Melanocytes are not absent in lesional skin of long duration vitiligo

Endoplasmic Reticulum Dysfunction: An Emerging Mechanism of Vitiligo Pathogenesis

The endoplasmic reticulum (ER) is the main site of protein synthesis, transport, and modification. Its abnormal status has now emerged as an established cause of many pathological processes, such as tumors and autoimmune diseases. Recent studies also demonstrated that the defective functions of ER may lead to pigmentary diseases. Vitiligo is a depigmenting ailment skin disorder whose pathogenesis is now found to be associated with ER. However, the detailed mechanism is still unclear. In this review, we try to link the association between ER with its inter- and intra-organellar interactions in vitiligo pathogenesis and focus on the function, mechanism, and clinical potential of ER with vitiligo. Expand ER is found in melanocytes of vitiligo and ER stress (ERS) might be a bridge between oxidative stress and innate and adaptive immunity. Meanwhile, the tight association between ER and mitochondria or melanosomes in organelles levels, as well as genes and cytokines, is the new paradigm in the pathogenesis of vitiligo. This undoubtedly adds a new aspect to the understanding of vitiligo, facilitating the design of targeted therapies for vitiligo.

Role of Dermal Factors Involved in Regulating the Melanin and Melanogenesis of Mammalian Melanocytes in Normal and Abnormal Skin

Mammalian melanin is produced in melanocytes and accumulated in melanosomes. Melanogenesis is supported by many factors derived from the surrounding tissue environment, such as the epidermis, dermis, and subcutaneous tissue, in addition to numerous melanogenesis-related genes. The roles of these genes have been fully investigated and the molecular analysis has been performed. Moreover, the role of paracrine factors derived from epidermis has also been studied. However, the role of dermis has not been fully studied. Thus, in this review, dermis-derived factors including soluble and insoluble components were overviewed and discussed in normal and abnormal circumstances. Dermal factors play an important role in the regulation of melanogenesis in the normal and abnormal mammalian skin.

Study protocol: Neuro-inflammatory parameters as mediators of the relationship between social anxiety and itch intensity: A cross-sectional, controlled laboratory study in patients with psoriasis and healthy skin controls

INTRODUCTION

Psoriasis (PSO) is a disease that in the majority of patients is accompanied by itch, which imposes a great burden and positively relates to anxiety. Social anxiety, a facet of anxiety associated with social withdrawal, may be a predictor of itch intensity in this patient group. Moreover, anxiety is linked to the secretion of neuroendocrine and inflammatory parameters such as substance P (SP), interleukin (IL)-6 and IL-17, which are also related to itch. In this research project, we investigate first, whether there is a direct relationship between social anxiety and itch intensity in patients with PSO and second whether the secretion of SP, IL-6 and IL-17 in the skin mediates this relationship. Additionally, PSO-patients are compared to healthy skin controls regarding their level of social anxiety, itch intensity and the secretion of SP, IL-6 and IL-17.

METHODS AND ANALYSES

For study 1, we aim to recruit 250 psoriasis patients and 250 healthy skin controls who complete questionnaires to assess social anxiety, itch intensity and control variables (e.g. sociodemographic variables and severity of PSO). A linear hierarchic regression will be used to determine whether social anxiety significantly contributes to itch intensity. In study 2, we plan to apply the suction blister method to 128 patients and healthy skin controls recruited from study 1 to determine SP, IL-6 and IL-17 in tissue fluid extracted from the skin. A mediation analysis will be conducted using the SPSS-macro PROCESS to test whether the relationship between social anxiety and itch is mediated by SP, IL-6 and IL-17.

TRIAL REGISTRATION NUMBERS

DRKS00023621 (study 1) and DRKS00023622 (study 2).

Transplantation of autologous epidermal melanocyte-keratinocyte cells suspension for cell therapy of vitiligo: A clinical evaluation and biometric assessment

INTRODUCTION

Among several surgical treatments, the use of transplantation of epidermal cultured melanocytes or melanocytes-keratinocytes cell suspension has gained many researchers and dermatologists' attention as a new technique for the treatment of vitiligo. The present study aimed to transplant autologous epidermal melanocytes-keratinocytes cell suspension for the treatment of vitiligo.

METHODS

In this study, 15 volunteer patients aged between 18 and 45 years old were studied. The autologous melanocytes-keratinocytes cell suspension was then transplanted to the region after dermabrasion. The included patients were evaluated by VisioFace, MPA9, and Skin Scanner-DUB once before and 1, 2, and 6 months after the transplantation, while the extents of stainability and changes in the transplanted region were recorded.

RESULTS

The color contrast between the lesion and normal skin significantly decreased after 1, 2, and 6 months of the melanocytes transplantation compared with the pre-procedure (13.8 ± 0.45 before vs. 12.9 ± 0.43, 12.2 ± 0.45, and 10.2 ± 0.34 at months 1, 2, and 6, p < 0.001). Furthermore, melanin index significantly increased six months after cell transplantation compared to the pretreatment (168.3 ± 4.22 vs. 130.5 ± 3.98, p < 0.001).

CONCLUSION

Transplantation of melanocytes cells with dermabrasion can be effective on vitiligo improvement, so it is recommended.

Loss of 'Epidermal Melanin Unit' Integrity in Human Skin During Melanoma-Genesis

Cutaneous melanoma can be a most challenging neoplasm of high lethality, in part due to its extreme heterogeneity and characteristic aggressive and invasive nature. Indeed, its moniker 'the great masquerader' reflects that not all melanomas are created equal in terms of their originating cellular contexts, but also that melanoma cells in the malignant tumor can adopt a wide range of different cell states and variable organotropism. In this review, we focus on the early phases of melanomagenesis by discussing how the originating pigment cell of the melanocyte lineage can be influenced to embark on a wide range of tumor fates with distinctive microanatomical pathways. In particular, we assess how cells of the melanocyte lineage can differ by maturation status (stem cell; melanoblast; transiently amplifying cell; differentiated; post-mitotic; terminally-differentiated) as well as by micro-environmental niche (in the stratum basale of the epidermis; within skin appendages like hair follicle, eccrine gland, etc). We discuss how the above variable contexts may influence the susceptibility of the epidermal-melanin unit (EMU) to become unstable, which may presage cutaneous melanoma development. We also assess how unique features of follicular-melanin unit(s) (FMUs) can, by contrast, protect melanocytes from melanomagenesis. Lastly, we postulate how variable melanocyte fates in vitiligo, albinism, psoriasis, and alopecia areata may provide new insights into immune-/non immune-mediated outcomes for melanocytes in cutaneous melanin units.

