; tumour antigens, especially synthetic tumour antigen peptides, recombinant tumour antigen proteins, cellular extracts of tumour cells, DNA in viral and non-viral vectors or synthetic or cell-derived RNA molecules encoding any of these antigens, or combinations thereof.

7. Method according to any one of claims 1 to 6, wherein immature DCs are differentiated from autologous or allogeneic mono^¬ cytes or precursor cells thereof including haematopoietic stem cells using cytokines, preferably by one or more of the group consisting of IL-4, GM-CSF, IL-3, IL-13, type I/II interferons, TNF-alpha, PG-E2 and IL- lalpha/beta, especially IL-4 and GM-CSF, for 3-9 days, preferably 4-8 days, especially 5-7 days; followed by pulsing with an antigen, wherein pulsing with the antigen is preferably conducted for 10 min to 5 h, more preferred for 20 min to 4 h, especially for 30 min to 2 h.

8. Method according to any one of claims 1 to 7, wherein imma^¬ ture DCs are charged with an antigen followed by treatment with a maturation agent for 1 to 20 h, preferably for 2 to 12 h, especially for 3 to 8 h.

9. Method according to any one of claims 1 to 8, wherein imma- ture DCs or precursor cells thereof are stimulated and/or matured by a stimulation and/or maturation agent comprising LPS, preferably LPS in combination with IFN-gamma, IL-4 and GM-CSF.

10. Composition comprising

a pathogen associated molecule pattern (PAMP) , preferably

LPS .

11. Composition according to claim 10, further comprising an inflammation promoting cytokine, especially interferon-gamma (INF- gamma) , IL-4 and GM-CSF.

12. Composition according to claims 10 or 11, wherein the MK2 inhibitor is selected from the group consisting of aminocyano- pyrimidines, pyrazolo [ 1 , 5-alpha ] pyrimidines , pyrrolopyridones , pyrrolo-amides , pyrrolo-nitriles , carbolines, especially tetra- hydro-beta-carboline-l-carboxylic acids, indolopyraz inones , squarates, indazole carboxamides , thienopyridines , furanopyri- dine, indazoles, dihydro-pyrimido [ 6, 1-alpha] isoquinolin-ones , 2- (2-Quinolin-3-ylpyridin-4-yl) -1,5,6, 7-tetrahydro-4H-pyrrolo-

[3, 2-c] pyridin-4-one, arylamides, rottlerin, ( + ) -makassaric acid, (+)-subersic acid, phaeochromycin A, and phaeochromycin C, and/or wherein the JAK1 inhibitor is selected from the group consisting of ruxolitinib, tofacitinib, baricitinib, piperidin- 4-yl azetidine derivatives, cycloamino and cycloalkylamino analogues containing a pyrrolopyridine ring system, (R) -3- (4- (7H- pyrrolo [ 2 , 3-d] pyrimidin-4-yl) -lH-pyrazol-1- yl)-3- cyclopentylpropanenitrile, C-2 Methyl Imidazopyrrolopyridines , and tricyclic pyrazone.

13. Composition according to any one of claims 10 to 12, wherein the PAMP is a Toll-like receptor (TLR) agonist, preferably LPS, especially dead or living microorganisms, resiquimod (R848), imiquimod, poly(I:C), flagellin, or combinations thereof.

14. Composition according to any one of claims 10 to 13, further comprising an antigen, wherein the antigen is selected from microbial antigens, especially bacterial, viral, or fungal antigens; tumour antigens, especially synthetic tumour antigen peptides, recombinant tumour antigen proteins, cellular extracts of tumour cells, DNA in viral and non-viral vectors or synthetic or cell-derived RNA molecules encoding any of these antigens, or combinations thereof.

15. Composition according to any one of claims 10 to 14, for use in tumour treatment, preferably for direct inoculation into primary or metastatic tumour tissue; for intradermal, subcutaneous, intramuscular, intravenous application; for introduction into lungs, gastro-intestinal tract, urogenital tract; for epidural application, or combinations thereof.