EP0497833A1

EP0497833A1 - C1 inhibitor muteins and uses thereof

Info

Publication number: EP0497833A1
Application number: EP90915919A
Authority: EP
Inventors: Eric Eldering; Lucien Aarden
Original assignee: Stichting Centraal Laboratorium Van de Bloedtransfusiedienst Van; Cetus Corp
Current assignee: STICHTING CENTRAAL LABORATORIUM VAN DE BLOEDTRANSF
Priority date: 1989-10-27
Filing date: 1990-10-22
Publication date: 1992-08-12
Also published as: JPH05503001A; CA2071871A1; WO1991006650A1; AU6611290A; AU658560B2

Abstract

Composition consistant en des mutéines d'inhibiteur C1 ayant une activité biologique semblable à l'inhibiteur de C1, mais avec une plus grande résistance au clivage protéolytique, rendant ainsi ces mutéines utiles comme agents anti-inflammatoires, de préférence pour le traitement ou la prévention de la septicémie.Composition consisting of C1 inhibitor muteins having biological activity similar to C1 inhibitor, but with greater resistance to proteolytic cleavage, thus making these muteins useful as anti-inflammatory agents, preferably for treatment or prevention sepsis.

Description

Cl INHIBITOR MUTEINS AND USES THEREOF

This invention is in the area of molecular biologyΛmmunology, and presents genetically engineered constructs of Cl inhibitor, termed Cl inhibitor muteins, that are resistant to proteolytic attack. The muteins have considerable applications, preferably as anti-inflammatory agents and more preferably for the prophylactic or therapeutic treatment of sepsis.

In the United States alone nosocomial bacteremia develops in about 194,000 patients, and of these about 75,000 die. Maki, D.G., 1981, Nosocomial Infect.. (Dikson, R.E., Ed.), page 183, Yrke Medical Books, U.S.A.. Most of these deaths are attributable to six major gram-negative bacilli, and these are Pseudomonas aeruginosa, Escherichia coli, Proteus, Klebsiella, Enterobacter and Serratia. The current treatment for bacteremia is the administration of antibiotics which, unfortunately, have limited effectiveness.

The precise pathology of bacteremia is not completely elucidated, nevertheless, it is known that bacterial endotoxins, lipopolysaccharides (LPS), are the primary causative agent. LPS consist of at least three significant antigenic regions, the lipid A, core polysaccharide, and O-specific polysaccharide. The latter is also referred to as O- specific chain or simply O-antigen. The O-specific chain region is a long-chain polysaccharide built up from repeating polysaccharide units. The number of polysaccharide units differs among different bacterial species and may vary from one to as many as six or seven monosaccharide units. While the O-specific chain varies among different gram-negative bacteria, the lipid A and core polysaccharides are similar if not identical.

Since LPS plays a key role in sepsis, a variety of approaches has been pursued to neutralize its activity. Presently, there is considerable work which suggest that antibody to LPS will soon be a valuable clinical adjunct to the standard antibiotic therapy.

LPS initiates a cascade of biochemical events that eventually causes the death of the patient. It is widely believed that the second event, after the introduction of LPS, is the production of tumor necrosis factor (TNF) as a result of LPS stimulation of macrophage cells. Thus, considerable effort has been expended to produce neutralizing antibody to TNF, or other molecules that could inhibit its septic effects. It is likely that antibody to TNF will have valuable clinical applications. Tracey, el al_*, 1987. Nature. 330:662. Sepsis caused by gram-negative bacteria is thought to involve activation of the complement system and causes a depletion of various complement component. One component of a complement system , C5a, causes the aggregation of neutrophils and the aggregates are thought to embolize and cause ischemia. Siegel, J., 1981, Ann. Rev. Med..22:175. It has been proposed that C5a is thus responsible for the observed organ failure phenomena in sepsis. Cl is a plasma glycoprotein with a molecular weight of about 105,000 and is a member of the super family of serine protease inhibitors which include such members as αl-antitrypsin, αl-antiplasmin, antithrombin HI, and plasminogen activator inhibitor types I and II. One mechanism by which the activator components of the complement system are controlled is by the Cl inhibitor. The Cl inhibitor is known to inhibit activating components of the classical pathway of complement (C lr and C 1 s) and the intrinsic coagulation system (Factor XIa, Factor Xlla, and Kallikrein). Further, Cl inhibitor has been shown to interact with the fϊbrinolytic components plasmin and tissue plasminogen activator.

