Adenoviral overexpression and small interfering RNA suppression demonstrate that plasminogen activator inhibitor-1 produces elevated collagen accumulation in normal and keloid fibroblasts

Natural products - Dawn of keloid treatment

Keloids are prevalent pathological scars, often leading to cosmetic deformities and hindering joint mobility.They cause discomfort, including burning and itching, while gradually expanding and potentially posing a risk of cancer.Developing effective drugs and treatments for keloids has been a persistent challenge in the medical field. Natural products are an important source of innovative drugs and a breakthrough for many knotty disease.Herein, keywords of "natural, plant, compound, extract" were combined with "keloid" and searched in PubMed and Google Scholar, respectively. A total of 32 natural products as well as 9 extracts possessing the potential for treating keloids were ultimately identified.Current research in this field faces a significant challenge due to the lack of suitable animal models, resulting in a predominant reliance on in vitro studies.In vivo and clinical studies are notably scarce as a result.Moreover, there is a notable deficiency in research focusing on the role of nutrients in keloid formation and treatment.The appropriate dosage form (oral, topical, injectable) is crucial for the development of natural product drugs. Finally, the conclusion was hereby made that natural products, when used as adjuncts to other treatments, hold significant potential in the management of keloids.By summarizing the natural products and elucidating their mechanisms in keloid treatment, the present study aims to stimulate further discoveries and research in drug development for effectively addressing this challenging condition.

The uPA System Differentially Alters Fibroblast Fate and Profibrotic Ability in Skin Fibrosis

Skin fibrosis is a common pathological feature of various diseases, and few treatment strategies are available because of the molecular pathogenesis is poorly understood. The urokinase-type plasminogen activator (uPA) system is the major serine protease system, and its components uPA, urokinase plasminogen activator receptor (uPAR) and plasminogen activator inhibitor-1(PAI-1) are widely upregulated in fibrotic diseases, including hypertrophic scars, keloids, and scleroderma. Here, we found that the successful binding of uPA and uPAR activates the downstream peroxisome proliferator-activated receptor (PPAR) signalling pathway to reduce the proliferation, migration, and contraction of disease-derived fibroblasts, contributing to the alleviation of skin fibrosis. However, increased or robust upregulation of the inhibitor PAI-1 inhibits these effects, suggesting of the involvement of PAI-1 in skin fibrosis. Subsequent in vivo studies showed that uPAR inhibitors increased skin fibrosis in mouse models, while uPA agonists and PAI-1 inhibitors reversed these effects. Our findings demonstrate a novel role for the uPA system and highlights its relationships with skin fibrosis, thereby suggesting new therapeutic approaches targeting the uPA system.

Contracting scars from fibrin drops

This paper describes a microscale fibroplasia and contraction model that is based on fibrin-embedded lung fibroblasts and provides a convenient visual readout of fibrosis. Cell-laden fibrin microgel drops are formed by aqueous two-phase microprinting. The cells deposit extracellular matrix (ECM) molecules such as collagen while fibrin is gradually degraded. Ultimately, the cells contract the collagen-rich matrix to form a compact cell-ECM spheroid. The size of the spheroid provides the visual readout of the extent of fibroplasia. Stimulation of this wound-healing model with the profibrotic cytokine TGF-β1 leads to an excessive scar formation response that manifests as increased collagen production and larger cell-ECM spheroids. Addition of drugs also shifted the scarring profile: the FDA-approved fibrosis drugs (nintedanib and pirfenidone) and a PAI-1 inhibitor (TM5275) significantly reduced cell-ECM spheroid size. Not only is the assay useful for evaluation of antifibrotic drug effects, it is relatively sensitive; one of the few in vitro fibroplasia assays that can detect pirfenidone effects at submillimolar concentrations. Although this paper focuses on lung fibrosis, the approach opens opportunities for studying a broad range of fibrotic diseases and for evaluating antifibrotic therapeutics.

Bioinformatics study on different gene expression profiles of fibroblasts and vascular endothelial cells in keloids

