Keloid Tissue Samples Research Articles

The m6A-methylated mRNA pattern and the activation of the Wnt signaling pathway under the hyper-m6A-modifying condition in the keloid.

Purpose: The present study was carried out to investigate the global m6A-modified RNA pattern and possible mechanisms underlying the pathogenesis of keloid. Method: In total, 14 normal skin and 14 keloid tissue samples were first collected on clinics. Then, three samples from each group were randomly selected to be verified with the Western blotting to determine the level of methyltransferase and demethylase. The total RNA of all samples in each group was isolated and subjected to the analysis of MeRIP sequencing and RNA sequencing. Using software of MeTDiff and htseq-count, the m6A peaks and differentially expressed genes (DEGs) were determined within the fold change >2 and p-value < 0.05. The top 10 pathways of m6A-modified genes in each group and the differentially expressed genes were enriched by the Kyoto Encyclopedia of Genes and Genomes signaling pathways. Finally, the closely associated pathway was determined using the Western blotting and immunofluorescence staining. Results: There was a higher protein level of WTAP and Mettl3 in the keloid than in the normal tissue. In the keloid samples, 21,020 unique m6A peaks with 6,573 unique m6A-associated genetic transcripts appeared. In the normal tissue, 4,028 unique m6A peaks with 779 m6A-associated modified genes appeared. In the RNA sequencing, there were 847 genes significantly changed between these groups, transcriptionally. The genes with m6A-methylated modification and the upregulated differentially expressed genes between two tissues were both mainly related to the Wnt signaling pathway. Moreover, the hyper-m6A-modified Wnt/β-catenin pathway in keloid was verified with Western blotting. From the immunofluorescence staining results, we found that the accumulated fibroblasts were under a hyper-m6A condition in the keloid, and the Wnt/β-Catenin signaling pathway was mainly activated in the fibroblasts. Conclusion: The fibroblasts in the keloid were under a cellular hyper-m6A-methylated condition, and the hyper-m6A-modified highly expressed Wnt/β-catenin pathway in the dermal fibroblasts might promote the pathogenesis of keloid.

Macrophages of the M1 and M2 types play a role in keloids pathogenesis.

The pathophysiology of keloid formation is unknown, however, macrophages are thought to play a role in keloid formation. Understanding the mechanism(s) of keloid development might be crucial in developing a new treatment regimen for keloids. The aim of this study was to understand possible status of M1 and M2 type macrophages in the pathogenesis of keloid. Thirty cases of Keloid tissues were selected according to our inclusion and exclusion criteria, as well as 30 normal scars, were enrolled in our study as a control group. An excisional biopsy was harvested and ELISA was done on keloid tissue and normal scar samples, with CD68, the surface marker for M1 and CD163 representing M2. The results revealed the low expression of M1 (CD68) in keloid tissue meanwhile high levels of M1 were detected in normal scars. We also detected that higher tissue expression of M2 (CD163) was significantly associated with keloid cases when compared to low M2 expression in the control group. An important finding that was discovered during our study is that the M1 and M2 are significant predictors of keloid. Every increase of 1 ng/mL in M1 decreases the risk of keloid by 0.99 while every increase of one unit in M2 increases the risk of keloid by 2.01. This study concluded that the keloid formation could be a result of an abnormal response to tissue injury where there is an excessive entry of inflammatory cells into the wound, including macrophages and that the keloid incidence might be related to a decrease in M1 and an increase in M2.

