Keloid Group Research Articles

Association of Human Leukocyte Antigens (HLA) with Keloids and Hypertrophic Scar in Thais

Background: Keloids and hypertrophic scars are abnormal fibro-proliferative lesions. Associations between genes, the human leukocyte antigen (HLA) system in particular, and keloids have been studied in various ethnic groups but not in Thais. Objective: To investigate the association of HLA alleles with keloids and hypertrophic scars in Thais. Materials and Methods: The present study employed a retrospective case-control design. Scar assessment was performed on 139 kidney donors who underwent nephrectomy at Ramathibodi Hospital between January 2008 and December 2015. The wound scars after nephrectomy were evaluated and graded by a plastic surgeon using the modified Vancouver Scar Scale. Kidney donors who were unable to communicate well or who had autoimmune diseases or complications from surgery were excluded from the study. The diagnosis of a keloid scar, hypertrophic scar, and flat scar was made by clinical criteria. The donors were categorized into groups with three scar types, flat as the control group, hypertrophic, and keloid. The associations between the frequencies of HLA antigen with hypertrophic scar and keloids were measured with an odds ratio using logistic regression analysis. Results: Of the 139 living kidney donors, 15 (10.8%) had keloids, 46 (33.1%) had hypertrophic scars, and 78 (56.1%) had flat scars. Sixty-one HLA-A, -B, -DRB1, and -DQB1 alleles were evaluated in the present study. Compared with controls, the allele frequency of HLA-DRB1*15 was significantly higher in the keloid group at 43.33% versus 24.36% (odds ratio 2.37, 95% confidence interval 1.06 to 5.33, p=0.036). No significant association between HLA alleles and hypertrophic scars was found. Conclusion: The present study demonstrated the positive association of HLA-DRB1*15 with keloids in Thai individuals. The HLA-DRB1*15 could be a susceptibility factor for the development of keloids. Keywords: Human leukocyte antigen; Keloids; Thais, HLA-DRB1; Positive association

Integration of single-cell and bulk transcriptomics reveals immune-related signatures in keloid.

Keloid is a pathological dermatological condition that manifests as an overgrowth scar secondary to skin trauma. This study endeavored to excavate immune-related signatures of keloid based on single-cell RNA (scRNA) sequencing data and bulk RNA sequencing data. The keloid-relevant scRNA sequencing dataset GSE163973 and bulk RNA sequencing dataset GSE113619 were mined from the GEO database. The "Seurat" R package was utilized for data quality control, cell clustering, and investigation of marker genes of each cell cluster. The "SingleR" package helped match the marker genes of the corresponding cluster to specific cell types. Moreover, the R package "Monocle" was deployed for pseudotemporal ordering analysis, and the "clusterProfiler" was applied for functional and pathway enrichment analysis. The immune-related signatures were then identified, and potential targeted drugs were predicted via the DGIdb database. Verification of the immune-related signatures in clinical validation samples was implemented by RT-qPCR. Totally 23 cell clusters were screened and classified into 10 cell types based on the scRNA sequencing data. The keloid group had a significantly higher endothelial cell proportion than the control group. As enrichment analysis was applied in both differentially expressed genes (DEGs) of scRNA and bulk RNA sequencing data, we found they were enriched in multiple common immune-related pathways and biological processes. Meanwhile, we acquired three immune-related signatures (VCAM1, CALCRL, and HLA-DPB1) by intersecting the above DEGs with immune-related genes (IRGs). Then, we predicted 16 drugs potentially targeting the biomarkers through the DGIdb database. Finally, the outcome of RT-qPCR of clinical validation samples further verified the results. In conclusion, we analyzed the cell types and functional differences in the keloid through scRNA and bulk RNA sequencing data. We identified three immune-related signatures (VCAM1, CALCRL, and HLA-DPB1) in keloid, providing a basis for further in-depth investigation of the molecular mechanisms of keloid and exploration of therapeutic targets.

Cyclical Stretching Induces Excess Intracellular Ca2+ Influx in Human Keloid-Derived Fibroblasts In Vitro.

