Functional defects of peripheral regulatory T lymphocytes in patients with progressive vitiligo

JAK inhibitors for the treatment of vitiligo

Vitiligo is an autoimmune disease involving melanocyte-targeting T cells initiated by environmental and genetic factors. Steroids and tacrolimus have been used as topical treatments. Recently, novel topical agents targeting Janus kinase (JAK), a family of tyrosine kinases that regulates cytokine signaling, have emerged. Ruxolitinib is the first approved in vitiligo therapy. Furthermore, ritlecitinib is currently under clinical trials for oral treatment of active vitiligo. In this review, we discuss the possibility of topical JAK inhibitors as promising options for the treatment of vitiligo with regard to their mechanism of action, efficacy and safety.

Human Regulatory T Cells: Understanding the Role of Tregs in Select Autoimmune Skin Diseases and Post-Transplant Nonmelanoma Skin Cancers

Regulatory T cells (Tregs) play an important role in maintaining immune tolerance and homeostasis by modulating how the immune system is activated. Several studies have documented the critical role of Tregs in suppressing the functions of effector T cells and antigen-presenting cells. Under certain conditions, Tregs can lose their suppressive capability, leading to a compromised immune system. For example, mutations in the Treg transcription factor, Forkhead box P3 (FOXP3), can drive the development of autoimmune diseases in multiple organs within the body. Furthermore, mutations leading to a reduction in the numbers of Tregs or a change in their function facilitate autoimmunity, whereas an overabundance can inhibit anti-tumor and anti-pathogen immunity. This review discusses the characteristics of Tregs and their mechanism of action in select autoimmune skin diseases, transplantation, and skin cancer. We also examine the potential of Tregs-based cellular therapies in autoimmunity.

Regulatory T Cells Require CCR6 for Skin Migration and Local Suppression of Vitiligo

Vitiligo is an autoimmune skin disease caused by melanocyte-targeting autoreactive CD8+ T cells. Regulatory T cells (Tregs) have been implicated in restraining vitiligo severity in both mouse models and human patients; however, whether they must be present in the skin for their suppressive function is still unclear. We observed uneven distribution of Tregs within different anatomical locations of mouse skin, which correlated with reduced depigmentation after vitiligo induction. We specifically depleted Tregs in our mouse model of vitiligo and observed increased disease. Next, we found that Tregs contact CD8+ T effector cells in vitiligo lesional skin and that Treg recruitment to the skin inversely correlated with disease severity, suggesting a critical role for Treg suppression within the skin. When we investigated the signals facilitating Treg migration to the skin, we found that although CXCR3 was dispensable for Treg migration and function in vitiligo, Tregs lacking CCR6 exhibited a reduced capacity to migrate to the skin and suppress depigmentation, despite normal systemic numbers in the skin-draining lymph nodes. Our observations highlight a key role for cutaneous Tregs in disease suppression during vitiligo and identify CCR6 as a chemokine receptor that contributes to Treg migration to the skin.

Immunometabolism in the pathogenesis of vitiligo

Vitiligo is a common depigmenting skin disorder characterized by the selective loss of melanocytes. Autoimmunity, genetic, environmental, and biochemical etiology have been proposed in vitiligo pathogenesis. However, the exact molecular mechanisms of vitiligo development and progression are unclear, particularly for immunometabolism. Sporadic studies have suggested mitochondrial dysfunction, enhanced oxidative stress, and specific defects in other metabolic pathways can promote dysregulation of innate and adaptive immune responses in vitiligo. These abnormalities appear to be driven by genetic and epigenetic factors modulated by stochastic events. In addition, glucose and lipid abnormalities in metabolism have been associated with vitiligo. Specific skin cell populations are also involved in the critical role of dysregulation of metabolic pathways, including melanocytes, keratinocytes, and tissue-resident memory T cells in vitiligo pathogenesis. Novel therapeutic treatments are also raised based on the abnormalities of immunometabolism. This review summarizes the current knowledge on immunometabolism reprogramming in the pathogenesis of vitiligo and novel treatment options.

