Review of Fractional Nonablative Lasers for the Treatment of Dermatologic Conditions in Darker Skin Phototypes

BACKGROUND

Fractional nonablative lasers (NAFLs) have demonstrated efficacy and safety for treating dermatologic conditions in patients with darker skin phototypes. Nonablative lasers are preferred in darker skin tones due to lower risk of postinflammatory hyperpigmentation.

OBJECTIVE

This review aims to identify the ideal laser options and parameters for treating common dermatologic conditions in patients with skin types IV-VI.

MATERIALS AND METHODS

A comprehensive literature search was conducted on PubMed in May 2023. Of 1,065 articles were identified, and 40 articles met the inclusion criteria. The studies were classified based on design, dermatologic condition, and skin phototype of patients, and assigned levels of evidence according to the Modified Criteria of the Oxford Center of Evidence Based Medicine.

RESULTS

Strong level 1 evidence supports the treatment of melasma and atrophic scars using NAFL. Moderate level 2 evidence was found for using NAFL in acne vulgaris, striae, and skin rejuvenation; 45% of the studies examined skin types III-IV, 20% III-V, 7.5% II-IV, 5% II-V, 5% IV alone, and 2.5% I-IV.

CONCLUSION

Further research is needed to determine the optimal treatment modalities and parameters for skin types V and VI. Appropriate device selection and conservative treatment settings are crucial for optimizing outcomes and minimizing adverse events.

2-Mercaptonicotinoyl glycine prevents UV-induced skin darkening and delayed tanning in healthy subjects: A randomized controlled clinical study

BACKGROUND

Chronic nonextreme sun exposure induces two mechanisms of skin pigmentation, causing immediate darkening and delayed tanning. A new molecule, 2-mercaptonicotinoyl glycine (2-MNG), has been shown in vitro to inhibit both immediate darkening and new melanin synthesis via covalent conjugation of the thiol group of 2-MNG to melanin precursors.

OBJECTIVE

To evaluate 2-MNG in preventing both mechanisms in vivo.

METHODS

In a randomized, intra-individual and controlled study, 33 subjects with melanin-rich skin were exposed to UV daylight on designated areas on the back and treated with a cosmetic formula containing 0.5% or 1% 2-MNG alone or 0.5% 2-MNG in association with lipohydroxy acid (LHA, 0.3%) plus Mexoryl-SX (MSX, 1.5%). The respective vehicles were used as controls and 4-n-butyl-resorcinol (4-n-BR, 2.5%) as a positive reference.

RESULTS

2-MNG alone significantly reduced immediate darkening and inhibited new melanin production when compared with vehicle, with higher performance at 1% than at 0.5%. 2-MNG at 0.5% in association with LHA and MSX showed significantly higher performance than 2-MNG 0.5% alone. 2-MNG at 0.5% and 1% showed significantly better performance than 4-n-BR.

CONCLUSIONS

2-MNG inhibited both UV-induced skin pigmentation mechanisms in vivo. The association of 2-MNG with LHA plus MSX showed the highest efficacy on melanin-rich skin with pigmentation induced by UV exposure.

Vitiligo non-responding lesions to narrow band UVB have intriguing cellular and molecular abnormalities that may prevent epidermal repigmentation

We have discovered that human vitiligo patients treated with narrow-band UVB (NBUVB) demonstrated localized resistance to repigmentation in skin sites characterized by distinct cellular and molecular pathways. Using immunostaining studies, discovery-stage RNA-Seq analysis, and confirmatory in situ hybridization, we analyzed paired biopsies collected from vitiligo lesions that did not repigment after 6 months of NBUVB treatment (non-responding) and compared them with repigmented (responding) lesions from the same patient. Non-responding lesions exhibited acanthotic epidermis, had low number of total, proliferative, and differentiated melanocyte (MC) populations, and increased number of senescent keratinocytes (KCs) and of cytotoxic CD8+ T cells as compared with responding lesions. The abnormal response in the non-responding lesions was driven by a dysregulated cAMP pathway and of upstream activator PDE4B, and of WNT/β-catenin repigmentation pathway. Vitiligo-responding lesions expressed high levels of WNT10B ligand, a molecule that may prevent epidermal senescence induced by NBUVB, and that in cultured melanoblasts prevented the pro-melanogenic effect of α-MSH. Understanding the pathways that govern lack of NBUVB-induced vitiligo repigmentation has a great promise in guiding the development of new therapeutic strategies for vitiligo.

The potential role of UV and blue light from the sun, artificial lighting, and electronic devices in melanogenesis and oxidative stress

Our exposure to blue light from artificial sources such as indoor lights (mainly light-emitting diodes [LEDs]) and electronic devices (e.g., smartphones, computer monitors, and television screens), has increased in recent years, particularly during the recent coronavirus disease 2019 lockdown. This radiation has been associated to skin damage across its potential in generating reactive oxygen species in both the epidermis and the dermis, skin water imbalances and of potential activating melanin production. These circumstances make it important to determine whether current blue light exposure levels under artificial illumination and electronic devices exposure can cause the previously indicated disorders as compared to solar UV and visible radiation in a typical summer day. Blue light accounted for 25% of the sun's rays, approximately 30% of radiation emitted by electronic devices, and approximately from 6% to 40% of that emitted by indoor lights. The reference equations showed that the sun was the main source of effective irradiance for immediate and persistent pigmentation as well as for potential oxidative stress in our skin. Effective blue light exposure to artificial devices is significantly lower than the solar contribution. However, its contribution must be considered as accumulative dose effect, and especially in people with hypersensitivity promoting skin hyperpigmentation.

Study of a 532/1064 Fractional Picosecond Laser for Facial Rejuvenation

BACKGROUND AND OBJECTIVES

Picosecond (ps) fractional lasers create small wounds, presumably by laser-induced optical breakdown. We studied a ps fractional laser in the treatment of wrinkles and mottled pigment.

MATERIALS AND METHODS

This was a single center, prospective, open-label clinical trial. Patients with at least 2 facial areas, with visible wrinkles and dyschromia, were enrolled in the study and received 3 treatments at monthly intervals and appeared at 3 follow-up visits at 1, 3, and 6 months after treatment. The laser is an 800 ps fractional system with nominal 10 mm macrospot diameter. Both 532 nm and 1,064 nm wavelengths were applied in each subject. Wrinkle and pigmentation clearance were assessed by 2 blinded investigators using a 5-point clearance scale. Skin improvement was assessed by investigators using the 5-point Global Aesthetic Improvement (GAI) Scale based on before/after photographs for the following categories: (1) fine lines/wrinkles and (2) pigmentation.

RESULTS

A total of 18 healthy subjects at a single site were enrolled. At least moderate pigmentation and fine line/wrinkles improvement were observed in 93% and 79% of patients at 1 month after the last treatment according to GAI, respectively. Pigment clearance approached a mean of approximately 40%.

CONCLUSION

A ps 1,064/532 fractional laser achieves reduction in fine lines and pigment.

