Mechanisms of Interferon-alpha Neurotoxicity

全世界有3500多万人感染艾滋病毒。这些艾滋病毒感染者中有50% 尽管联合抗逆转录病毒治疗， 治疗（cART）然而，自从cART出现以来，艾滋病毒相关痴呆症的发病率，最严重的是 HAND的一种形式，已经减少，在像美国这样的国家， available.因此，轻度形式的HAND，如无症状性神经认知障碍和轻度 神经认知障碍现在占优势最终，这些温和的HAND形式导致与HIV相关的 痴呆症及其严重后果。此外，由于艾滋病毒感染者的寿命更长， 易患老年性疾病，如阿尔茨海默病，这可能会加剧手。因此，委员会认为， 必须开发[cART]的辅助疗法。干扰素-α（IFNα）在脑脊液中升高 并与认知功能障碍相关。研究，包括临床和基础研究， 确定IFNα具有神经毒性，导致认知功能障碍和神经元树突异常。我们 研究表明，IFNα可能成为HAND预防性治疗的靶点。 开发了SCID小鼠中的HAND模型，并形成了翻译的重要部分。 这一提案的组成部分。该模型展示了人类HAND的行为相似性。模型 在研究发病机制和开发新的治疗方法方面很有用。最近有所改善 在治疗前后使用物体识别测试使我们能够确定行为的逆转 通过新的疗法治疗异常。模型的这一方面特别重要，因为它反映了温和的 人类的认知障碍与手，最常见的形式，因此模型条件发生在 人体临床试验因此，HAND模型代表了用于临床前筛选新的抗肿瘤药物的有价值的工具。 连续治疗。此外，IFNα在HAND小鼠的脑中升高，并且在HAND小鼠中阻断IFNα是一种有效的方法。 有效的治疗，可能证明有效的手患者。尽管如此，在人体中中和IFNα可能 由于潜在的副作用，最终不实用。因此，使用大鼠神经元培养物来研究 IFNα神经毒性机制。通过研究IFNα的神经毒性机制， 可以开发HAND以及可能其他认知障碍的治疗。 研究表明，IFNα神经毒性是通过IFNα受体（IFNAR）介导的， NMDA受体（NMDAR）。暴露于IFNα的大鼠神经元表现出树突长度减少， 分支最近的研究表明，沿着沿着树突的PSD-95斑点减少，表明更特异性的 毒性机制。蛋白质组学显示Arf 1、Cdc 42和β-连环蛋白的减少，这是关键的 细胞内信号蛋白密切参与树突棘支架。Arf 1降低显示 通过蛋白质组学已经通过蛋白质印迹验证。PSD-95稳定NMDAR和AMPA受体 因此，PSD-95在IFNα潜在地将其与Arf 1、Cdc 42和可能的β-catenin连接后降低。验证后 Cdc 42和β-catenin减少，我们将在神经元培养物中[单独]过度表达它们 暴露于IFNα以确定过表达是否校正PSD-95降低。 我们还假设，由于IFNα降低了脊柱上的PSD-95，这导致了 AMPA受体在体外和体内。这最终导致神经网络的破坏， 可塑性和长期抑郁导致认知能力差。我们计划研究以下因素的相对贡献： IFNAR和NMDAR对这些效应的影响，最终相信这两种受体都有贡献， 未来HAND的连续治疗将需要针对这两种受体。

Worldwide there are over 35 million individuals living with HIV. As many as 50% of these HIV-infected individuals will develop HIV associated neurocognitive disorders (HAND), despite combined antiretroviral therapy (cART). Yet, since the advent of cART the incidence of HIV associated dementia, the most severe form of HAND, has diminished and represents less than 5% of HAND in countries like the US where cART is available. Therefore, mild forms of HAND, such as Asymptomatic Neurocognitive Impairment and Mild Neurocognitive Disorder, now predominate. Eventually these mild forms of HAND lead to HIV associated dementia and its severe consequences. In addition, because HIV-infected individuals are living longer, they are susceptible to age related diseases like Alzheimer’s disease, which can exacerbate HAND. Consequently, adjunctive therapies [to cART] must be developed. Interferon-alpha (IFNα) is elevated in the cerebrospinal fluid of HAND patients and correlates with cognitive dysfunction. Studies, including both clinical and basic, have established that IFNα is neurotoxic causing cognitive dysfunction and neuronal dendritic abnormalities. Our investigations suggest that IFNα could be a target for adjunctive therapies for HAND. A model of HAND in SCID mice was developed and forms an important part of the translational component of this proposal. This model demonstrates behavioral similarities to HAND in humans. The model has been useful in studying pathogenesis and the development of novel treatments. Recent improvements using object recognition testing before and after treatment enable us to determine reversal of behavioral abnormalities by novel therapies. This aspect of the model is particularly important because it reflects mild cognitive impairment in humans with HAND, the most common forms, and thus models conditions occurring in human clinical trials. As a result, the HAND model represents a valuable tool for pre-clinical screening of novel adjunctive therapies. Also, IFNα is elevated in brains of HAND mice and blocking IFNα in HAND mice is an effective treatment that may prove effective in HAND patients. Nevertheless, neutralizing IFNα in humans may not be ultimately practical due to potential side effects. Therefore, rat neuronal cultures are used to study the mechanisms of IFNα neurotoxicity. By studying the mechanisms of IFNα neurotoxicity, novel approaches to treatment of HAND, and perhaps other cognitive disorders, may be developed. Studies have shown that IFNα neurotoxicity is mediated through both the IFNα receptor (IFNAR) and the NMDA receptor (NMDAR). Rat neurons exposed to IFNα exhibit decreases in dendritic length and branching. Recent work demonstrates decreased PSD-95 puncta along dendrites, suggesting more specific mechanisms of toxicity. Proteomics demonstrate decreases in Arf1, Cdc42, and β-catenin, which are critical intracellular signaling proteins that are intimately involved in dendritic spine scaffolding. Arf1 decreases shown by proteomics have been verified through Western blotting. PSD-95 stabilizes NMDAR and AMPA receptors and thus PSD-95 decreases after IFNα potentially link it to Arf1, Cdc42 and possibly β-catenin. After validation that Cdc42 and β-catenin are decreased, we will overexpress all of them [individually] in neuronal cultures exposed to IFNα to determine if overexpression corrects PSD-95 decreases. We also hypothesize that because IFNα decreases PSD-95 on the spine, this leads to internalization of AMPA receptors both in vitro and in vivo. This ultimately results in disruption of neuronal networks, decreased plasticity, and long-term depression leading to poor cognition. We plan to investigate the relative contribution of the IFNAR and NMDAR to these effects, with the ultimate belief that both receptors contribute and that any future adjunctive treatments for HAND will need to address both receptors.