Autocrine and paracrine regulation of melanocytes in human skin and in pigmentary disorders

Semaxanib, a VEGF inhibitor, suppresses melanogenesis by modulating CRTC3 independently of VEGF signaling

BACKGROUND

Dysregulation of melanogenesis contributes to the development of skin hyperpigmentation diseases, which poses a treatment challenge. Following the establishment of CRTC3 screening methods to explore small molecules inhibiting melanogenesis for the topical treatment of hyperpigmentation diseases, we identified a candidate molecule, semaxanib.

OBJECTIVE

To explore the antimelanogenic effects of semaxanib, a vascular endothelial growth factor receptor (VEGFR) 2 inhibitor, for potential applications in hyperpigmentation management and to unravel the role of VEGF signaling in melanocyte biology by investigating mechanism of action of semaxanib.

METHODS

Mouse-derived spontaneously immortalized melanocytes, B16F10, and normal human primary epidermal melanocytes cells were treated with semaxanib, and cellular responses were assessed using cell viability assays and melanin content measurements. Molecular mechanisms were investigated using transcriptional activity assays, reverse-transcription polymerase chain reaction, and immunoblotting analysis. In vivo studies were conducted using an epidermis-humanized transgenic mouse model and ex vivo human skin tissues.

RESULTS

Semaxanib ameliorated melanin content in cultured melanocytes by downregulating the expression of melanogenesis-associated genes by suppressing the CRTC3/microphthalmia-associated transcription factors. Topical application of semaxanib reduced melanin accumulation in the ultraviolet B-stimulated ex vivo human epidermis and tail of K14-stem cell factor transgenic mice. Mechanistically, the antimelanogenic effect induced by semaxanib was associated with SIK2-CRTC3-MITF rather than VEGF signaling in melanocytes.

CONCLUSION

Semaxanib emerges as a promising candidate for the development of therapeutics for hyperpigmentation, potentially working independently of VEGF signaling in human melanocytes.

Emerging Role of Fibroblasts in Vitiligo: A Formerly Underestimated Rising Star

Vitiligo is a disfiguring depigmentation disorder characterized by loss of melanocytes. Although numerous studies have been conducted on the pathogenesis of vitiligo, the underlying mechanisms remain unclear. Although most studies have focused on melanocytes and keratinocytes, growing evidence suggests the involvement of dermal fibroblasts, residing deeper in the skin. This review aims to elucidate the role of fibroblasts in both the physiological regulation of skin pigmentation and their pathological contribution to depigmentation, with the goal of shedding light on the involvement of fibroblasts in vitiligo. The topics covered in this review include alterations in the secretome, premature senescence, autophagy dysfunction, abnormal extracellular matrix, autoimmunity, and metabolic changes.

Combination of a Topical Anti-Inflammatory Drug and a Moisturizer, Both with a Lamellar Structure Containing Synthetic Pseudo-Ceramides, for the Treatment of Patients with Mild-to-Moderate Atopic Dermatitis

Purpose

Atopic dermatitis is characterized by chronic inflammation and dryness accompanied by severe itching. The combined use of moisturizers and topical anti-inflammatory drugs is essential for alleviating atopic dermatitis. We have developed a topical anti-inflammatory drug with a steroid and a moisturizer with heparinoid, both in lamellar structure-based formulations containing synthetic pseudo-ceramides. Here, assessed the efficacy of this combination in the treatment of atopic dermatitis.

Methods

We included 22 patients with mild to moderate atopic dermatitis and subjected them to a seven-week treatment with the test formulations, followed by a four-week post-treatment period.

Results

Clinical findings and the quality of life of participants remarkably improved after one week of treatment. Furthermore, skin hydration and transepidermal water loss considerably improved at weeks one and three, respectively. The Cer [NP]/[NS] ratio, an indicator of epidermal turnover, substantially increased during the treatment period and remained elevated even thereafter. The improvement in stratum corneum function was distinctive in participants with lower barrier function.

Conclusion

These findings indicated that the combined use of the anti-inflammatory drug and moisturizer, both in lamellar structure-based formulations, is effective in treating atopic dermatitis in patients with fragile barrier function.

Role of Dermal Factors Involved in Regulating the Melanin and Melanogenesis of Mammalian Melanocytes in Normal and Abnormal Skin

Mammalian melanin is produced in melanocytes and accumulated in melanosomes. Melanogenesis is supported by many factors derived from the surrounding tissue environment, such as the epidermis, dermis, and subcutaneous tissue, in addition to numerous melanogenesis-related genes. The roles of these genes have been fully investigated and the molecular analysis has been performed. Moreover, the role of paracrine factors derived from epidermis has also been studied. However, the role of dermis has not been fully studied. Thus, in this review, dermis-derived factors including soluble and insoluble components were overviewed and discussed in normal and abnormal circumstances. Dermal factors play an important role in the regulation of melanogenesis in the normal and abnormal mammalian skin.

col1a2+ fibroblasts/muscle progenitors finetune xanthophore countershading by differentially expressing csf1a/1b in embryonic zebrafish

Animals evolve diverse pigment patterns to adapt to the natural environment. Countershading, characterized by a dark-colored dorsum and a light-colored ventrum, is one of the most prevalent pigment patterns observed in vertebrates. In this study, we reveal a mechanism regulating xanthophore countershading in zebrafish embryos. We found that csf1a and csf1b mutants altered xanthophore countershading differently: csf1a mutants lack ventral xanthophores, while csf1b mutants have reduced dorsal xanthophores. Further study revealed that csf1a is expressed throughout the trunk, whereas csf1b is expressed dorsally. Ectopic expression of csf1a or csf1b in neurons attracted xanthophores into the spinal cord. Blocking csf1 signaling by csf1ra mutants disrupts spinal cord distribution and normal xanthophores countershading. Single-cell RNA sequencing identified two col1a2+ populations: csf1ahighcsf1bhigh muscle progenitors and csf1ahighcsf1blow fibroblast progenitors. Ablation of col1a2+ fibroblast and muscle progenitors abolished xanthophore patterns. Our study suggests that fibroblast and muscle progenitors differentially express csf1a and csf1b to modulate xanthophore patterning, providing insights into the mechanism of countershading.

The Keratinocyte in the Picture Cutaneous Melanoma Microenvironment

Melanoma progression is a multistep evolution from a common melanocytic nevus through a radial superficial growth phase, the invasive vertical growth phase finally leading to metastatic dissemination into distant organs. Melanoma aggressiveness largely depends on the propensity to metastasize, which means the capacity to escape from the physiological microenvironment since tissue damage due to primary melanoma lesions is generally modest. Physiologically, epidermal melanocytes are attached to the basement membrane, and their adhesion/migration is under the control of surrounding keratinocytes. Thus, the epidermal compartment represents the first microenvironment responsible for melanoma spread. This complex process involves cell-cell contact and a broad range of secreted bioactive molecules. Invasion, or at the beginning of the microinvasion, implies the breakdown of the dermo-epidermal basement membrane followed by the migration of neoplastic melanocytic cells in the superficial papillary dermis. Correspondingly, several experimental evidences documented the structural and functional rearrangement of the entire tissue surrounding neoplasm that in some way reflects the atypia of tumor cells. Lastly, the microenvironment must support the proliferation and survival of melanocytes outside the normal epidermal-melanin units. This task presumably is mostly delegated to fibroblasts and ultimately to the self-autonomous capacity of melanoma cells. This review will discuss remodeling that occurs in the epidermis during melanoma formation as well as skin changes that occur independently of melanocytic hyperproliferation having possible pro-tumoral features.

