METHODS OF AND COMPOSITIONS FOR DIAGNOSING, MONITORING AND TREATING THE EARLY STAGES OF OSTEOARTHRITIS

Abstract: Methods of and compositions for early diagnosis, monitoring and treatment of osteoarthritis using monoclonal antibodies which specifically recognize antigenic determinants on atypical chondroitin sulfate/dermatan sulfate glycosaminoglycan chains in body tissues and fluids, which determinants are markers of osteroarthritis.

Description: METHODS OF AND COMPOSITIONS FOR DIAGNOSING, MONITORING AND TREATING THE EARLY STAGES OF OSTEOARTHRITIS FIELD OF THE INVENTION This invention relates to methods of and compositions for early diagnosis, monitoring and treatment of osteoarthritis using monoclonal anti¬ bodies which specifically recognize antigenic deter¬ minants on atypical chondroitin sulfate/dermatan sulfate glycosaminoglycan chains of cartilage pro- teoglycans from humans and animals with osteoarthri¬ tis, such atypical chains being markers of osteo¬ arthritis. BACKGROUND OF THE INVENTION Osteoarthritis is a degenerative process in joints characterized by functional deterioration, abrasion of articular cartilage, and formation of new bone at and around the joint surfaces. It is estimated to affect approximately 40 million adults in the United States alone. The disease is particu¬ larly prevalent in individuals over the age of 55 and with the longevity of the population increasing, it has become a disease of major concern to the medical community. In humans, osteoarthritis takes years to develop. As the disease progresses, the affected diseased cartilage literally wears away. At the present time, osteoarthritis cannot be diagnosed until quite late in the degenerative process. Current medical treatment therefore consists mainly of trying to reverse the later inflammatory stage of the disease. At this point, it is really too late to stop or reverse the degenerative process. It has long been acknowledged in the litera¬ ture that the events leading up to these late inflam¬ matory stages are the most important. Many drug companies have for example given up the idea of treating osteoarthritis with anti-inflammatory drugs and are now trying to discover and develop drugs that will treat the primary lesion or the early stages of the disease. However, assays to monitor the effectiveness of these drugs on the early stages of osteoarthritis are not available. Moreover, diagnosis of the disease in its early stages has also not been possible. Therefore, in a clinical setting, it cannot be determined which patients are affected by the disease in its earliest stages and thus, are candi¬ dates for such drugs and therapies. United States patent 4,704,356 refers to a potential marker for diagnosing osteoarthritis. It employs a quantitative immunoassay for keratan sul- fate, which is thought to be elevated in patients with osteoarthritis. This immunoassay is not satis¬ factory for the diagnosis of osteoarthritis. First, it detects an increased release of a normal tissue component without selectively, identifying a patho- logical process. More importantly, there is still much controversy in the field over whether the initial stages of the degenerative process are asso- ciated with an abnormally high or an abnormally low level of keratan sulfate. Finally, the method of the '356 patent is useful only prospectively, i.e., to confirm the presence of osteoarthritis. It has not been used to diagnose or track the disease in its earliest stages.' As a result, clinical assessment of osteo¬ arthritis is hampered by the lack of sound diagnostic criteria and the absence of means to detect and measure the active processes of joint damage. Because the disease is widespread, heterogeneous and slowly progressive, the need for definitive and reliable tests is paramount not only for diagnosis, but also for longitudinal assessment, epidemiology and drug development. SUMMARY OF THE INVENTION It is therefore an object of this invention to identify a characteristic marker of an early stage of osteoarthritis. It is a further object of this invention to use this marker to develop methods and compositions for diagnosing, monitoring and treating osteoarthritis. The present invention accomplishes these objects by demonstrating for the first time £hat atypical chondroitin sulfate or dermatan sulfate glycosaminoglycan chains of osteoarthritic cartilage proteoglycans are markers for and characterize the early stages of osteoarthritis. We believe that these markers contain subtle structural domains that are atypical to the common chondroitin sulfate or dermatan sulfate glycosaminoglycan chains found in normal mature cartilaginous tissues. In further embodiments of this invention, monoclonal antibodies that selectively recognize these atypical structures are produced for use in methods of and compositions for the diagnosis of the early stages of osteoarthritis. Another aspect of this invention provides methods of and compositions for the treatment of osteoarthritis using therapeutic drugs linked to the monoclonal antibodies of this invention. In this way the drug is specifically targeted to the diseased versus normal tissue. Yet another aspect of this invention is the use of these monoclonal antibodies in methods and compositions for monitoring the course of osteoarthri¬ tis and determining the effect of treatment thereof. * This embodiment is particularly useful in animal models to screen and test for drugs which prevent or treat the earliest stages of osteoarthritis. