From genetics to epigenetics: new insights into keloid scarring

Multi-omics analysis to explore the molecular mechanisms related to keloid

BACKGROUND

Keloid is a benign skin tumor that result from abnormal wound healing and excessive collagen deposition. The pathogenesis is believed to be linked to genetic predisposition and immune imbalance, although the precise mechanisms remain poorly understood. Current therapeutic approaches may not consistently yield satisfactory outcomes and are often accompanied by potential side effects and risks. The high recurrence rate and refractory nature of keloid nodules present significant challenges and uncertainties in their management. Given the lack of effective treatment strategies, it is essential to identify key molecular pathways and potential therapeutic targets for keloid.

OBJECTIVE

This study aimed to identify the potential pathogenic mechanisms, hub genes, and immune cell involvement in keloid formation, with the goal of providing novel insights for targeted therapies.

METHODS

We utilized a combination of bulk RNA sequencing to analyze gene expression profiles in keloid tissues. Differentially expressed genes (DEGs) were identified and subjected to pathway enrichment analysis to reveal key biological processes involved in keloid pathogenesis. Mendelian randomization was performed to investigate the causal relationship between genetic factors and keloid formation, identifying potential hub genes. Immune infiltration analysis was conducted to determine the role of specific immune cells in keloid development. Subsequently, Gene Set Enrichment Analysis (GSEA) and Gene Set Variation Analysis (GSVA) were performed to investigate the functional pathways associated with the hub genes. Network analysis was employed to identify transcription factors, miRNAs, and potential drugs in the Connectivity Map associated with the hub genes. Single-cell RNA sequencing was also used to identify cell-specific expression patterns of these genes.

RESULTS

Pathway enrichment analysis highlighted the association of keloid pathogenesis with cell proliferation and division, providing insights into the molecular processes involved. Mendelian randomization revealed that DUSP1 acts as an inhibitor of keloid formation, while HOXA5 promotes keloid pathogenesis. Immune infiltration analysis suggested that mast cells and macrophages play critical roles in the disease's progression. Based on hub gene analysis, the IL17 signaling pathway emerged as a key pathway implicated in keloid development. Further drug prediction models identified 9-methyl-5H-6-thia-4, 5-diaza-chrysene-6, 6-dioxide, zebularine, temozolomide and valproic acid targeting these hub genes.

CONCLUSION

DUSP1 and HOXA5 are hub genes in keloid pathogenesis, with DUSP1 acting as an inhibitor and HOXA5 as a promoter of disease progression. Targeting the regulatory networks associated with these genes could provide novel therapeutic strategies. Mast cells and macrophages are identified as critical immune cell types involved in the disease process. Additionally, the IL17 signaling pathway plays a crucial role in keloid development, highlighting its potential as a therapeutic target. These findings suggest that a multi-target approach focusing on these pathways could offer effective treatment options for keloid patients.

Identification of DYRK2 and TRIM32 as keloids programmed cell death-related biomarkers: insights from bioinformatics and machine learning in multiple cohorts

This study aims to explore the expression patterns and mechanisms of programmed cell death-related genes in keloids and identify molecular targets for early diagnosis and treatment. We first explored the expression, immune, and biological function profiles of keloids. Using various machine learning methods, two key genes, DYRK2 and TRIM32, were identified, with ROC curves demonstrating their diagnostic potential. Further analyses, including GSEA, immune cell profiling, competing endogenous RNA network, and single-cell analysis, revealed their mechanism of action and regulatory network. Finally, SB-431542 was identified as a potential therapeutic agent for keloids through CMap and molecular docking.

Salidroside Prevents Keloid Fibroblast Aggressive Progression by Upregulating miR-26a-5p to Inhibit JAG1

Salidroside, a natural herb, exerts considerable anti-tumor effects in various human cancers. Evidence unveils that Salidroside mediates gene expression to affect cancer progression. Our work intended to uncover the molecular mechanism of Salidroside functional role in keloid. Expression analysis for JAG1 and miR-26a-5p in tissues and cells was performed using qRT-PCR or western blotting. For functional analysis, cell proliferation, apoptosis and migration were ascertained by CCK-8, flow cytometry and Transwell assay, respectively. The putative binding relationship between JAG1 and miR-26a-5p was further confirmed by dual-luciferase reporter assay. Salidroside exerted pharmacological properties in keloid and impaired keloid fibroblast (KF) viability. JAG1 was upregulated in keloid tissues, and its expression was repressed by Salidroside in KFs. Salidroside depleted KF proliferation and migration but stimulated apoptosis, and JAG1 knockdown largely strengthened the functional effects of Salidroside. MiR-26a-5p interacted with JAG1 3'UTR and expressed with an opposite pattern with JAG1 in keloid. Inhibition of miR-26a-5p largely abolished the effects of JAG1 knockdown in Salidroside-treated KFs, leading to the recovery of KF aggressive behaviors. Salidroside blocked KF aggressive progression by upregulating miR-26a-5p to inhibit JAG1, which provided evidence on the anti-tumor effects of Salidroside in human keloid.

Higher expression of mir-31-5p is associated with reduced risk of head and neck keloid recurrence following surgical resection

Objective

In this study, we aimed to evaluate mir-31-5p as a prognostic biomarker of keloid disease (KD) recurrence using a retrospective, treatment naïve, surgical cohort of head and neck KD cases from Henry Ford Health.

Methods

Using a tissue microarray, mir-31-5p expression was measured with miRNAscope, and mir-31-5p cell positivity was determined with QuPath. Logistic regression was used to test the association between mir-31-5p positive cells and KD recurrence at 1 year. In an independent dataset, associations between mir-31-5p and messenger RNA (mRNA) expression were assessed. Ingenuity Pathway Analysis identified target genes and pathways impacted by mir-31-5p.

Results

Of the 58 KD patients, 42 (72%) received adjuvant triamcinolone injections, and 8 recurred (14%). mir-31-5p was expressed in 48 (83%) specimens. Increasing mir-31-5p expression was associated with decreased risk of recurrence (p = .031), with an odds ratio of 0.86 (95% CI 0.75-0.98) for each 20% increase in mir-31-5p cellular positivity. This effect persisted with triamcinolone treatment (odds ratio 0.82; 95% CI 0.71-0.95; p = .015). mir-31-5p correlated with gene expression enriched in KD pathways, including mRNA splicing and autophagy.

Conclusion

Taken together, our data supports the association between mir-31-5p expression and KD recurrence. Its potential as a prognostic biomarker should be further investigated.

Level of Evidence

Level 2.

Gene Profiling of Circular RNAs in Keloid-prone Individuals and ceRNA Network Construction During Wound Healing

Epigenetic alterations of non-coding RNA (ncRNA) are pivotal in the continuous activation and differentiation of fibroblasts in keloid. However, the epigenetic mechanism of circRNA in keloid is still not clear yet. In this study, we aimed to investigate the interplay among differentially expressed circRNAs, miRNAs, and mRNAs during wound healing in keloid-prone individuals, construct a competing endogenous RNA (ceRNA) network, and gain an in-depth insight into the pathophysiological mechanisms underlying keloid development. Utilizing bioinformatic methods, we analyzed the expression profiles from the GSE113621 database. We identified 29 differentially expressed circRNAs (DEcircRNAs) in keloid-prone individuals during wound healing, from which we constructed 14 ceRNA networks. Subsequently, we validated the expression of predicted DEcircRNAs in keloid tissues and elucidated the ceRNA network involving circ_064002 and fibronectin-1 (FN1) through competing miR-30a/b-5p. Knocking down circ_064002 led to down-regulation of FN1 expression and various cellular functions in keloid-derived fibroblasts (KFs), including cell viability, migration, invasion, and repair capacity. Our study introduces a novel approach to explore the presence of DEcircRNAs and the ceRNA regulatory network during wound healing in keloid-prone individuals through in-depth mining of GEO data and also proves the epigenetic regulatory mechanism of circ_064002 in KFs. LEVEL OF EVIDENCE V: 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 .

Immediately Injections of Botulinum Toxin A After Surgical Excision for Ear Keloids: A Retrospective Study

BACKGROUND

Ear keloids are pathologic scar hyperplasia in the ear region. The most therapeutic approach was surgical shave excision with radiation therapy. However, radiation therapy is easily delivered to healthy surrounding tissues. In the last years, injections with botulinum toxin type A (BTX-A) have been proven to improve surgical scars effectively in clinical trials. This study aimed to evaluate the effect of immediate injections of BTX-A after surgical excision for ear keloids.

METHODS

From January 2020 to January 2023, 33 consecutive patients with ear keloids were enrolled. All patients underwent scar excision and revision at the same time when they needed BTX-A. It was injected into surgical wound closure immediately after surgery. The results of this study were evaluated at follow-up from 7 to 18 months using the Vancouver Scar Scale (VSS) and the Visual Analogue Scale (VAS).

RESULTS

From January 2020 to January 2023, 33 patients received concomitant therapy of immediate injections of BTX-A after surgery for ear keloids. The patients were evaluated at follow-ups lasting 7 to 18 months. Only one case recurred within the follow-up period, and no adverse effects were reported.

