Elucidating fibroblast heterogeneity as a pathway to target organ fibrosis

阐明成纤维细胞异质性作为靶器官纤维化的途径

• 批准号: 9074784
• 负责人: Pampee P Young
• 金额: $ 29.49万
• 依托单位: VANDERBILT UNIVERSITY MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-06-03 至 2020-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9074784
• 关键词: Affect; BMP2 gene; Biological Assay; Cardiac; Cell Communication; Cells; Characteristics; Cicatrix; Collagen Type I; Complex; Cutaneous; Data; Deposition; Equilibrium; Extracellular Matrix; Fibroblasts; Fibrosis; Foundations; Gene Expression Profile; Genes; Goals; Granulation Tissue; Healed; Health; Healthcare; Heart; Heart failure; Heterogeneity; Homeostasis; In Vitro; Infarction; Inflammation; Injury; Kidney; Light; Measures; Mediating; Mediator of activation protein; Modeling; Molecular; Molecular Profiling; Morbidity - disease rate; Mus; Myocardial; Natural regeneration; Organ; Organ failure; Outcome; Pathogenesis; Pathway interactions; Phenotype; Physiological; Play; Population; Population Heterogeneity; Process; Proteins; Regulation; Research; Role; Signal Pathway; Signal Transduction; Skin; Skin injury; Smooth Muscle Actin Staining Method; Sorting - Cell Movement; Structure; Surgical Injuries; Target Populations; Testing; Time; Tissue Survival; Tissues; Transforming Growth Factor beta; Transgenic Mice; Traumatic injury; Wound Healing; angiogenesis; base; connective tissue growth factor; cost; healing; in vivo; inhibitor/antagonist; injured; injury and repair; insight; mouse model; novel; overexpression; paracrine; promoter; repaired; response; spatiotemporal; tissue repair; transcriptome sequencing; wound

 DESCRIPTION (provided by applicant): Following surgical or traumatic injury, organs and tissues can heal by regeneration but more often than not, the repair process is complicated by fibrosis, resulting in reduced function and eventually organ failure. Activated fibroblasts (FBs) are the central mediators of both repair and fibrosis making it difficult to target fibrosis withou affecting repair. It is now well accepted that FBs represent a heterogeneous population of cells, yet we have a poor understanding of the molecular, cellular and functional basis of this heterogeneity. Our preliminary data have identified two major and distinct activated FB populations in mouse heart, skin and kidney following injury: Fibroblast specific protein 1 (FSP1)-expressing FBs and α-smooth muscle actin (αSMA)-expressing FBs, which appear at different time points after injury and remained as discrete populations during the healing process. Using mice which express GFP under FSP1 or α-SMA promoters we isolated these activated FB populations post cardiac injury and compared the gene expression profile of each population to those of FBs isolated from the uninjured heart. RNA sequencing indicated distinct molecular signatures. Particularly, pro-fibrotic genes such as type I collagen (Col I) and TGFβ signaling were significantly upregulated in αSMA-FBs, whereas genes involved in cellular homeostasis, tissue remodeling and cell-cell communication were upregulated in FSP1-FBs. Several studies, including from our group, have suggested that Secreted Frizzled-related protein 2 (sFRP2), a putative wnt pathway inhibitor, mediates wound repair by inhibiting fibrosis. We developed a novel mouse model in which we can induce expression of sFRP2 in activated FBs following injury. We found that early post-injury sFRP2 activation resulted in reduced fibrosis after myocardial, kidney and skin injuries without inhibiting tissue repair. Interestingly, our preliminary data showed that sFRP2 inhibited Col I synthesis and TGFβ signaling (but not Wnt signaling) only in αSMA-FBs but not in FSP-1 FBs in vitro. As such, sFRP2 represents an anti-fibrotic paracrine factor which may reduce tissue fibrosis by exerting distinct molecular effects on the post-injury (i.e. activated) FB subtypes. At the conclusion of this research application we will have characterized the cellular and functional heterogeneity of the major injury-activated FB populations and also have elucidated the mechanistic basis of the pro-reparative, antifibrotic effects of sFRP2 via its targeted and distinct effects on α-SMA-expressing FBs.

 描述（由申请人提供）：在手术或创伤性损伤后，器官和组织可以通过再生愈合，但通常修复过程会因纤维化而复杂化，导致功能降低并最终导致器官衰竭。活化的成纤维细胞（FB）是修复和纤维化的中心介质，使得难以在不影响修复的情况下靶向纤维化。现在人们普遍认为FB代表了一个异质性的细胞群体，但我们对这种异质性的分子，细胞和功能基础的了解很少。我们的初步数据已经确定了损伤后小鼠心脏、皮肤和肾脏中两种主要且不同的活化FB群体：表达成纤维细胞特异性蛋白1（FSP 1）的FB和表达α-平滑肌肌动蛋白（αSMA）的FB，它们出现在损伤后的不同时间点，并在愈合过程中保持离散群体。使用在FSP 1或α-SMA启动子下表达GFP的小鼠，我们分离了这些心脏损伤后活化的FB群体，并将每个群体的基因表达谱与从未损伤心脏分离的FB的基因表达谱进行了比较。RNA测序显示了不同的分子特征。特别是，促纤维化基因如I型胶原（Col I）和TGFβ信号在α SMA-FB中显著上调，而参与细胞稳态、组织重塑和细胞-细胞通讯的基因在FSP 1-FB中上调。包括我们小组在内的几项研究表明，分泌性卷曲相关蛋白2（sFRP 2），一种公认的wnt通路抑制剂，通过抑制纤维化介导伤口修复。我们开发了一种新的小鼠模型，其中我们可以诱导sFRP 2在损伤后活化的FB中的表达。我们发现，损伤后早期sFRP 2激活导致心肌、肾脏和皮肤损伤后纤维化减少，而不抑制组织修复。有趣的是，我们的初步数据显示，sFRP 2在体外仅抑制α SMA-FB中的Col I合成和TGFβ信号传导（但不抑制Wnt信号传导），而不抑制FSP-1 FB中的Col I合成和TGF β信号传导。因此，sFRP 2代表抗纤维化旁分泌因子，其可通过对损伤后（即活化的）FB亚型施加不同的分子效应来减少组织纤维化。在本研究应用结束时，我们将表征主要损伤激活FB群体的细胞和功能异质性，并阐明sFRP 2通过其对表达α-SMA的FB的靶向和独特作用而发挥促修复、抗纤维化作用的机制基础。