The protective role of melanin against UV damage in human skin

Silva C, Pedersen AG, Agger JW. Classification of polyphenol oxidases shows ancient gene duplication leading to two distinct enzyme types

Polyphenol oxidases (PPOs) are coupled binuclear copper proteins that catalyze the oxidation of phenols. New functions of PPOs are continuously being discovered, latest with several fungal o-methoxy phenolases, which are active on lignin-derived compounds. Here, we perform a comprehensive phylogenetic analysis of PPOs from a wide taxonomic origin and define 12 PPO groups. We find that a deep gene duplication has led to two distinct PPO types. Type 1 includes PPOs from chordates and molluscs, as well as the fungal o-methoxy phenolases. Type 2 includes plant PPOs, molluscan hemocyanins, and fungal tyrosinases. Most of the type 2 proteins have a C-terminal shielding domain and a thioether bond in the copper-binding site. We also find that most ascomycetes contain high numbers of the PPO type 1 that includes the o-methoxy phenolases, which may indicate a role in the lignin conversion strategy of these fungi.

Advances in aggregation-induced emission luminogens for biomedicine: From luminescence mechanisms to diagnostic applications

Advancements in early detection have demonstrated the significance of biomarkers as indicators of health and disease. Traditional detection methods often face limitations, such as low sensitivity and time consumption. Fluorescence-based techniques are considered promising approaches because of their noninvasiveness and rapid response. However, these conventional methods have some drawbacks, such as low quantum yield, photobleaching, and aggregation-caused quenching. Recently, aggregation-induced emission (AIE) has emerged as a potential alternative, characterized by luminous emission upon aggregation, thus improving detection sensitivity and stability. This review explores the recent advancements in AIE luminogens (AIEgens) in biomedical engineering, with a particular focus on their application in biomarker detection. Here, we discuss the different types of AIE mechanisms and their advantages in disease diagnosis and imaging. In addition, we summarize the development of various AIEgen-based probes for the detection of diverse biomarkers. Finally, we address the remaining challenges and future directions for AIE materials in modern biomedical engineering, emphasizing the potential of AIEgens in biomarker detection and disease diagnosis strategies.

Genetic determinants of skin ageing: a systematic review and meta-analysis of genome-wide association studies and candidate genes

BACKGROUND

Skin ageing is influenced by complex genetic factors. Various phenotypes such as wrinkling, pigmentation changes, and skin cancers have been linked to specific genetic loci. However, the underlying genetic mechanisms and pathways remain poorly understood. This systematic review and meta-analysis aims to summarise the genetic loci found to be associated with skin ageing phenotypes by published genome-wide association studies (GWAS) and candidate gene studies. We also evaluated the overall association of loci via meta-analysis and identified the association patterns to explore potential biological pathways contributing to skin ageing. The Web of Science, Embase, and PubMed databases were searched on January 2024 using specific exclusion criteria (e.g., study of non-human subjects, focus on skin diseases, or treatments) to identify relevant articles. There did not appear to be any significant publication bias observed across the all phenotypes.

MAIN BODY

A total of 48 studies were included, revealing 30 loci that were confirmed to be associated with skin ageing by multiple studies (e.g., AFG3L1P: odds ratio 1.133 95% confidence interval [1.044, 1.222]; BPIFA3: 1.859 [1.567, 2.151]; CLPTML1: 1.164 [1.0.99, 1.229]; CPNE7: 0.905 [0.852-0.958]; DEF8: 1.186 [1.042, 1.331]; IRF4: 1.260 [1.025, 1.495]; MYO16: 2.303 [1.697, 2.908]; PRDM16: 1.105 [1.084, 1.127]; RORA: 1.391 [1.206, 1.577]; SPG7: 0.922 [0.897, 0.947]; SPON1: 2.214 [1.204, 3.225]; SPTLC1: 1.464 [1.432, 1.495]; TYR: 1.175 [1.007, 1.343]). The lack of significance for many loci may be due to studies analysing different SNPs within the same locus, weakening the overall associations. Several loci were associated with specific phenotypic categories (e.g., skin colour related, skin cancer related, wrinkling and sagging related), suggesting shared biological pathways are involved in the pathogenesis of different skin ageing phenotypes. This pattern was also observed in several of the loci that do not have a significant overall association with skin ageing.

CONCLUSION

Despite significant heterogeneity among the included studies and the use of subjective visual methods for phenotype assessment, our review highlights the critical role of fundamental biological processes, such as development and cellular organisation, in skin ageing. Future research that targets the same SNP across multiple populations could strengthen the association of additional loci with skin ageing. Further investigation into these underlying biological processes would significantly advance our understanding of the pathogenesis of skin ageing phenotypes.

Targeting the gut-skin axis by food-derived active peptides ameliorates skin photoaging: a comprehensive review

Food-derived active peptides (FDAPs) are a class of peptides that exert antioxidant, anti-inflammatory, anti-aging and other effects. In recent years, active peptides from natural foods have been reported to improve skin photoaging, but their mechanisms have not been summarized to date. In this review, we focused on the preparation of FDAPs, their mechanisms of photoaging, and their function against photoaging through the gastrointestinal barrier. Furthermore, the latest progress on FDAPs in the prevention and treatment of skin photoaging via the gut-skin axis is summarized and discussed. FDAPs can be directly absorbed into the gastrointestinal tract and enter skin tissues to exert anti-photoaging effects; they can also regulate the gut microbiota, leading to changes in metabolites to ameliorate light-induced skin aging. Future work needs to focus on the delivery system and clinical validation of anti-photoaging peptides to provide solutions or suggestions for improving photoaging.

IL-7 secreted by keratinocytes induces melanogenesis via c-kit/MAPK signaling pathway in Melan-a melanocytes

Abnormal melanin synthesis within melanocytes can result in pigmentary skin disorders. Although pigmentation alterations associated with inflammation are frequently observed, the precise reason for this clinical observation is still unknown. More specifically, although many cytokines are known to be critical for inflammatory skin processes, it is unclear how they affect epidermal melanocyte function. Here, we wanted to see how IL-7, a type I cytokine, affects melanocytes because cytokine is known to be associated with various skin diseases. To this end, Melan-a melanocytes were tested for expression of the IL-7 receptor α (IL-7Rα) and common gamma chain (γc) and their response to IL-7. IL-7 promotes melanogenesis in Melan-a melanocytes, resulting in increased intracellular tyrosinase activity and melanin content. It also upregulates the transcription of melanogenesis-related genes like MITF, tyrosinase, TRP1, and TRP2. IL-7 receptor α (IL-7Rα) and common gamma chain (γc) are interacted with c-kit in Melan-a melanocytes. IL-7 also activates the phosphorylated c-kit and its downstream target genes, such as ERK1/2, JNK, and p38 phosphorylation in Melan-a melanocytes. Furthermore, inhibition of c-kit by ISCK03, c-kit inhibitor, significantly reversed c-kit phosphorylation and MITF expression. We also showed that IL-7 induces melanogenesis via the c-kit/MAPK signaling pathway based on the findings of this study. In conclusion, Melan-a melanocytes express IL-7 receptors on their surface, and IL-7 treatment on Melan-a cells leads to melanogenesis via the c-kit/MAPK signaling pathway. These results could lead to new treatments for pigmentation disorders and provide insight into the immunological processes surrounding melanocytes.

Periocular Aging Across Populations and Esthetic Considerations: A Narrative Review

As the face ages, the skin, fat, muscle, and fascia descend, and the underlying bone, cartilage, and teeth may lose mass. Oculofacial aging is a multifactorial process that is influenced by genetic, environmental, and lifestyle factors. This review summarizes the patterns of oculofacial aging that are observed across populations, including variations in periorbital hollowing, eyelid ptosis, and skin elasticity. Evidence indicates significant variability in aging patterns between sex- and race-based subgroups. Nonetheless, there remains a paucity of research on the progression of aging in some under-studied demographic groups. Signs of oculofacial aging often become apparent to patients well before these changes reach full maturity in later years, leading many to seek early esthetic interventions. Others may present with more advanced signs of aging, motivating a diverse range of therapeutic options. We discuss minimally invasive esthetic interventions to mitigate the signs of aging, which may include botulinum toxin injections, dermal fillers, applied energy-based treatments (e.g., lasers), and emerging techniques such as micro-focused ultrasound and platelet-rich plasma therapies. We review evidence on outcomes related to patient satisfaction and quality of life following esthetic interventions for oculofacial aging. Finally, we outline ethical considerations and challenges faced with the delivery of esthetic surgery, including treatment complications and the influence of social media. This review provides a comprehensive overview of oculofacial aging patterns, its management, and important considerations for the provision of esthetic oculofacial treatment.

