P38 MAP kinase mediates transforming growth factor-beta2 transcription in human keloid fibroblasts

Placental mesenchymal stem cells-secreted proenkephalin suppresses the p38 MAPK signaling to block hyperproliferation of keloid fibroblasts

BACKGROUND

Thanks to their multi-potency and secretory functions, mesenchymal stem cells (MSCs) have long been established as an ideal cell type for skin wound healing and a candidate therapeutic strategy for excessive pathological scarring in the meantime. This study focuses on the effect of placental MSCs (PMSCs) on the activity of keloid fibroblasts (KFs) and the potential involvement of proenkephalin (PENK).

METHODS

Secretory protein of PMSC that are lowly expressed in KFs were predicted by bioinformatics analyses. The expression of PENK in KFs was detected by RT-qPCR and western blot analysis. PMSCs were co-cultured with KFs and dermal fibroblasts (DFs) to examine their effect on proliferation, migration, invasion, and apoptosis of the distinct cell types. PENK secretion by PMSCs and its uptake by KFs were examined by ELISA, WB, and immunofluorescence staining. Loss-of-functions of PENK and p38-MAPK were induced to examine the activity of KFs in vitro and in mice.

RESULTS

PENK, a secretory protein of PMSCs, was conspicuously downregulated in KFs compared to normal DFs. PMSC stimulation suppressed proliferation, migration, invasion, and resistance to apoptosis of the co-cultured KFs but not DFs, which was ascribed to the upregulation of PENK protein in KFs. PMSCs-secreted PENK suppressed p38 phosphorylation in KFs. The proliferative and aggressive properties of KFs in vitro and the nodule-forming capacity of KFs in vivo were promoted upon PENK downregulation but suppressed by the p38 MAPK inhibitor SB202190.

CONCLUSION

This work unravels that PMSCs-secreted PENK suppresses the p38 MAPK signaling to block hyperproliferation of KFs.

An updated review of the immunological mechanisms of keloid scars

Keloid is a type of disfiguring pathological scarring unique to human skin. The disorder is characterized by excessive collagen deposition. Immune cell infiltration is a hallmark of both normal and pathological tissue repair. However, the immunopathological mechanisms of keloid remain unclear. Recent studies have uncovered the pivotal role of both innate and adaptive immunity in modulating the aberrant behavior of keloid fibroblasts. Several novel therapeutics attempting to restore regulation of the immune microenvironment have shown variable efficacy. We review the current understanding of keloid immunopathogenesis and highlight the potential roles of immune pathway-specific therapeutics.

Post-Inflammatory Hyperpigmentation in Dark Skin: Molecular Mechanism and Skincare Implications

Human skin is characterized by significant diversity in color and tone, which are determined by the quantity and distribution of melanin pigment in the epidermis. Melanin absorbs and reflects ultraviolet radiation (UVR), preventing the damage to genomic DNA in the epidermis and degradation of collagen in the dermis; therefore, darker skin types are thought to be well protected from the photodamage because of the high melanin content. However, increased content of melanin in combination with the extrinsic stress factors causing inflammation such as excess UVR, allergic reactions, or injury can also frequently lead to cosmetic problems resulting in discoloration and scarring. This review summarizes current knowledge on histopathology and likely molecular signatures of one of the most common problems, post-inflammatory hyperpigmentation (PIH). The mechanisms proposed so far are subsequently discussed in the context of other factors characterizing darker skin types. This includes the common cellular features, organization of upper skin layers, and major biomarkers, with particular emphasis on increased propensities to systemic and localized inflammation. Enhanced or prolonged inflammatory responses can not only affect the process of melanogenesis but also have been implicated in injury-related skin pathologies and aging. Finally, we summarize the major cosmetic treatments for PIH and their known anti-inflammatory targets, which can be beneficial for darker skin tones and combined with broad-spectrum filters against UVR.

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

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

The "Matrisome" reveals the characterization of skin keloid microenvironment

Keloids are fibroproliferative dermal tumors of unknown origin that are characterized by the overabundant accumulation of extracellular matrix (ECM) components. The mechanism of keloid formation has remained unclear because of a poor understanding of its molecular basis. In this study, the dermal ECM components of keloids were identified and the pathological features of keloid formation were characterized using large-scale quantitative proteomic analyses of decellularized keloid biomatrix scaffolds. We identified a total of 267 dermal core ECM and ECM-associated proteins that were differentially expressed between patients with keloids and healthy controls. Skin mechanical properties and biological processes including protease activity, wound healing, and adhesion were disordered in keloids. The integrated network analysis of the upregulated ECM proteins revealed multiple signaling pathways involved in these processes that may lead to keloid formation. Our findings may improve the scientific basis of keloid treatment and provide new ideas for the establishment of keloid models.

