BMSCs来源的外泌体SIRT1蛋白调控肺泡巨噬细胞HMGB1异常释放减轻体外循环术后急性肺损伤的机制研究

Acute lung injury (ALI) is a serious complication after cardiopulmonary bypass (CPB). Previous work confirmed that the release of HMGB1 from alveolar macrophages is a key factor leading to ALI. Studies have shown that SIRT1 as a deacetylase reverses HMGB1 acetylation and reduces HMGB1 release in ischemia-reperfusion injury. Pre-experiments found that bone marrow mesenchymal stem cell-derived exosomes (BMSCs-Exos) contained SIRT1 protein. Injection of BMSCs-Exos reduced ALI after CPB, and BMSCs-Exos co-culture reduced HMGB1 release from alveolar macrophages induced by oxygen-glucose deprivation. Based on this, we hypothesized that BMSCs-Exos can transmit the SIRT1 protein to alveolar macrophages, reverse acetylation of HMGB1, and reduce ALI after CPB. This study intends to use the rat CPB model and macrophage oxygen deprivation model, using lentivirus to interfere with the expression of SIRT1 in exosomes and constructing over-expressing SIRT1 plasmid to explore the mechanism of BMSCs-Exos to alleviate ALI after CPB. This research provides a new perspective and direction for clinical treatment of ALI/ARDS.

急性肺损伤（ALI）是体外循环（CPB）术后严重并发症，申请者证实肺泡巨噬细胞释放HMGB1是导致CPB术后ALI的关键因子。研究表明SIRT1作为去乙酰化酶可逆转缺血再灌注损伤(IRI)中HMGB1乙酰化，减少HMGB1释放。申请者发现，骨髓间充质干细胞来源的外泌体（BMSCs-Exos）含有SIRT1蛋白，注射BMSCs-Exos可减轻CPB术后ALI，且BMSCs-Exos共培养可减少氧糖剥夺(OGD)引起巨噬细胞HMGB1释放。申请者推测：BMSCs-Exos可将携带的SIRT1蛋白传输到肺泡巨噬细胞，逆转肺IRI导致HMGB1乙酰化，减轻CPB术后ALI。本课题采用大鼠CPB模型及巨噬细胞OGD模型，利用慢病毒干扰外泌体中SIRT1表达以及构建过表达SIRT1质粒等手段，探索BMSCs-Exos减轻CPB术后ALI的机制。本研究也为临床上治疗ALI/ARDS提供新的观点和方向。

急性肺损伤（ALI）是体外循环（CPB）或脓毒症（Sepsis）严重并发症，但机制不明，尚无有效治疗手段，是临床麻醉及重症医学科亟需解决的难题。本课题围绕着重探讨采用何种有效减轻ALI的治疗措施。首先我们发现，间充质干细胞来源的外泌体可以通过调控Nrf2减轻肺泡上皮细胞凋亡最终减轻Sepsis相关ALI。其次，我们发现抗氧化mitoQ通过调节Nrf2/Drp1信号通路阻断肺泡上皮细胞线粒体过度分裂减轻Sepsis相关ALI。最后，我们发现CPB病人术后24小时血浆外泌体中炎性蛋白HMGB1通过mtDNA/Sting信号通路介导肺泡上皮细胞坏死性凋亡加速ALI。综上可见，我们通过本课题紧紧围绕着ALI治疗理念，探讨出间充质干细胞外泌体治疗作用及机制，并说明外泌体HMGB1是导致CPB术后ALI的重要炎性蛋白，为临床上治疗ALI提高新的理论依据。