Role of interleukin-6 and endothelin-1 receptors in enhanced melanocyte dendricity of facial spots and suppression of their ligands by niacinamide and tranexamic acid.

BACKGROUND: Hyperpigmented spots are common issues in all ethnicities with a hallmark characteristic of increased melanocyte dendricity. OBJECTIVES: To determine (1) potential receptors and/or cytokines that are involved in increased melanocyte dendricity in multiple facial spot types; (2) treatment effects of skin-lightening compounds on identified cytokine release from keratinocytes and on dendricity in melanocytes. METHODS: Facial spots (melasma, solar lentigo, acne-induced post-inflammatory hyperpigmentation) and adjacent non-spot skin biopsies were collected from Chinese women (age 20-70). The epidermal supra and basal layers were laser dissected to enrich keratinocyte or melanocyte biology respectively for transcriptome analysis. Melanocyte dendricity was assessed histologically by immunofluorescent staining. Effect of interleukin-6 (IL-6) and endothelin-1 (ET-1) on melanocyte dendricity and melanosome transfer were assessed in human melanocytes or melanocyte-keratinocyte co-culture models. Treatment effects of skin-lightening compounds (niacinamide, tranexamic acid [TxA], sucrose laurate/dilaurate mixture [SDL]) were assessed on IL-6 or ET-1 release from keratinocytes and on dendricity in melanocytes. RESULTS: Transcriptome analysis revealed IL-6 receptor and ET-1 receptor were significantly upregulated compared to the adjacent normal skin, visually confirmed at the protein level through immunostaining. Melanocytes in spot areas are more dendritic than melanocytes in adjacent non-spot skin. The addition of IL-6 and ET-1 to cell culture models increased melanocyte dendricity and melanosome transfer. IL-6 release was significantly suppressed by niacinamide and its combination, while ET-1 release was significantly reduced by both niacinamide and TxA. In contrast, SDL acted directly upon melanocytes to reduce dendricity. CONCLUSION: Interleukin-6 and ET-1 receptors are significantly upregulated in multiple facial spot types. The in vitro testing demonstrated their respective ligands increased melanocyte dendricity. Tested skin-lightening compounds showed reduction in release of IL-6/ET-1 from epidermal keratinocytes and/or inhibition of melanocyte dendricity. This work sheds light on pathophysiological mechanism of facial spots and potential new mechanisms of these skin-lightening compounds which warrant further human clinical validation.

Tocotrienol-Rich Fraction Attenuates Blue Light-Induced Oxidative Stress and Melanogenesis in B16-F1 Melanocytes via Anti-Oxidative and Anti-Tyrosinase Properties.

Our skin is constantly exposed to blue light (BL), which is abundant in sunlight and emitted by digital devices. Prolonged exposure to BL can lead to oxidative stress-induced damages and skin hyperpigmentation. For this study, we used a cell line-based model to examine the protective effects of tocotrienol-rich fraction (TRF) on BL-induced oxidative stress and hyperpigmentation in B16-F1 melanocytes. Alpha-tocopherol (αTP) was used as a comparator. Molecular assays such as cell viability assay, flow cytometry, western blotting, fluorescence imaging, melanin and tyrosinase analysis were performed. Our results showed that TRF effectively suppressed the formation of reactive oxygen species and preserved the mitochondrial membrane potential. Additionally, TRF exhibited anti-apoptotic properties by reducing the activation of the p38 mitogen-activated protein kinase molecule and downregulating the expression of cleaved caspase-3. Moreover, TRF modulated tyrosinase activity, resulting in a lowered rate of melanogenesis and reduced melanin production. In contrast, αTP did not exhibit significant protective effects against skin damages and pigmentation in BL-induced B16-F1 cells. Therefore, this study indicates that TRF may offer superior protective effects over αTP against the effects of BL on melanocytes. These findings demonstrate the potential of TRF as a protective natural ingredient that acts against BL-induced skin damages and hyperpigmentation via its anti-oxidative and anti-melanogenic properties.

Anti-Melanogenic and Antioxidant Activity of Bifidobacterium longum Strain ZJ1 Extracts, Isolated from a Chinese Centenarian.

