CILP2 promotes hypertrophic scar through Snail acetylation by interaction with ACLY

BACKGROUND & AIMS

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.

METHODS AND RESULTS

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.

CONCLUSION

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.

Patients with hypertrophic scars following severe burn injury express different long noncoding RNAs

OBJECTIVE

Research indicates that long noncoding RNAs (lncRNAs) contribute significantly to fibrotic diseases. Although lncRNAs may play a role in hypertrophic scars after burns, its mechanisms remain poorly understood.

METHODS

Using chip technology, we compared the lncRNA expression profiles of burn patients and healthy controls (HCs). Microarray results were examined by quantitative reverse-transcription polymerase chain reaction (RT-PCR) to verify their reliability. The biological functions of differentially expressed mRNAs and the relationships between genes and signaling pathways were investigated by Gene Ontology (GO) and pathway analyses, respectively.

RESULTS

In contrast with HCs, it was found that 2738 lncRNAs (1628 upregulated) and 2166 mRNAs (1395 upregulated) were differentially expressed in hypertrophic scars after burn. Results from RT-PCR were consistent with those from microarray. GO and pathway analyses revealed that the differentially expressed mRNAs are mainly associated with processes related to cytokine secretion in the immune system, notch signaling, and MAPK signaling.

CONCLUSION

The lncRNA expression profiles of hypertrophic scars after burn changed significantly compared with HCs. It was believed that the transcripts could be used as potential targets for inhibiting abnormal scar formation in burn patients.

miRSNP rs188493331: A key player in genetic control of microRNA-induced pathway activation in hypertrophic scars and keloids

BACKGROUND

Our study aims to delineate the miRSNP-microRNA-gene-pathway interactions in the context of hypertrophic scars (HS) and keloids.

MATERIALS AND METHODS

We performed a computational biology study involving differential expression analysis to identify genes and their mRNAs in HS and keloid tissues compared to normal skin, identifying key hub genes and enriching their functional roles, comprehensively analyzing microRNA-target genes and related signaling pathways through bioinformatics, identifying MiRSNPs, and constructing a pathway-based network to illustrate miRSNP-miRNA-gene-signaling pathway interactions.

RESULTS

Our results revealed a total of 429 hub genes, with a strong enrichment in signaling pathways related to proteoglycans in cancer, focal adhesion, TGF-β, PI3K/Akt, and EGFR tyrosine kinase inhibitor resistance. Particularly noteworthy was the substantial crosstalk between the focal adhesion and PI3K/Akt signaling pathways, making them more susceptible to regulation by microRNAs. We also identified specific miRNAs, including miRNA-1279, miRNA-429, and miRNA-302e, which harbored multiple SNP loci, with miRSNPs rs188493331 and rs78979933 exerting control over a significant number of miRNA target genes. Furthermore, we observed that miRSNP rs188493331 shared a location with microRNA302e, microRNA202a-3p, and microRNA20b-5p, and these three microRNAs collectively targeted the gene LAMA3, which is integral to the focal adhesion signaling pathway.

CONCLUSIONS

The study successfully unveils the complex interactions between miRSNPs, miRNAs, genes, and signaling pathways, shedding light on the genetic factors contributing to HS and keloid formation.

Identification and validation of CRLF1 and NRG1 as immune-related signatures in hypertrophic scar

BACKGROUND

Hypertrophic scar (HTS) is a prevalent chronic inflammatory skin disorder characterized by abnormal proliferation and extracellular matrix deposition and the precise mechanisms underlying HTS remain elusive. This study aimed to identify and validate potential immune-related genes associated with hypertrophic scar formation.

METHODS

Skin samples from normal (n = 12) and hypertrophic scar tissues (n = 12) were subjected to RNA-seq analysis. Differentially expressed genes (DEGs) and significant modular genes in Weighted gene Co-expression Network Analysis (WGCNA) were identified. Subsequently, functional enrichment analysis was performed on the intersecting genes. Additionally, eight immune-related genes were matched from the ImmPort database. Validation of NRG1 and CRLF1 was carried out using an external cohort (GSE136906). Furthermore, the association between these two genes and immune cells was assessed by Spearman correlation analysis. Finally, RNA was extracted from normal and hypertrophic scar samples, and RT-qPCR, Immunohistochemistry staining and Western Blot were employed to validate the expression of characteristic genes.

RESULTS

A total of 940 DEGs were identified between HTS and normal samples, and 288 key module genes were uncovered via WGCNA. Enrichment analysis in key module revealed involvement in many immune-related pathways, such as Th17 cell differentiation, antigen processing and presentation and B cell receptor signaling pathway. The eight immune-related genes (IFI30, NR2F2, NRG1, ESM1, NFATC2, CRLF1, COLEC12 and IL6) were identified by matching from the ImmPort database. Notably, we observed that activated mast cell positively correlated with CRLF1 expression, while CD8 T cells exhibited a positive correlation with NRG1. The expression of NRG1 and CRLF1 was further validated in clinical samples.

CONCLUSION

In this study, two key immune-related genes (CRLF1 and NRG1) were identified as characteristic genes associated with HTS. These findings provide valuable insights into the immune-related mechanisms underlying hypertrophic scar formation.

MiR-141-3p-Functionalized Exosomes Loaded in Dissolvable Microneedle Arrays for Hypertrophic Scar Treatment

Hypertrophic scar (HS) is a common fibroproliferative disease caused by abnormal wound healing after deep skin injury. However, the existing approaches have unsatisfactory therapeutic effects, which promote the exploration of newer and more effective strategies. MiRNA-modified functional exosomes delivered by dissolvable microneedle arrays (DMNAs) are expected to provide new hope for HS treatment. In this study, a miRNA, miR-141-3p, which is downregulated in skin scar tissues and in hypertrophic scar fibroblasts (HSFs), is identified. MiR-141-3p mimics inhibit the proliferation, migration, and myofibroblast transdifferentiation of HSFs in vitro by targeting TGF-β2 to suppress the TGF-β2/Smad pathway. Subsequently, the engineered exosomes encapsulating miR-141-3p (miR-141-3pOE -Exos) are isolated from adipose-derived mesenchymal stem cells transfected with Lv-miR-141-3p. MiR-141-3pOE -Exos show the same inhibitive effects as miR-141-3p mimics on the pathological behaviors of HSFs in vitro. The DMNAs for sustained release of miR-141-3pOE -Exos are further fabricated in vivo. MiR-141OE -Exos@DMNAs effectively decrease the thickness of HS and improve fibroblast distribution and collagen fiber arrangement, and downregulate the expression of α-SMA, COL-1, FN, TGF-β2, and p-Smad2/3 in the HS tissue. Overall, a promising, effective, and convenient exosome@DMNA-based miRNA delivery strategy for HS treatment is provided.

Comprehensive modular analyses of scar subtypes illuminate underlying molecular mechanisms and potential therapeutic targets

Pathological scarring resulting from traumas and wounds, such as hypertrophic scars and keloids, pose significant aesthetic, functional and psychological challenges. This study provides a comprehensive transcriptomic analysis of these conditions, aiming to illuminate underlying molecular mechanisms and potential therapeutic targets. We employed a co-expression and module analysis tool to identify significant gene clusters associated with distinct pathophysiological processes and mechanisms, notably lipid metabolism, sebum production, cellular energy metabolism and skin barrier function. This examination yielded critical insights into several skin conditions including folliculitis, skin fibrosis, fibrosarcoma and congenital ichthyosis. Particular attention was paid to Module Cluster (MCluster) 3, encompassing genes like BLK, TRPV1 and GABRD, all displaying high expression and potential implications in immune modulation. Preliminary immunohistochemistry validation supported these findings, showing elevated expression of these genes in non-fibrotic samples rich in immune activity. The complex interplay of different cell types in scar formation, such as fibroblasts, myofibroblasts, keratinocytes and mast cells, was also explored, revealing promising therapeutic strategies. This study underscores the promise of targeted gene therapy for pathological scars, paving the way for more personalised therapeutic approaches. The results necessitate further research to fully ascertain the roles of these identified genes and pathways in skin disease pathogenesis and potential therapeutics. Nonetheless, our work forms a strong foundation for a new era of personalised medicine for patients suffering from pathological scarring.

Non-coding RNAs in hypertrophic scars and keloids: Current research and clinical relevance: A review

Hypertrophic scars (HS) and keloids (KD) are lesions that develop as a result of excessive fibroblast proliferation and collagen deposition in response to dermal injury, leading to dysregulation of the inflammatory, proliferative, and remodeling phases during wound healing. HS and KD affect up to 90 % of the population and are associated with lower quality of life, physical health, and mental status in patients. Efficient targeted treatment represents a significant challenge, primarily due to our limited understanding of their underlying pathogenesis. Non-coding RNAs (ncRNAs), which constitute a significant portion of the human transcriptome with minimal or no protein-coding capacity, have been implicated in various cellular physiologies and pathologies and may serve as diagnostic indicators or therapeutic targets. NcRNAs have been found to be aberrantly expressed and regulated in HS and KD. This review provides a summary of the expression profiles and molecular mechanisms of three common ncRNAs, including microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs), in HS and KD. It also discusses their potential as biomarkers for the diagnosis and treatment of these diseases and provides novel insights into epigenetic-based diagnosis and treatment strategies for HS and KD.

