Vishwas Ganu

Inhibition of interleukin‐1α‐induced cartilage oligomeric matrix protein degradation in bovine articular cartilage by matrix metalloproteinase inhibitors: Potential role for matrix metalloproteinases in the generation of cartilage oligomeric matrix protein fragments in arthritic synovial fluid

OBJECTIVE To determine whether matrix metalloproteinases (MMPs) degrade cartilage oligomeric matrix protein (COMP) to produce fragments similar to those found in synovial fluid (SF) from patients with arthritis. METHODS COMP fragments were generated in vitro by treating (a) bovine articular cartilage with interleukin-1alpha (IL-1alpha), (b) purified bovine COMP with MMPs, and (c) articular cartilage with MMPs. The fragments generated in each case were analyzed by Western blot, using an antibody to the C-terminal heptadecapeptide of COMP. RESULTS IL-1alpha stimulation of cartilage resulted in a fragmentation of COMP, which was inhibited by MMP inhibitors CGS 27023A and BB-94. Isolated, recombinant MMPs rapidly degraded purified COMP, as well as COMP residing in cartilage. Several COMP fragments produced in vitro had similar electrophoretic mobility to those in SF of patients with arthritis. CONCLUSION MMPs may contribute to the COMP fragments found in vivo. Quantitation of MMP-specific fragments may be useful in the evaluation of MMP inhibitors in patients with arthritis.

Oral administration of a matrix metalloproteinase inhibitor, CGS 27023A, protects the cartilage proteoglycan matrix in a partial meniscectomy model of osteoarthritis in rabbits.

Matrix metalloproteinases (MMP) are elevated in human osteoarthritic cartilage [1] and in cartilage from rabbits with experimental osteoarthritis (OA) following partial meniscectomy [2]. CGS 27023A is a M M P inhibitor that inhibits stromelysin, collagenase and gelatinase. CGS 27023A is an orally active inhibitor of stromelysin. CGS 27023A at 75 gmoles/kg p.o. inhibits release of proteoglycan into synovial fluid following intra-articular injection of stromelysin into rabbit knees. The purpose of these experiments was to determine whether CGS 27023A would inhibit cartilage proteoglycan loss in a partial meniscectomy model of osteoarthritis in rabbits [3]. Doxycycline was used as a reference drug [4].

Factor C3f is a spasmogenic fragment released from C3b by factors I and H: The heptadeca-peptide C3f was synthesized and characterized

C3f, a heptadeca-peptide having the amino acid sequence of NH2-Ser-Ser-Lys-Ile-Thr-His-Arg-Ile-His-Trp-Glu-Ser-Ala-Ser-Leu-Leu-Arg- COOH, is liberated during the catabolic degradation of C3b in serum. The amino acid sequence of C3f is known both from the cDNA-derived structure of C3 and from protein analysis after isolation of the natural factor. C3f was synthesized by solid phase peptide synthesis. Both natural and synthetic C3f had identical retention times by RP-18 high performance liquid chromatography (HPLC) analysis and the respective amino acid compositions agreed with the expected theoretical values. C3f, but not des-Arg-C3f, was weakly spasmogenic inducing contraction of guinea pig ileum at a level of 5-10 x 10(-6) M. Since C3f and C3a were cross-tachyphylactic, it was concluded that these two spasmogens compete for the same receptors. Both C3f and des-Arg-C3f at concns of 1-4 x 10(-4) M enhanced vascular permeability in guinea pig skin. These observations further suggest that C3f functionally resembles C3a anaphylatoxin. Formation of C3f in human serum following CVF activation of C3 could be demonstrated by radioimmunoassay (RIA). Digestion of C3f with purified human serum carboxypeptidase N produced C3f-desArg. These observations suggest that when serum complement protein C3 undergoes conversion to C3b, further degradation by Factors H and I readily generates C3f. C3f is a weak spasmogen that functions like C3a anaphylatoxin and C3f-desArg is a major metabolite in serum.

Potent and selective 2-naphthylsulfonamide substituted hydroxamic acid inhibitors of matrix metalloproteinase-13.

The matrix metalloproteinase enzyme MMP-13 plays a key role in the degradation of type II collagen in cartilage and bone in osteoarthritis (OA). An effective MMP-13 inhibitor would provide a disease modifying therapy for the treatment of arthritis, although this goal still continues to elude the pharmaceutical industry due to issues with safety. Our efforts have resulted in the discovery of a series of hydroxamic acid inhibitors of MMP-13 that do not significantly inhibit MMP-2 (gelatinase-1). MMP-2 has been implicated in the musculoskeletal side effects resulting from pan-MMP inhibition due to findings from spontaneously occurring human MMP-2 deletions. Analysis of the SAR of hundreds of previously prepared hydroxamate based MMP inhibitors lead us to 2-naphthylsulfonamide substituted hydroxamates which exhibited modest selectivity for MMP-13 versus MMP-2. This Letter describes the lead optimization of 1 and identification of inhibitors exhibiting >100-fold selectivity for MMP-13 over MMP-2.

