Lymphocyte imbalance in vitiligo patients indicated by elevated CD4+/CD8+ T-cell ratio

Exploring the roles and potential therapeutic strategies of inflammation and metabolism in the pathogenesis of vitiligo: a mendelian randomization and bioinformatics-based investigation

Introduction

Vitiligo, a common autoimmune acquired pigmentary skin disorder, poses challenges due to its unclear pathogenesis. Evidence suggests inflammation and metabolism's pivotal roles in its onset and progression. This study aims to elucidate the causal relationships between vitiligo and inflammatory proteins, immune cells, and metabolites, exploring bidirectional associations and potential drug targets.

Methods

Mendelian Randomization (MR) analysis encompassed 4,907 plasma proteins, 91 inflammatory proteins, 731 immune cell features, and 1400 metabolites. Bioinformatics analysis included Protein-Protein Interaction (PPI) network construction, Gene Ontology (GO), and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis. Subnetwork discovery and hub protein identification utilized the Molecular Complex Detection (MCODE) plugin. Colocalization analysis and drug target exploration, including molecular docking validation, were performed.

Results

MR analysis identified 49 proteins, 39 immune cell features, and 59 metabolites causally related to vitiligo. Bioinformatics analysis revealed significant involvement in PPI, GO enrichment, and KEGG pathways. Subnetwork analysis identified six central proteins, with Interferon Regulatory Factor 3 (IRF3) exhibiting strong colocalization evidence. Molecular docking validated Piceatannol's binding to IRF3, indicating a stable interaction.

Conclusion

This study comprehensively elucidates inflammation, immune response, and metabolism's intricate involvement in vitiligo pathogenesis. Identified proteins and pathways offer potential therapeutic targets, with IRF3 emerging as a promising candidate. These findings deepen our understanding of vitiligo's etiology, informing future research and drug development endeavors.

The role of cytokines and vitamin D in vitiligo pathogenesis

Vitiligo is a pigment-related disease with a global prevalence of 0.2% to 1.8% associated with considerable burden on quality of life. The treatment is still a challenge because of relapses and/or incomplete re-pigmentation. Although the exact cause is still unclear, its pathogenesis seems to be justifiable with the autoimmune theory, supported by the results of clinical research. In this narrative review, we aimed to summarize the evidence related to cytokines and vitiligo development. This review is consisted of English articles published in PubMed and Google Scholar concerning levels of inflammatory mediators, especially interleukins, in vitiligo patients over the last 20 years. References of relevant articles were also considered for review. Crucial role of dysregulated levels of interleukins and their synergistic function to each other, in the onset or progression of the disease is evident. The theory of autoimmune vitiligo is reinforced by the results of the studies in the literature, due to the association of pathogenesis with increased secretion of pro-inflammatory mediators and reduction of anti-inflammatory mediators. Decreased vitamin D levels may have a considerable role in vitiligo development by affecting Th1- and Th17-related immune responses. Cytokines play an important role in the pathogenesis or progression of the disease. Moreover, we believe that decreased vitamin D level has a considerable role in vitiligo development by affecting Th1- and Th17-related immune responses.

Integrin Regulated Autoimmune Disorders: Understanding the Role of Mechanical Force in Autoimmunity

The pathophysiology of autoimmune disorders is multifactorial, where immune cell migration, adhesion, and lymphocyte activation play crucial roles in its progression. These immune processes are majorly regulated by adhesion molecules at cell–extracellular matrix (ECM) and cell–cell junctions. Integrin, a transmembrane focal adhesion protein, plays an indispensable role in these immune cell mechanisms. Notably, integrin is regulated by mechanical force and exhibit bidirectional force transmission from both the ECM and cytosol, regulating the immune processes. Recently, integrin mechanosensitivity has been reported in different immune cell processes; however, the underlying mechanics of these integrin-mediated mechanical processes in autoimmunity still remains elusive. In this review, we have discussed how integrin-mediated mechanotransduction could be a linchpin factor in the causation and progression of autoimmune disorders. We have provided an insight into how tissue stiffness exhibits a positive correlation with the autoimmune diseases’ prevalence. This provides a plausible connection between mechanical load and autoimmunity. Overall, gaining insight into the role of mechanical force in diverse immune cell processes and their dysregulation during autoimmune disorders will open a new horizon to understand this physiological anomaly.

Prolonged Peripheral Immunosuppressive Responses as Consequences of Random Amphetamine Treatment, Amphetamine Withdrawal and Subsequent Amphetamine Challenges in Rats

Drug-induced immunosuppression may underline increased hypothalamic-pituitary-adrenal axis response to stress observed following chronic psychostimulant treatment. However, the consequences of random amphetamine (AMPH) treatment, withdrawal and AMPH challenge after withdrawal on the peripheral immunity and systemic corticosterone response are unknown. In this study, the total blood and spleen leukocyte, lymphocyte, T, B, NK, TCD4+/TCD8+ cell numbers and ratio, pro-inflammatory interferon gamma (IFN-γ), and anti-inflammatory interleukin-4 (IL-4) production, and plasma corticosterone concentration in Wistar rats were investigated after: chronic, random AMPH/SAL treatment alone (20 injections in 60 days, 1 mg/kg b.w., i.p.), AMPH/SAL withdrawal (for 20 consecutive days after random AMPH/SAL exposure) or AMPH/SAL challenge after withdrawal (single injection after the AMPH/SAL withdrawal phase). The results showed blood and spleen leukopenia, lymphopenia, lower blood production of IFN-ɤ, and increased plasma corticosterone concentration after the AMPH treatment, which were more pronounced in the AMPH after withdrawal group. In contrast, an increased number of blood NK cells and production of IL-4 after chronic, random AMPH treatment alone, were found. Blood AMPH-induced leukopenia and lymphopenia were due to decreased total number of T, B lymphocytes and, at least in part, of granulocytes and monocytes. Moreover, decreases in the number of blood TCD4+ and TCD8+ lymphocytes both in the AMPH chronic alone and withdrawal phases, were found.The major findings of this study are that AMPH treatment after the long-term withdrawal from previous random AMPH exposure, accelerates the drug-induced immunosuppressive and systemic corticosterone responses, suggesting prolonged immunosuppressive effects and an increase in incidence of infectious diseases. Prolonged peripheral immunosuppressive responses as consequences of random amphetamine…The results indicate that the chronic and random AMPH exposure alone and the acute (single injection) challenge of the drug after the withdrawal phase induced long-term immunosuppressive effects, which were similar to those occurring during the stress response, and sensitized the peripheral immunosuppressive and corticosterone responses of the rat to the disinhibitory effects of this stressor.