Integrated Analysis of Single-Cell and Spatial Transcriptomics in Keloids: Highlights on Fibrovascular Interactions in Keloid Pathogenesis

Studies on the etiopathogenesis of keloids mostly have focused on fibroblasts and their dysfunction. In this study, two cutting-edge technologies, single-cell RNA sequencing and spatial transcriptomics, were applied to uncover the underlying pathophysiology of keloids. Keloid tissue samples and normal skin control data were analyzed as well as those of patient-matched keloid and normal mature scar. Single-cell RNA sequencing revealed cellular heterogenicity such as fibroblasts, endothelial cells (ECs), and myofibroblasts within the keloids. Spatial transcriptomics results showed that disease-associated fibroblasts were enriched in the deeper keloid areas, mostly located around the spots with endothelial transcripts. Mesenchymal activation was observed in keloid ECs, characterized by dysregulation of TGF-β/SMAD signaling. Colocalization of mesenchymal and vascular markers through multiplex immunofluorescence suggested mesenchymal activation of keloid ECs. Cell‒cell interaction analysis identified a significant network between keloid fibroblasts and ECs, and this cellular crosstalk was supported by colocalization analysis of spatial transcriptomics. This study depicted the cellular landscape of keloids at a single-cell resolution as well as the integration of single-cell and valuable spatial data of keloids using spatial transcriptomics and multiplex immunofluorescence technologies. Our findings suggested a potential role of fibrovascular communication and mesenchymal activation of ECs that might be involved in the keloid pathogenesis.

Immune-related gene expression in skin, inflamed and keloid tissue from patients with keloids.

Keloids are a tumor-like fibroproliferative skin disease that could cause disfigurement and disability. The pathological mechanisms underlying this condition remain unclear, particularly the progression from normal healthy skin to inflammatory skin tissue, then keloid. In the present study, three immune-related gene expression profiling datasets, were obtained from normal skin tissue (N group), inflamed tissue (I group) and keloid tissue samples from patients with keloids (K group). This sample grouping represents the primary steps of keloid formation, from normal to inflammatory, and finally to keloid tissue. The expression levels of immune-related genes were analyzed, and the differentially expressed genes (DEGs) between the three groups were compared. Protein-protein interaction networks were established using Cytoscape. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analyses were carried out to determine the main functions associated with the DEGs and keloid-associated pathways. The results identified hub genes in the N and I groups, including C-C motif chemokine receptor (CCR) 1, CCR7, CD40 ligand, C-X-C motif chemokine ligand 9, IL-6 and IL-10. The hub genes in the I and the K groups included IL-10, IL-6, IL-13 and CD86. The expression levels of these genes were verified using reverse transcription-quantitative PCR. The results demonstrated that IL-6 expression levels were significantly increased in the I group compared with the N group (P=0.0111). CCR7 levels significantly differed between all three groups (P<0.017). The results of GO analysis suggested that the hub genes in the I and N groups may be associated with ‘regulation of lymphocyte activation’ and ‘T-cell activation’. Similar results were also observed between the I and K groups, which may play an important role in keloid initiation and formation. In conclusion, CCR7, IL-10 and IL-6 may be important in keloid initiation and formation. These findings provided insight into the pathogenesis of keloids and may help identify novel immune-related therapeutic targets for this condition.

Multitranscriptome analyses of keloid fibroblasts reveal the role of the HIF-1α/HOXC6/ERK axis in keloid development.

BackgroundA keloid is a disease of excessive fibrosis that is characterized by the aberrant proliferation of fibroblasts. However, the molecular mechanisms of fibroblasts during the development of keloids remain unclear. This study aims to identify new molecular targets that promote the proliferation and migration of keloid fibroblasts, providing new ideas for the prevention and treatment of keloids.MethodsWe utilized bioinformatics tools to analyze data from keloid fibroblasts (KFs) available in the Gene Expression Omnibus (GEO) database to identify the key genes involved in keloid development. Homeobox C6 (HOXC6) emerged as a hub gene in KFs from the GEO database was verified in keloid tissue samples and KFs using reverse transcription-quantitative polymerase chain reaction, western blot (WB) and immunohistochemistry. Subsequently, the effects of downregulated HOXC6 expression on the cellular behaviors of KFs were examined by performing Cell Counting Kit-8, flow cytometry, transwell migration and WB assays. Meanwhile, we performed transcriptome sequencing and gene set enrichment analysis (GSEA) to further explore HOXC6-related mechanisms and validated the signaling pathways by performing a series of experiments.Results HOXC6 was the top-ranking hub gene of KFs in microarray datasets from GEO and was upregulated in keloid tissue samples and KFs. Downregulation of HOXC6 inhibited proliferation, migration and extracellular matrix (ECM) accumulation and promoted KF apoptosis. GSEA predicted that the hypoxia signaling pathway was associated with HOXC6 in KFs. Transcriptome sequencing suggested that the extracellular regulated protein kinase (ERK) pathway was one of the downstream pathways of HOXC6 in KFs. Our experiments confirmed that hypoxia-inducible factor-1α (HIF-1α) upregulates HOXC6, contributing to KFs proliferation, migration, apoptosis inhibition and collagen accumulation through the ERK signaling pathway.ConclusionsOur findings first revealed that HOXC6 acts as an oncogenic driver in the molecular mechanisms of fibroblasts in keloids. The HIF-1α/HOXC6/ERK axis promotes proliferation, migration and ECM production by KFs, contributing to the progression of keloids. Taken together, HOXC6 may serve as a promising novel therapeutic target and new focus for research designed to understand the pathogenesis of keloids.