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 depicts densitometric scans of 5/6/3-B-3 immunoblots of proteoglycans from tibial, femoral and patella groove cartilage from normal and osteoarthritic knee joints of mature dogs 3 months after experimental osteoarthritis was induced. , Figure 2 depicts densitometric scans of 8/25/7-D-4 immunoblots of proteoglycan preparations from normal and osteoarthritic cartilage of mature dogs 3 months after experimental osteoarthritis was induced. Figures 3a and 3b depict densitometric scans of 5/6/3-B-3 immunoblots of proteoglycans from normal human cartilage. Figures 4a and 4b depict densitometric scans of 5/6/3-B-3 immunoblots of proteoglycans from osteo¬ arthritic human cartilage. DETAILED DESCRIPTION OF THE INVENTION In order that the invention described herein may be more fully understood, the following detailed description is set forth. Proteoglycans are major components of the extracellular matrix of cartilage and are responsible for the stiffness and elasticity of the tissue. Cartilage proteoglycans are complex macromolecules in which many glycosaminoglycan chains and oligo- saccharides are linked to an extended protein core. Five separate domains have been identified in the cartilage proteoglycan protein core: a highly folded globular region that forms the hyaluronate-bindiήg site, a second globular domain of unknown function that shares sequence homology with the hyaluronate binding region, a short extended keratan sulfate- rich region, a long extended chondroitin sulfate- bearing region, and a C-terminal globular domain that may possess lectin-like properties. Dermatan sulfate differs from chondroitin sulfate only in the presence of a variable portion of iduronate residues in the place of glucuronate residues. In this description and application, atypical chondroitin sulfate/dermatan sulfates are defined as chains that have subtle structural domains characteristic of osteoarthritis (but not normal cartilage tissue). Among these atypical chondroitin sulfate/dermatan sulfate chains are those that are specifically recognized by monoclonal antibodies 5/6/3-B-3 (human, dog and guinea pig cartilage proteoglycans) or 8/25/7-D-4 (dog and guinea pig cartilage proteoglycans). Other such atypical chondroitin sulfate/dermatan sulfate chains are those specifically recognized by the other mono¬ clonal antibodies of this invention. As described herein, our discovery and identification of these atypical chondroitin sulfate/dermatan sulfate chains and our recognition that they serve as specific markers for osteoarthri¬ tis have permitted us to develop methods of and com¬ positions for diagnosing early stages of osteoarthri¬ tis in mammals. Our discovery of these atypical chondroitin sulfate/dermatan sulfate chains has also permitted us to develop methods of and compositions for monitoring the course of osteoarthritis in mammals. Such monitoring is especially important in drug development and screening, and in following the course of a selected therapy in clinical applica¬ tions. For example, it is an important aspect of this invention that drug companies and other researchers may use the methods and compositions of this invention in animal models to search for and test drugs which prevent or treat the early stages of osteoarthritis. The compositions that are useful in the monitoring and diagnostic embodiments of this invention are characterized by monoclonal antibodies that are selectable using the following protocol: monoclonal antibodies are produced against the pro- teoglycans of cartilage extracts from a mammal suf¬ fering from osteoarthritis and screened for those (1) that selectively recognize proteoglycans of cartilage extracts from a mammal suffering from osteoarthritis (preferably the same mammal from which the antigen used to raise the antibody is derived), (2) that do not recognize or that recognize to a significantly lesser extent than in screen (1) proteoglycans of cartilage extracts from a mammal not suffering from osteoarthritis (preferably the same mammal as used in the first screening and more preferably the same mammal as used to derive the antigen and in the first screening) and (3) that do not recognize proteoglycans of cartilage extracts from a mammal suffering from- osteoarthritis, from which the chondroitin sulfate/dermatan sulfate chains have been completely removed by enzymatic or chemical treatment (again most preferably the same mammal from which the antigen used in raising the antibody . is derived and also the same mammal used in the first and second.screening) . In screen (1) and (2) above it is important that proteoglycans of cartilage extracts from a mammal suffering or not suffering from osteoarthritis are not treated with- chondroitinase, hyaluronidase or other enzymes that may cleave or otherwise modify the chain structure. Chondroitin sulfate/dermatan sulfate chains may be completely removed by enzymatic or chemical methods such as treatment with alkaline