Cl inhibitor is susceptible to proteolytic cleavage by so called non-target proteases, particularly lysosomal serine protease elastase. Browere, M. and Harpel, P., 1982, J. Biol. Chem.. 257:9849. This enzyme is released from polymorphonuclear leukocytes and is present in the circulation of septaremic patients. It is thought that the decrease in the concentration of coagulation factors observed in these patients may, in part, be the result of proteolysis by leukocyte elastase of Cl inhibitor. It will be appreciated, that a possible prophylactic/therapeutic approach to treating sepsis would be to genetically engineer Cl inhibitors that are resistant to proteolytic cleavage and administer these to patients that are at risk of contracting sepsis, or that are already septic.

The life threatening nature of sepsis mandates the identification and development of additional therapeutics or prophylactics, both antibody based or otherwise, that may be efficaciously applied in the treatment of sepsis.

In its most general form, the invention described herein presents Cl inhibitor muteins, methods of constructing the muteins, and applications of the muteins, preferably as anti-inflammatory agents and more preferably for the prophylactic or therapeutic treatment of sepsis.

A second object of the invention described herein relates to Cl inhibitor muteins that are both elastase resistant, and that maintain the capacity to covalently bind to, and inactivate components of the complement system.

A third object of the invention is a description of Cl inhibitor muteins that have amino acids at positions 440 and/or 442 mutated to another suitable amino acid, or deleted, that are both elastase resistant, and that maintain the capacity to covalently bind to, and inactivate components of the complement system.

A fourth object of the invention is a description of Cl inhibitor muteins that display differential sensitivity to proteases and inhibitory activity depending on the type of amino acid that is substituted for amino acids at positions 440 and/or 442.

A fifth object of the invention is a description of Cl inhibitor muteins that exhibit differential inhibitory activity towards various substrates depending on the type of amino acid that is substituted for amino acids at positions 440 and/or 442.

Further, the invention concerns the prophylactic or therapeutic use of Cl inhibitor muteins as anti-inflammatory medicaments, and preferably for the prophylactic or therapeutic treatment of sepsis.

These and further objects of the invention will become apparent after a consideration of the detailed description of the invention shown below.

Figure 1 shows the cDNA sequence corresponding to recombinant Cl inhibitor. Figure 2 schematically presents a generalized assay procedure for determining the inhibitory or protease sensitivity of the Cl muteins.

Figure 3 shows the degree of inhibitory activity (complex formation) and protease sensitivity (inactivation) of Cl muteins to Cls and Kallikrein.

Figure 4 shows the degree of inhibitory activity (complex formation) and protease sensitivity (inactivation) of Cl muteins to B-12a and plasmin.

Figure 5 shows the amount of neutrophil elastase needed for 50% inhibition of several Cls inhibitor muteins.

1. Definitions

To facilitate understanding the nature and scope of applicant's invention, several definitions regarding various aspects of the invention are presented below. It will be understood, however, that these definitions are general in nature, and encompassed within the definitions are meanings well known to those skilled in the art.

Sepsis is herein defined to mean a disease resulting from gram-positive or gram- negative bacterial infection, the latter primarily due to the bacterial endotoxin, lipopolysaccharide (LPS). It can be induced by at least the six major gram-negative bacilli and these are Pseudomonas aeruginosa, Escherichia coli, Proteus, Klebsiella, Enterobacter and Serratia.

By Cl inhibitor is meant a plasma glycoprotein with a molecular weight of about 105,000 that belongs to the super family of serine protease inhibitors. It inhibits activated components of the classical pathway of complement, Clr and Cls, and the intrinsic coagulation system, factor XIa, factor Xlla, and Kallikrein. Cl also interacts with plasmin and tissue plasminogen activator. Cl has the further property of itself being inactivated by proteases, notably elastase. It will, or course, be understood that intended to come within the scope of the definition of the Cl inhibitor are fragments of the molecule that maintain biologically activity. By Cl inhibitor mutein is meant a molecule that has the biological activity of

Cl inhibitor, although to different degrees as exemplified by the data of the invention, and is particularly resistant to proteolytic attack.

Several patents/patent applications and scientific references are referred to below. The instant invention draws on some of the material and methods shown in these references, and thus it is intended that all of the references, in their entirety, be incorporated by reference.

2. Cl Inhibitor Muteins

Cl inhibitor has been cloned and expressed and thus is readily available to the practitioner to perform the herein described mutagenesis. For example, cloning and expression is described by Bock, el al., 1986, Biochemistry. 2^:4292. The cDNA sequence is shown in Figure 1. Further, Eldering, ei -. 1988, J. Biol. Chem.. 2-52:11776, show a Aat ϋ-Haell Cl inhibitor cDNA fragment that encodes the entire molecule. This fragment can be manipulated using the procedures described below to generate the Cl inhibitor muteins.