The incidence of keloids is higher in the case of darker skin. It is more common in the parts exposed to stretching (thorax, abdomen, and joints). Cyclical stretching reportedly induced each Ca2+ spike through differential mechanosensitive channels in human synovial and dermal fibroblasts. Therefore, the authors hypothesized that cyclical stretching also induces a specific Ca2+ spike in keloid-derived fibroblasts. This in vitro study compared the intracellular calcium dynamics induced by cyclical stretching between control (human dermal fibroblasts) and keloid (human keloid-derived fibroblasts) groups. Each group was exposed to two-dimensional stretch using an originally developed stretch microdevice. Intracellular Ca2+ was observed for 5 minutes, including 30 seconds of baseline, under a fluorescent confocal laser microscope. The intracellular Ca2+ concentration was evaluated every 0.5 second using the fluorescence intensity ratio. A positive cellular response was defined as a rise of the ratio by greater than or equal to 20%. The normal response cutoff value was determined by receiver operating characteristic analysis. The keloid groups were significantly more responsive than the control groups (15.7% versus 8.2%; P = 0.029). In the cellular response-positive cells, the keloid groups reached significantly higher intracellular Ca2+ concentration peaks than the control groups (2.20 versus 1.26; P = 0.0022). The cutoff value was 1.77, and 10.4% of the keloid-derived fibroblasts exhibited a hyper-Ca2+ spike above the normal range. Keloid-derived fibroblasts with a hyper-Ca2+ spike might constitute a keloid-specific subpopulation. Hereafter, the authors will study whether the normalization of excessive intracellular Ca2+ concentration leads to keloid treatment in vivo. This study result provided a clue to the onset mechanism of keloids, which the authors hope will lead to the development of new therapy in the future.

A Study on the Expression of Messenger RNAs and Long Noncoding RNA in Keloid Fibroblasts Based on Gene Expression Omnibus Microarray Data Mining.

The purpose of this study was to find the coding RNA [messenger RNA (mRNA)] and long noncoding RNA (lncRNA) expressed in keloid through the analysis of Gene Expression Omnibus microarray chip of keloid fibroblasts. Gene Expression Omnibus database GSE7890 database was downloaded with selection of keloids and normal scar group data. The data were analyzed by R language combined with online database. The log2FC>1, P value <0.01 was chosen as screening criteria, and the differentially expressed mRNAs were screened for GO and KEGG function analysis. One hundred fifty-five mRNA expression in the keloid group was significantly different from that in the normal group, including 31 groups with upregulated mRNA expression and 124 groups with down-regulated mRNA expression. Meanwhile, 8 lncRNAs were changed in the keloid group, including 3 upregulated (Rp11-420a23.1, Rp11-522b15.3, and Rp11-706j10.1) and 5 down-regulated (LINC00511, LINC00327, Hoxb-as3, Rp11-385n17.1, and Rp3-428l16.2). Quantitative polymerase chain reaction analysis of DElncRNAs in keloid fibroblasts showed that the expression of all DElncRNAs except for RP11-385N17.1 was increased in the keloid group compared with the control group. Moreover, the differences in LINC00511 and RP11-706J10.1 were statistically significant. The noncoding RNA information of Gene Expression Omnibus chip data can be deeply mined through bioinformatics, and the potential epigenomic mechanism affecting keloid formation can be found from the existing database.

Identification and validation of HOXD3 and UNC5C as molecular signatures in keloid based on weighted gene co-expression network analysis

BackgroundKeloid is a benign proliferative disease characterized by excessive deposition of extracellular matrix collagen during skin wound healing. The mechanisms of keloid formation have not been fully elucidated, and the current treatment methods are not effective for all keloid patients. Therefore, there is an urgent need to find more effective therapies, and our research focused on identifying characteristic molecular signatures of keloid to explore potential therapeutic targets. MethodsGene expression profiles of keloid and control group samples were retrieved from the GEO database. Taking the GSE113619 dataset as the training set, the dataset collected skin tissues from non-lesion sites of healthy and keloid-prone individuals, denoted as Day0. The second sampling was performed 42 days later at the original sampling site of control and keloid groups, denoted as Day42.The 'limma' package and Venn diagram identified differentially expressed genes (DEGs) specific to keloid day42 versus day0 samples. Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), Reactome pathway functional enrichment, and annotation of the characteristic genes were conducted on the Metascape website. Ingenuity canonical pathways, disease & function enrichment analysis and gene interaction network were performed and predicted in Ingenuity Pathway Analysis (IPA) software. Key module genes related to keloid were filtered out by Weighted Gene Co-expression Network Analysis (WGCNA). We utilized the Least Absolute Shrinkage and Selection Operator (LASSO) algorithm to screen the characteristic genes in keloid by the ‘glmnet’ package. The area under the curve (AUC) of receiver operating characteristic (ROC) was utilized to determine the effectiveness of potential signatures in discriminating keloid samples from normal samples and performed by using the ‘pROC’ package. The enrich scores of 24 immune cells in each sample were calculated by the single-sample gene set enrichment analysis (ssGSEA) algorithm， and then the Gene Set Variation Analysis (GSVA) was performed. Finally, RNA from 4 normal and 6 keloid samples was extracted, and RT-qPCR and Western Blot validated the expression of characteristic genes. ResultsA total of 640 DEGs specific to keloid day42 versus day0 samples were detected. 69 key module genes were uncovered and implicated in ‘NCAM signaling for neurite out-growth’, ‘oncogenic MAPK signaling’, ‘transmission across chemical synapses’ pathways, and the mitotic cell cycle-related processes. Five characteristic genes (MTUS1, UNC5C, CEP57, NAA35, and HOXD3) of keloid were identified by LASSO, and among which UNC5C and HOXD3 were validated by ROC plot in external dataset, RT-qPCR and Western Blot in validation samples. The result of ssGSEA indicated that the infiltration of neutrophils showed a relatively higher abundance and natural killer cells with relatively low enrichment in the keloid group compared to the control group. UNC5C was correlated with more immune cells compared with other characteristic genes. ConclusionIn this study, characteristic genes associated with keloid were identified by bioinformatic approaches and verified in clinical validation samples, providing potential targets for the diagnosis and treatment of keloid.

