HIV: gp120, Chemokine Receptors & Macrophage Activation

描述（由申请人提供）：HIV脑病（HIVE）的临床疾病与巨噬细胞/小胶质细胞（M/M）活化的程度密切相关，许多模型表明HIV-1诱导M/M释放可溶性介质，损伤神经元并具有炎症或趋化潜力。暴露于HIV-1 Env糖蛋白gp 120和直接感染都可以诱导这些反应。这些结果暗示了HIV引起的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& M/M响应HIV而释放的神经毒素。然而，关于HIV触发M/M激活和神经毒素释放的具体机制知之甚少，这是我们理解HIV神经发病机制的一个重要空白。为了进入细胞，HIV-1使用趋化因子受体CCR 5和CXCR 4，它们通常会响应细胞外刺激而触发激活和迁移。在上一个资助期支持的研究中，我们发现gp 120通过趋化因子受体在原代巨噬细胞中激发细胞内信号，包括离子信号，Ca 2+升高和蛋白激酶磷酸化。此外，通过这些途径的激活导致炎症介质的释放，这可能有助于进一步激活和细胞募集。此外，我们发现gp 120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激酶通路。本项目将重点研究gp 120诱导的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相关的巨噬细胞活化和功能障碍。我们将：（1）确定HIV-1通过原代人巨噬细胞趋化因子受体激活的细胞内信号;（2）确定HIV-1诱导巨噬细胞产生细胞因子和神经毒素的具体途径;和（3）使用来源于HIVE组织的原代分离物，鉴定与HIVE发病机制直接相关的原代病毒和原代细胞相关的信号传导途径，和原代人脑衍生的巨噬细胞/小胶质细胞，以验证在单核细胞衍生的巨噬细胞中获得的结果。我们预计，这些研究将提供深入了解M/M激活和神经毒素生产在HIVE的传入机制，并最终提供了一个合理的基础，有针对性的策略来干扰这一过程。

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.