Effects of culture conditions and exposure to catabolic stimulators (IL-1 and retinoic acid) on the expression of matrix metalloproteinases (MMPs) and disintegrin metalloproteinases (ADAMs) by articular cartilage chondrocytes

The chondrocytes of articular cartilage synthesize a number of proteinases which are capable of degrading the component molecules of this specialized extracellular matrix. The use of class-specific proteinase inhibitors indic ates that major activities responsible for catabolism of proteoglycan (aggr ecan) and collagen are attributable to zinc-dependent metalloproteinases. I n this study, we have compared the mRNA expression profiles of two matrix m etalloproteinases (MMP-3 and MMP-13) and five disintegrin-metalloproteinase s (ADAM-10, ADAM-9, ADAM-15, TNF-a-converting enzyme and decysin) by chondr ocytes (human, porcine and bovine) from fresh cartilage and in cartilage ex plant cultures and isolated cells cultured in monolayer or in agarose gels. Such cultures were maintained in the presence or absence of interleukin-1 (IL-1) or all-trans-retinoic acid, two agents which promote cartilage matri x degradation in vitro. Whereas transcripts for all metalloproteinases exam ined were detected in chondrocytes from human osteoarthritic cartilage in m onolayer cultures, mRNAs for ADAM-15 and decysin were not present in fresh osteoarthritic human cartilage or explant cultures. Similarly, expression o f porcine and bovine metalloproteinase mRNAs varied with different culture conditions. Novel cDNA sequences obtained for porcine and bovine MMP-3 and MMP-13, porcine ADAM-10, porcine and bovine ADAM-9 and porcine TACE confirm ed expression of mRNAs for these molecules by articular chondrocytes, Quant itative RT-PCR analysis was used to determine the effects of IL-1 and retin oic acid on metalloproteinase mRNA levels in human chondrocytes cultured in monolayer and in porcine chondrocytes cultured in agarose. For the MMPs, I L-1 treatment resulted in an approximately two to threefold increase in hum an and porcine MMP-3 and MMP-13 mRNAs, while retinoic acid treatment caused a statistically significant increase in human MMP-3 mRNA levels, but no si gnificant change in transcript levels for porcine MMP-3 nor human or porcin e MMP-13. The mRNA levels for ADAM-15 were elevated in hum;ln monolayer cho ndrocytes exposed to IL-1 or retinoic acid, while transcripts levels for TN F-alpha converting enzyme were increased in response to retinoic acid. In c ontrast, ADAM-9 mRNA levels were decreased in human monolayer chondrocytes exposed to IL-1 or retinoic acid. The results demonstrate that chondrocyte metalloproteinase expression can vary dependent on cell environment in situ and in vitro, and provide new information on chondrocyte MMP and ADAM gene expression following cytokine (IL-1) or retinoid stimulation. (C) 1999 Els evier Science B.V./International Society of Matrix Biology. All rights rese rved.