CONCLUSION

This study demonstrates that significant cosmetic outcomes in ear keloid treatment were achieved after early postsurgical BTX-A injections. The patients reported high satisfaction and few complications.

Advances in skin gene therapy: utilizing innovative dressing scaffolds for wound healing, a comprehensive review

The skin, serving as the body's outermost layer, boasts a vast area and intricate structure, functioning as the primary barrier against external threats. Disruptions in the composition and functionality of the skin can lead to a diverse array of skin conditions, such as wounds, burns, and diabetic ulcers, along with inflammatory disorders, infections, and various types of skin cancer. These disorders not only exacerbate concerns regarding skin health and beauty but also have a significant impact on mental well-being. Due to the complexity of these disorders, conventional treatments often prove insufficient, necessitating the exploration of new therapeutic approaches. Researchers develop new therapies by deciphering these intricacies and gaining a thorough understanding of the protein networks and molecular processes in skin. A new window of opportunity has opened up for improving wound healing processes because of recent advancements in skin gene therapy. To enhance skin regeneration and healing, this extensive review investigates the use of novel dressing scaffolds in conjunction with gene therapy approaches. Scaffolds that do double duty as wound protectors and vectors for therapeutic gene delivery are being developed using innovative biomaterials. To improve cellular responses and speed healing, these state-of-the-art scaffolds allow for the targeted delivery and sustained release of genetic material. The most recent developments in gene therapy techniques include RNA interference, CRISPR-based gene editing, and the utilization of viral and non-viral vectors in conjunction with scaffolds, which were reviewed here to overcome skin disorders and wound complications. In the future, there will be rare chances to develop custom methods for skin health care thanks to the combination of modern technology and collaboration among disciplines.

Long Non-Coding RNA B3GALT5-AS1 Suppresses Keloid Progression by Regulating the β-Trcp1-Mediated Ubiquitination of HuR

Background

lncRNA β‑1,3‑galactosyltransferase 5‑AS1 (B3GALT5-AS1) plays a vital regulatory role in colon and gastric cancers. However, the biological functions and regulatory mechanisms of B3GALT5-AS1 in keloid progression remain unknown. This study aims to investigate the molecular mechanisms in the B3GALT5-AS1-regulated keloid proliferation and invasion.

Methods

Secondary mining of the lncRNA sequencing data from GSE158395 was conducted to screen differentially expressed lncRNAs between keloid and normal tissues. MTT, cell migration and invasion assays were performed to detect the effects of B3GALT5-AS1 on keloid fibroblasts (KFs) proliferation and metastasis. The extracellular acidification rate (ECAR) and oxygen consumption rate (OCR) were also determined to evaluate glycolysis in KFs. RNA pull-down and RNA-protein immunoprecipitation assays were used to confirm the interaction between B3GALT5-AS1 and Hu-Antigen R (HuR). Further ubiquitination and rescue experiments were performed to elucidate the regulatory relationship between B3GALT5-AS1 and HuR.

Results

B3GALT5-AS1 was significantly down-regulated in keloid tissues and fibroblasts. B3GALT5-AS1 overexpression significantly inhibited KFs proliferation, glycolysis, invasion, and migration and promoted cell apoptosis, whereas silencing B3GALT5-AS1 inhibited these effects. Moreover, B3GALT5-AS1 binds to HuRand reduces its stability through β-Transducin repeats-containing protein 1 (β-Trcp1)-mediated ubiquitination. Overexpression of HuR reversed the inhibition of B3GALT5-AS1 on cell proliferation, migration, and invasion in KFs, where glycolysis pathway was involved.

Conclusion

Our findings illustrate that B3GALT5-AS1 has great effect on inhibition of keloid formation, which provides a potential target for keloid therapy.

Nanocarrier-Mediated Delivery of MicroRNAs for Fibrotic Diseases

MicroRNAs (miRNAs) are endogenous noncoding RNAs that mediate the fibrotic process by regulating multiple targets. MicroRNA-based therapy can restore or inhibit miRNA expression and is expected to become an effective approach to prevent and alleviate fibrotic diseases. However, the safe, targeted, and effective delivery of miRNAs is a major challenge in translating miRNA therapy from bench to bedside. In this review, we briefly describe the pathophysiological process of fibrosis and the mechanism by which miRNAs regulate the progression of fibrosis. Additionally, we summarize the miRNA nanodelivery tools for fibrotic diseases, including chemical modifications and polymer-based, lipid-based, and exosome-based delivery systems. Further clarification of the role of miRNAs in fibrosis and the development of a novel nanodelivery system may facilitate the prevention and alleviation of fibrotic diseases in the future.

A role for vitamin D and the vitamin D receptor in keloid disorder

Keloids are disfiguring fibroproliferative lesions that can occur in susceptible individuals following any skin injury. They are extremely challenging to treat, with relatively low response rates to current therapies and high rates of recurrence after treatment. Although several distinct genetic loci have been associated with keloid formation in different populations, there has been no single causative gene yet identified and the molecular mechanisms guiding keloid development are incompletely understood. Further, although it is well known that keloids are more commonly observed in populations with dark skin pigmentation, the basis for increased keloid risk in skin of colour is not yet known. Because individuals with dark skin pigmentation are at higher risk for vitamin D deficiency, the role of vitamin D in keloid pathology has gained interest in the keloid research community. A limited number of studies have found lower serum vitamin D levels in patients with keloids, and reduced expression of the vitamin D receptor (VDR) in keloid lesions compared with uninjured skin. Vitamin D has documented anti-inflammatory, anti-proliferative and pro-differentiation activities, suggesting it may have a therapeutic role in suppression of keloid fibrosis. Here we review the evidence supporting a role for vitamin D and VDR in keloid pathology.

Characterization of the skin keloid microenvironment

Keloids are a fibroproliferative skin disorder that develops in people of all ages. Keloids exhibit some cancer-like behaviors, with similar genetic and epigenetic modifications in the keloid microenvironment. The keloid microenvironment is composed of keratinocytes, fibroblasts, myofibroblasts, vascular endothelial cells, immune cells, stem cells and collagen fibers. Recent advances in the study of keloids have led to novel insights into cellular communication among components of the keloid microenvironment as well as potential therapeutic targets for treating keloids. In this review, we summarized the nature of genetic and epigenetic regulation in keloid-derived fibroblasts, epithelial-to-mesenchymal transition of keratinocytes, immune cell infiltration into keloids, the differentiation of keloid-derived stem cells, endothelial-to-mesenchymal transition of vascular endothelial cells, extracellular matrix synthesis and remodeling, and uncontrolled angiogenesis in keloids with the aim of identifying new targets for therapeutic benefit. Video Abstract.

Relief of Extracellular Matrix Deposition Repression by Downregulation of IRF1-Mediated TWEAK/Fn14 Signaling in Keloids

Keloids represent a fibrotic disorder characterized by the excessive deposition of extracellular matrix (ECM). However, the mechanisms through which ECM deposition in keloids is regulated remain elusive. In this study, we found that the expression of both TWEAK and its cognate receptor Fn14 was significantly downregulated in keloids and that TWEAK/Fn14 signaling repressed the expression of ECM-related genes in keloid fibroblasts. The IRF1 gene was essential for this repression, and the TWEAK/Fn14 downstream transcription factor p65 directly bound to the promoter of the IRF1 gene and induced its expression. Furthermore, in patients with keloid, the expression of TWEAK and Fn14 was negatively correlated with that of ECM genes and positively correlated with that of IRF1. These observations indicate that relief of TWEAK/Fn14/IRF1-mediated ECM deposition repression contributes to keloid pathogenesis, and the identified mechanism and related molecules provide potential targets for keloid treatment in the future.

The Role of Physical Therapies in Wound Healing and Assisted Scarring

Wound healing (WH) is a complex multistep process in which a failure could lead to a chronic wound (CW). CW is a major health problem and includes leg venous ulcers, diabetic foot ulcers, and pressure ulcers. CW is difficult to treat and affects vulnerable and pluripathological patients. On the other hand, excessive scarring leads to keloids and hypertrophic scars causing disfiguration and sometimes itchiness and pain. Treatment of WH includes the cleaning and careful handling of injured tissue, early treatment and prevention of infection, and promotion of healing. Treatment of underlying conditions and the use of special dressings promote healing. The patient at risk and risk areas should avoid injury as much as possible. This review aims to summarize the role of physical therapies as complementary treatments in WH and scarring. The article proposes a translational view, opening the opportunity to develop these therapies in an optimal way in clinical management, as many of them are emerging. The role of laser, photobiomodulation, photodynamic therapy, electrical stimulation, ultrasound therapy, and others are highlighted in a practical and comprehensive approach.