A. Mutein Construction— General Procedures

Construction of suitable vectors containing the desired coding and control sequences for the Aat II-Haell Cl inhibitor cDNA fragment employs standard ligation and restriction techniques which are understood in the art. Isolated plasmids, DNA se¬ quences, or synthesized oligonucleotides are cleaved, tailored, and religated in the form desired.

More specifically, site specific DNA cleavage is performed by treating with the suitable restriction enzyme (or enzymes) under conditions which are generally understood in the art, and the particulars of which are specified by the manufacturer of these commercially available restriction enzymes. See, e.g., New England Biolabs, Product Catalog. In general, about 1 μg of plasmid or DNA sequence is cleaved by one unit of enzyme in about 20 λ of buffer solution; in the examples herein, typically, an excess of restriction enzyme is used to insure complete digestion of the DNA substrate. Incubation times of about one hour to two hours at about 37°C are workable, although variations can be tolerated. After each incubation, protein is removed by extraction with phenol/chloroform, and may be followed by ether extraction, and the nucleic acid recovered from aqueous fractions by precipitation with ethanol and resuspension in 10 mM Tris, 1 mM EDTA, pH 7.5. If desired, size separation of the cleaved fragments may be performed by polyacrylamide gel or agarose gel electro- phoresis using standard techniques. A general description of size separations is found in Methods in Enzvmologv. 1980, 6^:499-560.

Restriction cleaved fragments may be blunt ended by treating with the large fragment of E. coli DNA polymerase I (Klenow) in the presence of the four deoxy- nucleotide triphosphates (dNTPs) using incubation times of about 15 to 25 minutes at 20 to 25°C in 50 mM Tris pH 7.6, 50 mM NaCl, 6 mM MgCl₂, 6 mM DTT and 5-10 μM dNTPs. The Klenow fragment fills in at 5' sticky ends but chews back protruding 3' single strands, even though the four dNTPs are present. If desired, selective repair can be performed by supplying only one of the, or selected, dNTPs within the limitations dictated by the nature of the sticky ends. After treatment with Klenow, the mixture is extracted with phenol/chloroform and ethanol precipitated followed by running over a Sephadex G-50 spin column. Treatment under appropriate conditions with S 1 nuclease results in hydrolysis of any single-stranded portion.

Synthetic oligonucleotides are prepared by the triester method of Matteucci et al_. 1981, J. Am. Chem. Soc, 103:3185, or using commercially available automated oligonucleotide synthesizers. Kinasing of single strands prior to annealing or for labelling is achieved using an excess, e.g., approximately 10 units of polynucleotide kinase to 0.1 nmole substrate in the presence of 50 mM Tris, pH 7.6, 10 mM MgC12, 5 mM dithiothreitol, 1-2 mM ATP, 1.7 pmoles γ32P-ATP (2.9 mCi/mmole), 0.1 mM spermidine, 0.1 mM EDTA. Ligations are performed in 15-30 λ volumes under the following standard conditions and temperatures: 20 mM Tris-Cl pH 7.5, 10 mM MgCl₂, 10 mM DTT, 33 μg/ml BSA, 10 mM-50 mM NaCl, and either 40 μM ATP, 0.01-0.02 (Weiss) units T4 DNA ligase at 0°C (for "sticky end" ligation) or 1 mM ATP, 0.3-0.6 (Weiss) units T4 DNA ligase at 14°C (for "blunt end" ligation). Intermolecular "sticky end" ligations are usually performed at 33-100 μg/ml total DNA concentrations (5-100 nM total end concentration). Intermolecular blunt end ligations (usually employing a 10-30 fold molar excess of linkers) are performed at 1 μM total ends concentration.

In vector construction employing "vector fragments", the vector fragment is commonly treated with bacterial alkaline phosphatase (BAP) in order to remove the 5' phosphate and prevent religatioi; of the vector. BAP digestions are conducted at pH 8 in approximately 150 mM Tris, in the presence of Na+ and Mg+2 using about 1 unit of BAP per μg of vector at 60°C for about 1 hour. In order to recover the nucleic acid frag¬ ments, the preparation is extracted with phenol/chloroform and ethanol precipitated and desalted by application to a Sephadex G-50 spin column. Alternatively, religation can be prevented in vectors which have been double digested by additional restriction enzyme digestion of the unwanted fragments.