T-Lymphocyte Subsets Alteration, Infection and Renal Outcome in Advanced Chronic Kidney Disease

Background: T-lymphocyte subsets reflect patients' immune status and are associated with adverse outcomes in various diseases. However, the association between T-lymphocyte subsets and major infection and renal outcome in chronic kidney disease (CKD) patients has not been well-addressed.

Methods: Patients diagnosed with stage 3–5 of non-dialysis CKD were recruited, and healthy subjects were selected as the controls. T-lymphocyte subsets (CD3⁺, CD4⁺, CD8⁺) were detected by flow cytometry, and the CD4⁺/CD8⁺ T cell ratio was then calculated. Patients were divided into the normal-level group and the low-level group according to the clinical reference value. The primary outcomes were the major infection and renal outcome.

Results: A total of 410 CKD patients were enrolled; the average age was 47.25 years. Compared to the healthy controls, the level of CD3⁺, CD4⁺, CD8⁺ T cells, and the CD4⁺/CD8⁺ T cell ratio were significantly decreased in CKD patients (p < 0.05). During the median follow-up of 2.56 (quartile interval 1.24–3.46) years, major infections occurred in 15.10% of the CKD patients. The incidence of infection was significantly higher in the low-level group of CD3⁺, CD4⁺ T cells, and CD4⁺/CD8⁺ T cell ratio compared with the normal level groups. Kaplan-Meier analysis showed that the lower level of CD3⁺, CD4⁺ T cells, and CD4⁺/CD8⁺T cell ratio is associated with a greater risk of infection. Cox regression analysis further confirmed that low CD3⁺, CD4⁺ T cells, and CD4⁺/CD8⁺ T cell ratio were independent risk factors of infection in CKD patients. Moreover, during the follow-up, renal events occurred in 37.50% of patients. Kaplan-Meier analysis indicated that low levels of CD3⁺, CD4⁺, and CD8⁺ T cells are significantly associated with renal outcome in CKD patients. Cox regression analysis showed that low level of CD3⁺ T cells (HR = 2.407, 95% CI: 1.664–3.482, p < 0.001), CD4⁺ T cells (HR = 2.397, 95% CI: 1.633–3.518, p < 0.001) and CD8⁺ T cells (HR = 2.416, 95% CI: 1.476–3.955, p < 0.001) were independent risk factors for renal outcome after multivariable-adjusted.

Conclusion: CKD patients had a defect in T-lymphocyte subpopulation. T-lymphocyte subsets were closely associated with infection and renal outcome in CKD patients. Suggesting T-lymphocyte subsets are independent predictors of infection and renal outcome in CKD patients.

Investigation of the Role of Interleukin 6 in Vitiligo Pathogenesis

Interleukin-6 (IL6) is involved in pathogenesis of several autoimmune disorders including vitiligo. Hence, we aimed to investigate the association of IL6 -174 G/C and -572 G/C polymorphisms and its transcript levels with vitiligo; to evaluate the effect of IL-6 on normal human melanocyte (NHM) viability and expression of IL6R, MITF and TYR. IL6 -174 G/C and -572 G/C polymorphisms were genotyped by ARMS-PCR and PCR-RFLP respectively in 343 controls and 322 vitiligo patients. IL6 transcript levels were estimated from PBMCs (96 controls and 77 patients) and skin samples (15 controls and 15 patients) by qPCR. NHM viability was assessed by MTT; IL6R, MITF and TYR transcript and protein levels were monitored by qPCR and ICC respectively. Genetic analyses revealed no association of IL6 -174 G/C polymorphism (p> .05) with vitiligo. Analysis of IL6 -572 G/C revealed reduced risk of vitiligo in individuals with GC/CC genotypes compared to GG genotype (p = .010). IL6 expression was significantly increased (p = .0197) in PBMCs of patients. Further, IL6 expression was significantly higher in non-lesional skin compared to controls (p = .009). In-vitro NHM viability was decreased upon IL-6 exposure (10-50 ng/ml; p< .05), with significantly increased IL6R transcript (p = .042) and protein levels (p = .003) however, MITF transcript (p = .0003) and protein levels (p = .016), and TYR transcript levels (p = .001) were significantly decreased. The results suggest that IL6 -572 G/C polymorphism might be associated with vitiligo susceptibility in Gujarat population. Moreover, increased IL6 expression in vitiligo patients and its effect on NHM suggest a potential role in melanocyte biology.

CONCLUSION

The results suggest that IL6 - 572 G/C polymorphism might be associated with vitiligo susceptibility in Gujarat population. Moreover, increased IL6 expression in vitiligo patients and its effect on NHM suggest a potential role in melanocyte biology.

Therapeutic effects of iNOS inhibition against vitiligo in an animal model

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

Role of Fatty Acids Intake in Generalized Vitiligo

Background

Previous studies indicated the effect of fat on autoimmune diseases. The present study was aimed to investigate the association between fat intake and vitiligo.