Metformin Inhibits Transforming Growth Factor β-Induced Fibrogenic Response of Human Dermal Fibroblasts and Suppresses Fibrosis in Keloid Spheroids

ABSTRACT

Accumulation of excessive extracellular matrix (ECM) and aberrant transforming growth factor β (TGF-β) signaling pathway function can be potential therapeutic targets for keloid treatment. In this study, we examined the antifibrotic effect of metformin as a suppressor of TGF-β signaling pathways in human dermal fibroblasts (HDFs) and keloid spheroids. Human dermal fibroblasts were stimulated with TGF-β (10 ng/mL) and treated with metformin (10 mM). The mRNA and protein expression of ECM components were evaluated by quantitative polymerase chain reaction, western blot, and immunofluorescence assay. In addition, we immunohistochemically examined the expression levels of ECM proteins in keloid spheroids. After addition of metformin (10 mM), collagen types I and III and elastin mRNA levels were significantly decreased in HDFs, and collagen type I protein level was significantly decreased. In addition, the expression levels of collagen types I and III, fibronectin, and elastin were significantly reduced in keloid spheroids after treatment with metformin (100 mM). Collagen types I and III and p-Smad2/3 complex proteins were decreased in metformin-treated keloid spheroids. These findings indicated that metformin inhibits the expression of ECM components in TGF-β-stimulated HDFs and keloid spheroids. Therefore, we suggest the potential of metformin as an effective agent for the treatment of keloids.

Downregulation of CR6-interacting factor 1 suppresses keloid fibroblast growth via the TGF-β/Smad signaling pathway

Keloids are a type of aberrant skin scarring characterized by excessive accumulation of collagen and extracellular matrix (ECM), arising from uncontrolled wound healing responses. While typically non-pathogenic, keloids are occasionally regarded as a form of benign tumor. CR6-interacting factor 1 (CRIF1) is a well-known CR6/GADD45-interacting protein, that has both nuclear and mitochondrial functions, and also exerts regulatory effects on cell growth and apoptosis. In this study, cell proliferation, cell migration, collagen production and TGF-β signaling was compared between normal fibroblasts (NFs) and keloid fibroblasts (KFs). Subsequently, the effects of CRIF1 deficiency were investigated in both NFs and KFs. Cell proliferation, cell migration, collagen production and protein expressions of TGF-β, phosphorylation of Smad2 and Smad3 were all found to be higher in KFs compared to NFs. CRIF1 deficiency in NFs and KFs inhibited cell proliferation, migration, and collagen production. In addition, phosphorylation of Smad2 and Smad3, which are transcription factors of collagen, was decreased. In contrast, mRNA expression levels of Smad7 and SMURF2, two important inhibitory proteins of Smad2/3, were increased, suggesting that CRIF1 may regulate collagen production. CRIF1 deficiency decreases the proliferation and migration of KFs, thereby inhibiting their overgrowth via the transforming growth factor-β (TGF-β)/Smad pathway. CRIF1 may therefore represent a potential therapeutic target in keloid pathogenesis.

Nintedanib inhibits keloid fibroblast functions by blocking the phosphorylation of multiple kinases and enhancing receptor internalization

Keloid is a benign skin tumor characterized by its cell hyperproliferative activity, invasion into normal skin, uncontrolled growth, overproduction and deposition of extracellular matrices and high recurrence rate after various therapies. Nintedanib is a receptor tyrosine kinase inhibitor targeting VEGF, PDGF, FGF, and TGF-β receptors with proved efficacy in anti-angiogenesis and in treating various types of cancers. In this study, we investigated the effects of nintedanib on keloid fibroblasts in both in vitro and ex vivo models. Keloid fibroblasts were prepared from 54 keloid scar samples in active stages collected from 49 patients. We found that nintedanib (1−4 μM) dose-dependently suppressed cell proliferation, induced G₀/G₁ cell cycle arrest, and inhibited migration and invasion of keloid fibroblasts. The drug also significantly inhibited the gene and protein expression of collagen I (COL-1) and III (COL-3), fibronectin (FN), and connective growth factor (CTGF), as well as the gene expression of other pathological factors, such as alpha smooth muscle actin (α-SMA), plasminogen activator inhibitor-1 (PAI-1), FK506-binding protein 10 (FKBP10), and heat shock protein 47 (HSP47) in keloid fibroblasts. Furthermore, nintedanib treatment significantly suppressed the phosphorylation of p38, JNK, ERK, STAT3, and Smad, enhanced endocytosis of various growth factor receptors. Using an ex vivo tissue explant model, we showed that nintedanib significantly suppressed cell proliferation, migration, and collagen production. The drug also significantly disrupted microvessel structure ex vivo. In summary, our results demonstrate that nintedanib is likely to become a potential targeted drug for keloid systemic therapy.

