他克莫司通过上调自噬作用保护2型糖尿病大鼠足细胞

Tacrolimus protects podocytes by up-regulating autophagy in type 2 diabetic model rats

目的探讨他克莫司（FK506）对2型糖尿病（T2DM）大鼠足细胞的保护作用及其可能机制。方法高糖高脂喂养联合小剂量链佐星（STZ）构建T2DM大鼠模型，模型大鼠随机分为糖尿病组（DM组）和FK506组，后者给予0．5mg·kg-1·d-1FK506干预8周，另设正常对照组。比较各组大鼠的生化指标，光镜、电镜分别观察肾脏病理和足细胞超微结构改变，免疫组织化学检测nephrin蛋白表达，Western印迹测定自噬标志蛋白微管相关蛋白1轻链3-Ⅱ（LC3-Ⅱ）的表达。结果（1）与对照组比较，DM组大鼠肾小球肥大指数（KW／BW）、空腹血糖（FBG）、血压（SBP）、胆固醇（CH）、三酰甘油（TG）、内生肌酐清除率（Ccr）、24h尿白蛋白排泄率（UAE）均明显升高（均P〈0．05），而FK506组大鼠KW／BW、Ccr、UAE均明显低于DM组（均P〈0．05），其他指标差异均无统计学意义。（2）与对照组比较，光镜下DM组大鼠肾小球体积增大，肾小球系膜细胞及系膜区基质增多；电镜下DM组大鼠足细胞数量减少，足突融合、消失。而FK506干预后上述病变明显减轻。（3）与对照组比较，DM组大鼠肾组织nephrin及LC3-Ⅱ表达均降低（均P〈0．05），而FK506组大鼠组nephrin及LC3-Ⅱ表达高于DM组（均P〈0．05）。结论FK506可能通过上调T2DM大鼠肾脏足细胞的自噬作用保护足细胞。

Objective To assess the effects of tacrolimus （FK506） on podocyte in type 2 diabetic model rats and to explore the potential mechanism. Methods The model rats were fed with high fat and high sugar food and combining with a low-dose of streptozotocin （STZ）. They were then randomly divided into a diabetic mellitus group （DM group） and a FK506 group. A normal control group （NC group） was also set. The rats in FK506 group were given with 0.5 rag. kg-1. d-1 FK506 for 8 weeks. The biochemical parameters were measured. The changes of renal pathology and ultrastrncture of podocyte were observed by the light and electron microscopy. The expression of nephrin and LC3-Ⅱ was determined by immunohistochemistry and Western blotting. Results （1） Compared with those in NC group, KW/BW, systolic blood pressure （SBP）, fasting blood glucose （FBG）, triglyceride （TG）, total cholesterol （TC）, urinary albumin excretion rate （UAE） and creatinine clearance rate （Ccr） in DM group were significantly increased （all P 〈 0.05）. And the KW/BW, UAE and Ccr were decreased in FK506 group compared to those in DM group （all P 〈 0.05）, while other parameters had no significant difference （all P 〉 0.05）. （2） Compared with those in NC group, the glomerular volume, mesangial cell proliferation and accumulation of mesangial matrix were increased, and the foot process became disorder and fusion in DM group, while these changes were significantly reduced in FK506 group. （3） Compared with that in NC group, the expression of nephrin and LC3-Ⅱ was decreased in DM group （all P 〈 0.05）, and both of parameters were higher in FK506 group than those in DM group （all P 〈 0.05）. Conclusion FK506 may enhance podocyte autophagy in type 2 diabetic model rats and attenuate podocyte injury.