Methods

This case-control study was conducted in the Skin and Leishmania Research Center, Isfahan University of Medical Sciences, Isfahan, Iran. Intakes of fatty acids were examined for their relation to risk of vitiligo among 100 cases and 110 controls. We included patients who suffered from generalized or localized vitiligo for <5 years that was approved by a dermatologist via the Vitiligo European Task Force criteria and the vitiligo area scoring index. Fat intake was assessed through individual interviews by a standardized food frequency questionnaire.

Results

Vitiligo group consumed more saturated fatty acid (SFA) and less eicosapentaenoic acid and docosahexaenoic acid than control group, while other fatty acids were not significantly different among two groups (P > 0.05). Crude analysis showed that total fat (odds ratio [OR] = 3.33, 95% confidence interval [CI]: 1.46-7.58) and SFA (OR = 2.22, 95% CI: 1.04-4.90) intakes were associated with an increased risk of vitiligo (for highest quartile vs. lowest quartile). Results demonstrated a decrease in the risk of vitiligo for those within the highest quartile of monounsaturated fatty acids intake (OR = 0.41, 95% CI: 0.18-0.92). However, this relationship disappeared after adjustment for confounders as energy, age, sex, and body mass index, except for total fat (OR = 2.84, 95% CI: 1.63-5.44). Crude and adjusted analyses for polyunsaturated fatty acids and cholesterol intake were not statistically significant.

Conclusions

Total-fat content of the diet had more impressive role than the specific subclasses of fats on the incidence risk of vitiligo. High-fat diet escalated the vitiligo risk. Regarding the role of fats on skin autoimmune diseases especially vitiligo, future studies are crucial.

Emerging role of immune cell network in autoimmune skin disorders: An update on pemphigus, vitiligo and psoriasis

Autoimmune skin diseases are a group of disorders that arise due to a deregulated immune system resulting in skin tissue destruction. In the majority of these conditions, either autoreactive immune cells or the autoantibodies are generated against self-antigens of the skin. Although the etiology of these diseases remains elusive, biochemical, genetic, and environmental factors such as infectious agents, toxins damage the skin tissue leading to self-antigen generation, autoantibody attack and finally results in autoimmunity of skin. Immune dysregulation, which involves predominantly T helper 1/17 (Th1/Th17) polarization and the inability of regulatory T cells to regress immune response, is implicated in autoimmune skin diseases. The emerging roles of immune cells, cytokines, and chemokines in the pathogenesis of common autoimmune skin diseases like pemphigus, vitiligo, and psoriasis are discussed in this review. The main focus is on the interplay between immune cell network including the innate and adaptive immune system, regulatory cells, immune checkpoints and recently identified tissue-resident memory cells (TRMs) in disease pathogenesis and relapse. We also attempt to highlight on the immune mechanisms common to these diseases which can be targeted for designing novel therapeutics.

Cutaneous expression of thymic stromal lymphopoietin (TSLP) in vitiligo patients: a case-control study

BACKGROUND

Thymic stromal lymphopoietin (TSLP) is a major pro-allergic cytokine promoting T helper-2 responses. Our aim was to study and verify the hypothesis of the role of TSLP in the pathogenesis of vitiligo.

METHODS

This case-control study was conducted on 25 patients with generalized non-segmental vitiligo (recruited from the Dermatology outpatient clinic, Kasr El Ainy, Faculty of Medicine, Cairo University) and 25 healthy controls fulfilling the inclusion criteria over a period of 7 months (January 2017-July 2017). Patients underwent complete medical history, detailed assessment of vitiligo, and photographic documentation. Skin biopsies were taken from the back from both patients' vitiliginous skin and from normal skin of controls for which relative TSLP messenger RNA (mRNA) tissue expression levels were measured using quantitative real-time polymerase chain reaction technique.

RESULTS

There was a statistically significant difference between the TSLP mRNA expression levels in patients and controls (P < 0.001) with lower levels in the former group.

CONCLUSION

This study revealed lower TSLP mRNA expression levels in vitiliginous skin than in normal skin suggesting an imminent role of TSLP in the pathogenesis of vitiligo.

The role of interleukins in vitiligo: a systematic review

Vitiligo is a disorder of the skin that causes depigmentation and asymptomatic macules whose exact cause is still unclear. Although its aetiology is not fully elucidated, the main theory of its pathomechanism is that it is associated with the autoimmune process. There is few summarized information about the role of inflammatory mediators, as interleukins, in vitiligo, so our aim was to present a systematic review of the role of interleukins in vitiligo, focusing on interleukins. In this review, we included all studies assessing interleukin levels in vitiligo patients conducted up to June 2017. Quality assessment of these studies was performed using the Newcastle-Ottawa Scale (NOS). The interleukins mainly involved were IL-2, IL-4, IL-6, IL-10 and IL-17. The studies highlight the crucial role of IL-17 in the onset and progression of the disease, and its synergistic action with IL-2, IL-6 and IL-33. Dysregulated levels of the interleukins were also correlated with the stage of disease, the affected skin surface area, and indicated as the main factor for lymphocyte infiltration found in depigmented regions. These findings illustrate the growing need for new therapies targeting vitiligo and further research into the role of interleukins as an area of particular interest.