Keloid is a benign fibroproliferative skin tumor. The respective functions of fibroblasts and vascular endothelial cells in keloid have not been fully studied. The purpose of this study is to identify the respective roles and key genes of fibroblasts and vascular endothelial cells in keloids, which can be used as new targets for diagnosis or treatment.The microarray datasets of keloid fibroblasts and vascular endothelial cells were obtained from the Gene Expression Omnibus (GEO) database. Differentially expressed genes (DEGs) were screened out. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) were used for functional enrichment analysis. The search tool for retrieval of interacting genes and Cytoscape were used to construct protein-protein interaction (PPI) networks and analyze gene modules. The hub genes were screened out, and the relevant interaction networks and biological process analysis were carried out.In fibroblasts, the DEGs were significantly enriched in collagen fibril organization, extracellular matrix organization and ECM-receptor interaction. The PPI network was constructed, and the most significant module was selected, which is mainly enriched in ECM-receptor interaction. In vascular endothelial cells, the DEGs were significantly enriched in cytokine activity, growth factor activity and transforming growth factor-β (TGF-β) signaling pathway. Module analysis was mainly enriched in TGF-β signaling pathway. Hub genes were screened out separately.In summary, the DEGs and hub genes discovered in this study may help us understand the molecular mechanisms of keloid, and provide potential targets for diagnosis and treatment.

Identification of key genes and pathways in scleral extracellular matrix remodeling in glaucoma: Potential therapeutic agents discovered using bioinformatics analysis

Background: Glaucoma is a leading cause of irreversible blindness. Remodeling of the scleral extracellular matrix (ECM) plays an important role in the development of glaucoma. The aim of this study was to identify the key genes and pathways for the ECM remodeling of sclera in glaucoma by bioinformatics analysis and to explore potential therapeutic agents for glaucoma management. Methods: Genes associated with glaucoma, sclera and ECM remodeling were detected using the text mining tool pubmed2ensembl, and assigned Gene Ontology (GO) biological process terms and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways using the GeneCodis program. A protein-protein interaction (PPI) network was constructed by STRING and visualized in Cytoscape, module analysis was performed using the Molecular Complex Detection (MCODE) plugin, and GO and KEGG analyses of the gene modules were performed using the Database of Annotation, Visualization and Integrated Discovery (DAVID) platform. The genes that clustered in the significant module were selected as core genes, and functions and pathways of the core genes were visualized using ClueGO and CluePedia. Lastly, the drug-gene interaction database was used to explore drug-gene interactions of the core genes to find drug candidates for glaucoma. Results: We identified 125 genes common to "Glaucoma", "Sclera", and "ECM remodeling" by text mining. Gene functional enrichment analysis yielded 30 enriched GO terms and 20 associated KEGG pathways. A PPI network that included 60 nodes with 249 edges was constructed, and three gene modules were obtained using the MCODE. We selected 13 genes that clustered in module 1 as core candidate genes that were associated mainly with ECM degradation and cell proliferation and division. The HIF-1 signaling pathway, FOXO signaling pathway, PI3K-Akt signaling pathway and TGFB signaling pathway were found to be enriched. We found that 11 of the 13 selected genes could be targeted by 26 existing drugs. Conclusions: The results showed that VEGFA, TGFB1, TGFB2, TGFB3, IGF2, IGF1, EGF, FN1, KNG1, TIMP1, SERPINE1, THBS1, and VWF were potential key genes involved to scleral ECM remodeling. Furthermore, 26 drugs were identified as potential therapeutic agents for glaucoma treatment and management.

Keloid disorder: Fibroblast differentiation and gene expression profile in fibrotic skin diseases

Keloid disorder, a group of fibroproliferative skin diseases, is characterized by unremitting accumulation of the extracellular matrix (ECM) of connective tissue, primarily collagen, to develop cutaneous tumors on the predilection sites of skin. There is a strong genetic predisposition for keloid formation, and individuals of African and Asian ancestry are particularly prone. The principal cell type responsible for ECM accumulation is the myofibroblast derived from quiescent resident skin fibroblasts either through trans-differentiation or from keloid progenitor stem cells with capacity for multi-lineage differentiation and self-renewal. The biosynthetic pathways leading to ECM accumulation are activated by several cytokines, but particularly by TGF-β signalling. The mechanical properties of the cellular microenvironment also play a critical role in the cell's response to TGF-β, as demonstrated by culturing of fibroblasts derived from keloids and control skin on substrata with different degrees of stiffness. These studies also demonstrated that culturing of fibroblasts on tissue culture plastic in vitro does not reflect their biosynthetic capacity in vivo. Collectively, our current understanding of the pathogenesis of keloids suggests a complex network of interacting cellular, molecular and mechanical factors, with distinct pathways leading to myofibroblast differentiation and activation. Keloids can serve as a model system of fibrotic diseases, a group of currently intractable disorders, and deciphering of the critical pathogenetic steps leading to ECM accumulation is expected to identify targets for pharmacologic intervention, not only for keloids but also for a number of other, both genetic and acquired, 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.