Melanocytes and keratinocytes morphological changes in vitiligo patients. A histological, immunohistochemical and ultrastructural analysis

Vitiligo is an idiopathic acquired chronic stigmatizing disease. It is a pigmentary disorder that affects the skin and the mucous membranes, and it is characterized by well-circumscribed, depigmented milky white macules and patches. It has an estimated prevalence of 0.5-2% of the population worldwide. In the previous studies, several mechanisms such as autoimmune, oxidative stress, genetic factors, melanocytorrhagy, and neural hypothesis have been suggested for vitiligo pathogenesis.We aimed to assess the morphological changes of epidermal melanocytes and keratinocytes in patients with vitiligo. This aim will be fulfilled by histological, ultrastructural, and immunohistochemical analysis of skin biopsies from lesioned and non-lesioned sites in vitiligo patients.The study was carried out on 15 selected patients with stable vitiligo vulgaris but not receiving treatment in the last year and they fulfilled our inclusion criteria.Biopsies were taken from lesioned and non-lesioned sites in the same vitiligo patients, and they are processed for examinations by LM (using Hx & E, and Masson Fontana stain), immunohistochemical analysis (using Melan-A, E-cadherin, and caspase-3), and TEM (to demonstrate the ultra-structures).By LM, staining with Hx & E, lesioned skin in vitiligo patients showed hyperkeratosis, basal vacuolization, acanthosis with an increase in the epidermal thickness, ballooning of keratinocytes, and spongiosis. Regarding melanocytes, we observed a few numbers of melanocytes, also we detected some basal epidermal cells contain brown melanin granules. Using Fontana-Masson stain, we found that the melanin pigment is present in both lesioned and non-lesioned skin of vitiligo patients. We confirmed the presence of melanocytes in the lesioned skin by the immunohistochemical staining with Melan-A. The epidermal cells in lesioned skin of vitiligo patients showed weak positive expression of E-cadherin between them and an increase in the number of apoptotic Caspase-3 positive cells. BY TEM, the lesioned skin in vitiligo patients showed that the keratinocytes and melanocytes had various degenerative changes, disturbance of desmosomes in between keratinocytes, and absence of melanosomes in the keratinocytes. The detected melanocytes were degenerated and contained some melanosomes, melanin granules, and autophagosomes.We concluded that vitiligo pathogenesis is a combination of several factors and cannot be explained by only one mechanism. The pathology in the lesioned vitiliginous skin is a combination of several degenerative changes in keratinocytes, and melanocytes.

Patho-immunological mechanisms of vitiligo: the role of the innate and adaptive immunities and environmental stress factors

Epidermal melanocyte loss in vitiligo, triggered by stresses ranging from trauma to emotional stress, chemical exposure or metabolite imbalance, to the unknown, can stimulate oxidative stress in pigment cells, which secrete damage-associated molecular patterns that then initiate innate immune responses. Antigen presentation to melanocytes leads to stimulation of autoreactive T-cell responses, with further targeting of pigment cells. Studies show a pathogenic basis for cellular stress, innate immune responses and adaptive immunity in vitiligo. Improved understanding of the aetiological mechanisms in vitiligo has already resulted in successful use of the Jak inhibitors in vitiligo. In this review, we outline the current understanding of the pathological mechanisms in vitiligo and locate loci to which therapeutic attack might be directed.

The clinical and pathological effectiveness of microneedling and topical 5-fluorouracil in vitiligo treatment: An association with matrix metalloproteinase 2 immunohistochemical expression

BACKGROUND

The current therapies for vitiligo require long duration with often disappointing outcomes. 5-Fluorouracil (5-FU) is a chemotherapeutic agent approved for topical use in the treatment of several dermatologic conditions. Matrix metalloproteinase 2 (MMP2) is synthesized by keratinocytes during the epidermal remodeling process and has been found to help in melanocyte migration.

AIM

To investigate the efficacy and safety of flexible microneedling followed by application of 5-FU in vitiligo treatment and to evaluate the immunohistochemical expression of MMP2 in involved skin in vitiligo patients before and after treatment.

METHODS

Twenty patients presented with vitiligo were planned to receive one session every 2 weeks for 12 weeks of microneedling followed by 5-FU application. Clinical response to therapy was evaluated by VASI score. Pre- and post-treatment biopsies were taken from vitiliginous patches for MMP2 immunostaining.

RESULTS

Fifteen patients (75%) responded to therapy with observed side effects such as pain, erythema, and hyperpigmentation of margins. The clinical response was more in young patients and those who have short disease duration. MMP2 was significantly increased in post-treatment biopsy compared with the pretreatment one.

CONCLUSIONS

5-Fluorouracil application after microneedling is effective in the treatment of vitiligo with 75% response, 60% patient satisfaction, and tolerable side effects. The improvement in vitiligo patients by microneedling and 5-fluorouracil could be due to upregulation of MMP2 in affected vitiligo specimens.