Attenuation Effect of Radiofrequency Irradiation on UV-B-Induced Skin Pigmentation by Decreasing Melanin Synthesis and through Upregulation of Heat Shock Protein 70

Excess melanin deposition in the skin causes cosmetic problems. HSP70 upregulation decreases microphthalmia-associated transcription factor (MITF) expression, which eventually decreases tyrosinase activity and melanogenesis. Ultraviolet (UV) radiation upregulates p53, which increases the melanocortin receptor (MC1R) and MITF. Furthermore, HSP70 decreases p53 and radiofrequency irradiation (RF) increases HSP70. We evaluated whether RF increased HSP70 and decreased p53, consequently decreasing the MITF/tyrosinase pathway and melanogenesis in UV-B radiated animal skin. Various RF combinations with 50, 100, and 150 ms and 5, 10, and 15 W were performed on the UV-B radiated mouse skin every 2 d for 28 d. When RF was performed with 100 ms/10 W, melanin deposition, evaluated by Fontana–Masson staining, decreased without skin crust formation in the UV-B radiated skin. Thus, we evaluated the effect of RF on decreasing melanogenesis in the HEMn and UV-B radiated skin at a setting of 100 ms/10 W. HSP70 expression was decreased in the UV-B radiated skin but was increased by RF. The expression of p53, MC1R, and MITF increased in the UV-B radiated skin but was decreased by RF. The expression of p53, MC1R, and MITF increased in the α-MSH treated HEMn but was decreased by RF. The decreasing effects of RF on p53, MC1R, CREB and MITF were higher than those of HSP70-overexpressed HEMn. The decreasing effect of RF on p53, MC1R, CREB, and MITF disappeared in the HSP70-silenced HEMn. MC1R, CREB, and MITF were not significantly decreased by the p53 inhibitor in α-MSH treated HEMn. RF induced a greater decrease in MC1R, CREB, and MITF than the p53 inhibitor. Therefore, RF may have decreased melanin synthesis by increasing HSP70 and decreasing p53, thus decreasing MC1R/CREB/MITF and tyrosinase activity.

The Pathogenesis and Management of Acne-Induced Post-inflammatory Hyperpigmentation

Acne vulgaris is a common inflammatory disease. Among patients with darker skin phototypes (Fitzpatrick III-VI), the inflammatory processes of acne stimulate excess melanogenesis and abnormal melanin deposition, leading to pigmentary sequelae known as post-inflammatory hyperpigmentation and post-inflammatory erythema in all skin tones, although post-inflammatory hyperpigmentation is more common in darker skin and post-inflammatory erythema in lighter skin. These pigmentary alterations can be long lasting and are often more distressing to patients than the active acne lesions. This article discusses what is known about acne-related pigmentation, much of which is extrapolated from general study of nonspecific pigment deposition. Because dyspigmentation poses both a significant clinical concern to patients and a therapeutic challenge to clinicians, we formed a working group consisting of pigmentary experts with the aim of increasing awareness and education of acne-related pigmentary sequelae.

Blue Light and the Skin

In photodermatology, UV radiation is the component of the solar system that has attracted the most interest as it represents the greatest risk of skin damage from solar exposure. Efficient protection strategies have therefore been developed to protect skin against powerful solar radiation. Recently, there has been increasing evidence to suggest that less energetic radiation, such as visible light and infrared radiation, might also influence skin physiology. Yet, it remains unclear, regarding risk assessment, whether visible light irradiation induces positive or negative effects in skin and when appropriate protection is needed. This review focuses primarily on blue light as part of the visible spectrum and sets out current mechanistic understanding of the benefits and risks of blue-light exposure to skin. Furthermore, it discusses phototherapies and potential strategies for protecting against detrimental effects of blue light such as hyperpigmentation and premature skin aging.

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

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

Safety and Efficacy of Tattoo Removal Using a Dual-Wavelength 1064/532-nm Picosecond Laser in Patients With Fitzpatrick Skin Type III and IV

BACKGROUND AND OBJECTIVES

To investigate the safety and efficacy of a dual-wavelength 1064/532-nm picosecond-domain laser for tattoo removal in Vietnamese patients.

STUDY DESIGN/MATERIALS AND METHODS

This prospective clinical study enrolled 30 subjects with 52 decorative tattoos treated with up to six treatments of laser removal at intervals of 6-8 weeks. Safety and efficacy were assessed at each treatment session and at 4 weeks after the final session. A "good" response was defined as at least 75% clearance of tattoo pigments.

RESULTS

A significant reduction of tattoo appearance was achieved in all subjects. 88.5% of tattoos exhibited a "good" response to treatment by the end of the six sessions and more than 36% of tattoos exhibited better than "good" responses. Adverse events were common in the early period after treatment but did not persist in most patients. Only one case of prolonged hypopigmentation was reported.

CONCLUSIONS

Treatment using a 1064/532-nm picosecond laser is an effective approach for removal of decorative tattoos, which poses a minimal risk of long-term adverse events in patients with Fitzpatrick skin type III or IV. Lasers Surg. Med. © 2020 Wiley Periodicals LLC.

NNT mediates redox-dependent pigmentation via a UVB- and MITF-independent mechanism

Ultraviolet (UV) light and incompletely understood genetic and epigenetic variations determine skin color. Here we describe an UV- and microphthalmia-associated transcription factor (MITF)-independent mechanism of skin pigmentation. Targeting the mitochondrial redox-regulating enzyme nicotinamide nucleotide transhydrogenase (NNT) resulted in cellular redox changes that affect tyrosinase degradation. These changes regulate melanosome maturation and, consequently, eumelanin levels and pigmentation. Topical application of small-molecule inhibitors yielded skin darkening in human skin, and mice with decreased NNT function displayed increased pigmentation. Additionally, genetic modification of NNT in zebrafish alters melanocytic pigmentation. Analysis of four diverse human cohorts revealed significant associations of skin color, tanning, and sun protection use with various single-nucleotide polymorphisms within NNT. NNT levels were independent of UVB irradiation and redox modulation. Individuals with postinflammatory hyperpigmentation or lentigines displayed decreased skin NNT levels, suggesting an NNT-driven, redox-dependent pigmentation mechanism that can be targeted with NNT-modifying topical drugs for medical and cosmetic purposes.

Stem cell spreading dynamics intrinsically differentiate acral melanomas from nevi

Early differential diagnosis between malignant and benign tumors and their underlying intrinsic differences are the most critical issues for life-threatening cancers. To study whether human acral melanomas, deadly cancers that occur on non-hair-bearing skin, have distinct origins that underlie their invasive capability, we develop fate-tracing technologies of melanocyte stem cells in sweat glands (glandular McSCs) and in melanoma models in mice and compare the cellular dynamics with human melanoma. Herein, we report that glandular McSCs self-renew to expand their migratory progeny in response to genotoxic stress and trauma to generate invasive melanomas in mice that mimic human acral melanomas. The analysis of melanocytic lesions in human volar skin reveals that genetically unstable McSCs expand in sweat glands and in the surrounding epidermis in melanomas but not in nevi. The detection of such cell spreading dynamics provides an innovative method for an early differential diagnosis of acral melanomas from nevi.

