糖基化终产物诱导牛视网膜毛细血管周细胞凋亡及凋亡调节基因的表达

目的　研究糖基化终产物 (advancedglycosylationendproducts,AGE)对培养的牛视网膜毛细血管周细胞凋亡及凋亡调节基因Bax、bcl 2表达的影响 ,以探讨糖尿病视网膜病变的发病机制。方法　在体外培养 3～ 6代近融合的视网膜毛细血管周细胞中加入不同浓度的AGE(8、32、12 5、5 0 0及2 0 0 0mg/L)液 ,于 4d后检测不同浓度AGE对牛视网膜毛细血管周细胞凋亡及凋亡调节基因Bax、bcl 2表达的影响。结果　周细胞与AGE作用 4d后 ,呈现出典型的细胞凋亡特征 ;AGE促周细胞凋亡(r=0 878,P <0 0 1)和凋亡调节基因Bax的表达 (r=0 85 5 ,P <0 0 1)及抑制凋亡调节基因bcl 2的表达 (r=- 0 85 0 ,P <0 0 1)呈剂量依赖性 ;而周细胞凋亡率与Bax/bcl 2的比率呈正相关 (r=0 80 8,P<0 0 1)。结论　AGE能以剂量依赖的方式促进周细胞的凋亡 ,周细胞的凋亡率取决于凋亡调节基因Bax/bcl 2的比率。细胞凋亡是糖尿病视网膜病变中毛细血管周细胞早期丧失的一种方式。

Advanced glycation end products induce apoptosis and expression of apoptotic genes in cultured bovine retinal capillary pericytes

Objective The purpose of the present study was to examine whether advanced glycation end products (AGE) contribute to the development of apoptosis and expression of apoptotic genes in cultured bovine retinal capillary pericytes (BRPs),in order to investigate retinal microvascular pathologic process during early stage of diabetic retinopathy Methods After a 4 day incubation with various concentrations of AGE (8, 32, 125, 500, 2 000 mg/L) which were prepared in vitro by incubating bovine serum albumin (BSA) with glucose, we studied the degree of apoptosis and the expressions of apoptotic genes (Bax and bcl 2) in BRPs by staining with the Annexin V FITC and propidium iodide (PI), terminal deoxynucleotidyl transferase mediated dUTP nick end labeling (TUNEL) and immunohistochemistry Results (1)After a 4 day incubation with various concentrations of AGE, BRPs showed typical changes of apoptosis, i e shrunken cell size, nuclear condensation associated with DNA fragmentation, a relatively intact cell membrane, and loss of cell viability eventually (2)AGE could induce significant apoptosis of BRPs in a dose dependent manner as compared with normal cultures or the albumin group not treated by glucose ( r =0 878, P <0 01) (3)After a 4 day incubation, the level of pro apoptotic gene Bax was upregulated ( r =0 855, P <0 01), whereas the level of pro survival gene bcl 2 was downregulated by AGE in a dosedependent manner ( r =-0 850, P <0 01) (4)There was a positive correlation between apoptotic rate and Bax bcl 2 ratio of BRPs induced by AGE ( r =0 808, P <0 01) Conclusions AGE can induce a significant apoptosis of BRPs in a dose dependent manner and the rate of apoptosis was determined by the Bax/bcl 2 ratio These results suggest that the selective loss of pericytes in diabetic retinopathy involves an apoptotic process