PTB Regulates the Metabolic Pathways and Cell Function of Keloid Fibroblasts through Alternative Splicing of PKM

Keloids, benign fibroproliferative cutaneous lesions, are characterized by abnormal growth and reprogramming of the metabolism of keloid fibroblasts (KFb). However, the underlying mechanisms of this kind of metabolic abnormality have not been identified. Our study aimed to investigate the molecules involved in aerobic glycolysis and its exact regulatory mechanisms in KFb. We discovered that polypyrimidine tract binding (PTB) was significantly upregulated in keloid tissues. siRNA silencing of PTB decreased the mRNA levels and protein expression levels of key glycolytic enzymes and corrected the dysregulation of glucose uptake and lactate production. In addition, mechanistic studies demonstrated that PTB promoted a change from pyruvate kinase muscle 1 (PKM1) to PKM2, and silencing PKM2 substantially reduced the PTB-induced increase in the flow of glycolysis. Moreover, PTB and PKM2 could also regulate the key enzymes in the tricarboxylic acid (TCA) cycle. Assays of cell function demonstrated that PTB promoted the proliferation and migration of KFb in vitro, and this phenomenon could be interrupted by PKM2 silencing. In conclusion, our findings indicate that PTB regulates aerobic glycolysis and the cell functions of KFb via alternative splicing of PKM.

PI3K/AKT pathway promotes keloid fibroblasts proliferation by enhancing glycolysis under hypoxia

Our previous study demonstrated altered glucose metabolism and enhanced phosphorylation of the PI3K/AKT pathway in keloid fibroblasts (KFb) under hypoxic conditions. However, whether the PI3K/AKT pathway influences KFb cell function by regulating glucose metabolism under hypoxic conditions remains unclear. Here, we show that when PI3K/AKT pathway was inactivated with LY294002, the protein expression of glycolytic enzymes decreased, while the amount of mitochondria and mitochondrial membrane potential increased. The key parameters of extracellular acidification rate markedly diminished, and those of oxygen consumption rate significantly increased after inhibition of the PI3K/AKT pathway. When the PI3K/AKT pathway was suppressed, the levels of reactive oxygen species (ROS) and mitochondrial ROS (mitoROS) were significantly increased. Meanwhile, cell proliferation, migration and invasion were inhibited, and apoptosis was increased when the PI3K/AKT pathway was blocked. Additionally, cell proliferation was compromised when KFb were treated with both SC79 (an activator of the PI3K/AKT pathway) and 2-deoxy-d-glucose (an inhibitor of glycolysis), compared with the SC79 group. Moreover, a positive feedback mechanism was demonstrated between the PI3K/AKT pathway and hypoxia-inducible factor-1α (HIF-1α). Our data collectively demonstrated that the PI3K/AKT pathway promotes proliferation and inhibits apoptosis in KFb under hypoxia by regulating glycolysis, indicating that the PI3K/AKT signalling pathway could be a therapeutic target for keloids.

Construction and validation of the diagnostic model of keloid based on weighted gene co-expression network analysis (WGCNA) and differential expression analysis

Keloid is a disease that seriously affects the aesthetic appearance of the body. In contrast to normal skin or hypertrophic scars, keloid tissue extends beyond the initial site of injury. Patients may complain of pain, itching, or burning. Although multiple treatments exist, none is uniformly successful. Genetic advances have made it possible to explore differences in gene expression between keloids and normal skin. Identifying the biomarker for keloid is beneficial to the mechanism exploration and treatment development of keloid. In this study, we identified seven genes with significant differences in keloids through weighted gene co-expression network analysis(WGCNA) and differential expression analysis. Then, by the Lasso regression, we constructed a keloid diagnostic model using five of these genes. Further studies found that keloids could be divided into high-risk and low-risk groups by this model, with differences in immunity, m6A methylation, and pyroptosis. Finally, we verified the accuracy of the diagnostic model in clinical RNA-sequencing data.

SPARC promotes fibroblast proliferation, migration, and collagen production in keloids by inactivation of p53

BACKGROUND

Keloid, an aggressive fibroproliferative disease of the skin, is usually caused by infectious skin diseases, burns, and trauma.

OBJECTIVE

This study aimed to assess the effect of SPARC on the keloid pathogenesis.

METHODS

In normal skin and keloid scar tissues, changes in SPARC expression were analysed by qRT-PCR, western blotting, and immunohistochemistry. Keloid fibroblasts were isolated from human keloid tissue. GSEA was performed to investigate the signalling pathways related to SPARC. Cell Counting Kit-8, 5-Ethynyl-2'-deoxyuridine, transwell assay, and scratching assays were used to assess fibroblast proliferation and migration. Changes in α-SMA, fibronectin, collagen I, and collagen III levels were examined in fibroblasts by western blotting.

RESULTS

SPARC expression was upregulated in keloid scar tissues. In fibroblasts, cell proliferation, migration, collagen production, and extracellular matrix (ECM) synthesis were promoted by SPARC overexpression, whereas SPARC knockdown resulted a converse result. GSEA showed that SPARC regulates the p53 pathway. In keloid scar tissues, there was a negative correlation between SPARC and p53 expression. p53 expression was decreased by SPARC overexpression, whereas SPARC knockdown increased p53 expression. Furthermore, the effects of SPARC on the fibroblast phenotype were reversed by p53 overexpression.

CONCLUSIONS

Fibroblast proliferation, migration, and ECM synthesis were promoted by SPARC overexpression, which was achieved by regulating the p53 pathway. Our findings provide new therapeutic targets for keloids.

Comparisons of the effects of topical anti-scar drugs on post-surgical facial scar formation: a clinical investigation

OBJECTIVES

Scarring is a common but intricate problem, and topical anti-scarring drugs are the most widely used treatment. However, the wide range of drugs available makes it difficult for doctors and patients to choose from because of the lack of clinical comparisons. Therefore, we conducted an observational study to compare the clinical efficacy of different topical anti-scarring drugs.

METHODS

Patients with post-suturing facial scars were enrolled in this study. The questionnaire was designed to record the basic characteristics of the patients. The Vancouver Scar Scale, SCAR scale, and measurements of scar width and thickness were used to evaluate scar quality. Patients who met the inclusion criteria were divided into four groups for comparison: the silicone preparation (SP), onion extract (OE), asiaticoside (AC) groups, and the untreated blank control (BC) group. The overall data were analyzed before they were confined to the zygomatic region.

RESULTS

A total of 127 eligible patients were enrolled in this study. The results of the total and zygomatic scars demonstrated that SP, OE, and AC groups resulted in narrower scars and lower scar scale scores. The SP group depicted higher melanin efficacy than the other two groups. The OE group had the best pliability, whereas the AC group had the thinnest scar.

CONCLUSIONS

In this study, we acquired expertise with different topical anti-scar agents: SP significantly reduced melanin levels, OE mainly benefited scar pliability, and AC was better at reducing scar thickness. These differences may be more instructive for clinical applications.

Potential genetic therapies based on m6A methylation for skin regeneration: Wound healing and scars/keloids

Skin wound healing is a complex and multistage process, where any abnormalities at any stage can result in the accumulation of non-functional fibrotic tissue, leading to the formation of skin scars. Epigenetic modifications play a crucial role in regulating gene expression, inhibiting cell fate determination, and responding to environmental stimuli. m6A methylation is the most common post-transcriptional modification of eukaryotic mRNAs and long non-coding RNAs. However, it remains unclear how RNA methylation controls cell fate in different physiological environments. This review aims to discuss the current understanding of the regulatory pathways of RNA methylation in skin wound healing and their therapeutic implications with a focus on the specific mechanisms involved.

An improved explants culture method: Sustainable isolation of keloid fibroblasts with primary characteristics

BACKGROUND

Keloid (KD) is a complex fibroproliferative disease, but the exact mechanisms underlying keloid pathogenesis remain to be elucidated. The primary keloid fibroblasts (KFs) culture in vitro has always been a fundamental measure to study the pathogenesis of keloid. However, the traditional primary culture methods have some limitations, such as a long culture cycle, low specimen utilization rate and so on.

AIMS

Improve the keloid explants culture method sts.

MATERIALS & METHODS

We proposed an improved new "explants multiple culture method"-reusing keloid explants for primary culture and harvesting the primary KFs in specific culture times. Meanwhile, the purity, proliferation, apoptosis, migration, invasion, extracellular matrix synthesis, and some fibrosis and inflammation-related proteins of KFs obtained from the first, fifth, and tenth explants cultures were detected.

RESULTS

The results showed that the culture cycle of this new method (Cell Isolation: 2.67 ± 0.86 days, Explants removal: 8.83 ± 0.79 days, Cell Passage: 15.17 ± 1.39 days) was significantly shorter than that of the traditional method (Cell Isolation: 8.67 ± 1.84 days, Explants removal: 17.67 ± 2.17 days, Cell Passage: 22.67 ± 1.84 days). No significant difference was observed between the phenotypes of the fibroblasts obtained from the first explants culture and cultures less than 10 times (p > 0.05).

DISSCUSSION

Taken together, this study provides an effective method for the primary culture of KFs with a higher specimen utilization rate and shorter culture cycle.

CONCLUSION

This method breaks through the limitation of traditional explants culture requiring a large number of keloid specimens and provides a rich source of KFs for the study of keloid.

LncRNA-ZNF252P-AS1/miR-15b-5p promotes the proliferation of keloid fibroblast by regulating the BTF3-STAT3 signaling pathway

BACKGROUND

JAK2/STAT3 signaling pathway plays an important role in keloid formation, but the upstream mechanism of their activation remains unclear.

OBJECTIVE

This study aims to investigate the possible mechanism of lncRNA-ZNF252P-AS1 in keloid.