For portions of vectors derived from cDNA or genomic DNA which require sequence modifications, site specific primer directed mutagenesis is used. This is conducted using a synthetic primer oligonucleotide complementary to a single stranded phage DNA to be mutagenized except for limited mismatching, representing the desired mutation. Briefly, the synthetic oligonucleotide is used as a primer to direct synthesis of a strand complementary to the phage, and the resulting double-stranded DNA is transformed into a phage-supporting host bacterium. Cultures of the transformed bacteria are plated in top agar, permitting plaque formation from single cells which harbor the phage. Theoretically, 50% of the new plaques will contain the phage having, as a single strand, the mutated form; 50% will have the original sequence. The resulting plaques are hybridized with dnased synthetic primer at a temperature which permits hybridization of an exact match, but at which the mismatches with the original strand are sufficient to prevent hybridization. Plaques which hybridize with the probe are then picked, cultured, and the DNA recovered. Details of site specific mutation procedures are described below in specific examples.

Correct ligations for plasmid construction are confirmed by first transforming E. _____ strain MM294 obtained from E. C_QH Genetic Stock Center, CGSC #6135, or other suitable host with the ligation mixture. Successful transformants are selected by ampicillin, tetracycline or other antibiotic resistance or using other markers depending on the mode of plasmid construction, as is understood in the art. Plasmids from the transformants are then prepared according to the method of Clewell, D.B., gj; al_. 1969, Proc. Natl. Acad. Sci. (USA). 62:1159, optionally following chloramphenicol amplifi¬ cation (Clewell, D.B., 1972, J. Bacteriol.. Hβ:667). The isolated DNA is analyzed by restriction and/or sequenced by the dideoxy method of Sanger, F., el al., 1977, Proc. Natl. Acad. Sci. (USA). 24:5463 as further described by Messing el al-, 1981, Nucleic Acids Res..2:309, or by the method of Maxam __t al*, 1980, Methods in Enzymology , £2:499.

Depending on the host cell used, transformation is done using standard techniques appropriate to such cells. The calcium treatment employing calcium chloride, as described by Cohen, S.N., Proc. Natl. Acad. Sci. (USA) (1972) £2:2110, or the RbC_₂ method described in Maniatis £t al., Molecular Cloning: A Laboratory Manual (1982) Cold Spring Harbor Press, p. 254 was used for procaryotes or other cells which contain substantial cell wall barriers. For mammalian cells without such cell walls, the calcium phosphate precipitation method of Graham and Van der Eb, Virology , 1978, 52:546 is preferred. Host strains used in cloning and expression herein are as follows. For cloning and sequencing, E. coli strain HB 101 may be used as the host. For Ml 3 phage recombinants, E. cjpϋ strains susceptible to phage infection, such as E.£oJi K12 strain DG98 are employed. The DG98 strain has been deposited with ATCC 13 July 1984 and has accession number 1965. A preferred expression system for the Cl inhibitor muteins is the COS-lcell /pSVL vector system shown by Eldering __χ__\., 1988, Journal of Biological Chemistry. 263: 11776. pS VL (Pharmacia, Uppsala, Sweden) consists of the SV40 origin of replication, the SV40 late promoter, and the VP1 intron in front of a polylinker followed by the SV40 late polyadenylation signal, fused to a pBR322 fragment containing the origin of replication and ampicillin resistance gene. Mutagenesis can be carried out using any number of procedures known in the art. These techniques are described by Smith, 1985, Annual Review of Genetics. 12:423, and modifications of some of the techniques are described in Methods in Enzymology. 154. part E, (eds.) Wu and Grossman (1987), chapters 17, 18, 19, and 20. The preferred procedure is a modification of the Gapped Duplex site-directed mutagenesis method which is described by Kramer, el a!-, in chapter 17 of volume 154 of Methods in Enzvmologv. above; and by Kramer ej al., 1984, Nucleic Acids Research. 12:9441.

B. Mutein Construction - Preferred Procedures

Conventional Ml 3 mutagenesis methods involve annealing a short synthetic oligonucleotide to single stranded Ml 3 DNA having a cloned target coding sequence that is sought to be mutagenized. The oligonucleotide is almost, but not entirely complementary to the target sequence and has at least one mispaired nucleotide. After the annealing reaction, the rer -aining portion of the single stranded DNA must be filled in to give heteroduplex DNA that can be transfected into a suitable host cell which allows for the expression of the mutation. In the gapped duplex method, as described by Kramer, el al-. in chapter 17 of the Methods in Enzymology. a partial DNA duplex is constructed that has only the target region exposed, unlike the conventional methods which have the target region and the rest of the single stranded Ml 3 DNA exposed. Like the conventional methods, a short oligonucleotide is annealed to the target region, and extended and ligated to produce a heteroduplex. However, because only a small portion of single-stranded DNA is available for hybridization in the gapped duplex method, the oligonucleotide does not anneal to undesired sites within the M13 genome. This method has the additional advantage of introducing fewer errors during the formation of the heteroduplex since only a very small region of DNA on either side of the target region has to be filled in. More specifically, the gapped duplex method involves cloning the target Aat II-

