CN113527503A

CN113527503A - anti-VEGF and TNF-alpha bispecific nano antibody fusion protein for rheumatoid arthritis

Info

Publication number: CN113527503A
Application number: CN202110850014.2A
Authority: CN
Inventors: 陈逸媛; 林仪芮; 陈昱翰; 黄超; 陈妍; 张旭韬
Original assignee: Fujian Medical University
Current assignee: Fujian Medical University
Priority date: 2021-07-27
Filing date: 2021-07-27
Publication date: 2021-10-22

Abstract

The invention discloses an anti-VEGF and TNF-alpha bispecific nano antibody fusion protein for rheumatoid arthritis, which belongs to the technical field of genetic engineering and comprises an anti-VEGF antibody or a V EGF receptor-Fc fusion body and an anti-TNF-alpha polypeptide, and a connecting peptide for connecting the anti-VEGF antibody or the VEGF receptor-Fc fusion body and the anti-TNF-alpha polypeptide; the linker peptide consists of a flexible peptide comprising 1 or more flexible units and a rigid peptide comprising one or more rigid units. The anti-VEGF and anti-TNF-alpha bispecific nano antibody fusion protein provided by the invention can be used for preventing or treating rheumatoid arthritis, and has the advantages of safety, reliability and strong specificity.

Description

anti-VEGF and TNF-alpha bispecific nano antibody fusion protein for rheumatoid arthritis

Technical Field

The invention relates to the technical field of genetic engineering, in particular to a bispecific nano antibody fusion protein for resisting VEGF and TNF-alpha for rheumatoid arthritis.

Background

Rheumatoid Arthritis (RA) is a chronic inflammatory and destructive joint disease that affects 0.5-1% of the population in the industrialized world and often causes significant disability that reduces the quality of life of patients.

Angiogenesis in the synovium of patients with RA is considered an important early step in pathogenesis and perpetuation of disease (Taylor, 2002). As in neoplastic diseases, angiogenesis promotes dilation of the synovium (Walsh et al, 1998). Vascular growth is likely to contribute to the proliferation of inflammatory synovium pannus and to the entry of inflammatory leukocytes into synovial tissue. Synovium of patients with RA contains increased amounts of fibroblast growth factor-2 (FGF-2) and Vascular Endothelial Growth Factor (VEGF) (Koch, 2003). Serum VEGF concentrations correlate with disease activity and decrease when synovitis can be successfully inhibited by therapy (Taylor, 2002).

Vascular Endothelial Growth Factor (VEGF) is a major family of angiogenic proteins involved in endothelial cell activation, proliferation and survival, particularly during retinal proliferative diseases and tumorigenesis. VEGF belongs to the VEGF-PDGF (platelet-derived growth factor) supergene family and is a small glycoprotein dimer that binds to receptors expressed in blood vessels and lymphatic endothelial cells. Currently, there are seven known ligands in the VEGF family: VEGF-A (VEGF), VEGF-B, VEGF-C, VEGF-D, VEGF-E (viral derived), and placental growth factor (PIGF) -1 and-2. These VEGF ligands mediate their effects by binding to one or more of three known VEGF receptors (VEGF-R), each of which possesses receptor tyrosine kinase activity. VEGF-R1(Flt-1) is expressed primarily in endothelial cells and monocytes, binds to VEGF and VEGF-B, and appears to mediate migration of endothelial cells and monocytes. VEGF-R2 (i.e., human KDR or murine Flk-1) is expressed predominantly in endothelial cells, is selective for VEGF (and specific fragments of VEGF-C and VEGF-D), and mediates VEGF-induced endothelial cell proliferation, survival and migration, and vascular permeability. VEGF-R3(Flt-4) is expressed predominantly in lymphatic endothelial cells and binds to VEGF-C and VEGF-D to promote lymphangiogenesis. VEGF-R1, -R2, and-R3 are each expressed in some tumor cells. Binding of VEGF to VEGF receptors triggers receptor dimerization, leading to subsequent receptor activation and signal transduction. Binding of VEGF to VEGF-R2 initiates a signal transduction pathway that is dominant in promoting angiogenesis. This pathway involves receptor activation and subsequent induction of intracellular signal transduction. In this case, receptor activation requires three basic events: (i) VEGF binds to VEGF-R2, (ii) receptor dimerization, and (iii) receptor autophosphorylation (and thus activation) of receptor tyrosine kinases. Intracellular messengers, such as phospholipase C and phosphatidylinositol-3-kinase, bind directly to the autophosphorylated form of VEGF-R2 and are phosphorylated by receptor tyrosine kinases, which then trigger an intracellular cascade of signal transduction events, resulting in the generation of nuclear signals that ultimately promote cell proliferation, migration and survival (anti-apoptosis) and increase vascular permeability.

