Ultrastructural and functional alterations of mitochondria in perilesional vitiligo skin

Emerging Role of Fibroblasts in Vitiligo: A Formerly Underestimated Rising Star

Vitiligo is a disfiguring depigmentation disorder characterized by loss of melanocytes. Although numerous studies have been conducted on the pathogenesis of vitiligo, the underlying mechanisms remain unclear. Although most studies have focused on melanocytes and keratinocytes, growing evidence suggests the involvement of dermal fibroblasts, residing deeper in the skin. This review aims to elucidate the role of fibroblasts in both the physiological regulation of skin pigmentation and their pathological contribution to depigmentation, with the goal of shedding light on the involvement of fibroblasts in vitiligo. The topics covered in this review include alterations in the secretome, premature senescence, autophagy dysfunction, abnormal extracellular matrix, autoimmunity, and metabolic changes.

Dietary Influences on Skin Health in Common Dermatological Disorders

The role of diet in the development of skin disorders is well-established, with nutritional deficiency often identified as a risk factor for skin diseases. Imbalances in the skin can be caused by nutritional deficiencies, excessive intake, insufficient nutrients, and hazardous ingredients. Patients frequently inquire about the impact of dietary patterns on skin health when consulting dermatologists in clinical settings. Simultaneously, the popularity of using nutritional supplements containing vitamins, minerals, and nutraceutical blends has been on the rise. It is crucial for dermatologists, primary care physicians, and other healthcare providers to be acquainted with evidence-based dietary interventions, distinguishing them from those that are more market-driven than truly efficacious. This review explores the modification of diet, encompassing both dietary exclusion and supplementation, as a therapeutic approach for conditions such as psoriasis, atopic dermatitis, bullous disease, vitiligo, and alopecia areata. A comprehensive literature search, utilizing the PubMed/Medline, Google Scholar, and Medscape databases, was conducted to investigate the relationship between each nutrient and various inflammatory skin diseases. The findings emphasize the significance of a well-balanced and thoughtfully planned diet in supplying adequate amounts of proteins, vitamins, and minerals to support optimal skin health. Additionally, this comprehensive review navigates through various dietary recommendations, offering insights into their multifaceted impacts on the immune system, gut microbiome, and skin health. The goal is to pave the way for informed and targeted dietary interventions for individuals dealing with food allergies and associated skin conditions.

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.

Multimodal analyses of vitiligo skin identifies tissue characteristics of stable disease

Vitiligo is an autoimmune skin disease characterized by the destruction of melanocytes by autoreactive CD8⁺ T cells. Melanocyte destruction in active vitiligo is mediated by CD8⁺ T cells, but the persistence of white patches in stable disease is poorly understood. The interaction between immune cells, melanocytes, and keratinocytes in situ in human skin has been difficult to study due to the lack of proper tools. We combine noninvasive multiphoton microscopy (MPM) imaging and single-cell RNA-Seq (scRNA-Seq) to identify subpopulations of keratinocytes in stable vitiligo patients. We show that, compared with nonlesional skin, some keratinocyte subpopulations are enriched in lesional vitiligo skin and shift their energy utilization toward oxidative phosphorylation. Systematic investigation of cell-to-cell communication networks show that this small population of keratinocyte secrete CXCL9 and CXCL10 to potentially drive vitiligo persistence. Pseudotemporal dynamics analyses predict an alternative differentiation trajectory that generates this new population of keratinocytes in vitiligo skin. Further MPM imaging of patients undergoing punch grafting treatment showed that keratinocytes favoring oxidative phosphorylation persist in nonresponders but normalize in responders. In summary, we couple advanced imaging with transcriptomics and bioinformatics to discover cell-to-cell communication networks and keratinocyte cell states that can perpetuate inflammation and prevent repigmentation.

Four-Octyl Itaconate Attenuates UVB-Induced Melanocytes and Keratinocytes Apoptosis by Nrf2 Activation-Dependent ROS Inhibition