Melanin produced by melanocytes protects our skin against ultraviolet (UV) radiation-induced cell damage and oxidative stress. Melanin overproduction by hyperactivated melanocytes is the direct cause of skin hyperpigmentary disorders, such as freckles and melasma. Exploring natural whitening agents without the concern of toxicity has been highly desired. In this study, we focused on a Bifidobacterium longum strain, ZJ1, isolated from a Chinese centenarian, and we evaluated the anti-melanogenic activity of the distinctive extracts of ZJ1. Our results demonstrated that whole lysate (WL) and bacterial lysate (BL) of ZJ1 ferments efficiently reduce α-melanocyte-stimulating hormone (α-MSH)-induced melanin production in B16-F10 cells as well as the melanin content in zebrafish embryos. BL and WL downregulate melanogenesis-related gene expression and indirectly inhibit intracellular tyrosinase activity. Furthermore, they both showed antioxidant activity in a menadione-induced zebrafish embryo model. Our results suggest that ZJ1 fermentation lysates have application potential as therapeutic reagents for hyperpigmentary disorders and whitening agents for cosmetics.

Quercetin 3-O-Galactoside Isolated from Limonium tetragonum Inhibits Melanogenesis by Regulating PKA/MITF Signaling and ERK Activation.

Quercetin 3-O-galactoside (Q3G) is a common dietary flavanol that has been shown to possess several bioactivities, including anti-melanogenesis. However, how Q3G exerts its anti-melanogenic effect has not been studied. The current study, therefore aimed to investigate the anti-melanogenesis potential of Q3G and elucidate the underlying action mechanism in α-melanocyte-stimulating hormone (α-MSH)-induced hyperpigmentation model of B16F10 murine melanoma cells. Results showed that α-MSH stimulation significantly increased tyrosinase (TYR) and melanin production, which were significantly downregulated by Q3G treatment. The treatment with Q3G suppressed the transcriptional and protein expressions of melanogenesis-related enzymes TYR, tyrosinase related protein-1 (TRP-1), and TRP-2, along with the melanogenic transcription factor microphthalmia-associated transcription factor (MITF) in B16F10 cells. It was shown that Q3G downregulated MITF expression and suppressed its transcriptional activity by inhibiting the cAMP-dependent protein kinase A (PKA)-mediated activation of CREB and GSK3ß. In addition, MAPK-regulated MITF activation signaling was also involved in the inhibition of melanin production by Q3G. The results suggest that the anti-melanogenic properties of Q3G rationalize further studies in vivo to confirm its action mechanism and consequent utilization as a cosmetic ingredient against hyperpigmentation.

Histology and clinical imaging lifecycle of black pigment in fibrosis secondary to neovascular age-related macular degeneration.

PURPOSE: Melanotic cells with large spherical melanosomes, thought to originate from retinal pigment epithelium (RPE), are found in eyes with neovascular age-related macular degeneration (nvAMD). To generate hypotheses about RPE participation in fibrosis, we correlate histology to clinical imaging in an eye with prominent black pigment in fibrotic scar secondary to nvAMD. METHODS: Macular findings in a white woman with untreated inactive subretinal fibrosis due to nvAMD in her right eye were documented over 9 years with color fundus photography (CFP), fundus autofluorescence (FAF) imaging, and optical coherence tomography (OCT). After death (age 90 years), this index eye was prepared for light and electron microscopy to analyze 7 discrete zones of pigmentation in the fibrotic scar. In additional donor eyes with nvAMD, we determined the frequency of black pigment (n = 36 eyes) and immuno-labeled for retinoid, immunologic, and microglial markers (RPE65, CD68, Iba1, TMEM119; n = 3 eyes). RESULTS: During follow-up of the index eye, black pigment appeared and expanded within a hypoautofluorescent fibrotic scar. The blackest areas correlated to melanotic cells (containing large spherical melanosomes), some in multiple layers. Pale areas had sparse pigmented cells. Gray areas correlated to cells with RPE organelles entombed in the scar and multinucleate cells containing sparse large spherical melanosomes. In 94% of nvAMD donor eyes, hyperpigmentation was visible. Certain melanotic cells expressed some RPE65 and mostly CD68. Iba1 and TMEM119 immunoreactivity, found both in retina and scar, did not co-localize with melanotic cells. CONCLUSION: Hyperpigmentation in CFP results from both organelle content and optical superimposition effects. Black fundus pigment in nvAMD is common and corresponds to cells containing numerous large spherical melanosomes and superimposition of cells containing sparse large melanosomes, respectively. Melanotic cells are molecularly distinct from RPE, consistent with a process of transdifferentiation. The subcellular source of spherical melanosomes remains to be determined. Detailed histology of nvAMD eyes will inform future studies using technologies for spatially resolved molecular discovery to generate new therapies for fibrosis. The potential of black pigment as a biomarker for fibrosis can be investigated in clinical multimodal imaging datasets.