The underestimated role of mitochondria in vitiligo: From oxidative stress to inflammation and cell death

Vitiligo is an acquired depigmentary disorder characterized by the depletion of melanocytes in the skin. Mitochondria shoulder multiple functions in cells, such as production of ATP, maintenance of redox balance, initiation of inflammation and regulation of cell death. Increasing evidence has implicated the involvement of mitochondria in the pathogenesis of vitiligo. Mitochondria alteration will cause the abnormalities of mitochondria functions mentioned above, ultimately leading to melanocyte loss through various cell death modes. Nuclear factor erythroid 2-related factor 2 (Nrf2) plays a critical role in mitochondrial homeostasis, and the downregulation of Nrf2 in vitiligo may correlate with mitochondria damage, making both mitochondria and Nrf2 promising targets in treatment of vitiligo. In this review, we aim to discuss the alterations of mitochondria and its role in the pathogenesis of vitiligo.

Expression of Endothelin-1, Endothelin Receptor-A, and Endothelin Receptor-B in facial melasma compared to adjacent skin

Background/Objectives

Although melasma is highly prevalent, its pathogenesis is not yet fully understood. In the skin, endothelin-1 (ET-1) is primarily produced by keratinocytes in response to UVB exposure, which is mediated by an increase in IL-1α or reactive oxygen species. ET-1 plays a role in melanogenesis by binding to specific receptor B (ERB) or receptor A (ERA). However, the expression of ET-1, ERA, and ERB in melasma has not been systematically investigated. The objective of this study was to evaluate the expression of ET-1, ERA, and ERB in facial melasma compared to the adjacent unaffected skin.

Methods

Cross-sectional study, with 40 skin samples (20: facial melasma; 20: adjacent unaffected skin) from women with facial melasma without treatment for 30 days except for sunscreen. A triple staining immunofluorescence technique was performed for anti-vimentin, DAPI, plus one of the following antibodies: (a) anti-ET1, (b) anti-ERA; (c) anti-ERB. Interfollicular areas on the slides of each topography (melasma; unaffected skin) were photographed in triplicate under confocal laser microscopy. The mean staining intensities of the image histograms (0-255 pixels intensity) were estimated for different types of cells (suprabasal keratinocytes, basal layer, and upper dermis) and were blindly compared between topographies.

Results

The mean (SD) age of the participants was 44.9 (9.2). The expression of ET-1 was increased in the whole epidermis with melasma when compared to the adjacent skin, being 32.8% (CI95% 14.7%-52.6%) higher in the spinous layer (p=0.013), 30.4% (CI95% 13.7%-47.9%) higher in the basal layer (p=0.014), and 29.7% (CI95% 11.4%-49.7%) higher in the melanocytes (p=0.006). There was no noticeable expression of ET-1 within the cells on the upper dermis. Neither ERA nor ERB resulted in differential epidermal expression between melasma and unaffected skin (p≥0.1).

Conclusion

ET-1 is expressed more intensely on the epidermis from the skin with facial melasma compared to the unaffected adjacent skin.

Novel Hydrogenated Derivatives of Chemically Modified Curcumin CMC2.24 Are Potent Inhibitors of Melanogenesis in an In Vitro Model: Influence of Degree of Hydrogenation

Chemically modified curcumin, CMC2.24, is a promising therapeutic that has shown efficacy in ameliorating excessive pigmentation in our previous studies. However, its inherent disadvantages of color, stability, solubility, and cytotoxicity to melanocytes and keratinocytes at concentrations > 4 µg/mL posed challenges in its use in cosmetic formulations. To overcome these limitations, chemical reduction by hydrogenation of CMC2.24 (compound 1) was developed to yield products at different time points of hydrogenation (1 h, 2 h, 4 h, and 24 h) referred to as partially (2, 3, 4) or fully hydrogenated (5) products, and the effects of the degree of hydrogenation on melanogenesis in vitro were explored. Compound 1 and products 2-5 were evaluated using mushroom tyrosinase activity assays with two substrates (L-tyrosine and L-DOPA), then cellular assays using B16F10 mouse melanoma cells, MNT-1 human melanoma cells, and physiological normal human melanocytes (HEMn-DP cells). The cytotoxicity, melanin contents, cellular tyrosinase activities, and cellular oxidative stress were evaluated. Moreover, the recovery of melanin contents in HEMn-DP cells was also studied. Our results provide novel insights into the role of the degree of hydrogenation of compound 1 on the biological effects of melanogenesis, which were dependent on cell type. To the best of our knowledge, this is the first study to show that in HEMn-DP cells, the anti-melanogenic efficacy of the yellow-colored CMC2.24 is retained as early as 1 h after its hydrogenation; this efficacy is enhanced with longer durations of hydrogenation, with a robust efficacy achieved for the 24 h hydrogenated product 5 at the lowest concentration of 4 µg/mL. A similar potency could be achieved for product 4 at higher concentrations, although interestingly, both differ only by a minor amount of dihydro-CMC2.24. Our results indicate promise for using products 4 & 5 as a skin-lightener in cosmetic formulations with the advantages of lack of color combined with a potency much greater than that of the parent compound 1 at lower concentrations and reversibility of the effects on melanocytes. This, along with the easy synthesis and scale-up of the hydrogenation method for CMC2.24 and the documented higher solubility, stability, and bioavailability of tetrahydrocurcumin, provides further impetus to incorporating these derivatives in cosmetic formulations. The results of this study can help to extend the therapeutic window of the lead compound CMC2.24 by providing options for selecting partially or fully hydrogenated derivatives for cosmetic applications where a trade-off between color and efficacy is needed. Thus, the degree of hydrogenation can be tuned for desired biological effects. Further studies are warranted to evaluate the efficacy of products 4 & 5 at suppressing pigmentation in 3D skin-tissue equivalents and in vivo models.

Dark pigmentation and related low FMOD expression increase IL-3 and facilitate plasmacytoid dendritic cell maturation

According to epidemiological research, skin autoimmune diseases are more prevalent among black Americans. We postulated that pigment-producing melanocytes may contribute to local immune regulation in the microenvironment. We examined murine epidermal melanocytes in vitro to determine the role of pigment production in immune responses mediated by dendritic cell (DC) activation. Our study revealed that darkly pigmented melanocytes produce more IL-3 and the pro-inflammatory cytokines, IL-6 and TNF-α, and consequently induce plasmacytoid DC (pDC) maturation. Additionally, we demonstrate that low pigment-associated fibromodulin (FMOD) interferes with cytokine secretion and subsequent pDC maturation.

Impact of KIT Editing on Coat Pigmentation and Fresh Meat Color in Yorkshire Pigs

The white coat color of Yorkshire pigs is caused by the dominant white I allele, which has been associated with at least one copy of the 450-kb duplication encompassing the entire KIT gene and a splice mutation (G > A) at the first base of intron 17. The splice mutation in KIT has an adverse effect on pigmentation in mice. Therefore, removing the 450 kb duplications harboring the KIT copy with splice mutations is expected to affect Yorkshire pig pigmentation. In this study, we describe the use of a Yorkshire pig kidney cell strain with the I^?/I^Be-ed genotype, previously created by CRISPR-Cas9, as donor cells for somatic cell nuclear transfer to generate gene-edited Yorkshire pigs. The removal of the 450 kb duplications harboring the KIT copy with splice mutation did not alter the white coat color of Yorkshire pigs, which was confirmed by the absence of fully mature melanocytes and melanin accumulation in the hair follicles. Except for the improved transcription of tyrosinase, and slight increase in microphthalmia transcription factor and tyrosinase-related protein 1 protein expression, there was no significant impact of the removal of splice mutations on genes and signaling pathways (PI3K/AKT) involved in melanogenesis. However, the removal of the 450 kb duplications harboring the KIT copy with splice mutation substantially improved fresh meat color accompanied by significantly increased red blood cell number, which merits further investigation. Our study provides new insights into the role of structural mutations of the KIT gene in the formation of white coat color and erythropoiesis in Yorkshire pigs.

