Green tea extract and (-)-epigallocatechin-3-gallate inhibit mast cell-stimulated type I collagen expression in keloid fibroblasts via blocking PI-3K/AkT signaling pathways

Investigation of the Effect of Camellia Sinensis Essence Cream on Skin Burns

Background/Objective: Burn injuries are among the most common causes of trauma globally, affecting millions annually. Current treatments often rely on topical agents, but alternatives to synthetic formulations are increasingly sought due to safety and efficacy concerns. This study aimed to evaluate the therapeutic effects of a cream containing Camellia sinensis (white tea) extract on third-degree burn-induced skin lesions in a rat model. Methods: Thirty-two male Sprague-Dawley rats were randomized into four groups: control, Burn only, Burn + Camellia sinensis extract, and Burn + Camellia sinensis cream. Skin biopsies were evaluated using histopathological, immunohistochemical, and biochemical methods. Malondialdehyde (MDA) and glutathione (GSH) levels were measured to assess oxidative stress, while histological damage and immunoreactivity for collagen I, collagen III, NF-kβ/p65, TNF-alfa, 8-OhDG, and caspase-3 were analyzed. Results: The Camellia sinensis cream significantly reduced MDA levels and increased GSH levels compared to the burn-only group (p < 0.001). Histological analysis revealed enhanced epidermal regeneration and reduced dermal damage. The immunohistochemical findings demonstrated reduced NF-kβ/p65, TNF-alfa, 8-OhDG, caspase-3, collagen I, and collagen III immunopositivity in the cream-treated group (p < 0.001). Conclusions: Camellia sinensis cream demonstrated significant protective and reparative effects on burn-induced skin damage, suggesting its potential as a natural, effective, and safe alternative for burn management.

Epigallocatechin-3-Gallate Inhibits Atrial Fibrosis and Reduces the Occurrence and Maintenance of Atrial Fibrillation and its Possible Mechanisms

BACKGROUND

Atrial fibrosis is one of the main causes of the onset and recurrence of atrial fibrillation (AF), for which there is no effective treatment. The aim of this study was to investigate the effect and mechanism of epigallocatechin-3-gallate (EGCG) on AF in rats.

METHODS

The rat model of AF was established by rapid pacing induction after angiotensin-II (Ang-II) induced atrial fibrosis to verify the relationship between atrial fibrosis and the AF. The expression levels of TGF-β/Smad3 pathway molecules and lysyl oxidase (LOX) in AF were detected. Subsequently, EGCG was used to intervene Ang-II-induced atrial fibrosis to explore the role of EGCG in the treatment of AF and its inhibitory mechanism on fibrosis. It was further verified that EGCG inhibited the production of collagen and the expression of LOX through the TGF-β/Smad3 pathway at the cellular level.

RESULTS

The results showed that the induction rate and maintenance time of AF in rats increased with the increase of the degree of atrial fibrosis. Meanwhile, the expressions of Col I, Col III, molecules related to TGF-β/Smad3 pathway, and LOX increased significantly in the atrial tissues of rats in the Ang-II induced group. EGCG could reduce the occurrence and maintenance time of AF by inhibiting the degree of Ang-induced rat atrial fibrosis. Cell experiments confirmed that EGCG could reduce the synthesis of collagen and the expression of LOX in cardiac fibroblast induced by Ang-II. The possible mechanism is to down-regulate the expression of genes and proteins related to the TGF-β/Smad3 pathway.

CONCLUSION

EGCG could downregulate the expression levels of collagen and LOX by inhibiting the TGF-β/Smad3 signaling pathway, alleviating Ang-II-induced atrial fibrosis, which in turn inhibited the occurrence and curtailed the duration of AF.

Natural products for the treatment of hypertrophic scars: Preclinical and clinical studies

Hypertrophic scarring (HS) is a complication of wound healing that causes physiological and psychological distress in patients. However, the possible mechanism underlying HS is not fully understood, and there is no gold standard for its treatment. Natural products are more effective, economical, convenient, and safe than existing drugs, and they have a wide application prospect. However, there is a lack of literature on this topic, so we reviewed in vivo, in vitro, and clinical studies and screened natural products showing beneficial effects on HS that can become potential therapeutic agents for HS to fill in the gaps in the field. In addition, we discussed the drug delivery systems related to these natural products and their mechanisms in the treatment of HS. Generally speaking, natural products inhibit inflammation, myofibroblast activation, angiogenesis, and collagen accumulation by targeting interleukins, tumor necrosis factor-α, vascular endothelial growth factors, platelet-derived growth factors, and matrix metalloproteinases, so as to play an anti-HS effects of natural products are attributed to their anti-inflammatory, anti-proliferative, anti-angiogenesis, and pro-apoptotic (enhancing apoptosis and autophagy) roles, thus treating HS. We also screened the potential therapeutic targets of these natural compounds for HS through network pharmacology and constructed a protein-protein interaction (PPI) network, which may provide clues for the pharmacological mechanism of natural products in treating this disease and the development and application of drugs.

Comprehensive Insights into Keloid Pathogenesis and Advanced Therapeutic Strategies

Keloid scars, characterized by abnormal fibroproliferation and excessive extracellular matrix (ECM) production that extends beyond the original wound, often cause pruritus, pain, and hyperpigmentation, significantly impacting the quality of life. Keloid pathogenesis is multifactorial, involving genetic predisposition, immune response dysregulation, and aberrant wound-healing processes. Central molecular pathways such as TGF-β/Smad and JAK/STAT are important in keloid formation by sustaining fibroblast activation and ECM deposition. Conventional treatments, including surgical excision, radiation, laser therapies, and intralesional injections, yield variable success but are limited by high recurrence rates and potential adverse effects. Emerging therapies targeting specific immune pathways, small molecule inhibitors, RNA interference, and mesenchymal stem cells show promise in disrupting the underlying mechanisms of keloid pathogenesis, potentially offering more effective and lasting treatment outcomes. Despite advancements, further research is essential to fully elucidate the precise mechanisms of keloid formation and to develop targeted therapies. Ongoing clinical trials and research efforts are vital for translating these scientific insights into practical treatments that can markedly enhance the quality of life for individuals affected by keloid scars.

Pharmacotherapy for Keloids and Hypertrophic Scars

Keloids (KD) and hypertrophic scars (HTS), which are quite raised and pigmented and have increased vascularization and cellularity, are formed due to the impaired healing process of cutaneous injuries in some individuals having family history and genetic factors. These scars decrease the quality of life (QOL) of patients greatly, due to the pain, itching, contracture, cosmetic problems, and so on, depending on the location of the scars. Treatment/prevention that will satisfy patients' QOL is still under development. In this article, we review pharmacotherapy for treating KD and HTS, including the prevention of postsurgical recurrence (especially KD). Pharmacotherapy involves monotherapy using a single drug and combination pharmacotherapy using multiple drugs, where drugs are administered orally, topically and/or through intralesional injection. In addition, pharmacotherapy for KD/HTS is sometimes combined with surgical excision and/or with physical therapy such as cryotherapy, laser therapy, radiotherapy including brachytherapy, and silicone gel/sheeting. The results regarding the clinical effectiveness of each mono-pharmacotherapy for KD/HTS are not always consistent but rather scattered among researchers. Multimodal combination pharmacotherapy that targets multiple sites simultaneously is more effective than mono-pharmacotherapy. The literature was searched using PubMed, Google Scholar, and Online search engines.