Permeation enhancer nanovesicles mediated topical delivery of curcumin for the treatment of hyperpigmentation.

The main aim of the present study was to develop curcumin (CUR) loaded permeation enhancer-lipid vesicles for the treatment of hyperpigmentation. Hyperpigmentation is an acquired skin disorder characterized by uneven skin coloration, mainly in the regions of the facial skin, affecting millions of people worldwide. It often occurs in visible areas, hence causing significant negative psychological and social impacts. In the present study, curcumin-loaded permeation enhancer nanovesicles (PE-NVs) were developed by modified ethanol injection method and dimethyl sulfoxide was added as a penetration enhancer. PE-NVs were subjected to various physicochemical characterizations and drug permeation studies across the skin. The PE-NVs were tested for their efficacy in a sunlight-induced hyperpigmented rabbit skin model. Topical application of PE-NVs reduced symptoms of hyperpigmentation as compared with CUR methanolic solution because of higher accumulation because of better permeation into skin layers. Histopathological studies also confirmed the effectiveness of PE-NVs, since they reduced hyperpigmentation-induced lesions. Results confirmed that PE-NVs is a potential drug delivery system for topical administration drugs to treat skin-associated inflammatory disorders.

Atraric Acid Ameliorates Hyperpigmentation through the Downregulation of the PKA/CREB/MITF Signaling Pathway.

Atraric acid (AA) is derived from lichens and is widely used in perfumes for its desirable scent. It has been reported as having anti-inflammatory and antioxidant activity. Hyperpigmentation is the underlying cause of a variety of dermatological diseases that have a significant impact on patients' quality of life and are frequently difficult to treat. This study aimed to explore the inhibitory effects of AA on hyperpigmentation in vitro and in vivo and its potential molecular mechanisms. The cytological results revealed that at a dose of 250 µM, AA may reduce melanin content and tyrosinase levels without causing cytotoxicity. Furthermore, the expression of melanocortin-1 receptor (MC1R), phosphorylated protein kinase A (pPKA) and phosphorylated cAMP response element binding protein (pCREB) were downregulated in AA-administrated cells. In vivo, histological analysis showed that AA could inhibit melanin production and tyrosinase activity, and 3% AA had the best activity, with almost no side effects. Furthermore, the results of Western blot analysis and RT-PCR suggested that AA may suppress the mRNA transcription of microphthalmia-associated transcription factor (MITF) protein and tyrosine protease by decreasing the expression of MC1R, consequently decreasing the phosphorylation of PKA and CREB. Finally, the MC1R inhibitor MSG606 verified the hypothesis that AA suppresses melanin formation by downregulating the PKA/CREB/MITF signaling pathway. Taken together, our study offers valuable information for the development of AA as a possible ingredient in skin-lightening cosmeceuticals and hyperpigmentation inhibitors.

New Butyroside D from Argan Press Cake Possess Anti-Melanogenesis Effect via MITF Downregulation in B16F10 and HEM Cells.

Hyperpigmentation is a skin condition where patches of skin become darker in color due to excess melanin production upon UV exposure leading to melasma, which are lentigines or post inflammatory hyperpigmentation that psychologically affecting a great number of people. The present study investigates the anti-melanogenic effect of Butyroside D and the underling mechanism. After the confirmation of the non-cytotoxic effect of Butyroside D on B16F10 cells, we proceeded with analyzing the impact of the treatment at low and high concentration (i.e., 0.2 µM and 2 µM) using gene profiling analysis and examined the differentiation in gene expression. Our results identify cyclic adenosine monophosphate (cAMP), Wnt/ß-catenin and Mitogen-Activated Protein Kinase (MAPK) signaling pathways to be downregulated upon treatment with Butyroside D. These pathways were targeted to further validate the effect of Butyroside D on membrane receptors melanocortin 1 receptor (MC1R) and receptor tyrosine kinase (c-Kit), related microphthalmia-associated transcription factor (MITF) and consequently tyrosinase (TYR), and tyrosine-related protein-1 (TYRP-1) that were all shown to be downregulated and, therefore, leading to the repression of melanin biosynthesis. Finally, the anti-melanogenic effect of Butyroside D was confirmed on human epidermal melanocytes (HEM) cells by inhibiting the activation of cAMP pathway generally mediated through α-melanocyte-stimulating hormone (α-MSH) and MC1R. Overall, this study suggests the potential applicability of this purified compound for the prevention of hyperpigmentation conditions.

