Pharmacological characterization of GLPG1972/S201086, a potent and selective small-molecule inhibitor of ADAMTS5

OBJECTIVE

A disintegrin and metalloproteinase with thrombospondin motifs 5 (ADAMTS5) is a key enzyme in degradation of cartilage in osteoarthritis (OA). We report the pharmacological characterization of GLPG1972/S201086, a new, potent and selective small-molecule ADAMTS5 inhibitor.

METHODS

Potency and selectivity of GLPG1972/S201086 for ADAMTS5 were determined using fluorescently labeled peptide substrates. Inhibitory effects of GLPG1972/S201086 on interleukin-1α-stimulated glycosaminoglycan release in mouse femoral head cartilage explants and on interleukin-1β-stimulated release of an ADAMTS5-derived aggrecan neoepitope (quantified with ELISA) in human articular cartilage explants were determined. In the destabilization of the medial meniscus (DMM) mouse and menisectomized (MNX) rat models, effects of oral GLPG1972/S201086 on relevant OA histological and histomorphometric parameters were evaluated.

RESULTS

GLPG1972/S201086 inhibited human and rat ADAMTS5 (IC50 ± SD: 19 ± 2 nM and <23 ± 1 nM, respectively), with 8-fold selectivity over ADAMTS4, and 60->5,000-fold selectivity over other related proteases in humans. GLPG1972/S201086 dose-dependently inhibited cytokine-stimulated aggrenolysis in mouse and human cartilage explants (100% at 20 μM and 10 μM, respectively). In DMM mice, GLPG1972/S201086 (30-120 mg/kg b.i.d) vs vehicle reduced femorotibial cartilage proteoglycan loss (23-37%), cartilage structural damage (23-39%) and subchondral bone sclerosis (21-36%). In MNX rats, GLPG1972/S201086 (10-50 mg/kg b.i.d) vs vehicle reduced cartilage damage (OARSI score reduction, 6-23%), and decreased proteoglycan loss (∼27%) and subchondral bone sclerosis (77-110%).

CONCLUSIONS

GLPG1972/S201086 is a potent, selective and orally available ADAMTS5 inhibitor, demonstrating significant protective efficacy on both cartilage and subchondral bone in two relevant in vivo preclinical OA models.

Calcitonin protects rat chondrocytes from IL-1β injury via the Wnt/β-catenin pathway

The present study investigated whether the Wnt/β-catenin pathway was involved in the protective effect of calcitonin (CT) in interleukin-1β (IL-1β)-injured rat chondrocytes. Chondrocytes were acquired from the articular cartilage of 4-week-old rats and treated with 10 ng/ml IL-1β to stimulate an in vitro osteoarthritis model. CT (10 and 50 nM) and 5 µm IWR-1-endo (a Wnt/β-catenin inhibitor) was used for treatment. The proliferation and apoptosis of rat articular chondrocytes were measured using a cell counting kit-8 assay and Annexin V/PI staining, respectively. Expression of matrix-metalloproteinases (MMP)-13 MMP3 and MMP9 and aggrecanases [metalloproteinase thrombospondin motifs (ADAMTS4 and ADAMTS5)] were measured to assess the degradation of the cartilage extracellular matrix. The results of the present study demonstrate that CT protected rat chondrocytes from IL-1β stimulation by enhancing cell viability, suppressing apoptosis and decreasing the expression of matrix metallopeptidase (MMP) MMP13, MMP3, MMP9, ADAMTS4 and ADAMTS5. CT treatment also upregulated dickkopf-1 and downregulated β-catenin. IWR-1-endo demonstrated similar effects to that of CT treatment. The administration of CT in addition to IWR-1-endo reinforced the change trends induced by CT or IWR-1-endo in the aforementioned events, indicating that CT possibly acted via the Wnt/β-catenin pathway to exert a protective effect on IL-1β-injured rat chondrocytes.

Identification of potent and selective hydantoin inhibitors of aggrecanase-1 and aggrecanase-2 that are efficacious in both chemical and surgical models of osteoarthritis

A disintegrin and metalloproteinase with thrombospondin motifs-4 (ADAMTS-4) and ADAMTS-5 are zinc metalloproteases commonly referred to as aggrecanase-1 and aggrecanase-2, respectively. These enzymes are involved in the degradation of aggrecan, a key component of cartilage. Inhibitors of these enzymes could be potential osteoarthritis (OA) therapies. A series of hydantoin inhibitors of ADAMTS-4 and ADAMTS-5 were identified from a screening campaign and optimized through structure-based drug design to give hydantoin 13. Hydantoin 13 had excellent selectivity over other zinc metalloproteases such as TACE, MMP2, MMP3, MMP13, and MMP14. The compound also produced efficacy in both a chemically induced and surgical model of OA in rats.

Enzyme-linked immunosorbent assay (ELISAs) for metalloproteinase derived type II collagen neoepitope, CIIM--increased serum CIIM in subjects with severe radiographic osteoarthritis

OBJECTIVES

In joint degenerative diseases, the collagens are degraded by matrix metalloproteinases and protein fragments are released to serum as potential biomarkers.

METHODS

A collagen type II specific neoepitope, CIIM, was identified (…RDGAAG(1053)) by mass spectrometry. Two ELISAs against the neoepitope were developed. CIIM was measured in cartilage explants in the presence or absence of protease inhibitors. CIIM was measured in OA synovial fluid (n=51) and serum (n=156). Knee OA was graded by standard Kellgren-Lawrence (KL) score.

RESULTS

The ELISAs showed good technical performance; CV%, <13%. CIIM release from cartilage explants was blocked by the MMP inhibitor. CIIM was detected in synovial fluid. Furthermore, serum CIIM levels were significantly higher (P<0.05) in those individuals with mild or severe OA than in those with no OA.

CONCLUSION

We developed a new biomarker for joint degenerative diseases, which we demonstrated was derived from MMP-degraded type II collagen.

Extracellular matrix and pathogenic mechanisms in osteoarthritis

Osteoarthritis (OA) is a heterogeneous condition of joint degeneration characterized by structural changes in extracellular matrices such as subchondral bone and cartilage. Research has identified many diverse ways of initiating OA, varying from mechanical disruption to gene mutations in structural proteins. A frequent end point is cartilage loss, which can occur irrespective of the initiating mechanism. Of the mechanisms responsible for cartilage matrix damage, a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS)-5 was identified as of key importance in knockout mice, but work with human cartilage has suggested that ADAMTS-4 was also involved. A transgenic mouse expressing aggrecan lacking a key aggrecanase site clearly showed that loss of aggrecan from cartilage was an important step in both inflammatory and trauma-induced joint degeneration. In OA, cartilage chondrocytes show changes in gene expression, and it remains to be resolved if this reflects adaptive responses to changes in biological, physical, and mechanical signaling rather than any form of differentiation.