Medical and Maintenance Treatments for Vitiligo

Melanogrit potentiates melanogenesis by escalating cellular tyrosinase activity and MITF levels via pERK inhibition

Vitiligo is characterized by the development of white patches on the skin either due to the loss of functional melanocytes or perturbations in the melanogenesis pathway. In the present study, we investigated the therapeutic potential of herbo-mineral formulation, Melanogrit in neutralizing the white patches in the skin. The study utilized UPLC/MS-QToF technique to determine the diversified phytochemical profile in Melanogrit. The murine B16F10 cells when treated with Melanogrit underwent morphological changes, including increased angularity, enlarged cell size, and greater dendritic protrusions. To establish an equivalent model to study melanogenesis, we carefully optimized the dosage of α-melanocyte stimulating hormone (αMSH) in B16F10 cells as an alternative to using melanocyte-keratinocyte cocultures. The study determined a sub-optimal dose of αMSH (0.2 nM) in B16F10 cells that does not manifest any measurable effects on melanogenesis. In contrast, Melanogrit when used in conjunction with 0.2 nM αMSH, induced a dose-dependent increase in extracellular and intracellular melanin levels. Melanogrit transcriptionally up-regulated the decisive genes of the melanogenesis pathway, MITF, TYR, and TRP1, which was evident from the increased cellular tyrosine activity. Our findings also demonstrated that Melanogrit ameliorated the MITF protein levels by inhibiting pERK; notably without involving GSK3β in the process. Taken together, our findings strongly suggest that Melanogrit has the potential to stimulate melanogenesis, making it a promising candidate for clinical applications in the treatment of white skin patches that develop in vitiligo patients.

Awareness of sun exposure risks and photoprotection for preventing pigmentary disorders in Asian populations: Survey results from three Asian countries and expert panel recommendations

BACKGROUND

In this article, we review and discuss the photoprotection behavior of Asians based on the literature, along with a subanalysis of an original online survey, and make recommendations to optimize photoprotection for Asian populations to prevent photoaging and pigmentary disorders.

METHODS

An international panel of eight dermatologists from Asia (China, Korea, Japan, Singapore, Indonesia, and Vietnam) met to discuss sunscreen photoprotection for Asian patients. Additionally, a subanalysis of an online survey by 3000 respondents from three Asian countries (China, Indonesia, and Japan) investigated general public awareness and attitudes to sun exposure.

RESULTS

A pre-meeting survey of the eight experts from Asia showed key concerns of Asian patients consulting dermatologists are pigmentary disorders, especially actinic/senile lentigo, post-inflammatory hyperpigmentation, melasma, vitiligo, and Hori's nevus. The survey subanalysis of participants from China, Indonesia, and Japan with predominantly Fitzpatrick skin types (FST) II to IV revealed that they are particularly concerned about sun exposure causing photoaging and pigmentary disorders. Most of the respondents indicated they have limited knowledge on sunlight radiation and appropriate sunscreen protection factors. Only 22%, 13%, and 3% for China, Indonesia, and Japan, respectively, systematically use multiple protective measures (using sunscreen, avoiding midday sun, staying in the shade, wearing a hat, protective clothing, and sunglasses) when exposed to the sun.

CONCLUSIONS

Further education is needed for Asian populations on the importance of comprehensive daily photoprotection, including broad-spectrum sunscreen, with high UVA and visible light protection, to reduce and prevent photoaging and pigmentary disorders.

The possible role of Wnt/β-catenin signalling in vitiligo treatment

Vitiligo is a common chronic skin disease which has an adverse impact on patients' life. Its pathogenesis is complex, involving autoimmunity and oxidative stress (OS). Autoimmunity leads to the loss of epidermal melanocytes and the formation of the depigmented patches of the disease. Treatment of vitiligo should control the exaggerated immune response to arrest the progress of active disease, and then promote melanocytes to repigmentation. Wnt/β-catenin signalling pathway has been of recent interest in vitiligo. Wnt/β-catenin signalling pathway is downregulated in vitiligo. Upregulation of Wnt/β-catenin signalling possibly control vitiligo autoimmune response by protecting melanocyte from OS damage, inhibiting CD8+ T cell effector cell differentiation and enhancing Treg. Wnt/β-catenin signalling plays a critical role in the melanocyte regeneration by driving the differentiation of melanocyte stem cells (McSCs) into melanocytes. Promoting Wnt/β-catenin signalling can not only arrest the progress of active disease of vitiligo but also promote repigmentation. Some of the main effective therapies for vitiligo are likely to work by activating Wnt/β-catenin signalling. Agents that can enhance the effect of Wnt/β-catenin signalling may become potential candidates for the development of new drugs for vitiligo treatment.