Haell Cl inhibitor cDNA fragment into an appropriate M13 phage that carries selectable markers, such as, for example, the stop codon amber mutation. The latter allows for negative selection in a host cell that cannot suppress the effects of the mutation. Preferably the phage is M13mp9 which contains two amber codons in critical phage genes. Thus, the sequence that encodes Cl is cloned into M13mp9 amber+, and single stranded DNA is prepared therefrom using standard techniques. Next, double stranded replicative form DNA from M13 GAP, a genetically engineered M13 derivative that lacks the amber codons is cleaved with the appropriate restriction enzyme. The base sequence of M13 GAP is similar to M13mpl8, which lacks both the amber codons and the sequence between base pairs 6172 and 6323. This deletion flanks the multiple cloning sites of the M13mp series and generates a unique restriction site. Gapped duplex DNA is formed, using standard DNA/DNA hybridization techniques, consisting of single stranded DNA having the amber codons, and a second strand of DNA from digested Ml 3 GAP lacking both the amber codons and the Cl coding sequences. Thus, the only portion of the gapped duplex that is exposed is the Cl target sequence. The desired oligonucleotide(s) is annealed to the gapped duplex DNA , and any remaining gaps filled in with DNA polymerase and the nicks sealed with DNA ligase to produce a heteroduplex. As applied to the instant invention mutagenesis was performed with a mixture of oligonucleotides that code for 16 different muteins. The sequence of the degenerate oligonucleotide used to isolate P5 and P3 double mutants and the P5 leucine and valine single muteins is:

5' GCG GGC C(AG) (GC) AGA G (AG) (GC) GGC GGA G 3' The oligonucleotide is complementary to nucleotides 1412-1433 of Bock etal-_ above.

In addition to the above, several other single P3 muteins were obtained using the following oligonucleotides :

P3-ala 5' GGTGOGGGOGGCAGAGATGG 3'

P3-gly 5' GGTGOGGGCTCCAGAGATGG 3'

P3-arg 5' GGGTGOGGGCTCTAGAGATGGCG 3'

P3-leu 5' GOGGGCCAGAGAGATGG 3' P3-thr 5' GGGTGOGGGOGGTAGAGATGGCG 3'

The heteroduplex is transfected, preferably into a mismatch repair deficient host, and mixed phage produced. From the mixed phage population, phage carrying unmutated Cl DNA, which also have the amber mutations, can be selected against by infecting the mixed phage population into a host cell that cannot suppress the amber mutation. Clones can then be screened for phage that carry a Cl mutation, and the molecules sequenced to determine the position of the mutation. Clones were screened using a mixture of kinased degenerate oligonucleotides. Using the foregoing method, 11 Cl inhibitor muteins were produced.

Cl inhibitor mutein DNA fragments were excised from M13 with the appropriate restriction enzymes and cloned into a vector suitable for expression in COS cells. The vector is pSVL and is shown in Bock __t al-, above. Alternatively pCl-INH, also described by Bock ≤l al-, could be used.

SV40-transformed COS-1 monkey cells were grown in Iscove's Modified Dulbecco Cell Culture Medium containing penicillin and streptomycin. The media was supplemented with 10% v/v) heat-inactivated fetal calf serum. Transfection of the cells was performed essentially as described by Luthmann, and Magnusson, 1983, Nucleic Acids Research.5:1295. This consisted of incubating subconfluent COS-1 cells in the cell culture media for 90 minutes with supercoiled vector encoding Cl inhibitor mutein DNA (5-7.5 μg/ml) and DEAE-dextran (200 μg ml). After a 90 minute incubation period, the cells were washed twice with cell culture media, and incubated for an additional 2 hours with cell culture media containing 80 μg ml chloroquine. Two further washes were performed, and the cells incubated with cell culture media supplemented with 10% fetal calf serum. This media was replaced 24 hours later with serum free media. The latter media was harvested after 72 hours, centrifuged to remove cells and debris, and assayed for Cl inhibitor activity, as described below.

C. Assay for Cl Inhibitor Mutein Activities Figure 2 presents a generalized assay screening format for determining both the inhibitory (complex formation) or protease sensitivity (inactivation) of the Cl muteins.

The latter measures inactivation of the Cl inhibitor muteins by non- target proteases.

This procedure is also described by Eldering __t al-, 1988, in J. of Biological Chem..