Metalloprotease inhibitors halt collagen breakdown in IL-1 induced bovine nasal cartilage cultures

Interleukin-1 (IL-I) stimulates chondrocytes to increase the synthesis of metalloproteases, which can then degrade the cartilage extracellular matrix [1,2]. Growth factors, such as insulin-like growth factor-1 have been shown to decrease the catabolic effects of IL-1 [3]. Other studies have shown that compounds, such as synthetic matrix metalloprotease inhibitors (MMPIs), can prevent IL-1 stimulated collagen breakdown [4-5]. In this report, we compared the effects of two synthetic MMPIs, CGS 27023A and Ro 31-9790, on preventing the release of collagen from IL-1 treated cartilage organ cultures. We also investigated the effect of adding a matrix metalloprotease inhibitor (MMPI), in this model, starting at different times.

Thick filter neutrophil chemotaxis performed in the absence of albumin.

Migration through a filter is a technique widely used for the study of cell chemotaxis. Since the original description of the technique by Boyden in 1962 (J. Exp. Med. 115, 453) using neutrophils and thick filters prepared from cellulose nitrate, albumin has been required in the incubation medium to support chemotaxis. However, the binding to albumin of compounds affecting chemotaxis can reduce their free concentration. We developed two procedures for studying neutrophil chemotaxis under reduced or albumin-free conditions. In one, cellulose nitrate filters were pretreated with albumin by a novel procedure and chemotaxis was carried out in albumin-free medium. As tested with the chemoattractant LTB4 and human neutrophils, the procedure resulted in full chemotaxis, measured by the number of cells crossing the filter, with an EC50 of 0.43 nM for LTB4. The LTB4-receptor antagonist LY 223982 inhibited the chemotactic action of LTB4 with a Ki of 62 nM in the albumin-pretreated filter system, thus showing 58 times greater potency than in medium containing 0.5% albumin. The second procedure makes use, for the first time, of a relatively new filter (Hydrophilic Durapore). This filter has the same dimensions and pore rating of the cellulose nitrate filter but did not require pretreatment with albumin to support chemotaxis in the albumin-free medium. LTB4 stimulated neutrophil chemotaxis across this filter with an EC50 of 0.29 nM. LY 223982 had a Ki of 11 nM, thus exhibiting a potency even greater than in the albumin-pretreated cellulose nitrate filter system. fMLP and C5a also stimulated chemotaxis in the absence of albumin. These results suggest that albumin is not obligatory for neutrophil chemotaxis through thick filters. The role of albumin in the chemotaxis assay using cellulose nitrate filters may be to counteract the adherence of cells or chemotactic agents to the filters.

Improved synthetic inactivators of plasmin

Synthetic inhibitors for plasmin of the peptidyl chloromethyl ketone type are described which have increased effectiveness due to side-chains which improve affinity to auxiliary binding regions of the active center.

Design and synthesis of thiol containing inhibitors of matrix metalloproteinases

A series of thiol containing derivatives was prepared. Several of these compounds were found to inhibit matrix metalloproteinases 1, 3, and 9 with selectivity towards 3 and 9. Compounds 15, 20, and 22 were administered to rats orally at 75 mumol/kg. Drug levels of compounds 20 and 22 in the plasma were found to exceed the IC50 values for MMP 3 and 9 four hours after administration.

Matrix Metalloproteinase Inhibitor CGS 27023A Protects COMP and Proteoglycan in the Bovine Articular Cartilage but not the Release of Their Fragments from Cartilage after Prolonged Stimulation in Vitro with IL‐1α

In arthritis, the metalloproteinases (MP) such as stromelysin-1, collagenase-1 and -3, MT1-MMP, 92-kDa gelatinase, and as yet unidentified MP aggrecanase are thought to play a role in the degradation of proteoglycans (PG), cartilage oligomeric matrix protein (COMP), and type II collagen, the components of articular cartilage. It is not yet clear which of these MP plays a dominant role in the degradation of cartilage. The matrix metalloproteinase inhibitors CGS 27023A 1 and BB-94 2 are potent inhibitors of several MPs, but only BB-94 inhibits aggrecanase activity. 3 Here, we investigated whether inhibition of these two activities is needed in protecting the cartilage components PG and COMP. We used them in an IL-1 α –induced bovine cartilage degradation assay 4 and determined their effect on the release of these cartilage components from cartilage and also their retention in the cartilage after prolonged IL-1 stimulation of cartilage.

A stromelysin assay for the assessment of metalloprotease inhibitors on human aggregated proteoglycan

Human proteoglycan was aggregated to an immobilized hyaluronan solid phase on a 96-well ELISA plate. This complex was then degraded by recombinant human stromelysin. The remaining proteoglycan fragments were detected using a monoclonal antibody probe directed against the chondroitin sulfate (CS) region of the core protein. Stromelysin degraded the aggregate in a time and dose dependent manner as reflected by the loss of the CS epitope. Assay sensitivity was 0.125 U/well with total loss of the CS epitope occurring at 4 U/well.o-phenanthroline (IC50=52 μM) and U24522 (IC50=9 μM) inhibted degradation, while phosphoramidon did not. Serine and cysteine protease inhibitors had no effect. A comparative analysis of this assay with a reference method, substance P assay, gave similar inhibitor profiles. The use of aggregated human proteoglycan (native conformation) as a substrate, may better reflect how stromelysin inhibitors behave in the presence of complex substrates such as cartilage matrix.