17β-estradiol reduces expression of MMP-1, -3, and -13 in human primary articular chondrocytes from female patients cultured in a three dimensional alginate system.

Clinical observations have suggested a relationship between osteoarthritis and a changed sex-hormone metabolism, especially in menopausal women. This study analyzes the effect of 17β-estradiol on expression of matrix metalloproteinases-1, -3, -13 (MMP-1, -3, -13) and tissue inhibitors of metalloproteinases-1, -2 (TIMP-1, -2) in articular chondrocytes. An imbalance of matrix metalloproteinases (MMPs) specialized on degradation of articular cartilage matrix over the respective inhibitors of these enzymes (TIMPs) that leads to matrix destruction was postulated in the pathogenesis of osteoarthritis. Primary human articular chondrocytes from patients of both genders were cultured in alginate beads at 5% O(2) to which 10(-11)M-10(-5)M 17β-estradiol had been added and analyzed by means of immunohistochemistry, immunocytochemistry and real-time RT-PCR. Since articular chondrocytes in vivo are adapted to a low oxygen tension, culture was performed at 5% O(2). Immunohistochemical staining in articular cartilage tissue from patients and immunocytochemical staining in articular chondrocytes cultured in alginate beads was positive for type II collagen, estrogen receptor α, MMP-1, and -13. It was negative for type I collagen, MMP-3, TIMP-1 and -2. Using real-time RT-PCR, it was demonstrated that physiological and supraphysiological doses of 17β-estradiol suppress mRNA levels of MMP-3 and -13 significantly in articular chondrocytes of female patients. A significant suppressing effect was also seen in MMP-1 mRNA after a high dose of 10(-5)M 17β-estradiol. Furthermore, high doses of this hormone led to tendentially lower TIMP-1 levels whereas the TIMP-2 mRNA level was not influenced. In male patients, only incubations with high doses (10(-5)M) of 17β-estradiol were followed by a tendency to suppressed MMP-1 and TIMP-1 levels while TIMP-2 mRNA level was decreased significantly. There was no effect on MMP-13 expression of cells from male patients. Taken together, application of 17β-estradiol in physiological doses will improve the imbalance between the amounts of MMPs and TIMPs in articular chondrocytes from female patients. Downregulation of TIMP-2 by 17β-estradiol in male patients would not be articular cartilage protective.