Keloids are transcriptionally distinct from normal and hypertrophic scars

Wound healing and skin regeneration after injury are complex biological processes, and deep injuries with a high degree of tissue destruction may result in severe scar formation. Clinically, scars can be classified into normal, hypertrophic and keloid scars. However, the molecular signature of each scar type is currently not known. The aim of this study was to reveal the transcriptional landscape of normal, hypertrophic and keloid skin scars following hand and plastic surgery based on total RNA sequencing. Eighteen skin scar samples from hand and plastic surgeries of human donors were minced directly after removal and stored in TRIzol (Thermo Fisher, USA). Samples were then subjected to RNA isolation, cDNA library preparation, bulk RNA sequencing and bioinformatics analysis. We show that keloid scars transcriptionally differed from normal and hypertrophic scars. Normal and hypertrophic scars presented overlapping clustering, and eight genes were shown to be commonly expressed between hypertrophic and normal scars. No genes were specifically expressed at a higher level in keloid and normal scars. Based on gene ontology pathway analysis, genes with a higher level of expression in keloid scars lead to increased (extra-) cellular matrix proliferation and cell interaction. Moreover, tumour-like genes were more highly expressed in keloid scars, supporting the clinical impression of strong and diffuse growth. This study furthers our understanding of the classification of differential scar types based on molecular signature, which may shed light on new diagnostic and therapeutic strategies for keloid scars in the future.

Glycoprotein M6A upregulation detected by transcriptome analysis controls the proliferation of keloidal fibroblasts

Hypertrophic scars and keloids are fibroproliferative disorders caused by abnormal wound healing. Their exact cause has not been found, but abnormalities during the wound healing process including inflammatory, immune, genetic, and other factors are thought to predispose an individual to excessive scarring. In the present study, we performed transcriptome analysis of established keloid cell lines (KEL FIB), focusing on gene expression analysis and fusion gene detection for the first time. For gene expression analysis, fragments per kilobase per million map read values were calculated, which were validated by real-time PCR and immunohistochemistry. Fusion genes were predicted by transcriptome sequence, and validated by Sanger sequence and G-banding. As a result, GPM6A was shown in the expression analysis to be upregulated in KEL FIB compared with normal fibroblasts. The GPM6A upregulation in KEL FIB was confirmed by real-time PCR, and GPM6A messenger ribonucleic acid expression was consistently significantly elevated in the tissues of hypertrophic scar and keloid compared to normal skin. Immunohistochemistry also revealed that the number of fibroblast-like spindle-shaped cells positive for GPM6A was significantly increased in keloidal tissues. GPM6A inhibition by small interfering ribonucleic acid significantly reduced the number of KEL FIB. On the other hand, although we hypothesized that fusion genes are involved in the pathogenesis of keloids, the transcriptome analysis could not prove the presence of fusion genes in KEL FIB. Taken together, GPM6A upregulation may have an inducible effect on cell proliferation in keloidal fibroblasts. GPM6A can be a novel therapeutic target in hypertrophic scars and keloids. The inflammatory nature may be more prominent in the pathogenesis of keloids, rather than being skin tumors, as proposed by Ogawa et al. Future studies using several cell lines will be required.

miR-15a-5p up-regulates TLR4 and induces the formation of hypertrophic scars and keloids

The formation of hypertrophic scar and keloid is considered to be a very complex pathological process. Our previous studies have shown that miR-15a-5p is an important miRNA in HTS tissues, and its expression level is significantly increased. Therefore, the potential mechanism of action of miR-15a-5p in scarring arouses our interest. This study preliminarily investigated the expression level of miR-15a-5p in HTS tissue and normal skin tissue and further explored the molecular mechanism. The results of this study once again confirmed that the expression level of miR-15a-5p was increased in HTS tissues and cells, and the closely related mRNA and protein levels of MyD88 and TGF-β were also highly expressed. The relative expression levels of fibrosis-related indicators in HTsFb cells were up-regulated, such as collagen-Ⅰ, collagen-III and α-SMA. We constructed the HTS cell model and BALB/c nude animal model, and down-regulating miR-15a-5p, the HTsFb cells proliferation was inhibited, and qRT-PCR results showed that the fibrosis index mRNA was also reduced, and significantly reduce the pathological state of scar tissue. In conclusion, miR-15a-5p may participate in the formation and development of HTS through TLR/MyD88 signaling pathway and TGF-β1 signaling pathway.

Deciphering the contributions of cuproptosis in the development of hypertrophic scar using single-cell analysis and machine learning techniques

Hypertrophic scar (HS) is a chronic inflammatory skin disease characterized by excessive deposition of extracellular matrix, but the exact mechanisms related to its formation remain unclear, making it difficult to treat. This study aimed to investigate the potential role of cuproptosis in the information of HS. To this end, we used single-cell sequencing and bulk transcriptome data, and screened for cuproptosis-related genes (CRGs) using differential gene analysis and machine learning algorithms (random forest and support vector machine). Through this process, we identified a group of genes, including ATP7A, ULK1, and MTF1, as novel therapeutic targets for HS. Furthermore, quantitative real-time polymerase chain reaction (qRT-PCR) was conducted to confirm the mRNA expression of ATP7A, ULK1, and MTF1 in both HS and normal skin (NS) tissues. We also constructed a diagnostic model for HS and analyzed the immune infiltration characteristics. Additionally, we used the expression profiles of CRGs to perform subgroup analysis of HS. We focused mainly on fibroblasts in the transcriptional profile at single-cell resolution. By calculating the cuproptosis activity of each fibroblast, we found that cuproptosis activity of normal skin fibroblasts increased, providing further insights into the pathogenesis of HS. We also analyzed the cell communication network and transcription factor regulatory network activity, and found the existence of a fibroblast-centered communication regulation network in HS, where cuproptosis activity in fibroblasts affects intercellular communication. Using transcription factor regulatory activity network analysis, we obtained highly active transcription factors, and correlation analysis with CRGs suggested that CRGs may serve as potential target genes for transcription factors. Overall, our study provides new insights into the pathophysiological mechanisms of HS, which may inspire new ideas for the diagnosis and treatment.

[Research advances on the role and mechanism of microRNA in hypertrophic scar]

Hypertrophic scar (HS) affects the function and beauty of patients, and brings a heavy psychological burden to patients. However, the specific pathogenesis mechanism of HS in molecular biology level is not yet clear, and this disease is still one of the clinical diseases difficult to prevent and cure. MicroRNA (miR) is a family of single-stranded endogenous noncoding RNAs that can regulate gene expression. The abnormal transcription of miR in hypertrophic scar fibroblasts can affect the transduction and expression of downstream signal pathway or protein, and the exploration of miR and its downstream signal pathway and protein helps deeply understand the occurrence and development mechanism of scar hyperplasia. This article summarized and analyzed how miR and multiple signal pathways involve in the formation and development of HS in recent years, and further outlined the interaction between miR and target genes in HS.

MicroRNA-365a/b-3p as a Potential Biomarker for Hypertrophic Scars

The clinical aspects of hypertrophic scarring vary according to personal constitution and body part. However, the mechanism of hypertrophic scar (HS) formation remains unclear. MicroRNAs (miRNAs) are known to contribute to HS formation, however, their detailed role remains unknown. In this study, candidate miRNAs were identified and analyzed as biomarkers of hypertrophic scarring for future clinical applications. HSfibroblasts and normal skin fibroblasts from patients were used for profiling and validation of miRNAs. An HS mouse model with xenografted human skin on nude mice was established. The miRNA expression between normal human, normal mouse, and mouse HS skin tissues was compared. Circulating miRNA expression levels in the serum of normal mice and mice with HSs were also analyzed. Ten upregulated and twenty-one downregulated miRNAs were detected. Among these, miR-365a/b-3p and miR-16-5p were identified as candidate miRNAs with statistically significant differences; miR-365a/b-3p was significantly upregulated (p = 0.0244). In mouse studies, miR-365a/b-3p expression levels in skin tissue and serum were higher in mice with HSs than in the control group. These results indicate that miRNAs contribute to hypertrophic scarring and that miR-365a/b-3p may be considered a potential biomarker for HS formation.