Vitiligo is an acquired skin depigmentation disease in which excessive reactive oxygen species (ROS) play a critical pathogenic role in melanocyte destruction. The complex crosstalk between melanocytes and keratinocytes in vitiligo suggests that treatments aimed at protecting both the cells might be meaningful. In this study, we investigated the effect of 4-octyl itaconate (4-OI), an itaconate derivative, on ultraviolet B- (UVB-) induced apoptosis in HaCaT and PIG1 cells and the underlying mechanisms. HaCaT and PIG1 cells were pretreated with 4-OI (50 or 100 μM) for 24 h and then exposed to 300 mJ/cm2 UVB (emission range 290–320 nm, emission peak 310 nm). ROS levels and cell apoptosis were investigated using fluorescence microscopy and flow cytometry 24 h after irradiation. In addition, nuclear translocation and the expression of pathway-related proteins and mRNAs were detected using confocal microscopy, western blotting, and qRT-PCR, respectively. Our results demonstrated that UVB induced apoptosis in HaCaT and PIG1 cells, whereas inhibition of ROS production could reverse this effect. Furthermore, 4-OI attenuated UVB-induced apoptosis in HaCaT and PIG1 cells in a concentration-dependent manner by reducing the ROS levels. Moreover, 4-OI induced nuclear translocation and activation of nuclear factor erythroid 2-related factor 2 (Nrf2), and Nrf2 silencing reversed the inhibitory effect of 4-OI on the UVB-induced increase in ROS production and apoptosis in HaCaT and PIG1 cells. In addition, in vivo experiments using the Institute of Cancer Research mouse model showed that 4-OI via tail vein injection (10 mg/kg/day for six consecutive days) could reduce skin damage induced by UVB (400 mJ/cm2/day for five consecutive days). In conclusion, 4-OI can protect melanocytes and keratinocytes from UVB-induced apoptosis by Nrf2 activation-dependent ROS inhibition and can potentially treat skin disorders associated with oxidative stress, such as vitiligo.

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.

The Role of Nutrition in Immune-Mediated, Inflammatory Skin Disease: A Narrative Review

Immune-mediated inflammatory skin diseases are characterized by a complex multifactorial etiology, in which genetic and environmental factors interact both in genesis and development of the disease. Nutrition is a complex and fascinating scenario, whose pivotal role in induction, exacerbation, or amelioration of several human diseases has already been well documented. However, owing to the complexity of immune-mediated skin disease clinical course and breadth and variability of human nutrition, their correlation still remains an open debate in literature. It is therefore important for dermatologists to be aware about the scientific basis linking nutrition to inflammatory skin diseases such as psoriasis, atopic dermatitis, hidradenitis suppurativa, bullous diseases, vitiligo, and alopecia areata, and whether changes in diet can influence the clinical course of these diseases. The purpose of this narrative review is to address the role of nutrition in immune-mediated inflammatory skin diseases, in light of the most recent and validate knowledge on this topic. Moreover, whether specific dietary modifications could provide meaningful implementation in planning a therapeutic strategy for patients is evaluated, in accordance with regenerative medicine precepts, a healing-oriented medicine that considers the whole person, including all aspects of the lifestyle.

Evaluation of the Langerhans cells role in vitiligo and its relationship to NB-UVB

BACKGROUND

Langerhans cells (LCs) are antigen-presenting cells that are characterized by CD1a and CD207/langerin expression. The disturbance in the communication network among keratinocytes, melanocytes, and antigen-presenting cells may be involved in vitiligo pathogenesis.

AIMS

The current work aims to detect and quantify LCs in involved skin of patients affected by vitiligo before and after treatment with NB-UVB using CD1a immunohistochemistry, in addition to correlate percentage of LCs with the clinicopathological parameters.

METHODS

Twenty vitiligo patients and 10 age and sex matched controls were investigated. Patients were received NB-UVB thrice weekly for 12 weeks.

RESULTS

There was a significant reduction in LCs percentage in skin affected by vitiligo before treatment in comparison with normal skin. About 65% (13/20) of vitiligo patients responded to NB-UVB, and the liability to respond was correlated with LCs percentage in specimens before treatment. However, there was no statistical difference between specimens before and after treatment regarding LCs percentage.

CONCLUSIONS

Reduction in LCs in vitiligo may be a sign of active disease and melanocytes destruction. The percentage of LCs affects response to NB-UVB since higher percentage is associated with greater response to therapy. Therefore, modulation of LCs as a type of immunotherapy could be beneficial in improvement of vitiligo.

An update on Vitiligo pathogenesis

Vitiligo, the most common depigmenting disorder of the skin, is undergoing a period of intense advances in both disease understanding and therapeutic possibilities leading the way to the beginning of a new era for the disorder. Its pathophysiology has gathered the attention of researchers for years, and many advances have been made in the clarification of the interaction between different factors that result in depigmented macule formation. The complex interplay between non-immunological and immunological factors in vitiligo is key for the development of the disease, and the participation of cells other than melanocytes, such as keratinocytes, fibroblasts, natural killer cells, and innate lymphoid cells, has been shown. Recent advances have also brought to the understanding of the complex part played by a specific subtype of T cells: T-resident memory cells. This review analyzes some of the most recent insights in vitiligo pathogenesis underlining the interactions between different cell types, which are the basis for the therapeutic approaches under development.