Tauroursodeoxycholic Acid Decreases Keloid Formation by Reducing Endoplasmic Reticulum Stress as Implicated in the Pathogenesis of Keloid.

Keloids are a common form of pathologic wound healing and are characterized by an excessive production of extracellular matrix. This study examined the major contributing mechanism of human keloid pathogenesis using transcriptomic analysis. We identified the upregulation of mitochondrial oxidative stress response, protein processing in the endoplasmic reticulum, and TGF-β signaling in human keloid tissue samples compared to controls, based on ingenuity pathway and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses. Electron microscopic examinations revealed an increased number of dysmorphic mitochondria and expanded endoplasmic reticulum (ER) in human keloid tissue samples than that in controls. Western blot analysis performed using human tissues suggested noticeably higher ER stress signaling in keloids than in normal tissues. Treatment with tauroursodeoxycholic acid (TUDCA), an ER stress inhibitor, significantly decreased scar formation in rabbit models, compared to normal saline and steroid injections. In summary, our findings demonstrate the contributions of mitochondrial dysfunction and dysregulated ER stress signaling in human keloid formation and the potential of TUDCA in the treatment of keloids.

Hyperbaric oxygen treatment on keloid tumor immune gene expression.

Background:Hyperbaric oxygen treatment (HBOT) has been demonstrated to influence the keloid recurrence rate after surgery and to relieve keloid symptoms and other pathological processes in keloids. To explore the mechanism of the effect of HBOT on keloids, tumor immune gene expression and immune cell infiltration were studied in this work.Methods:From February 2021 to April 2021, HBOT was carried out on keloid patients four times before surgery. Keloid tissue samples were collected and divided into an HBOT group (keloid with HBOT before surgery [HK] group, n = 6) and a non-HBOT group (K group, n = 6). Tumor gene expression was analyzed with an Oncomine Immune Response Research Assay kit. Data were mined with R package. The differentially expressed genes between the groups were compared. Hub genes between the groups were determined and verified with Quantitative Real-time PCR. Immune cell infiltration was analyzed based on CIBERSORT deconvolution algorithm analysis of gene expression and verified with immunohistochemistry (IHC).Results:Inflammatory cell infiltration was reduced in the HK group. There were 178 upregulated genes and 217 downregulated genes. Ten hub genes were identified, including Integrin Subunit Alpha M (ITGAM), interleukin (IL)-4, IL-6, IL-2, Protein Tyrosine Phosphatase Receptor Type C (PTPRC), CD86, transforming growth factor (TGF), CD80, CTLA4, and IL-10. CD80, ITGAM, IL-4, and PTPRC with significantly downregulated expression were identified. IL-10 and IL-2 were upregulated in the HK group but without a significant difference. Infiltration differences of CD8 lymphocyte T cells, CD4 lymphocyte T-activated memory cells, and dendritic resting cells were identified with gene CIBERSORT deconvolution algorithm analysis. Infiltration levels of CD4 lymphocyte T cell in the HK group were significantly higher than those of the K group in IHC verification.Conclusion:HBOT affected tumor gene expression and immune cell infiltration in keloids. CD4 lymphocyte T cell, especially activated memory CD4+T, might be the key regulatory immune cell, and its related gene expression needs further study.