The Keloid Disorder: Heterogeneity, Histopathology, Mechanisms and Models

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

Dynamics of the Activity of MAP-Kinase Cascades in the Healing Process of Postoperative Musculocutaneous Wounds

Background. Management of the reparative process is an urgent task of modern medicine. In our opinion, the development of pathogenetically grounded approaches to optimizing the repair process for managing the interrelations of stromal cells is promising. One of the promising areas in this regard is the impact on the MAPK-cascades.Aim: to study the expression of MAP-kinase mechanisms in the regulation of repair by the example of a musculocutaneous wound.Methods. A linear muscular skin wound was modeled using Wistar rats weighing 220–250 g at the age of 9 months (n = 24). Immunofluorescence staining was performed to detect the activity of p38, JNK, and ERK MAPK cascades from 1 to 30 days.Results. It was established that specific staining in the area of connective tissue formation during staining with p38 MAPK and its phosphorylated form was first observed on the 3rd day, and its maximum severity occurred at the same time. On the 7th and 14th day, small zones in the area of scar formation were minimally stained. The phosphorylated part of the JNK-cascade in the zone of traumatic injury was detected starting from the 1st day after the injury. Bright color persisted on the 3rd day. On the 7th day, the color was minimal, and by the 14th day a second wave of expression was observed. ERK-staining was observed from the 1st to the 14th day with a peak activity on the 3rd day.Conclusion. Thus, we revealed the simultaneous involvement of p38, JNK-, and ERK-cascades in the regulation of the reparative process in the conditions of a musculoskeletal wound. At the same time, it is noteworthy that the peak activity of all cascades coincides and falls on the 3rd day.

Baicalein retards proliferation and collagen deposition by activating p38MAPK-JNK via microRNA-29

Immoderate proliferation and deposition of collagen generally result in hypertrophic scars and even keloids. microRNA-29 (miR-29) has been proved as a crucial regulator in these pathological processes. Although mounting evidence have proved baicalein (BAI) impairs scar formation, it is still incompletely understood whether miR-29 participated in the underlying mechanism. In the present study, NIH-3T3 cells were stimulated with BAI, and then cell viability was analyzed by cell counting kit-8 (CCK-8) and Western blot. We further analyzed total soluble collagen, collagen 1, and alpha-smooth muscle actin (α-SMA) in NIH-3T3 cells, which were exposed to transforming growth factor beta 1 (TGF-β1)/BAI, using a Sircol assay kit, quantitative reverse transcription-PCR (qRT-PCR) and Western blot, respectively. Besides, the miR-29 inhibitor was transduced and its transfection efficiency was verified by qRT-PCR. Finally, the phosphorylated p38 mitogen-activated protein kinase (p38MAPK) and c-Jun N-terminal kinase (JNK) were examined by Western blot. BAI effectively retarded NIH-3T3 proliferation in a dose-dependent manner. Besides, TGF-β1-induced deposition of total soluble collagen and synthesis of collagen 1 and α-SMA were repressed by BAI at mRNA and protein levels. However, miR-29 inhibitor reversed the effects of BAI. Remarkably, BAI promoted phosphorylated expression of p38MAPK and JNK while miR-29 inhibitor reversed its effects on the phosphorylated expression of p38MAPK and JNK. BAI effectively weakened the cell viability and repressed TGF-β1-induced total soluble collagen as well as collagen 1 and α-SMA by upregulating miR-29. Mechanically, BAI activates the p38MAPK/JNK pathway by promoting miR-29.

Keloid research: current status and future directions

INTRODUCTION

Keloids and hypertrophic scars are fibroproliferative disorders of the skin that result from abnormal healing of injured or irritated skin. Multiple studies suggest that genetic, systemic and local factors may contribute to the development and/or growth of keloids and hypertrophic scars. A key local factor may be mechanical stimuli. Here, we provide an up-to-date review of the studies on the roles that genetic variation, epigenetic modifications and mechanotransduction play in keloidogenesis.

METHODS

An English literature review was performed by searching the PubMed, Embase and Web of Science databases with the following keywords: genome-wide association study; epigenetics; non-coding RNA; microRNA; long non-coding RNA (lncRNA); DNA methylation; mechanobiology; and keloid. The searches targeted the time period between the date of database inception and July 2018.

RESULTS

Genetic studies identified several single-nucleotide polymorphisms and gene linkages that may contribute to keloid pathogenesis. Epigenetic modifications caused by non-coding RNAs (e.g. microRNAs and lncRNAs) and DNA methylation may also play important roles by inducing the persistent activation of keloidal fibroblasts. Mechanical forces and the ensuing cellular mechanotransduction may also influence the degree of scar formation, scar contracture and the formation/progression of keloids and hypertrophic scars.

CONCLUSIONS

Recent research indicates that the formation/growth of keloids and hypertrophic scars associate clearly with genetic, epigenetic, systemic and local risk factors, particularly skin tension around scars. Further research into scar-related genetics, epigenetics and mechanobiology may reveal molecular, cellular or tissue-level targets that could lead to the development of more effective prophylactic and therapeutic strategies for wounds/scars in the future.

