Project description:Skin fibrotic disease representsa major global healthcare burden, characterized by fibroblast hyperproliferation and excessive accumulation of extracellular matrix.Fibroblasts are found to be heterogeneous in multiple fibrotic diseases,but the fibroblast heterogeneity of skin fibrotic diseases remains unknown.In this study, we performed single-cell RNA-seq in keloid, a paradigm of skin fibrotic diseases, andnormal scardermis tissues.Our results indicate thatkeloid and normal scar fibroblasts could be divided into 4 subpopulations: secretory-papillary, secretory-reticular, mesenchymal and pro-inflammatory.The percentage of mesenchymal fibroblast subpopulationincreased significantly in keloid compared to normal scar. Interestingly, we also found increasing mesenchymal fibroblast subpopulation in scleroderma, another skin fibrotic disease.Function studies showed that the mesenchymal fibroblasts promoted collagen synthesis of the other fibroblasts in keloid partiallythrough secreting POSTN. These findings will help us understandskin fibroticpathogenesis in depth,and provided potential target cells for fibrotic diseases therapies.
Project description:Skin fibrotic disease representsa major global healthcare burden, characterized by fibroblast hyperproliferation and excessive accumulation of extracellular matrix.Fibroblasts are found to be heterogeneous in multiple fibrotic diseases,but the fibroblast heterogeneity of skin fibrotic diseases remains unknown.In this study, we performed single-cell RNA-seq in keloid, a paradigm of skin fibrotic diseases, andnormal scardermis tissues.Our results indicate that keloid and normal scar fibroblasts could be divided into 4 subpopulations: secretory-papillary, secretory-reticular, mesenchymal and pro-inflammatory.The percentage of mesenchymal fibroblast subpopulationincreased significantly in keloid compared to normal scar. Interestingly, we also found increasing mesenchymal fibroblast subpopulation in scleroderma, another skin fibrotic disease.Function studies showed that the mesenchymal fibroblasts promoted collagen synthesis of the other fibroblasts in keloid partiallythrough secreting POSTN. These findings will help us understandskin fibroticpathogenesis in depth,and provided potential target cells for fibrotic diseases therapies.
Project description:Transforming growth factor-β (TGFβ) is a key mediator of fibroblast activation in fibrotic diseases including systemic sclerosis. Here we show that Engrailed 1 (EN1) is re-expressed in multiple fibroblast subpopulations in the skin of SSc patients. We characterize EN1 as a molecular amplifier of TGFβ signaling in myofibroblast differentiation: TGFβ induces EN1 expression in a SMAD3-dependent manner, and, in turn, EN1 mediates the pro-fibrotic effects of TGFβ. RNA sequencing demonstrates that EN1 induces a pro-fibrotic gene expression profile functionally related to the cytoskeleton organization and ROCK activation. EN1 regulates gene expression by modulating the activity of SP1 and other SP-transcription factors, as confirmed by ChIP-seq experiments for EN1 and SP1. Functional experiments confirm the coordinating role of EN1 on ROCK activity and the re-organization of cytoskeleton during myofibroblast differentiation both in standard fibroblast culture systems and in in vitro skin models. Consistently, mice with fibroblast-specific knockout of En1 demonstrate impaired fibroblast-to-myofibroblast transition and are partially protected from experimental skin fibrosis.
Project description:Transforming growth factor-β (TGFβ) is a key mediator of fibroblast activation in fibrotic diseases including systemic sclerosis. Here we show that Engrailed 1 (EN1) is re-expressed in multiple fibroblast subpopulations in the skin of SSc patients. We characterize EN1 as a molecular amplifier of TGFβ signaling in myofibroblast differentiation: TGFβ induces EN1 expression in a SMAD3-dependent manner, and, in turn, EN1 mediates the pro-fibrotic effects of TGFβ. RNA sequencing demonstrates that EN1 induces a pro-fibrotic gene expression profile functionally related to the cytoskeleton organization and ROCK activation. EN1 regulates gene expression by modulating the activity of SP1 and other SP-transcription factors, as confirmed by ChIP-seq experiments for EN1 and SP1. Functional experiments confirm the coordinating role of EN1 on ROCK activity and the re-organization of cytoskeleton during myofibroblast differentiation both in standard fibroblast culture systems and in in vitro skin models. Consistently, mice with fibroblast-specific knockout of En1 demonstrate impaired fibroblast-to-myofibroblast transition and are partially protected from experimental skin fibrosis.
Project description:Background: Skin homeostasis is mediated by dermal fibroblasts and is affected by aging. Although age-related heterogeneity in fibroblasts has been reported, the effects of donor and species on this heterogeneity are unclear. Methods: To analyze age-related transcriptomic changes in human dermal fibroblasts, single-cell RNA sequencing was performed on dermal fibroblasts (ASF-4 cells) collected from the inner forearm of a volunteer over three decades. Results: Four main cell subpopulations changed with donor age and showed proliferative, homeostasis, fibrotic, and senescence functional annotations. The downregulation of the expression of genes encoding key extracellular matrix production and mechanotransduction components decreased with donor age. Interestingly, dermal fibroblasts have two putative differentiation pathways: one that involves the acquisition of senescent properties and the acquisition of fibrotic properties without the suppression of proliferation. Aging induced fibroblast differentiation in a manner involving the acquisition of senescent properties. Conclusion:Reconciling the various aspects of fibroblast heterogeneity may provide insight into the mechanisms underlying human skin aging and associated phenomena, including wrinkles, sagging, delayed wound healing, and suppressed scar formation.