Keratin intermediate filaments mechanically position melanin pigments for genome photoprotection

Melanin pigments block genotoxic agents by positioning on the sun-exposed side of human skin keratinocytes' nucleus. How this position is regulated and its role in genome photoprotection remains unknown. By developing a model of human keratinocytes internalizing extracellular melanin into pigment organelles, we show that keratin 5/14 intermediate filaments mechanically control the 3D perinuclear position of pigments, shielding DNA from photodamage. Imaging and microrheology in human disease-related model identify structural keratin cages surrounding pigment organelles to stiffen their microenvironment and maintain their 3D position. Optimum pigment spatialization is required for DNA photoprotection and rely on the interplay between intermediate filaments and microtubules bridged by plectin cytolinkers. Thus, the mechanically-driven proximity of pigment organelles to the nucleus is a key photoprotective parameter. Uncovering how human skin counteracts solar radiation by positioning the melanin microparasol next to the genome anticipates that dynamic spatialization of organelles is a physiological UV stress response.

Lipidomic and Instrumental Evaluation of a Melatonin-Based In & Out Strategy Versus Topical Treatment in Skin Aging: A Randomized Prospective Trial

This study aimed to evaluate the efficacy of a novel "In & Out" strategy, combining topical and oral melatonin supplementation, in managing skin aging compared to topical treatment alone. A randomized, prospective study was conducted on 39 healthy females aged 55-69 years. Participants were divided into two groups: one received both the topical formula and oral melatonin supplementation (Group A), while the other received a topical melatonin-based formula (Group B). Clinical evaluations included lipidomic analysis, skin moisturization, and wrinkle depth analysis at baseline and after 84 days. The addition of oral melatonin supplementation to the topical regimen led to improvements in the skin's lipid profile and moisturization levels. These findings suggest that combining topical and oral melatonin may provide a more comprehensive approach to managing skin aging by addressing both local and systemic factors. Background/Objectives: With age, the endogenous antioxidant capacity of the skin decreases, including melatonin (Mel) synthesis. Skin aging is also associated with alterations in epidermal lipids, particularly a reduction in triglycerides and ceramides, which are essential for maintaining skin structure and hydration. The administration of exogenous melatonin could, therefore, be an effective anti-aging strategy. While some data suggest that melatonin may positively influence the lipid profile, specific data on its effects on skin aging are lacking. This study aimed to evaluate the anti-aging effects of an "In & Out" regimen consisting of a Mel-based cream and dietary supplement in comparison with topical treatment alone, focusing on clinical and lipidomic changes involved in skin homeostasis. Results: A statistically significant variation was observed in both groups compared to baseline (T0) in terms of moisturization (+23.6% in Group A, +18.3% in Group B) and wrinkle depth (-18.5% in Group A, -9.4% in Group B, p < 0.05). Both groups showed improvements in the lipid content of the skin, which typically decreases with age. The "In & Out" strategy resulted in a statistically significant increase in triacylglycerols and ceramides, key lipids that exhibit water-holding properties. Conclusions: The "In & Out" melatonin-based regimen demonstrated greater efficacy in clinical improvement and positive lipid profile modifications compared to topical treatment alone, highlighting its potential as a comprehensive anti-aging strategy.

Inhibition of Melanin Synthesis and Inflammation by Exosomes Derived from Leuconostoc mesenteroides DB-14 Isolated from Camellia japonica Flower

Leuconostoc mesenteroides is a lactic acid bacteria found in fermented products. In our previous study, L. mesenteroides was isolated from Camellia japonica flowers, and its acid tolerance and antibacterial properties were thoroughly investigated. This study focuses on the inhibition of melanin synthesis and inflammation of exosomes derived from L. mesenteroides. Moreover, L. mesenteroides exosomes (DB-14 exosome) exhibited significant inhibitory effects on inflammation and melanogenesis. At concentrations of 4.44 × 108, 8.88 × 108, and 1.78 × 109 particles/ml, the exosomes reduced nitric oxide and prostaglandin E2 activity while maintaining the growth of RAW 264.7 macrophages. In addition, proinflammatory cytokines, such as interleukin (IL)-1β, IL-6, and tumor necrosis factor alpha, were rarely expressed, and western blot revealed that L. mesenteroides DB-14 derived exosomes inhibited inducible nitric oxide synthase and cyclooxygenase-2 expression. Moreover, the exosomes had no toxic effects on B16F10 melanoma cells at concentrations of 1.78 × 109, 3.55 × 109, and 7.10 × 109 particles/ml, and they suppressed melanogenesis by reducing tyrosinase activity. Furthermore, western blot analysis demonstrated that microphthalmia-associated transcription factor (MITF), tyrosinase, tyrosinase related protein (TRP)-1, and TRP-2 were evidently reduced, ultimately repressing melanin production. Moreover, MITF expression was inhibited by reduced mitogen-activated protein kinase and protein kinase B phosphorylation levels. Overall, this study proves the efficacy of the novel DB-14 exosome as a strong lightening and anti-inflammatory agent.

ROS and calcium signaling are critical determinant of skin pigmentation

Pigmentation is a protective phenomenon that shields skin cells from UV-induced DNA damage. Perturbations in pigmentation pathways predispose to skin cancers and lead to pigmentary disorders. These ailments impart psychological trauma and severely affect the patients' quality of life. Emerging literature suggests that reactive oxygen species (ROS) and calcium (Ca2+) signaling modules regulate physiological pigmentation. Further, pigmentary disorders are associated with dysregulated ROS homeostasis and changes in Ca2+ dynamics. Here, we systemically review the literature that demonstrates key role of ROS and Ca2+ signaling in pigmentation and pigmentary disorders. Further, we discuss recent studies, which have revealed that organelle-specific Ca2+ transport mechanisms are critical determinant of pigmentation. Importantly, we deliberate upon the possibility of clinical management of pigmentary disorders by therapeutically targeting ROS generation and cellular Ca2+ handling toolkit. Finally, we highlight the key outstanding questions in the field that demand critical and timely attention. Although an important role of ROS and Ca2+ signaling in regulating skin pigmentation has emerged, the underlying molecular mechanisms remain poorly understood. In future, it would be vital to investigate in detail the signaling cascades that connect perturbed ROS homeostasis and Ca2+ signaling to human pigmentary disorders.

Gain of Protection Afforded by the Methoxypropylamino Cyclohexenylidene Ethoxyethylcyanoacetate (MCE) UVA1 Filter on Pigmentary and Aging Signs: An Outdoor 4-Week Randomized, Intra-Individual Comparative Study in 52 Brazilian Women

BACKGROUND

Conventional sunscreens shield the skin from ultraviolet (UV) rays up to 370 nm leaving wavelengths between 370 and 400 nm unfiltered despite their potentially harmful biological and clinical effects.

OBJECTIVE

The beneficial effects of methoxypropylamino cyclohexenylidene ethoxyethylcyanoacetate (MCE) UVA1 filter were explored at 1% in a SPF50 sunscreen under outdoors summer conditions against pigmentation and aging signs compared against a reference SPF50 without the MCE filter.

MATERIALS AND METHODS

A prospective randomized comparative intra-individual study was conducted in 52 Brazilian women (phototype I-III). A hemiface application was performed for the SPF50 sunscreen with 1% MCE and SPF50 reference without MCE before 1-h outdoor sunlight exposure, twice daily for 4 weeks. Study endpoint included expert panel grading of pigmentation (3), vascular (1) signs as well as facial skin ageing and assessment of facial skin radiance and skin homogeneity by a naïve panel.

RESULTS

Significant differences were reported for all facial signs comparing areas protected with SPF50/MCE and SPF50, respectively: upper lip wrinkles, crow's feet wrinkles, upper lip texture, upper lip pigmentation, vascular abnormalities (all p < 0.0001), texture of the mouth contour (p = 0.001), ptosis of lower face (p = 0.003), lateral facial pigmentation (p = 0.005), and whole face pigmentation (p = 0.01). The evaluations performed by naïve panel showed a significant superiority of the SPF50/MCE product for skin homogeneity (p = 0.043).

CONCLUSION

Overall, this study demonstrates a significant gain of protection with the SPF50 containing 1% MCE in reducing hyperpigmentation, redness and aging signs compared to the same SPF50 sunscreen without MCE, thus supporting the need for an enlarged UVA1 photoprotection.