T-cell regulation in Erythema Nodosum Leprosum

Leprosy is a disease caused by Mycobacterium leprae where the clinical spectrum correlates with the patient immune response. Erythema Nodosum Leprosum (ENL) is an immune-mediated inflammatory complication, which causes significant morbidity in affected leprosy patients. The underlying cause of ENL is not conclusively known. However, immune-complexes and cell-mediated immunity have been suggested in the pathogenesis of ENL. The aim of this study was to investigate the regulatory T-cells in patients with ENL. Forty-six untreated patients with ENL and 31 non-reactional lepromatous leprosy (LL) patient controls visiting ALERT Hospital, Ethiopia were enrolled to the study. Blood samples were obtained before, during and after prednisolone treatment of ENL cases. Peripheral blood mononuclear cells (PBMCs) were isolated and used for immunophenotyping of regulatory T-cells by flow cytometry. Five markers: CD3, CD4 or CD8, CD25, CD27 and FoxP3 were used to define CD4⁺ and CD8⁺ regulatory T-cells. Clinical and histopathological data were obtained as supplementary information. All patients had been followed for 28 weeks. Patients with ENL reactions had a lower percentage of CD4⁺ regulatory T-cells (1.7%) than LL patient controls (3.8%) at diagnosis of ENL before treatment. After treatment, the percentage of CD4⁺regulatory T-cells was not significantly different between the two groups. The percentage of CD8⁺ regulatory T-cells was not significantly different in ENL and LL controls before and after treatment. Furthermore, patients with ENL had higher percentage of CD4⁺ T-ells and CD4⁺/CD8⁺ T-cells ratio than LL patient controls before treatment. The expression of CD25 on CD4⁺ and CD8⁺ T-cells was not significantly different in ENL and LL controls suggesting that CD25 expression is not associated with ENL reactions while FoxP3 expression on CD4⁺ T-cells was significantly lower in patients with ENL than in LL controls. We also found that prednisolone treatment of patients with ENL reactions suppresses CD4⁺ T-cell but not CD8⁺ T-cell frequencies. Hence, ENL is associated with lower levels of T regulatory cells and higher CD4⁺/CD8⁺ T-cell ratio. We suggest that this loss of regulation is one of the causes of ENL.

Leprosy reactions (Type 1 and 2) are important causes of nerve damage and illness. Erythema Nodosum Leprosum (ENL) also called type 2 reaction is a severe systemic immune-mediated complication of borderline and lepromatous leprosy. ENL causes high morbidity and thus requires immediate medical attention. We recruited 77 untreated patients with lepromatous leprosy (46 patients with ENL reactions and 31 patients without ENL reactions) in Ethiopia to better define the immune regulation process in patients with ENL reactions. We took blood samples at 3 time points (before, during and after prednisolone treatment) and measured regulatory T-cells at each time point. Patients with ENL reactions had a lower percentage of CD4⁺ regulatory T-cells than in non-reactional LL patient controls before treatment. Patients with ENL reactions had higher percentage of CD4⁺ T- cells and CD4⁺/CD8⁺ ratio than LL patient controls before treatment. These experiments indicate the need to explore ways of restoring regulatory T-cells in patients with ENL reactions to control the undesired outcome of the reaction.

Biomarkers of disease activity in vitiligo: A systematic review

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

Evaluation of Histologically and Histochemically Proven Cases of Vitiligo and its Correlation with CD4+ and CD8+ Lymphocyte Counts using Flow Cytometry

INTRODUCTION

Vitiligo is an acquired cutaneous disorder characterized by progressive and selective destruction of melanocytes from the epidermis. Autoimmunity is strongly implicated in its pathogenesis. The destruction of melanocytes has a correlation with the peripheral blood lymphocyte imbalance mainly including Cytotoxic T cells (CD8+cells) and Helper T cells (CD4+cells). The progression of vitiligo is associated with higher CD8+ counts and lower CD4⁺ counts thus, altering CD4+: CD8+ ratio.

AIM

To evaluate the clinically suspected cases of vitiligo histopathologically and histochemically and to establish the co-relation of autoimmunity with the flow cytometric analysis of CD8+ and CD4+ lymphocyte counts.

MATERIALS AND METHODS

In this study, 40 patients with proven vitiligo were taken. The destruction of melanocytes was confirmed by Haematoxylin & Eosin (H & E) and by histochemical stains using Dihydroxyphenylacetic Acid (DOPA) reaction. Blood sample from these vitiligo patients and 10 control subjects was taken. Flow Cytometry was used for the determination of CD8+ and CD4+ counts in the vitiligo patients and control subjects. Then CD4+: CD8+ ratio was calculated and comparison between vitiligo patients and control subjects was done. T-test was used for the statistical analysis.

RESULTS

There was statistically significant decrease in CD4+: CD8+ ratio. CD4+: CD8+ ratio was decreased in 57.5% cases of vitiligo with increase in CD8+ counts and decreased CD4+ counts.

CONCLUSION

It was concluded from this study that cellular immunity might have a role to play in the pathogenesis of vitiligo causing the destruction of melanocytes.

Genetic variants of interferon-gamma and its mRNA expression and inflammatory parameters in the pathogenesis of vitiligo

Although genetics plays an essential role in the pathogenesis of vitiligo, vitiligo pathogenesis is still unclear. Our aim was to investigate the role of IFN-γ expression and polymorphism in vitiligo susceptibility and whether intercellular adhesion molecule-1 (ICAM-1), tumor necrosis factor (TNF)-α, and TNF-β play a role in vitiligo pathogenesis as important inflammatory parameters. Eighty-five patients with vitiligo and 90 controls were investigated for IFN-γ gene expression by quantitative real-time PCR and genotyped for IFN-γ +874T/A (rs2430561) and IFN-γ +2109A/G (rs1861494) gene polymorphisms by sequence-specific primer (SSP)-PCR and PCR-restriction fragment length polymorphism (RFLP), respectively. Serum levels of inflammatory parameters were measured using ELISA. Frequencies of the +874 TT genotype and T allele were significantly higher in patients with active vitiligo than in stable patients (P = 0.01 and 0.03, respectively). Calculation of odds ratio suggested a 1.7-fold increased risk of vitiligo in individuals having the TA haplotype. We observed overexpression of IFN-γ mRNA with elevated serum levels of IFN-γ, ICAM-1, TNF-α, and TNF-β in patients with vitiligo when compared with the control group (P = 0.001, for all). In addition, these levels were elevated in patients with active vitiligo compared with stable patients with vitiligo (P = 0.008, 0.006, 0.01, 0.01, and 0.03, respectively), which suggests the involvement of these cytokines in disease activity. In conclusion, IFN-γ is a promising immunological marker in vitiligo pathogenesis.