Potential treatment of keloid pathogenesis with follistatin 288 by blocking the activin molecular pathway.

Keloids are benign tumours caused by abnormal wound healing driven by increased expression of cytokines, including activin A. This study compared effects of activins on normal and keloid-derived human dermal fibroblasts and investigated a novel treatment for keloids using follistatin. Normal skin and keloid tissue samples from 11 patients were used to develop primary fibroblast cultures, which were compared in terms of their histology and relevant gene (qRT-PCR and RNAseq) and protein (ELISA) expression. Activin A (INHBA) and connective tissue growth factor (CTGF) gene expression were significantly upregulated in keloid fibroblasts, as was activin A protein expression in cell lysates and culture medium. Activator protein 1 inhibitor (SR11302) significantly decreased INHBA and CTGF expression in keloid fibroblasts and a single treatment of follistatin over 5days significantly inhibited activin and various matrix-related genes in keloid fibroblasts when compared to controls. Follistatin, by binding activin A, suppressed CTGF expression suggesting a novel therapeutic role in managing keloids and perhaps other fibrotic diseases.

Gene Expression Profile of Isolated Dermal Vascular Endothelial Cells in Keloids.

Wound healing is a complex biological process, and imbalances of various substances in the wound environment may prolong healing and lead to excessive scarring. Keloid is abnormal proliferation of scar tissue beyond the original wound margins with excessive deposition of extracellular matrix (ECM) and chronic inflammation. Despite numerous previous research efforts, the pathogenesis of keloid remains unknown. Vascular endothelial cells (VECs) are a major type of inductive cell in inflammation and fibrosis. Despite several studies on vascular morphology in keloid formation, there has been no functional analysis of the role of VECs. In the present study, we isolated living VECs from keloid tissues and investigated gene expression patterns using microarray analysis. We obtained 5 keloid tissue samples and 6 normal skin samples from patients without keloid. Immediately after excision, tissue samples were gently minced and living cells were isolated. Magnetic-activated cell sorting of VECs was performed by negative selection of fibroblasts and CD45+ cells and by positive selection of CD31+cells. After RNA extraction, gene expression analysis was performed to compare VECs isolated from keloid tissue (KVECs) with VECs from normal skin (NVECs). After cell isolation, the percentage of CD31+ cells as measured by flow cytometry ranged from 81.8%–98.6%. Principal component analysis was used to identify distinct molecular phenotypes in KVECs versus NVECs and these were divided into two subgroups. In total, 15 genes were upregulated, and 3 genes were downregulated in KVECs compared with NVECs using the t-test (< 0.05). Quantitative RT-PCR and immunohistochemistry showed 16-fold and 11-fold overexpression of SERPINA3 and LAMC2, respectively. SERPINA3 encodes the serine protease inhibitor, α1-antichymotripsin. Laminin γ2-Chain (LAMC2) is a subunit of laminin-5 that induces retraction of vascular endothelial cells and enhances vascular permeability. This is the first report of VEC isolation and gene expression analysis in keloid tissue. Our data suggest that SERPINA3 and LAMC2 upregulation in KVECs may contribute to the development of fibrosis and prolonged inflammation in keloid. Further functional investigation of these genes will help clarify the mechanisms of abnormal scar tissue proliferation.

Expression of Cathepsins B, D, and G by the Embryonic Stem Cell-Like Population within Human Keloid Tissues and Keloid-Derived Primary Cell Lines.