Assessment of changes in color and size of vitiligo lesions during treatment with narrow band ultraviolet B

BACKGROUND

Many treatment modalities have been used to stabilize vitiligo and induce repigmentation. Several methods were used to monitor the color changes inside the treated lesions such as spectroscopes and colorimeters that measure the melanin index inside the lesion.

OBJECTIVE

To study whether the colorimeter and point counting technique can be used as objective methods in monitoring vitiligo lesions during treatment with Nb-UVB.

METHODS

Twenty randomly chosen patients with non-segmental vitiligo were enrolled in this interventional study. Vitiligo disease activity score was recorded in each patient. Patients received Nb-UVB three times per week for 6 months. Two lesions were chosen in each patient, and each lesion was assessed for size using point counting technique and degree of color using the Dermacatch® at the beginning of the treatment and evaluated for changes in color and size every 4 weeks till the end of the treatment.

RESULTS

After 6 months of treatment, regarding the lesion size, 90% of lesions showed variable degrees of repigmentation and 10% showed increase in size, indicating increased activity of the disease, and regarding to color changes. We noticed that after one month of Nb-UVB treatment, there is marked increase in MI measurements in many lesions before any clinical improvement appeared, while at the end of treatment, inside the lesion; 95% showed an increase in melanin index and 5% showed no elevation. While the color changes outside the lesion showed 75% of lesions increased in melanin index, 15% remained unchanged and 10% of the lesions showed decrease in melanin index.

CONCLUSION

Colorimeter was able to detect change in color after only one month of treatment before it was clinically apparent which means that it can be used as a prognostic tool.

The Efficacy and Psychoneuroimmunology Mechanism of Camouflage Combined With Psychotherapy in Vitiligo Treatment

Background and Objectives

The efficacy of camouflage combined with psychotherapy and the underlying mechanisms are poorly understood in vitiligo management. This study aimed to investigate the joint efficacy and further explore psycho-neuro-endocrine-immune-skin interactions.

Patients and Methods

In a prospective, non-randomized and concurrent controlled trial, patients were divided into two groups. Quality of life (QOL) was evaluated using the Chinese version of the Vitiligo Life Quality Index (VLQI-C). Serum levels of neuropeptides and cytokines were detected by enzyme-linked immunosorbent assay.

Results

A total of 149 patients were included for final evaluation. After treatment for 4 weeks, total and subcategory quality of life scores in the intervention group were much lower than in the control group. Serum levels of neuropeptide-Y (NPY) and melanin-concentrating hormone (MCH) significantly decreased, and serum level of adrenocorticotropic hormone (ACTH) increased in both active and stable patients of the intervention group, but not in the control group. In addition, the serum levels of interferon-γ (IFN-γ), CXC chemokine ligand 10 (CXCL10), and interleukin-1β (IL-1β) decreased in both the active and stable patients of the intervention group and only in the active patients of the control group.

Conclusions

The combination of camouflage and psychotherapy provided a clinically meaningful improvement in quality of life and ameliorated the outcome by likely modulating the psycho-neuro-endocrine-immuno-skin system during vitiligo management.

Clinical Trial Registration

www.clinicaltrials.gov/ct2/show/NCT03540966, identifier: NCT03540966.

