Modifying skin pigmentation - approaches through intrinsic biochemistry and exogenous agents

Microneedling Technique With Topical Vitamin C for Gingival Depigmentation Enhancing Gingival Aesthetics: A Longitudinal Study

Introduction As the focus on dental aesthetics intensifies, contemporary cosmetic dentistry seeks to establish an equilibrium between teeth and gums. Gingival hyperpigmentation, resulting from excessive melanin accumulation, can impact individuals regardless of age or gender and frequently gives rise to aesthetic apprehensions. Microneedling combined with topical vitamin C is a promising new method for improving gum appearance, particularly for reducing gingival hyperpigmentation caused by excess melanin. Microneedling is less expensive, more versatile, and promotes faster healing than traditional procedures like lasers or surgery. Materials and methods A study with 10 participants at the Karnavati School of Dentistry demonstrated significant pigmentation reduction. A paste was made with powdered ascorbic acid and a liquid ampule solution and applied with a Derma Pen (Dr. Pen Ultima A1, C Cube Advanced Technologies, India), which is a rechargeable pen-like instrument with 24-36 adjustable needles (0.25 mm to 2 mm) and five-speed settings. The gadget enables multi-directional treatment, and its disposable needle tips assure clean use with several patients. Results A significant decrease in melanin pigmentation was observed across all age groups, but anatomical challenges, such as irregular gingival contours, hampered results in some cases. Conclusion Microneedling is a safe and effective option for improving gingival aesthetics. As the technique evolves, it has the potential for broader applications.

Focus on the Contribution of Oxidative Stress in Skin Aging

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

Revealing the genetic basis of eyelid pigmentation in Hereford cattle

Ocular squamous cell carcinoma and infectious keratoconjunctivitis are common ocular pathologies in Hereford cattle with considerable economic impact. Both pathologies have been associated with low eyelid pigmentation, and thus, genetic selection for higher eyelid pigmentation could reduce their incidence. The objective of the present study was to reveal the genetic basis of eyelid pigmentation in Hereford cattle. The analysis included a single-step genome-wide association study (ssGWAS) and a subsequent gene-set analysis in order to identify individual genes, genetic mechanisms and biological pathways implicated in this trait. Data consisted of eyelid pigmentation records in 1,165 Hereford bulls and steers, visually assessed in five categories between 0% and 100%. Genotypic data for 774,660 single nucleotide polymorphism markers were available for 886 animals with pigmentation records. Pedigree information of three generations of ancestors of animals with phenotype was considered in this study, with a total of 4,929 animals. Our analyses revealed that eyelid pigmentation is a moderately heritable trait, with heritability estimates around 0.41. The ssGWAS identified at least eight regions, located on BTA1, BTA3, BTA5, BTA14, BTA16, BTA18, BTA19 and BTA24, associated with eyelid pigmentation. These regions harbor genes that are directly implicated in melanocyte biology and skin pigmentation, such as ADCY8, PLD1, KITLG, and PRKCA. The gene-set analysis revealed several functional terms closely related to melanogenesis, such as positive regulation of melanocyte differentiation and regulation of ERK1 and ERK2 cascade. Overall, our findings provide evidence that eyelid pigmentation is a heritable trait influenced by many loci. Indeed, the ssGWAS detected several candidate genes that are directly implicated in melanocyte biology, including melanogenesis. This study contributes to a better understanding of the genetic and biological basis of eyelid pigmentation and presents novel information that could aid to design breeding strategies for reducing the incidence of ocular pathologies in cattle. Additional research on the genetic link between eyelid pigmentation and ocular pathologies is needed.

Sebocytes contribute to melasma onset

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

Exogenous ochronosis associated with hydroquinone: a systematic review

Exogenous ochronosis is a potential side effect associated with hydroquinone, and treatment is often unsatisfactory. Our study objectives were to review data on hydroquinone-associated ochronosis to determine risk factors for patients experiencing this adverse event. On September 27, 2020 (MEDLINE/PubMed), and October 30, 2020 (Scopus and Web of Science), databases were searched for "ochronosis + hydroquinone" by both authors to reduce risk basis. PRISMA reporting guidelines were used to select 56 articles with a total of 126 patients with hydroquinone-associated ochronosis. Included articles described hydroquinone-associated ochronosis. Articles were excluded if they had irrelevant content, were non-English language text, and were non-case studies. Full text articles were assessed and recorded. Cross-tabulation analysis was performed on categorical data, and Fisher exact test was performed. Ochronosis was most often reported in middle-aged women (53.2%), of African descent (45.2%), Black races (55.5%), and Fitzpatrick skin types V-VI (52.4%). It was most frequently reported with unknown and hydroquinone concentrations greater than 4% (32.5 and 35.7% cases, respectively). Median duration of use was 5 years, with only four cases reported with courses 3 months or shorter and eight cases reported with use 1 year or less. All patients presented with facial blue-black or gray-blue macules in a reticulate, lace-like fashion. Histopathology consistently showed solar elastosis and brownish-yellow, 'banana-shaped' fibers between degenerated collagen fibers of the papillary dermis. Based on these findings, we conclude that hydroquinone in concentrations above 4% and in treatment courses longer than 3 months may be associated with new-onset ochronosis.

A Pilot Study of Negative Pressure Therapy with Autologous Skin Cell Suspensions in a Porcine Model

BACKGROUND

Negative pressure wound therapy (NPWT) is an option for securing meshed split thickness skin grafts (mSTSGs) after burn excision to optimize skin graft adherence. Recently, the use of autologous skin cell suspension (ASCS) has been approved for use in the treatment of burn injuries in conjunction with mSTSGs.To date, limited data exists regarding the impact of NPWT on healing outcomes when the cellular suspension is utilized. It was hypothesized that NPWT would not negatively impact wound healing of ASCS+mSTSG.

