Project 4

项目摘要 HIV-1感染是一个主要的全球健康问题。尽管有效的联合抗逆转录病毒疗法已经 延长HIV-1感染者的寿命，HIV-1感染对大脑的损害持续存在。HIV-1 感染者现在正在经历HIV-1相关的神经认知障碍(HAND)， 在美国，这一比例超过50%。虽然对那些受影响的人来说是广泛的和毁灭性的，但其发病机制 手部情况仍不明朗。有趣的是，手的病理与HIV-1病毒载量并不成正比，而HIV-1病毒 不会感染神经元。因此，神经毒性效应被认为是由HIV-1病毒蛋白和 炎症反应。在HIV-1病毒蛋白中，HIV-1转录反式激活因子(HIV-1 Tat) 仍然被认为是手部疾病的病因；我们和其他人 一贯表明，HIV-1TAT可诱导小胶质细胞介导的神经炎症、突触破坏和 神经毒性，但潜在的机制仍然难以捉摸。这里的目标是确定一部小说 HIV-1Tat诱导和促进手部发育的内溶酶体依赖机制。 我们的中心假设是，HIV-1Tat破坏了液泡型ATPase的组装，而液泡型ATPase的组装反过来又使 内溶酶体pH，从而导致小胶质细胞功能障碍、突触破坏和神经元损伤，以及 ML-SA1降低内溶酶体pH减轻HIV-1TAT诱导 神经炎症和神经元损伤。在我们的发现的指导下，这一新的假设将通过追求 三个具体目标。(1)剖析HIV-1TAT破坏突触完整性和诱导 原代培养神经元的神经毒性。(2)剖析HIV-1Tat诱导小胶质细胞的机制 原代培养的小胶质细胞功能障碍。(3)在体内确定HIV-1 TAT的诱导机制 神经炎症、突触破坏和神经毒性。我们是第一个表明HIV-1TAT可以提高 内溶酶体pH。我们认为内溶酶体pH升高在小胶质细胞介导的 手部出现神经炎症、突触破坏和神经毒性。我们发现ML-SA1 降低内溶酶体的pH值，从而阻断HIV-1TAT诱导的内溶酶体pH的升高。 因此，这项工作的一个主要目标是确定内溶酶体pH的升高是否对 神经炎症、突触破坏和神经毒性的发展。因此，建议的结果是 这项工作将为手部疾病的发病机制提供重大进展，并可能导致发现 针对手部疾病的新的有效治疗策略，从而减少艾滋病毒-1感染者的痛苦。

Project Summary HIV-1 infection is a major global health problem. Although the effective combined antiretroviral therapy has prolonged the life span of HIV-1 infected individuals, damaging effects of HIV-1 infection persist in brain. HIV-1 infected people are now experiencing HIV-1 associated neurocognitive disorders (HAND), the prevalence of which is over 50% in the USA. Although widespread and devastating to those affected, the pathogenesis of HAND remains unclear. Interestingly, HAND pathology is not proportional to HIV-1 viral load, and HIV-1 virus does not infect neurons. Thus, neurotoxic effects are deemed to be resulted from HIV-1 viral proteins and inflammatory responses. Among HIV-1 viral proteins, HIV-1 transactivator of transcription (HIV-1 Tat) continues to be implicated as a causative factor in the pathogenesis of HAND; We and others have consistently shown that HIV-1 Tat induces microglia-mediated neuroinflammation, synaptic disruption, and neurotoxicity, but the underlying mechanisms are still elusive. The objective here is to determine a novel endolysosome-dependent mechanism whereby HIV-1 Tat elicits and contributes to the development of HAND. Our central hypothesis is that HIV-1 Tat disrupts the assembly of vacuolar ATPase, which in turn, elevates endolysosome pH, thereby inducing microglia dysfunction, synaptic disruption, and neuronal injury, and that reduction of endolysosome pH with the administration of ML-SA1 attenuates HIV-1 Tat-induced neuroinflammation and neuronal injury. Guided by our findings, this novel hypothesis will be tested by pursuing three specific aims. (1) Dissect mechanisms by which HIV-1 Tat disrupts synaptic integrity and induces neurotoxicity in primary cultured neurons. (2) Dissect mechanisms by which HIV-1 Tat induces microglia dysfunction in primary cultured microglia. (3) Determine, in vivo, mechanisms by which HIV-1 Tat induces neuroinflammation, synaptic disruption, and neurotoxicity. We are the first to show that HIV-1 Tat elevates endolysosome pH. We believe that elevation of endolysosome pH plays a critical role in microglia-mediated neuroinflammation, synaptic disruption and neurotoxicity as occur in HAND. We have discovered that ML-SA1 reduces endolysosome pH, which could then block HIV-1 Tat-induced elevation of endolysosome pH. Therefore, a major goal of this work is to determine if elevation of endolysosome pH is central to the development of neuroinflammation, synaptic disruption, and neurotoxicity. Therefore, results form the proposed work will provide a significant advancement in the pathogenesis of HAND, and may lead to the discovery of new effective therapeutic strategies against HAND and thereby reduce suffering of HIV-1 infected individuals.