Immunoregulatory networks and HIV pathogenesis

描述（由申请人提供）：联合抗逆转录病毒疗法（ART）已导致HIV感染的发病率和死亡率大幅下降。然而，一旦治疗中断，ART不能根除病毒或恢复能够控制病毒复制的HIV特异性免疫应答。开发能够产生免疫反应的干预措施，能够在停止ART后维持HIV抑制，并提高候选疫苗的有效性，这将是一个至关重要的临床进展。有证据表明，有效的HIV特异性CD 4 T细胞将需要实现这一目标，但这些细胞仍然严重不足。尽管延长了抗逆转录病毒疗法，但缺乏有效的HIV特异性CD 4辅助性T细胞反应的恢复，这增加了这些反应不可逆地受损的可能性。然而，我们在这项资助的前四年中产生的结果支持了一个惊人的结论：HIV感染中的CD 4 T细胞损伤在很大程度上受到控制。 抑制机制，可以通过操纵调控网络恢复。数据表明，这些途径之一PD-1在维持HIV储库中也起着重要作用，使其成为非常有吸引力的治疗靶点。在这一竞争性更新中，我们建议在最初资助期间取得的主要进展的基础上，利用细胞生物学、分子免疫学和先进细胞成像的综合方法，查明调节有效和无效的HIV特异性CD 4 T细胞应答的关键事件。 我们还建议调查HIV研究的另一个被忽视的领域：无效的HIV特异性CD 4 T细胞应答对抗原呈递细胞功能的影响。在目标1中，我们将确定功能性和耗尽的HIV特异性CD 4 T细胞的关键基因特征。我们将确定在HIV特异性CD 4 T细胞中由PD-1调节的主要转录因子，并确定它们在控制耗尽的CD 4 T细胞功能中的作用。我们将通过在原代细胞中过表达或沉默这些主基因来研究HIV特异性CD 4 T细胞功能可塑性的潜力。在目标2中，我们将使用先进的活体成像来确定由功能性和耗尽的HIV特异性CD 4 T细胞建立的免疫突触的动力学。我们将定义单个共抑制剂的作用，并确定优化的共刺激信号传导是否可以防止这种有缺陷的突触形成和功能。在目标3中，我们将定义HIV特异性CD 4 T细胞许可抗原呈递细胞的特定缺陷，以及APC损伤的特定机制。我们将确定APC是否对刺激信号产生不适当的反应。通过选择性阻断功能失调的CD 4 T细胞表达的分子，我们将确定APC功能紊乱中因果相关的事件。我们还将定义调控途径之间的相互作用如何导致所观察到的缺陷。该提案将提供对保护性和无效的HIV特异性CD 4 T细胞之间功能差异的分子基础的新理解，并将确定新的治疗靶点，以在ART治疗和未感染者中产生有效的HIV特异性免疫。

DESCRIPTION (provided by applicant): Combination antiretroviral therapy (ART) has resulted in a major decrease in morbidity and mortality in HIV- infection. However, ART does not eradicate virus or restore HIV-specific immune responses capable of controlling viral replication once therapy is interrupted. Development of interventions that could generate immune responses capable of maintaining HIV suppression after cessation of ART and improve efficacy of vaccine candidates would be a crucial clinical advance. Evidence suggests that effective HIV-specific CD4 T cells will be required to achieve this goal, yet these cells remain seriously understudied. The lack of restoration of effective HIV-specific CD4 T helper responses in spite of extended ART raised the possibility that these responses are irreversibly crippled. However, the results we have generated during the first four years of this grant support a striking conclusion: that CD4 T cell impairment in HIV-infection is to a significant extent under control of inhibitory mechanisms that can be reverted by manipulation of regulatory networks. Data suggest that one of these pathways, PD-1, also plays an important role in the maintenance of HIV reservoirs, making it a very attractive therapeutic target. In this competing renewal we propose to build on the major progress made during the initial funding period and to utilize combined approaches of cellular biology, molecular immunology and advanced cell imaging to pinpoint critical events that regulate effective and inefficient HIV-specific CD4 T cell responses. We also propose to investigate another neglected area of HIV-research: the impact that ineffective HIV-specific CD4 T cell responses have on antigen-presenting cell functions. In Aim 1, we will identify critical gene signatures of functional and exhausted HIV-specific CD4 T cells. We will determine the master transcription factors that are regulated by PD-1 in HIV-specific CD4 T cells and define their role in the control of exhausted CD4 T cell functions. We will examine the potential for HIV-specific CD4 T cell functional plasticity by overexpressing or silencing these master genes in primary cells. In Aim 2 we will use advanced live imaging to determine the dynamics of immunological synapses built by functional and exhausted HIV- specific CD4 T cells. We will define the role of individual co-inhibitors and determine whether optimized co- stimulatory signaling can prevent this defective synapse formation and function. In Aim 3 we will define specific defects in licensing of antigen-presenting cells by HIV-specific CD4 T cells, and specific mechanisms of APC impairment. We will determine whether APC present inappropriate responses to stimulatory signals. By selectively blocking molecules expressed by dysfunctional CD4 T cells, we will determine events causally involved in the perturbation of APC functions. We will also define how the interplay between regulatory pathways leads to the observed defects. This proposal will provide novel understanding of the molecular basis for functional differences between protective and ineffective HIV-specific CD4 T cells and will identify new therapeutic targets to generate effective HIV-specific immunity in ART-treated and uninfected persons.