IL-17A基因敲除减轻脂多糖诱导的脂肪肝小鼠肝脏炎症性损伤及其机制

IL-17A knockout alleviates lipopolysaccharide-induced steatotic liver injury in mice

目的在长程高脂膳食诱导的脂肪肝小鼠中,探讨白介素17A(interleukin 17A,IL-17A)基因缺陷对脂多糖(lipopolysaccharide,LPS)诱导的急性肝损伤的作用及其可能的机制。方法利用IL-17A基因敲除小鼠构建脂肪肝急性损伤模型,通过检测血浆中谷丙转氨酶(alanine transaminase,ALT)和谷草转氨酶(aspartate transaminase,AST)评估肝脏损伤情况,通过检测血浆中3种主要炎症因子TNF-α、IL-1β以及IL-6评估机体炎症水平,通过肝脏病理形态观测肝脏组织炎症细胞浸润和肝细胞损伤情况。通过对肝脏组织表达mRNA进行转录组学分析,寻找IL-17A基因敲除在高脂膳食(high fat diet,HF)+LPS诱导的肝损伤中的发挥作用的相关分子信号机制。结果在高脂膳食喂养辅之以一次性LPS刺激下,IL-17A基因敲除(gene knockout,KO)小鼠血浆中的ALT及AST水平显著降低(P<0.05);KO小鼠血浆中炎症因子水平显著降低(P<0.05),肝脏组织中浸润的炎症细胞显著减少(P<0.05)。肝脏转录组学分析结果显示,刺激后,KO小鼠下调的938个基因主要富集于氧化应激(P<0.01)、过氧化氢代谢途径(P<0.01)以及谷胱甘肽代谢途径(P<0.01)。Real-time PCR检测发现KO小鼠肝脏中与过氧化氢代谢相关的CAT、GPX1、IDH1、IDH2以及ME1基因的mRNA水平显著升高。同时,肝脏的氧化应激水平显著降低(P<0.05)。TUNEL检测进一步检测结果显示,KO小鼠肝脏凋亡细胞数量显著减少(P<0.01)。结论 IL-17A基因敲除可能通过促进过氧化氢代谢减轻LPS诱导的脂肪肝小鼠急性炎症性肝损伤。

Objective To investigate the effect of interleukin 17A （IL-17A）deficiency on lipopolysaccharide（LPS）-induced liver injury in mice with long-term high fat diet feeding and explore the underlying mechanism. Methods C57BL/6 mice with IL-17A gene knockout （KO） and the wild-type （WT） littermates fed with high fat diet for 3 months were given an intraperitoneal injection of 4 mg/kg lipopolysaccharide （LPS）. Plasma levels of alanine transaminase（ALT） and aspartate transaminase （AST） were detected to assess liver injury. Plasma TNF-α, IL-1β and IL-6 levels were determined to assess the severity of inflammation. Inflammatory cell infiltration in the liver and the impairment of hepatic cells were observed. The liver tissues from the WT and KO mice were subjected to transcriptomic analysis to study the effect of IL-17A deficiency on high-fat-diet-and LPS-induced liver injuries. Results High fat diet feeding and LPS challenge significantly decreased the plasma ALT and AST levels in IL-17A KO mice （P 〈 0.05）. In the KO mice, the plasma levels of inflammatory cytokines and the number of infiltrating inflammatory cells in the liver were reduced significantly（P 〈 0.05）. Transcriptomic analysis showed that 938 genes were down-regulated in the KO mice after LPS stimulation, among which the genes involved in oxidation reduction process（P 〈 0.01）, hydrogen peroxide metabolic process （P 〈 0.01）, and glutathione metabolic process （P 〈 0.01） showed the most significant decreases. Real-time PCR demonstrated that a panel of metabolic enzymes participated in hydrogen peroxide detoxification, such as CAT, GPX1, IDH1, IDH2 and ME1, which were highly expressed in the KO mice （P 〈 0.05）. The levels of reactive oxygen species （ROS） were significantly decreased in the liver of KO mice （P 〈 0.05）. TUNEL assay indicated that the number of apoptotic cells was significantly reduced in the liver of KO mice（P 〈 0.05）. Conclusion IL-17A deficiency may alleviate LPS-induced acute inflammatory injury in fatty liver mice by reducing hepatic ROS accumulation.