The Reparative Abilities of Menstrual Stem Cells Modulate the Wound Matrix Signals and Improve Cutaneous Regeneration

Considerable advances have been made toward understanding the cellular and molecular mechanism of wound healing, however, treatments for chronic wounds remain elusive. Emerging concepts utilizing mesenchymal stem cells (MSCs) from umbilical cord, adipose tissue and bone marrow have shown therapeutical advantages for wound healing. Based on this positive outcome, efforts to determine the optimal sources for MSCs are required in order to improve their migratory, angiogenic, immunomodulatory, and reparative abilities. An alternative source suitable for repetitive, non-invasive collection of MSCs is from the menstrual fluid (MenSCs), displaying a major practical advantage over other sources. This study aims to compare the biological functions and the transcriptomic pattern of MenSCs with umbilical cord MSCs in conditions resembling the wound microenvironment. Consequently, we correlate the specific gene expression signature from MenSCs with changes of the wound matrix signals in vivo. The direct comparison revealed a superior clonogenic and migratory potential of MenSCs as well as a beneficial effect of their secretome on human dermal fibroblast migration in vitro. Furthermore, MenSCs showed increased immunomodulatory properties, inhibiting T-cell proliferation in co-culture. We further, investigated the expression of selected genes involved in wound repair (growth factors, cytokines, chemokines, AMPs, MMPs) and found considerably higher expression levels in MenSCs (ANGPT1 1.5-fold; PDGFA 1.8-fold; PDGFB 791-fold; MMP3 21.6-fold; ELN 13.4-fold; and MMP10 9.2-fold). This difference became more pronounced under a pro-inflammatory stimulation, resembling wound bed conditions. Locally applied in a murine excisional wound splinting model, MenSCs showed a significantly improved wound closure after 14 days, as well as enhanced neovascularization, compared to the untreated group. Interestingly, analysis of excised wound tissue revealed a significantly higher expression of VEGF (1.42-fold) among other factors, translating an important conversion of the matrix signals in the wound site. Furthermore, histological analysis of the wound tissue from MenSCs-treated group displayed a more mature robust vascular network and a genuinely higher collagen content confirming the pro-angiogenic and reparative effect of MenSCs treatment. In conclusion, the superior clonogenicity, immunosuppressive and migration potential in combination with specific paracrine signature of MenSCs, resulted in an enhanced wound healing and cutaneous regeneration process.

Opposite effects of non-thermal plasma on cell migration and collagen production in keloid and normal fibroblasts

Recent progress in the understanding non-thermal plasma (NTP) properties prompted its application in the treatment of various diseases. However, therapeutic effect of NTP on keloid cells has not been reported previously. We sought to investigate the effect of NTP treatment on keloid by comparing cell migration and collagen production of keloid (KFs) and normal fibroblasts (NFs) and determined the regulatory pathways involved. We assessed NTP effects on cell migration in KFs and NFs by the wound healing assay and measured the expression of the epidermal growth factor receptor (EGFR), signal transducer and activator of transcription-3 (STAT3), and collagen by western blot. Expression of the transforming growth factor-β and Type I collagen following NTP treatment was determined by reverse transcription-polymerase chain reaction, immunofluorescence staining, and the Sircol collagen assay. NTP treatment increased cell migration and collagen production of NFs. However, it reduced these parameters in KFs. NTP reduced the expression of EGFR, STAT3, and Type I collagen in KFs but increased their levels in NFs. We revealed that NTP suppressed KF cell migration via down-regulation of EGFR and STAT3 and reduced collagen production via supressing transforming growth factor-β. Our data suggest that NTP may be a new therapeutic strategy for keloids.

From genetics to epigenetics: new insights into keloid scarring

Keloid scarring is a dermal fibroproliferative response characterized by excessive and progressive deposition of collagen; aetiology and molecular pathology underlying keloid formation and progression remain unclear. Genetic predisposition is important in the pathogenic processes of keloid formation, however, environmental factors and epigenetic mechanisms may also play pivotal roles. Epigenetic modification is a recent area of investigation in understanding the molecular pathogenesis of keloid scarring and there is increasing evidence that epigenetic changes may play a role in induction and persistent activation of fibroblasts in keloid scars. Here we have reviewed three epigenetic mechanisms: DNA methylation, histone modification and the role of non-coding RNAs. We also review the evidence that these mechanisms may play a role in keloid formation - in future, it may be possible that epigenetic markers may be used instead of prognostic or diagnostic markers here. However, there is a significant amount of work required to increase our current understanding of the role of epigenetic modification in keloid disease.

