ANERGY & APOPTOSIS--ROLE & MECHANISM IN HIV PATHOGENESIS

在感染HIV期间，CD4有明显的选择性下降。 与进行性免疫缺陷有关的T细胞。这个 HIV感染导致CD4T细胞耗竭的机制(S) 辩论过了。尽管最近的数据表明中国的病毒载量较高 循环和淋巴器官中以前 即使在疾病的早期阶段，也会欣赏来自模型的最新数据 用人类淋巴样细胞重建SCID小鼠也认为 直接病毒感染和细胞病变不能解释所有 CD4T细胞死亡。此外，黑猩猩能够维持 体内慢性艾滋病毒感染和体外细胞病变感染， 但不会发展为获得性免疫缺陷综合征(艾滋病)， 表明其他直接摧毁病毒的机制有助于 导致CD4T细胞丧失。我们已经证明了CD4On的交联性 人CD4T细胞通过T细胞受体传递信号 抗原通过细胞凋亡导致激活诱导的细胞死亡。这些 结果表明，艾滋病患者体内大量的CD4T细胞耗尽是一种机制。 尤其是在面临同时感染和抗原挑战的情况下 和其他生物体一起。HIV中T细胞死亡机制的证据 感染来自几个群体，包括我们自己，他们已经表明 HIV感染者的CD4(在某些情况下还包括CD8)T细胞 在培养中激活时会发生细胞凋亡。这里面的实验 提案的目的是同时研究 艾滋病中的细胞凋亡。在目标1中，我们建议在体外确认我们的 活体观察，并确定激活是否诱导细胞凋亡 在发展为艾滋病的过程中起着重要作用。我们的体内研究将利用 来自人类和非人类灵长类动物的HIV或SIV感染组织 原位鉴定凋亡细胞，并确定是否有更多的细胞 细胞的凋亡性比感染病毒的效率要高。进步将会 通过对患者细胞的纵向和横断面研究进行研究 和血清，以便将细胞凋亡与疾病分期和通过 灵长类动物模型中细胞凋亡的分析 类似艾滋病的疾病。在目标2中，我们将研究CD4的机制 为艾滋病患者的细胞凋亡做准备。我们将确定通过哪些方式 在HIV感染中，凋亡启动信号被传递到CD4T细胞， 对这种信号敏感的细胞，动力学和 这一信号的传播，以及特定的激酶和 启动事件中的磷酸酶。 这些实验将使用HIV感染者和非感染者的PBL 成人和儿童，淋巴组织来自感染和未感染 人类和非人类灵长类动物、T细胞系和人类CD4转基因小鼠 结合了许多实验方法，包括流动 DNA片段化和蛋白质的细胞学和生化分析 激酶和磷酸酶的激活。 拟议的研究将调查细胞凋亡的一系列方面 艾滋病，从其临床意义到分子机制。我们的终极 目标是开发针对艾滋病毒感染者的治疗干预措施 个人，以防止发展为艾滋病。理想情况下，这是 将允许抗病毒疗法消除病毒感染，而 疾病已经被控制住了。

During HIV infection there is a profound and selective decrease in CD4 T cells which is associated with progressive immunodeficiency. The mechanism(s) by which HIV infection lead to CD4 T cell depletion are debated. Although recent data gives evidence for a higher viral load in the circulation and in lymphoid organs that had been previously appreciated, even at early stages of disease, recent data from a model reconstituting the SCID mouse with human lymphoid cells also argue that direct viral infection and cytopathicity cannot account for all of the CD4 T cell death. In addition, the fact that chimpanzee can sustain a chronic infection with HIV in vivo, and c cytopathic infection in vitro, but does not progress to acquired immune deficiency syndrome (AIDS), suggests that mechanisms other that direct viral destruction contribute to CD4 T cell loss. We have demonstrated that crosslinking of CD4 on human CD4 T cells followed by signaling through the T cell receptor for antigen results in activation-induced cell death by apoptosis. These results suggest a mechanism for the massive CD4 T cell depletion in AIDS, particularly in the face of concurrent infection and antigenic challenge with other organisms. Evidence for this mechanism of T cell death in HIV infection has come from several groups, including our own, who have shown that CD4 (and in some cases CD8) T cells from HIV-infected individuals undergo apoptosis upon activation in culture. The experiments in this proposal are designed to investigate both the mechanism and role of apoptosis in AIDS. In Aim 1, we propose to confirm our in vitro observations in vivo, and to determine if activation-induced apoptosis plays a role in progression to AIDS. Our in vivo studies will make use of HIV- or SIV-infected tissue from humans and from nonhuman primates to identify apoptotic cells in situ and to determine whether more cells are apoptotic than are productively infected with virus. Progression will be studied by longitudinal and cross-sectional studies of patient cells and serum in order to correlate apoptosis with disease stage and by analysis of apoptosis in primate models which do or do not progress to AIDS-like disease. In Aim 2, we will investigate the mechanism of CD4 priming for apoptosis in AIDS. We will identify the means by which the apoptotic priming signal is delivered to the CD4 T cell in HIV infection, the cell which is susceptible to this signal, the kinetics and propagation of this signal, and the role of specific kinases and phosphatases in the priming event. These experiments will employ PBL's from HIV-infected and uninfected adults and children, lymph node tissue from infected and uninfected humans and nonhuman primates, T cell lines, and human CD4 transgenic mice in conjunction with a number of experimental methods including flow cytometry and biochemical analysis of DNA fragmentation, and protein kinase and phosphatase activation. The proposed studies will investigate a range of aspects of apoptosis in AIDS, from its clinical relevance to molecular mechanisms. Our ultimate goal is the development of therapeutic interventions for HIV-infected individuals, in order to prevent progression to AIDS. Ideally, this would allow anti-viral therapies to eliminate viral infection, while the disease is held at bay.