Culturing of Melanocytes from the Equine Hair Follicle Outer Root Sheath

Hair follicles harbor a heterogeneous regenerative cell pool and represent a putative low-to-non-invasively available source of stem cells. We previously reported a technology for culturing human melanocytes from the hair follicle outer root sheath (ORS) for autologous pigmentation of tissue engineered skin equivalents. This study translated the ORS technology to horses. We de-veloped a culture of equine melanocytes from the ORS (eMORS) from equine forelock hair follicles cultured by means of an analogue human hair follicle-based in vitro methodology. The procedure was adjusted to equine physiology by addition of equine serum to the culture medium. The hair follicles were isolated by macerating forelock skin rests, enzymatically digested and subjected to air-medium-interface cultivation method. The procedure resulted in differentiated equine melanocytes, which exhibited typical morphology, presence of melanosomes, expression of cytoskeleton proteins vimentin, α-SMA, Sox2, S100ß and tyrosinase as well as tyrosinase activity followed by production of melanin. According to all assessed parameters, eMORS could be ranked as partially melanotic melanocytes. The results of the study offer an experimental base for further insight into hair follicle biology in equine and for comparative studies of hair follicles across different species.

Anxiety and depression in pediatric patients with vitiligo and alopecia areata and their parents: A cross-sectional controlled study

BACKGROUND

Alopecia areata (AA) and vitiligo are associated with various psychiatric comorbidities, and the care of a child with AA or vitiligo may be associated with higher anxiety and depression than healthy children.

AIMS

We aimed to identify psychiatric findings in children and adolescent groups with AA and vitiligo and to evaluate the levels of anxiety and depression in their parents.

METHODS

This study included 31 patients with AA and 29 patients with vitiligo, aged seven to 17 years, and their parents. Age- and gender-matched 30 controls and their parents were included. The patients and controls completed the Revised Child Anxiety and Depression Scales-Child version (RCADS-C), and their parents completed the parent version (RCADS-P). The parents also completed the Beck Anxiety Inventory (BAI) and Beck Depression Inventory (BDI). In addition, the stressful event history of all cases was noted.

RESULTS

Stressful event history was higher in the vitiligo group compared to the AA group, and it was higher in the AA and vitiligo groups compared to the control group. Separation anxiety, generalized anxiety, social phobia, and major depressive disorder (MDD) scores were higher in the AA group than controls according to the RCADS-C. According to the RCADS-P, panic disorder (PD), MDD, and total anxiety scores were higher in the AA group. Only the PD and MDD scores were higher in the vitiligo group than those of the controls based on the RCADS-P. Lastly, no significant difference was observed between the three groups concerning the parents' BAI and BDI scores.

CONCLUSIONS

Stressful events were more common in pediatric patients with vitiligo than those with AA. Anxiety symptoms were more prevalent in patients with AA than those with vitiligo.

Melanosome transport and regulation in development and disease

Melanosomes are specialized membrane-bound organelles that synthesize and organize melanin, ultimately providing color to the skin, hair, and eyes. Disorders in melanogenesis and melanosome transport are linked to pigmentary diseases, such as Hermansky-Pudlak syndrome, Chediak-Higashi syndrome, and Griscelli syndrome. Clinical cases of these pigmentary diseases shed light on the molecular mechanisms that control melanosome-related pathways. However, only an improved understanding of melanogenesis and melanosome transport will further the development of diagnostic and therapeutic approaches. Herein, we review the current literature surrounding melanosomes with particular emphasis on melanosome membrane transport and cytoskeleton-mediated melanosome transport. We also provide perspectives on melanosome regulatory mechanisms which include hormonal action, inflammation, autophagy, and organelle interactions.

Extracellular fraction of adipose tissue as an innovative regenerative approach for vitiligo treatment

Vitiligo is a common, disfiguring autoimmune disease that negatively affects patients' self-esteem and quality of life. Current treatments are moderately effective in reversing disease and promoting melanocyte regeneration. Thus, therapeutic advanced strategies are emerging from regenerative medicine. It has recently emerged that adipose tissue secretome may be used as a cell-free therapy in skin regeneration since paracrine functions of adipose-derived stem cells alone are responsible for most of the therapeutic effect of stem cells in several animal disease models. In this study, we tested the effect of adipose tissue extracellular fraction (AT-Ex) isolated from lipoaspirates on dermal and epidermal vitiligo cells in vitro. Using this experimental model, we demonstrated that molecules secreted by adipose tissue ameliorate the capability to counteract oxidative stress by a physiological stimulation of intracellular antioxidant enzymes and positively impact on cell proliferation. Due to the presence of Wnt-secreted factors, AT-Ex treatment promotes glycogen synthase kinase 3β inactivation and consequently Wnt/β-catenin pathway activation. Collectively, our findings show that AT-Ex could be useful as a natural approach to improve treatment of vitiligo.

Dysfunction of ATG7-dependent autophagy dysregulates the antioxidant response and contributes to oxidative stress-induced biological impairments in human epidermal melanocytes

Autophagy is a process involving the self-digestion of components that participates in anti-oxidative stress responses and protects cells against oxidative damage. However, the role of autophagy in the anti-oxidative stress responses of melanocytes remains unclear. To investigate the role of autophagy in human epidermal melanocytes, we knocked down and overexpressed ATG7, the critical gene of autophagy, in normal human epidermal melanocytes. We demonstrated that ATG7-dependent autophagy could affect melanin content of melanocytes by regulating melanogenesis. Moreover, suppression of ATG7-dependent autophagy inhibits proliferation and promotes oxidative stress-induced apoptosis of melanocytes, whereas enhancement of ATG7-dependent autophagy protects melanocytes from oxidative stress-induced apoptosis. Meanwhile, deficiency of ATG7-dependent autophagy results in premature senescence of melanocytes under oxidative stress. Notably, we verified that ATG7-dependent autophagy could alter oxidative stress homeostasis by regulating reactive oxygen species (ROS) production, nuclear factor erythroid 2-related factor 2 (Nrf2) antioxidant pathway, and the activity of several antioxidant enzymes in melanocytes. In conclusion, our study suggested that ATG7-dependent autophagy is indispensable for redox homeostasis and the biological functions of melanocytes, such as melanogenesis, proliferation, apoptosis, and senescence, especially under oxidative stress.