263: 11776. Modifications of these methods are also known in the art. Generally, inhibitor activity of Cl muteins may be determined by measuring complex formation between the Cl inhibitor and a substrate. The preferred substrates are, of course, Cls, Kallikrein, B-12a, and plasmin. The Cl inhibitor, or Cl inhibitor muteins, inhibit the protease activity of the substrate by forming a covalent bond with the substrate. These molecules were purified by techniques known in the art, or as described by Liebermann, H., e l-, 1984, J. Mol. Biol.. 177:531 and Nuijens, J., et al., 1987. Immunology. 61:387. Many procedures are available for measuring the complex resulting from the interaction of the Cl inhibitor mutein and its target proteinase substrate, and include standard immunochemical, radiochemical, or elisa assays. Levin, M., eial., 1983, 1 Biol. Chem.. 258:6415, Nuijens, J., ξ al, 1987, Thromb. Haemost.. 58:778, de Agostini, 1985, PNAS. £2:5190. The procedures generally consist of contacting a Cl inhibitor mutein with a target substrate in solution to permit complex formation to occur, then separating the complex from uncomplexedreactants, and detecting the amount of complex formed. Other assays may be employed whereby the amount of reactants, that is, free Cl inhibitor mutein or target molecule, remaining in the reaction solution are measured after complex formation has occurred.

The preferred assay is a radioimmune assay based on the observation that functional Cl inhibitor muteins bind to activated target substrate, such as Cls. The assay can be performed in several ways, but preferably purified activated Cls is coupled to a solid matrix, preferably Sepharose 4B via cyanogen bromide as is known in the art. Coupled Cls is incubated in an appropriately buffered solution containing, if desired, a small amount of detergent, preferably Tween-20. The latter is used at a concentration of about 0.1% (w/v). The capacity of the Cl inhibitor muteins to complex with the target substrate can be detected using anti-Cl inhibitor mutein antibody. Alternatively, a radiolabelled second antibody can be used to detect the bound first antibody. The antibody may be polyclonal or monoclonal and is incubated for a sufficient time to permit detectible binding of the antibody to the Cl inhibitor to occur. After the appropriate washing steps are conducted whereby non-specifically bound radiolabelled antibody is separated from antibody bound to Cl inhibitor muteins, the amount of radioactivity associated with the latter is determined. In this way, and incorporating the appropriate controls in the assay scheme, the inhibitory capacity of the Cl muteins is determined.

Using similar approaches, the non-target protease sensitivity of the Cl inhibitor muteins may be determined. Numerous assays may be employed that measure the amount of intact Cl inhibitor mutein, or fragments that are derived from the muteins, remaining after exposure to protease. Many procedures are available for measuring the protease sensitivity of the Cl inhibitor muteins, and include standard immunochemical, radiochemical, or elisa assays. A solid phase assay is preferred whereby Cl inhibitor muteins are reacted with non-target protease bound to a solid matrix and the amount of proteolysis of the muteins measured by determining the amount of intact mutein remaining, or preferably by detecting fragments of the mutein. Alternatively, the Cl inhibitor mutein may be bound to a solid support matrix and this material subjected to proteolysis provided attachment of the mutein does not stericly interfere with protease accessability to the mutein .

An exemplary non-target protease that cleaves Cl is neutrophil elastase. Thus this enzyme may be coupled to CNBr treated Sepharose 4B, and incubated with a Cl inhibitor mutein, and the presence of proteoly tically cleaved C 1 mutein monitored usin a number of techniques. The preferred procedure is to pellet the Sepharose-coupled elastase, and measure the presence of cleaved Cl inhibitor in t^'*e supernatant using an antibody that recognizes this molecule. Such antibodies are available and are describe by Nuijens, el al., 1988, Blood. 22:1841. They may be attached to a solid matrix to facilitate separating the cleaved Cl inhibitor mutein from the other reactants. The Sepharose beads containing antibody having bound cleaved Cl mutein inhibitor are spun down, washed and separated from the supernatant containing uncleaved Cl inhibitor or cleaved but unbound fragments. Subsequently, the amount of bound cleaved Cl inhibitor can be determined using a second radiolabelled antibody that recognizes the cleaved molecule. Finally, the amount of radioactivity adherent to the Sepharose beads may be determined as an indication of the amount of cleavage resulting from elastase.

The general procedures for determining both the inhibitory or non-target protease sensitivity of the Cl inhibitor muteins are shown in Figure 1. The procedure involving Cls will be described briefly, the procedures for the other substrates is similar with modifications as noted by Eldering, 1988, J. Biological Chem.. 2£2:11776, and as shown by Nuijens el a!-, above.