Tumor necrosis factor alpha (TNF α) is a multifunctional cytokine, is involved in important physiological processes such as apoptosis, survival, inflammatory response, and immune response of cells, and plays an important role in the development of diseases such as rheumatoid arthritis, Crohn's disease, and psoriasis (psoriatic). Therefore, TNF α is considered to be a very important target for drug development in the treatment of the above-mentioned related diseases. Infliximab (infliximab), adalimumab (adalimumab), golimumab (golimumab) and the like are therapeutic anti-TNF alpha antibodies, show remarkable curative effect and safety in treating diseases such as RA and the like, are one of the most popular global heavy drugs, and the research and development of other therapeutic anti-TNF alpha antibodies are hot.

In the last two decades, protein fusion technology has been widely applied to construct bifunctional antibodies, bifunctional enzymes, bifunctional proteins, and the like. However, various problems have been encountered in constructing fusion proteins, such as failure to fold correctly in a fusion protein when the protein is expressed alone; the two fused proteins are close to each other in space, so that the active sites are shielded; fusion protein molecules are easily degraded by proteases due to their inability to fold correctly or their conformational changes; the original protein catalytic domain with certain flexibility loses the original functions after fusion. These problems often result in a reduction or even complete loss of the activity of the fusion protein. It is generally thought that the activity of the original protein molecule is reduced to some extent after the fusion protein is constructed; an interesting fusion protein is one in which the activity of each part is maintained above 50% of the original protein molecule. In order to solve the above problems, many studies and researches have been made on the design and construction of fusion proteins in order to improve the activity of the fusion proteins.

Disclosure of Invention

The invention aims to provide a bispecific nano antibody fusion protein for resisting VEGF and TNF-alpha for rheumatoid arthritis, which aims to solve the problems in the prior art.

In order to achieve the purpose, the invention provides the following scheme:

the invention provides an anti-VEGF and TNF-alpha bispecific nanobody fusion protein, which comprises an anti-VEGF antibody or a VEGF receptor-Fc fusion and an anti-TNF-alpha polypeptide, and a connecting peptide for connecting the anti-VEGF antibody or the VEGF receptor-Fc fusion and the anti-TNF-alpha polypeptide; the linker peptide consists of a flexible peptide comprising 1 or more flexible units and a rigid peptide comprising one or more rigid units.

Further, the flexible unit amino acid has a general structural formula of (GS) x (GGS) y (GGGS) z (GGGGS) m, wherein x, y, z and m are integers greater than or equal to 0, and x + y + z + m is greater than or equal to 1.

Further, the rigid unit is selected from the following sequences:

(1)SPSKKAPAPSLPLPSRLGGPSGTPPLPQ；

(2)SAGSKKPGPS。

further, the rigid peptide is located at the C-terminus of the flexible peptide.

Further, the flexible unit is selected from the following sequence:

(1)GSYHKNYALPPQSKKALLRFQDSLK；

(2)ARLFGPSSLLPQQAAGSRLGSGGRRP。

the invention also provides a polynucleotide for encoding the anti-VEGF and TNF-alpha bispecific nanobody fusion protein.

The present invention also provides an expression vector comprising the polynucleotide.

The invention also provides a host cell transfected with the expression vector.

The invention also provides a method for preparing the anti-VEGF and TNF-alpha bispecific nanobody fusion protein, which comprises the step of culturing the host cell.

The invention also provides application of the anti-VEGF and TNF-alpha bispecific nanobody fusion protein, the polynucleotide, the expression vector or the host cell in preparation of drugs for treating and/or preventing rheumatoid arthritis.

The invention also provides a pharmaceutical composition, which comprises the anti-VEGF and TNF-alpha bispecific nanobody fusion protein and at least one pharmaceutically acceptable excipient.

Further, at least one pharmaceutically acceptable adjuvant is also included.

