Immune control mechanisms of TB latency in the setting of HIV co-infection

 描述（由申请人提供）： 结核分枝杆菌（Mycobacterium tuberculosis，MTb）驱动增强的HIV复制和疾病进展，相反，HIV诱导的CD 4 + T细胞耗竭增加了新发MTb感染的风险，更重要的是，MTb从潜伏期重新激活。肺泡巨噬细胞（AM）是MTb在传播时的主要靶标，并且也是肉芽肿病变中缓慢复制和/或休眠的分枝杆菌的主要来源。AM也被HIV急性感染和潜伏HIV。AM内的MTb复制还驱动肺部的局部炎症，这反过来又可以驱动HIV从潜伏期重新激活。因此，在巨噬细胞中HIV感染的背景下，对参与控制潜伏性和活动性TB的免疫学和细胞机制的更好理解对于设计旨在控制合并感染和加速清除潜伏生物体以降低MTb再活化风险的新型治疗至关重要。我们的初步研究已经证明，干扰素刺激的基因（ISG）产物，干扰素诱导的跨膜蛋白3（IFITM 3），由MTb感染诱导，并抑制MTb和HIV-1感染的人单核细胞和单核细胞衍生的巨噬细胞（MDM）。我们还发现FDA批准的小分子硝唑尼特（NTZ）诱导IFITM 3的表达，并且还诱导HIV限制因子SAMHD 1。此外，我们已经表明NTZ抑制单核细胞和MDM中的MTb和HIV感染，并抑制单核细胞中MTb和TLR介导的沉默的小型HIV-1前病毒的激活。基于我们的初步数据，我们将检验以下主要假设：（i）IFITM 3是抑制MTb/HIV-1共感染和MTb在肺靶细胞中存活的关键免疫调节剂，和（ii）NTZ通过直接刺激IFITM 3以及其他宿主因子（包括PKR和在HIV-1的情况下，特别是SAMHD 1）来抑制两种病原体的生长。具体地，在目的1中，我们将测试IFITM 3是TB/HIV共感染的关键免疫调节剂，并且其通过干扰宿主脂质生物合成和定位于成熟吞噬体来限制MTb感染的假设。在目标2中，我们将重点阐明NTZ抑制MTb和HIV感染骨髓细胞的机制。我们将检验NTZ通过诱导IFITM 3和PKR抑制MTb以及通过诱导/激活SAMHD 1和PKR抑制HIV感染的假设。此外，我们将研究NTZ对HIV和TB的抑制作用是否涉及PKR依赖性自噬的刺激，从而导致增强的病毒和细菌降解。我们期望确定新的IFITM 3相关的双重TB/HIV抑制机制，包括那些对MTb存活和代谢转换到休眠至关重要的机制，这些机制将作为在HIV共感染的背景下同时调节潜伏性和活动性TB疾病的有吸引力的靶点。我们还预计，我们将确定NTZ介导的抗TB/HIV活性的分子和免疫学相关性，这将为快速重新利用NTZ作为潜伏性TB和TB/HIV的治疗提供基础。

 DESCRIPTION (provided by applicant): MTb (Mycobacterium tuberculosis) drives enhanced HIV replication and disease progression and, conversely, HIV-induced CD4+ T cell depletion increases risk of de novo MTb infection and, more importantly, MTb reactivation from latency. Alveolar macrophages (AMs) are a primary target of MTb upon transmission and are also a major source of slowly replicating and/or dormant mycobacterial in granulomous lesions. AMs are also infected by HIV acutely and harbor latent HIV. MTb replication within AMs also drives local inflammation in the lung, which in can in turn drive HIV reactivation from latency. Thus, improved understanding of the immunological and cellular mechanisms involved in the control of latent and active TB in the context of HIV infection in macrophages is critical for the design of novel treatments aimed at controlling co-infection and expediting the clearance of latent organisms to reduce risk of MTb reactivation. Our preliminary studies have demonstrated that an interferon-stimulated gene (ISG) product, interferon-inducible trans-membrane protein 3 (IFITM3), is induced by MTb infection and inhibits MTb and HIV-1 infection of human monocytes and monocyte -derived-macrophages (MDM). We have also found that the FDA-approved small molecule nitazoxanide (NTZ) induces expression of IFITM3 and also induces the HIV restriction factor SAMHD1. Furthermore, we have shown that NTZ inhibits MTb and HIV infection in monocytes and MDM, and suppresses MTb- and TLR- mediated activation of a silent mini HIV-1 provirus in monocytic cells. Based on our preliminary data, we will test the major hypothesis that (i) IFITM3 is a criticl immune modulator that inhibits MTb/HIV-1 co-infection and MTb survival in target cells of the lung, and (ii) that NTZ inhibits growth of both pathogens through direct stimulation of IFITM3, as well as additional host factors including PKR and, in the case of HIV-1 specifically, SAMHD1. Specifically, in Aim 1 we will test the hypotheses that IFITM3 is a critical immune modulator of TB/HIV co-infection, and that it restricts MTb infection via perturbation of host lipid biosynthesi and localization to the maturing phagosome. In Aim 2 we will focus on elucidating the mechanisms involved in NTZ inhibition of MTb and HIV infection of myeloid cells. We will test the hypothesis that NTZ inhibits MTb via its induction of IFITM3 and PKR, and that it inhibits HIV infection via its induction/activation of SAMHD1 and PKR. Furthermore, we will investigate whether NTZ's inhibitory effect upon HIV and TB involves stimulation of PKR- dependent autophagy, leading to enhanced viral and bacterial degradation. We expect to identify novel IFITM3-associated mechanisms of dual TB/HIV suppression, including those that are critical for MTb survival and metabolic switching to dormancy that will serve as attractive targets for simultaneous modulation of both latent and active TB disease in the context of HIV co-infection. We also anticipate that we will identify molecular and immunological correlates of NTZ-mediated anti-TB/HIV activity that will provide a foundation for the rapid repurposing of NTZ as a treatment of latent TB and TB/HIV.