The role of cytokines and vitamin D in vitiligo pathogenesis

Vitiligo is a pigment-related disease with a global prevalence of 0.2% to 1.8% associated with considerable burden on quality of life. The treatment is still a challenge because of relapses and/or incomplete re-pigmentation. Although the exact cause is still unclear, its pathogenesis seems to be justifiable with the autoimmune theory, supported by the results of clinical research. In this narrative review, we aimed to summarize the evidence related to cytokines and vitiligo development. This review is consisted of English articles published in PubMed and Google Scholar concerning levels of inflammatory mediators, especially interleukins, in vitiligo patients over the last 20 years. References of relevant articles were also considered for review. Crucial role of dysregulated levels of interleukins and their synergistic function to each other, in the onset or progression of the disease is evident. The theory of autoimmune vitiligo is reinforced by the results of the studies in the literature, due to the association of pathogenesis with increased secretion of pro-inflammatory mediators and reduction of anti-inflammatory mediators. Decreased vitamin D levels may have a considerable role in vitiligo development by affecting Th1- and Th17-related immune responses. Cytokines play an important role in the pathogenesis or progression of the disease. Moreover, we believe that decreased vitamin D level has a considerable role in vitiligo development by affecting Th1- and Th17-related immune responses.

Assessment of stem cell factor expression and its c-KIT receptor in patients with vitiligo

Introduction

Melanocytes show antigen expressions characteristic for the immune response effector cells, and the immune reactions in the skin, especially those with inflammation background, significantly affect the function of melanocytes. Among the cytokines produced by keratinocytes, the stem cell factor (SCF) plays a leading role in stimulating melanogenesis.

Aim

To compare the expression level of stem cell factor (mSCF, pSCF) and the c-Kit receptor in the centre of the vitiligo patch and in the area of healthy skin adjacent to the vitiligo patch.

Material and methods

The research material consisted of skin samples from a vitiligo lesion and from non-lesional skin adjacent to the vitiligo patch. Real Time PCR analysis (Applied Biosystems 7900HT) was performed to determine the expression level of the studied genes.

Results

The studies showed a statistically significant increase in the amount of mSCF within the vitiligo patch compared to both healthy skin of patients with vitiligo and controls. In patients with vitiligo, c-Kit receptor expression was significantly decreased in the area of the lesional skin compared to the healthy skin of the same patient and the skin of the control group.

Conclusions

The membrane-bound form of the SCF is overexpressed within the vitiligo skin, which may indicate the participation of mSCF in the stimulation of melanogenesis in response to melanocyte damage. Decreased expression of C-Kit receptor by melanocytes in the vitiligo patch disrupts the ligand-receptor interaction and may therefore be related to melanocytes dysfunction and/or loss.

Incobotulinum Toxin Type A for Treatment of Ultraviolet-B-Induced Hyperpigmentation: A Prospective, Randomized, Controlled Trial

Incobotulinum toxin A (IncoBoNT-A) is effective in preventing ultraviolet B (UVB)-induced hyperpigmentation. This prospective, randomized, controlled study aimed to evaluate the effect of IncoBoNT-A on the treatment of UVB-induced hyperpigmentation in 15 volunteers. Five hyperpigmentation squares (2 × 2 cm) were induced by local UVB on the abdomen at baseline. At Day 7, each site was randomized to receive no treatment (control), normal saline, or intradermal IncoBoNT-A injection with 1:2.5, 1:5, and 1:7.5 dilutions (12, 6, and 4 units, respectively). The mean lightness index (L*), hyperpigmentation improvement score evaluated by blinded dermatologists, and participant satisfaction scores were obtained at Days 21, 28, and 35. At Day 21, improvements in mean L* of 1:2.5, 1:5, and 1:7.5 IncoBoNT-A-treated, saline-treated, and control sites were 14.30%, 12.28%, 6.62%, 0.32%, and 4.98%, respectively (p = 0.86). At Day 28, the improvement in mean L* in IncoBoNT-A-treated groups was superior to that in the other groups. In terms of the hyperpigmentation improvement score, 12 participants (80%) experienced better outcomes with the IncoBoNT-A-injected site compared with the other sites. IncoBoNT-A, especially at higher concentrations, showed some positive effects on the treatment of UVB-induced hyperpigmentation. This may serve as an adjuvant treatment for hyperpigmentary conditions that are aggravated by UVB.

Focus on the Contribution of Oxidative Stress in Skin Aging

Skin aging is one of the most evident signs of human aging. Modification of the skin during the life span is characterized by fine lines and wrinkling, loss of elasticity and volume, laxity, rough-textured appearance, and pallor. In contrast, photoaged skin is associated with uneven pigmentation (age spot) and is markedly wrinkled. At the cellular and molecular level, it consists of multiple interconnected processes based on biochemical reactions, genetic programs, and occurrence of external stimulation. The principal cellular perturbation in the skin driving senescence is the alteration of oxidative balance. In chronological aging, reactive oxygen species (ROS) are produced mainly through cellular oxidative metabolism during adenosine triphosphate (ATP) generation from glucose and mitochondrial dysfunction, whereas in extrinsic aging, loss of redox equilibrium is caused by environmental factors, such as ultraviolet radiation, pollution, cigarette smoking, and inadequate nutrition. During the aging process, oxidative stress is attributed to both augmented ROS production and reduced levels of enzymatic and non-enzymatic protectors. Apart from the evident appearance of structural change, throughout aging, the skin gradually loses its natural functional characteristics and regenerative potential. With aging, the skin immune system also undergoes functional senescence manifested as a reduced ability to counteract infections and augmented frequency of autoimmune and neoplastic diseases. This review proposes an update on the role of oxidative stress in the appearance of the clinical manifestation of skin aging, as well as of the molecular mechanisms that underline this natural phenomenon sometimes accelerated by external factors.

Selaginellin Inhibits Melanogenesis via the MAPK Signaling Pathway

Hyperpigmented skin diseases such as melasma, freckles, and melanosis usually mar the appearance of patients. Traditional herbal medicines are highly accepted in inhibiting skin pigmentation, with advantages of high efficiency, low cost, and low side effects. Selaginellin (SEL), one of the active compounds of selaginella, has been proved to be exhibit antineoplastic, antioxidant, antisenescence, and antiapoptosis activities. In this study, we found that SEL can inhibit melanogenesis in vitro and in vivo. A mechanism study found that SEL inhibits melanogenesis through inhibiting the mitogen-activated protein kinase (MAPK) signaling pathway, then down-regulating the expression of microphthalmia-associated transcription factor (MITF) and downstream genes tyrosinase (TYR) and tyrosinase-related protein 2 (TYRP2). UVB-activated paracrine function of fibroblasts and keratinocytes promotes melanogenesis of melanocytes. Interestingly, SEL antagonizes UVB-activated paracrine function of fibroblasts and keratinocytes. These findings indicate that SEL can be a potential whitening compound to inhibit melanogenesis.

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.

Therapeutic Effects of New Pulsed-Type Microneedling Radiofrequency for Refractory Facial Pigmentary Disorders

BACKGROUND

Numerous treatments for pigmentary disorders have been used with variable outcomes. Recently, a new radiofrequency (RF) device with minimal pulse duration has been introduced.

OBJECTIVE

The aim of this study was to evaluate the efficacy and safety of a pulsed-type microneedling RF device for treatment of facial pigmentary disorders.

METHODS

Forty-four patients diagnosed with facial melasma or Riehl melanosis received 5 treatments with RF at 2-week intervals, and evaluation was performed at each visits, including 4 and 8 weeks after the last treatment. Treatment outcomes were evaluated by investigator global assessment, patient global assessment score, and skin biophysical parameters of erythema index, melanin index (MI), and transepidermal water loss. Gene array and immunohistochemical staining including melan-A, Fontana silver, CD44, basic fibroblast growth factor (bFGF), and periodic acid-Schiff were performed.

