Polyphenolic compounds from green tea have been shown to reduce inflammation in a murine model of inflammatory arthritis, but no studies have been undertaken to investigate whether these compounds are protective to joint tissues. We therefore investigated the effects of catechins found in green tea on cartilage extracellular matrix components using in vitro model systems. Bovine nasal and metacarpophalangeal cartilage as well as human nondiseased, osteoarthritic and rheumatoid cartilage were cultured with and without reagents known to accelerate cartilage matrix breakdown. Individual catechins were added to the cultures and the amount of released proteoglycan and type II collagen was measured by metachromatic assay and inhibition ELISA, respectively. Possible nonspecific or toxic effects of the catechins were assessed by lactate output and proteoglycan synthesis. Catechins, particularly those containing a gallate ester, were effective at micromolar concentrations at inhibiting proteoglycan and type II collagen breakdown. No toxic effects of the catechins were evident. We conclude that some green tea catechins are chondroprotective and that consumption of green tea may be prophylactic for arthritis and may benefit the arthritis patient by reducing inflammation and slowing cartilage breakdown. Further studies will be required to determine whether these compounds access the joint space in sufficient concentration and in a form capable of providing efficacy in vivo.

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Aims-To determine the collective roles of stromelysin 1, neutrophil collagenase, and collagenase 3 in chondrocyte mediated cartilage proteoglycan and type II collagen degradation in tissue culture model systems. Methods-Bovine nasal cartilage explants were cultured with and without recombinant human interleukin 1 (IL-1 ), recombinant human tumour necrosis factor , or retinoic acid. Proteoglycan and type II collagen release were determined by colorimetric assay and immunoassay, respectively, in the absence and presence of matrixin inhibitors. Potential toxic eVects of the inhibitors were assessed by measuring rates of glycolysis. Results-Loss of proteoglycan and type II collagen from nasal cartilage was inhibited by batimastat, a broad spectrum matrixin inhibitor. BB-3437, a selective inhibitor of stromelysin, neutrophil collagenase, and collagenase 3, at the concentrations used in this study, showed a weak but dose dependent inhibitory eVect on the IL-1 stimulated degradation of type II collagen, but had virtually no eVect on proteoglycan breakdown. Neither inhibitor aVected rates of glycolysis. Conclusions-Stromelysin 1, neutrophil collagenase, and collagenase 3 are unlikely to contribute to chondrocyte mediated proteoglycan degradation in our model system. The modest eVect of a selective inhibitor of these enzymes on IL-1 stimulated collagen breakdown suggests a minor role for one or more of these proteinases; potent inhibition by an inhibitor of interstitial collagenase and the gelatinases suggests that these enzymes play a major role in IL-1 stimulated, chondrocyte mediated type II collagen breakdown from nasal cartilage. (J Clin Pathol: Mol Pathol 1998;51:282-286)

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