Ultraviolet-B irradiance and cumulative dose combine to determine performance and survival

Despite decades of research, the role of elevated solar ultraviolet-B radiation (UVBR; 280-315 nm) in shaping amphibian populations remains ambiguous. These difficulties stem partly from a poor understanding of which parameters of UVBR exposure - dose, irradiance, and time interval - determine UVBR exposure health risk, and the potentially erroneous assumption that effects are proportional to the dose of exposure, irrespective of the administered regime (Bunsen-Roscoe Law of Reciprocity; BRL). We tested if the BRL holds with respect to UVBR-induced physiological effects in amphibians by acutely exposing tadpoles of the Australian green tree frog (Litoria caerulea) to a combination of different UVBR irradiances and doses in a fully factorial experiment. The BRL was invalid across all metrics assessed, with UVBR irradiance influencing the effects of a given dose on growth, coloration and burst swimming performance of larvae. We demonstrated some of the first empirical evidence for beneficial physiological effects of UVBR exposure in a larval amphibian, with improvements in growth, burst swimming performance and survival at the highest UVBR doses, contrary to hypotheses. Our findings demonstrate the species-specific nature of amphibian responses to UVBR, and the importance of UVBR irradiance in influencing the long-term physiological effects of a given dose of radiation. This work enhances our understanding of which parameters of complex UVBR exposures determine amphibian health risk.

A Systematic Review on the Treatment of Dermatosis Papulosa Nigra

Dermatosis papulosa nigra (DPN) is a benign skin condition that is primarily reported in skin of color patients. While prevalent, treatment options are limited and the benign course of DPNs may cause them to be overlooked by clinicians. However, large and multiple lesions in cosmetically sensitive areas may be emotionally and socially distressful to patients. There are few literature reviews examining treatment options for this condition. A literature search was performed using PubMed, Medline, Embase, and Web of Science databases. 67 articles were identified and 15 studies met the inclusion criteria. Our findings demonstrate that laser therapy is becoming increasingly utilized as a safe and efficacious treatment for DPNs in skin of color patients. J Drugs Dermatol. 20(4):467-472. doi:10.36849/JDD.2021.5555.

Post-Inflammatory Hyperpigmentation: A Review of Treatment Strategies

Post-inflammatory hyperpigmentation (PIH) is a reactive process resulting from increased melanin or abnormal distribution of melanin secondary to inflammatory skin conditions, dermatologic therapies, and external stimuli. Because PIH is a common condition that has a substantial effect on the quality of life, an understanding of its treatment modalities is essential. Though there are many therapeutic strategies for hyperpigmentary conditions such as melasma that are described in the literature, fewer studies focus on PIH. This article aims to provide a comprehensive literature review of therapies specifically used to treat PIH, such as topical combinations, chemical peels, and lasers. J Drugs Dermatol. 2020;19(8): doi:10.36849/JDD.2020.4887.

Seven traditional Chinese herbal extracts fermented by Lactobacillus rhamnosus provide anti-pigmentation effects by regulating the CREB/MITF/tyrosinase pathway

Skin pigmentation is resulted from several processes, such as melanin synthesis transportation and abnormal melanin accumulation in keratinocytes. Various studies have suggested that seven traditional Chinese herbal extracts from Atractylodes macrocephala, Paeonia lactiflora, Bletilla striata, Poria cocos, Dictamnus dasycarpus, Ampelopsis japonica and Tribulus terrestris (which we collectively named ChiBai), show several protective effects toward skin-related diseases. Lactobacillus rhamnosus, a lactic acid bacterium, has been reported to treat skin inflammation and atopic dermatitis. In this study, the broth produced by the cofermentation of ChiBai with Lactobacillus rhamnosus was studied for its effects on skin pigmentation through in vitro and in vitro experiments. In the in vitro experiments, we found that the fermented broth of ChiBai (FB-ChiBai) suppressed alpha-melanocyte stimulating hormone (α-MSH)-induced melanogenesis in B16F0 murine melanoma cells without any cytotoxicity at a concentration of 0.5%. FB-ChiBai significantly attenuated melanin production, tyrosinase activities and melanogenesis-related signaling pathways. Treatment with FB-ChiBai also reduced the nuclear translocation and promoter binding activities of MITF. In the in vivo experiments, FB-ChiBai was topically applied to the dorsal skin of C57BL/6J nude mice and concurrently irradiated with UVB, three times a week for 8 weeks. The results indicated that FB-ChiBai alleviated UVB-induced hyperpigmentation by reducing epidermal hyperplasia and inhibiting the CREB/MITF/tyrosinase pathway. In conclusion, our data indicated that the anti-melanogenic effects of FB-ChiBai are mediated by the inhibition of CREB/MITF/tyrosinase signaling pathway. The findings suggest that FB-ChiBai can protect against UV-B irradiation and that it might be used as an agent in cosmetic products to protect against UVB-induced hyperpigmentation.

Visible light. Part II: Photoprotection against visible and ultraviolet light

Cutaneous photobiology studies have focused primarily on the ultraviolet portion of the solar spectrum. Visible light (VL), which comprises 50% of the electromagnetic radiation that reaches the Earth's surface and, as discussed in Part I of this CME, has cutaneous biologic effects, such as pigment darkening and erythema. Photoprotection against VL includes avoiding the sun, seeking shade, and using photoprotective clothing. The organic and inorganic ultraviolet filters used in sunscreens do not protect against VL, only tinted sunscreens do. In the United States, these filters are regulated by the Food and Drug Administration as an over-the-counter drug and are subject to more stringent regulations than in Europe, Asia, and Australia. There are no established guidelines regarding VL photoprotection. Alternative measures to confer VL photoprotection are being explored. These novel methods include topical, oral, and subcutaneous agents. Further development should focus on better protection in the ultraviolet A1 (340-400 nm) and VL ranges while enhancing the cosmesis of the final products.

Intense Pulsed Light: A Methodical Approach to Understanding Clinical Endpoints

BACKGROUND

Intense Pulsed Light (IPL) is a non-coherent polychromatic broadband filtered flashlamp that emits light in the spectrum of approximately 400–1200 nm. Its effects on photorejuvenation are well documented. The goal of this study is to help practitioners better conceptualize and fine tune IPL device settings in order to produce the most effective and safest clinical outcome.

MATERIALS/METHODS

This was a prospective study testing several filters (515 nm; 560 nm; 590 nm and 530–650; 900–1200 nm vascular filter), fluences, pulse durations, and pulse numbers (ie, multiple sequence pulsing or MSP) with a new IPL system.

RESULTS

Post-procedure erythema response was more pronounced with increasing fluence, decreasing wavelength, fewer pulses and shorter pulse duration. The exception was the 515 nm filter with regard to pulse duration, which was observed to have a more pronounced response with longer pulse durations. The overall clinical outcome at the 4-week follow-up visit demonstrated greatest improvement in erythema and pigmentation using the 515 nm filter on a Fitzpatrick Skin Type III individual.

