Regulators of Myofibroblast State Stability & Fibrotic Responsiveness of the Heart

项目摘要 心脏纤维化是心脏肌肉细胞周围瘢痕组织的病理发展。它 几乎每一种心脏病都会发生，并迅速发展为心力衰竭。一项基本 纤维化的细胞决定因素是成纤维细胞向肌成纤维细胞的转变，肌成纤维细胞是纤维化的主要细胞。 纤维化基质的制造者。值得注意的是，肌成纤维细胞恢复到静止状态， 从一些伤害中恢复过来，纤维化也得到解决。来自肝脏和皮肤的新证据表明， 失活的肌成纤维细胞被引发重新激活，具有增强的纤维化反应性和创伤性。 作为对未来伤害的保护性适应的愈合能力。这从来没有在心里检查过， 但我们的初步数据表明，当恢复的心脏经历 第二次病理性压力鉴于心脏病是由累积的压力和 恢复后，心脏肌成纤维细胞可能经历多个失活和再活化循环， 推动界定这些过程，并确定如何管理它们。我们以前的工作 提示p38 MAPK调节肌成纤维细胞表型的稳定性和心脏的纤维化。 反应此外，最近的研究结果表明，p38抑制似乎使肌成纤维细胞失活， 使它们恢复平静。这一发现表明，我们可以使用实验性的p38扰动， 研究其对心脏纤维化反应的影响。两个全面 具体的目的将被用来检查总体假设，即p38调节肌成纤维细胞， 状态稳定性和失活的动力学和命运轨迹是长期纤维化的基础， 心脏的反应。在这里，单细胞RNA测序与肌成纤维细胞谱系相结合 用靶向获得或丧失p38功能工程化的报道小鼠将用于确定：（目的1） p38在调节肌成纤维细胞失活和解决心脏纤维化中的作用，以及（目的2） p38活性对失活的心肌成肌纤维细胞再活化、纤维化反应性和纤维化的影响 记忆这些目标将试图（A）定义心脏的过程和调节， 肌成纤维细胞失活和再活化，（B）以鉴定对 （C）鉴定失活的肌成纤维细胞的功能，它们的表观遗传 损伤的记忆，以及它们在增强心脏纤维化反应中的作用。

PROJECT SUMMARY Cardiac fibrosis is the pathologic development of scar tissue around the muscle cells of the heart. It occurs with nearly every form of heart disease and rapidly progresses the heart to failure. A fundamental cellular determinant of fibrosis is the transition of fibroblasts into myofibroblasts, which are the primary producers of fibrotic matrix. Notably, myofibroblast revert to quiescence as organs including the heart recover from some injuries and fibrosis resolves. New evidence from liver and skin suggests these deactivated myofibroblasts are primed to reactivate with enhanced fibrotic responsiveness and wound healing capabilities as a protective adaptation to future injury. This has never been examined in the heart, but our preliminary data suggests cardiac fibrosis more than doubles when recovered hearts experience a second bout of pathologic stress. Given heart disease develops from cumulative rounds of stress and recovery, cardiac myofibroblasts likely undergo multiple cycles of deactivation and reactivation providing impetus for delineating these processes and determining how they are regulated. Our previous work suggests that p38 MAPK regulates the stability of the myofibroblast phenotype and the heart's fibrotic response. Moreover, recent findings suggest p38 inhibition appears to deactivate myofibroblasts reverting them to quiescence. This finding suggests that we can use experimental p38 perturbations of the myofibroblast state to study its impact on the heart's fibrotic response. Hence two comprehensive specific aims will be used to examine the overarching hypothesis that p38 regulation of myofibroblast state stability and the kinetics and fate trajectory of deactivation underlies long-term fibrotic responsiveness of the heart. Here single cell RNA sequencing in combination with myofibroblast lineage reporter mice engineered with targeted gain or loss of p38 function will be used to determine: (Aim 1) the role of p38 in regulating myofibroblast deactivation and resolving cardiac fibrosis, and (Aim 2) the effects of p38 activity on deactivated cardiac myofibroblast reactivation, fibrotic responsiveness, and fibrotic memory. Together these aims will attempt (A) to define the process and regulation of cardiac myofibroblast deactivation and reactivation, (B) to identify compensatory responses to perturbations in myofibroblast activity, and (C) to identify the function of deactivated myofibroblasts, their epigenetic memories of injury, and their role in enhancing the heart's fibrotic responsiveness.