Human adipose-derived stem cells inhibit bioactivity of keloid fibroblasts

Background

A keloid is a fibroproliferative disorder occurring in wounds characterized by an exaggerated response to injury. To date, no effective cure has been identified. As multipotent stem cells, human adipose-derived stem cells (ADSCs) may show the possibility for curing diseases such as fibrosis. This study sought to explore the potential role of human ADSCs in curing keloids.

Methods

After culture in conditioned medium, gene and protein expression of keloid fibroblasts was examined using real-time polymerase chain reaction (RT-PCR) and Western blotting, while analysis of the cell cycle was used to measure the proliferative properties of the cells. Furthermore, ex vivo explant cultures were used to test the effects of ADSC-conditioned medium (ADSC-CM) on CD31⁺ and CD34⁺ expression in keloid tissue.

Results

Our experimental results show that ADSC-CM was able to attenuate extracellular matrix-related gene expression as well as decrease protein expression. Cell proliferation was significantly suppressed in our study. CD31⁺ and CD34⁺ vessels in ex vivo explants were reduced by 55% and 57% in treatment groups compared with control groups.

Conclusions

Human ADSC-CM significantly inhibited keloid fibroblast-related bioactivities.

Expressions of Collagen I and III in Hypoxic Keloid Tissue

BACKGROUND

Wound heals itself spontaneously as physiological process. However, in some individuals, small wounds such as parenteral injections or body piercings may cause increased expression of collagen synthesis. The condition is known as keloid. Histopathology of keloid demonstrates extensive tissue proliferation that extends beyond the margin of primary wound. As a result, it develops uncontrolled or excessive fibrogenesis and tremendous source of collagen that still causes clinical problems until now. A wound, no matter how small the size is, will be followed by increased expression of collagen synthesis. Procollagen I and III is one of markers indicating the development of fibrosis. In fibrosis, there is hypoxia, which is characterized by stabilization of HIF-1α. Therefore, our study was aimed to obtain information about expression of collagen I and III in hypoxic keloid tissue.

METHOD

The study design was observational descriptive. Keloid specimens were obtained from biopsy and preputium skins as the control specimens were obtained from circumcision. There were 10 tissue specimens for each specimen group. The analysis performed were evaluation of mRNA expression on collagen I, collagen III and HIF-1α using RT-PCR, the evaluation of HIF-1α protein level using ELISA and the expression of collagen I and collagen III protein using immunohistochemistry. Statistically, data was analyzed by unpaired t-test.

RESULTS

In keloid with excessive cell proliferation, we found that the expression of procollagen I mRNA increased 35 times and the expression of procollagen III mRNA increased 27.1 times compared to preputium control group (p<0.05). The expression of procollagen I protein in the dermal layer of keloid was 61% and in the preputium was 37% (p<0.05). The expression of collagen III protein in the dermal layer of keloid was 39% and in the preputium was 16% (p<0.05). There was a 5-fold increase on expression of HIF-1α mRNA in keloid tissue compared to those in preputium (p<0.05). The levels of HIF-1α protein in keloid tissue was 0.201 ng/mg protein and the level in preputium was 0.122 ng/mg protein (p<0.05). There was a strong positive and extremely significant correlation between the expression of HIF-1α protein and procollagen III (R=0.744; p<0.05, Pearson), but HIF-1α with procollagen I are weak correlation (R=0.360; p>0.05, Pearson) Conclusion: Expression of collagen I and III have important role in hypoxic keloid tissue characterized by increased expressions. The expression of collagen I and III is associated with stable HIF-1α in keloid tissue.

Will stem cells bring hope to pathological skin scar treatment?

Pathological skin scars, such as keloids, aesthetically and psychosocially affect patients. The quest for scar reduction and the increasing recognition of patient satisfaction has led to the continued exploration of scar treatment. Stem cells are a promising source for tissue repair and regeneration. The multi-potency and secretory functions of these cells could offer possible treatments for pathological scars and have been examined in recent studies. Here, we analyze the factors that influence the formation of pathological skin scars, summarize recent research on pathological scar treatment with stem cells and elaborate on the possible mechanisms of this treatment. Additionally, other effects of stem cell treatments are also presented while evaluating potential side effects of stem cell-based pathological scar treatments. Thus, this review may provide meaningful guidance in the clinic for scar treatments with stem cells.