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.

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.

Update on the pathogenesis of vitiligo

Vitiligo is a complex disease whose pathogenesis results from the interaction of genetic components, metabolic factors linked to cellular oxidative stress, melanocyte adhesion to the epithelium, and immunity (innate and adaptive), which culminate in aggression against melanocytes. In vitiligo, melanocytes are more sensitive to oxidative damage, leading to the increased expression of proinflammatory proteins such as HSP70. The lower expression of epithelial adhesion molecules, such as DDR1 and E-cadherin, facilitates damage to melanocytes and exposure of antigens that favor autoimmunity. Activation of the type 1-IFN pathway perpetuates the direct action of CD8+ cells against melanocytes, facilitated by regulatory T-cell dysfunction. The identification of several genes involved in these processes sets the stage for disease development and maintenance. However, the relationship of vitiligo with environmental factors, psychological stress, comorbidities, and the elements that define individual susceptibility to the disease are a challenge to the integration of theories related to its pathogenesis.

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

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

The Immunogenetics of Vitiligo: An Approach Toward Revealing the Secret of Depigmentation

Vitiligo is a hypomelanotic skin disease and considered to be of autoimmune origin due to breaching of immunological self-tolerance, resulting in inappropriate immune responses against melanocytes. The development of vitiligo includes a strong heritable component. Different strategies ranging from linkage studies to genome-wide association studies are used to explore the genetic factors responsible for the disease. Several vitiligo loci containing the respective genes have been identified which contribute to vitiligo and genetic variants for some of the genes are still unknown. These genes include mainly the proteins that play a role in immune regulation and a few other genes important for apoptosis and regulation of melanocyte functions. Despite the available data on genetic variants and risk alleles which influence the biological processes, only few immunological pathways have been found responsible for all ranges of severity and clinical manifestations of vitiligo. However, studies have concluded that vitiligo is of autoimmune origin and manifests due to complex interactions in immune components and their inappropriate response toward melanocytes. The genes involved in the immune regulation and processing the melanocytes antigen and its presentation can serve as effective immune-therapeutics that can target specific immunological pathways involved in vitiligo. This chapter highlights those immune-regulatory genes involved in vitiligo susceptibility and loci identified to date and their implications in vitiligo pathogenesis.

Identification of the Role of Wnt/β-Catenin Pathway Through Integrated Analyses and in vivo Experiments in Vitiligo

Purpose

Vitiligo is an acquired depigmentation skin disease, which affects an average of 1% of the world’s population. The purpose of this study is to identify the key genes and pathways responsible for vitiligo and find new therapeutic targets.

Methods

The datasets GSE65127, GSE53146, and GSE75819 were downloaded from the Gene Expression Omnibus (GEO) database. R language was used to identify the differentially expressed genes (DEGs) between lesional skin of vitiligo and non-lesional skin. Next, the key pathways were obtained by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses. The protein–protein interaction (PPI) networks were conducted by STRING database and Cytoscape software. Subsequently, module analysis was performed by Cytoscape. Among these results, the Wnt/β-catenin pathway and melanogenesis pathway caught our attention. The expression level of β-catenin, microphthalmia-associated transcription factor (MITF) and tyrosinase (TYR) was detected by immunofluorescence in vitiligo lesions and healthy skin. Moreover, zebrafish was treated with XAV-939, an inhibitor of the Wnt/β-catenin pathway. After that, the area of melanin granules as a percentage of the head area was measured. The mRNA expression of β-catenin, lymphoid-enhancing factor 1(lef1), tyr and mitf were detected by q-PCR (quantitative polymerase chain reaction) in zebrafish (Danio rerio).