Predictive Factors of Keloid Formation in Congenital Foot Syndactyly.

Background:Keloid formation after syndactyly division is a stressful situation for patients. In our experience, digital enlargement may be involved in keloid formation following syndactyly divisions. Therefore, we aimed to identify predictive factors and reference values for keloid formation.Methods:In this retrospective study, 11 keloid patients (seven children, four adults) and 11 nonkeloid patients after syndactyly division (control group) with the same sex, age, webspace division site, and operation were enrolled between 2008 and 2020. Using preoperative x-ray images, we compared bony width, length, area, and protruding index relative to the great toe between keloid and control groups. Additionally, reference values for keloid formation were obtained using receiver operating characteristic curves. Statistical analysis was performed using Spearman’s correlation test.Results:When compared with the same digit in the normal foot, distal phalanx (P3) bony base width, area, and protruding index on keloid foot were significantly different between keloid group and control group. The reference values for keloid formation after syndactyly release were 1.34 for the P3 area ratio and 1.61 for the P3 triangular area ratio (using the horizontal length of the P3 base and P3 vertical length). The reliability of reference values for the P3 area ratio and P3 triangular area ratio was excellent for all patients.Conclusions:If digital enlargement in distal phalanx is present when compared with adjacent toe in patients who had undergone primary foot syndactyly divisions, risk of keloid development should be communicated preoperatively, and preventive strategies for keloid development and close observations are required.

A comparison expression analysis of CXCR4, CXCL9 and Caspase-9 in dermal vascular endothelial cells between keloids and normal skin on chemotaxis and apoptosis

This present study was designed to explore key biological characteristics and biomarkers associated with dermal vascular endothelial cells of keloids. GSE121618 dataset was downloaded in the Gene Expression Omnibus (GEO) Database, including the KECs group and NVECs group. Through GEO2R, we have screened the differentially expressed genes (DEGs) and performed gene ontology (GO), Gene Set Enrichment Analysis (GSEA), and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis. Then, we constructed a protein–protein interaction (PPI) network and analyzed hub genes via the Search Tool for the Retrieval of Interacting Genes (STRING) Online Database and Cytoscape software. Furthermore, experiments were performed to validate the expression of selected genes, including H&E staining, immunohistochemical staining, Western blot, and RT-qPCR. A total of 1040 DEGs were selected with GEO2R online tools. Most of the enriched pathways and processes focus on cell migration, tube development, chemotaxis, cell motility, and regulation of apoptosis. With the assistance of STRING and Cytoscape, hub genes were selected. In our validation experiments of RT-qPCR, the mRNA expression of selected genes has significant differences between different groups in tissue and cell experiments. As was shown in immunohistochemical staining, the proteins of CXCR4, CXCL9, and Caspase-9 had higher expression levels in tissue samples of the Keloid group than the Normal skin group. Western blot and RT-qPCR in dermal vascular endothelial cell experiments were consistent with the aforementioned results. This study has provided a deeper analysis of the pathogenesis of dermal vascular endothelial cells in keloids. Genes of CXCR4, CXCL9, and Caspase-9 may influence the processes of inflammatory responses and vascular endothelial cell apoptosis to exert crucial effects in the development of keloids. Abbreviations: GEO: gene expression omnibus; DEGs: differentially expressed genes; KVECs: keloid vascular endothelial cells; NVECs: normal skin vascular endothelial cells; GO: gene ontology; KEGG: Kyoto encyclopedia of genes and genomes; PPI: protein protein interaction; BP: biological process; CC: cellular component; MF: molecular function; GSEA: gene set enrichment analysis; STRING: search tool for the retrieval of interacting genes; MCODE: molecular complex detection

Blood perfusion in hypertrophic scars and keloids studied by laser speckle contrast imaging.

