脂氧素A4抑制TLR4/MyD88/NF-κB通路减缓脓毒症性急性肾损伤

LipoxinA4 protects sepsis-induced acute kidney injury via the TLR4/MyD88/NF-κB pathway

目的探讨脂氧素A4(LXA4)通过抑制TLR4/MyD88/NF-κB通路减缓脓毒症性急性肾损伤(SAKI)。方法将40只无特定病原体级雄性C57BL/6J小鼠随机分为SAKI组、SAKI+LXA4组、假手术组、假手术+LXA4组,每组10只。采用盲肠结扎穿孔术进行SAKI造模,SAKI+LXA4组、假手术+LXA4组在术后30 min腹腔注射LXA4(40 ng/kg)。各组小鼠在造模术后24 h收集血清、尿液、肾组织。酶联免疫吸附试验(ELISA)测定各组小鼠血肌酐(Scr)、血尿素氮(Bun)、白细胞介素-1β(IL-1β)、IL-6、肿瘤坏死因子-α(TNF-α),尿液中性粒细胞明胶酶相关性脂质运载蛋白(NGAL)及肾损伤分子1(KIM-1);HE及PAS染色观察小鼠肾脏损伤情况;实时荧光定量PCR检测各组小鼠肾脏Toll样受体4(TLR4)、髓样分化因子88(MyD88)、核因子-κB p65(NF-κB p65)mRNA水平;免疫组化法、蛋白免疫印迹实验检测各组小鼠TLR4、MyD88、NF-κB p65、磷酸化NF-κB p65(p-NF-κB p65)的表达。结果ELISA实验提示SAKI组Scr、Bun、IL-1β、IL-6、TNF-α、NGAL、KIM-1水平均高于SAKI+LXA4组(P<0.05),假手术组及假手术+LXA4组Scr、Bun、IL-1β、IL-6、TNF-α、NGAL、KIM-1无明显上升;HE及PAS染色提示SAKI组肾损伤程度明显高于SAKI+LXA4组(P<0.05),假手术组及假手术+LXA4组无明显肾损伤;实时荧光定量PCR提示SAKI组较SAKI+LXA4组TLR4、MyD88、NF-κB p65 mRNA升高(P<0.05),假手术组与假手术+LXA4组TLR4、MyD88、NF-κB p65 mRNA均低于SAKI组及SAKI+LXA4组(P<0.05);免疫组化法、蛋白免疫印迹实验结果提示SAKI组较SAKI+LXA4组TLR4、MyD88、NF-κB p65、p-NF-κB p65表达升高(P<0.05),假手术组与假手术+LXA4组TLR4、MyD88、NF-κB p65、p-NF-κB p65表达均低于SAKI组及SAKI+LXA4组(P<0.05)。结论TLR4/MyD88/NF-κB通路在SAKI发生发展中起重要作用,LXA4可能通过抑制TLR4/MyD88/NF-κB信号通路减缓SAKI。

Objective To study the protective effect of lipoxin A4(LXA4)against sepsis-induced acute kidney injury(SAKI)in rats and its effect on the expression of toll-like receptor 4(TLR4),myeloid differentiation factor88(MyD88),nuclear factor kappa B(NF-κB)in the kidney.Methods Forty male specific pathogen-free C57BL/6J mice were randomly divided into SAKI group,SAKI+LXA4 group,sham procedure group,sham procedure+LXA4 group.The mice in SAKI group and SAKI+LXA4 group were given cecum ligation and puncture(CLP)to establish SAKI animal models.The mice in SAKI+LXA4 group and sham procedure+LXA4 group were given LXA4(40 ng/kg)with intraperitoneal injection 30 mins after CLP.All mice were sacrificed at the 24th hour after CLP to collect serum,urine and kidney tissues.The enzyme linked immunosorbent assay(ELISA)was used to test the serum creatinine(Scr),blood urea nitrogen(Bun),interleukin-1β(IL-1β),IL-6,tumor necrosis factor-α(TNF-α)and urine neutrophil gelatinase-associated lipocalin(NGAL),kidney injury molecule 1(KIM-1)levels of mice.The pathological changes were examined through hematoxylin-eosin(HE)staining and Periodic Acid-Schiff(PAS)staining.And the mRNA levels of TLR4,MyD88,NF-κB p65 were detected through real-time PCR(RT-PCR);the expression levels of TLR4,MyD88,NF-κB p65,phospho-NF-κB p65(p-NF-κB p65)were detected through immunohistochemistry(IHC)and Western blot assay.Results ELISA showed that the values of Scr,Bun,IL-1β,IL-6,TNF-α,NGAL,KIM-1 in SAKI group were higher than those in SAKI+LXA4 group(P<0.05),and there were no significant differences in Scr,Bun,IL-1β,IL-6,TNF-α,NGAL,KIM-1 between sham procedure group and sham procedure+LXA4 group.HE and PAS staining showed that SAKI group had severer pathological changes than SAKI+LXA4 group in the kidney structure(P<0.05),while pathological structures of the kidney were normal in sham procedure group and sham procedure+LXA4 group.RT-PCR showed that the mRNA levels of TLR4,MyD88,N F-κB p65 in SAKI group,SAKI+LXA4 group were higher than sham procedure group and sham procedure+LXA4 group(P<0.05);the mRNA levels of TLR4,MyD88,NF-κB p65 in SAKI group were higher than SAKI+LXA4 group(P<0.05);The results of IHC,Western blot assay were as follows:The expression levels of TLR4,MyD88,NF-κB p65,p-NF-κB p65 in SAKI group,SAKI+LXA4 group were higher than sham procedure group and sham procedure+LXA4 group(P<0.05);the expression levels of TLR4,MyD88,NF-κB p65,p-NF-κB p65 in SAKI group were higher than SAKI+LXA4 group(P<0.05).Conclusion TLR4/MyD88/NF-κB pathway plays an important role in the occurrence and development of SAKI,and LXA4 may reduce SAKI by inhibiting TLR4/MyD88/NF-κB signaling pathway.