Genetic Susceptibility to Vitiligo: GWAS Approaches for Identifying Vitiligo Susceptibility Genes and Loci

Chemical leukoderma: An insight of pathophysiology and contributing factors

Chemical leukoderma, or chemical-based vitiligo, is a dermal disease triggered by exposure to chemicals and characterized by the emergence of depigmentation or hypopigmentation of the skin. The etiology of this condition is associated with exposure to various chemical substances present in both occupational and non-occupational settings. The precise mechanism that underlies chemical leukoderma remains elusive and is believed to result from the demise of melanocytes, which are responsible for producing skin pigments. This condition has gained particular prominence in developing countries like India. An interesting connection between chemical leukoderma and vitiligo has been identified; studies suggest that exposure to many household chemicals, which are derivatives of phenols and catechol, may serve as a primary etiological factor for the condition. Similar to autoimmune diseases, its pathogenesis involves contributions from both genetic and environmental factors. Furthermore, over the last few decades, various studies have demonstrated that exposure to chemicals plays a crucial role in initiating and progressing chemical leukoderma, including cases stemming from occupational exposure.

A bidirectional autoimmune cluster between vitiligo and rheumatoid arthritis: a large-scale population-based study

A knowledge gap exists regarding the association between vitiligo and rheumatoid arthritis (RA) due to the absence of large-scale cohort studies designed to investigate this association. To investigate the bidirectional epidemiological association between vitiligo and RA. A population-based study was conducted using Clalit Health Services (CHS) database (2002-2019) using both a cohort study and a case-control study design. Adjusted hazard ratio (HR) and odds ratio (OR) were calculated by multivariate Cox and logistic regressions, respectively. Overall, 20,851 vitiligo patients and 102,475 controls were included. The incidence of new-onset RA was 4.1 (95% CI 3.0-5.4) and 2.9 (95% CI 2.4-3.3) cases per 10,000 person-years among patients with vitiligo and controls, respectively. Patients with vitiligo had a significantly increased risk of developing new-onset RA (adjusted HR, 1.44; 95% confidence interval [CI], 1.02-2.02, P = 0.036). The likelihood of having vitiligo was significantly elevated after a preexisting diagnosis of RA (adjusted OR, 1.67; 95% CI, 1.38-2.03; P < 0.001). Relative to the remaining patients with vitiligo, those with vitiligo and comorbid RA demonstrated an elevated risk of all-cause mortality (adjusted HR, 1.61; 95% CI, 1.03-2.51; P = 0.037). Our study confirms the bidirectional association between vitiligo and RA. Physicians treating patients with vitiligo should be aware of the association in clinical practice.

ViCEKb: Vitiligo-linked Chemical Exposome Knowledgebase

Vitiligo is a complex disease wherein the environmental factors, in conjunction with the underlying genetic predispositions, trigger the autoimmune destruction of melanocytes, ultimately leading to depigmented patches on the skin. While genetic factors have been extensively studied, the knowledge on environmental triggers remains sparse and less understood. To address this knowledge gap, we present the first comprehensive knowledgebase of vitiligo-triggering chemicals namely, Vitiligo-linked Chemical Exposome Knowledgebase (ViCEKb). ViCEKb involves an extensive and systematic manual effort in curation of published literature and subsequent compilation of 113 unique chemical triggers of vitiligo. ViCEKb standardizes various chemical information, and categorizes the chemicals based on their evidences and sources of exposure. Importantly, ViCEKb contains a wide range of metrics necessary for different toxicological evaluations. Notably, we observed that ViCEKb chemicals are present in a variety of consumer products. For instance, Propyl gallate is present as a fragrance substance in various household products, and Flutamide is used in medication to treat prostate cancer. These two chemicals have the highest level of evidence in ViCEKb, but are not regulated for their skin sensitizing effects. Furthermore, an extensive cheminformatics-based investigation revealed that ViCEKb chemical space is structurally diverse and comprises unique chemical scaffolds in comparison with skin specific regulatory lists. For example, Neomycin and 2,3,5-Triglycidyl-4-aminophenol have unique chemical scaffolds and the highest level of evidence in ViCEKb, but are not regulated for their skin sensitizing effects. Finally, a transcriptomics-based analysis of ViCEKb chemical perturbations in skin cell samples highlighted the commonality in their linked biological processes. Overall, we present the first comprehensive effort in compilation and exploration of various chemical triggers of vitiligo. We believe such a resource will enable in deciphering the complex etiology of vitiligo and aid in the characterization of human chemical exposome. ViCEKb is freely available for academic research at: https://cb.imsc.res.in/vicekb.

Vitamin D Receptor Gene Polymorphisms and Association with Vitiligo in Indonesian Population

Introduction

Vitiligo is an acquired depigmenting skin disorder due to the loss of melanocyte function in the epidermis and hair follicles. The pathogenesis of vitiligo is multifactorial, with genetics being a predisposing factor. Previous studies had varying results regarding whether or not polymorphisms of vitamin D receptor (VDR) gene are associated with the risk of vitiligo in specific populations. This study investigated the association between three frequently analyzed VDR gene polymorphisms (ApaI, BsmI, TaqI) and susceptibility to vitiligo in Indonesian population.

Methods

Thirty-four vitiligo patients and 34 age- and sex-matched healthy subjects aged ≥18 years old were recruited in the Dermatology and Venereology Outpatient Clinic of Dr. Hasan Sadikin General Hospital, Bandung, Indonesia. Genomic deoxyribonucleic acid (DNA) was extracted from the peripheral blood using a DNA isolation kit. VDR gene polymorphisms (ApaI, BsmI, and TaqI) were investigated using the polymerase chain reaction-restriction-fragment length polymorphism method. The differences of genotype distributions and allele frequencies were statistically compared between case and control groups using Chi-square test.

Results

VDR gene polymorphisms were identified in 68 participants, consisting of Aa (n = 14), aa (n = 20), Bb (n = 15), bb (n = 19), and TT (n = 34) genotypes in the case group. In the control group, Aa (n = 6), aa (n = 28), Bb (n = 17), bb (n = 17), and TT (n = 34) genotypes were identified. However, only subjects with ApaI Aa genotype polymorphism had a 3.267-fold increased risk of developing vitiligo.

Conclusion

This study showed that ApaI Aa genotype polymorphism of the VDR gene increases the risk of vitiligo in Indonesian population.

Immunogenetic Metabolomics Reveals Key Enzymes That Modulate CAR T-cell Metabolism and Function

Immune evasion is a critical step of cancer progression that remains a major obstacle for current T cell-based immunotherapies. Hence, we investigated whether it is possible to genetically reprogram T cells to exploit a common tumor-intrinsic evasion mechanism whereby cancer cells suppress T-cell function by generating a metabolically unfavorable tumor microenvironment (TME). In an in silico screen, we identified ADA and PDK1 as metabolic regulators. We then showed that overexpression (OE) of these genes enhanced the cytolysis of CD19-specific chimeric antigen receptor (CAR) T cells against cognate leukemia cells, and conversely, ADA or PDK1 deficiency dampened this effect. ADA-OE in CAR T cells improved cancer cytolysis under high concentrations of adenosine, the ADA substrate, and an immunosuppressive metabolite in the TME. High-throughput transcriptomics and metabolomics analysis of these CAR T cells revealed alterations of global gene expression and metabolic signatures in both ADA- and PDK1-engineered CAR T cells. Functional and immunologic analyses demonstrated that ADA-OE increased proliferation and decreased exhaustion in CD19-specific and HER2-specific CAR T cells. ADA-OE improved tumor infiltration and clearance by HER2-specific CAR T cells in an in vivo colorectal cancer model. Collectively, these data unveil systematic knowledge of metabolic reprogramming directly in CAR T cells and reveal potential targets for improving CAR T-cell therapy.

Vitiligo and insulin resistance as a component of metabolic syndrome: an analysis

There have been many studies on the association between vitiligo and metabolic syndrome, while only few scientific papers on vitiligo and insulin resistance. In recent years, there have been significant developments in research to trace and understand the aetiology of both conditions. In this article we have analysed pathophysiological mechanisms and the association of insulin resistance (as a component of metabolic syndrome) and vitiligo.

