Molecular biology and mechanics of cardiac interstitium

描述(申请人提供)：急性冠状动脉闭塞(CO)导致心肌细胞死亡和细胞外基质降解。大多数存活于心肌梗死(毫升)的患者都有残留的疤痕。我们将验证这样的假设：“冠状动脉闭塞后48小时内，通过改变梗塞心肌的机械性能，胶原降解会影响随后形成的瘢痕内胶原的合成，从而决定了早期(3周)和晚期(6周)的室性瘢痕的结构和功能”。我们计划：1)表征CO环境下基质金属蛋白酶(MMPs)的早期激活和胶原降解的相关因素，包括MMPs、纤溶酶和肿瘤坏死因子-a(TNF-a)的机械激活；2)确定早期胶原降解的程度与梗死区材料特性的关系；3)确定演变中的瘢痕局部变形与愈合组织中胶原合成的关系。我们将研究以下目标。目的1.慢性阻塞性肺疾病(CO)后48h内，基质金属蛋白酶诱导的胶原降解是由于肿瘤坏死因子-α、拉伸、纤溶酶对基质金属蛋白酶的独立诱导/激活作用以及对胶原纤维的机械破坏所致。我们将使用各种药理学方法来确定机械扩张、纤溶酶和肿瘤坏死因子-α在调节血清和心肌标本中胶原分解产物和基质金属蛋白酶活性方面的作用。目的2.CO后48小时内胶原的降解决定了未成熟(3周)胶原瘢痕的结构和功能特性以及随后的胶原沉积。通过对猪和小鼠CO的药物干预，我们将干扰MMPs的特定激活物或胶原的分解活性，并定量测定I型胶原的转录以及缺血区和早期瘢痕的结构/功能。目的3.成熟的(6周)心脏瘢痕的结构和功能依赖于早期(lt；48h)胶原的降解程度，在较小程度上依赖于随后的胶原合成和交联性。利用药理学方法在CO术后48小时内降低基质金属蛋白酶的活性，我们认为，在成熟的瘢痕中，纤维化以及整个纤维和交叉纤维的僵硬程度将会减弱，这些事件将由对原始胶原基质的早期损害程度来定义。缺血面积和6周的瘢痕结构/功能将按目标2进行评估。

DESCRIPTION (provided by applicant): Acute coronary occlusion (CO) results in myocyte cell death and degradation of the extracellular matrix. Most patients who survive a myocardial infarction (Ml) have a residual scar. We will test the hypothesis that: "Collagen degradation within the first 48 h after coronary occlusion by changing the mechanical properties of the infarcted myocardium influences the ensuing collagen synthesis within the evolving scar and thus, determines the early (3 week) and late (6 week) structure and function of the ventricular scar". We plan to: 1) characterize factors involved in the early activation of matrix metalloproteinases (MMPs) and collagen degradation in the setting of CO including the mechanical activation of MMPs, plasmin and tumor necrosis factor-a (TNF-a), 2) determine the relationship between the extent of early collagen degradation and the material properties of the infarcted area and, 3) determine the relationship between local deformation in the evolving scar and collagen synthesis in the healing tissue. We will examine the following aims. Aim 1. MMP induced collagen degradation within 48 h after CO is due to TNF-a, stretch, plasmin dependent and independent inducing/activating actions on MMPs and to the mechanical disruption of collagen fibers. We will use various pharmacological approaches following CO in pigs to determine the role of mechanical distention, plasmin and TNF-a have on modulating collagen breakdown products and MMP activity in serum and in myocardial samples. Aim 2. Collagen degradation within 48 h after CO determines th6 structural and functional properties of the immature (3 week) collagenous scar and the ensuing collagen deposition. Using pharmacological interventions in pigs and mice undergoing CO we will interfere with specific activators of MMPs or collagen breakdown activities and quantify collagen type I transcription as well as the structure/function of the ischemic area and early scar. Aim 3. The structure and function of the mature (6 week) cardiac scar is dependent on the degree of early (< 48 h) degradation of collagen and to a lesser extent on their ensuing synthesis and crosslinking of collagen. Using pharmacological approaches to reduce MMP activity within the first 48 h after CO we propose that fibrosis and as a consequence overall fiber- and cross-fiber stiffness will be attenuated in the mature scar and that these events will be defined by the extent of early damage to the original collagen matrix. lschemic area and 6 week scar structure/function will be assessed as in aim 2.