Claassen Horst, Schlüter Matthias, Schünke Michael, Kurz Bodo
Institute of Anatomy and Cell Biology, Martin-Luther-University of Halle-Wittenberg, Grosse Steinstrasse 52, D-06097 Halle, Saale, Germany.
Bone. 2006 Aug;39(2):310-7. doi: 10.1016/j.bone.2006.02.067. Epub 2006 May 2.
Clinical observations have suggested a relationship between osteoarthritis and a changed estrogen metabolism in menopausal women. Type II collagen is one main structural protein of articular cartilage matrix and its synthesis is increased by insulin in growth plate cartilage. Therefore, it was investigated if [(3)H]-proline incorporation and type II collagen synthesis (immunocytochemistry, ELISA) in female bovine articular chondrocytes are affected by 17beta-estradiol and/or insulin. Articular chondrocytes were cultured in monolayers at 5% O(2) in medium containing serum for 5-9 days, followed by application of 10(-13) to 10(-9) M estradiol or 5 microg/ml insulin during a serum-free culture phase of 2-3 days. Immunostaining for type II collagen was strong in the serum-free culture phase whereas it was negative for type I collagen, indicating that cells did not dedifferentiate to fibroblast-like cells during culture in serum-free medium. Whereas insulin raised the proline incorporation and the type II collagen synthesis significantly, physiological doses of estradiol did not show significant effects. The stimulating effect of insulin on the [(3)H]-proline incorporation or the type II collagen synthesis was significantly suppressed after preincubation of cells with 10(-11) to 10(-9) M estradiol resembling an unfavorable effect for articular cartilage. The suppression was reversed if cells were incubated with 10(-11) to 10(-7) M tamoxifen or ICI 182,780 combined with 10(-11) or 10(-9) M estradiol followed by incubation with 5 microg/ml insulin, indicating an estrogen receptor-mediated process. Because the articular cartilage of diabetic patients is biomechanically less stable, further experiments are needed to clarify the role of estradiol and insulin in the metabolism of articular chondrocytes.
临床观察表明，骨关节炎与绝经后女性雌激素代谢变化之间存在关联。II型胶原蛋白是关节软骨基质的一种主要结构蛋白，其合成在生长板软骨中会因胰岛素而增加。因此，研究了17β-雌二醇和/或胰岛素是否会影响雌性牛关节软骨细胞中[³H]-脯氨酸掺入及II型胶原蛋白合成（免疫细胞化学、酶联免疫吸附测定）。关节软骨细胞在含血清的培养基中于5%氧气条件下单层培养5 - 9天，随后在2 - 3天的无血清培养阶段施加10⁻¹³至10⁻⁹ M的雌二醇或5 μg/ml胰岛素。在无血清培养阶段，II型胶原蛋白免疫染色强，而I型胶原蛋白为阴性，表明细胞在无血清培养基培养期间未去分化为成纤维细胞样细胞。胰岛素显著提高了脯氨酸掺入及II型胶原蛋白合成，而生理剂量的雌二醇未显示出显著影响。在用10⁻¹¹至10⁻⁹ M雌二醇预孵育细胞后，胰岛素对[³H]-脯氨酸掺入或II型胶原蛋白合成的刺激作用被显著抑制，这对关节软骨似乎产生了不利影响。如果细胞先用10⁻¹¹至10⁻⁷ M他莫昔芬或ICI 182,780与10⁻¹¹或10⁻⁹ M雌二醇共同孵育，然后再与5 μg/ml胰岛素孵育，这种抑制作用会被逆转，表明这是一个雌激素受体介导的过程。由于糖尿病患者的关节软骨生物力学稳定性较差，需要进一步实验来阐明雌二醇和胰岛素在关节软骨细胞代谢中的作用。
