半胱氨酸天冬氨酸蛋白酶在视网膜毛细血管周细胞凋亡中的活性及意义

目的探讨糖基化终产物（AGE）在糖尿病视网膜病变（DR）发生中的作用。方法培养的牛视网膜毛细血管周细胞分别与不同浓度（0．47、1．88、7．50μmol／L）的AGE共同培养4d后,分别检测细胞凋亡、半胱氨酸天冬氨酸蛋白酶（caspase-3）活性及caspase-3抑制剂Z—DEVD-fmk对周细胞凋亡及凋亡调节基因Bcl-2／Bax比率的影响。结果AGE能以剂量依赖的方式诱导培养的牛视网膜毛细血管周细胞凋亡（r=0．867,P〈0．01）、增加细胞内caspase-3的活性,而选择性caspase-3抑制剂Z—DEVD—fmk能明显抑制AGE作用下的周细胞凋亡及提高凋亡调节基因Bcl-2／Bax的比率。结论凋亡是DR中视网膜毛细血管周细胞选择性丧失的机制之一,caspase-3活性的增加是AGE诱导周细胞发生凋亡的关键因素。

The effects of caspase-3 in apoptosis of cultured retinal microvascular pericytes induced by advanced glycation end products

OBJECTIVE: One of the earliest changes observed in the development of diabetic retinopathy (DR) is the selective loss of pericytes and acellular capillaries. We tested the hypothesis that advanced glycation end products (AGE) might be involved in the disappearance of retinal pericytes by apoptosis and further investigated the activity and effect of caspase-3 at the same time. METHODS: Cultured bovine retinal microvascular pericytes (BRPs) were exposed to various concentrations of advanced glycation end products-bovine serum albumin (AGE, 0.47, 1.88, 7.50 micromol/L) for 4 days. We assayed the degree of pericytes apoptosis by fluorescence activated cell sorting, and further measured the caspase-3 activity and the effect of selective caspase-3 inhibitor Z-DEVD-fmk on apoptosis and the of ratio Bcl-2/Bax expression. RESULTS: The results showed that AGE could induce significantly the apoptosis of BRPs in a dose-dependent manner compared with controls (r = 0.867, P < 0.01), associated with an increase in intracellular caspase-3 activity. Selective caspase-3 inhibitor Z-DEVD-fmk inhibited pericyte apoptosis induced by AGE. CONCLUSION: These data suggest that the pericyte loss in DR involves an apoptotic process, and that activation of caspase-3 are associated with apoptotic process, which can provide new therapeutic perspectives in diabetic retinopathy.