Sleep Quality and Depression in Vitiligo Patients

Aim: Vitiligo is a common disorder that has not only dermatological but also psychological consequences. The aim of this study was to compare depression and sleep quality of vitiligo patients with healthy control group. Methods: In this cross-sectional case-control study, patients admitted to the Dermatology Clinic of Skin and Venereal Diseases Department of Hitit University Erol Olçok Education and Research Hospital between August 2018 and August 2019 were compared with healthy control group. The study included 67 patients and 69 control group participants who were matched for age, sex, marriage status, and education level. The subjects were asked to complete a sociodemographic data form, the Beck Depression Inventory, and the Pittsburgh Sleep Quality Index. Results: The median total Pittsburgh Sleep Quality Index score was higher in the patient group compared with the control group. The median scores for subjective sleep quality, sleep latency, and sleep disturbance were also higher in the patient group compared with the control group. A family history of vitiligo was present in 18 (26.9%) patients. The most common type was acrofacial vitiligo, which was present in 29 (43.3%) patients. Conclusions: Increased probability levels of depression and impaired sleep quality in vitiligo patients suggest that psychiatric evaluation and treatment should be provided for vitiligo patients as a part of a multidisciplinary approach in order to increase the success of the treatment. Keywords: Vitiligo, depression, sleep quality

Evaluating prevalence of depression, anxiety and hopelessness in patients with Vitiligo on an Iranian population

INTRODUCTION

Vitiligo is caused by partial or complete destruction of melanocytes in the affected skin area and influences the patient's quality of life. Besides physical involvement, vitiligo patients experience a high level of stress. Depression and Anxiety are common psychiatric disorders in vitiligo patients.

AIM

This study, as the first study, evaluates hopelessness, anxiety, depression and general health of vitiligo patients in comparison with normal controls in an Iranian population.

METHOD

Hundred patients with vitiligo and hundred healthy controls were examined. General health, depression, hopelessness and anxiety were evaluated based on general health questionnaire. Anxiety, depression and hopelessness levels were analyzed using Chi-Square, and the mean value of general health was evaluated through t-test.

RESULTS

The results showed that anxiety and hopelessness levels were significantly higher in vitiligo patients than those who are in healthy controls. This significant difference refers to high levels of anxiety and hopelessness among women with vitiligo. It was also found that the single patients were more anxious, hopeless and depressive, while the married patients were only more anxious and hopeless than those who are in the control group, respectively. General health of patients was significantly worse than in healthy controls. The low level of general health in patients was related to poorer level of general health among women with vitiligo.

CONCLUSION

It seems that women with vitiligo are more mentally stressed than men with vitiligo. Both singles and married vitiligo patients suffer from anxiety and hopelessness.

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.

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.

Repigmentation in vitiligo universalis after starting dialysis-could they be related?

Vitiligo is an acquired disorder of pigmentation characterized by the development of white macules and patches on the skin. Although multiple theories have been proposed to understand the underlying pathophysiology behind the pigment loss, the exact etiology remains unknown. Vitiligo universalis is an extremely rare variant that causes nearly complete depigmentation of the entire body surface. Treatment is challenging, especially when pigment loss is generalized and diffuse. We present a unique case of a patient with vitiligo universalis that had remained untreated and stable for >20 years until she developed repigmentation shortly after initiation of dialysis.

Therapeutics of premature hair graying: A long journey ahead

Premature graying of hair has major psychosocial and socioeconomic repercussion, as it is considered as a sign of hastily progressing old age, ill health and often leads to loss of self-esteem. Hair is said to gray prematurely when it happens before the age of 20 years in Caucasians, 25 years in Asians, and 30 years in Africans. The hair color chiefly depends on melanin pigment, and fabrication of this pigment takes place in melanosomes through the process of melanogenesis. This complex biochemical pathway (melanogenesis) is further dependent on tyrosinase which acts as fuel.The normal human scalp is subjected to various factors categorized as intrinsic and extrinsic leading to graying of hair. Intrinsic factors comprise of variants responsible for changes at genetic level while extrinsic factors include air pollution, ultraviolet radiation, smoking, and nutrition. It has been proposed that direct or indirect effect of all these factors results in the generation of reactive oxygen species (ROS), thus leading to further damage. Though research has expanded in last few years in terms of microscopic, biochemical (hormonal, enzymatic), and molecular changes happening within hair follicle/shaft, still the exact mechanism leading to premature graying of hair is not well understood. Probable solutions toward this quandary are diet, herbal remedies, and temporary hair colorants. Ironically, the latter one being the most common has various side effects such as allergic reactions, inflammation, and hair loss. The aim of this paper was to review the manifestation and probable future interventions in preventing premature hair graying.

Therapeutic effects of iNOS inhibition against vitiligo in an animal model

Nitric oxide (NO) is involved in several biological processes, but its role in human melanogenesis and vitiligo need further studies. Previous studies revealed that exposure to UVA and UVB were capable of the inducing nitric oxide production in keratinocytes and melanocytes through the activation of constitutive nitric oxide synthase, whereas inducible nitric oxide synthase overexpression has been reported to play an important role in hyperpigmentary disorders. The aim of this study was to evaluate iNOS inhibitor aminoguanidine (AG) as a therapeutic agent in our mouse model of vitiligo. In this study, male C57BL/6J Ler-vit/vit mice were purchased to evaluate the effect of iNOS inhibitor (aminoguanidine) (50 and 100 mg/kg) and L-arginine (100 mg/kg) in a mouse model of vitiligo induced by monobenzone 40%. Moreover, we used phototherapy device to treat the mice with NBUVB as a gold standard.The findings revealed that monobenzone was capable of inducing depigmentation after 6 weeks. However, aminoguanidine in combination with monobenzone was decrease the effect of monobenzone, while L-arginine play a key role in promoting the effect of monobenzone (P<0.001). Based on the phototherapy, the efficacy of phototherapy significantly increased by adding L-arginine (P<0.05). Taken together, we suggest that iNOS inhibitor can be a novel treatment for the prevention and treatment of vitiligo by combination of NBUVB therapy, furthermore; NO agents like L-arginine could also increase the effectiveness of phototherapy. Taken together, this pilot study showed significant repigmentation of vitiligous lesions treated with iNOS inhibitor plus NBUVB therapy, where other aspect including expression of an inducible iNOS, NO and TNF levels remained to be evaluated in mice model.

