阻断肾素-血管紧张素系统对肾小球硬化大鼠肾TGFβ1的影响及意义

摘要

目的探讨阻断肾素-血管紧张素系统(RAS)对肾小球硬化大鼠肾组织转化生长因子β1(TGF β1)基因及蛋白表达的影响及其意义.方法SD大鼠40只,其中30只单侧肾切除加阿霉素(6 mg/kg)尾静脉注射制作肾小球硬化大鼠模型,大鼠随机分成肾小球硬化组(D组),肾小球硬化苯那普利治疗组(DB组)和肾小球硬化芦沙坦治疗组(DL组),每组各10只;另10只为假手术(对照)组(C组),尾静脉注射生理盐水.DB组每日苯那普利(10 mg/kg.d)灌胃,DL组每日芦沙坦(40mg/kg.d)灌胃,C组及D组每日用相应量生理盐水灌胃.治疗6周后应用逆转录聚合酶链反应在基因水平检测肾皮质TGFβ1mRNA和Ⅳ型胶原(ColⅣ)mRNA的表达,Western蛋白质印迹检测TGFβ1蛋白的表达,免疫组织化学方法测定肾组织ColⅣ的含量,并分析肾脏的病理改变,测定血白蛋白、胆固醇、尿素氮和肌酐以及24h尿蛋白的含量.结果D组出现大量蛋白尿、低蛋白血症及高胆固醇血症,与C组比较有显著性差异(P＜0.05),血尿素氮及肌酐也上升,肾小球系膜细胞增生,细胞外基质沉积,肾皮质TGFβ1mRNA和蛋白的表达分别比对照组增加3.59倍和2.60倍,ColⅣmRNA和蛋白表达分别比对照组增加2.57倍和1.40倍.应用苯那普利及芦沙坦治疗6周后,DB组及DL组的血、尿生化改变明显改善,病理改变减轻.肾皮质TGFβ1mRNA和蛋白表达分别下调46%,53%,55%和59%,ColⅣ表达也降低.TGFβ1表达与肾小球细胞外基质Ⅳ型胶原,肾小球硬化指数和肾小管间质损伤指数存在明显的正相关(P＜0.05).结论应用苯那普利和芦沙坦阻断RAS,可能通过对TGFβ1mRNA及蛋白的下调作用减少肾小球细胞外基质的沉积.%Objective: To study the influence of blocking renin-angiotensin system (RAS) on gene and protein expression of transforming growth factor β1 (TGFβ1) and its significance in renal tissue of rat glomerulosclerosis model. Methods: There were 40 SD rats in the study. Among them 30 rats were made into glomerulosclerosis models by resecting one side of kidney and injecting Adriblastine. These rats were divided randomly into glomerulosclerosis (nephrosis) group (group D), glomerulosclerosis treated with Benazepril group (group DB), glomerulosclerosis treated with Losartan group (group DL) with 10 rats in each group. The remaining 10 ones were taken as sham-operation (control) group (group C), injected with normal saline into caudal vein. Rats in group DB were given Benazepril (10mg/kg.d)) through gastric administration. Rats in group DL were given Losartan (40 mg/kg.d) through gastric administration. Rats in group C and D were given normal saline of corresponding volume every day through gastric administration. After 6 weeks of treatment,the expressions of TGFβ1 mRNA and type Ⅳ collagen (Col Ⅳ) mRNA in renal cortex were tested using reverse transcription polymerase chain reaction. The expression of TGFβ1 protein was tested using Western blot.The content of Col Ⅳ in renal cortex was measured using immunohistochemical method. The renal pathological changes were analyzed. Blood albumin, cholesterol, BUN, creatinine and 24-hour urine protein were tested. Results: Group D presented with massive proteinuria, hypoalbuminemia and hypercholesterolemia, which had a significant difference with group C (P＜0.05). BUN and creatinine were elevated. There were glomerular mesangial proliferation and extracellular matrix deposit. The expressions of TGFβ1 mRNA and protein increased 3.59 and 2.60 times respectively more than the control. The expressions of Col Ⅳ mRNA and protein increased 2.57 and 1.40 times respectively more than the control. After 6 weeks of treatment with Benazepril and Losartan, blood and urine biochemical changes were significantly improved in groups DB and DL and so were the pathological changes. The expressions of TGFβ1 mRNA and protein were downregulated 46%, 53%,55% and 59%, respectively. The expression of Col Ⅳ also decreased. The expression of TGFβ1 had significant positive correlations with glomerular extracellular matrix type Ⅳ collagen, glomerular assault index (GAI)and renal tubule interstitial assault index (IAI) (P＜0.05). Conclusion: Blocking RAS with Benazepril and Losartan could decrease the glomerular extracellular matrix deposit probably through the downregulation of TGFβ1 mRNA and protein.