RESULTS

Most of the patients showed clinical improvement. Erythema index, MI, and transepidermal water loss decreased after the first treatment. Histopathologic examination showed decrease of melanin pigment, melanophages, and blood vessel proliferation but thickened basement membrane after treatment. Expression of CD44 and b-FGF was decreased after treatment. There were no serious adverse events reported during the study.

CONCLUSION

Pulsed-type microneedling RF could be a treatment option for facial pigmentary disorders.

Post-acne hyperpigmentation: Evaluation of risk factors and the use of artificial neural network as a predictive classifier

Acne is common among young individuals. People with dark skin have a higher risk for developing pigmentary complications. Inflammation is an important factor in post-acne hyperpigmentation however other factors are also involved in developing this complication however these factors are not well studied. The aim of this study is to identify risk factors involved in post-acne hyperpigmentation. Clinical data related to acne, acne- related hyperpigmentation were collected. Data was analyzed for risk factors associated with acne pigmentation. Artificial neural network was used as predictive disease classifier for the outcome of pigmentation. Majority of patients in this study (339 patients) had dark skin phototypes (3 and 4). Post- acne hyperpigmentation was seen in more than 80% of patients. Females, darker skin color, severe acne, facial sites, and excessive sunlight exposure, squeezing or scratching lesions are important risk factors for post-acne hyperpigmentation. Post-acne hyperpigmentation is multifactorial. Several factors implicated in PAH are modifiable by adequate patient education (lesion trauma, excessive sunlight exposure). The use of ANN was helpful in predicting appearance of post-acne hyperpigmentation based on identified risk factors.

Bioactive substances in the stratum corneum of the epidermis found as indicators of skin damage due to sun exposure

Background/Purpose

Although an inflammatory response upon acute injury caused by ultraviolet radiation (UV) can be observed immediately, the influence of long‐term, repetitive low‐dose UV exposure on the skin cannot be precisely perceived, making early detection of chronic damage difficult. This study investigated bioactive substances in the stratum corneum as a potential early and sensitive indicator of the influence of sun exposure on the skin using receiver operating characteristic (ROC) analysis.

Methods

Receiver operating characteristic analysis was performed to assess the responsiveness of cytokines [interleukin (IL)‐1α, IL‐1 receptor antagonist (IL‐1ra), IL‐10, tumor necrosis factor (TNF)‐α], BCL2‐associated protein X (Bax), Toll‐like receptor (TLR)3, and TLR4 in the stratum corneum of healthy people exposed (dorsum of the hand) and unexposed (inner arm) to UV. Sunscreen was applied to patients with photodermatosis for 4 weeks to evaluate changes in IL‐1ra/IL‐1α, TNF‐α, Bax, and TLR3 levels after sunscreen application, as these molecules exhibited high responsiveness to sun exposure according to ROC analysis. In addition, IL‐1ra, IL‐1α, and IL‐10 levels were quantified by enzyme‐linked immunosorbent assay, and TNF‐α, Bax, TLR3, and TLR4 levels were semi‐quantitatively assessed by immunocytochemistry.

Results

Receiver operating characteristic analysis identified IL‐1ra/IL‐1α, TNF‐α, Bax, and TLR3 in the stratum corneum as highly responsive to sun exposure. Moreover, in participants, including patients with photodermatosis, IL‐1ra/IL‐1α, TNF‐α, and Bax levels decreased significantly after sunscreen application.

Conclusion

The results revealed that IL‐1ra/IL‐1α, TNF‐α, and Bax in the stratum corneum represent sensitive indicators of the influence of sun exposure on the skin.

A Lower Irradiation Dose of 308 nm Monochromatic Excimer Light Might Be Sufficient for Vitiligo Treatment: A Novel Insight Gained from In Vitro and In Vivo Analyses

A 308 nm monochromatic excimer light (MEL) is widely used to treat patients with vitiligo. However, dose optimization still needs to be clarified. This study aimed to obtain objective evidence regarding various doses of MEL irradiation, induced cell level changes in vitro, and skin level alterations in vivo. Cultured human keratinocytes were irradiated with MEL using various doses. After irradiation at low doses, stem cell factor, endothelin-1, and glycoprotein nonmetastatic melanoma protein B, factors that activate and protect melanocytes, were found to be significantly elevated in keratinocytes. After irradiation using medium and high doses, inflammatory cytokines were induced. The amount of ATP released and the level of inflammasome activation, which are known to be related to interleukin-1β activation, were also increased. The back skin of guinea pigs and mice were irradiated with MEL at varying doses. After irradiation, an increase of epidermal melanin and epidermal melanocytes was confirmed, using the minimal erythemal dose or less. In rhododendrol-induced leukoderma guinea pigs, a much lower dose of MEL irradiation was effective, when compared with the effective dose for control guinea pigs. Our results suggest that a lower irradiation dose of MEL might be sufficient and more suitable for repigmentation in vitiligo treatment.

Nanofat Injection for the Treatment of Depressed Facial Scars

BACKGROUND

Patients with depressed facial scars complain of their negative effects. However, the efficacy of optional treatment techniques is never completely adequate. This study aimed to assess the efficacy of nanofat injection in the improvement of depressed facial scars.

METHODS

This retrospective study included patients who underwent depressed facial scar filling with nanofat between November 2017 and January 2020. The FACE-Q scale was sent to patients for feedback regarding satisfaction. Evaluations of the results were also performed by three plastic surgeons.

RESULTS

Among the 52 included patients, 44 patients (29 women and 15 men) completed the questionnaire. Obvious and stable effects were usually acquired 3 months after surgery. Temporary erythema appeared at the injection site to varying degrees, lasting 2 to 3 weeks in 93% of the patients. No other serious postoperative complications were observed in the injection area. The FACE-Q outcomes showed that patients who completed injection therapy more than 1 year prior were significantly more satisfied with the decision to undergo this therapy than those who completed the treatment less than 1 year prior. Furthermore, according to the physicians' evaluations, 91% of patients experienced improvement in scar appearance after treatment.

CONCLUSIONS

The low rate of injection-site complications and the safety of this procedure both support the current implementation of nanofat in the treatment of depressed facial scars. The results of the physicians' evaluations and patient satisfaction surveys confirmed the stable effect of nanofat injection in the treatment of depressed facial scars.

LEVEL OF EVIDENCE IV

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The regulatory role of Korean ginseng in skin cells

As the largest organ in our body, the skin acts as a barrier against external stress and damages. There are various cell types of skin, such as keratinocytes, melanocytes, fibroblasts, and skin stem cells. Korean ginseng, which is one of the biggest distributions of ginseng worldwide, is processed into different products, such as functional food, cosmetics, and medical supplies. This review aims to introduce the functional role of Korean ginseng on different dermal cell types, including the impact of Korean ginseng in anti-photodamaging, anti-inflammatory, anti-oxidative, anti-melanogenic, and wound healing activities, etc. We propose that this information could form the basis of future research of ginseng-derived components in skin health.