BCI-215, a Dual-Specificity Phosphatase Inhibitor, Reduces UVB-Induced Pigmentation in Human Skin by Activating Mitogen-Activated Protein Kinase Pathways.

BACKGROUND: The dysregulation of melanin production causes skin-disfiguring ultraviolet (UV)-associated hyperpigmented spots. Previously, we found that the activation of c-Jun N-terminal kinase (JNK), a mitogen-activated protein kinase (MAPK), inhibited melanogenesis. METHODS: We selected BCI-215 as it may modify MAPK expression via a known function of a dual-specificity phosphatase (DUSP) 1/6 inhibitor. B16F10 melanoma cells, Mel-ab cells, human melanocytes, and a coculture were used to assess the anti-melanogenic activity of BCI-215. The molecular mechanisms were deciphered by assaying the melanin content and cellular tyrosinase activity via immunoblotting and RT-PCR. RESULTS: BCI-215 was found to suppress basal and cAMP-stimulated melanin production and cellular tyrosinase activity in vitro through the downregulation of microphthalmia-associated transcription factor (MITF) protein and its downstream enzymes. The reduction in MITF expression caused by BCI-215 was found to be due to all three types of MAPK activation, including extracellular signal-regulated kinase (ERK), JNK, and p38. The degree of activation was greater in ERK. A phosphorylation of the ß-catenin pathway was also demonstrated. The melanin index, expression of MITF, and downstream enzymes were well-reduced in UVB-irradiated ex vivo human skin by BCI-215. CONCLUSIONS: As BCI-215 potently inhibits UV-stimulated melanogenesis, small molecules of DUSP-related signaling modulators may provide therapeutic benefits against pigmentation disorders.

Radiofrequency Irradiation Mitigated UV-B-Induced Skin Pigmentation by Increasing Lymphangiogenesis.

Dermal macrophages containing melanin increase skin pigmentation since dermal melanin removal is slower than epidermal melanin removal. Lymphatic vessels are also involved in melanin clearance. We evaluated whether radiofrequency (RF) irradiation induced an increase in HSP90, which promotes lymphangiogenesis by activating the BRAF/MEK/ERK pathway and decreasing tyrosinase activity, in the UV-B exposed animal model. The HSP90/BRAF/MEK/ERK pathway was upregulated by RF. Tyrosinase activity and the VEGF-C/VEGFR 3/PI3K/pAKT1/2/pERK1/2 pathway, which increase lymphangiogenesis, as well as the expression of the lymphatic endothelial marker LYVE-1, were increased by RF. Additionally, the number of melanin-containing dermal macrophages, the melanin content in the lymph nodes, and melanin deposition in the skin were decreased by RF. In conclusion, RF increased HSP90/BRAF/MEK/ERK expression, which decreased tyrosinase activity and increased lymphangiogenesis to eventually promote the clearance of dermal melanin-containing macrophages, thereby decreasing skin pigmentation.

Dimethyl Itaconate Reduces α-MSH-Induced Pigmentation via Modulation of AKT and p38 MAPK Signaling Pathways in B16F10 Mouse Melanoma Cells.

Dimethyl itaconate (DMI) exhibits an anti-inflammatory effect. Activation of nuclear factor erythroid 2-related factor 2 (NRF2) is implicated in the inhibition of melanogenesis. Therefore, DMI and itaconic acid (ITA), classified as NRF2 activators, have potential uses in hyperpigmentation reduction. The activity of cyclic adenosine monophosphate (cAMP) response element-binding protein (CREB), an important transcription factor for MITF gene promoter, is regulated by glycogen synthase kinase 3ß (GSK3ß) and protein kinase A (PKA). Here, we investigated the inhibitory effect of ITA and DMI on alpha-melanocyte-stimulating hormone (α-MSH)-induced MITF expression and the modulatory role of protein kinase B (AKT) and GSK3ß in melanogenesis in B16F10 mouse melanoma cells. These cells were incubated with α-MSH alone or in combination with ITA or DMI. Proteins were visualized and quantified using immunoblotting and densitometry. Compared to ITA, DMI treatment exhibited a better inhibitory effect on the α-MSH-induced expression of melanogenic proteins such as MITF. Our data indicate that DMI exerts its anti-melanogenic effect via modulation of the p38 mitogen-activated protein kinase (MAPK) and AKT signaling pathways. In conclusion, DMI may be an effective therapeutic agent for both inflammation and hyperpigmentation.