borohydride, anhydrous hydrogen fluoride or trifluoro methane sulfonic acid. Screen (3) serves to eliminate those antibodies recognizing proteoglycan antigens that are not part of chondroitin sulfate/dermatan sulfate chain structures. Among the antibodies selectable by this defined protocol are monoclonal antibodies 5/6/3-B-3, 8/25/7-D-4 and antibodies which are immunologically crossreactive with them (immunologically crossreactive being defined as the ability to bind to substantially the same epitopes on atypical chondroitin sulfate/der¬ matan sulfate chains). Prior to- this invention, monoclonal antibody 5/6/3-B-3 had been used to quantify normal chondroitin- 6-sulfated proteoglycans. This use of monoclonal antibody 5/6/3-B-3 requires that the tissue or sample be pretreated with chondroitinase or hyaluronidase, thereby cleaving the glycosaminoglycan chains to leave shortened chains characterized by the 5/6/3-B-3 epitope. Caterson et al. , "Monoclonal Antibodies As Probes For Elucidating Proteoglycan Structures and Function," In: Biology of Proteoglycans, ed. , T. Wight and R. Mecham, pp. 1-26, Academic Press, N.Y. (1987). In contrast, it is an essential feature of the methods and compositions according to this invention that the antibodies are employed without pretreatment of the tissue or sample with enzymes that cleave the glycosaminoglycan chains to leave shortened chains or with enzymes or chemicals that remove the entire chain. Monoclonal antibody 5/6/3-B-3 is available from ICN Biochemical in Cleveland, Ohio, or it may be prepared using Swarm rat chondrosarcoma pro¬ teoglycan core protein as antigen for immunization. It is the preferred monoclonal antibody of this invention. Without wishing to be bound by theory, we believe that monoclonal 5/6/3-B-3 detects a terminal glucuronic acid residue adjacent to N-acetyl galactosamine-6-sulfate at the non-reducing end of chondroitin sulfate chains in proteoglycans. Monoclonal antibody 8/25/7-D-4 can be produced using 17 day old embryonic chicken bone marrow proteoglycan as antigen. In contrast to mono¬ clonal antibody 5/6/3-B-3, enzymatic (chondroitinase or hyaluronidase) cleavage of the chondroitin sulfate/dermatan sulfate chains-to leave the shortened . chains eliminates the epitope recognized by this antibody. While not wishing to be bound by theory, we believe that monoclonal antibody 8/25/7-D-4 detects an epitope of chondroitin sulfate/dermatan sulfate chains distinct from that of 5/6/3-B-3. However, the specific biochemical characteristics of this epitope have not yet been identified. A sample of monoclonal hybridoma 8/25/7-D-4 has been deposited at In Vitro International, Inc., 611 P. Hammonds Ferry Road, Linthicum, Maryland 21090, on June 16, 1988, and has been assigned the accession number IVI 10173. Other antibodies of this invention that are diagnostic for early stages of osteoarthritis are preferably prepared as described above using proteoglycans of cartilage extracts from a mammal suffering from osteoarthritis as an antigen in standard (conventional) immunization procedures as described in Caterson et al. , "Monoclonal Antibodies As Probes For Elucidating Proteoglycan Structures and Function," In: Biology of Proteoglycans, ed. , T. Wight and R. Mecham, pp. 1-26, Academic Press, N.Y. (1987). The antibodies of this invention are then selected by screening the collection of mono- clonals produced against these antigens for those (1) that selectively recognize proteoglycans of cartilage extracts from a mammal suffering from osteoarthritis (preferably the same mammal from which the antigen used to raise the antibody is derived), (2) that do not recognize proteoglycans of cartilage extracts from a mammal not suffering, from osteo- arthritis (preferably the same mammal as used in the first screening and more preferably the same mammal as used to derive the antigen and in the first screen¬ ing) and (3) that do not recognize proteoglycans of cartilage extracts from a mammal suffering from osteoarthritis, from which the chondroitin sulfate/ dermatan sulfate chains have been completely removed by enzymatic or chemical treatment (again most prefer¬ ably the same mammal from which the antigen used raising the antibody is derived and the same mammal used in the first and second screening). According to the methods of this invention, the antibodies of the invention may be used to diagnose osteoarthritis in mammals using cartilagin¬ ous tissue, synovial fluid or. serum. However, because the atypical chondroitin sulfate/dermatan sulfate chains that we have discovered as characteristic markers for this disease are present in equilibrium throughout the body, they may be found in other body tissues and fluids as well, e.g., urine. The above described compositions are useful in various assays to diagnose or monitor the course of osteoarthritis. The fundamentals of such assays are well known and conventional in the art. They are useful in the various embodiments of this invention because of the specificities of the mono¬ clonal antibodies of this invention that characterize them. The diagnostic assays of this invention depend on the detection of an increased amount of atypical chondroitin sulfate/dermatan sulfate chains in a body fluid or