Autocrine Sfrp1 inhibits fibroblast invasion during transition to injury induced myofibroblasts - daily profiling of mouse lungs after Bleomycin injury
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ABSTRACT: Fibroblast to myofibroblast conversion is a major driver of tissue remodeling in organ fibrosis. Here, we combined spatial transcriptomics, longitudinal single-cell RNA-seq and genetic lineage tracing to study fibroblast fates during mouse lung regeneration. We discovered a transitional fibroblast state characterized by high Sfrp1 expression, derived from both Tcf21-Cre lineage positive and negative cells. Sfrp1+ cells appeared early after injury in peribronchiolar, adventitial and alveolar locations and preceded the emergence of myofibroblasts. We identified lineage specific paracrine signals and inferred converging transcriptional trajectories towards Sfrp1+ transitional fibroblasts and Cthrc1+ myofibroblasts. Tgfβ1 downregulated Sfrp1 in non-invasive transitional cells and induced their switch to an invasive Cthrc1+ myofibroblast identity. Our study reveals the convergence of spatially and transcriptionally distinct fibroblast lineages into transcriptionally uniform myofibroblasts and identifies Sfrp1 as an autocrine inhibitor of fibroblast invasion during early stages of fibrogenesis.
Project description:Fibroblast to myofibroblast conversion is a major driver of tissue remodeling in organ fibrosis. Here, we combined spatial transcriptomics, longitudinal single-cell RNA-seq and genetic lineage tracing to study fibroblast fates during mouse lung regeneration. We discovered a transitional fibroblast state characterized by high Sfrp1 expression, derived from both Tcf21-Cre lineage positive and negative cells. Sfrp1+ cells appeared early after injury in peribronchiolar, adventitial and alveolar locations and preceded the emergence of myofibroblasts. We identified lineage specific paracrine signals and inferred converging transcriptional trajectories towards Sfrp1+ transitional fibroblasts and Cthrc1+ myofibroblasts. Tgfβ1 downregulated Sfrp1 in non-invasive transitional cells and induced their switch to an invasive Cthrc1+ myofibroblast identity. Our study reveals the convergence of spatially and transcriptionally distinct fibroblast lineages into transcriptionally uniform myofibroblasts and identifies Sfrp1 as an autocrine inhibitor of fibroblast invasion during early stages of fibrogenesis.
Project description:Fibroblast to myofibroblast conversion is a major driver of tissue remodeling in organ fibrosis. Several distinct lineages of fibroblasts support homeostatic tissue niche functions, yet, specific activation states and phenotypic trajectories of fibroblasts during injury repair have remained unclear. Here, we combined spatial transcriptomics, longitudinal single-cell RNA-seq and genetic lineage tracing to study fibroblast fates during mouse lung regeneration. We discovered a transitional fibroblast state characterized by high Sfrp1 expression, derived from both Tcf21-Cre lineage positive and negative cells. Sfrp1+ cells appeared early after injury in peribronchiolar, adventitial and alveolar locations and preceded the emergence of myofibroblasts. We identified lineage specific paracrine signals and inferred converging transcriptional trajectories towards Sfrp1+ transitional fibroblasts and Cthrc1+ myofibroblasts. Tgfβ1 downregulated Sfrp1 in non-invasive transitional cells and induced their switch to an invasive Cthrc1+ myofibroblast identity. Finally, using loss of function experiments we show that autocrine Sfrp1 directly inhibits fibroblast invasion by regulating the RhoA pathway. In summary, our study reveals the convergence of spatially and transcriptionally distinct fibroblast lineages into transcriptionally uniform myofibroblasts and identifies Sfrp1 as an autocrine inhibitor of fibroblast invasion during early stages of fibrogenesis.