Clinical differences between segmental nevus depigmentosus and segmental vitiligo

Segmental nevus depigmentosus and segmental vitiligo can be difficult to differentiate from each other. Differential diagnosis of these two diseases is important because they have significantly different prognoses and psychological effects. The purpose of this study is to identify clinical clues that may be helpful in differentiating these two diseases. We enrolled 63 patients with segmental nevus depigmentosus and 149 patients with segmental vitiligo. Sex, age of onset, sites involved, dermatomal distribution, margin of lesion and presence of poliosis were evaluated in both groups. The age of onset was less than 10 years in 96.8% of segmental nevus depigmentosus and 28.9% of segmental vitiligo cases. Trunk (36.5%) and cervical (38.1%) dermatomes were the most commonly involved in segmental nevus depigmentosus and face (67.1%) and trigeminal (64.4%) dermatomes in segmental vitiligo. The average number of dermatomes involved in truncal lesions was different in segmental nevus depigmentosus and segmental vitiligo (2.71 vs 1.62, P = 0.001). Segmental vitiligo on the face, neck and trunk appeared closer to the axis than segmental nevus depigmentosus (P < 0.001). Segmental nevus depigmentosus and segmental vitiligo showed significantly different margins (90.5% and 41.6% serrated, respectively; P < 0.001). We observed clinical differences between patients with segmental nevus depigmentosus and those with segmental vitiligo. Distribution (site, distance to axis, dermatome), vertical width, margin of lesion and presence of poliosis can be helpful in differentiating segmental nevus depigmentosus and segmental vitiligo.

The physiology of melanin deposition in health and disease

Eumelanin is the major pigment responsible for human skin color. This black/brown pigment is localized in membrane-bound organelles (melanosomes) found in specialized cells (melanocytes) in the basal layer of the epidermis. This review highlights the steps involved in melanogenesis in the epidermis and the disorders in skin pigmentation that occur when specific steps critical for this process are defective. Melanosomes, which contain tyrosinase, a major enzyme involved in melanin synthesis, develop through a series of steps in the melanocyte. They are donated from the melanocyte dendrites to the surrounding keratinocytes in the epidermis. In the keratinocytes, the melanosomes are found singly or packaged into groups, and as the keratinocytes move upward in the epidermis, the melanosomes start to degrade. This sequence of events is critical for melanin pigmentation in the skin and can be influenced by genetic, hormonal, and environmental factors, which all play a role in levels of melanization of the epidermis. The effects these factors have on skin pigmentation can be due to different underlying mechanisms involved in the melanization process leading to either hypo- or hyperpigmentary disorders. These disorders highlight the importance of mechanistic studies on the specific steps involved in the melanization process.

Plasma & urinary catecholamines & urinary vanillylmandelic acid levels in patients with generalized vitiligo

Background & objectives

Vitiligo is an acquired skin disease characterized by depigmented areas of the skin. Increased release of catecholamines from autonomic nerve endings in microenvironment of melanocytes in affected skin might be involved in the aetiopathogenesis of vitiligo. Levels of catecholamines are considered as being related to onset or worsening of the disease. Therefore, in this study, the role of catecholamines was evaluated in mapping disease stability and outcome of vitiligo patients undergoing melanocyte transfer.

Methods

In this study, circulatory and urinary levels of catecholamine (CA) and vanillylmandelic acid (VMA) were determined in 45 individuals (30 vitiligo patients and 15 healthy controls) using ELISA.

Results

A significant increase for plasma and urinary catecholamines along with VMA was observed as compared to healthy controls. When the pre- and post-intervention levels were analyzed in responders and non-responders, respectively, only dopamine showed significant decline in urine, rest of the molecules in plasma as well as urine showed non-significant decline except VMA which showed insignificant increase.

Interpretation & conclusions

Levels of plasma/urinary epinephrine, and plasma dopamine, could not be established as biomarkers for disease stability or successful outcome of autologous melanocyte transfer in generalized vitiligo patients. However, dopamine (urine) might be of help in determining the stability in patients with generalized vitiligo undergoing melanocyte transfer. Further studies need to be done on a large sample of patients to confirm our findings.

Lymphoid Stress Surveillance Response Contributes to Vitiligo Pathogenesis

Vitiligo is a chronic multifactorial depigmentation disorder characterized by the destruction and functional loss of melanocytes. Although a direct cytotoxic T cell attack is thought to be responsible for melanocyte damage, the events leading to the loss of self-tolerance toward melanocytic antigens are not understood. This research aimed to identify novel cellular and molecular factors that participate in vitiligo pathogenesis through the application of gene expression and immunofluorescence analysis of skin biopsy samples along with immunophenotyping of circulating cells. Our study provides insights into the mechanisms involved in melanocyte destruction. The upregulation of stress-ligand MICA/MICB, recognized by activating receptors on innate and innate-like T cells, imply involvement of lymphoid stress surveillance responses in vitiligo lesions. A simultaneous increase in the expression of transcription factor EOMES that is characteristic for innate-like virtual memory T cells, suggest a similar scenario. Local lymphoid stress surveillance has been previously associated with the amplification of systemic humoral responses that were mirrored in our study by increased T follicular helper cells and switched memory B cell proportions in patients with active vitiligo. In addition, microtubule-associated protein light chain 3 staining was compatible with the activation of autophagy in keratinocytes and in the remaining melanocytes of vitiligo lesional skin.

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.

Regulation of melanocyte stem cell behavior by the niche microenvironment

Somatic stem cells are regulated by their niches to maintain tissue homeostasis and repair throughout the lifetime of an organism. An excellent example to study stem cell/niche interactions is provided by the regeneration of melanocytes during the hair cycle and in response to various types of injury. These processes are regulated by neighboring stem cells and multiple signaling pathways, including WNT/β-catenin, KITL/KIT, EDNs/EDNRB, TGF-β/TGF-βR, α-MSH/MC1R, and Notch signaling. In this review, we highlight recent studies that have advanced our understanding of the molecular crosstalk between melanocyte stem cells and their neighboring cells, which collectively form the niche microenvironment, and we focus on the question of how McSCs/niche interactions shape the responses to genotoxic damages and mechanical injury.