Identification of Candidate Genes and Pathways in Nonsegmental Vitiligo Using Integrated Bioinformatics Methods

BACKGROUND

Nonsegmental vitiligo (NSV) is an acquired depigmentation disorder of unknown origin. Enormous interests focus on finding novel biomarkers and pathways responsible for NSV.

METHODS

The gene expression level was obtained by integrating microarray datasets (GSE65127 and GSE75819) from the Gene Expression Omnibus database using the sva R package. Differentially expressed genes (DEGs) between each group were identified by the limma R package. The interaction network was constructed using STRING, and significant modules coupled with hub genes were identified by cytoHubba and molecular complex detection. Pathway analyses were conducted using generally applicable gene set enrichment and further visualized in R environment.

RESULTS

A total of 102 DEGs between vitiligo lesional skin and healthy skin, 14 lesion-specific genes, and 29 predisposing genes were identified from the integrated dataset. Except for the anticipated decrease in melanogenesis, three major functional changes were identified, including oxidative phosphorylation, p53, and peroxisome proliferator-activated receptor (PPAR) signaling in lesional skin. PPARG, MUC1, S100A8, and S100A9 were identified as key hub genes involved in the pathogenesis of vitiligo. Besides, upregulation of the T cell receptor signaling pathway was considered to be associated with susceptibility of the skin in NSV patients.

CONCLUSION

Our study reveals several potential pathways and related genes involved in NSV using integrated bioinformatics methods. It might provide references for targeted strategies for NSV.

Near-infrared spectroscopy as a potential non-invasive tool in the assessment of disease activity in vitiligo patients

Vitiligo is a common chronic depigmenting skin disease. We explored the utility of near-infrared (NIR) spectroscopy in the identification of spectral changes associated with disease activity in vitiligo patients. In vivo spectral measurements were performed directly on the perilesional skin of 70 vitiligo patients. Relative intensities (second derivative) at 1139, 1344, 1646 and 1839 nm appeared to be significantly lower in the perilesional region of patients with active vitiligo compared with stable disease, while the intensity at 1884 nm seemed to be significantly higher. A classification model based on the spectral ranges around those peaks generated a correct prediction in 82.9% of the cases. In conclusion, we can state that NIR spectroscopy could have potential in the assessment of disease activity. However, large-scale prospective studies are necessary to confirm our preliminary results.

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.

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.

Myg1 exonuclease couples the nuclear and mitochondrial translational programs through RNA processing

Semi-autonomous functioning of mitochondria in eukaryotic cell necessitates coordination with nucleus. Several RNA species fine-tune mitochondrial processes by synchronizing with the nuclear program, however the involved components remain enigmatic. In this study, we identify a widely conserved dually localized protein Myg1, and establish its role as a 3′-5′ RNA exonuclease. We employ mouse melanoma cells, and knockout of the Myg1 ortholog in Saccharomyces cerevisiae with complementation using human Myg1 to decipher the conserved role of Myg1 in selective RNA processing. Localization of Myg1 to nucleolus and mitochondrial matrix was studied through imaging and confirmed by sub-cellular fractionation studies. We developed Silexoseqencing, a methodology to map the RNAse trail at single-nucleotide resolution, and identified in situ cleavage by Myg1 on specific transcripts in the two organelles. In nucleolus, Myg1 processes pre-ribosomal RNA involved in ribosome assembly and alters cytoplasmic translation. In mitochondrial matrix, Myg1 processes 3′-termini of the mito-ribosomal and messenger RNAs and controls translation of mitochondrial proteins. We provide a molecular link to the possible involvement of Myg1 in chronic depigmenting disorder vitiligo. Our study identifies a key component involved in regulating spatially segregated organellar RNA processing and establishes the evolutionarily conserved ribonuclease as a coordinator of nucleo-mitochondrial crosstalk.

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.

Decreased SUMOylation of the retinoblastoma protein in keratinocytes during the pathogenesis of vitiligo