Project description:Pericryptal myofibroblasts in the colon and rectum play an important role in regulating the normal colorectal stem cell niche and facilitating tumour progression. Myofibroblasts have previously mostly been distinguished from normal fibroblasts only by the expression of α smooth muscle actin (αSMA). We now identify AOC3, a surface monoamine oxidase, as a new marker of myofibroblasts by showing that it is the target protein of the myofibroblast reacting monoclonal antibody (mAb), PR2D3. The normal and tumour tissue distribution and the cell line reactivity of AOC3 match that expected for myofibroblasts. We have shown that the surface expression of AOC3 is sensitive to digestion by trypsin and collagenase and that anti-AOC3 antibodies can be used for FACS sorting of myofibroblasts obtained by non-enzymatic procedures. Whole genome microarray mRNA expression profiles of myofibroblasts and skin fibroblasts revealed four additional genes that are significantly expressed differentially between these two cell types; NKX2-3 and LRRC17 are expressed in myofibroblasts and SHOX2 and TBX5 in skin fibroblasts. Transforming Growth Factor β (TGFβ) substantially down-regulated AOC3 expression in myofibroblasts but not in skin fibroblasts, in which it dramatically increased the expression of αSMA. A knockdown of NKX2-3 in myofibroblasts caused a decrease of myofibroblast-related gene expression and an increased expression of the fibroblast associated gene, SHOX2, suggesting that NKX2-3 is a key mediator for maintaining myofibroblast characteristics. Our results show that colorectal myofibroblasts, as defined by the expression of AOC3, NKX2-3 and other markers, are a distinctly different cell type from TGFβ activated fibroblasts. colorectal myofibroblast specific markers and expression profiles were sought by comparing four primary myofibroblast cultures to a panel of four dermal and foreskin fibroblast cell lines Four primary myofibroblast cultures established from adult human colon compared to four skin fibroblast cell lines to identify intestinal myofibroblast specific markers
Project description:Idiopathic pulmonary fibrosis (IPF) is a fatal lung disease where invasive pulmonary myofibroblasts secrete collagen and destroy lung integrity. Here we show that IL-11 is upregulated in the lung of IPF patients, associated with disease severity and is secreted from IPF fibroblasts. In vitro, IL-11 stimulates lung fibroblasts to become invasive, ACTA2+ve, collagen secreting myofibroblasts, in an ERK-dependent fashion. In mice, fibroblast-specific transgenic expression or administration of Il-11 drives lung fibroblast-to-myofibroblast transformation and causes lung fibrosis. Il11ra1 deleted mice, whose lung fibroblasts are unresponsive to pro-fibrotic stimulation, are protected from fibrosis in the bleomycin mouse model of pulmonary fibrosis. We generated an IL-11 neutralising antibody that blocks lung fibroblast activation downstream of multiple stimuli and reverses myofibroblast activation. In therapeutic studies, anti-IL-11 treatment both prevented and reversed lung fibrosis, which was accompanied by diminished Erk activation. These data prioritise IL-11 as a drug target for lung fibrosis and IPF.
Project description:Idiopathic pulmonary fibrosis (IPF) is frequently diagnosed in elderly men. IPF is characterized by irreversible accumulation of excessive extracellular matrix components by activated myofibroblasts (aMYFs) leading to lung failure. Lineage tracing of alpha smooth muscle actin-positive (ACTA2+) cells in the context of bleomycin-induced pulmonary fibrosis in young mice has shown that activated myofibroblasts (aMYFs) are heterogeneous population. However, aMYFs heterogeneity and as well as their fate during fibrosis resolution in aged mice is still studied. Tg(Acta2-CreERT2), tdTomatoflox, 52-56 week-old mice were used to identify Acta2+ cells following bleomycin treatment (Bleo-Tam condition). At the peak of fibrosis formation (day 14) as well as during resolution (days 30 and 60), the origin and fate of Acta2+ cells converging on the aMYF/Cthrc1+ myofibroblast lineage were examined using scRNA-seq. Our findings demonstrate that at the peak of fibrosis day 14, aMYF/Cthrc1+ cells significantly recruited. Four subclusters within aMYF/Cthrc1+ exhibit distinct pro-fibrotic vs pro-alveologenic characteristics. During fibrosis formation and resolution, alveolar fibroblasts with a strong LIF-like signature are primarily responsible for the origin and fate of aMYFs. Finally, our findings indicate that a LIF-to-aMYF reversible switch is observed during the development and resolution of fibrosis in both young and old mice.