Results

A total of 2442 DEGs were identified, including 1068 upregulated and 1374 downregulated DEGs. The key pathways were identified by GO and KEGG analyses, such as “NOD-like receptor signaling pathway”, “Wnt signaling pathway”, “Melanogenesis”, “mTOR signaling pathway”, “PI3K-Akt signaling pathway”, “Calcium signaling pathway” and “Rap1 signaling pathway”. The immunofluorescence results showed that the level of β-catenin, MITF and TYR was significantly downregulated in vitiligo lesional skin. In zebrafish, the mean percentage area of melanin granules and the expression of β-catenin, lef1, tyr and mitf were decreased after treated with XAV-939.

Conclusion

The present study identified key genes and signaling pathways associated with the pathophysiology of vitiligo. Among them, the Wnt/β-catenin pathway played an essential role in pigmentation and could be a breakthrough point in vitiligo treatment.

scRNA-seq of human vitiligo reveals complex networks of subclinical immune activation and a role for CCR5 in Treg function

[Figure: see text].

Immunophenotypic Analysis Reveals Differences in Circulating Immune Cells in the Peripheral Blood of Patients with Segmental and Nonsegmental Vitiligo

Accumulating studies have indicated immune-based destruction of melanocytes in both segmental vitiligo (SV) and non-SV (NSV). Whereas SV often occurs unilaterally during childhood and stabilizes after an initial period of activity, the disease course of NSV is usually slowly progressive, with new lesions occurring bilaterally during life. This suggests an involvement of distinct pathophysiology pathways, specifically increased systemic immune activation in patients with NSV but not in patients with SV. This research aimed to identify the differences in immune cells in the blood of patients with SV and NSV through immunophenotyping of circulating cells. Regulatory T cells were unaffected in patients with SV compared with that in healthy controls but decreased in patients with NSV. In patients with NSV, the reduction in regulatory T cells was associated with the presence of other systemic autoimmune comorbidities, which were less present in SV. Similarly, the absence of a melanocyte-specific antibody response in patients with SV suggests less involvement of B-cell immunity in SV. These data show that in contrast to patients with NSV, no increased systemic immunity is found in patients with SV, indicating that SV pathogenesis is associated with a localized cytotoxic reaction targeting epidermal melanocytes.

A New Insight into the Potential Role of Tryptophan-Derived AhR Ligands in Skin Physiological and Pathological Processes

The aryl hydrocarbon receptor (AhR) plays a crucial role in environmental responses and xenobiotic metabolism, as it controls the transcription profiles of several genes in a ligand-specific and cell-type-specific manner. Various barrier tissues, including skin, display the expression of AhR. Recent studies revealed multiple roles of AhR in skin physiology and disease, including melanogenesis, inflammation and cancer. Tryptophan metabolites are distinguished among the groups of natural and synthetic AhR ligands, and these include kynurenine, kynurenic acid and 6-formylindolo[3,2-b]carbazole (FICZ). Tryptophan derivatives can affect and regulate a variety of signaling pathways. Thus, the interest in how these substances influence physiological and pathological processes in the skin is expanding rapidly. The widespread presence of these substances and potential continuous exposure of the skin to their biological effects indicate the important role of AhR and its ligands in the prevention, pathogenesis and progression of skin diseases. In this review, we summarize the current knowledge of AhR in skin physiology. Moreover, we discuss the role of AhR in skin pathological processes, including inflammatory skin diseases, pigmentation disorders and cancer. Finally, the impact of FICZ, kynurenic acid, and kynurenine on physiological and pathological processes in the skin is considered. However, the mechanisms of how AhR regulates skin function require further investigation.