Identification and validation of CRLF1 and NRG1 as immune-related signatures in hypertrophic scar

BACKGROUND

Hypertrophic scar (HTS) is a prevalent chronic inflammatory skin disorder characterized by abnormal proliferation and extracellular matrix deposition and the precise mechanisms underlying HTS remain elusive. This study aimed to identify and validate potential immune-related genes associated with hypertrophic scar formation.

METHODS

Skin samples from normal (n = 12) and hypertrophic scar tissues (n = 12) were subjected to RNA-seq analysis. Differentially expressed genes (DEGs) and significant modular genes in Weighted gene Co-expression Network Analysis (WGCNA) were identified. Subsequently, functional enrichment analysis was performed on the intersecting genes. Additionally, eight immune-related genes were matched from the ImmPort database. Validation of NRG1 and CRLF1 was carried out using an external cohort (GSE136906). Furthermore, the association between these two genes and immune cells was assessed by Spearman correlation analysis. Finally, RNA was extracted from normal and hypertrophic scar samples, and RT-qPCR, Immunohistochemistry staining and Western Blot were employed to validate the expression of characteristic genes.

RESULTS

A total of 940 DEGs were identified between HTS and normal samples, and 288 key module genes were uncovered via WGCNA. Enrichment analysis in key module revealed involvement in many immune-related pathways, such as Th17 cell differentiation, antigen processing and presentation and B cell receptor signaling pathway. The eight immune-related genes (IFI30, NR2F2, NRG1, ESM1, NFATC2, CRLF1, COLEC12 and IL6) were identified by matching from the ImmPort database. Notably, we observed that activated mast cell positively correlated with CRLF1 expression, while CD8 T cells exhibited a positive correlation with NRG1. The expression of NRG1 and CRLF1 was further validated in clinical samples.

CONCLUSION

In this study, two key immune-related genes (CRLF1 and NRG1) were identified as characteristic genes associated with HTS. These findings provide valuable insights into the immune-related mechanisms underlying hypertrophic scar formation.

Insights into How Plant-Derived Extracts and Compounds Can Help in the Prevention and Treatment of Keloid Disease: Established and Emerging Therapeutic Targets

Keloid is a disease in which fibroblasts abnormally proliferate and synthesize excessive amounts of extracellular matrix, including collagen and fibronectin, during the healing process of skin wounds, causing larger scars that exceed the boundaries of the original wound. Currently, surgical excision, cryotherapy, radiation, laser treatment, photodynamic therapy, pressure therapy, silicone gel sheeting, and pharmacotherapy are used alone or in combinations to treat this disease, but the outcomes are usually unsatisfactory. The purpose of this review is to examine whether natural products can help treat keloid disease. I introduce well-established therapeutic targets for this disease and various other emerging therapeutic targets that have been proposed based on the phenotypic difference between keloid-derived fibroblasts (KFs) and normal epidermal fibroblasts (NFs). We then present recent studies on the biological effects of various plant-derived extracts and compounds on KFs and NFs. Associated ex vivo, in vivo, and clinical studies are also presented. Finally, we discuss the mechanisms of action of the plant-derived extracts and compounds, the pros and cons, and the future tasks for natural product-based therapy for keloid disease, as compared with existing other therapies. Extracts of Astragalus membranaceus, Salvia miltiorrhiza, Aneilema keisak, Galla Chinensis, Lycium chinense, Physalis angulate, Allium sepa, and Camellia sinensis appear to modulate cell proliferation, migration, and/or extracellular matrix (ECM) production in KFs, supporting their therapeutic potential. Various phenolic compounds, terpenoids, alkaloids, and other plant-derived compounds could modulate different cell signaling pathways associated with the pathogenesis of keloids. For now, many studies are limited to in vitro experiments; additional research and development are needed to proceed to clinical trials. Many emerging therapeutic targets could accelerate the discovery of plant-derived substances for the prevention and treatment of keloid disease. I hope that this review will bridge past, present, and future research on this subject and provide insight into new therapeutic targets and pharmaceuticals, aiming for effective keloid treatment.

Evidence of Potential Natural Products for the Management of Hypertrophic Scars

Hypertrophic scarring is an aberrant wound-healing response to reestablish dermal integrity after an injury and can cause significant abnormalities in physical, aesthetic, functional, and psychological symptoms, impacting the patient's quality of life. There is currently no gold standard for preventing and treating hypertrophic scars. Therefore, many researchers have attempted to search for antihypertrophic scar agents with greater efficacy and fewer side effects. Natural therapeutics are becoming attractive as potential alternative anti-scarring agents because of their high efficacy, safety, biocompatibility, low cost, and easy accessibility. This review demonstrates various kinds of natural product-based therapeutics, including onion, vitamin E, Gotu kola, green tea, resveratrol, emodin, curcumin, and others, in terms of their mechanisms of action, evidence of efficacy and safety, advantages, and disadvantages when used as anti-scarring agents. We reviewed the literature based on data from in vitro, in vivo, and clinical trials. A total of 23 clinical trials were identified in this review; most clinical trials were ranked as having uncertain results (level of evidence 2b; n = 16). Although these natural products showed beneficial effects in both in vitro and in vivo studies of potential anti-scarring agents, there was limited clinical evidence to support their efficacy due to the limited quality of the studies, with individual flaws including small sample sizes, poor randomization, and blinding, and short follow-up durations. More robust and well-designed clinical trials with large-scale and prolonged follow-up durations are required to clarify the benefits and risks of these agents.

Identification of a potential bioinformatics-based biomarker in keloids and its correlation with immune infiltration

Keloid formation is a pathological consequence resulting from cutaneous irritation and injury, primarily attributed to excessive collagen matrix deposition and fibrous tissue proliferation. Chronic inflammation, left uncontrolled over an extended period, also stands as a substantial contributing factor. The precise mechanisms underlying keloid formation remain unclear. Therefore, this study aimed to identify key genes for diagnostic purposes. To achieve this, we used two Gene Expression Omnibus (GEO) data sets to identify differentially expressed genes. We identified one particular gene, homeobox C9 (HOXC9), using a thorough strategy involving two algorithms (least absolute shrinkage and selection operator and support vector machine-recursive feature elimination) and weighted gene co-expression network analysis. We then assessed its expression in normal and keloid tissues. In addition, we explored its temporal expression patterns via Mfuzz time clustering analysis. In our comprehensive analysis, we observed that immune infiltration, as well as cell proliferation, are crucial to keloid formation. Thus, we investigated immune cell infiltration in the keloid and normal groups, as well as the correlation between HOXC9 and these immune cells. It was found that HOXC9 was closely associated with the immune microenvironment of keloids. This shows that HOXC9 can serve as a potential biomarker and therapeutic target for keloids.