Novel Insights on Understanding of Keloid Scar: Article Review

Keloid scar, dermal benign fibro-proliferative growth that extends outside the original wound and invades adjacent dermal tissue due to extensive production of extracellular matrix, especially collagen, which caused by over expression of cytokines and growth factors. Although many attempts were made to understand the exact pathophysiology and the molecular abnormalities, the pathogenesis of keloid scar is yet to be determined. Even though there are several treatment options for keloid scars include combination of medical and surgical therapies like combination of surgical removal followed by cryotherapy or intralesional steroid therapy, the reoccurrence rate is still high despite the present treatment. In this review, PubMed, clinical key and Wright State Library web site have been used to investigate any update regarding Keloid disease. We used Keloid, scar formation, hypertrophic scar and collagen as key words. More than 40 articles have been reviewed. This paper reviews literature about keloid scar formation mechanism, the most recent therapeutic options including the ones under research.

Heat Shock Protein 90 Inhibitor Decreases Collagen Synthesis of Keloid Fibroblasts and Attenuates the Extracellular Matrix on the Keloid Spheroid Model

BACKGROUND

The 90-kDa heat-shock protein (heat-shock protein 90) is an abundant cytosolic chaperone, and inhibition of heat-shock protein 90 by 17-allylamino-17-demethoxygeldanamycin (17-AAG) compromises transforming growth factor (TGF)-β-mediated transcriptional responses by enhancing TGF-β receptor I and II degradation, thus preventing Smad2/3 activation. In this study, the authors evaluated whether heat-shock protein 90 regulates TGF-β signaling in the pathogenesis and treatment of keloids.

METHODS

Keloid fibroblasts were treated with 17-AAG (10 μM), and mRNA levels of collagen types I and III were determined by real-time reverse- transcriptase polymerase chain reaction. Also, secreted TGF-β1 was assessed by enzyme-linked immunosorbent assay. The effect of 17-AAG on protein levels of Smad2/3 complex was determined by Western blot analysis. In addition, in 17-AAG-treated keloid spheroids, the collagen deposition and expression of major extracellular matrix proteins were investigated by means of Masson trichrome staining and immunohistochemistry.

RESULTS

The authors found that heat-shock protein 90 is overexpressed in human keloid tissue compared with adjacent normal tissue, and 17-AAG decreased mRNA levels of type I collagen, secreted TGF-ß1, and Smad2/3 complex protein expression in keloid fibroblasts. Masson trichrome staining revealed that collagen deposition was decreased in 17-AAG-treated keloid spheroids, and immunohistochemical analysis showed that expression of collagen types I and III, elastin, and fibronectin was markedly decreased in 17-AAG-treated keloid spheroids.

CONCLUSION

These results suggest that the antifibrotic action of heat-shock protein 90 inhibitors such as 17-AAG may have therapeutic effects on keloids.

All-Trans Retinoic Acid Induces TGF-β2 in Intestinal Epithelial Cells via RhoA- and p38α MAPK-Mediated Activation of the Transcription Factor ATF2

Objective

We have shown previously that preterm infants are at risk of necrotizing enterocolitis (NEC), an inflammatory bowel necrosis typically seen in infants born prior to 32 weeks’ gestation, because of the developmental deficiency of transforming growth factor (TGF)-β₂ in the intestine. The present study was designed to investigate all-trans retinoic acid (atRA) as an inducer of TGF-β₂ in intestinal epithelial cells (IECs) and to elucidate the involved signaling mechanisms.

Methods

AtRA effects on intestinal epithelium were investigated using IEC6 cells. TGF-β₂ expression was measured using reverse transcriptase-quantitative polymerase chain reaction (RT-qPCR) and Western blots. Signaling pathways were investigated using Western blots, transiently-transfected/transduced cells, kinase arrays, chromatin immunoprecipitation, and selective small molecule inhibitors.

Results

AtRA-treatment of IEC6 cells selectively increased TGF-β₂ mRNA and protein expression in a time- and dose-dependent fashion, and increased the activity of the TGF-β₂ promoter. AtRA effects were mediated via RhoA GTPase, Rho-associated, coiled-coil-containing protein kinase 1 (ROCK1), p38α MAPK, and activating transcription factor (ATF)-2. AtRA increased phospho-ATF2 binding to the TGF-β₂ promoter and increased histone H2B acetylation in the TGF-β₂ nucleosome, which is typically associated with transcriptional activation.

Conclusions

AtRA induces TGF-β₂ expression in IECs via RhoA- and p38α MAPK-mediated activation of the transcription factor ATF2. Further studies are needed to investigate the role of atRA as a protective/therapeutic agent in gut mucosal inflammation.

Effect of captopril on collagen metabolisms in keloid fibroblast cells

BACKGROUND

Keloid is a proliferative disease of fibrous tissues. The mechanism and consistently effective treatments of keloid remained unknown. Although there was a report about treating keloid with topical captopril, the further investigation about captopril affecting keloid has not been performed so far.

