The role of TFAM alterations in HIV- and ART-induced mitochondrial dysfunction in the brain

摘要 全世界有超过3700万人感染艾滋病毒，多达50%的人受到某种形式的 神经功能障碍。尽管有效的抗逆转录病毒疗法(ART)，减少发病率的治疗 缺乏艾滋病毒相关的神经认知障碍(HAND)。最近的研究结果表明， 反应性星形胶质细胞中的线粒体活性在神经元线粒体功能障碍中起着因果作用，这可能 是HIV病毒抑制患者(PWH)神经元功能障碍的靶向机制。早些时候 在艾滋病毒感染期间，感染艾滋病毒的单核细胞进入大脑，将感染传播到常驻的小胶质细胞，然后 释放HIV、HIV蛋白和炎性细胞因子，所有这些都刺激炎症表型 星形星云。反应性星形胶质细胞是陈旧性脑出血死后脑组织的一个特征，即使在 压抑艺术。星形胶质细胞具有许多稳态功能，这些功能可能会被慢性低水平星形胶质细胞破坏 艾滋病毒感染和长期接触抗逆转录病毒药物。星形胶质细胞的一个这样的功能是缓冲 可供细胞外空间的神经元使用的代谢底物(葡萄糖、乳酸和谷氨酰胺)。尽管 这一维持大脑中生物能量平衡的关键功能和良好记录的证据表明 在手部过程中，生物能量缺乏，关于这些过程如何在反应性星形胶质细胞中受到影响，人们知之甚少。 我们最近发现，HIV和ART刺激星形胶质细胞从最初的糖酵解和 分泌副产物乳酸，以依赖氧化磷酸化来满足能量需求。要实现 这种线粒体活性增加，反应性星形胶质细胞增加了线粒体生物发生因子的水平 (TFAM)，这与TFAM的表达减少和神经元的存活有关。重要的是，这 神经毒性可被抗炎化合物阻断，这些化合物可抑制线粒体的活动并减少 反应性星形胶质细胞的反应性表型。然而，线粒体活性增加之间的机制联系 在反应性星形胶质细胞中，线粒体生物发生的减少在神经元中还不清楚。我们会 通过检验增加线粒体的假说来研究星形胶质细胞代谢在手部的作用 反应性星形胶质细胞的活动损害了近端神经元的线粒体功能。AIM 1将在 人脑细胞TFAM基因敲除改变线粒体活性及反应性神经毒性 星形星云。Aim 2将在有和没有手和HIV对照组的PWH死后脑组织中进行研究 反应性线粒体生物发生、动力学因素及乳酸转运体的定位和变化 星形胶质细胞和神经元。在AIM 3中，暴露于HIV蛋白gp120和抗逆转录病毒药物的小鼠大脑将被用于 研究星形胶质细胞和神经元中线粒体的生物发生和动力学因素以及乳酸转运体。 这些目标涉及艾滋病研究办公室的优先事项：1)处理与艾滋病毒有关的合并症；2) 推进基础科学和行为科学的交叉研究领域。

SUMMARY Over 37 million people worldwide are infected with HIV and as many as 50% are affected by some form of neurological dysfunction. Despite effective antiretroviral therapy (ART), treatments to reduce the prevalence of HIV-associated neurocognitive disorder (HAND) are lacking. Recent findings suggest that increased mitochondrial activity in reactive astroglia play a causal role in mitochondrial dysfunction in neurons and this may be a targetable mechanism underlying neuronal dysfunction in virally suppressed people with HIV (PWH). Early during HIV infection, HIV-infected monocytes enter the brain and spread infection to resident microglia that then release HIV, HIV proteins, and inflammatory cytokines, all of which stimulate a proinflammatory phenotype in astroglia. Reactive astroglia are a hallmark of postmortem brain tissues from PWH with HAND even when on suppressive ART. Astroglia have many homeostatic functions, which are likely disrupted by chronic low-level HIV infection and long-term exposure to ART. One such function of astroglia is to buffer the concentrations of metabolic substrates (glucose, lactate, and glutamine) available to neurons in the extracellular space. Despite this crucial function to maintain bioenergetic homeostasis in the brain and the well-documented evidence of bioenergetic deficits during HAND, little is known about how these processes are affected in reactive astroglia. We’ve recently discovered that HIV and ART stimulate a switch in astroglia from being primarily glycolytic and secreting the byproduct lactate, to relying on oxidative phosphorylation to meet energy demands. To achieve this increase in mitochondrial activity, reactive astroglia increase levels of the mitochondrial biogenesis factors (TFAM), which is associated with a reduction in TFAM expression and viability in neurons. Importantly, this neurotoxicity is blocked by anti-inflammatory compounds that inhibit mitochondrial activity and reduce the reactive phenotype of reactive astroglia. However, the mechanistic link between increased mitochondrial activity in reactive astroglia and the reduction in mitochondrial biogenesis in neurons is not understood. We will investigate the role of astroglial metabolism in HAND by testing the hypothesis that increased mitochondrial activity in reactive astroglia compromises mitochondrial function in proximal neurons. AIM 1 will test in human brain cells how TFAM knockdown alters mitochondrial activity in and neurotoxicity conferred by reactive astroglia. AIM 2 will investigate in postmortem brain tissues from PWH with and without HAND and HIV- controls the location and changes in mitochondrial biogenesis and dynamics factors and lactate transporters in reactive astroglia and neurons. In AIM 3, mouse brains exposed to the HIV protein gp120 and ART drugs will be used to investigate mitochondrial biogenesis and dynamics factors and lactate transporters in astroglia and neurons. These AIMs address the Office of AIDS Research Priorities to 1) Address HIV-Associated Comorbidities; and 2) Advance Cross-Cutting Areas of research in the basic and behavioral sciences.