tissue analyte. As used in this application, an increased amount is at least 2 fold over normal tissue or fluid. Most usually, the increased amount is between 2 and 150 fold. And more preferably, the increased amount is between 2 and 15 fold. When the compositions of this invention are used to monitor the progression of osteoarthritis or the effect or course of therapy,the assays depend on following the presence and amount of the atypical chondroitin sulfate/dermatan sulfate chains in a body fluid or tissue analyte. In this embodiment of the invention, the relative amount of such chains is compared with that of normal tissue or body fluid and diseased tissue or body fluid samples before treatment or earlier in time to determine the course of disease or treatment. One such assay, by way of example, is a radioimmunoassay as described by Ratcliffe and Hardingham, "Cartilage Proteoglycan Binding Region and Link Protein," Biochem J. , 213, pp. 371-78 (1983). In this particular assay system, synovial fluid samples may be analyzed in a competitive radioimmuno- assay using 125I-labelled proteoglycans containing the epitope specifically recognized by the monoclonal antibody of this invention as labelled antigen, with heat denatured, formalin fixed S. aureas as an immuno- precipitant. We may then quantitate the results by calibration with a standard proteoglycan antigen. In the preferred embodiment of this invention, where 5/6/3-B-3 is the monoclonal antibody, human articular • cartilage proteoglycans pretreated with chondroitinase would be radiolabelled. For assays using monoclonal antibody 8/25/7-D-4, 17- day old embryonic chicken bone marrow proteoglycans would be radiolabelled. An alternative assay to diagnose osteo¬ arthritis is characterized by the electrophoresis of samples of cartilage extracts on composite agarose/acrylamide slab gels. The extracts of cartilage and composite agarose/acrylamide gels may be, for example, prepared according to the method of Carney et al., "Electrophoresis of 35S-Labeled Proteoglycans on Polyacrylamide-Agarose Composite Gels and Their Visualization by Fluorography," Analyt. Biochem, 156, pp. 38-44 (1986), with a com¬ posite gel mixture of 1.2% (w/v) polyacrylamide and 0.6% (w/v) agarose. After electrophoresis, the proteoglycans are electrophoretically transferred onto nylon sheets and the occurrence of the osteo¬ arthritis markers of this invention are detected by immunolocalization with the monoclonal antibodies of this invention, e.g., 5/6/3-B-3 or 8/25/7-D-4, using a peroxidase-conjugated second antibody for detection. It should be noted that a variety of other assays such as an enzyme-linked immunosorbent assay (ELISA) and immunoradiometric assays may be employed as alternative methods of this invention using the antibodies of this invention. Because we have for the first time dis¬ covered atypical structures that serve as markers for osteoarthritis, other conventional biochemical techniques, such as HPLC analysis or GC-Mass Spectro- metry analysis may also be used to detect these atypical structures and thus to diagnose osteo¬ arthritis or to monitor the course of the disease or therapy against it. For example, these atypical structures could be detected after conventional chemical or enzymatic cleavage of the glycosamino¬ glycan chains, fractionation of the resultant oligo- saccharides by HPLC gel filtration and/or ion exchange methods, and chemical analysis using GC-Mass Spectrometry or other analytical procedures. Another embodiment of this invention pro¬ vides a therapeutic method and compositions in which the monoclonal antibodies of this invention may be linked to a pharmaceutical drug and administered directly in a pharmaceutically acceptable manner to osteoarthritic lesions. The preferred drug depends on the intended mode of therapeutic application. For example, such a drug might include cellular growth factors, cellular toxins, analogues of cytokine receptors or inhibitors of extracellular proteinases. The dosage and treatment regimens will depend upon factors such as the patient's health status, and the judgment of the treating physician. In order that this invention may be better understood, the following examples are set forth. These examples are for the purpose of illustration only, and are not to be construed as limiting the scope of the invention in any manner. Example 1 A. Preparation of Antigen, Immunization and Cell Hybridization Monoclonal antibody 5/6/3-B-3 was produced using Swarm rat chondrosarcoma proteoglycan core protein as antigen for immunization. The proteoglycan core protein was obtained after digestion of the proteoglycan monomer, AIDI fraction, with chondro¬ itinase ABC using the conditions described by Christner et al., J. Biol. Chem. , 255, 7102-05 (1980). Mono¬ clonal antibody 8/25/7-D-4 was produced using 17 day old embryonic chicken bone marrow proteoglycan as antigen. The marrow proteoglycan monomer preparation was prepared as described by Sorrell et al. , Cell Tissue Res., 252, ' 523-31 (1988). Stock solutions of each antigen (800 μg/ml in sterile Dulbecco's phosphate-buffered saline, 5 X 0.5ml aliquots) was prepared and stored at -20°C. Female Balb/cJ mice (Jackson Laboratories; 4-8 weeks old) were immunized