MATERIALS AND METHODS

A burn, excision, mSTSG, ASCS ± NPWT model was used. Two Duroc pigs were utilized in this experiment, each with 2 sets of paired burns. Four wounds received mSTSG+ASCS+NPWT through post-operative day 3, and 4 wounds received mSTSG+ACSC+ traditional ASCS dressings. Cellular viability was characterized prior to spraying. Percent re-epithelialization, graft-adherence, pigmentation, elasticity, and blood perfusion and blood vessel density were assessed at multiple time points through 2 weeks.

RESULTS

All wounds healed within 14 days with minimal scar pathology and no significant differences in percent re-epithelialization between NPWT, and non-NPWT wounds were observed. Additionally, no differences were detected for pigmentation, perfusion, or blood vessel density. NPWT treated wounds had less graft loss and improved elasticity, with elasticity being statistically different.

CONCLUSIONS

These data suggest the positive attributes of the cellular suspension delivered are retained following the application of negative pressure. Re-epithelialization, revascularization, and repigmentation are not adversely impacted. The use of NPWT may be considered as an option when using ASCS with mSTSGs for the treatment of full-thickness burns.

A Study of Botulinum Toxin A for Ultraviolet-Induced Hyperpigmentation: A Randomized Controlled Trial

BACKGROUND

Ultraviolet (UV) exposure contributes to skin hyperpigmentation. Recently, botulinum neurotoxin type A (BoNT-A) showed a promising protective effect on UVB-induced hyperpigmentation in both in vitro and animal models.

OBJECTIVE

The study aimed to investigate the preventive effect of BoNT-A against UVB-induced hyperpigmentation in human subjects.

MATERIALS AND METHODS

A prospective, double-blinded, randomized controlled trial was performed in 15 healthy participants. Four separate square areas on the abdomen were randomly injected intradermally with different dilutions of BoNT-A (1:2.5, 1:5, 1:7.5) and normal saline (control). Two weeks after injection, hyperpigmented spots were induced by UVB irradiation at the experimental sites. The lightness index and hyperpigmentation scores from blinded physician and participants were evaluated.

RESULTS

Fifteen participants completed the study. One week after UVB irradiation, all BoNT-A-treated sites had a significantly lower degree of hyperpigmentation than the control site in lightness index and hyperpigmentation scores from blinded physician and participants (p < .05). However, no statistically significant difference was observed between different concentrations of BoNT-A. No side effects were observed throughout the study period.

CONCLUSION

Intradermal BoNT-A injection provided a protective effect from UVB-induced hyperpigmentation. It may be used for other hyperpigmentation disorders that are aggravated by UVB.

Clinical evaluation of the efficacy of a facial serum containing dioic acid, glycolic acid, salicylic acid, LHA, citric acid, and HEPES in treating post-inflammatory hyperchromia and controlling oily skin in patients with acne vulgaris

BACKGROUND

Acne is a chronic disease that affects the pilosebaceous follicle and is characterized by the presence of non-inflammatory and/or inflammatory lesions, affecting both adolescents and adults. Inflammatory acne lesions are capable to increase their melanin production and promote a post-inflammatory hyperchromia.

AIMS

To assess the efficacy of a serum containing dioic acid, glycolic acid, salicylic acid, LHA, citric acid, and HEPES in treating post-inflammatory hyperpigmentation and controlling skin oiliness in Brazilian patients with acne vulgaris.

PATIENTS/METHODS

A single-center, prospective, open-label clinical study included 42 subjects, from both genders, presenting acne (grade I or II), oily skin and a clinical diagnosis of acne post-inflammatory hyperpigmentation. The study was conducted for 56 days, with clinical (skin quality and the number of post-inflammatory hyperchromic lesions) and instrumental (Sebumetry) evaluations after 7, 28, and 56 days of treatment. Standardized pictures were obtained using a VISIA-6^® device.

RESULTS

A significant decrease in the grade of post-inflammatory hyperchromic lesions was observed after 28 and 56 days, while the number of lesions decreases by 29.4% after 56 days (p < 0.001). Sebumetry values showed a significant decrease of 30.7% in the oiliness after 7 days of treatment, and then stable during the study conduction period of 56 days (p < 0.001 for all measurements).

CONCLUSIONS

The daily treatment using the investigational product showed an interesting decrease both in the grade and the number of post-inflammatory hyperchromia acne lesions after 56 days, and in the oiliness after 7 days, being stable for all study period.

Low-Temperature Argon Plasma Regulates Skin Moisturizing and Melanogenesis-Regulating Markers through Yes-Associated Protein

Extensive water loss and melanin hyperproduction can cause various skin disorders. Low-temperature argon plasma (LTAP) has shown the possibility of being used for the treatment of various skin diseases, such as atopic dermatitis and skin cancer. However, the role of LTAP in regulating skin moisturizing and melanogenesis has not been investigated. In this study, we aimed to determine the effect of LTAP on yes-associated protein (YAP), a major transcriptional coactivator in the Hippo signaling pathway that is involved in skin moisturizing and melanogenesis-regulating markers. In normal human epidermal keratinocytes (NHEKs), the human epidermal keratinocyte line HaCaT, and human dermal fibroblasts (HDFs), we found that LTAP exhibited increased expression levels of YAP protein. In addition, the expression levels of filaggrin (FLG), which is involved in natural moisturizing factors (NMFs), and hyaluronic acid synthase (HAS), transglutaminase (TGM), and involucrin (IVL), which regulate skin barrier and moisturizing, were also increased after exposure to LTAP. Furthermore, collagen type I alpha 1 and type III alpha 1 (COL1A1, COL3A1) were increased after LTAP exposure, but the expression level of matrix metalloproteinase-3 (MMP-3) was reduced. Moreover, LTAP was found to suppress alpha-melanocyte stimulating hormone (α-MSH)-induced melanogenesis in murine melanoma B16F10 cells and normal human melanocytes (NHEMs). LTAP regulates melanogenesis of the melanocytes through decreased YAP pathway activation in a melanocortin 1 receptor (MC1R)-dependent manner. Taken together, our data show that LTAP regulates skin moisturizing and melanogenesis through modulation of the YAP pathway, and the effect of LTAP on the expression level of YAP varies from cell to cell. Thus, LTAP might be developed as a treatment method to improve the skin barrier, moisture content, and wrinkle formation, and to reduce melanin generation.

