Azelaic acid reduced senescence-like phenotype in photo-irradiated human dermal fibroblasts: possible implication of PPARγ

New Insights into the Role of PPARγ in Skin Physiopathology

Peroxisome proliferator-activated receptor gamma (PPARγ) is a transcription factor expressed in many tissues, including skin, where it is essential for maintaining skin barrier permeability, regulating cell proliferation/differentiation, and modulating antioxidant and inflammatory responses upon ligand binding. Therefore, PPARγ activation has important implications for skin homeostasis. Over the past 20 years, with increasing interest in the role of PPARs in skin physiopathology, considerable effort has been devoted to the development of PPARγ ligands as a therapeutic option for skin inflammatory disorders. In addition, PPARγ also regulates sebocyte differentiation and lipid production, making it a potential target for inflammatory sebaceous disorders such as acne. A large number of studies suggest that PPARγ also acts as a skin tumor suppressor in both melanoma and non-melanoma skin cancers, but its role in tumorigenesis remains controversial. In this review, we have summarized the current state of research into the role of PPARγ in skin health and disease and how this may provide a starting point for the development of more potent and selective PPARγ ligands with a low toxicity profile, thereby reducing unwanted side effects.

Antimicrobial Effects of Platelet-Rich Plasma and Platelet-Rich Fibrin: A Scoping Review

Platelet-rich plasma (PRP), derived from the centrifugation and subsequent separation of whole blood, results in an unusually high concentration of platelets. A newer form of platelet concentrate, platelet-rich fibrin (PRF), has also been developed. There has been significant research into the therapeutic effects of PRP, particularly in enhancing wound healing and preventing infections in surgical wounds. This scoping review aims to thoroughly evaluate preclinical and clinical evidence regarding the antimicrobial effects of PRP and PRF. In conducting this review, 612 records were examined, and 36 articles were selected for inclusion. The studies reviewed include preclinical research, such as in-vitro and in-vivo studies, and clinical trials involving human participants. The current clinical evidence suggests a notable trend towards the antimicrobial capabilities of PRP and PRF, underscoring their potential benefits in treating wounds. The application of PRP and PRF in wound management shows encouraging outcomes, but further investigation is needed to optimize their use as antimicrobial agents. Additional research, particularly randomized controlled trials, is essential to substantiate their antimicrobial effectiveness in specific diseases and types of wounds, considering their potential impact on clinical results.

Corneal metabolic biomarkers for moderate and high myopia in human

This study aimed to identify the corneal metabolic biomarkers for moderate and high myopia in human. We enrolled 221 eyes from 221 subjects with myopia to perform the femtosecond laser small incision lenticule extraction (SMILE) surgery. Among these, 71 eyes of 71 subjects were enrolled in the low myopic group, 75 eyes of 75 subjects in the moderate myopic group and 75 eyes of 75 subjects in the high myopic group. The untargeted metabolomics analysis was performed to analyze the corneal tissues extracted during the SMILE surgery using an ultra-high-performance liquid chromatography (UHPLC) coupled to a quadrupole time-of-flight (Q-TOF) mass spectrometry (MS). The one-way analysis of variance (ANOVA) was used to identify the different metabolites among the three myopic groups, the orthogonal partial least-squares discriminant analysis (OPLS-DA) model was used to reveal the different metabolites between moderate myopia and low myopia, and between high myopia and low myopia. The Venn gram was used to find the overlapped metabolites of the three datasets of the different metabolites. The stepwise multiple linear regression analysis was used to determine the metabolic molecules associated with manifest refractive spherical equivalents (MRSE). The Receiver Operating Characteristics (ROC) analysis was performed to reveal the corneal biomarkers for moderate and high myopia. The hub biomarker was further selected by the networks among different metabolites created by the Cytoscape software. A total of 1594 metabolites were identified in myopic corneas. 321 metabolites were different among the three myopic groups, 106 metabolites were different between high myopic corneas and low myopic corneas, 104 metabolites were different between moderate myopic corneas and low myopic corneas, and 30 metabolic molecules overlapped among the three datasets. The multivariate linear regression analysis revealed the myopic degree was significantly influenced by the corneal levels of azelaic acid, arginine-proline (Arg-Pro), 1-stearoyl-2-myristoyl-sn-glycero-3-phosphocholine, and hypoxanthine. The ROC curve analysis showed that azelaic acid, Arg-Pro and hypoxanthine were effective in discriminating low myopia from moderate to high myopia with the area under the curve (AUC) values as 0.982, 0.991 and 0.982 for azelaic acid, Arg-Pro and hypoxanthine respectively. The network analysis suggested that Arg-Pro had the maximum connections among these three biomarkers. Thus, this study identified azelaic acid, Arg-Pro and hypoxanthine as corneal biomarkers to discriminate low myopia from moderate to high myopia, with Arg-Pro serving as the hub biomarker for moderate and high myopia.

Melasma: The need for tailored photoprotection to improve clinical outcomes

BACKGROUND/PURPOSE

Melasma is a frequent photoexacerbated hyperpigmentary disorder, which can significantly impact on the quality of life. We sought to review the pathogenesis of melasma, and the role of photoprotection in the prevention and treatment of this disorder.

METHODS

We conducted a narrative review of the literature. We performed literature searches with PubMed from January 1990 to December 2021 using the keywords "melasma," "pathogenesis," "ultraviolet radiation," "visible light," "photoprotection," and "sunscreens."

