Estrogen/Relaxin Induce While Progesterone Represses MMP Expression in TMJ Fibrochondrocytes

Objectives: Because TMJDs are highly prevalent in women of reproductive age, it has been hypothesized that female hormones contribute to their initiation or progression. Previously, we have demonstrated that relaxin (R) and / or estrogen (E) increase the expression of specific MMPs in TMJ fibrochondrocytes. In this study we used mice TMJ fibrochondrocytes to (1) characterize which MMPs from the family of MMPs and their inhibitors TIMPs are regulated by the hormones, (2) detail the effects of these hormones on those MMPs that are regulated, and (3) determine the effects of progesterone (P) on the regulation of MMPs. Methods: Early-passage female mouse TMJ fibrochondrocytes in serum-free medium were treated with E (0.1ng/ml), R (0.1ng/ml), P (10ng/ml), or combinations of these hormones for 48 hours, and assayed by MMP/TIMP gene array, qRT-PCR, FITC-collagenase assay, substrate zymography and Western-blot. Results: E and/or R specifically induced MMP-3, -9 and -13. P alone or in combination with other hormones maintained or reduced the expression of all MMPs. In contrast, E and/or R reduced the expression of TIMP-1 and -2 while P maintained them at baseline levels. TIMP-3 was not regulated by any of the hormones. qRT-PCR assays showed that E and/or R produced between a 1.5 to 2.5 fold-increase in MMP-3, -9 and -13. Progesterone alone or together with E and/or R maintained the levels of MMP-3 and -9 at baseline levels and significantly reduced that of MMP-13 below control levels. Western blots and collagenase activity assays confirmed these findings. Conclusion: We show that R and/or E specifically induce MMP-3, -9 and -13 and downregulate of TIMP-1 and -2 by in mice TMJ fibrochondrocytes implying an increase in net matrix degradative activity. We also show for the first time that progesterone attenuates the R and/or E-mediated induction of MMPs in TMJ fibrochondrocytes.