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

描述（由申请人提供）：在整个发病过程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，并且这些细胞类型已被认为是感染患者体内关键的长期存活的 HIV-1 储存库。我们最近观察到，感染 M-tropic HIV-1 的人类原代巨噬细胞在细胞损伤后表现出大大提高的生存能力。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），可以合理地推测，HIV-1 可能已经进化到在巨噬细胞和小胶质细胞库中表现出针对 HIV-1 诱导的细胞毒性损伤的自我保护反应，并实现这些 HIV-1 感染细胞类型的长期存活和持续的 HIV-1 产生。然而，从未设想过导致HIV-1感染的非分裂靶细胞的这种延长存活表型的病毒因素以及涉及这种长期存活表型的细胞机制。由于人类原代小胶质细胞的获取有限，我们最近建立了人类小胶质细胞系系统，该系统也显示出在HIV-1感染后大大增强的生存能力。该模型系统使我们能够揭示 HIV-1 诱导细胞存活的机制以及细胞内 Tat 作为负责 HIV-1 细胞保护表型的关键病毒因子。我们的初步数据还表明，已明确表征的 PI3K/Akt 存活途径在机制上参与了 HIV-1 感染和细胞内 Tat 表达的细胞保护作用。使用我们的模型系统以及原代人类巨噬细胞，我们确定了受 Tat 表达调节的几个关键宿主因子，这将指导我们查明细胞内 HIV-1 Tat 引起的细胞保护作用机制。更有趣的是，使用几种已开发为抗癌药物的 PI3K/Akt 抑制剂，我们发现，抑制 PI3K/Akt 通路可以导致消除 HIV-1 感染巨噬细胞的长期存活表型，并最终抑制受感染巨噬细胞产生 HIV-1。在本提案中，我们寻求 1) 了解 HIV-1 感染对原代人类巨噬细胞和小胶质细胞的细胞保护作用所涉及的细胞机制和宿主/病毒因素，以及 2) 通过特异性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的长期存活以及感染患者体内 HIV-1 储存库的建立所涉及的分子和细胞机制。该研究的目标是制定新策略来专门根除长期存活的 HIV-1 病毒库。公共卫生相关性：组织巨噬细胞和中枢神经系统储存库中 HIV-1 的长期感染会导致病毒持续产生和临床并发症，例如 HIV-1 相关痴呆。由于缺乏抗病毒治疗来抑制已感染的长期存活的 HIV-1 病毒库的病毒产生，因此 HIV-1 病毒库引发的病毒传播目前无法控制。该申请旨在确定新的抗病毒策略，以专门根除长期存活的 HIV-1 病毒库，从而最大限度地减少 HIV-1 感染患者体内持续的病毒产生和感染。

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.