血小板-中性粒细胞凝集介导的线粒体NETosis在SFTSV重症/危重症感染中的作用机制研究

发热伴血小板减少综合征病毒（SFTSV）感染可引起致死性出血热。血小板减少是SFTS多器官衰竭的始动因素，但机制不明。近年发现血小板-中性粒细胞凝集既能造成血小板减少，又能触发中性粒细胞胞外诱捕网（NETs）释放。NETs是造成组织损伤的细胞外DNA-蛋白质复合物。我们前期发现NETs升高与血小板减少有关，且是SFTS患者预后不良的新标志；但非经典的染色质NETs，而是线粒体NETs。据此提出：血小板-中性粒细胞凝集破坏Ca2+稳态，触发线粒体NETs释放，从而造成SFTS多器官衰竭。本项目拟通过临床队列和小鼠模型明确线粒体NETs在SFTS重症化过程中的作用，阐明凝集的分子途径以及进而引起Ca2+内流、线粒体NETs释放（即NETosis）的机制。采用抗凝剂、NETs抑制剂反向验证，探讨干预线粒体NETosis的分子靶点，阐明SFTS重症化机制，为降低病死率提供新的免疫治疗策略。

Severe fever with thrombocytopenia syndrome virus (SFTSV) infection can cause hemorrhagic fever, with a serious condition and a high mortality rate. Thrombocytopenia is the initiating factor for multiple organ failure in SFTS, but the mechanism is still unknown. In recent years, it has been discovered that "platelet-neutrophil aggregation" is both an immunological cause of thrombocytopenia and a fuse triggering the release of neutrophil extracellular traps (NETs). NETs are extracellular DNA-protein complexes that cause inflammatory damage of tissues. We preliminary found that the levels of NETs were negatively correlated with the numbers of platelets, and are also a novel biomarker of poor prognosis in SFTS. However, SFTS patients were dominated by mitochondrial NETs rather than classic chromatin NETs. Accordingly, it is proposed that the platelet-neutrophil aggregation disrupts the calcium homeostasis and subsequently triggers the release of mitochondrial NETs, results in multiple organ failure in SFTS. We intend to clarify the pathological role of mitochondrial NETs in severe SFTSV infection through clinical cohort and mouse models; to investigate the molecular pathway of platelet-neutrophil aggregation and the mechanism that causes calcium influx and mitochondrial NETs release (NETosis); finally, to perform the verification assays by using anticoagulants and NETs inhibitors in vivo and in vitro. The aim of this project is to explore the molecular targets of mitochondrial NETosis to clarify the mechanism of SFTS severe / critical infection and to provide a new immunotherapy strategy to reduce the mortality.