Fractalkine as a therapeutic for opioid accelerated neurotoxicity in HIV

描述(由申请人提供)：在艾滋病毒阳性个体中，阿片类药物滥用者向艾滋病痴呆症的进展似乎明显加快。在中枢神经系统中，HIV感染小胶质细胞，在较小程度上感染星形胶质细胞，增加氧自由基、促炎细胞因子的产生，并释放HIV-1蛋白，如gp120和Tat，从而导致旁观神经元的损伤甚至死亡。滥用阿片类药物可以通过直接作用于神经胶质细胞，协同增加艾滋病毒的上述病理生理效应。我们发现，Fractalkine是小胶质细胞对神经元直接毒性的关键调节因子，对吗啡联合暴露引起的加速HIV-1神经毒性具有完全保护作用。相比之下，阻断Fractalkine受体(CX3CR1)完全模拟了吗啡和TAT联合使用的神经毒性效应。这表明，吗啡-HIV联合使用选择性地减弱了Fractalkine水平或通过CX3CR1传递的信号。有研究提出，假设吗啡通过破坏Fractalkine-CX3CR1相互作用和促进小胶质细胞介导的神经元杀伤而导致HIV脑炎的附带损害。这些研究将明确地确定特定的细胞来源(S)、靶点(S)和因果胶质神经元(反之亦然)，这些信号是在阿片类艾滋病毒TAT/GP120暴露后由Fractalkine介导的神经保护机制下的。此外，还将探讨吗啡HIV1TAT和Gp120对神经元、小胶质细胞和星形胶质细胞中Fractalkine的表达、释放和加工、CX3CR1的表达以及Fractalkine功能的关键调节因子(ADAM10、ADAM17和组织蛋白酶S)的影响。最后，在一种新的TAT转基因小鼠HIV脑炎模型中，将评估Fractalkine和Fractalkine“Sheddase”抑制剂的潜在神经保护作用。这些实验代表了一种适合R21机制的高风险/高回报策略，目的是了解Fractalkine如何防止阿片类药物-HIV共病中的毒性神经元-神经胶质相互作用。 与公共健康相关：新出现的证据表明，阿片类药物滥用阻碍了通常存在于神经元表面的一种神经保护因子(称为Fractalkine)的作用。我们发现，当我们在致死浓度的吗啡和HIV蛋白中加入Fractalkine时，它可以完全阻止细胞培养中的神经元损伤和死亡。该提案将研究阿片类药物是否会导致神经元失去Fractalkine和/或阿片类药物是否会导致免疫细胞忽视保护性的Fractalkine信号，并确定Fractalkine是否可以用于治疗。

DESCRIPTION (provided by applicant): The progression to AIDS dementia in HIV-positive individuals appears to be markedly accelerated in opiate drug abusers. In the CNS, HIV infects microglia, and to a lesser extent astroglia, increasing the production of oxyradicals, pro-inflammatory cytokines, and the release of HIV-1 proteins such as gp120 and Tat, which can cause injury and even death in bystander neurons. Opioid drugs of abuse can synergistically increase each of the above pathophysiological effects of HIV through direct actions on glia. We have discovered that fractalkine, which is a key regulator of microglial directed toxicity to neurons, is completely protective against the accelerated HIV-1 neurotoxicity caused by morphine co-exposure. By contrast, blocking fractalkine receptors (CX3CR1) completely mimics the neurotoxic effects of combined morphine and Tat. This suggests that morphine-HIV in combination selectively attenuate fractalkine levels or signaling via CX3CR1. Studies are proposed that hypothesize that morphine induces collateral damage in HIV encephalitis by disrupting fractalkine-CX3CR1 interactions and enhancing microglial mediated killing of neurons. These studies will unambiguously determine the specific cellular origin(s), target(s), and causal glia-neuron (or vice versa) directed signaling underlying fractalkine-mediated neuroprotection following opioid HIV Tat/gp120 exposure. In addition, the expression, release, and processing of fractalkine, the expression of CX3CR1 and key regulators of fractalkine function (ADAM10, ADAM17, and cathepsin S) will be explored in neurons, microglia, and astroglia following morphine HIV-1 Tat and gp120. Lastly, the potential neuroprotective effects of fractalkine and fractalkine "sheddase" inhibitors will be assessed in a novel Tat transgenic mouse model of HIV encephalitis co-exposed to morphine. These experiments represent a high risk/high reward strategy appropriate for the R21 mechanism with the goal of understanding how fractalkine prevents toxic neuron-glial interactions in opioid drug-HIV comorbidity. PUBLIC HEALTH RELEVANCE: Emerging evidence indicates that opioid drug abuse blocks the actions of a neuroprotective factor (termed fractalkine) normally present on the surface of neurons. We discovered that when we add fractalkine to lethal concentrations of morphine and HIV proteins it completely blocked neuronal injury and death in cell culture. The proposal will examine whether opioids cause neurons to lose fractalkine and/or whether opioids cause immune cells to ignore the protective fractalkine signal, and determine whether fractalkine could be used therapeutically.