Mitochondrial DNA-depleter mouse as a model to study human pigmentary skin disorders

Pigmentation abnormalities are reported in the spectrum of phenotypes associated with aging and in patients with mitochondrial DNA depletion syndrome (MDS). Yet, a relevant animal model that mimics these effects and would allow us to evaluate the detrimental aspects of mtDNA depletion on melanocyte function has not been described. Here, we characterize the pigmentary changes observed in the ears of a mtDNA-depleter mouse, which phenotypically includes accentuation of the peri-adnexal pseudonetwork, patchy hyper- and hypopigmentation, and reticular pigmentation. Histologically, these mice show increased epidermal pigmentation with patchy distribution, along with increased and highly dendritic melanocytes. These mtDNA-depleter mice mimic aspects of the cutaneous, pigmentary changes observed in humans with age-related senile lentigines as well as MDS. We suggest that this mouse model can serve as a novel resource for future interrogations of how mitochondrial dysfunction contributes to pigmentary skin disorders. The mtDNA-depleter mouse model also serves as a useful tool to identify novel agents capable of treating pigmentary changes associated with age-related mitochondrial dysfunction in humans.

Laser-Assisted Depigmentation-An Introspection of the Science, Techniques, and Perceptions

BACKGROUND

Gingival hyperpigmentation is a major concern for a significant number of patients, as a relevant aesthetic or cosmetic need. Oral melanin pigmentation is considered to be multifactorial and could be related to physiological or even pathological reasons and can be the consequence of a variety of local or systemic factors. This pigmentation varies individually across races or age groups and is without any gender predilection. Evidence gleaned from literature is presented from case-control studies and from the authors' own research work in prospective, split-mouth, double-blinded, clinical trials comparing treatment modalities in effecting depigmentation.

METHODS

A systematic review of published articles, using suitable assay criteria, was carried out to formulate a consensus on laser-assisted modalities. A total of 295 published sources were subject to critical analysis and resulted in six papers that were subject to data scrutiny. Additionally, evidence is presented on clinical protocols and treatment outcomes.

RESULTS

Analysis of randomized clinical studies identified the use of two laser wavelength groups-near infrared diode and erbium group of mid-infrared lasers. Several areas of analysis were examined, and inconsistent degrees of significance were obtained to establish which laser group was optimal and if they were any better than scalpel depigmentation.

CONCLUSION

A definitive conclusion is wanting as studies with scientific and standardized protocols of evaluation are yet to provide a take on comparative assessments between different techniques of depigmentation.

Isobutylamido thiazolyl resorcinol for prevention of UVB-induced hyperpigmentation

BACKGROUND

Isobutylamido thiazolyl resorcinol (ITR, Thiamidol^® ) has been proposed as a potent tyrosinase inhibitor. A formulation containing ITR has recently shown promising efficacy for the treatment of some hyperpigmentary conditions.

OBJECTIVES

This study aimed to evaluate the efficacy and safety of ITR in the prevention of ultraviolet (UV)-induced hyperpigmentation in human skin.

MATERIALS AND METHODS

We performed a randomized, single-blinded, pilot study in 30 healthy participants. One arm was randomly assigned to receive an ITR-containing product for three weeks. Three hyperpigmented spots were induced by UVB irradiation on both arms after 3 weeks of ITR application. Outcome evaluations included measuring mean lightness index (*L) obtained by colorimeter, hyperpigmentation scores by visual analog scale (VAS), and adverse effects.

RESULTS

Both experimental sides showed no significant difference in terms of skin lightening after ITR application. However, the ITR-treated sides showed a statistically significant lower mean lightness index compared to control after an induction with UVB. In addition, the ITR-treated sides had an earlier improvement and resumed the normal skin color after 3 weeks post-UVB induction. A clinical evaluation by a blinded nontreating physician and subjects was more favorable on the ITR-treated side than the control side (P < .05). No significant side effect was noted.

CONCLUSIONS

ITR is an effective agent in the prevention of pigmentary change from UVB irradiation and may serve as a promising agent for preventing other hyperpigmentary conditions.

Tyrosinase and Melanogenesis Inhibition by Indigenous African Plants: A Review

The indiscriminate use of non-regulated skin lighteners among African populations has raised health concerns due to the negative effects associated with skin lightener toxicity. For this reason, there is a growing interest in the cosmetic development of plants and their metabolites as alternatives to available chemical-derived skin lightening formulations. Approximately 90% of Africa’s population depends on traditional medicine, and the continent’s biodiversity holds plant material with various biological activities, thus attracting considerable research interest. This study aimed to review existing evidence and document indigenous African plant species capable of inhibiting the enzyme tyrosinase and melanogenesis for potential incorporation into skin lightening products. Literature search on melanin biosynthesis, skin lightening, and tyrosinase inhibitors resulted in the identification of 35 plant species were distributed among 31 genera and 21 families across 15 African countries and 9 South African provinces. All plants identified in this study showed competent tyrosinase and melanogenesis inhibitory capabilities. These results indicate that African plants have the potential to serve as alternatives to current chemically-derived skin lighteners.