Keloids and Hypertrophic Scars: A Spectrum of Clinical Challenges

Since their earliest description, keloids and hypertrophic scars have beleaguered patients and clinicians alike. These scars can be aesthetically disfiguring, functionally debilitating, emotionally distressing, and psychologically damaging, culminating in a significant burden for patients. Our current understanding of keloid pathophysiology has grown and continues to advance while molecular biology, genetics, and technology provide ever-deepening insight into the nature of wound healing and the pathologic perturbations thereof. Greater understanding will lead to the development and application of refined therapeutic modalities. This article provides an overview of our current understanding of keloids, highlighting clinical characteristics and diagnostic criteria while providing a comprehensive summary of the many therapeutic modalities available. The proposed mechanism, application, adverse events, and reported efficacy of each modality is evaluated, and current recommendations are summarized.

Bone marrow derived mesenchymal stem cells inhibit the proliferative and profibrotic phenotype of hypertrophic scar fibroblasts and keloid fibroblasts through paracrine signaling

BACKGROUND

Hypertrophic scars and keloids, characterized by over-proliferation of fibroblasts and aberrant formation of the extracellular matrix (ECM), are considered fibrotic diseases. Accumulating evidence indicates that mesenchymal stem cells (MSCs) promote scar-free wound healing and inhibit fibrotic tissue formation, making them a potentially effective therapeutic treatment for hypertrophic scars and keloids.

OBJECTIVE

To investigate the paracrine effects of bone marrow derived MSCs (BMSCs) on the biological behavior of hypertrophic scar fibroblasts (HSFs) and keloid fibroblasts (KFs).

METHODS

Proliferative and profibrotic phenotype changes of the fibroblasts were analyzed by immunofluorescence staining, in-cell western blot, and real-time PCR.

RESULTS

BMSC-conditioned medium inhibited HSF and KF proliferation and migration, but did not induce apoptosis. Interestingly, normal skin fibroblast-conditioned medium exhibited no inhibitory effects on HSF or KF proliferation and migration. Furthermore, BMSC-conditioned medium significantly decreased expression of profibrotic genes, including connective tissue growth factor, plasminogen activator inhibitor-1, transforming growth factor-β1, and transforming growth factor-β2, in HSFs and KFs at both transcriptional and translational levels. In contrast, the expression of antifibrotic genes, such as transforming growth factor-β3 and decorin, was substantially enhanced under the same culture conditions. Finally, we observed that BMSC-conditioned medium suppressed the ECM synthesis in HSFs and KFs, as indicated by decreased expression of collagen I and fibronectin and low levels of hydroxyproline in cell culture supernatant.

CONCLUSION

These findings suggest that BMSCs attenuate the proliferative and profibrotic phenotype associated with HSFs and KFs and inhibit ECM synthesis through a paracrine signaling mechanism.

Inflammatory Gene Expression Upon TGF-β1-Induced p38 Activation in Primary Dupuytren's Disease Fibroblasts

OBJECTIVES

Inflammation is an underlying mechanism behind fibrotic processes and differentiation of cells into myofibroblasts. Presented study therefore provides new data on activation of autoimmune and inflammatory immune response genes that accompany activation of p38 and cell differentiation in primary cells derived from Dupuytren's disease (DD) patients.

METHODS

Primary non-Dupuytren's disease cells (ND) were isolated from macroscopically unaffected palmar fascia adjacent to diseased tissue obtained from patients diagnosed with the last stage of DD and cultured in vitro. Gene expression, collagen gel contraction assay and analysis of secreted proteins were performed in ND cells treated with TGF-β1 and/or inhibitor of p38 phosphorylation.

RESULTS

During differentiation of ND fibroblasts, increased expression of immune response genes PAI-1, TIMP-1, CCL11, and IL-6 was found. These changes were accompanied by increased cell contractility and activation of p38 and its target kinase MK2. Inhibition of p38 phosphorylation reversed these processes in vitro.

CONCLUSIONS

TGF-β1 induced p38 phosphorylation in ND cells grown from macroscopically unaffected palmar fascia adjacent to diseased tissue from DD patients. This was accompanied by activation of the cytokine genes CCL-11 and IL-6 and secretion of extracellular matrix regulatory proteins PAI-1 and TIMP-1. A combined approach directed toward inflammation and p38 MAPK-mediated processes in DD might be considered for improving management of DD patients and prevention of recurrence.

Dissecting fibrosis: therapeutic insights from the small-molecule toolbox

Fibrosis, which leads to progressive loss of tissue function and eventual organ failure, has been estimated to contribute to ~45% of deaths in the developed world, and so new therapeutics to modulate fibrosis are urgently needed. Major advances in our understanding of the mechanisms underlying pathological fibrosis are supporting the search for such therapeutics, and the recent approval of two anti-fibrotic drugs for idiopathic pulmonary fibrosis has demonstrated the tractability of this area for drug discovery. This Review examines the pharmacology and structural information for small molecules being evaluated for lung, liver, kidney and skin fibrosis. In particular, we discuss the insights gained from the use of these pharmacological tools, and how these entities can inform, and probe, emerging insights into disease mechanisms, including the potential for future drug combinations.