Autoimmune HLA Alleles and Neoepitope Presentation Predict Post-Allogenic Transplant Relapse

Introduction

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) can cure patients with high-risk myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML). However, many patients relapse or develop debilitating graft-versus-host disease. Transplant restores T-cell reactivity against tumor cells, implicating patient human leukocyte antigen (HLA)-dependent antigen presentation via the major histocompatibility complex as a determinant of response. We sought to identify characteristics of the HLA genotype that influence response in allo-HSCT patients.

Methods

We collected HLA genotype and panel-based somatic mutation profiles for 55 patients with AML and MDS and available data treated at the University of California San Diego Moores Cancer Center between May 2012 and January 2019. We evaluated characteristics of the HLA genotype relative to relapse-free time and overall survival (OS) post-allo-HSCT using univariable and multivariable regression.

Results

In multivariable regression, the presence of an autoimmune allele was significantly associated with relapse-free time (hazard ratio [HR], 0.25; p = 0.01) and OS (HR, 0.16; p < 0.005). The better potential of the donor HLA type to present peptides harboring driver mutations trended toward better relapse-free survival (HR, 0.45; p = 0.07) and significantly correlated with longer OS (HR, 0.33; p = 0.01) though only a minority of cases had an HLA mismatch.

Conclusion

In this single institution retrospective study of patients receiving allo-HSCT for relapsed AML/MDS, characteristics of an individual's HLA genotype (presence of an autoimmune allele and potential of the donor HLA to better present peptides representing driver mutations) were significantly associated with better outcomes. These findings suggest that HLA type may guide the optimal application of allo-HSCT and merit evaluation in larger cohorts. ClinicalTrials.gov Identifier: NCT02478931.

Spontaneous Vitiligo in a Captive Rhesus Monkey (Macaca Mulatta)

Vitiligo affects a significant portion of human and animal populations. The disease causes irregular and multifocal progressive loss of fur, skin, and mucous membrane pigmentation due to the loss or absence of melanocytes. While etiopathogenesis is not completely understood, autoimmunity, environmental, and genetic factors are implicated We present a case report on a 16-y-old female rhesus macaque (Macaca mulatta ) with depigmented areas that are progressively increasing on the skin and coat and are distributed on the head and back. Histopathology revealed alterations compatible with vitiligo characterized by the absence of melanocytes in the epidermis and dermis. The clinical history and complementary exams support this diagnosis.

Investigating the epidemiological relationship between vitiligo and psoriasis: a population-based study

BACKGROUND

The association of vitiligo with psoriasis is inconsistent in the current literature.

OBJECTIVE

To assess the bidirectional association between vitiligo and psoriasis.

METHODS

A population-based study was performed to compare vitiligo patients (n = 20,851) with age-, sex- and ethnicity-matched control subjects (n = 102,475) regarding the incidence of new-onset and the prevalence of preexisting psoriasis. Adjusted hazard ratios (HRs) and adjusted odds ratios (ORs) were calculated by cox regression and logistic regression, respectively.

RESULTS

The incidence rate of new-onset psoriasis was estimated at 7.9 (95% CI 6.4-9.7) and 4.7 (95% CI 4.1-5.3) cases per 10,000 person-years among patients with vitiligo and controls, respectively. Patients with vitiligo experienced an increased risk of psoriasis (fully-adjusted HR 1.71; 95% CI 1.35-2.17; P < 0.001). On the other hand, the odds of vitiligo were only marginally elevated among patients with preexisting psoriasis (fully-adjusted OR 1.19; 95% CI 1.01-1.40; P = 0.051). Compared to other patients with vitiligo, those with vitiligo and comorbid psoriasis were older at the onset of the disease and had a greater prevalence of metabolic and cardiovascular comorbidities.

CONCLUSIONS

A diagnosis of vitiligo predisposes individuals to develop subsequent psoriasis. Clinicians managing dermatologic patients ought to be aware of this comorbidity. Further research is required to explicate the pathomechanism underlying this epidemiological observation.

Association of rs4711998 of IL-17A, rs2275913 of IL-17A and rs763780 IL-17F gene polymorphisms with non-segmental vitiligo in a Mexican population

Vitiligo is the most common depigmenting disease characterized by achromic macules due to selective loss of melanocytes. The pathogenesis remains poorly elucidated, and multiple hypotheses exist regarding its pathogenesis. Evidence suggests that stress on melanocytes can result in activation of the immune system, and involvement of both activated cluster of differentiation (CD8+) cytotoxic and CD4+ T cells in the dysfunction, depigmentation, and apoptosis of melanocytes. Recent studies show that the interleukin 17 (IL-17) axis plays a central role in the pathogenesis of the disease. IL-17 is an important regulatory effector cytokine in this pathway. The aim of this study was to evaluate the association of IL-17A rs4711998 (-832A/G), IL-17A rs2275913 (-197G/A), and IL-17F rs763780 (7488A/G) with vitiligo in a Northeastern Mexican population. This was a case-control study and included 116 patients with vitiligo and 116 control subjects. Genotype characterization of IL-17A rs4711998 (-832A/G), IL-17A rs2275913 (-197G/A), and IL-17F rs763780 (7488A/G) was performed using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. A p ≤ 0.05 was considered significant. It was observed that the combination of the genotypes GG/GA for IL-17F rs763780 (7488A/G) was associated with an increased risk for the development of vitiligo (OR 2.0943, 95% Cl 1.2375-3.5445, p = 0.0056). Regarding IL-17A rs4711998 (-832A/G) and IL-17A rs2275913 (-197G/A) genotyping, no association with vitiligo development was found. In conclusion, the SNP rs763780 in the IL-17F gene appears to be a risk factor for vitiligo development in this Mexican population and it may be useful in future studies, especially for the development of new therapies.

Biologic and targeted therapeutics in vitiligo

BACKGROUND

Vitiligo is a long-standing progressive autoimmune disease with depigmented macules/patches with significant psychological morbidity to the patients. From being one of the most poorly understood diseases in the past, there has been a rampant advance in determining the molecular and genetic factors influencing the disease process. More light has been shed on the complex intracellular environment and interplay between innate and adaptive immunity. Numerous cytokines and signaling pathways have been associated with disease pathogenesis in the recent past.

OBJECTIVE

The aim of this review the efficacy of biologic and targeted therapeutics in vitiligo.

METHODS

A detailed literature search was conducted on databases like PubMed, COCHRANE Central, EMBASE and Google Scholar using keywords-"biologics," "vitiligo," "treatment," "repigmentation," "JAK inhibitors,", "TNF-ꭤ inhibitors," and "IL17/23 inhibitors," Relevant studies and review articles in English were analyzed in detail and report was written. This article aimed at a comprehensive review of all the biologicals and newer targeted therapeutics tried in vitiligo and their efficacy with an insight into the potential complications arising as a result of the therapy.

RESULTS

Most conventional vitiligo treatment modalities are restricted to generalized nonspecific immunosuppressants like topical and oral corticosteroids, calcineurin inhibitors, phototherapy, and surgical modalities. There have been reports and studies on the usage of biologicals in treating vitiligo. JAK inhibitors have shown good efficacy in vitiligo; however, it lacks substantial evidence in the form of randomized control trials. Similarly, the use of targeted therapeutics in treating vitiligo is substantiated by limited evidence and requires more randomized trials for further evidence.

CONCLUSION

JAK inhibitors have shown promising results and good tolerability; Adjuvant phototherapy can achieve a superior response compared to monotherapy. Though TNF-ꭤ has been tried in a few cases, it is best used if vitiligo is present in association with other chronic autoimmune diseases for which it is indicated. More in vitro studies and clinical research are required to understand the pathogenesis clearly, and therapy has to be targeted at specific pathways for a better approach toward vitiligo. Treatment aimed at induction and differentiation of melanocytes may be added to achieve faster repigmentation.

Beyond skin white spots: Vitiligo and associated comorbidities

Vitiligo is a common depigmentation disorder of an unknown origin characterized by the selective loss of melanocytes, resulting in typical white macules and patches. However, vitiligo is now recognized as more than just a skin disease, what a dermatologist observes as a white spot of skin is just the "tip of the iceberg" of the condition. We attempt to clarify the classification of comorbidities associated with vitiligo from various reviews and reports, and describe their possible pathogenesis. In conclusion, the literature provides evidence of an association between vitiligo and ocular and auditory abnormalities, autoimmune disorders, other dermatological diseases, metabolic syndrome and related disorders, and psychological diseases. These associations highlight the importance of a multidisciplinary approach in managing vitiligo patients.

