受miRNAs调控的Smad3基因通过调节自噬减轻脓毒症肺损伤的作用研究

Sepsis is a common clinical critical disease and a leading death cause. Our previous study has showed that the post-sepsis lung injury of the Smad3-/-mice aggravated，leading to higher fatality rate. Compared to wild type mice, Smad3-/- mice have worse apoptosis and lower autophage in lung epithelia cell following spesis. On the other hand，compared to Smad3-/-mice，we found out that wild type mice have higher expression of Smad3 and lower expression of miRNAs targeting Smad3. Based upon the pre-study and previous studies, we have reasons to bring forth this hypothesis: sepsis causes lower expression of miRNAs regulating Smad3 in the lung, giving rise to higher expression of Smad3, which to some extent lowers sepsis-derived apoptosis by regulating its autophage after expression and activation. The protective role played by Smad3 in sepsis alleviates its damage, which could have caused death from aggravated lung injury following sepsis if there is none or low expression of Smad3. this project is to prove Smad3' role in sepsis on Smad3-/- mice,cells and plenty of clinical samples, in hope to provide new perspective for sepsis treatment.

脓毒症（sepsis）是临床常见的危重症和重要死因。我们前期研究证实脓毒症后Smad3-/-鼠与野生型小鼠相比，肺损伤加重、死亡率增高；在肺上皮细胞凋亡加重的同时，发现细胞自噬表达降低。我们进一步发现：脓毒症后，野生型鼠的Smad3表达升高，而靶向Smad3的多数miRNAs表达水平下调。基于前期研究和预实验结果，我们有理由提出这样一个假说：脓毒症时肺部调控Smad3基因的某些miRNAs表达水平降低，使Smad3基因表达水平升高，Smad3表达、活化后，调节自噬在一定程度上降低了脓毒症导致的细胞调亡，从而起到机体自身缓解脓毒症损伤的作用。一旦这种自身调控机制被破坏，如在Smad3表达缺失或受miRNAs调控而减少的情况下，脓毒症后肺损伤加重进而导致死亡。本项目主要利用Smad3-/-鼠、细胞和临床样本验证受miRNAs调控的Smad3基因的此类作用，以期为脓毒症的防治提供新思路。

我们前期实验研究证实脓毒症后Smad3-/-鼠与野生型小鼠相比，肺损伤加重，死亡率增高；在肺上皮细胞凋亡加重的同时发现自噬降低。我们进一步发现：脓毒症后，野生型鼠的Smad3表达升高，而靶向Smad3的多数miRNA表达下调。因此我们认为：脓毒症时肺部调控Smad3基因的某些miRNA(以microRNA126-3p为代表)表达变化，使Smad3基因表达升高，Smad3表达与活化后通过调节自噬而在一定程度上降低脓毒症引起的调亡的水平，从而起到机体自身缓解脓毒症引起损伤的作用，而这种作用被破坏，如在Smad3表达缺失或受miRNA调节而减少的情况下，脓毒症后肺损伤加重导致死亡。本项目主要利用Smad3-/-动物、慢病毒建立稳转干扰Smad3正常肺上皮细胞系，来确定脓毒症时调控Smad3表达的miRNA，并用细胞、动物以及丰富的临床样本来验证调控Smad3基因的miRNA的作用，为脓毒症的防治提供新靶点和理论依据。