IL-33 circulating serum levels are increased in patients with non-segmental generalized vitiligo

IL-33 is a recently identified cytokine, encoded by the IL-33 gene, which is a member of the IL-1 family that drives the production of T-helper-2 (Th-2)-associated cytokines. Serum levels of IL-33 have been reported to be up-regulated in various T-helper (Th)-1/Th-17-mediated diseases, such as psoriasis, rheumatoid arthritis, and inflammatory bowel. To investigate whether cytokine imbalance plays a role in the pathogenesis of vitiligo, we performed a case-control association study by enzyme-linked immunosorbent assay of IL-33 in our patients. IL-33 serum levels were measured by a quantitative enzyme immunoassay technique in patients with non-segmental generalized vitiligo and compared with those of healthy controls. IL-33 serum levels in patients with vitiligo were significantly increased than those in healthy controls. There was a positive correlation of IL-33 serum levels with extension of vitiligo and disease activity. This study suggests a possible systemic role of IL-33 in the pathogenesis of vitiligo. Inhibiting IL-33 activity might be a novel therapeutic strategy in the treatment of autoimmune inflammatory disease, like vitiligo.

Analysis of oxidative stress status, catalase and catechol-O-methyltransferase polymorphisms in Egyptian vitiligo patients

Vitiligo is the most common depigmentation disorder of the skin. Oxidative stress is implicated as one of the probable events involved in vitiligo pathogenesis possibly contributing to melanocyte destruction. Evidence indicates that certain genes including those involved in oxidative stress and melanin synthesis are crucial for development of vitiligo. This study evaluates the oxidative stress status, the role of catalase (CAT) and catechol-O-Methyltransferase (COMT) gene polymorphisms in the etiology of generalized vitiligo in Egyptians. Total antioxidant capacity (TAC) and malondialdehyde (MDA) levels as well as CAT exon 9 T/C and COMT 158 G/A polymorphisms were determined in 89 patients and 90 age and sex-matched controls. Our results showed significantly lower TAC along with higher MDA levels in vitiligo patients compared with controls. Meanwhile, genotype and allele distributions of CAT and COMT polymorphisms in cases were not significantly different from those of controls. Moreover, we found no association between both polymorphisms and vitiligo susceptibility. In conclusion, the enhanced oxidative stress with the lack of association between CAT and COMT polymorphisms and susceptibility to vitiligo in our patients suggest that mutations in other genes related to the oxidative pathway might contribute to the etiology of generalized vitiligo in Egyptian population.

Assessment of tissue FoxP3+, CD4+ and CD8+ T-cells in active and stable nonsegmental vitiligo

BACKGROUND

The exact etiology of vitiligo remains obscure. Studies have indicated a role for cellular immunity in the pathogenesis of vitiligo. The aim of this study is to assess tissue FoxP3+ natural regulatory T-cells (Tregs), as well as CD4+ and CD8+ T-cells in active vs. stable nonsegmental vitiligo.

MATERIALS AND METHODS

Immunohistochemical double-staining for expression of CD4+ and CD8+ T-cells with immunostaining for expression of FoxP3 in lesional, marginal, and nonlesional skin of nonsegmental vitiligo was used to evaluate the abundance of Tregs among CD4+ and CD8+ T-cells in active and stable cases of vitiligo.

RESULTS

A significant increase in the number of CD4+ and CD8+ T-cells and a highly significant reduction in the number of FoxP3-expressing Tregs were detected in marginal skin in both stable and active vitiligo cases. FoxP3+ cells were decreased in tissue of patients with vitiligo compared with healthy controls. The number of CD8+ T-cells was increased in the epidermis and dermoepidermal junction (DEJ) in comparison with the number of CD4+ T-cells. Tregs were mostly present at the DEJ.

CONCLUSION

The reduction in the number of FoxP3+ cells in the marginal skin suggests that this is the site where regulatory activity is needed to suppress the activity of helper and cytotoxic T-cells that are actively contributing to depigmentation.

The role of tumor necrosis factor-α in the pathogenesis of vitiligo

Vitiligo is an acquired immune disorder of the skin characterized by the presence of white depigmented macules. Its immunopathogenesis is not completely understood, but inflammatory alterations in the skin microenvironment, and particularly increased expression of the cytokine tumor necrosis factor-α (TNFα), are thought to be essential regulators of melanocyte dysfunction and death. In this article we review the evidence that implicates TNFα in the pathogenesis of vitiligo, including studies on serum and tissue levels of TNFα, TNFα gene polymorphisms, in vitro studies, and therapeutic trials using TNFα inhibitors. TNFα emerges as a complex mediator with apparently conflicting roles in vitiligo.

Decreased regulatory T-cells and CD4(+) /CD8(+) ratio correlate with disease onset and progression in patients with generalized vitiligo

The aim of present study was to evaluate CD4(+) /CD8(+) ratio and CD4(+) CD25(hi) FoxP3(+) Tregs in GV patients with reference to their effect on disease onset and progression. Flow cytometry was used for determination of CD4(+) /CD8(+) ratio and Tregs in 82 patients and 50 controls. CD8(+) T-cell counts were significantly higher in GV patients as compared with controls (p = 0.003). Active GV patients showed higher CD8(+) T-cell counts compared with stable GV patients (p = 0.001). The CD4(+) /CD8(+) ratio decreased significantly in patients as compared with controls (p = 0.001). Moreover, the ratio in active GV patients significantly lowered as compared with stable GV patients (p = 0.002). Significant decrease in Treg cell percentage and counts in GV patients was observed compared with controls (p = 0.009, p = 0.008) with significant reduction in FoxP3 expression (p = 0.024). Treg cell percentage and counts were significantly decreased in active GV patients compared with stable GV patients (p = 0.007, p = 0.002). Our results suggest that an imbalance of CD4(+) /CD8(+) ratio and natural Tregs in frequency and function might be involved in the T-cell mediated pathogenesis of GV and its progression.