PMEL is mutated in oculocutaneous albinism

Oculocutaneous albinism (OCA) is a group of Mendelian disorders characterized by hypopigmentation of skin, hair and pigmented ocular structures. While much of the genetic heterogeneity of OCA has been resolved, many patients still lack a molecular diagnosis following exome sequencing. Here, we report a consanguineous family in which the index patient presented with OCA and Hirschsprung disease but tested negative for known genetic causes of OCA. Instead, he was found to have a homozygous presumptive loss of function variant in PMEL. PMEL encodes a scaffolding protein that is essential for the normal maturation of melanosomes and normal deposition of the melanin pigment therein. Numerous PMEL vertebrate ortholog mutants have been reported and all were characterized by conspicuous pigmentary abnormalities. We suggest that the patient we report is the first human equivalent of PMEL loss of function.

Different vitiligo characteristics as predictors of increased risk of metabolic syndrome and insulin resistance: A case-control study

BACKGROUND

Autoimmune and metabolic disturbances have been reported in association with vitiligo, highlighting possible systemic associations that should be considered.

AIMS

To assess the possible association of metabolic syndrome (MetS) as well as insulin resistance (IR) with vitiligo in different age groups.

METHODS

This case-control study included 142 patients with vitiligo aging ≥ 6 years and 142 age- and sex-matched controls. Participants were assessed for MetS using the International Diabetes Federation (IDF) criteria in addition to IR via homeostasis model assessment of IR (HOMA-IR). The study was registered at Clinical Trials.gov, Identifier: NCT03622320, on August 9, 2018.

RESULTS

As per the IDF criteria, patients with vitiligo showed significantly more frequent association with high fasting plasma glucose levels, high blood pressure readings, central obesity, dyslipidemia, and MetS than controls (p = 0.020, p = 0.034, p = 0.014, p < 0.001, and p = 0.002, respectively). Moreover, patients with vitiligo have significantly higher levels of fasting insulin and HOMA-IR (p ≤ 0.001). Results obtained from patients with vitiligo and controls with coexistent MetS/IR demonstrated vitiligo as a risk factor for both MetS and IR. Univariate and multivariate logistic regression highlighted that older age was the significant independent predictor for MetS and IR.

CONCLUSION

Patients with vitiligo showed a significantly higher incidence of MetS than controls. Vitiligo per se can be considered a risk factor for MetS and IR. Therefore, regular follow-up and early metabolic derangement diagnoses are mandatory.

A comprehensive meta-analysis and prioritization study to identify vitiligo associated coding and non-coding SNV candidates using web-based bioinformatics tools

Vitiligo is a prevalent depigmentation disorder affecting around 1% of the general population. So far, various Genome Wide Association Studies (GWAS) and Candidate Gene Association Studies (CGAS) have identified several single nucleotide variants (SNVs) as a risk factor for vitiligo. Nonetheless, little has been discerned regarding their direct functional significance to the disease pathogenesis. In this study, we did extensive data mining and downstream analysis using several experimentally validated datasets like GTEx Portal and web tools like rSNPBase, RegulomeDB, HaploReg and STRING to prioritize 13 SNVs from a set of 291SNVs that have been previously reported to be associated with vitiligo. We also prioritized their underlying/target genes and tried annotating their functional contribution to vitiligo pathogenesis. Our analysis revealed genes like FGFR10P, SUOX, CDK5RAP1 and RERE that have never been implicated in vitiligo previously to have strong potentials to contribute to the disease pathogenesis. The study is the first of its kind to prioritize and functionally annotate vitiligo-associated GWAS and CGAS SNVs and their underlying/target genes, based on functional data available in the public domain database.

Current Concepts of Vitiligo Immunopathogenesis

Vitiligo is an acquired immune-mediated disorder of pigmentation clinically characterized by well-defined depigmented or chalk-white macules and patches on the skin. The prevalence of vitiligo varies by geographical area, affecting 0.5% to 2% of the population. The disease imposes a significant psychological burden due to its major impact on patients’ social and emotional aspects of life. Given its autoimmune background, vitiligo is frequently associated with other autoimmune diseases or immune-mediated diseases. Vitiligo is a multifaceted disorder that involves both genetic predisposition and environmental triggers. In recent years, major predisposing genetic loci for the development of vitiligo have been discovered. The current findings emphasize the critical role of immune cells and their mediators in the immunopathogenesis of vitiligo. Oxidative-stress-mediated activation of innate immunity cells such as dendritic cells, natural killer, and ILC-1 cells is thought to be a key event in the early onset of vitiligo. Innate immunity cells serve as a bridge to adaptive immunity cells including T helper 1 cells, cytotoxic T cells and resident memory T cells. IFN-γ is the primary cytokine mediator that activates the JAK/STAT pathway, causing keratinocytes to produce the key chemokines CXCL9 and CXCL10. Complex interactions between immune and non-immune cells finally result in apoptosis of melanocytes. This paper summarizes current knowledge on the etiological and genetic factors that contribute to vitiligo, with a focus on immunopathogenesis and the key cellular and cytokine players in the disease’s inflammatory pathways.

Multi-Trait Genetic Analysis Identifies Autoimmune Loci Associated with Cutaneous Melanoma

Genome-wide association studies (GWAS) have identified a number of risk loci for cutaneous melanoma. Cutaneous melanoma shares overlapping genetic risk (genetic correlation) with a number of other traits, including its risk factors such as sunburn propensity. This genetic correlation can be exploited to identify additional cutaneous melanoma risk loci by multitrait analysis of GWAS (MTAG). We used bivariate linkage disequilibrium-score regression score regression to identify traits that are genetically correlated with clinically confirmed cutaneous melanoma and then used publicly available GWAS for these traits in a multitrait analysis of GWAS. Multitrait analysis of GWAS allows GWAS to be combined while accounting for sample overlap and incomplete genetic correlation. We identified a total of 74 genome-wide independent loci, 19 of them were not previously reported in the input cutaneous melanoma GWAS meta-analysis. Of these loci, 55 were replicated (P < 0.05/74, Bonferroni-corrected P-value in two independent cutaneous melanoma replication cohorts from Melanoma Institute Australia and 23andMe, Inc. Among the, to our knowledge, previously unreported cutaneous melanoma loci are ones that have also been associated with autoimmune traits including rs715199 near LPP and rs10858023 near AP4B1. Our analysis indicates genetic correlation between traits can be leveraged to identify new risk genes for cutaneous melanoma.

Zusammenhang zwischen Vitiligo und wichtigen Komponenten des metabolischen Syndroms: eine systematische Übersicht und Metaanalyse

HINTERGRUND UND ZIELE

Ziel dieser Studie war die Untersuchung des Zusammenhangs zwischen Vitiligo und dem metabolischen Syndrom (MetS) sowie dessen relevanten Komponenten.

MATERIAL UND METHODEN

Die Datenbanken PubMed, Web of Science, Cochrane Library und Embase wurden von deren Beginn bis zum 30. März 2021 nach relevanten Studien durchsucht. Querschnitts- und Fall-Kontroll-Studien, die entweder die Prävalenz oder die Odds-Ratio [OR] des MetS oder seiner Komponenten bei Vitiligo-Patienten berichteten, wurden eingeschlossen. Die Daten wurden entsprechend der Heterogenität entweder mit einem Zufallseffektmodell oder einem Modell mit festen Effekten gepoolt.

ERGEBNISSE

Es wurden 30 Studien mit insgesamt 28.325 Vitiligo-Patienten eingeschlossen. Signifikante Zusammenhänge wurden zwischen Vitiligo und Diabetes mellitus (gepoolte OR, 3,30; 95 %-Konfidenzintervall [KI], 2,10-5,17) sowie zwischen Vitiligo und Adipositas (gepoolte OR, 2,08; 95 %-KI, 1,40-3,11) ermittelt. Die Gesamtprävalenz der Hypertonie bei Patienten mit Vitiligo betrug 19,0 % (95 %-KI, 2,0 %-36,0 %).

