NLRP3炎症小体介导的炎症反应参与糖尿病导致的肾损伤和脂代谢异常

Inflammatory response mediated by NLRP3 is involved in renal injury and abnormal lipid metabolism caused by diabetes mellitus

目的:观察NLRP3在糖尿病肾组织炎症及胆固醇代谢中的作用及机制。方法:实验小鼠分为4组:对照(WT)组、糖尿病(WT+STZ)组、NLRP3基因敲除(NKO)组和NLRP3基因敲除+糖尿病(NKO+STZ)组。腹腔注射STZ构建糖尿病小鼠模型。观察小鼠血尿生化指标及肾组织形态学;电镜及油红O染色观察肾组织脂滴形成情况;Western blot方法检测NLRP3、ASC、caspase-1、IL-1β、IL-18及胆固醇代谢指标SCAP、SREBP-2、HMGCR、LDLR、LXRα和ABCA1的蛋白表达情况及p38 MAPK的磷酸化情况。结果:与WT组小鼠相比,糖尿病小鼠肾组织的NLRP3表达和p38 MAPK的磷酸化水平显著升高;肾组织内炎症明显,胆固醇含量增加伴肾功能受损;敲除NLRP3显著减轻糖尿病小鼠肾组织炎症反应及胆固醇沉积,同时抑制p38 MAPK的磷酸化。结论:NLRP3介导的炎症反应在糖尿病肾损伤及脂代谢异常中发挥重要作用,这种作用可能与p38 MAPK信号通路的活化密切相关。

AIM:To observe the role of NLRP3 in inflammation and cholesterol metabolism in mice with diabetic nephropathy.METHODS:The experimental animals were randomly divided into 4 groups:wild-type C57 BL/6 mice(WT)group,diabetes(WT+STZ)group,NLRP3 knockout mice(NKO)group and diabetic NLRP3 knockout mice(NKO+STZ)group.Diabetes mellitus was induced by intraperitoneal injection of STZ daily for 5 d.At the 8 th week of the experiments,the mice were sacrificed and the samples of blood and 24 h urine were collected for determining the renal function,blood glucose and blood lipids.Transmission electron microscopy and oil red O staining were used to observe the formation of lipid droplets.The protein levels of NLRP3,ASC,caspase-1,IL-1β,IL-18,SCAP,SREBP-2,LDLR,HMGCR,LXRα,ABCA1 and phosphorylated p38 MAPK were detected by Western blot.RESULTS:Compared with the WT mice,the expression of NLRP3 and the phosphorylation of p38 MAPK were significantly increased in the diabetic mice(P<0.01).Inflammmation and the content of cholesterol in the renal tissues of diabetic mice were significantly higher than those in the WT mice.Meanwhile,increased p38 MAPK phosphorylation,inflammation and cholesterol deposition were effectively suppressed by NLRP3 knockout.CONCLUSION:NLRP3 is involved in renal injury and abnormal lipid metabolism in diabetic mice,which may be related to the activation of p38 MAPK signaling pathway.