In-depth examination of hyperproliferative healing in two breeds of Sus scrofa domesticus commonly used for research

Background

Wound healing can result in various outcomes, including hypertrophic scar (HTS). Pigs serve as models to study wound healing as their skin shares physiologic similarity with humans. Yorkshire (Yk) and Duroc (Dc) pigs have been used to mimic normal and abnormal wound healing, respectively. The reason behind this differential healing phenotype was explored here.

Methods

Excisional wounds were made on Dc and Yk pigs and were sampled and imaged for 98 days. PCR arrays were used to determine differential gene expression. Vancouver Scar Scale (VSS) scores were given. Re-epithelialization was analyzed. H&E, Mason's trichrome, and immunostains were used to determine cellularity, collagen content, and blood vessel density, respectively.

Results

Yk wounds heal to a "port wine" HTS, resembling scarring in Fitzpatrick skin types (FST) I-III. Dc wounds heal to a dyspigmented, non-pliable HTS, resembling scarring in FST IV-VI. Gene expression during wound healing was differentially regulated versus uninjured skin in 40/80 genes, 15 of which differed between breeds. Yk scars had a higher VSS score at all time points. Yk and Dc wounds had equivalent re-epithelialization, collagen disorganization, and blood vessel density.

Conclusions

Our findings demonstrate that Dc and Yk pigs can produce HTS. Wound creation and healing were consistent among breeds, and differences in gene expression were not sufficient to explain differences in resulting scar phenotype. Both pig breeds should be used in animal models to investigate novel therapeutics to provide insight into a treatment's effectiveness on various skin types.

The Mechanism of miR-222 Targets Matrix Metalloproteinase 1 in Regulating Fibroblast Proliferation in Hypertrophic Scars

This study aimed to investigate the value of miR-222 in hypertrophic scars (HS). Specific mechanisms were used to measure the level of miR-222, while MTT assay, flow cytometry, western blot and qRT-PCR were employed to detect the relative proteins after fibroblasts were transfected with the miR-222 mimic/inhibitor. The direct target of miR-222 was determined by Dual-Luciferase Reporter assay. Furthermore, qRT-PCR and western blot were employed to detect the matrix metalloproteinase 1 (MMP1) RNA/protein after fibroblasts were transfected with the miR-222 mimic/inhibitor. These results revealed that miR-222 was significantly upregulated in HS fibroblasts. The overexpression of miR-222 enhanced the HS fibroblast proliferation, increased the cell population in the S phase, inhibited the cell apoptosis, enhanced the expression levels of Col1A1, Col3A1 mRNA/protein, proliferating cell nuclear antigen (PCNA), cyclin D1, cyclin E1 and CDK1 and reduced the expression levels of cleaved caspase-3/9. However, the miR-222 suppression triggered opposite effects. Furthermore, miR-222 played a regulatory role in HS by negatively regulating its target gene MMP1 by binding with its 3'-untranslated region. The overexpression of MMP1 reduced the expression levels of PCNA and cyclin D1, but enhanced the expression levels of cleaved caspase-3. Therefore, MiR-222 and MMP1 have potential value for HS. NO LEVEL ASSIGNED: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Inhibition of Notch Intracellular Domain Suppresses Cell Activation and Fibrotic Factors Production in Hypertrophic Scar Fibroblasts Versus Normal Skin Fibroblasts

BACKGROUND

Hypertrophic scar (HS) is the most common complication after skin injury with unknown etiopathogenesis. There is increasing evidence to suggest that aberrant Notch signaling contributes directly to skin pathogenesis and altered expression of the Notch intracellular domain (NICD) identified in HS. Therefore, the aim of this study was to investigate the effects of Notch signaling pathway in HS pathogenesis.

METHODS

Hypertrophic scar and normal skin samples were collected. Notch intracellular domain expression was detected by immunohistochemistry staining and fibroblasts were separated from the samples. We compared fibrotic factors production, cell viability, migration and apoptosis of HS fibroblasts (HFB) versus normal skin fibroblasts (NFB) by real time quantitative polymerase chain reaction, MTS, cell scratch assay and flow cytometry respectively under the impact of inhibition of Notch signaling by NICD-small-interfering RNA (SiRNA).

RESULTS

The results showed that NICD was overexpressed in the dermis of HS tissues. Inhibition of Notch signaling by NICD-SiRNA suppressed the production of the fibrotic factors including collagen 1, collagen 3, α-SMA, and TGF-β1 by HFB and NFB. Cell viability and migration were reduced in NICD-SiRNA-treated NFB and HFB, whereas cell apoptosis was enhanced by NICD-SiRNA.

CONCLUSIONS

Conclusively, the study demonstrates a potential role for Notch signaling in HS progression, and targeting this pathway may provide a novel strategy for treatment of HS.

Hypopigmented burn hypertrophic scar contains melanocytes that can be signaled to re-pigment by synthetic alpha-melanocyte stimulating hormone in vitro

There are limited treatments for dyschromia in burn hypertrophic scars (HTSs). Initial work in Duroc pig models showed that regions of scar that are light or dark have equal numbers of melanocytes. This study aims to confirm melanocyte presence in regions of hypo- and hyper-pigmentation in an animal model and patient samples. In a Duroc pig model, melanocyte presence was confirmed using en face staining. Patients with dyschromic HTSs had demographic, injury details, and melanin indices collected. Punch biopsies were taken of regions of hyper-, hypo-, or normally pigmented scar and skin. Biopsies were processed to obtain epidermal sheets (ESs). A subset of ESs were en face stained with melanocyte marker, S100β. Melanocytes were isolated from a different subset. Melanocytes were treated with NDP α-MSH, a pigmentation stimulator. mRNA was isolated from cells, and was used to evaluate gene expression of melanin-synthetic genes. In patient and pig scars, regions of hyper-, hypo-, and normal pigmentation had significantly different melanin indices. S100β en face staining showed that regions of hyper- and hypo-pigmentation contained the same number of melanocytes, but these cells had different dendricity/activity. Treatment of hypo-pigmented melanocytes with NDP α-MSH produced melanin by microscopy. Melanin-synthetic genes were upregulated in treated cells over controls. While traditionally it may be thought that hypopigmented regions of burn HTS display this phenotype because of the absence of pigment-producing cells, these data show that inactive melanocytes are present in these scar regions. By treating with a pigment stimulator, cells can be induced to re-pigment.

miR-124-3p targeting of TGF-β1 inhibits the proliferation of hypertrophic scar fibroblasts

BACKGROUND

microRNAs are involved in a variety of physiological and pathophysiological processes, but their role in the pathogenesis of hypertrophic scars (HS) is not fully understood. Transforming growth factor β1 (TGF-β1) plays an important role in the genesis and development of HS.

OBJECTIVES

In this study, we hypothesized that a post-translational miRNA mechanism regulates the expression of TGF-β1 in HS fibroblasts (HSFBs) and participates in the development of HS.

MATERIAL AND METHODS

Predictions from EBCORI, PicTar and miRBase databases showed that miR-124-3p can target and regulate the expression of TGF-β1. We collected HS tissue and corresponding normal tissue from 25 patients with HS who had been operated on for the first time.

RESULTS

The expression level of miR-124-3p in HS tissue was significantly lower than in normal tissue, while the expression level of TGF-β1 mRNA was significantly higher than in normal tissue (p < 0.05), showing a negative correlation between them. Results from a luciferase reporter assay showed that miR-124-3p targets the 3'-UTR of TGF-β1 and inhibits its expression. After miR-124-3p mimics were transfected into HSFBs, the expression of TGF-β1, α-smooth muscle actin (α-SMA), collagen I, survivin, and Bcl-2 were reduced and the expression of Bax was increased, with significant decreases in DNA synthesis, proliferation and survival. However, after a miR-124-3p inhibitor was transfected into HSFBs, these effects were reversed as the expression of TGF-β1, α-SMA, collagen I, survivin, and Bcl-2 increased, expression of Bax decreased, and DNA synthesis, proliferation and survival cells increased significantly.

CONCLUSIONS

miR-124-3p can inhibit the proliferation of HSFBs by targeting TGF-β1, and miR-124-3p may thus be a potential therapeutic target in HS.

