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Hypertrophic scar (HS) is a chronic inflammatory skin disorder characterized by excessive deposition of extracellular matrix, and the mechanisms underlying their formation remain poorly understood. We analysed scRNA‐seq data from samples of normal skin and HS. Using the hdWGCNA method, key gene modules of fibroblasts in HS were identified. Non‐negative matrix factorization was employed to perform subtype analysis of HS patients using these gene modules. Multiple machine learning algorithms were applied to screen and validate accurate gene signatures for identifying and predicting HS, and a convolutional neural network (CNN) based on deep learning was established and validated. Quantitative reverse transcription‐polymerase chain reaction and western blotting were performed to measure mRNA and protein expression. Immunofluorescence was used for gene localization analysis, and biological features were assessed through CCK8 and wound healing assay. Single‐cell sequencing revealed distinct subpopulations of fibroblasts in HS. HdWGCNA identified key gene characteristics of this population, and pseudotime analysis was conducted to investigate gene variation during fibroblast differentiation. By employing various machine learning algorithms, the gene range was narrowed down to three key genes. A CNN was trained using the expression of these key genes and immune cell infiltration, enabling diagnosis and prediction of HS. Functional experiments demonstrated that THBS2 is associated with fibroblast proliferation and migration in HS and affects the formation and development of HS through the TGFβ1/P‐Smad2/3 pathway. Our study identifies unique fibroblast subpopulations closely associated with HS and provides biomarkers for the diagnosis and treatment of HS. [ABSTRACT FROM AUTHOR]

Background: Hypertrophic scar (HS) is caused by the abnormal proliferation of fibroblasts and excessive deposition of extracellular matrix (ECM). Emerging evidence demonstrates that c‐Maf positive M2 macrophages were mainly located in the hypertrophic scar tissues of proliferative phase. But whether c‐Maf positive M2 macrophages can promote hypertrophic scar formation through modulating hypertrophic scar fibroblasts remains elusive. Aims: The aim of this study is to investigate the effects of c‐Maf positive M2 macrophages on the biological behaviors and functions of hypertrophic scar fibroblasts and the potential mechanism. Methods: HE and Masson trichrome staining were used to examine the histological features of human hypertrophic scar. Immunofluorescence staining was employed to label and quantify the c‐Maf+/CD68+ M2 macrophages. CCK8, wound healing, and transwell assays were utilized to test the effects of c‐Maf overexpressed M2 macrophages or the cell culture supernatants on the proliferation and migration of hypertrophic scar derived fibroblasts (HFBs) and normal skin derived fibroblasts (NFBs). Western blot and qPCR were harnessed to test the expressions of COL1, COL3, and α‐SMA in the co‐cultivated fibroblasts and TGF‐β1 in the c‐Maf overexpressed M2 macrophages. Results: Increased number of c‐Maf+/CD68+ M2 macrophages were found in HS in contrast to the normal skin (NS). Elevated proliferation and migration were observed in the HFBs or NFBs co‐cultured with c‐Maf overexpressed macrophages or the cell culture supernatants. A higher mRNA and protein expressions of COL1, COL3, and α‐SMA were recorded in the HFBs co‐cultured with c‐Maf overexpressed macrophages or treated with its culture supernatants. In addition, augmented mRNA and protein expressions of TGF‐β1 were also investigated in the c‐Maf overexpressed macrophages. Conclusion: c‐Maf positive macrophages promote hypertrophic scar formation through regulating HFBs proliferation, migration, and ECM deposition via the secreted TGF‐β1. [ABSTRACT FROM AUTHOR]

Objective: Hypertrophic scarring is a common skin fibro‐proliferative disease, but currently there has no satisfactory drugs for anti‐scar treatments. Previous study showed that epigallocatechin gallate (EGCG), the main catechin in green tea, improved wound healing and tissue fibrosis in both rats and mice. In the present study, the therapeutic effects of EGCG on hypertrophic scar were analyzed using a rabbit ear hypertrophic scar model. Materials: A rabbit ear model of hypertrophic scarring was used. DMSO, 0.5 mg EGCG/wound, 1.0 mg EGCG/wound or triamcinolone were injected subcutaneously once a week for 4 weeks. The scar elevation index (SEI) was measured using HE staining images, the collagen fibers were examined by Masson' trichrome staining images, and the number of capillaries in hypertrophic scar were calculated by CD31 staining images. The mRNA levels in the scar tissues were detected by quantitative real‐time polymerase chain reaction (qRT‐PCR). Results: Gross observation and histological evaluation showed the inhibitory effects of EGCG on hypertrophic scar formation at both doses, and decreased scar height and SEI were detected. EGCG also attenuated the mean collagen area fraction and decreased the number of capillaries in scar tissues. qRT‐PCR revealed that EGCG significantly inhibited the mRNA expression of TGF‐β1, Col I, Col III, α‐SMA, and eNOS. Conclusion: EGCG may serve as a useful candidate therapeutic drug for hypertrophic scar via inhibiting fibrotic gene expression and suppressing angiogenesis. [ABSTRACT FROM AUTHOR]

