Viral Host Interactions in SIV Cardiac Dysfunction

描述（由申请人提供）：HIV相关心肌病是一种常见且严重的HIV并发症，但其潜在的病理生理机制尚不清楚。有趣的是，先前的研究将SIV作为神经艾滋病的模型，强烈暗示巨噬细胞的浸润和激活是神经变性的关键机制。类似的过程可能发生在心脏，如果是这样，就会触发在心室重构中起重要作用的基质金属蛋白酶的激活。因此，该建议的中心假设是SIV感染猕猴的功能性心脏损伤是由选择性基质金属蛋白酶（MMPs）的合成和激活增加引起的，这些选择性基质金属蛋白酶（MMPs）与SIV感染引起的巨噬细胞浸润和激活相关。拟议的研究将确定心功能下降的时间过程及其与巨噬细胞激活、SIV复制和MMP活性的关系，并确定激活MMPs在心肌病发展中起作用的主要信号级联。目的一：通过综合序列回声多普勒和压力-容积关系分析，确定siv感染猕猴心功能障碍的演变，明确心功能障碍与心肌巨噬细胞活化等心脏炎症反应的关系。通过免疫染色和定量图像分析，在心内膜活检和死后组织样本中测量宿主炎症反应和心肌细胞损伤，并与心功能状态进行比较。目的二：确定嗜巨噬细胞SIV毒株在心脏中的复制是否是心功能障碍发生的先决条件。为了建立病毒复制与心脏病之间的关系，我们将通过实时RT-PCR测量心肌病毒载量，并鉴定心脏中主要的复制病毒基因型，以比较炎症反应，包括心肌巨噬细胞的激活、基质金属蛋白酶（MMP）的产生和心功能障碍的严重程度。目的三：确定基质金属蛋白酶的活化，特别是明胶酶MMP2和MMP9，间质胶原酶MMP1和MMP13，以及MMP12（巨噬细胞金属弹性酶）是否被siv感染的心脏巨噬细胞刺激并导致心功能障碍。MMPs的组织抑制剂（TIMPs）也将被量化，并通过原位测定评估净酶蛋白酶活性。体外研究将测试SIV感染的培养巨噬细胞是否能产生类似的MMP合成和激活谱，以确定存在于功能失调心脏中的特定SIV基因型的作用。这些研究将为在siv感染的猕猴中进行干预性研究奠定基础，使用靶向特定MMPs的方法来预防心功能障碍。

DESCRIPTION (provided by applicant): HIV-associated cardiomyopathy is a frequent and serious HIV complication, yet the underlying pathophysiology is poorly understood. Intriguingly, prior studies examining SIV as model for neuroAIDS have strongly implicated macrophage infiltration and activation as a key mechanism underlying neurodegeneration. A similar process may occur in the heart and, if so, trigger activation of matrix metalloproteinases that play an important role in chamber remodeling. Accordingly, the central hypothesis of this proposal is that functional cardiac impairment that develops in SIV-infected macaques results from both increased synthesis and activation of selective matrix metalloproteinases (MMPs) associated with macrophage infiltration and activation driven by SIV infection in the heart. The proposed studies will both define the temporal course of decline in cardiac function and its relationship to macrophage activation, SIV replication, and MMP activity, and determine the primary signaling cascades activating the MMPs that play a role in development of cardiomyopathy. There are 3 specific aims: Aim One: To determine the evolution of cardiac dysfunction in SIV-infected macaques based on comprehensive serial echo Doppler and pressure-volume relation analysis and to define the relationship between cardiac dysfunction and inflammatory responses in the heart including myocardial macrophage activation. Host inflammatory responses and cardiomyocyte damage will be measured in endomyocardial biopsy and postmortem tissue samples by immunostaining and quantitative image analysis to compare with cardiac functional status. Aim Two: To determine whether replication of macrophage-tropic SIV strains in the heart is a prerequisite for the development of cardiac dysfunction. To establish the relationship between viral replication and cardiac disease, we will measure myocardial viral load by real-time RT-PCR and identify the predominant replicating viral genotypes in the heart to compare with inflammatory responses including activation of myocardial macrophages, matrix metalloproteinase (MMP) production, and severity of cardiac dysfunction. Aim Three: To determine whether activation of matrix metalloproteinases- specifically gelatinases MMP2 and MMP9, interstitial collagenases MMP1 and MMP13, and MMP12 (macrophage metalloelastase)-are stimulated by SIV-infection of macrophages in the heart and lead to cardiac dysfunction. Tissue inhibitors of MMPs (TIMPs) will also be quantified, and net enzyme protease activity assessed by in situ assay. In vitro studies will test whether a similar profile of MMP synthesis and activation can be produced by SIV-infected cultured macrophages to define the role of specific SIV genotypes present in dysfunctional hearts. These studies will set the stage for performing interventive studies in SIV-infected macaques using approaches to target specific MMPs to prevent cardiac dysfunction.