Therapeutic role of exosomes and conditioned medium in keloid and hypertrophic scar and possible mechanisms

Exosomes, ranging from 40 to 160 nm in diameter, are extracellular lipid bilayer microvesicles that regulate the body's physiological and pathological processes and are secreted by cells that contain proteins, nucleic acids, amino acids and other metabolites. Previous studies suggested that mesenchymal stem cell (MSC)-derived exosomes could either suppress or support keloid and hypertrophic scar progression. Although previous research has identified the potential value of MSC-exosomes in keloid and hypertrophic scar, a comprehensive analysis of different sources of MSC-exosome in keloid and hypertrophic scar is still lacking. This review mainly discusses different insights regarding the roles of MSC-exosomes in keloid and hypertrophic scar treatment and summarizes possible underlying mechanisms.

The PI3K-Akt-mTOR and Associated Signaling Pathways as Molecular Drivers of Immune-Mediated Inflammatory Skin Diseases: Update on Therapeutic Strategy Using Natural and Synthetic Compounds

The dysregulated phosphatidylinositol-3-kinase (PI3K)-Akt-mammalian target of rapamycin (mTOR) signaling pathway has been implicated in various immune-mediated inflammatory and hyperproliferative dermatoses such as acne, atopic dermatitis, alopecia, psoriasis, wounds, and vitiligo, and is associated with poor treatment outcomes. Improved comprehension of the consequences of the dysregulated PI3K/Akt/mTOR pathway in patients with inflammatory dermatoses has resulted in the development of novel therapeutic approaches. Nonetheless, more studies are necessary to validate the regulatory role of this pathway and to create more effective preventive and treatment methods for a wide range of inflammatory skin diseases. Several studies have revealed that certain natural products and synthetic compounds can obstruct the expression/activity of PI3K/Akt/mTOR, underscoring their potential in managing common and persistent skin inflammatory disorders. This review summarizes recent advances in understanding the role of the activated PI3K/Akt/mTOR pathway and associated components in immune-mediated inflammatory dermatoses and discusses the potential of bioactive natural products, synthetic scaffolds, and biologic agents in their prevention and treatment. However, further research is necessary to validate the regulatory role of this pathway and develop more effective therapies for inflammatory skin disorders.

Statins block mammalian target of rapamycin pathway: a possible novel therapeutic strategy for inflammatory, malignant and neurodegenerative diseases

Inflammation plays a critical role in several diseases such as cancer, gastric, heart and nervous system diseases. Data suggest that the activation of mammalian target of rapamycin (mTOR) pathway in epithelial cells leads to inflammation. Statins, the inhibitors of the 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA), seem to be able to inhibit the mTOR. Statins are considered to have favorable effects on inflammatory diseases by reducing the complications caused by inflammation and by regulating the inflammatory process and cytokines secretion. This critical review collected data on this topic from clinical, in vivo and in vitro studies published between 1998 and June 2022 in English from databases including PubMed, Google Scholar, Scopus, and Cochrane libraries.

EGCG inhibits hypertrophic scar formation in a rabbit ear model

OBJECTIVE

Hypertrophic scarring is a common skin fibro-proliferative disease, but currently there has no satisfactory drugs for anti-scar treatments. Previous study showed that epigallocatechin gallate (EGCG), the main catechin in green tea, improved wound healing and tissue fibrosis in both rats and mice. In the present study, the therapeutic effects of EGCG on hypertrophic scar were analyzed using a rabbit ear hypertrophic scar model.

MATERIALS

A rabbit ear model of hypertrophic scarring was used. DMSO, 0.5 mg EGCG/wound, 1.0 mg EGCG/wound or triamcinolone were injected subcutaneously once a week for 4 weeks. The scar elevation index (SEI) was measured using HE staining images, the collagen fibers were examined by Masson' trichrome staining images, and the number of capillaries in hypertrophic scar were calculated by CD31 staining images. The mRNA levels in the scar tissues were detected by quantitative real-time polymerase chain reaction (qRT-PCR).

RESULTS

Gross observation and histological evaluation showed the inhibitory effects of EGCG on hypertrophic scar formation at both doses, and decreased scar height and SEI were detected. EGCG also attenuated the mean collagen area fraction and decreased the number of capillaries in scar tissues. qRT-PCR revealed that EGCG significantly inhibited the mRNA expression of TGF-β1, Col I, Col III, α-SMA, and eNOS.

CONCLUSION

EGCG may serve as a useful candidate therapeutic drug for hypertrophic scar via inhibiting fibrotic gene expression and suppressing angiogenesis.

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.

Nanoencapsulation of Tea Catechins for Enhancing Skin Absorption and Therapeutic Efficacy

Tea catechins are a group of flavonoids that show many bioactivities. Catechins have been extensively reported as a potential treatment for skin disorders, including skin cancers, acne, photoaging, cutaneous wounds, scars, alopecia, psoriasis, atopic dermatitis, and microbial infection. In particular, there has been an increasing interest in the discovery of cosmetic applications using catechins as the active ingredient because of their antioxidant and anti-aging activities. However, active molecules with limited lipophilicity have difficulty penetrating the skin barrier, resulting in low bioavailability. Nevertheless, topical application is a convenient method for delivering catechins into the skin. Nanomedicine offers an opportunity to improve the delivery efficiency of tea catechins and related compounds. The advantages of catechin-loaded nanocarriers for topical application include high catechin loading efficiency, sustained or prolonged release, increased catechin stability, improved bioavailability, and enhanced accumulation or targeting to the nidus. Further, various types of nanoparticles, including liposomes, niosomes, micelles, lipid-based nanoparticles, polymeric nanoparticles, liquid crystalline nanoparticles, and nanocrystals, have been employed for topical catechin delivery. These nanoparticles can improve catechin permeation via close skin contact, increased skin hydration, skin structure disorganization, and follicular uptake. In this review, we describe the catechin skin delivery approaches based on nanomedicine for treating skin disorders. We also provide an in-depth description of how nanoparticles effectively improve the skin absorption of tea catechins and related compounds, such as caffeine. Furthermore, we summarize the possible future applications and the limitations of nanocarriers for topical delivery at the end of this review article.

