Cocaine & HIV: Role of PDGF/PDGF-Receptor Axis in Blood Brain Barrier Disruption

描述（由申请人提供）：静脉吸毒和艾滋病毒感染是两个相互关联的全球健康危机，因为共用针头是一种公认的艾滋病毒传播模式。虽然HIV-1感染是25-44岁美国人死亡的主要原因，但注射毒品现在占美国每年报告的所有新艾滋病病例的三分之一左右。通常被艾滋病毒感染者滥用的可卡因，已被认为通过未知的机制使艾滋病毒相关性痴呆（HAD）恶化。大脑是娱乐性毒品和HIV-1的靶器官。血脑屏障（BBB）的破坏是HIV进入CNS的主要途径。单核细胞和/或T细胞穿过BBB进入CNS实质的机制仍然是一个谜。血脑屏障对于维持中枢神经系统稳态和调节神经微环境至关重要。这项提案将调查可卡因和艾滋病毒合作，以诱导血脑屏障破坏的具体机制。我们假设HIV蛋白和可卡因可以以相加或协同的方式相互作用，以直接放大细胞和分子过程，从而导致其毒性血管效应，例如破坏BBB和增加受感染的单核细胞迁移到CNS中。这一假设的基本原理是基于初步研究，显示在患有猿猴-人类免疫缺陷病毒脑炎的猕猴的大脑中以及在感染HIV或暴露于可卡因的单核细胞中，血管渗透性PDGF-BB上调。反过来，我们的新发现也表明可卡因介导的内皮单层破坏涉及PDGF-beta受体的磷酸化。因此，该提议将研究一个新的概念，即PDGF/PDGF-R轴可能是可卡因/HIV介导的BBB破坏中缺失的环节。使用HIV神经变性的体外和互补小鼠模型的组合，我们将在三个特定目标中测试该假设：该研究的SA 1将集中于研究暴露于HIV蛋白和/或可卡因的单核细胞中PDGF上调所涉及的分子机制。SA 2将致力于探索PDGF和可卡因诱导的人脑微血管内皮细胞通透性变化的机制。最后，SA 3将使用体内方法来检验以下假设：PDGF-β受体抑制剂gleevac对PDGF/PDGF-R轴的抑制将导致暴露于可卡因的HIV转基因大鼠和达特转基因小鼠中BBB破坏的消除。公共卫生相关性：可卡因是一种强效和成瘾性的大脑兴奋剂，经常被艾滋病毒感染者滥用，已知会加剧艾滋病毒相关的中枢神经系统疾病。该提案旨在了解HIV-1和可卡因在大脑中的联合有害作用所涉及的分子机制，最终目标是测试新的治疗方法。

DESCRIPTION (provided by applicant): IV drug use and HIV infections are two linked global health crises since needle sharing is a well-recognized mode of HIV transmission. While HIV-1 infection is the leading cause of death among Americans 25-44 years old, injection drug use now accounts for about one-third of all new US AIDS cases reported each year. Cocaine, often abused by HIV-infected patients, has been suggested to worsen HIV-associated dementia (HAD) via unknown mechanisms. The brain is a target organ for both, the recreational drugs and HIV-1. Disruption of the blood brain barrier (BBB) is the main route of HIV entry into the CNS. The mechanisms by which the monocytes and/or T cells cross the BBB into the CNS parenchyma still remain an enigma. BBB is critical for the maintenance of CNS homeostasis and for the regulation of the neural microenvironment. This proposal will investigate specific mechanisms by which cocaine and HIV co-operate to induce BBB disruption. We hypothesize that HIV proteins & cocaine can interact in an additive or synergistic manner to directly amplify cellular & molecular processes contributing to their toxic vascular effects such as, disruption of the BBB and increased transmigration of infected monocytes into the CNS. The rationale of this hypothesis is based on preliminary studies showing up-regulation of a vascular permeant PDGF-BB in the brains of macaques with Simian-human immunodeficiency virus encephalitis and in monocytes infected with HIV or exposed to cocaine. Reciprocally, our new findings also demonstrate that cocaine-mediated disruption of endothelial monolayer involves phosphorylation of the PDGF-beta receptor. This proposal will thus investigate a novel concept that PDGF/PDGF-R axis could be the missing link in cocaine/HIV-mediated disruption of BBB. Using a combination of in vitro and complementary murine models of HIV neurodegeneration, we will test the hypothesis in three specific aims: SA1 of the study will be focused on investigating the molecular mechanisms involved in upregulation of PDGF in monocytes exposed to HIV proteins and/or cocaine. SA2 will be focused on exploring the mechanisms involved in PDGF & cocaine-induced permeability changes in human brain microvascular endothelial cells. Finally, SA3 will use in vivo approach to test the hypothesis that inhibition of the PDGF/PDGF-R axis by the PDGF-beta receptor inhibitor gleevac will result in abrogation of BBB disruption in HIV-transgenic rats and Tat transgenic mice exposed to cocaine. PUBLIC HEALTH RELEVANCE: Cocaine, a highly potent and addictive brain stimulant, often abused by HIV-infected patients, is known to exacerbate HIV-associated CNS disease. This proposal is aimed at understanding molecular mechanisms involved in the combined deleterious effects of HIV-1 and cocaine in the brain with the ultimate goal of testing novel therapeutics.