Surgical procedures and innovative approaches for vitiligo regenerative treatment and melanocytorrhagy

Surgical treatments for vitiligo are a safe and effective treatment modality for select patients with vitiligo. Many techniques of vitiligo surgery exist, each with unique advantages and disadvantages. We reviewed the various surgical therapies and innovative approaches for vitiligo regenerative treatment reported in the literature. Surgical therapies can be subdivided into tissue grafting methods and cellular grafting methods. Tissue grafting methods mainly include mini punch grafts, suction blister roof grafts, and hair follicle grafts. Cellular grafting methods include cultured and non-cultured treatments. The efficacy needs to be improved largely due to the poor proliferation and quality of the autologous melanocytes. Rho-associated protein kinase inhibitor enhances primary melanocyte culture proliferation from vitiligo patients to prevent apoptosis. Innovative approaches using stem cell methods could prove invaluable in developing a novel cell therapy for patients suffering from vitiligo. We succeeded in inducing melanin pigmentation in mice skin in vivo using our human induced pluripotent stem cell-derived melanocytes. In addition, we reviewed melanocytorrhagy, detachment and transepidermal loss of melanocytes, and melanocyte-related adhesion molecules. These adhesion molecules include epithelial cadherin, discoidin domain receptor tyrosine kinase 1, glycoprotein non-metastatic melanoma protein B, macrophage migration inhibiting factor, 17β-hydroxysteroid dehydrogenase 1, and E26 transformation-specific 1.

Discovery of small-molecule modulators of melanogenesis by docking-based virtual screening

Background: Vitiligo is a relatively common depigmenting skin disorder. UV light stimulation is often used to obtain repigmentation. Wnt signaling regulates melanocyte differentiation, and expression of TYR is upregulated in narrow-band UVB-treated epidermis. Manipulation of these two pathways by drugs could serve as one of the therapeutic approaches for durable repigmentation. Methods and results: CD9 was identified as a novel TYR activator by virtual screening and bioactivity assay. CD9 activated the Wnt signaling pathway through triggering translocation of β-catenin from cytoplasm to nucleus. Conclusion: The pathogenesis of vitiligo is complicated and varies with each individual, so combination therapy may be much more suitable for treatment of vitiligo. CD9 could synergize with other anti-inflammatory compounds or autoimmune suppressors to shorten repigmentation time and improve efficacy.

Reduced risk of skin cancer and internal malignancies in vitiligo patients: a retrospective population-based cohort study in Taiwan

The relationship between cancer and vitiligo has been explored but with inconsistent results. To examine the long-term cancer risk in vitiligo patients, we conducted a retrospective nationwide cohort study. From the National Health Insurance Research Database of Taiwan, a total of 13,824 vitiligo patients were identified and matched with 55,296 reference subjects without vitiligo by age, gender, and propensity score estimated by major comorbidities from 1997 to 2013. Demographic characteristics and comorbidities were compared between these two groups. Incidence rate ratios and hazard ratios (HRs) were calculated to examine cancer risks. The 16-year incidence rates of overall cancers were 621.06 (566.56–675.55) and 726.99 (697.24–756.74) per 100,000 person-years in the vitiligo and reference groups. Patients with vitiligo showed a significantly decreased risk of overall cancers [adjusted HR, 0.85; 95% confidence interval (CI), 0.77 to 0.93, p < 0.001] compared with reference subjects without vitiligo after adjusting for age, sex, comorbidities, and treatments. The risks of basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) were significantly reduced (adjusted HR 0.21, 95% CI 0.11–0.38, p < 0.001), as well as internal malignancies (adjusted HR 0.89, 95% CI 0.81–0.99, p = 0.026). The results were consistent across different subgroups of patients, including male gender, ages more than 40 years, and those receiving long-term systemic disease-modifying antirheumatic drugs and phototherapies. Information related to phenotype, disease duration, vitiligo lesion sites, family history of vitiligo or cancer, occupation, and personal lifestyle was not included in the database. Vitiligo is associated with reduced risks of BCC and SCC, as well as internal malignancies.

