Wang Yanqiu, Liu Na, Bian Xiaohui, Sun Guangping, Du Feng, Wang Bowen, Su Xuesong, Li Detian
Department of Nephrology, Shengjing Hospital of China Medical University, Shenyang, Liaoning, People's Republic of China.
Department of Nephrology, Ordos Central Hospital, Ordos, Inner Mongolia, People's Republic of China.
J Surg Res. 2015 Jul;197(1):145-54. doi: 10.1016/j.jss.2015.03.034. Epub 2015 Mar 26.
Tubular cell apoptosis plays a crucial role in different kinds of renal diseases. Epigallocatechin-3-gallate (EGCG), a polyphenol extracted from green tea, has been shown to inhibit renal fibrosis in unilateral ureteral obstruction (UUO) mice, but its role in preventing tubular cell apoptosis and the underlying signaling mechanisms still remains unclear.
Mice subjected to UUO were intraperitoneally administered EGCG (5 mg/kg) for 14 d. Normal rat kidney proximal tubular epithelial cell line NRK-52E was induced by transforming growth factor β1 (TGF-β1). Periodic acid-schiff and Masson's trichrome staining was used for histologic study. TUNEL, Hoechst staining, and flow cytometry analysis were used to measure the apoptotic status of tubular cells. Western blotting was used to determine the expression of apoptotic-associated proteins and mitogen-activated protein kinase pathway proteins.
EGCG significantly attenuated tubular injury and renal tubulointerstitial fibrosis in the obstructed kidneys of UUO mice. In addition, EGCG prevented UUO and TGF-β1-induced tubular apoptosis in a dose-dependent manner. In parallel, protein expression of B-clell lymphoma-2 (Bcl-2) was upregulated and protein expressions of Bcl-2 accosiated X protein (Bax), cleaved caspase 3, and cleaved poly ADP-ribose polymerase (PARP) were downregulated by EGCG. Furthermore, UUO and TGF-β1-stimulated phosphorylation of mitogen-activated protein kinase was inhibited by EGCG.
EGCG effectively reduces tubular cell apoptosis induced by UUO and may have potential as a clinical treatment in patients with chronic kidney disease.
肾小管细胞凋亡在各类肾脏疾病中起关键作用。表没食子儿茶素-3-没食子酸酯（EGCG）是一种从绿茶中提取的多酚，已被证明可抑制单侧输尿管梗阻（UUO）小鼠的肾纤维化，但其在预防肾小管细胞凋亡中的作用及潜在信号机制仍不清楚。
对接受UUO的小鼠腹腔注射EGCG（5毫克/千克），持续14天。用转化生长因子β1（TGF-β1）诱导正常大鼠肾近端小管上皮细胞系NRK-52E。采用高碘酸-希夫染色和Masson三色染色进行组织学研究。用TUNEL、Hoechst染色和流式细胞术分析来测量肾小管细胞的凋亡状态。用蛋白质印迹法测定凋亡相关蛋白和丝裂原活化蛋白激酶途径蛋白的表达。
EGCG显著减轻了UUO小鼠梗阻肾脏的肾小管损伤和肾小管间质纤维化。此外，EGCG以剂量依赖方式预防了UUO和TGF-β1诱导的肾小管凋亡。同时，EGCG上调了B细胞淋巴瘤-2（Bcl-2）的蛋白表达，下调了Bcl-2相关X蛋白（Bax）、裂解的半胱天冬酶3和裂解的聚ADP核糖聚合酶（PARP）的蛋白表达。此外，EGCG抑制了UUO和TGF-β1刺激的丝裂原活化蛋白激酶的磷酸化。
EGCG有效减少UUO诱导的肾小管细胞凋亡，可能具有作为慢性肾病患者临床治疗方法的潜力。