RESULTS

The physiopathology of melasma includes a complex interaction between genetics, sex hormones, and sun exposure. Visible light, in particular high-energy visible light (HEVL), and long-wave UVA (UVA1) play a key role in melasma pathophysiology, and recent research suggests that melasma shares many features with photoaging disorders. Melasma disproportionately affects dark-skinned individuals. Some 30% to 50% of South Americans and Asians, among other ethnicities, can present with melasma. Dark-skinned patients take fewer photoprotective measures. Also, the majority of melasma patients do not adequately follow photoprotection recommendations, including the application of sunscreen. Intensive use of a broad-spectrum sunscreen can prevent melasma in high-risk individuals, can lessen melasma severity (associated or not with depigmenting agents), and can reduce relapses.

CONCLUSIONS

Due to the physiopathology of melasma, sunscreens should be broad-spectrum with high sun protection factor, and provide high protection against UVA1 and VL. Sunscreens should be cosmetically acceptable and leave no white residue. Tinted sunscreens are an excellent choice, as pigments can protect from HEVL and UVA1, and may provide camouflage, but they must offer colors that match the skin tone of each patient.

Current research and clinical trends in rosacea pathogenesis

Background

Rosacea is a common and complex chronic inflammatory skin disorder, the pathophysiology and etiology of which remain unclear. Recently, significant new insights into rosacea pathogenesis have enriched and reshaped our understanding of the disorder. A systematic analysis based on current studies will facilitate further research on rosacea pathogenesis.

Objective

To establish an international core outcome and knowledge system of rosacea pathogenesis and develop a challenge, trend and hot spot analysis set for research and clinical studies on rosacea using bibliometric analysis and data mining.

Methods

A search of the WoS, and PubMed, MEDLINE, Embase and Cochrane collaboration databases was conducted to perform visual bibliometric and data analysis.

Results

A total of 2,654 studies were used for the visualization and 302 of the 6,769 outcomes for data analysis. It reveals an increased trend line in the field of rosacea, in which its fast-growing pathogenesis attracted attention closely related to risk, comorbidity and therapeutic strategies. The rosacea pathogenesis has undergone the great development on immunology, microorganisms, genes, skin barriers and neurogenetics. The major of studies have focused on immune and microorganisms. And keyword visualization and data analyses demonstrated the cross-talk between cells or each aspect of pathogenesis, such as gene-gene or gene-environment interactions, and neurological mechanisms associated with the rosacea phenotype warrant further research.

Limitations

Inherent limitations of bibliometrics; and reliance on research and retrospective studies.

Conclusions

The understanding of rosacea's pathogenesis has been significantly enhanced with the improved technology and multidisciplinary integration, but high-quality, strong evidence in favor of genomic and neurogenic requires further research combined with a better understanding of risks and comorbidities to guide clinical practice.

Understanding Melasma-How Can Pharmacology and Cosmetology Procedures and Prevention Help to Achieve Optimal Treatment Results? A Narrative Review

Melasma is a chronic skin condition that involves the overproduction of melanin in areas exposed to ultraviolet radiation. Melasma treatment is long-term and complicated with recurrence and resistance to treatment. The pathogenesis of melasma is highly complex with multiple pathologies occurring outside of the skin pigment cells. It includes photoaging, excessive melanogenesis, an increased number of mast cells, increased vascularization, and basement membrane damage. In addition, skin lesions related to melasma and their surrounding skin have nearly 300 genes differentially expressed from healthy skin. Traditionally, melasma was treated with topical agents, including hydroquinone, tretinoin, glucocorticosteroids and various formulations; however, the current approach includes the topical application of a variety of substances, chemical peels, laser and light treatments, mesotherapy, microneedling and/or the use of systemic therapy. The treatment plan for patients with melasma begins with the elimination of risk factors, strict protection against ultraviolet radiation, and the topical use of lightening agents. Hyperpigmentation treatment alone can be ineffective unless combined with regenerative methods and photoprotection. In this review, we show that in-depth knowledge associated with proper communication and the establishment of a relationship with the patient help to achieve good adherence and compliance in this long-term, time-consuming and difficult procedure.

Exploring the fuzzy border between senolytics and senomorphics with chemoinformatics and systems pharmacology

Senescent cells accumulate within tissues during aging and secrete an array of pro-inflammatory molecules known as senescent-associated secretory phenotype (SASP), which contribute to the appearance and progression of various chronic degenerative diseases. Novel pharmacological approaches aimed at modulating or eliminating senescent cells´ harmful effects have recently emerged: Senolytics are molecules that selectively eliminate senescent cells, while senomorphics modulate or decrease the inflammatory response to specific SASP. So far, the physicochemical, structural, and pharmacological properties that define these two kinds of pharmacological approaches remain unclear. Therefore, the identification and correct choice of molecules, based on their physicochemical, structural, and pharmacological properties, likely to exhibit the desired senotherapeutic activity is crucial for developing effective, selective, and safe senotherapies. Here we compared the physicochemical, structural, and pharmacological properties of 84 senolytics and 79 senomorphics using a chemoinformatic and systems pharmacology approach. We found great physicochemical, structural, and pharmacological similarities between them, also reflected in their cellular responses measured through transcriptome perturbations. The identified similarities between senolytics and senomorphics might explain the dual activity of some of those molecules. These findings will help design and discover new, more effective, and highly selective senotherapeutic agents.

Efficacy and Safety of Using Noninsulated Microneedle Radiofrequency Alone Versus in Combination with Polynucleotides for the Treatment of Melasma: A Pilot Study

Introduction

This split-face, double-blind, randomized controlled study investigated the efficacy and safety of using a microneedling radiofrequency (RF) device with polynucleotides (PN) versus RF alone for the treatment of melasma.