SCHLUSSFOLGERUNGEN

Unserer Ergebnisse lassen auf einen Zusammenhang zwischen Vitiligo und Diabetes mellitus sowie Hypertonie schließen. Dermatologen wird empfohlen diese Zusammenhänge zu berücksichtigen, um potenzielle Begleiterkrankungen bei Vitiligo-Patienten zeitnah zu identifizieren. Zudem wird Vitiligo-Patienten empfohlen, Parameter wie BMI, Blutzuckerspiegel und Blutdruck zu überwachen und bei auffälligen Veränderungen dieser Parameter unverzüglich einen Spezialisten zu konsultieren.

Association between vitiligo and relevant components of metabolic syndrome: a systematic review and meta-analysis

BACKGROUND AND OBJECTIVES

This study aimed to investigate the association of vitiligo with metabolic syndrome (MetS) and its relevant components.

MATERIAL AND METHODS

We searched PubMed, Web of Science, Cochrane Library and Embase databases from inception to March 30, 2021, for relevant studies. Cross-sectional and case-control studies that reported either the prevalence or odds ratio [OR] of MetS or its components in vitiligo patients were included. Data were pooled using either random-effects model or fixed-effects model according to the heterogeneity.

RESULTS

Thirty studies with a total of 28,325 vitiligo patients were included. Significant associations were found between vitiligo and diabetes mellitus (pooled OR, 3.30; 95 % confidence interval [CI], 2.10-5.17) and between vitiligo and obesity (pooled OR, 2.08; 95 % CI, 1.40-3.11). The overall prevalence of hypertension in the patients with vitiligo was 19.0 % (95 % CI, 2.0 %-36.0 %).

CONCLUSIONS

Our findings suggest the association of vitiligo with diabetes mellitus, obesity, and hypertension. It is recommended for dermatologists to take these associations into account so as to identify potential comorbidities promptly in vitiligo patients. Additionally, vitiligo patients are advised to monitor the indexes including BMI, blood glucose, and blood pressure levels and the consultation with specialists is necessary upon abnormal changes of these indexes.

Association between exonic polymorphisms of human leukocyte antigen-G gene and non-segmental vitiligo in the Korean population

BACKGROUND

Vitiligo is a pigmentary skin disorder characterised by a chronic and progressive loss of melanocytes. Although several theories have been suggested to the pathogenesis of vitiligo, an autoimmune process leading to melanocyte destruction appears most likely. Human leukocyte antigen-G is a non-classic, major histocompatibility complex Class I molecule that plays an important role in the suppression of the immune response. Several recent studies have provided evidences that polymorphisms in the human leukocyte antigen-G gene might be related with autoimmune diseases.

OBJECTIVES

The aim of this study was to decide whether exonic single nucleotide polymorphisms in human leukocyte antigen-G contribute to the risk of developing non-segmental vitiligo in the Korean population.

METHODS

To evaluate the associations between exonic single nucleotide polymorphisms (rs1630223 [Ala5Ala] and rs12722477 [Leu134Ile]) of human leukocyte antigen-G and vitiligo, 244 patients with vitiligo and 398 healthy controls were recruited. Genotyping was performed using Fluidigm 192.24 Dynamic Array with EP1 (Fluidigm Corp., CA). The SNP type assay (Fluidigm Corp., CA), which employs allele-specifically designed fluorescences (FAM or VIC) primers and a common reverse primer was applied and the data were analysed using the EP1 single nucleotide polymorphisms genotyping analysis software to obtain genotype calls.

RESULTS

Two exonic single nucleotide polymorphisms (rs1630223 and rs12722477) exhibited significant associations with susceptibility and remained a statistically significant association following Bonferroni correction. These two single nucleotide polymorphisms were located within a block of linkage disequilibrium. Haplotypes G-C and A-A comprising rs1630223 and rs12722477 demonstrated a significant association with non-segmental vitiligo.

LIMITATIONS

The protein expression level of patients with vitiligo and controls was not studied and a replication study of the genetic association in an independent group was not managed.

CONCLUSION

Our results suggest that exonic human leukocyte antigen-G polymorphisms (rs1630223 and rs12722477) are associated with the development of non-segmental vitiligo.

Association of genetic variants of the vitamin D receptor gene with vitiligo in a tertiary care center in a Saudi population: a case-control study

BACKGROUND

Vitiligo is a common cutaneous disorder of the skin and hair caused by a systemic depigmentation disorder that affects 1% of the population or less due to its onset in early adulthood. Meta-analyses have documented a linkage between vitiligo and the vitamin D receptor (VDR) gene.

OBJECTIVE

Investigate the relationship between the ApaI, BsmI, FokI and TaqI genetic variants in the VDR gene with vitiligo in a Saudi population.

DESIGN

Case-control.

SETTING

Single tertiary care center.

PATIENT AND METHODS

The case-control study was carried out between January 2015-December 2015 in Saudi vitiligo patients and healthy controls. VDR genetic variants or polymorphisms (ApaI, BsmI, FokI and TaqI) were genotyped by polymerase chain reaction-restriction fragment length analysis followed by 3% agarose gel electrophoresis. Applicable statistical methods were used to assess relationships between vitiligo cases and controls.

MAIN OUTCOM MEASURE

Effect of genotype distribution among four single nucleotide polymorphisms.

SAMPLE SIZE

152 vitiligo (median [IQR] 23 [19] years) patients and 159 healthy controls (45 [28.5] years).

RESULTS

We found an association of vitiligo with ApaI and BsmI polymorphisms (P<.05). However, a decreased risk was noted in vitiligo patients with FokI and TaqI polymorphisms and in the diplotype and haplotype analysis within males and females. A positive association with vitiligo was observed in ACAC and AC (adjusted by gender) haplotypes (P<.05). The strongest linkage disequilibrium was observed between rs79785232 (ApaI) and rs731236 (TaqI) polymorphisms (r²=.83), followed by rs2228570 (FokI) and rs1544410 (BsmI) polymorphisms (r²=.53).

CONCLUSIONS

Our results confirm an association of vitiligo with ApaI and BsmI polymorphisms and fail to show an association in TaqI and FokI polymorphism with vitiligo. Additional studies need to be carried out in different Arab populations to determine whether the polymorphisms are present.

LIMITATIONS

Controls not age matched, small sample size, lack of biochemical parameters.

CONFLICT OF INTEREST

None.

Variations in TAP1 and PSMB9 Genes Involved in Antigen Processing and Presentation Increase the Risk of Vitiligo in the Saudi Community

Background

The antigen processing 1 (TAP1) and proteasome 20S subunit beta 9 (PSMB9) genes are associated with strong susceptibility to many autoimmune diseases. Here, we explored whether TAP1/PSMB9 genetic variants, individually or combined, affected susceptibility to the complex, autoimmune-based skin disorder vitiligo.

Methods

Samples of genomic DNA from buccal cells of 172 patients with vitiligo and 129 healthy controls were analyzed using TaqMan™ genotyping assays for the TAP1 rs1135216 (A>G) and PSMB9 rs17587 (A>G) single nucleotide polymorphisms (SNPs). SNPStats software (https://www.snpstats.net) was utilized to choose the best interactive inheritance mode for selected SNPs.

Results

The genotype frequencies for the TAP1 rs1135216 and PSMB9 rs17587 SNPs were in Hardy-Weinberg equilibrium for cases (P= 0.11 and P= 0.10, respectively) but not for controls (P< 0.05). The TAP1 rs1135216 (D637G) and PSMB9 rs17587 (R60H) SNPs increased the risk of vitiligo four-fold and two-fold, respectively (odds ratio [OR]= 4.6; 95% confidence interval [CI], 3.2-6.5; P< 0.0001 and OR= 2.2; 95% CI, 1.5-3.1; P< 0.0001). The recessive model (G/G-D/G versus D/D) and the codominant model (R/R versus R/H) were the best models of inheritance for the rs113526 and rs17587 SNPs, respectively (OR= 16.4; 95% CI, 2.0-138; P= 0.0006 and OR= 1.7; 95% CI, 0.3-1.8; P= 0.013). Vulgaris, focal vulgaris, and acryl/acrofacial were the most common vitiligo subtypes in our sample (51%, 21%, and 19%, respectively). Heterozygous rs113526 (637D/G) and rs17587 (60R/H) were the most common genotypes in most vitiligo subtypes. The heterozygous 637D/G genotype and the 637G variant allele were significantly more common in patients with active disease than in patients with stable disease (P= 0.000052 and P= 0.0063, respectively).