using as antigen either Swarm rat chondrosarcoma proteoglycan core protein • (800 μg/ml) for the monoclonal antibody 5/6/3-B-3 or 17 day old embryonic chicken bone marrow proteoglycan monomer (400 μg/ml) for the monoclonal antibody 8/25/7-D-4. The antigen was administered to the mouse at six injection sites (hind foot pads, lateral thoracic and inguinal regions) using a procedure described by Caterson et al., "Biology of Proteogly¬ cans" In: Biology of the Extracellular Matrix, T. Wight and R. Mecham, ed. , pp. 1-26, Academic Press, N.Y. (1987). Injections were administered on days 1, 3, 6, 9 and 12 of the injection regimen. For the first injection (day 1) the antigen was mixed 1:1 with Freund's complete adjuvant, the second injection (day 3), ' Freund's incomplete adjuvant and the subsequent three injections (days 6, 9 and 12) with isotonic saline (0.15 M NaCl). Approximately 50 μl of the antigen mixture was injected into each of the six injection sites of the mouse on each injection day. Hybridoma fusion was performed 2 days after the last injection (day 14). Draining lymph nodes (axillary, brachial, inguinal, and popliteal lymph nodes) from the regions nearest the sites of injection on the mouse were dissected aseptically under a laminar flow hood and used as the source of proliferating lymphocytes for hybridoma production. Lymphocytes were dispersed by teasing the lymph nodes with forceps in a 25 mm Petri dish containing 2 ml sterile Dulbecco's phosphate- buffered saline and finally by repeated suction and aspiration through an 18 gauge needle using a 3 ml syringe. The lymphocytes were separated from adhering connective tissue by passing the cell suspension through a sterile glass wool filter plug in a Pasteur pipette and the cells washed twice with 40 ml of culture medium RPMI 1640 (Flow Laboratories) at 4°C. Cell fusion was carried out according to the procedure developed by Kohler and Milstein. Q Approximately 1 X 10 lymphocytes were fused with 7 5 X 10 x63-Ag8.653 myeloma cells (a gift from Dr. John F. Kearney, University of Alabama at Birmingham, ATCC # CLR 1580) by dropwise addition of 1.5 ml of a fusion medium comprising 20% polyethylene glycol (PEG 4000, Fisher Scientific) and 5% dimethyl- sulfoxide in RPMI 1640 medium (Flow Laboratories). B. Selection and Growth of Hybridoma ' After cell fusion, cells were cultured in HAT medium (hypoxanthine, aminopterin, and thymidine at 37°C with 5% C0 2 in a humid atmosphere. Ten to fourteen days later, 0.5 ml samples of medium from cultures containing hybridomas were taken and analyzed for antibodies recognizing epitopes present on the original proteoglycan antigen using ELISA and radio- immunoassay procedures described by Caterson et al., J. Biol. Chem., 258, pp. 8848-54 (1983). Hybridoma cultures containing antibodies reacting specifically with epitopes present on the injected antigen were selected and cloned. Subsequently, the clones were transferred intraperitoneally by injecting 1 x 10 7 cells of a given clone (in 1.0 ml volume in Dulbecco's phosphate-buffered saline) into retired breeder Balb/cJ mice primed with 2, 6, 10, 14-tetramethyl- pentadecane (Aldrich Chemical Company). The malignant ascites fluid from these mice were then used to characterize the antibody specificity. Both of the subject hybrid antibodies 5/6/3-B-3 and 8/25/7-D-4 were demonstrated by standard techniques to be of IgM subclass. Monoclonal antibody 5/6/3-B-3 was also found to bind S. aureus protein A, an unusual property for the mouse IgM subclass. C. Characterization of Monoclonal Antibody Specificity Monoclonal antibody 5/6/3-B-3 was produced with chondroitinase ABC-treated Swarm rat chondro- sarcoma proteoglycan monomer as an antigen. The antigenic specificity of 5/6/3-B-3 was defined using normal cartilage proteoglycans pretreated with either chondroitinase ABC, AC11 or mammalian hyaluronidase. J.R. Couchman et al., Nature, 307, pp. 650-52 (1984); B. Caterson et al., "Monoclonal Antibodies As Probes For Elucidating Proteoglycan Structure And Function," In: Biology Of The Extracellular Matrix, -ed. T. Wight and R. Mecham, Academic Press, pp. 1-26 (1987). This pretreatment shortens chondroitin sulfate chains and increases the amount of a non-reducing terminal glucuronic acid residue adjacent to a 6-sulfated N- acetylgalactosamine residue. This epitope is recog- nized by monoclonal antibody 5/6/3-B-3. These non- reducing terminal structures containing the 5/6/3-B-3 epitope are present in chondroitin sulfate chains in osteoarthritic human and dog cartilage proteoglycans (without prior chondroitinase or hyaluronidase pre- treatment) but this epitope is found to a signifi¬ cantly lesser degree in normal or control tissues. Monoclonal antibody 8/25/7-D-4 was produced using 17 day old embryonic chicken bone marrow pro¬ teoglycan as antigen. In this case, nonchondroitinase treated proteoglycan was used as the antigen. Charac¬ terization of the specificity of this monoclonal antibody indicated that the 8/25/7-D-4 epitope is only present in proteoglycans that have not had their chondroitin sulfate chains extensively cleaved by chondroitinase pretreatment. Exhaustive chondroitinase digestion removes the antigenic determinant recognized by 8/25/7-D-4 