The role of SUMOylation in the pathogenesis of vitiligo has not been reported previously. The present study aimed to reveal abnormalities in small ubiquitin‑like modifier (SUMO) conjugation in keratinocytes from depigmented lesions of patients with vitiligo and confirm the role of SUMOylation in keratinocytes from patients with vitiligo. Skin samples used for immunohistochemistry were obtained by punch biopsy from the depigmented lesions of 6 patients. Blisters were produced by vacuum and the roofs were collected for keratinocyte culture. HaCaT cells were transduced with SUMO1 knockdown vectors. The protein expression of SUMO1, SUMO‑specific peptidase 1 (SENP1), ubiquitin‑conjugating enzyme E2 I (Ubc9), SUMO‑activating enzyme subunit 1 (SAE1), cyclin‑dependent kinase (CDK)2, CDK6, proliferating cell nuclear antigen (PCNA), retinoblastoma protein (Rb), phosphorylated Rb (pRb) and β‑actin was assessed by western blotting. The SUMOylation status of proteins was assessed by immunoprecipitation. Cell cycle analysis was performed by flow cytometry and cell proliferation rate was investigated using a Cell Counting Kit‑8. The results demonstrated that the levels of SUMO1‑conjugated proteins were decreased in vitiligo lesions and vitiligo keratinocytes compared with normal controls. The protein expression of Ubc9 was decreased and SENP1 was increased in vitiligo keratinocytes compared with normal keratinocytes, with no alterations in SAE1 expression. Following knockdown of SUMO1 in HaCaT cells, the proliferation of HaCaT cells was reduced and the cell cycle was arrested in G1 phase. Furthermore, the protein expression levels of PCNA, CDK2, CDK6 and pRb were reduced in SUMO1‑knockdown HaCaT cells, and SUMOylated Rb was also decreased markedly in keratinocytes from lesions of patients with vitiligo compared with normal keratinocytes. In conclusion, vitiligo lesions in the present study exhibited dysregulated SUMOylation and deSUMOylation balance and dysregulation of cell cycle progression may be present in SUMO1 knockdown HaCaT cells. These results indicate that deSUMOylation of Rb of keratinocytes may serve an important role in vitiligo, providing a novel direction for the study into the mechanism of vitiligo.

Re-appraisal of Keratinocytes' Role in Vitiligo Pathogenesis

Background

Vitiligo is a common pigmentary disorder. Studies on its pathogenesis extensively investigated melanocytes' abnormalities and few studies searched for keratinocytes' role in disease development. Liver X receptor-α (LXR-α) is a member of nuclear hormone receptors that acts as a transcription factor. Its target genes are the main regulators of melanocyte functions.

Aim

The aim of this study is to investigate keratinocytes' role in vitiligo pathogenesis through immunohistochemical expression of LXR-α in lesional, perilesional, and distant nonlesional vitiligo skin.

Materials and Methods

This case-control study was carried out on 44 participants. These included 24 patients with vitiligo and 20 age- and sex-matched normal individuals as a control group. Biopsies, from cases, were taken from lesional, perilesional, and distant nonlesional areas. Evaluation was done using immunohistochemical technique.

Results

Keratinocyte LXR-α expression was upregulated in the lesional and perilesional skin (follicular and interfollicular epidermis) compared with control skin (P <0.001 for all). There was significant association between higher histoscore (H-score) in lesional epidermis (P <0.001) and in hair follicle (P =0.001) and the presence of angiogenesis. There was significant association between higher H-score in lesional epidermis and suprabasal vacuolization (P =0.02). No significant association was found between H-score or expression percentage and clinical data of selected cases.

Conclusion

LXR-α upregulation is associated with keratinocyte damage in vitiligo lesional skin that leads to decreased keratinocyte-derived mediators and growth factors supporting the growth and/or melanization of surrounding melanocytes. Therefore, melanocyte function and survival are affected.

Vitiligo in Children: What's New in Treatment?

Vitiligo is an acquired chronic hypopigmentary disorder, which usually stars in childhood. The Authors discuss a short review of the more innovative therapies for childhood vitiligo.

Vitiligo in Children: A Better Understanding of the Disease

Vitiligo is an important skin disease of childhood. The authors briefly discuss the etiopathobiology, clinics and comorbidities of the disease.

Reduced Nrf2 activation in PI3K phosphorylation-impaired vitiliginous keratinocytes increases susceptibility to ROS-generating chemical-induced apoptosis

Keratinocytes in affected epidermis of vitiligo patients are known to have impaired activation of the PI3K/AKT pathway. Based on critical roles of keratinocytes and oxidative stress in vitiligo development, this study examined whether keratinocytes with impaired PI3K activation were more vulnerable to apoptosis caused by oxidative stress from phenolic compounds, p-tert-butylphenol (4-TBP) and hydroquinone (HQ). Cell viability assay, FACS analysis, ELISA for TNF-α or IL-1a, ROS assay, Western blot analysis for Nrf2 expression, and confocal microscopy with anti-Nrf2 and phospho-PI3K antibodies were done on primary cultured normal human keratinocytes with or without PI3K knockdown in the presence or absence of chemical treatment or antioxidant. Immunofluorescence staining using anti-Nrf2, phospho-PI3K, TNF-ɑ, and IL-1ɑ antibodies, ROS assay using dihydroethidium, and TUNEL assay were performed on sets of depigmented and normally pigmented skin from vitiligo patients. Results showed that 4-TBP or HQ treatment increased apoptosis and the expression levels of TNF-ɑ, IL-1ɑ, and ROS in PI3K-knockdown keratinocytes which reduced Nrf2 nuclear translocation compared to control keratinocytes. These changes were significantly recovered by an antioxidant treatment. Depigmented epidermis of vitiligo patients also showed lower levels of Nrf2 and phospho-PI3K but higher levels of ROS, TNF-ɑ, IL-1ɑ, and ROS with more TUNEL-positive cells. Therefore, impaired PI3K activation in keratinocytes in depigmented epidermis of vitiligo patients are vulnerable to apoptosis caused by ROS-generating chemicals due to reduced Nrf2 activation.

