巨噬细胞极化分型在分枝杆菌感染免疫应答中的作用及其转化医学研究

Mycobacterium leprae (ML) and Mycobacterium tuberculosis (M.tb)can live in the infected macrophages and multinuclear giant cells for a long time. Macrophages are a heterogeneous population of immune cells that are essential for the initiation and resolution of pathogen- or tissue damage-induced inflammation. Macrophages demonstrate considerable plasticity that allows them to respond efficiently to environmental signals. On the basis of the T helper type 1 (TH1) and TH2 polarization idea, these cells are now referred to as M1 (classic) macrophages, which produce proinflammatory cytokines and mediate resistance to pathogens and contribute to tissue destruction, and M2 (alternative) macrophages, which produce anti- inflammatory cytokines and promote tissue repair. While these environmental signals( pathogen and cytokines) inducing the macrophage polarization can also promote the formation of multinuclear giant cells. So far, we still know little about after macrophages infected with ML or M.tb, whether the plasticity of classically activated M1 macrophages and alternatively activated M2 macrophages have been changed or not? and how about their effect on host fighting against mycobacterial infections? In this study, we will investigate the contribution and mechanism of the macrophage polarization and its multinuclear giant cell formation in the immune responses of host struggling against ML or M.tb infections especially including molecular and cellular interplay between ML or M.tb and infected host cells, the function of the antigen presentation and ability that inducing specific immune responses of T lymphocytes of different polarizing macrophages and multinuclear giant cell infected with ML or M.tb. In addition, we will explore the relationship between the macrophages polarization and multinuclear giant cells formation with the spectrum of clinical and histopathological manifestations of leprosy. Macrophages will be induced into special polarization in vitro which possesing ability to strongly control pathogens invading, and which were conformed by nude mice infected by ML.Experiment methods involving cell culture, May-Grünwald-Giemsa stain(MGG), immunohistochemistry, ELISA, radiorespirometry, flow cytometry, confocal microscope and RNA sequencing etc. will be used in this study.

巨噬细胞既是麻风和结核杆菌长期寄居的场所，又是对其发动天然免疫和适应性免疫的 "操纵者"。巨噬细胞的极化分型（M1型和M2型）与宿主Th1和Th2细胞免疫应答密切相关，且导致巨噬细胞极化分型的重要免疫分子也是其形成多核巨细胞的"推手"。本项目拟以麻风病这一极佳的巨噬细胞极化分型的天然模型为基础，结合已建立的可动态观察巨噬细胞极化分型形成过程的体外实验平台，通过将免疫组化、流式细胞仪及RNA Sequencing等检测技术相结合来深入研究被分枝杆菌感染后的巨噬细胞之极化分型能力和相关功能的变化，特别是不同极化状态下的巨噬细胞和其多核巨细胞在相关信号传导、吞噬细菌和杀灭细菌、抗原递呈和诱导T细胞免疫应答能力的变化，同时研究巨噬细胞极化分型在决定麻风病不同临床谱型形成中的作用，揭示巨噬细胞极化分型在分枝杆菌抗感染免疫应答中的作用和机制，并筛选和验证可以用于抗分枝杆菌感染免疫治疗的极化型巨噬细胞。

巨噬细胞既是麻风和结核杆菌长期寄居的场所，又是对其发动天然免疫和适应性免疫的“操纵者”。巨噬细胞的极化分型（M1 型和 M2 型） 与宿主 Th1 和 Th2 细胞免疫应答密切相关，且导致巨噬细胞极化分型的重要免疫分子也是其形成多核巨细胞的“推手”。本项目建立能实现动态、直观地观察巨噬细胞极化分型和向MGCs演变的分枝杆菌感染的巨噬细胞极化分型体外实验平台，通过将免疫组化、流式细胞仪及 RNA Sequencing 等检测技术相结合，来深入研究被分枝杆菌感染后的巨噬细胞之极化分型能力和相关功能的变化。研究结果发现不同极化状态下的巨噬细胞和其MGCs在吞噬细菌和杀灭细菌、抗原递呈和诱导T细胞免疫应答能力方面的具有明显的差异；M2细胞杀菌能力低于M1细胞，而吞噬能力和抗原递呈的能力高于M1细胞。而麻风病不同临床谱型细胞构成比、表达差异基因及其通路、长链非编码RNA(LncRNA)结果有较大差别，这些差异基因的发掘为巨噬细胞极化分型、MGCS和感染性肉芽肿形成和维持机制研究提供了新的切入点，需进一步挖掘。