Dose response of black American mink to Aleutian mink disease virus

INTRODUCTION

Aleutian mink disease virus (AMDV) causes a serious health problem for mink globally. The disease has no cure nor an effective vaccine and selection for tolerance using antibody titer is adopted by many mink farmers. The objective of this study was to investigate the effects of various doses of a local AMDV isolate on the response of black American mink to infection with AMDV.

METHODS

Eight black American mink were each inoculated intranasally with 0.5 mL of eight serial 10-fold dilutions (100 to 10-7 ) of a 10% spleen homogenate containing a local AMDV isolate. Blood samples were collected on days 0, 20, 35, 56, 84, 140, and 196 postinoculation (dpi). Anti-AMDV antibodies and viral DNA were tested by counter-immunoelectrophoresis (CIEP) and PCR, respectively. Animals that were PCR or CIEP positive at 196 dpi (n = 41) were killed at 218 dpi, and samples of blood and seven organs were tested by CIEP and PCR.

RESULTS

Antibody production persisted in all seroconverted mink until the termination of the experiment, whereas 71.1% of the mink showed short-lived viremia. Significant associations were observed between inoculum dose and the incidence of viremia until 84 dpi which disappeared thereafter, whereas associations between inoculum dose and the incidence of seropositive mink were significant on all sampling occasions. Antibody titer at 218 dpi significantly decreased with decreasing inoculum dose. AMDV DNA was detected in the bone marrow, lymph nodes, and spleen samples of almost all mink inoculated at every dose but was not detected in other organs of some mink.

CONCLUSIONS

CIEP is more accurate than PCR for detecting AMDV infection in mink. Using antibody titer in naturally infected mink may not be accurate for the identification of tolerant mink.

Assessment of the Pharmacological Properties and Phytochemical Profile of Bruguiera gymnorhiza (L.) Lam Using in Vitro Studies, in Silico Docking, and Multivariate Analysis

Bruguiera gymnorhiza (L.) Lam. is claimed to effectively manage a number of ailments including diabetes and associated complications. Nonetheless, no attempt has been made to delineate its pharmacological propensities and phytochemical profile. This study was designed to appraise the antioxidant and enzymatic inhibitory properties relevant to the management of diabetes mellitus, obesity, and neurodegenerative and skin disorders. A combination of colorimetric assays and ultra-high-performance liquid chromatography/electrospray ionization tandem mass spectrometry (UHPLC-ESI-MS/MS) were applied for the phytochemical screening of leaf, root, twig, and fruit extracts (methanol and ethyl acetate). In vitro antioxidant evaluations were via radical scavenging abilities (DPPH, ABTS), reducing potential (FRAP, CUPRAC), chelating power, and total antioxidant capacity (phosphomolybdenum). Seven key metabolic enzymes (α-amylase, α-glucosidase, tyrosinase, elastase, lipase, AChE, and BChE) were targeted to determine the inhibitory effects. Multivariate and in silico docking analysis were performed on collected data. Methanolic fruit extract yielded the highest total phenolic, tannin, and triterpenoid contents (174.18 ± 4.27 mg GAE/g, 176.24 ± 3.10 mg CE/g, 63.11 ± 3.27 mg OAE/g, respectively); significantly depressed tyrosinase, elastase, and α-amylase activities (155.35 ± 0.29 mg KAE/g, 4.56 ± 0.10 mg CAE/g, 1.00 ± 0.05 mmol ACAE/g, accordingly); and harboured the most potent antioxidant capacities with DPPH, CUPRAC, FRAP (492.62 ± 5.31, 961.46 ± 11.18, 552.49 ± 8.71 mg TE/g, respectively), and phosphomolybdenum (4.17 ± 0.31 mmol TE/g) assays. Multivariate analysis suggested that the type of solvents used influenced the biological activities more compared to plant parts. Docking analysis showed that azelaic acid binds with tyrosinase by Van der Waals and conventional hydrogen bonds. We anticipate that the present study may establish baseline data on this halophyte that could open new avenues for the development of biomedicine.

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

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

The role and mechanism of Asian medicinal plants in treating skin pigmentary disorders

ETHNOPHARMACOLOGICAL RELEVANCE

Chloasma, senile plaques, vitiligo and other pigmentary disorders seriously affect patients' appearance and life quality. Medicinal plant is the product of long-term medical practice worldwide, with the advantages of outstanding curative properties and less side effects. Recently, research were made to explore the value of medicinal plants in the treatment of pigmentary disorders, and remarkable results were achieved.

AIM OF THE REVIEW

This review outlines the current understanding of the role and potential mechanisms of medicinal plants (including active ingredients, extracts and prescriptions) in pigmentary disorders, especially Chinese medicinal plants, provides the preclinical evidence for the clinical benefits. This study hopes to provide comprehensive information and reliable basis for exploring new therapeutic strategies of plant drugs in the treatment of skin pigmented diseases.

METHODS

The literature information was obtained from the scientific databases (up to Oct, 2017), mainly from the PubMed, Web of Science and CNKI databases, and was to identify the experimental studies on the regulating melanogenesis role of the active agents from herbal medicine and the involved mechanisms. The search keywords for such work included: "pigmentary" or "pigmentation", "melanogenesis", and "traditional Chinese medicine" or "Chinese herbal medicine", "herb", "medicinal plant".