Engineered antigen-specific regulatory T cells for autoimmune skin conditions

Regulatory T cells (Tregs) are a subset of T cells responsible for the regulation of immune responses, thereby maintaining immune homeostasis and providing immune tolerance to both self and non-self-antigens. An increasing number of studies revealed Treg numbers and functions in a variety of autoimmune diseases. Treg deficiency can cause the development of several autoimmune skin diseases including vitiligo, alopecia areata, pemphigoid and pemphigus, psoriasis, and systemic sclerosis. Many clinical trials have been performed for autoimmune conditions using polyclonal Tregs, but efficiency can be significantly improved using antigen-specific Tregs engineered using T cell receptor (TCR) or chimeric antigen receptor (CAR) constructs. In this review, we systematically reviewed altered frequencies, impaired functions, and phenotypic features of Tregs in autoimmune skin conditions. We also summarized new advances in TCR and CAR based antigen-specific Tregs tested both in animal models and in clinics. The advantages and limitations of each approach were carefully discussed emphasizing possible clinical relevance to patients with autoimmune skin diseases. Moreover, we have reviewed potential approaches for engineering antigen-specific Tregs, and strategies for overcoming possible hurdles in clinical applications. Thereby, antigen-specific Tregs can be infused using autologous adoptive cell transfer to restore Treg numbers and to provide local immune tolerance for autoimmune skin disorders.

Antigen Specificity Enhances Disease Control by Tregs in Vitiligo

Vitiligo is an autoimmune skin disease characterized by melanocyte destruction. Regulatory T cells (Tregs) are greatly reduced in vitiligo skin, and replenishing peripheral skin Tregs can provide protection against depigmentation. Ganglioside D3 (GD3) is overexpressed by perilesional epidermal cells, including melanocytes, which prompted us to generate GD3-reactive chimeric antigen receptor (CAR) Tregs to treat vitiligo. Mice received either untransduced Tregs or GD3-specific Tregs to test the hypothesis that antigen specificity contributes to reduced autoimmune reactivity in vitro and in vivo. CAR Tregs displayed increased IL-10 secretion in response to antigen, provided superior control of cytotoxicity towards melanocytes, and supported a significant delay in depigmentation compared to untransduced Tregs and vehicle control recipients in a TCR transgenic mouse model of spontaneous vitiligo. The latter findings were associated with a greater abundance of Tregs and melanocytes in treated mice versus both control groups. Our data support the concept that antigen-specific Tregs can be prepared, used, and stored for long-term control of progressive depigmentation.

Targeting the PD-1/PD-L1 Axis in Human Vitiligo

Autoreactive CD8⁺ T cells play a pivotal role in melanocyte destruction in autoimmune vitiligo. Immunotherapy for melanoma often leads to autoimmune side-effects, among which vitiligo-like depigmentation, indicating that targeting immune checkpoints can break peripheral tolerance against self-antigens in the skin. Therapeutically enhancing immune checkpoint signaling by immune cells or skin cells, making self-reactive T cells anergic, seems a promising therapeutic option for vitiligo. Here, we review the current knowledge on the PD-1/PD-L1 pathway in vitiligo as new therapeutic target for vitiligo therapy.

ZMIZ1 promotes the proliferation and migration of melanocytes in vitiligo

Genome wide association studies have revealed that the zinc finger MIZ-type containing 1 (ZMIZ1) is involved in the pathogenesis of vitiligo; however, the underlying mechanism remains unclear. The present study aimed to investigate the effects of ZMIZ1 on the proliferation, apoptosis and migration of the human melanocyte cell lines PIG1 and PIG3V. ZMIZ1 overexpression and knockdown PIG1 and PIG3V cell models were established by lentivirus infection, and the effects of ZMIZ1 on cell proliferation and apoptosis were determined using an MTT assay and flow cytometry, respectively. Furthermore, the expression levels of proliferation- and apoptosis-associated proteins were analyzed using western blotting. Additionally, Transwell assays were performed to determine the effect of ZMIZ1 on the migration of PIG1 and PIG3V cells. Finally, the effect of ZMIZ1 on cytoskeletal remodeling in PIG1 and PIG3V cells was analyzed using immunocytochemistry. The overexpression of ZMIZ1 promoted the proliferation and inhibited the apoptosis of PIG1 and PIG3V cells, whereas the genetic knockdown of ZMIZ1 resulted in the opposite effects. Furthermore, ZMIZ1 overexpression increased the migration, whereas the knockdown of ZMIZ1 inhibited the migration and altered remodeling of the actin cytoskeleton in PIG1 and PIG3V cells. In conclusion, the results of the present study suggest that ZMIZ1 regulates the proliferation, apoptosis and migration of PIG1 and PIG3V cells, and indicate that ZMIZ1 may serve as a potential therapeutic target for vitiligo.