Molecular modeling and phenoloxidase inhibitory activity of arbutin and arbutin undecylenic acid ester.

Excessive melanin formation has been linked to various skin disorders such as hyperpigmentation and skin cancer. Tyrosinase is the most prominent target for inhibitors of melanin production. In this study, we investigated whether arbutin and its prodrug, arbutin undecylenic acid ester, might inhibit phenoloxidase (PO), a tyrosinase-like enzyme. Molecular docking simulation results suggested that arbutin and arbutin undecylenic acid ester can bind to the substrate-binding pocket of PO. Arbutin undecylenic acid ester with an IC50 6.34 mM was effective to inhibit PO compared to arbutin (IC50 29.42 mM). In addition, arbutin undecylenic acid ester showed low cytotoxicity in Drosophila S2 cells and the compound inhibited the melanization reaction. Therefore, the results of this study have demonstrated that arbutin undecylenic acid ester as a potential inhibitor of PO. We successfully designed a new platform utilizing Drosophila melanogaster and Bombyx mori as animal models propounding fast, cheap, and high effectiveness in method to screen tyrosinase inhibitors.

Novel Chemically Modified Curcumin (CMC) Analogs Exhibit Anti-Melanogenic Activity in Primary Human Melanocytes.

Hyperpigmentation is a dermatological condition characterized by the overaccumulation and/or oversecretion of melanin pigment. The efficacy of curcumin as an anti-melanogenic therapeutic has been recognized, but the poor stability and solubility that have limited its use have inspired the synthesis of novel curcumin analogs. We have previously reported on comparisons of the anti-melanogenic activity of four novel chemically modified curcumin (CMC) analogs, CMC2.14, CMC2.5, CMC2.23 and CMC2.24, with that of parent curcumin (PC), using a B16F10 mouse melanoma cell model, and we have investigated mechanisms of inhibition. In the current study, we have extended our findings using normal human melanocytes from a darkly pigmented donor (HEMn-DP) and we have begun to study aspects of melanosome export to human keratinocytes. Our results showed that all the CMCs downregulated the protein levels of melanogenic paracrine mediators, endothelin-1 (ET-1) and adrenomedullin (ADM) in HaCaT cells and suppressed the phagocytosis of FluoSphere beads that are considered to be melanosome mimics. All the three CMCs were similarly potent (except CMC2.14, which was highly cytotoxic) in inhibiting melanin production; furthermore, they suppressed dendricity in HEMn-DP cells. CMC2.24 and CMC2.23 robustly suppressed cellular tyrosinase activity but did not alter tyrosinase protein levels, while CMC2.5 did not suppress tyrosinase activity but significantly downregulated tyrosinase protein levels, indicative of a distinctive mode of action for the two structurally related CMCs. Moreover, HEMn-DP cells treated with CMC2.24 or CMC2.23 partially recovered their suppressed tyrosinase activity after cessation of the treatment. All the three CMCs were nontoxic to human dermal fibroblasts while PC was highly cytotoxic. Our results provide a proof-of-principle for the novel use of the CMCs for skin depigmentation, since at low concentrations, ranging from 5 to 25 µM, the CMCs (CMC2.24, CMC2.23 and CMC2.5) were more potent anti-melanogenic agents than PC and tetrahydrocurcumin (THC), both of which were ineffective at melanogenesis at similar doses, as tested in HEMn-DP cells (with PC being highly toxic in dermal fibroblasts and keratinocytes). Further studies to evaluate the efficacy of CMCs in human skin tissue and in vivo studies are warranted.

A New Insight into the Potential Role of Tryptophan-Derived AhR Ligands in Skin Physiological and Pathological Processes.