Oxidation products are increased in patients affected by non-segmental generalized vitiligo

Several lines of evidence support the relevance of reactive oxygen species (ROS) in vitiligo, but the exact role of glycation and oxidation of macromolecules needs to be better addressed. To investigate the involvement of advanced oxidation protein products (AOPPs) and advanced glycation end-products (AGEs), we performed a case-control association study by spectrofluorimetry and spectrophotometry, in 47 patients with non-segmental generalized vitiligo and 47 age- and sex-matched controls. Significantly higher levels of both AOPPs (p < 0.0001) and AGEs (p < 0.0001) were observed in vitiligo patients compared to healthy controls. In vitiligo patients, AGEs and AOPPs serum levels were directly associated with extension, duration of vitiligo, and disease activity. ROS, and in particular AGEs and AOPPs, could represent one of the main biomarkers to assess the onset and progression of vitiligo, due to the potential role as direct inducers of cell damage and also as autoimmunity triggers. Further longitudinal studies involving larger cohorts of patients are required to elucidate the role of oxidation products in the pathogenesis of vitiligo.

Usefulness of ischemia-modified albumin in predicting oxidative stress in patients with vitiligo

Aim: To investigate the emphasis of oxidative stress in the pathogenesis of vitiligo through an evaluation of ischemia-modified albumin (IMA). Results/methodology: IMA was of higher statistical significance in patients than in the control group (IMA: 0.57 ± 0.2 vs 0.52 ± 0.2 ΔABSU; p < 0.0001). IMA (p < 0.0001; OR: 8.9; 95% CI = 3.1–26.1) was found as an independent predictor of oxidative stress. Increases in affected body surface area and age were found to be independent risk factors for IMA. The sensitivity, specificity and positive and negative predictive values and capacity of IMA were higher than other studied biomarkers. Discussion/conclusion: IMA can be detected in the condition of oxidative stress in vitiligo; it has great potential as a biomarker of said condition, when compared with other studied biomarkers.

Dysfunction of Autophagy: A Possible Mechanism Involved in the Pathogenesis of Vitiligo by Breaking the Redox Balance of Melanocytes

Vitiligo is a common chronic acquired pigmentation disorder characterized by loss of functional melanocytes from the epidermis and follicular reservoir. Among multiple hypotheses which have been proposed in the pathogenesis of vitiligo, autoimmunity and oxidative stress-mediated toxicity in melanocytes remain most widely accepted. Macroautophagy is a lysosome-dependent degradation pathway which widely exists in eukaryotic cells. Autophagy participates in the oxidative stress response in many cells, which plays a protective role in preventing damage caused by oxidative stress. Recent studies have enrolled autophagy as an important regulator in limiting damage caused by UV light and lipid oxidation, keeping oxidative stress in a steady state in epidermal keratinocytes and maintaining normal proliferation and aging of melanocytes. Impairment of autophagy might disrupt the antioxidant defense system which renders melanocytes to oxidative insults. These findings provide supportive evidence to explore new ideas of the pathogenesis of vitiligo and other pigmentation disorders.

Fabrication of anti-vitiligo ointment containing Psoralea corylifolia: in vitro and in vivo characterization

BACKGROUND

Vitiligo is a repugnant and odious dermatological malady of the time. It has an detrimental impact on the pigmentation of the human skin as a result of the destruction of cutaneous melanocytes. It affects 1%-2% of the population worldwide. Different therapeutic regimens have been deployed to treat vitiligo, but none of them could stand alone to be stated as a perfect cure. Recently, a change has been observed through novel experimental-designed optimization leading to the development of an anti-vitiligo ointment containing Psoralea corylifolia (PC) seed powder.

AIM

The aim of this study was to explore the clinical outcomes of ointment containing powdered seeds of PC.