Mechanical stretch promotes hypertrophic scar formation through mechanically activated cation channel Piezo1

Hypertrophic scar (HS) formation is a skin fibroproliferative disease that occurs following a cutaneous injury, leading to functional and cosmetic impairment. To date, few therapeutic treatments exhibit satisfactory outcomes. The mechanical force has been shown to be a key regulator of HS formation, but the underlying mechanism is not completely understood. The Piezo1 channel has been identified as a novel mechanically activated cation channel (MAC) and is reportedly capable of regulating force-mediated cellular biological behaviors. However, the mechanotransduction role of Piezo1 in HS formation has not been investigated. In this work, we found that Piezo1 was overexpressed in myofibroblasts of human and rat HS tissues. In vitro, cyclic mechanical stretch (CMS) increased Piezo1 expression and Piezo1-mediated calcium influx in human dermal fibroblasts (HDFs). In addition, Piezo1 activity promoted HDFs proliferation, motility, and differentiation in response to CMS. More importantly, intradermal injection of GsMTx4, a Piezo1-blocking peptide, protected rats from stretch-induced HS formation. Together, Piezo1 was shown to participate in HS formation and could be a novel target for the development of promising therapies for HS formation.

miR-205 inhibits the development of hypertrophic scars by targeting THBS1

Increasing evidence shows that miRNAs are involved in the growth and development of hypertrophic scars. However, the specific mechanism of miR-205 is unclear. Here, we investigated the relationship between miR-205, thrombospondin 1 (THBS1) expression, and hypertrophic scars, and showed that miR-205 inhibits cell proliferation and migration and induces apoptosis. Double luciferase analysis, Western blot, and real-time polymerase chain reaction showed that miR-205 downregulates THBS1 expression and activity. Compared to the control group, miR-205 inhibited hypertrophic scar development. Our findings contribute to a better understanding of the miR-205-THBS1 pathway as a promising therapeutic target for reducing hypertrophic scars.

Long non-coding RNA H19 promotes the proliferation, migration and invasion while inhibits apoptosis of hypertrophic scarring fibroblasts by targeting miR-3187-3p/GAB1 axis

BACKGROUND

It had been reported that long non-coding RNA (lncRNA) H19 was associated with the proliferation of fibroblasts. However, the regulatory mechanism of H19 remains unclear. Thus, the study was designed to explore the underlying mechanism of H19 in the process of Hypertrophic scarring (HS).

METHODS

The expression levels of H19, miR-3187-3p, and growth factor receptor binding 2-associated binding protein 1 (GAB1) in HS tissues and HS fibroblasts were measured by real-time quantitative polymerase chain reaction (RT-qPCR) assay. The biological behaviors of HS fibroblasts, such as cell proliferation, apoptosis, migration, and invasion were assessed by 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyl-2H-tetrazol-3-ium bromide (MTT), colony formation, flow cytometry, and transwell assays, respectively. The protein expression level was quantified by western blot assay. The interaction association between miR-3187-3p and H19 or GAB1 was predicted by Starbase database analysis and confirmed by dual-luciferase reporter assay, respectively.

RESULTS

H19 was significantly increased in HS tissues and HS fibroblasts. Loss-of-functional experiments revealed that knockdown of H19 inhibited the development of HS. Moreover, silencing of H19 impeded the proliferation, migration, and invasion, while enhanced apoptosis of HS fibroblasts by increasing miR-3187-3p expression. In addition, overexpression of GAB1 could abolish miR-3187-3p overexpression-induced effects on cell proliferation, apoptosis, migration, and invasion of HS fibroblasts. Mechanistically, H19 could act as a sponge of miR-3187-3p to upregulate the expression of GAB1 in HS fibroblasts.

CONCLUSION

Collectively, our results revealed that H19 promoted the proliferation, migration, and invasion, while impeded apoptosis of HS fibroblasts by targeting miR-3187-3p/GAB1 axis.

Smad interacting protein 1 influences transforming growth factor-β1/Smad signaling in extracellular matrix protein production and hypertrophic scar formation

The transforming growth factor (TGF)-β/Smad signal transduction pathway is closely associated with hypertrophic scar (HS) formation. Smad interacting protein 1 (SIP1) is a cytoplasmic protein that efficiently regulates Smad2-/3-dependent signaling within the TGF-β₁ pathway. SIP1 influences collagen synthesis in the HS through a heretofore unknown mechanism. This study investigated the role of the SIP1-mediated TGF-β₁/Smad signaling pathway in extracellular matrix (ECM) protein production and hypertrophic scarring. SIP1 expression was markedly lower in HS vs. normal skin (NS) tissue, and α-smooth muscle actin (α-SMA) content and collagen I/III (Col I/III) synthesis were inversely correlated with SIP1 expression. Furthermore, SIP1 inhibited Smad2/3 phosphorylation in vitro, and improved the collagen-based architecture of the scar while reducing collagen expression and overall scar formation in a rabbit ear model of HS. Based on these findings, we propose that SIP1 acts as a molecular modulator capable of altering Smad2-/3-facilitated signaling through the control of Smad phosphorylation, thus inhibiting α-SMA and collagen upregulation in fibroblasts and, ultimately, HS formation. The low SIP1 content in scar tissue also suggests that SIP1 (and positive regulation thereof) is a prospective target for selective HS drug therapy.

Key Cell Functions are Modulated by Compression in an Animal Model of Hypertrophic Scar

INTRODUCTION

The value of compression studies and applications in hypertrophic scar (HTS) treatment is often undermined due to the lack of ideal controls, patient compliance, and clear action mechanisms.

OBJECTIVE

This study assesses the genome-wide compression effects on scars under well-controlled conditions.

MATERIALS AND METHODS

An automated pressure delivery system (APDS) applied controlled doses of pressure to scars in a red Duroc swine HTS model. Full-thickness wounds were created by a skin grafting instrument on each animal's bilateral flanks and were observed through reepithelialization and scar development. On day 70, the APDSs were mounted on the developed scars; right flank scars received a pressure of 30 mm Hg, while left flank scars received APDSs with no pressure (sham) for 2 weeks. A genome-wide assessment of compression effect on transcription in scar specimens before (early), shortly after (mid), and long after (late) compression initiation were performed.

RESULTS

Analysis of early-phase biopsies showed similar transcriptome profiles, which diverged thereafter in gene numbers and functions between compression- and sham-treated scars in the mid phase. The majority of these changes persisted in the late-phase scar samples. Canonical pathway analysis of differentially regulated genes resulted in an almost identical list of pathways during the early phase prior to compression. In the mid and late phases after compression, many of the identified pathways shifted in significance, and new pathways such as calcium signaling and cholesterol synthesis emerged.

CONCLUSIONS

Compression modulates transcription and affects multiple biological functions associated with an improved scar appearance.

MicroRNA-519d inhibits proliferation and induces apoptosis of human hypertrophic scar fibroblasts through targeting Sirtuin 7

MicroRNAs (miRNAs) play critical roles in various pathological processes, including hypertrophic scar (HS) formation. However, the precise role of miRNAs in HS formation remains largely unknown. In this study, we aimed to investigate the role of miR-519d in HS formation. We found that miR-519d expression was significantly downregulated in HS tissues and fibroblasts. Overexpression of miR-519d inhibited the expression of type I collagen (Col I), type III collagen (Col III) and α-smooth muscle actin (α-SMA) in HS fibroblasts. Moreover, overexpression of miR-519d reduced the proliferation and induced the apoptosis of HS fibroblasts. In contrast, suppression of miR-519d showed the opposite effects. Interestingly, Sirtuin 7 (SIRT7) was identified as a target gene of miR-519d. The results showed that miR-519d directly targeted the 3'-untranslated region of SIRT7 and negatively regulated its expression. Furthermore, miR-519d regulated the expression of TGF-β type I receptor (TGFBRI) and the phosphorylation of Smad2. Knockdown of SIRT7 by siRNA inhibited the expression of Col I, Col III and α-SMA, and reduced the proliferation and induced the apoptosis of HS fibroblasts. Overexpression of SIRT7 abrogated the effects mediated by miR-519d overexpression in HS fibroblasts. Overall, these results suggest that miR-519d inhibits the expression of extracellular matrix-associated genes, reduces the proliferation and induces the apoptosis of HS fibroblasts by targeting SIRT7, implying a suppressive role of miR-519d in HS formation. This study suggests that miR-519d may serve as a promising therapeutic target for treatment of human HS.

Extracorporeal Shock Wave Therapy Alters the Expression of Fibrosis-Related Molecules in Fibroblast Derived from Human Hypertrophic Scar

Extracorporeal shock wave therapy (ESWT) considerably improves the appearance and symptoms of post-burn hypertrophic scars (HTS). However, the mechanism underlying the observed beneficial effects is not well understood. The objective of this study was to elucidate the mechanism underlying changes in cellular and molecular biology that is induced by ESWT of fibroblasts derived from scar tissue (HTSFs). We cultured primary dermal fibroblasts derived from human HTS and exposed these cells to 1000 impulses of 0.03, 0.1, and 0.3 mJ/mm². At 24 h and 72 h after treatment, real-time PCR and western blotting were used to detect mRNA and protein expression, respectively, and cell viability and mobility were assessed. While HTSF viability was not affected, migration was decreased by ESWT. Transforming growth factor beta 1 (TGF-β1) expression was reduced and alpha smooth muscle actin (α-SMA), collagen-I, fibronectin, and twist-1 were reduced significantly after ESWT. Expression of E-cadherin was increased, while that of N-cadherin was reduced. Expression of inhibitor of DNA binding 1 and 2 was increased. In conclusion, suppressed epithelial-mesenchymal transition might be responsible for the anti-scarring effect of ESWT, and has potential as a therapeutic target in the management of post-burn scars.

