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

描述（由申请方提供）：人类免疫缺陷病毒（HIV）感染正在推动机会性结核病（TB）作为全球卫生紧急事件重新出现，并与多重或广泛耐药结核病（MDR-，XDR-TB）的发展密切相关。由于HIV的人类宿主嗜性，目前还没有研究HIV/Mtb共感染的动物模型。BLT人源化小鼠模型正迅速应用于研究几种缺乏合适动物模型的病原体，包括HIV、疟疾和HIV/HCV共感染。本提案的目的是在人源化小鼠中开发HIV/Mtb共感染的小动物模型，用于Mtb疫苗开发的关键免疫学研究。中心假设是HIV感染将增加Mtb的发病机制，并在HIV/Mtb共感染的人源化小鼠模型中损害疫苗诱导的细胞介导的对Mtb的免疫。拟议研究的基本原理是，人类HIV/Mtb共感染的小动物模型将极大地促进对HIV抑制CMI至Mtb的这些和其他机制的理解，并加速HIV+人群结核疫苗的设计和筛选。检验这一中心假设的具体目标是：1）开发相关小鼠模型以研究Mtb和HIV/Mtb感染的发病机制; 2）确定HIV如何改变M中保护性CMI至Mtb。牛BCG疫苗接种的人源化小鼠。这些目标将通过使用移植有人胎肝和胸腺组织的NOD-SCID/3cnull小鼠，并静脉内注射来自相同组织来源的CD 34+胎肝细胞来实现。将通过体内荧光定量（tdTomato Mtb H37 Rv）、组织中的病理学和细菌载量以及存活率来监测HIV感染导致的Mtb疾病严重程度的差异。将通过分析以下因素来确定由HIV引起的未接种和BCG（热灭活）接种动物中CMI的变化：细胞因子谱; Mtb感染部位的白细胞分布和组织以及T细胞效应分子表达;以及CD 4+和CD 8 + T细胞对Mtb感染的巨噬细胞的体外抗分枝杆菌活性。拟议的工作将建立一个HIV/Mtb共感染的小动物模型，确定Mtb引起的疾病的程度、时间进程和结果。此外，将鉴定和评估相对于保护免受Mtb攻击的疫苗接种后抗分枝杆菌T细胞功能被HIV损害的具体机制。这种合并感染模型将成为发现合并感染和疾病干预的基础生物学的有力研究工具。该模型的开发具有重要意义，因为这些结果将提供新的机会来确定HIV损害对Mtb的保护性CMI反应的机制。该模型系统的积极影响将大大增强设计和筛选用于艾滋病毒免疫系统受损人群的结核病创新药物和治疗方法的能力。 公共卫生相关性：这项拟议的研究与公共卫生有关，因为它将大大推进我们对艾滋病毒免疫系统失调如何促进结核分枝杆菌易感性的基本理解。这些研究的结果将为开发疫苗和治疗方法提供知情指导，以保护艾滋病毒阳性患者免受结核病的侵害。

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.