The pharmaceutical composition may comprise any number of excipients. Excipients that may be used include carriers, surfactants, thickening or emulsifying agents, solid binders, dispersing or suspending aids, stabilizers, colorants, flavorants, coatings, disintegrants, lubricants, sweeteners, preservatives, isotonic agents, and combinations thereof.

The primary vehicle or carrier in the pharmaceutical composition may be aqueous or non-aqueous in nature. For example, a suitable vehicle or carrier may be water for injection, saline, or artificial cerebrospinal fluid, which may be supplemented with other materials common in injections. For example, the vehicle or carrier may be a neutral buffered saline solution or a saline solution mixed with serum albumin. Other exemplary pharmaceutical compositions comprise Tris buffer, or acetate buffer, which may also comprise sorbitol or a suitable substitute thereof. In one embodiment of the invention, the composition may be prepared for storage by mixing the selected component with the desired purity with any formulation, either in lyophilized or aqueous solution form. In addition, the therapeutic composition may be formulated as a lyophilizate using suitable excipients such as sucrose.

Preferably, the pharmaceutical composition is suitable for intravenous, intramuscular, subcutaneous, parenteral, spinal, or epidermal administration (e.g., by injection or bolus injection). Depending on the route of administration, the active molecule may be encapsulated in a material to protect it from the action of acids and other natural conditions that may inactivate it.

The invention discloses the following technical effects:

the connecting peptide has wide applicability and portability, the combined sequence of the rigid unit and the flexible unit can endow the connecting peptide with conformation between complete rigidity and complete flexibility, and the specific rigidity (or flexibility) degree of the polypeptide is different according to the proportion and arrangement between the two sequences. Through designing the combination sequences of the rigid units and the flexible units in different proportions and arrangements, the rigidity of the connecting peptide can be finely regulated so as to meet different requirements on the rigidity of the connecting peptide in the construction of the fusion protein.

The anti-VEGF and anti-TNF-alpha bispecific nano antibody fusion protein provided by the invention can be used for preventing or treating rheumatoid arthritis, and has the advantages of safety, reliability and strong specificity.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.

FIG. 1 is a graph of the ability of a fusion protein to stimulate proliferation of mouse mononuclear cells;

FIG. 2 shows the ability of the bispecific nanobody fusion protein VEGF to bind to tumor cells Raji;

FIG. 3 shows the ability of the bispecific nanobody fusion protein TNF-alpha to bind to tumor cells Raji;

FIG. 4 is a graph showing the detection of the ability of the bispecific nanobody fusion proteins VEGF and TNF-alpha to bind to tumor cells Raji.

Detailed Description

Reference will now be made in detail to various exemplary embodiments of the invention, the detailed description should not be construed as limiting the invention but as a more detailed description of certain aspects, features and embodiments of the invention.

It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Further, for numerical ranges in this disclosure, it is understood that each intervening value, between the upper and lower limit of that range, is also specifically disclosed. Every smaller range between any stated value or intervening value in a stated range and any other stated or intervening value in a stated range is encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included or excluded in the range.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference herein for the purpose of disclosing and describing the methods and/or materials associated with the documents. In case of conflict with any incorporated document, the present specification will control.

It will be apparent to those skilled in the art that various modifications and variations can be made in the specific embodiments of the present disclosure without departing from the scope or spirit of the disclosure. Other embodiments will be apparent to those skilled in the art from consideration of the specification. The description and examples are intended to be illustrative only.

As used herein, the terms "comprising," "including," "having," "containing," and the like are open-ended terms that mean including, but not limited to.

Methods of making bispecific antibodies

Bispecific antibodies of the invention can be prepared by any method known in the art. Early methods for constructing bispecific antibodies include chemical cross-linking methods or hybrid or tetravalent tumor methods (e.g., Staerz UD et al, Nature,314:628-31, 1985; Milstein C et al, Nature,305:537-540, 1983; Karpovsky B et al, J.Exp.Med.,160:1686-1701, 1984). The chemical coupling method is to link 2 different monoclonal antibodies together by means of chemical coupling to prepare the bispecific monoclonal antibody. For example the chemical binding of two different monoclonal antibodies, or for example the chemical binding of two antibody fragments, such as two Fab fragments. The hybrid-hybridoma method is to produce bispecific monoclonal antibodies by means of cell-hybrid or triple-hybrid hybridomas obtained by fusing established hybridomas or established hybridomas with lymphocytes obtained from mice. Although these techniques are used to make biabs, various problems arise that make such complexes difficult to use, such as generating a mixed population containing different combinations of antigen binding sites, difficulties in protein expression, the need to purify the BiAb of interest, low yields, high production costs, and the like.

