HIV: gp120, Chemokine Receptors & Macrophage Activation

描述（申请人提供）：HIV脑病（HIVE）的临床疾病与巨噬细胞/小胶质细胞（M/M）的激活程度密切相关，许多模型表明HIV-1诱导M/M释放损伤神经元并具有炎症或趋化电位的可溶性介质。暴露于HIV-1 Env糖蛋白gp120和直接感染均可诱导这些反应。这些结果暗示了hiv诱导的M/M激活和神经毒素产生的主要致病作用。许多研究已经解决了HIVE中的炎症介质和M/M释放的神经毒素对HIV的反应。然而，我们对HIV触发M/M激活和神经毒素释放的具体机制知之甚少，这是我们对HIV神经发病机制认识的一个重要空白。为了进入细胞，HIV-1使用趋化因子受体CCR5和CXCR4，它们通常会触发细胞外刺激的激活和迁移。在之前资助期支持的研究中，我们发现gp120通过趋化因子受体在原代巨噬细胞中引发细胞内信号，包括离子信号、Ca2+升高和蛋白激酶磷酸化。此外，通过这些途径激活可导致炎症介质的释放，炎症介质可能有助于进一步激活和细胞募集。此外，我们发现gp120激活的巨噬细胞产生损伤神经元的因子，并确定了通过趋化因子受体相互作用激活的特定MAP激酶途径。本项目将重点研究gp120介导的M/M激活在HIVE发病机制中的作用机制。我们的假设是HIV-1 Env与脑巨噬细胞/小胶质细胞上的趋化因子受体相互作用，触发细胞内信号级联反应，导致不适当的激活、炎症介质分泌和神经毒素产生。该项目的目标是更好地了解HIV-1 Env在巨噬细胞中引发的途径，以及这些信号级联如何促进与HIVE相关的巨噬细胞激活和功能障碍。我们将：(1)确定HIV-1通过人原代巨噬细胞的趋化因子受体激活的细胞内信号；(2)确定hiv诱导的巨噬细胞细胞因子和神经毒素产生的具体途径；(3)确定与HIVE发病直接相关的原代、病毒和原代细胞相关的信号通路，使用来自HIVE组织的原代分离物和人脑源性巨噬细胞/小胶质细胞来验证在单核细胞源性巨噬细胞中获得的结果。我们预计这些研究将为HIVE中M/M激活和神经毒素产生的传入机制提供深入的见解，并最终为有针对性的干预这一过程的策略提供合理的基础。

DESCRIPTION (provided by applicant): Clinical disease in HIV encephalopathy (HIVE) is closely correlated with the degree of macrophage/microglia (M/M) activation, and many models have shown that HIV-1 induces M/M to release soluble mediators that injure neurons & have inflammatory or chemotactic potential. Both exposure to the HIV-1 Env glycoprotein gp120 & direct infection can induce these responses. These results implicate a major pathogenic role for HIV-elicited M/M activation & neurotoxin production. Many studies have addressed inflammatory mediators in HIVE & neurotoxins released by M/M in response to HIV. However, little is known about the specific mechanism by which HIV triggers M/M activation & neurotoxin release, which is an important gap in our understanding of HIV neuropathogenesis. To enter cells, HIV-1 uses the chemokine receptors CCR5 & CXCR4, which normally trigger activation & migration in response to extracellular stimuli. In studies supported by the previous funding period, we found that gp120 elicits intracellular signals in primary macrophages through the chemokine receptors including ionic signals, Ca2+ elevations & protein kinase phosphorylation. In addition, activation through these pathways leads to release of inflammatory mediators that may contribute to further activation & cell recruitment. Furthermore, we found that gp120-activated macrophages produce factors that injure neurons, and identified specific MAP kinase pathways activated through chemokine receptor interactions responsible. This project will focus on mechanisms of gp120- elicited M/M activation in HIVE pathogenesis. Our hypothesis is that HIV-1 Env interacts with chemokine receptors on brain macrophage/microglia to trigger intracellular signaling cascades that lead to inappropriate activation, inflammatory mediator secretion, and neurotoxin production. The goals of this project are to better understand pathways elicited by HIV-1 Env in macrophages, and how these signaling cascades contribute to macrophage activation & dysfunction relevant to HIVE. We will: (1) Define the intracellular signals activated by HIV-1 through the chemokine receptors in primary human macrophages; (2) Determine the specific pathways involved in HIV-elicited macrophage cytokine & neurotoxin production; and (3) Identify signaling pathways linked to primary, viruses & primary cells directly relevant to HIVE pathogenesis, using primary isolates derived from HIVE tissue, and primary human brain-derived macrophage/microglia to validate results obtained in monocyte-derived macrophages. We anticipate that these studies will provide insight into the afferent mechanisms of M/M activation & neurotoxin production in HIVE and, ultimately, provide a rational basis for targeted strategies to interfere with this process.