METHODS

The differentially expressed genes in keloid and their upstream regulatory miRNAs and long non-coding RNAs (lncRNAs) were analyzed by bioinformatics database, and the targeting relationship was further verified by dual-luciferase reporter gene assay. LncRNA function as competitive endogenous RNA (ceRNA) in keloid was further verified by in keloid fibroblasts (KFs) and in nude mice with subcutaneous keloids.

RESULTS

BTF3 expression was up-regulated in keloid tissues. The targeting relationship between BTF3 and miR-15b-5p was confirmed by dual-luciferase reporter gene assay. miR-15b-5p overexpression inhibited BTF3, Bcl-2, Cyclin D1, C-myc, Collagen I, MMP2, MMP9, N-cadherin, and ZEB2 expressions in KFs, inhibited cell proliferation and migration, while promoted E-cadherin levels. BTF3 overexpression reversed miR-15b-5p effects on KFs. Bioinformatics analysis as well as clinical and cellular experiments confirmed that the lncRNA ZNF252P-AS1 was highly expressed in keloid/KFs. Dual-luciferase reporter gene assays confirmed the targeting relationship between lncRNA ZNF252P-AS1 and miR-15b-5p. LncRNA ZNF252P-AS1 overexpression inhibited miR-15b-5p and E-cadherin levels, upregulated BTF3, Bcl-2, Cyclin D1, C-myc, Collagen I, MMP2, MMP9, N-cadherin, and ZEB2 expressions, increased cell proliferation and migration, and activated JAK2/STAT3 pathway, while miR-15b-5p overexpression reversed this effect. The in vivo results were consistent with in vitro results. In vivo experiments further confirmed that lncRNA ZNF252P-AS1 reduced keloid volume and weight.

CONCLUSION

lncRNA ZNF252P-AS1 is a potential target for keloid treatment.

Circular RNAs: Emerging players in the pathogenesis of keloid

Circular RNAs (circRNAs) are a new type of non-coding RNAs originating from precursor messenger RNAs. Recent research has confirmed that circRNAs play a significant role in various biological and pathological processes, including cell viability, migration, and apoptosis. Emerging studies have demonstrated that the deregulated circRNA-miRNA-mRNA interaction network plays a key role in the development of many diseases. Increasing evidence has highlighted the role of ncRNAs (mainly miRNAs and lncRNAs) in the pathogenesis of keloids. Recently, several publications also indicated that circRNAs contribute to keloid development. The discovery of circRNAs changed the current understanding of the biology of keloids It is crucial to elucidate a circRNA-miRNA-mRNA network to understand the pathological mechanism of keloids. In the present review, we summarize the aberrant expression of regulatory roles of circRNAs in keloids. We discuss the potential clinical application of circRNAs in the diagnosis and treatment of keloids.

Keloid: Genetic susceptibility and contributions of genetics and epigenetics to its pathogenesis

Keloid, characterized by fibroproliferative disorders of the skin, can be developed in people of different genders, ages, and ethnicities. Keloid can appear in any part of the body but are especially common on the earlobe, upper torso, and triangular muscle. The genetic heterogeneity and susceptibility of KD (keloid) vary among different races and ethnicities. Studies have found that multiple loci on multiple chromosomes are associated with the pathogenesis of KD, and specific gene variants may also be involved. Despite multiple investigations attempting to uncover the etiology of keloid formation, the genetic mechanism of keloid formation remains unknown. To establish a foundation for a better understanding of the genetics and epigenetics of keloids, we have evaluated and summarized current studies which are mostly related to heredity, genetic polymorphisms, predisposing gene, DNA methylation, and non-coding RNA. We also discussed the problems and potential of genetic and epigenetic investigations of keloids, with the goal of developing new therapeutic approaches to enhance the prognosis of keloid patients.

Loureirin A Exerts Antikeloid Activity by Antagonizing the TGF-β1/Smad Signalling Pathway

It has been recently shown that loureirin A (LA), a major active component of resina draconis, might be effective in the prevention and treatment of liver fibrosis. We examined whether LA could inhibit the formation of keloids. To investigate the pharmacological effects of loureirin A on keloid formation and the underlying mechanisms. CellTiter-Blue viability assays were used to examine the proliferation of keloid fibroblasts (KFs) that were treated with LA. Fibroblast migration was evaluated using a cell migration assay. Immunofluorescence staining was used to measure the expression of α-SMA in KFs. RT-qPCR was used to evaluate the mRNA expression of Col-I, Col-III, α-SMA, Bax, and Caspase-3, while Western blotting was used to evaluate the protein expression of Col-I, Col-III, α-SMA, Bax, Caspase-3, p-Smad2, and p-Smad3. LA inhibited the proliferation of KFs and suppressed the migration and TGF-β1-induced myofibroblast differentiation of KFs. In addition, LA downregulated the mRNA and protein levels of Col-I, Col-III, and α-SMA while promoting the mRNA and protein levels of Bax and Caspase-3. Moreover, LA downregulated the protein levels of p-Smad2 and p-Smad3 in cultured TGF-β1-treated KFs ex vivo. These results show that LA has an antikeloid effect on KFs by suppressing the TGF-β1/Smad signalling pathway. Our findings suggest that LA may be a potential candidate drug for the prevention and treatment of keloids.

Identifying miRNAs Associated with the Progression of Keloid through mRNA-miRNA Network Analysis and Validating the Targets of miR-29a-3p in Keloid Fibroblasts

Background. Keloid has brought great trouble to people and currently has no uniformly successful treatment. It is urgent to find new targets to effectively prevent the progress of keloid. The current research mainly identifies the differentially expressed genes (DEGs) in keloid through high-throughput sequencing technology and bioinformatics analysis technology, to screen new therapeutic targets and potential biomarkers. However, due to the different samples, different control groups, and small sample sizes, the sequencing results obtained from different studies are quite different and lack reliability. It is necessary to analyze the existing datasets in a reasonable way. Methods. Datasets about keloid were filtered in Gene Expression Omnibus (GEO) and ArrayExpress databases according to the inclusion and exclusion criteria. The discovery datasets were used for summarizing significant DEGs, and the validation datasets were to validate the mRNA and miRNA expression levels. The Encyclopedia of RNA Interactomes (ENCORI) online platform was used to predict the interactions between miRNAs and their target mRNAs. Protein-protein interaction network (PPI network) analysis and functional enrichment analysis were conducted. miRNA-mRNA network was established by Cytoscape software and verified in keloid tissue ( $n=8$ ) by RT-qPCR. miR-29a-3p mimic and inhibitor were transfected into keloid fibroblasts (KFs) to preliminary verify its targets, the prognostic value of which was estimated by the receiver operating characteristic (ROC) curve. Results. A total of 6 datasets involving 20 patients were included. 15 miRNAs and 12 target mRNAs were identified as potential biomarkers for keloid patients. The RT-qPCR results showed that miR-29a-3p, miR-92a-3p, and miR-143-3p were downregulated, and all their target mRNAs were upregulated in keloid tissue ( $P<0.05$ ). The expression of COL1A1, COL1A2, COL3A1, COL5A1, and COL5A2 decreased when miR-29a-3p was overexpressed but increased when miR-29a-3p was knocked down ( $P<0.05$ ). And these genes had a good performance in the diagnosis of keloid, especially when using keloid nonlesional skin or normal scar tissues as controls. Conclusion. The miRNA-mRNA network, especially miR-29a-3p and its targets, may provide insights into the underlying pathogenesis of keloid and serve as potential biomarkers for keloid treatment.

The emerging therapeutic targets for scar management: genetic and epigenetic landscapes

Background

Wound healing is a complex process including hemostasis, inflammation, proliferation, and remodeling during which an orchestrated array of biological and molecular events occurs to promote skin regeneration. Abnormalities in each step of the wound healing process lead to reparative rather than regenerative responses, thereby driving the formation of cutaneous scar. Patients suffering from scars represent serious health problems such as contractures, functional and esthetic concerns as well as painful, thick, and itchy complications, which generally decrease the quality of life and impose high medical costs. Therefore, therapies reducing cutaneous scarring are necessary to improve patients' rehabilitation.

Summary

Current approaches to remove scars, including surgical and nonsurgical methods, are not efficient enough, which is in principle due to our limited knowledge about underlying mechanisms of pathological as well as the physiological wound healing process. Thus, therapeutic interventions focused on basic science including genetic and epigenetic knowledge are recently taken into consideration as promising approaches for scar management since they have the potential to provide targeted therapies and improve the conventional treatments as well as present opportunities for combination therapy. In this review, we highlight the recent advances in skin regenerative medicine through genetic and epigenetic approaches to achieve novel insights for the development of safe, efficient, and reproducible therapies and discuss promising approaches for scar management.

Key Message

Genetic and epigenetic regulatory switches are promising targets for scar management, provided the associated challenges are to be addressed.