This study used laser speckle contrast imaging (LSCI) to evaluate the difference in blood perfusion between hypertrophic scars and keloids. A total of 30 keloids, 21 early hypertrophic scars, 20 proliferative hypertrophic scars, 20 regressive hypertrophic scars, and 20 mature hypertrophic scars were enrolled into this study. Vancouver Scar Scale (VSS) was assessed by a plastic surgeon. LSCI was used to evaluate perfusion of the whole (W), marginal (M), central (C) regions, and surrounding normal skin of the scars, and ratios (M/N, C/N) were calculated. The perfusion of the marginal region in the keloid was significantly higher than that of the central region. Nevertheless, there was no significant difference in perfusion between the central and marginal regions in the early, proliferative, regressive, and mature hypertrophic scars. The degree of perfusion and perfusion ratio in the marginal region of keloid was similar to that of proliferative hypertrophic scars, and the degree of perfusion and perfusion ratio in central region of keloid group was similar to that of early and regressive hypertrophic scars. The difference in perfusion distribution in keloids and hypertrophic scars may provide ideas for their identification. LSCI may be a useful method for differentiating between keloids and hypertrophic scars.

Association of Leptin Receptor Gene Polymorphisms with Keloids in the Chinese Han Population.

BackgroundThe association between leptin receptor (LEPR) polymorphisms and keloids is still unclear. Our study aimed to explore the association between LEPR gene polymorphisms and keloids in the Chinese Han population.Material/MethodsWe implemented a case-control study in a cohort of 352 keloid patients and 299 healthy controls to analyze the correlation between 4 SNPs (rs1137101, rs1938496, rs6588147, and rs7555955) and keloids. Genomic DNA was extracted from peripheral blood by using TGuide M16 (Tiangen). Genotyping of LEPR SNPs was performed using an improved multiple ligase detection reaction (iMLDR) by Shanghai Genesky Bio-Tech Co., Ltd.ResultsWe found that patients caring the AA genotype of rs1137101 and the CC genotype rs1938496 tend to have the increased risk of keloids (P=0.026, P=0.047). Carrying the GA, AA gene type, and G allele frequencies of rs7555955, patients were more likely to have to keloids (P=0.030, P=0.016, P=0.018, respectively). There were no significant differences in genotype distribution and allele frequencies of rs6588147 between cases and controls. The association of rs1137101 and rs7555955 under dominant, recessive, and allele models exhibited significant differences among family-history keloid patients, no-family-history keloid groups, and normal controls (χ2=6.471, P=0.039; χ2=6.477, P=0.039; χ2=6.197, P=0.045, respectively). Similarly, the OR of rs1137101 in the recessive model was significantly higher in patients with a family history of keloids than those in controls. Nonetheless, there are significant ORs of rs1938496 and rs6588147 among the mild-moderate keloid, severe keloid, and control groups.ConclusionsThe LEPR gene polymorphisms are associated with keloid formation and severity, especially in patients with a positive family history.

Heterogeneous Features of Keloids Assessed by Laser Speckle Contrast Imaging: A Cross-Sectional Study.