Conclusion

Our findings suggest a crucial role for TAP1 rs1135216 and PSMB9 rs17587 in the risk and progression of vitiligo in the Saudi community. Genomic analyses are needed to identify more candidate genes and more genetic variants associated with vitiligo.

Cognitive Process of Psoriasis and Its Comorbidities: From Epidemiology to Genetics

Psoriasis (PsO) is a chronic inflammatory skin disease that affects approximately 2% of the population all over the world. Comorbidities of PsO have increasingly garnered more interest in the past decades. Compared with the normal population, the incidences of comorbidities are higher among patients with PsO. In the last 20 years, researchers have focused on studying the genetic components of PsO, and genetic associations between PsO and its comorbidities were elucidated. This review provides an in-depth understanding and summarization of the connection between PsO and its comorbidities from the perspectives of epidemiology and genetics. Further understanding of PsO and its comorbidities will promote research on the pathogenesis, drug development, novel therapy methods, and personalized and precision treatment of PsO and its comorbidities.

Equine vitiligo-like depigmentation in grey horses is related to genes involved in immune response and tumor metastasis

Background

In horses, the autoimmune disease vitiligo is characterized by the loss of melanocytes and results in patchy depigmentation of the skin around the eyes, muzzle and the perianal region. Vitiligo-like depigmentation occurs predominantly in horses displaying the grey coat colour and is observed at a prevalence level of 26.0–67.0% in grey horses compared with only 0.8–3.5% in non-grey horses. While the polygenetic background of this complex disease is well documented in humans, the underlying candidate genes for this skin disorder in horses remain unknown. In this study we aim to perform a genome-wide association study (GWAS) for identifying putative candidate loci for vitiligo-like depigmentation in horses.

Methods

In the current study, we performed a GWAS analysis using high-density 670 k single nucleotide polymorphism (SNP) data from 152 Lipizzan and 104 Noriker horses, which were phenotyped for vitiligo-like depigmentation by visual inspection. After quality control 376,219 SNPs remained for analyses, the genome-wide Bonferroni corrected significance level was p < 1.33e-7.

Results

We identified seven candidate genes on four chromosomes (ECA1, ECA13, ECA17, ECA20) putatively involved in vitiligo pathogenesis in grey horses. The highlighted genes PHF11, SETDB2, CARHSP1 and LITAFD, are associated with the innate immune system, while the genes RCBTB1, LITAFD, NUBPL, PTP4A1, play a role in tumor suppression and metastasis. The antagonistic pathogenesis of vitiligo in relation to cancer specific enhanced cell motility and/or metastasis on typical melanoma predilection sites underlines a plausible involvement of RCBTB1, LITAFD, NUBPL, and PTP4A1.

Conclusions

The proposed candidate genes for equine vitiligo-like depigmentation, indicate an antagonistic relation between vitiligo and tumor metastasis in a horse population with higher incidence of melanoma. Further replication and expression studies should lead to a better understanding of this skin disorder in horses.

Autoimmunity in vitiligo: Therapeutic implications and opportunities

Vitiligo is an acquired chronic pigmentary disorder affecting the melanocytes, mainly in the skin and mucosae. It occurs due to the dynamic interaction between genetic and environmental factors leading to autoimmune destruction of melanocytes. Defects in melanocyte adhesion and increased oxidative stress further augment the immune response in vitiligo. It is a cosmetically disfiguring condition with a substantial psychological burden. Its autoimmune nature with resultant chronicity, variable responses to therapeutic modalities, and frequent recurrences have further diminished the quality of life. Hence, treatment should aim to provide more extended remission periods, prevent recurrences, provide good cosmetic outcomes and ensure patient satisfaction. These treatment goals seem plausible with the recent progress in our understanding of the complex pathogenic mechanisms underlying vitiligo at a molecular and genetic level. We provide a literature review of the pathogenic mechanisms and the therapies targeting these mechanisms.

Granzyme B prevents aberrant IL-17 production and intestinal pathogenicity in CD4+ T cells

CD4⁺ T cell activation and differentiation are important events that set the stage for proper immune responses. Many factors are involved in the activation and differentiation of T cells, and these events are tightly controlled to prevent unwanted and/or exacerbated immune responses that may harm the host. It has been well-documented that granzyme B, a potent serine protease involved in cell-mediated cytotoxicity, is readily expressed by certain CD4⁺ T cells, such as regulatory T cells and CD4⁺CD8αα⁺ intestinal intraepithelial lymphocytes, both of which display cytotoxicity associated with granzyme B. However, because not all CD4⁺ T cells expressing granzyme B are cytotoxic, additional roles for this protease in CD4⁺ T cell biology remain unknown. Here, using a combination of in vivo and in vitro approaches, we report that granzyme B-deficient CD4⁺ T cells display increased IL-17 production. In the adoptive transfer model of intestinal inflammation, granzyme B-deficient CD4⁺ T cells triggered a more rapid disease onset than their WT counterparts, and presented a differential transcription profile. Similar results were also observed in granzyme B-deficient mice infected with Citrobacter rodentium. Our results suggest that granzyme B modulates CD4⁺ T cell differentiation, providing a new perspective into the biology of this enzyme.

Translational Research in Vitiligo

Vitiligo is a disease of the skin characterized by the appearance of white spots. Significant progress has been made in understanding vitiligo pathogenesis over the past 30 years, but only through perseverance, collaboration, and open-minded discussion. Early hypotheses considered roles for innervation, microvascular anomalies, oxidative stress, defects in melanocyte adhesion, autoimmunity, somatic mosaicism, and genetics. Because theories about pathogenesis drive experimental design, focus, and even therapeutic approach, it is important to consider their impact on our current understanding about vitiligo. Animal models allow researchers to perform mechanistic studies, and the development of improved patient sample collection methods provides a platform for translational studies in vitiligo that can also be applied to understand other autoimmune diseases that are more difficult to study in human samples. Here we discuss the history of vitiligo translational research, recent advances, and their implications for new treatment approaches.

Comprehensive Analysis of Cell Population Dynamics and Related Core Genes During Vitiligo Development

Vitiligo is a common immune-related depigmentation condition, and its pathogenesis remains unclear. This study used a combination of bioinformatics methods and expression analysis techniques to explore the relationship between immune cell infiltration and gene expression in vitiligo. Previously reported gene expression microarray data from the skin (GSE53146 and GSE75819) and peripheral blood (GSE80009 and GSE90880) of vitiligo patients and healthy controls was used in the analysis. R software was used to filter the differentially expressed genes (DEGs) in each dataset, and the KOBAS 2.0 server was used to perform functional enrichment analysis. Compared with healthy controls, the upregulated genes in skin lesions and peripheral blood leukocytes of vitiligo patents were highly enriched in immune response pathways and inflammatory response signaling pathways. Immunedeconv software and the EPIC method were used to analyze the expression levels of marker genes to obtain the immune cell population in the samples. In the lesional skin of vitiligo patients, the proportions of macrophages, B cells and NK cells were increased compared with healthy controls. In the peripheral blood of vitiligo patients, CD8+ T cells and macrophages were significantly increased. A coexpression analysis of the cell populations and DEGs showed that differentially expressed immune and inflammation response genes had a strong positive correlation with macrophages. The TLR4 receptor pathway, interferon gamma-mediated signaling pathway and lipopolysaccharide-related pathway were positively correlated with CD4+ T cells. Regarding immune response-related genes, the overexpression of IFITM2, TNFSF10, GZMA, ADAMDEC1, NCF2, ADAR, SIGLEC16, and WIPF2 were related to macrophage abundance, while the overexpression of ICOS, GPR183, RGS1, ILF2 and CD28 were related to CD4+ T cell abundance. GZMA and CXCL10 expression were associated with CD8+ T cell abundance. Regarding inflammatory response-related genes, the overexpression of CEBPB, ADAM8, CXCR3, and TNIP3 promoted macrophage infiltration. Only ADORA1 expression was associated with CD4+ T cell infiltration. ADAM8 and CXCL10 expression were associated with CD8+ T cell abundance. The overexpression of CCL18, CXCL10, FOS, NLRC4, LY96, HCK, MYD88, and KLRG1, which are related to inflammation and immune responses, were associated with macrophage abundance. We also found that immune cells infiltration in vitiligo was associated with antigen presentation-related genes expression. The genes and pathways identified in this study may point to new directions for vitiligo treatment.