MATERIALS AND METHODS

Guided by the protocol Response Surface Methodology, 13 formulations of concentration variance of permeation enhancers were prepared. The formulation fulfilling the required criteria (pH; temperature stability tests at 8°C±0.1°C, 25°C±0.1°C and 40°C±0.1°C; and the physical properties such as color, bleeding and rheology) was selected for clinical trials. Fourier transform infrared spectroscopy studies of seed powder of PC and selected formulation of the seed powder were performed. After obtaining informed consents and with prior approval of university and hospital ethical review boards, 20 patients (age range 25-65 years) were included in the present study. Formulations were applied on the affected body parts of patients, and some affected portion of the same patient was taken as control (self-control study design). The pigmentation of white spots of vitiligo was photographically evaluated before, during and after 12 weeks of treatment. Analysis of the measured values was performed using GraphPad Prism version 5 statistical software. A paired sample t-test was performed to observe variation between repigmented patches and white patches of self-control.

RESULTS

Hydrophilic ointment (10% w/w) prepared with seed powder of PC was fabricated. The ointment was found effective for small circular white lesions of vitiligo as compared to self-control. Pre- and post-treatment differences in the levels of pigmentation were statistically significant (P≤0.05).

CONCLUSION

Ointment containing seed powder of PC could be an effective monotherapy for small circular white lesions of vitiligo.

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.

Vitiligo: How do oxidative stress-induced autoantigens trigger autoimmunity?

Vitiligo is a common depigmentation disorder characterized by a loss of functional melanocytes and melanin from epidermis, in which the autoantigens and subsequent autoimmunity caused by oxidative stress play significant roles according to hypotheses. Various factors lead to reactive oxygen species (ROS) overproduction in the melanocytes of vitiligo: the exogenous and endogenous stimuli that cause ROS production, low levels of enzymatic and non-enzymatic antioxidants, disturbed antioxidant pathways and polymorphisms of ROS-associated genes. These factors synergistically contribute to the accumulation of ROS in melanocytes, finally leading to melanocyte damage and the production of autoantigens through the following ways: apoptosis, accumulation of misfolded peptides and cytokines induced by endoplasmic reticulum stress as well as the sustained unfolded protein response, and an 'eat me' signal for phagocytic cells triggered by calreticulin. Subsequently, autoantigens presentation and dendritic cells maturation occurred mediated by the release of antigen-containing exosomes, adenosine triphosphate and melanosomal autophagy. With the involvement of inducible heat shock protein 70, cellular immunity targeting autoantigens takes the essential place in the destruction of melanocytes, which eventually results in vitiligo. Several treatments, such as narrow band ultraviolet, quercetin and α-melanophore-stimulating hormone, are reported to be able to lower ROS thereby achieving repigmentation in vitiligo. In therapies targeting autoimmunity, restore of regulatory T cells is absorbing attention, in which narrow band ultraviolet also plays a role.

Vitiligo

Vitiligo is an acquired depigmenting disorder that affects 0.5% to 2% of the world population. Three different forms are classified according to the distribution of lesions; namely non-segmental, segmental and mixed vitiligo. Vitiligo is associated with polymorphisms in genes involved in the immune response and in melanogenesis. However, environmental factors are required for the development of manifest disease. In general, the diagnosis is clinical and no laboratory tests or biopsies are required. Metabolic alterations are central to current concepts in pathophysiology. They induce an increased generation of reactive oxygen species and susceptibility to mild exogenous stimuli in the epidermis. This produces a senescent phenotype of skin cells, leads to the release of innate immune molecules, which trigger autoimmunity, and ultimately causes dysfunction and death of melanocytes. Clinical management aims to halt depigmentation, and to either repigment or depigment the skin, depending on the extent of disease. New therapeutic approaches include stimulation of melanocyte differentiation and proliferation through α-melanocyte-stimulating hormone analogues and through epidermal stem cell engineering. Several questions remain unsolved, including the connection between melanocyte depletion and stem cell exhaustion, the underlying degenerative mechanisms and the biological mediators of cell death. Overall, vitiligo is an excellent model for studying degenerative and autoimmune processes and for testing novel approaches in regenerative medicine. For an illustrated summary of this Primer, visit: http://go.nature.com/vIhFSC.

Oxidative stress and immune system in vitiligo and thyroid diseases

Vitiligo is an acquired dermatological disease frequently associated with autoimmune thyroid disorders. Several theories have been proposed so far to unravel the complex vitiligo pathogenesis. Currently, the autocytotoxic and the autoimmune theories are the most accredited hypothesis, since they are sustained by several important clinical and experimental evidences. A growing body of evidences shows that autoimmunity and oxidative stress strictly interact to finally determine melanocyte loss. In this scenario, associated thyroid autoimmunity might play an active and important role in triggering and maintaining the depigmentation process of vitiligo.

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.