A Randomized Controlled Trial on the Effectiveness of Epidermal Growth Factor-Containing Ointment on the Treatment of Solar Lentigines as Adjuvant Therapy

Background and Objective: Little is known about the anti-pigmentation effects of whitening agents on solar lentigines. Epidermal growth factor (EGF) has been used as a booster for wound healing in the skin, and it has been suggested to have anti-pigmentation effects. This study aimed to evaluate the effect and safety of EGF-containing ointment for treating solar lentigines with a Q-switched (QS) 532 nm neodymium-doped yttrium aluminum garnet (Nd:YAG) laser (Bluecore company, Seoul, Republic of Korea). Materials and Methods: Subjects who underwent QS 532 nm Nd:YAG laser treatment of solar lentigines were randomly assigned to treatment with an EGF ointment or petrolatum. After the laser procedure, the subjects were administered the test ointment twice a day for 4 weeks. The physician's assessment of the degree of pigment clearance and patient's satisfaction were assessed after 4 and 8 weeks. Additionally, the melanin index (MI), erythema index (EI), transepidermal water loss (TEWL), and post-inflammatory hyperpigmentation (PIH) were evaluated. This trial was registered with ClinicalTrials.gov (NCT04704245). Results: The blinded physician's assessment using 5-grade percentage improvement scale and patient's satisfaction were significantly higher in the study group than in the control group at the 4th and 8th weeks. The MI was significantly higher in the control group than in the study group at the 4th and 8th weeks. The EI and TEWL did not differ significantly between the two groups at either time point. The incidence of PIH was higher in the control group (37.5%) than in the EGF group (7.14%) at the 8th week. Conclusions: The application of EGF-containing ointment on facial solar lentigines with a QS 532 nm Nd:YAG laser showed efficient and safe therapeutic effects, with less PIH. Thus, EGF-containing ointment could be suggested as the promising adjuvant treatment strategy with a QS laser for solar lentigines.

Whitening effect of novel peptide mixture by regulating melanosome biogenesis, transfer and degradation

Peptides are short chain of amino acids linked by peptide bonds. They are widely used as effective and biocompatible active ingredients in cosmetic industry. In this study, we developed novel peptide mixture and identified its anti-pigmentation effect on melanocytes and keratinocytes. Our results revealed that peptide mixture inhibited melanosome biogenesis through the regulation of microphthalmia-associated transcription factor, a key factor of melanogenesis in melanocytes. And we observed that peptide mixture inhibited melanosome uptake through the reduction of protease-activated receptor 2, a phagocytosis-related receptor in keratinocytes. Furthermore, peptide mixture activated autophagy system resulting in degradation of transferred melanosomes in keratinocytes. The anti-pigmentation effect of multi-targeting peptide mixture was assessed in a human skin equivalent model (MelanoDerm). Melanin contents in epidermal layer were significantly decreased by topical treatment of peptide mixture, suggesting that it can be applied as a novel cosmetics material having a whitening function.

The additive efficacy of therapeutic low-intensity pulsed ultrasound in the treatment of vitiligo: A randomized, left-right comparison clinical trial

Repigmentation of vitiligo relies on the proliferation and migration of melanoblasts from hair follicles to the epidermis to replenish epidermal melanin. Our previous study has demonstrated low-intensity pulsed ultrasound (LIPUS) can stimulate melanoblast migration in vitro. We sought to evaluate the potential additive efficacy and safety of LIPUS for repigmentation of vitiligo. Twenty-seven adult patients with stable generalized vitiligo on the face or trunk were recruited in this randomized, open, left-right comparison study. In each patient, two symmetric lesional sites were randomly selected; one was assigned as the target lesion, which was treated with add-on LIPUS twice weekly for 24 weeks, and the other as the control lesion, which was administrated with sham sonification. The primary outcome was the difference of repigmentation degree between the target and control lesions at week 24, based on the 7-point physician global assessment score. At the end of study, 23 patients with vitiligo on the face (n = 10) or trunk (n = 13) completed the 24-week treatment course. Enhanced repigmentation for vitiligo receiving LIPUS as compared to sham sonification was observed in 38.5% (5/13) of the patients with truncal vitiligo, but none of those with facial vitiligo. Truncal vitiligo (P = .046) and higher intensity of LIPUS administered (P = .01) were statistically significantly associated with the effectiveness of additive LIPUS treatment. The LIPUS treatment was well-tolerated without remarkable adverse effects. This pilot study showed that LIPUS could provide therapeutic benefits and could be considered as a treatment adjunct for truncal vitiligo.

A Framework of Major Tumor-Promoting Signal Transduction Pathways Implicated in Melanoma-Fibroblast Dialogue

Simple Summary

Melanoma cells reside in a complex stromal microenvironment, which is a critical component of disease onset and progression. Mesenchymal or fibroblastic cell type are the most abundant cellular element of tumor stroma. Factors secreted by melanoma cells can activate non-malignant associated fibroblasts to become melanoma associate fibroblasts (MAFs). MAFs promote tumorigenic features by remodeling the extracellular matrix, supporting tumor cells proliferation, neo-angiogenesis and drug resistance. Additionally, environmental factors may contribute to the acquisition of pro-tumorigenic phenotype of fibroblasts. Overall, in melanoma, perturbed tissue homeostasis contributes to modulation of major oncogenic intracellular signaling pathways not only in tumor cells but also in neighboring cells. Thus, targeted molecular therapies need to be considered from the reciprocal point of view of melanoma and stromal cells.

Abstract

The development of a modified stromal microenvironment in response to neoplastic onset is a common feature of many tumors including cutaneous melanoma. At all stages, melanoma cells are embedded in a complex tissue composed by extracellular matrix components and several different cell populations. Thus, melanomagenesis is not only driven by malignant melanocytes, but also by the altered communication between melanocytes and non-malignant cell populations, including fibroblasts, endothelial and immune cells. In particular, cancer-associated fibroblasts (CAFs), also referred as melanoma-associated fibroblasts (MAFs) in the case of melanoma, are the most abundant stromal cells and play a significant contextual role in melanoma initiation, progression and metastasis. As a result of dynamic intercellular molecular dialogue between tumor and the stroma, non-neoplastic cells gain specific phenotypes and functions that are pro-tumorigenic. Targeting MAFs is thus considered a promising avenue to improve melanoma therapy. Growing evidence demonstrates that aberrant regulation of oncogenic signaling is not restricted to transformed cells but also occurs in MAFs. However, in some cases, signaling pathways present opposite regulation in melanoma and surrounding area, suggesting that therapeutic strategies need to carefully consider the tumor–stroma equilibrium. In this novel review, we analyze four major signaling pathways implicated in melanomagenesis, TGF-β, MAPK, Wnt/β-catenin and Hyppo signaling, from the complementary point of view of tumor cells and the microenvironment.

Comparative efficacy between localized 308-nm excimer light and targeted 311-nm narrowband ultraviolet B phototherapy in vitiligo: A randomized, single-blind comparison study

BACKGROUND

There are limited data to compare efficacy between recent 308-nm excimer and conventional 311-nm narrowband ultraviolet B (NB-UVB) light in the treatment of vitiligo.

OBJECTIVE

To compare efficacy between 308-nm excimer light and 311-nm NB-UVB in patients with symmetrical vitiligo lesions.

METHODS

Thirty-six symmetrically paired vitiligo lesions on the same anatomical area were enrolled. One side of the symmetrical lesions was treated with localized 308-nm excimer light, and the opposite side was treated with targeted 311-nm NB-UVB assigned randomly by computer. All lesions were treated with the same protocol, for 48 sessions. Repigmentation was evaluated using Vitiligo Area Scoring Index (VASI) and grading the repigmentation was carried out with three independent investigators.

RESULTS

Thirty-six symmetrically vitiligo lesions were randomly treated, one side with 308-nm excimer light and the opposite side with 311-nm NB-UVB. After 48 sessions, a significantly lower VASI score and a higher grade of repigmentation were observed in 308-nm excimer light-treated side (P < .001). Nine lesions (25%) treated with 308-nm excimer light and only five lesions (13.89%) treated with 311-nm NB-UVB achieved excellent repigmentation. The 308-nm excimer light and 311-nm NB-UVB-treated sides rapidly obtained 25% repigmentation within a mean of 19.42 sessions and 26.25 sessions, respectively (P = .002). There was no significant difference in mean cumulative UV dosage (P = .065). Side effect as phototoxicity was similar in both sides (P = .08).

