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

The underestimated role of mitochondria in vitiligo: From oxidative stress to inflammation and cell death

Vitiligo is an acquired depigmentary disorder characterized by the depletion of melanocytes in the skin. Mitochondria shoulder multiple functions in cells, such as production of ATP, maintenance of redox balance, initiation of inflammation and regulation of cell death. Increasing evidence has implicated the involvement of mitochondria in the pathogenesis of vitiligo. Mitochondria alteration will cause the abnormalities of mitochondria functions mentioned above, ultimately leading to melanocyte loss through various cell death modes. Nuclear factor erythroid 2-related factor 2 (Nrf2) plays a critical role in mitochondrial homeostasis, and the downregulation of Nrf2 in vitiligo may correlate with mitochondria damage, making both mitochondria and Nrf2 promising targets in treatment of vitiligo. In this review, we aim to discuss the alterations of mitochondria and its role in the pathogenesis of vitiligo.

Mitophagy and immune infiltration in vitiligo: evidence from bioinformatics analysis

Background

Vitiligo is an acquired, autoimmune, depigmented skin disease with unclear pathogenesis. Mitochondrial dysfunction contributes significantly to vitiligo, and mitophagy is vital for removing damaged mitochondria. Herein, using bioinformatic analysis, we sought to determine the possible role of mitophagy-associated genes in vitiligo and immune infiltration.

Methods

Microarrays GSE53146 and GSE75819 were used to identify differentially expressed genes (DEGs) in vitiligo. By crossing vitiligo DEGs with mitophagy-related genes, the mitophagy-related DEGs were identified. Functional enrichment and protein-protein intersection (PPI) analyses were conducted. Then, the hub genes were identified using two machine algorithms, and receiver operating characteristic (ROC) curves were generated. Next, the immune infiltration and its connection with hub genes in vitiligo were investigated. Finally, the Regnetwork database and NetworkAnalyst were used to predict the upstream transcriptional factors (TFs), microRNAs (miRNAs), and the protein-compound network.

Results

A total of 24 mitophagy-related genes were screened. Then, five mitophagy hub genes (GABARAPL2, SP1, USP8, RELA, and TBC1D17) were identified using two machine learning algorithms, and these genes showed high diagnostic specificity for vitiligo. The PPI network showed that hub genes interacted with each other. The mRNA expression levels of five hub genes were validated in vitiligo lesions by qRT-PCR and were compatible with the bioinformatic results. Compared with controls, the abundance of activated CD4⁺ T cells, CD8⁺ T cells, immature dendritic cells and B cells, myeloid-derived suppressor cells (MDSCs), gamma delta T cells, mast cells, regulatory T cells (Tregs), and T helper 2 (Th2) cells was higher. However, the abundance of CD56 bright natural killer (NK) cells, monocytes, and NK cells was lower. Correlation analysis revealed a link between hub genes and immune infiltration. Meanwhile, we predicted the upstream TFs and miRNAs and the target compounds of hub genes.

Conclusion

Five hub mitophagy-related genes were identified and correlated with immune infiltration in vitiligo. These findings suggested that mitophagy may promote the development of vitiligo by activating immune infiltration. Our study might enhance our comprehension of the pathogenic mechanism of vitiligo and offer a treatment option for vitiligo.

Potential Role of Chronic Physical Exercise as a Treatment in the Development of Vitiligo

Vitiligo is an autoimmune disease characterized by progressive skin depigmentation and the appearance of white patches throughout the body caused by significant apoptosis of epidermal melanocytes. Despite not causing any physical pain, vitiligo can originate several psychosocial disorders, drastically reducing patients' quality of life. Emerging evidence has shown that vitiligo is associated with several genetic polymorphisms related to auto-reactivity from the immune system to melanocytes. Melanocytes from vitiligo patients suffer from excess reactive oxygen species (ROS) produced by defective mitochondria besides a poor endogenous antioxidant system (EAS). This redox imbalance results in dramatic melanocyte oxidative stress (OS), causing significant damage in proteins, lipid membranes, and DNA. The damaged melanocytes secret damage-associated molecular pattern (DAMPs), inducing and increasing inflammatory gene expression response that ultimately leads to melanocytes apoptosis. Vitiligo severity has been also associated with increasing the prevalence and incidence of metabolic syndrome (MetS) or associated disorders such as insulin resistance and hypercholesterolemia. Thus, suggesting that in genetically predisposed individuals, the environmental context that triggers MetS (i.e., sedentary lifestyle) may also be an important trigger for the development and severity of vitiligo disease. This paper will discuss the relationship between the immune system and epidermal melanocytes and their interplay with the redox system. Based on state-of-the-art evidence from the vitiligo research, physical exercise (PE) immunology, and redox system literature, we will also propose chronic PE as a potential therapeutic strategy to treat and prevent vitiligo disease progression. We will present evidence that chronic PE can change the balance of inflammatory to an anti-inflammatory state, improve both EAS and the mitochondrial structure and function (resulting in the decrease of OS). Finally, we will highlight clinically relevant markers that can be analyzed in a new research avenue to test the potential applicability of chronic PE in vitiligo disease.