RESULTS

We summarized the function of medicinal plants involved in melanogenesis, especially Chinese medicine. It was reported that the active ingredients, extracts, or prescriptions of medicinal plants can regulate the expression of genes related to melanogenesis by affecting the signaling pathways such as MAPK and PKA, thereby regulating pigment synthesis. Some of them can promote melanogenesis (such as isoliquiritigenin, geniposide; Cornus officinalis Siebold & Zucc., Eclipta prostrata (L.) L.; the Bairesi complex prescription, etc.). While others have the opposite effect (such as biochanin A, Gomisin N; Panax ginseng C.A. Meyer, Nardostachys chinensis Bat.; Sanbaitang, etc.).

CONCLUSION

Asian medicinal plants, especially their active ingredients, have multilevel effects on melanogenesis by regulating melanogenesis-related genes or signaling pathways. They are of great clinical value for the treatment of skin pigmentary disorders. However, the experimental effect, safety, and functional mechanism of the medicinal plants require further determination before studying their clinical efficacy.

Patient Preferences and Comparative Outcomes Regarding Cryosurgery versus Electrodesiccation in the Removal of Truncal Seborrheic Keratoses

Background: Seborrheic keratoses (SKs) are one of the most common benign epithelial tumors seen by dermatologists. Many people elect to have these lesions removed, most commonly by way of cryosurgery or electrodesiccation. Objective: We sought to evaluate the comparative efficacy and patient preferences regarding cryosurgery and electrodesiccation for the treatment of truncal SK lesions. Methods: In this randomized, blinded clinical trial, 33 eligible subjects with two similar truncal SKs were assigned to receive treatment with cryosurgery and electrodesiccation applied to separate lesions. Patients rated their pain and preference at the time of treatment and follow up at two and eight weeks. Physicians rated the color, texture, and efficacy of lesion removal at eight weeks. Results: Patients did not have a treatment preference (p=0.10) and there was no significant difference in pain when comparing cryosurgery to electrodesiccation (p=0.43). Both treatment modalities were similar in terms of efficacy (p=0.50). Skin texture was rated similarly (p=0.64); however, lesions treated with cryosurgery were nominally less likely to have posttreatment hyperpigmentation compared to lesions treated with electrodesiccation (odds ratio: 0.35, 95% confidence interval: 0.12-1.002; p=0.0504). Conclusion: Cryosurgery and electrodesiccation are both effective treatment modalities for truncal SKs. While cosmetic outcomes were similar, cryosurgery resulted in less postinflammatory hyperpigmentation.

Evaluating the Efficacy, Safety, and Tolerability of the Combination of Tazarotene, Azelaic Acid, Tacrolimus, and Zinc Oxide for the Treatment of Melasma: A Pilot Study

Background: Melasma is a common hyperpigmentation disorder of the skin. Combination therapy of topical retinoids, corticosteroids, and hydroquinone has been effective in treating melasma, but long-term use is limited by corticosteroid atrophy and exogenous ochronosis. The aim of this pilot study (NCT02730819) was to determine the efficacy, safety, and tolerability of a novel composition (2013-MCN-333) comprising tazarotene 0.075%, azelaic acid 20%, tacrolimus 0.1%, and (microfine) zinc oxide 10% for the treatment of melasma. Methods: Sixteen patients with moderate-to-severe melasma were treated daily with sunscreen and 2013-MCN-333 for 20 weeks. Primary outcome measure was change in Melasma Area and Severity Index (MASI) score. Results: Twenty-five percent of patients met the primary endpoint of a MASI score of less than eight points at Week 20. MASI score also decreased significantly from baseline (median: 18.9 points) through Week 4 (median: 17.3 points; p=0.006), Week 12 (median: 16.0 points; p=0.001), and Week 20 (median: 13.3 points; p=0.001). Treatment-related adverse events were mild, most of which decreased or resolved over the course of the study. Limitations: The small sample size and nonblinded nature of treatment intervention are potential limitations. Conclusion: Our results suggest daily 2013-MCN-333 could potentially be an effective, safe, and tolerable treatment for moderate-to-severe melasma.

Characterization of sulfuretin as a depigmenting agent

Sulfuretin is a major flavonoid found in Rhus verniciflua and carries anti-oxidative and anti-inflammatory properties, but its potential use in the control of skin pigmentation is unknown. The purpose of the present study was to elucidate sulfuretin as a new active compound inhibiting melanogenesis and the underlying mechanism. The effects of sulfuretin on melanin production, tyrosinase activity, cAMP level, and MITF expression were examined in murine melanoma B16 cells challenged with forskolin or α-MSH. The inhibitory effect of sulfuretin on melanogenesis was further validated on neonatal human melanocytes. When tested in melanoma B16 cells treated with forskolin or α-MSH, sulfuretin inhibited the cellular melanogenesis. Sulfuretin also showed direct inhibitory effect on tyrosinase activity in vitro. In human primary melanocytes, the inhibitory effect of sulfuretin on melanin synthesis was also confirmed. Our current results support the depigmenting effect of sulfuretin and suggest a clinical strategy for using sulfuretin in the topical treatment of hyperpigmentation disorders.

Exploring pathways for sustained melanogenesis in facial melasma: an immunofluorescence study

BACKGROUND

The physiopathology of epidermal hypermelanization in melasma is not completely understood. Several cytokines and growth factors are increased in skin with melasma, nevertheless, nor the pathways involved in the increased αMSH expression have been adequately evaluated, nor a model for sustained focal melanogenesis is available.

OBJECTIVE

To explore stimulatory pathways for epidermal pigmentation in facial melasma related to αMSH: those linked to ultraviolet radiation, oxidative stress, inflammation, neural crest pigmentation cell differentiation and antagonism of αMSH.