CONCLUSION

Localized 308-nm excimer light appears to be more effective and also more rapidly induces repigmentation than targeted 311-nm NB-UVB for treatment of vitiligo.

Investigation of the Role of Interleukin 6 in Vitiligo Pathogenesis

Interleukin-6 (IL6) is involved in pathogenesis of several autoimmune disorders including vitiligo. Hence, we aimed to investigate the association of IL6 -174 G/C and -572 G/C polymorphisms and its transcript levels with vitiligo; to evaluate the effect of IL-6 on normal human melanocyte (NHM) viability and expression of IL6R, MITF and TYR. IL6 -174 G/C and -572 G/C polymorphisms were genotyped by ARMS-PCR and PCR-RFLP respectively in 343 controls and 322 vitiligo patients. IL6 transcript levels were estimated from PBMCs (96 controls and 77 patients) and skin samples (15 controls and 15 patients) by qPCR. NHM viability was assessed by MTT; IL6R, MITF and TYR transcript and protein levels were monitored by qPCR and ICC respectively. Genetic analyses revealed no association of IL6 -174 G/C polymorphism (p> .05) with vitiligo. Analysis of IL6 -572 G/C revealed reduced risk of vitiligo in individuals with GC/CC genotypes compared to GG genotype (p = .010). IL6 expression was significantly increased (p = .0197) in PBMCs of patients. Further, IL6 expression was significantly higher in non-lesional skin compared to controls (p = .009). In-vitro NHM viability was decreased upon IL-6 exposure (10-50 ng/ml; p< .05), with significantly increased IL6R transcript (p = .042) and protein levels (p = .003) however, MITF transcript (p = .0003) and protein levels (p = .016), and TYR transcript levels (p = .001) were significantly decreased. The results suggest that IL6 -572 G/C polymorphism might be associated with vitiligo susceptibility in Gujarat population. Moreover, increased IL6 expression in vitiligo patients and its effect on NHM suggest a potential role in melanocyte biology.

CONCLUSION

The results suggest that IL6 - 572 G/C polymorphism might be associated with vitiligo susceptibility in Gujarat population. Moreover, increased IL6 expression in vitiligo patients and its effect on NHM suggest a potential role in melanocyte biology.

Extracellular fraction of adipose tissue as an innovative regenerative approach for vitiligo treatment

Vitiligo is a common, disfiguring autoimmune disease that negatively affects patients' self-esteem and quality of life. Current treatments are moderately effective in reversing disease and promoting melanocyte regeneration. Thus, therapeutic advanced strategies are emerging from regenerative medicine. It has recently emerged that adipose tissue secretome may be used as a cell-free therapy in skin regeneration since paracrine functions of adipose-derived stem cells alone are responsible for most of the therapeutic effect of stem cells in several animal disease models. In this study, we tested the effect of adipose tissue extracellular fraction (AT-Ex) isolated from lipoaspirates on dermal and epidermal vitiligo cells in vitro. Using this experimental model, we demonstrated that molecules secreted by adipose tissue ameliorate the capability to counteract oxidative stress by a physiological stimulation of intracellular antioxidant enzymes and positively impact on cell proliferation. Due to the presence of Wnt-secreted factors, AT-Ex treatment promotes glycogen synthase kinase 3β inactivation and consequently Wnt/β-catenin pathway activation. Collectively, our findings show that AT-Ex could be useful as a natural approach to improve treatment of vitiligo.

Solar ultraviolet-induced DNA damage response: Melanocytes story in transformation to environmental melanomagenesis

Exposure to sunlight is both beneficial, as it heats the planet to a comfortable temperature, and potentially harmful, since sunlight contains ultraviolet radiation (UVR), which is deemed detrimental for living organisms. Earth's ozone layer plays a vital role in blocking most of the extremely dangerous UVC; however, low frequency/energy UVR (i.e., UVB and UVA) seeps through in minute amount and reaches the Earth's surface. Both UVB and UVA are physiologically responsible for a plethora of skin ailments, including skin cancers. The UVR is readily absorbed by the genomic DNA of skin cells, causing DNA bond distortion and UV-induced DNA damage. As a defense mechanism, the DNA damage response (DDR) signaling in skin cells activates nucleotide excision repair (NER), which is responsible for the removal of UVR-induced DNA photolesions and helps maintain the genomic integrity of the cells. Failure of proper NER function leads to mutagenesis and development of skin cancers. One of the deadliest form of skin cancers is melanoma which originates upon the genetic transformation of melanocytes, melanin producing skin cells. NER is a well-studied DNA repair system in the whole skin, as a tissue, but not much is known about it in melanocytes. Therefore, this review encapsulates NER in melanocytes, with a specific focus on its functional regulators and their cross talks due to skin heterogeneity and divulging the potential knowledge gap in the field.

308-nm Excimer Laser Plus Platelet-Rich Plasma for Treatment of Stable Vitiligo: A Prospective, Randomized Case-Control Study

Purpose

308-nm excimer laser has a confirmed treatment effect on vitiligo. Platelet-rich plasma (PRP) is an autologous preparation which contains a variety of growth factors. The effect of 308-nm excimer laser combined with PRP on vitiligo has been rarely reported. This study investigated the effect of PRP combined with 308-nm excimer laser on stable vitiligo.

Patients and Methods

A total of 60 patients with localized stable vitiligo who received treatment at Beijing Friendship Hospital and Xi’an Vitiligo Specialist Hospital between May 2019 and January 2020 were consecutively enrolled. They were equally randomized into three groups according to different treatment methods: intradermal PRP injection (group I), 308-nm excimer laser alone (group II), and 308-nm excimer laser plus PRP injection (group III). All treatments lasted for 3 months. At 3 months after treatment, clinical assessments were performed in terms of the visual analogue scale (VAS) score, repigmentation response and side effects.

Results

The VAS scores showed significant differences among the three groups (P<0.001), with the highest score in group III, followed by group II and then group I. Repigmentation responses also showed significant differences among the groups (P<0.001), and the best effect was observed in group III. No side effects were reported in any of the groups.

Conclusion

The effect of PRP combined with 308-nm excimer laser on stable vitiligo is significantly better than that of PRP and 308-nm excimer laser alone. It is safe and satisfactorily tolerant.

Fueling Melanocytes with ATP from Keratinocytes Accelerates Melanin Synthesis

Melanocyte homoeostasis and their response to ultraviolet radiation (UVR) are mediated to a large extent by keratinocyte-derived factors, many of which have been well-characterized. Lee et al. describe novel effects of adenosine 5'-triphosphate (ATP), which is secreted by keratinocytes and can stimulate melanogenesis by melanocytes following UVA exposure. The investigators attribute the melanogenic effect of ATP to binding purinergic receptors type 2 X7 (P2X7), which are expressed on human melanocytes, leading to activation of the protein kinase C pathway. This report is the first to identify expression of specific purinergic receptors on human melanocytes, and it suggests ATP as a signaling molecule that stimulates pigmentation. Follow up on these results should clarify the physiological role of ATP in mediating the tanning response to solar UVR.

Studying the effect of adding growth factors to the autologous melanocyte keratinocyte suspension in segmental vitiligo

Addition of different growth factors to the medium used in autologous melanocyte-keratinocyte transplantation procedure (MKTP) was reported in the literature. The aim of the current study was comparison of response to MKTP in segmental vitiligo (SV) with and without adding growth factors to the suspension medium. Eighteen cases with SV were randomly divided into two groups. In group A: Ham F12 medium was used for suspension and in group B: 5 ng/mL recombinant basic fibroblast growth factor (bFGF) and 25 mg/500 mL 3'5' cyclic adenosine monophosphate (cAMP) were added to the medium. All cases received NB-UVB twice weekly for 24 weeks. The area of vitiligo lesions was measured before and after therapy by point-counting technique and complications were recorded. Excellent response (90%-100% repigmentation) occurred in 5/9 cases (56%) in group A and 7/9 cases (78%) in group B (with growth factors). A significant decrease in the area of treated lesions before and after therapy was found in both groups A and B (P = .0012 and .0004, respectively), however, a higher percentage of reduction in area of vitiligo was seen in group B cases (70% in group A vs 90% in group B; P value: .028). Marginal halo was seen in five cases in group A and six in group B. In conclusion addition of bFGF and cAMP to MKTP medium improved the results of the procedure. It could be considered if economically feasible.

