Corps AN, Curry VA, Buttle DJ, Hazleman BL, Riley GP.
Rheumatology Research Unit, Box 194, Addenbrooke's Hospital, Hills Road, Cambridge CB2 2QQ, UK. anc@mole.bio.cam.ac.uk
The medicinal benefits of green tea (Camellia sinensis) consumption have been attributed to bioavailable polyphenols, notably epigallocatechin gallate (EGCG). We have assessed the effects of EGCG and its non-esterified counterpart EGC on the expression of the collagenases, matrix metalloproteinases (MMP)-1 and -13, and the stromelysin, MMP-3, in human tendon-derived fibroblasts. Interleukin (IL)-1beta increased MMP-1, -3 and -13 mRNA and output at least 30-fold. EGCG reduced this stimulation, by 20-30% at 2.5 microM and more than 80% at 25 microM, and had a smaller effect on MMP-2 mRNA expression, which was not stimulated by IL-1beta. In all experiments EGCG was at least 10-fold more potent than EGC. EGCG reduced the stimulation of p54 JNK/SAPK phosphorylation by IL-1beta but did not affect p38 MAPK phosphorylation, the degradation of IkappaB or the activating phosphorylation of NFkappaB. We conclude that EGCG reduces the IL-1-stimulated expression of both collagenase and stromelysin mRNA species, an effect which may be mediated by inhibition of the JNK/SAPK pathway. Taken together with previous reports of EGCG effects on the expression and/or activity of gelatinases and aggrecanases, our results underline the importance of extracellular matrix breakdown as a potential target for the actions of green tea polyphenols.