The authors have previously shown that an embryonic stem cell-like population within keloid-associated lymphoid tissues in keloid lesions expresses components of the renin-angiotensin system that may be dysregulated. The authors hypothesized that cathepsins B, D, and G are present within the embryonic stem cell-like population in keloid lesions and contribute to bypass loops of the renin-angiotensin system. 3,3'-Diaminobenzidine immunohistochemical staining for cathepsins B, D, and G was performed on formalin-fixed paraffin-embedded sections in keloid tissue samples of 11 patients. Immunofluorescence immunohistochemical staining was performed on three of these keloid tissue samples, by co-staining with CD34, tryptase, and OCT4. Western blotting, reverse transcription quantitative polymerase chain reaction, and enzyme activity assays were performed on five keloid tissue samples and four keloid-derived primary cell lines to investigate protein and mRNA expression, and functional activity, respectively. 3,3'-Diaminobenzidine immunohistochemical staining demonstrated expression of cathepsins B, D, and G in all 15 keloid tissue samples. Immunofluorescence immunohistochemical staining showed localization of cathepsins B and D to the endothelium of microvessels within the keloid-associated lymphoid tissues and localization of cathepsin G to the tryptase-positive perivascular cells. Western blotting confirmed semiquantitative levels of cathepsins B and D in keloid tissue samples and keloid-derived primary cell lines. Reverse transcription quantitative polymerase chain reaction showed quantitative transcriptional activation of cathepsins B and D in keloid tissue samples and keloid-derived primary cell lines and cathepsin G in keloid tissue samples. Enzyme activity assays demonstrated functional activity of cathepsins B and D. Cathepsins B, D, and G are expressed by the embryonic stem cell-like population within the keloid-associated lymphoid tissues of keloid lesions and may act to bypass the renin-angiotensin system, suggesting a potential therapeutic target using renin-angiotensin system modulators and cathepsin inhibitors.

Expression of Components of the Renin-Angiotensin System by the Embryonic Stem Cell-Like Population within Keloid Lesions.

We investigated expression of prorenin receptor, angiotensin-converting enzyme, angiotensin II receptor 1, and angiotensin II receptor 2 by the embryonic stem cell-like population on the endothelium of the microvessels and perivascular cells within keloid-associated lymphoid tissues. Immunohistochemical staining for prorenin receptor, angiotensin-converting enzyme, angiotensin II receptor 1, and angiotensin II receptor 2 was performed on 11 formalin-fixed, paraffin-embedded sections of keloid tissue samples. Immunofluorescence staining was performed on three keloid tissue samples by co-staining with OCT4, CD34, ERG, and tryptase. Real-time quantitative polymerase chain reaction was performed on five keloid tissue samples and four keloid-derived primary cell lines. Western blotting was performed on the four keloid-derived primary cell lines for mRNA and protein expression of these proteins, respectively. Immunohistochemical and immunofluorescence staining showed expression of prorenin receptor, angiotensin-converting enzyme, angiotensin II receptor 1, and angiotensin II receptor 2 in all 11 keloid tissue samples. Prorenin receptor and angiotensin II receptor 1 were expressed on the endothelium and the pericyte layer of the microvessels and perivascular cells, angiotensin II receptor 2 was localized to the endothelium of the microvessels and the tryptase-positive perivascular cells, and angiotensin-converting enzyme was localized to the endothelium of the microvessel, within the keloid-associated lymphoid tissues. Real-time quantitative polymerase chain reaction showed transcripts of prorenin receptor, angiotensin-converting enzyme, and angiotensin II receptor 1 in the keloid tissue samples and keloid-derived primary cell lines, whereas angiotensin II receptor 2 was detected in keloid tissue samples only. Western blotting confirmed the presence of prorenin receptor, angiotensin-converting enzyme, and angiotensin II receptor 1 in the keloid-derived primary cell lines. Prorenin receptor, angiotensin-converting enzyme, angiotensin II receptor 1, and angiotensin II receptor 2 were expressed by the embryonic stem cell-like population within the keloid-associated lymphoid tissues, suggesting that this primitive population may be a potential therapeutic target by modulation of the renin-angiotensin system.

Identification and integrated analysis of microRNA expression profiles in keloid.