CONCLUSION

Greatest clinical endpoint response at 4-week follow-up was observed with more robust initial responses. This was most apparent at higher fluence levels and fewer pulse counts. However, when the IPL is pushed to aggressive parameters, there is risk of hypopigmentation and hair loss as seen in this case study. Skin type is an important consideration when using IPL and MSP adds to its safety profile. J Drugs Dermatol. 2021;20(2):203-207. doi:10.36849/JDD.5638.

New Protocol for Long-Term Results With a Multi-Pulse Nd:YAG Laser for Melasma Treatment: A Descriptive Cohort Study

BACKGROUND

Melasma is a photoaging condition with a typical clinical and histological pattern under a genetic and epigenetic context. Over the years, many treatments modalities have been proposed including topical agents, oral medication, procedures, and combination treatments aiming at different aspects of the pathogenesis including photodamage, inflammation, vascularity, and pigmentation. Recently, lasers have become an alternative for the treatment of melasma using thermal energy to target, in a selective way, the chromophore found in the skin such as melanin.

OBJECTIVE

This study aimed to show how we have implemented a multifactorial approach that not only treats the symptoms but addresses the primary underlying cause of melasma.

MATERIALS AND METHODS

Twenty female patients with dermal and mixed melasma were admitted to Medical Art between December 2017 and April 2018 and received a four-step Fotona laser protocol. Clinical evaluation of a clearance percentage of melasma was performed 1 month after the last session by a blinded dermatologist grading the images taken during the study. Follow-up evaluation was performed at 6 and 12 months following the completion of the laser treatment, which was 6 sessions. Patients were also asked following the end of the treatment about their satisfaction, which was evaluated with a 5-point scale.

RESULTS

This descriptive cohort study included patients with melasma who underwent the four-step laser protocol treatment at 2-week intervals. The clearance percentage score showed 70% with excellent reduction, 25% with good reduction in appearance of melasma, none of the patients with a fair reduction, and 5% with a poor reduction. The mean score of patient satisfaction was 4,65 ± 0,93 (93%).

CONCLUSION

Results of this study indicate that the four-step Fotona laser protocol is a safe and effective treatment option for melasma. J Drugs Dermatol. 2021;20(2):150-154. doi:10.36849/JDD.1221.

Effects of Electromagnetic Waves with LTE and 5G Bandwidth on the Skin Pigmentation In Vitro

With the rapid growth of wireless communication devices, the influences of electromagnetic fields (EMF) on human health are gathering increasing attention. Since the skin is the largest organ of the body and is located at the outermost layer, it is considered a major target for the health effects of EMF. Skin pigmentation represents one of the most frequent symptoms caused by various non-ionizing radiations, including ultraviolet radiation, blue light, infrared, and extremely low frequency (ELF). Here, we investigated the effects of EMFs with long-term evolution (LTE, 1.762 GHz) and 5G (28 GHz) bandwidth on skin pigmentation in vitro. Murine and Human melanoma cells (B16F10 and MNT-1) were exposed to either LTE or 5G for 4 h per day, which is considered the upper bound of average smartphone use time. It was shown that neither LTE nor 5G exposure induced significant effects on cell viability or pigmentation. The dendrites of MNT-1 were neither lengthened nor regressed after EMF exposure. Skin pigmentation effects of EMFs were further examined in the human keratinocyte cell line (MNT-1-HaCaT) co-culture system, which confirmed the absence of significant hyper-pigmentation effects of LTE and 5G EMFs. Lastly, MelanoDerm™, a 3D pigmented human epidermis model, was irradiated with LTE (1.762 GHz) or 5G (28 GHz), and image analysis and special staining were performed. No changes in the brightness of MelanoDerm™ tissues were observed in LTE- or 5G-exposed tissues, except for only minimal changes in the size of melanocytes. Collectively, these results imply that exposure to LTE and 5G EMFs may not affect melanin synthesis or skin pigmentation under normal smartphone use condition.

Recent information on photoaging mechanisms and the preventive role of topical sunscreen products

The main environmental element causing photoaging is ultraviolet (UV) light, and this involves an extrinsic mechanism of skin aging superimposed on an intrinsic process. Clinical (evident) characteristics of photoaging include the presence of deep wrinkles, deterioration of skin laxity, and hyperpigmentation. In the UV light spectrum, UVA and UVB radiation cause the most damage in photoaging. UVB light has shorter wavelengths and is mostly absorbed by the stratum corneum, causing erythema and changes in the epidermis, whereas UV rays with longer wavelengths (i.e., UVA) penetrate to the deepest layer of the skin (i.e., the dermis) and interact with DNA. As a result of UV radiation, chemical reactions in the skin produce reactive oxygen species (ROS), which cause protein denaturation, impairment of RNA and DNA synthesis, and damage to the skin structure. Using local sunscreen agents can not only prevent sunburn, but also help prevent photocarcinogenesis and photoaging. Therefore, many epidemiological studies have been conducted with results showing credible and positive evidence for the safety and efficacy of sunscreen to prevent photoaging and photocarcinogenesis.

Pathogenic and therapeutic role for NRF2 signaling in ultraviolet light-induced skin pigmentation

Mottled skin pigmentation and solar lentigines from chronic photodamage with aging involve complex interactions between keratinocytes and melanocytes. However, the precise signaling mechanisms that could serve as therapeutic targets are unclear. Herein, we report that expression of nuclear factor erythroid 2-related factor 2 (NRF2), which regulates reduction-oxidation reactions, is altered in solar lentigines and photodamaged skin. Moreover, mottled skin pigmentation in humans could be treated with topical application of the NRF2 inducer sulforaphane (SF). Similarly, UV light-induced pigmentation of WT mouse ear skin could be treated or prevented with SF treatment. Conversely, SF treatment was unable to reduce UV-induced ear skin pigmentation in mice deficient in NRF2 or in mice with keratinocyte-specific conditional deletion of IL-6Rα. Taken together, NRF2 and IL-6Rα signaling are involved in the pathogenesis of UV-induced skin pigmentation, and specific enhancement of NRF2 signaling could represent a potential therapeutic target.

Dermatologic Laser Side Effects and Complications: Prevention and Management

The evolution of modern laser and light-based systems has mirrored the demand for clinically effective treatments and the need for safer technologies with reduced postoperative recovery, side effects, and complications. With each new generation of lasers, more selective tissue destruction can be achieved with reduced unwanted sequelae. Patient selection and preparation, operator technique, and expeditious recognition and management of post-treatment side effects are paramount in avoiding complications and patient dissatisfaction. An overview of important variables to consider for dermatologic laser treatments are presented in order to provide a framework to reduce the severity and duration of possible post-treatment side effects and complications.