Methods

Thirty adult participants with melasma (Fitzpatrick skin types III–V) received three treatments with an invasive, bipolar, pulsed-type microneedling RF device on both sides of the face. The treatment sessions occurred once every 2 weeks. The hemifaces of each participant were designated for treatment and control with PN and normal saline solution (NSS), applied after treatment with RF. Measurements were made of melanin index (MI), erythema index (EI), skin roughness (by the Antera 3D system), modified melasma area severity index (mMASI) for each hemiface, and patients’ self-assessed improvement. These occurred at baseline and again following the final treatment (2 weeks and 1, 2, 3, and 6 months after). Mean values were obtained for MI, EI, skin roughness, and mMASI. A generalized estimating equation (GEE) was used to compare the obtained values for the outcome measures across all assessment points.

Results

All patients were women (mean age, 43.2 ± 7.0 years). Mixed melasma predominated (61.5%; n = 16), and the mean duration of melasma was 8.9 ± 6.5 years. Twenty-six participants were followed up to the 6-month assessment point. Significant improvements were observed from baseline in MI, skin roughness, and mMASI scores for both the PN and control sides at 6 months, with no statistically significant differences between sides. Patients’ self-assessed improvement scores also showed a positive trend. Melasma recurrence was observed in three patients at 2, 3, and 4 months after the last treatment session (10% recurrence rate).

Conclusions

The combination of an invasive, bipolar, pulsed-type microneedling RF with PN is not superior compared with microneedling RF alone in the treatment of melasma. Microneedling RF may be considered as safe and efficacious for the improvement of skin roughness, and as an adjunctive treatment option for melasma.

Clinical Trial Registration

This study was registered on ClinicalTrials.gov and assigned NCT number TCTR20210804002.

Sebocytes contribute to melasma onset

Melasma is a hyperpigmentary disorder with photoaging features, whose manifestations appear on specific face areas, rich in sebaceous glands (SGs). To explore the SGs possible contribution to the onset, the expression of pro-melanogenic and inflammatory factors from the SZ95 SG cell line exposed to single or repetitive ultraviolet (UVA) radiation was evaluated. UVA up-modulated the long-lasting production of α-MSH, EDN1, b-FGF, SCF, inflammatory cytokines and mediators. Irradiated SZ95 sebocyte conditioned media increased pigmentation in melanocytes and the expression of senescence markers, pro-inflammatory cytokines, and growth factors regulating melanogenesis in fibroblasts cultures. Cocultures experiments with skin explants confirmed the role of sebocytes on melanogenesis promotion. The analysis on sebum collected from melasma patients demonstrated that in vivo sebocytes from lesional areas express the UVA-activated pathways markers observed in vitro. Our results indicate sebocytes as one of the actors in melasma pathogenesis, inducing prolonged skin cell stimulation, contributing to localized dermal aging and hyperpigmentation.

The pathogenesis of melasma and implications for treatment

BACKGROUND

Melasma is a complex and poorly understood disorder, with high rates of treatment failure and recurrences.

OBJECTIVES

We aimed to review the current knowledge of the pathogenesis of melasma and apply this knowledge to clinical implications on relevant therapeutic interventions.

METHODS

A systematic PubMed search was performed using the search term "((melasma[Text Word]) OR facial melanosis[Text Word]) AND (pathogenesis OR causality[MeSH Terms])" for articles published between 1990 and 2020. Included articles were then evaluated by two authors and assessed for relevant pathomechanistic pathways, after which they were divided into groups with minimal overlap. We then reviewed current treatment modalities for melasma and divided them according to the involved pathomechanistic pathway.

RESULTS

A total of 309 search results were retrieved among which 76 relevant articles were identified and reviewed. Five main pathomechanisms observed in melasma were identified: (1) melanocyte inappropriate activation; (2) aggregation of melanin and melanosomes in dermis and epidermis; (3a) increased mast cell count and (3b) solar elastosis; (4) altered basement membrane; and (5) increased vascularization. Treatment modalities were then divided based on these five pathways and detailed in 6 relevant tables.

CONCLUSION

The pathophysiology of melasma is multifactorial, resulting in treatment resistance and high recurrence rates. This wide variety of pathomechanisms should ideally be addressed separately in the treatment regimen in order to maximize results.

NFATc4 mediates ethanol-triggered hepatocyte senescence

BACKGROUND

Hepatocyte senescence is a core event that mediates the occurrence and development of alcoholic liver disease. Nuclear factor of activated T-cells 4 (NFATc4) is a key driver of nonalcoholic steatohepatitis. However, little was known about the implication of NFATc4 for alcoholic liver disease. This study was aimed to investigate the role of NFATc4 in hepatocyte senescence and further elucidate the underlying mechanism.

METHODS

Real-time PCR, Western blot, immunofluorescence staining, and enzyme-linked immunosorbent assay were performed to explore the role of NFATc4 in hepatocyte senescence.

RESULTS

NFATc4 was induced in ethanol-incubated hepatocytes. NFATc4 knockdown recovered cell viability and reduced the release of aspartate transaminase, alanine transaminase, and lactic dehydrogenase from ethanol-incubated hepatocytes. NFATc4 knockdown protected mice from alcoholic liver injury and inflammation. NFATc4 knockdown counteracted ethanol-induced hepatocyte senescence, evidenced by decreased senescence-associated β-galactosidase positivity and reduced p16, p21, HMGA1, and γH2AX, which was validated in in vivo studies. Peroxisome proliferator-activated receptor (PPAR)γ was inhibited by NFATc4 in ethanol-treated hepatocytes. PPARγ deficiency abrogated the inhibitory effects of NFATc4 knockdown on hepatocyte senescence, oxidative stress, and hepatic steatosis in mice with alcoholic liver disease.

CONCLUSIONS

This work discovered that ethanol enhanced NFATc4 expression, which further triggered hepatocyte senescence via repression of PPARγ.

