VEGFR-3调控巨噬细胞焦亡的分子机制研究

Pyroptosis plays key role in sensing and denfensing pathogen or endogenous dangerous signals. However, excessive pyroptosis might induce a variety of pathological inflammatory diseases. Our study has demonstrated that vascular endothelial growth factor receptor-3 (VEGFR-3) shows a feedback inhibition of TLR4-mediated inflammatory response in macrophages. However, little is known about the role of VEGFR-3 in bacterial-induced macrophage pyroptosis. We showed that deficiency of VEGFR-3 signaling markedly promotes the formation of ASC specks, caspase-1 activation, pyroptosis and IL-1β secretion, which resulting in the clearance of S.Typhimurium. We will use VEGFR-3 mutant mice carrying kinase dead or ligand-binding domain deletion to further investigate how VEGFR-3 regulate ASC-caspase activation and following induced pyroptosis and secretion of IL-1β/IL-18 in response to bacterial infection. This project proposes a new mechanism of inflammasome-induced pyroptosis regulated by VEGFR-3, which help us further understand the regulation mechanism of pyroptosis. And VEGFR-3 antibody or ligand will be potential targets for intervention and drug development.

细胞焦亡在宿主感知并抵抗病原体感染或内源性危险信号中发挥重要作用，然而过度的细胞焦亡会诱发机体多种炎症相关疾病。我们前期已发表的研究结果证明细胞表面的血管内皮生长因子受体-3（VEGFR-3）反馈性抑制巨噬细胞中TLR4介导的炎症反应，但目前仍未有报道其调控细菌诱发巨噬细胞焦亡的功能研究。本项目预实验发现VEGFR-3能够抑制沙门氏菌感染诱发的细胞焦亡和IL-1β分泌，调控巨噬细胞对沙门氏菌的清除。利用VEGFR-3活性位点突变或功能区缺失的基因工程小鼠，阐明细菌感染时VEGFR-3调控ASC-caspase诱发的细胞焦亡和IL-1β/IL-18的作用机制。该研究创新性地提出VEGFR-3协同炎症小体通路调控细胞焦亡发生的新分子机制，有利于我们进一步认识细胞焦亡的调控机理，并且利用其抗体或配体进行人为干涉，成为应用价值较高的潜在药物靶点。

巨噬细胞作为机体对抗感染的重要免疫细胞，能够快速做出糖代谢重编程并调控炎症小体活化和焦亡信号通路以清除病原微生物。那么，鉴定有效的参与调控这些过程的关键分子将提供重要的潜在治疗靶点。沙门氏菌感染过程中，VEGFR3一方面抑制caspase-1介导的炎症小体活化和焦亡，另一方面增强巨噬细胞清除沙门氏菌的感染。与此一致的是，在感染小鼠的肝脏组织和巨噬细胞中，缺乏胞外配体结合域的VEGFR3突变体显著上调了琥珀酸和乳酸等促炎代谢物的水平，同时减少包括柠檬酸和NAD(P)H在内的抗菌代谢物的水平。机制上，我们进一步发现VEGFR3结合并促进AMPK α的磷酸化，进而激活AMPK。同时利用AMPK激动剂或抑制剂能够有效回复VEGFR3突变体对糖代谢重编程和炎症小体活化的作用，这将对携带VEGFR3突变的患者在防止复发感染上有潜在的转化应用价值。