TSG-6 Induces Apoptosis of Human Hypertrophic Scar Fibroblasts via Activation of the Fas/FasL Signalling Pathway

Tumour necrosis factor-stimulated gene 6 (TSG6) is a protective inflammatory reaction gene which is upregulated by inflammatory processes. Recent studies suggest that TSG-6 exhibits anti-scarring effects. However, the mechanism of TSG-6 action in the scar formation remains poorly understood. We investigated whether TSG-6 affects growth of the human hypertrophic scar fibroblasts (HSFs) via Fas/FasL signalling pathway. Cultured HSFs were transfected with a vector carrying the TSG6 gene (pLVX-Puro-TSG-6) or with a vector not containing the TSG6 gene (pLVX-Puro). Untransfected HSFs served as a control group to both transfected HSFs. The expressions level of TSG-6 was up-regulated in the pLVX-Puro-TSG-6 group at the protein and mRNA level. MTT and flow cytometry were used to assess the effect of TSG-6 on the growth and apoptotic status of HSFs. Finally, qRT-PCR and western blot were used to measure the expression levels of Fas, FasL, FADD, caspase-3 and caspase-8 in each group. The apoptosis rate was significantly enhanced and the growth rate reduced in the HSFs transfected with the TSG6 gene vector. The expression levels of Fas, FasL, FADD, caspase-3 and caspase- 8 were significantly raised in the TSG-6 overexpressing HSFs. It is concluded that increased expression of TSG-6 may induce apoptosis of human hypertrophic scar fibroblasts via activation of the Fas/FasL signalling pathway.

Keloid and Hypertrophic Scars Are the Result of Chronic Inflammation in the Reticular Dermis

Keloids and hypertrophic scars are caused by cutaneous injury and irritation, including trauma, insect bite, burn, surgery, vaccination, skin piercing, acne, folliculitis, chicken pox, and herpes zoster infection. Notably, superficial injuries that do not reach the reticular dermis never cause keloidal and hypertrophic scarring. This suggests that these pathological scars are due to injury to this skin layer and the subsequent aberrant wound healing therein. The latter is characterized by continuous and histologically localized inflammation. As a result, the reticular layer of keloids and hypertrophic scars contains inflammatory cells, increased numbers of fibroblasts, newly formed blood vessels, and collagen deposits. Moreover, proinflammatory factors, such as interleukin (IL)-1α, IL-1β, IL-6, and tumor necrosis factor-α are upregulated in keloid tissues, which suggests that, in patients with keloids, proinflammatory genes in the skin are sensitive to trauma. This may promote chronic inflammation, which in turn may cause the invasive growth of keloids. In addition, the upregulation of proinflammatory factors in pathological scars suggests that, rather than being skin tumors, keloids and hypertrophic scars are inflammatory disorders of skin, specifically inflammatory disorders of the reticular dermis. Various external and internal post-wounding stimuli may promote reticular inflammation. The nature of these stimuli most likely shapes the characteristics, quantity, and course of keloids and hypertrophic scars. Specifically, it is likely that the intensity, frequency, and duration of these stimuli determine how quickly the scars appear, the direction and speed of growth, and the intensity of symptoms. These proinflammatory stimuli include a variety of local, systemic, and genetic factors. These observations together suggest that the clinical differences between keloids and hypertrophic scars merely reflect differences in the intensity, frequency, and duration of the inflammation of the reticular dermis. At present, physicians cannot (or at least find it very difficult to) control systemic and genetic risk factors of keloids and hypertrophic scars. However, they can use a number of treatment modalities that all, interestingly, act by reducing inflammation. They include corticosteroid injection/tape/ointment, radiotherapy, cryotherapy, compression therapy, stabilization therapy, 5-fluorouracil (5-FU) therapy, and surgical methods that reduce skin tension.

MicroRNA expression signature and the therapeutic effect of the microRNA‑21 antagomir in hypertrophic scarring

Hypertrophic scars (HS) area fibroproliferative disorder of the skin, which causes aesthetic and functional impairment. However, the molecular pathogenesis of this disease remains largely unknown and currently no efficient treatment exists. MicroRNAs (miRNAs) are involved in a variety of pathophysiological processes, however the role of miRNAs in HS development remains unclear. To investigate the miRNA expression signature of HS, microarray analysis was performed and 152 miRNAs were observed to be differentially expressed in HS tissue compared with normal skin tissues. Of the miRNAs identified, miRNA‑21 (miR‑21) was significantly increased in HS tissues and hypertrophic scar fibroblasts (HSFBs) as determined by reverse transcription‑quantitative polymerase chain reaction analysis. It was also observed that, when miR‑21 in HSFBs was blocked through use of an antagomir, the phenotype of fibrotic fibroblasts in vitro was reversed, as demonstrated by growth inhibition, induction of apoptosis and suppressed expression of fibrosis‑associated genes collagen type I α 1 chain (COL1A1), COL1A2 and fibronectin. Furthermore, miR‑21 antagomir administration significantly reduced the severity of HS formation and decreased collagen deposition in a rabbit ear HS model. The total scar area and scar elevation index were calculated and were demonstrated to be significantly decreased in the treatment group compared with control rabbits. These results indicated that the miR‑21 antagomir has a therapeutic effect on HS and suggests that targeting miRNAs may be a successful and novel therapeutic strategy in the treatment of fibrotic diseases that are difficult to treat with existing methods.

Recombinant human endostatin reduces hypertrophic scar formation in rabbit ear model through down-regulation of VEGF and TIMP-1

BACKGROUND

Recombinant human endostatin (Endostar) has been widely used to suppress angiogenesis in carcinoma patients. Hypertrophic scar (HS) tissue, much like a carcinoma, is often associated with angiogenesis. However, there have been few studies conducted on the effects of Endostar on HS or its mechanism.

OBJECTIVE

This paper investigated the effects Endostar on the HS of rabbit ears and studied the effects of Endostar on VEGF and TIMP-1 expression.

METHODS

Sixteen New Zealand white rabbits were used to establish HS models. Then, rabbit ears containing HS were randomly assigned to either the Endostar group or the control group. The changes of appearance and histology were evaluated using the naked eye, hematoxylin eosin staining, and a scar elevation index. The VEGF and TIMP-1 expressions were detected by immunohistochemical staining, RT-PCR, and western blot.

RESULTS

The thickness of the connective tissue in the Endostar group were thinner, the numbers of micro vessels and fibroblasts were fewer, and the collagen fibers were smoother. Moreover, the mRNA and protein expressions of VEGF and TIMP-1 in the Endostar group were significantly lower than those in the control group.

CONCLUSION

The results suggested that Endostar reduced the formation of HS by down-regulation of VEGF and TIMP-1 expressions.

Keloids: Animal models and pathologic equivalents to study tissue fibrosis

Animal models are crucial for the study of fibrosis. Keloids represent a unique type of fibrotic scarring that occurs only in humans, thus presenting a challenge for those studying the pathogenesis of this disease and its therapeutic options. Here, several animal models of fibrosis currently in use are described, emphasizing recent progress and highlighting encouraging challenges.

Missense Variant in MAPK Inactivator PTPN5 Is Associated with Decreased Severity of Post-Burn Hypertrophic Scarring

Background

Hypertrophic scarring (HTS) is hypothesized to have a genetic mechanism, yet its genetic determinants are largely unknown. The mitogen-activated protein kinase (MAPK) pathways are important mediators of inflammatory signaling, and experimental evidence implicates MAPKs in HTS formation. We hypothesized that single-nucleotide polymorphisms (SNPs) in MAPK-pathway genes would be associated with severity of post-burn HTS.

Methods

We analyzed data from a prospective-cohort genome-wide association study of post-burn HTS. We included subjects with deep-partial-thickness burns admitted to our center who provided blood for genotyping and had at least one Vancouver Scar Scale (VSS) assessment. After adjusting for HTS risk factors and population stratification, we tested MAPK-pathway gene SNPs for association with the four VSS variables in a joint regression model. In addition to individual-SNP analysis, we performed gene-based association testing.

Results

Our study population consisted of 538 adults (median age 40 years) who were predominantly White (76%) males (71%) admitted to our center from 2007–2014 with small-to-moderate-sized burns (median burn size 6% total body surface area). Of 2,146 SNPs tested, a rare missense variant in the PTPN5 gene (rs56234898; minor allele frequency 1.5%) was significantly associated with decreased severity of post-burn HTS (P = 1.3×10⁻⁶). In gene-based analysis, PTPN5 (P = 1.2×10⁻⁵) showed a significant association and BDNF (P = 9.5×10⁻⁴) a borderline-significant association with HTS severity.