Vitiligo: interplay between oxidative stress and immune system

Vitiligo is a multifactorial polygenic disorder with a complex pathogenesis, linked with both genetic and non-genetic factors. The precise modus operandi for vitiligo pathogenesis has remained elusive. Theories regarding loss of melanocytes are based on autoimmune, cytotoxic, oxidant-antioxidant and neural mechanisms. Reactive oxygen species (ROS) in excess have been documented in active vitiligo skin. Numerous proteins in addition to tyrosinase are affected. It is possible that oxidative stress is one among the main principal causes of vitiligo. However, there also exists ample evidence for altered immunological processes in vitiligo, particularly in chronic and progressive conditions. Both innate and adaptive arms of the immune system appear to be involved as a primary event or as a secondary promotive consequence. There is speculation on the interplay, if any, between ROS and the immune system in the pathogenesis of vitiligo. The article focuses on the scientific evidences linking oxidative stress and immune system to vitiligo pathogenesis giving credence to a convergent terminal pathway of oxidative stress-autoimmunity-mediated melanocyte loss.

Systemic analyses of immunophenotypes of peripheral T cells in non-segmental vitiligo: implication of defective natural killer T cells

Although it is widely believed that non-segmental vitiligo (NSV) results from the autoimmune destruction of melanocytes, a clear understanding of defects in immune tolerance, which mediate this uncontrolled self-reactivity, is still lacking. In the present study, we systemically evaluated circulating regulatory T (Treg) cells, including CD4(+) CD25(+) FoxP3(+) Treg cells and invariant natural killer T (iNKT) cells, as well as naïve and memory CD4(+) and CD8(+) T cells and their cytokine production, in a cohort of 43 progressive NSV patients with race-, gender-, and age-matched healthy controls. We found that the general immunophenotypes of CD4(+) and CD8(+) T cells and the percentage of CD4(+) CD25(+) FoxP3(+) Tregs were comparable between NSV and healthy controls. However, percentages of peripheral iNKT cells were significantly decreased in NSV patients compared to that in healthy controls. Our data confirm the previous notion that the percentage of peripheral CD4(+) CD25(+) FoxP3(+) Tregs remains unaltered in NSV and suggests the involvement of defective iNKT cells in the pathogenesis of NSV.

Serum concentration of IL-6, IL-2, TNF-α, and IFNγ in Vitiligo patients

Background:

Vitiligo is an acquired depigmenting disorder characterized by the loss of functional melanocytes from the epidermis. Although the etiology of vitiligo is unknown, over the last few years, substantial data from clinical research has greatly supported the ‘Autoimmune theory’ and this is supported by the frequent association of vitiligo with disorders that have an autoimmune origin, including Hashimoto's thyroiditis, Graves disease, type 1 insulin-dependent diabetes mellitus, and Addison's disease. As cytokines are important mediators of immunity, there is evidence to suggest that they play a major role in the pathogenesis of autoimmune diseases.

Aim:

Keeping this in view we have assayed sera for cytokine IL-6, IL-2, Tumor necrosis factor (TNF)-α, and IFNγ in 80 cases of vitiligo and compared it with healthy subjects, in order to find out whether they play a role in the pathogenesis of vitiligo or not.

Materials and Methods:

Serum IL-6, IL-2, TNF-α, and IFNγ were done by the indirect enzyme linked immunosorbent assay (ELISA).

Results:

The mean serum IL-6 and IL-2 levels in the patient group were significantly higher when compared with those of the normal controls. The mean serum IFNγ level in patients with vitiligo was significantly lower than that in the control group. There was no significant difference in the serum level of TNF-α between vitiligo and healthy controls.

Conclusion:

An increase in the production of proinflammatory cytokines such as IL-6 and IL-2 in vitiligo patients may play an important role in melanocytic cytotoxicity. Thus, we speculate that the cytokine production of epidermal microenvironment may be involved in vitiligo.

CD8+ T-Cell Deficiency, Epstein-Barr Virus Infection, Vitamin D Deficiency, and Steps to Autoimmunity: A Unifying Hypothesis

CD8+ T-cell deficiency is a feature of many chronic autoimmune diseases, including multiple sclerosis, rheumatoid arthritis, systemic lupus erythematosus, Sjögren's syndrome, systemic sclerosis, dermatomyositis, primary biliary cirrhosis, primary sclerosing cholangitis, ulcerative colitis, Crohn's disease, psoriasis, vitiligo, bullous pemphigoid, alopecia areata, idiopathic dilated cardiomyopathy, type 1 diabetes mellitus, Graves' disease, Hashimoto's thyroiditis, myasthenia gravis, IgA nephropathy, membranous nephropathy, and pernicious anaemia. It also occurs in healthy blood relatives of patients with autoimmune diseases, suggesting it is genetically determined. Here it is proposed that this CD8+ T-cell deficiency underlies the development of chronic autoimmune diseases by impairing CD8+ T-cell control of Epstein-Barr virus (EBV) infection, with the result that EBV-infected autoreactive B cells accumulate in the target organ where they produce pathogenic autoantibodies and provide costimulatory survival signals to autoreactive T cells which would otherwise die in the target organ by activation-induced apoptosis. Autoimmunity is postulated to evolve in the following steps: (1) CD8+ T-cell deficiency, (2) primary EBV infection, (3) decreased CD8+ T-cell control of EBV, (4) increased EBV load and increased anti-EBV antibodies, (5) EBV infection in the target organ, (6) clonal expansion of EBV-infected autoreactive B cells in the target organ, (7) infiltration of autoreactive T cells into the target organ, and (8) development of ectopic lymphoid follicles in the target organ. It is also proposed that deprivation of sunlight and vitamin D at higher latitudes facilitates the development of autoimmune diseases by aggravating the CD8+ T-cell deficiency and thereby further impairing control of EBV. The hypothesis makes predictions which can be tested, including the prevention and successful treatment of chronic autoimmune diseases by controlling EBV infection.