Full-spectrum cannabidiol reduces UVB damage through the inhibition of TGF-β1 and the NLRP3 inflammasome

The thermodynamic characteristics, antioxidant potential, and photoprotective benefits of full-spectrum cannabidiol (FS-CBD) against UVB-induced cellular death were examined in this study. In silico analysis of CBD showed antioxidant capacity via proton donation and UV absorption at 209.09, 254.73, and 276.95 nm, according to the HAT and SPLET methodologies. FS-CBD protected against UVB-induced bacterial death for 30 min. FS-CBD protected against UVB-induced cell death by 42% (1.5 μg/mL) and 35% (3.5 μg/mL) in an in vitro keratinocyte cell model. An in vivo acute irradiated CD-1et/et mouse model (UVB-irradiated for 5 min) presented very low photoprotection when FS-CBD was applied cutaneously, as determined by histological analyses. In vivo skin samples showed that FS-CBD regulated inflammatory responses by inhibiting the inflammatory markers TGF-β1 and NLRP3. The docking analysis showed that the CBD molecule had a high affinity for TGF-β1 and NLRP3, indicating that protection against inflammation might be mediated by blocking these proinflammatory molecules. This result was corroborated by the docking interactions between CBD and TGF-β1 and NLRP3, which resulted in a high affinity and inhibition of both proteins The present work suggested a FS-CBD moderate photoprotective agent against UVB light-induced skin damage and that this effect is partially mediated by its anti-inflammatory activity.

Tyrosinase Inhibitory Properties of Compounds Isolated from Artocarpus integer Roots

A comprehensive phytochemical investigation of Artocarpus integer root extract led to the isolation of two new geranylated xanthones (1 and 2), one new geranylated flavone (3), one new flavanone (4), and one unique benzopyran (5), along with 16 known compounds. Structures of the new compounds were elucidated by a combination of spectroscopic and computational methods. Two different types of compounds, flavone 12 and arylbenzofuran 19, displayed the most potent antityrosinase activity with IC50 values of 1.7 ± 0.2 and 1.2 ± 0.1 μM, respectively. In addition, kinetic measurements and molecular docking simulations of compounds 12 and 19 were performed and revealed that compound 12 is a competitive inhibitor binding with the tyrosinase active site, while compound 19 is a noncompetitive tyrosinase inhibitor binding the enzyme at the allosteric site.

Photoprotection and antioxidant activity of eumelanin from Streptomyces lasalocidi NTB 42 and its photoprotective effects on Schizosaccharomyces pombe ARC039

This study evaluated the photoprotective and antioxidant properties of eumelanin derived from Streptomyces lasalocidi NTB 42 (eumelanin NTB 42). This study also investigated the cellular-level photoprotective effects of eumelanin using Schizosaccharomyces pombe ARC039 as a model organism and its ability to enhance the Sun Protection Factor (SPF) of commercial sunscreens. The thermal and light stability and total phenolic and flavonoid contents were analyzed. Antioxidant activity was assessed using hydroxyl radicals (OH), and superoxide anions (O2.-) radical-scavenging assays. The efficacy of photoprotection was determined using various in vitro methods, yeast cell viability assays, and enhanced SPF values of commercial sunscreen products. Eumelanin NTB 42 exhibited both thermal and photostabilities. The total phenolic and flavonoid contents were reported as 88.82 ± 0.68 mg gallic acid equivalent (GAE)/g and 53.24 ± 2.66 mg quercetin equivalent (QE)/g, respectively, representing the first report on microbial eumelanin. Eumelanin NTB 42 demonstrated significant scavenging activity against OH and O2.-. It also displays notable photoprotective effects against UV-B radiation, offering broad-spectrum coverage and optimal protection against UV-A radiation. It effectively acted as a sunblock against UV-A and UV-B radiation. Furthermore, eumelanin NTB 42 enhanced S. pombe ARC039 cell viability after exposure to UV-B and UV-C for 30-90 min. It also augmented the SPF value of commercial products at a minimum concentration of 0.0025 %. These findings highlight the potential antioxidant and photoprotective properties of eumelanin NTB 42, suggesting its applicability as a raw material for sunscreen formulations in the cosmetic industry.

Polyphenol Profile and Antioxidant, Antityrosinase, and Anti-Melanogenesis Activities of Ethanol Extract of Bee Pollen

Background/Objective: Bee pollen, a rich nutritional food, was employed to develop a raw material for skin whitening. Methods: The polyphenol profile and antioxidant, antityrosinase, and anti-melanogenesis activities of the ethanol extracts of five species of bee pollens (EEBPs) were determined. Results: The results showed that there were a total of 121 phenolic compounds in these EEBPs. Each type of bee pollen had unique substances. The best anti-melanogenesis activity was observed for sunflower EEBP, about 25% at a concentration of 25 μg/mL BEEP. The anti-melanogenesis activities of EEBPs from high to low were sunflower, apricot, camellia, rapeseed, and lotus EEBPs. The anti-melanogenesis activity in B16F10 cells was positively correlated with the antityrosinase activity and total phenol content, with coefficients of 0.987 and 0.940. The Kyoto Encyclopedia of Genes and Genomes enrichment analysis results of untargeted proteomics revealed that sunflower EEBP inhibited melanogenesis in B16F10 cells by reducing the expression of the proteins MAP2K1, NFKB2, RELB, RPS6KA3, CASP3, TRAF6, MAP2K5, MAPKAPK3, STRADA, CCNA2, and FASN involved in the cAMP, MAPK, and TNF signaling pathways, even though these pathways were not significantly different from the control group. Conclusions: The sunflower EEBP has high inhibition effect on melanogenesis than other species EEBPs. The results provide a basis for the future industrial development of a raw material for skin whitening.

Melanin in the Retinal Epithelium and Magnetic Sensing: A Review of Current Studies

Coming in a variety of forms, melanin is one of the most abundant, stable, diverse, and evolutionarily ancient pigments found in living things in nature. These pigments often serve protective functions, typically well-adapted to their specific roles. One such protective function is metal chelation and cation exchange, which help regulate and buffer metal concentrations within cells. By binding to certain metals, melanin can acquire magnetic properties. Because of this, it may play a role in magnetic effects and possibly in the response of organisms to external magnetic fields and magnetic sensing. While there is melanin in plants, microbes, fungi, and invertebrates, certain types of melanin are specifically associated with the retina in vertebrates, including migrating bird and fish species. In this review, we examine studies focusing on the properties of melanin in these parts of the body and their possible association with magnetic sensing, and generally, magnetic sensing in the retina.

Integrating skin color assessments into clinical practice and research: A review of current approaches

Skin color classification can have importance in skin health, pigmentary disorders, and oncologic condition assessments. It is also critical for evaluating disease course and response to a variety of therapeutic interventions and aids in accurate classification of participants in clinical research studies. A panel of dermatologists conducted a literature review to assess the strengths and limitations of existing classification scales, as well as to compare their preferences and utilities. We identified 17 skin classification systems utilized in dermatologic settings. These systems include a range of parameters such as UV light reactivity, race, ethnicity, and degree of pigmentation. The Fitzpatrick skin type classification is most widely used and validated. However it has numerous limitations including its conflation with race, ethnicity, and skin color. There is a lack of validation data available for the remaining scales. There are significant deficiencies in current skin classification instruments. Consensus-based initiatives to drive the development of validated and reliable tools are critically needed.

Hydrolyzed cow colostrum extract (BCFM) inhibits alpha-MSH-induced melanogenesis in B16F1 cells via regulation of the MC1R-cAMP signaling pathway

Cow colostrum is the first milk produced after birth and is a rich natural source of nutrients, immunoglobulins, peptides, and growth factors. The bioconversion of milk and whey changes the immobilization and biochemical characterization. However, the cellular mechanism and the anti-melanin synthesis effects of hydrolyzed cow colostrum extract (BCFM) in alpha-MSH-induced B16F1 cells have not been examined. In this study, we investigated the anti-melanogenesis mechanism by examining the effects of BCFM in alpha-MSH-induced B16F1 cells. Cells were treated with BCFM in the presence or absence of alpha-MSH and co-cultured for 24, 48, and 72 h. The treatment of B16F1 cells with alpha-MSH resulted in the darkening of the color of the cells and induction of melanin synthesis. In addition, the expression levels of MC1R and cAMP, as well as phosphorylation levels of CREB and PKA, were increased by alpha-MSH treatment. However, concomitant treatment with BCFM resulted in a significant decrease in these factors and phosphorylated MITF. At the same time, the expressive amount of TRP-1 and tyrosinase was also decreased in B16F1 cells. These results demonstrate the potential of BCFM for the prevention of melanogenesis progression via the regulation of the MC1R-cAMP signaling pathway in alpha-MSH-induced B16F1 cells. The administration of BCFM suppressed the expression of TRP-1 and/or tyrosinase by regulating the CREB/MITF signaling pathways in the B16F1 cells. We propose that hydrolyzed cow colostrum extract (BCFM) is suitable for use as a novel active agent for skin whitening or pharmaceutical applications.