METHODS

Paired skin biopsies (3 mm) from 26 women with facial melasma and from normal adjacent skin (<2 cm far) were processed for immunofluorescence with markers for p53, p38, αMSH, MC1R, Melan-A, IL-1α, COX2, Wnt1, WIF-1 and ASIP.

RESULTS

The fluorescence intensity in the skin from melasma was higher for MC1R, αMSH at epidermis as at melanocytes (P < 0.05). There were no differences between the sites in epidermal protein expression of COX2, IL-1α, p53, WIF-1 and ASIP (P > 0.1). P53 was expressed only in epidermis, without difference between sites (P = 0.92). WNT1 was remarkable in the epidermis of melasma (P < 0.01), but not in dermis. Positive p38 cells were prominent in the upper dermis of melasma (P < 0.01), despite no marking in epidermis.

CONCLUSION

Melanogenesis in melasma involves epithelial secretion of αMSH and activation of the Wnt pathway; nevertheless, it seems to be independent of the stimulation by ultraviolet radiation/p53, IL-1α, COX2/PgE₂ , WIF-1 and ASIP. Damaged cells at upper dermis suggest the role of senescence/autophagy in sustained pigmentation in melasma.

Intrinsic and extrinsic regulation of human skin melanogenesis and pigmentation

In human skin, melanogenesis is a tightly regulated process. Indeed, several extracellular signals are transduced via dedicated signalling pathways and mostly converge to MITF, a transcription factor integrating upstream signalling and regulating downstream genes involved in the various inherent mechanisms modulating melanogenesis. The synthesis of melanin pigments occurs in melanocytes inside melanosomes where melanogenic enzymes (tyrosinase and related proteins) are addressed with the help of specific protein complexes. The melanosomes loaded with melanin are then transferred to keratinocytes. A more elaborate level of melanogenesis regulation comes into play via the action of non-coding RNAs (microRNAs, lncRNAs). Besides this canonical regulation, melanogenesis can also be modulated by other non-specific intrinsic pathways (hormonal environment, inflammation) and by extrinsic factors (solar irradiation such as ultraviolet irradiation, environmental pollution). We developed a bioinformatic interaction network gathering the multiple aspects of melanogenesis and skin pigmentation as a resource to better understand and study skin pigmentation biology.

A Novel Stilbene-Like Compound That Reduces Melanin through Inhibiting Melanocyte Differentiation and Proliferation without Inhibiting Tyrosinase

Cosmetic practices that use skin-lightening agents to obtain desired skin tones or treat pigment abnormalities have been popular worldwide. However, the molecular and cellular mechanisms of these agents are still largely unknown. Here we identified a family of compounds, with the lead compound named A11, that exhibited strong pigment reduction in developing zebrafish embryos. The pigment inhibition lasted for several days and is effective both before and after melanogenesis. By comparison with several known skin-lightening compounds, A11 appeared to be more potent and caused slower pigment recovery after withdrawal. A11, however, did not inhibit tyrosinase or cause apoptosis in melanocytes. We further found that A11 suppressed proliferation in melanocytes and reduced the number of differentiated melanocytes by activating MAPK (mitogen-activated protein kinase) and Akt. Finally, A11 also caused melanin reduction in mammalian melanocytes. Together, A11 might be a potent skin-lightening agent with novel mechanisms.

Myosin VI and branched actin filaments mediate membrane constriction and fission of melanosomal tubule carriers

Vesicular and tubular transport intermediates regulate organellar cargo dynamics. Transport carrier release involves local and profound membrane remodeling before fission. Pinching the neck of a budding tubule or vesicle requires mechanical forces, likely exerted by the action of molecular motors on the cytoskeleton. Here, we show that myosin VI, together with branched actin filaments, constricts the membrane of tubular carriers that are then released from melanosomes, the pigment containing lysosome-related organelles of melanocytes. By combining superresolution fluorescence microscopy, correlative light and electron microscopy, and biochemical analyses, we find that myosin VI motor activity mediates severing by constricting the neck of the tubule at specific melanosomal subdomains. Pinching of the tubules involves the cooperation of the myosin adaptor optineurin and the activity of actin nucleation machineries, including the WASH and Arp2/3 complexes. The fission and release of these tubules allows for the export of components from melanosomes, such as the SNARE VAMP7, and promotes melanosome maturation and transfer to keratinocytes. Our data reveal a new myosin VI- and actin-dependent membrane fission mechanism required for organelle function.

Restoration of skin pigmentation after deep partial or full-thickness burn injury

Significant skin pigmentation changes occur when patients suffer deep burn injuries. These pigmentation disorders may cause not only cosmetic and psychological issues, but more importantly it increases the risk of skin cancer or photoaging. Severe burns significantly effect on the process of repigmentation as the pigmentation is tightly regulated by cell proliferation and differentiation of melanocytes and melanocyte stem cells which are housing in the epidermis and hair follicles of the skin. In the present review, we discuss the possible mechanisms to replenish the melanocytes from the healthy epidermis and hair follicles surrounding burn wounds. The molecular mechanisms of skin repigmentation following healing of burn injuries includes the differentiation of melanoblasts into melanocytes, the distribution and responses of melanocytes and melanocyte stem cells after burn injury, and the regulation of melanin production. We also reviewed advanced therapeutic strategies to treat pigmentation disorders, such as convectional surgery, laser, UV treatment and emerging concepts in skin tissue-engineering.

