LAMPs诱导记忆性肺泡巨噬细胞的作用及分子机制研究

Mycoplasma pneumonia is a leading cause of community-acquired pneumonia in children. Severe and refractory mycoplasma pneumonia pneumoniae increase year by year, there is limited means of prevention and treatment at present. Innate immunity plays a leading role in the clearance of mycoplasma pneumonia infection, especially alveolar macrophages. Recent studies have shown that innate immune cells also have immune memory functions, but little is known about how these immune memories are formed. Our previous studies showed that lipid-associated membrane proteins (LAMPs) could induce a strong immune memory function in pulmonary macrophages, further studies demonstrated that LAMPs might affect the glucose metabolism of macrophages through TLR2, and influenced the up-regulation of H3K4me3 and the decrease of H3K9me3 to induce the formation of immune memory in macrophages, and these memory alveolar macrophages had strong ability to clear MP. In order to provide a new theoretical basis for the prevention and treatment of mycoplasma pneumonia infection, the purpose of this study is to study the role and molecular mechanism of LAMPs-induced memory alveolar macrophage formation.

肺炎支原体是儿童社区获得性肺炎的最主要病原。重症和难治性肺炎支原体肺炎逐年增多，目前防治手段有限。固有免疫在清除肺炎支原体感染过程中起主导作用，尤其是肺泡巨噬细胞。最新研究进展显示，固有免疫细胞同样具有免疫记忆功能，但这些免疫记忆如何形成却知之甚少。我们的前期研究结果表明，肺炎支原体来源的膜脂蛋白（Lipid-associated membrane proteins, LAMPs）可以诱导很强的肺巨噬细胞的免疫记忆功能，且进一步的研究证明LAMPs可能通过TLR2进而影响巨噬细胞的糖代谢，并影响H3K4me3的上调以及H3K9me3的下降来最终诱导巨噬细胞的免疫记忆形成，且这些记忆性肺泡巨噬细胞具有较强的清除MP的能力。本课题拟在已有研究基础上，进一步通过分子生物学手段研究LAMPs诱导记忆性肺泡巨噬细胞形成的作用及机制，为肺炎支原体感染的防治提供新的理论依据。

肺泡巨噬细胞(Alveolar macrophages, AMs)作为固有免疫细胞具有免疫记忆功能，在清除MP感染中起主要作用，MP来源的膜脂蛋白（Lipid-associated membrane proteins, LAMPs）可以诱导巨噬细胞免疫记忆功能，本项目从表观遗传和细胞代谢重编程角度研究LAMPs诱导记忆性AMs形成机制。.本项目首先培养MP获得LAMPs，LAMPs可以浓度依赖形式刺激A549上皮细胞高表达MUC5AC和MUC5B，表明LAMPs具有生物学功能。LAMPs与小鼠AMs共育24h，更换新鲜培养基，再予灭活MP共育，检测AMs对MP吞噬作用、胞内MP杀灭率、TNF-α和IL-6水平，结果发现LAMPs刺激后AMs吞噬和杀菌能力增强、促炎因子分泌增强，提示LAMPs可以诱导记忆性AMs形成。TLR2受体参与了记忆性AMs形成。LAMPs预处理小鼠，再予MP感染小鼠，结果发现，LAMPs预处理小鼠清除MP所需天数少，表明具有固有免疫记忆的小鼠清除MP的能力强。其次，检测记忆性AMs表观遗传学标志H3K4me和H3K9me的水平，结果发现H3K4me升高，H3K9me下降，表明LAMPs诱导AMs固有免疫记忆与组蛋白修饰有关。最后，检测记忆性AMs乳酸浓度和NAD+/NADH水平，结果发现乳酸浓度和NAD+/NADH水平均升高，提示其糖酵解水平增加，表明LAMPs诱导AMs固有免疫记忆与糖代谢增强有关。综上，LAMPs可以诱导记忆性AMs形成，深入研究其机制可为临床治疗MP感染提供有效的新手段。