IRAK-4活性在脂多糖预处理减轻肝脏缺血再灌注损害中作用的实验研究

目的:观察脂多糖(LPS)预处理后白细胞介素-1受体相关激酶-4（IRAK-4）表达水平在大鼠肝脏缺血再灌注(I/R)早期的变化，探讨LPS预处理减轻肝脏缺血再灌注损害(I/RI)的相关机制。 方法:雄性SD大鼠，随机分为正常对照组，缺血再灌注组(I/R组)和LPS预处理组（LPS组）。正常对照组未予任何处理；LPS组第 1 d 经尾静脉给予脂多糖0.1mg·kg-1，第2、3、4、5 d给予0.5 mg·kg-1；I/R组给予等体积0.5 mL无菌PBS液。第 8 d，建立肝脏缺血再灌注模型。再灌注后0 min、60 min及180 min, 蛋白免疫印记法及逆转录-聚合酶链式反应测定肝组织的IRAK-4蛋白和mRNA表达水平；酶连免疫吸附法检测肝组织NF-κB活性及血清TNF-α含量。 结果:再灌注0 min, IRAK-4蛋白与mRNA表达水平依次为LPS组>I/R组>正常对照组(P<0.01), NF-κB活性以及TNF-α含量LPS组与I/R组差异无显著(P>0.05)，但均高于正常对照组(P<0.01)；再灌注后60 min及180 min，LPS组的IRAK-4蛋白与mRNA表达水平，NF-κB活性以及TNF-α含量却明显低于I/R组（P<0.01）。 结论:抑制IRAK-4表达是LPS预处理减轻肝脏I/RI的重要机制之一。

Role of IRAK-4 activity in inhibitory effects of lipopolysaccharide pretreatment on hepatic ischemia/reperfusion injury

AIM:To observe the changes of interleukin-1 receptor associated kinase-4 (IRAK-4) in ischemia/reperfusion (I/R) liver pretreated with lipopolysaccharide (LPS) and to explore the protective mechanisms of LPS pretreatment against hepatic I/R injury. METHODS:Male Sprague-Dawley rats, weighing 240-280 g, were divided into three groups:control, ischemia/reperfusion group (I/R group) and LPS-pretreated group (LPS group). On the first day, LPS group received 0.1 mg/kg LPS via the tail vein, followed by 0.5 mg/kg on the 2nd, 3rd, 4th and 5th day. I/R group received the equivalent volumes (0.5 mL) of sterile PBS. Experiments of I/R injury was induced by temporary ischemia of the left lateral liver lobe for 90 min followed by 3 h reperfusion on 2 days after the last LPS treatment. At 0 min, 60 min and 180 min after reperfusion, the expression of IRAK-4 gene and protein level were determined by RT-PCR and Western blotting. The activity of NF-κB and the serum TNF-α level were also detected by ELISA. RESULTS:Although the level of IRAK-4 gene and protein were higher in the LPS group than that in I/R group and control group (P<0.01), no difference of the activities of NF-κB and the TNF-α level was observed between the LPS group and I/R group (P>0.05) at 0 min after reperfusion. However, all those indexes were evidently lower in the LPS group than those in I/R group (P<0.01) at 60 min and 180 min after reperfusion. CONCLUSION:This data suggests that the protective effects induced by LPS pretreatment against hepatic I/R injury may be via down-regulation of IRAK-4 expression.