OBJECTIVES

The aim of this study was to analyse the effect of captopril on collagen metabolisms in keloid fibroblast cells, and to provide information for the mechanism and therapy of keloid.

METHODS

To investigate the effects and relative mechanism of captopril on keloid fibroblast cells, we examined the changes of collagen metabolism, expression of angiotensin, transforming growth factor (TGF)-β1, platelet-derived growth factor (PDGF)-BB and heat shock protein 47 (HSP47), and cellular proliferation in keloid fibroblast cells.

RESULTS

We found that all collagen metabolisms, expression of TGF-β1, PDGF-BB and HSP47, and cellular proliferation decreased significantly with effective captopril concentrations in keloid fibroblast cells.

CONCLUSIONS

With a comprehensive analysis of test results, we proposed that captopril may decrease the expression of angiotensin, PDGF-BB, TGF-β1 and HSP47, and further inhibit proliferation and collagen synthesis of keloid fibroblast cells, which were the key in keloid formation.

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.

Unfolded protein response regulation in keloid cells

BACKGROUND

Keloids are a common form of pathologic wound healing characterized by excessive production of extracellular matrix. The unfolded protein response (UPR) is a cellular response to hypoxia, a component of the wound microenvironment, capable of protecting cells from the effects of over-accumulation of misfolded proteins. Since keloids have hypersecretion of extracellular matrix, we hypothesized that keloid fibroblasts (KFs) may have enhanced activation of the UPR compared with normal fibroblasts (NFs).

METHODS

KFs and NFs were placed in a hypoxia chamber for 0, 24, and 48h. We also used tunicamycin to specifically up-regulate the UPR. UPR activation was assayed by PCR for xbp-1 splicing and by immunoblotting with specific antibodies for the three UPR transducers. Nuclear localization of XBP-1 protein in KFs was confirmed by immunofluorescence.

RESULTS

There is increased activation of XBP-1 protein in KFs compared with NFs following exposure to hypoxia. Pancreatic ER kinase (PERK) and ATF-6, two other pathways activated by the UPR, show comparable activation between KFs and NFs. We confirmed that there is enhanced activation of XBP-1 by demonstrating increased nuclear localization of XBP-1 using immunofluorescence.

CONCLUSION

In contrast to our initial hypothesis that keloids would have broad activation of the UPR, we demonstrate here that there is a specific up-regulation of one facet of the UPR response. This may represent a specific molecular defect in KFs compared with NFs, and also suggests modulation of the UPR can be used in wound healing therapy.

Inhibition of HSP27 phosphorylation by a cell-permeant MAPKAP Kinase 2 inhibitor

Heat shock protein 27 (HSP27) has been implicated in many intracellular signaling processes. Since the phosphorylation of HSP27 can modulate its activity, the ability to inhibit phosphorylation of HSP27 might have clinical relevance especially with regard to the treatment of fibrosis. We have developed a cell-permeant peptide inhibitor of MAPKAP Kinase 2 (MK2), an enzyme that phosphorylates HSP27, by combining a previously described peptide substrate of MK2 with a cell penetrating peptide. This novel MK2 inhibitor (MK2i) reduced HSP27 phosphorylation by MK2 in vitro. At 10 microM, MK2i inhibited TGF-beta1-induced HSP27 phosphorylation in serum-starved human keloid fibroblasts. In addition, 10 microM MK2i decreased TGF-beta1-induced expression of connective tissue growth factor and collagen type I within serum-starved keloid fibroblasts. Thus, MK2i represents a potential therapeutic for the treatment of fibrotic disorders.

5-Fluorouracil treatment of problematic scars

BACKGROUND

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

Gene expression profiling reveals alteration of caspase 6 and 14 transcripts in normal skin of keloid-prone patients

Excessive scar formation in keloids points to altered tissue modeling and repair mechanisms. Dysregulation of cytokine and apoptotic cascades and their downstream signaling pathways might have a role in keloid development. Total RNA was isolated from biopsied keloidal tissue and adjacent normal skin of black patients, white patient's scars, and normal skin of black and white patients, with normal wound healing. Apoptosis, cytokine and NFkB pathway microarrays were used to study and compare gene expression levels. Real-time PCR was used to verify microarray results in original samples and a separate, validation-set of samples. Significant differences were observed in the expression levels of members of caspase, cytokines and MAP kinase pathways, between the normal skin of keloid-prone and normal skin of keloid-resistant patients. Specifically, expression of caspase 6, and caspase 14 genes were different between normal skin of keloid-prone individuals and normal skin of keloid-resistant patients. Our results suggest that normal skin of keloid-prone individuals constitutively expresses a distinct gene profile which might contribute to their susceptibility to develop keloids.

