Department of Pathophysiology and Therapeutics of Diabetic Vascular Complications, Kurume University School of Medicine, Kurume 830-0011, Fukuoka, Japan.
Pharmacol Res. 2010 Jan;61(1):34-9. doi: 10.1016/j.phrs.2009.07.004. Epub 2009 Jul 25.
Renin-angiotensin system (RAS) plays a central role in the development and progression of diabetic nephropathy. Further, there is a growing body of evidence that advanced glycation end products (AGEs) and their receptor (RAGE) axis also contributes to diabetic nephropathy. However, the pathophysiological crosstalk between the RAS and AGE-RAGE system in tubular cell injury, which is more important than glomerulopathy in terms of renal prognosis in diabetic nephropathy, remains unknown. In this study, we examined whether and how irbesartan, an angiotensin II type 1 receptor blocker (ARB), inhibited the AGE-induced tubular cell apotptosis and damage in vitro. Gene expression was analyzed by quantitative real-time reverse transcription-polymerase chain reactions. Intracellular formation of reactive oxygen species (ROS) was measured with dihydroethidium staining. Apoptosis levels were evaluated for DNA fragments with an enzyme-linked immunosorbent assay kit and for caspase-3 activity. Irbesartan inhibited the AGE-induced up-regulation of RAGE mRNA levels and subsequently reduced ROS generation in human proximal tubular cells. AGEs induced apoptosis and increased inflammatory, thrombogenic and fibrogenic gene expressions in tubular cells, which were also blocked by the treatment with irbesartan. Our present data suggest that there exists a crosstalk between the RAS and AGE-RAGE system in tubular cell apoptosis and damage. Blockade of the RAS by irbesartan may play a protective role against tubular injury in diabetes by attenuating the deleterious effects of AGEs via down-regulation of RAGE.
肾素-血管紧张素系统（RAS）在糖尿病肾病的发生和发展中起着核心作用。此外，越来越多的证据表明，晚期糖基化终产物（AGEs）及其受体（RAGE）轴也有助于糖尿病肾病。然而，RAS 和 AGE-RAGE 系统在肾小管细胞损伤中的病理生理学相互作用尚不清楚，而在糖尿病肾病的肾脏预后方面，肾小管细胞损伤比肾小球病变更为重要。在这项研究中，我们研究了血管紧张素 II 型 1 型受体阻滞剂（ARB）厄贝沙坦是否以及如何抑制 AGE 诱导的体外肾小管细胞凋亡和损伤。通过实时定量逆转录聚合酶链反应分析基因表达。用二氢乙啶染色测量细胞内活性氧（ROS）的形成。通过酶联免疫吸附测定试剂盒评估 DNA 片段的凋亡水平和 caspase-3 活性。厄贝沙坦抑制 AGE 诱导的 RAGE mRNA 水平上调，随后减少人近端肾小管细胞中 ROS 的产生。AGEs 诱导肾小管细胞凋亡，并增加炎症、血栓形成和纤维生成基因的表达，这些表达也被厄贝沙坦的治疗所阻断。我们目前的数据表明，RAS 和 AGE-RAGE 系统在肾小管细胞凋亡和损伤中存在相互作用。通过 RAGE 的下调，厄贝沙坦阻断 RAS 可能通过减轻 AGE 的有害作用，在糖尿病中发挥保护肾小管损伤的作用。
