NOD2介导的自噬在糖尿病肾病肾小管损伤中的作用及机制研究

The pathogenesis of the tubular injury in diabetic nephropathy (DN) is currently focused on the balance of inflammation-mediated immunity, and the role of the innate immune response has been increasingly prominent. Nucleootide-binding oligomerization domain containing 2 (NOD2), a member of cytosolic pattern recognition receptors, plays an important role in a variety of autoimmune diseases, but the role in the the mechanism of the tubular injury in DN is still unclear. Previous work demonstrated that the expression of NOD2 was significantly increased in the renal cortex from DN patients and diabetic mice, and closely related to the infiltrated inflammatory cells; Also, it was found that the NOD2 expression was significantly increased in the renal tubular epithelial cells with high glucose treatment in a concentration-dependent manner; Meanwhile the results of knockout-mice experiments showed that the deficiency of NOD2 could significantly improve the state of autophagy in renal tubular cells, suggesting that NOD2 might be involved in the autophagy injury in diabetic renal tubules. Therefore, this project aims to explore the mechanism of NOD2-mediated autophagy in the renal tubular epithelial cells and to clearify the role of NOD2 in the immunity balance and cellular homeostasis in the kidney parenchyma cells, by using cell biologic, gene knockout mice and other molecular biologic techniques. So，to relieve the inflammation and restore the autophagic function will be a new way to cure DN.

糖尿病肾病肾小管损伤发病机制的研究目前集中在炎症介导的免疫平衡，其中固有免疫应答的作用日益凸显。核苷酸结合寡聚化结构域2（NOD2）是位于胞浆内的模式识别受体，在多种自身免疫性疾病中发挥重要作用，但其在糖尿病肾病肾小管损伤中的作用机制尚不清楚。前期工作证实NOD2在糖尿病肾病患者及糖尿病小鼠的肾皮质中表达显著升高，且在浸润的炎症细胞中高表达；高糖刺激的肾小管上皮细胞中NOD2表达明显升高，且呈浓度依赖性；同时基因敲除小鼠实验表明NOD2基因缺失明显改善糖尿病肾病肾小管自噬功能，提示NOD2参与糖尿病肾病肾小管自噬损伤。本项目将以NOD2为中心，围绕肾小管上皮细胞自噬改变，采用细胞生物学、基因敲除小鼠等技术深入探讨NOD2-自噬在糖尿病肾病肾小管损伤中的分子生物学机制，阐明NOD2在肾脏实质细胞免疫平衡及细胞稳态中的重要作用，以期从减轻炎症反应、恢复自噬功能角度，找到糖尿病肾病治疗的新思路。

糖尿病肾病肾小管损伤发病机制的研究目前集中在炎症介导的免疫平衡，其中固有免疫应答的作用日益凸显。核苷酸结合寡聚化结构域2（NOD2）是位于胞浆内的模式识别受体，在多种自身免疫性疾病中发挥重要作用，但其在糖尿病肾病肾小管损伤中的作用机制尚不清楚。本项目实验结果发现NOD2在糖尿病肾病患者及糖尿病小鼠的肾皮质中表达显著升高，且在浸润的炎症细胞中高表达；高糖刺激的肾小管上皮细胞中NOD2表达明显升高，且呈浓度依赖性，但在TNF-α刺激下，NOD2的表达没有明显升高；同时基因敲除小鼠实验表明NOD2敲除能够减轻高脂饮食-STZ损伤糖尿病小鼠肾脏组织vimentin的表达及胶原蛋白的产生，证明NOD2参与了糖尿病肾病肾间质纤维化的进程，从另一角度阐明NOD2在肾脏实质细胞免疫平衡及细胞稳态中的重要作用。虽然棕榈酸联合BSA刺激可以明显升高肾小管上皮细胞自噬水平，且自噬抑制剂CQ能够抑制其诱导的自噬升高，但是由于在细胞实验中，高糖刺激、棕榈酸-BSA刺激以及高糖联合棕榈酸-BSA刺激后自噬相关蛋白的变化始终未得到确认，且棕榈酸-BSA刺激以及高糖联合棕榈酸-BSA刺激后NOD2的蛋白变化也未得到确认，NOD2与自噬的相互作用仍然没有阐明。在今后一年中本项目将继续将研究重点放在NOD2与自噬的相互作用关系上，以期能够阐明NOD2-自噬在糖尿病肾病肾小管损伤中的分子生物学机制。