STING信号促进巨噬细胞促炎性免疫应答参与老龄肝脏缺血再灌注损伤的机制研究

Liver ischemia and reperfusion injury (IRI) is a complex pathophysiological process resulting in significantly impaired postoperative recovery. The old liver suffers more serious liver IRI and the pro-inflammatory immune response mediated by macrophage plays a key role in its pathogenesis. Our group found that reduced autophagy activation but enhanced STING activation and pro-inflammatory response in macrophages after liver IRI in old mice. Autophagy-dependent STING degradation is an important mechanism to avoid over-activation of macrophages. Thus, we hypothesize that STING signal-mediated macrophage over-activation may play a key role in aggravating IRI in old livers. On the one hand, aging aggravates hepatocyte damage and increases mitochondrial DNA release after IRI, leading to enhanced cGAS-STING activation in macrophages; on the other hand, aging inhibits macrophage autophagy activation and impairs autophagy-dependent STING degradation. These two signals ultimately promote the macrophage pro-inflammatory response and exacerbates the IRI in old livers. Using IRI and in vitro macrophage activation model with the STINGgt old mice, we plan to explore the underlying mechanism of STING over-activation in old macrophages, analyze the regulatory roles of autophagy and potential signals such as AMPK, ULK1, p62 and ATG16L1, and their effects on the IRI of old livers. The study will provide new target for clinical intervention.

肝脏缺血再灌注损伤（IRI）直接影响手术预后，发生机制复杂。老龄肝脏IRI更为严重，巨噬细胞（Mɸ）炎性应答在其中起了重要作用。本课题组发现，老龄肝脏IRI后肝内Mɸ自噬被抑制，STING活化和促炎性反应增强。自噬依赖的STING降解是避免Mɸ过度活化的重要机制，由此推断，STING信号介导的Mɸ过度活化在加重老龄肝脏IRI中发挥了关键作用。一方面，老龄小鼠IRI后肝细胞受损加重，线粒体DNA释放增加，增强了Mɸ内cGAS-STING信号；另一方面，老龄抑制了Mɸ自噬，使自噬依赖的STING降解减少。两者最终都增强了Mɸ炎性反应，加重了老龄肝脏IRI。本课题计划利用STINGgt老龄小鼠，建立IRI和体外Mɸ活化模型，探索老龄Mɸ内STING过度活化的机制，分析自噬及AMPK、ULK1、p62、ATG16L1等潜在信号在其中的调控作用，及其对老龄肝脏IRI的影响，为临床干预提供新的思路。

背景：肝脏缺血再灌注损伤（IRI）直接影响手术预后，发生机制复杂。老龄肝脏IRI更为严重，巨噬细胞（Mɸ）炎性应答在其中起了重要作用。巨噬细胞cGAS-STING信号通路是近年新发现的模式识别受体通路，在肝脏炎症性疾病中发挥着重要作用。.主要研究内容：本项目深入研究了老龄巨噬细胞自噬调控STING信号介导免疫应答调控老龄肝脏IRI的具体机制。通过体内外实验，分析老龄加重肝脏IRI的机制和巨噬细胞STING信号在其中起到的促炎作用，研究老龄对自噬的影响及调控STING信号的具体信号机制，并探寻靶向治疗的关键中间分子。.重要成果：1）老龄加重IR后巨噬细胞STING信号激活，并进一步激活NLRP3炎症小体，加重肝脏炎症损伤，Mɸ-STING敲除可减轻老龄肝脏IRI损伤；2）老龄抑制了Mɸ线粒体自噬，线粒体DNA释放增加，增强Mɸ内cGAS-STING信号；3）药物干预恢复自噬可降低老龄MɸSTING信号的过度活化，减轻肝脏炎性损伤。进一步拓展研究还发现CHOP、Pink1-PARKIN、MLKL等信号在肝脏缺血再灌注损伤中也发挥着重要的作用。.结论和科学意义：通过上述研究，我们发现了老龄抑制线粒体自噬，加速了线粒体DNA的释放，激活MɸSTING信号，进一步激动NLRP3炎症小体，促进了肝脏炎症损伤。靶向激活自噬的治疗策略，可降低老龄肝脏的缺血再灌注损伤。这可能成为临床减轻老龄肝脏缺血再灌注损伤的重要手段。