Keloid is a common abnormal cutaneous fibroproliferative disorder. However, the process underlying keloid pathogenesis still remains to be unclear. To integrated analyse the miRNA expression profiles of keloid. We performed miRNA expression profiles analysis of 3 paired keloid and normal tissue samples by miRNA microarray. Differentially expressed miRNAs were further performed integrative analysed and validated using quantitative reverse transcription polymerase chain reaction (qRT-PCR). After predicting target genes, we constructed the miRNA-target genes interaction network and carried out bioinformatics analysis. The results revealed that 264 miRNAs were significantly altered. The expression of high frequency miRNAs which included miRNA-199a-5p, miRNA-21-5p, miRNA-214-5p, miRNA-424-5p, and miRNA-205-5p was further evaluated. The gene ontology (GO) analyses and the top enriched Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways showed these target genes were associated with MAPK signaling pathway and HIF-1 signaling pathway. This study revealed the profiling of miRNAs in keloid that are potentially implicated in the development of this disease and could serve as novel diagnostic and therapeutic target of keloid.

The Superficial Dermis May Initiate Keloid Formation: Histological Analysis of the Keloid Dermis at Different Depths

Several studies have reported on certain aspects of the characteristics of different sites within a keloid lesion, but detailed studies on the keloid dermis at different depths within a keloid lesion are scarce. The aim of this study was to investigate the histology of the keloid dermis at different depths. This study included 19 keloid tissue samples that were collected from 19 patients and 19 normal skin samples, which were harvested from subjects without keloids or hypertrophic scar. Samples were studied by light microscopy using routine hematoxylin and eosin histochemical staining, and immunohistochemistry to detect CD20-positive B-lymphocytes and CD3-positive T-lymphocytes. Sirius Red histochemical staining was used to determine the type of collagen in keloid tissue and normal skin samples. The migratory properties of fibroblasts within the keloid dermis at different depths was compared, using an in vitro migration assay. The findings of this study showed that although the papillary and reticular dermis could be clearly distinguished in normal skin, three tissue layers were identified in the keloid dermis. The superficial dermis of keloid was characterized by active fibroblasts and lymphocytes; the middle dermis contained dense extracellular matrix (ECM) with large numbers fibroblasts, and the deep dermis was poorly cellular and characterized by hyalinized collagen bundles. In the keloid samples, from the superficial to the deep dermis, type I collagen increased and type III collagen decreased, and fibroblasts from the superficial dermis of the keloid were found to migrate more rapidly. In conclusion, the findings of this study showed that different depths within the keloid dermis displayed different biological features. The superficial dermis may initiate keloid formation, in which layer intralesional injection of pharmaceuticals and other treatments should be performed for keloid.

Downregulation of β-catenin blocks fibrosis via Wnt2 signaling in human keloid fibroblasts.

Keloid is a disorder of fibroproliferative diseases that occurs in wounds, characterized by an exaggerated response to injury. The key factor responsible for the disease process has not been identified. This study sought to elucidate the role of β-catenin in the regulation of keloid phenotypes and signaling. Expression of β-catenin in keloid and normal non-keloid samples was measured by real-time polymerase chain reaction. Knockdown of β-catenin was achieved by delivering small interfering RNA to target β-catenin. Cell proliferation, cell cycle progression, and apoptosis of keloid cells were measured by functional assays in vitro. The proteins related to keloid fibrosis were measured by Western blotting. β-catenin expression was significantly upregulated in keloid tissue samples compared with the normal non-keloid age-adjusted skin sample counterparts. Functionally, targeting β-catenin with lipofection-delivered small interfering RNA oligonucleotide inhibited the proliferation and cell cycle arrest in G0/G1 phase and increased apoptosis of fibroblast cells, accompanied by downregulation of Wnt2 and cyclin D1 as well as the phosphorylation level of glycogen synthase kinase 3 beta in the keloid fibrosis. Our study supports a crucial role of β-catenin in the regulation of fibroproliferation and extracellular matrix deposition. Targeting β-catenin using small interfering RNA oligonucleotide may be a promising approach for preventing excessive fibroproliferative development after wound healing and may lead to the development of novel strategies for restoring keloid diseases.