Decreased suppression of CD8+ and CD4+ T cells by peripheral regulatory T cells in generalized vitiligo due to reduced NFATC1 and FOXP3 proteins

Regulatory T cells (Tregs) are involved in the suppression of activated T cells in generalized vitiligo (GV). The study was aimed to investigate Tregs functional defects in Treg:CD8⁺ and Treg:CD4⁺ T cells' co-culture systems of 55 GV patients and 45 controls. CD8⁺ and CD4⁺ T-cell proliferation was assessed by BrdU assay; production of IL-10, TGF-β and IFN-γ cytokines was assessed by ELISA; and FOXP3, CD25, NFATC1 and CD44 proteins were measured by flow cytometry. Generalized vitiligo patients showed reduced suppression of CD8⁺ and CD4⁺ T cells (P = .0384, P = .0084), increased IFN-γ (P < .0001, P = .0019), decreased IL-10 and TGF-β (P < .0001) and decreased FOXP3, CD25 and NFATC1 proteins (P < .0001). Active vitiligo (AV) patients showed reduced suppression of CD8⁺ & CD4⁺ T cells (P = .006, P = .015), increased IFN-γ (P = .036, P = .045), decreased IL-10 (P = .009, P = .021), FOXP3 (P = .0244) and NFATC1 (P = .019). Severe GV (50%-75% VASI) patients showed reduced suppression of CD8⁺ and CD4⁺ T cells (P = .0003, P = .001), increased IFN-γ (P = .0029, P < .0001), decreased IL-10 (P = .0057, P = .0017), FOXP3 (P = .002) and NFATC1 (P = .0347). VASI score was positively correlated with the suppression of CD8⁺ and CD4⁺ T cells (P = .0006, P < .0001), IL-10 (P = .0096, P = .029), FOXP3 (P = .0008) and NFATC1 (P = .043), whereas it was negatively correlated with IFN-γ (P = .0029, P = .0017). Early age of onset patients' Tregs demonstrated decreased suppression of CD8⁺ and CD4⁺ T cells (P = .0156, P = .0074), decreased TGF-β (P = .0212, P = .0083) and NFATC1 (P = .0103). NFATC1 was positively correlated with FOXP3 in Tregs (P < .0001). Our results suggest impaired Tregs suppressive function in GV patients due to decreased NFATC1, FOXP3, CD25, IL-10 and TGF-β resulting into increased CD8⁺ and CD4⁺ T-cell proliferation and IFN-γ production. For the first time, decreased NFATC1 levels were correlated with decreased FOXP3, thereby altering Treg cell function in GV patients. Additionally, decreased Treg cell function also affected onset, activity and severity of GV.

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: Mechanisms of Pathogenesis and Treatment

Vitiligo is an autoimmune disease of the skin that targets pigment-producing melanocytes and results in patches of depigmentation that are visible as white spots. Recent research studies have yielded a strong mechanistic understanding of this disease. Autoreactive cytotoxic CD8+ T cells engage melanocytes and promote disease progression through the local production of IFN-γ, and IFN-γ-induced chemokines are then secreted from surrounding keratinocytes to further recruit T cells to the skin through a positive-feedback loop. Both topical and systemic treatments that block IFN-γ signaling can effectively reverse vitiligo in humans; however, disease relapse is common after stopping treatments. Autoreactive resident memory T cells are responsible for relapse, and new treatment strategies focus on eliminating these cells to promote long-lasting benefit. Here, we discuss basic, translational, and clinical research studies that provide insight into the pathogenesis of vitiligo, and how this insight has been utilized to create new targeted treatment strategies.