Association of the plasminogen activator inhibitor-1 (PAI-1) Gene -675 4G/5G and -844 A/G promoter polymorphism with risk of keloid in a Chinese Han population

Background

A keloid is pathological scar caused by aberrant response to skin injuries, characterized by excessive accumulation of histological extracellular matrix, and occurs in genetically susceptible individuals. Plasminogen activator inhibitor-1 (PAI-1) has been implicated in the pathogenesis of keloid. We investigated the association between PAI-1 polymorphisms and plasma PAI-1 level with keloid risk.

Material/Methods

A total of 242 Chinese keloid patients and 207 controls were enrolled in this study. Polymerase chain reaction-restriction technique was used to determine PAI-1 promoter polymorphism (-675 4G/5G and -844 A/G) distribution. Plasma PAI-1 levels were detected using enzyme-linked immunosorbent assay (ELISA).

Results

There was a statistically significant difference in the distribution of PAI-1 -675 4G/5G polymorphism between keloid patients and healthy controls. 4G/4G carriers were more likely to develop keloid. In contrast, the -844 A/G polymorphism distribution did not vary significantly between keloid patients and controls. The keloid patients group had a significantly higher plasma PAI-1 level than the control group. In the -675 4G/4G carrier population, the plasma PAI-1 levels were significant higher in keloid patients compared with controls.

Conclusions

Our study provides evidence that PAI-1 promoter polymorphism -675 4G/5G and plasma PAI-1 level are associated with keloid risk. PAI-1 -675 4G/5G polymorphism may be an important hereditary factor responsible for keloid development in the Chinese Han population.

Effect of human Wharton's jelly mesenchymal stem cell paracrine signaling on keloid fibroblasts

Keloid scars are abnormal benign fibroproliferative tumors with high recurrence rates and no current efficacious treatment. Accumulating evidence suggests that human umbilical cord Wharton's jelly-derived mesenchymal stem cells (WJ-MSCs) have antifibrotic properties. Paracrine signaling is considered one of the main underlying mechanisms behind the therapeutic effects of mesenchymal stem cells. However, the paracrine signaling effects of WJ-MSCs on keloids have not yet been reported. The aim of this study is to investigate paracrine signaling effects of human WJ-MSCs on keloid fibroblasts in vitro. Human umbilical cords and keloid skin samples were obtained, and WJ-MSCs and keloid fibroblasts were isolated and cultured. One-way and two-way paracrine culture systems between both cell types were investigated. Plasminogen activator inhibitor-I and transforming growth factor-β2 (TGF-β2) transcripts were upregulated in keloid fibroblasts cultured with WJ-MSC-conditioned medium (WJ-MSC-CM) and cocultured with inserts, while showing lower TGF-β3 gene expression. Interleukin (IL)-6, IL-8, TGF-β1, and TGF-β2 protein expression was also enhanced. The WJ-MSC-CM-treated keloid fibroblasts showed higher proliferation rates than their control keloid fibroblasts with no significant change in apoptosis rate or migration ability. In our culture conditions, the indirect application of WJ-MSCs on keloid fibroblasts may enhance their profibrotic phenotype.

Site-specific keloid fibroblasts alter the behaviour of normal skin and normal scar fibroblasts through paracrine signalling

Keloid disease (KD) is an abnormal cutaneous fibroproliferative disorder of unknown aetiopathogenesis. Keloid fibroblasts (KF) are implicated as mediators of elevated extracellular matrix deposition. Aberrant secretory behaviour by KF relative to normal skin fibroblasts (NF) may influence the disease state. To date, no previous reports exist on the ability of site-specific KF to induce fibrotic-like phenotypic changes in NF or normal scar fibroblasts (NS) by paracrine mechanisms. Therefore, the aim of this study was to investigate the influence of conditioned media from site-specific KF on the cellular and molecular behaviour of both NF and NS enabled by paracrine mechanisms. Conditioned media was collected from cultured primary fibroblasts during a proliferative log phase of growth including: NF, NS, peri-lesional keloid fibroblasts (PKF) and intra-lesional keloid fibroblasts (IKF). Conditioned media was used to grow NF, NS, PKF and IKF cells over 240 hrs. Cellular behavior was monitored through real time cell analysis (RTCA), proliferation rates and migration in a scratch wound assay. Fibrosis-associated marker expression was determined at both protein and gene level. PKF conditioned media treatment of both NF and NS elicited enhanced cell proliferation, spreading and viability as measured in real time over 240 hrs versus control conditioned media. Following PKF and IKF media treatments up to 240 hrs, both NF and NS showed significantly elevated proliferation rates (p<0.03) and migration in a scratch wound assay (p<0.04). Concomitant up-regulation of collagen I, fibronectin, α-SMA, PAI-1, TGF-β and CTGF (p<0.03) protein expression were also observed. Corresponding qRT-PCR analysis supported these findings (P<0.03). In all cases, conditioned media from growing marginal PKF elicited the strongest effects. In conclusion, primary NF and NS cells treated with PKF or IKF conditioned media exhibit enhanced expression of fibrosis-associated molecular markers and increased cellular activity as a result of keloid fibroblast-derived paracrine factors.