Keloids are described as benign dermal fibroproliferative lesions, and vascularization may play a significant role in their pathogenesis. In this study, laser speckle contrast imaging (LSCI) was used to assess perfusion within keloids and surrounding skin, and perfusion of keloids at different stages was compared. A total of 59 patients with 110 untreated keloids on the anterior chest were enrolled in this study. Different keloid stages (progressive, stable, and regressive) were defined according to patients' descriptions of whether keloids became larger, stable, or smaller during the previous year. Vancouver Scar Scale (VSS) was assessed by a plastic surgeon, and patient reports on pain and itching were documented. LSCI was used to evaluate blood perfusion of keloids (K), skin adjacent to keloids (A), and nonadjacent skin (N). The mean perfusion of these regions was determined, and ratios (K/N, A/N) were calculated. A heterogeneous perfusion map was observed among the keloid groups, as well as within each keloid. A positive correlation was found between keloid perfusion and VSS. There were 62 (56.4%) keloids in the progressive stage, 33 (30.0%) keloids in the stable stage, and 15 (13.6%) keloids in the regressive stage. The mean K/N ratios in the progressive, stable, and regressive stages were 2.3 ± 0.5, 1.8 ± 0.3, and 1.5 ± 0.5, respectively. The mean A/N ratios were 1.2 ± 0.4, 1.2 ± 0.2, and 1.0 ± 0.5, respectively. Within each keloid, significantly higher perfusion was noted in the keloid and adjacent skin compared with nonadjacent skin. These results indicate that LSCI is a promising technique for evaluating keloid blood perfusion and distinguishing heterogeneous keloids. Lasers Surg. Med. © 2020 Wiley Periodicals LLC.

53 Regulation of Glycolysis and the Warburg Effect in Keloids

Abstract Introduction Hypertrophic and keloid scarring are considered as major determinants for long-term outcomes and quality of life for burn survivors. Keloid development is predicated on prolonged local inflammation and altered glucose metabolism. Owing to its tumor-like dependence on glucose, we hypothesized that keloids would display the bioenergetics of cancer cells; namely, increased glucose uptake via Glut1 and upregulation of key glycolytic enzymes. Furthermore, burn patients who develop keloids potentially demonstrate early evidence of the aforementioned features compared to non-keloid patients. Therefore, elevated Glut1 expression could serve as a marker for keloid development in burn patients. Methods We enrolled 27 control burn patients with 39% ± 4% total body surface area (TBSA) burns. The keloid burn group included 9 burn patients with 47% ± 9% TBSA burns. Skin was obtained for histology, gene and protein expression at 0–17 days post-burn. Results Keloids have higher Glut1 expression compared to normal and burn skin (7.72 vs. 0.15, p&amp;lt; 0.001; 7.72 vs. 2.35, p&amp;lt; 0.05). Keloids also exhibit enhanced expression of critical glycolytic enzymes compared to burn skin at 7–10 days post-burn (HK2: 4.14 vs. 2.36, p&amp;lt; 0.001; PFK1: 6.51 vs. 3.83, p&amp;lt; 0.001; PFK2: 5.35 vs. 1.27, p&amp;lt; 0.001; PDK1: 5.50 vs. 4.31, p&amp;lt; 0.05; PKM2: 7.58 vs. 2.98, p&amp;lt; 0.001). A Glut1 time-course analysis in burn skin from non-keloid patients indicated a significant elevation at 7–10 days post-burn compared to normal skin (3.22 vs. 0.20, p&amp;lt; 0.01). Skin from keloid burn patients prior to development of keloids demonstrate higher Glut1 expression compared to skin from non-keloid controls when matched by days post-burn (40.5 vs. 0.58 at 0–2 days, p&amp;lt; 0.05). Conclusions Patients who develop post-burn keloids exhibit early risk factors prior to the development of keloids (e.g. elevated skin Glut1). Keloids have an augmented reliance on glycolysis compared to burn skin. Therefore, early identification and targeting glycolysis in susceptible patients is key. Applicability of Research to Practice Upregulation of glycolytic enzymes and transporters such as Glut1 may serve as keloid predictive markers. Identification of at-risk patients allows for a tailored treatment regimen that targets dysregulated glycolysis in these patients. Pharmaceutical agents like shikonin suppress multiple glycolytic steps, serving as an effective means to interfere with the proliferative capacity of keloids. Potentially, local shikonin administration could serve as a therapy in select patients exhibiting keloid risk factors.

Gene Expression of Neurotrophins and Their Receptors in Keloids

The aim of this study was to assess gene expression of neurotrophins and their receptors in keloids. Skin samples of normal skin and keloids were obtained from patients in the control (n = 12) and keloid (n = 12) groups, respectively. Ribonucleic acid was extracted from the skin specimens, purified, evaluated by spectrophotometry, and used to synthesize complementary DNA. Real-time quantitative polymerase chain reaction analysis of 84 human neurotrophin genes and their receptors was performed. Twelve genes, including heat shock 27-kDa protein 1, gastrin-releasing peptide receptor, corticotropin-releasing hormone receptor 2, neuropeptide Y Y2 receptor, interleukin 6 signal transducer, nerve growth factor, metallothionein 3, B-cell chronic lymphocytic leukemia/lymphoma 2, cholecystokinin A receptor, persephin, galanin receptor 2, and fibroblast growth factor receptor 3, were down-regulated in keloid tissue compared with normal skin. The genes 27-kDa heat shock protein 1, gastrin-releasing peptide receptor, corticotropin-releasing hormone receptor 2, nerve growth factor, metallothionein 3, B-cell chronic lymphocytic leukemia/lymphoma 2, and persephin protein were considered priority genes associated with keloid formation.