Kunzea Ericoides (Kanuka) Leaf Extracts Show Moisturisation, Antioxidant, and UV Protection Effects in HaCaT Cells and Anti-melanogenesis Effects in B16F10 Cells

Kunzea ericoides (kanuka) products are well-known for their potent medicinal values in antioxidant and anti-inflammatory applications. The present study identified various compounds, such as chlorogenic acid, gallic acid, quercetin, and (E)-ferulic acid in the kanuka leaf extract, showing its potential use in maintaining skin health. The influence of kanuka leaf extract upon epidermal cells concerning cytotoxicity and in vitro activities of moisturisation, antioxidation, UV protection, and anti-melanogenesis effects were explored in the study. Kanuka leaf extract demonstrated significant promotion in the proliferation of HaCaT and B16F10 cells. After incubation with kanuka leaf extract, the content of ROS and DPPH in HaCaT was significantly decreased; at the same time, more SOD was produced. Furthermore, hyaluronidase-1 (HYAL-1) and HYAL-4 expressions were inhibited, while the aquaporin 3 (AQP-3) content was significantly increased in HaCaT. Kanuka leaf extract also inhibited the expressions of matrix metalloproteinases-1 (MMP-1) and MMP-14 in UV-induced HaCaT cells. In the B16F10 cell line, melanin and tyrosinase production were decreased under the presence of kanuka leaf extract, and the expressions of microphthalmia-associated transcription factor (MITF), tyrosinase-related protein-1 (TYRP-1), and TYRP-2 were also inhibited. The study validated kanuka leaf extract as an effective natural product against photoaging and melanogenesis.

False Positive Rate from Prospective Studies of PET-CT in Cutaneous Malignant Melanoma: A Systematic Review and Meta-Analysis

BACKGROUND

Cutaneous malignant melanoma (CMM) is increasing in prevalence and possesses the highest mortality rate of any skin cancer. Positron Emission Tomography and Computed Tomography (PET-CT) may be utilised in either radiological staging or surveillance, primarily in stage III-IV disease. False positive (FP) results lead to patient distress, increased costs, and unnecessary follow-up. The FP rate in CMM literature varies widely, altering calculations of positive predictive value and has not undergone pooled meta-analytic.

MATERIALS AND METHODS

A systematic review and meta-analysis of FP results in prospective studies of PET-CT in CMM was performed in accordance with PRISMA guidelines.

RESULTS

The systematic review produced 14 trials for inclusion. Patient-based reporting had the lowest pooled proportion of FP results with 5.8 % (95 % CI = 3.3 % to 8.8 %), lesion-based was highest with 9.1 % (95 % CI = 3.4 % to 17.2 %) and combined was 6.1 % (95 % CI = 4.3 % to 8.1 %). Bias was low to unclear other than for FP reporting. Heterogeneity (I2) was variable across all analyses. FP findings were mainly lymphatic, dermatological, respiratory, or skeletal. Diagnostic information was not provided.

CONCLUSIONS

This study was the first attempt to quantify the pooled proportion of FP results from PET-CT in CMM. A small number of studies (n = 14) were available due to the predominance of retrospective methodology. Due to inconsistent reporting the true proportion of FP results is unclear. Systemic distribution was expected but limited diagnostic information was provided. Repeat meta-analysis using retrospective work should be performed. Future work should be prospective with clearly documented FP proportion, distribution, diagnosis, and follow-up.

Vaginal Mucosal Melanoma Cell Activation in Response to Photon or Carbon Ion Irradiation

Purpose

Primary gynecological melanomas are uncommon with lower survival rates compared to cutaneous melanomas. Although melanocytes have been identified in a variety of mucosal membranes, little is known about their interactions or roles inside the mucosa layer. Melanin is a common pigment in nature and is endowed with several peculiar chemical, paramagnetic, and semiconductive characteristics. One of its latest explored functions is its interaction with ionizing radiation as a protective mechanism as well as its implication in the metastatic cascade of tumor cells.

Materials and Methods

In this work, we analyzed in vitro the effects of different doses of photon and carbon ion irradiation on dendrite formation, pigmentation, migration, and invasion abilities of human mucosal melanoma cells of the vagina. We evaluated the morphology and melanin production of HMV-II cells exposed to photon and carbon ion beams with single doses between 0.5 and 10 Gy.

Results

Our results showed that irradiation induces dendrite formation or elongation and pigmentation in HMV-II cells in a dose-type-dependent and radiation-type-dependent way but also a decrease in cell motility.

Conclusion

The present study describes for the first time an induction of dendritic formation, melanin production, and alterations in migration and invasion abilities by low-linear energy transfer and high-linear energy transfer radiation in human mucosal melanoma cells, suggesting a radioprotective response to further possible exposures increasing the radioresistance of these cells.

An overlooked risk for skin health: Less availability and higher cost of sunscreen for people with melanated skin

Background

Sunscreen with a skin protection factor (SPF) of 30 or greater is recommended to reduce the risk of skin cancer and improve skin health for all people regardless of skin tone. Traditional sunscreen that creates a white cast on the skin is incompatible with melanated skin.

Methods

The number of products on the shelf, SPF level, application, coloration, and cost were recorded at three beauty supply chain stores and three pharmacy, health, and wellness stores in or near Harlem in New York City in the Spring of 2023. The number of skin tones for tinted sunscreen was visually matched to the Fitzpatrick Skin Phototypes scale.

Results

A total of 385 sunscreen products were identified; 78.7 % were traditional white sunscreen, followed by sheer (15.3 %) and tinted (6.0 %) products. Beauty supply stores offered more tinted sunscreen options than did pharmacy, health, and wellness stores (n = 17,15.3 % vs. n = 6, 2.2 %, p < 0.001). Of the tinted sunscreen products, 19 brands offered only a single tone. Tinted sunscreen was significantly more expensive with an average cost of $24.59 [SD $14.71] per ounce vs. $6.85 [SD 8.66] for traditional, and $9.38 [SD 8.92] for sheer suncreen.

Conclusions

Sunscreen that is tinted or sheer and compatible with melanated skin is less available and more costly than traditional white sunscreen in beauty and pharmacy chain stores in NYC. Availability and affordability of sunscreen matching the spectrum of skin tones are essential for optimal sun protection and skin health.

Stem cell factor-mediated upregulation of SIRT1 protects melanin-deprived keratinocytes against UV-induced DNA damage in individuals with vitiligo

Despite the loss of melanocytes, individuals with vitiligo have a significantly lower risk of developing skin malignancies compared to ethnicity-matched controls. The study investigated the molecular mechanisms that protect skin cells (keratinocytes) from UV-B-induced DNA damage in individuals with vitiligo. The study found that upregulation of stem cell factor (SCF) signaling significantly reduced γ-H2AX positivity and cyclobutane pyrimidine dimer formation and improved mitochondrial health (elongated mitochondria, reduced reactive oxygen species [ROS] and lipid peroxidation) in keratinocytes upon UV-B exposure. Interestingly, SCF treatment also reduced lipid droplet accumulation and triacylglyceride levels by upregulating lipoprotein lipase (LPL). Further, siLPL increased DNA damage and lipid droplet (LD) accumulation, while NO-1886, an LPL agonist, reversed both, suggesting a direct link between lipid metabolism and DNA damage. Downregulation of NAD-dependent deacetylase sirtuin1 (SIRT1) with siRNA or with Ex-527, a pharmacological inhibitor of SIRT1, diminished the protective effects mediated by SCF and NO-1886, suggesting SIRT1 to be the final effector protein in the SCF-LPL-SIRT1 signaling axis. Analysis of clinical samples of vitiligo corroborated the upregulation of SCF and LPL in lesional epidermis. In conclusion, our study demonstrates a novel SCF-LPL-SIRT1 signaling axis that confers protection to vitiligo keratinocytes from the harmful effects of UV-B radiation.

Skin Phototype Classification with Machine Learning Based on Broadband Optical Measurements

The Fitzpatrick Skin Phototype Classification (FSPC) scale is widely used to categorize skin types but has limitations such as the underrepresentation of darker skin phototypes, low classification resolution, and subjectivity. These limitations may contribute to dermatological care disparities in patients with darker skin phototypes, including the misdiagnosis of wound healing progression and escalated dermatological disease severity. This study introduces (1) an optical sensor measuring reflected light across 410-940 nm, (2) an unsupervised K-means algorithm for skin phototype classification using broadband optical data, and (3) methods to optimize classification across the Near-ultraviolet-A, Visible, and Near-infrared spectra. The differentiation capability of the algorithm was compared to human assessment based on FSPC in a diverse participant population (n = 30) spanning an even distribution of the full FSPC scale. The FSPC assessment distinguished between light and dark skin phototypes (e.g., FSPC I vs. VI) at 560, 585, and 645 nm but struggled with more similar phototypes (e.g., I vs. II). The K-means algorithm demonstrated stronger differentiation across a broader range of wavelengths, resulting in better classification resolution and supporting its use as a quantifiable and reproducible method for skin type classification. We also demonstrate the optimization of this method for specific bandwidths of interest and their associated clinical implications.