Asiatic acid isolated from Centella asiatica inhibits TGF-β1-induced collagen expression in human keloid fibroblasts via PPAR-γ activation

Keloids are fibroproliferative disorders characterized by exuberant extracellular matrix deposition and transforming growth factor (TGF)-β/Smad pathway plays a pivotal role in keloid pathogenesis. Centella asiatica extract has been applied in scar management for ages. As one of its major components, asiatic acid (AA) has been recently reported to inhibit liver fibrosis by blocking TGF-β/Smad pathway. However, its effect on keloid remains unknown. In order to investigate the effects of AA on cell proliferation, invasion and collagen synthesis, normal and keloid fibroblasts were exposed to TGF-β1 with or without AA. Relevant experiments including 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay, 5-ethynyl-2-deoxyuridine (EdU) incorporation assay, Transwell invasion assay, enzyme-linked immunosorbent assay, Western blot, quantitative polymerase chain reaction and RNA interference assay were conducted. As a result, keloid fibroblasts showed higher responsiveness to TGF-β1 stimulation than normal fibroblasts in terms of invasion and collagen synthesis. AA could suppress TGF-β1-induced expression of collagen type I, inhibit Smad 2/3 phosphorylation and plasminogen activator inhibitor-1 (PAI-1) expression, while elevate Smad 7 protein level. Noteworthy, the effects of AA on keloid fibroblasts could be abrogated by PPAR-γ antagonist GW9662 and by silencing of PPAR-γ. The present study demonstrated that AA inhibited TGF-β1-induced collagen and PAI-1 expression in keloid fibroblasts through PPAR-γ activation, which suggested that AA was one of the active constituents of C. asiatica responsible for keloid management, and could be included in the arsenal for combating against keloid.

Propolis modulates vitronectin, laminin, and heparan sulfate/heparin expression during experimental burn healing

OBJECTIVE

This study was aimed at assessing the dynamics of vitronectin (VN), laminin (LN), and heparan sulfate/heparin (HS/HP) content changes during experimental burn healing.

METHODS

VN, LN, and HS/HP were isolated and purified from normal and injured skin of domestic pigs, on the 3rd, 5th, 10th, 15th, and 21st days following thermal damage. The wounds were treated with apitherapeutic agent (propolis), silver sulfadiazine (SSD), physiological salt solution, and propolis vehicle. VN and LN were quantified using an immunoenzymatic assay and HS/HP was estimated by densitometric analysis.

RESULTS

Propolis treatment stimulated significant increases in VN, LN, and HS/HP contents during the initial phase of study, followed by a reduction in the estimated extracellular matrix molecules. Similar patterns, although less extreme, were observed after treatment with SSD.

CONCLUSIONS

The beneficial effects of propolis on experimental wounds make it a potential apitherapeutic agent in topical burn management.

Ex vivo evaluation of antifibrotic compounds in skin scarring: EGCG and silencing of PAI-1 independently inhibit growth and induce keloid shrinkage