A new model to investigate UVB-induced cellular senescence and pigmentation in melanocytes

Ultraviolet (UV) light is known to potentially damage human skin and accelerate the skin aging process. Upon UVB exposure, melanocytes execute skin protection by increasing melanin production. Senescent cells, including senescent melanocytes, are known to accumulate in aged skin and contribute to the age-associated decline of tissue function. However, melanocyte senescence is still insufficiently explored. Here we describe a new model to investigate mechanisms of UVB-induced senescence in melanocytes and its role in photoaging. Exposure to mild and repeated doses of UVB directly influenced melanocyte proliferation, morphology and ploidy. We confirmed UVB-induced senescence with increased senescence-associated β-galactosidase positivity and changed expression of several senescence markers, including p21, p53 and Lamin B1. UVB irradiation impaired proteasome and increased autophagic activity in melanocytes, while expanding intracellular melanin content. In addition, using a co-culture system, we could confirm that senescence-associated secretory phenotype components secreted by senescent fibroblasts modulated melanogenesis. In conclusion, our new model serves as an important tool to explore UVB-induced melanocyte senescence and its involvement in photoaging and skin pigmentation.

The 1440 nm and 1927 nm Nonablative Fractional Diode Laser: Current Trends and Future Directions

Clinical characteristics of skin exposed to ultraviolet and infrared radiation include dryness, dyschromia, laxity, roughness, sallowness, scaling, telangiectasia, and wrinkles. Fractional photothermolysis promotes skin remodeling by formation of new dermal collagen. The nonablative fractional diode laser (NFDL) system employs fractional photothermolysis to rejuvenate the skin, using 2 distinct handpieces for wavelengths of 1440 nm and 1927 nm. Fractional photothermolysis from nonablative fractional diode lasers facilitates delivery of small molecular-weight compounds, such as L-ascorbic acid, through the skin without compromising barrier function of the stratum corneum. Both handpieces of the NFDL system are effective for rejuvenation of photodamaged facial skin, providing clinical improvement in skin tone, skin texture, fine lines, and dyschromia and reducing the number of detectable skin pores. Application of the 1927 nm wavelength handpiece has shown clinical improvement of hyperpigmentation, melasma, and postinflammatory hyperpigmentation, which have been challenging to treat effectively with other laser devices. With a target chromophore of water, the infrared energy of the 1440 nm and 1927 nm NFDL system is appropriate for skin rejuvenation and treatment of dyschromia in skin of color, with a reduced risk of the adverse events observed with other nonablative and ablative fractional lasers. Clinical data have demonstrated that both the 1440 nm and 1927 nm wavelengths are effective, with high levels of patient satisfaction, transient side effects, and minimal patient downtime.

Administration of Apple Polyphenol Supplements for Skin Conditions in Healthy Women: A Randomized, Double-Blind, Placebo-Controlled Clinical Trial

This clinical study was performed to evaluate the effects of continuous apple polyphenol (AP) administration on facial skin conditions and pigmentation induced by ultraviolet (UV) irradiation in healthy women participants. Participants (n = 65, age 20–39 years) were randomized to receive tablets containing AP (300 or 600 mg/day) or placebo in a double-blinded, placebo-controlled clinical trial. Continuous administration of AP for 12 weeks significantly prevented UV irradiation induced skin pigmentation (erythema value, melanin value, L value), although a dose-dependent relationship was not clearly observed. In contrast, no significant differences were detected between the groups with regard to water content and trans-epidermal water loss. Our study demonstrated that APs and their major active compounds, procyanidins, have several health benefits. Here, we report that continuous administration of AP for 12 weeks alleviated UV irradiation induced skin pigmentation, when compared with placebo, in healthy women.

Photoprotection and Skin Pigmentation: Melanin-Related Molecules and Some Other New Agents Obtained from Natural Sources

Direct sun exposure is one of the most aggressive factors for human skin. Sun radiation contains a range of the electromagnetic spectrum including UV light. In addition to the stratospheric ozone layer filtering the most harmful UVC, human skin contains a photoprotective pigment called melanin to protect from UVB, UVA, and blue visible light. This pigment is a redox UV-absorbing agent and functions as a shield to prevent direct UV action on the DNA of epidermal cells. In addition, melanin indirectly scavenges reactive oxygenated species (ROS) formed during the UV-inducing oxidative stress on the skin. The amounts of melanin in the skin depend on the phototype. In most phenotypes, endogenous melanin is not enough for full protection, especially in the summertime. Thus, photoprotective molecules should be added to commercial sunscreens. These molecules should show UV-absorbing capacity to complement the intrinsic photoprotection of the cutaneous natural pigment. This review deals with (a) the use of exogenous melanin or melanin-related compounds to mimic endogenous melanin and (b) the use of a number of natural compounds from plants and marine organisms that can act as UV filters and ROS scavengers. These agents have antioxidant properties, but this feature usually is associated to skin-lightening action. In contrast, good photoprotectors would be able to enhance natural cutaneous pigmentation. This review examines flavonoids, one of the main groups of these agents, as well as new promising compounds with other chemical structures recently obtained from marine organisms.

Discovery of a Highly Selective MC1R Agonists Pentapeptide to Be Used as a Skin Pigmentation Enhancer and with Potential Anti-Aging Properties

One of the first lines of cutaneous defense against photoaging is (a) the synthesis of melanin and (b) the initiation of an oxidative stress response to protect skin against the harmful effects of solar radiation. Safe and selective means to stimulate epidermal pigmentation associated with oxidative stress defense are; however, scarce. Activation of the melanocortin-1 receptor (MC1R) on epidermal melanocytes represents a key step in cutaneous pigmentation initiation and, additionally, it regulates cellular defense mechanisms like oxidative stress and DNA-repair. Thus, making the activation of MC1R an attractive strategy for modulating skin pigmentation and oxidative stress. In this context, we designed and synthesized pentapeptides that act as MC1R agonists. These peptides bound, with high potency, to MC1R and activated cAMP synthesis in CHO cells expressing human MC1R. Using one lead pentapeptide, we could show that this activation of MC1R was specific as testing the activation of other G-protein coupled receptors, including the MC-receptor family, was negative. In vitro efficacy on mouse melanoma cells showed similar potency as for the synthetic MC1R agonist alpha-melanocyte stimulating hormone (NDP-alpha-MSH). Moreover, we could reproduce this activity in human skin tissue culture. The lead pentapeptide was able to induce ex-vivo protein expression of key melanogenesis markers melanocyte inducing transcription factor (MITF), tyrosinase (TYR), and tyrosinase-related protein 1 (TYRP-1). Concerning oxidative stress response, we found that the pentapeptide enhanced the activation of Nrf2 after UVA-irradiation. Our results make this pentapeptide an ideal candidate as a skin pigmentation enhancer that mimics alpha-MSH and may also have anti-photoaging effects on the skin.

