miR-155上调自噬对脓毒症小鼠肺保护作用的实验研究

肺内巨噬细胞过度活化，失控性释放炎症介质，是脓毒症肺损伤的根本原因。本课题组前一研究表明，miR-146a可以抑制TLRs/NF-κB炎症通路，减轻肺损伤。最新研究发现自噬能抑制炎性体及其关键效应蛋白caspase-l的活化，减少IL-1β等炎症因子的释放，而自噬受TAB2的负性调控，值得关注的是，miR-155能靶向沉默TAB2蛋白的表达。我们推测在肺泡巨噬细胞内过表达miR-155，有可能成为抑制炎症介质释放的新途径。我们的前期工作已证实LPS刺激肺泡巨噬细胞后miR-155表达上调、细胞自噬增加。本项目拟体外转染miR-155入肺泡巨噬细胞，分析它对TAB2/自噬/炎性体及caspase-l和炎症介质的影响，并将专门用于肺内转染的in vivo-jetPEI介导的miR-155气管滴入脓毒症小鼠肺损伤模型中，探讨其对小鼠脓毒症肺损伤保护作用及其机制，为治疗脓毒症肺损伤提供新途径。

Treatment of lung injury induced by sepsis is limited by excessive activation of macrophage, resulting in uncontrolled release of inflammatory mediators. Our recent studies and those from others have shown: (1) miR-146a efficiently inhibits TLRs/NF-κB pathway and attenuates lung injury; (2) Inflammasome and caspase-1 activation are inhibited by autophagy, leading to decrease IL-1β release. Moreover, autophagy is negatively regulated by TAB2; (3) More importantly, up-regulation of miR-155 can down-regulate TAB2 expression. (4) Finally, we have strong evidence that activation of macrophages by LPS induced miR-155 overexpression and enhanced autophagy. Based on these findings, we hypothesize that overexpression of miR-155 in alveolar macrophages might provide new strategy to block release of inflammatory mediators during sepsis in lung. To this end, we will explore whether upregulation of miR-155 in alveolar macrophages by transfection effects TAB2 expression, autophagy, caspase-1 and inflammatory mediators in vitro. Furthermore, we will take advantage of mouse lung injury model induced by sepsis to examine whether miR-155 tracheal instillation by in vivo-jetPEI protect lung against sepsis induced injury, to investigate potential mechanisms. The success of such strategy will provide a novelty approach to treat sepsis induced lung injury.