Non-invasive high-intensity focused ultrasound for UV-induced hyperpigmentation in Fitzpatrick skin types III and IV: a prospective, randomized, controlled, evaluator-blinded trial

Skin hyperpigmentation is a frequently encountered problem, particularly in darker skin types. Unfortunately, standard treatments for this condition have shown disappointing results. High-intensity focused ultrasound (HIFU) is commonly indicated for skin laxity, but recently was used to treat UV-induced hyperpigmentation in animal models. This study is aimed to evaluate the efficacy and safety of high-intensity focused ultrasound for UVB-induced hyperpigmentation in human subjects. A randomized, evaluator-blinded pilot study was conducted on 20 subjects. Each subject was induced three hyperpigmentary spots by local broadband UVB. After 2 weeks, each spot was randomly allocated to control, low-energy, and high-energy HIFU. Subjects were instructed to follow up weekly for a duration of 1 month. Lightness index measurements, mean improvement scores, subjects' satisfaction, pain scores, and side effects were evaluated. All 20 subjects completed the study. Fourteen subjects had Fitzpatrick (FPT) skin type III and six subjects had FPT skin type IV. Twelve subjects showed greater improvement at control sites while eight subjects showed greater improvement at HIFU-treated sites. In FPT skin type III, HIFU appeared to be inferior to control in both lightness index and mean improvement scores, but in FPT skin type IV, HIFU had greater lightness index improvement and higher improvement scores than control. Side effects were more frequent in high-energy-treated areas. Focused ultrasound may be offered in some patients with hyperpigmentary conditions. More research is needed to determine proper energy settings for optimal outcome.

A novel stilbene-like compound that inhibits melanoma growth by regulating melanocyte differentiation and proliferation

Melanoma is the most aggressive form of skin cancer. Current challenges to melanoma therapy include the adverse effects from immunobiologics, resistance to drugs targeting the MAPK pathway, intricate interaction of many signal pathways, and cancer heterogeneity. Thus combinational therapy with drugs targeting multiple signaling pathways becomes a new promising therapy. Here, we report a family of stilbene-like compounds called A11 that can inhibit melanoma growth in both melanoma-forming zebrafish embryos and mouse melanoma cells. The growth inhibition by A11 is a result of mitosis reduction but not apoptosis enhancement. Meanwhile, A11 activates both MAPK and Akt signaling pathways. Many A11-treated mouse melanoma cells exhibit morphological changes and resemble normal melanocytes. Furthermore, we found that A11 causes down-regulation of melanocyte differentiation genes, including Pax3 and MITF. Together, our results suggest that A11 could be a new melanoma therapeutic agent by inhibiting melanocyte differentiation and proliferation.

A holistic review on the autoimmune disease vitiligo with emphasis on the causal factors

Vitiligo is an idiopathic systemic autoimmune disease affecting skin, hair and oral mucosa. This genetic yet acquired disease characterized by melanin loss is a cause of morbidity across all races. Though thyroid disturbance has been recognized as a key trigger of this pathology, an array of other factors plays critical role in its manifestation. Multiple hormones (corticotropin-releasing hormone, adrenocorticotropic hormone, α-melanocyte-stimulating hormone, melatonin, calcitriol, testosterone, estrogen), genes (Human leukocyte antigen (HLA), Cytotoxic T lymphocyte-associated antigen 4 (CTLA-4), Forkhead box D3 (FOXD3), Cluster of differentiation 117 (CD117), Estrogen receptor (ESR) 1, Cyclooxygenase-2 (COX2), Vitiligo-associated protein 1 (VIT1)), and lifestyle choices (stress, diet, cosmetic products, and medications) have been suspected as drivers of this disorder. The pathological mechanisms have been understood in recent times, with the aid of genomic studies; however a universally-effective therapy is yet to be achieved. This review discusses these under-investigated facets of vitiligo onset and progression; hence, it is expected to enrich vitiligo research.

Efficacy of Conventional Laser Irradiation Versus a New Method for Gingival Depigmentation (Sieve Method): A Clinical Trial

Introduction: Diode laser irradiation has recently shown promising results for treatment of gingival pigmentation. This study sought to compare the efficacy of 2 diode laser irradiation protocols for treatment of gingival pigmentations, namely the conventional method and the sieve method. Methods: In this split-mouth clinical trial, 15 patients with gingival pigmentation were selected and their pigmentation intensity was determined using Dummett's oral pigmentation index (DOPI) in different dental regions. Diode laser (980 nm wavelength and 2 W power) was irradiated through a stipple pattern (sieve method) and conventionally in the other side of the mouth. Level of pain and satisfaction with the outcome (both patient and periodontist) were measured using a 0-10 visual analog scale (VAS) for both methods. Patients were followed up at 2 weeks, one month and 3 months. Pigmentation levels were compared using repeated measures of analysis of variance (ANOVA). The difference in level of pain and satisfaction between the 2 groups was analyzed by sample t test and general estimate equation model. Results: No significant differences were found regarding the reduction of pigmentation scores and pain and scores between the 2 groups. The difference in satisfaction with the results at the three time points was significant in both conventional and sieve methods in patients (P = 0.001) and periodontists (P = 0.015). Conclusion: Diode laser irradiation in both methods successfully eliminated gingival pigmentations. The sieve method was comparable to conventional technique, offering no additional advantage.

