Sirtuin家族成员在脓毒症急性期与抑制期的不同效应与机制研究

The overactivation of TLR (hyper-inflammatory) during the acute phase and the failure of TLR activation (hypo-inflammatory) upon secondary infections, also called endotoxin tolerance, are both of great importance for the pathology of sepsis.Sirt1/2 was found to negatively regulate inflammation by deacetylating target proteins during aging or inflammation. We found that there was linear relationship between the dynamic production of NAD+ production and inflammatory cytokines and dynamic expression variation of Sirt family members during inflammation. Functional Screening revealed Sirt3/5 positively regulated TLR-induced responses, which was opposite to Sirt1/2. We plan to further investigate the dynamic expression Sirt family members and activation status of innate immune by applying the established Sirt3/5 knockout mice and Sirt1/2 agonist or antagonist, to explore the function and molecular mechanism of Sirt3/5 in both acute and suppressive phases of sepsis by in vivo and in vitro model of sepsis and signal transduction screening. Our proposal will not only provide novel cues and mechanism to discriminate the sepsis stage, but also novel drug target for precise medicine to treat sepsis.

脓毒症的典型特征是在急性期的炎症过度活化、造成器官损伤；而在抑制期则是炎症反应过弱（免疫崩溃）、对二次感染敏感，TLR信号介导的炎症反应往往占据主要地位。研究发现，在衰老与慢性炎症环境中，Sirt1/2通过去乙酰化靶蛋白而负向调节炎症反应。课题组前期通过筛选发现，NAD+的产量与炎症因子直接负向相关，Sirt家族成员表达水平随着炎症时间发生动态改变，功能筛选发现Sirt3/5具有促进炎症反应的作用。提示Sirt3/5在脓毒症的作用与Sirt1/2不同。课题组拟应用已引进和培育成功Sirt3/5缺陷小鼠模型、以及Sirt1/2抑制剂或活化剂，探索发现Sirt家族成员在脓毒症中表达规律和免疫功能相关性，探索发现Sirt3/5在脓毒症急性期和抑制期中的体内和体外效应；并通过信号通路筛选探索发现Sirt3/5的作用机制。为脓毒症研究的免疫功能分期分级提供线索，也为脓毒症精准治疗提供药物筛选靶点。

脓毒症的典型特征是机体应对细菌、病毒等病原体感染情况下，在急性期的炎症过度活化、造成器官损伤；而在抑制期则是炎症反应过弱（免疫崩溃）、对二次感染敏感，TLR和RIG-I信号介导的炎症反应往往占据主要地位。a.按照研究计划，本项目发现了NAD产量和IL-6的负相关，Sirt5可以通过竞争性结合p65，阻止Sirt2对p65去乙酰化，并促进LPS诱导NF-κB活化，促进LPS诱导的脓毒症；b.通过筛选技术完成了SIRT5通过DDX3促进抗病毒功能，发表论文（Theranostics 2021）；c.发现了SIRT3通过抑制糖酵解促进抗病毒功能（正在投稿）。本项目分别发现了Sirt3/5在抗细菌和抗病毒天然免疫反应中的作用和机制，为细菌病毒等病原体感染引起的急性炎症反应或脓毒症机制研究提供了新的机制，也为临床干预病毒性和细菌性脓毒症提供了新思路，超额完成了研究目标。