Keloid disease (KD) is a common fibroproliferative disorder of unknown etiopathogenesis. Its unique occurrence in human skin and lack of animal models pose challenges for KD research. The lack of a suitable model in KD and over-reliance on cell culture has hampered the progress in developing new treatments. Therefore, we evaluated the effect of two promising candidate antifibrotic therapies: (-)-epigallocatechin-3-gallate (EGCG) and plasminogen activator inhibitor-1 (PAI-1) silencing in a long-term human keloid organ culture (OC). Four millimeters of air-liquid interface (ALI) keloid explants on collagen gel matrix in serum-free medium (n=8 cases) were treated with different modalities (EGCG treatment; PAI-1 knockdown by short interfering RNA (siRNA) and application of dexamethasone (DEX) as control). Normal skin (n=6) was used as control (only for D0 keloid-untreated comparison). Besides routine histology and quantitative (immuno-) histomorphometry, the key phenotypic and growth parameters of KD were assessed. Results demonstrated that EGCG reduced keloid volume significantly (40% by week 4), increased apoptosis (≥40% from weeks 1 to 4), and decreased proliferation (≤17% in week 2). EGCG induced epidermal shrinkage, reduced collagen-I and -III at mRNA and protein levels, depleted 98% of keloid-associated mast cells, and reduced the percentage of both cellularity and blood vessel count by week 4. Knockdown of PAI-1 significantly reduced keloid volume by 28% in week 4, respectively, and reduced collagen-I and -III at both mRNA and protein levels. As expected, DEX increased keloid apoptosis, decreased keloid proliferation, and collagen synthesis, but induced connective tissue growth factor overexpression. In conclusion, using keloid OC model, we provide the first functional evidence for testing candidate antifibrotic compounds in KD. We show that EGCG and PAI-1 silencing effectively inhibits growth and induces shrinkage of human keloid tissue in situ. Therefore, the application of EGCG, PAI-1 silencing, and other emerging compounds tested using this model may provide effective treatment and potentially aid in the prevention of recurrence of KD following surgery.

PAI-1 in tissue fibrosis

Fibrosis is defined as a fibroproliferative or abnormal fibroblast activation-related disease. Deregulation of wound healing leads to hyperactivation of fibroblasts and excessive accumulation of extracellular matrix (ECM) proteins in the wound area, the pathological manifestation of fibrosis. The accumulation of excessive levels of collagen in the ECM depends on two factors: an increased rate of collagen synthesis and or decreased rate of collagen degradation by cellular proteolytic activities. The urokinase/tissue type plasminogen activator (uPA/tPA) and plasmin play significant roles in the cellular proteolytic degradation of ECM proteins and the maintenance of tissue homeostasis. The activities of uPA/tPA/plasmin and plasmin-dependent MMPs rely mostly on the activity of a potent inhibitor of uPA/tPA, plasminogen activator inhibitor-1 (PAI-1). Under normal physiologic conditions, PAI-1 controls the activities of uPA/tPA/plasmin/MMP proteolytic activities and thus maintains the tissue homeostasis. During wound healing, elevated levels of PAI-1 inhibit uPA/tPA/plasmin and plasmin-dependent MMP activities, and, thus, help expedite wound healing. In contrast to this scenario, under pathologic conditions, excessive PAI-1 contributes to excessive accumulation of collagen and other ECM protein in the wound area, and thus preserves scarring. While the level of PAI-1 is significantly elevated in fibrotic tissues, lack of PAI-1 protects different organs from fibrosis in response to injury-related profibrotic signals. Thus, PAI-1 is implicated in the pathology of fibrosis in different organs including the heart, lung, kidney, liver, and skin. Paradoxically, PAI-1 deficiency promotes spontaneous cardiac-selective fibrosis. In this review, we discuss the significance of PAI-1 in the pathogenesis of fibrosis in multiple organs.

Keloid explant culture: a model for keloid fibroblasts isolation and cultivation based on the biological differences of its specific regions

In vitro studies with keloid fibroblasts frequently present contradictory results. This may occur because keloids present distinct genotypic and phenotypic characteristics in its different regions, such as the peripheral region in relation to the central region. We suggest an explant model for keloid fibroblasts harvesting, standardising the initial processing of keloid samples to obtain fragments from different regions, considering its biological differences, for primary cell culture. The different keloid regions were delimited and fragments were obtained using a 3-mm diameter punch. To remove fragments from the periphery, the punch was placed in one longitudinal line extremity, respecting the lesion borders. For the central region, it was placed in the intersection of lines at the level of the largest longitudinal and transversal axes, the other fragments being removed centrifugally in relation to the first one. Primary fibroblast culture was carried out by explant. Flow cytometry analysis showed cell cycle differences between the groups, confirming its different origins and biological characteristics. In conclusion, our proposed model proved itself efficient for keloid fibroblast isolation from specific regions and cultivation. Its simplicity and ease of execution may turn it into an important tool for studying the characteristics of the different keloid-derived fibroblasts in culture.