Variations in TAP1 and PSMB9 Genes Involved in Antigen Processing and Presentation Increase the Risk of Vitiligo in the Saudi Community

BACKGROUND

The antigen processing 1 (TAP1) and proteasome 20S subunit beta 9 (PSMB9) genes are associated with strong susceptibility to many autoimmune diseases. Here, we explored whether TAP1/PSMB9 genetic variants, individually or combined, affected susceptibility to the complex, autoimmune-based skin disorder vitiligo.

METHODS

Samples of genomic DNA from buccal cells of 172 patients with vitiligo and 129 healthy controls were analyzed using TaqMan™ genotyping assays for the TAP1 rs1135216 (A>G) and PSMB9 rs17587 (A>G) single nucleotide polymorphisms (SNPs). SNPStats software (https://www.snpstats.net) was utilized to choose the best interactive inheritance mode for selected SNPs.

RESULTS

The genotype frequencies for the TAP1 rs1135216 and PSMB9 rs17587 SNPs were in Hardy-Weinberg equilibrium for cases (P= 0.11 and P= 0.10, respectively) but not for controls (P< 0.05). The TAP1 rs1135216 (D637G) and PSMB9 rs17587 (R60H) SNPs increased the risk of vitiligo four-fold and two-fold, respectively (odds ratio [OR]= 4.6; 95% confidence interval [CI], 3.2-6.5; P< 0.0001 and OR= 2.2; 95% CI, 1.5-3.1; P< 0.0001). The recessive model (G/G-D/G versus D/D) and the codominant model (R/R versus R/H) were the best models of inheritance for the rs113526 and rs17587 SNPs, respectively (OR= 16.4; 95% CI, 2.0-138; P= 0.0006 and OR= 1.7; 95% CI, 0.3-1.8; P= 0.013). Vulgaris, focal vulgaris, and acryl/acrofacial were the most common vitiligo subtypes in our sample (51%, 21%, and 19%, respectively). Heterozygous rs113526 (637D/G) and rs17587 (60R/H) were the most common genotypes in most vitiligo subtypes. The heterozygous 637D/G genotype and the 637G variant allele were significantly more common in patients with active disease than in patients with stable disease (P= 0.000052 and P= 0.0063, respectively).

CONCLUSION

Our findings suggest a crucial role for TAP1 rs1135216 and PSMB9 rs17587 in the risk and progression of vitiligo in the Saudi community. Genomic analyses are needed to identify more candidate genes and more genetic variants associated with vitiligo.

Analysis of symmetricity in the three different (sagittal, transverse and frontal) planes in generalized nonsegmental vitiligo

BACKGROUND

Nonsegmental vitiligo is defined as being "often symmetrical", however, no work has tackled the point as to how valid it is to depend upon the concept of symmetricity in generalized nonsegmental vitiligo.

AIMS

To investigate vitiligo symmetry, taking into account sites of predilection, the clinical characteristics of patients were studied.

METHODS

This multicentric study included 712 nonsegmental vitiligo patients with 2876 examined lesions. Three models were drawn for each patient. Sagittal, transverse and frontal planes were drawn to divide the body into right/left, upper/lower and anterior/posterior halves respectively. Patients were examined by Wood's light and analyzed for symmetry.

RESULTS

Bilateral involvement was present in 78% (P < 0.001). Studying the similarity of clinical involvement in the upper and lower body parts revealed that such similarity was present in 38%, with a significant positive association in some areas. Studying clinical similarity in the anteroposterior distribution pattern revealed a significant positive association in 11%.

LIMITATIONS

Relatively low number of patients.

CONCLUSIONS

We found significant bilateral symmetry in the lesions of 78% of vitiligo patients. Our work could aid in drawing the anticipated vitiligo map in patients with active disease, helping in increasing our understanding of the clinical behaviour of this disease.

Association of multiple sclerosis with vitiligo: a systematic review and meta-analysis

Polyautoimmunity implicates that some autoimmune diseases share common etiopathogenesis. Some studies have reported an association between multiple sclerosis (MS) and vitiligo; meanwhile, other studies have failed to confirm this association. We performed a systemic review and meta-analysis to examine the association of MS with vitiligo. We searched the MEDLINE and Embase databases on March 8, 2020 for relevant case–control, cross-sectional, and cohort studies. The Newcastle–Ottawa Scale was used to evaluate the risk of bias of the included studies. Where applicable, we performed a meta-analysis to calculate the pooled odds ratio (OR) for case–control/cross-sectional studies and risk ratio for cohort studies with 95% confidence interval (CI). Our search identified 285 citations after removing duplicates. Six case–control studies with 12,930 study subjects met our inclusion criteria. Our meta-analysis found no significant association of MS with prevalent vitiligo (pooled OR 1.33; 95% CI 0.80‒2.22). Analysis of the pooled data failed to display any increase of prevalent vitiligo in MS patients compared with controls. Ethnic and genetic factors may play an important role for sporadically observed associations between MS and vitiligo. Future studies of this association should therefore consider stratification by ethnic or genetic factors.

Genome-wide association study identifies CDH13 as a susceptibility gene for rhododendrol-induced leukoderma

Racemic RS-4-(4-hydroxyphenyl)-2-butanol (rhododendrol; trade name: Rhododenol [RD]), which is used in topical skin-lightening cosmetics, was unexpectedly reported in Japan to induce leukoderma or vitiligo called RD-induced leukoderma (RIL) after repeated application. To our knowledge, no studies have investigated chemical-induced vitiligo pathogenesis on a genome-wide scale. Here, we conducted a genome-wide association study (GWAS) for 147 cases and 112 controls. CDH13, encoding a glycosylphosphatidylinositol-anchored protein called T-cadherin (T-cad), was identified as the strongest RIL susceptibility gene. RD sensitivity was remarkably increased by T-cad knockdown in cultured normal human melanocytes. Furthermore, we confirmed tyrosinase upregulation and downregulation of the anti-apoptotic molecules (BCL-2 and BCL-XL), suggesting that T-cad is associated with RD via tyrosinase or apoptotic pathway regulation. Finally, monobenzyl ether of hydroquinone sensitivity also tended to increase with T-cad knockdown, suggesting that the T-cad could be a candidate susceptibility gene for RIL and other chemical-induced vitiligo forms. This is the first GWAS for chemical-induced vitiligo, and it could be a useful model for studying the disease's genetic aspects.

Intracellular virus sensor MDA5 exacerbates vitiligo by inducing the secretion of chemokines in keratinocytes under virus invasion

Vitiligo is a disfiguring disease featuring chemokines-mediated cutaneous infiltration of autoreactive CD8+ T cells that kill melanocytes. Copious studies have indicated that virus invasion participates in the pathogenesis of vitiligo. IFIH1, encoding MDA5 which is an intracellular virus sensor, has been identified as a vitiligo susceptibility gene. However, the specific role of MDA5 in melanocyte death under virus invasion is not clear. In this study, we first showed that the expression of anti-CMV IgM and MDA5 was higher in vitiligo patients than healthy controls. Then, by using Poly(I:C) to imitate virus invasion, we clarified that virus invasion significantly activated MDA5 and further potentiated the keratinocyte-derived CXCL10 and CXCL16 which are the two vital chemokines for the cutaneous infiltration of CD8+ T cells in vitiligo. More importantly, IFN-β mediated by the MDA5-MAVS-NF-κB/IRF3 signaling pathway orchestrated the secretion of CXCL10 via the JAK1-STAT1 pathway and MDA5-meidiated IRF3 transcriptionally induced the production of CXCL16 in keratinocytes under virus invasion. In summary, our results demonstrate that MDA5 signaling orchestrates the aberrant skin immunity engaging in melanocyte death via mediating CXCL10 and CXCL16 secretion, which supports MDA5 as a potential therapeutic target for vitiligo under virus invasion.