Controlling Inflammation Pre-Emptively or at the Time of Cutaneous Injury Optimises Outcome of Skin Scarring

Inflammation plays an active role during the wound healing process. There is a direct association between the extent of injury as well as inflammation and the amount of subsequent cutaneous scarring. Evidence to date demonstrates that high levels of inflammation are associated with excessive dermal scarring and formation of abnormal pathological scars such as keloids and hypertrophic scars. In view of the multiple important cell types being involved in the inflammatory process and their influence on the extent of scar formation, many scar therapies should aim to target these cells in order to control inflammation and by association help improve scar outcome. However, most current treatment strategies for the management of a newly formed skin scar often adopt a watch-and-wait approach prior to commencing targeted anti-inflammatory therapy. Moreover, most of these therapies have been evaluated in the remodelling phase of wound healing and the evaluation of anti-inflammatory treatments at earlier stages of healing have not been fully explored and remain limited. Taken together, in order to minimise the risk of developing a poor scar outcome, it is clear that adopting an early intervention prior to skin injury would be optimal, however, the concept of pre-emptively priming the skin prior to injury has not yet been thoroughly evaluated. Therefore, the aim of this review was to evaluate the available literature regarding scar therapies that aim to target inflammation which are commenced prior to when a scar is formed or immediately after injury, with a particular focus on the role of pre-emptive priming of skin prior to injury in order to control inflammation for the prevention of poor scarring outcome.

Flavoring agent dihydrocoumarin alleviates IgE-mediated mast cell activation and allergic inflammation

Mast cells (MCs) are the main effector cells in the onset of high-affinity receptor for IgE (FcεRI)-mediated allergic diseases. The aim of this study was to test whether dihydrocoumarin (DHC), a food flavoring agent derived from Melilotus officinalis, can block IgE-induced MC activation effects and to examine the potential molecular mechanisms by which DHC affects MC activation. Rat basophilic leukemia cells (RBLs) and mouse bone marrow-derived mast cells (BMMCs) were sensitized with anti-dinitrophenol (DNP) immunoglobulin (Ig)E antibodies, stimulated with DNP-human serum albumin antigen, and treated with DHC. Western blot analyses were performed to detect the expression of signaling proteins. Murine IgE-mediated passive cutaneous anaphylaxis (PCA) and ovalbumin (OVA)-induced active systemic anaphylaxis (ASA) models were used to examine DHC effects on allergic reactions in vivo. DHC inhibited MC degranulation, as evidenced by reduced β-hexosaminidase activity and histamine levels, and reduced morphological changes associated with MC activation, namely cellular elongation and F-actin reorganization. DHC inhibited the activation of MAPK, NF-κB, and AP-1 pathways in IgE-activated MCs. Additionally, DHC could attenuate IgE/Ag-induced allergic reactions (dye extravasation and ear thickening) in PCA as well as OVA challenge-induced reactions in ASA mice (body temperature, serum histamine and IL-4 secretion changes). In conclusion, DHC suppressed MC activation. DHC may represent a new MC-suppressing treatment strategy for the treatment of IgE-mediated allergic diseases.

Single-Cell Sequencing Analysis and Weighted Co-Expression Network Analysis Based on Public Databases Identified That TNC Is a Novel Biomarker for Keloid

Background

The pathophysiology of keloid formation is not yet understood, so the identification of biomarkers for kelod can be one step towards designing new targeting therapies which will improve outcomes for patients with keloids or at risk of developing keloids.

Methods

In this study, we performed single-cell RNA sequencing analysis, weighted co-expression network analysis, and differential expression analysis of keloids based on public databases. And 3 RNA sequencing data from keloid patients in our center were used for validation. Besides, we performed QRT-PCR on keloid tissue and adjacent normal tissues from 16 patients for further verification.

Results

We identified the sensitive biomarker of keloid: Tenascin-C (TNC). Then, Pseudotime analysis found that the expression level of TNC decreased first, then stabilized and finally increased with fibroblast differentiation, suggesting that TNC may play an potential role in fibroblast differentiation. In addition, there were differences in the infiltration level of macrophages M0 between the TNC-high group and the TNC-low group. Macrophages M0 had a higher infiltration level in low TNC- group (P<0.05).

Conclusion

Our results can provide a new idea for the diagnosis and treatment of keloid.

PPAR-gamma agonists: Potential modulators of autophagy in obesity

Autophagy pathways are involved in the pathogenesis of some obesity related health problems. As obesity is a nutrient sufficiency condition, autophagy process can be altered in obesity through AMP activated protein kinase (AMPK) inhibition. Peroxisome proliferator-activated receptor-gamma (PPAR-gamma) as the main modulator of adipogenesis process can be effective in the regulation of obesity related phenotypes. As well, it has been revealed that PPAR-gamma and its agonists can regulate autophagy in different normal or cancer cells. However, their effects on autophagy modulation in obesity have been investigated in the limited number of studies. In the current comprehensive mechanistic review, we aimed to investigate the possible mechanisms of action of PPAR-gamma on the process of autophagy in obesity through narrating the effects of PPAR-gamma on autophagy in the non-obesity conditions. Moreover, mode of action of PPAR-gamma agonists on autophagy related implications comprehensively reviewed in the various studies. Understanding the different effects of PPAR-gamma agonists on autophagy in obesity can help to develop a new approach to management of obesity.

Beneficial Effects of Green Tea EGCG on Skin Wound Healing: A Comprehensive Review

Epigallocatechin gallate (EGCG) is associated with various health benefits. In this review, we searched current work about the effects of EGCG and its wound dressings on skin for wound healing. Hydrogels, nanoparticles, micro/nanofiber networks and microneedles are the major types of EGCG-containing wound dressings. The beneficial effects of EGCG and its wound dressings at different stages of skin wound healing (hemostasis, inflammation, proliferation and tissue remodeling) were summarized based on the underlying mechanisms of antioxidant, anti-inflammatory, antimicrobial, angiogenesis and antifibrotic properties. This review expatiates on the rationale of using EGCG to promote skin wound healing and prevent scar formation, which provides a future clinical application direction of EGCG.