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.

Transcriptome Analysis Reveals the Molecular Immunological Characteristics of Lesions in Patients with Halo Nevi When Compared to Stable Vitiligo, Normal Nevocytic Nevi and Cutaneous Melanoma

Background

Given their similar appearance and histology, halo nevi (HN) were considered as a type of vitiligo. However, whether HN have stronger immune response than stable vitiligo (VL) remains unclear. In addition, the molecular alterations in HN compared with normal nevocytic nevi (NN) and primary cutaneous melanoma (MM) must be determined. This study aimed to systematically characterize the molecular immunological features of HN.

Methods

Skin samples from patients with HN, VL, NN, and MM were obtained with informed consent. Each of the four groups underwent transcriptome sequencing and data analysis were for pairwise comparison. Quantitative real-time PCR (RT-qPCR) was conducted to confirm the transcriptional expression of some differentially expressed genes (DEGs) that were closely related to immunity.

Results

A total of 441 and 1507 DEGs were found in the HN/NN and HN/MM groups, respectively. Compared with those of VL, HN lesions contained 162 up-regulated DEGs and 12 down-regulated DEGs. Bioinformatics analysis showed that the up-regulated genes in HN were substantially enriched in immune response, immune deficiency, and immune rejection; biological stimulation (virus, bacteria); and proliferation and activation of immune cells. Immune cell composition analysis also confirmed high expression levels of multiple immunocytes in HN.

Conclusion

The molecular immune mechanisms of HN and VL were similar, but the immune activity of HN was stronger than that of VL. Innate and adaptive immunity were involved in the pathogenesis and progression of HN and VL.

RIP1-Mediated Necroptosis Facilitates Oxidative Stress‒Induced Melanocyte Death, Offering Insight into Vitiligo

Vitiligo is a common depigmentation disease characterized by melanocyte death, which is attributed to various mechanisms such as apoptosis and autoimmune destruction. However, whether necroptosis, a newly discovered way of cell death, plays a key role in the pathogenesis of vitiligo is still elusive and has not been well-studied. In this study, we found that necroptosis markers, including phosphorylated RIP3 and phosphorylated-MLKL, were positive in melanocytes from vitiligo perilesional skins, which supported the existence of necroptosis in vitiligo. Furthermore, the expression of RIP1 was remarkably upregulated in melanocytes treated with hydrogen peroxide. Then, RIP1 intervention suppression and MLKL deficiency could significantly enhance the resistance of melanocytes to hydrogen peroxide‒induced necroptosis. Mechanistically, we confirmed that RIP1 and RIP3 could form necrosomes under oxidative stress and further trigger phosphorylated MLKL translocation to the cell membrane, which led to the destruction of melanocytes. Finally, we showed that RIP1-mediated generation of mitochondrial ROS contributed to necrosome formation in melanocytes. Collectively, our study confirms that necroptosis significantly facilitates oxidative stress‒induced melanocyte death through the RIP1 signaling pathway, offering insight into vitiligo.