Effects of various doses of glutathione on the proliferation, viability, migration, and ultrastructure of cultured human melanocytes

Normal human cultured melanocytes were exposed to various glutathione concentrations (0.1, 0.5, 1.0, 5.0, and 10.0 mg/mL) for 72 hours. At the end of the experiment, proliferation, viability, migration, and ultrastructural changes were monitored. Glutathione at the doses of 0.5 to 10.0 mg/mL reduced the viability of melanocytes significantly as compared to the control (P < .05). Glutathione significantly reduced the proliferation of melanocytes at the doses of 0.5 to 10.0 mg/mL as compared to the control (P < .001). Glutathione at 0.5 to 10.0 mg/mL significantly reduced the migration of melanocytes as compared to the control (P < .001). The percentage of mature melanosomes was 53.43% in control and 50.58%, 41.83%, 33.4%, and 8.95% in 0.1, 0.5, 1.0, and 5.0 mg/mL glutathione exposed cells, respectively. This reduction in the number of mature melanosomes was statistically significant as compared to the control. However, no cytotoxic effects were recognized by electron micrographs. These results encourage the potential implementation of glutathione as a skin-lightening agent. However, this study is limited by cell culture and ultrastructural. It should therefore be expanded in the future to include patients with pigmentary disorders.

Functional Analysis of KIT Gene Structural Mutations Causing the Porcine Dominant White Phenotype Using Genome Edited Mouse Models

The dominant white phenotype in pigs is thought to be mainly due to a structural mutation in the KIT gene, a splice mutation (G > A) at the first base in intron 17 which leads to the deletion of exon 17 in the mature KIT mRNA. However, this hypothesis has not yet been validated by functional studies. Here, we created two mouse models, KIT D17/+ to mimic the splice mutation, and KIT Dup/+ to partially mimic the duplication mutation of KIT gene in dominant white pigs using CRISPR/Cas9 technology. We found that the splice mutation homozygote is lethal and the heterozygous mice have a piebald coat. Slightly increased expression of KIT in KIT Dup/+ mice did not confer the patched phenotype and had no obvious impact on coat color. Interestingly, the combination of these two mutations reduced the phosphorylation of PI3K and MAPK pathway associated proteins, which may be related to the impaired migration of melanoblasts observed during embryonic development that eventually leads to the dominant white phenotype.

Consumption of Polyphenols in Coffee and Green Tea Alleviates Skin Photoaging in Healthy Japanese Women

Purpose

Hyperpigmentation of the skin can occur at any age depending on etiological factors but its intensity increases during adolescence in Japanese females and gradually develops further in adults. The purpose of this study was to characterize factors that influence skin hyperpigmentation, including age, skin type and dietary polyphenol sources.

Patients and Methods

A cross-sectional survey of healthy Japanese women aged from 30 to 60 years (n=244) was conducted using food and environmental questionnaires and a VISIA™ facial photoimage analyzer.

Results

UV Pigmented Spot (PS) scores correlated negatively with the consumption of total polyphenols (TPs) (R=-0.224, p<0.001) and the rate of hyperpigmented spot development (PS score/age after 18 years of age) was suppressed by the consumption of TPs. This trend was independent of the melanin index and the skin type, which indicates the ability of the skin to tan after sun exposure. Consumption of coffee, the largest source of TPs, suppressed the PS score (p<0.001). Consumption of green tea, the second largest source of TPs, also suppressed the PS score, which was weaker than coffee but was statistically significant (p=0.029). The PS score was suppressed the most in subjects with both a high consumption of coffee and green tea.

Conclusion

Higher consumption of TPs may be beneficial to alleviate photoaging of the skin, and coffee as well as green tea contribute to suppress skin hyperpigmentation through adding large amounts of TPs in the diet.

The effects of UVB irradiance on vitiligo phototherapy and UVB-induced photocarcinogenesis

Phototherapy is the most commonly used modality for repigmenting vitiligo. Currently, UVB emitting devices, including narrow-band UVB (NBUVB) and excimer laser/light, are considered as the treatment of choice. While emitting wavelengths at close proximity, excimer lights emit higher irradiance (HI; W/m² ) compared to NBUVB. Clinical reports have shown that excimer light is more efficacious in treating vitiligo compared to NBUVB, and we demonstrated that irradiance plays a critical role in promoting melanoblasts differentiation. UVB radiation from the sun is closely associated with photocarcinogenesis of the skin. Sunscreens were used to protect the skin by reducing UVB irradiance (low irradiance (LI) UVB). Sunscreen use was associated with skin cancer reduction in clinical trials. Paradoxically, sunscreen use was associated with increased sunburn episodes in the real-world settings. It was shown that UVB-induced sunburn depends on fluence (J/m² ) but not irradiance of UVB radiation. We investigated the significance of irradiance in the context of UVB-induced carcinogenesis of the skin. For mice receiving equivalent fluence of UVB exposure, the LIUVB-treated mice showed earlier tumor development, larger tumor burden, and more epidermal keratinocytes harboring mutant p53 as compared to their HIUVB-treated counterparts. These results suggested that at equivalent fluence, LIUVB radiation has more photocarcinogenic potential on the skin compared to its HI counterpart. Since development of sunburn with or without sunscreen use indicates that certain threshold of UVB fluence has been received by the skin at LI and HI, respectively, sunburn episodes with sunscreen use (LIUVB) are more damaging to the skin compared to that without sunscreen (HIUVB) application. In summary, since irradiance plays an important role determining the biological effects of UVB radiation on the skin, future related studies should take this critical parameter into consideration.

Stem Cell Factor-Inducible MITF-M Expression in Therapeutics for Acquired Skin Hyperpigmentation

Rationale: Microphthalmia-associated transcription factor M (MITF-M) plays important roles in the pigment production, differentiation and survival of melanocytes. Stem cell factor (SCF) and its receptor KIT stimulate MITF-M activity via phosphorylation at the post-translation level. However, the phosphorylation shortens half-life of MITF-M protein over the course of minutes. Here, we investigated novel hypotheses of (i) whether SCF/KIT can regulate MITF-M activity through gene expression as the alternative process, and (ii) whether chemical inhibition of KIT activity can mitigate the acquired pigmentation in skin by targeting the expression of MITF-M. Methods: We employed melanocyte cultures in vitro and pigmented skin samples in vivo, and applied immunoblotting, RT-PCR, siRNA-based gene knockdown and confocal microscopy. Results: The protein and mRNA levels of MITF-M in epidermal melanocytes and the promoter activity of MITF-M in B16-F0 melanoma cells demonstrated that SCF/KIT could trigger the expression of MITF-M de novo, following the phosphorylation-dependent proteolysis of pre-existing MITF-M protein. SCF/KIT regulated the transcription abilities of cAMP-responsive element-binding protein (CREB), CREB-regulated co-activator 1 (CRTC1) and SRY-related HMG-box 10 (SOX10) but not β-catenin at the MITF-M promoter. Meanwhile, chemical inhibition of KIT activity abolished SCF-induced melanin production in epidermal melanocyte cultures, as well as protected the skin from UV-B-induced hyperpigmentation in HRM2 mice or brownish guinea pigs, in which it down-regulated the expression of MITF-M de novo at the promoter level. Conclusion: We propose the targeting of SCF/KIT-inducible MITF-M expression as a strategy in the therapeutics for acquired pigmentary disorders.