Epigenetically altered wound healing in keloid fibroblasts

Keloids are benign dermal tumors that form during wound healing in genetically susceptible individuals. The mechanism(s) of keloid formation is unknown and there is no satisfactory treatment. We have reported differences between fibroblasts cultured from normal scars and keloids that include a pattern of glucocorticoid resistance and altered regulation of genes in several signaling pathways associated with fibrosis, including Wnt and IGF/IGF-binding protein 5 (IGFBP5). As previously reported for glucocorticoid resistance, decreased expression of the Wnt inhibitor secreted frizzled-related protein 1 (SFRP1), matrix metalloproteinase 3 (MMP3), and dermatopontin (DPT), and increased expression of IGFBP5 and jagged 1 (JAG1) are seen only in fibroblasts cultured from the keloid nodule. In vivo, decreased expression of SFRP1 and SFRP2 and increased expression of IGFBP5 proteins are observed only in proliferative keloid tissue. There is no consistent difference in the replicative life span of normal and keloid fibroblasts, and the altered response to hydrocortisone (HC) and differential regulation of a subset of genes in standard culture medium are maintained throughout at least 80% of the culture lifetime. Preliminary studies using ChIP-chip analysis, Trichostatin A, and 5-aza-2'-deoxycytidine further support an epigenetically altered program in keloid fibroblasts that includes an altered pattern of DNA methylation and histone acetylation.

Genetics of keloid scarring

Keloid scarring, also known as keloid disease (KD), is a common, abnormally raised fibroproliferative cutaneous lesion that can occur following even minor skin trauma. The aetiopathogenesis of KD has remained an enigma todate compounded by an ill-defined clinical management. There is strong evidence suggesting a genetic susceptibility in individuals affected by KD, including familial heritability, common occurrence in twins and high prevalence in certain ethnic populations. This review aims to address the genetic aspects of KD that have been described in present literature that include inheritance patterns, linkage studies, case-control association studies, whole genome gene expression microarray studies and gene pathways that were significant in KD. In addition to our clinical and scientific background in KD, we used search engines, Scopus, Scirus and PubMed, which searched for key terms covering various genetic aspects of KD. Additionally, genes reported in seven whole genome gene expression microarray studies were separately compared in detail. Our findings indicate a varied inheritance pattern in KD (predominantly autosomal dominant), linkage loci (chromosomes 2q23 and 7p11), several human leukocyte antigen (HLA) alleles (HLA-DRB1*15, HLA-DQA1*0104, DQ-B1*0501 and DQB1*0503), negative candidate gene case-control association studies and at least 25 dysregulated genes reported in multiple microarray studies. The major pathways reportedly proposed to be involved in KD include apoptosis, mitogen-activated protein kinase, transforming growth factor-beta, interleukin-6 and plasminogen activator inhibitor-1. In summary, involvement of more than one gene is likely to be responsible for susceptibility to KD. A better understanding of the genes involved in KD may potentially lead to the development of more effective diagnostic, therapeutic and prognostic measures.

A Profibrotic Effect of Plasminogen Activator Inhibitor Type-1 (PAI-1) in the Heart

Increased expression of PAI-1 is profibrotic in several organs. However, its potentially profibrotic effects in the heart subjected to infarction have not been elucidated. Accordingly, we induced coronary occlusion in 10-week-old mice congenic on a C57BL6 background and in mice overexpressing PAI-1 (PTG) in multiple tissues. Compared with C57BL6 control mice without myocardial infarction (MI), PTG mice exhibited consistently elevated PAI-1 in plasma at 16 weeks of age but virtually identical PAI-1 content in left ventricular (LV) myocardium. However, they exhibited a 2-fold increase in LV PAI-1 content 6 weeks after induction of MI (4.21 ± 1.0 ng/ml tissue protein) compared with that in C57BL6 mice (2.04 ± 0.5, P < 0.05). In 16-week-old mice, ultrasonically delineated LV fractional shortening (FS) was comparable in normal PTG and normal C57BL6 controls. However, 6 weeks after MI, PTG ( n = 21) compared with C57BL6 ( n = 14) mice exhibited markedly thinner LV posterior walls in both diastole (C57BL6 0.79 ± 0.05 mm, PTG 0.55 ± 0.06, P < 0.05) and systole (0.97 ± 0.05 mm, 0.75 ± 0.06, P < 0.05); increased end systolic LV dimensions (4.54 ± 0.2 mm, 5.17 ± 0.2, P < 0.05); and significantly depressed FS, more impaired LV segmental function, and greater mitral E wave amplitude. Compared with fibrosis assessed by Masson staining of sections from apex to base in C57BL6 mice (10.85 ± 0.43% LV area), PTG mice exhibited 33% more LV fibrosis after MI ( P < 0.05). Thus, PAI-1 is profibrotic in the heart subjected to infarction. Accordingly, overexpression of PAI-1 is a promising target for attenuation of heart failure after MI that may be exacerbated by fibrosis.