Biomechanical Regulatory Factors and Therapeutic Targets in Keloid Fibrosis

Keloids are fibroproliferative skin disorder caused by abnormal healing of injured or irritated skin and are characterized by excessive extracellular matrix (ECM) synthesis and deposition, which results in excessive collagen disorders and calcinosis, increasing the remodeling and stiffness of keloid matrix. The pathogenesis of keloid is very complex, and may include changes in cell function, genetics, inflammation, and other factors. In this review, we aim to discuss the role of biomechanical factors in keloid formation. Mechanical stimulation can lead to excessive proliferation of wound fibroblasts, deposition of ECM, secretion of more pro-fibrosis factors, and continuous increase of keloid matrix stiffness. Matrix mechanics resulting from increased matrix stiffness further activates the fibrotic phenotype of keloid fibroblasts, thus forming a loop that continuously invades the surrounding normal tissue. In this process, mechanical force is one of the initial factors of keloid formation, and matrix mechanics leads to further keloid development. Next, we summarized the mechanotransduction pathways involved in the formation of keloids, such as TGF-β/Smad signaling pathway, integrin signaling pathway, YAP/TAZ signaling pathway, and calcium ion pathway. Finally, some potential biomechanics-based therapeutic concepts and strategies are described in detail. Taken together, these findings underscore the importance of biomechanical factors in the formation and progression of keloids and highlight their regulatory value. These findings may help facilitate the development of pharmacological interventions that can ultimately prevent and reduce keloid formation and progression.

The Polygenic Map of Keloid Fibroblasts Reveals Fibrosis-Associated Gene Alterations in Inflammation and Immune Responses

Due to many inconsistencies in differentially expressed genes (DEGs) related to genomic expression changes during keloid formation and a lack of satisfactory prevention and treatment methods for this disease, the critical biomarkers related to inflammation and the immune response affecting keloid formation should be systematically clarified. Normal skin/keloid scar tissue-derived fibroblast genome expression data sets were obtained from the Gene Expression Omnibus (GEO) and ArrayExpress databases. Hub genes have a high degree of connectivity and gene function aggregation in the integration network. The hub DEGs were screened by gene-related protein–protein interactions (PPIs), and their biological processes and signaling pathways were annotated to identify critical biomarkers. Finally, eighty-one hub DEGs were selected for further analysis, and some noteworthy signaling pathways and genes were found to be closely related to keloid fibrosis. For example, IL17RA is involved in IL-17 signal transduction, TIMP2 and MMP14 activate extracellular matrix metalloproteinases, and TNC, ITGB2, and ITGA4 interact with cell surface integrins. Furthermore, changes in local immune cell activity in keloid tissue were detected by DEG expression, immune cell infiltration, and mass CyTOF analyses. The results showed that CD4+ T cells, CD8+ T cells and NK cells were abnormal in keloid tissue compared with normal skin tissue. These findings not only support the key roles of fibrosis-related pathways, immune cells and critical genes in the pathogenesis of keloids but also expand our understanding of targets that may be useful for the treatment of fibrotic diseases.

Clinical Observation of Subepidermal Vascular Network Flaps in Keloid Patients

BACKGROUND

There are many different keloid treatment modalities. One surgical technique is to keep the "shell" of the keloid to cover the defect. We named this "shell" keloid subepidermal vascular network flap (KSVNF), and we outlined the characteristics of this flap by observing 35 flaps in keloid patients.

METHODS

A total of 35 KSVNFs were designed in 15 patients during 2020-2021. All patients underwent the operation and adjuvant radiotherapy as well as hyperbaric oxygen therapy. All flap lengths and widths were recorded, and the blood perfusion of the flaps was measured on the first day postoperation and the day of stitch removal. Flap survival and the quality of flaps were evaluated on the day of stitch removal. All harvested data were analyzed using the R (version 4.0.1) package.

RESULTS

The mean blood perfusion on the first day postoperation (pod1) and the day of stitch removal was 120.4013 and 168.6900, respectively (p = 0.02249); 2 flaps had partial necrosis (5.714%). Receiver operating characteristic (ROC) curve analysis showed that when the length/width ratio was less than 1.05, the quality of the flap was good (AUC = 0.724), which suggests that the effective safe length/width ratio was 1.05.

CONCLUSION

KSVNF is an applicable method for covering the remaining wound after keloid mass removal with sufficient blood perfusion and adequate skin quality. We recommend that the length/width ratio of the flap design not exceed 1.

LEVEL OF EVIDENCE IV

This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies, and Experimental Studies. 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 .

Warburg effect in keloids: A unique feature different from other types of scars

Keloid fibroblasts (KFs) undergo reprogramming of the metabolic phenotype from oxidative phosphorylation to the Warburg effect. However, more studies are needed to demonstrate whether there is a Warburg effect in KFs and to determine whether there is a similar phenomenon in other types of scars or in the proliferative stage of scars. In our study, the mRNA and protein expression of key glycolytic enzymes, glucose consumption and lactate production in KFs, normal skin fibroblasts (NFs), atrophic scar fibroblasts (ASFs), proliferative stage scar fibroblasts (PSSFs), and hypertrophic scar fibroblasts (HSFs) were detected. In addition, the effects of 2-deoxy-d-glucose (2-DG, a glycolysis inhibitor) on cell proliferation in KFs and NFs were studied. We found that the mRNA and protein expression of key glycolytic enzymes in KFs were significantly upregulated compared with those in NFs. Glucose consumption and lactate production in KFs were also higher than that in NFs. However, we found no similar phenomenon in ASFs, PSSFs, or HSFs. When treated with 2mmol/l 2-DG, the cell viability of KFs decreased more than that of NFs. What's more, treatment with increasing concentrations of 2-DG could inhibit cell viability and migration of KFs in a dose-dependent manner. In conclusion, the Warburg effect in KFs is a feature different from ASFs, PSSFs, or HSFs. Keloids are essentially different from other types of scars in terms of energy metabolism. This characteristic of KFs could provide new hope for the early diagnosis and treatment of keloids.

Alu repetitive sequence CpG methylation changes in burn scars

Alu elements are retrotransposons related to epigenetic modifications. To date, the role of epigenetics in hypertrophic scars from burn remains unknown. Here, our aim was to examine the pathophysiology of hypertrophic scars from an epigenetic perspective. For that, we performed a cross-sectional analytical study using tissue and blood samples from burned and healthy patients (n = 23 each) to detect Alu methylation levels and patterns. The results of the combined bisulfite restriction analysis technique were categorized into four groups based on the methylation status at the CpG dinucleotides from the 5' to the 3' ends of the Alu sequence: hypermethylated (^mC^mC), hypomethylated (^uC^uC), and partially methylated (^uC^mC and ^mC^uC). Alu methylation levels were significantly lower in hypertrophic scar tissues than in normal skin (29.37 ± 2.49% vs. 35.56 ± 3.18%, p = 0.0002). In contrast, the levels were significantly higher in white blood cells from blood samples of burned patients than in those of control blood samples (26.92 ± 4.04% vs. 24.58 ± 3.34%, p = 0.0278). Alu total methylation (^mC) and the ^uC^mC pattern were significantly lower, whereas ^uC^uC was significantly higher, in hypertrophic scar tissues than in normal skin (p < 0.0001). Receiver operating characteristic analysis indicated that the ^uC^mC and ^uC^uC patterns are useful as hypertrophic scar DNA methylation markers after burn, with 91.30% sensitivity and 96.23% specificity and 100% sensitivity and 94.23% specificity, respectively. Our findings suggest that epigenetic modifications play a major role in hypertrophic scar pathogenesis, and may be the starting point for developing a novel technique for burn scar treatment.

A Scoping Review of the Methodology Used in Studies of Genetic Influences on the Development of Keloid or Hypertrophic Scarring in Adults and Children After Acute Wounding

Significance: Keloid and hypertrophic scarring are common following acute wounds. However, the variability in scarring outcomes between individuals and in particular, the association between genetic factors and scarring, is not well understood. This scoping review aims to summarize the methodology used in studies of genetic influences on the development of keloid or hypertrophic scarring in adults and children after acute wounding. The objectives were to determine the study designs used, the characteristics of participants included, the tools used to assess scarring and the length of follow-up after wounding. Recent Advances: The review was conducted according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Medline, Excerpta Medica Database (EMBASE), Web of Science, Biosciences Information Service (BIOSIS), Prospective Register of Systematic Reviews (PROSPERO), The Human Genetic Epidemiology (HuGE) Navigator (database of genetic association studies), and the genome-wide association study Catalog were searched from January 2008 to April 2020. Cohort studies and case-control studies that examined the association between one or more genetic variations and the development of keloid or hypertrophic scarring were eligible for inclusion. A narrative synthesis that grouped studies by wound type was conducted. Critical Issues: Nine studies met the inclusion criteria (five in burns, four surgical wounds, and none in other types of acute wounds). Seven assessed hypertrophic scarring, one keloid scarring, and one both scar types. Seven studies used a prospective cohort design. All studies used subjective methods (clinician or patient observation) to assess scarring. There was considerable variation in how scar scales were operationalized. Future Directions: This review identified a small body of evidence on genetic susceptibility to scarring after acute wounding. Further studies are needed, and in a wide range of populations, including patients with wounds caused by trauma.