Pre-Emptive Priming of Human Skin Improves Cutaneous Scarring and Is Superior to Immediate and Delayed Topical Anti-Scarring Treatment Post-Wounding: A Double-Blind Randomised Placebo-Controlled Clinical Trial

The concept of pre-emptive priming of skin pre-surgery offers a novel approach in optimizing cutaneous scarring outcome. We previously showed an anti-scarring topical (epigallocatechin-3-gallate (EGCG)) is effective in improving skin scarring when applied post-surgery. The objective was to deliver an active compound at the optimal time in order to maximize its impact and improve cutaneous scarring. Therefore, pre-emptive application of anti-scarring topical pre-surgery compared with post-surgery can potentially be superior on scarring outcome. This double-blinded randomized placebo-controlled trial compares the effects of pre-emptive priming of skin with an anti-scarring topical pre-surgery versus post-surgery. Healthy volunteers (n = 40) were split into 4-groups; each undergoing different modes of application versus placebo: Group-1 = priming (7Days) pre-injury, Group-2 = priming (3D) pre-injury, Group-3 = immediate (0D) day-of-injury, Group-4 = delayed application (14D) post-injury. Excisional skin-biopsies in upper-arms were evaluated weekly with multiple quantitative devices over 8-weeks. Histological, immunohistochemical, mRNA sequencing and QRT-PCR studies were performed on tissue-biopsies. EGCG reduced mast cells at weeks-4 and 8 by gene and protein analyses (p < 0.01). Group 1 was superior to other groups (p < 0.01) in both clinical (blood flow) and laboratory parameters (elastin and immune marker expression). Additionally, there was down-regulation of angiogenic-markers by mRNA-sequencing and of CD31 and VEGF-A at weeks-4 and 8 (p < 0.01) by immunohistochemistry and at week-4 (p < 0.05) by QRT-PCR. EGCG increased antioxidant levels (HO-1) at week-4 (p < 0.01) plus elastin at week-8 (p < 0.01). In conclusion, pre-emptive priming of skin pre-injury has significant beneficial effects on surgically induced skin scarring shown by reducing mast cells, blood flow and angiogenesis plus increasing elastin content. This clinical trial was registered with ISRCTN (ISRCTN70155584).

Pre-Emptive Priming of Human Skin Improves Cutaneous Scarring and Is Superior to Immediate and Delayed Topical Anti-Scarring Treatment Post-Wounding: A Double-Blind Randomised Placebo-Controlled Clinical Trial

The concept of pre-emptive priming of skin pre-surgery offers a novel approach in optimizing cutaneous scarring outcome. We previously showed an anti-scarring topical (epigallocatechin-3-gallate (EGCG)) is effective in improving skin scarring when applied post-surgery. The objective was to deliver an active compound at the optimal time in order to maximize its impact and improve cutaneous scarring. Therefore, pre-emptive application of anti-scarring topical pre-surgery compared with post-surgery can potentially be superior on scarring outcome. This double-blinded randomized placebo-controlled trial compares the effects of pre-emptive priming of skin with an anti-scarring topical pre-surgery versus post-surgery. Healthy volunteers (n = 40) were split into 4-groups; each undergoing different modes of application versus placebo: Group-1 = priming (7Days) pre-injury, Group-2 = priming (3D) pre-injury, Group-3 = immediate (0D) day-of-injury, Group-4 = delayed application (14D) post-injury. Excisional skin-biopsies in upper-arms were evaluated weekly with multiple quantitative devices over 8-weeks. Histological, immunohistochemical, mRNA sequencing and QRT-PCR studies were performed on tissue-biopsies. EGCG reduced mast cells at weeks-4 and 8 by gene and protein analyses (p < 0.01). Group 1 was superior to other groups (p < 0.01) in both clinical (blood flow) and laboratory parameters (elastin and immune marker expression). Additionally, there was down-regulation of angiogenic-markers by mRNA-sequencing and of CD31 and VEGF-A at weeks-4 and 8 (p < 0.01) by immunohistochemistry and at week-4 (p < 0.05) by QRT-PCR. EGCG increased antioxidant levels (HO-1) at week-4 (p < 0.01) plus elastin at week-8 (p < 0.01). In conclusion, pre-emptive priming of skin pre-injury has significant beneficial effects on surgically induced skin scarring shown by reducing mast cells, blood flow and angiogenesis plus increasing elastin content. This clinical trial was registered with ISRCTN (ISRCTN70155584).

A Review of the Evidence for and against a Role for Mast Cells in Cutaneous Scarring and Fibrosis

Scars are generated in mature skin as a result of the normal repair process, but the replacement of normal tissue with scar tissue can lead to biomechanical and functional deficiencies in the skin as well as psychological and social issues for patients that negatively affect quality of life. Abnormal scars, such as hypertrophic scars and keloids, and cutaneous fibrosis that develops in diseases such as systemic sclerosis and graft-versus-host disease can be even more challenging for patients. There is a large body of literature suggesting that inflammation promotes the deposition of scar tissue by fibroblasts. Mast cells represent one inflammatory cell type in particular that has been implicated in skin scarring and fibrosis. Most published studies in this area support a pro-fibrotic role for mast cells in the skin, as many mast cell-derived mediators stimulate fibroblast activity and studies generally indicate higher numbers of mast cells and/or mast cell activation in scars and fibrotic skin. However, some studies in mast cell-deficient mice have suggested that these cells may not play a critical role in cutaneous scarring/fibrosis. Here, we will review the data for and against mast cells as key regulators of skin fibrosis and discuss scientific gaps in the field.

The Roles of Inflammation in Keloid and Hypertrophic Scars

The underlying mechanisms of wound healing are complex but inflammation is one of the determining factors. Besides its traditional role in combating against infection upon injury, the characteristics and magnitude of inflammation have dramatic impacts on the pathogenesis of scar. Keloids and hypertrophic scars are pathological scars that result from aberrant wound healing. They are characterized by continuous local inflammation and excessive collagen deposition. In this review, we aim at discussing how dysregulated inflammation contributes to the pathogenesis of scar formation. Immune cells, soluble inflammatory mediators, and the related intracellular signal transduction pathways are our three subtopics encompassing the events occurring in inflammation associated with scar formation. In the end, we enumerate the current and potential medicines and therapeutics for suppressing inflammation and limiting progression to scar. Understanding the initiation, progression, and resolution of inflammation will provide insights into the mechanisms of scar formation and is useful for developing effective treatments.

Inflammation as an orchestrator of cutaneous scar formation: a review of the literature

Inflammation is a key phase in the cutaneous wound repair process. The activation of inflammatory cells is critical for preventing infection in contaminated wounds and results in the release of an array of mediators, some of which stimulate the activity of keratinocytes, endothelial cells, and fibroblasts to aid in the repair process. However, there is an abundance of data suggesting that the strength of the inflammatory response early in the healing process correlates directly with the amount of scar tissue that will eventually form. This review will summarize the literature related to inflammation and cutaneous scar formation, highlight recent discoveries, and discuss potential treatment modalities that target inflammation to minimize scarring.

Mast Cells in Skin Scarring: A Review of Animal and Human Research

Mast cells (MCs) are an important immune cell type in the skin and play an active role during wound healing. MCs produce mediators that can enhance acute inflammation, stimulate re-epithelialisation as well as angiogenesis, and promote skin scarring. There is also a link between MCs and abnormal pathological cutaneous scarring, with increased numbers of MCs found in hypertrophic scars and keloid disease. However, there has been conflicting data regarding the specific role of MCs in scar formation in both animal and human studies. Whilst animal studies have proved to be valuable in studying the MC phenomenon in wound healing, the appropriate translation of these findings to cutaneous wound healing and scar formation in human subjects remains crucial to elucidate the role of these cells and target treatment effectively. Therefore, this perspective paper will focus on evaluation of the current evidence for the role of MCs in skin scarring in both animals and humans in order to identify common themes and future areas for translational research.