Cosmeceutical Aptitudes of Azelaic Acid

BACKGROUND

Azelaic acid (AZA) is a white crystalline dicarboxylic acid naturally found in grains, rye and barley. AZA has substantial biological and therapeutic abilities (viz a viz) its anti-inflammatory, anti-oxidant, anti-keratinizing, anti-microbial properties, etc. which contribute to its applicability in the management of mild to harsh dermatological complications (acne, rosacea, dermatitis, hyper-pigmentation, carcinomas, etc.). AZA has shown its effectiveness against varied non-inflammatory and inflammatory lesions by normalizing the hyper-keratinization statie and attenuating the increased levels of microbial content. Topically AZA, either alone or in conjunction with other active moieties, has proved to be effective in preventing acne and several other hyper-pigmentary conditions.

OBJECTIVES

Chronic applicability of AZA has been evidenced with the effects like itching, burning, stinging, redness, etc. To deal with the former issues, research is being conducted to substitute the conventional formulations with novel preparations (liposome's, niosomes, micro sponges, lipid nanocarriers, etc.), which could enhance the overall pharmaceutical and pharmacological profile of the drug.

CONCLUSION

This article is an attempt to highlight the basic physiochemical properties of AZA, its physiological role (especially in dermatology), various commercial preparations and recent novel approaches that are in research with an aim to augment the therapeutic and safety profile of AZA.

Liposomal azelaic acid 20% cream vs hydroquinone 4% cream as adjuvant to oral tranexamic acid in melasma: a comparative study

BACKGROUND

Melasma negatively impacts patient's quality of life (QoL). Although hydroquinone 4% is the most prescribed treatment, several side effects had been reported. The traditionally used azelaic acid 20% has poor tolerability and low skin absorption rate.

AIM

To assess the efficacy and tolerability of the liposomal form of azelaic acid 20% as an adjuvant to oral tranexamic acid in the treatment of melasma.

PATIENTS AND METHODS

Fifty females suffering from melasma were divided into two equal groups. The first group used a liposomal form of azelaic acid 20%, and the second group used hydroquinone 4%. Oral tranexamic acid 250 mg was taken by both groups as a single oral daily dose. Melasma severity and the patient's QoL were assessed.

RESULTS

A significant improvement of melasma was detected in females who used the liposomal form of azelaic acid 20% than those who used hydroquinone 4%. This was associated with a significant positive effect on their QoL. Furthermore, the liposomal form of azelaic acid 20% was more significantly tolerable than hydroquinone 4%.

CONCLUSION

The use of the liposomal form of azelaic acid provides an effective and well-tolerated addition to the treatment of melasma.

Epilipidomics of Senescent Dermal Fibroblasts Identify Lysophosphatidylcholines as Pleiotropic Senescence-Associated Secretory Phenotype (SASP) Factors

During aging, skin accumulates senescent cells. The transient presence of senescent cells, followed by their clearance by the immune system, is important in tissue repair and homeostasis. The persistence of senescent cells that evade clearance contributes to the age-related deterioration of the skin. The senescence-associated secretory phenotype of these cells contains immunomodulatory molecules that facilitate clearance but also promote chronic damage. Here, we investigated the epilipidome-the oxidative modifications of phospholipids-of senescent dermal fibroblasts, because these molecules are among the bioactive lipids that were recently identified as senescence-associated secretory phenotype factors. Using replicative- and stress- induced senescence protocols, we identified lysophosphatidylcholines as universally elevated in senescent fibroblasts, whereas other oxidized lipids displayed a pattern that was characteristic for the used senescence protocol. When we tested the lysophosphatidylcholines for senescence-associated secretory phenotype activity, we found that they elicit chemokine release in nonsenescent fibroblasts but also interfere with toll-like receptor 2 and 6/CD36 signaling and phagocytic capacity in macrophages. Using matrix-assisted laser desorption/ionization Fourier transform ion cyclotron resonance mass spectrometry imaging, we localized two lysophosphatidylcholine species in aged skin. This suggests that lysophospholipids may facilitate immune evasion and low-grade chronic inflammation in skin aging.

Effect of 3,3'-Diindolylmethane on Pulmonary Injury Following Thoracic Irradiation in CBA Mice

The molecule 3,3'-diindolylmethane (DIM) is small, a major bioactive metabolite of indole-3 carbinol (13C), and a phytochemical compound from cruciferous vegetables released upon exposure to the gut acid environment. DIM is a proposed anti-cancer agent and was previously demonstrated to prevent radiation damage in the bone marrow and the gastrointestinal tract. Here we investigated the effect of DIM on radiation-induced injury to the lung in a murine model through untargeted metabolomics and gene expression studies of select genes. CBA mice were exposed to thoracic irradiation (17.5 Gy). Mice were treated with vehicle or DIM (250 mg kg, subcutaneous injection) on days -1 pre-irradiation through +14 post-irradiation. DIM induced a significant improvement in survival by day 150 post-irradiation. Fibrosis-related gene expression and metabolomics were examined using lung tissue from days 15, 45, 60, 90, and 120 post-irradiation. Our qRT-PCR experiments showed that DIM treatment reduced radiation-induced late expression of collagen Iα and the cell cycle checkpoint proteins p21/waf1 (CDKN1A) and p16ink (CDKN2A). Metabolomic studies of lung tissue demonstrated a significant dampening of radiation-induced changes following DIM treatment. Metabolites associated with pro-inflammatory responses and increased oxidative stress, such as fatty acids, were suppressed by DIM treatment compared to irradiated samples. Together these data suggest that DIM reduces radiation-induced sequelae in the lung.