MLPH is a novel adipogenic factor controlling redox homeostasis to inhibit lipid peroxidation in adipocytes

Abnormal adipose tissue formation is associated with metabolic disorders such as obesity, diabetes, and liver and cardiovascular diseases. Thus, identifying the novel factors that control adipogenesis is crucial for understanding these conditions and developing targeted treatments. In this study, we identified the melanosome-related factor MLPH as a novel adipogenic factor. MLPH was induced during the adipogenesis of 3T3-L1 cells and human mesenchymal stem cells. Although MLPH did not affect lipid metabolism, such as lipogenesis or lipolysis, adipogenesis was severely impaired by MLPH depletion. We observed that MLPH prevented excess reactive oxygen species (ROS) accumulation and lipid peroxidation during adipogenesis and in mature adipocytes. In addition, increased MLPH expression was observed under cirrhotic conditions in liver cancer cells and its overexpression also reduced ROS and lipid peroxidation. Our findings demonstrate that MLPH is a novel adipogenic factor that maintains redox homeostasis by preventing lipid peroxidation and ROS accumulation, which could lead to metabolic diseases.

Design, CTAB-catalyzed ultrasound-assisted synthesis and tyrosinase inhibition potential of naphthofuran-triazole conjugates

The development of novel and efficient tyrosinase inhibitors is a critical necessity of agricultural, cosmetic and medicinal chemistry. Bearing in mind the therapeutical potential of naphthofuran-containing organic compounds, we carried out the CTAB-catalyzed ultrasound-assisted synthesis of a library of novel naphthofuran-triazole joined N-aryl/alkyl acetamides 20(a-j) in 74-92% yield, which were further assessed for their tyrosinase inhibitory potential by taking kojic acid and ascorbic acid as standard inhibitors. The tyrosinase inhibitory assay demonstrated the promising tyrosinase inhibiting tendency of all prepared derivatives 20(a-h) as they all were found to be more efficient in comparison to the standard kojic acid. Similarly, most of the derivatives also exhibited tyrosinase inhibition potency in juxtaposition to ascorbic acid. More specifically, among the catalog of compounds, 20f and 20i exhibited potent inhibition results with IC50 = 0.51 ± 0.12 and 1.99 ± 0.07, respectively. Overall, 20f was shown to be the most efficacious tyrosinase inhibitor, owing to the presence of an electronegative group, i.e., 2-chloro substitution on the phenyl ring. The tyrosinase inhibition activity results of 20f and 20i were further supplemented with molecular docking analysis to validate experimental studies. In silico modelling findings revealed their significant interactions with the tyrosinase protein (PDB ID: 5OAE), thereby illustrating the efficient docking score of -7.10 kcal mol-1 and -6.95 kcal mol-1 in comparison to kojic acid (-5.03 kcal mol-1).

Deciphering melanophagy: role of the PTK2-ITCH-MLANA-OPTN cascade on melanophagy in melanocytes

Melanosomes play a pivotal role in skin color and photoprotection. In contrast to the well-elucidated pathway of melanosome biogenesis, the process of melanosome degradation, referred to as melanophagy, is largely unexplored. Previously, we discovered that 3,4,5-trimethoxycinnamate thymol ester (TCTE) effectively inhibits skin pigmentation by activating melanophagy. In this study, we discovered a new regulatory signaling cascade that controls melanophagy in TCTE-treated melanocytes. ITCH (itchy E3 ubiquitin protein ligase) facilitates ubiquitination of the melanosome membrane protein MLANA (melan-A) during TCTE-induced melanophagy. This ubiquitinated MLANA is then recognized by an autophagy receptor protein, OPTN (optineurin). Additionally, a phospho-kinase antibody array revealed that TCTE activates PTK2 (protein tyrosine kinase 2), which phosphorylates ITCH, enhancing the ubiquitination of MLANA. Furthermore, inhibition of either PTK2 or ITCH disrupts the ubiquitination of MLANA and the MLANA-OPTN interaction in TCTE-treated cells. Taken together, our findings highlight the critical role of the PTK2-ITCH-MLANA-OPTN cascade in orchestrating melanophagy progression.Abbreviations: α-MSH: alpha-melanocyte-stimulating hormone; dichlone: 2,3-dichloro-1,4-naphthoquinone; ITCH: itchy E3 ubiquitin protein ligase; MITF: melanocyte inducing transcription factor; MLANA: melan-A; NBR1: NBR1 autophagy cargo receptor; OPTN: optineurin; PINK1: PTEN induced kinase 1; PTK2: protein tyrosine kinase 2; SQSTM1/p62: sequestosome 1; TCTE: 3,4,5-trimethoxycinnamate thymol ester; TPC2: two pore segment channel 2; VDAC1: voltage dependent anion channel 1.

Anti-Melanogenic Activities of Sargassum fusiforme Polyphenol-Rich Extract on α-MSH-Stimulated B16F10 Cells via PI3K/Akt and MAPK/ERK Pathways

BACKGROUND

Melanin overproduction leads to pigmented skin diseases. Brown algae polyphenols, non-toxic secondary metabolites, exhibit potential bioactivities. Sargassum fusiforme, an edible seaweed, has been underexplored in the field of beauty despite its polyphenol richness.

METHODS

Polyphenols from S. fusiforme were extracted using macroporous resin (SFRP) and ethyl acetate (SFEP). Their antioxidant and anti-aging properties, tyrosinase inhibitory activities, and mechanisms were assessed. The melanogenesis inhibition effect and mechanism by SFRP was examined in B16F10 melanoma cells.

RESULTS

Both SFRP and SFEP demonstrated scavenging activities against DPPH, superoxide anion, and hydroxyl radicals. SFRP showed stronger anti-collagenase and anti-elastase effects. They dose-dependently inhibited mushroom tyrosinase, with IC50 values of 9.89 μg/mL for SFRP and 0.99 μg/mL for SFEP. SFRP reversibly inhibited tyrosinase, while SFEP showed irreversible inhibition. SFRP also suppressed melanin content and intracellular tyrosinase activity in B16F10 cells, downregulating the expression of microphthalmia-associated transcription factor, tyrosinase, and tyrosinase-related protein 1 and 2 expression through the PI3K/Akt and MAPK/ERK signal pathways.

CONCLUSIONS

S. fusiforme polyphenols, especially SFRP, exhibit promising antioxidant, anti-aging, and melanogenesis inhibitory properties, highlighting their potential application as novel anti-melanogenic agents in cosmetics and the food industry.

A Spectrophotometric Method to Determine Minimal Erythema Dose for Ultraviolet Radiation in Human Skin

Background/Objectives: Ultraviolet radiation (UVR) induces oxidative stress in the skin by generating reactive oxygen species (ROS), which can lead to inflammatory conditions including erythema (a sign of sunburn). This clinical study aims to develop an instrumental evaluation method to determine the minimal erythema dose (MED) for UVR. Methods: Fourteen human subjects aged 27 to 57 years (48.93 ± 8.54) participated in this study. Six subsites were designated on the test skin site of each subject and irradiated with UVR at different doses. The examiner visually assessed erythema, determining the 'visual MED'. Additionally, the a* value (a chrominance parameter presenting greenness to redness) was measured using a spectrophotometer as an indicator of erythema. The a* values of the UVR-irradiated subsites were compared to the non-irradiated control value, and the differences were referred to as Δa*. The Δa* value of the subsites irradiated with UVR at the 'visual MED' was referred to as the Δa*VMED for each subject. The mean of the Δa*VMED values of all subjects was chosen as a criterion value for the 'instrumental MED'. The 'instrumental MED' was defined as the lowest dose of UVR that causes an Δa* value equivalent to the criterion value. The 'visual MED' and 'instrumental MED' values of all subjects were subjected to correlation analysis. Results: The mean of the Δa*VMED values of all subjects was 1.88 ± 0.8. The means of the 'visual MED' and 'instrumental MED' values (in J m-2 unit) of all subjects were 300.14 ± 84.16 and 303.29 ± 77.99, respectively. In Pearson correlation analysis, the 'instrumental MED' and 'visual MED' values had a very strong positive correlation with each other (r = 0.864, p = 0.000). Conclusions: This study suggests that the instrumental evaluation method of MED based on the spectrophotometric measurement of the a* values can complement or replace the visual evaluation method and that this method will be useful in monitoring skin tolerance to oxidative stress affected by prooxidant factors and defensive factors.

