雌激素缺乏导致的骨质疏松发病过程中骨髓间充质干细胞FasL表达降低对CD4+T淋巴细胞凋亡的影响

 目的：研究雌激素在骨质疏松发病过程中导致骨髓间充质干细胞（BMMSCs）Fas配体（FasL）表达降低对CD4+T淋巴细胞凋亡的作用。方法：选用8周龄健康雌性小鼠行双侧卵巢切除术(OVX)，建立绝经后骨质疏松模型。选用同一批次周龄相同、体重相近的健康小鼠行双侧卵巢附近脂肪组织部分切除，建立假手术组（sham），Micro-CT确定模型成功建立。流式细胞术对BMMSCs行表型鉴定，将OVX组、sham组和sham+雌激素刺激组BMMSCs与激活的T淋巴细胞共培养，以Annexin V/7-AAD/CD4流式细胞仪计数3组共培养体系中CD4+T淋巴细胞的凋亡差异，用实时荧光定量PCR和Western blotting检测OVX组、sham组及不同浓度雌激素刺激BMMSCs后FasL的表达情况。结果：流式检测显示sham+雌激素刺激组CD4+T淋巴细胞凋亡程度大于sham组(P<0.05)，sham组CD4+T淋巴细胞凋亡程度大于OVX组(P<0.05)，实时荧光定量PCR及Western blotting显示OVX组FasL mRNA及蛋白水平表达都较sham组低。在一定范围内不同浓度雌激素刺激下的sham组BMMSCs中FasL mRNA及蛋白表达与雌激素浓度呈梯度上升。结论：雌激素能够调控BMMSCs中FasL的表达，雌激素调控BMMSCs表达FasL能够影响CD4+T淋巴细胞凋亡的改变,这可能与绝经后骨质疏松发病相关。

Effect of FasL expression in bone marrow mesenchymal stem cells on CD4+ T-lymphocyte apoptosis during estrogen deficiency-induced osteoporosis

AIM：To investigate the effect of FasL expression in bone marrow mesenchymal stem cells (BMMSCs) on CD4+ T-lymphocyte apoptosis  during osteoporosis (OP) under the condition of estrogen deficiency. METHODS：An animal model of OP was established by ovariectomy (OVX, bilateral ovarian resection) in 8-week-old healthy female mice. T-lymphocytes were divided into OVX group, sham group and estradiol-stimulated group, and co-cultured with the BMMSCs from the mice. The comparison of CD4+ T-lymphocyte apoptosis among the 3 groups was performed. The level of FasL expression was detected by Western blotting and real-time PCR. RESULTS：The apoptosis of CD4+ T-lymphocytes was significantly higher in sham group than that in OVX group. The expression of FasL at mRNA and protein levels was lower in OVX group than that in sham group, and was increased by estrogen in a concentration-dependent manner. CONCLUSION：Expression of FasL is regulated by estrogen in BMMSCs. The change of FasL affects apoptosis of CD4+ T-lymphocytes, which may be an important mechanism in the pathogenesis of postmenopausal osteoporosis.