The early repigmentation pattern of vitiligo is related to the source of melanocytes and by the choice of therapy: a retrospective cohort study

BACKGROUND

Patients with vitiligo present with different repigmentation patterns in the early recovery stage.

OBJECTIVES

To analyze the relationships between early repigmentation patterns in vitiliginous patches, their clinical characteristics, and therapeutic choices.

METHODS

Patients with vitiligo seen in the Department of Dermatology, The First Affiliated Hospital of Nanjing Medical University from 2010 to 2015, were included, and their clinical records, especially photographs and medical treatments, were reviewed.

RESULTS

One hundred and sixteen patients were included in this study, and 326 lesions with different degrees of depigmentation, locations, stages, distributions, therapies, and repigmentation patterns were included and analyzed. Perifollicular repigmentation occurred more frequently in lesions with complete depigmentation (P = 0.005), in non-sun exposed areas (P < 0.001), a stable stage (P = 0.008), and lesions treated with narrow band ultraviolet B (NB-UVB) (P < 0.001, despite lesion distributions). Marginal repigmentation is more frequent in lesions with complete depigmentation (P = 0.016), lesions treated without NB-UVB (P = 0.002), and facial lesions treated with topical vitamin D analogs (TVDAs) monotherapy (P = 0.022). Diffuse repigmentation is the predominant pattern in lesions with incomplete depigmentation (P < 0.001), in sun-exposed areas (P < 0.001), progressive stage (P = 0.044), and truncal lesions treated with TVDAs (P < 0.001).

CONCLUSIONS

The different repigmentation patterns of vitiligo lesions depend on the different source and status of melanocytes and their abilities to produce melanin on the choice of therapy.

Differential Expression of Nitric Oxide Synthase Isoforms nNOS and iNOS in Patients with Non-Segmental Generalized Vitiligo

Nitric oxide (NO) is involved in several biological processes, but its role in human melanogenesis is still not well understood. Exposure to UVA and UVB induces nitric oxide production in keratinocytes and melanocytes through the activation of constitutive nitric oxide synthase, increasing tyrosinase activity and melanin synthesis, whereas inducible nitric oxide synthase over expression might be involved in hypopigmentary disorders. The aim of this study was to evaluate whether inducible nitric oxide synthase and neuronal nitric oxide synthase expression were modified in vitiligo skin compared to healthy controls. Skin biopsies were obtained from inflammatory/lesional and white/lesional skin in 12 patients with active, non-segmental vitiligo; site-matched biopsies of normal skin from eight patients were used as controls. Nitric oxide synthase isoforms expression was evaluated by confocal laser scanning microscopy and Western Blot analysis. Inducible nitric oxide synthase expression was significantly increased in inflammatory/lesional skin compared to healthy skin; melanocytes showed a moderate neuronal nitric oxide synthase expression in white/lesional skin, demonstrating that metabolic function still goes on. The obtained data demonstrated that vitiligo lesions were characterized by modifications of nitric oxide synthase isoforms, thus confirming the hypothesis that nitric oxide imbalance is involved in vitiligo and supporting the idea that nitric oxide synthase inhibitors might be used as a possible therapeutic approach for the management of vitiligo.

Repigmentation in vitiligo: position paper of the Vitiligo Global Issues Consensus Conference

The Vitiligo Global Issues Consensus Conference (VGICC), through an international e-Delphi consensus, concluded that 'repigmentation' and 'maintenance of gained repigmentation' are essential core outcome measures in future vitiligo trials. This VGICC position paper addresses these core topics in two sections and includes an atlas depicting vitiligo repigmentation patterns and color match. The first section delineates mechanisms and characteristics of vitiligo repigmentation, and the second section summarizes the outcomes of international meeting discussions and two e-surveys on vitiligo repigmentation, which had been carried out over 3 yr. Treatment is defined as successful if repigmentation exceeds 80% and at least 80% of the gained repigmentation is maintained for over 6 months. No agreement was found on the best outcome measure for assessing target or global repigmentation, therefore highlighting the limitations of e-surveys in addressing clinical measurements. Until there is a clear consensus, existing tools should be selected according to the specific needs of each study. A workshop will be conducted to address the remaining issues so as to achieve a consensus.

Vitiligo and depression: a systematic review and meta-analysis of observational studies

Vitiligo is a common depigmenting disorder with profound psychosocial impacts. Previous observational studies have suggested a link between vitiligo and psychiatric morbidity, such as depression. However, variability in study design makes it difficult to quantify accurately the relationship between vitiligo and depression. We aimed to investigate the underlying prevalence and risk of depression among patients with vitiligo. A comprehensive search of MEDLINE, Embase and the Cochrane Library was conducted. Cross-sectional, case-control or cohort studies that assessed the prevalence of depression among patients with vitiligo or the relationship between vitiligo and depression were included. DerSimonian and Laird random-effects models were utilized to calculate the pooled prevalence and relative risks. Publication bias was evaluated by funnel plots and Egger's tests. Twenty-five studies with 2708 cases of vitiligo were included. Based on diagnostic codes, the pooled prevalence of depression among patients with vitiligo was 0·253 [95% confidence interval (CI) 0·16-0·34; P < 0·001)]. Using self-reported questionnaires, the pooled prevalence of depressive symptoms was 0·336 (95% CI 0·25-0·42; P < 0·001). The pooled odds ratio of depression among patients with vitiligo was 5·05 vs. controls (95% CI 2·21-11·51; P < 0·001). Moderate-to-high heterogeneity was observed between the studies. Patients with vitiligo were significantly more likely to suffer from depression. Clinical depression or depressive symptoms can be prevalent, with the actual prevalence differing depending on screening instruments or, possibly, geographical regions. Clinicians should actively evaluate patients with vitiligo for signs/symptoms of depression and provide appropriate referrals to manage their psychiatric symptoms accordingly.