antibody indicating that the epitope resides in the chondroitin sulfate glycosaminoglycan chain. Thus the 8/25/7-D-4 epitope is a component structure of the intact chondroitin sulfate glycos- aminoglycan chain. Example 2 Detection of Atypical Chondroitin Sulfate/ Dermatan Sulfate Structures in Synovial Fluid from Joints by Radioimmunoassay Using Monoclonal 5/6/3-B-3 We induced experimental osteoarthritis in six mature (3-6 year old) Beagle dogs, using the method described by M. Pond and G. Nuki, "Experimentally-induced Osteoarthritis in the Dog," Ann. Rheum. Pis., 32, pp. 387-88 (1973). Three months after surgery, the animals were sacrificed and we injected 5 ml of sterile saline into the knee joints of the dogs. The contralateral knee joint serves as a control in our animal model. The joints were extended and flexed several times and the synovial fluid was then aspirated to dryness. We next prepared radiolabelled antigen containing 5/6/3-B-3 epitopes for standardization of our radi .oi.mmunoassay ("RIA") by 125I-ιodmatιon of chondroitinase ABC digested proteoglycans isolated from human articular cartilage. A. Ratcliffe and T.E. Hardingham, Biochem J., 213, pp. 371-78 (1983). In order to prepare the standard "unlabeled" antigen for measuring the epitope recognized by monoclonal antibody 5/6/3-B-3, we pretreated proteoglycans isolated from human articular cartilage with chondroitinase ABC. This pretreatment shortens the glycosaminoglycan chain(s) and creates many new carbohydrate chain termini containing the epitope ι ~ recognized by 5/6/3-B-3. The I radiolabelled standardization antigen showed an appropriate titration with the 5/6/3-B-3 antibody and was used as the labelled antigen in competitive RIA analyses. All of the test samples of synovial fluid obtained from either osteoarthritic or control dogs ' were analyzed without prior chondroitinase digestion so that only the amount of in vivo occurring 5/6/3-B-3. epitope on the chondroitin sulfate/dermatan sulfate chains was detected. Serial dilutions, using incu¬ bation buffer (0.15M NaCl, 0.01M N 2 HP0 4 , pH 7.4 containing 0.5% (w/v) sodium deoxycholate, 0.1% (w/v) Nonidet P-40 and 0.1% (w/v) Bovine Serum Albumin), were prepared from each aspirate followed by competitive radioimmunoassay analysis. A dilu¬ tion of the 5/6/3-B-3 antibody (lOOμl) (sufficient to preci ■pi.tate 50% of the 125I-labeled RIA standardi¬ zation antigen) was mixed with dilute osteoarthritic samples or controls (50μl) in incubation buffer together with 125I-labelled chondroi.ti■nase ABC digested human cartilage proteoglycan (20,000 dpm) in 1.5 ml plastic microcentrifuge tubes and incubated overnight at 20°C. A suspension (10% w/v) of S. aureus (30μl) (heat denatured and formalin treated) was added and after mixing for 25 minutes the tubes were spun and the pellet washed twice with incubation buffer. The pellet and the combined supernatant and washings were next counted separately in a gamma radiation counter (LKB,. Sweden). The . . ■ 125 . . inhibition of I-antigen binding achieved by the samples was compared with a set of standards of known antigen concentration and the results were expressed in units of concentration of the antigen (chondroitinase digested human proteoglycan). Table 1 compares the level of monoclonal antibody 5/6/3-B-3 epitope between normal (synovial fluid from contralateral control joint) and osteo¬ arthritic ("OA") joints. In each case, the presence of increased amounts of 5/6/3-B-3 epitope in the synovial fluid from the osteoarthritic joints was demonstrated. Example 3 Detection of Atypical Chondroitin Sulfate/Dermatan Sulfate Structures In Cartilage Proteoglycans from Joints Using Monoclonal Antibodies 5/6/3-B-3 and 8/25/7-D-4 We induced experimental osteoarthritis in dogs as described by Pond and Nuki. Cartilage was freshly dissected from tibial plateau, patellar groove and femoral condyles 3 months after ligament section and was extracted in 10 volumes of 4M guanidine HCl, 0-.5M sodium acetate pH 5.8 containing proteinase inhibitors (0.1M 6-aminohexanoic acid, 0.01M disodiu ethylene diamine tetracetic acid, benzamidine HCl and 0.001M phenyl-methane- sulphonylfluoride). The extract was dialyzed against several changes of 8M urea and the proteoglycan concentration was determined in a dye binding assay described by R.W. Farndale et al., Conn. Tiss. Res. 9, pp. 247-48 (1982). We used cartilage from the contra- lateral unoperated joint as a control. Proteoglycans extracted from the cartilage from different joint regions were next compared by electrophoresis on composite agarose/acrylamide slab gels. The gels were prepared by suspending agarose (0.24g) in 22 ml gel buffer (0.04 M Tris-acetate/lmM Na 2 S0 4 pH 6.8) and heating to 90°C. Acrylamide (0.456g) and bisacrylamide (0.024g) were dissolved in gel buffer (9.7ml) and beta-dimethylaminoproprio- nitrile (0.4% w/v; 4.8ml) was added to it and the mixture was warmed. The agarose solution was allowed to cool to 52°C and ammonium persulfate (0.3% v/v; 3ml) was added to the acrylamide solution, followed by mixing thoroughly with the agarose and quickly poured into the gel cast, which was preheated to 50°C. (A plug of acrylamide (10% w/v) of depth 50mm was preformed in the bottom of the gel