Conclusions

We report PTPN5 as a novel genetic locus associated with HTS severity. PTPN5 is a MAPK inhibitor expressed in neurons, suggesting a potential role for neurotrophic factors and neuroinflammatory signaling in HTS pathophysiology.

Cross-talk between TGF-β/Smad pathway and Wnt/β-catenin pathway in pathological scar formation

TGF-β1 is a key factor in the process of wound healing, which is regulated by TGF-β/Smad pathway. We previously demonstrated that TGF-β1 contributed to pathological scar formation. And previous studies also suggested Wnt/β-catenin pathway might be involved in wound healing. However, their role and relation in pathological scar formation remains not very clear. For evaluating TGF-β1 and β-catenin, key factors of the two signal pathways, immunohistochemistry, western blot analysis and RT-PCR were used. Simultaneously, immunohistochemistry were used to evaluate Smad2, Smad3 and Wnt-1, which were also the important factors. We found that they all significantly accumulated in pathological scars compared with normal skins (P<0.05), that implied the two signal pathways both contributed to pathological scar formation. Meanwhile, β-catenin expression showed a tendency to increase first and then decrease under the influence of different concentrations of TGF-β1 (P<0.01). It is possible that there is a complicated interaction between the two signal pathways in pathological scar formation (both synergy and antagonism).

In vivo early intervention and the therapeutic effects of 20(s)-ginsenoside rg3 on hypertrophic scar formation

BACKGROUND

Intra-lesional injections of corticosteroids, interferon, and chemotherapeutic drugs are currently the most popular treatments of hypertrophic scar formation. However, these drugs can only be used after HS is formed, and not during the inflammatory phase of wound healing, which regulates the HS forming process.

OBJECTIVE

To investigate a new, effective, combining therapeutic and safe drug for early intervention and treatment for hypertrophic scars.

METHODS

Cell viability assay and flow cytometric analysis were studied in vitro. Animal studies were done to investigate the combining therapeutic effects of 20(S)-ginsenoside Rg3 (Rg3) on the inflammatory phase of wound healing and HS formation.

RESULTS

In vitro studies showed that Rg3 can inhibit HS fibroblasts proliferation and induce HSF apoptosis in a concentration-dependent manner. In vivo studies demonstrated that Rg3 can limit the exaggerated inflammation, and do not delay the wound healing process, which indicates that Rg3 could be used as an early intervention to reduce HS formation. Topical injection of 4 mg/mL Rg3 can reduce HS formation by 34%. Histological and molecular studies revealed that Rg3 injection inhibits fibroblasts proliferation thus reduced the accumulation of collagen fibers, and down-regulates VEGF expression in the HS tissue.

CONCLUSION

Rg3 can be employed as an early intervention and a combining therapeutic drug to reduce inflammation and HS formation as well.

Enhanced in vivo delivery of 5-fluorouracil by ethosomal gels in rabbit ear hypertrophic scar model

Applying Ethosomal Gels (EGs) in transdermal drug delivery systems has evoked considerable interest because of their good water-solubility and biocompatibility. However, there has not been an explicit description of applying EGs as a vehicle for hypertrophic scars treatment. Here, a novel transdermal EGs loaded with 5-fluorouracil (5-FU EGs) was successfully prepared and characterized. The stability assay in vitro revealed that 5-FU EGs stored for a period of 30 days at 4 ± 1 °C had a better size stability than that at 25 ± 1 °C. Furthermore, using confocal laser scanning microscopy, EGs labeled with Rhodamine 6 G penetrated into the deep dermis of the hypertrophic scar within 24 h in the rabbit ear hypertrophic model suggested that the EGs were an optional delivery carrier through scar tissues. In addition, the value of the Scar Elevation Index (SEI) of 5-FU EGs group in the rabbit ear scar model was lower than that of 5-FU Phosphate Buffered Saline gel and Control groups. To conclude, these results suggest that EGs delivery system loaded 5-fluorouracil is a perfect candidate drug for hypertrophic scars therapy in future.

The four-herb Chinese medicine ANBP enhances wound healing and inhibits scar formation via bidirectional regulation of transformation growth factor pathway

The four-herb Chinese medicine ANBP is a pulverized mixture of four herbs including Agrimonia Eupatoria (A), Nelumbo Nucifera Gaertn (N), Boswellia Carteri (B) and Pollen Typhae Angustifoliae (P). The combination of the four herbs was first described in Chinese canonical medicine about 2000 years ago for treatment of various trauma disorders, such as hemostasis, antiinflammatory, analgesia, and wound healing, etc. However, the precise mechanisms of ANBP are still unclear. In our study, using rabbit ear hypertrophic scar models of full-thickness skin defect, we showed that local ANBP treatment not only significantly enhanced wound healing by relieving inflammation, increasing formation of granulation tissue and accelerating re-epithelialization, but also reduced scar formation by decreasing collagen production, protuberant height and volume of scars, and increasing collagen maturity. We demonstrated that these effects of ANBP are associated with transforming growth factor (TGF)-β1-mediated signalling pathways through Smad-dependent pathways. ANBP treatment significantly increased expression of TGF-β1 and Smad2/3 mRNA at the early stage of wound healing, and led to markedly decrease expression of TGF-β1 and Smad2/3 compared with the control group after 14 days post-wounding. Taken together, our results defined a bidirectional regulation role of ANBP for TGF-β1/Smad pathway in promoting wound healing and alleviating scar formation, which may be an effective therapy for human wounds at the earliest stage.

Anti-scarring properties of different tryptophan derivatives

Hypertrophic scars are associated with prolonged extracellular matrix (ECM) production, aberrant ECM degradation and high tissue cellularity. Routinely used antifibrotic strategies aim to reduce ECM deposition and enhance matrix remodeling. Our previous study investigating the antifibrotic effects of indoleamine2, 3 dioxygenase (IDO) led to the identification of kynurenine (Kyn) as an antiscarring agent. A topical antifibrogenic therapy using Kyn is very attractive; however, it is well established that Kyn passes the blood brain barrier (BBB) which causes complications including excitatory neuronal death. Here we investigated the antiscarring properties of kynurenic acid (KynA), a downstream end product of Kyn that is unlikely to pass the BBB, as an effective and safe replacement for Kyn. Our results indicated that while not having any adverse effect on dermal cell viability, KynA significantly increases the expression of matrix metalloproteinases (MMP1 and MMP3) and suppresses the production of type-I collagen and fibronectin by fibroblasts. Topical application of cream containing KynA in fibrotic rabbit ear significantly decreased scar elevation index (1.13±0.13 vs. 1.61±0.12) and tissue cellularity (221.38±21.7 vs. 314.56±8.66 cells/hpf) in KynA treated wounds compared to controls. KynA treated wounds exhibited lower levels of collagen deposition which is accompanied with a significant decrease in type-I collagen and fibronectin expression, as well as an increase in MMP1 expression compared to untreated wounds or wounds treated with cream only. The results of this study provided evidence for the first time that KynA is promising candidate antifibrogenic agent to improve healing outcome in patients at risk of hypertrophic scarring.

Effects of downregulation of S100A8 protein expression on cell cycle and apoptosis of fibroblasts derived from hypertrophic scars

BACKGROUND

Uncontrolled growth and lack of apoptosis in fibroblasts derived from a hypertrophic scar play an important role in pathology.

OBJECTIVE

The authors explore the contribution of S100A8 overexpression to the phenotype of cells and discuss how the downregulation of S100A8 could inhibit the growth and induce apoptosis of fibroblasts derived from hypertrophic scars.

METHODS

Fibroblasts were harvested from hypertrophic scar tissue in 8 patients treated with small interfering RNA against S100A8 in an in vitro culture. The effects of silencing S100A8 were analyzed by Western blot. Cellular proliferation and apoptosis were detected by flow cytometry.

RESULTS

Fibroblasts treated with small interfering RNA targeting S100A8 showed a significant decrease in S100A8 protein 48 hours after treatment. They also proliferated significantly slower and showed more apoptosis than control fibroblasts.

CONCLUSIONS

Inhibition of S100A8 resulted in significant growth reduction and apoptosis acceleration in fibroblasts derived from hypertrophic scars. Manipulation of S100A8 protein expression by gene silencing may represent something new in the treatment of hypertrophic scarring.

[Effect of tetrandine on gene expression of collagen type I, collagen type III and TGF-beta1 in scar tissue's of rabbits ear]

OBJECTIVE

To observe the effect of tetrandine on gene expression of collagen type I, collagen type III, transformation growth factor-beta1 and to investigate the inhibitory effect of tetrandine on the scar tissue hyperplasia in rabbits' ears.