Anti-inflammatory and neuroprotective effects of natural cordycepin in rotenone-induced PD models through inhibiting Drp1-mediated mitochondrial fission

Accumulating evidences suggest that inflammation-mediated neurons dysfunction participates in the initial and development of Parkinson's disease (PD), whereas mitochondria have been recently recognized as crucial regulators in NLRP3 inflammasome activation. Cordycepin, a major component of cordyceps militaris, has been shown to possess neuroprotective and anti-inflammatory activity. However, the effects of cordycepin in rotenone-induced PD models and the possible mechanisms are still not fully understood. Here, we observed that motor dysfunction and dopaminergic neurons loss induced by rotenone exposure were ameliorated by cordycepin. Cordycepin also reversed Drp1-mediated aberrant mitochondrial fragmentation through increasing AMPK phosphorylation and maintained normal mitochondrial morphology. Additionally, cordycepin effectively increased adenosine 5'-triphosphate (ATP) content, mitochondrial membrane potential (MMP), and reduced mitochondrial ROS levels, as well as inhibited complex 1 activity. More importantly, cordycepin administration inhibited the expression of NLRP3 inflammasome components and the release of pro-inflammatory cytokine in rotenone-induced rats and cultured neuronal PC12 cells. Moreover, we demonstrated that the activation of NLRP3 inflammasome within neurons could be suppressed by the mitochondrial division inhibitor (Mdivi-1). Collectively, the present study provides evidence that cordycepin exerts neuroprotective effects partially through preventing neural NLRP3 inflammasome activation induced by Drp1-dependent mitochondrial fragmentation in rotenone-injected PD models.

Molecular Hydrogen Protects Human Melanocytes from Oxidative Stress by Activating Nrf2 Signaling

Oxidative stress is proven to be critical for the initiation and progression of vitiligo. Molecular hydrogen (H₂) possesses potent antioxidant activity and has been shown to protect against various oxidative stress-related diseases. In this study, we first investigated the effects and mechanisms of H₂ in human melanocytes damaged by hydrogen peroxide. We initially found that H₂ reduced intracellular ROS accumulation and malondialdehyde levels in both vitiligo specimens and hydrogen peroxide-treated melanocytes in vitro in a concentration- and time-dependent manner, concomitant with the enhancement of antioxidant enzyme activity. Correspondingly, H₂ reversed hydrogen peroxide-induced apoptosis and dysfunction in both normal and vitiligo melanocytes. H₂ protected mitochondrial morphology and function in melanocytes under stress and promoted the activation of Nrf2 signaling, whereas Nrf2 deficiency abolished the protective effect of H₂ against hydrogen peroxide-induced oxidative damage. Furthermore, H₂ positively modulated β-catenin in hydrogen peroxide-treated melanocytes, and the β-catenin pathway was implicated in H₂-induced Nrf2 activation. Collectively, our results indicate that H₂ could be a promising therapeutic agent for vitiligo treatment via attenuating oxidative damage, and its beneficial effect in human melanocytes might involve Wnt/β-catenin-mediated activation of Nrf2 signaling.

Suppression of FADS1 induces ROS generation, cell cycle arrest, and apoptosis in melanocytes: implications for vitiligo

Vitiligo is a potentially serious condition characterized by loss of melanin and death of melanocytes. To identify potential therapeutic targets for vitiligo, we conducted a microarray analysis of three human vitiligo specimens and paired adjacent normal tissues. Because we found that the fatty acid desaturase 1 (FADS1) gene was downregulated in vitiligo specimens, we carried out experiments to assess its role in melanocyte replication and survival. RT-qPCR was used to verify that FADS1 expression was lower in vitiligo-affected tissues and vitiligo melanocyte PIG3V cells than in matched controls or normal human epidermal PIG1 melanocytes. In addition, CCK-8, immunofluorescence, western blot and flow cytometry assay were used to detect the proliferation and apoptosis in PIG1 cells respectively. Overexpression of FADS1 promoted proliferation of PIG3V melanocytes, while FADS1 silencing inhibited proliferation and induced cell death in PIG1 melanocytes. Increased ROS generation; induction of mitochondrial-mediated apoptosis via upregulation of Bax and active caspases 3 and 9 and downregulation of Bcl-2; and cell cycle arrest via downregulation of c-Myc and Cyclin D1 and upregulation of p21 were all enhanced after FADS1 silencing in PIG1 melanocytes. These findings implicate FADS1 downregulation in the pathogenesis of vitiligo and may open new avenues for its treatment.

Andrographolide alleviates Parkinsonism in MPTP-PD mice via targeting mitochondrial fission mediated by dynamin-related protein 1

BACKGROUND AND PURPOSE

Accumulating evidence indicates that mitochondrial dynamics play an important role in the progressive deterioration of dopaminergic neurons. Andrographolide has been found to exert neuroprotective effects in several models of neurological diseases. However, the mechanism of how andrographolide protects neurons in Parkinson's disease (PD) remains not fully understood.

