Non-tuberculous mycobacterium and B cells in the stimulation of ectopic germinal centers and immunological control of pulmonary tuberculosis

项目摘要 人类结核病(TB)主要由结核分枝杆菌(MTB)引起，是一种巨大的 由于目前可获得的药物和疫苗不足，全球卫生面临挑战。最多的 常见的临床表现是肺结核，卡介苗(BCG)是唯一获得许可的疫苗 用于预防结核病；然而，它的效力是高度可变的。今天，至少有52个国家报告了 无法治愈或控制的多药耐药(MDR)和广泛耐药(XDR)结核病病例 目前的结核病治疗。因此，迫切需要开发新的疗法/疫苗，以有效地预防或 治愈结核病。众所周知，针对结核分枝杆菌的获得性免疫反应的产生发生在 次级淋巴器官(SLO)中的生发中心(GC)，如脾和病变引流淋巴结， 抗原提呈细胞(APC)和抗原特异性循环T、B淋巴细胞克隆性相互作用 扩大，并传播到感染部位。我们发现接种了卡介苗并暴露于 禽分枝杆菌[一种非结核分枝杆菌(NTM)]通过饮用水提供更强大的 通过减少结核分枝杆菌的细菌负荷和炎症而确定的比单独使用卡介苗更长期的保护 感染的进展。有趣的是，这些小鼠还在肺部发育了异位生发中心(EGC)。 B细胞数量增加，抗结核分枝杆菌细胞裂解物特异性IgA和IgG抗体水平升高。 这些发现表明NTM和B细胞在产生保护性免疫中起着关键作用。 肺部结核分枝杆菌感染，这些小鼠中EGC的形成是提高免疫力的关键因素。 因此，研究EGC的形成机制以及NTM和B细胞在其刺激中的作用是一个重要的研究方向。 这是了解结核病发病机制和开发有效的疫苗和治疗方法的重要问题。在这台K99/R00 应用方面，我们提出了三个目标：1)研究EGC在肺部和常规肺组织中的主要区别 2)评估NTM和B细胞在EGC刺激中的作用，以及3)表征 EGC B细胞抗结核分枝杆菌抗原的特异性和亲和力。这项提议的结果将给我们带来一个 进一步了解B细胞和抗体介导的预防结核病的机制。

Project Summary Human tuberculosis (TB) is caused mainly by Mycobacterium tuberculosis (Mtb) and represents an enormous challenge to global health because of the inadequacy of currently available drugs and vaccines. The most common clinical manifestation is pulmonary TB, and Bacille Calmette Guerin (BCG) is the only licensed vaccine for protection against TB; however, its efficacy is highly variable. Today at least 52 countries have reported multidrug-resistant (MDR) and extensive drug-resistant (XDR) TB cases which cannot be cured or contained by current TB therapy. Thus, there is an urgent need to develop new therapies/vaccines that effectively prevent or cure TB. It is well established that the generation of an adaptive immune response against Mtb occurs inside germinal centers (GCs) in secondary lymphoid organs (SLOs), such as spleen and lesion draining lymph nodes, where antigen‐presenting cells (APCs) and antigen-specific circulating T and B lymphocytes interact, clonally expand, and are disseminated to sites of infection. We found that mice vaccinated with BCG and exposed to Mycobacterium avium [a non-tuberculous mycobacterium (NTM)] via drinking water provide more robust and longer-term protection than BCG alone as determined by reduced Mtb bacterial burden and inflammatory progression of infection. Interestingly, these mice also developed ectopic germinal centers (eGC) in the lungs and have an increased number of B-cells and higher levels of anti-Mtb cell lysate-specific IgA and IgG antibodies. These findings suggest that NTM and B-cells play a critical role in generating protective immunity against pulmonary Mtb infection, and the formation of eGC in these mice is a crucial factor in this improved immunity. Thus, investigating the mechanism of eGC formation and the role of NTM and B-cells in its stimulation is an important question to understand TB pathogenesis and develop effective vaccines and therapies. In this K99/R00 application, we propose three aims: 1) investigating the key differences between eGC in lungs and conventional GCs in lymph nodes, 2) evaluating the role of NTM and B-cells in eGC stimulation, and 3) characterizing the antigen-specificity and affinity of eGC B-cells against Mtb antigens. The results of this proposal will bring us one step closer to understanding the B-cell and antibody-mediated mechanisms of protection from TB.