MiR-21 promotes collagen production in keloid via Smad7

ObjectiveTo explore the biological function of miR-21 in the formation of keloid. MethodsNormal skin and keloid tissue samples underwent histopathologic study and qPCR analysis. The expression of miR-21 and mRNA expression of Smad7, Col1A1, Col3A1 in fibroblasts derived from keloid tissue and normal skin tissue samples were detected by qPCR. Normal and keloid fibroblasts were transfected with miR-21 mimics or inhibitor respectively, and expression of Smad7, Col1A1 and Col3A1 were examined. After the normal fibroblasts were transfected with Smad7 siRNA, expression of Col1A1 and Col3A1 were detected by Western blot and qPCR analysis. ResultsCollagen was obviously thick and disorganized in keloid tissue. The expression of miR-21, Col1A1 and Col3A1 in keloid tissue and keloid-derived fibroblasts were higher than that of normal counterparts, while the expression of Smad7 in keloid tissue and keloid-derived fibroblasts was lower. miR-21 mimics attenuated expression of Smad7, and enhanced the expression of Col1A1, Col3A1. Furthermore, the Smad7 siRNA increased expression of Col1A1and Col3A1. ConclusionsmiR-21 promoted collagen production in keloid by negatively regulating the expression of the Smad7.

RUNX3 expression is associated with sensitivity to pheophorbide a-based photodynamic therapy in keloids.

Runt-related transcription factor 3 (RUNX3) has recently been reported to be a possible predictor of sensitivity of cancer cells for photodynamic therapy (PDT), a promising therapeutic modality for keloids. In this study, we aimed to elucidate the implications of RUNX3 for keloid pathogenesis and sensitivity to pheophorbide a-based PDT (Pa-PDT). RUNX3 and proliferating cell nuclear antigen (PCNA) expression were examined in 6 normal skin samples and 32 keloid tissue samples by immunohistochemistry. We found that RUNX3 expression was detected more often in keloid tissues than in dermis of normal skin. In keloid tissues, RUNX3 expression was significantly increased in patients presenting with symptoms of pain or pruritus, and was also significantly related to PCNA expression. The therapeutic effect of Pa-PDT was comparatively investigated in keloid fibroblasts (KFs) with and without RUNX3 expression. Significant differences were found after Pa-PDT between KFs with and without RUNX3 expression in cell viability, proliferative ability, type I collagen expression, generation of reactive oxygen species (ROS), and apoptotic cell death. In addition, RUNX3 expression was significantly decreased after Pa-PDT in KFs, and KFs with downregulation of RUNX3 showed significantly increased cell viability after Pa-PDT. Pa-PDT may be a potential therapeutic modality for keloids, and RUNX3, as a possible contributor to keloid pathogenesis, may improve sensitivity to Pa-PDT in KFs.

Insufficient expression of the melanocortin-1 receptor by human dermal fibroblasts contributes to excess collagen synthesis in keloid scars

Activation of the α-melanocyte-stimulating hormone (αMSH)/melanocortin-1 receptor (MC1R) signalling pathway exerts antagonistic actions on cutaneous inflammatory and fibrogenic responses in addition to promoting pigment production. Herein, the expression of MC1R by keloid-derived fibroblasts and keloid scar tissue was investigated using a range of techniques. MC1R mRNA expression levels in five different keloid fibroblast cell lines were significantly reduced to less than half compared with five normal fibroblast cell lines (P<0.05). Immunohistological analysis of tissue samples indicated that MCR1 immunoreactivity in both epidermal and dermal compartments of five keloid tissue samples was dramatically decreased compared with normal skin (P<0.05). Insufficient expression of MC1R on human dermal fibroblasts might abolish the αMSH-mediated suppression of collagen production and myofibroblast transformation elicited by the profibrotic cytokine-transforming growth factor-β1. Restoration of reduced MC1R by dermal fibroblasts may lead to novel scar-reducing therapeutic approaches for treating this refractory fibrotic disease.

