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

说明(申请人提供)：静脉用药和艾滋病毒感染是两个相互关联的全球健康危机，因为共用针头是公认的艾滋病毒传播方式。虽然HIV-1感染是25-44岁美国人的主要死亡原因，但注射毒品现在占美国每年报告的所有新增艾滋病病例的三分之一左右。可卡因经常被艾滋病毒感染患者滥用，已被认为通过未知的机制加重艾滋病毒相关痴呆(HAD)。大脑是娱乐毒品和HIV-1病毒的靶器官。血脑屏障(BBB)破坏是HIV进入中枢神经系统的主要途径。单核细胞和/或T细胞穿过血脑屏障进入中枢神经系统实质的机制仍然是个谜。血脑屏障是维持中枢神经系统内环境稳定和调节神经微环境的关键。这项提案将调查可卡因和艾滋病毒合作诱导血脑屏障中断的具体机制。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，直接放大导致其毒性血管效应的细胞和分子过程，如破坏血脑屏障和增加受感染的单核细胞向中枢神经系统的迁移。这一假说的理论基础是基于初步研究，该研究表明患有猿猴-人类免疫缺陷病毒脑炎的猕猴大脑以及感染艾滋病毒或接触可卡因的单核细胞中血管内PDGF-BB的表达上调。反过来，我们的新发现也表明可卡因介导的内皮单层的破坏涉及PDGF-β受体的磷酸化。因此，这项建议将调查一个新的概念，即PDGF/PDGF-R轴可能是可卡因/HIV介导的血脑屏障破坏中缺失的一环。结合使用体外和互补的小鼠HIV神经变性模型，我们将在三个特定目标上检验这一假设：该研究的SA1将专注于研究暴露于HIV蛋白和/或可卡因的单核细胞中PDGF上调的分子机制。SA2将重点探索PDGF的相关机制&可卡因诱导的人脑微血管内皮细胞通透性改变。最后，SA3将使用体内方法来测试假设，即PDGF-β受体抑制剂Gleevac抑制PDGF/PDGF-R轴将导致暴露在可卡因中的HIV转基因大鼠和TAT转基因小鼠的血脑屏障破坏。与公共卫生相关：可卡因是一种高度有效和令人上瘾的大脑刺激剂，经常被艾滋病毒感染患者滥用，众所周知，它会加剧艾滋病毒相关的中枢神经系统疾病。这项提议旨在了解HIV-1和可卡因对大脑的联合有害影响所涉及的分子机制，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.