调节性IL-10+中性粒细胞在CVB3诱导的急性心肌炎和心肌纤维化中的调控作用及机制

Neutrophils are critical peripheral monitoring innate cells in host defense against bacterial and fungi infection. However, the role of neutrophils in host defense to viral infections remains poorly characterized. Intensive neutrophil infiltration (up to 80% of infiltrated leucocytes) has been detected in the local apartment during various viral infections. Neutrophil antiviral activity is beneficial in some cases, whereas unbalanced inflammatory neutrophil response may worsen the disease outcome. In our previous study, Coxsackievirus B3 (CVB3) infection up-regulated IL-17A expression in the heart as early as day 3 post infection, leading to a robust peripheral neutrophil expansion and influx into the heart via IL-17-IL-17RA pathway. Infection of IL-17RA KO mice with CVB3 significantly reduced cardiac neutrophil-chemokines expression, cardiac neutrophil infiltration and cardiac inflammation. CVB3-induced neutrophil excellular traps (NET) structure had a direct injury effect on cardiomyocytes, indicating a pro-inflammatory detrimental role of cardiac neutrophils. However, peripheral depletion of neutrophils by mAbs did not affect viral replication or disease progression. Meanwhile, we also noticed a significantly induced production of IL-10 by neutrophils in vivo and in vitro by CVB3 which inhibited cardiac TNFα response indicating a regulatory role of cardiac IL-10+neutrophils. Thereafter, in this study, we would focus the induction kinetics of IL-10-secreting regulatory neutrophils during CVB3 infection, their regulatory mechanism by targeting cardiac monocyte/macrophages or Th1/Th17 pro-inflammatory response. We are also interested in their countering effect on the pro-inflammatory TNFα+neutrophils. The data hope to provide novel insight into the pathogenesis of CVB3 myocarditis and new targets for treating viral myocarditis and cardiomyopathy.

中性粒细胞是抗细菌真菌感染的关键前哨效应细胞，但于病毒感染的作用不明。我们在B3柯萨奇病毒（CVB3）诱导的小鼠急性病毒性心肌炎（viral myocarditis）中，发现感染3天心脏HMGB1释放及IL-17-IL-17RA通路介导外周血中性粒扩增和心脏中性粒细胞优势浸润；敲除IL-17RA可显著减轻CVB3诱导的心脏中性粒细胞浸润、心肌炎及心肌纤维化；CVB3诱导的胞外诱捕网NET效应亦直接损伤心肌，提示早期中性粒的促炎有害作用；然而清除外周中性粒细胞不影响病毒复制与心肌炎，同时发现中性粒细胞体内外经CVB3刺激显著分泌IL-10，且可抑制心脏TNFα应答。本研究拟深入阐明IL-10+调节性中性粒细胞的诱生和对促炎单核巨噬细胞及Th1/Th17应答的免疫调控功能与机制，及调节性中性粒与TNFα+促炎中性粒细胞在CVB3感染中的消长与拮抗，为病毒性心肌炎的免疫发病机制和免疫防治策略提供新切入点。

中性粒细胞在病毒感染中的作用迄今不明。B3柯萨奇病毒（CVB3）诱导的小鼠急性病毒性心肌炎（viral myocarditis, VMC）和急性胰腺炎（acute pancreatitis, AP）中，发现IL-17-IL-17RA通路介导感染3天心脏和胰腺中性粒细胞优势浸润；中性粒细胞本身不支持病毒复制；清除外周中性粒细胞不影响病毒复制与心肌炎，而IL-17RA缺失通过显著降低心脏和胰腺中性粒细胞浸润减轻VMC和AP；中性粒细胞体内外经CVB3刺激显著分泌IL-10，IL-10+调节性中性粒细胞体外可促进CVB3在巨噬细胞复制，体内通过抑制TNFα+巨噬细胞和IFNg+CD8+T应答促病毒复制、加剧VMC与AP。Annexin A1模拟肽Ac2-26通过显著抑制中性粒细胞组织浸润和抗病毒发挥良好的治疗急性VMC和AP作用。因此脏器局部调节性中性粒的诱导促进病毒复制并加剧CVB3心肌炎和胰腺炎疾病进展。本结果为VMC和AP免疫发病机制和免疫防治策略提供新靶点。