Oral Polypodium Leucotomos Extract and Its Impact on Visible Light-Induced Pigmentation in Human Subjects

BACKGROUND: Visible light (VL) has multiple effects on the skin that currently available sunscreens do not protect against. Polypodium leucotomos extract (PLE) has properties that may offer protection against VL. OBJECTIVES: To determine the effectiveness of PLE in preventing VL-induced effects. METHODS: Twenty-two subjects with Fitzpatrick skin phototype IV-VI were enrolled. On day 0, subjects were irradiated with VL. Clinical Investigator’s Global Assessment (IGA) scoring and spectroscopic evaluations were performed immediately, 24 hours, and 7 days after irradiation. Subjects then received a 28-day supply of PLE (480 mg daily). Irradiation and evaluation were repeated. Three 4-mm punch biopsies were obtained for immunohistochemistry analysis: one from normal unirradiated skin and the other two twenty-four hours after irradiation, pre- and post-PLE, from sites irradiated with highest dose of VL. RESULTS: All subjects had immediate pigment darkening, persistent pigment darkening, and delayed tanning both pre- and post-PLE. For the highest VL dose (480 J/cm²) spectroscopic assessments demonstrated a statistically significant decrease in persistent pigment darkening and delayed tanning post-PLE. In addition, there was a significant decrease in cyclooxygenase-2, and a trend towards decreases in the markers for cellular damage post-PLE. While there was a trend towards lower IGA scores post-PLE, statistical significance was not reached possibly due to lack of sensitivity of the visual IGA scoring system in detecting small changes. CONCLUSIONS: Spectroscopic data and immunohistochemistry indicate an effect of PLE on visible light induced effects. As such, PLE may be used as an adjuvant to traditional means of photoprotection to protect against the effects of VL. Clinical trial registration number: NCT02904798. J Drugs Dermatol. 2019;18(12):1198-1203.

Impact of ultraviolet radiation on dermal and epidermal DNA damage in a human pigmented bilayered skin substitute

Our laboratory has developed a scaffold-free cell-based method of tissue engineering to produce bilayered tissue-engineered skin substitutes (TESs) from epidermal and dermal cells. However, TES pigmentation is absent or heterogeneous after grafting, due to a suboptimal number of melanocytes in culture. Our objectives were to produce TESs with a sufficient quantity of melanocytes from different pigmentation phototypes (light and dark) to achieve a homogeneous color and to evaluate whether the resulting pigmentation was photoprotective against ultraviolet radiation (UVR)-induced DNA damage in the dermis and the epidermis. TESs were cultured using different concentrations of melanocytes (100, 200, and 1,500 melanocytes/mm² ), and pigmentation was evaluated in vitro and after grafting onto an athymic mouse excisional model. Dermal and epidermal DNA damage was next studied, exposing pigmented TESs to 13 and 32.5 J/cm² UVR in vitro. We observed that melanocyte cell density increased with culture time until reaching a plateau corresponding to the cell distribution of native skin. Pigmentation of melanocyte-containing TESs was similar to donor skin, with visible melanin transfer from melanocytes to keratinocytes. The amount of melanin in TESs was inversely correlated to the UVR-induced formation of cyclobutane pyrimidine dimer in dermal fibroblasts and keratinocytes. Our results indicate that the pigmentation conferred by the addition of melanocytes in TESs protects against UVR-induced DNA damage. Therefore, autologous pigmented TESs could ensure photoprotection after grafting.

Therapeutic Insights in Melasma and Hyperpigmentation Management

Melasma and postinflammatory hyperpigmentation (PIH) are the most common forms of dyschromia in patients with skin of color. Both are associated with a high psychological burden of disease. To exacerbate this burden, the need for treatment is chronic, and the results are often suboptimal in the eyes of the patient. Successful treatment is therefore contingent upon a correct diagnosis, patient education, and a carefully considered therapeutic approach. The latter is often multimodal in its design, incorporating sun protection, topical and systemic medications, and in some cases, procedural intervention. Although topical hydroquinone is a mainstay of treatment for melasma and PIH, there are alternatives that have emerged as of late that have shown varying degrees of promise, both in terms of safety and efficacy. In this article, we review the epidemiological, clinical, and histologic features of melasma and postinflammatory hyperpigmentation, and discuss important considerations for both established and emerging treatments for these vexingly common and difficult to treat conditions.

A Survey-Based Comparison of Sun Safety Practices in a Representative Cohort of the General Public Versus Attendees of a Skin Cancer Screening

A large proportion of data on photoprotective practices is yielded from free skin cancer screenings. However, the sun safety practices of populations who seek these skin cancer screenings may differ from the general public. To examine differences in skin cancer prevention practices and risk factors, we surveyed pedestrians at six locations in Washington, DC (public group, n=285) and attendees of a free skin cancer screening (screening group, n=144) using an IRB-approved survey. The screening group was older and included more individuals with fair skin than the public group. Respondents from the screening group were significantly more likely to always wear sunscreen, always seeks shade, and always or sometimes wear sun-protective clothing than the public group (P<0.05). To examine whether younger and non-white participants, who were less likely to attend our free screening, have different practices and risk factors than older and white participants, respectively, we compared survey answers for all participants by age and race. White participants were more likely to always or sometimes wear sunscreen and sun-protective clothing than non-white participants (P<0.05). Patients over 61 years were more likely to always seek shade and wear sun-protective clothing than those younger than 31 years (P<0.05). Therefore, free skin cancer screenings need to be better popularized among non-white and younger populations or more effective educational vehicles are needed. J Drugs Dermatol. 2019;18(7):649-653.

Practical Applications for Medical and Aesthetic Treatment of Skin of Color With a New 650-Microsecond Laser

The following roundtable is edited from discussion between the authors concerning treatment with the 650-microsecond 1064nm Nd:YAG laser. These dermatologist experts share their expertise, experience, and treatment pearls regarding the device for medical and aesthetic use, and in treatment of skin of color (SOC).

Laser Treatment of Skin of Color for Medical and Aesthetic Uses With a New 650-Microsecond Nd:YAG 1064nm Laser

Individuals with skin of color are a rapidly growing portion of the cosmetic procedures market. There are unique challenges to treating skin conditions in skin of color patients. This article and roundtable discussion focus on the use of energy-based modalities, particularly a 650-microsecond 1064nm laser that delivers energy in a collimated beam. Alone or in combination with other therapies, the 650-microsecond 1064nm laser has been used successfully to treat melasma, acne, postinflammatory hyperpigmentation, pseudofolliculitis barbae, hair removal, acne keloidalis nuchae, and aging skin in skin of color. J Drugs Dermatol. 2019;18(4 Suppl 1):s135-137.

Photoaging and Photoprotection in United States Hispanic Population

Photoaging is a complex and chronic process that induces structural and functional changes in sun-exposed skin, including coarse wrinkles, laxity, dyschromia, telangiectasias, and potential precancerous lesions. Pigmented skin presents different structure and physiology that contribute to distinctive photoaging process. The skin of color population is reported to “age better” than their Caucasian counterparts in general, with fewer wrinkles and better skin texture. However, pigmentary disorders and sun-exposure related dyschromia are highly prevalent in skin of color. Hispanics are the fastest growing population in the U.S. and represents a heterogenous group of people with different skin tones and Fitzpatrick phototypes. They demonstrate large diversity and heterogeneity in skin physiology, pigmentary disorders, and photoaging-related skin color shifting. Specific concerns around hyperpigmentation, skin tone evenness, and texture or roughness are very common among Hispanics, demanding targeted medical and cosmeceutical solutions. Customized daily routines including sufficient photo-protection are essential to address such needs. This mini review identifies some of the specific skin concerns of Hispanics in America and emphasizes the needs for long-term sunscreen use and education. J Drugs Dermatol. 2019;18(3 Suppl):s121-123.