support in order to hold the composite gel in place during electrophoresis.) Water saturated n-butanol was layered on top of the freshly poured gel to exclude air during polymerization. The gel was placed in the cold (4°C) for 1 hour and then equilibrated in buffer containing 4M urea overnight. Samples con¬ taining about lOμg proteoglycan in buffer (0.01M Tris-acetate/0.25mM 2 S0 4 containing 8M urea and 0.001% (w/v) bromophenol blue, pH 6.8) were loaded in each track. Gels were electrophoresed at 4°C initially at 60V until the bromophenol blue had entered the gel and then at 120V until it had migrated 30mm. Replicate gels were run in this manner. One gel was then stained with toluidine blue (0.2% (w/v) in 0.1M acetic acid to reveal proteoglycan bands and replicate gels were left unstained for electro- blotting. Electrophoretic transfer to a nylon sheet (Gelman Biotrace RP) was carried out with minimal amounts of buffer (0.01M Tris-acetate, 0.25mM Na 2 S0 4 pH 6.8) in a semi-dry electroblotter (Sartorius, Belmont, UK) run at 80mA for one hour. The nylon sheet was rinsed with water and dried on filter paper. For immunolocalization of atypical chondroi¬ tin sulfate/dermatan sulfate chains, the method used was essentially that of A. L. Deblas and H. M. Cherwinski, Analyt. Biochem., 133, pp. 214-219 (1983), as described for nitrocellulose sheets. The nylon sheet was wetted in phosphate buffered saline (PBS) (0.14M NaCl, 0.01M Na 2 HP0 4 , pH 7.4) and protein absorptive sites were blocked by incubation with 1% (w/v) bovine serum albumin (BSA) in PBS for 1 hour. The sheet was then incubated in antibody 5/6/3-B-3 or 8/25/7-D-4 (1 in 1000 dilution in PBS) for 1.5 hours and then washed for 5 minutes in six changes of PBS. It was then incubated with peroxidase- conjugated rabbit anti ouse immunoglobulin (Sigma, St. Louis, Missouri) (1 in 1000 dilution in PBS containing 1% (w/v) BSA) for 1 hour followed by 5 minutes of washing in six changes of PBS. The sheet was then incubated with peroxidase substrate (diaminobenzidine/cobalt chloride/ammonium nickel sulfate reagent) for 15 minutes in the dark followed by fresh reagent, but also containing H 2 0 2 to develop the staining (30-90 minutes). The atypical chondroitin/dermatan sulfate epitopes localized by the antibodies on the nylon sheet appeared as darkly stained bands on an unstained background. The distri¬ bution and intensity of the bands were recorded by preparing densitometric scans on a dual wavelength TLC scanner CS-930 (Shimadzu, Japan). This permitted quantitative comparison of OA and normal samples detected under identical conditions on the same nylon sheet. As shown in Figure 1, expression of the atypical chondroitin sulfate/dermatan sulfate epitope recognized by monoclonal antibody 5/6/3-B-3 is increased in osteoarthritic cartilage from all areas 3 months after osteoarthritis was induced as compared to the contralateral control. This result was found in 23 out of 23 animals tested in which osteorthritis had been induced either 3 months or 6 months earlier. We also employed monoclonal antibody 8/25/7-D-4 in place of 5/6/3-B-3 using the same techniques described above. Similarly, Figure 2 shows the atypical chondroitin sulfate/dermatan sulfate epitope recognized by 8/25/7-D-4 was expressed more strongly in proteoglycans in osteoarthritic cartilage compared with control joints. Quantitative assessment of the immuho- blotting from parallel tracks showed an average increase to 440% of control in the proteoglycans from osteoarthritic cartilage (see Table 2). Table 2 8/25/7-D-4 Epitope in Proteoglycans from Experimental Canine Osteoarthritis Analysis of Densitometric Scans (Fig 2) Animal Region Epitope Abundance Average Number Expressed as % of control femoral 428 74 tibial 348 327 patellar 204 femoral 348 75 tibial 359 305 patellar 208 77 femoral 475 tibial 1115 688 patellar 474 Example 4 Detection of Atypical Chondroitin • Sulfate/Dermatan Sulfate Chains in Osteoarthritic Human Articular Cartilage We obtained human cartilage samples from 16 osteoarthritic femoral heads removed at joint replace¬ ment (65-85 yrs) and 15 normal femoral head or femoral condyle specimens (0-80 yrs) and compared the presence of atypical chondroitin sulfate/dermatan sulfate chains using the same method described in Example 1, using monoclonal antibody 5/6/3-B-3, except for taking densitometric scans. We observed 11 out of 16 immuno¬ blots of the proteoglycans in osteoarthritic samples (Figures 3a and 3b) and 3 out of 15 normal samples (Figures 4a and 4b) as being positive for the atypical chondroitin sulfate/dermatan sulfate recognized by 5/6/3-B-3. In the latter case, we believe that 2 of these 3 "normal" samples were positive because they were obtained from apparently normal cartilage adjacent to osteoarthritic lesions. This cartilage would be expected to contain atypical chondroitin sulfate/dermatan sulfate chains indicative of osteoarthritis. We found atypical chondroitin sulfate/dermatan sulfate chains were present at low levels in all other normal human samples. It will be appreciated that the scope of this invention is to be defined by the claims appended hereto rather than by the specific embodiments which have been presented herein by way of example.