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.

Pleiotropic Biological Effects of Dietary Phenolic Compounds and their Metabolites on Energy Metabolism, Inflammation and Aging

Dietary phenolic compounds are considered as bioactive compounds that have effects in different chronic disorders related to oxidative stress, inflammation process, or aging. These compounds, coming from a wide range of natural sources, have shown a pleiotropic behavior on key proteins that act as regulators. In this sense, this review aims to compile information on the effect exerted by the phenolic compounds and their metabolites on the main metabolic pathways involved in energy metabolism, inflammatory response, aging and their relationship with the biological properties reported in high prevalence chronic diseases. Numerous in vitro and in vivo studies have demonstrated their pleiotropic molecular mechanisms of action and these findings raise the possibility that phenolic compounds have a wide variety of roles in different targets.

Long non-coding RNA HOXA11-AS accelerates the progression of keloid formation via miR-124-3p/TGFβR1 axis

Emerging evidence reveals the importance of long non-coding RNAs (lncRNAs) in the development and progression of keloid formation, whereas the underlying mechanisms are not well understood. In the present study, we investigated the biological effects and molecular mechanisms of lncRNA HOXA11-AS in keloid formation. First, the expression levels of HOXA11-AS, miR-124-3p, and transforming growth factor β receptor type I (TGFβR1) were measured in both keloid tissues and human keloid fibroblasts (HKFs) using qRT-PCR and western blot analysis, respectively. Next, we adopted both gain- and loss-of-function strategies to explore the significance of HOXA11-AS. TUNEL, flow cytometry, DNA ladder, and tube formation assays were performed to measure cell apoptosis and angiogenesis, respectively. Besides, the potential binding relationship between HOXA11-AS and miR-124-3p, as well as miR-124-3p and TGFβR1 was identified using bioinformatic screening and verified by luciferase reporter assay. Furthermore, we explored the importance of miR-124-3p in HOXA11-AS-induced phenotypes and regulations on TGFβ signaling or PI3K/Akt signaling. We found that HOXA11-AS and TGFβR1 were significantly up-regulated, while miR-124-3p was down-regulated both in keloid tissues or fibroblasts than in normal skin tissues or fibroblasts. Functionally, high expression of HOXA11-AS essentially inhibited cell apoptosis and promoted fibroblast-induced angiogenesis. Mechanistically, miR-124-3p was identified as a downstream effector to be involved in HOXA11-AS-mediated phenotypes through directly targeting TGFβR1, thus modulating PI3K/Akt signaling pathway. Taken together, our findings revealed that HOXA11-AS inhibits cell apoptosis and promotes angiogenesis through miR-124-3p/TGFβR1 axis, contributing to the progression of keloid formation, which might provide a novel target for keloid therapy.

Monocytes co-cultured with reconstructed keloid and normal skin models skew towards M2 macrophage phenotype

Several abnormalities have been reported in the peripheral blood mononuclear cells of keloid-forming patients and particularly in the monocyte cell fraction. The goal of this in vitro study was to determine whether monocytes from keloid-prone patients contribute to the keloid phenotype in early developing keloids, and whether monocyte differentiation is affected by the keloid microenvironment. Therefore, keloid-derived keratinocytes and fibroblasts were used to reconstruct a full thickness, human, in vitro keloid scar model. The reconstructed keloid was co-cultured with monocytes from keloid-forming patients and compared to reconstructed normal skin co-cultured with monocytes from non-keloid-formers. The reconstructed keloid showed increased contraction, dermal thickness (trend) and α-SMA+ staining, but co-culture with monocytes did not further enhance the keloid phenotype. After 2-week culture, all monocytes switched from a CD11c^high/CD14^high/CD68^low to a CD11c^high/CD14^low/CD68^high phenotype. However, only monocytes co-cultured with either reconstructed keloid scar or normal skin models skewed towards the more fibrotic M2-macrophage phenotype. There was negligible fibroblast and fibrocyte differentiation in mono- and co-cultured monocytes. These results indicate that monocytes differentiate into M2 macrophages when in the vicinity of early regenerating and repairing tissue, independent of whether the individual is prone to normal or keloid scar formation.

The anti-fibrotic role of mast cells in the liver is mediated by HLA-G and interaction with hepatic stellate cells

BACKGROUND & AIMS

We have reported a significant association between HLA-G expression or the number of hepatic mast cells and liver fibrosis. Here, we investigated the role of HLA-G and mast cells in liver fibrosis, focusing, in particular, on interactions between human mast and stellate cells.

METHODS

Human mast cells (HMC cell line, CD34-derived mast cells, or tissue-derived mast cells) were co-cultured with purified human hepatic stellate cells (HSCs), and collagen I production by HSCs was evaluated. Mast cells and HSCs were characterized by immunocytochemistry. Various conditions were tested: different times in direct or indirect contact, presence or absence of cytokines, addition or not of HLA-G, and presence or absence of specific protease inhibitors.

RESULTS

The reciprocal interaction between HSCs and mast cells led to the attraction of mast cells to HSCs in vivo and in vitro, and to a significant decrease in collagen production, at all times of co-culture, following the direct or indirect contact of mast cells with HSCs alone or in the presence of TGF-β, IFN-α or IL-10. We identified the diffusible factors involved in collagen I degradation as mast cell proteases. Moreover, HLA-G expression increased during the co-culture of HSCs and mast cells, with HLA-G acting on both mast cells and HSCs, to enhance collagen I degradation.

CONCLUSIONS

Mast cells play a beneficial, anti-fibrotic role in liver fibrosis, via the HLA-G-mediated decrease of collagen I. These findings are consistent with high levels of cross-communication between mast cells and hepatic stellate cells and the role of HLA-G.

Targeting mTORC1/2 with OSI-027 inhibits proliferation and migration of keloid keratinocytes

Keloid is a dermal proliferative disorder characterized by the excessive proliferation and migration of keratinocytes and fibroblasts. Over-activation of the serine/threonine protein kinase, mammalian target of rapamycin (mTOR), plays a pivotal role in the process. Here, we show that both mTOR complex 1 (mTORC1) and mTOR complex 2 (mTORC2) were hyper-activated in keloid-derived primary keratinocytes. Further, OSI-027, an mTOR kinase inhibitor, potently inhibited proliferation and migration of keloid keratinocytes. At the molecular level, OSI-027 disrupted the assembly of mTORC1 (mTOR-Raptor) and mTORC2 (mTOR-Rictor-mLST8). Further, OSI-027 almost completely blocked the phosphorylation of the mTORC1 substrates, S6K1, S6 and 4EBP1, and the mTORC2 substrate, AKT, at Ser-473. The OSI-027 treatment of keloid keratinocytes showed more effectively inhibited cell proliferation and migration compared to the mTORC1 inhibitor, rapamycin. Moreover, restoring mTORC1 activation by the introduction of the constitutively active S6K1 only partly alleviated OSI-027-induced inhibition of keloid keratinocytes. Notably, mTOR2 inhibition by Rictor siRNAs also inhibited keloid keratinocyte proliferation and migration, but less efficiently than OSI-027. Together, our results imply that concurrent targeting of mTORC1/2 by OSI-027 potently inhibits the proliferation and the migration of keloid keratinocytes. Thus, OSI-027 may have translational value for the treatment of keloid.