The versatility of azelaic acid in dermatology

Azelaic acid has numerous pharmacological uses in dermatology. Its anti-inflammatory and anti-oxidant properties are thought to correlate with its efficacy in papulopustular rosacea and acne vulgaris, amongst other cutaneous conditions. We conducted a review of the literature on the use of azelaic acid in dermatology using key terms 'acne', 'azelaic acid', 'dermatology', 'melasma', 'rosacea', searching databases such as MEDLINE, EMBASE and PubMed. Only articles in English were chosen. The level of evidence was evaluated and selected accordingly listing the studies with the highest level of evidence first using the Oxford Center of Evidence-Based Medicine 2011 guidance.This review found the strongest evidence supporting the use of azelaic acid in rosacea, followed by its use off-label in melasma followed by acne vulgaris. Weaker evidence is currently available to support the use of azelaic acid in several other conditions such as hidradenitis suppurativa, keratosis pilaris and male androgenic alopecia.Azelaic acid, as a monotherapy or in combination, could be an effective first-line or alternative treatment, which is well-tolerated and safe for a range of dermatological conditions.

Premature cell senescence in human skin: Dual face in chronic acquired pigmentary disorders

Although senescence was originally described as an in vitro acquired cellular characteristic, it was recently recognized that senescence is physiologically and pathologically involved in aging and age-related diseases in vivo. The definition of cellular senescence has expanded to include the growth arrest caused by various cellular stresses, including DNA damage, inadequate mitochondria function, activated oncogene or tumor suppressor genes and oxidative stress. While senescence in normal aging involves various tissues over time and contributes to a decline in tissue function even with healthy aging, disease-induced premature senescence may be restricted to one or a few organs triggering a prolonged and more intense rate of accumulation of senescent cells than in normal aging. Organ-specific high senescence rate could lead to chronic diseases, especially in post-mitotic rich tissue. Recently, two opposite acquired pathological conditions related to skin pigmentation were described to be associated with premature senescence: vitiligo and melasma. In both cases, it was demonstrated that pathological dysfunctions are not restricted to melanocytes, the cell type responsible for melanin production and transport to surrounding keratinocytes. Similar to physiological melanogenesis, dermal and epidermal cells contribute directly and indirectly to deregulate skin pigmentation as a result of complex intercellular communication. Thus, despite senescence usually being reported as a uniform phenotype sharing the expression of characteristic markers, skin senescence involving mainly the dermal compartment and its paracrine function could be associated with the disappearance of melanocytes in vitiligo lesions and with the exacerbated activity of melanocytes in the hyperpigmentation spots of melasma. This suggests that the difference may arise in melanocyte intrinsic differences and/or in highly defined microenvironment peculiarities poorly explored at the current state of the art. A similar dualistic phenotype has been attributed to intratumoral stromal cells as cancer-associated fibroblasts presenting a senescent-like phenotype which influence the behavior of neoplastic cells in either a tumor-promoting or tumor-inhibiting manner. Here, we present a framework dissecting senescent-related molecular alterations shared by vitiligo and melasma patients and we also discuss disease-specific differences representing new challenges for treatment.

Antimicrobial action of autologous platelet-rich plasma on MRSA-infected skin wounds in dogs

Effective antimicrobial preparations, other than antibiotics, are important for the treatment of potentially fatal drug-resistant infections. Methicillin-resistant Staphylococcus aureus (MRSA) is one of the leading causes of hospital-acquired and post- operative infections. Fortunately, the antimicrobial properties of platelet-rich plasma (PRP) against various microorganisms enable its potential use as an alternative to conventional antibiotics. The present work was designed to evaluate the hypothesized antimicrobial activity of PRP against MRSA infected skin wounds. Six adult male dogs were divided equally into control and PRP groups. Unilateral circular full-thickness skin wounds were created then a MRSA suspension was injected locally. Treatment started at 1st week post infection with subcutaneous infiltration of autologous activated PRP every week in the PRP group and with topical application of clindamycin cream twice daily in the control group. PRP decreased wound size and significantly increased wound contractility and re-epithelization, as confirmed by histopathological and immunohistochemical findings. Also PRP treated group showed significant decrease in ROS and redox imbalance with over expression of the TNF-α and VEGFA genes that indicate angiogenesis and maximum antibacterial activity after three weeks. In conclusion, CaCl2-activated PRP exhibited antimicrobial activity against MRSA infection, which improved the infected wound healing re-epithelization and granulation tissue formation.

Melasma: Updates and perspectives

Management of melasma is highly challenging due to inconsistent treatment results and frequent relapses. However, recent studies revealed that melasma may not only be a disease of melanocytes, but also a photoaging skin disorder. Herein, we attempt to validate that melasma is indeed a photoaging disorder by presenting the histopathologic findings of melasma: solar elastosis, altered basement membrane, increased vascularization and increased mast cell count. We also provide some therapeutic implications based on these findings and a discussion on the latest updates and perspectives regarding treatment.

Melasma, a photoaging disorder

Melasma is a common hyperpigmentary disorder. The impact on the quality of life of affected individuals is well demonstrated, demanding new therapeutic strategies. However, the treatment of melasma remains highly challenging. Melasma is often considered as the main consequence of female hormone stimulation on a predisposed genetic background. Although these two factors do contribute to this acquired pigmentary disorder, the last decade has revealed several other key players and brought new pieces to the complex puzzle of the pathophysiology of melasma. Here, we summarize the latest evidence on the pathophysiology of melasma, and we suggest that melasma might be a photoaging skin disorder affecting genetically predisposed individuals. Such data must be taken into consideration by clinicians as they could have a profound impact on the treatment and the prevention of melasma.