As mentioned above, the radioimmune assay to determine the Cl inhibitor activity of the various muteins is based on the observation that functional Cl inhibitor mutein will bind to activated Cls. Thus, purified activated Cls is coupled to CNBr

Sepharose 4B and suspended in phosphate-buffered saline, pH 7.4 10 mM EDTA, an 0.1% (w/v) Tween-20. Next, 0.3 ml of this mixture containing 1.5 μg of activated Cls is incubated with various dilutions of the Cl inhibitor muteins for 5 hours. The Sepharose 4B beads are collected, extensively washed, and complexed Cl inhibitor mutein incubated (>4 hours) with 1251-polyclonal anti-Cl antibody. The antibody is described by Hack, et aL, above. The Sepharose beads are washed, and bound radioactivity determined using a LKB 1260 multigamma II gamma counter.

Inactivation of the Cl inhibitor muteins is determined as follows. Porcine pancreatic elastase is coupled to Sepharose 4B such that about 3.75 mg of elastase is coupled to 300 mg of Sepharose. The beads are suspended in phosphate buffered saline containing 10 mM EDTA, and 0.1% w/v Tween-20. Various amounts of Cl inhibitor muteins are incubated with 150 μl of Sepharose 4B suspension containing 5.6 mg of elastase in 500 μl of volume for 1 hour at room temperature. Subsequently, the mixture is centrifuged, and the supernatant assayed for the presence of inactivated Cl inhibitor mutein using KOK12 monoclonal antibody bound to Sepharose, and polyclonal i25I-anti-Cl-inhibitor antibodies, as described above. Figure 3 shows the degree of inhibitory activity (complex formation) and protease sensitivity (inactivation) of 11 Cl inhibitor muteins as assessed using Cls and Kallikrein as substrates and neutrophil elastase as the source of protease. Figure 4 shows the same data with the exception that the substrates were B-12a and plasmin. It is noteworthy that the 11 Cl inhibitor muteins exhibit considerable variation in inhibitor activity, and protease sensitive. This was a function of both the type of amino acid used to substitute for the wild type amino acid, and the substrates used to test for inhibitory activity.

The wild type Cl inhibitor has isoleucine and valine at positions 440 and 442, respectively. Mutations at position 440 and 442 are termed P₅ and P₃ muteins, respectively. The figures show that muteins altered only at P₃ (Ala, Gly, Arg, Leu or Thr substituted for Val) display different properties depending on the target protease used. When solid phase Cls is used, complex formation occurs in the order Arg = Gly<Ala<Leu<wild-type = Thr.

Further, it appears that two variants, P₅-leu:P₃-ala; andPs-leu:P₃-leu show significantly reduced susceptibility to inactivation. The amount of HNE needed for 50% inactivation, as determined by residual functional activity towards Cls, is increased by a factor 5 to 8 compared to wild type Cl inhibitor (Figure 5).

D. Cl Pegylated Muteins

The preferred embodiment Clmuteins consists of modified muteins that have a substantially longer in vivo circulating lifetime than the unmodified molecules. Favored modified Cl inhibitor muteins are those having a water soluble polymer bound to the muteins. Exemplary of such water soluble polymers are polyacrylic acid, and derivatives thereof, dextran, carboxymethylcellulose, polyethylene glycol, and polyoxyethylated glycerol. The preferred embodiment water soluble polymer is polyethylene glycol. It is disclosed in U.S. Patent No. 4,179,337, along with methods for binding polyethylene glycol to proteins. Polyethylene glycol modified IL-2 is shown in U.S. Patent No. 4,766,106. Using the compositions and procedures described in these two patents, polyethylene glycol modified Cl muteins are readily produced by those skilled in the art. E. Administration of Cl Muteins

It will be appreciated by those skilled in the art that the Cl muteins described herein can be administered to mammals, including humans, either alone or in combination with other anti-inflammatory agents, or they may be combined with various pharmaceutically acceptable diluents or carriers. Such are widely known to those skilled in the art and are formulated according to standard pharmaceutical practices.

Exemplary diluents include physiologic saline, or buffered saline, as well as Ringer's and dextrose injection fluid, and dextrose saline and lactated Ringer's injection or diluent solutions containing additional therapeutic agents, preferably antibiotics or antibody known to be efficacious in the treatment of sepsis. Such antibody would include those known to be beneficial for the therapeutic treatment of sepsis caused by different strains of bacteria, preferably Pseudomonas aeruginosa, Escherichia coli, Proteus, Klebsiella, Enterobacter and Serratia.

F. Therapeutic Application of Cl Inhibitor Muteins

One embodiment of the invention is the administration of an effective amount of the subject Cl inhibitor muteins to individuals that are at a high risk of developing sepsis or that have developed sepsis. An example of the former category are patients about to undergo surgery. While the mode of administration is not particularly important, parenteral administration is preferred because of the rapid progression of sepsis, and thus, the need to have the Cl inhibitor muteins compositions disseminate quickly throughout the body. The preferred mode of administration is to deliver an I.V. bolus slightly before, during, or after surgery. The dosage of the Cl inhibitors will normally be determined by the prescribing physician. It is to be expected that the dosage will vary according to the age, weight and response of the individual patient. Having generally described what the applicants believe their invention to be, presented below are examples that are illustrative of the scope of the invention. It will be appreciated by those skilled in the art that the examples are not intended to be construed as limiting the invention to the materials and methods shown as there are numerous substitutions that can be made therein without departing from the scope of the invention.