Long non-coding RNA expression profiling in the lesional tissue and derived fibroblasts of keloid

Introduction

Long non-coding RNA (lncRNA) plays a key role in various disorders. However, its role in keloid is still unclear.

Aim

We explored differentially expressed (DE) lncRNAs and mRNAs between keloid tissue (KT)s and normal tissue (NT)s, as well as keloid fibroblast (KFB)s and normal fibroblast (NFB)s, respectively.

Material and methods

We use KTs and NTs from the chest of 5 patients, and 3 pairs of KFBs and NFBs, to perform microarray respectively. Gene ontology and pathway analyses were conducted by online software DAVID (Database for Annotation, Visualization and Integrated Discovery). The validation of targeted lncRNAs were conducted by qRT-PCR in enlarged samples (79 KTs and 21 NTs).

Results

We identified 3680 DE-lncRNAs in tissue essay, and 1231 DE-lncRNAs in cell essay. Furthermore, we found that many lncRNAs and their relative mRNAs were regulated simultaneously in keloid. We identified that ENST00000439703 and uc003jox.1 were up-regulated in both of the above essays through comparing the results of lncRNA screening between tissue essay and cell essay; the results were confirmed through qRT-PCR in enlarged samples.

Conclusions

Our study demonstrates that numerous lncRNAs are involved in the pathogenesis and development of the keloid.

A system to identify inhibitors of mTOR signaling using high-resolution growth analysis in Saccharomyces cerevisiae

The mechanistic target of rapamycin (mTOR) is a central regulator of growth and proliferation and mTOR inhibition is a promising therapy for a variety of diseases and disorders. Inhibition of mTOR complex I (mTORC1) with rapamycin delays aging and increases healthy longevity in laboratory animals and is used clinically at high doses to prevent organ transplant rejection and to treat some forms of cancer. Clinical use of rapamycin is associated with several unwanted side effects, however, and several strategies are being taken to identify mTORC1 inhibitors with fewer side effects. We describe here a yeast-based growth assay that can be used to screen for novel inhibitors of mTORC1. By testing compounds using a wild-type strain and isogenic cells lacking either TOR1 or FPR1, we can resolve not only whether a compound is an inhibitor of mTORC1 but also whether the inhibitor acts through a mechanism similar to rapamycin by binding Fpr1. Using this assay, we show that rapamycin derivatives behave similarly to rapamycin, while caffeine and the ATP competitive inhibitors Torin 1 and GSK2126458 are mTORC1 inhibitors in yeast that act independently of Fpr1. Some mTOR inhibitors in mammalian cells do not inhibit mTORC1 in yeast, and several nutraceutical compounds were not found to specifically inhibit mTOR but resulted in a general inhibition of yeast growth. Our screening method holds promise as a means of effectively assaying drug libraries for mTOR-inhibitory molecules in vivo that may be adapted as novel treatments to fight diseases and extend healthy longevity.

Camellia sinensis increased apoptosis on U2OS osteosarcoma cells and wound healing potential on NIH3T3 fibroblast cells

Camellia sinensis (Cs) is a plant which is rich in polyphenols and has antioxidant, antiinflammatory, antimutagenic, anticarcinogenic and antibacterial activities. In this study, two different methanol extracts (Cs-I and Cs-II) were prepared from the leaf of C. sinensis in order to investigate the wound healing and anticancer activities. Total phenolic content and antioxidant activity of the extracts were determined. Wound healing effects of Cs extracts were evaluated by using Masson's Trichrome Tecnique on NIH3T3 fibroblast cells. Cytotoxic and apoptotic effects of the extracts were determined by MTT and AnnexinV-PI assays on U2OS osteosarcoma cells. Total phenolic contents and antioxidant activities of the extracts were almost the same. The highest concentration (60 µg/mL) of the extracts showed significant cytotoxic and apoptotic effects on U2OS cells. Especially, the highest apoptotic effect was determined with 60 µg/mL Cs-I extract. Significant wound healing potential on NIH3T3 fibroblast cells were determined especially with low extract concentrations (0.5, 1 and 5 µg/mL), while high extract concentrations showed significant anticancer effects. As a result, two Cs leaf extracts exhibited important apoptotic properties and both have wound healing potential. However, the Cs-I extract was found more effective on apoptotic osteosarcoma cell death and has an increased wound healing potential than the Cs-II extract.

Functional testing of topical skin formulations using an optimised ex vivo skin organ culture model

A number of equivalent-skin models are available for investigation of the ex vivo effect of topical application of drugs and cosmaceuticals onto skin, however many have their drawbacks. With the March 2013 ban on animal models for cosmetic testing of products or ingredients for sale in the EU, their utility for testing toxicity and effect on skin becomes more relevant. The aim of this study was to demonstrate proof of principle that altered expression of key gene and protein markers could be quantified in an optimised whole tissue biopsy culture model. Topical formulations containing green tea catechins (GTC) were investigated in a skin biopsy culture model (n = 11). Punch biopsies were harvested at 3, 7 and 10 days, and analysed using qRT-PCR, histology and HPLC to determine gene and protein expression, and transdermal delivery of compounds of interest. Reduced gene expression of α-SMA, fibronectin, mast cell tryptase, mast cell chymase, TGF-β1, CTGF and PAI-1 was observed after 7 and 10 days compared with treated controls (p < 0.05). Histological analysis indicated a reduction in mast cell tryptase and chymase positive cell numbers in treated biopsies compared with untreated controls at day 7 and day 10 (p < 0.05). Determination of transdermal uptake indicated that GTCs were detected in the biopsies. This model could be adapted to study a range of different topical formulations in both normal and diseased skin, negating the requirement for animal models in this context, prior to study in a clinical trial environment.

Impaired wound healing results from the dysfunction of the Akt/mTOR pathway in diabetic rats

BACKGROUND

Wound healing is impaired in diabetes mellitus. The underlying mechanism involved in this process is still unknown. The Akt/mTOR signaling pathway plays a crucial role in the pathogenesis of diabetes.

OBJECTIVE

we investigated the role of the Akt/mTOR pathway in diabetic wounds and the mechanisms that growth factors activate this pathway to promote diabetic wound healing.