The Role of TRM Cells in the Pathogenesis of Vitiligo-A Review of the Current State-Of-The-Art

Vitiligo is the most common hypopigmentation disease affecting both the skin and mucous membranes. The pathogenesis of this disorder is complex and involves the influence of genetic and environmental factors, oxidative stress, and autoimmune responses. Recent studies have indicated that skin lesions observed in vitiligo tend to recur in the same places where they were found before treatment. This phenomenon is explained by the presence of recently discovered tissue-resident memory T cells (T_RM), whose primary function is to provide antiviral and antibacterial protection in non-lymphoid tissues. T_RM cells show the presence of CD49a, CD69, and CD103 markers on their surface, although not all of them express these particles. Due to their ability to produce and secrete perforin, IFN-γ, and granzyme B, T_RM cells demonstrate a cytotoxic effect on melanocytes, thus inducing depigmented lesions in the course of the vitiligo. It has been proved that the occurrence of T_RM cells largely depends on IL-15, which promotes the T_RM function ex vivo. The findings above, as well as their reference to the pathogenesis of autoimmune skin diseases will have a considerable influence on the development of new therapeutic strategies in the near future. This article presents an up-to-date review of information regarding the role of T_RM cells in the development and progression of vitiligo.

Vitiligo: A Review

Vitiligo, a common depigmenting skin disorder, has an estimated prevalence of 0.5–2% of the population worldwide. The disease is characterized by the selective loss of melanocytes which results in typical nonscaly, chalky-white macules. In recent years, considerable progress has been made in our understanding of the pathogenesis of vitiligo which is now clearly classified as an autoimmune disease. Vitiligo is often dismissed as a cosmetic problem, although its effects can be psychologically devastating, often with a considerable burden on daily life. In 2011, an international consensus classified segmental vitiligo separately from all other forms of vitiligo, and the term vitiligo was defined to designate all forms of nonsegmental vitiligo. This review summarizes the current knowledge on vitiligo and attempts to give an overview of the future in vitiligo treatment.

Primary DQ effect in the association between HLA and neurological syndromes with anti-GAD65 antibodies

The primary cause of neurological syndromes with antibodies against glutamic acid decarboxylase 65 (GAD65-Ab) is unknown, but genetic predisposition may exist as it is suggested by the co-occurrence in patients and their relatives of other organ-specific autoimmune diseases, notably type 1 diabetes mellitus (T1DM), and by the reports of a few familial cases. We analyzed the human leukocyte antigen (HLA) in 32 unrelated patients and compared them to an ethnically matched sample of 137 healthy controls. Four-digit resolution HLA alleles were imputed from available Genome Wide Association data, and full HLA next-generation sequencing-based typing was also performed. HLA DQA1*05:01-DQB1*02:01-DRB1*03:01 was the most frequent class II haplotype in patients (13/32, 41%). DQB1*02:01 was the only allele found to be significantly more common in patients than in controls (20/137, 15%, corrected p = 0.03, OR 3.96, 95% CI [1.54-10.09]). There was also a trend towards more frequent DQA1*05:01 among patients compared to controls (22/137, 16%; corrected p = 0.05, OR 3.54, 95% CI [1.40-8.91]) and towards a protective effect of DQB1*03:01 (2/32, 6% in patients vs. 42/137, 31% in control group; corrected p = 0.05, OR 0.15, 95% CI [0.02-0.65]). There was no significant demographic or clinical difference between DQ2 and non-DQ2 carriers (p > 0.05). Taken together, these findings suggest a primary DQ effect on GAD65-Ab neurological diseases, partially shared with other systemic organ-specific autoimmune diseases such as T1DM. However, it is likely that other non-HLA loci are involved in the genetic predisposition of GAD65-Ab neurological syndromes.

Expression of melanocortin 1 receptor before and after narrowband UVB phototherapy treatment in patients with stable vitiligo: A prospective study

Vitiligo is a disease characterized by skin depigmentation caused by the selective destruction of melanocytes. The melanocortin system participates as a regulator of melanogenesis and skin pigmentation. Narrowband UVB phototherapy (nb-UVB) is currently considered to be the gold standard and first choice treatment method for vitiligo vulgaris. The aim of the present study was to analyze the clinical and biochemical parameters of vitiligo, as well as to determine the expression of proopiomelanocortin (POMC), melanocortin 1 receptor (MC1R) and melanocortin 4 receptor (MC4R) genes in the skin of patients with stable vitiligo receiving nb-UVB phototherapy. Patient clinical and biochemical parameters, and the skin biopsies of 22 patients with stable vitiligo were analyzed. These biopsies were obtained before and after nb-UVB phototherapy. The genetic expression analysis of POMC, MC1R and MC4R genes was performed via RNA-Sequence analysis. A statistical evaluation of the clinical and biochemical parameters, the degree of response to treatment and the expression profiles of the melanocortin system genes were performed to identify their association with treatment response. A two-sided P≤0.05 value was considered to indicate a statistically significant difference. Alterations were observed in the expression profiles of MC1R following nb-UVB phototherapy (P≤0.05). In addition, elevated levels of triiodothyronine were associated with a poor response to nb-UVB phototherapy. In conclusion the current study revealed that nb-UVB phototherapy altered the expression profile of the MC1R gene.

Aggravation of depigmentation for a non-small-cell lung cancer patient with pre-existing vitiligo using anti-programmed cell death-1 therapy: case report

Immune checkpoint inhibitors can enhance the antitumor activity of the immune system by mainly promoting CD8⁺ T lymphocyte immune function. However, they can also induce immune-related adverse events, especially skin toxicity. Some studies found that patients with autoimmune or inflammatory disease are susceptible to immune checkpoint inhibitors and were associated with a significantly increased risk of immune-related adverse events. In our present report, we described a newly diagnosed non-small-cell lung cancer patient who suffered from focal vitiligo for approximately ten years and was treated with the anti-programmed cell death-1 receptor antibody camrelizumab (SHR-1210), which accelerated the aggravation of depigmentation of the skin over the whole body in just half a year.

Emerging drugs for the treatment of vitiligo

Introduction: Vitiligo is a relatively common autoimmune depigmenting disorder of the skin. There has been a great advance in understanding the pathological basis, which has led to the development and utilization of various new molecules in treating vitiligo. This review aims at a comprehensively describing the treatments available and the emerging treatment aspects and the scope for future developments.Areas covered: This study comprehensively summarizes the current concepts in the pathogenesis of vitiligo with special focus on the cytokine and signaling pathways, which are the targets for newer drugs. JAK kinase signaling pathways and the cytokines involved are the focus of vitiligo treatment in current research, followed by antioxidant mechanisms and repigmenting mechanisms. Topical immunosuppressants may be an alternative to steroids in localized vitiligo. Newer repigmenting agents like basic fibroblast growth factors, afamelanotide have been included and a special emphasis is laid on the upcoming targeted immunotherapy.Expert opinion: The treatment of vitiligo needs to be multimodal with emphasis on targeting different limbs of the pathogenesis. Topical and oral JAK inhibitors are the most promising new class of drugs currently available for treating vitiligo and acts best in conjunction with NB-UVB.

The Woronoff Ring in Psoriasis and the Mechanisms of Postinflammatory Hypopigmentation

The Woronoff ring is a ring-like hypopigmentation zone around regressing psoriasis lesions. Although it was first described more than 100 years ago, its aetiology has remained a mystery. Recent insights into the pathogenesis of psoriasis can now explain the origin of the Woronoff ring. Psoriasis involves an HLA-class I-restricted autoimmune response of CD8+ T cells against melanocytes in the epidermis. The pathogenic CD8+ T cells are not cytotoxic, but are characterized by the production of interleukin-17, interleukin-22 and tumour necrosis factor-α. Interleukin-17 and tumour necrosis factor-α act synergistically on melanocytes by increasing proliferation while inhibiting melanogenesis. This reduces the cellular melanin content despite an increased number of melanocytes in psoriatic lesions. As a consequence, during healing the prior influence of interleukin-17 and tumour necrosis factor-α, despite the increased density of melanocytes, leaves a hypopigmented zone at the edge of regressing psoriasis lesions, which becomes visible as the Woronoff ring. This mechanism can explain a long-discussed puzzling phenomenon in dermatology.