Cosmetic Laser Procedures in Latin Skin

Hispanics/Latinos are one of the fastest growing segments in the skin of color population in the United States. Utilization of lasers especially in people with skin of color requires a thorough understanding of laser physics and laser tissue interactions. In this article, we will outline the different lasers used in our practice based on each chromophore. Pretreatment recommendations as well as management of complications will also be shortly discussed. Our goal is for the readers to grasp the importance of proper device selection, understand the concept of selective photothermolysis, and the various treatment parameters required for optimal safety and efficacy. J Drugs Dermatol. 2019;18(3 Suppl):s127-131.

Evaluation of skin expression profiles of patients with vitiligo treated with narrow-band UVB therapy by targeted RNA-seq

BACKGROUND

Vitiligo is characterized by a lack of pigmentation in the skin. To date, there are no studies that analyze the changes in gene expression in the skin of vitiligo patients in response to narrow-band ultraviolet B (nb-UVB) phototherapy treatment.

OBJECTIVE

Explore the usefulness of new generation RNA sequencing in the identification of gene expression changes in the skin of vitiligo patients treated with nb-UVB phototherapy.

METHODS

Four skin biopsies (4mm in diameter) were collected from 45 Mexican vitiligo vulgaris patients, 2 specimens before and 2 after treatment with nb-UVB phototherapy, obtained from pigmented and non-pigmented tissue. RNA extracted from the biopsies was analyzed using the Illumina TruSeq Targeted RNA Expression protocol to study the expression of genes that participate in pathways of skin homeostasis. The 2 groups were compared using Student's t-test and the Mann-Whitney U-test.

RESULTS

The expression analysis identified differences in 12 genes included in this study after comparing the samples obtained before and after treatment: 5 genes involved in skin pigmentation, 2 genes involved in apoptosis, 2 genes involved in cell survival, 2 genes involved in oxidative stress responses and 1 gene involved in signal transduction mechanisms (p<0.05).

STUDY LIMITATIONS

The small size of skin biopsies limits the amount of RNA obtained, the number of genes to be analyzed and the use of conventional techniques such as RT-qPCR.

CONCLUSION

We demonstrated usefulness of new generation RNA sequencing in the identification of gene expression changes, in addition to identifying new targets in the study of vitiligo.

Melanin-concentrating hormone is a major substance mediating light wavelength-dependent skin color change in larval zebrafish

Melanosome dispersion is important for protecting the internal organs of fish against ultraviolet light, especially in transparent larvae with underdeveloped skin. Melanosome dispersion leads to dark skin color in dim light. Melanosome aggregation, on the other hand, leads to pale skin color in bright light. Both of these mechanisms are therefore useful for camouflage. In this study, we investigated a hormone thought to be responsible for the light wavelength-dependent response of melanophores in zebrafish larvae. We irradiated larvae using light-emitting diode (LED) lights with peak wavelengths (λ_max) of 355, 400, 476, 530, and 590 nm or fluorescent light (FL) 1-4 days post fertilization (dpf). Melanosomes in skin melanophores were more dispersed under short wavelength light (λ_max ≤ 400 nm) than under FL. Conversely, melanosomes were more aggregated under mid-long wavelength light (λ_max ≥ 476 nm) than under FL. In addition, long-term (1-12 dpf) irradiation of 400 nm light increased melanophores in the skin, whereas that of 530 nm light decreased them. In teleosts, melanin-concentrating hormone (MCH) aggregates melanosomes within chromatophores, whereas melanocyte-stimulating hormone, derived from proopiomelanocortin (POMC), disperses melanosomes. The expression of a gene for MCH was down-regulated by short wavelength light but up-regulated by mid-long wavelength light, whereas a gene for POMC was up-regulated under short wavelength light. Melanosomes in larvae (4 dpf) exposed to a black background aggregated when immersing the larvae in MCH solution. Yohimbine, an α₂-adrenergic receptor antagonist, attenuated adrenaline-dependent aggregation in larvae exposed to a black background but did not induce melanosome dispersion in larvae exposed to a white background. These results suggest that MCH plays a key role in the light wavelength-dependent response of melanophores, flexibly mediating the transmission of light wavelength information between photoreceptors and melanophores.

Homeostasis in Topical Photoprotection: Getting the Spectral Balance Right

The solar radiation range has harmful and beneficial effects. Sunscreens, which selectively block specific spectral regions, may potentially interfere with skin homeostasis. For instance, the ultraviolet (UV) B waveband produces erythema and DNA damage; simultaneously, it induces pre-vitamin D₃ synthesis. UVA1 and visible light can both induce pigmentation in skin phototypes IV–VI, and act in synergy to induce erythema and persistent pigment darkening. In contrast, UVA may contribute to blood pressure control and cardioprotection by inducing release of nitric oxide from intracutaneous photolabile nitric oxide derivatives. Finally, infrared A radiation alters the collagen equilibrium of the dermal extracellular matrix but is involved in the regulation of body temperature and in nitric oxide release, with a potential beneficial impact on blood pressure regulation. Ideally, photoprotection should thus be performed with a neutral density filter, mitigating all radiation ranges homogeneously, to maintain solar spectrum homeostasis. Natural compounds such as mycosporine-like amino acids are promising natural UV radiation-filtering compounds for an improved homeostasis with our environment. Lastly, we should not forget individual characteristics and behavior, as homeostasis differs according to individual phototypes and skin exposure behaviors.

MC1R: Front and Center in the Bright Side of Dark Eumelanin and DNA Repair

Melanin, the pigment produced by specialized cells, melanocytes, is responsible for skin and hair color. Skin pigmentation is an important protective mechanism against the DNA damaging and mutagenic effects of solar ultraviolet radiation (UV). It is acknowledged that exposure to UV is the main etiological environmental factor for all forms of skin cancer, including melanoma. DNA repair capacity is another major factor that determines the risk for skin cancer. Human melanocytes synthesize eumelanin, the dark brown form of melanin, as well as pheomelanin, which is reddish-yellow in color. The relative rates of eumelanin and pheomelanin synthesis by melanocytes determine skin color and the sensitivity of skin to the drastic effects of solar UV. Understanding the complex regulation of melanocyte function and how it responds to solar UV has a huge impact on developing novel photoprotective strategies to prevent skin cancer, particularly melanoma, the most fatal form, which originates from melanocytes. This review provides an overview of the known differences in the photoprotective effects of eumelanin versus pheomelanin, how these two forms of melanin are regulated genetically and biochemically, and their impact on the DNA damaging effects of UV exposure. Additionally, this review briefly discusses the role of paracrine factors, focusing on α-melanocortin (α-melanocyte stimulating hormone; α-MSH), in regulating melanogenesis and the response of melanocytes to UV, and describes a chemoprevention strategy based on targeting the melanocortin 1 receptor (MC1R) by analogs of its physiological agonist α-MSH.