Clinical Features, Immunopathogenesis, and Therapeutic Strategies in Vitiligo

Vitiligo is an autoimmune disease of the skin characterized by epidermal melanocyte loss resulting in white patches, with an approximate prevalence of 0.5-2% worldwide. Several precipitating factors by chemical exposure and skin injury present commonly in patients with vitiligo. Although the diagnosis appears to be straightforward for the distinct clinical phenotype and specific histological features, vitiligo provides many challenges including chronicity, treatment resistance, frequent relapse, associated profound psychosocial effect, and negative impact on quality of life. Multiple mechanisms are involved in melanocyte disappearance, including genetics, environmental factors, and immune-mediated inflammation. Compelling evidence supports the melanocyte intrinsic abnormalities with poor adaptation to stressors leading to instability and release of danger signals, which will activate dendritic cells, natural killer cells, and innate lymphoid cells to initiate innate immunity, ultimately resulting in T-cell mediated adaptive immune response and melanocyte destruction. Importantly, the cross- talk between keratinocytes, melanocytes, and immune cells, such as interferon (IFN)-γ signaling pathway, builds inflammatory loops that give rise to the disease deterioration. Improved understanding of the immune pathogenesis of vitiligo has led to the development of new therapeutic options including Janus kinase (JAK) inhibitors targeting IFN-γ signaling pathways, which can effectively reverse depigmentation. Furthermore, definition of treatment goals and integration of comorbid diseases into vitiligo management have revolutionized the way vitiligo is treated. In this review, we highlight recent developments in vitiligo clinical aspects and immune pathogenesis. Our key objective is to raise awareness of the complexity of this disease, the potential of prospective therapy strategies, and the need for early and comprehensive management.

Male genital vitiligo

Vitiligo is a polygenetic multifactorial disease leading to melanocytic loss in skin and sometimes in hair. Genital areas may be involved and represent a specific therapeutic challenge. Surprisingly, data on male genital vitiligo remain scarce. This review aims to collate current knowledge on male genital vitiligo and to discuss the risks and benefits of the various therapeutic approaches. Male genital vitiligo is relatively frequent and often induces marked impairment of quality of life, with a specific impact on sex life. Prompt recognition of activity remains mandatory to halt disease progression, as repigmentation remains difficult to achieve in most cases. Thanks to progress in understanding of the pathophysiology of vitiligo, new therapeutic approaches are under development. Topical ruxolitinib, a JAK pathway inhibitor, is currently the product in the most advanced stage of development, with a very encouraging repigmentation rate on the face, although specific efficacy in genital area remains to be assessed. The next generation of treatments, such as topical WNT agonists, could be of great interest in genital vitiligo as they will not require combination with UV therapy and they may be able to enhance the differentiation and proliferation of melanocyte stem cells in this difficult-to-treat area.

Updates and new medical treatments for vitiligo (Review)

Vitiligo is a multifactorial disease characterized by the loss of skin pigment, which results in achromic macules and patches. There are currently several medical treatments available, which aim to arrest progression and induce skin repigmentation. These treatments alone or combined have exhibited varying degrees of pigmentation, and the majority are safe and effective. All therapies for vitiligo are limited, and no known treatment can consistently produce repigmentation in all patients. Individualized treatment is appropriate according to the location, clinical presentation and the presence of disease activity. The present review summarizes the medical treatments available for vitiligo: Systemic and topic pharmacological therapies, physical and depigmentation treatments. Several treatments are still underway and have not yet been approved. However, due to the promising preliminary results, these are also mentioned in the present review.

Photoprotection according to skin phototype and dermatoses: practical recommendations from an expert panel

Increasing evidence on the impact of the different wavelengths of sunlight on the skin demonstrates the need for tailored recommendations of sunscreen according to skin phototype and dermatoses, which is now possible due to advances in the filters and formulations of sunscreens. A selective literature search was performed by an international expert panel, focusing on the type of sunscreen to recommend for photoaging, skin cancers, photodermatoses, pigmentary disorders and skin inflammatory disorders. Protection against ultraviolet (UV)B is especially important for light skin as there is a high risk of sunburn, DNA damage and skin cancers. Darker skin may be naturally better protected against UVB but is more prone to hyperpigmentation induced by visible light (VL) and UVA. Protection against UVA, VL and infrared A can be helpful for all skin phototypes as they penetrate deeply and cause photoaging. Long‐wave UVA1 plays a critical role in pigmentation, photoaging, skin cancer, DNA damage and photodermatoses. Adapting the formulation and texture of the sunscreen to the type of skin and dermatoses is also essential. Practical recommendations on the type of sunscreen to prescribe are provided to support the clinician in daily practice.

