Ma Tian-Kui, Xu Li, Lu Ling-Xu, Cao Xu, Li Xin, Li Lu-Lu, Wang Xu, Fan Qiu-Ling
Department of Nephrology, The First Hospital of China Medical University, Shenyang, Liaoning, People's Republic of China.
Department of Clinical Laboratories, The First Hospital of China Medical University, Shenyang, Liaoning, People's Republic of China.
Diabetes Metab Syndr Obes. 2019 Dec 9;12:2597-2608. doi: 10.2147/DMSO.S222323. eCollection 2019.
This study aimed to investigate whether ursolic acid (UA) mitigates renal inflammation, oxidative stress and fibrosis by regulating the angiotensin II type 1 receptor-associated protein (ARAP1)/angiotensin II type 1 receptor (AT1R) signaling pathway and subsequently alleviating renal damage.
db/db mice were divided randomly into a diabetic nephropathy (DN) group and a UA treatment group. Light microscopy and electron microscopy were used to observe pathological changes in renal tissues. Immunohistochemistry (IHC) was employed to examine changes in the expression of ARAP1, AT1R, 8-hydroxydeoxyguanosine (8-OHdG), NADPH oxidase 2 (NOX2), the extracellular matrix protein fibronectin (FN), IL-1β and IL-18 in renal tissues. Western blotting and RT-qPCR were used to detect the respective changes in the protein and mRNA levels of ARAP1, AT1R, NOX4, NOX2, transforming growth factor-β1 (TGF-β1), FN, collagen IV, IL-1β and IL-18 in renal tissues and mesangial cells. In addition, immunofluorescence staining was employed to examine changes in FN and NOX2 expression in mesangial cells.
UA treatment effectively reduced the body weights and blood glucose levels of db/db mice (p<0.05) as well as the urinary albumin/creatinine ratio (p<0.05). In addition, the renal tissue lesions and glomerulosclerosis index of the db/db mice were significantly improved after treatment (p<0.01). Histochemical analysis results showed significantly lower expression levels of ARAP1, AT1R, FN, NOX2, 8-OHdG, IL-1β and IL-18 in renal tissues in the UA treatment group than in the DN group. Western blotting and RT-qPCR data also revealed UA-induced decreases in the renal levels of the ARAP1, AT1, NOX4, NOX2, TGF-β1, FN, collagen IV, IL-1β and IL-18 proteins in vivo and/or in vitro (p<0.01). ARAP1 knockdown effectively reduced the expression of NOX2 and FN in vitro.
UA alleviated renal damage in type 2 diabetic db/db mice by downregulating proteins in the ARAP1/AT1R signaling pathway to inhibit extracellular matrix accumulation, renal inflammation, fibrosis and oxidative stress.
本研究旨在探讨熊果酸（UA）是否通过调节血管紧张素II 1型受体相关蛋白（ARAP1）/血管紧张素II 1型受体（AT1R）信号通路减轻肾脏炎症、氧化应激和纤维化，进而减轻肾脏损伤。
将db/db小鼠随机分为糖尿病肾病（DN）组和UA治疗组。采用光学显微镜和电子显微镜观察肾脏组织的病理变化。采用免疫组织化学（IHC）检测肾脏组织中ARAP1、AT1R、8-羟基脱氧鸟苷（8-OHdG）、NADPH氧化酶2（NOX2）、细胞外基质蛋白纤连蛋白（FN）、IL-1β和IL-18表达的变化。采用蛋白质印迹法和RT-qPCR检测肾脏组织和系膜细胞中ARAP1、AT1R、NOX4、NOX2、转化生长因子-β1（TGF-β1）、FN、IV型胶原、IL-1β和IL-18蛋白和mRNA水平的相应变化。此外，采用免疫荧光染色检测系膜细胞中FN和NOX2表达的变化。
UA治疗有效降低了db/db小鼠的体重和血糖水平（p<0.05）以及尿白蛋白/肌酐比值（p<0.05）。此外，治疗后db/db小鼠的肾脏组织病变和肾小球硬化指数显著改善（p<0.01）。组织化学分析结果显示，UA治疗组肾脏组织中ARAP1、AT1R、FN、NOX2、8-OHdG、IL-1β和IL-18的表达水平明显低于DN组。蛋白质印迹法和RT-qPCR数据还显示，UA在体内和/或体外均可使肾脏中ARAP1、AT1、NOX4、NOX2、TGF-β1、FN、IV型胶原、IL-1β和IL-18蛋白水平降低（p<0.01）。ARAP1基因敲低有效降低了体外NOX2和FN的表达。
UA通过下调ARAP1/AT1R信号通路中的蛋白质表达，抑制细胞外基质积聚、肾脏炎症、纤维化和氧化应激，从而减轻2型糖尿病db/db小鼠的肾脏损伤。
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