钠钾ATP酶配体转录后精密调控TH1细胞因子mRNA稳定性的分子机制及其在脓毒症中的应用价值

项目名称： 钠钾ATP酶配体转录后精密调控TH1细胞因子mRNA稳定性的分子机制及其在脓毒症中的应用价值

项目编号： No.81473293

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 医药、卫生

项目作者： 殷武

作者单位： 南京大学

项目金额： 50万元

中文摘要： 获得性免疫抑制，或免疫麻痹是脓毒症高死亡率的重要病理机制，但临床治疗手段匮乏。通过药物筛选，我们发现钠钾ATP酶配体如哇巴因能有效逆转脓毒症免疫麻痹，且该作用与哇巴因诱导HuR出核，增强TH1细胞因子，尤其是TNFαmRNA稳定性相关。意外的是，哇巴因也能刺激miR181s表达降解TNFαmRNA，且该作用与内毒素颇为相似。为解释该矛盾结果，我们发现miR181s在TNFαmRNA 3′-UTR上的结合位点恰好位于HuR结合位点内部，由此推测哇巴因或内毒素诱导的miR181s表达属于机体反馈性保护机制，旨在抑制TNFα过度积累导致的炎性损伤，但也会因为抑制TNFα表达加剧免疫麻痹。为规避miR181s潜在免疫抑制作用，在哇巴因作用下，HuR能与miR181s竞争结合TNFαmRNA，或形成压力颗粒将TNFαmRNA包裹在内，躲避miR181s的降解，最终稳定TNFαmRNA，逆转免疫麻痹。

中文关键词： 脓毒症免疫麻痹；肿瘤坏死因子；转录后调控；钠钾ATP酶配体；分子药理学

英文摘要： The acquired immunosuppression, or immunoparalysis is an important pathological mechanism for the high mortality of sepsis; however, effective therapies for immunoparalysis are not clinically available. By drug screening, we found that Na+,K+-ATPase ligand, such as ouabain can effectively reverse immunoparalysis, and further, this effect was related to the increased TH1 cytokines mRNA stability by ouabain-induced HuR nuclear export, especially for TNF α. Unexpectedly, ouabain also increased miR181s expression to destabilize TNFα mRNA, and this effect was similar as that of LPS. To explain the contradictory result, we found the binding site of miR181s on the 3'-UTR of TNFα mRNA locates exactly within HuR binding sites. Therefore, we presume in this study that the induction of miR181s by ouabain belongs to feedback protective mechanism, the purpose of which is to suppress the overproduction of TNFα and the resultant inflammatory injury. However, miR181s-mediated TNFα mRNA degradation also leads to the enhancement of immunoparalysis. To circumvent the potential immunosuppressive effect of miR181s, ouabain treatment-induced HuR export can compete with miR181s on the shared target of TNFα mRNAs, or recruit TNFα mRNAs to stress granules in case of being degraded by miR181s, thereby leading to stabilization of TNFα mRNA and the reversal of immunoparalysis.

英文关键词： immunoparalysis of sepsis;tumor necrosis factor;posttransriptional regulation;Na+;K+-ATPase ligand;molecular pharmacology