Targeting Innate Immunity to Combat Cutaneous Stress: The Vitiligo Perspective

Multiple factors are involved in the process leading to melanocyte loss in vitiligo including environmental triggers, genetic polymorphisms, metabolic alterations, and autoimmunity. This review aims to highlight current knowledge on how danger signals released by stressed epidermal cells in a predisposed patient can trigger the innate immune system and initiate a cascade of events leading to an autoreactive immune response, ultimately contributing to melanocyte disappearance in vitiligo. We will explore the genetic data available, the specific role of damage-associated-molecular patterns, and pattern-recognition receptors, as well as the cellular players involved in the innate immune response. Finally, the relevance of therapeutic strategies targeting this pathway to improve this inflammatory and autoimmune condition is also discussed.

Stem Cell Therapy Offers a Possible Safe and Promising Alternative Approach for Treating Vitiligo: A Review

BACKGROUND

Normal skin pigmentation pattern is an extremely important component of the appearance of a person, as it can be a significant factor in the social context of any person. A condition known as vitiligo is caused by the death of melanocytes leading to pigmentation loss in the skin. This affects all races across the globe and sometimes leads to social avoidance as in some communities, it is stigmatized. Although there are different pathobiological processes suspected because of the different underlying causes of vitiligo, autoimmunity and oxidative stress are suspected to be the most probable ones.

OBJECTIVE

In this review, we present an overview of the underlying mechanisms causing and developing the disease. Also, some of the most successful treatments along with the clinical applications of Mesenchymal Stem Cells (MSCs) as a comprehensive approach for treating this condition will be covered.

RESULTS

Autoreactive CD8+ T-cells are the primary suspect considered to be responsible for the destruction of melanocytes. Therefore, topical use of autoimmune inhibitors including those derived from MSCs, thanks to their immune-modulatory properties, have been reported to be successful in the promotion of repigmentation. MSCs can suppress the proliferation of CD8+T via the NKG2D pathway while inducing T-cell apoptosis. The use of pharmacological agents for reducing cellular oxidative stress with the help of topical application of antioxidants and growth factors also have been in use. Intravenous administration of MSCs has been shown to regulate the level of reactive oxidative species (ROS) in a mice model. Growth factors derived from platelet-rich-plasma (PRP) or from MSCs caused rapid tissue regeneration.

CONCLUSIONS

Finally, MSC therapy also has been shown to stimulate the mobilization of healthy melanocytes, leading to successful repigmentation of skin lesions in vitiligo patients.

Oral mini-pulse therapy in vitiligo: a systematic review

BACKGROUND

There is limited evidence supporting the use of alternative treatments for patients with nonstable vitiligo.

OBJECTIVE

This study aimed to review the effects of oral mini-pulse (OMP) therapy in the management of nonsegmental vitiligo.

METHODS

The following databases were searched between inception and May 2020 for relevant studies: Scopus, Web of Science, MEDLINE, and Embase. All randomized controlled trials that compared OMP therapy with any other active treatment or placebo for nonstable vitiligo were included. The Cochrane's risk of bias tool was used to evaluate the risk of bias (ROB) in selected studies, and the overall quality of evidence of each outcome was assessed using the Grading Recommendations, Assessment, Development, and Evaluations (GRADE) system.

RESULTS

Four studies met our selection criteria. All of them were conducted in India and included 246 patients. OMP therapy included betamethasone or dexamethasone. The duration of treatment was 6 months in all studies. Up to 32% of patients achieved a repigmentation rate of >75% when OMP therapy was administered as monotherapy. No difference was observed between OMP therapy and other treatments in arresting the disease, and weight gain was the most frequent adverse effect. The overall ROB in all included studies was relatively high because of the randomization process, outcome measurement and informed selection of outcomes.

CONCLUSION

Based on the findings of these studies, OMP therapy did not demonstrate additional value compared with other treatments. Hence, there is an urgent need to conduct high-quality clinical trials to evaluate this therapy.

A retrospective study of long term follow-up of 2283 vitiligo patients treated by autologous, non-cultured melanocyte-keratinocyte transplantation

Background: Autologous non-cultured melanocyte-keratinocyte transplantation (MKTP) can be used to treat stable vitiligo cases, but there were insufficient clinical data to evaluate its safety and efficacy.