METHODS

After the scar model was formed on the rabbits' ears, the rabbits were divided into 4 groups to receive intro-lesion injection with saline, or prednisolone (Pre) or tetrandrine in low concentration (L-Tet, 1.0 mg/ml) or tetrandrine in high concentration (H-Tet, 7.5 mg/ml). The morphological changes of scar tissue were observed. The changes of fibroblasts quantity and collagen expression were observed with HE and Masson staining. Immunohistochemical study was used to observe the expression level of collagen type I and collagen type III and TGF-beta1. Collagen type I and collagen type III and TGF-beta1, and signal factor Smad 3 mRNA were detected with RT-PCR.

RESULTS

(1) 24 days after injury, all the wounds healed completely with formation of red, tough and hypertrophic scar. HE and Masson staining showed significant increase of fibroblasts and collagen density with irregularly arrangement. (2) Compared with that in saline group, the scar in other groups became softer, lighter and thinner, especially in H-Tet group. (3) HE and Masson staining shows the scar in Tet and Pre groups contained less fibroblasts and lower collagen dentsity with comparatively regular arrangement than that in saline group (P < 0.01), especially in H-Tet group. (4) According to the immunohistochemical study, the expression of collage type I and III and TGF-beta was positive in all the groups, but the positive rate and the ratio of collagen density I to III decreased in the order of saline, L-Tet, H-Tet and Pre groups (P < 0.01). (5) PT-PCR detection results showed that the amplification bands brightness of collagen type I and III and TGF-beta1 and signal molecular Smad 3 mRNA in scar tissue were obviously different. Compared with that in saline group, the expression of collagen type I and III and TGF-beta1 and Smad 3 mRNA decreased in Tet and Pre groups (P < 0.01). H-Tet group showed the most obvious reduce in the expression of type I collagen and TGF-beta1 and Smad 3 mRNA. Conclusions Tetrandine can significantly suppress the expression of collagen type I and collagen type III and TGF-beta1 on hypertrophic scar of rabbit ears, and reduce signal factor Smad 3 mRNA' s expression. It may be one of the important mechanism for its inhibitory effect on scar hyperplasia.

[Differential expression profile of microRNA between hyperplastic scar and normal skin]

OBJECTIVE

To explore the miRNA differential expression profiles of hyperplastic scar and normal skin so as to further elucidate the pathogenesis of hyperplastic scar and search for new therapeutic targets.

METHODS

The total RNA was extracted from 5 human hyperplastic scar and normal skin tissues by Trizol. The specimens were collected from the First Affiliated Hospital of Nanchang University from November 2010 to May 2011, and purified by mirVana(TM) miRNA Isolation Kit and then labeled and hybridized by miRNA Complete Labeling and Hyb Kit. The images of hybridization were analyzed by the Feature Extraction (v10.7) software and the microarray results confirmed by quantitative real-time reverse transcription-polymerase chain reaction (RT-PCR).

RESULTS

In hyperplastic scar, 92 miRNA genes were up-regulated and 13 down-regulated. The most significantly up-regulated miRNAs were hsa-miR-564 and hsa-miR-936, etc. while hsa-miR-451, hsa-miR-223, hsa-miR-363 and hsa-miR-29b-1* became significantly down-regulated. The findings of RT-PCR on hsa-miR-21 and hsa-miR-451 of regulation were in a high concordance with the microarray results.

CONCLUSION

Distinct differences of miRNA expression between human hyperplastic scar and normal skin, it may be closely correlated with the formation, development and evolution of hyperplastic scar.

Therapeutic effects of liposome-enveloped Ligusticum chuanxiong essential oil on hypertrophic scars in the rabbit ear model

Hypertrophic scarring, a common proliferative disorder of dermal fibroblasts, results from an overproduction of fibroblasts and excessive deposition of collagen. Although treatment with surgical excision or steroid hormones can modify the symptoms, numerous treatment-related complications have been described. In view of this, we investigated the therapeutic effects of essential oil (EO) from rhizomes of Ligusticum chuanxiong Hort. (Umbelliferae) on formed hypertrophic scars in a rabbit ear model. EO was prepared as a liposomal formulation (liposome-enveloped essential oil, LEO) and a rabbit ear model with hypertrophic scars was established. LEO (2.5, 5, and 10%) was applied once daily to the scars for 28 days. On postoperative day 56, the scar tissue was excised for masson's trichrome staining, detection of fibroblast apoptosis, assays of the levels of collagens I and III, and analysis of the mRNA expression of matrix metalloproteinase-1 (MMP-1), caspase-3 and -9, and transforming growth factor beta 1 (TGF-β₁). In addition, the scar elevation index (SEI) was also determined. As a result, LEO treatment significantly alleviated formed hypertrophic scars on rabbit ears. The levels of TGF-β₁, MMP-1, collagen I, and collagen III were evidently decreased, and caspase -3 and -9 levels and apoptosis cells were markedly increased in the scar tissue. SEI was also significantly reduced. Histological findings exhibited significant amelioration of the collagen tissue. These results suggest that LEO possesses the favorable therapeutic effects on formed hypertrophic scars in the rabbit ear model and may be an effective cure for human hypertrophic scars.

[Analysis of the binding domain of hydroxypyruvate isomerase homologues in hypertrophic scar fibroblasts]

OBJECTIVE

To explore the binding domain of hydroxypyruvate isomerase homologues (HYI) in the interaction with protein P311 in hypertrophic scar fibroblasts (Fb).

METHODS

(1) P 311 was amplified by PCR using plasmid pMD18-T-P 311 as template. The total RNA of hypertrophic scar Fb was extracted by Trizol to amplify HYI with RT-PCR. Recombinant vectors pGADT7-P 311 and pGBKT7-HYI were constructed by double-enzyme digestion, and they were verified by PCR and sequencing. The secondary structure of protein HYI was analyzed with software Prot Seale and HNN. Fragments of HYI-1 (1-447 bp), HYI-2 (247-447 bp), HYI-3 (1-279 bp), and HYI-4 (247-654 bp) were amplified based on the result of software analysis. And then the recombinant vectors pGBKT7-HYI-1, 2, 3, and 4 were constructed by double-enzyme digestion and verified by PCR and sequencing. (2) AH109 yeast cells were transformed into competent cells by lithium acetate method and divided into 7 groups roughly in the same amount, including HYI full length, HYI-1, HYI-2, HYI-3, and HYI-4 hybrid groups, positive control group, and negative control group. Cells in the first five groups were respectively transformed with recombinant vector pGBKT7-HYI full length, pGBKT7-HYI-1, pGBKT7-HYI-2, pGBKT7-HYI-3, pGBKT7-HYI-4 and recombinant vector pGADT7-P 311, and that in the rest two groups were transformed with recombinant vectors pGBKT7-53 and pGADT7-RecT, pGADT7-RecT and pGBKT7-Lam by polyethyleneglycol/lithium acetate method. Immediately after transformation, a part of the transformed cells in each group was spread onto the medium lacking leucine, tryptophan, adenine, and histidine (briefly called four-factor lacking medium), and another portion of the cells was spread onto the medium lacking leucine and tryptophan (briefly called two-factor lacking medium). After 3 to 6 days' culture, the growth of yeast was observed, and the expression of β-galactosidase of yeast was detected by color reaction with 5-bromo-4-chloro-indolyl-β-D-galactopyranoside.

RESULTS

(1) Cloned P 311 and the reported P 311 (GenBank ID hsu36189) had the same sequence. The A base at 496 bp in reported HYI (GenBank ID AY775560) was replaced by G base as found in cloned HYI. It was verified that the insert segment of each recombinant vector was correct. (2) Among those 216 amino acids which composed the protein HYI, 101 amino acids might form α helices, 90 amino acids might form random coils, 25 amino acids might form extended-chains as revealed in the simulated structure analysis by computer. (3) Cloned segments HYI-1, 2, 3, 4 showed expected lengths. It was verified that the insert segment of each recombinant vector was correct. (4) Except for strains in negative control group which did not show growth on four-factor lacking medium, all strains in other groups grew on both kinds of media, and growth of colonies was less in HYI-2 (with the fewest number of α helices) and HYI-3 hybrid groups. (5) Positive expression of β-galactosidase was observed in strains of all groups growing on four-factor lacking medium except for the HYI-2 hybrid group. No expression of β-galactosidase was observed in strains of negative control group which grew on two-factor lacking medium.

CONCLUSIONS

Protein HYI may closely bind with protein P311 by α helix, which plays an important role in fibroblast-to-myofibroblast transdifferentiation in hypertrophic scar.

[Literature mining and bioinformatic analysis of dysregulated genes in hypertrophic scar]

OBJECTIVE

To explore the pathogenesis mechanism of hypertrophic scar (HS) and the effective means for its clinical treatment, the difference of the gene expressions between HS and normal skin was compared.