Hypothesis: zinc can be effective in treatment of vitiligo

Vitiligo is a common depigmenting skin disorder (prevalence 0.1-2%), still represents a cause of stigmatization and quality of life impairment in a large population. Several theories on vitiligo etiopathogenesis have been suggested including in trauma, stress, and autoimmune and genetic predisposition, accumulation of toxic compounds, altered cellular environment, imbalance in the oxidant-antioxidant system, impaired melanocyte migration and/or proliferation, infection, and psychological factors. Zinc, as a trace element, has many vital functions in human. It is antiapoptotic factor and needed as a cofactor for antioxidant defense system. It plays an important role in the process of melanogenesis. It may be effective in prevention and treatment of vitiligo via some mechanism. Herein, we suggested some probable protective mechanism for zinc in association with vitiligo.

Vitiligo: a review of the published work

Vitiligo is a common depigmenting skin disorder, characterized by acquired, idiopathic, progressive, circumscribed hypomelanosis of the skin and hair, with total absence of melanocytes microscopically. It occurs worldwide, with an incidence rate of between 0.1% and 2%. Vitiligo is an important skin disease having a major impact on the quality of life of the patient suffering from it. The causes of this condition are uncertain but seem to be dependent on the interaction of genetic, immunological and neurological factors. Vitiligo coexists with other autoimmune disorders, Sutton or halo nevus, and malignant melanoma. The substantial disfigurement associated with vitiligo can cause serious emotional stress for the patient, which necessitates treatment. Because its pathogenesis is still not understood, there is a plethora of different treatments. Among them, topical steroids and narrowband ultraviolet B monotherapy were the most common as current treatments for localized and generalized vitiligo, respectively. Cosmetic improvement can be achieved by camouflage products and self-tanning dyes. The course of vitiligo is unpredictable, but often progressive. Spontaneous repigmentation may occur in a few people (10–20%), mainly in children, but this tends to be only partial and on sun-exposed areas. In this article, we review vitiligo as a whole, including epidemiology, pathogenesis and etiology, histopathology, clinical manifestations, classification, clinical variants, diagnosis and differential diagnoses, specific investigation, treatment, prognosis, psychosocial view and its association with other disorders.

Reduction of skin-homing cytotoxic T cells (CD8+ -CLA+) in patients with vitiligo

BACKGROUND

Vitiligo is a frequently acquired, hereditary disease, characterized by achromic macules due to the absence of melanocytes. In contrast with earlier studies, in which the main pathogenic role was attributed to anti-melanocyte antibodies, recent papers have emphasized a role for CD8(+) cytotoxic T lymphocytes in melanocyte destruction. Fifteen percent of peripheral T cell express cutaneous lymphocyte-associated antigen (CLA), responsible for skin-homing T cell. Phototherapy is used to treat patients with generalized vitiligo and it has been shown to interfere with CLA(+) T cells in other skin diseases.

OBJECTIVE

To describe peripheral blood T cell subpopulations' frequency and ability to express the skin-homing molecule (CLA) in patients with non-segmental vitiligo, before and after photochemotherapy (PUVA).

PATIENTS AND METHODS

Twenty-two patients with generalized and active spreading vitiligo were submitted to 30 PUVA-8MOP sessions. Lymphocyte immunophenotyping was performed by flow cytometry using anti-CD3, anti-CD8 and anti-CLA monoclonal antibodies. Fifteen healthy volunteers, sex- and age-matched, were included as a control group.

RESULTS

CD8(+) -CLA(+) T cells were significantly reduced in number in untreated vitiligo patients (P=0.008) when compared with control individuals, albeit with a more intense CLA expression (P=0.028). These findings were not altered after PUVA. No significant difference was noticed in CD4/CD8 ratios nor in CD4-CLA(+) T cell numbers between vitiligo patients and controls, both before and after PUVA.

CONCLUSIONS

CD8-CLA(+) T cells are reduced in peripheral blood of patients with non-segmental vitiligo. This finding may be related to the previously reported increase of CD8(+) cells in both lesions and perilesional skin of these patients.

The presence of non-segmental vitiligo modifies intracellular cytokine subsets in patients with chronic lymphocytic thyroiditis

Chronic lymphocytic thyroiditis and vitiligo often occur in association and seem to be characterized by a prevalent Th1-driven autoimmune process. The aim of this study is to analyze selected intracellular Τh1 and Th2 cytokines in patients with Hashimoto?s thyroiditis when associated with non-segmental vitiligo. We analyzed intracellular interleukin-2, interferon-gamma (Τh1) and interleukin-4 (Th2), in peripheral blood lymphocytes of 23 patients with isolated Hashimoto?s thyroiditis (group A) and of 11 patients with Hashimoto?s thyroiditis associated with non-segmental vitiligo (group B). Peripheral blood lymphocytes were stimulated and incubated with specific monoclonal antibodies. Intracellular cytokines were assayed by flow cytometric analysis. Interleukin-2 and interferon-gamma positive cells were increased in almost all patients but the median values were similar in patients with isolated Hashimoto?s thyroiditis and in those with concurrent vitiligo. In contrast, the number of patients with increased interleukin-4 positive cells was higher in patients with thyroiditis and vitiligo (9/11) than in those with isolated thyroiditis (2/23; p<0.0001). The median values of IL-4 positive cells in the two groups confirmed this difference (A: 5.8 percent, vs B: 20.6 percent; p=0.0011). Increased interleukin-4 positive lymphocytes characterize Hashimoto?s thyroiditis when associated with non-segmental vitiligo, suggesting a modified balance from highly prevalent Th1 to mixed Th1/Th2 subset.

