Viral Host Interactions in SIV Cardiac Dysfunction

描述(申请人提供)：艾滋病毒相关性心肌病是一种常见和严重的艾滋病毒并发症，但其潜在的病理生理学知之甚少。有趣的是，先前的研究将SIV作为神经艾滋病的模型，强烈地暗示巨噬细胞的渗透和激活是导致神经退化的关键机制。类似的过程可能发生在心脏，如果是这样的话，触发基质金属蛋白酶的激活，这在心腔重塑中发挥重要作用。因此，这一建议的中心假设是，SIV感染猕猴发生的功能性心脏损伤是由于SIV感染导致心脏中与巨噬细胞渗透和激活相关的选择性基质金属蛋白酶(MMPs)的合成和激活增加所致。这些研究将确定心功能下降的时间进程及其与巨噬细胞激活、SIV复制和基质金属蛋白酶活性的关系，并确定激活基质金属蛋白酶的主要信号级联反应，从而在心肌病的发生发展中发挥作用。目的1：通过对SIV感染猕猴心功能的综合分析，探讨SIV感染猕猴心功能障碍的演变过程，明确心功能障碍与心肌巨噬细胞激活等炎症反应之间的关系。心内膜心肌活检和死后组织标本将通过免疫组织化学染色和定量图像分析检测宿主炎症反应和心肌细胞损伤，以与心功能状态进行比较。目的二：确定嗜巨噬细胞的SIV毒株在心脏内的复制是否是心功能障碍发生的先决条件。为了确定病毒复制与心脏病之间的关系，我们将通过实时定量RT-PCR测量心肌病毒载量，并确定心脏中主要的复制病毒基因类型，以与炎症反应(包括心肌巨噬细胞激活、基质金属蛋白酶(MMPs)产生和心功能不全的严重程度)进行比较。目的：探讨SIV感染心脏巨噬细胞是否刺激基质金属蛋白酶--特别是明胶酶MMP2、MMP9、间质胶原酶MMP1、MMP13、MMP12的激活，从而导致心功能不全。MMPs的组织抑制物(TIMPs)也将被量化，并通过原位分析来评估净酶蛋白活性。体外研究将测试SIV感染的培养巨噬细胞是否可以产生类似的基质金属蛋白酶合成和激活曲线，以确定存在于功能障碍心脏的特定SIV基因型的作用。这些研究将为在感染SIV的猕猴中进行干预性研究奠定基础，使用针对特定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.