西罗莫司阻断mTOR通路对大鼠肾纤维化的保护作用及其机制研究

目的 研究西罗莫司(Sir)阻断哺乳动物雷帕霉素靶蛋白(mTOR)通路对大鼠急性完全性梗阻所致肾脏纤维化的保护作用及其机制.方法 健康雄性Wistar大鼠42只,随机分为3组(n=14).单侧输尿管结扎组(UUO组):采用单侧输尿管结扎法建立大鼠肾纤维化模型；Sir组:从建模前1d开始每日给予Sir 2mg/kg灌胃直至实验结束；假手术组:除结扎输尿管外其他过程同UUO组.分别于实验第7天和第14天处死大鼠,取梗阻肾脏,通过病理学观察比较各组肾脏及肾小管扩张程度,并测定肾盂内梗阻性尿液的钠、钾、钙离子浓度,同时采用免疫组化法观察细胞增殖核抗原(PCNA)的表达,TUNEL法观察细胞凋亡情况,定量PCR测定纤维化相关的microRNA分子mir-155、mir-143、mir-29c的表达情况.结果 第7和第14天时,与对照组比较,UUO组和Sir组患侧肾脏均明显扩大,肾小管明显扩张,但Sir组患侧肾脏扩大程度明显小于UUO组(P＜0.01).肾小管扩张程度低于UUO组(P＜0.01).与UUO组比较,Sir组肾小管损伤程度、间质渗出、肾脏纤维化程度均明显减轻,肾盂内尿液的钠、钾、钙离子浓度明显下降(P＜0.05),PCNA阳性和凋亡细胞比例明显降低(P＜0.001).3组间比较mir-155、mir-143表达无明显差异,UUO组mir-29c表达下降,明显低于Sir组和假手术组(P＜0.01),而Sir组与假手术组比较无明显差异.结论 Sir抑制mTOR通路可以显著延缓急性完全性梗阻所致的大鼠肾脏纤维化的进展.

Protective effect of sirolimus against renal fibrosis via blockage of mTOR in rat model and its mechanism

Objective To investigate the protective effects of sirolimus on unilateral ureteral obstruction(UUO) induced renal fibrosis by blockage of mTOR and its mechanism.Methods Forty-two female rats were randomized to 3 groups: UUO group,sirolimus group(Sir group),and control group.UUO rats underwent unilateral ureteral ligation to reproduce renal fibrosis model.Sir group received sirolimus 2mg/kg wt per day(0.4ml,intragastric administration) from one day before the UUO procedure to the end of study.The control group underwent surgery but without ureteral ligation.Obstructed kidneys were harvested on 7th and 14th day,and histological examination was performed for observing and comparing the degree of renal and renal tubule expansion.The concentrations of sodium,potassium and calcium ion in the urine obtained from the pelvis of the kidneys with ligated ureters were determined.At the same time,the expression of proliferating cell nuclear antigen(PCNA) and apoptosis were observed with immunohistochemical method and TUNEL respectively.MicroRNAs quantities(mir-29c,mir-143,and mir-155) were assayed by quantitative PCR.Results At above-mentioned two time-points,swollen kidneys and expanded renal tubules were observed in UUO and Sir groups as compared to control group,however,kidney in Sir group showed significantly less swelling and than that in UUO group(P<0.01).Histological observation found tubular injury,cellular infiltration,and fibrosis were more marked in UUO group as compared to Sir group.Na+,K+ and Ca2+ of retention urine were significantly lower in Sir group than in UUO group(P<0.05).PCNA-positive cell ratio and apoptosis ratio were higher in UUO group than in Sir and control groups(P<0.01).No significant difference in expression of miR-155 or miR-143 was found between 3 groups,however,miR-29c expression in UUO group was down-regulated and significantly lower than that in control or Sir group(P<0.01).Conclusion With obstruction of the ureter,blocking mTOR pathways by sirolimus can attenuate fibrosis in the affected kidney.