Fibroblast polarization over the myocardial infarction time continuum shifts roles from inflammation to angiogenesis

Abstract

Cardiac fibroblasts are the major producers of extracellular matrix (ECM) to form infarct scar. We hypothesized that fibroblasts undergo a spectrum of phenotype states over the course of myocardial infarction (MI) from early onset to scar formation. Fibroblasts were isolated from the infarct region of C57BL/6J male mice (3–6 months old, n = 60) at days 0 (no MI control) and 1, 3, or 7 after MI. Whole transcriptome analysis was performed by RNA-sequencing. Of the genes sequenced, 3371 were differentially expressed after MI. Enrichment analysis revealed that MI day 1 fibroblasts displayed pro-inflammatory, leukocyte-recruiting, pro-survival, and anti-migratory phenotype through Tnfrsf9 and CD137 signaling. MI day 3 fibroblasts had a proliferative, pro-fibrotic, and pro-angiogenic profile with elevated Il4ra signaling. MI day 7 fibroblasts showed an anti-angiogenic homeostatic-like myofibroblast profile and with a step-wise increase in Acta2 expression. MI day 7 fibroblasts relied on Pik3r3 signaling to mediate Tgfb1 effects and Fgfr2 to regulate PI3K signaling. In vitro, the day 3 MI fibroblast secretome stimulated angiogenesis, while day 7 MI fibroblast secretome repressed angiogenesis through Thbs1 signaling. Our results reveal novel mechanisms for fibroblasts in expressing pro-inflammatory molecules and regulating angiogenesis following MI.Electronic supplementary materialThe online version of this article (10.1007/s00395-019-0715-4) contains supplementary material, which is available to authorized users.

cellHarmony: Cell-level matching and holistic comparison of single-cell transcriptomes

“…Moreover, examination of the predicted transcriptional regulatory networks for each specific cell-state comparison identifies well-defined MI-associated gene expression differences in human Fibroblasts (upregulation of Col1a1,Col1a2,Col3a1,Col4a2,Col5a1,Col5a2 [Collagen scar] Fn1, Thbs1, Mmp14) along with novel implicated regulators which agree with prior literature (Fig. 4F) (van Dijk et al 2008;Spinale et al 2013;Frangogiannis 2017;Mouton et al 2019). While the two central transcriptional nodes in this network, Hif1a and Runx1, have been previously implicated in MI and even as possible targets for therapy, these markers have not been explicitly associated with the MI fibroblasts (Kido et al 2005;Semenza 2014;McCarroll et al 2018).…”

Computational Model Predicts Paracrine and Intracellular Drivers of Fibroblast Phenotype After Myocardial Infarction

“…We identified three mechanisms by which IL1 can attenuate TGFβ-induced collagen expression: the IL6 pathway, p38 signaling, and BAMBI upregulation. Examination of both bulk RNA-seq from fibroblasts post-MI and single-cell RNA-seq from Wnt-expressing fibroblasts post-MI shows increased expression of BAMBI in the proliferative phase [19, 66]. Further, BAMBI knockout enhanced profibrotic responses in TGFβ-stimulated cardiac fibroblasts or after transverse aortic constriction in vivo [67].…”

“…This “transient fibrosis” is likely facilitated by many different factors including inflammatory cell phenotype and number, the pre-infarct signaling state, the size of the infarct, and the health of the remaining cardiac vessels [17, 18]. Fibroblasts play a prominent role throughout the entire wound healing process, and therefore present a good system for studying how cells respond to the dynamic signaling environment of wound healing[19]. Additionally, understanding how fibroblasts respond during the different phases of wound healing could identify mechanisms by which fibrosis develops in other organs.…”

Multiscale Coupling of an Agent-Based Model of Tissue Fibrosis and a Logic-Based Model of Intracellular Signaling

“…Post-MI cardiac wound healing is a complex and dynamic process with many overlapping phases. The cardiac fibroblast is the key effector cell throughout the phases of wound healing that creates and remodels scar tissue (Spinale et al, 2016;Mouton et al, 2019). However, fibroblasts are a highly dynamic and plastic cell type that can transition from a proinflammatory phenotype in the early phases of wound healing to an anti-inflammatory and pro-fibrotic phenotype later in the wound healing cascade (Chen and Frangogiannis, 2013;Mouton et al, 2019).…”

“…The cardiac fibroblast is the key effector cell throughout the phases of wound healing that creates and remodels scar tissue (Spinale et al, 2016;Mouton et al, 2019). However, fibroblasts are a highly dynamic and plastic cell type that can transition from a proinflammatory phenotype in the early phases of wound healing to an anti-inflammatory and pro-fibrotic phenotype later in the wound healing cascade (Chen and Frangogiannis, 2013;Mouton et al, 2019). Fibroblast response to single cytokine inputs are well-documented (Fredj et al, 2005;Fix et al, 2011;Turner, 2014), but fibroblast activation and cytokine secretion in response to multiple cytokines and other stimuli in vivo that shift over the time course of MI wound healing are not well-described (Ma et al, 2017).…”