Network Meta-Analysis of Different Clinical Commonly Used Drugs for the Treatment of Hypertrophic Scar and Keloid

Background: There is no uniform treatment for pathological scars, including keloids and hypertrophic scars, in clinic currently. Previously, multiple randomized controlled trials have examined the clinical efficacy of different treatments. Nonetheless, the results are inconsistent, and many treatments have not been directly compared. This makes it difficult to conclude which approach is more favorable, in terms of efficacy and safety, for the treatment of pathological scarring. This study aimed at evaluating the efficacy of different injection and topical treatment strategies for hypertrophic scar and keloid.

Methods: Relevant literature from PubMed, Medline, Embase, Scopus, the Cochrane Central Register of Controlled Trials (CCRCT), and WHO International Clinical Trials Registry Platform (WHO-ICTRP) were searched, from database inception through November 2020. Randomized clinical trials evaluating different treatment strategies of pathological scars, including triamcinolone acetonide (TAC), verapamil (VER), 5-fluorouracil (5-FU), botulinum toxin A (BTA), bleomycin (BLM), and silicone gels were included in the study.

Results: The network meta-analysis included a total of 2,009 patients from 29 studies. A network meta-analysis of injection and topical treatment strategies showed that the efficacy of TAC combined with BTA was best in the treatment of pathological scars. Combination therapies of TAC with 5-FU and TAC with BTA significantly improved the clinical efficiency. However, there was no statistically significant difference between other treatment strategies. The order of efficacy predicted by the surface under the cumulative ranking (SUCRA) curve was as follows: TAC+BTA (82.2%) > TAC+5-FU (69.8%) > BTA (67.3%) > 5-FU+silicone (59.4%) > TAC+silicone (58.3%) > 5-FU (49.8%) > BLM (42.0%) > TAC (26.7%) > VER (26.2%) > silicone (18.3%). There was no publication bias revealed based on the funnel diagram.

Conclusion: This study recommends intralesional injection of TAC-BTA and TAC-5-FU combined therapies. But for patients who cannot tolerate the side effects, the use of silicone gels in combination with TAC is recommended. However, these conclusions need to be further confirmed by more randomized controlled trials.

Botulinum toxin A promotes the transdifferentiation of primary keloid myofibroblasts into adipocyte-like cells

Keloid is a type of unusually raised scar. Botulinum toxin A (BTX-A) has a great application potential in keloids treatment. Here, we investigated the functional role of BTX-A in keloids. We separated keloid tissues and normal skin tissues from keloid patients and found that the expression of myofibroblast markers, α-SMA, Collagen I, and Collagen III was increased in the keloid tissues as compared with normal skin tissues. Keloid fibroblasts derived from keloid tissues were treated with TGF-β1 to induce the differentiation of fibroblasts into myofibroblasts. The keloid myofibroblasts displayed a significant up-regulation of α-SMA. BTX-A enhanced the expression of adipocyte markers, PPARγ and C/EBPα, and increased the accumulation of lipid droplets, and reduced the expression of α-SMA, Collagen I, and Collagen III in the keloid myofibroblasts. Moreover, BTX-A enhanced the expression of BMP4 and p-smad1/5/8. Noggin (BMP4 antagonist) treatment reversed BTX-A-mediated increase of PPARγ and C/EBPα expression and lipid droplets, and down-regulation of α-SMA, Collagen I, and Collagen III in primary keloid myofibroblasts. In conclusion, BTX-A promoted the transdifferentiation of primary keloid myofibroblasts into adipocyte-like cells, which may attribute to activate BMP4/Smad signalling pathway. Thus, this study provides new insights into the mechanism of BTX-A in keloid.

Keloid fibroblasts have elevated and dysfunctional mechanotransduction signaling that is independent of TGF-β

BACKGROUND

Fibroblasts found in keloid tissues are known to present an altered sensitivity to microenvironmental stimuli. However, the impact of changes in extracellular matrix stiffness on phenotypes of normal fibroblasts (NFs) and keloid fibroblasts (KFs) is poorly understood.

OBJECTIVES

Investigation the impact of matrix stiffness on NFs and KFs mainly via detecting yes-associated protein (YAP) expression.

METHODS

We used fibronectin-coated polyacrylamide hydrogel substrates with a range from physiological to pathological stiffness values with or without TGF-β (fibrogenic inducer). Atomic force microscopy was used to measure the stiffness of fibroblasts. Cellular mechanoresponses were screened by immunocytochemistry, Western blot and Luminex assay.

RESULTS

KFs are stiffer than NFs with greater expression of α-SMA. In NFs, YAP nuclear translocation was induced by increasing matrix stiffness as well as by stimulation with TGF-β. In contrast, KFs showed higher baseline levels of nuclear YAP that was not responsive to matrix stiffness or TGF-β. TGF-β1 induced p-SMAD3 in both KFs and NFs, demonstrating the pathway was functional and not hyperactivated in KFs. Moreover, blebbistatin suppressed α-SMA expression and cellular stiffness in KFs, linking the elevated YAP signaling to keloid phenotype.

CONCLUSIONS

These data suggest that whilst normal skin fibroblasts respond to matrix stiffness in vitro, keloid fibroblasts have elevated activation of mechanotransduction signaling insensitive to the microenvironment. This elevated signaling appears linked to the expression of α-SMA, suggesting a direct link to disease pathogenesis. These findings suggest changes to keloid fibroblast phenotype related to mechanotransduction contribute to disease and may be a useful therapeutic target.

Mediation of Anti-Keloid Effects of mTOR Inhibitors by Autophagy-Independent Machinery

Objective:

Blocking mechanistic target of rapamycin (mTOR) activation with mTOR inhibitors has promising therapeutic potential for keloids. However, the precise mechanism of mTOR inhibitors remains unclear. This study was aimed to investigate the role of autophagy machinery in the anti-keloid effects of mTOR inhibitors.

Methods:

We first validated the biological effects induced by the mTOR inhibitors rapamycin (100 nmol/L) and KU-0063794 (5 μmol/L) on the proliferation, apoptosis, migration, and collagen synthesis of keloid fibroblasts (KFs) derived from Han Chinese persons through a Cell Counting Kit-8 assay, 5-Bromo-2’-deoxyuridine incorporation, Annexin V/propidium iodide staining, migration, and western blotting. To explore whether autophagy machinery is involved in the anti-keloid effects of mTOR inhibitors, we first blocked the autophagy activation induced by rapamycin and KU-0063794 with a pharmacological autophagy inhibitor (wortmannin) or by silencing the key autophagy gene (ATG5), and we then re-evaluated these biological effects on KFs.

Results:

Blocking mTOR activation with either rapamycin or KU-0063794 completely inhibited proliferation, migration, and collagen synthesis of primary KFs but did not affect apoptosis. Incubating KFs with the autophagy inhibitor wortmannin or performing ATG5 silencing abrogated the subsequent activation of autophagic activity induced by rapamycin (rapamycin + E-64d + pepstatin vs. rapamycin + wortmannin + E-64d + pepstatin: 1.88 ± 0.38 vs. 1.02 ± 0.35, F = 6.86, P = 0.013), (non-sense control + rapamycin vs. ATG5 small interfering RNA + rapamycin: 1.46 ± 0.18 vs. 0.75 ± 0.20, respectively; F = 7.68, P = 0.01) or KU-0063794 (KU-0063794 + E-64d + pepstatin vs. KU-0063794 + wortmannin + E-64d + pepstatin: 1.65 ± 0.35 vs. 0.76 ± 0.17, F = 10.01, P = 0.004), (NC + KU-0063794 vs. ATG5 small interfering RNA + KU-0063794: 1.59 ± 0.50 vs. 0.77 ± 0.09, F = 5.93, P = 0.02) as evidenced by decreased accumulation of LC3-II. However, blockage of autophagy induction in mTOR inhibitor-treated KFs with both methods did not disturb their anti-keloid effects, such as inhibition of cell viability, cell migration, and collagen synthesis (P > 0.05 each).

Conclusion:

Blocking mTOR activation with the mTOR inhibitors rapamycin and KU-0063794 showed anti-keloid effects in KFs. Restoration of autophagy inhibition by mTOR inhibitors does not contribute to their anti-keloid effects.

Protein tyrosine phosphatase 1B regulates fibroblasts proliferation, motility and extracellular matrix synthesis via the MAPK/ERK signalling pathway in keloid

Keloid is a fibroproliferative disorder resulting from trauma, characterized by abnormal activation of keloid fibroblasts and excessive deposition of extracellular matrix (ECM). It affects life quality of patients and lacks of effective therapeutic targets. Protein tyrosine phosphatase 1B (PTP1B) belongs to the protein tyrosine phosphatases and participates in many cellular processes such as metabolism, proliferation and motility. It has been reported that PTP1B negatively regulated diabetic wound healing and tumor progression. However, its effects in keloid remain unclear. Here, we aimed to evaluate the effects of PTP1B on keloid fibroblasts which play essential roles in keloids pathogenesis. Our results revealed that PTP1B expression was decreased both in keloid tissues and in keloid fibroblasts compared to healthy controls. Keloid fibroblasts (KFs) showed higher cell proliferation, motility, ECM production and ERK activity than normal fibroblasts (NFs). Overexpression of PTP1B in KFs and NFs inhibited cell proliferation, motility, ECM synthesis and the MAPK/ERK signalling pathway while knockdown of PTP1B showed converse effects. The rescue experiments with ERK inhibitor further verified that MAPK/ERK signalling pathway involved in PTP1B regulatory network. Taken together, our findings indicated that overexpression of PTP1B suppressed keloid fibroblasts bio-behaviours and promoted their phenotype switch to normal cells via inhibiting the MAPK/ERK signalling pathway, suggesting it may be a potential anti-keloid therapy.

