远端缺血后处理减轻大鼠肢体缺血再灌注后肺损伤中微小RNA-146a的表达变化

Expression of microRNA-146a in lower limb ischemia-reperfusion-induced lung injury following remote limb ischemic postconditioning in rats

目的 观察远端缺血后处理减轻大鼠肢体缺血再灌注后肺损伤中微小RNA（miRNA）-146a的表达变化,探讨远端缺血后处理的保护机制.方法 将24只雄性大鼠随机分为3组（每组8只）：假手术组（Sham）、远端缺血后处理组（RIPC）和肢体缺血再灌注组（LIR）.检测各组大鼠肺组织中miRNA-146a含量、Toll样受体4（TLR4）含量、丙二醛（MDA）含量、髓过氧化物酶（M PO）活性、湿干重比（W/D）比值及光镜下肺组织病理学改变.结果 与Sham组比较,LIR组和RIPC组大鼠肺组织中miRNA-146a的表达量明显降低（P＜0.05）,TLR4表达水平明显升高（P＜0.05）;与Sham组[（3.44±0.33） nmol/mg、（1.95±0.12） U/g、4.03 ±0.40]比较,LIR组和RIPC组MDA含量[（4.49±0.54）、（4.00 ±0.39） nmol/mg]、MPO活性[（2.55±0.31）、（2.26±0.32）U/g]及W/D比值（5.61±0.79、4.80 ±0.63）明显升高（P＜0.05）.与LIR组比较,RIPC组大鼠肺组织中miRNA-146a的表达量明显升高（P＜0.05）,TLR4、MDA、MPO水平及W/D比值明显降低（P＜0.05）.光镜下Sham组肺组织结构正常;RIPC组肺组织结构基本完整;LIR组肺组织损伤明显.结论 远端缺血后处理明显减轻肢体缺血再灌注后引起的肺损伤,其机制可能与miRNA-146a抑制TLR4蛋白表达和相关炎性介质的释放有关.

Objective To determine the expression of microRNA-146a （miRNA-146a） in lower limb ischemia-reperfusion-induced lung injury following remote limb ischemic postconditioning （RIPC） in rats,and understand the protective mechanism of RIPC.Methods Twenty-four male rats were randomly divided into three groups （n =8 in each group）：sham-operated group （Sham）,RIPC group and limbs ischemia-reperfusion （LIR） group.The miRNA-146a,Toll-like receptor 4 （TLR4）,malondialdehyde （MDA）,myeloperoxidase （MPO）,Wet/Dry （W/D） ratio and pulmonary pathological changes were observed in the lung tissues.Results Compared with the Sham group,miRNA-146a expression in rat lung tissue was significantly decreased （P 〈 0.05）,and TLR4 expression was significantly reduced in LIR and RIPC groups （P 〈 0.05）.Compared with the Sham group [（3.44 ± 0.33） nmol/mg,（1.95 ± 0.12） U/g,and 4.03 ±0.40],the MDA levels [（4.49 ±0.54） and （4.00 ±0.39） nmol/mg],MPO activity [（2.55 ± 0.31） and （2.26 ±0.32） U/g] and W/D ratio （5.61 ± 0.79 and 4.80 ± 0.63） in LIR and RIPC groups were significantly increased （P 〈 0.05）.Compared with the LIR group,the miRNA-146a expression was significantly increased （P 〈 0.05）,and TLR4,MDA and MPO levels and W/D ratio decreased significantly （P 〈0.05） in RIPC group.Microscopically,the lung tissue structure in Sham group was normal; In the RIPC group,lung tissue structure was almost intact; In the LIR group,the critical injury in lung tissue structure was observed.Conclusion The protective mechanism of remote limb ischemic postconditioning on lung injury induced by lower limb ischemia-reperfusion in rats may be correlated to the fact that miRNA-146a inhibits the TLR4 expression,as well as the release of inflammatory mediators.