EXPERIMENTAL APPROACH

Behavioural experiments were performed to examine the effect of andrographolide in 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-PD mice. Mitochondrial mass and morphology were visualized using transmission electron microscopy (TEM). SH-SY5Y cells and primary mouse neurons were exposed to rotenone to mimic PD in vitro. Western blotting, co-immunoprecipitation and immunofluorescence were performed. The target protein of andrographolide was identified by biotin-andrographolide pulldown assay as well as drug affinity responsive target stability (DARTS), cellular thermal shift (CETSA), and surface plasmon resonance (SPR) assays.

KEY RESULTS

Andrographolide administration improved behavioural deficits and attenuated loss of dopaminergic neurons in MPTP-exposed mice and reduced cell death induced by rotenone in vitro. An increased mitochondrial mass, and decreased surface area were found in the striatum from MPTP-PD mice, as well as in rotenone-treated primary neurons and SH-SY5Y cells, while andrographolide treatment preserved mitochondrial mass and morphology. Dynamin-related protein 1 (DRP1) was identified as a target protein of andrographolide. Andrographolide bound to DRP1 and inhibited its GTPase activity, thereby preventing excessive mitochondria fission and neuronal damage in PD.

CONCLUSIONS AND IMPLICATIONS

Our findings suggest that andrographolide may protect neurons against rotenone- or MPTP-induced damage in vitro and in vivo through inhibiting mitochondrial fission.

Efficacy of 308-nm Monochromatic Excimer Light in the Management of Halo Nevi: An Open-Label, Pilot Study

Introduction:

Halo nevus (HN) affects approximately 1% of the population. Presence of hypo- or depigmented lesion carries tremendous psychosocial disturbance in the mind-set of population in the Indian subcontinent. Hence, HN requires intervention by any modalities. Here authors attempted to evaluate the efficacy of monochromatic excimer light (MEL) in treating HN.

Materials and Methods:

A total of 29 patients with HN were included in the study. A xenon chloride lamp emitting noncoherent, monochromatic 308-nm light that represents the natural evolution of the excimer laser was used. The initial dose was 100 mJ/cm², which was increased by 100 mJ/cm² per session. All the patients were followed up for 6 months.

Results:

A total of 29 patients with 10 males and 19 females (male to female ratio of 1:1.9) completed the study. The age of onset of HN ranged from 5 to 47 years and the mean age of the patients was 23 years. HN was seen on the face, back, neck, chest, trunk, and extremities in 5 (17.2%), 6 (20.7%), 4 (13.7%), and 6 (20.7%) patients, respectively. Outstanding response was noticed in 14 patients (48.2%), whereas 6 (20.6%) patients showed excellent improvement. Only 2 (6.8%) patients showed no response after 10 consecutive sessions.

Conclusion:

HN causes apprehension in the Indian population because of the social stigma associated with depigmented patches on the body. Mere observation and only counseling in the treatment protocol are not sufficient. MEL is a noninvasive procedure, which results in excellent repigmentation of HN without scarring.

Baicalein protects human vitiligo melanocytes from oxidative stress through activation of NF-E2-related factor2 (Nrf2) signaling pathway

Vitiligo is a complex disorder characterized by patchy loss of skin pigmentation due to abnormal melanocyte function. Overwhelming evidences have suggested that oxidative stress plays a major role in the loss of melanocytes thereby mediating the onset and progression of vitiligo. The nuclear factor erythroid 2-like factor 2 (Nrf2) is a master regulator of cellular redox homeostasis and the activation of Nrf2 signaling pathway is impaired in the vitiligo melanocytes. Baicalein, as flavonoid extracted from the Scutellaria baicalensis, has been proved to possess the ability to activate Nrf2 signaling pathway in other cell types and mouse model. Our previous data found that baicalein exerts a cytoprotective role in H₂O₂-induced apoptosis in human melanocytes cell line (PIG1). Based on these founding, we hypothesized that baicalein activates Nrf2 signaling pathway, alleviates H₂O₂-induced mitochondrial dysfunction and cellular damage, thereby protecting human vitiligo melanocytes from oxidative stress. In the present study, we found that baicalein effectively inhibited H₂O₂-induced cytotoxicity and apoptosis in human vitiligo melanocytes (PIG3V). Further results demonstrated that baicalein promoted Nrf2 nucleus translocation as well as up-regulated the expression of Nrf2 and its target gene, heme oxygenase-1 (HO-1). Moreover, the protective effects of baicalein against H₂O₂-induced cellular damage and apoptosis as well as mitochondrial dysfunction were abolished by Nrf2 knockdown. Additionally, we observed that Nrf2 knockdown suppressed proliferation and increased the sensitivity of PIG3V cells to H₂O₂ treatment. Finally, we explored the mechanism of baicalein associated with Nrf2 activation and found that the phosphorylation of Nrf2 as well as ERK1/2and PI3K/AKT signaling were not involved in the baicalein-induced activation of Nrf2. Taken together, these data clearly suggest that baicalein enhances cellular antioxidant defense capacity of human vitiligo melanocytes through the activation of the Nrf2 signaling pathway, providing beneficial evidence for the application of baicalein in the vitiligo treatment.