A recent approach is to utilize genetically engineered constructs that are capable of producing homogeneous products of a single BiAb without the need for extensive purification to remove unwanted side products. Such constructs include tandem scFv, anti-antibodies, tandem antibodies, double variable domain antibodies, and heterodimerization using motifs such as Ch1/Ck domain or DNLTM (Chames & Baty, curr. Opin. drug. Discov. Devel.,12: 276-. Related purification techniques are well known.

Antibodies can also be produced using the single lymphocyte antibody method by cloning and expressing immunoglobulin variable region cDNAs produced by a single lymphocyte selected for the production of specific antibodies, such as those described by Babcook J et al, Proc. Natl. Acad. Sci. USA.93: 7843-; WO 92/02551; the methods described in WO 2004/051268 and WO 2004/106377.

Antigenic polypeptides for the production of, for example, antibodies for immunization of a host or for panning, such as for phage display (or yeast cell or bacterial cell surface expression) can be prepared by methods well known in the art from genetically engineered host cells containing expression systems, or they can be recovered from natural biological sources. For example, nucleic acid encoding one or both polypeptide chains of a bispecific antibody can be introduced into a cultured host cell by a variety of known methods (e.g., transformation, transfection, electroporation, bombardment with nucleic acid-coated microparticles, etc.). In some embodiments, the nucleic acid encoding the bispecific antibody may be inserted into a vector suitable for expression in a host cell prior to introduction into the host cell. Typically the vector will contain sequence elements that enable expression of the inserted nucleic acid at the RNA and protein levels.

Such carriers are well known in the art, and many are commercially available. The host cell containing the nucleic acid can be cultured under conditions that enable the cell to express the nucleic acid, and the resulting BiAb can be collected from the cell population or culture medium. Alternatively, the BiAb may be produced in vivo, for example, in plant leaves and in avian eggs, or in mammalian milk.

Various cultured host cells that may be used include, for example, prokaryotic cells, eukaryotic cells, bacterial cells (such as E.coli or Bacillus stearothermophilus), fungal cells (such as Saccharomyces cerevisiae or Pichia pastoris), insect cells (such as Lepidoptera insect cells including Spodoptera frugiperda cells), or mammalian cells (such as Chinese Hamster Ovary (CHO) cells, NS0 cells, hamster kidney (BHK) cells, monkey kidney cells, Hela cells, human hepatocellular carcinoma cells, or 293 cells, among others).

Bispecific antibodies can be prepared by immunizing a suitable subject (e.g., a rabbit, goat, mouse, or other mammal, including transgenic and knockout mammals as described above) with an immunogenic preparation of a bispecific antigen. Suitable immunogenic preparations may be, for example, chemically synthesized or recombinantly expressed bispecific antigens. The formulation may further comprise an adjuvant, such as freund's complete or incomplete adjuvant or similar immunostimulatory compound. Furthermore, when used to prepare antibodies, particularly by means of in vivo immunization, the bispecific antigens of the invention may be used alone or, preferably, as conjugates with carrier proteins. Such methods of boosting antibody responses are well known in the art. Depending on the antibody desired, different animal hosts may be used for in vivo immunization. A host that expresses a useful endogenous antigen itself, or a host that has been rendered deficient in a useful endogenous antigen, may be used.

Bispecific antibodies or nucleic acids or polynucleotides encoding the antibodies of the application or pharmaceutical compositions or combination therapies play a key role in the pathology associated with a variety of diseases including immune and inflammatory factors. Such diseases include, but are not limited to, rheumatoid arthritis.

EXAMPLE 1 construction of fusion proteins

The invention constructs the anti-VEGF and TNF-alpha bispecific nano antibody fusion protein containing the connecting peptide. The DNA sequences encoding the anti-VEGF antibody and the anti-TNF-alpha antibody are linked by the DNA sequence of the linker peptide to form a fusion gene sequence. Preferably, they are all codon-preferred by CHO cells that have been artificially optimized. Preferably using chemical synthesis methods.