The mechanism of skin lipids influencing skin status

Skin lipids, compose of sebocyte-, keratinocyte-, and microbe- derived lipids, dramatically influence skin status by different mechanisms. (I) Physical chemistry function: They are "mortar" to establish the physico-chemical barrier function of skin; (II) Biochemistry function: They function as signals in the complex signaling network originating at the epidermal level; (III) Microecology function: Sebocyte- and keratinocyte-derived lipids vary the composition of microbial skin flora, and microorganisms metabolize them to produce lipids as signal starting signaling transduction. Importantly, further research needs lipidiomics, more powerful analytical ability and high-throughput manner, to identify skin lipid components into individual species. The validation of lipid structure and function to research the process that lipid species involved in. Additional, the integration of lipidomics data with other omics strategies can develop the power to study the mechanism of skin lipids influencing skin status.

Modulation of Toll Like Receptor-2 on sebaceous gland by the treatment of adult female acne

Adult female acne is a chronic inflammatory, immune-mediated disease that affects the pilosebaceous unit in women in their 20s to 40s, and is considered different from acne vulgaris. Propionibacterium acnes is recognized by TLR-2, resulting in activation of this receptor and an inflammatory response through the NFκ B pathway. This therapeutic, interventional, open, randomized, evaluator-blinded and comparative trial included 38 adult women with moderate facial acne and 10 age-matched controls, all aged between 26 and 44 years. Two treatments were performed over six months: 15% azelaic acid gel (AA) bid (n = 18) and oral contraceptive (COC) drospirenone 3 mg/ethinylestradiol .02 mg (n = 20). Biopsies were taken at baseline (control, lesion, perilesional) and at the conclusion (lesion and perilesional) of the study to evaluate TLR-2 expression by immunohistochemistry. Lesion count and blind photographic evaluation were used for efficacy. The groups were homogeneous: 70% of lesions were located in the submandibular area, 95% of participants had inflammatory lesions; of these, 50% had persistent and 50% had late-onset acne. The mean ages were 33.7 ± 5.5 and 33.1 ± 5.3 years (COC and AA group, respectively). A moderate clinical improvement was observed in both groups. No difference in TLR-2 expression in the lesion or perilesional areas was observed; however, reduced TLR-2 expression was seen in the control group. A significant reduction in expression was observed after both treatments, with no difference between the groups. This finding suggests an anti-inflammatory effect of COCs and AA in adult female acne, via modulation of the TLR-2 receptor.

Platelet-rich plasma ameliorates senescence-like phenotypes in a cellular photoaging model

Platelet-rich plasma (PRP) is a portion of blood plasma enriched with platelets widely investigated for accelerating bone and soft tissue healing.

Topical treatments for acne

Topical drugs have been used successfully to treat acne for decades. This review discusses the use, efficacy, and safety of options available via prescription. Topical antibiotics, dapsone, benzyl peroxide, azelaic acid, and topical retinoids are included. Topical antibiotics should not be used as monotherapy but rather be combined with other agents to avoid resistant Propionibacterium acnes strains. Benzoyl peroxide is effective in preventing bacteria resistance. Topical retinoids address primarily the comedonal but also the inflammatory lesions of acne. Azelaic acid is useful in treating acne lesions and for lightening postinflammatory hyperpigmentation that may accompany inflammatory acne lesions. Combinations of agents that address different aspects of acne pathogenesis may offer higher benefit to acne patients.

Activation of Peroxisome Proliferator-Activated Receptor Alpha Improves Aged and UV-Irradiated Skin by Catalase Induction

Peroxisome proliferator-activated receptor alpha (PPARα) is a nuclear hormone receptor involved in the transcriptional regulation of lipid metabolism, fatty acid oxidation, and glucose homeostasis. Its activation stimulates antioxidant enzymes such as catalase, whose expression is decreased in aged human skin. Here we investigated the expression of PPARα in aged and ultraviolet (UV)-irradiated skin, and whether PPARα activation can modulate expressions of matrix metalloproteinase (MMP)-1 and procollagen through catalase regulation. We found that PPARα mRNA level was significantly decreased in intrinsically aged and photoaged human skin as well as in UV-irradiated skin. A PPARα activator, Wy14643, inhibited UV-induced increase of MMP-1 and decrease of procollagen expression and caused marked increase in catalase expression. Furthermore, production of reactive oxygen species (ROS) was suppressed by Wy14643 in UV-irradiated and aged dermal fibroblasts, suggesting that the PPARα activation-induced upregulation of catalase leads to scavenging of ROS produced due to UV irradiation or aging. PPARα knockdown decreased catalase expression and abolished the beneficial effects of Wy14643. Topical application of Wy14643 on hairless mice restored catalase activity and prevented MMP-13 and inflammatory responses in skin. Our findings indicate that PPARα activation triggers catalase expression and ROS scavenging, thereby protecting skin from UV-induced damage and intrinsic aging.

Optimizing Non-Antibiotic Treatments for Patients with Acne: A Review

Acne is a very common non-infectious skin condition that is frequently treated in dermatological practices. Because acne is often chronic and may persist for years, safe and effective long-term maintenance therapy is often required. Given the increasing frequency of antibiotic-resistant bacteria and the gravity of the consequences of this trend, it behooves dermatologists to maximize use of non-antimicrobial therapy when treating acne. In this review of the literature we present data regarding the efficacy and appropriate use of non-antimicrobial treatments for acne. A variety of topical and oral treatment options exist that can be used in a step-wise manner according to the patients’ severity and therapeutic response. Non-antimicrobial treatments can be highly efficacious at controlling acne, especially when used as maintenance therapy. While antibiotics have a role in acne treatment, they should not be used as monotherapy, and lengthy courses of antibiotic use are discouraged.