The pathogenesis of hypertrophic scar (HS) is still poorly understood. Macrophages, especially the polarisation of that to M1 or M2, play a pivotal role in control of the degree of scar formation. Profiling of macrophage phenotypes in human specimens during long‐term period of wound healing and HS formation may provide valuable clinical evidence for understanding the pathology of human scars. Human wound and HS specimens were collected, the macrophage phenotype was identified by immunofluorescence, and biomarkers and cytokines associated with M1 and M2 macrophages were detected by RT‐PCR. The correlation between the macrophage phenotype and HS characteristics was analysed by linear regression analyses. We found excessive and persistent infiltration by M1 macrophages around the blood vessels in the superficial layer of the dermis at early wound tissues, whereas M2 macrophages predominated in later wound tissues and the proliferative phase of HS and were scattered throughout the dermis. The density of M1 macrophages was positively correlated with mRNA expression levels of tumour necrosis factor‐alpha (TNF‐α) and IL‐6. The density of M2 macrophages was positively correlated with ARG1 and negatively correlated with the duration of HS. The sequential infiltration by M1 macrophage and M2 macrophages in human wound and HS tissues was confirmed. [ABSTRACT FROM AUTHOR]

Highlights • We investigated the effects of UA on hypertrophic scarring in a rabbit ear model. • UA reduced the scar elevation index and ameliorated collagen accumulation. • UA inhibited HUVEC migration and tube formation and hypertrophic scar angiogenesis. • UA inhibited proliferation of both HUVECs and hypertrophic scar fibroblasts. • UA inhibits hypertrophic scar formation via suppression of scar angiogenesis. Abstract Hypertrophic scarring is a common condition in the Chinese population; however, there are currently no satisfactory drugs to treat the disorder. Previous studies showed that angiogenesis plays an important role in the early phase of hypertrophic scarring and inhibition of angiogenesis has been reported as an effective strategy for anti-hypertrophic scar therapy. A recent study showed that usnic acid (UA), an active compound found mainly in lichens, inhibited tumor angiogenesis both in vivo and in vitro. To investigate the therapeutic effects of UA on hypertrophic scarring and to explore the possible mechanism involved, a rabbit ear hypertrophic scar model was established. Scars were treated once a week for four weeks with UA, DMSO or triamcinolone acetonide acetate. Histological evaluation of hematoxylin and eosin staining indicated that UA significantly inhibited hypertrophic scar formation, with obvious reductions in scar height and coloration. The scar elevation index (SEI) was also evidently reduced. Masson's trichrome staining showed that UA significantly ameliorated accumulation of collagen tissue. Immunohistochemical analysis of CD31 expression showed that UA significantly inhibited scar angiogenesis. In vitro, UA inhibited endothelial cell migration and tube formation as well as the proliferation of both human umbilical vein endothelial cells and scar fibroblast cells. These results provide the first evidence of the therapeutic effectiveness of UA in hypertrophic scar formation in an animal model via a mechanism that involves suppression of scar angiogenesis. [ABSTRACT FROM AUTHOR]

Hypertrophic scar (HS) is a skin fibroproliferative disorder occurring after burns, surgeries or traumatic injuries, and it has caused a tremendous economic and medical burden. Its molecular mechanism is associated with the abnormal proliferation and transition of fibroblasts and excessive deposition of extracellular matrix. Cartilage intermediate layer protein 2 (CILP2), highly homologous to cartilage intermediate layer protein 1 (CILP1), is mainly secreted predominantly from chondrocytes in the middle/deeper layers of articular cartilage. Recent reports indicate that CILP2 is involved in the development of fibrotic diseases. We investigated the role of CILP2 in the progression of HS. It was found in this study that CILP2 expression was significantly higher in HS than in normal skin, especially in myofibroblasts. In a clinical cohort, we discovered that CILP2 was more abundant in the serum of patients with HS, especially in the early stage of HS. In vitro studies indicated that knockdown of CILP2 suppressed proliferation, migration, myofibroblast activation and collagen synthesis of hypertrophic scar fibroblasts (HSFs). Further, we revealed that CILP2 interacts with ATP citrate lyase (ACLY), in which CILP2 stabilizes the expression of ACLY by reducing the ubiquitination of ACLY, therefore prompting Snail acetylation and avoiding reduced expression of Snail. In vivo studies indicated that knockdown of CILP2 or ACLY inhibitor, SB-204990, significantly alleviated HS formation. CILP2 exerts a vital role in hypertrophic scar formation and might be a detectable biomarker reflecting the progression of hypertrophic scar and a therapeutic target for hypertrophic scar. • CILP2 stabilized the expression of ACLY expression by reducing ubiquitination of ACLY, thereby promoting Snail expression, which then promoted proliferation, migration, myofibroblast activation and collagen synthesis of hypertrophic scar fibroblasts. [ABSTRACT FROM AUTHOR]