Effects of the Cyclin-Dependent Kinase 10 (CDK10) on the Tamoxifen Sensitivity of Keloid Samples

Cyclin-dependent kinase 10 (CDK10) is a cell cycle regulating protein kinase, which has just been discriminated in recent years. In this paper, mRNA and protein expression of CDK10 were first investigated by a comparative study between 23 human keloid tissue samples and their adjacent normal skin. To further address its potential as a therapeutic target in the treatment of keloid, a plasmid expressing the CDK10 gene was transfected into keloid fibroblast. The effects on tamoxifen-induced apoptosis were then investigated using Western blot assay and flow cytometry. Results showed that there is a generally down-regulated expression of CDK10 in keloid compared to normal skin samples. Transfection with the recombinant CDK10 plasmid significantly decreased the viability of cells and increased the apoptosis rates. Tamoxifen sensitivity in keloid fibroblasts was observed after treatment with the recombinant CDK10 plasmid. The results suggested that CDK10 may play an important role in enhancement of tamoxifen efficiency, and its expression may have a synergistic effect on keloid treatments.

Promoted activation of matrix metalloproteinase (MMP)‐2 in keloid fibroblasts and increased expression of MMP‐2 in collagen bundle regions: implications for mechanisms of keloid progression

Keloid is characterized by excessive deposition of collagen, resulting from aberrant extracellular matrix (ECM) production and degradation. The aim was to investigate the role of matrix metalloproteinases (MMPs) and tissue inhibitor of metalloproteinases (TIMPs) in pathological wound healing in keloids. Semiquantitative analysis of 60 keloid tissue samples and 25 mature scar tissue samples demonstrated significantly increased expression of MMP-2, TIMP-2 and TIMP-3 in keloids compared with mature scars. Within keloid regions, MMP-2 expression was significantly higher in collagen bundle regions than in non-collagen bundle regions. Double immunofluorescence revealed that keloid fibroblasts between collagen bundles exhibited MMP-2, TIMP-2 and membrane-type 1 MMP (MT1-MMP) co-expression, whereas only MMP-2 expression was evident on the edge of collagen bundles. Western blot analysis and gelatin zymography of 13 keloid-derived fibroblasts (KFbs) and six normal skin dermal-derived fibroblasts (NFbs) demonstrated that unstimulated KFbs exhibited significantly increased MMP-2 activity and expression compared with NFbs under the same conditions. These results together indicate that MMP-2 activity can be promoted in keloid fibroblasts between collagen bundles in cooperation with TIMP-2 and MT1-MMP. This could contribute to remodelling of collagen bundle regions and invasion of fibroblasts into peripheral normal regions through promoted degradation of ECM.

The Expression of Human HtrA1 in Keloid Tissue

Aim: To investigate the expression of human HtrA1 in keloid lesions, and to clarify a possible role of human HtrA1 in keloid pathogenesis.Methods: Total RNA was isolated from six keloids and two normal skins by single‐step method. The expression level of human HtrA1 was examined by using Northern blot analysis. Keloid and normal skin tissue samples were fixed in paraformaldehyde, and paraffin sections were obtained. Immunohistochemical analysis was performed with anti‐human HtrA1 polyclonal antibody.Results: The mRNA level of human HtrA1 was markedly elevated in keloid samples, compared with normal skin. Using immunohistochemical analysis, fibroblast‐like cells abundantly found in the margin of keloid lesions, were stained with anti‐human HtrA1 antibody. No human HtrA1 staining of fibroblasts in normal skin was observed. Interestingly, no significant staining was detected in hypertrophyic scar lesions, which is a similar dermal disease to keloid.Conclusion: Human HtrA1 expression was found to be up‐regulated in keloid lesions, especially in their margin, compared to normal skins and hypertrophic scars. Our data suggest that human HtrA1 could play a critical role in an expression of keloid specific phenotype and in the development of keloid lesions.