Project description:Fibrosis represents the uncontrolled replacement of parenchymal tissue with extracellular matrix (ECM) produced by myofibroblasts. While genetic fate-tracing and single-cell RNA-sequencing (scRNA-seq) technologies have helped elucidate fibroblast heterogeneity and ontogeny beyond fibroblast to myofibroblast differentiation, the novel identified fibroblast populations remain ill-defined, both in respect to the molecular cues driving their differentiation, and their subsequent role in fibrosis. Here we identify the metalloprotease ADAMTS12 in an unbiased manner as a fibroblast-specific gene that is strongly upregulated during fibrogenesis in mice and humans. In vivo knockout studies in mice confirmed that Adamts12 is critical during fibrogenesis in heart and kidney. Leveraging spatial transcriptomics, CRISPR-Cas9 gene editing and expression of catalytically active or inactive ADAMTS12 we demonstrate that the protease domain of Adamts12 controls fibrogenesis by licensing expansion and migration of a distinct fibroblast subset defined by Mt1 gene expression and strong JAK-STAT signaling.
Project description:Dynamic fibroblast state transitions underlie the heart’s fibrotic response, raising the possibility that tactical control of these transitions could alter maladaptive fibrotic outcomes. Transcriptome maturation by Muscleblind-like 1 (MBNL1) has emerged as a driver of differentiated cell states. Indeed, MBNL1 expression is elevated in conjunction with profibrotic transcripts in lineage traced myofibroblasts and modeling this gain in function by fibroblast-specific overexpression of an MBNL1 transgene induced a myofibroblast transcriptional identity in healthy hearts and promoted maladaptive myocyte remodeling and scar maturation following injury. Both fibroblast-specific and myofibroblast-specific loss of MBNL1 limited scar production and maturation, which was ascribed to negligible myofibroblast activity. MBNL1 deletion drove expansion of all quiescent cardiac fibroblast states and promoted mesenchymal stem cell characteristics while forced MBNL1 expression restricted state diversity by transitioning most fibroblasts to the most mature myofibroblast identity. These data suggest MBNL1 is a post-transcriptional switch controlling quiescent to myofibroblast transitions during cardiac wound healing.
Project description:Myofibroblasts are the major cellular source of collagen, and their accumulation – via differentiation from fibroblasts and resistance to apoptosis – is a hallmark of tissue fibrosis. Clearance of myofibroblasts by de-differentiation and restoration of apoptosis sensitivity has the potential to reverse fibrosis. Prostaglandin E2 (PGE2) and mitogens such as fibroblast growth factor-2 (FGF2) have each been shown to de-differentiate myofibroblasts, but the resultant cellular phenotypes have neither been comprehensively characterized nor compared. Here we show that PGE2 elicited de-differentiation of human lung myofibroblasts via cAMP/PKA while FGF2 utilized MEK/ERK. The two mediators yielded transitional cells with distinct transcriptomes, with FGF2 promoting but PGE2 inhibiting proliferation and survival. The gene expression pattern in fibroblasts isolated from the lungs of mice undergoing resolution of experimental fibrosis resembled that of myofibroblasts treated with PGE2 in vitro. We conclude that myofibroblast de-differentiation can proceed via distinct programs exemplified by treatment with PGE2 and FGF2, with that occurring in vivo most closely resembling the former.
Project description:Myofibroblasts are the major cellular source of collagen, and their accumulation – via differentiation from fibroblasts and resistance to apoptosis – is a hallmark of tissue fibrosis. Clearance of myofibroblasts by de-differentiation and restoration of apoptosis sensitivity has the potential to reverse fibrosis. Prostaglandin E2 (PGE2) and mitogens such as fibroblast growth factor-2 (FGF2) have each been shown to de-differentiate myofibroblasts, but the resultant cellular phenotypes have neither been comprehensively characterized nor compared. Here we show that PGE2 elicited de-differentiation of human lung myofibroblasts via cAMP/PKA while FGF2 utilized MEK/ERK. The two mediators yielded transitional cells with distinct transcriptomes, with FGF2 promoting but PGE2 inhibiting proliferation and survival. The gene expression pattern in fibroblasts isolated from the lungs of mice undergoing resolution of experimental fibrosis resembled that of myofibroblasts treated with PGE2 in vitro. We conclude that myofibroblast de-differentiation can proceed via distinct programs exemplified by treatment with PGE2 and FGF2, with that occurring in vivo most closely resembling the former.