The role of PPARγ-mediated signalling in skin biology and pathology: new targets and opportunities for clinical dermatology

Peroxisome proliferator-activated receptors (PPARs) are ligand-activated transcription factors that modulate the expression of multiple different genes involved in the regulation of lipid, glucose and amino acid metabolism. PPARs and cognate ligands also regulate important cellular functions, including cell proliferation and differentiation, as well as inflammatory responses. This includes a role in mediating skin and pilosebaceous unit homoeostasis: PPARs appear to be essential for maintaining skin barrier permeability, inhibit keratinocyte cell growth, promote keratinocyte terminal differentiation and regulate skin inflammation. They also may have protective effects on human hair follicle (HFs) epithelial stem cells, while defects in PPARγ-mediated signalling may promote the death of these stem cells and thus facilitate the development of cicatricial alopecia (lichen planopilaris). Overall, however, selected PPARγ modulators appear to act as hair growth inhibitors that reduce the proliferation and promote apoptosis of hair matrix keratinocytes. The fact that commonly prescribed PPARγ-modulatory drugs of the thiazolidine-2,4-dione class can exhibit a battery of adverse cutaneous effects underscores the importance of distinguishing beneficial from clinically undesired cutaneous activities of PPARγ ligands and to better understand on the molecular level how PPARγ-regulated cutaneous lipid metabolism and PPARγ-mediated signalling impact on human skin physiology and pathology. Surely, the therapeutic potential that endogenous and exogenous PPARγ modulators may possess in selected skin diseases, ranging from chronic inflammatory hyperproliferative dermatoses like psoriasis and atopic dermatitis, via scarring alopecia and acne can only be harnessed if the complexities of PPARγ signalling in human skin and its appendages are systematically dissected.

A three-dimensional skin equivalent reflecting some aspects of in vivo aged skin

Human skin undergoes morphological, biochemical and functional modifications during the ageing process. This study was designed to produce a 3-dimensional (3D) skin equivalent in vitro reflecting some aspects of in vivo aged skin. Reconstructed skin was generated by co-culturing skin fibroblasts and keratinocytes on a collagen-glycosaminoglycan-chitosan scaffold, and ageing was induced by the exposition of fibroblasts to Mitomycin-C (MMC). Recently published data showed that MMC treatment resulted in a drug-induced accelerated senescence (DIAS) in human dermal fibroblast cultures. Next to established ageing markers, histological changes were analysed in comparison with in vivo aged skin. In aged epidermis, the filaggrin expression is reduced in vivo and in vitro. Furthermore, in dermal tissue, the amount of elastin and collagen is lowered in aged skin in vivo as well as after the treatment of 3D skin equivalents with MMC in vitro. Our results show histological signs and some aspects of ageing in a 3D skin equivalent in vitro, which mimics aged skin in vivo.

Influence of azelaic acid on acne pathogenesis

I In current literature review the physicochemical properties, peculiarities of mode of action and pharmacokinetics of azelaic and influence of azelaic on pathogenetic aspects of acne are characterized.

Face-to-face with anti-inflammatory therapy for rosacea

In the past, our understanding of rosacea has been inadequate and limited to descriptions of factors that exacerbate and improve the disease. While the pathophysiology of rosacea is complex and multifactorial, cathelicidin peptides have emerged as key players in the pathogenesis of this common dermatological disorder. This article correlates recent findings in abnormal cathelicidin production and proteolytic processing in rosacea with therapeutic actions of current treatment options and, in this way, highlights potential points of intervention for the development of efficient therapeutic alternatives.

Foam cell-derived 4-hydroxynonenal induces endothelial cell senescence in a TXNIP-dependent manner

Vascular endothelial cell (VEC) senescence is considered an early event in the development of atherosclerotic lesions. Stressful stimuli, in particular oxidative stress, have been linked to premature senescence in the vasculature. Foam cells are a major source of reactive oxygen species and may play a role in the induction of VEC senescence; hence, we investigated their involvement in the induction of VEC senescence in a co-culture transwell system. Primary bovine aortic endothelial cells, exposed to the secretome of THP-1 monocyte-derived foam cells, were analysed for the induction of senescence. Senescence associated β-galactosidase activity and the expression of p16 and p21 were increased, whereas phosphorylated retinoblastoma protein was reduced. This senescent phenotype was mediated by 4-hydroxnonenal (4-HNE), a lipid peroxidation product secreted from foam cells; scavenging of 4-HNE in the co-culture medium blunted this effect. Furthermore, both foam cells and 4-HNE increased the expression of the pro-oxidant thioredoxin-interacting protein (TXNIP). Molecular manipulation of TXNIP expression confirmed its involvement in foam cell-induced senescence. Previous studies showed that peroxisome proliferator-activated receptor (PPAR)δ was activated by 4-hydroalkenals, such as 4-HNE. Pharmacological interventions supported the involvement of the 4-HNE-PPARδ axis in the induction of TXNIP and VEC senescence. The association of TXNIP with VEC senescence was further supported by immunofluorescent staining of human carotid plaques in which the expression of both TXNIP and p21 was augmented in endothelial cells. Collectively, these findings suggest that foam cell-released 4-HNE activates PPARδ in VEC, leading to increased TXNIP expression and consequently to senescence.