Skin Bleaching and Dermatologic Health of African and Afro-Caribbean Populations in the US: New Directions for Methodologically Rigorous, Multidisciplinary, and Culturally Sensitive Research

Skin-bleaching practices, such as using skin creams and soaps to achieve a lighter skin tone, are common throughout the world and are triggered by cosmetic reasons that oftentimes have deep historical, economic, sociocultural, and psychosocial roots. Exposure to chemicals in the bleaching products, notably, mercury (Hg), hydroquinone, and steroids, has been associated with a variety of adverse health effects, such as Hg poisoning and exogenous ochronosis. In New York City (NYC), skin care product use has been identified as an important route of Hg exposure, especially among Caribbean-born blacks and Dominicans. However, surprisingly sparse information is available on the epidemiology of the health impacts of skin-bleaching practices among these populations. We highlight the dearth of large-scale, comprehensive, community-based, clinical, and translational research in this area, especially the limited skin-bleaching-related research among non-White populations in the US. We offer five new research directions, including investigating the known and under-studied health consequences among populations for which the skin bleach practice is newly emerging at an alarming rate using innovative laboratory and statistical methods. We call for conducting methodologically rigorous, multidisciplinary, and culturally sensitive research in order to provide insights into the root and the epidemiological status of the practice and provide evidence of exposure-outcome associations, with an ultimate goal of developing potential intervention strategies to reduce the health burdens of skin-bleaching practice.

Vasoactive intestinal peptide stimulates melanogenesis in B16F10 mouse melanoma cells via CREB/MITF/tyrosinase signaling

Vasoactive intestinal peptide (VIP), one of the major skin neuropeptides, has been suggested to have active roles in the pathogenesis of inflammatory skin disorders such as atopic dermatitis and psoriasis, which can commonly cause post-inflammatory hyperpigmentation. However, the effect of VIP on melanogenesis remains unknown. In this study, we showed that the melanin contents, tyrosinase activity, and gene expression of tyrosinase and microphthalmia-associated transcription factor (MITF) were significantly increased by treatment with VIP in B16F10 mouse melanoma cells and the stimulatory melanogenic effect was further examined in human epidermal melanocytes (HEMns). In addition, phosphorylated levels of CRE-binding protein (CREB) and protein kinase A (PKA) were markedly increased after VIP treatment, but not p38 mitogen-activated protein kinase (p38 MAPK), extracellular signal-regulated kinase (ERK), or Akt, indicating the possible PKA-CREB signaling pathway involved in VIP-induced melanogenesis. This result was further verified by the fact that VIP induced increased melanin synthesis, and protein levels of phosphorylated CREB, MITF, tyrosinase were significantly attenuated by H89 (a specific PKA inhibitor). These data suggest that VIP-induced upregulation of tyrosinase through the CREB-MITF signaling pathway plays an important role in finding new treatment strategy for skin inflammatory diseases related pigmentation disorders.

1-Phenyl-3-(2-thiazolyl)-2-thiourea inhibits melanogenesis via a dual-action mechanism

1-Phenyl-3-(2-thiazolyl)-2-thiourea (PTTU) is a well-characterized dopamine β-hydroxylase inhibitor that prevents 6-hydroxydopamine-induced degenerative neuronal disease. However, the effect of PTTU on melanogenesis has not been reported. In this study, we examined the effect of PTTU on melanogenesis and studied its mechanism of action. We found that PTTU decreased melanin biosynthesis in a dose-dependent manner in normal human epidermal melanocytes (NHEMs). PTTU also inhibited tyrosinase catalytic activity in NHEMs. Moreover, PTTU treatment led to reduced protein levels of tyrosinase in NHEMs, while the protein levels of tyrosinase-related protein-1, tyrosinase-related protein-2, and microphthalmia-associated transcription factor were not affected. However, PTTU treatment did not affect the mRNA expression of tyrosinase. We found that PTTU-accelerated tyrosinase degradation via the ubiquitin-dependent proteasome pathway. In summary, we found that PTTU decreased melanin biosynthesis by decreasing the enzymatic activity and stability of tyrosinase. Our results indicate that PTTU could be used as a depigmentation agent for hyperpigmentation disorder.

Pigment Production Analysis in Human Melanoma Cells

The human epidermal melanocyte is a highly specialized pigmented cell that serves to protect the epidermis from ultraviolet (UV) damage through the production of melanin, or melanogenesis. Misregulation in melanogenesis leading to either hyper- or hypo-pigmentation is found in human diseases such as malasma and vitiligo. Current therapies for these diseases are largely unsuccessful and the need for new therapies is necessary. In order to identify genes and or compounds that can alter melanogenesis, methods are required that can detect changes in pigment production as well as expression of key melanogenesis transcription factors and enzymes. Here we describe methods to detect changes in melanogenesis in a human melanoma cell line, MNT-1, by (1) analyzing pigment production by measuring the absorbance of melanin present by spectrophotometry, (2) analyzing transcript expression of potent regulators of melanogenesis by qunatitative reverse-transcription (RT)PCR and (3) analyzing protein expression of potent regulators of melanogenesis by Western blot (WB).

Targeting ALDH1A1 to treat pigmentary disorders

Clinical disorders related to skin pigmentation include hypo- or hyperpigmentation. Because they are difficult to treat, new approaches to develop safe pigment modulatory agents are needed. In the March issue of the journal, Paterson et al. (Exp Dermatol, 22, 2013) determined which aldehyde dehydrogenase 1A1 (ALDH1A1) substrates and products regulate melanogenesis. The authors demonstrated that ALDH1A1 substrate 9-cis retinal and its corresponding product 9-cis retinoic acid potently induced the accumulation of MITF mRNA, tyrosinase mRNA and melanin. Despite depletion of ALDH1A1, there was observed decreased ability of 9-cis retinal but not 9-cis retinoic acid to stimulate melanogenesis, indicating that ALDH1A1 regulates melanogenesis by catalysing the conversion of 9-cis retinal to 9-cis retinoic acid. Additionally, potent ALDH1A1 inhibitor such as cyanamide or Angeli's salt significantly suppressed pigmentation in human skin cells. These findings provide new candidate agents for the treatment of hypo- or hyperpigmentation disorders, using novel pigmentation-modulatory agents that target ALDH1A1.