SIRT1 regulates MAPK pathways in vitiligo skin: insight into the molecular pathways of cell survival

Vitiligo is an acquired and progressive hypomelanotic disease that manifests as circumscribed depigmented patches on the skin. The aetiology of vitiligo remains unclear, but recent experimental data underline the interactions between melanocytes and other typical skin cells, particularly keratinocytes. Our previous results indicate that keratinocytes from perilesional skin show the features of damaged cells. Sirtuins (silent mating type information regulation 2 homolog) 1, well-known modulators of lifespan in many species, have a role in gene repression, metabolic control, apoptosis and cell survival, DNA repair, development, inflammation, neuroprotection and healthy ageing. In the literature there is no evidence for SIRT1 signalling in vitiligo and its possible involvement in disease progression. Here, biopsies were taken from the perilesional skin of 16 patients suffering from non-segmental vitiligo and SIRT1 signalling was investigated in these cells. For the first time, a new SIRT1/Akt, also known as Protein Kinase B (PKB)/mitogen-activated protein kinase (MAPK) signalling has been revealed in vitiligo. SIRT1 regulates MAPK pathway via Akt-apoptosis signal-regulating kinase-1 and down-regulates pro-apoptotic molecules, leading to decreased oxidative stress and apoptotic cell death in perilesional vitiligo keratinocytes. We therefore propose SIRT1 activation as a novel way of protecting perilesional vitiligo keratinocytes from damage.

Genetic variants of the APE1 gene and the risk of vitiligo in a Chinese population: a genotype-phenotype correlation study

Vitiligo is an acquired depigmentation disorder, and reactive oxygen species play an important role in melanocyte damage. Base excision repair is the major pathway responsible for removing reactive oxygen species-induced DNA damage, in which APE1, ADPRT, and XRCC1 play key roles. To investigate the association between genetic variations of these genes and the risk of vitiligo in Chinese populations, we genotyped APE1-Asp148Glu, ADPRT-Val762Ala, and XRCC1-Arg399Gln polymorphisms and measured serum 8-OHdG levels in a hospital-based case-control study. We found that a significantly increased risk of vitiligo was associated with the APE1 Asp/Glu (adjusted odds ratio (OR) 1.24; 95% confidence interval (CI) 1.02-1.52) and Glu/Glu genotypes (adjusted OR 1.48; 95% CI 1.13-1.93), compared with the APE1 Asp/Asp genotype, whereas no vitiligo risk was associated with the genotypes ADPRT-Val762Ala and XRCC1-Arg399Gln. Furthermore, serum 8-OHdG levels were elevated in the APE1-148Glu allele carriers (Asp/Glu+Glu/Glu), in an allele dose-response manner, with the risk of vitiligo (Ptrend<0.05). In addition, we found that the APE1-148Glu variant increased the 8-OHdG levels of cultured human melanocytes treated with H2O2, without any impact on the endonuclease activity. These data suggest that the APE1-Asp148Glu polymorphism aggravates oxidative stress in human melanocytes and contributes to genetic predisposition to vitiligo in Chinese people.

Baicalein protects human melanocytes from H₂O₂-induced apoptosis via inhibiting mitochondria-dependent caspase activation and the p38 MAPK pathway

The removal of H(2)O(2) by antioxidants has been proven to be beneficial to patients with vitiligo. Baicalein (5,6,7-trihydroxyflavone; BE) has antioxidant activity and has been used in vitiligo therapy in Chinese traditional medicine. In this study, we investigated the potential protective effect and mechanisms of BE against H(2)O(2)-induced apoptosis in human melanocytes. Melanocytes from the PIG1 cell line were pretreated with different concentrations of BE for 1 h, followed by exposure to 1.0 mM H(2)O(2) for 24 h. Cell apoptosis, reactive oxygen species levels, and mitochondrial membrane potentials were evaluated by flow cytometry, and cell viability was determined by an MTT assay. The expressions of Bax, Bcl-2, caspase-3, total and phosphorylated ERKs, and p38 MAPK were assayed by Western blot to investigate the possible molecular mechanisms. Our results showed that BE significantly inhibited H(2)O(2)-induced apoptosis, intracellular reactive oxygen species generation, and changes in the mitochondrial membrane potential. It also reduced the Bax/Bcl-2 ratio, the release of cytochrome c, the activation of caspase-3, and the phosphorylation of p38 MAPK in a concentration-dependent manner. The results demonstrate for the first time that BE exerts a cytoprotective role in H(2)O(2)-induced apoptosis by inhibiting the mitochondria-dependent caspase activation and p38 MAPK pathway.

