SGLT1在糖尿病肾病小管及间质炎症损伤中的作用与机制研究

Diabetic Nephropathy (DN) is one of the leading causes of end-stage renal desease. As we known, renal tubulointerstitial inflammatory injury plays an important role in the development of DN. Recent studies have shown that the activation of NLRP3 inflammasome is a key link in DN development. SGLT1 is a sodium-glucose cotransporter which is located on the brush border of renal proximal tubule, however its role in DN tubular injury is still unclear. Our previous studies showed that SGLT1 expression of kidney was markedly increased in Akita mice, while both mRNA expression of IL-1β and IL-18, and protein expression NLRP3 and Caspase-1 were observed to decrease in renal tissues of SGLT1 knockout Akita mice, which prompting that SGLT1 involves in the activation of NLRP3 inflammasome in DN , however, the mechanism of this phenomenon is unclear. In this project, we will investigate the effects of SGLT1 on renal tubular epithelial cells injury and interstitial fibrosis and the mechanism of whether SGLT1 active NLRP3 inflammasome by mitophagy- ROS-TXNIP signal transduction pathways from both cultured cells and gene knockout mice model by using molecular biology techniques. The aim of this project is to prove SGLT1 induces NLRP3 inflammasome activation through mitophagy- ROS-TXNIP dependent pathways in tubular cell, and then mediates DN tubular injury. Hopefully we will shed new light in treating DN.

糖尿病肾病（DN）是引起ESRD的主要原因。肾小管间质慢性微炎症损伤在DN发病中起重要作用。最近研究证明NLRP3炎症小体激活是DN慢性微炎症发生的关键环节。SGLT1是位于肾近端小管上皮细胞的钠葡萄糖共转运体，但其在DN小管损伤中的作用与机制尚不清楚。我们前期研究发现Akita小鼠肾组织SGLT1表达增高，而肾小管SGLT1特异性敲除的Akita小鼠肾组织IL-1β和IL-18转录水平下降，NLRP3及Caspase-1蛋白表达亦降低。据此我们推测SGLT1促进DN肾组织炎症小体的激活，但其具体的调控机制尚不明确。本项目拟采用条件性基因敲除小鼠模型及细胞分子生物学技术，从不同层次研究SGLT1对DN小管上皮细胞凋亡及间质纤维化的影响，探讨其是否通过线粒体自噬-ROS-TXNIP信号通路激活NLRP3炎症小体，旨在阐明DN小管及间质损伤的分子机制，为早期DN的治疗提供新的理论依据。

糖尿病肾病（DN）是引起终末期肾脏疾病的主要原因，然而目前DN的治疗手段有限。肾小管间质慢性微炎症损伤在DN发病中起重要作用，且研究证明NLRP3炎症小体激活是DN慢性微炎症发生的关键环节。SGLT1是位于肾近端小管上皮细胞的钠葡萄糖共转运体，但其在DN小管损伤中的作用与机制尚不清楚。我们前期研究发现Akita糖尿病小鼠肾组织SGLT1表达增高，而肾小管SGLT1特异性敲除的Akita小鼠肾组织IL-1β和IL-18转录水平下降，NLRP3及Caspase-1蛋白表达亦降低。提示SGLT1可能参与了NLRP3炎症小体激活的调控。本研究采用条件性基因敲除小鼠模型及生信分析、基因组学、免疫组化、Western blot、RT-PCR、免疫荧光等实验方法，从临床、动物、细胞三个不同层次进一步探索了SGLT1对DN小管上皮细胞NLRP3炎症小体的调控机制及其介导糖尿病肾病小管损伤的原理。本研究通过基因组学和生信分析进一步证实了SGLT1在糖尿病小鼠肾组织中高表达，且发现了高糖状态下SGLT1可以使Rac1活化，SGLT1的表达水平对肾小管细胞线粒体ROS的生成、线粒体形态的改变以及NLRP3炎症小体的激活、肾小管细胞凋亡及间质纤维化影响显著。发现了SGLT1-Rac1-线粒体ROS途径对NLRP3炎症小体进行调控从而介导糖尿病肾病小管损伤。此外，我们的扩展实验进一步发现CXCL1-CLCR2轴亦参与了糖尿病肾小管的炎症损伤。我们相信本研究的继续深入有望为为早期DN的治疗提供新的理论依据和治疗靶点。