In vivo mechanisms of Mycobacterium tuberculosis control and susceptibility

项目摘要 结核分枝杆菌(MTB)感染肺部，每年导致160万人死亡。唯一的疫苗 被批准用于结核病的疗效有限。此外，抗生素治疗需要六个月，但可以 对于正在变得更加流行的多重耐药菌株，需要两年或更长时间。因此， 开发一种直接针对结核分枝杆菌宿主的治疗策略将极大地 影响人类健康。我建议确定新的先天性免疫因子，以防止结核分枝杆菌感染 活体，这可能是这种治疗方法的基础。具体目标：在结核分枝杆菌感染期间， 像IL-1这样的炎性细胞因子刺激未感染的细胞产生增强抗菌作用的因子 携带结核分枝杆菌的细胞活性。虽然IL-1对于预防结核分枝杆菌至关重要，但它的作用机制是 未知。目的1)我们鉴定了结核分枝杆菌感染肺中的IL-1敏感细胞和IL-1诱导基因 由这些细胞表达。我将测试自然杀伤T 17细胞，IL-1敏感群体之一， 提供对结核分枝杆菌的保护。此外，我将确定哪些IL-1诱导的基因直接作用于结核分枝杆菌 体内感染巨噬细胞，发挥IL-1的保护作用。目的2)中性粒细胞在结核分枝杆菌中有害- 敏感的小鼠品系和中性粒细胞增多与人类的细菌负荷和死亡率呈正相关。 然而，目前尚不清楚中性粒细胞如何干扰宿主对结核分枝杆菌的反应。我们之前已经表明， IL-1受体拮抗剂(IL-1ra)是一种免疫抑制分子，可限制易感人群的结核分枝杆菌控制 老鼠品系。由于中性粒细胞高度表达IL-1ra，我将确定中性粒细胞是否抑制 通过产生IL-1ra对结核分枝杆菌的保护性反应以及这种免疫抑制是否 功能在多个结核分枝杆菌敏感株之间是保守的。另外，我会确定中性粒细胞 利用其他免疫抑制途径，如IL-18信号抑制和PD-1，以阻碍生产 结核分枝杆菌的免疫应答。研究设计：我将定义非感染者和感染者之间的沟通方式 细胞通过产生混合骨髓嵌合体来控制结核病感染。这些实验 将测试IL-1驱动的基因表达与我们的单细胞RNA中确定的候选基因在体内的相关性 结核杆菌感染肺的测序数据集。此外，我将利用我们的单细胞RNA测序数据集 确定中性粒细胞如何抑制结核分枝杆菌敏感小鼠品系的感染控制。潜在影响： 结核分枝杆菌控制的保护性和抑制性调控因子的鉴定可以作为宿主定向调控的基础 治疗结核分枝杆菌感染的治疗方法，这将是该领域的重大进展。

Project Summary Mycobacterium tuberculosis (Mtb) infects the lungs causing 1.6 million deaths a year. The only vaccine approved for tuberculosis has limited efficacy. Additionally, antibiotic treatment requires six months, but can require two or more years for multi-drug resistant strains that are becoming more prevalent. Therefore, development of a host-directed therapeutic strategy that directly targets the Mtb reservoir would dramatically impact human health. I propose to identify novel innate immune factors that protect against Mtb infection in vivo, which could be the basis of such a therapeutic approach. Specific Aims: During Mtb infection, inflammatory cytokines like IL-1 stimulate non-infected cells to produce factors that enhance anti-bacterial activity of Mtb-bearing cells. While IL-1 is critical for protection against Mtb, its mechanism of action is unknown. Aim 1) We have identified IL-1 sensing cells in Mtb-infected lungs and IL-1-induced genes expressed by these cells. I will test whether natural killer T 17 cells, one of the IL-1 sensing populations, provides protection against Mtb. Additionally, I will determine which IL-1-induced genes act directly on Mtb infected macrophages in vivo to confer the protective effect of IL-1. Aim 2) Neutrophils are detrimental in Mtb- susceptible mouse strains and neutrophilia positively correlates with bacterial burden and mortality in humans. However, it is unclear how neutrophils interfere with the host response to Mtb. We have previously shown that IL-1 receptor antagonist (IL-1Ra) is an immunosuppressive molecule that limits Mtb control in a susceptible mouse strain. As IL-1Ra is highly expressed by neutrophils, I will determine whether neutrophils inhibit the protective response against Mtb through their production of IL-1Ra and whether this immunosuppressive function is conserved across multiple Mtb susceptible strains. Additionally, I will determine whether neutrophils exploit other immunosuppressive pathways, like IL-18 signaling inhibition and PD-1, to hinder the productive immune response to Mtb. Study Design: I will define how communication between non-infected and infected cells leads to control of tuberculosis infection by generating mixed bone marrow chimeras. These experiments will test the in vivo relevance of IL-1-driven gene expression for candidates identified in our single cell RNA- sequencing dataset of Mtb-infected lungs. Additionally, I will leverage our single cell RNA-sequencing dataset to determine how neutrophils inhibit control of the infection in Mtb-sensitive mouse strains. Potential Impact: The identification of protective and inhibitory regulators of Mtb control can serve as the basis for host-directed therapies to treat Mtb infection, which will be a major advance for the field.