Age-related variations in stratum corneum hydration in the foot

OBJECTIVE

The aims of the study are to identify which region of the foot has lower hydration according to age, measure the variation in the level of stratum corneum hydration of the foot across the a wide age range, and examine hydration differences of the foot according to gender.

STUDY DESIGN

A descriptive observational study was conducted to assess stratum corneum hydration of the foot among 504 participants recruited between November 2023 and March 2024.

MAIN OUTCOMES MEASURES

Stratum corneum hydration assessment was conducted using a Corneometer 825® probe at 10 specific points on the foot. Data on sociodemographic variables, medical history, foot care habits, and hydration-related factors were collected. Statistical analyses were performed using SPSS v. 24.0.

RESULTS

Stratum corneum hydration of the foot varied significantly across regions, with higher hydration in the digital zone and lower hydration in the heel. An inverse correlation was found between age and hydration, with younger participants exhibiting higher hydration levels. Women showed higher hydration than men. Differences in hydration were observed between the right and left feet.

CONCLUSION

This study highlights the importance of localized assessment of foot skin dehydration. Aging significantly affects stratum corneum hydration of the foot. Gender differences in hydration suggest the importance of personalized approaches to skin care. Differential hydration between feet underscores the influence of mechanical load.

Irritant Contact Dermatitis Due to Fecal, Urinary, or Dual Incontinence: It Is Time to Focus on Darkly Pigmented Skin

GENERAL PURPOSE

To review best practices related to the assessment of irritant contact dermatitis due to fecal, urinary, or dual incontinence (ICD-FIUIDI) among patients with darkly pigmented skin.

TARGET AUDIENCE

This continuing education activity is intended for physicians, physician assistants, nurse practitioners, and registered nurses with an interest in skin and wound care.

LEARNING OBJECTIVES/OUTCOMES

After participating in this educational activity, the participant will:1. Identify risk factors for the development of ICD-FIUIDI.2. Describe clinical features and manifestations of ICD-FIUIDI.3. Propose recommendations to improve care related to ICD-FIUIDI.

Kinetic studies, molecular docking, and antioxidant activity of novel 1,3-diphenyl pyrazole-thiosemicarbazone with anti-tyrosinase and anti-melanogenesis properties

This study reports the Design Hypothesis of a novel series of 1,3-diphenyl pyrazole-thiosemicarbazone as novel tyrosinase inhibitors (TYRI). The designed compounds were prepared and their TYRI activity and mechanisms were studied. The results showed that the selected compounds exhibited potent tyrosinase inhibitory activities greater than that of kojic acid (KA). Lead candidates, denoted as 6g and 6n, with a para-hydroxyphenyl group attached to the 3-position of the pyrazole ring demonstrated IC50 values of 2.09 and 3.18 µM, respectively. The potency of these compounds was approximately 5-8 times higher than that of KA. The in vitro melanin content of 6g or 6n-treated melanoma cells resulted in significant efficacy in melanin reduction. The DPPH assay result revealed that the tyrosinase inhibition mechanism for these derivatives was independent of a redox effect and corresponded to the interaction with tyrosinase. According to the Lineweaver-Burk plot, the most potent compounds, 6g and 6n, exhibit a mixed type of inhibition, primarily noncompetitive inhibition. In silico molecular docking studies were employed to determine the binding mode and explore the Design Hypothesis in detail. The results suggested that these compounds could be considered promising leads for the further development of novel inhibitors to treat disorders related to tyrosinase.

Ethanolic Extract of Bergenia purpurascens Exhibits Antimelanogenic Effects in B16F10 Cells through Multiple Mechanisms That Suppress Tyrosinase

Bergenia purpurascens, renowned for its antibacterial and antioxidant properties, remains relatively unexplored in its impact on melanogenesis. This study delves into the antimelanogenic potential of the ethanol extract derived from B. purpurascens (BPE). Our investigations reveal the robust antioxidant capabilities of the BPE, along with its effective inhibition of mushroom tyrosinase activity. Remarkably, these effects were significantly stronger than those observed with arbutin, the positive control. In vitro assays demonstrate the BPE's efficacy in reducing the melanin content and tyrosinase activity in α-MSH-stimulated B16F10 cells. Immunofluorescence and qPCR analyses further reveal the BPE's ability to inhibit MITF-mediated gene expression levels associated with melanogenesis, including Trp-1, Trp-2, and tyrosinase. These findings suggest that the extract operates through dual mechanisms, suppressing both tyrosinase activity and key transcription factor-mediated downstream signaling. Utilizing UPLC-MS/MS analysis, we identified six key compounds implicated in tyrosinase activity inhibition and melanogenesis suppression. Docking simulations confirm moderate binding affinities between these compounds and tyrosinase. This study highlights the potential of B. purpurascens as a novel natural agent for depigmentation in medicinal and cosmetic applications, elucidating its dual mechanism of action in melanogenesis inhibition.

Geographical Differences in Hydrochlorothiazide Associated Risk of Skin Cancer Balanced Against Disability Related to Hypertensive Heart Disease

BACKGROUND

Hypertension affects 25%-30% of the world population. Hydrochlorothiazide (HCTZ) is among the most used and cheapest medications but was in 2018 labeled with a warning stating the increased risk of nonmelanoma skin cancer (NMSC). This study describes geographical differences in the association between HCTZ and NMSC from the perspective of hypertensive heart disease (HHD).

METHODS

We conducted a systematic literature search (PubMed, Embase, Clinicaltrial.gov, and Clinicaltrial.eu) using PICO/PECO acronyms, including case-control, cohort, and randomized controlled trials. We constructed a rate ratio of disability-adjusted life years (DALY) for HHD/NMSC in the global burden of disease (GBD) regions.

RESULTS

No increased risk of NMSC with the use of HCTZ was found in Taiwan, India, and Brazil. A small (hazard ratio (HR)/odds ratio (OR) ≤1.5) but significantly increased risk was seen in Canada, the United States, and Korea. An increased risk (1.5< HR/OR ≤2.5) in Iceland, Spain, and Japan and a highly increased risk (HR/OR >2.5) in the United Kingdom, Denmark, the Netherlands, and Australia. HHD is associated with a more than tenfold DALY rate compared with NMSC in 13 of 21 GBD regions, corresponding to 77.2% of the global population. In none of these 13 regions was there an increased risk of HCTZ-associated NMSC.

CONCLUSIONS

Despite limited information from many countries, our data point to large geographical differences in the association between HCTZ and NMSC. In all GBD regions, except Australasia, HHD constitutes a more than fivefold DALY rate compared to NMSC. This disproportionate risk should be considered before avoiding HCTZ from the antihypertensive treatment.

The Contribution of the Skin Microbiome to Psoriasis Pathogenesis and Its Implications for Therapeutic Strategies

Psoriasis is a common chronic inflammatory skin disease, associated with significant morbidity and a considerable negative impact on the patients' quality of life. The complex pathogenesis of psoriasis is still incompletely understood. Genetic predisposition, environmental factors like smoking, alcohol consumption, psychological stress, consumption of certain drugs, and mechanical trauma, as well as specific immune dysfunctions, contribute to the onset of the disease. Mounting evidence indicate that skin dysbiosis plays a significant role in the development and exacerbation of psoriasis through loss of immune tolerance to commensal skin flora, an altered balance between Tregs and effector cells, and an excessive Th1 and Th17 polarization. While the implications of skin dysbiosis in psoriasis pathogenesis are only starting to be revealed, the progress in the characterization of the skin microbiome changes in psoriasis patients has opened a whole new avenue of research focusing on the modulation of the skin microbiome as an adjuvant treatment for psoriasis and as part of a long-term plan to prevent disease flares. The skin microbiome may also represent a valuable predictive marker of treatment response and may aid in the selection of the optimal personalized treatment. We present the current knowledge on the skin microbiome changes in psoriasis and the results of the studies that investigated the efficacy of the different skin microbiome modulation strategies in the management of psoriasis, and discuss the complex interaction between the host and skin commensal flora.

Uncovering key mechanisms and intervention therapies in aging skin

Advancements in understanding skin aging mechanisms, which encompass both external and internal aging processes, have spurred the development of innovative treatments primarily aimed at improving cosmetic appearance. These findings offer the potential for the development of novel therapeutic strategies aimed at achieving long-term, non-therapy-dependent clinical benefits, including the reversal of aging and the mitigation of associated health conditions. Realizing this goal requires further research to establish the safety and efficacy of targeting aging-related skin changes, such as pigmentation, wrinkling, and collagen loss. Systematic investigation is needed to identify the most effective interventions and determine optimal anti-aging treatment strategies. These reviews highlight the features and possible mechanisms of skin aging, as well as the latest progress and future direction of skin aging research, to provide a theoretical basis for new practical anti-skin aging strategies.