Expression and clinical significance of HIF-1, VEGF and MMP-2 in patients with pathological scar

Objective To investigate the expression levels and significance of hypoxia inducible factor-1α (HIF-1α), vascular endothelial growth factor (VEGF) and matrix metalloproteinase-2 (MMP-2) in pathological scar. Methods 73 patients with pathological scar from March 2015 to February 2017 in our hospital were selected, including 42 cases in hypertrophic scar group and 31 cases in keloid group. 20 cases of non pathological scar patients and 20 cases of normal plastic surgery were selected as control group. mRNA and protein expression levels of HIF-1, VEGF and MMP-2 in skin tissue of each group were detected by real-time fluorescence quantitative and Western blot, and the clinical significance was analyzed. Results Compared with non pathological scar tissue and normal skin tissue, the mRNA and protein expression levels of HIF-1α, VEGF and MMP-2 in pathological scar tissue were significantly increased, and the differences were statistically significant (P 0.05); the mRNA and protein expression levels of MMP-2 in keloid group were significantly lower than those in hypertrophic scar group (P<0.05). Pearson correlation analysis showed that there was a significant positive correlation between HIF-1α and VEGF, MMP-2 in pathological scar tissues (r=0.623, 0.507, P<0.05). Conclusions The expressions of HIF-1α, VEGF and MMP-2 in pathological scar tissue is obviously increased, which is closely related to the formation of pathological scar. Key words: Cicatrix/PA; Hypoxia-inducible factor 1, alpha subunit/ME; Vascular endothelial growth factors/ME; Matrix metalloproteinase 2/ME

Intralesional cryotherapy versus excision with corticosteroid injections or brachytherapy for keloid treatment: Randomised controlled trials

Keloids are a burden for patients due to physical, aesthetic and social consequences. Treatment remains a challenge due to therapy resistance and high recurrence rates. The main goals of treatment are to improve scar appearance and symptoms and patients' quality of life (QoL). Two multicentre, randomised controlled open trials that compared 1) intralesional cryotherapy with excision and corticosteroid injections for primary keloids, and 2) intralesional cryotherapy with excision and brachytherapy for therapy resistant keloids. Primary outcome was scar appearance assessed with the Patient and Observer Scar Assessment Scale. Secondary outcomes were patient reported QoL (Skindex-29, SF-36, EQ-5D-5L), recurrence rates and scar volume reduction. For analysis, a linear mixed model was used. Power analysis indicated 33 patients in each group were needed. The trial was prematurely terminated after inclusion of 26 patients due to unexpectedly inferior outcomes after intralesional cryotherapy. For primary keloids no convincing difference between treatments was found, but surgery improved scar appearance while cryotherapy did not. For resistant keloids, excision followed by brachytherapy improved scar appearance (POSAS) and scar symptoms (itch and pain) significantly (p < 0.001, p < 0.001 and p = 0.006 respectively) while cryotherapy did not. Neither of the treatments caused indisputable improvements in QoL. Intralesional cryotherapy is inferior to keloid excision followed by brachytherapy for resistant keloids. In primary keloids, intralesional cryotherapy reduced keloid volume and, therefore, may be used in these patients and specific cases. Primary keloid group size was too small to draw valid conclusions, further research on the efficacy of intralesional cryotherapy for primary keloids is warranted.