[A multicenter prospective randomized controlled clinical study of 5-fluorouracil in different mass concentrations combined with triamcinolone in the treatment of keloids]

Objective: To evaluate the clinical effects of 5-fluorouracil in different mass concentrations combined with triamcinolone in the treatment of keloids. Methods: From March 2018 to March 2019, 29 patients with 31 keloids receipted in the Department of Plastic Surgery of Fujian Medical University Union Hospital, 11 patients with 20 keloids receipted in the Department of Dermatology of Pingtan Comprehensive Experimental Area Hospital, and 9 patients with 9 keloids receipted in the Fuzhou Heisey-Dea Aesthetic Clinic were included in this prospectively randomized control study, with 27 males and 22 females, aged (30±9) years. According to the random number table, the keloids were divided into low mass concentration group (19 keloids, 17 patients), medium mass concentration group (21 keloids, 19 patients), and high mass concentration group (20 keloids, 17 patients). Then 5-fluorouracil at mass concentrations of 0.5, 5.0, and 12.5 mg/mL combined with triamcinolone acetonide were injected respectively, once every 4 weeks, for a total of 3 times. Before the first treatment and in 3 months after the last treatment, the appearance of keloids was evaluated by Vancouver Scar Scale (VSS) and pain and pruritus of keloids were evaluated by Visual Analogue Scale (VAS). Then the score differences before and after the treatment were calculated. In 6 months after the last treatment, the patients' efficacy satisfaction was evaluated by efficacy satisfaction rating scale. Adverse reactions during the treatment were recorded. In the follow-up of one year after the last treatment, the recurrence rates of keloids were counted. Data were statistically analyzed with chi-square test, one-way analysis of variance, paired sample t test, least significant difference t test, Wilcoxon rank sum test, Kruskal-Wallis rank sum test, or Fisher's exact probability test. Results: Before the first treatment, the appearance VSS scores of appearance of keloids in the three groups were similar (F=0.039, P>0.05). In 3 months after the last treatment, the appearance VSS scores of keloids in low mass concentration group were significantly higher than those in medium mass concentration group and high mass concentration group (t=2.267, 4.086, P<0.05 or P<0.01). In 3 months after the last treatment, the appearance VSS scores of keloids in low mass concentration group, medium mass concentration group, and high mass concentration group were significantly decreased compared with those before the first treatment (t=18.222, 44.272, 22.523, P<0.01). The differences of appearance VSS scores of keloids in low mass concentration group before and after treatment were significantly lower than those in medium mass concentration group and high mass concentration group (t=-4.096, -6.357, P<0.01), and the differences of appearance VSS scores of keloids in medium mass concentration group before and after treatment were significantly lower than those in high mass concentration group (t=-2.368, P<0.05). Before the first treatment, the pain and pruritus VAS scores of keloids in the three groups were similar (χ2=0.149, P>0.05). In 3 months after the last treatment, the pain and pruritus VAS scores of keloids in low mass concentration group were significantly higher than those in medium mass concentration group and high mass concentration group (Z=2.191, 4.386, P<0.05 or P<0.01), and the pain and pruritus VAS scores of keloids in medium mass concentration group were significantly higher than those in high mass concentration group (Z=2.276, P<0.05). In 3 months after the last treatment, the pain and pruritus VAS scores of keloids in medium mass concentration group and high mass concentration group were significantly decreased compared with those before the first treatment (Z=-3.904, -3.844, P<0.01). The differences of pain and pruritus VAS scores of keloids in low mass concentration group before and after treatment were significantly lower than those in medium mass concentration group and high mass concentration group (Z=-4.265, -6.104, P<0.01). In 6 months after the last treatment, the efficacy satisfaction scores of the corresponding patients of keloids were (88±8) points in high mass concentration group, which were significantly higher than (76±8) points in medium mass concentration group and (60±8) points in low mass concentration group (t=-3.820, -6.675, P<0.01), and the efficacy satisfaction scores of the corresponding patients of keloids in medium mass concentration group were significantly higher than those in high mass concentration group (t=-2.984, P<0.05). There was only statistically significant difference in pain within the 3 groups (P<0.01). In the follow-up of one year after the last treatment, the recurrence rate of keloids in high mass concentration group was significantly lower than that in low mass concentration group (χ2=8.313, P<0.01), and the recurrence rate of keloids in medium mass concentration group was similar to the recurrence rates in low mass concentration group and high mass concentration group (P>0.05). Conclusions: After treating keloids with high mass concentration of 5-fluorouracil combined with triamcinolone acetonide, the symptoms were significantly improved, the efficacy satisfaction of patients was increased, with no obvious adverse reactions but long lasting efficacy. Their overall effects are better than treatment using medium and low mass concentrations of 5-fluorouracil, which is worthy of clinical promotion.

Association between MeCP2 and Smad7 in the pathogenesis and development of pathological scars

To explore the relationship between methylated binding protein 2 (MeCP2) and mothers against decapentaplegic homolog 7 (Smad7) in the pathogenesis and development of pathological scars. Immunohistochemistry, Western blot and real-time polymerase chain reaction (RT-PCR) were used to detect the expression of MeCP2 in different types of human scars and hypertrophic scars at different growth times. The methylation status of Smad7 gene promoter in different scar tissues was determined by methylation-specific PCR. After transfection with MeCP2-siRNA (small interfering RNA) in human keloid fibroblasts, MTT assay was used to assess the proliferation activity of keloid fibroblasts, while RT-PCR and Western blot assays were used to detect the expression levels of MeCP2, transforming growth factor-β1 (TGF-β1), α-smooth muscle actin (α-SMA), phospho-Smad2 (p-Smad2) and Smad7. MeCP2 was mainly expressed in the nucleus of fibroblasts. The mRNA and protein levels of MeCP2 were significantly higher in keloids than in hypertrophic scars, normal scars and normal skin (p<.05). The expression level of MeCP2 in hypertrophic scars during the growth period of <6 months was markedly higher than that of >6 months (p<.05). The methylation level of Smad7 was significantly higher in keloids compared to normal skin. After MeCP2 silencing, the proliferation rate of human keloid fibroblasts was decreased, the mRNA and protein levels of Smad7 were increased, and the expression levels of TGF-β1, α-SMA and p-Smad2 were decreased (p<.05). MeCP2 and Smad7 play an important role in formation of pathological scars. During keloid formation, MeCP2 weakens the inhibitory effect of Smad7 on p-Smad2/3 by downregulating the expression of Smad7, which in turn promotes fibrosis and scar hyperplasia.

Identifying miRNA modules associated with progression of keloids through weighted gene co-expression network analysis and experimental validation in vitro

Keloid is a type of skin fibroproliferative disease, characterized by excessive deposition of collagen in the extracellular matrix, myofibroblast activation and invasive growth to the surrounding normal skin tissue. However, the specific pathogenesis of keloids is not yet fully understood and existing treatment strategies are unsatisfied. It is therefore urgent to explore new biomarkers associated with its progression for keloids. In this study, the microarray dataset GSE113620 was downloaded from the Gene Expression Omnibus (GEO) database to screen out the differential expression of miRNAs (DEMs). The DEMs with large variance were applied to construct a weighted gene co-expression network to identify miRNA modules that are closely relevant to keloid progression. It is worth noting that miR-424-3p in the blue module (r = 0.98, p = 1e-18) is considered to be the ultimate target most relevant to keloid progression through co-expressed network analysis. Subsequently, the results of molecular biology experiments determine that miR-424-3p targeting Smad7 significantly enhanced the ability of cell proliferation, migration and collagen secretion after transfection with miR-424-3p mimic, while the apoptosis rate was significantly reduced. On the contrary, the miR-424-3p inhibitor performs the exact opposite function.

Epigenetic modification mechanisms involved in keloid: current status and prospect

Keloid, a common dermal fibroproliferative disorder, is benign skin tumors characterized by the aggressive fibroblasts proliferation and excessive accumulation of extracellular matrix. However, common therapeutic approaches of keloid have limited effectiveness, emphasizing the momentousness of developing innovative mechanisms and therapeutic strategies. Epigenetics, representing the potential link of complex interactions between genetics and external risk factors, is currently under intense scrutiny. Accumulating evidence has demonstrated that multiple diverse and reversible epigenetic modifications, represented by DNA methylation, histone modification, and non-coding RNAs (ncRNAs), play a critical role in gene regulation and downstream fibroblastic function in keloid. Importantly, abnormal epigenetic modification manipulates multiple behaviors of keloid-derived fibroblasts, which served as the main cellular components in keloid skin tissue, including proliferation, migration, apoptosis, and differentiation. Here, we have reviewed and summarized the present available clinical and experimental studies to deeply investigate the expression profiles and clarify the mechanisms of epigenetic modification in the progression of keloid, mainly including DNA methylation, histone modification, and ncRNAs (miRNA, lncRNA, and circRNA). Besides, we also provide the challenges and future perspectives associated with epigenetics modification in keloid. Deciphering the complicated epigenetic modification in keloid is hopeful to bring novel insights into the pathogenesis etiology and diagnostic/therapeutic targets in keloid, laying a foundation for optimal keloid ending.

