丁酸调控中性粒细胞胞外诱捕网（NETs）形成在糖尿病肾病发病中的作用和机制研究

Diabetic nephropathy is one of the most serious complications of diabetes， and it is also one of the main causes of death in diabetes, but its mechanism is still unclear. We found that neutrophil extracellular traps (NETs) was increased in the blood of DN patients, which was negatively correlated with the estimated glomerular filtration rate. In DN mice, the intestinal bacteria producing butyric acid was decreased, at the same time, sodium butyrate (NaB) supplementation can significantly ameliorate the degree of renal damage and reduce NETs in peripheral blood. In vitro, we detected that NaB can reduce the expression and secretion of inflammatory cytokines, MCP-1 and IL-6 in renal mesangial cells. So, we assume that NETs are involved in the occurrence and development of DN, and NaB can ameliorate renal inflammatory of DN via inhibiting the formation of NETs. Based on our previous work, we intend to do the following studies at population-individual-cell levels: (1) the role and mechanism of NETs in renal inflammation of DN; (2) how butyric acid, a metabolite of enterobacteria, regulates NETs formation, and its effect on DN. These studies will reveal a new mechanism of renal inflammation and provide a new theory for early prediction and treatment of DN.

糖尿病肾病是糖尿病最严重的并发症和主要死亡原因之一，但是其机制尚不明确。我们发现糖尿病肾病病人的血液中中性粒细胞胞外诱捕网（NETs）含量增加，与患者肾小球滤过率的估计值呈负相关；糖尿病肾病小鼠肠道中产生丁酸的细菌减少；丁酸钠处理能显著改善糖尿病肾病小鼠肾脏的病变程度，同时降低血液中的NETs含量；细胞实验表明，丁酸钠处理能降低肾系膜细胞中炎症因子MCP-1和IL-6的表达和分泌。我们假设NETs在糖尿病肾病的发生发展过程中起作用，而丁酸钠通过抑制NETs形成改善糖尿病肾病。基于前期工作，本项目拟从人群、个体和细胞水平研究：（1）NETs介导糖尿病肾病肾脏炎症的发生发展的作用与机制；（2）肠道菌群代谢产物丁酸如何调节NETs形成，及其对糖尿病肾病的影响。这些研究将揭示肾脏炎症的新机制，为早期预测和治疗糖尿病肾病提供新的理论。

糖尿病肾病是糖尿病最严重的并发症和主要死亡原因之一，炎症是糖尿病肾病发生发展的中心环节，但是炎症介导肾脏损伤的具体机制尚不明确。中性粒细胞是炎症的主要效应细胞，中性粒细胞胞外诱捕网（NETs）是中性粒细胞死亡的一种新形式，NETs已在糖尿病及炎症性疾病中发现，NETs在糖尿病肾病发病中的作用及机制尚不明确。项目前期研究发现肠道菌群代谢产物丁酸可通过改善糖尿病小鼠肠上皮屏障的完整性，减轻内毒素血症、炎症和氧化应激损伤；但是，siRNA敲低短链脂肪酸特异性受体GPR41或GPR43表达不能阻断丁酸钠的抗炎效果，这表明丁酸可能通过其他途径抑制糖尿病肾脏炎症。本项目从人群、个体和细胞水平进行研究，发现NETs在DN患者和小鼠模型中显著增加，并且其生成损害肾小球血管内皮。有趣的是，AGEs可以通过增加NETs的形成来促进ROS的产生，而p38MAPK信号的激活在NETs的形成中起着重要作用。此外，DN小鼠产生丁酸的细菌减少，补充丁酸钠可以改善肠道屏障，逆转AGEs介导的NETs增加，减轻炎症，对DN有治疗作用。我们的研究结果表明，NETs是AGEs介导DN肾损伤的重要中间环节，丁酸钠可通过抑制NETosis改善DN炎症。