The aryl hydrocarbon receptor (AhR) plays a crucial role in environmental responses and xenobiotic metabolism, as it controls the transcription profiles of several genes in a ligand-specific and cell-type-specific manner. Various barrier tissues, including skin, display the expression of AhR. Recent studies revealed multiple roles of AhR in skin physiology and disease, including melanogenesis, inflammation and cancer. Tryptophan metabolites are distinguished among the groups of natural and synthetic AhR ligands, and these include kynurenine, kynurenic acid and 6-formylindolo[3,2-b]carbazole (FICZ). Tryptophan derivatives can affect and regulate a variety of signaling pathways. Thus, the interest in how these substances influence physiological and pathological processes in the skin is expanding rapidly. The widespread presence of these substances and potential continuous exposure of the skin to their biological effects indicate the important role of AhR and its ligands in the prevention, pathogenesis and progression of skin diseases. In this review, we summarize the current knowledge of AhR in skin physiology. Moreover, we discuss the role of AhR in skin pathological processes, including inflammatory skin diseases, pigmentation disorders and cancer. Finally, the impact of FICZ, kynurenic acid, and kynurenine on physiological and pathological processes in the skin is considered. However, the mechanisms of how AhR regulates skin function require further investigation.

The deregulation of NOTCH pathway, inflammatory cytokines, and keratinization genes in two Dowling-Degos disease patients with hidradenitis suppurativa.

Dowling-Degos disease (DDD) is a rare autosomal-dominant genodermatosis and it has been associated with hidradenitis suppurativa (HS). Deregulation of NOTCH pathway has been linked to the development of HS in DDD context (DDD-HS). However, molecular alterations in DDD-HS, including altered gene expression of NOTCH and downstream effectors that are involved in the follicular differentiation and inflammatory response, are poorly defined. We report two cases of patients diagnosed with DDD-HS, one of those, under Adalimumab treatment. Our results have shown downregulation of NOTCH1/NCSTN pathway, distinct molecular profiles of inflammatory cytokines (IL23A and TNF), and a novel aberrant upregulation of genes involved in the cornified envelope (CE) formation (SPRR1B, SPRR2D, SPRR3, and IVL) in paired HS lesions of two DDD patients.

Light and electron microscopy of chlorpromazine-induced hyperpigmentation.

Chlorpromazine may induce abnormal skin hyperpigmentation in exposed areas, described as slate-gray, purple, or blue-grayish discoloration. A 58-year-old man with schizophrenia, had been taking chlorpromazine for 5 years, and his sun-exposed skin areas exhibited a blue-grayish color. Large deposits of brown pigment and granular basophilic material were seen in the dermis with light microscopy. HMB-45 and anti-Melan-A antibody immunostaining labeled some pigment in the dermis. Transmission electron microscopy identified deposits among dermal collagen bundles collagen in both transverse and longitudinal sections. In the latter, an arboriform aspect of deposits was quite clear, and some melanophages were also seen. The three-dimensional examination of the dermis with scanning electron microscopy also identified deposits, which at higher magnification demonstrated an appearance in the shape of leaves, grass-like, interspersed with normal collagen. These results suggest a complex pathogenic mechanism, including deposition of dermal melanin together with drug itself and potentially additional unknown metabolites.

Palladium causes bizarre skin hyperpigmentation in long-term dihydrocodeinone 'Braun' abusers.

BACKGROUND: 'Braun' is an illegal injectable dihydrocodeinone-enriched drug mixture of semi-synthetic opioids. It is prepared by palladium-catalysed hydrogenation from codeine-containing tablets. OBJECTIVE: We aimed to characterize the dermatologic consequences of long-term abuse of 'Braun'. METHODS: Skin biopsies of two long-term 'Braun' abusers were evaluated histopathologically, immunohistochemically and ultrastructurally. Palladium skin content was assessed by X-ray fluorescence (XRF) spectrometry. RESULTS: Both patients showed generalized diffuse dark blue-grey hyperpigmentation of the skin. In both, an abnormal population of cells containing intracytoplasmic brownish granular material was identified in the papillary dermis by light microscopy. Electron microscopy revealed a dense and minimally structured material that predominantly accumulated in macrophages, fibroblasts and vascular endothelial cells. XRF analysis confirmed elevated levels of palladium in the patient's skin in comparison to healthy controls. CONCLUSION: Long-term abuse of palladium-contaminated dihydrocodeinone ('Braun') results in excessive accumulation of granular material in various dermal cell types and causes generalized diffuse skin hyperpigmentation.

