Novel Pathways of HAARTmediated Neuronal Toxicity in the Central Nervous System

尽管在高活性抗逆转录病毒治疗（HAART）时代，艾滋病毒相关性痴呆（HAD）的发病率有所降低，但HAD的患病率正在增加，艾滋病毒阳性患者中轻微认知诊断的频率也在增加。尽管HAART在外周神经系统和培养的神经元中均具有神经毒性，但HAART对HIV相关神经认知障碍的作用尚不清楚。HAART化合物的毒性是由于不同的抗逆转录病毒类依赖性机制，如蛋白质代谢的改变和线粒体损伤诱导的ROS（ROS）的产生，这两者都与其他神经退行性疾病有关。这些机制，以及HAART药物本身，可以启动内质网（ER）应激反应，一种多分支的促生存信号通路，如果长期激活，可能会变得有害，以及自噬，这与神经变性有关。理解不同类别HAART触发的细胞机制 在神经元和巨噬细胞中检测药物的活性，对于指导新药的设计和组合抗逆转录病毒疗法，最大限度地减少神经系统的影响至关重要。我们假设HAART化合物直接和间接地诱导神经元毒性（例如巨噬细胞功能的改变），并且这些机制是由HAART化合物类别之间不同的应激反应的细胞特异性活化介导的。支持这一假设，我们已经观察到，个别抗逆转录病毒药物在中枢神经系统培养的神经毒性和无毒药物，当应用在推荐的HAART组合，成为神经毒性。我们还证明了在患有HIV相关神经认知障碍的患者的神经元和小胶质细胞/巨噬细胞中以及在用HAART化合物治疗后的神经元和单核细胞衍生的巨噬细胞（MDM）培养物中ER应激反应活化的下游指标的增加。基于这些发现，我们建议：1）确定HAART药物类别单独和推荐的治疗组合的直接神经元毒性机制; 2）确定HAART药物类别（单独和组合）在单核细胞衍生的巨噬细胞中的直接毒性机制; 3）确定HAART暴露的MDM对神经毒性的贡献。通过研究中枢神经系统中HAART毒性的细胞特异性机制，我们将揭示HIV阳性患者认知障碍的未探索来源，确定有效控制病毒复制的HAART化合物减轻副作用的靶点，并创建检测当前和未来HAART化合物单独和组合的神经毒性的模型。

Despite a reduction in the incidence of HIV-associated dementia (HAD) in the era of Highly Active Anti-Retroviral Therapy (HAART), the prevalence of HAD is increasing, as is the frequency of minor cognitive diagnoses in HIV-positive patients. Although HAART is neurotoxic in both the peripheral nervous system and cultured neurons, the contribution of HAART to HIV-associated neurocognitive disorders is unknown. The toxicity of HAART compounds is due to distinct antiretroviral class-dependent mechanisms, such as alteration of protein metabolism and mitochondrial damage-induced generation of ROS (ROS), both of which have been implicated in other neurodegenerative conditions. These mechanisms, as well as HAART drugs themselves, can initiate the endoplasmic reticulum (ER) stress response, a multi-pronged pro-survival signaling pathway that may become deleterious if chronically activated, and autophagy, which has been implicated in neurodegeneration. An understanding of the cellular mechanisms triggered by the different classes of HAART drugs, in both neurons and macrophages, is crucial for guiding the design of new drugs and the assembly of combinational anti-retroviral therapies that minimize neurological impact. We hypothesize that HAART compounds induce neuronal toxicity both directly and indirectly (e.g. alteration of macrophage function), and that these mechanisms are mediated by cell-specific activation of stress responses that differ among classes of HAART compounds. Supporting this hypothesis, we have observed that individual antiretroviral drugs are neurotoxic in CNS cultures and that nontoxic drugs, when applied in recommended HAART combinations, become neurotoxic. We have also demonstrated an increase of downstream indicators of ER stress response activation in neurons and microglia/macrophages of patients with HIV-associated neurocognitive disorders, and in cultures of neurons and monocyte derived macrophages (MDM) following treatment with HAART compounds. Based on these findings, we propose to: 1) Determine the mechanisms of direct neuronal toxicity of HAART drug classes alone and in recommended, therapeutic combinations; 2) Determine the mechanisms of direct toxicity of HAART drug classes (alone and in combination) in monocyte derived macrophages, 3) Determine the contributions of HAART-exposed MDM to neurotoxicity. By investigating the cell-specific mechanisms of HAART toxicity in the central nervous system we will uncover an unexplored source for cognitive impairment in HIV-positive patients, identify targets to mitigate side-effects of HAART compounds that effectively control viral replilcation, and create a model to detect neurotoxicity of current and future HAART compounds alone and in combination.