Role of collagen heterogeneity in remodeling of acute and chronic heart scars

项目总结/摘要 哺乳动物的心脏在缺血性心脏损伤后再生能力差，通过瘢痕愈合 阵多项临床研究表明，瘢痕组织的大小是一个独立的预测因子， 急性心肌梗死后的心血管结局和死亡率。然而，人们对 调节急性缺血性心脏损伤后纤维化程度或瘢痕组织大小的因素。胶原 是缺血性心脏损伤后差异上调最多的基因， 细胞外基质（ECM）蛋白质的一种形式，在梗塞的心脏中分泌。I型和III型胶原蛋白是 心脏中发现的主要胶原蛋白，但我们表明，大量的胶原蛋白， 在缺血性心脏损伤后，在未损伤心脏中表达的蛋白质被强烈诱导。在本提案中，我们 研究胶原蛋白异质性的生理必要性，并证明V型胶原蛋白， 纤维状胶原蛋白在调节缺血性心脏损伤后瘢痕组织的大小方面起关键作用。使用 多重RNA-FISH（荧光原位杂交）或MERFISH，我们创建了一个胶原蛋白的地图， 心脏，并使用遗传功能丧失技术，以确定V型胶原蛋白的功能意义， 调节梗死后瘢痕组织的大小和心脏功能。我们确定化学成分是如何 的ECM变化后，V型胶原删除，研究改变基质的力学生物学特性 并研究这些变化如何影响心脏功能和心肌壁应力分布。我们解剖 通过V型胶原调节瘢痕大小的分子机制。我们证明V型 胶原缺失与梗塞心脏中心脏成纤维细胞的深度激活有关， 增强的肌成纤维细胞活化是继发于心肌细胞上整合素表达谱的改变， 成纤维细胞我们研究了整合素表达改变的机制，整合素介导的驱动机制， 肌成纤维细胞活化，并确定特异性整合素的抑制是否可以挽救肌成纤维细胞的表型。 在V型胶原缺乏状态下观察到梗死后瘢痕形成增加。综合考虑，我们的建议将 导致对心脏伤口愈合更广泛的理解，并阐明了心脏修复的新范例 其中心脏疤痕的结构成分调节疤痕本身的大小。

Project Summary/Abstract The mammalian heart possesses a poor ability to regenerate after ischemic cardiac injury and heals via scar formation. Multiple clinical studies have demonstrated that the size of scar tissue is an independent predictor of cardiovascular outcomes and mortality after acute myocardial infarction. However, little is understood about factors that regulate the degree of fibrosis or size of scar tissue after acute ischemic cardiac injury. Collagens are the most differentially upregulated genes following ischemic cardiac injury and remain the most abundant form of extracellular matrix (ECM) proteins secreted in the infarcted heart. Type I and III collagens are the principal collagens found in the heart but we show that a large number of collagens that are minimally expressed in the uninjured heart are robustly induced following ischemic cardiac injury. In this proposal, we investigate the physiological necessity of collagen heterogeneity and demonstrate that type V collagen, a fibrillar collagen plays a critical role in regulating the size of scar tissue after ischemic cardiac injury. Using multiplexing of RNA-FISH (fluorescence in situ hybridization) or MERFISH, we create a collagen map of the heart and use genetic loss of function techniques to determine the functional significance of type V collagen in regulating the size of post infarct scar tissue and heart function. We determine how the chemical composition of ECM changes following type V collagen deletion, study the mechano-biological properties of altered matrix and examine how such changes affect cardiac function and distribution of myocardial wall stress. We dissect the molecular mechanisms mediating regulation of scar size by type V collagen. We demonstrate that type V collagen deletion is associated with profound activation of cardiac fibroblasts in the infarcted heart and show that augmented myofibroblast activation is secondary to an altered integrin expression profile on cardiac fibroblasts. We study the mechanisms of altered integrin expression, integrin mediated mechanisms driving myofibroblast activation and determine whether inhibition of specific integrins can rescue the phenotype of increased post infarct scarring observed in type V collagen deficient states. Taken together, our proposal will lead to a broader understanding of cardiac wound healing and illustrate a new paradigm of cardiac repair where the structural constituents of heart scars regulate the size of scar itself.