Project description:Keloids comprise an inflammatory fibroproliferative skin disorder characterized by excessive scarring. Fibroblasts play a pivotal role in skin fibrosis, exhibiting heightened collagen deposition. To investigate the molecular drivers of excessive collagen deposition in keloid, we compared the transcriptome of keloids and adjacent normal skin which demonstrated significant shifts towards bone and cartilage lineages in keloids, along with RUNX2, a key regulator of osteogenic and chondrogenic differentiation, notably upregulated. We then confirmed elevated levels of RUNX2 protein and phosphorylated RUNX2 in keloid tissue and fibroblasts compared to normal skin and normal dermal fibroblasts. To delve into how RUNX2 overexpression could contribute to keloids pathogenesis, we performed siRNA-mediated knockdown of RUNX2 in keloid fibroblasts followed by mRNA-sequencing. The results revealed significant downregulation of collagen genes COL11A1, COL5A3, COL15A1, and COL6A6, in knock-down vs. control groups along with GO enrichment analysis showing perturbation of genes involved in collagen and ECM organization. Further functional studies utilizing Runx2-knockout mice confirmed downregulation of these collagen genes along with reduced dermis thickness and reduced total dermal collagen in Runx2-knockout vs. Runx2- wild mice. These findings underscore the critical contribution of RUNX2 to collagen remodeling in keloid and provide potential therapeutic target.
Project description:A hallmark of pulmonary fibrosis is aberrant activation of lung fibroblasts into pathological fibroblasts producing excessive extracellular matrix (ECM). Thus, identification of key regulator(s) driving the generation of pathological fibroblasts can inform effective countermeasures against disease progression. In this study, we show that Leptin Receptor (Lepr)+ fibroblasts arising during alveologenesis include Signal Peptide-CUB-EGF Domain-containing Protein 2 (Scube2)+ alveolar fibroblasts as a major constituent significantly contributing to collagen triple helix repeat containing 1 (Cthrc1)+ Periostin (Postn)+ pathological fibroblasts in two mouse models of pulmonary fibrosis. Genetic ablation of the Postn+ pathological fibroblasts attenuates fibrosis. Comprehensive analysis of single cell RNA sequencing (scRNA-seq) and single cell Assay for Transposase-Accessible Chromatin sequencing (scATAC-seq) reveal Runt related transcription factor 2 (RUNX2) as a key regulator of fibrotic genes. Consistently, conditional deletion of Runx2 with Lepr-CreERT2 or Scube2-CreERT2 reduces the generation of pathological fibroblasts, ECM deposition, and pulmonary fibrosis. Therefore, Lepr+ derived fibroblasts which include Scube2+ alveolar fibroblasts are a key source of pathological fibroblasts, and targeting Runx2 provides a potential treatment option for pulmonary fibrosis.
Project description:This study investigated the effects of extracellular matrix (ECM) rigidty on gene expression patterns in normal dermal fibroblasts (NDFs) and keloid dermal fibroblasts (KDFs). Cells were cultured on collagen coated polyacrylamide hydrogels with elastic moduli mimicking normal skin (8 kPa) or keloid scar tissue (214 kPa), and changes in gene expression were profiled using next-generation RNA-sequencing. Differential gene expression analysis identified overall significant differences in gene expression between the NDF and KDF populations. Despite high levels of inter-patient heterogeneity in the KDF samples, further principal components analysis revealed a subset of genes (PC5) that were specifically regulated by ECM rigidity. Gene set enrichment analysis of the PC5 genes identified classic pathways associated with mechanotransduction, including Hippo Signalling and Regulation of the Actin Cytoskeleton, as well as genes associated with the Autophagy pathway. Additional in vitro studies and human tissue staining confirmed the biomechanical regulation of autophagic flux in NDFs and KDFs and differential remodelling of the lysosome in KDFs and keloid scars. Together, these findings implicate autophagy and lysosomal remodelling as biomechanically dysregulated pathways in keloid fibroblasts, and these mechanisms may contribute to scar pathogenesis.
