Neuronal Survival, HIV-1 and Astrocyte-TIMP-1

描述（由申请人提供）：星形胶质细胞产生组织金属蛋白酶抑制剂(TIMP)-1在中枢神经系统稳态和炎症性疾病如hiv -1相关痴呆（HAD）中起重要作用。虽然最初发现TIMP-1是作为基质金属蛋白酶（MMPs）的抑制剂，但最近发现TIMP-1是一种促进细胞存活的多功能分子。MMP/TIMP失衡与几种神经炎性疾病有关。我们之前的研究独特地证明，HAD患者大脑中TIMP-1的水平降低。星形胶质细胞- timp -1的表达在急性和慢性炎症条件下受到不同的调节，急性水平升高，慢性水平降低。这些观察结果表明，在HAD中补充TIMP-1可能具有治疗价值。我们提出星形胶质细胞- timp -1通过神经营养活性和/或抗凋亡蛋白的激活来调节HAD中的神经元存活。TIMP-1神经保护可能涉及也可能不涉及MMPs。为了了解TIMP-1在HAD中的调节和神经保护机制，我们提出以下问题：

DESCRIPTION (provided by applicant): Astrocyte production of tissue inhibitor of metalloproteinase (TIMP)-1 plays an important role in central nervous system homeostasis and inflammatory diseases such as HIV-1-associated dementia (HAD). While originally discovered as an inhibitor of matrix metalloproteinases (MMPs), recently, TIMP-1 has emerged as a multifunctional molecule promoting cell survival. MMP/TIMP imbalance is implicated in several neuro-inflammatory diseases. Our previous studies uniquely demonstrate that HAD patients have reduced levels of TIMP-1 in the brain. Astrocyte-TIMP-1 expression is differentially regulated in acute and chronic inflammatory conditions with elevated levels in acute and diminished levels in chronic. These observations indicate that TIMP-1 replenishment in HAD may have therapeutic value. We propose that astrocyte-TIMP-1 regulates neuronal survival in HAD, either through neurotrophic activities and/or via activation of anti-apoptotic proteins. TIMP-1 neuroprotection may or may not involve MMPs. To understand the mechanisms of TIMP-1 regulation and neuroprotection in HAD, the following questions are proposed: 1. How is TIMP-1 regulated in immune-activated astrocytes at the molecular level and what is the temporal relationship between TIMP-1 expression and chronic glial activation? 2. What is the mechanism of TIMP-1-mediated neuronal survival? Is TIMP-1 neuroprotection mediated through interactions with MMP? 3. Can TIMP-1 be utilized as a therapeutic agent to attenuate HIV-1-mediated neurodegeneration? To address these questions, cellular and animal models for HAD will be utilized to mimic acute and chronic inflammatory disease processes. Laboratory in vitro systems consisting of primary human astrocytes, human neurons, neurotoxins, virus and viral proteins will be used. Molecular manipulations such as TIMP-1 promoter-luciferase reporter constructs, adenoviral infections and gene silencing with siRNA molecules will be used to examine TIMP-1 promoter elements and signal transduction pathways involved in astrocvte-TIMP-1 regulation and neuroprotective effects. Neuroprotective mechanisms of TIMP-1 including induction of anti-apoptotic pathways and neurotrophic activities will be evaluated. MMP-dependence of these phenomena will be investigated using TIMP-1 mutants with differential MMP binding abilities. To examine if TIMP-1 can attenuate neurodegeneration, adenoviral-expressed TIMP-1 will be delivered to areas of injury in an HIV encephalitis SCID mouse model using intra-cranial or intra-ventricular injections. These studies will shed light on glial inflammatory responses in HAD, unravel novel mechanisms of glial-neuronal interactions, and may uncover potential future therapeutic strategies for neurodegenerative diseases.