大鼠残肾细胞凋亡及凋亡相关基因的动态表达及意义

目的： 研究在5/6肾切除大鼠不同时段残肾组织中肾实质细胞凋亡及相关基因Bax、Bcl-2、caspase-3、caspase-8、caspase-9 mRNA、蛋白质的动态表达变化及其意义。 方法: SD大鼠5/6肾切除后,分别在1周、2周、4周、8周、12周、16周、26周、40周采集标本，普通光镜、电镜观察残肾病理改变、TUNEL法检测肾脏细胞凋亡、RT-PCR和Western blotting检测残肾组织凋亡相关基因mRNA和蛋白质的变化、免疫组织化学进行蛋白质定位，分析凋亡、增殖与肾小球硬化和间质纤维化的相关关系。 结果: 5/6肾切除后大鼠残肾出现进行性肾小球硬化及间质纤维化病变。肾增殖与凋亡水平高于对照组，肾实质凋亡细胞以肾小管上皮细胞和肾间质细胞为主。肾小球凋亡指数与肾间质炎细胞浸润和24 h尿蛋白呈显著正相关(r=0.788、r=0.822,P<0.01);肾小管凋亡指数与血肌酐、尿素氮、24 h尿蛋白、炎细胞浸润指数呈显著正相关（r=0.824、0.794、0.883、0.948，P<0.01）。促凋亡相关基因Bax、caspase-3、caspase-8、caspase-9mRNA及相应蛋白质明显增加且表达一致，在病变过程中呈波浪式上调，高峰分别在4周和40周，这些变化与肾间质炎细胞浸润指数的变化呈显著正相关（P<0.01）；抑制凋亡因子Bcl-2表达与对照组比较无明显差异。 结论: 细胞凋亡参与肾小球硬化、肾小管萎缩及间质纤维化的过程，肾间质炎细胞的浸润更促进残肾凋亡的发生。

Apoptosis and expression of apoptosis-related genes in kidneys of the rats with 5/6 nephrectomy

AIM: To establish a model of subtotal nephrectomy (SNx) and investigate the changes of apoptosis and apoptosis-related genes (Bax, bcl-2, caspase-3, caspase-8 and caspase-9) in the rat remnant kidney. METHODS: Remnant kidneys were produced in adult male SD rats by 5/6 nephrectomy. The renal function and histopathological changes were evaluated at 1, 2, 4, 8, 12, 16, 26 and 40 weeks after operation. The tissues of remnant kidneys were collected to detect apoptosis cells by in situ end-labeling of cleaved DNA (TUNEL) and proliferating cells by determining the proliferating cell nuclear antigen (PCNA). The expression of Bax, bcl-2, caspase-3, caspase-8 and caspase-9 was measured by RT-PCR and Western blotting. The proteins were detected by immunohistochemistry staining. The relation between apoptosis, proliferation, glomerulosclerosis and renal interstitial fibrosis was also observed. RESULTS: The results showed the renal pathological dynamic changes in 5/6 nephrectomy remnant kidneys were tubule-interstitial inflammation and fibrosis, as well as glomerulosclerosis. There were transient increases in both proliferating and apoptotic processes in glomerulus, tubules and interstitium. Apoptosis was increased and most of apoptotic cells were detected in tubular epithelial cells and interstitial area. The mRNA and protein expression of Bax, caspase-3, caspase-8 and caspase-9 were increased in all course, and peaked at week 4 and 40 in the SNX rats. The successive changes of these parameters were parallel to the level of focal inflammation in interstitium. Glomerulosclerosis index was related with focal inflammation cells and 24 hours urine protein (r=0.788, 0.822; P<0.01). The tubuler apoptosis index was related with Scr, BUN, 24 hours urine protein and focal inflammation cells (r=0.824, 0.794, 0.883, 0.948; P<0.01). The mRNA and protein expression of Bcl-2 was not significantly increased than those in control rats. CONCLUSION: Apoptosis may be involved in the development of chronic renal damaged in 5/6 nephrectomy and play an important role in chronic glomerulosclerosis, tubule atrophy and interstitial fibrosis. The renal interstitial inflammation may promote the apoptosis in the remnant kidney.