In order to insert the target fragment of the fusion gene obtained above into a specific site of an expression vector, a restriction enzyme site was inserted into each of the 5 'and 3' ends of the synthesized fragment, SpeI and EcoRI, respectively. And (3) carrying out enzyme digestion on the fusion protein gene after sequencing verification by using corresponding restriction enzyme, and then inserting the fusion protein gene into corresponding enzyme digestion sites of the modified expression plasmid PXY1A1 by using PCDNA3.1 as a template to obtain the fusion protein high expression plasmid.

The PXY1a1 plasmid contains but is not limited to the following important expression components:

1) human cytomegalovirus early promoter and enhancer required for high exogenous expression of mammalian cells;

2) a dual selection marker, kanamycin resistance in bacteria and G418 resistance in mammalian cells;

3) the murine dihydrofolate reductase (DHFR) gene expression cassette, Methotrexate (MTX) co-amplifies the fusion gene and the DHFR gene when the host cell is DHFR gene deficient.

The fusion protein expression plasmid is transfected into a mammalian host cell line, preferably a DHFR enzyme deficient CHO cell in order to obtain a stable high level of expression. Two days after transfection, the medium was changed to a selection medium containing 0.6mg/mL G418, cells were seeded at a concentration (5000-. Transfectants resistant to the selection were selected using ELISA assays. Wells producing high levels of fusion protein were subcloned by limiting dilution of 96-well culture plates.

For fusion proteins with good multi-party verification effect, in order to realize higher-level expression, DHFR genes inhibited by MTX drugs are preferably used for co-amplification. The transfected fusion protein gene was co-amplified with the DHFR gene in growth medium containing increasing concentrations of MTX. The obtained high-expression monoclonal cell strain is firstly subjected to fed-batch culture in a shake flask or a 5-liter fermentation tank, and then fusion Protein is purified by a Protein A affinity chromatographic column and other ion exchange chromatographic columns.

Example 2 fusion protein preparation and characterization

The stably expressing cell line obtained in example 1 was subjected to shake flask fed-batch culture for 10-14 days, purified by four steps of Protein A affinity chromatography, multidimensional mode chromatography, anion exchange chromatography and molecular sieve chromatography, and then activated by a solution incubation self-activation method. SDS-PAGE protein electrophoresis detection shows that under the reducing condition, the unactivated FP-A2 has two obvious bands respectively near 70-85kDa and 40kDa, indicating that the degraded fragment exists, accounting for about 20-30%; under non-reducing conditions, the purified protein migrated to approximately 130kDa with a partial >200kDa band, indicating that partial fusion protein polymerization occurred. The unactivated FP-A3 was a single-stranded molecule approaching 100kDa under reducing conditions, with no heterobands, and the partially purified protein migrated to >200kDa under non-reducing conditions, indicating that FP-A3 was all multimeric. The unactivated FP-A1 has a single-stranded molecule of 100-110kDa under reducing conditions, no significant bands, and the purified protein migrates to 150kDa under non-reducing conditions. The activated FP-A1 presents two clear bands under reducing condition, namely 74.3KDa HC-L-CTPFc and 24.0KDa LC respectively, no other miscellaneous bands, and the purified protein migrates to 150kDa under non-reducing condition, which shows that the fusion protein FP-A1 is not obviously degraded and has no obvious polymerization phenomenon, and has higher thermodynamic stability and stronger anti-protease hydrolysis capability. This example shows that the presence of CTP rigid units in the linker peptide increases the stability of the fusion protein, is not prone to degradation, and reduces polymer formation.

Example 3

The stably expressing cell line obtained in example 1 was subjected to shake flask feeding culture for 12-14 days, purified by Protein A affinity chromatography, and both fusion proteins were 95% pure and molecular size was expected to be suitable for activity analysis. The in vitro bioactivity assay of the fusion protein was as follows: after activation of mouse spleen-derived mononuclear cells by Canavalid protein A (ConA), 100. mu.L of the cells were seeded in a 96-well plate, followed by addition of a series of concentration gradients of FP-D1 and FP-D2 at 37 ℃ with 5% CO₂After 72 hours of culture, 20. mu.L of MTT reagent was added, the culture was continued for 4 hours, and after the medium was aspirated, 100. mu.L of dimethyl sulfoxide (DMSO) was added to each well, and the absorbance at 492nm was measured to determine the proliferation of the cells. Three replicates per treatment were set up and assayed twice per replicate, with recombinant IL-7 as a positive control and media as a negative control. FIG. 1 shows the ability of the fusion protein to stimulate proliferation of mouse mononuclear cells. According to the drawn dose response curve, half of the fusion protein can be obtainedEffective concentration values (EC50) were 0.039 and 0.048nM, respectively.