Clinical and Biological Characterization of Skin Pigmentation Diversity and Its Consequences on UV Impact

Skin color diversity is the most variable and noticeable phenotypic trait in humans resulting from constitutive pigmentation variability. This paper will review the characterization of skin pigmentation diversity with a focus on the most recent data on the genetic basis of skin pigmentation, and the various methodologies for skin color assessment. Then, melanocyte activity and amount, type and distribution of melanins, which are the main drivers for skin pigmentation, are described. Paracrine regulators of melanocyte microenvironment are also discussed. Skin response to sun exposure is also highly dependent on color diversity. Thus, sensitivity to solar wavelengths is examined in terms of acute effects such as sunburn/erythema or induced-pigmentation but also long-term consequences such as skin cancers, photoageing and pigmentary disorders. More pronounced sun-sensitivity in lighter or darker skin types depending on the detrimental effects and involved wavelengths is reviewed.

Predictive Model for Response Rate to Narrowband Ultraviolet B Phototherapy in Vitiligo: A Retrospective Cohort Study of 579 Patients

Vitiligo is an acquired depigmenting disorder. To date, there is no predictive model for its response rate to narrowband ultraviolet B (NBUVB) phototherapy. The aim of this study was to investigate the different types of response of patients with non-segmental vitiligo undergoing NBUVB 3 times a week. Many patients who were previously considered non-responders were given the opportunity to continue the treatment. Long-term maintenance of treatment and follow-up of a cohort of 579 patients enabled different subtypes of response (very rapid, rapid, average, slow and "non-responders") to be described for the first time, and a predictive model of response to be constructed based on repigmentation rate in the first 48 sessions of NBUVB. Among those patients who did not respond during the first 48 sessions, a new subgroup of patients was found, termed "very-slow" responders, who achieved a low, but significant, level of repigmentation after 96 sessions of NBUVB.

Fractional Carbon Dioxide Laser as an "Add-on" Treatment for Vitiligo: A Meta-analysis with Systematic Review

Treatment of vitiligo is challenging and requires a multidisciplinary approach. Fractional carbon dioxide (CO2) laser as an add-on to conventional treatment has been reported to be effective, but there is no consensus on its use. A systematic review was performed by searching major databases for relevant publications to February 2017. Six studies with 85 participants were included. For those with refractory vitiligo, the addition of fractional CO2 laser to routine treatment modalities was superior to conventional treatment alone in terms of > 50% re-pigmentation (risk ratio (RR) 4.90, 95% confidence interval (95% CI), 1.15-20.93; p = 0.03), physician improvement score (mean difference (MD) 0.81, 95% CI 0.33-1.29; p < 0.001), < 25% re-pigmentation (RR 0.64, 95% CI, 0.49-0.85; p=0.002) and patient satisfaction (MD 1.61, 95% CI 0.73-2.49; p< 0.001). Side-effects were minor. These results provide evidence supporting that fractional CO2 laser is a valuable treatment modality for patients with vitiligo, especially for those with refractory vitiligo.

Impact of UVR Exposure Pattern on Squamous Cell Carcinoma-A Dose-Delivery and Dose-Response Study in Pigmented Hairless Mice

Cumulative lifetime ultraviolet radiation (UVR) is an important factor in the development of squamous cell carcinoma. This study examines the impact of UVR exposure pattern on tumor development. Hairless C3.Cg/TifBomTac immunocompetent pigmented mice (n = 351) were irradiated with 12 standard erythema doses (SED)/week, given as 2 SED ×6, 3 SED ×4, 4 SED ×3, or 6 SED ×2 (dose-delivery study) or 0, 0.6, 1.2, 2, 3 or 4 SED ×3/week (dose-response study). All mice were irradiated until development of 3 tumors of 4 mm each. Pigmentation was measured once monthly. In the dose-delivery study, the median time until tumor development was independent of dose fractions. In the dose-response study, higher UVR doses resulted in faster tumor appearance. When the weekly UVR dose was decreased from 12 to 6 SED, the cumulative UVR dose needed for tumor development was reduced by 40%. In conclusion, delivery schedules of a fixed weekly UVR dose did not affect tumor development. When using different weekly UVR doses, longer time to tumor development was observed using lower UVR doses. Lower weekly UVR doses however resulted in lower cumulative UVR doses to induce tumors in hairless pigmented mice.

Disparity in Cutaneous Pigmentary Response to LED vs Halogen Incandescent Visible Light: Results from a Single Center, Investigational Clinical Trial Determining a Minimal Pigmentary Visible Light Dose

<p>Background: While most of the attention regarding skin pigmentation has focused on the effects of ultraviolet radiation, the cutaneous effects of visible light (400 to 700nm) are rarely reported.

OBJECTIVE

The purpose of this study was to investigate the cutaneous pigmentary response to pure visible light irradiation, examine the difference in response to different sources of visible light irradiation, and determine a minimal pigmentary dose of visible light irradiation in melanocompetent subjects with Fitzpatrick skin type III - VI.

METHODS

The study was designed as a single arm, non-blinded, split-side dual intervention study in which subjects underwent visible light irradiation using LED and halogen incandescent light sources delivered at a fluence of 0.14 Watts/cm2 with incremental dose progression from 20 J/cm2 to 320 J/cm2. Pigmentation was assessed by clinical examination, cross-polarized digital photography, and analytic colorimetry.

RESULTS

Immediate, dose-responsive pigment darkening was seen with LED light exposure in 80% of subjects, beginning at 60 Joules. No pigmentary changes were seen with halogen incandescent light exposure at any dose in any subject.

CONCLUSION

This study is the first to report a distinct difference in cutaneous pigmentary response to different sources of visible light, and the first to demonstrate cutaneous pigment darkening from visible LED light exposure. Our findings raise the concern that our increasing daily artificial light surroundings may have clandestine effects on skin biology.</p> <p><em>J Drugs Dermatol. 2017;16(11):1105-1110.</em></p>.

Support for indoor tanning policies among young adult women who indoor tan

The purpose of this study to examine support for indoor tanning policies and correlates of policy support among young adult women who indoor tan. Non-Hispanic white women ages 18-30 who indoor tanned in the past year (n = 356, M 23.3 age, SD 3.1) recruited in the Washington, DC area from 2013 to 2016 completed measures of indoor tanning behaviors, attitudes, perceptions, beliefs, and policy support. Most women in the sample supported policies to prevent children under the age of 18 from indoor tanning (74.0 %) and stronger warnings about the risks of indoor tanning on tanning devices (77.6 %); only 10.1 % supported a total ban. In multivariable analyses, support for individual indoor tanning policies varied by demographics (e.g., age), frequent indoor tanning behavior, indoor tanning beliefs, and risk perceptions. Non-Hispanic white young adult women who indoor tan, the primary consumers of indoor tanning, and a high-risk population, largely support indoor tanning prevention policies implemented by many state governments and those currently under review for national enactment. Given low levels of support for a total indoor tanning ban, support for other potential policies (e.g., increasing the minimum age to 21) should be investigated to inform future steps to reduce indoor tanning and the associated health risks.