Overcoming restrained lung trafficking by memory CD4+ T cells to prevent active tuberculosis in people living with HIV

项目摘要/摘要 由结核分枝杆菌(Mtb)感染引起的结核病(TB)是一种可导致1.5人死亡的疾病 每年有数百万人，而且没有可靠的疫苗来预防结核病。CD4T细胞对宿主至关重要 保护作用，通过多种效应器机制与结核杆菌感染细胞直接相互作用。人民 携带潜在结核分枝杆菌感染(LTBI)的艾滋病毒携带者(PWH)患活动性疾病的风险高达20倍 疾病。尽管将CD4T细胞计数维持在500个/uL以上，但重症肝炎患者活动性结核病的风险仍在上升 有效的病毒抑制。然而，稳定的PWH患者患结核病风险增加的确切机制 CD4计数尚不清楚。鉴于针对结核病的T细胞疫苗所做的努力，一个关键的研究重点是确定哪种疫苗 记忆性CD4T细胞的特定属性对于降低PWH中的结核病风险至关重要。唯一的标识 来自受保护宿主的T细胞的特征将加速疫苗的开发，并确定宿主的靶点- 定向治疗。最近，表达Fractalkine受体(CX3CR1)的Mtb特异性CD4T细胞被证明是 包含强大的效应器功能，包括强大的干扰素分泌和细胞溶解功能，但它们被认为 无保护作用，因为它们保留在肺微血管中，而在肺实质中大部分缺失 小鼠和非人灵长类(NHP)结核病模型。有趣的是，发现CX3CR1+T细胞增加 可能是由于慢性炎症所致。我们最重要的假设是，尽管 稳定的总CD4计数，与艾滋病毒感染相关的炎症状态增加了 除其他作用外，CX3CR1+CD4T细胞对结核分枝杆菌具有特异性，并损害其肺实质运输。这 该项目试图了解Mtb特异性的贩运和黏附受体的表达和功能 记忆CD4T细胞，比较来自HIV+和HIV感染者的LTBI患者的CD4T细胞。在目标1中，我们将使用 自体体外共培养系统鉴定记忆CD4T细胞对结核分枝杆菌感染的反应 巨噬细胞，并确定它们表达哪些运输和黏附受体。我们进一步评估了 结核分枝杆菌特异性CD4的T细胞效应器功能和T细胞抗原受体(TCR)谱系的异质性 来自HIV+和HIV-个体的T细胞。在目标2中，我们将利用一种新的T细胞迁移试验来确定 表面受体与记忆CD4T细胞通过血管内皮细胞的转运有关 结核杆菌感染的巨噬细胞。对于一种有效预防结核病的疫苗来说，它必须激发能够动员的T细胞 到肺部的感染部位并识别感染的细胞。这项研究的结果将决定 HIV-Mtb特异性CD4T细胞功能和转运受体表达的差异 和HIV+LTBI患者，以及这些差异与T细胞通过 血管内皮细胞。这些结果将为结核病疫苗的开发提供基准，并将揭示目标 受体阻断可以改善T细胞向结核分枝杆菌感染细胞的运输。

PROJECT SUMMARY / ABSTRACT Tuberculosis (TB), caused by infection with Mycobacterium tuberculosis (Mtb), is a disease that kills 1.5 million people every year, and there is no reliable vaccine to prevent TB. CD4 T cells are critical for host protection, acting through direct interaction with Mtb-infected cells via multiple effector mechanisms. People living with HIV (PWH) who harbor latent Mtb infection (LTBI) have up to 20-fold greater risk of developing active disease. The elevated risk of active TB in PWH persists despite maintaining CD4 T cell counts over 500 / uL and effective viral suppression. However, an exact mechanism for the increased risk of TB among PWH with stable CD4 counts is unclear. Given the efforts on T cell vaccines for TB, a key research priority is to determine which specific attributes of memory CD4 T cells are critical to lowering the risk of TB in PWH. Identification of the unique features of T cells from protected hosts would accelerate vaccine development and identify targets for host- directed therapy. Recently, Mtb-specific CD4 T cells that express fractalkine receptor (CX3CR1) were shown to contain potent effector functions, including robust IFNg secretion and cytolytic function, yet they are considered non-protective since they are retained in lung microvasculature and are largely absent from lung parenchyma in the mouse and non-human primate (NHP) models of TB. Interestingly, CX3CR1+ T cells are found with increased frequency in PWH, possibly due to chronic inflammation. Our overarching hypothesis is that despite maintaining stable total CD4 counts, the inflammatory state associated with HIV infection increases the proportion of CX3CR1+ CD4 T cells specific for Mtb, among other effects, and impairs their lung parenchymal trafficking. This project seeks to understand the trafficking and adhesion receptor expression and function of Mtb-specific memory CD4 T cells, comparing those from HIV+ and HIV- individuals with LTBI. In Aim 1, we will use an autologous ex vivo co-culture system to identify the memory CD4 T cells able to respond to Mtb-infected macrophages and determine which trafficking and adhesion receptors they express. We further evaluate the heterogeneity in T cell effector function and T cell antigen receptor (TCR) repertoire among the Mtb-specific CD4 T cells from HIV+ and HIV- individuals. In Aim 2, we will utilize a novel T cell migration assay to determine which surface receptors are associated with the trafficking of memory CD4 T cells through vascular endothelium toward Mtb-infected macrophages. For a vaccine to effectively prevent TB, it must elicit T cells that are able to mobilize to the site of infection in the lung and recognize infected cells. Results from this study will determine the differences in function and trafficking receptor expression between Mtb-specific CD4 T cells isolated from HIV- and HIV+ individuals with LTBI, and the extent to which these differences correlate with T cell trafficking through vascular endothelium. These results will provide benchmarks for TB vaccine development and will reveal targets for receptor blockade that could improve T cell trafficking toward Mtb-infected cells.