Novel Pathways of HAARTmediated Neuronal Toxicity in the Central Nervous System

尽管在高效抗逆转录病毒疗法 (HAART) 时代，HIV 相关痴呆 (HAD) 的发病率有所下降，但 HAD 的患病率仍在增加，HIV 阳性患者中轻微认知诊断的频率也在增加。尽管HAART对周围神经系统和培养的神经元都有神经毒性，但HAART对HIV相关神经认知障碍的影响尚不清楚。 HAART化合物的毒性是由于不同的抗逆转录病毒类别依赖性机制造成的，例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（一种多管齐下的促生存信号传导途径，如果长期激活可能会变得有害）和自噬（与神经变性有关）。了解不同类别的 HAART 触发的细胞机制 神经元和巨噬细胞中的药物对于指导新药的设计和组合抗逆转录病毒疗法的组装以最大限度地减少神经系统影响至关重要。我们假设HAART化合物直接和间接诱导神经元毒性（例如巨噬细胞功能的改变），并且这些机制是由细胞特异性激活应激反应介导的，不同类别的HAART化合物不同。支持这一假设的是，我们观察到个别抗逆转录病毒药物在 CNS 培养物中具有神经毒性，而无毒药物在推荐的 HAART 组合中使用时会产生神经毒性。我们还证明，在 HIV 相关神经认知障碍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巨噬细胞 (MDM) 培养物中，ER 应激反应激活的下游指标有所增加。基于这些发现，我们建议： 1) 确定单独使用 HAART 药物类别和推荐的治疗组合的直接神经毒性机制； 2) 确定 HAART 药物类别（单独和联合）对单核细胞来源的巨噬细胞的直接毒性机制，3) 确定暴露于 HAART 的 MDM 对神经毒性的贡献。通过研究中枢神经系统HAART毒性的细胞特异性机制，我们将发现HIV阳性患者认知障碍的一个未探索的来源，确定减轻HAART化合物副作用的靶标，有效控制病毒复制，并创建一个模型来检测当前和未来单独和组合的HAART化合物的神经毒性。

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.