Plastic use as nesting material can alter incubation temperature and behaviour but does not affect yellow-legged gull chicks

Optimal incubation temperature is crucial for embryos' development and survival. With the increasing use of plastics in gulls' nests, it is essential to understand how their incorporation affects incubation temperature, parental behaviour, and hatching success. Considering this, we conducted an experiment where plastic was introduced into yellow-legged gulls (Larus michahellis) nests. The experiment comprised three groups: a control group, a group with low amount of plastic, and a third with a high amount of plastic. This design allowed us to investigate the effects of plastic on 1) the heart rate of incubating adults, 2) the number and duration of adults' absences from their nest, 3) how the presence or absence of the adult influenced egg temperature, and 4) chick hatching success, physiological parameters, and bill colour phenotype. We observed that incubation temperature was consistently higher in nests with plastic. The number of absences was higher in the low plastic group at increased temperatures, though the duration was significantly lower in both plastic groups than in the control, possibly to mitigate the effects of heat stress. During higher environmental temperatures, heart rate was higher for the high plastic group. The increase in heart rate in the low plastic group was less pronounced with increasing environmental temperatures. No significant effects were observed on hatching success or in the health condition of young chicks, except for high values of haemoglobin in both plastic groups, which might indicate dehydration.

Changes in human skin composition due to intrinsic aging: a histologic and morphometric study

Skin represents the main barrier against the external environment, but also plays a role in human relations, as one of the prime determinants of beauty, resulting in a high consumer demand for skincare-related pharmaceutical products. Given the importance of skin aging in both medical and social spheres, the present research aims to characterize microscopic changes in human skin composition due to intrinsic aging (as opposed to aging influenced by external factors) via histological analysis of a photoprotected body region. Samples from 25 autopsies were taken from the periumbilical area and classified into four age groups: group 1 (0-12 years), group 2 (13-25 years), group 3 (26-54 years), and group 4 (≥ 55 years). Different traditional histological (hematoxylin-eosin, Masson's trichrome, orcein, toluidine, Alcian blue, and Feulgen reaction) and immunohistochemical (CK20, CD1a, Ki67, and CD31) stains were performed. A total of 1879 images photographed with a Leica DM3000 optical microscope were morphometrically analyzed using Image ProPlus 7.0 for further statistical analysis with GraphPad 9.0. Our results showed a reduction in epidermis thickness, interdigitation and mitotic indexes, while melanocyte count was raised. Papillary but not reticular dermis showed increased thickness with aging. Specifically, in the papillary layer mast cells and glycosaminoglycans were expanded, whereas the reticular dermis displayed a diminution in glycosaminoglycans and elastic fibers. Moreover, total cellularity and vascularization of both dermises were diminished with aging. This morphometric analysis of photoprotected areas reveals that intrinsic aging significantly influences human skin composition. This study paves the way for further research into the molecular basis underpinning these alterations, and into potential antiaging strategies.

Advanced nanomedicines for the treatment of age-related macular degeneration

The critical and unmet medical need for novel therapeutic advancements in the treatment of age-related macular degeneration (AMD) cannot be overstated, particularly given the aging global population and the increasing prevalence of this condition. Current AMD therapy involves intravitreal treatments that require monthly or bimonthly injections to maintain optimal efficacy. This underscores the necessity for improved approaches, prompting recent research into developing advanced drug delivery systems to prolong the intervals between treatments. Nanoparticle-based therapeutic approaches have enabled the controlled release of drugs, targeted delivery of therapeutic materials, and development of smart solutions for the harsh microenvironment of diseased tissues, offering a new perspective on ocular disease treatment. This review emphasizes the latest pre-clinical treatment options in ocular drug delivery to the retina and explores the advantages of nanoparticle-based therapeutic approaches, with a focus on AMD, the leading cause of irreversible blindness in the elderly.

MITF regulates IDH1, NNT, and a transcriptional program protecting melanoma from reactive oxygen species

Microphthalmia-associated transcription factor (MITF) is a master regulator of melanocyte function, development and plays a significant role in melanoma pathogenesis. MITF genomic amplification promotes melanoma development, and it can facilitate resistance to multiple therapies. Here, we show that MITF regulates a global antioxidant program that increases survival of melanoma cell lines by protecting the cells from reactive oxygen species (ROS)-induced damage. In addition, this redox program is correlated with MITF expression in human melanoma cell lines and patient-derived melanoma samples. Using a zebrafish melanoma model, we show that MITF decreases ROS-mediated DNA damage in vivo. Some of the MITF target genes involved, such as IDH1 and NNT, are regulated through direct MITF binding to canonical enhancer box (E-BOX) sequences proximal to their promoters. Utilizing functional experiments, we demonstrate the role of MITF and its target genes in reducing cytosolic and mitochondrial ROS. Collectively, our data identify MITF as a significant driver of the cellular antioxidant state.

Overview on tyrosinases: Genetics, molecular biology, phylogenetic relationship

Tyrosinases (TYRs) are enzymes found in various organisms that are crucial for melanin biosynthesis, coloration, and UV protection. They play vital roles in insect cuticle sclerotization, mollusk shell formation, fungal and bacterial pigmentation, biofilm formation, and virulence. Structurally, TYRs feature copper-binding sites that are essential for catalytic activity, facilitating substrate oxidation via interactions with conserved histidine residues. TYRs exhibit diversity across animals, plants, fungi, mollusks, and bacteria, reflecting their roles and function. Eukaryotic TYRs undergo post-translational modifications, such as glycosylation, which affect protein folding and activity. Bacterial TYRs are categorized into five types based on their structural variation, domain organization and enzymatic properties, showing versatility across bacterial species. Moreover, bacterial TYRs, akin to fungal TYRs, have been implicated in the synthesis of secondary metabolites with antimicrobial properties. TYRs share significant sequence homology with hemocyanins, oxygen-carrier proteins in mollusks and arthropods, highlighting their evolutionary relationships. The evolution of TYRs underscores the dynamic nature of these enzymes and reflects adaptive strategies across diverse taxa.

Variation in ultraviolet-B (UV-B)-induced DNA damage repair mechanisms in plants and humans: an avenue for developing protection against skin photoaging

PURPOSE

The increasing amounts of ultraviolet-B (UV-B) light in our surroundings have sparked worries about the possible effects on humans and plants. The detrimental effects of heightened UV-B exposure on these two vital elements of terrestrial life are different due to their unique and concurrent nature. Understanding common vulnerabilities and distinctive adaptations of UV-B radiation by exploring the physiological and biochemical responses of plants and the effects on human health is of huge importance. The comparative effects of UV-B radiation on plants and animals, however, are poorly studied. This review sheds light on the sophisticated web of UV-B radiation effects by navigating the complex interaction between botanical and medical perspectives, drawing upon current findings.

CONCLUSION

By providing a comprehensive understanding of the complex effects of heightened UV-B radiation on plants and humans, this study summarizes relevant adaptation strategies to the heightened UV-B radiation stress, which offer new approaches for improving human cellular resilience to environmental stressors.

Rice (Oryza sativa) Stem Cells as a Novel Promising Active Ingredient with Anti-Proliferative Effects for Potential Skin Cancer Prevention and Skin Whitening Activity

Rice is one of the plants proven to possess antioxidant, anti-inflammatory, anti-proliferative, and whitening properties, making it one of the most beneficial plants in this regard. This study aimed to introduce a novel natural cosmetic and pharmaceutical product based on rice callus as a source of active ingredients that can inhibit skin melanoma cell (B16F10) proliferation and brighten the skin. The 2,4-D hormone at concentrations of 1 µg/mL and 1.5 µg/mL was used to induce rice callus formation. Rice callus extracts were then prepared using aqueous and ethanolic solvents, with a concentration of 1 mg/mL used for characterization tests. To determine the optimal hormone concentration, the phenols/flavonoids, antioxidant activity, proteins, and carbohydrates in the extracts were measured. The optimal concentration of the hormone was found to be 1 µg/mL. Finally, the anti-melanocyte and skin-whitening activity of the extracts was assessed through measurements of their cytotoxicity and inhibition of melanin synthesis-related enzymes. Cellular cytotoxicity measurements revealed that the ethanolic extract induced more cytotoxicity than the aqueous extract, with IC50 values of 566.3 µg/mL for the ethanolic extract and 1327 µg/mL for the aqueous extract. Skin-whitening-related tests demonstrated that the extracts were 1.7 times more effective than arbutin in inhibiting factors that cause hyperpigmentation. The aqueous extract achieved 85% inhibition of melanin biosynthesis at a concentration of 3200 µg/mL, compared to 68% for the ethanolic extract and 50% for arbutin. Based on these findings, rice callus extract can be introduced as a new, effective substance for skin-lightening and anti-melanocyte products in cosmeceutical and pharmaceutical formulations.