EXPRESSION AND SIGNIFICANCE OF PEROXISOME PROLIFERATOR ACTIVATED RECEPTOR γ IN KELOID

To investigate the expression and significance of peroxisome proliferator activated receptor γ(PPAR-γ) in human keloid. Twenty-three keloid samples were harvested from the patients undergoing keloid and auto-skin grafting operation as the experimental group (keloid group), and the residual normal skin after auto-skin grafting operation was collected as the control group. The expression of PPAR-γ protein was examined by immunohistochemistry staining in both keloid and normal skin. Referring to Shimizu immunohistochemical standard, the result was graded; the positive rate of samples and the rate of positive cells were calculated. Immunohistochemistry staining showed that PPAR-γ protein was expressed in both keloid and normal skin. In keloid, it located in the pricle cell layer, and granular layer of epidermis, and the dermal vessel; the degree of dyeing was very light. However, in normal skin, it located in the base layer of epidermis, dermal vessel walls, sweat glands and sebaceous glands; the dyeing degree was deeper. Immunohistochemical staining score in the keloid group (2.65±0.78) was significantly lower than that in the control group (3.65±1.19) (t=5.030, P=0.000). The positive rate of samples in the keloid group (52.17%, 12/23) was significantly lower than that in the control group (82.61%, 19/23) (χ2=4.847, P=0.028). The rate of positive cells was 46.04%±8.61% in the keloid group, which was significantly lower than that in the control group (59.39%±11.26%) (t=5.974, P=0.000). Compared with normal skin, the expression of PPAR-γ protein in keloid is down-regulated in in human keloid, indicating that PPAR-γ may be related to the formation of keloid.

The Relationship between Proliferative Scars and Endothelial Function in Surgically Revascularized Patients.

Proliferative scars are benign fibrotic proliferations which demonstrate abnormal wound healing in response to skin injuries. As postulated in the "response to injury hypothesis", atherosclerosis is also triggered by an endothelial injury. Keloid and atherosclerotic processes have many pathophysiological and cytological features in common. In this study, we investigated the relationship between proliferative scars and endothelial function in surgically revascularized patients. We aimed to test the hypothesis that atherosclerosis is a wound healing abnormality. Cross-sectional study. Consecutive patients who were admitted to the cardiology outpatient clinic with a history of coronary artery bypass grafting operation were evaluated. Thirty-three patients with proliferative scars at the median sternotomy site formed the keloid group, and 36 age- and sex-matched patients with no proliferative scar at the median sternotomy site formed the control group. Endothelial function was evaluated by flow-mediated vasodilatation of the brachial artery via ultrasonograhic examination. There is no signicant difference according to the demographic data, biochemical parameters, clinical parameters and number of grafts between keloid and control groups. Endothelial-dependent vasodila-tory response was lower in the keloid group than the control group (9.30±3.5 and 18.68±8.2, respectively; p=0.001). This study showed that endothalial dysfunction, which is strongly correlated with atherosclerosis, was more prominent in patients with proliferative scars. As proliferative scars and atherosclerosis have many features in common, we might conclude that atherosclerosis is a wound healing abnormality.

Preliminary study on CASK/Id1 pathway in fibroblasts of human keloid

To verify the existence and significance of calcium/calmodulin dependent serine protein kinase/inhibitors of differentiation 1 (CASK/Id1) pathway in fibroblasts of human keloid. Immunofluorescence laser was used to confirm CASK and Id1 protein expression and localization in fibroblasts of the keloid and normal skin. RT-PCR and Western-blot were adopted to analysis the CASK and Id1 expression and differences between keloid and normal skin fibroblasts. The natural combination of CASK and Id1 protein of keloid fibroblasts was tested by immunoprecipitation. CASK and Id1 protein expression were both found in fibroblast cells of keloid and normal skin under normal circumstances. Most of CASK and Id1 were distributed in the cytoplasm and nucleus of fibroblasts. The results of RT-PCR showed that the expression of CASK mRNA in the keloid group was 0.658 +/- 0.024, which was lower than that in the normal control group (1.076 +/- 0.008, t = 11.159, P < 0.05). The expression of Id1 mRNA was 0.497 +/- 0.014, which was higher than that in the normal control group (0.307 +/- 0.017, t = 15.148, P < 0.05). The results of Western-blot showed that the expression level for CASK protein in the keloid group was 0.057 +/- 0.006, which was lower than that in the normal control group (0.168 +/- 0.012, t = 13.524, P < 0.05); the expression of Id1 protein was 0.812 +/- 0.035, which was higher than that in the normal control group (0.368 +/- 0.031, t = 16.356, P < 0.05). The results of immunoprecipitation showed that Id1 could be detected in the CASK precipitate, while CASK also could be detected in the Id1 precipitate. There was a natural binding of CASK and Id1 in keloid fibroblasts. CASK/Id1 signal pathway may be existed and involved in the proliferation of keloid fibroblasts, which is related with the occurrence of keloid.

