Markers of HIV Brain Disease under HAART: Validation in a Mouse Model

说明(申请人提供)：本建议书是根据PA-07-089的要求提交的。尽管高度有效的抗逆转录病毒疗法在恢复痴呆HIV-1感染者的免疫功能和认知功能方面总体上取得了成功，但对日益流行的轻度中枢神经系统疾病的效果有限。根据我们对轻度认知和运动障碍(MCMD)患者大脑中独立治疗的、显著的基因失调的发现，我们假设，在现有治疗中持续存在的长期感染细胞引起了大脑生理的核心变化，这些细胞并不是为了阻止整合前病毒的表达而设计的。这些细胞持续产生病毒蛋白可导致累积性炎症、抗病毒和氧化应激反应，从而影响神经功能。为了验证这一假说以及核心缺陷的一个机制，我们提出了四个具体目标：1)建立具有代表性的轻度艾滋病毒CNS疾病患者的全基因组脑基因表达谱；2)确定在接受抗逆转录病毒治疗的情况下，持续轻度艾滋病毒CNS疾病在大脑中的生物通路和生物标记物；3)在免疫活性和免疫缺陷小鼠的艾滋病毒感染模型中验证选定的艾滋病毒CNS疾病标志物；4)检验轻度、慢性艾滋病毒CNS疾病依赖于不受现有抗逆转录病毒治疗影响的低水平病毒转录的假设。我们依赖于S.Morgello博士收集的定义明确的患者队列的脑组织，通过全基因组表达分析和生物信息学发现的基因，包括与豪伊博士在脂代谢产物中可见的氧化应激途径的验证性研究，以及再现轻度中枢神经系统疾病的许多特征的小鼠艾滋病毒感染的强大实验模型。利用可以感染小鼠并易于进行基因修改的嵌合艾滋病毒，我们将测试轻度中枢神经系统疾病的一个因果假设：尽管有效的治疗仍在大脑中持续存在的低水平病毒转录，但仍保持脑细胞生理的失调，表现为mcmd。如果这些研究表明，尽管接受了抗病毒治疗，但HIV-1的低水平表达损害了大脑中的细胞功能，应该努力开发新的抗病毒药物，以阻断来自细胞储存库的病毒转录。公共卫生相关性医学通过开发有效的抗病毒药物，延长了艾滋病毒感染者的寿命，改善了他们的健康。然而，尽管接受了治疗，艾滋病毒疾病的某些方面仍然存在，其中之一会导致大脑和中枢神经系统的功能异常。我们建议使用最先进的基因发现和脂质代谢组学工具来确定这种轻微但显著和持久的脑部疾病的分子基础。一旦在人类中得到确认，我们将使用这些轻微脑部疾病的标记来测试由小鼠感染艾滋病毒引起的类似疾病是否在药物治疗的存在下持续存在，即使病毒感染开始在大脑中。最后，我们将通过在小鼠的大脑中建立一个实验性的HIV感染，在它开启之前一直保持沉默，通过有效的治疗来询问HIV感染者轻微脑部疾病的起源。通过打开和关闭这种大脑艾滋病毒，我们将确定是否是残留的艾滋病毒表达本身导致了大脑中无法用现有药物控制的轻微疾病。这项研究可能会为控制在当前HAART制度下持续存在的艾滋病毒CNS损害提出两项建议：a)相对于目前的惯例，更早地对血清转换进行抗病毒干预；b)呼吁科学界和医药界开发阻止艾滋病毒表达的抗艾滋病毒药物。

DESCRIPTION (provided by applicant): This proposal is submitted in response to PA-07-089. Despite its overall success at restoring immune function and often cognitive function in demented HIV-1-infected persons, highly active antiretroviral therapy has limited effects upon milder CNS disease that is increasingly prevalent. Based on our findings of treatment independent, significant gene dysregulation in brains of patients with minor cognitive and motor disorder (MCMD), we hypothesize that there are core changes in brain physiology arising from long-lived infected cells that persist through existing therapies, which were not designed to arrest expression of integrated provirus. Unabated production of viral proteins by these cells can cause cumulative inflammatory, antiviral, and oxidative stress reactions that affect neuronal function. To test this hypothesis as well as one mechanism underlying the core defect we propose four Specific Aims to: 1) establish genome-wide brain gene expression profiles representative of patients with milder forms of HIV CNS disease; 2) identify biological pathways and biomarkers in the brain characteristic of continuing mild HIV CNS disease in the presence of antiretroviral treatment; 3) validate selected markers of mild HIV CNS disease in a mouse model of HIV infection in immunocompetent and immunodeficient mice; 4) test the hypothesis that mild, chronic HIV CNS disease depends upon low level virus transcription unaffected by existing antiretroviral treatment. We rely upon brain tissue from well defined patient cohorts assembled by Dr. S. Morgello, gene discovery through genome wide expression analysis and bioinformatics, confirmatory studies including pathways of oxidative stress visible in lipid metabolites with Dr. Haughey, and a robust experimental model of HIV infection in mice that reproduces many features of mild CNS disease. Using chimeric HIV that can infect mice and is amenable to genetic modification, we shall test one causal hypothesis for mild CNS disease: low-level virus transcription that persists in the brain despite effective therapy maintains dysregulation of brain cell physiology that is expressed as MCMD. If these studies demonstrate that low level HIV-1 expression impairs cellular function in the brain despite antiviral treatment, efforts should be directed toward development of new antiviral agents to block viral transcription from cellular reservoirs. PUBLIC HEALTH RELEVANCE Medical science has prolonged life and improved health of HIV-infected people through development of effective antiviral drugs. Nevertheless, some aspects of HIV disease persist despite treatment, one of these leads to functional abnormalities in the brain and central nervous system. We propose to determine the molecular bases of this mild, but significant and persistent brain disease using state-of-the-art gene discovery and lipid metabolomics tools. Once confirmed in human beings, we shall use these markers of mild brain disease to test whether a similar disease caused by HIV infection of mice persists in the presence of drug treatment, even when the virus infection begins in the brain. Finally, we shall ask questions about the origin of mild brain disease in HIV infected people with effective therapy by establishing an experimental HIV infection in the brains of mice that is silent until it is turned on. By turning on and off this brain HIV, we shall determine whether it is residual HIV expression itself that causes the mild disease in the brain that cannot be controlled by existing drugs. This research may lead to two recommendations for control of the HIV CNS impairment that persists under current HAART regimes: a) earlier antiviral intervention relative to seroconversion than it is customary today; b) a call to the scientific and pharmaceutical communities to develop anti-HIV drugs that stop HIV expression.