Example 4

Determination of binding Activity of bispecific antibodies to Effector and target cells (FACS)

Raji cells (Shanghai academy of sciences cell bank) which are tumor cells positive for CD19 expression are cultured, and the cells are collected by centrifugation. The collected cells were resuspended in 1% PBSB to adjust the cell density to 2X 10⁶one/mL, 100. mu.l (2X 10) per well in a 96-well plate⁵Individual cells), blocked at 4 ℃ for 0.5 h. Centrifuging the closed cells, removing supernatant, adding the diluted bispecific antibody with a series of concentrations, and incubating at 4 ℃ for 1 h; centrifuging to remove supernatant, washing with 1% BSA in PBS (PBSB) for 3 times, adding diluted AF 647-labeled goat anti-human IgG antibody, and incubating at 4 deg.C in dark for 1 h; the supernatant was centrifuged off, washed twice with 1% PBSB, resuspended in 100. mu.l of 1% Paraformaldehyde (PF) per well and the signal intensity was measured by flow cytometry. The mean fluorescence intensity was taken as the Y-axis and the antibody concentration as the X-axis, and the EC50 value for the bispecific antibody binding to tumor cells Raji was calculated by analysis with the software GraphPad.

The results show that bispecific antibodies of different structures and over-expressed tumor cells have good binding activity. Fig. 2, fig. 3 and fig. 4 show binding curves of bispecific antibodies of different structures and tumor cells Raji.

The above-described embodiments are merely illustrative of the preferred embodiments of the present invention, and do not limit the scope of the present invention, and various modifications and improvements of the technical solutions of the present invention can be made by those skilled in the art without departing from the spirit of the present invention, and the technical solutions of the present invention are within the scope of the present invention defined by the claims.

Claims

1. An anti-VEGF and TNF- α bispecific nanobody fusion protein comprising an anti-VEGF antibody or VEGF receptor-Fc fusion and an anti-TNF- α polypeptide, and a linker peptide for linking the anti-VEGF antibody or VEGF receptor-Fc fusion and the anti-TNF- α polypeptide; the linker peptide consists of a flexible peptide comprising 1 or more flexible units and a rigid peptide comprising one or more rigid units.

2. The anti-VEGF and TNF-a bispecific nanobody fusion protein of claim 1, wherein the flexible unit amino acid composition has a general structural formula of (GS) x (GGS) y (GGGS) z (GGGGS) m, wherein x, y, z and m are integers greater than or equal to 0, and x + y + z + m is greater than or equal to 1.

3. The anti-VEGF and TNF- α bispecific nanobody fusion protein of claim 1, wherein the rigid unit is selected from the following sequences:

(1)SPSKKAPAPSLPLPSRLGGPSGTPPLPQ；

(2)SAGSKKPGPS。

4. the anti-VEGF and TNF- α bispecific nanobody fusion protein of claim 1, wherein the rigid peptide is C-terminal to the flexible peptide.

5. The anti-VEGF and TNF- α bispecific nanobody fusion protein of claim 1, wherein the flexible unit is selected from the group consisting of:

(1)GSYHKNYALPPQSKKALLRFQDSLK；

(2)ARLFGPSSLLPQQAAGSRLGSGGRRP。

6. a polynucleotide encoding the anti-VEGF and TNF- α bispecific nanobody fusion protein of any one of claims 1-5.

7. An expression vector comprising the polynucleotide of claim 6.

8. A host cell transfected with the expression vector of claim 7.

9. A method of preparing the anti-VEGF and TNF- α bispecific nanobody fusion protein of any one of claims 1 to 5, comprising culturing the host cell of claim 8.

10. Use of the anti-VEGF and TNF- α bispecific nanobody fusion protein of any one of claims 1 to 5, the polynucleotide of claim 6, the expression vector of claim 7 or the host cell of claim 8 in the manufacture of a medicament for the treatment and/or prevention of rheumatoid arthritis.