Green tea polyphenol epigallocatechin-3-gallate suppresses collagen production and proliferation in keloid fibroblasts via inhibition of the STAT3-signaling pathway

Keloids are benign skin tumors characterized by collagen accumulation and hyperproliferation of fibroblasts. To find an effective therapy for keloids, we explored the pharmacological potential of (-)-epigallocatechin-3-gallate (EGCG), a widely investigated tumor-preventive agent. When applied to normal and keloid fibroblasts (KFs) in vitro, proliferation and migration of KFs were more strongly suppressed by EGCG than normal fibroblast proliferation and migration (IC(50): 54.4 microM (keloid fibroblast (KF)) versus 63.0 microM (NF)). The level of Smad2/3, signal transducer and activator of transcription-3 (STAT3), and p38 phosphorylation is more enhanced in KFs, and EGCG inhibited phosphorylation of phosphatidylinositol-3-kinase (PI3K), extracellular signal-regulated protein kinase 1/2 (ERK1/2), and STAT3 (Tyr705 and Ser727). To evaluate the contribution of these pathways to keloid pathology, we treated KFs with specific inhibitors for PI3K, ERK1/2, or STAT3. Although a PI3K inhibitor significantly suppressed proliferation, PI3K and MEK/ERK inhibitors had a minor effect on migration and collagen production. However, a JAK2/STAT3 inhibitor and a STAT3 siRNA strongly suppressed proliferation, migration, and collagen production by KFs. We also found that treatment with EGCG suppressed growth and collagen production in the in vivo keloid model. This study demonstrates that EGCG suppresses the pathological characteristics of keloids through inhibition of the STAT3-signaling pathway. We propose that EGCG has potential in the treatment and prevention of keloids.

Opposite regulation of transforming growth factors-beta2 and -beta3 expression in the human endometrium

TGF-betas have been reported to mediate the repression by progesterone of several matrix metalloproteinases in the human endometrium, thereby preventing menstrual breakdown. Because of conflicting reports on the expression profiles, source, and regulation of the TGF-beta system in this tissue, we investigated by real-time RT-PCR and ELISA the expression of the three TGF-betas (total and mature forms) and their two receptors throughout the menstrual cycle, and their regulation by ovarian steroids in cultured explants including their microdissected epithelial and stromal compartments. Regulation by cAMP and MAPK was further investigated. This comprehensive study on a large collection of endometrial samples evidenced a differential regulation of TGF-beta isoforms expression, both in vivo and in explant culture. In vivo, TGF-beta2 increased by about 5-fold at the mid-late secretory phase then declined after menstruation; TGF-beta3 increased at menstruation and remained high during the proliferative phase; TGF-beta1 was maximal at menstruation. In explants cultured without ovarian steroids both TGF-beta2 and -beta3 were preferentially expressed in the stroma. Ovarian steroids strongly repressed both TGF-beta2 and -beta3 in stroma but only TGF-beta2 in glands. cAMP prevented inhibition by ovarian steroids of TGF-beta2 but not -beta3. In presence of ovarian steroids, MAPK inhibitors (p38 and ERK pathways) stimulated TGF-beta3 but inhibited TGF-beta2 expression. In conclusion, TGF-beta2 and -beta3 are differentially expressed during the menstrual cycle and regulated by progesterone in epithelial vs stromal cells. The opposite regulation of TGF-beta2 and -beta3 by cAMP and MAPK could account for their distinct expression in vivo.

Use of organotypic coculture to study keloid biology

BACKGROUND

Keloids are pathologic scars afflicting a large segment of our population and for which there is no definitive therapy. The lack of an animal model for keloid formation has hampered study. We developed an in vitro organotypic skin model to simulate normal keloid biology, which may allow us to study keloid formation without an animal model.

METHODS

Normal (NFs) and keloid (KFs) human fibroblasts were cultured in a collagen matrix to create a 3-dimensional dermal structure. Normal human keratinocytes (NKs) were cultured as a second layer on top and exposed to an air-fluid interface to allow differentiation into a mature keratinocyte layer. The organotypic skin was maintained for 28 days in Dulbecco's modified eagle medium with 10% fetal calf serum. Samples were collected, processed, sectioned, stained with hematoxylin and eosin, and then measured for qualitative analysis. alpha-smooth-muscle actin was also evaluated by immunoblotting.

RESULTS

KF/NK organotypic skin showed increased collagen deposition, based on significantly denser collagen staining, with increased dermal thickness compared with NF/NK organotypic skin. We saw increased contracture in the KF/NK construct, and this correlated with increased organization of alpha-smooth-muscle actin fibers in the dermal layer of KF/NK organotypic skin compared with NF/NK skin.

CONCLUSIONS

We have shown that coculture of KFs with keloid keratinocytes leads to an increased collagen production and dermal contracture compared with NFs and NKs, consistent with known keloid behavior. Given the lack of an animal model, we believe that organotypic skin culture can serve as a surrogate to study keloid formation.

