Does cyclooxygenase 2-dependent prostaglandin E2 modulate cartilage proteoglycan degradation in human osteoarthritis explants?
IL-1 beta-induced production of COX-2 protein and PGE(2) was low in OA articular cartilage compared with that in the other OA tissues examined. IL-1 beta-mediated degradation of cartilage proteoglycans in OA synovial membrane-cartilage cocultures was blocked by the selective COX-2 inhibitor, SC-236, and the effect of SC-236 was reversed by the addition of exogenous PGE(2). Our data suggest that induction of synovial COX-2-produced PGE(2) is one mechanism by which IL-1 beta modulates cartilage proteoglycan degradation in OA.
These results indicate that an excess of galectin-7 leads to a destabilisation of adherens junctions associated with defects in epidermal repair. As this phenotype shares similarities with that of galectin-7 null mutant mice, we conclude that a critical level of this protein is required for maintaining proper epidermal homeostasis. This study brings new insight into the mode of action of galectins in normal and pathological situations.