HIV Latency, Epigenetics, and Therapeutics

描述（由申请人提供）：逆转录病毒基因组整合到宿主染色质中，使HIV在感染细胞内持续存在。终身治疗的困难使得必须了解艾滋病毒持续感染的机制，制定克服潜伏性艾滋病毒感染的策略。组蛋白修饰酶在前病毒潜伏期中起关键作用，组蛋白去乙酰化酶（HDAC）抑制剂诱导HIV启动子和病毒表达。滥用药物，特别是可卡因，可以通过表观遗传修饰改变细胞功能。这种环境影响对记忆T细胞和持续HIV感染的持久的表观遗传效应尚未探索。需要更全面地了解表观遗传学如何调节HIV前病毒静止，以及暴露于可卡因是否会改变潜伏感染。为了实现这一点，我们将使用转化的和原代细胞模型的潜伏期，和潜伏感染的细胞从患者，包括患者的可卡因暴露史，全面评估以下假设。具体目标一：选择的HDAC被特异性地募集以作用于HIV启动子，并且靶向HDAC抑制诱导静止前病毒HIV的表达：辅因子复合物募集HDAC 1、2和3以作用于HIV LTR，其中HDAC同种型占据被自动调节。阻断所选HDAC的功能可以诱导模型系统中的潜伏前病毒表达，并允许病毒从HIV感染的ART治疗患者的静息CD4+ T细胞中恢复。具体目标二：组蛋白去乙酰化是在沉默的LTR上建立限制性染色质结构的早期步骤：组蛋白去乙酰化后的一系列广泛的染色质修饰，包括组蛋白甲基化，导致从“诱导”到“锁定”状态的转变，降低HIV启动子对单一诱导信号的响应性。具体目标三：可卡因的使用将改变潜伏感染细胞的群体，降低它们对诱导信号的反应：通过诱导静息CD4+ T细胞中的组蛋白乙酰化，可卡因暴露将减少对HDAC抑制剂有反应的处于“诱导状态”的潜伏感染细胞的数量。对HIV感染者前病毒静止期的表观遗传学和调节的详细研究，包括滥用药物对潜伏性HIV感染的影响，将增强我们对持续性HIV感染的理解。这些研究将指导治疗方法的发展，以破坏持续性前病毒感染，并确保这些方法适用于广泛的患者群体。公共卫生相关性：高活性抗逆转录病毒疗法（ART）已经导致HIV感染个体的发病率和死亡率显著降低，但是从HIV感染个体中根除病毒仍然是遥远的前景，这主要是由于HIV在静息的CD 4 + T淋巴细胞中建立潜伏期的能力。为了克服艾滋病毒在广大受感染人群中的潜伏期，还必须评估环境暴露（如滥用药物）对艾滋病毒持续感染的影响。因此，需要更详细地了解持续感染背后的表观遗传机制。

DESCRIPTION (provided by applicant): The integration of retroviral genomes into host chromatin allows HIV to persist within infected cells. The difficulties of lifelong therapy make it imperative to understand the mechanisms of persistent HIV infection, to devise strategies to overcome latent HIV infection. Histone modifying enzymes play a critical role in proviral latency, and histone deacetylase (HDAC) inhibitors induce HIV promoter and viral expression. Drugs of abuse, most notably cocaine, can alter cellular function via epigenetic modification. The durable, epigenetic effect of such environmental influences on memory T cells and persistent HIV infection is unexplored. A more complete understanding of how epigenetics modulate HIV proviral quiescence, and whether latent infection is altered by exposure to cocaine is needed. To achieve this we will comprehensively evaluate the following hypotheses using transformed and primary cell models of latency, and latently infected cells obtained from patients, including patients with a history of cocaine exposure. Specific Aim I: Selected HDACs are specifically recruited to act at the HIV promoter, and targeted HDAC inhibition induces the expression of quiescent proviral HIV: Cofactor complexes recruit HDACs 1, 2, and 3 to act on the HIV LTR, where HDAC isoform occupancy is autoregulated. Blockade of the function of selected HDACs can induce latent proviral expression in model systems, and allow viral recovery from the resting CD4+ T cells of HIV-infected, ART-treated patients. Specific Aim II: Histone deacetylation is an early step in the establishment of restrictive chromatin structures on the silenced LTR: An extensive series of chromatin modifications following histone deacetylation, including histone methylation, results in transition from the "inducible" to the "locked" state, decreasing responsiveness of the HIV promoter to single inductive signals. Specific Aim III: Cocaine use will alter the population of latently infected cells, reducing their response to inductive signals: By inducing histone acetylation in resting CD4+ T cells, cocaine exposure will reduce the number of latently infected cells in the "inducible state" responsive to HDAC inhibitors. Detailed studies of the epigenetics and regulation of proviral quiescence in HIV-infected patients, including the effects of drugs of abuse on latent HIV infection, will enhance our understanding of persistent HIV infection. These studies will guide the development of therapeutic approaches to disrupt persistent proviral infection, and insure that such approaches are applicable to broad populations of patients. PUBLIC HEALTH RELEVANCE: Highly active antiretroviral therapy (ART) has lead to a significant decrease in the morbidity and mortality of HIV-infected individuals, but eradication of virus from HIV-infected individuals remains a distant prospect due largely to the ability of HIV to establish latency in resting CD4+ T-lymphocytes. To overcome HIV latency in a broad population of infected individuals, it is also important to assess the effect of environmental exposures, such as those to drugs of abuse, on persistent HIV infection. Therefore a more detailed understanding is needed of the epigenetic mechanisms behind persistent infection.