Low-fluence Q-switched Nd:YAG 1064-nm laser versus Q-switched Nd:YAG 532-nm laser in the treatment of hyperpigmented lips: a prospective, randomized, controlled, evaluator-blinded trial.

Lip hyperpigmentation is an esthetic problem. Clinical data from controlled comparative studies is insufficient to support the efficacy of laser treatments for hyperpigmented lips. This study is aimed to compare the efficacy of low-fluence Q-switched Nd:YAG 1064-nm laser (LFQS 1064-nm) versus Q-switched Nd:YAG 532-nm laser (QS 532-nm) for the treatment of hyperpigmented lips. A randomized, controlled, evaluator-blinded study was conducted in thirty subjects. They were randomized into 2 groups. The first group was treated with five treatment sessions with a 2-week interval of LFQS 1064-nm laser while the second group was treated with a single session of QS 532-nm laser. The evaluation was conducted at baseline, 2 weeks of each post treatment, and 4 weeks after the last treatment session. The efficacy was assessed by melanin index, Methuen colored plate, photographic evaluation, pain score, patient's satisfaction, and patient's Dermatology Life Quality Index. The adverse effects were also recorded. All patients attained throughout the study protocol. The most frequent fluence applied was 2.4 J/cm2 (2.2-2.5 J/cm2) and 2.0 J/cm2 (1.7-2.4 J/cm2) in the LFQS 1064-nm group and QS 532-nm group, respectively. The results of the QS 532-nm group showed greater percentage of melanin index reduction and better average mean of photographic evaluation percentage changes from the baseline than the LFQS 1064-nm group (p < 0.001 and p < 0.001, respectively). The adverse effects were less likely to occur in the LFQS 1064-nm group. Few cases of scale, hypopigmentation, bleb formation, postinflammatory hyperpigmentation, and labial edema occurred only in the QS 532-nm group.

A Novel Method for Visualizing Melanosome and Melanin Distribution in Human Skin Tissues.

Melanin incorporated into keratinocytes plays an important role in photoprotection; however, abnormal melanin accumulation causes hyperpigmentary disorders. To understand the mechanism behind the accumulation of excess melanin in the skin, it is essential to clarify the spatial distribution of melanosomes or melanin in the epidermis. Although several markers have been used to detect melanosomes or melanin, no suitable markers to determine the precise localization of melanin in the epidermis have been reported. In this study, we showed that melanocore-interacting Kif1c-tail (M-INK), a recently developed fluorescent probe for visualizing mature melanosomes, binds to purified melanin in vitro, and applied it for detecting melanin in human skin tissues. Frozen skin sections from different phototypes were co-stained for the hemagglutinin (HA)-tagged M-INK probe and markers of melanocytes or keratinocytes, and a wide distribution of melanin was observed in the epidermis. Analysis of the different skin phototypes indicated that the fluorescent signals of HA-M-INK correlated well with skin color. The reconstruction of three-dimensional images of epidermal sheets enabled us to observe the spatial distribution of melanin in the epidermis. Thus, the HA-M-INK probe is an ideal tool to individually visualize melanin (or melanosome) distribution in melanocytes and in keratinocytes in skin tissues.

Carvone Decreases Melanin Content by Inhibiting Melanoma Cell Proliferation via the Cyclic Adenosine Monophosphate (cAMP) Pathway.

Melanin, which determines the color of the skin and hair, is initially synthesized to protect the skin from ultraviolet light; however, excessive melanin pigmentation caused by abnormal cell proliferation can result in various melanocytic lesions. Cyclic adenosine monophosphate (cAMP) is known to regulate cell cycle progression and consequently to inhibit the division of abnormally proliferating cells. In this work, we aimed to test whether carvone, a scent compound from plants, inhibits proliferation and subsequently reduces melanin content of melanoma cells and to determine whether its beneficial effects are mediated by the cAMP pathway. We found that carvone decreases melanin content and inhibits melanoma cell proliferation in a concentration-dependent manner. Meanwhile, it inhibited the activation of cell cycle-associated proteins such as cyclin-dependent kinase 1 (CDK1). Of note, the beneficial effects of carvone were abrogated by cAMP inhibition. Our findings indicate potential benefits of carvone for the treatment of melanomas and presumably other hyperpigmentation-related dermatological disorders such as melasmas, lentigines, and excessive freckles.