Dendritic cells: ultrastructural and immunophenotypical changes upon nb-UVB in vitiligo skin

The role of dendritic cells in vitiligo is still unclear. Few studies have provided contradictory results about their quantitative variation and no data exist concerning their immunophenotypical distribution in diseased skin. The purpose of our study was to analyze the presence, the distribution, the immunophenotypical markers and the effects of nb-UVB therapy on dendritic cells in non-lesional, perilesional, and lesional vitiligo skin. Punch-biopsies of 6 mm were taken from lesional, perilesional, and non-lesional skin of 12 patients affected by non-segmental vitiligo, treated with nb-UVB. An immunohistochemical and an ultrastructural analysis were performed. Immunohistochemical and ultrastructural analysis showed both quantitative and qualitative modifications of Langerhans cells. Nb-UVB therapy, one of the most effective treatments for the disease, was able to reduce the Langerhans cells number and to redistribute main dendritic subsets. This study underlines the importance of dendritic cells, Langerhans cells in particular, in non-segmental vitiligo, in its pathogenesis and in its better therapeutical approach.

The involvement of Smac/DIABLO, p53, NF-kB, and MAPK pathways in apoptosis of keratinocytes from perilesional vitiligo skin: Protective effects of curcumin and capsaicin

Oxidative stress has been suggested as the initial pathogenetic event in melanocyte degeneration in vitiligo. Our previous results indicate that keratinocytes from perilesional skin show the features of damaged cells. In the present study, biopsies were taken from the perilesional skin of 12 patients suffering from nonsegmental vitiligo. The intracellular pathways involved in keratinocyte damage and apoptosis and the antioxidant protection of curcumin and capsaicin in these cells were investigated. In keratinocytes from perilesional vitiligo skin, we observed high levels of activated p38, NF-kB p65 subunit, p53, and Smac/DIABLO proteins. In contrast, low levels of ERK phosphorylation were present. To investigate the relationship between these pathways, we used specific inhibitors and evaluated the alteration of each pathway. For the first time, our study demonstrates the pivotal role of p38 MAP kinase as an upstream signal of perilesional keratinocyte damage, and the important contribution of p38 and NF-kB on p53 accumulation. Curcumin and capsaicin also increase ERK phosphorylation, thus inhibiting apoptosis. Moreover, pretreatment with such natural antioxidants inhibited caspase activation, increased total antioxidant capacity, repressed intracellular ROS generation and lipid peroxidation, and improved mitochondrial activity. These results suggest that antioxidants might represent an alternative approach to protect against vitiligo progression.

Promoter polymorphism -119C/G in MYG1 (C12orf10) gene is related to vitiligo susceptibility and Arg4Gln affects mitochondrial entrance of Myg1

Background

MYG1 (Melanocyte proliferating gene 1, also C12orf10 in human) is a ubiquitous nucleo-mitochondrial protein, involved in early developmental processes and in adult stress/illness conditions. We recently showed that MYG1 mRNA expression is elevated in the skin of vitiligo patients. Our aim was to examine nine known polymorphisms in the MYG1 gene, to investigate their functionality, and to study their association with vitiligo susceptibility.

Methods

Nine single nucleotide polymorphisms (SNPs) in the MYG1 locus were investigated by SNPlex assay and/or sequencing in vitiligo patients (n = 124) and controls (n = 325). MYG1 expression in skin biopsies was detected by quantitative-real time PCR (Q-RT-PCR) and polymorphisms were further analysed using luciferase and YFP reporters in the cell culture.

Results

Control subjects with -119G promoter allele (rs1465073) exhibited significantly higher MYG1 mRNA levels than controls with -119C allele (P = 0.01). Higher activity of -119G promoter was confirmed by luciferase assay. Single marker association analysis showed that the -119G allele was more frequent in vitiligo patients (47.1%) compared to controls (39.3%, P < 0.05, OR 1.37, 95%CI 1.02-1.85). Analysis based on the stage of progression of the vitiligo revealed that the increased frequency of -119G allele occurred prevalently in the group of patients with active vitiligo (n = 86) compared to the control group (48.2% versus 39.3%, P < 0.05; OR 1.44, 95%CI 1.02-2.03). Additionally, we showed that glutamine in the fourth position (in Arg4Gln polymorphism) completely eliminated mitochondrial entrance of YFP-tagged Myg1 protein in cell culture. The analysis of available EST, cDNA and genomic DNA sequences revealed that Myg1 4Gln allele is remarkably present in human populations but is never detected in homozygous state according to the HapMap database.

Conclusions

Our study demonstrated that both MYG1 promoter polymorphism -119C/G and Arg4Gln polymorphism in the mitochondrial signal of Myg1 have a functional impact on the regulation of the MYG1 gene and promoter polymorphism (-119C/G) is related with suspectibility for actively progressing vitiligo.