METHODS

The differentially expressed genes between HS and normal skin were obtained by mining PubMed. The dysregulated genes in HS were analyzed by a series of bioinformatics methods, including protein-protein interaction networks, pathways, Gene Ontology and functional annotation clustering analysis.

RESULTS

A total of 55 dysregulated genes in HS was identified (46 up-regulated genes and 9 down-regulated genes). Fifty-one genes were found to encode proteins with interaction network, including up-regulated genes TGFB1, FN1, JUN, COL1A1, CTGF, VEGFA, FOS, COL3A1, IGF1, IL4, PELO, SMAD2, TIMP1, PCNA, and ITGA4 and down-regulated genes ITGB1 and DCN as the central nodes for this network. The dysregulated genes in HS involved in a variety of biological pathways, such as focal adhesion formation, integrin signal transduction, and tumor formation. Furthermore, the dysregulated genes in HS played the important roles in biological processes of cell surface receptor linked signal transduction, tissue development, cell proliferation and apoptosis, and macromolecule biosynthetic process, as well as in molecular function of calcium ion binding, double-stranded DNA binding, heparin binding, promoter binding and MAP kinase activity. The results of functional annotation clustering analysis revealed that the dysregulated genes in HS involved in epidermis development, angiogenesis, and apoptosis.

CONCLUSION

Such key genes as TGFB1, FN1, and JUN, along with the pathways, biological processes and molecular functions involving epidermis development, angiogenesis, and extracellular matrix-integrin-focal adhesion signal transduction may play the important roles in the development of HS. The investigations of the dysregulated genes in HS could provide the new targets for clinical treatment.

[The effect of integrin-linked kinase on VEGF expression in fibroblasts from human hypertrophic scar]

OBJECTIVE

To explore the expression of integrin-linked kinase (ILK) and its effect on VEGF expression in fibroblasts from human hypertrophic scar.

METHODS

Fibroblasts were isolated from hypertrophic scar of 8 patients and cultured in vitro. Then the cells were divided into three groups: (1) Cells were cultured only in DMEM containing 10% FCS in the control group; (2) Cells were transfected with empty plasmid in the empty plasmid group; (3) Cells were transfected with plasmid expressing ILKcDNA in the ILK cDNA plasmid transfection group. First, the expression of ILK and VEGF was observed by immunocytochemistry before and after ILK cDNA transfection. Second, ILK and VEGF mRNA expression was investigated by real-time PCR (RT-PCR). Third, the protein expression of ILK and VEGF was detected by Western blot. Finally, the protein level of VEGF in supernatant of fibroblasts was measured by ELISA.

RESULTS

Before ILK cDNA transfection, the expression of ILK was positive and the VEGF expression was weak in cytoplasm of fibroblasts . After ILK cDNA transfection, both the expression of ILK and VEGF was enhanced. The level of VEGF mRNA was significantly higher in ILK cDNA transfection group (0.338 +/- 0.060) than that in control group (0.022 +/- 0.001) and empty plasmid group (0.028 +/- 0.005, P < 0.05). The level of VEGF protein was significantly higher in ILK cDNA transfection group (0.819 +/- 0.019) than that in control group (0.607 +/- 0.033) and empty plasmid group (0. 591 +/- 0.024, P<0. 05). Secretion of VEGF increased remarkably in ILK cDNA transfection group comparing with the other two groups (P < 0.05).

CONCLUSIONS

ILK could up-regulate the VEGF mRNA and protein level in human scar fibroblasts. It may play an important role in the angiogenesis in hypertrophic scar.

[Effect of recombinant Sp1 gene on the collagen expression of hypertrophic scar fibroblasts in vitro]

OBJECTIVE

To explore the feasibility of transfecting recombinant Sp1 into hypertrophic scar fibroblasts and investigate the proliferation and collagen I, III synthesis in the transfected cells.

METHODS

Recombinant human Sp1 was transfected into hypertrophic scar fibroblasts with the karyocyte expressive vector. The expression of Sp1, collagen I, III mRNA was tested by real time PCR. The change of cell proliferation was observed with CCK8 colorimeter.

RESULTS

About 30% of transfected hypertrophic scar fibroblasts showed green fluorescence positive. The relative expression of Sp1 mRNA in transfected cells, empty-vector cell or untransfected cells group was 5.26 +/- 0.76, 1.08 +/- 0.18, 1.09 +/- 0.15, respectively, showing a significant difference between thansfected and untransfected cells or between the transfected cells and empty-vector group (P <0.01, n = 5). Expression of collagen I, III mRNA was 2.49 +/- 0.40 and 1.88 +/- 0.30 in transfected cells, 0.96 +/- 0.18 and 0.95 +/- 0.18 in empty-vector cell, and 0.97 +/- 0.15 and 0.93 +/- 0.13 in untransfected cells, respectively, showing a significant difference between thansfected and untransfected cells or between the transfected cells and empty-vector group (P < 0.01, n = 5).

CONCLUSIONS

The hypertrophic scar fibroblasts could be as the target cells of Sp1 gene transfection. Sp1 gene may play an important role in abnormal collagen metabolism in hypertrophic scar.

[Effects of antisense oligonucleotides on the expression of focal adhesion kinase gene and collagen synthesis in the cultured human fibroblasts of hypertrophic scar]

OBJECTIVE

To study the role of focal adhesion kinase (FAK) in the pathogenesis of human hypertrophic scar.

METHODS

Human hypertrophic scar fibroblasts (HSFB) were isolated from human hypertrophic scar and cultured in vitro. The cells were then divided into 3 groups as AT group (phosphorothioate FAK ASODN was transfected into the HSFB by liposome), LPC group (liposome only), and LC group (control group, without liposome or ASODN). The FAKmRNA index of HSFB was assessed by polymerase chain reaction method (FQ-PCR). The collagen synthesis of HSFB was assessed by 3H-proline incorporation method.

RESULTS

The FAK mRNA index of HSFB in AT group 48 hours after transfection was significantly lower than that in LPC and LC groups (0.043 +/- 0.030, 0.124 +/- 0.070, 0.127 +/- 0.0195, P < 0.05). The 3H-proline incorporation rate in AT group was lower than that in LPC and LC groups (257.0 +/- 15.14, 962.2 +/- 300.5, 930.8 +/- 28.97, P < 0.01).

CONCLUSION

The expression of FAK gene and collagen synthesis of the cultured HSFB could be inhibited by FAK ASODN, indicating that FAK played a role in the development of excessive fibrosis of human hypertrophic scar.

[Effect of METH1 gene transfection on the proliferation of rabbit's ear scar]

OBJECTIVE

To investigate the effect of METH1 gene transfection on fibroblast proliferation and I, III collagen synthesis in rabbit ear scar.

METHODS

The hypertrophic scar model on the rabbit ears was reproduced. 10 days after epithelization, Ad-METH1 was injected into the scar tissue. 30 days later, the effect of METH1 gene transfection on the angiogenesis, fibroblast proliferation and the ratio of collagen I/III in the scar tissue was detected by microcirculation microscope, AgNOR particle count and collagen dyeing.

RESULTS

30 days after injection of Ad-METH1, angiogenesis, fibroblast proliferation and the ratio of collagen I/III in the scar tissue were obviously suppressed.

CONCLUSION

Early application of Ad-METH1 after epithelization can markedly inhibit the formation of the hypertrophic scar.

[Expression of matrix metalloproteinase-2, -9 and their inhibitor-1 in hypertrophic scars]

OBJECTIVE

To investigate the gene expression of matrix metalloproteinases (MMP-2, MMP-9) and tissue inhibitor of metalloproteinase-1 (TIMP-1) in proliferative and mature hypertrophic scars.

METHODS

Total RNA from 8 normal skin samples and from 16 human hypertrophic scar samples of different maturing stage was respectively extracted, and then mRNA was isolated. The gene expressions of MMP-2, MMP-9 and TIMP-1 in these samples were examined with reverse transcription-polymerase chain reaction (RT-PCR).

RESULTS

The gray scale ratio of MMP-2, MMP-9 and TIMP-1 transcription in normal skin were (3.8 +/- 0.7)%, (5.8 +/-4.4)%, (30.3 +/- 3.0)%, respectively, which were obviously higher than those in proliferative hypertrophic scar [(14 +/- 5)%, (18 +/- 5)%, (38 +/- 4)%, P < 0.05]. The expression of MMP-2 and MMP-9 genes in mature hypotrophic scar returned to normal level, but that of TIMP-1 remained high when compared with that of normal level (P < 0. 05).

CONCLUSION

The increase in MMP-2, MMP-9 and TIMP-1 gene expression might be involved in the formation of hypertrophic scars, while the lowering of MMP-2 and MMP-9 gene expression might be associated with the maturation of hypertrophic scars.