Objective: To assess the influence of various factors on the therapeutic outcome of MKTP.

Method: The single-center retrospective study included stable vitiligo patients who underwent MKTP between June 2009 and June 2018. Univariate and/or multivariable analysis were used to determine the factors affecting the outcome of repigmentation.

Result: The study comprised 2283 patients who had long-term follow-up data (12-108months). Excellent repigmentation was achieved in 400/606 (66%),788/1341 (58.8%),437/684 (63.9%),18/24 (75%) patients with segmental vitiligo, pre-MKTP phototherapy, younger than 24 years, the lesion on the perineum and scrotum, respectively. However, the patients with a positive family history, Koebner phenomenon responded worse(χ²=29.417, P<0.001; χ²=107.397, P<0.001; respectively). Overall, a significant positive correlation between duration of stability and percentage of repigmentation was found (χ²=42.053, P<0. 001).

Conclusion: MKTP is efficient and well tolerated for stable vitiligo treatment. Various factors such as duration of disease stability, vitiligo type, family history, site of lesion should be carefully assessed before using MKTP, as it would further improve the post-operative repigmentation.

Deciphering skin re-pigmentation patterns in vitiligo: an update on the cellular and molecular events involved

Current treatment of vitiligo is still a great challenge, since most cases of vitiligo have variable re-pigmentation outcomes due to their unpredictable responses to existing therapeutic regimens. There is an urgent need to identify this re-pigmentation process and to develop novel therapies. This review illustrates the most current research and latest understanding of vitiligo skin re-pigmentation and related regulatory mechanisms. Literature was collected from PubMed until January 2020, using the search terms including "vitiligo," "re-pigmentation," "phototherapy," "narrow-band ultraviolet B, " "excimer," "fractional carbon dioxide laser," and "melanocyte stem cells." Literature was mainly derived from English articles. Article type was not limited. Emerging evidence suggests that patients with vitiligo present various re-pigmentation patterns following ultraviolet B phototherapy, which relies on different cell reservoirs from the perilesional margins and/or from uninvolved hair follicles to replenish functional melanocytes that are lost in vitiliginous skin. The following events are likely to be involved in this re-pigmentation process, including: 1) changes in the paracrine secretion and distribution of transforming growth factor-β1 in the bulge area and in the epidermis; 2) the enhanced transfer of dermal pro-melanogenic growth factors to the epidermis; and 3) the induction of a C-X-C motif chemokine ligand (CXCL) 12-enriched micro-environment that efficiently recruits CXCR4- or CXCR7-positive melanocytes. Ongoing studies on the cellular and molecular events underlying vitiligo re-pigmentation will help design new therapeutic strategies to improve treatment outcomes.

Vitiligo: Mechanisms of Pathogenesis and Treatment

Vitiligo is an autoimmune disease of the skin that targets pigment-producing melanocytes and results in patches of depigmentation that are visible as white spots. Recent research studies have yielded a strong mechanistic understanding of this disease. Autoreactive cytotoxic CD8+ T cells engage melanocytes and promote disease progression through the local production of IFN-γ, and IFN-γ-induced chemokines are then secreted from surrounding keratinocytes to further recruit T cells to the skin through a positive-feedback loop. Both topical and systemic treatments that block IFN-γ signaling can effectively reverse vitiligo in humans; however, disease relapse is common after stopping treatments. Autoreactive resident memory T cells are responsible for relapse, and new treatment strategies focus on eliminating these cells to promote long-lasting benefit. Here, we discuss basic, translational, and clinical research studies that provide insight into the pathogenesis of vitiligo, and how this insight has been utilized to create new targeted treatment strategies.