Epidermal hydrogen peroxide is not increased in lesional and non-lesional skin of vitiligo

It is widely believed that the loss of the epidermal melanocytes in vitiligo is basically due to excessive oxidative stress. Previous research work described abnormal elevation of the absolute concentration of the epidermal hydrogen peroxide (H₂O₂) in lesional and non-lesional skin of vitiligo. Based on this finding, our primary research objective was to use this feature as a screening marker in individuals at a great risk of developing vitiligo. Ninety-six patients of non-segmental vitiligo (NSV) of varying durations, skin phototypes, and treatment modalities (psoralen UVA-, narrow band UVB-treated) were recruited for this study. Raman spectroscopic measurements, using an external probehead, of the lesional and non-lesional skin were obtained, and the resulting spectra were analyzed using the Opus software package of the MultiRam spectrometer and the intensity of the peak at 875 cm^-1 that represents the absolute concentration of H₂O₂ was calculated. Contrary to previous reports, in patients of skin phototype IV, the absolute concentrations of H₂O₂ in non-lesional and lesional NSV of all groups were non-significantly decreased compared to normal control. In patients of NSV of skin phototype V, the decrease in the absolute concentrations of H₂O₂ was not significant in the untreated group, and a slight non-significant increase in the NBUVB-treated group was noted. However, in the PUVA-treated group, the non-lesional skin demonstrated significant increase in the absolute concentration of H₂O₂, whereas the lesional skin showed only a slight non-significant increase compared to normal control. In NSV patients of skin phototype VI who were previously treated with PUVA, the non-lesional skin showed a slight non-significant increase in the absolute concentration of H₂O₂; however, the lesional skin showed a marked significant decrease compared to normal control and the non-lesional skin. Thereof, one can conclude that the epidermal H₂O₂ is not increased in NSV as previously thought and may not be responsible for the oxidative stress that leads to the melanocytes destruction, the hallmark of vitiligo pathogenesis.

Repigmentation patterns induced by NB-UVB and their relationship with melanocytic migration and proliferation in vitiligo

BACKGROUND/PURPOSE

Vitiligo is the most commonly acquired depigmentation disorder of the skin and is characterized by the destruction of melanocytes. Ultraviolet phototherapy with narrow band (UVB-NB) induces proliferation, differentiation, maturation, and migration of melanocytes. The clinical repigmentation is featured by follicular, marginal, and diffuse patterns. The aim of this study was to observe the process involved in the melanocyte migration and proliferation among these patterns and the unresponsive lesions following UVB-NB phototherapy. The focal adhesion kinase (FAK) and c-KIT were used as markers of melanocyte migration and differentiation, respectively.

METHODS

A total of 17 vitiligo patients under UVB-NB therapy were selected. The patients expressed the three repigmentation patterns as well as unresponsive lesions at the conclusion of a 30-session cycle. Skin biopsies were evaluated by immunohistochemistry and qRT-PCR.

RESULTS

We found an increased expression of c-KIT in the follicular pattern compared to the diffuse pattern that was expressed predominantly of FAK. Marginal pattern expressed both proteins. The unresponsive achromic lesions showed poor expressions of both markers.

CONCLUSION

Proliferation was prominent in the follicular pattern, but migration was prominent in the diffuse pattern. For the marginal pattern, both dynamics were present. The absence of these markers in vitiligo lesions suggests a lack of response to UVB-NB.

Vitiligo - The story from within: A transmission electron microscopic study before and after narrow-band ultraviolet B

Melanocyte loss is the main feature of vitiligo, but evidence refers to pathological multiplayers. Transmission electron microscopy was utilized to further explore vitiligo before and after narrow-band ultraviolet B (NB-UVB) therapy. Skin biopsies were retrieved from lesional and perilesional skin and compared to normal control skin. Sections were examined for melanocytes and keratinocytes and the number of melanosomes and thickness of basal lamina were measured. In lesional skin, keratinocytes revealed two types of degeneration with a significant increase in the mean thickness of basal lamina and decrease in the number of melanosomes. After treatment, lesional and perilesional skin showed variable ultrastructural features.

Clinical repigmentation patterns in paediatric vitiligo

BACKGROUND

Repigmentation is an essential outcome measure in vitiligo. However, clinical studies describing vitiligo repigmentation patterns are lacking.

OBJECTIVES

To assess and clearly define the repigmentation patterns in a series of patients with vitiligo, correlating these with clinicoepidemiological characteristics.

METHODS

Patients with vitiligo seen at least at twice (initial consultation and follow-up visit) in the Department of Paediatric Dermatology, Hôpital Pellegrin des Enfants, Bordeaux University Hospital from 2006 to 2014 were included. Clinical photographs and case records were reviewed.

RESULTS

There were 109 patients (64 female, 45 male) mostly with Fitzpatrick skin type III (n = 67, 61%). The majority had nonsegmental (n = 71, 65%) or segmental vitiligo (n = 29, 27%). In total 172 representative vitiligo lesions were analysed. Overall, a combined pattern of repigmentation was most commonly seen (n = 106, 62%). The combined pattern occurred more frequently in patients with segmental vs. nonsegmental vitiligo (P = 0·009), whereas the diffuse pattern was more frequent in the latter (P = 0·007). Diffuse repigmentation was the predominant pattern on the eyelids (P < 0·001). We observed a new pattern in sites with few to absent hair follicles, which we propose to call 'medium spotted repigmentation'. This begins as circular macules of repigmentation, wider than 5 mm in diameter, which, from the outset, are larger than the initial macules of perifollicular repigmentation. This study is limited by its retrospective nature and small sample size for subgroup assessment.

CONCLUSIONS

The combined pattern of repigmentation was most frequently observed. Medium spotted repigmentation is a new pattern, which will benefit from larger studies for a better understanding.