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.

Standardization of organoid culture for evaluation of melanogenesis induced by UVB, UVA and visible light

Background

Organoid cultures are primary cultures that maintain architectural characteristics and the relationships between cells, as well as the extracellular matrix. They are alternatives for pathophysiological or therapeutic investigation rather than animal and in vitro tests.

Objective

Development of a cutaneous organoid culture model, aiming at the study of radiation-induced melanogenesis.

Method

A validation study, which involved biopsies of the skin of the back of the adult ear. One sample was irradiated with different doses of UVB, UVA, or visible light (VL); the other was maintained in the dark for 72 h. The viability of the tissues was evaluated from the morphological and architectural parameters of the histology, and the expression of the glyceraldehyde-3-phosphate dehydrogenase (GAPDH) gene, by real-time polymerase chain reaction (PCR). The radiation-induced melanin pigmentation was standardized according to the doses of each radiation and evaluated by digital image analysis (Fontana-Masson).

Results

The primary skin culture was standardized at room temperature using DMEM medium. The doses of UVB, UVA, and VL (blue light) that induced differential melanogenesis were: 166 mJ/cm², 1.524 J/cm², and 40 J/cm². The expression of the GAPHD constitutional gene did not differ between the sample of skin processed immediately after tissue collection and the sample cultured for 72 h in the standardized protocol.

Study limitations

This was a preliminary study that evaluated only the viability and integrity of the melanogenic system, and the effect of the radiation alone.

Conclusions

The standardized model maintained viable melanocytic function for 72 h at room temperature, allowing the investigation of melanogenesis induced by different forms of radiation.

The Role of Stem Cell Factor in Hyperpigmented Skin Lesions

BACKGROUND

Skin hyperpigmentation usually results from an increased number, or activity, of melanocytes. The degree of pigmentation of skin depends on the amount and type of melanin, degree of skin vascularity, presence of carotene, and thickness of the stratum corneum. Common causes of hyperpigmentation include post-inflammatory hyperpigmentation, melasma, solar lentigines, ephelides (freckles), and café-au-lait macules. Some skin tumors can be hyperpigmented as basal cell carcinoma (BCC), squamous cell carcinoma (SCC) and malignant melanoma (MM). Stem cell factor (SCF) is a growth factor and its interaction with its receptor, c-kit, is well known to be critical to the survival of melanocytes.

METHODS

This study was carried out on 60 patients complaining of hyperpigmented skin lesions (20 melasma, 20 solar lentigines, and 20 freckles) and 36 patients with skin tumors (14 BCC, 12 SCC, and 10 MM). Punch skin biopsies were taken from the previous lesions. Immunohistochemical staining of these samples was done using the stem cell factor (SCF).

RESULTS

There was positive expression of SCF in all cases of melasma, solar lentigines and freckles with significant increase in the intensity of expression in the lesional areas than the non-lesional ones (P=0.004). There was also a statistically significant increase in the expression of SCF in BCC and melanoma tumor cells.

CONCLUSION

SCF has a great role in skin hyperpigmented disorders and this can be used as a target for the developing of new antipigmentary lines of treatment by inhibiting SCF. SCF can also be involved in the emergence of some skin tumors.

Epidermal keratin 5 expression and distribution is under dermal influence

Human skin melanin pigmentation is regulated by systemic and local factors. According to the type of melanin produced by melanocytes, the transfer and degradation of melanosomes differ, thus accounting for most variations between ethnicities. We made the surprising observation that in a drastically changed environment, white and black phenotypes are reversible since Caucasian skin grafted onto nude mice can become black with all black phenotypic characteristics. Black xenografts differed essentially from other grafts by the levels of epidermal FGF-2 and keratin 5. In vitro analysis confirmed that FGF-2 directly regulates keratin 5. Interestingly, this phenomenon may be involved in human pathology. Keratin 5 mutations in Dowling-Degos Disease (DDD) have already been associated with the pheomelanosome-eumelanosome transition. In a DDD patient, keratin 5 was expressed in the basal and spinous layers, as observed in black xenografts. Furthermore, in a common age-related hyperpigmentation disorder like senile lentigo (SL), keratin 5 distribution is also altered. In conclusion, modulation of keratin 5 expression and distribution either due to mutations or factors may account for the development of pigmentary disorders.

A challenging case of pigmented Bowen's disease and differential diagnosis of pagetoid pigmented skin lesions

Differentiation of pagetoid cutaneous neoplasms can be very challenging on hematoxylin and eosin-stained sections.

We report a singular case of pigmented pagetoid Bowen’s disease showing transitional features between extramammary Paget’s disease and in situ squamous cell carcinoma.

Protective Effect of Botulinum Toxin against Ultraviolet-Induced Skin Pigmentation

BACKGROUND

Hyperpigmentation following ultraviolet irradiation has cosmetic concerns. Botulinum toxin type A can favorably affect skin pigmentation. However, the mechanism of skin pigmentation is unclear.

METHODS

In vitro, human epidermal melanocytes were co-cultured with human keratinocytes. After cells were treated with botulinum toxin type A, cell morphology, proliferation, and dendricity were analyzed, and immunofluorescence, tyrosinase activity, and melanin contents were determined. To evaluate the effect of botulinum toxin type A on ultraviolet B-irradiated mouse skin, ultraviolet B alone was applied to one side of the back of each mouse as a control, whereas ultraviolet B plus injection of botulinum toxin type A was applied to the contralateral side. Skin pigmentation, histology, and the number of dihydroxyphenylalanine-positive melanocytes were evaluated. The L* colorimeter value was measured. Enzyme-linked immunosorbent assay determinations of basic fibroblast growth factor, interleukin-1 alpha, and prostaglandin E2 were performed.

RESULTS

Immunohistochemical staining revealed botulinum toxin type A in the cytoplasm of melanocytes and in the positive control. In vitro, melanocyte dendricity and melanin contents were decreased slightly but significantly (p < 0.05) after botulinum toxin type A treatment. In vivo, botulinum toxin type A suppressed skin pigmentation. The number of dihydroxyphenylalanine-positive melanocytes was also significantly lower than in the control side. Tyrosinase activity and melanin content were also significantly reduced (p < 0.05). Botulinum toxin type A also significantly reduced the amounts of basic fibroblast growth factor, interleukin-1 alpha, and prostaglandin E2 (all p < 0.05).

CONCLUSION

Botulinum toxin type A can suppress epidermal melanogenesis through both direct and indirect mechanisms.

Effect of the Stromal Vascular Fraction on Changes in Melanin Formation in B16 Cells Treated by IBMX

OBJECTIVE

To investigate the effect of the stromal vascular fraction (SVF) on changes in melanin formation and tyrosinase activity in B16 cells treated by 3-isobutyl-1 methylxanthine (IBMX) and to explore the mechanism of SVF-mediated inhibition of pigmentation.

METHODS

We co-cultured extracted SVFs and B16 cells treated with IBMX in a certain proportion, and the marker molecule HMB-45 was detected by immunochemistry. Melanin content was determined by NaOH lysis. Activity of tyrosinase was measured by the DOPA oxidation method.

RESULTS

HMB-45 was commonly expressed in B16 cells induced by IBMX. After the addition of SVFs, the expression of HMB-45 decreased significantly and positively correlated with increases in SVFs. After the induction of B16 cells by IBMX, melanin content increased significantly. However, melanin decreased after SVF and B16 co-culturing; the effect was more substantial with the increase and decrease in SVFs, and the activity of tyrosinase decreased.

CONCLUSION

SVFs inhibit the production of melanin and reduce the activity of tyrosinase, possibly providing a new breakthrough for the treatment of pigment disorders.

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