The role of Fli1 in myeloid cells and its contribution to cardiac fibrosis

摘要 心脏病是美国的主要死因，纤维化是大多数心脏病患者的常见终点。 疾病最近的研究表明，单核细胞和巨噬细胞是心脏纤维化的重要介质。 我们发现从系统性硬化症（SSc）分离的单核细胞中转录因子Fli 1水平降低， 患者，一种自身免疫性结缔组织疾病，其特征在于广泛的组织纤维化和纤维化 心肌病人心脏成纤维细胞和Fli 1耗竭的单核细胞的共培养导致有效的 骨髓细胞中半乳糖凝集素-3和替代活化标志物的诱导，以及 这一点被mTOR抑制剂雷帕霉素阻断。初步实验显示， 使用LysMCre小鼠通过Cre介导的重组删除单核细胞/巨噬细胞中的Fli 1 （LysMCre/Fli 1fl/fl）使小鼠易发生心肌纤维化。 基于已发表的数据和我们的初步结果，我们假设巨噬细胞中Fli 1缺乏 这些结果有助于SSc纤维化和心肌病，雷帕霉素可能会阻断这些作用。为了验证这一 根据这一假设，我们提出以下具体目标： 具体目标1：确定Fli 1缺失后导致纤维化的分子机制， 单核细胞/巨噬细胞。我们预计单核细胞/巨噬细胞中Fli 1的减少将导致单核细胞/巨噬细胞中Fli 1的增强。 迁移，心肌细胞肥大，并将通过Fli 1/galactoside促进细胞外基质的产生， 3/mTOR通路。 具体目标2：确定巨噬细胞中Fli 1的缺失是否会导致体内心肌病。我们 预期LysMCre/Fli 1fl/fl小鼠将具有增强的炎性浸润、心脏纤维化和舒张功能， 血管紧张素II反应性功能障碍，这将被雷帕霉素抑制。 具体目标3。研究髓样Fli 1是否在Ssc相关心肌病中发挥作用。我们预计 来自患有心肌病的SSc患者的单核细胞和巨噬细胞将显示与 LysMCre/Fli 1fl/fl巨噬细胞。 这些研究将使我们更好地了解心脏纤维化的分子机制 在SSc中，并确定未来SSc-心肌病的治疗是否应该靶向Fli 1和髓系 系统通过雷帕霉素，从而提供了潜在的更安全，更有效的疗法的基础。

ABSTRACT Heart disease is the leading cause of death in the USA and fibrosis is a common endpoint for most cardiac diseases. Recent research has shown monocytes and macrophages are important mediators of heart fibrosis. We found reduced levels of the transcription factor Fli1 in monocytes isolated from systemic sclerosis (SSc) patients, an autoimmune connective tissue disease characterized by widespread tissue fibrosis and fibrotic cardiomyopathy. Co-culture of human cardiac fibroblasts and Fli1 depleted monocytes resulted in potent induction of galectin-3, and alternative activation markers in myeloid cells, and abundant collagen deposition by fibroblasts, and this was blocked by the mTOR inhibitor Rapamycin. Preliminary experiments revealed that deletion of Fli1 in monocytes/macrophages via Cre-mediated recombination using LysMCre mice (LysMCre/Fli1fl/fl) predisposed mice to develop myocardial fibrosis. Based on published data and our preliminary results, we hypothesize that Fli1 deficiency in macrophages contributes to SSc fibrosis and cardiomyopathy, and that Rapamycin may block these effects. To test this hypothesis, we propose the following specific aims: Specific aim 1: Determine the molecular mechanism leading to fibrosis following Fli1 depletion in monocytes/macrophages. We expect that decreased Fli1 in monocytes/macrophages will result in enhanced migration, cardiomyocyte hypertrophy, and will promote the production of extracellular matrix via Fli1/galetin- 3/mTOR pathway. Specific aim 2: Determine whether loss of Fli1 in macrophages leads to cardiomyopathy in vivo. We expect that the LysMCre/Fli1fl/fl mice will have enhanced inflammatory infiltrates, heart fibrosis and diastolic dysfunction in response to Angiotensin II, which will be inhibited by Rapamycin. Specific aim 3. Investigate whether myeloid Fli1 has a role in SSc-associated cardiomyopathy. We expect that monocytes and macrophages from SSc patients with cardiomyopathy will display a similar phenotype to the LysMCre/Fli1fl/fl macrophages. The studies proposed should allow us to gain better understanding of the molecular mechanisms of heart fibrosis in SSc, and determine whether future treatments for SSc-cardiomyopathy, should target Fli1 and the myeloid system via Rapamycin, thus providing the basis for potentially safer, more effective therapies.