Oxidative stress-induced overexpression of miR-25: the mechanism underlying the degeneration of melanocytes in vitiligo

Oxidative stress has a critical role in the pathogenesis of vitiligo. However, the specific molecular mechanism involved in oxidative stress-induced melanocyte death is not well characterized. Given the powerful role of microRNAs (miRNAs) in the regulation of cell survival as well as the fact that the generation of miRNAs can be affected by oxidative stress, we hypothesized that miRNAs may participate in vitiligo pathogenesis by modulating the expression of vital genes in melanocytes. In the present study, we initially found that miR-25 was increased in both serum and lesion samples from vitiligo patients, and its serum level was correlated with the activity of vitiligo. Moreover, restoration of miR-25 promoted the H2O2-induced melanocyte destruction and led to the dysfunction of melanocytes. Further experiments proved that MITF, a master regulator in melanocyte survival and function, accounted for the miR-25-caused damaging impact on melanocytes. Notably, other than the direct role on melanocytes, we observed that miR-25 inhibited the production and secretion of SCF and bFGF from keratinocytes, thus impairing their paracrine protective effect on the survival of melanocytes under oxidative stress. At last, we verified that oxidative stress could induce the overexpression of miR-25 in both melanocytes and keratinocytes possibly by demethylating the promoter region of miR-25. Taken together, our study demonstrates that oxidative stress-induced overexpression of miR-25 in vitiligo has a crucial role in promoting the degeneration of melanocytes by not only suppressing MITF in melanocytes but also impairing the paracrine protective effect of keratinocytes. Therefore, it is worthy to investigate the possibility of miR-25 as a potential drug target for anti-oxidative therapy in vitiligo.

Vitiligo--Part 2--classification, histopathology and treatment

In an unprecedented effort in the field of vitiligo, a global consensus resulted on a suggested new classification protocol for the disease. The main histopathological finding in vitiligo is the total absence of functioning melanocytes in the lesions, while the inflammatory cells most commonly found on the edges of the lesions are CD4+ and CD8+ T lymphocytes. Physical and pharmacological treatment strategies aim to control the autoimmune damage and stimulate melanocyte migration from the unaffected edges of lesions and the outer hair follicle root sheath to the affected skin; moreover, surgical treatments can be combined with topical and physical treatments.

Blood supply--susceptible formation of melanin pigment in hair bulb melanocytes of mice

BACKGROUND

Allogeneic skin grafts onto C57BL/6 mice are rejected, and the rejected skin is replaced by surrounding skin with black hair. In contrast, syngeneic skin grafts are tolerated, and gray hair grows on the grafts.

METHODS

To explore the mechanism of gray hair growing on the tolerated skin grafts, we prepared full-thickness skin (2-cm square) autografts, 2 (2 cm + 2 cm) horizontal or vertical parallel incisions, and U-shaped (2 cm × 2 cm × 2 cm) flaps with or without pedicle vessels. The grafts, incisions, and flaps were fixed by suturing with string and protected by a transparent bandage. On day 14 after the operation, the bandages were removed to observe the color of the hair growing on the skin.

RESULTS

Skin autografts from wild-type or hepatocyte growth factor-transgenic (Tg) C57BL/6 mice survived with gray hair, whereas those from steel factor (Kitl)-Tg C57BL/6 mice survived with black hair. In addition, U-shaped flaps lacking both of the 2 main feeding vessels of wild-type mice had gray hair at the tip of the flaps. Light microscopy after staining with hematoxylin and eosin or dihydroxyphenylalanine showed that the formation of melanin pigment in the follicles, but not in the interadnexal skin, was susceptible to the blood supply.

CONCLUSIONS

Melanin pigment formation in the hair bulb melanocytes appeared to be susceptible to the blood supply, and melanocytosis was promoted in the follicles and in the epidermis of Kitl-Tg C57BL/6 mice.

Beyond vitiligo guidelines: combined stratified/personalized approaches for the vitiligo patient

'Vitiligo' is a word that bears endless possibilities and no promises. Each vitiligo patient has a different story that demands a different therapeutic approach. Even though great efforts have been made to evaluate, study, compare and document the different therapeutic modalities available for vitiligo, clearly handling their modes of actions as well as their side effects and establishing clear stratified guidelines, numerous dilemmas are frequently met on practical grounds. 'Stabilize', 'repigment', 'depigment' or 'camouflage'? 'for whom and how do we achieve the best results' ? 'Separately or in combination ? - questions that need to be answered and decisions need to be taken in the appropriate timing and altered when the necessity arises. In the current viewpoint, we have utilized the available knowledge and exploited years of experience in an attempt to go beyond the guidelines to set the rationale for an optimal and personalized therapy, within the framework of a stratified approach.

A comparative study of mitochondrial ultrastructure in melanocytes from perilesional vitiligo skin and perilesional halo nevi skin

Vitiligo and halo nevi are both pigmentary disorders of the skin characterized by the acquired loss of functional epidermal melanocytes manifesting as white macules and patches. The cellular mechanism(s) and biochemical changes that result in the appearance of these two types of achromic lesions are still uncertain; and the relationship between vitiligo and halo nevi has been in dispute. In this study, we investigated the ultrastructure of mitochondria in melanocytes and in keratinocytes from perilesional vitiligo skin and from perilesional halo nevi skin using Transmission Electron Microscopy. Furthermore, we performed a quantitative analysis of mitochondrial morphology through a stereological study. As previously reported, we found that melanocytes from perilesional active vitiligo skin were loosely connected with their surroundings by their retracted dendrites. The surface density and the volume density of mitochondria in melanocytes and in keratinocytes from perilesional vitiligo skin are increased significantly compared with the controls, especially in active vitiligo. In contrast, there are no significant differences in mitochondria in melanocytes and in keratinocytes from perilesional halo nevi skin compared with the controls. In summary, the tendency of different morphologic alterations in mitochondria from perilesional vitiligo skin and from perilesional halo nevi skin reflect heterogeneous backgrounds between the two diseases, revealing that vitiligo and halo nevi may have separate pathogenic mechanisms. These findings may help elucidate the relationship of these two diseases and their underlying mechanisms.