Characteristics of Malassezia furfur at various pH and effects of Malassezia lipids on skin cells

Malassezia species are commensal and opportunistic fungi found in human skin. All Malassezia species lack fatty acid synthesis genes and survive by utilizing several lipases to degrade and absorb fatty acids from external lipid sources, but little research has been done on their optimal active pH and temperature. Our skin protects itself from external stimuli and maintains homeostasis, involving bacteria and fungi such as Malassezia species that inhabit our skin. Hence, dysbiosis in the skin microbiome can lead to various skin diseases. The skin's pH is slightly acidic compared to neutral, and changes in pH can affect the metabolism of Malassezia species. We used keratinocyte cell lines to determine the effect of lipids bio-converted by Malassezia furfur, Malassezia japonica, and Malassezia yamatoensis under pH conditions similar to those of healthy skin. Lipids bio-converted from Malassezia species were associated with the regulation of transcripts related to inflammation, moisturizing, and promoting elasticity. Therefore, to determine the effect of pH on lipid metabolism in M. furfur, which is associated with seborrheic dermatitis, changes in biomass, lipid content, and fatty acid composition were determined. The results showed that pH 7 resulted in low growth and reduced lipid content, which had a negative impact on skin health. Given that bio-converted Malassezia-derived lipids show positive effects at the slightly acidic pH typical of healthy skin, it is important to study their effects on skin cells under various pH conditions. KEY POINTS: • pH 6, Malassezia spp. bio-converted lipid have a positive effect on skin cells • Malassezia spp. have different lipid, fatty acid, and growth depending on pH • Malassezia spp. can play a beneficial role by secreting lipids to the outside.

Synthesis and evaluation of 3-hydroxyquinolin-2(1H)-one derivatives as inhibitors of tyrosinase

The tyrosinase (TYR) enzyme catalyses sequential reactions in the melanogenesis pathway: l-tyrosine is oxidised to yield L-3,4-dihydroxyphenylalanine (l-dopa), which in turn is converted to dopaquinone. These two reactions are the first two steps of melanin biosynthesis and are rate limiting. The accumulation or overproduction of melanin may cause skin hyperpigmentation and inhibitors of TYR are thus of interest to the cosmeceutical industry. Several TYR inhibitors are used to treat skin hyperpigmentation, however, some are ineffective and possess questionable safety profiles. This emphasises the need to develop novel TYR inhibitors with better safety and efficacy profiles. The small molecule, 3-hydroxycoumarin, has been reported to be a good potency TYR inhibitor (IC50 = 2.49 µM), and based on this, a series of eight structurally related 3-hydroxyquinolin-2(1H)-one derivatives were synthesised with the aim to discover novel TYR inhibitors. The results showed that four of the derivatives inhibited TYR from the champignon mushroom Agaricus bisporus (abTYR) with IC50 < 6.11 µM. The most potent inhibitor displayed an IC50 value of 2.52 μM. Under the same conditions, the reference inhibitors, thiamidol and kojic acid, inhibited abTYR with IC50 values of 0.130 and 26.4 μM, respectively. Based on the small molecular structures of the active 3-hydroxyquinolin-2(1H)-one inhibitors which are amenable to structure optimisation, it may be concluded that this class of compounds are good leads for the design of TYR inhibitors for cosmeceutical applications.

Virtual screening of natural products to enhance melanogenosis

Natural products have long been an important source of inspiration for medicinal chemistry and drug discovery. In the cosmetic field, they remain the major elements of the composition and serve as marketing asset. Recent research showed the implication of salt-inducible kinases on the melanin production in skin via MITF regulation. Finding new potent modulators on such target could open the way to several cosmetic applications to attenuate visible signs of photoaging and improve the tan without sun. Since virtual screening can be a powerful tool for detecting hit compounds in the early stages of a drug discovery process, we applied this method on salt-inducible kinase 2 to discover potential interesting compounds. Here, we present the different steps from the construction of a database of natural products, to the validation of a docking protocol and the results of the virtual screening. Hits from the screening were tested in vitro to confirm their efficiency and results are discussed.

Higher ultraviolet light exposure is associated with lower mortality: An analysis of data from the UK biobank cohort study

We aimed to examine associations between ultraviolet (UV) exposure and mortality among older adults in the United Kingdom (UK). We used data from UK Biobank participants with two UV exposures, validated with measured vitamin D levels: solarium use and annual average residential shortwave radiation. Associations between the UV exposures, all-cause and cause-specific mortality were examined as adjusted hazard ratios. The UV exposures were inversely associated with all-cause, cardiovascular disease (CVD) and cancer mortality. Solarium users were also at a lower risk of non-CVD/non-cancer mortality. The benefits of UV exposure may outweigh the risks in low-sunlight countries.

Oxidative State in Cutaneous Melanoma Progression: A Question of Balance

Reactive oxygen species (ROS) are highly bioactive molecules involved not only in tissue physiology but also in the development of different human conditions, including premature aging, cardiovascular pathologies, neurological and neurodegenerative disorders, inflammatory diseases, and cancer. Among the different human tumors, cutaneous melanoma, the most aggressive and lethal form of skin cancer, is undoubtedly one of the most well-known "ROS-driven tumor", of which one of the main causes is represented by ultraviolet (UV) rays' exposure. Although the role of excessive ROS production in melanoma development in pro-tumorigenic cell fate is now well established, little is known about its contribution to the progression of the melanoma metastatic process. Increasing evidence suggests a dual role of ROS in melanoma progression: excessive ROS production may enhance cellular growth and promote therapeutic resistance, but at the same time, it can also have cytotoxic effects on cancer cells, inducing their apoptosis. In this context, the aim of the present work was to focus on the relationship between cell redox state and the signaling pathways directly involved in the metastatic processes. In addition, oxidative or antioxidant therapeutic strategies for metastatic melanoma were also reviewed and discussed.

The possible and intriguing relationship between bullous pemphigoid and melanoma: speculations on significance and clinical relevance

Bullous pemphigoid (BP) is the most common autoimmune bullous disease: it most commonly affects individuals over 70 years old and impacts severely on their quality of life. BP represents a paradigm for an organ-specific autoimmune disease and is characterized by circulating IgG autoantibodies to hemidesmosomal components: BP180 and BP230. While the crucial role of these autoantibodies in triggering BP inflammatory cascade is fully acknowledged, many ancillary etiological mechanisms need to be elucidated yet. Cutaneous melanoma is due to a malignant transformation of skin melanocytes, that produce and distribute pigments to surrounding keratinocytes. Melanoma is the most fatal skin cancer because of its increasing incidence and its propensity to metastasize. Several data such as: i) reported cases of concomitant melanoma and BP; ii) results from association studies; iii) BP onset following immune check-point inhibitors therapy; iv) expression of BP antigens in transformed melanocytes; and vi) circulating autoantibodies to BP antigens in melanoma patients suggest an intriguing, although unproven, possible association between melanoma and BP. However, a possible causative link is still debated and the putative pathogenetic mechanism underlying this association is unclear. This review aims to describe and discuss the possible relationship between BP and melanoma and give an overview of the speculations for or against this association. Of note, if demonstrated, this association could unwrap considerations of clinical relevance that represent new research frontiers.

Fungal Peptidomelanin: A Novel Biopolymer for the Chelation of Heavy Metals

Melanin is an amorphous, highly heterogeneous polymer found across all kingdoms of life. Although the properties of melanin can greatly vary, most forms are insoluble and strongly absorb light, appearing dark brown to black. Here, we describe a water-soluble form of melanin (peptidomelanin) secreted by the spores of Aspergillus niger (strain: melanoliber) during germination. Peptidomelanin is composed of an insoluble L-DOPA core polymer that is solubilized via short, copolymerized heterogeneous peptide chains forming a "corona" with a mean amino acid length of 2.6 ± 2.3. Based on in vitro experiments, we propose a biochemical copolymerization mechanism involving the hydroxylation of tyrosynylated peptides. Peptidomelanin is capable of chelating heavy metals such as lead, mercury, and uranium (as uranyl) in large quantities. Preliminary data indicates that peptidomelanin may have applications for the remediation of heavy metals in situ, including in agricultural settings.