Molecular Imaging of neuroHIv using animals models of disease

2018年转基因大鼠研究综述： 1.氧化应激在TG大鼠神经病理中的作用：HIV相关性神经认知障碍(HAND)仍然是一个普遍存在的问题，已有报道称HIV携带者因年龄增长而导致神经认知障碍的进展。HAND的特征是细胞水平上的活性氧(ROS)和活性氮物种(RNS)的增加。运动和行为障碍是常见的症状之一，人们认为氧化和亚硝化应激导致机械性改变，导致神经认知功能障碍。我们之前的成像、组织学、运动和行为评估支持随着HIV-1TG大鼠年龄的增长，多巴胺能功能的失调。本研究的目的是证明在HIV-1转基因(HIV-1TG)大鼠脑内与多巴胺能功能障碍相关的神经解剖区域内存在氧化和亚硝化应激。我们发现，与年龄匹配的野生型大鼠相比，HIV-1TG大鼠基底节神经元突触前多巴胺能神经元丢失，纹状体NADPH氧化酶-4(NOX4)和神经元型一氧化氮合酶(NNOS)表达增加，3-硝基酪氨酸(3-NT)修饰的神经丝蛋白增加。这些异常在9月龄大鼠中可见，而在3月龄大鼠中未见。最后，这种自由基介导的神经元病理的增加发生在没有显著诱导转录因子Nrf2以及Nrf2反应的硫氧还蛋白和谷胱甘肽抗氧化系统的氧化还原适应的情况下。我们的发现提示，在衰老的HIV-1 TG大鼠中，可能由于长期暴露于HIV-1蛋白和缺乏适当的氧化还原适应，基底节神经元神经丝蛋白的亚硝化应激和3-NT修饰加速，可能导致多巴胺能神经元的结构变化和继发性多巴胺能功能障碍。我们已经在《美国病理学》杂志上发表了我们的研究结果。 使用受SIV感染的猴子的研究摘要： 1.我们假设11C-DASB结合在SIV感染时会受到影响(关于接种前的扫描)。我们使用的是感染了神经毒力SIV毒株SIVsm804E的恒河猴。我们用11C-DASB在猴体内完成了免疫前后靶向SERT的PET成像，以检测SIV感染下的5-羟色胺能系统状态。当我们比较最后的时间点成像(11C-DASB PET)和接种前的扫描时，我们发现大多数接种SIV的动物(7只动物中有6只)5-羟色胺转运体(SERT)水平/表达增加。我们在《精神病学前沿》上发表了我们的研究结果。 2.我们还在以外周病毒血症和疾病控制(模拟最佳治疗的HIV+患者)为协变量，研究SIV感染猴子的神经炎性变化的演变。为了实现这一目标，我们已经完成了18F-DPA-714PET成像，作为体内感染SIV的猴子小胶质细胞激活(神经炎症)的生物标志物。与我们的预期不同，我们没有发现18F-DPA714 PET成像在猴子体内的转位蛋白表达增加(5/5在接种后显示结合减少，而不是增加)。我们认为这与脑脊液病毒载量测量的中枢神经系统受累的严重程度有关。我们还发现，由于大脑中的高病毒负荷，许多脑细胞正在死亡。我们已经在mBio上发表了我们的研究结果

Summary of studies using the transgenic rats in 2018: 1. Role of oxidative stress in the neuropathology of the tg rat: HIV-associated neurocognitive disorder (HAND) continues to be a widespread problem, and progression of neurocognitive impairment caused by aging in individuals with HIV has been reported. HAND is characterized by an increase in reactive oxygen (ROS), and reactive nitrogen species (RNS) at the cellular level. Motor and behavioral dysfunction are among the common symptoms and it is believed that oxidative and nitrosative stress contribute to mechanistic changes leading to neurocognitive impairment. Our previous imaging, histological, motor and behavioral assessments support a dysregulation in dopaminergic function as the HIV-1 Tg rat ages. The goal of this study was to demonstrate the presence of oxidative and nitrosative stress within the neuroanatomic areas associated with dopaminergic dysfunction in the HIV-1 transgenic (HIV-1 Tg) rat brain. We found pathology consistent with pre-synaptic dopaminergic neuronal loss, increases in striatal NADPH oxidase-4 (Nox4) and neuronal nitric oxide synthase (nNOS) expression with associated increase in 3-nitrotyrosine (3-NT) modified neurofilament proteins in the basal ganglia neurons of HIV-1 Tg rats compared to age-matched wild type rats. Those abnormalities were seen in the 9 month-old but not in the 3 month-old rats. Finally, this increase in free radical mediated neuronal pathology occurred without significant induction of the transcription factor Nrf2 and redox adaptation of the Nrf2 responsive thioredoxin and glutathione antioxidant system. Our findings suggest that in the aging HIV-1 Tg rat, possibly due to chronic exposure to HIV-1 proteins and lack of appropriate redox adaptation, nitrosative stress and 3-NT modification of neurofilament proteins of basal ganglia neurons is hastened possibly contributing to structural changes to dopaminergic neurons and secondary dopaminergic dysfunction. We have published our results in the American journal of pathology. Summary of studies using the SIV infected monkeys: 1. We hypothesized that 11C-DASB binding will be affected in SIV infection (with respect to pre-inoculation scans). We are using rhesus macaques infected with the neurovirulent SIV strain, SIVsm804E. We have finished acquiring PET imaging targeting SERT using 11C-DASB in monkeys before and after inoculation, in order to detect serotonergic system status under the effect of SIV infection. We found that the serotonin transporter (SERT) levels/expression increased in most animals (6 out of 7) that were inoculated with SIV when we compared the last time point imaging (11C-DASB PET) to the preinoculation scans. We published our results in Frontiers of Psychiatry. 2. We are also investigating the evolution of neuroinflammatory changes in the SIV-infected monkeys using peripheral viremia and disease control (simulating optimally treated HIV+ patients) as covariants. Towards this goal, we have finished acquiring 18F-DPA-714 PET imaging as biomarker of microglial activation (neuroinflammation), in vivo, in the SIV-infected monkeys. Unlike our expectations, we did not find increased translocator protein expression using 18F-DPA714 PET imaging in the monkeys (5 out 5 showing decreased binding after inoculation rather than increased binding). We believe this correlates to the severity of CNS involvement as measured by CSF viral load. We also found that many brain cells were dying because of the high viral loads in the brain. We have published our results in mBIO