Matrix metalloproteinase‐2 and ‐9 activities in human keloids, hypertrophic and atrophic scars: a pilot study

Proteolytic degradation of extracellular matrix is one of the principal features of cutaneous wound healing but little is known about the activities of gelatinases; matrix metalloproteinase-2 (MMP-2) and matrix metalloproteinase-9 (MMP-9) on abnormal scar formation. The aim of this study is to determine collagen levels and the gelatinase activities in tissue from hypertrophic scars, atrophic scars, keloids and donor skin in 36 patients and 14 donors. Gelatinase levels (proenzyme + active enzyme) were determined by ELISA and their activities by gelatin zymography. MMP-9 activity was undetectable in gelatin zymography analysis. Pro-MMP-2 levels (median) were highest in normal skin group 53.58 (36.40-75.11) OD microg(-1) protein, while active MMP-2 levels were highest in keloid group 52.53 (42.47-61.51) OD microg(-1) protein. The active/pro ratio was the highest in keloid group 0.97 followed by hypertrophic scar, normal skin and atrophic scar groups 0.69 > 0.54 > 0.48, respectively. According to results of our study, the two-phase theory of the duration of hypertrophic scar and keloid formation can be supported by the data of tissue collagen and gelatinase analysis. This study is the first to relate scar formation relationship in regard to gelatinase activation ratio in a keloid, hypertrophic and atrophic scar patient group which is chosen appropriate in age and sex.

5-Fluorouracil Treatment of Problematic Scars

Keloids and hypertrophic scars can be uncomfortable, disfiguring, and aesthetically undesirable. Anecdotal reports suggest that low-dose intralesional fluorouracil can be used to treat these undesirable scars. Using a prospective case series protocol, both keloid and hypertrophic scar patients were included. Keloid patients underwent excision followed by a series of treatments with intralesional 5-fluorouracil into the healing scar to prevent recurrence (n = 32). The hypertrophic scar patients were treated with the same series of injections without scar excision to both control symptoms and improve scar appearance (n = 21). The primary outcome measures were scar volume and a symptom questionnaire. Patients were followed for 1 year after completing the injection treatments. In the keloid group, the recurrence rate was 19 percent at 1-year follow-up for this group of patients who had failed previous corticosteroid injection therapy. In the hypertrophic scar group, 14 percent did not respond to the series of injections. In this group, there was a median volume decrease of 50 percent maintained for 1 year after injection therapy was terminated. Intralesional fluorouracil is a safe and effective means of controlling problem scars in terms of both recurrence and symptom control. Benefits were maintained for at least 1 year after completion of therapy. Intralesional 5-fluorouracil should be considered another option for patients suffering from problematic scars.

Tretinoin reverses upregulation of matrix metalloproteinase-13 in human keloid-derived fibroblasts.

Keloids are skin abnormalities that are characterized by excessive deposition of collagen bundles in the dermis. Patients with keloids complain not only about their cosmetic appearance, but also about continuous itching and/or tenderness associated with chronic inflammation. Degradation of extracellular matrix (ECM) may be upregulated, associated with the expansion of keloids into circumferential skin, and high metabolic activity of keloid tissues may be due to increased matrix metalloproteinase (MMP) activity. Based on these hypotheses, we examined differences in expression of MMP-1, MMP-8, and MMP-13 between keloid-derived and normal dermal fibroblasts. Since retinoids are potent inhibitors of MMPs in the treatment of photoaged skin and cancers, we also examined whether or not tretinoin affects MMP expression of keloid-derived fibroblasts. The results of real-time polymerase chain reaction and ELISA demonstrated significant upregulation of MMP-13 and significant downregulation of MMP-1 and MMP-8 in keloid-derived fibroblasts, at both mRNA and protein levels. MMP-1 mRNA expression in the control group was significantly upregulated after the addition of tretinoin, whereas no significant change was observed in the keloid group. MMP-8 mRNA expression in the control group was significantly upregulated by tretinoin, with the peak at 12 h, while no significant change was observed in the keloid-derived fibroblasts. In contrast, the remarkably elevated MMP-13 mRNA expression in the keloid group was significantly suppressed, with the peak suppression at 12 h after addition of tretinoin, while MMP-13 mRNA expression in the control group was not significantly changed. The decrease in MMP-1 and MMP-8 may contribute to accumulation of type I and type III collagen in keloid tissues, and this mechanism may be modulated by molecular interaction with MMP-13. Tretinoin appeared to reverse the abnormal expression profile of MMPs in keloid-derived fibroblasts, such as markedly elevated expression of MMP-13, partly through inactivation of AP-1 pathway. The present results suggest that tretinoin may be clinically useful to improve the chronic inflammation seen in keloids and prevent expansion of keloid tissues into circumferential normal skin.