Keloids: a review of therapeutic management

Keloid scar formation arises from a disorganized fibroproliferative collagen response that extends beyond the original wound margins because of excessive production of extracellular matrix (ECM). Despite treatment options for keloid scars including medical and surgical therapies, such as intralesional steroid injection and surgical excision, the recurrence rate remains high. Herein we consolidate recently published narrative reviews, systematic reviews, and meta-analyses to provide an overview of updated treatment recommendations for keloidal scar formation. PubMed search engine was used to access the MEDLINE database to investigate updates regarding keloid incidence and treatment. More than 100 articles were reviewed. Keloid management remains a multimodal approach. There continues to be no gold standard of treatment that provides a consistently low recurrence rate; however, the increasing number of available treatments and synergistic combinations of these treatments (i.e., laser-based devices in combination with intralesional steroids, or 5-fluorouracil (5-FU) in combination with steroid therapy) is showing favorable results. Future studies could target the efficacy of novel treatment modalities (i.e., autologous fat grafting or stem cell-based therapies) for keloid management. This review article provides updated treatment guidelines for keloids and discusses insight into management to assist patient-focused, evidence-based clinical decision making.

Monoclonal Antibodies Addressed to Factors of Signalization in Keloid Scars: Opportunities and Areas of Action

The advance of technology has made possible the use of new techniques within medicine for the treatment of diseases; monoclonal antibodies are a clear example of this. Keloid scars are one of the most difficult pathologies to treat due to the high percentage of recidivism, formed by the growth of a scar with benign fibrous tissue in genetically predisposed individuals, resulting from a process of inflammation and abnormal scarring. Monoclonal antibodies, being a line of treatment that has increased over the years, can show a new frontier in the treatment of them by focusing on the signaling that causes it. We review the literature on the signaling mechanisms of keloid scars and the possible monoclonal approach.

Identification of Differentially Methylated CpG Sites in Fibroblasts from Keloid Scars

As a part of an abnormal healing process of dermal injuries and irritation, keloid scars arise on the skin as benign fibroproliferative tumors. Although the etiology of keloid scarring remains unsettled, considerable recent evidence suggested that keloidogenesis may be driven by epigenetic changes, particularly, DNA methylation. Therefore, genome-wide scanning of methylated cytosine-phosphoguanine (CpG) sites in extracted DNA from 12 keloid scar fibroblasts (KF) and 12 control skin fibroblasts (CF) (six normal skin fibroblasts and six normotrophic fibroblasts) was conducted using the Illumina Human Methylation 450K BeadChip in two replicates for each sample. Comparing KF and CF used a Linear Models for Microarray Data (Limma) model revealed 100,000 differentially methylated (DM) CpG sites, 20,695 of which were found to be hypomethylated and 79,305 were hypermethylated. The top DM CpG sites were associated with TNKS2, FAM45B, LOC723972, GAS7, RHBDD2 and CAMKK1. Subsequently, the most functionally enriched genes with the top 100 DM CpG sites were significantly (p ≤ 0.05) associated with SH2 domain binding, regulation of transcription, DNA-templated, nucleus, positive regulation of protein targeting to mitochondrion, nucleoplasm, Swr1 complex, histone exchange, and cellular response to organic substance. In addition, NLK, CAMKK1, LPAR2, CASP1, and NHS showed to be the most common regulators in the signaling network analysis. Taken together, these findings shed light on the methylation status of keloids that could be implicated in the underlying mechanism of keloid scars formation and remission.

The Keloid Disorder: Heterogeneity, Histopathology, Mechanisms and Models

Keloids constitute an abnormal fibroproliferative wound healing response in which raised scar tissue grows excessively and invasively beyond the original wound borders. This review provides a comprehensive overview of several important themes in keloid research: namely keloid histopathology, heterogeneity, pathogenesis, and model systems. Although keloidal collagen versus nodules and α-SMA-immunoreactivity have been considered pathognomonic for keloids versus hypertrophic scars, conflicting results have been reported which will be discussed together with other histopathological keloid characteristics. Importantly, histopathological keloid abnormalities are also present in the keloid epidermis. Heterogeneity between and within keloids exists which is often not considered when interpreting results and may explain discrepancies between studies. At least two distinct keloid phenotypes exist, the superficial-spreading/flat keloids and the bulging/raised keloids. Within keloids, the periphery is often seen as the actively growing margin compared to the more quiescent center, although the opposite has also been reported. Interestingly, the normal skin directly surrounding keloids also shows partial keloid characteristics. Keloids are most likely to occur after an inciting stimulus such as (minor and disproportionate) dermal injury or an inflammatory process (environmental factors) at a keloid-prone anatomical site (topological factors) in a genetically predisposed individual (patient-related factors). The specific cellular abnormalities these various patient, topological and environmental factors generate to ultimately result in keloid scar formation are discussed. Existing keloid models can largely be divided into in vivo and in vitro systems including a number of subdivisions: human/animal, explant/culture, homotypic/heterotypic culture, direct/indirect co-culture, and 3D/monolayer culture. As skin physiology, immunology and wound healing is markedly different in animals and since keloids are exclusive to humans, there is a need for relevant human in vitro models. Of these, the direct co-culture systems that generate full thickness keloid equivalents appear the most promising and will be key to further advance keloid research on its pathogenesis and thereby ultimately advance keloid treatment. Finally, the recent change in keloid nomenclature will be discussed, which has moved away from identifying keloids solely as abnormal scars with a purely cosmetic association toward understanding keloids for the fibroproliferative disorder that they are.

Comparative Efficacy and Safety of Common Therapies in Keloids and Hypertrophic Scars: A Systematic Review and Meta-analysis

OBJECTIVES

At present, there are many therapies for treating keloids and hypertrophic scars, but there is still a lack of treatments that are relatively balanced in efficacy and safety. The study aims to evaluate comprehensively efficacy and safety of common therapies in keloids and hypertrophic scars.

METHODS

The literature search was conducted up to May 2019. The traditional meta-analysis was performed on 17 therapies. Bayesian network meta-analysis was conducted on the four most common treatments. The outcome indicators were the numbers of patients with good-to-excellent effect, Vancouver Scar Scale (VSS) and adverse events.

RESULTS

There was no significant difference in the efficacy of triamcinolone acetonide (TAC) compared with other monotherapies except for silicone gel sheet and neodymium-yttrium-aluminum-garnet in primary indicator. The combination therapies were superior to TAC, and the results were consistent after the pooled analysis (RR = 0.522, 95% CI 0.332-0.823). The level of VSS in TAC group was higher than that in 5-flurouracil (5-FU) and TAC + 5-FU group, but lower than that in verapamil (VER) group. And the patients treated with TAC were less safe than those treated with verapamil (P = 0.013). Surface under cumulative ranking ranked verapamil and TAC + 5-FU as the favorable efficacy therapies in terms of primary indicator and ranked TAC + 5-FU as the best therapy for VSS, while VER was ranked as the worst.

CONCLUSION

This meta-analysis showed that TAC + 5-FU may be the most effective therapy, while verapamil may be a better therapeutic strategy for safety.

LEVEL OF EVIDENCE III

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.

Expression profile and bioinformatics analyses of circular RNAs in keloid and normal dermal fibroblasts

Increasing evidence indicates that circular RNAs (circRNAs) play a crucial regulatory role in the pathogenesis of multiple diseases. However, no study has examined the potential biological function and expression profile of circRNAs in keloid dermal fibroblasts (KDFs). Therefore, the aim of this study to investigate the expression profile of circRNAs and analyze their role in KDFs. Bioinformatic analyses and high-throughput RNA sequencing technology were applied to explore the expression profile of circRNAs in 3 human KDFs and normal dermal fibroblasts (NDFs). The differentially expressed circRNAs were verified by reverse transcription PCR (RT-PCR), quantitative real-time-PCR (qRT-PCR) and Sanger sequencing. A circRNA-microRNA (miRNA)-mRNA interaction network was created using bioinformatics tools. Hsa_circ_0008259, was selected to confirm its function by qRT-PCR and Western blot. Collectively, 411 circRNAs, of which 206 were upregulated and 205 decreased, were found to be differentially expressed in KDFs and could bind to 2532 miRNA response elements (MREs). GO and KEGG pathways enrichment analyses showed that differentially expressed circRNAs were mainly involved in apoptosis, focal adhesion, PI3K-Akt and metabolic pathway, and may regulate the pathogenesis and development of keloid. Two candidate circRNAs (hsa_circRNA_0008259, hsa_circRNA_0005480) were verified to be significantly reduced in KDFs, and one candidate circRNA (hsa_circRNA_0002198) was significantly elevated in accordance with RNA-Seq data analysis. Overexpression of hsa_circRNA_0008259 inhibited type I and Ⅲ collagen expression. Taken together, our study demonstrates for the first time that circRNAs exhibits differential expression in KDFs, and may be key players in the pathogenesis of keloid, or act as biomarkers of keloid.