Factors Associated with Development of Vitiligo in Patients with Halo Nevus

Background:

Halo nevus (HN) has been shown to be associated with vitiligo, but no standard signs are currently available to identify HN patients at risk of vitiligo, and the relevant data obtained in previous studies are somewhat conflicting. This study aimed to identify factors affecting the presence of vitiligo in HN patients.

Methods:

We performed a retrospective study on consecutive patients with HN at the First Affiliated Hospital of Sun Yat-sen University between January 2011 and December 2016. Detailed demographic and clinical data were collected to identify the factors associated with the presence of vitiligo in this cohort of patients using uni- and multi-variate logistic regression analyses.

Results:

A total of 212 HN patients were included, 101 of whom had vitiligo-associated HN (HNV). Univariate analysis indicated that a personal history of thyroid diseases was positively associated with HNV (odds ratio [OR] = 10.761, P = 0.025), while the onset age of HN was negatively associated with HNV (OR = 0.537, P = 0.026). Multivariate analysis demonstrated that the Koebner phenomenon (KP; OR = 10.632, P < 0.0001), multiple HN (OR = 3.918, P < 0.0001), and a familial history of vitiligo (OR = 3.222, P = 0.014) were independent factors associated with HNV.

Conclusions:

HN without vitiligo has clinical features distinct from HN associated with vitiligo. HN patients with KP, multiple lesions, or familial history of vitiligo are more likely to develop vitiligo and therefore should be monitored for clinical signs of such accompanied conditions.

Energetic mitochondrial failing in vitiligo and possible rescue by cardiolipin

Vitiligo is characterized by death or functional defects of epidermal melanocytes through still controversial pathogenic process. Previously, we showed that mitochondria-driven pre-senescent phenotype diminishes the capability of vitiligo melanocytes to cope with stressful stimuli. In the current study, we investigated markers of mitochondrial energy metabolism including the PGC1a axis, and then we determined the index of mitochondrial impairment using a cytomic approach. We found in cultured epidermal vitiligo melanocytes, compared to healthy ones, low ATP, increased proton leakage, and altered expression of several glycolytic enzymes (hexokinase II, pyruvic dehydrogenase kinase 1 and pyruvic kinase M2), We suggest that the low ATP production may be sufficient in steady-state conditions but it is unable to cover further needs. We also found in vitiligo melanocyrtes hyper-activation of the PGC1α axis, finalized to counteract the energy defect. Cytomic analysis, supported by MitoTracker Red pattern and ex-vivo immunohistochemistry, suggested an increased mitochondrial mass, possibly useful to ensure the essential ATP level. Finally, pharmacological cardiolipin stabilization reverted the energetic impairment, confirming the initial mitochondrial role. In conclusion, we report new insight in the pathogenetic mechanism of viitligo and indicate that the mitochondrial failure rescue by cardiolipin manipulation may be a new intriguing target in treatment development.