Induction of TIMP-1 and HSP47 synthesis in primary keloid fibroblasts by exogenous nitric oxide

BACKGROUND

The excessive accumulation of extracellular matrix is a hallmark of many fibrotic diseases, including the hypertrophic scar and keloid. Recent reports from this research team had shown that exogenous nitric oxide (NO) participates in the keloid formation; however, its role on the synthesis of fibrotic factor (TGF-beta1, TIMP-1 and HSP47) in the keloid fibroblasts (KF) remained unclear.

OBJECTIVE

In this study, to better define the potential effect of exogenous NO on the expression of fibrotic factors in KF, the enhancing effect of exogenous NO, released from a NO donor, on the synthesis of fibrotic factors in KF was investigated.

METHODS

The seven primary KF cultures were set up to measure the effect of exogenous NO on enhancing the expression of fibrotic factor.

RESULTS

Elevation of cellular cGMP levels was observed to be induced by NO or blocked by the hydrolysis activity of phosphodiesterase (PDE) by the PDE inhibitor. The elevated levels of cellular cGMP were noted to enhance the expression of TIMP-1 and HSP47 in KF. Exogenous NO was found to significantly accelerate the production of TIMP-1 and HSP47 in the seven primary KFs with a corresponding increase in the production of TGF-beta1.

CONCLUSION

The results have led to a conclusion, that is: the excess collagen formations in the keloid lesion may be attributed to the NO/cGMP signal pathway by initiating a rapid increase in the expression of TGF-beta1, TIMP-1 and HSP47 in the KF cells.

Exogenous nitric oxide stimulated collagen type I expression and TGF-beta1 production in keloid fibroblasts by a cGMP-dependent manner

Keloids arise from the aberrant wound healing process and nitric oxide (NO) plays an important role in the inflammation stage of wound healing. In order to better define the potential effect of NO/cGMP signal pathway in the keloid pathogenesis, the enhancing effect of exogenous NO (released from NO donor) on collagen expression in the keloid fibroblast (KF) as well as on the induction of collagen type I protein and TGF-beta1 expression in the KF were studied in this investigation. The DETA NONOate, an NO donor, was added to the KF, as the exogenous NO, to release NO in the culture medium. The expression of collagens was then determined by assaying the total soluble collagens and collagen type I in the KF. The cellular concentration of cGMP was measured by EIA in the KF. Exogenous NO was found to enhance the expression of collagens and elevate the cellular levels of cGMP. Moreover, to evaluate the effect of the elevated cellular cGMP levels on the expression of collagen and TGF-beta1, both cGMP and TGF-beta1 were measured by ELISA. The inhibitors for phosphodiesterase (PDE), such as IBMX (3-isobutyl-1-methylxanthine), Vinpocetine, EHNA, Milrinone and Zapriast, which have been reported to reduce the ability of PDE and subsequently produce an increase of cellular cGMP, induce the production of autocrine TGF-beta1 as well as the synthesis of collagen in the KF. In this investigation, the inhibition of the PDE enzyme activity was observed to enhance the effect on the collagen synthesis, and was induced by exogenous NO. Taken together, these results have suggested that the NO/cGMP pathway could positively influence the progression of keloid formation, via the TGF-beta1 expression in the KF.

Differential transcriptional responses of keloid and normal keratinocytes to serum stimulation

BACKGROUND

Keloids are benign tumors that occur only in response to injury, for which there is no effective treatment. We demonstrated previously that keloid keratinocytes (KKs) promote fibroblast proliferation more than normal keratinocytes (NKs) and that transforming growth factor (TGF)-beta is a component of that signal. We used the transcriptional response to serum stimulation to examine how TGF-beta expression is stimulated in KKs.

MATERIALS AND METHODS

Quiescent KKs and NKs were stimulated using serum; harvested using RNA at 0, 1, 6, 12, and 24 h; and analyzed using quantitative real-time polymerase chain reaction. TGF-beta activity in the conditioned medium was measured with an MLEC/PAI-luciferase assay. Inhibition of ERK1/2, p38 kinase, and JNK pathways was performed with PD98059, SB203580, and SP600125, respectively.

RESULTS

Increased transcription of TGF-beta2 occurs within 1 h of serum stimulation in KKs but not in NKs. In contrast, TGF-beta3 transcription was suppressed in KKs compared with NKs. No significant differences were observed in the transcriptional response of TGF-beta1. Increased TGF-beta2 mRNA correlated with increased TGF-beta biological activity in the conditioned medium. Inhibition of the ERK, p38 kinase or JNK signal transduction pathways blocked the transcriptional up-regulation of TGF-beta2, TbetaR1, and TbetaR2 in KKs.

CONCLUSIONS

KKs produce more TGF-beta2 mRNA than NKs in response to serum stimulation, resulting in increased TGF-beta activity in conditioned medium. Combining these results with our previous data lead us to propose a model of keloid formation characterized by an exaggerated response to cellular stress and abnormal epithelial-mesenchymal signaling promoting keloid formation.