METHODS

Full-thickness skin excisional wounds were created on the backs of normal and streptozotocin-induced diabetic rats. The expression of key proteins in the Akt/mTOR pathway was assayed using western blotting; topical effects of granulocyte-macrophage colony stimulating factor (GM-CSF) on diabetic wounds and activation of the Akt/mTOR pathway were subsequently investigated. Activation of the Akt/mTOR pathway by GM-SCF in vitro was examined in rat primary fibroblasts.

RESULTS

The results indicate that the Akt/mTOR pathway was activated in the wound tissue of both non-diabetic and diabetic rats, as indicated by a remarkable increase in expression of total and phosphorylated key proteins in this pathway. However, the expression level of these proteins was dramatically attenuated in diabetic wounds compared with non-diabetic wounds. Upon topical application of GM-CSF, the diabetic wound healing was remarkably improved concomitantly with increased expression and phosphorylation of key proteins in the Akt/mTOR pathway. In addition, rat fibroblast proliferation induced by GM-CSF depended on the Akt/mTOR pathway activation.

CONCLUSION

Impaired wound healing results from the dysfunction of the Akt/mTOR pathway in diabetic rats. The pharmacologic elevation of this pathway may represent an attractive intervention strategy to improve prognosis of diabetic wounds.

Silymarin Suppresses Cellular Inflammation By Inducing Reparative Stress Signaling

Silymarin, a characterized extract of the seeds of milk thistle (Silybum marianum), suppresses cellular inflammation. To define how this occurs, transcriptional profiling, metabolomics, and signaling studies were performed in human liver and T cell lines. Cellular stress and metabolic pathways were modulated within 4 h of silymarin treatment: activation of Activating Transcription Factor 4 (ATF-4) and adenosine monophosphate protein kinase (AMPK) and inhibition of mammalian target of rapamycin (mTOR) signaling, the latter being associated with induction of DNA-damage-inducible transcript 4 (DDIT4). Metabolomics analyses revealed silymarin suppression of glycolytic, tricarboxylic acid (TCA) cycle, and amino acid metabolism. Anti-inflammatory effects arose with prolonged (i.e., 24 h) silymarin exposure, with suppression of multiple pro-inflammatory mRNAs and signaling pathways including nuclear factor kappa B (NF-κB) and forkhead box O (FOXO). Studies with murine knock out cells revealed that silymarin inhibition of both mTOR and NF-κB was partially AMPK dependent, whereas silymarin inhibition of mTOR required DDIT4. Other natural products induced similar stress responses, which correlated with their ability to suppress inflammation. Thus, natural products activate stress and repair responses that culminate in an anti-inflammatory cellular phenotype. Natural products like silymarin may be useful as tools to define how metabolic, stress, and repair pathways regulate cellular inflammation.

Autologous Graft Thickness Affects Scar Contraction and Quality in a Porcine Excisional Wound Model

BACKGROUND

Texture, color, and durability are important characteristics to consider for skin replacement in conspicuous and/or mobile regions of the body such as the face, neck, and hands. Although autograft thickness is a known determinant of skin quality, few studies have correlated the subjective and objective characters of skin graft healing with their associated morphologic and cellular profiles. Defining these relationships may help guide development and evaluation of future skin replacement strategies.

METHODS

Six-centimeter-diameter full-thickness wounds were created on the back of female Yorkshire pigs and covered by autografts of variable thicknesses. Skin quality was assessed on day 120 using an observer scar assessment score and objective determinations for scar contraction, erythema, pigmentation, and surface irregularities. Histological, histochemical, and immunohistochemical assessments were performed.

RESULTS

Thick grafts demonstrated lower observer scar assessment score (better quality) and decreased erythema, pigmentation, and surface irregularities. Histologically, thin grafts resulted in scar-like collagen proliferation while thick grafts preserves the dermal architecture. Increased vascularity and prolonged and increased cellular infiltration were observed among thin grafts. In addition, thin grafts contained predominately dense collagen fibers, whereas thick grafts had loosely arranged collagen. α-Smooth muscle actin staining for myofibroblasts was observed earlier and persisted longer among thinner grafts.

CONCLUSIONS

Graft thickness is an important determinant of skin quality. High-quality skin replacements are associated with preserved collagen architecture, decreased neovascularization, and decreased inflammatory cellular infiltration. This model, using autologous skin as a metric of quality, may give a more informative analysis of emerging skin replacement strategies.

A comprehensive evidence-based review on the role of topicals and dressings in the management of skin scarring

Wound healing after dermal injury is an imperfect process, inevitably leading to scar formation as the skin re-establishes its integrity. The resulting scars have different characteristics to normal skin, ranging from fine-line asymptomatic scars to problematic scarring including hypertrophic and keloid scars. Scars appear as a different colour to the surrounding skin and can be flat, stretched, depressed or raised, manifesting a range of symptoms including inflammation, erythema, dryness and pruritus, which can result in significant psychosocial impact on patients and their quality of life. In this paper, a comprehensive literature review coupled with an analysis of levels of evidence (LOE) for each published treatment type was conducted. Topical treatments identified include imiquimod, mitomycin C and plant extracts such as onion extract, green tea, Aloe vera, vitamin E and D, applied to healing wounds, mature scar tissue or fibrotic scars following revision surgery, or in combination with other more established treatments such as steroid injections and silicone. In total, 39 articles were included, involving 1703 patients. There was limited clinical evidence to support their efficacy; the majority of articles (n = 23) were ranked as category 4 LOE, being of limited quality with individual flaws, including low patient numbers, poor randomisation, blinding, and short follow-up periods. As trials were performed in different settings, they were difficult to compare. In conclusion, there is an unmet clinical need for effective solutions to skin scarring, more robust long-term randomised trials and a consensus on a standardised treatment regime to address all aspects of scarring.

The mTOR signalling pathway in cancer and the potential mTOR inhibitory activities of natural phytochemicals

The mammalian target of rapamycin (mTOR) kinase plays an important role in regulating cell growth and cell cycle progression in response to cellular signals. It is a key regulator of cell proliferation and many upstream activators and downstream effectors of mTOR are known to be deregulated in various types of cancers. Since the mTOR signalling pathway is commonly activated in human cancers, many researchers are actively developing inhibitors that target key components in the pathway and some of these drugs are already on the market. Numerous preclinical investigations have also suggested that some herbs and natural phytochemicals, such as curcumin, resveratrol, timosaponin III, gallic acid, diosgenin, pomegranate, epigallocatechin gallate (EGCC), genistein and 3,3'-diindolylmethane inhibit the mTOR pathway either directly or indirectly. Some of these natural compounds are also in the clinical trial stage. In this review, the potential anti-cancer and chemopreventive activities and the current status of clinical trials of these phytochemicals are discussed.