Microglia and choroid plexus macrophages in Neuro-AIDS

人类免疫缺陷病毒(HIV)迅速渗透到中枢神经系统(CNS)，可导致不同程度的神经元丢失和神经损伤，包括艾滋病痴呆。由于在艾滋病发展之前病毒与中枢神经系统的相互作用可能为随后的疾病进展奠定了基础，因此早期干预对于有效治疗艾滋病毒感染的神经和行为并发症可能是重要的。小胶质细胞和巨噬细胞被认为在病毒渗透到神经系统和随后的发病机制中发挥关键作用。然而，我们对病毒与脑小胶质细胞和巨噬细胞的相互作用的了解仍然相当有限。具体地说，对小胶质细胞和巨噬细胞在发病机制中的相对作用，刺激这些细胞激活和释放可能的毒素，以及导致神经元功能障碍的机制知之甚少。利用猫免疫缺陷病毒(FIV)，我们建立了一个病毒感染和发病机制的模型，该模型可能有助于解释每个细胞如何在进化的发病机制中做出贡献。这一模型表明，脉络丛内的巨噬细胞群可能维持着一个病毒储存库，能够局部感染T细胞，并可能有助于巨噬细胞的运输和神经毒素的分泌。利用原代培养的脑小胶质细胞、脉络丛巨噬细胞和神经元，我们将确定诱导小胶质细胞和巨噬细胞激活和分泌毒素的病毒和非病毒刺激。小胶质细胞/巨噬细胞的激活将通过评估细胞内钙离子的增加、细胞因子和趋化因子mRNA的产生以及原代培养中对皮质猫神经元的毒性物质的积累来评估。此外，我们还将从药理学角度研究分泌的毒素对神经元的作用，这些毒素会导致细胞内钙离子的不稳定。然后将体外感染的小胶质细胞、巨噬细胞或T细胞注入脑室，生成中枢神经系统发病的体内模型。这些研究将阐明小胶质细胞、巨噬细胞和T细胞在慢病毒感染后大脑中发展的炎症反应中的作用，并有助于建立巨噬细胞诱导毒性的动物模型，该模型可用于识别和评估早期治疗干预的改进策略。

Human immunodeficiency virus (HIV) rapidly penetrates the central nervous system (CNS) and can lead to varying levels of neuronal loss and neurological impairments including AIDS dementia. Because interactions of the virus with the CNS prior to the development of AIDS probably set the stage for subsequent disease progression, early intervention is likely to be important for effective treatment of the neurological and behavioral complications of HIV infection. Microglia and macrophages are thought to play a key role in the penetration of the virus into the nervous system and subsequent pathogenesis. However, our understanding of the interactions of the virus with brain microglia and macrophages is still quite limited. Specifically, little is know about the relative role of microglia and macrophages in pathogenesis, the stimuli that provoke the activation of these cells and release of putative toxins, and the mechanisms that lead to neuronal dysfunction. Using feline immunodeficiency virus (FIV) we have developed a model of viral infection and pathogenesis that may help to explain how each cell might contribute to evolving pathogenesis. This model suggests that the macrophage population within the choroid plexus could maintain a virus reservoir capable of infecting T-cells locally and perhaps contribute to the trafficking of macrophages and secretion of neurotoxins. Using primary cultures of brain microglia, choroid plexus macrophages and neurons, we will determine the viral and non-viral stimuli that induce microglial and macrophage activation and secretion of toxins. Microglial/macrophage activation will be assessed by evaluating increases in intracellular calcium in vitro, production of cytokine and chemokine mRNA and the accumulation of substances toxic to cortical cat neurons in primary culture. In addition, we will pharmacologically characterize the actions of the secreted toxins on neurons that lead to the destabilization of intracellular calcium. Microglia, macrophages or T-cells infected in vitro will then be infused into the brain ventricles to generate an in vivo model of central nervous system pathogenesis. These studies will clarify the role of microglia, macrophages and T-cells in the inflammatory response that develops in the brain following lentivirus infection and help to generate an animal model of macrophage-induced toxicity that can be used for identification and evaluation of improved strategies for early therapeutic intervention.