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

项目总结/摘要 结核病（TB）是由结核分枝杆菌（Mtb）感染引起的疾病， 每年有200万人感染结核病，而且没有可靠的疫苗来预防结核病。CD 4 T细胞对宿主细胞的增殖至关重要。 保护，通过多种效应机制与Mtb感染的细胞直接相互作用起作用。人 携带潜伏性Mtb感染（LTBI）的HIV感染者（PWH）发生活动性结核病的风险高达20倍。 疾病尽管维持CD 4 T细胞计数超过500 / uL，但PWH中活动性TB的风险升高持续存在， 有效抑制病毒。然而，一个确切的机制，结核病的风险增加之间的PWH与稳定 CD 4计数不清楚。鉴于结核病T细胞疫苗的研究工作，一个关键的研究重点是确定 记忆性CD 4 T细胞的特定属性对于降低PWH中的TB风险至关重要。唯一标识 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（CX 3CR 1）的Mtb特异性CD 4 T细胞被证明是 含有有效的效应子功能，包括强大的IFNg分泌和细胞溶解功能，但它们被认为是 非保护性的，因为它们保留在肺微血管系统中，并且在肺实质中基本上不存在。 小鼠和非人灵长类动物（NHP）结核病模型。有趣的是，发现CX 3CR 1 + T细胞与CX 3CR 1 + T细胞相比， PWH中的频率，可能是由于慢性炎症。我们的总体假设是，尽管维持 稳定的总CD 4计数，与HIV感染相关的炎症状态的比例增加， 对Mtb具有特异性的CX 3CR 1 + CD 4 T细胞，以及其他作用，并损害其肺实质运输。这 该项目旨在了解Mtb特异性的运输和粘附受体的表达和功能， 记忆性CD 4 T细胞，比较来自HIV+和HIV-个体的LTBI。在目标1中，我们将使用 自体离体共培养系统，以鉴定能够响应Mtb感染的记忆性CD 4 T细胞 巨噬细胞，并决定哪些运输和粘附受体，他们表达。我们进一步评估 Mtb特异性CD 4 + T细胞效应子功能和T细胞抗原受体（TCR）库的异质性 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 表面受体与记忆性CD 4 T细胞通过血管内皮向血管内皮的运输有关。 结核杆菌感染的巨噬细胞。要使疫苗有效预防结核病，它必须引发能够动员的T细胞， 到达肺部感染部位并识别感染细胞。这项研究的结果将决定 分离自HIV-1的Mtb特异性CD 4 T细胞之间的功能和运输受体表达的差异。 以及这些差异与T细胞通过LTBI的运输相关的程度。 血管内皮这些结果将为结核病疫苗开发提供基准，并将揭示靶点 用于受体阻断，可以改善T细胞向Mtb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.