糖肾方基于SP1/PGC-1α途径改善糖尿病肾脏脂质沉积的机制研究

Diabetic nephropathy (DN) is the leading cause of end stage renal disease. Renal lipid accumulation is one of major underlying mechanisms contributing to renal injury and the development of albuminuria in diabetic condition. Specificity protein 1 (SP1) plays a key role in regulation of renal fibrosis, podocyte injury and renal lipid metabolism. In the previous study, we found that Tangshen Formula (TSF) can significantly alleviate lipid accumulation in the kidney and delay DN progression. Meanwhile, renal cholesterol efflux was increased markedly after TSF treatment. In the current proposal, we will investigate the effect of SP1 and PGC-1α on the lipid accumulation in renal cells. The effect of TSF on the SP1 and PGC-1α are carried out in db/db mouse model and cells. In addition, the effect of TSF on regulating the activity of SP1 and PGC-1α is analyzed. The study will reveal the mechanism of TSF alleviates renal lipid accumulation, which will provide scientific clues in clinical use in treating DN.

肾脏脂质沉积是糖尿病肾病（DN）发生发展的重要因素，与中医“脉络瘀阻”有关，DN情况下肾脏脂质沉积明显，导致“瘀阻肾络”，进一步加重肾脏损伤。最近研究显示，特殊蛋白1（SP1）在DN肾脏纤维化、足细胞损伤中具有重要作用，同时还可调节肾脏脂代谢紊乱，但SP1在PGC-1α介导的DN肾脏脂质沉积中的作用尚无相关报道。申请人前期研究发现中药糖肾方可通过PGC-1α/LXR/ABCA1途径，显著增加肾脏中胆固醇流出，改善DN肾脏脂质沉积。本研究利用Sp1-siRNA干预小鼠肾小管上皮细胞，使用激光共聚焦显微镜观察，明确SP1在PGC-1α介导的脂质沉积中的作用；继而采用db/db小鼠模型验证糖肾方下调SP1表达，继而上调PGC-1α的表达，改善肾脏脂质沉积，延缓DN进展的科学假说；在细胞水平明确糖肾方对SP1/PGC-1α的调控机制，从而阐释糖肾方益气养阴、活血通络的科学内涵。

肾脏脂质沉积是糖尿病肾病（diabetic nephropathy, DN）发生发展的重要因素，与中医“脉络瘀阻”有关，DN情况下肾脏脂质沉积明显，导致“瘀阻肾络”，进一步加重肾脏损伤。申请人前期研究发现中药糖肾方可改善糖尿病肾脏脂质沉积，但特殊蛋白1（specificity protein 1, SP1）在PGC-1α介导的DN肾脏脂质沉积中的作用尚无相关报道。本研究利用了db/db小鼠模型和SP1-siRNA干预棕榈酸钠诱导的小鼠肾小管上皮细胞模型，发现糖肾方上调PGC-1α表达，改善db/db小鼠肾脏及棕榈酸钠诱导的mTECs中脂质氧化及胆固醇流出，继而减轻肾脏脂质沉积；PGC-1α-siRNA干预后，糖肾方改善棕榈酸钠诱导的mTECs的脂质氧化及胆固醇流出的作用受到抑制；Sp1-siRNA干预后促进糖肾方上调PGC-1α表达作用，Sp1-shRNA干预后抑制糖肾方上调PGC-1α表达作用；糖肾方可通过上调FXR，抑制db/db小鼠肾脏及棕榈酸钠诱导的mTECs的纤维化；糖肾方中的活性成分莫诺苷具有促进棕榈酸钠或高糖诱导的mTECs的胆固醇流出的作用。由此证实糖肾方可通过抑制Sp1表达，继而改善PGC-1α介导的DN肾脏脂质沉积。