A Humanized Mouse Model to Study HIV/Mtb Co-infection

描述(申请人提供)：人类免疫缺陷病毒(HIV)感染正在促使机会性结核病(TB)重新出现，成为一种全球卫生紧急情况，并与耐多药或广泛耐药结核病(MDR-、XDR-TB)的发展密切相关。由于人类对HIV的趋向性，目前还没有研究HIV/结核分枝杆菌混合感染的动物模型。BLT人源化小鼠模型正被迅速应用于研究几种缺乏合适动物模型的病原体，包括艾滋病毒、疟疾和艾滋病毒/丙型肝炎病毒联合感染。这项建议的目的是在人源化小鼠中开发一种HIV/Mtb混合感染的小动物模型，用于对Mtb疫苗开发至关重要的免疫学研究。中心假设是HIV感染将增加结核分枝杆菌的发病机制，并在HIV/Mtb混合感染的人源化小鼠模型中损害疫苗诱导的细胞介导的结核杆菌免疫。拟议研究的基本原理是，人类艾滋病毒/结核分枝杆菌混合感染的小动物模型将极大地促进在了解艾滋病毒抑制CMI到结核分枝杆菌感染的这些和其他机制方面的进展，并加快针对艾滋病毒+人群的结核病疫苗的设计和筛选。验证这一中心假设的具体目的是：1)建立相关的小鼠模型，研究结核分枝杆菌和HIV/结核分枝杆菌感染的发病机制；2)确定HIV如何改变牛分枝杆菌卡介苗接种人源化小鼠的保护性CMI。这些目的将通过将人胎肝和胸腺组织移植到NOD-SCID/3cnul小鼠，并从相同组织来源的CD34+胎肝细胞静脉注射来实现。艾滋病毒感染引起的结核分枝杆菌病严重程度的差异将通过体内荧光定量(TdTomato Mtb H37Rv)、组织中的病理和细菌载量以及生存情况进行监测。通过对以下几个方面的分析，确定初始接种和卡介苗(热灭活)接种的动物的CMI变化：细胞因子谱；结核分枝杆菌感染部位的白细胞分布和组织；T细胞效应分子的表达；以及CD4+和CD8+T细胞对结核杆菌感染巨噬细胞的体外抗分枝杆菌活性。这项拟议的工作将建立一种艾滋病毒/结核分枝杆菌混合感染的小动物模型，该模型定义了结核分枝杆菌引起的疾病的程度、时间进程和结果。此外，将确定和评估疫苗接种后因艾滋病毒而受损的抗分枝杆菌T细胞功能的具体机制，以防止结核分枝杆菌的攻击。这一混合感染模型将成为发现混合感染和疾病干预的基础生物学的有力研究工具。这一模型的发展意义重大，因为这些结果将提供新的机会来确定艾滋病毒损害对结核分枝杆菌的保护性CMI反应的机制。这一模式系统的积极影响将大大增强设计和筛选创新的结核病预防和治疗方法的能力，以便在免疫系统感染艾滋病毒的人群中使用。 公共卫生相关性：这项拟议的研究与公共卫生相关，因为它将极大地促进我们对艾滋病毒免疫系统调节失调如何促进对结核分枝杆菌易感性的基本理解。这些研究的结果将使人们能够在知情的情况下指导疫苗和治疗方法的开发，以保护艾滋病毒阳性患者免受结核病的侵袭。

DESCRIPTION (provided by applicant): Human immunodeficiency virus (HIV) infection is driving the re-emergence of opportunistic tuberculosis (TB) as a global health emergency, and is strongly associated with the development of multi- or extensively- drug resistant TB (MDR-, XDR-TB). Currently there are no animal models to study HIV/Mtb co-infection due to the human host tropism of HIV. The BLT humanized mouse model is being rapidly applied to study several pathogens where suitable animal models are deficient, including HIV, malaria, and HIV/HCV co-infection. The objective of this proposal is to develop a small animal model of HIV/Mtb co-infection in the humanized mouse for immunological studies critical to Mtb vaccine development. The central hypothesis is that HIV infection will increase the pathogenesis of Mtb and compromise vaccine-induced cell-mediated immunity to Mtb in a humanized mouse model of HIV/Mtb co-infection. The rationale for the proposed research is that a small animal model of human HIV/Mtb co-infection would greatly enhance progress towards understanding these and other mechanisms whereby HIV suppresses CMI to Mtb and accelerate design and screening of TB vaccines for HIV+ populations. The specific aims to test this central hypothesis are 1) To develop a relevant mouse model to study the pathogenesis of Mtb and HIV/Mtb infection and 2) To determine how HIV alters protective CMI to Mtb in M. bovis BCG-vaccinated, humanized mice. These aims will be accomplished by using the NOD-SCID/3cnull mouse engrafted with human fetal liver and thymic tissue, and injected intravenously with CD34+ fetal liver cells from the same tissue source. Differences in Mtb disease severity due to HIV infection will be monitored by in vivo fluorescent quantification (tdTomato Mtb H37Rv), pathology and bacterial load in tissues, and survival. Alterations in CMI in naive and BCG (heat-inactivated)-vaccinated animals due to HIV will be determined by analysis of: cytokine profiles; leukocyte distribution and organization, and T cell effector molecule expression, at sites of Mtb infection; and ex vivo antimycobacterial activity of CD4+ and CD8+ T cells against Mtb-infected macrophages. The proposed work will establish a small animal model of HIV/Mtb co-infection with a defined magnitude, time course, and outcome of disease due to Mtb. Further, specific mechanisms of post-vaccination antimycobacterial T cell function that are impaired by HIV will be identified and assessed relative to protection from Mtb challenge. This co-infection model will be a powerful research tool for discoveries in the basic biology of co-infection and disease intervention. Development of this model is significant, as these results will provide new opportunities to identify the mechanisms whereby HIV compromises the protective CMI response to Mtb. The positive impact of this model system will be greatly enhanced capabilities to design and screen innovative prophylactics and therapeutics for TB to use in populations with HIV-compromised immune systems. PUBLIC HEALTH RELEVANCE: The proposed research is relevant to public health because it will significantly advance our fundamental understanding of how HIV dysregulation of the immune system promotes the susceptibility to Mycobacterium tuberculosis. The results of these studies will enable informed guidance for the development of vaccines and therapeutics to protect HIV+ patients from tuberculosis.