Immunopathogenesis of vitiligo

Vitiligo is a common depigmenting disorder which may have devastating psychological and social consequences and is characterized by the presence of circumscribed white macules in the skin due to the destruction of melanocytes in the epidermis. Various hypotheses have been proposed to explain the pathomechanisms involved in this disease, and studies have shown the participation of autoimmune processes in the pathogenesis of vitiligo. Cellular and humoral immunities have been implicated in the development of vitiligo and their role continues to be investigated. Peripheral blood and skin biopsies of patients with vitiligo show that T-cells, mononuclear cells, various pro-inflammatory cytokines, and auto-antibodies can damage melanocytes. Further research is required to determine whether autoimmunity is the main mechanism of vitiligo or only a consequence.

Vitiligo, reactive oxygen species and T-cells

The acquired depigmenting disorder of vitiligo affects an estimated 1% of the world population and constitutes one of the commonest dermatoses. Although essentially asymptomatic, the psychosocial impact of vitiligo can be severe. The cause of vitiligo remains enigmatic, hampering efforts at successful therapy. The underlying pathogenesis of the pigment loss has, however, been clarified to some extent in recent years, offering the prospect of effective treatment, accurate prognosis and rational preventative strategies. Vitiligo occurs when functioning melanocytes disappear from the epidermis. A single dominant pathway is unlikely to account for all cases of melanocyte loss in vitiligo; rather, it is the result of complex interactions of biochemical, environmental and immunological events, in a permissive genetic milieu. ROS (reactive oxygen species) and H2O2 in excess can damage biological processes, and this situation has been documented in active vitiligo skin. Tyrosinase activity is impaired by excess H2O2 through oxidation of methionine residues in this key melanogenic enzyme. Mechanisms for repairing this oxidant damage are also damaged by H2O2, compounding the effect. Numerous proteins and peptides, in addition to tyrosinase, are similarly affected. It is possible that oxidant stress is the principal cause of vitiligo. However, there is also ample evidence of immunological phenomena in vitiligo, particularly in established chronic and progressive disease. Both innate and adaptive arms of the immune system are involved, with a dominant role for T-cells. Sensitized CD8+ T-cells are targeted to melanocyte differentiation antigens and destroy melanocytes either as the primary event in vitiligo or as a secondary promotive consequence. There is speculation on the interplay, if any, between ROS and the immune system in the pathogenesis of vitiligo. The present review focuses on the scientific evidence linking alterations in ROS and/or T-cells to vitiligo.

Role of interleukin-17 in the pathogenesis of vitiligo

BACKGROUND

Skewing of the immune response towards T helper (Th)1 or Th17 and away from regulatory T cells (Tregs) and Th2 cells may be responsible for the development and progression of autoimmune disease. An autoimmune theory has been proposed in the pathogenesis of vitiligo. No previous reports have investigated alterations in IL-17 produced by Th17 cells in lesional skin in vitiligo.

AIM

To investigate the role of IL-17 in the pathogenesis of vitiligo by assessing its levels in lesional skin and serum of patients with vitiligo compared with controls.

METHODS

In total, 30 patients with vitiligo and 20 controls matched for age and gender were enrolled in the study. Serum and tissue IL-17 levels were measured by ELISA and compared between both groups for correlations with age, gender, family history, disease duration, activity of vitiligo and percentage of involved body surface area.

RESULTS

A significant difference between patients and healthy controls was found for both serum and tissue IL-17 levels (P<0.001 for both). Significant positive correlations were found between disease duration and IL-17 level in both serum (r=0.42, P=0.02) and lesional skin (r=0.45, P<0.015); between extent of vitiligo and IL-17 levels in both serum (r=0.65, P<0.001) and skin (r=0.48, P<0.05); and between the serum and the tissue IL-17 levels in patients with vitiligo (r=0.54, P=0.002).

CONCLUSIONS

Multiple factors have been implicated in the pathogenesis of vitiligo. The increased levels of IL-17 we found in serum and lesional skin suggest an important role for this cytokine in the pathogenesis of vitiligo.

Cocaine administration increases CD4/CD8 lymphocyte ratio in peripheral blood despite lymphopenia and elevated corticosterone

The CD4/CD8 lymphocyte ratio in peripheral blood is used in the diagnosis of HIV infection, autoimmune disorders or susceptibility to infections. The present experiment aimed to evaluate the lymphocyte subsets, their distribution and CD4/CD8 ratio in blood after repeated, intravenous administration of cocaine. Adult male Wistar rats received three daily, in 30 min intervals, intravenous infusions of cocaine hydrochloride (5 mg/kg) or saline for 14 consecutive days. After each infusion the locomotor-activating effects of cocaine were assessed. Blood samples were collected 30 min after the last daily infusion on the 1st, 7th and 14th day of treatment. Total leukocyte numbers, percentages of leukocyte subpopulations, and T, B, NK, T CD4+, and T CD8+ lymphocyte subsets, IFN-γ, and plasma corticosterone were determined. Repeated cocaine treatment resulted in an increase in neutrophil numbers and a significant decrease in total leukocyte and lymphocyte numbers involving a significant reduction in numbers of T, B, and NK lymphocyte subsets. T CD4+ and T CD8+ lymphocyte numbers were reduced but with a considerably smaller decrease in T CD4+ number. Cocaine treatment altered proportions between the lymphocyte subsets by decreasing the percentages of T CD8+, B, and NK cells but increasing a percentage of T CD4+ cells. Destabilization in proportions between T CD4+ and T CD8+ was manifested as an elevated CD4/CD8 ratio that occurred despite increased plasma corticosterone and the lymphocytopenia. Cocaine did not affect the concentration of IFN-γ. The results suggest that although cocaine induced lymphopenia, it did not suppress the overall immune activity in terms of the CD4/CD8 ratio.