Project description:Keloid scars is a pathologic fibro-proliferative disorders of the skin, which exhibit abnormal phenotypes including fibroblasts proliferation and collagen deposits. There have been several treatments of keloids including conventional surgical therapies and adjuvant therapies, but a high recurrence rate of keloids was also observed after treatment. Quantitative proteomics approach has been proved an efficient approach to investigate pathological mechanism and novel biomarkers. In this study, we present a label-free quantitative proteomics analysis to explore differential protein expression profiles in normal skin and keloid scar tissues based on nano-liquid chromatography and tandem mass spectrometry (Nano-LC–MS/MS). The study results displayed a more comprehensive keloid protein expression landscape and provided novel pathological insight of keloid.
Project description:To further explore the expression of circular RNAs in keloid,we have completed the Arraystar Human circRNA Array V2 analysis of the 8 samples,including 4 patients-derived keloid dermal fibroblasts and 4 normal dermal fibroblasts.
Project description:Keloids are benign fibroproliferative tumours resulting from skin damage such as trauma, burns or surgery. Keloids are more prevalent in populations with darkly pigmented skin. Links between skin pigmentation and vitamin D production have been established and some studies indicate involvement of vitamin D signalling in keloid pathology. This study assessed the impact of paricalcitol (a selective vitamin D signalling activator) on fibroblasts derived from keloid and normal skin, to further investigate the role and potential clinical relevance of vitamin D signalling in keloid pathology. Analysis of keloid and normal skin tissue using immunohistochemistry demonstrated a significant reduction of nuclear vitamin D receptor (VDR) in keloid tissue. After treatment with paricalcitol, nuclear VDR was increased in both keloid and normal fibroblasts. RNA sequencing of normal fibroblasts treated with paricalcitol demonstrated significant changes in gene expression, with many upregulated genes identified to have anti-fibrotic effects. However, paricalcitol failed to alter gene expression in Keloid fibroblasts. To investigate this further, we performed RNA sequencing of normal and keloid fibroblasts and found that retinoid-X receptor α (RXRα), a key binding partner of VDR required for downstream transcriptional activation, is significantly downregulated in keloid fibroblasts. Our results indicate that paricalcitol can effectively activate VDR translocation to the nucleus but is unable to effect change at the transcriptional level in keloid fibroblasts, most likely due to the reduced expression of RXRα. This suggests Vitamin D signalling may be aberrant in keloids, and that supplementation with Vitamin D alone would likely be ineffective in restoring signalling. Keywords: Keloid, Vitamin D receptor, Paricalcitol, Retinoid-X receptor α
Project description:Keloids are wounding-induced fibroproliferative human tumor–like skin scars of complex genetic makeup and poorly defined pathogenesis. Fibroblasts are the principal mediator of fibroproliferative disorders. To reveal dynamic epigenetic and transcriptome changes of keloid fibroblasts, a vertical study from RNA-seq and ATAC-seq analyses followed by in vivo confirmation of candidate molecule expression and subsequent functional testing was carried out using an early passage, freshly isolated keloid fibroblast cell strain and its paired normal control. These keloid fibroblasts produce keloid-like scars in a plasma clot-based skin equivalent humanized keloid animal model. RNA-seq analysis reveals that Hepatic fibrosis is the most significant pathway followed by Wnt–b-catenin signaling, TGF-b signaling, regulation of the EMT pathway, the STAT3 pathway, and adherens junction signaling. ATAC-seq analysis shows that STAT3 signaling is the most active pathway in keloid fibroblasts, followed by Wnt signaling (Wnt5) and regulation of the EMT pathway. Immunohistochemistry confirms that activated STAT3, (Tyr705 phospho-STAT3) and/or b-catenin are upregulated in dermal fibroblasts of keloid clinical specimens and mature keloid skin equivalent implants from the humanized mouse model compared to the normal control. The effect of STAT3 signaling on keloid fibroblast collagen expression was further tested in plasma clot-based skin equivalents using Cucurbitacin I, a selective JAK2/STAT3 inhibitor. A non-linear dose response of Cucurbitacin I was observed in collagen type I expression indicating a likely role of STAT3 signaling pathway in keloid pathogenesis. This work also demonstrates the utility of the recently established humanized keloid mouse model in exploring the mechanism of keloid formation.
Project description:Keloid disease (KD) is a fibroproliferative cutaneous tumour characterised by heterogeneity, excess collagen deposition and aggressive local invasion. Normal and keloid scar tissues were analysed with a site-specific in situ approach through combined laser capture microdissection, as well as whole tissue biopsy and monolayer cell culture techniques.