Project description:In adult mammals, skin wound healing has evolved to favor rapid repair through formation of fibrotic scar. Consequently, skin wounds are dysfunctional and lead to chronic disfigurement and disability, yet the biologic mechanisms that drive fibrosis and prevent tissue regeneration remain unknown. Here, we report that reindeer (Rangifer tarandus) antler velvet exhibits regenerative wound healing, whereas identical full-thickness injury in dorsal back skin forms fibrotic scar. This regenerative capacity is retained even following ectopic transplantation of velvet to a scar-forming site, demonstrating that this latent regenerative capacity is innate to velvet cells and independent of local factors derived from the growing antler. Single cell RNA-sequencing of uninjured skin revealed a marked divergence in resting fibroblast transcriptional states and immunomodulatory function. Uninjured velvet fibroblast shared a striking resemblance with human fetal fibroblasts whereas uninjured back skin fibroblasts exhibited an overrepresentation of pro-inflammatory genes resembling adult human fibroblasts. Identical skin injury resulted in site-specific fibroblast polarization; back fibroblasts exacerbated the inflammatory response, whereas velvet fibroblasts adopted an immunosuppressive state and reverted back to a regeneration-competent ground state. Consequently, velvet wounds exhibited reduced immune infiltrate, accelerated adoption of anti-inflammatory immune states and expedited resolution of immune response. This study demonstrates reindeer as a novel mammalian model to study adult skin regeneration (velvet) and scar formation (back skin) within the same animal. Our study underscores the importance of fibroblast heterogeneity in shaping local immune cell functions that ultimately polarize wound healing outcomes. Purposeful, acute modulation of fibroblast-mediated immune signaling represents an important therapeutic avenue to mitigate scar and improve wound healing.
Project description:In adult mammals, skin wound healing has evolved to favor rapid repair through the formation of fibrotic scar. These dermal scars are dysfunctional and may lead to chronic disfigurement and disability, yet the biologic mechanisms that drive fibrosis and prevent tissue regeneration remain unknown. Here, we report that reindeer (Rangifer tarandus) antler velvet exhibits regenerative wound healing, whereas identical full-thickness injury in dorsal back skin of the same animal forms fibrotic scar. This regenerative capacity is retained even following ectopic transplantation of velvet to a scar-forming site, demonstrating that this latent regenerative capacity is innate to velvet cells and independent of local factors derived from the growing antler. Single cell RNA-sequencing of uninjured skin revealed a marked divergence in resting fibroblast transcriptional states and immunomodulatory function. Uninjured velvet fibroblast shared a striking resemblance with human fetal fibroblasts whereas uninjured back skin fibroblasts exhibited an overrepresentation of pro-inflammatory genes resembling adult human fibroblasts. Identical skin injury resulted in site-specific fibroblast polarization; back fibroblasts exacerbated the inflammatory response, whereas velvet fibroblasts adopted an immunosuppressive state and reverted back to a regeneration-competent ground state. Consequently, velvet wounds exhibited an accelerated adoption of anti-inflammatory immune states and an expedited resolution of immune response. This study demonstrates reindeer as a novel comparative mammalian model to study both adult skin regeneration (velvet) and scar formation (back skin) within the same animal. Our study underscores the importance of fibroblast heterogeneity in shaping local immune cell functions that ultimately polarize wound healing outcomes. Purposeful, acute modulation of fibroblast-mediated immune signaling represents an important therapeutic avenue to mitigate scar and improve wound healing.
Project description:Project abstract: In adult mammals, skin wound healing has evolved to favor rapid repair through the formation of fibrotic scar. These dermal scars are dysfunctional and may lead to chronic disfigurement and disability, yet the biologic mechanisms that drive fibrosis and prevent tissue regeneration remain unknown. Here, we report that reindeer (Rangifer tarandus) antler velvet exhibits regenerative wound healing, whereas identical full-thickness injury in dorsal back skin of the same animal forms fibrotic scar. This regenerative capacity is retained even following ectopic transplantation of velvet to a scar-forming site, demonstrating that this latent regenerative capacity is innate to velvet cells and independent of local factors derived from the growing antler. Single cell RNA-sequencing of uninjured skin revealed a marked divergence in resting fibroblast transcriptional states and immunomodulatory function. Uninjured velvet fibroblast shared a striking resemblance with human fetal fibroblasts whereas uninjured back skin fibroblasts exhibited an overrepresentation of pro-inflammatory genes resembling adult human fibroblasts. Identical skin injury resulted in site-specific fibroblast polarization; back fibroblasts exacerbated the inflammatory response, whereas velvet fibroblasts adopted an immunosuppressive state and reverted back to a regeneration-competent ground state. Consequently, velvet wounds exhibited an accelerated adoption of anti-inflammatory immune states and an expedited resolution of immune response. This study demonstrates reindeer as a novel comparative mammalian model to study both adult skin regeneration (velvet) and scar formation (back skin) within the same animal. Our study underscores the importance of fibroblast heterogeneity in shaping local immune cell functions that ultimately polarize wound healing outcomes. Purposeful, acute modulation of fibroblast-mediated immune signaling represents an important therapeutic avenue to mitigate scar and improve wound healing.