Home phototherapy for patients with vitiligo: challenges and solutions

Vitiligo is a chronic autoimmune condition involving selective dysfunction and destruction of melanocytes in the skin, hair, or both. The typical presentation is well-demarcated depigmented skin patches. Given vitiligo is the most common cause of depigmentation worldwide and early disease responds best to treatment, prompt diagnosis and proactive management of vitiligo are critical. While a wide variety of treatments has demonstrated variable effectiveness in treating vitiligo, phototherapy remains standard of care because of its proven efficacy and favorable side effect profile. However, many patients with vitiligo are unable to access affordable, consistent, or convenient phototherapy. To address these issues, home-based phototherapy has emerged as a patient-centered alternative. The purpose of this review is to discuss management of vitiligo with a specific focus on access to home-based phototherapy (HBPT) for patients with this condition. Key challenges to HBPT include misperceptions around safety and efficacy, inadequate physician education and training, insurance and financial barriers, and appropriate patient selection. Solutions to these challenges are presented, such as approaches to improve physician education and increasing the evidence surrounding the effectiveness and safety of this treatment for vitiligo. In addition, various practical considerations are discussed to guide dermatologists on how to approach HBPT as a treatment option for patients with vitiligo.

Stem Cell-Derived Models of Neural Crest Are Essential to Understand Melanoma Progression and Therapy Resistance

During development, neural crest (NC) cells are early precursors of several lineages including melanocytes. Along their differentiation from multipotent cells to mature melanocytes, NC cells will go through successive steps which require either proliferative or motile capacities. For example, they will undergo Epithelial to Mesenchymal Transition (EMT) in order the separate from the neural tube and migrate to their final location in the epidermis (Larribere and Utikal, 2013; Skrypek et al., 2017). The differentiated melanocytes are the cells of origin of melanoma tumors which progress through several stages such as radial growth phase, vertical growth phase, metastasis formation, and often resistance to current therapies. Interestingly, depending on the stage of the disease, melanoma tumor cells share phenotypes with NC cells (proliferative, motile, EMT). These phenotypes are tightly controlled by specific signaling pathways and transcription factors (TFs) which tend to be reactivated during the onset of melanoma. In this review, we summarize first the main TFs which control these common phenotypes. Then, we focus on the existing strategies used to generate human NCs. Finally we discuss how identification and regulation of NC-associated genes provide an additional approach to improving current melanoma targeted therapies.

Therapeutic management of vitiligo

Affecting 0.5 % of the world's population, vitiligo is an acquired skin disorder that poses major challenges in terms of dermatological care. Characterized by patchy depigmentation, the disease is frequently associated with cosmetic disfigurement and considerable psychological distress. The primary pathophysiological causes for the loss of functional melanocytes are thought to include genetic predisposition, autoimmune mechanisms, and oxidative stress. The present article highlights treatment recommendations contained in the European guidelines as well as those provided by recent reviews on vitiligo. Current therapeutic options are based on three approaches: (1) Regulation of the autoimmune response using topical and systemic immunomodulatory agents (corticosteroids and calcineurin inhibitors); (2) decrease in oxidative stress in melanocytes by means of topical and systemic antioxidants; and (3) activation of melanocyte regeneration using phototherapy (UVB in particular) and transplantation of pigment cells. In addition, patients should be educated in techniques for cosmetic camouflage. Following successful repigmentation, application of calcineurin inhibitors is recommended to prevent recurrences. Combination therapies of the aforementioned approaches are generally considered to be more successful than monotherapies. Early initiation of treatment is associated with a more favorable prognosis. Using the above treatment options, it may be possible to halt disease progression, stabilize depigmented lesions, and achieve repigmentation. Only in exceptional cases should permanent depigmentation be considered as a possible option. New insights into the pathogenesis of vitiligo will likely give rise to novel therapeutic approaches.

Clinical and Molecular Aspects of Vitiligo Treatments

Vitiligo is an asymptomatic but cosmetically disfiguring disorder that results in the formation of depigmented patches on skin and/or mucosae. Vitiligo can be segmental or non-segmental depending upon the morphology of the clinical involvement. It can also be classified as progressing or stable based on the activity of the disease. Further, the extent of involvement can be limited (localized disease) or extensive (generalized disease). The treatment of vitiligo therefore depends on the clinical classification/characteristics of the disease and usually comprises of 2 strategies. The first involves arresting the progression of active disease (to provide stability) in order to limit the area involved by depigmentation. The second strategy aims at repigmentation of the depigmented area. It is also important to maintain the disease in a stable phase and to prevent relapse. Accordingly, a holistic treatment approach for vitiligo should be individualistic and should take care of all these considerations. In this review, we shall discuss the vitiligo treatments and their important clinical and molecular aspects.