谷氨酰胺通过增加中性粒细胞焦亡抑制临床高毒力肺炎克雷伯菌肝脓肿并发迁徙性感染的机制

Liver abscess caused by highly virulent Klebsiella pneumoniae (hvKP) is prone to metastatic infections and is one of the infectious diseases with higher morbidity and mortality in our country. It was reported that inability of neutrophil killing of bacteria may be the main reason causing metastatic infection, however, the specific mechanism is still unclear. In our previous studies, the ratio of pyroptotic neutrophils after infection with hvKP was found to be significantly lower than that after classic K. pneumoniae infection. Moreover, the expressions of neutrophil pyroptosis marker proteins IL-1β and LDH were obviously inhibited by hvKP infection. In addition, exogenously supplied glutamine can inhibit hvKP-induced liver abscess and metastatic infection. Therefore, we speculate that glutamine can inhibit K. pneumoniae liver abscess and metastatic infection via enhancing neutrophil pyroptosis. In this project, we intend to analyze the phenomenon of hvKP affecting the secretion of inflammatory factors such as IL-1β and IL-18, and the neutrophil pyroptosis and macrophage efferocytosis in vivo and in vitro, and further clarify the mechanism of glutamine inhibiting K. pneumoniae liver abscess and metastatic infection via regulation of neutrophil pyroptosis, ROS release and NLRP3/Caspase-1/IL-1β pathway. This project will shed new light on the mechanism of innate immune inhibiting bacterial infection, offer new clues to enrich immune cell pyroptosis theory, and provide new theoretical and experimental basis for the treatment of anti-hvKP infection.

高毒力肺炎克雷伯菌（hvKP）所致肝脓肿易并发迁徙性感染，在我国发病率高且病症危重。研究显示中性粒细胞清除细菌障碍是迁徙性感染的主要原因，然而具体机制仍不清。我们前期研究发现hvKP感染后中性粒细胞发生焦亡的比例明显少于经典肺炎克雷伯菌感染，并抑制中性粒细胞焦亡标志物IL-1β和LDH表达；外源补充谷氨酰胺能抑制hvKP所致小鼠肝脓肿并发迁徙感染。我们推测谷氨酰胺通过增加中性粒细胞焦亡抑制hvKP肝脓肿并发迁徙性感染。本项目拟通过体内外实验，分析hvKP对中性粒细胞炎症因子IL-1β和IL-18分泌、细胞焦亡及巨噬细胞胞葬能力的影响，阐明谷氨酰胺通过调控中性粒细胞焦亡，ROS释放和NLRP3/Caspase-1/IL-1β通路抑制hvKP肝脓肿并发迁徙性感染的机制。本项目为理解天然免疫抗菌机制提供新视角，为丰富免疫细胞焦亡发生理论提供新线索，也为抗hvKP感染提供新的理论基础与实验依据。

高毒力肺炎克雷伯菌（hvKP）所致肝脓肿易并发迁徙性感染，在我国发病率高且病症危重。研究显示中性粒细胞清除细菌障碍是迁徙性感染的主要原因，然而具体机制仍不清。我们研究发现hvKP感染后中性粒细胞发生焦亡的比例明显少于经典肺炎克雷伯菌感染，并抑制中性粒细胞焦亡标志物IL-1β和LDH表达；外源补充谷氨酰胺能抑制hvKP所致小鼠肝脓肿并发迁徙感染。实验显示谷氨酰胺通过调控中性粒细胞焦亡，ROS释放和NLRP3/Caspase-1/IL-1β通路抑制hvKP肝脓肿并发迁徙性感染。研究期间，我们还发现致病菌为ESBL阳性的肺炎克雷伯菌为肝脓肿复发的危险因素。本项目还发现了Rcn2参与脓毒症诱导的内皮细胞焦亡调控，并可能是通过SP1-RCN2-ROS-NLRP3信号通路来调控。此外，我们成功构建了能有效预测肺炎克雷伯菌肝脓肿侵袭性的模型。本项目为理解天然免疫抗菌机制提供新视角，为丰富免疫细胞焦亡发生理论提供新线索，也为抗hvKP感染提供新的理论基础与实验依据。