Targeting PI3K/Akt Cell Survival Pathway as a Novel Anti-HIV Therapy

描述(申请人提供)：在整个发病机制中，可以观察到组织巨噬细胞和中枢神经系统小胶质细胞的持续HIV-1感染，这些细胞类型被认为是感染患者长期存活的关键细胞。我们最近观察到，感染M嗜性HIV-1的人原代巨噬细胞在细胞损伤时显示出极大的存活能力。考虑到HIV-1感染引起的各种细胞毒性环境，在CNS模型中得到了很好的解释，这是一个合乎逻辑的推测，HIV-1可能已经进化为在巨噬细胞和小胶质细胞库中对HIV-1诱导的细胞毒性损伤表现出自我保护反应，并实现了这些HIV-1感染细胞类型的长期存活和HIV-1的持续产生。然而，导致HIV-1感染的未分裂靶细胞这种延长存活表型的病毒因素以及参与这种长期生存表型的细胞机制从未被设想过。由于人类原代小胶质细胞的可获得性有限，我们最近建立了一种人小胶质细胞系，该细胞系在HIV-1感染后也显示出极大的增强的生存能力。这个模型系统使我们能够揭示HIV-1诱导细胞存活的机制和细胞内TAT作为导致HIV-1细胞保护表型的关键病毒因素。我们的初步数据还表明，特征明确的PI3K/Akt生存通路可能参与了HIV-1感染和细胞内Tat表达的细胞保护作用。利用我们的模型系统以及原代人巨噬细胞，我们鉴定了几个受Tat表达调控的关键宿主因子，这将指导我们准确地定位细胞内HIV-1Tat引发的细胞保护作用机制。更有趣的是，利用几种已被开发为抗癌药物的PI3K/Akt抑制剂，我们揭示了PI3K/Akt途径的抑制可以导致HIV-1感染的巨噬细胞的长期存活表型的丧失，最终抑制感染的巨噬细胞产生HIV-1。在这个建议中，我们试图1)了解HIV-1感染在原代人类巨噬细胞和小胶质细胞中的细胞保护作用的细胞机制和宿主/病毒因素，以及2)通过特异性地根除巨噬细胞和小胶质细胞HIV-1储存库来测试PI3K/Akt抑制剂的抗HIV效果。这项拟议的工作将有助于了解HIV-1感染的巨噬细胞和小胶质细胞长期存活的分子和细胞机制，以及HIV-1感染患者体内HIV-1储存库的建立。这项研究的目标是开发新的战略，专门根除长期存活的艾滋病毒-1宿主。公共卫生相关性：HIV-1在组织巨噬细胞和中枢神经系统储存库中的长期感染会导致持续的病毒产生和临床并发症，如HIV-1相关性痴呆。由于缺乏抗病毒治疗来抑制已经被感染的长期存活的艾滋病毒-1宿主的病毒产生，从艾滋病毒-1宿主发起的病毒传播目前已经失控。这项应用建议确定新的抗病毒策略，以专门根除长期存活的HIV-1宿主，从而将HIV-1感染患者的持续病毒生产和感染降至最低。

DESCRIPTION (provided by applicant): Persistent HIV-1 infection of tissue macrophage and CNS microglia can be observed throughout pathogenesis, and these cell types have been considered as key long-living HIV-1 reservoirs in the infected patients. We recently observed that human primary macrophages infected with M-tropic HIV-1 display a greatly elevated survival capability upon cellular insults. Considering the various cytotoxic environments caused by HIV-1 infection, which are well explained in the CNS model, it is a logical speculation that HIV-1 may have evolved to display self-protective responses in macrophage and microglia reservoirs against the HIV-1 induced cytotoxic insults and to achieve the long term survival of these HIV-1 infected cell types and persistent HIV-1 production. However, the viral factors responsible for this extended survival phenotype of HIV-1 infected non-dividing target cells and the cellular mechanisms involved in this long-term survival phenotype have never been envisioned. Due to the limited access of human primary microglia, we have recently established a human microglial cell line system that also displays the greatly enhanced survival capability upon HIV-1 infection. This model system enabled us to reveal both the mechanisms underlying HIV-1 induced cell survival and intracellular Tat as a key viral factor responsible for the cytoprotective phenotype of HIV-1. Our preliminary data also suggest that the well characterized PI3K/Akt survival pathway is mechanistically involved in the cytoprotective effect of HIV-1 infection and intracellular Tat expression. Using our model system as well as primary human macrophages, we identified several key host factors regulated by Tat expression, which will guide us in pinpointing the cytoprotective mechanism of action elicited by intracellular HIV-1 Tat. More interestingly, employing several PI3K/Akt inhibitors, which had been developed as anti-cancer agents, we revealed that the inhibition of the PI3K/Akt pathway can lead to the abolishment of the long-term survival phenotype of HIV-1 infected macrophages and eventually to the inhibition of HIV-1 production from the infected macrophages. In this proposal, we seek to 1) understand the cellular mechanisms and host/viral factors involved in the cytoprotective effect of HIV-1 infection in primary human macrophages and microglia, and 2) test the anti-HIV effect of the PI3K/Akt inhibitors by specifically eradicating macrophages and microglia HIV-1 reservoirs. This proposed work will shed light on understanding the molecular and cellular mechanisms involved in the long term survival of HIV-1 infected macrophage and microglia and the establishment of the HIV-1 reservoirs in the infected patients. The goal of the research is to develop new strategies to specifically eradicate the long- living HIV-1 reservoirs. PUBLIC HEALTH RELEVANCE: Long term infection of HIV-1 in tissue macrophage and central nerve system reservoirs leads to persistent viral production and clinical complications such as HIV-1 associated dementia. Due to lack of antiviral therapy inhibiting viral production from long-living HIV-1 reservoirs that have been already infected, the viral spreading initiated from the HIV-1 reservoirs is currently beyond control. This application proposes to identify new antiviral strategies to specifically eradicate long-living HIV-1 reservoirs, which can minimize persistent viral production and infection in the HIV-1 infected patients.