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，这些细胞类型被认为是感染患者中关键的长期HIV-1储存库。我们最近观察到，感染了嗜m型HIV-1的人原代巨噬细胞在细胞损伤时表现出极大的生存能力。考虑到由HIV-1感染引起的各种细胞毒性环境，这在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可能已经进化到在巨噬细胞和小胶质细胞库中显示自我保护反应，以抵抗HIV-1诱导的细胞毒性损伤，并实现这些HIV-1感染细胞类型的长期存活和持续的HIV-1生产。然而，导致HIV-1感染的非分裂靶细胞延长生存表型的病毒因子和参与这种长期生存表型的细胞机制从未被设想过。由于人类初级小胶质细胞的途径有限，我们最近建立了一个人类小胶质细胞系系统，该系统在HIV-1感染后也显示出极大增强的生存能力。该模型系统使我们能够揭示HIV-1诱导细胞存活的机制和细胞内Tat作为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，PI3K/Akt存活通路在机制上参与了HIV-1感染和细胞内Tat表达的细胞保护作用。利用我们的模型系统和原代人巨噬细胞，我们确定了几个受Tat表达调节的关键宿主因子，这将指导我们确定细胞内HIV-1 Tat引发的细胞保护机制。更有趣的是，通过使用几种PI3K/Akt抑制剂（已被开发为抗癌药物），我们发现抑制PI3K/Akt通路可导致HIV-1感染巨噬细胞的长期存活表型的消除，并最终抑制感染巨噬细胞的HIV-1产生。在本研究中，我们寻求1)了解参与HIV-1感染在人原代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)通过特异性根除巨噬细胞和小胶质细胞中的HIV-1储存库来测试PI3K/Akt抑制剂的抗hiv作用。这项工作将有助于理解HIV-1感染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库在感染患者体内的建立。这项研究的目标是开发新的策略来专门根除长期存在的HIV-1储存库。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的长期感染导致持续的病毒产生和临床并发症，如HIV-1相关痴呆。由于缺乏抗病毒治疗来抑制已经感染的长期HIV-1储存库的病毒产生，从HIV-1储存库开始的病毒传播目前已无法控制。该应用程序提出了确定新的抗病毒策略，以特异性根除长期存在的HIV-1储存库，这可以最大限度地减少HIV-1感染患者的持续病毒产生和感染。

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.