miR-146a在大鼠缺血再灌注肝损伤中的表达及作用

目的:评价肝组织微小RNA-146a(miR-146a)表达变化与大鼠缺血再灌注(I/R)炎性肝损伤的关系。方法:72只SD大鼠随机分为非手术组(N组)、假手术组(S组)及I/R组,按分组处理后分别检测各组大鼠0、2、12和24 h(每组各时点n=6)血浆丙氨酸转氨酶(ALT)活性及白细胞介素6(IL-6)和肿瘤坏死因子α(TNF-α)含量,real-time PCR检测肝组织Toll样受体4(TLR4)、IL-6、TNF-α和miR-146a表达,Western blot分析肝组织中TLR4、IL-6和TNF-α表达。结果:N组大鼠各时点血浆ALT活性及IL-6和TNF-α含量与肝组织中TLR4、IL-6和TNF-α表达量无显著差异。S组大鼠血浆IL-6和TNF-α含量升高(P0.01),但血浆ALT活性与肝组织TLR4、IL-6和TNF-αm RNA及蛋白的表达量却无明显变化。I/R后,大鼠血浆ALT活性及IL-6和TNF-α含量明显升高(P0.01),肝组织TLR4、IL-6和TNF-αm RNA及蛋白的表达量亦显著升高(P0.01),且随着时间延长,各指标仍持续升高;肝组织miR-146a表达量显著下降,其中在缺血12 h时下降最为明显,到24 h表达量再次升高,但始终低于I/R前(P0.01)。N组及S组大鼠各时点肝组织miR-146a表达量显著高于I/R组I/R后相应时点的表达(P0.01)。结论:I/R大鼠肝组织miR-146a表达下降的同时存在TLR4信号通路的激活及炎性肝损伤的发生。

Expression and effect of miR-146a in ischemia-reperfusion liver injury in rats

AIM:To evaluate the relationship between microRNA-146a (miR-146a) expression in liver tissues and hepatic ischemia-reperfusion (I/R) inflammatory injury in rats. METHODS:The SD rats (n=72) were randomly divided into non-operative group (N group), sham-operated group (S group) and I/R group. The plasma levels of alanine aminotransferase (ALT), interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) were tested at 0 h, 12 h and 24 h in each group (n=6). The mRNA expression of Toll-like receptor 4 (TLR4), IL-6 and TNF-α, and the expression level of miR-146a in the liver tissue were detected by real-time PCR, and the protein expression levels of TLR4, IL-6 and TNF-α were determined by Western blot. RESULTS:No significant difference was observed in the levels of ALT, IL-6 and TNF-α in the plasma and the expression of TLR4, IL-6 and TNF-α at mRNA and protein levels in the liver tissues of the rats at each time point in N group. The plasma concentrations of IL-6 and TNF-α were increased (P<0.01) in S group, and no significant change in the plasma ALT level and the expression of TLR4, IL-6 and TNF-α at mRNA and protein levels in the liver tissues was observed. I/R significantly increased the plasma levels of ALT, IL-6 and TNF-α and the expression of TLR4, IL-6 and TNF-α at mRNA and protein levels in the rat liver tissues (P<0.01), and the parameters continued to increase with time. The expression of miR-146a was significantly decreased in the liver tissue after ischemia with the peak time at 12 h, and although the expression level increased to 24 h, it was always lower than that before I/R (P<0.01). The expression of miR-146a in the liver tissues at each time point in N group and S group was significantly higher than that in I/R group at corresponding time points after I/R (P<0.01). CONCLUSION:Decreased expression of miR-146a in the rat liver tissue induced by I/R may coexist with the activation of TLR4 signaling pathway and the occurrence of inflammatory liver injury.