Genome-Wide Association Analysis Reveals Key Genes Responsible for Egg Production of Lion Head Goose

The lion head goose is one of the most important agricultural resources in China; however, its breeding process is relatively slow. In the present study, a genome-wide association study was performed for the genetic selection of egg production characters in lion head geese. We detected 30 single-nucleotide polymorphisms located in or near 30 genes that might be associated with egg production character, and quantitative real-time polymerase chain reaction was used to verify their expression level in lion head geese. The results showed that the expression levels of CRTC1 (encoding CREB-regulated transcription coactivator 1), FAAH2 (encoding fatty acid amide hydrolase 2), GPC3 (encoding glypican 3), and SERPINC1 (encoding serpin family C member 1) in high egg production population were significantly lower than those in the low egg production populations (*P < 0.05). The expression levels of CLPB (encoding caseinolytic peptidase B protein homolog), GNA12 (encoding guanine nucleotide-binding protein subunit alpha-12), and ZMAT5 (encoding zinc finger, matrin type 5) in the high egg production population were significantly higher than those in the low egg production populations (*P < 0.05). The expression of BMP4 (encoding bone morphogenetic protein 4), FRMPD3 (encoding FERM and PDZ domain containing 3), LIF (encoding leukemia inhibitory factor), and NFYC (encoding nuclear transcription factor Y subunit gamma) in the high egg production population were very significantly lower than those in the low egg production population (**P < 0.01). Our findings provide an insight into the economic traits of lion head goose. These candidate genes might be valuable for future breeding improvement.

The relationship between stress and vitiligo: Evaluating perceived stress and electronic medical record data

Vitiligo is a T-cell mediated skin disorder characterized by progressive loss of skin color. In individuals genetically predisposed to the disease, various triggers contribute to the initiation of vitiligo. Precipitating factors can stress the skin, leading to T-cell activation and recruitment. Though hereditary factors are implicated in the pathogenesis of vitiligo, it is unknown whether precipitating, stressful events play a role in vitiligo. To understand this, we utilized a validated perceived stress scale (PSS) to measure this parameter in vitiligo patients compared to persons without vitiligo. Additionally, we probed a clinical database, using a knowledge linking software called ROCKET, to gauge stress-related conditions in the vitiligo patient population. From a pool of patients in an existing database, a hundred individuals with vitiligo and twenty-five age- and sex-matched comparison group of individuals without vitiligo completed an online survey to quantify their levels of perceived stress. In parallel, patients described specifics of their disease condition, including the affected body sites, the extent, duration and activity of their vitiligo. Perceived stress was significantly higher among vitiligo individuals compared to those without vitiligo. ROCKET analyses suggested signs of metabolic-related disease (i.e., ‘stress’) preceding vitiligo development. No correlation was found between perceived stress and the stage or the extent of disease, suggesting that elevated stress may not be a consequence of pigment loss alone. The data provide further support for stress as a precipitating factor in vitiligo development.

Primary Immunodeficiency with Severe Multi-Organ Immune Dysregulation

Polyglandular autoimmune syndrome type 1, also known as autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED), is a rare primary immunodeficiency disorder with multi-organ involvement. Besides for being predisposed to severe life-threatening infections, patients with APECED are also prone to organ impairment secondary to severe autoimmunity. As this is an autosomal recessive disorder, a biallelic mutation in the AIRE gene is responsible for APECED. The author presents a case of APECED with a single AIRE mutation. Whole exome sequencing identified a mutation in the BTNL2 gene that the author suggests may have contributed to the patient's presentation.

Vitiligo susceptibility at workplace and in daily life: the contribution of oxidative stress gene polymorphisms

Objective

Vitiligo is a frequently underestimated and little known dermal disease whose symptoms appear as white patches on several skin areas of the body. In this review, the impact of idiopathic and chemical-induced vitiligo at workplace and in daily life is discussed. Also, the influence of selected oxidative stress gene polymorphisms on melanocyte damage is described to understand their involvement in the disease.

Methods

A PubMed search was carried out to select the journal articles reporting an association between specific oxidative stress polymorphic genes and vitiligo.

Results

The double-null glutathione S-transferase T1 and M1 genotypes are associated with vitiligo while the relationship between nuclear factor erythroid 2-related factor 2, heme oxygenase, catalase and superoxide dismutase gene polymorphisms and the disease should be confirmed by further studies.

Conclusions

The polymorphic genes analysed here may have a role in the susceptibility of patients affected by vitiligo, while little is known about the affected workers, due to the lack of epidemiologic data on these subjects. However, the similarity of the skin lesions observed in both groups might have in common some genetic factors making all these individuals susceptible to the development of vitiligo, regardless of the disease-triggering factor.

Association of rs2111485 and rs1990760 Polymorphisms of Interferon Induced with Helicase C Domain 1 Gene with Hepatitis C Virus Clearance in Chinese Han Population

Interferon induced with helicase C domain 1 (IFIH1), which is a type of cytological RNA helicase protein and an important initiator of innate immune response to RNA virus infection, may play an important role in hepatitis C virus (HCV) infection outcomes. This study was conducted to investigate the association of IFIH1 gene polymorphisms with HCV clearance in Chinese Han population. A total of 1,527 subjects positive for anti-HCV and 357 chronic hepatitis C (CHC) patients were enrolled in this study. Two single nucleotide polymorphisms in IFIH1 gene (rs2111485 and rs1990760) were selected and genotyped by TaqMan real-time polymerase chain reaction. Haplotypes analysis was further performed by HaploView software and PHASE software. Our results demonstrated that the mutant alleles of rs2111485 (dominant model: odds ratio [OR] = 1.41, 95% confidence interval [CI] = 1.11-1.79) and rs1990760 (dominant model: OR = 1.63, 95% CI = 1.30-2.06) decreased the possibility of spontaneous HCV clearance, but it had no association with HCV clearance induced by interferon-alfa (IFN-α). And, CHC risk increased with the increasing number of unfavorable alleles (p_trend < 0.001). In addition, haplotype analysis also showed that the A-C protective haplotype (rs2111485-rs1997060) promoted spontaneous HCV clearance (p < 0.001). Variants of rs2111485 and rs1990760 at IFIH1 may be associated with spontaneous HCV clearance in Chinese Han population, but have no effect on HCV clearance induced by IFN-α.

VitiVar: A locus specific database of vitiligo associated genes and variations

Vitiligo is the most common skin pigmentation disorder which affects around 1% of the population worldwide. The disease has complex pathogenesis and is of multifactorial etiology, that finally culminates in patchy depigmentation of skin. Genetic contribution to the disease is well studied, however the information about multiple associated genes and contributing variations are scattered across the literature. To address this complex disorder affecting the skin, we systematically cataloged the genes and variations by creating a Locus Specific Database for vitiligo called, “VitiVar”. This comprehensive resource houses manually curated 322 genes and 254 variations, from 202 articles indexed in PubMed. We applied an integrative approach to stratify genes and variations to facilitate dissection of vitiligo pathogenesis by layering it with expression status in specific constituent cell types of skin and in-house vitiligo expression data. Finally, we were able to demonstrate the utility of VitiVar by generating a vitiligo interactome using GeneMANIA and overlaying the vitiligo and cell type specific information. This interaction network yielded 20 new genes (apart from 322 VitiVar genes) of which we were able to prioritize IFI27 and IFI6 for further validation. This, thereby makes VitiVar a comprehensive integrative platform in unravelling disease biology by providing meaningful leads for functional interrogation. VitiVar is freely accessible to the research community for prioritizing and validating the candidate genes and variations (http://vitivar.igib.res.in/).

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We developed a Vitiligo centric web resource cataloguing the associated genes and variations

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Overlaid the information of cell type specificity and expression status in Vitiliginous skin

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Utilizing the network approach, we prioritized IFI6 & IFI27 which could be functionally interrogated in disease pathology