Gene expression profile of high-fat diet-fed C57BL/6J mice: in search of potential role of azelaic acid

High-fat diet (HFD) elevates circulatory fatty acids and influences glucose and fat metabolism. Azelaic acid (AzA), a naturally occurring α,ω-dicarboxylic acid in wheat, rye, barley, oat seeds and sorghum, has been reported to exert antidiabetic effects in HFD-induced type 2 diabetes mellitus (T2DM) C57BL/6J mice. The present study was undertaken to identify the genes that are differentially modulated by treatment with AzA in HFD-fed mice. Mice were fed HFD for 10 weeks and subjected to intragastric administration of 80 mg/kg body weight (BW) of AzA daily along with HFD from 11 to 15 weeks. Lipid profile, adipokines and cytokines were examined in the plasma/liver of mice. Whole genome profiling was performed in the liver of mice using microarray and validated by qRT-PCR, Western blot and immunohistochemical analyses. HFD intake resulted in significantly elevated lipids (except high-density lipoproteins), resistin, tumour necrosis factor alpha and interleukin-6 with marked reduction in adiponectin. Administration of AzA to HFD-fed mice significantly restored the lipids, adipokines and cytokines to near normal. Transcript profiling revealed that HFD intake activated the genes involved in stress response, cell cycle regulation and apoptosis. Treatment with AzA caused increased expression of genes involved in reactive oxygen species (ROS) scavenging, receptor-mediated signalling, transcription, protein modification and insulin signal transduction. AzA activates insulin signal molecules leading to insulin sensitivity. The ability of AzA to modulate the expression of these genes supports the notion that AzA is a promising drug candidate for the treatment of insulin resistance associated with T2DM.

Senescence suppressors: their practical importance in replicative lifespan extension in stem cells

Recent animal and clinical studies report promising results for the therapeutic utilization of stem cells in regenerative medicine. Mesenchymal stem cells (MSCs), with their pluripotent nature, have advantages over embryonic stem cells in terms of their availability and feasibility. However, their proliferative activity is destined to slow by replicative senescence, and the limited proliferative potential of MSCs not only hinders the preparation of sufficient cells for in vivo application, but also draws a limitation on their potential for differentiation. This calls for the development of safe and efficient means to increase the proliferative as well as differentiation potential of MSCs. Recent advances have led to a better understanding of the underlying mechanisms and significance of cellular senescence, facilitating ways to manipulate the replicative lifespan of a variety of primary cells, including MSCs. This paper introduces a class of proteins that function as senescence suppressors. Like tumor suppressors, these proteins are lost in senescence, while their forced expression delays the onset of senescence. Moreover, treatments that increase the expression or the activity of senescence suppressors, therefore, cause expansion of the replicative and differentiation potential of MSCs. The nature of the activities and putative underlying mechanisms of the senescence suppressors will be discussed to facilitate their evaluation.

Modulation of PPARγ provides new insights in a stress induced premature senescence model

Peroxisome proliferator-activated receptor gamma (PPARγ) may be involved in a key mechanism of the skin aging process, influencing several aspects related to the age-related degeneration of skin cells, including antioxidant unbalance. Therefore, we investigated whether the up-modulation of this nuclear receptor exerts a protective effect in a stress-induced premature senescence (SIPS) model based on a single exposure of human dermal fibroblasts to 8-methoxypsoralen plus + ultraviolet-A-irradiation (PUVA). Among possible PPARγ modulators, we selected 2,4,6-octatrienoic acid (Octa), a member of the parrodiene family, previously reported to promote melanogenesis and antioxidant defense in normal human melanocytes through a mechanism involving PPARγ activation. Exposure to PUVA induced an early and significant decrease in PPARγ expression and activity. PPARγ up-modulation counteracted the antioxidant imbalance induced by PUVA and reduced the expression of stress response genes with a synergistic increase of different components of the cell antioxidant network, such as catalase and reduced glutathione. PUVA-treated fibroblasts grown in the presence of Octa are partially but significantly rescued from the features of the cellular senescence-like phenotype, such as cytoplasmic enlargement, the expression of senescence-associated-β-galactosidase, matrix-metalloproteinase-1, and cell cycle proteins. Moreover, the alterations in the cell membrane lipids, such as the decrease in the polyunsaturated fatty acid content of phospholipids and the increase in cholesterol levels, which are typical features of cell aging, were prevented. Our data suggest that PPARγ is one of the targets of PUVA-SIPS and that its pharmacological up-modulation may represent a novel therapeutic approach for the photooxidative skin damage.

Role of PPAR, LXR, and PXR in epidermal homeostasis and inflammation

Epidermal lipid synthesis and metabolism are regulated by nuclear hormone receptors (NHR) and in turn epidermal lipid metabolites can serve as ligands to NHR. NHR form a large superfamily of receptors modulating gene transcription through DNA binding. A subgroup of these receptors is ligand-activated and heterodimerizes with the retinoid X receptor including peroxisome proliferator-activated receptor (PPAR), liver X receptor (LXR) and pregnane X receptor (PXR). Several isotypes of these receptors exist, all of which are expressed in skin. In keratinocytes, ligand activation of PPARs and LXRs stimulates differentiation, induces lipid accumulation, and accelerates epidermal barrier regeneration. In the cutaneous immune system, ligand activation of all three receptors, PPAR, LXR, and PXR, has inhibitory properties, partially mediated by downregulation of the NF-kappaB pathway. PXR also has antifibrotic effects in the skin correlating with TGF-beta inhibition. In summary, ligands of PPAR, LXR and PXR exert beneficial therapeutic effects in skin disease and represent promising targets for future therapeutic approaches in dermatology. This article is part of a Special Issue entitled The Important Role of Lipids in the Epidermis and their Role in the Formation and Maintenance of the Cutaneous Barrier. Guest Editors: Kenneth R. Feingold and Peter Elias.

Azelaic acid: Properties and mode of action

Acne is a common skin disorder that can be problematic for adults as well as for adolescents. It has several key pathophysiological features such as follicular hyperkeratosis, elevated Propionibacterium acnes proliferation, and reactive inflammation, all of which should be targeted for an optimal outcome. Azelaic acid (AzA) has profound anti-inflammatory, antioxidative effects, and is bactericidal against a range of Gram-negative and Gram-positive microorganisms as well, including antibiotic-resistant bacterial strains. In addition, AzA's antikeratinizing effects are inhibitory toward comedones. AzA is effective overall in targeting multiple causes of acne and has been proven to be well tolerated in numerous clinical trials.