Biomarkers of disease activity in vitiligo: A systematic review

The pathophysiology of vitiligo is complex although recent research has discovered several markers which are linked to vitiligo and associated with disease activity. Besides providing insights into the driving mechanisms of vitiligo, these findings could reveal potential biomarkers. Activity markers can be used to monitor disease activity in clinical trials and may also be useful in daily practice. The aim of this systematic review was to document which factors have been associated with vitiligo activity in skin and blood. A second goal was to determine how well these factors are validated in terms of sensitivity and specificity as biomarkers to determine vitiligo activity. Both in skin (n=43) as in blood (n=66) an adequate number of studies fulfilled the predefined inclusion criteria. These studies used diverse methods and investigated a broad range of plausible biomarkers. Unfortunately, sensitivity and specificity analyses were scarce. In skin, simple histopathology with or without supplemental CD4 and CD8 stainings can still be considered as the gold standard, although more recently chemokine (C-X-C motif) ligand (CXCL) 9 and NLRP1 have demonstrated a good and possibly even better association with progressive disease. Regarding circulating biomarkers, cytokines (IL-1β, IL-17, IFN-γ, TGF-β), autoantibodies, oxidative stress markers, immune cells (Tregs), soluble CDs (sCD25, sCD27) and chemokines (CXCL9, CXCL10) are still competing. However, the two latter may be preferable as both chemokines and soluble CDs are easy to measure and the available studies display promising results. A large multicenter study could make more definitive statements regarding their sensitivity and specificity.

Differences in the melanosome distribution within the epidermal melanin units and its association with the impairing background of leukoderma in vitiligo and halo nevi: a retrospective study

Skin color is determined by the number of melanin granules produced by melanocytes that are transferred to keratinocytes. Melanin synthesis and the distribution of melanosomes to keratinocytes within the epidermal melanin unit (EMU) within the skin of vitiligo patients have been poorly studied. The ultrastructure and distribution of melanosomes in melanocytes and surrounding keratinocytes in perilesional vitiligo and normal skin were investigated using transmission electron microscopy (TEM). Furthermore, we performed a quantitative analysis of melanosome distribution within the EMUs with scatter plot. Melanosome count within keratinocytes increased significantly compared with melanocytes in perilesional stable vitiligo (P < 0.001), perilesional halo nevi (P < 0.01) and the controls (P < 0.01), but not in perilesional active vitiligo. Furthermore, melanosome counts within melanocytes and their surrounding keratinocytes in perilesional active vitiligo skin decreased significantly compared with the other groups. In addition, taking the means-standard error of melanosome count within melanocytes and keratinocytes in healthy controls as a normal lower limit, EMUs were graded into 3 stages (I-III). Perilesional active vitiligo presented a significantly different constitution in stages compared to other groups (P < 0.001). The distribution and constitution of melanosomes were normal in halo nevi. Impaired melanin synthesis and melanosome transfer are involved in the pathogenesis of vitiligo. Active vitiligo varies in stages and in stage II, EMUs are slightly impaired, but can be resuscitated, providing a golden opportunity with the potential to achieve desired repigmentation with an appropriate therapeutic choice. Adverse milieu may also contribute to the low melanosome count in keratinocytes.

Efficacy and Safety of 308-nm Monochromatic Excimer Lamp Versus Other Phototherapy Devices for Vitiligo: A Systematic Review with Meta-Analysis

BACKGROUND

Various phototherapy methods are used to treat vitiligo; however, the recent emergence of new devices has heightened debate concerning the best treatment method.

OBJECTIVE

We aimed to systematically review and meta-analyze published data comparing the efficacy and adverse effects of monochromatic excimer lamps versus excimer laser and narrowband ultraviolet B (NB-UVB) in treating vitiligo.

METHODS

A systematic search of PubMed, EMBASE, LILACS, Cochrane Central Register of Controlled Trials (CENTRAL), and clinical trials registries identified randomized controlled trials that included vitiligo patients, regardless of age, sex, or study language. We evaluated studies comparing excimer lamps with excimer laser or NB-UVB phototherapy.

RESULTS

The review included six studies (411 patients, 764 lesions). No study found significantly different efficacy between excimer lamps and excimer laser using the outcomes of ≥50% repigmentation [risk ratio (RR) = 0.97, 95% confidence interval (CI) 0.84-1.11] and ≥75% repigmentation (RR = 0.96, 95% CI 0.71-1.30). Likewise, no study found significant differences between excimer lamps and NB-UVB (RR = 1.14, 95% CI 0.88-1.48 for ≥50% repigmentation; RR = 1.81, 95% CI 0.11-29.52 for ≥75% repigmentation). Adverse effects were mild, including pruritus, burning sensation, and dryness, none of which interrupted treatment.

CONCLUSIONS

To our knowledge, this is the first systematic review of the efficacy and safety of excimer lamp treatment for vitiligo. Excimer lamps, excimer laser, and NB-UVB are all safe and effective in repigmentation of vitiligo lesions. Safety, effectiveness, and cost are considerations when choosing treatment.

PROSPERO REGISTRATION NUMBER

CRD42014015237.