The present invention has been described with reference to specific embodiments. However, this application is intended to cover those changes and substitutions which may be made by those skilled in the art without departing from the spirit and the scope of the appended claims.

Claims

WE CLAIM:

1. Recombinant Cl inhibitor muteins.

2. The Cl inhibitor muteins of claim 1 , wherein said muteins are of human origin.

3. The Cl inhibitor muteins of claim 2, wherein said Cl inhibitor muteins have amino acid at position 440 of recombinant Cl inhibitor replaced or deleted.

4. The Cl inhibitor muteins of claim 3, wherein said Cl inhibitor muteins have amino acid at position 440 of recombinant Cl inhibitor replaced with neutral amino acids.

5. The Cl inhibitor muteins of claim 3, wherein said Cl inhibitor muteins have amino acid at position 440 of recombinant Cl inhibitor replaced with charged amino acids.

6. The Cl inhibitor muteins of claim 3, wherein said Cl inhibitor muteins have amino acid at position 440 of recombinant Cl inhibitor replaced with the charged amino acid arginine.

7. The Cl inhibitor muteins of claim 4, wherein said Cl inhibitor muteins have amino acid at position 440 of recombinant Cl inhibitor replaced with neutral amino acids selected from the group consisting of alanine, glycine, leucine, and threonine.

8. The Cl inhibitor muteins of claim 2, wherein said Cl inhibitor muteins have amino acid at position 442 of recombinant Cl inhibitor replaced.

9. The Cl inhibitor muteins of claim 3, wherein said Cl inhibitor muteins have amino acid at position 442 of recombinant Cl inhibitor replaced with neutral amino acids.

10. The Cl inhibitor muteins of claim 3, wherein said Cl inhibitor muteins have amino acid at position 442 of recombinant Cl inhibitor replaced with charged amino acids.

11. The Cl inhibitor muteins of claim 3, wherein said Cl inhibitor muteins have amino acid at position 442 of recombinant Cl inhibitor replaced with the charged amino acid arginine.

12. The Cl inhibitor muteins of claim 4, wherein said Cl inhibitor muteins have amino acid at position 442 of recombinant Cl inhibitor replaced with neutral amino acids selected from the group consisting of alanine, glycine, leucine, and threonine.

13. The Cl inhibitor muteins of claim 2, wherein amino acids at positions 440 and 442 of recombinant Cl inhibitor are replaced by neutral amino acids.

14. The Cl inhibitor muteins of claim 13, wherein amino acids at positions 440 and 442 of recombinant Cl inhibitor are replaced by neutral amino acid alanine and leucine, respectively.

15. The Cl inhibitor muteins of claim 13, wherein amino acids at positions 440 and 442 of recombinant Cl inhibitor are replaced by neutral amino acids alanine and valine, respectively.

16. The Cl inhibitor muteins of claim 13, wherein amino acids at positions 440 and 442 of recombinant Cl inhibitor are replaced by neutral amino acid leucine.

17. The Cl inhibitor muteins of claim 13, wherein amino acids at positions 440 and 442 of recombinant Cl inhibitor are replaced by neutral amino acids leucine and valine, respectively.

18. Recombinant DNA that encodes a molecule comprising Cl inhibitor mutein activity.

19. Recombinant DNA that encodes a molecule comprising C 1 inhibitor mutein activity as described in claim 7.

20. Recombinant DNA that encodes a molecule comprising - l inhibitor mutein activity as described in claim 12.

21. Recombinant DNA that encodes a molecule comprising Cl inhibitor mutein activity as described in claim 17.

22. A composition for the therapeutic or prophylactic treatment of sepsis comprising an effective amount of a biologically active Cl inhibitor mutein as described in claim 7.

23. A composition for the therapeutic or prophylactic treatment of sepsis comprising an effective amount of a biologically active Cl inhibitor mutein as described in claim 12.

24. A composition for the therapeutic or prophylactic treatment of sepsis comprising an effective amount of a biologically active Cl inhibitor mutein as described in claim 17.

25. A method for treating sepsis comprising administering an effective amount of the composition of claim 22 to a patient.

26. A method for treating sepsis comprising administering an effective amount of the composition of claim 23 to a patient.

27. A method for treating sepsis comprising administering an effective amount of the composition of claim 24 to a patient.