Claims: We Claim: 1. A method for the early diagnosis of osteoarthritis in mammals comprising the step of detecting the presence of an increased amount of atypical chondroitin sulfate/dermatan sulfate glycosaminoglycan chains in body tissue and fluids, said atypical chains being chondroitin sulfate/dermatan sulfate chains which are specifi¬ cally recognizable by a monoclonal antibody select¬ able by the process of raising monoclonal antibodies against the proteoglycans of cartilage extracts from a mammal suffering from osteoarthritis and screening for those antibodies (1) that selectively recognize proteoglycans of cartilage extracts from a mammal suffering from osteoarthritis (2) that do not recognize or recognize to a significantly lesser extent than in screen (1) proteoglycans of cartilage extracts from a mammal not suffering from osteoar¬ thritis and (3) that do not recognize proteoglycans of cartilage extracts from a mammal suffering from osteoarthritis, from which the chondroitin sulfate/dermatan sulfate chains have been completely removed by enzymatic or chemical treatment. 2. The method according to claim 1, wherein the mammal is selected from a group con¬ sisting of humans, dogs and guinea pigs and the monoclonal antibody is selected from a group con¬ sisting of monoclonal antibody 5/6/3-B-3 and mono¬ clonal antibodies immunologically crossreactive with said antibody. 3. The method according to claim 1, wherein the mammal is selected from a group con¬ sisting of humans, dogs and guinea pigs and the monoclonal antibody is selected from a group con¬ sisting of monoclonal antibody 8/25/7-D-4 and monoclonal antibodies immunologically crossreactive with said antibody. 4. A monoclonal antibody selectable by the process of raising monoclonal antibodies - against the proteoglycans of cartilage extracts from a mammal suffering from osteoarthritis and screening for those antibodies (1) that selectively recognize proteoglycans of cartilage extracts from a mammal suffering from osteoarthritis, (2) that do not recognize or recognize to a significantly lesser extent than in screen (1) proteoglycans of cartilage extracts from a mammal not suffering from osteo¬ arthritis and (3) that do not recognize proteogly¬ cans of cartilage extracts from a mammal suffering from osteoarthritis, from which the chondroitin sulfate/dermatan sulfate chains have been completely removed by enzymatic or chemical treatment, said monoclonal antibody excluding monoclonal antibody 5/6/3-B-3. 5. The monoclonal antibody according to claim 4, selected from the group consisting of monoclonal antibody 8/25/7-D-4 and monoclonal anti¬ bodies immunologically crossreactive with said antibody. 6. A method for treating osteoarthritis which comprises the step of administering to a mammal a therapeutically effective amount of a drug useful in the treatment of osteoarthritis, said drug being linked to a monoclonal antibody selectable by the process of raising monoclonal antibodies against the proteoglycans of cartilage extracts from a mammal suffering from osteoarthritis and screening for those antibodies (1) that selectively recognize proteogly¬ cans of cartilage extracts from a mammal suffering from osteoarthritis, (2) that do not recognize or recognize to a significantly lesser extent than in screen (1) proteoglycans of cartilage extracts from a mammal not suffering from osteoarthritis,and (3) that do not recognize proteoglycans of cartilage extracts from a mammal suffering from osteoarthritis, from which the chondroitin sulfate/dermatan sulfate chains have been completely removed by enzymatic or chemical treatment. 7. The method according to claim 6, wherein the monoclonal antibody is selected from the group consisting of 5/6/3-B-3, 8/25/7-D-4 and mono¬ clonal antibodies immunologically crossreactive with said antibodies. 8. A detection kit for detecting or moni¬ toring osteoarthritis in mammals, said kit being characterized by at least one monoclonal antibody selectable by the process of raising monoclonal antibodies against the proteoglycans of cartilage extracts from a mammal suffering from osteoarthritis and screening for those antibodies (1) that selec¬ tively recognize proteoglycans of cartilage extracts from a mammal suffering from osteoarthritis, (2) that do not recognize or recognize to a significantly lesser extent than in screen (1) proteoglycans of cartilage extracts from a mammal not suffering from osteoarthritis,and (3) that do not recognize proteogly¬ cans of cartilage extracts from a mammal suffering from osteoarthritis, from which the chondroitin sulfate/dermatan sulfate chains have been completely - removed by enzymatic or chemical treatment. 9. The detection kit according to claim 8, wherein the monoclonal antibody is selected from the group consisting of monoclonal antibody 5/6/3-B-3, monoclonal antibody 8/25/7-D-4 and monoclonal anti¬ bodies immunologically crossreactive with said anti¬ bodies. 10. A method of monitoring the progression of osteoarthritis or the effect or course of therapy on it comprising the step of following the presence and relative quantity of atypical chondroitin sulfate/dermatan sulfate glycosaminoglycan chains in body tissue and fluids, said atypical chains being specifically recognizable by a monoclonal antibody selectable by the process of raising monoclonal antibodies against the proteoglycans of cartilage extracts from a mammal suffering from osteoarthritis and screening for those antibodies (1) that selec¬ tively recognize proteoglycans of cartilage extracts from a mammal suffering from osteoarthritis, (2) that do not recognize or recognize to a significantly lesser extent than in screen (1) proteoglycans of cartilage extracts from a mammal not suffering from osteoarthritis, and (3) that do not recognize 1 pro¬ teoglycans of cartilage extracts from a mammal suffering from osteoarthritis, from which the chondroitin sulfate/dermatan sulfate chains have been completely removed by enzymatic or chemical treatment. 11. The method according to claim 10, wherein the mammal is selected from a group con¬ sisting of humans, dogs and guinea pigs and the monoclonal antibody is selected from a group consisting of monoclonal antibody 5/6/3-B-3 and monoclonal antibodies immunologically crossreactive with said antibody. 12. The method according to claim 10, wherein the mammal is selected from a group con- sisting of humans, dogs and guinea pigs and the monoclonal antibody is selected from a group con¬ sisting of monoclonal antibody 8/25/7-D-4 and mono¬ clonal antibodies immunologically crossreactive with said antibody.

Inventors: CATERSON BRUCE, HARDINGHAM TIMOTHY E, CATERSON, BRUCE, HARDINGHAM, TIMOTHY, E.
Applicants: CATERSON BRUCE, HARDINGHAM TIMOTHY E, CATERSON, BRUCE, HARDINGHAM, TIMOTHY, E.
Application year: 1989
Main classification: A61K39
IPC codes: A61K38, A61K39, A61K47, A61K49, C07K16, C12N5, C12N15, C12P21, C12R1, G01N33