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.

Skin immunity and its dysregulation in atopic dermatitis, hidradenitis suppurativa and vitiligo

While the epidermis is the frontline defense against infections and indeed, it is a peripheral lymphoid organ, the same immunological mechanisms may initiate and sustain pathological conditions. Indeed, a deregulated action against exogenous pathogens could activate a T cell response in atopic dermatitis, hidradenitis suppurativa and vitiligo. Atopic dermatitis (AD) is a chronic inflammatory skin condition with a complex pathophysiology. Although T helper 2 immunity dysregulation is thought to be the main cause of AD etiopathogenesis, the triggering mechanism is not well understood, and the treatment is often difficult. As the AD, hidradenitis suppurativa (HS) is a chronic inflammatory skin disease with a dramatic impact on the quality of life of the affected patients. The exact pathophysiology of HS is still unclear, but many evidences report a follicular obstruction and subsequent inflammation with TNF-α, interleukin (IL)-1β, IL-10, and IL-17 involvement. Vitiligo is an autoimmune epidermal disorder which consists of melanocytes destruction and skin depigmentation. Melanocytes destruction is mainly due to their increased oxidative-stress sensitivity with a consequent activation of innate first and adaptative immunity (CD8⁺ T cells) later. The understanding of the triggering mechanisms of AD, HS and Vitiligo is pivotal to outline novel therapies aimed at regaining the physiological immune homeostasis of healthy skin. The aim of this review is to provide new insight on the pathogenesis of these skin diseases and to highlight on the new therapeutic approaches adopted in the treatment of AD, HS and Vitiligo.

Immunophenotype of circulatory T-helper cells in patients with non-segmental vitiligo

Introduction

Non-segmental vitiligo (NSV) is an immune-mediated skin depigmentation disease. Cytokine-mediated interaction between T lymphocytes and melanocytes leads to death of melanocytes, causing a defect in melanin synthesis and thereby depigmentation. There is an increased population of T-helper cells in the skin lesions as well as in the peripheral circulation in NSV. However, the relative percentage of each T-cell phenotype in the disease pathogenesis is rarely studied.

Aim

To study the immunophenotype of the different T-helper/Treg cell subsets in patients with NSV, in comparison to healthy controls.

Material and methods

A total of 80 patients with NSV and eighty age- and gender-matched healthy controls were recruited in this cross-sectional study. Disease activity was determined by vitiligo index of disease activity (VIDA) scoring. Peripheral blood mononuclear cells were separated by Ficoll-Paque density centrifugation, and T-cell immunophenotyping was done by flow cytometric analysis.

Results

In patients with NSV, we observed an imbalance in T-cell immunophenotype, characterized by an increase in Th1 (p < 0.0001) and Th17 cells (p = 0.01). There is no difference in relative percentage of Th2/Treg cells, as compared to the healthy controls (p > 0.05).

Conclusions

There is a significant immune-dysregulation with a preponderance of circulatory Th1/Th17 phenotype in NSV patients.

MicroRNA‑155 inhibits the proliferation of CD8+ T cells via upregulating regulatory T cells in vitiligo

It has been reported that loss and degradation of epidermal melanocytes is closely associated with the pathogenesis of vitiligo. In addition, CD8⁺ T and regulatory T (Treg) cells serve an important role during these two processes. MicroRNA-155 (miR-155) is known to contribute to the pathogenesis of vitiligo; however, the mechanism by which miR-155 regulates the development of vitiligo remains unclear. In the present study, naïve T and CD8⁺ T cells were isolated from a patient with non-segmental vitiligo by flow cytometry. The cells were differentiated into Treg cells by treatment with interleukin-2, transforming growth factor-β and retinoic acid. In addition, miR-155 agonists and antagonists were used to investigate the effect of miR-155 on the proliferation of CD8⁺ T cells, Treg cells and melanocytes. The results demonstrated that the miR-155 agonist significantly decreased the rate of CD8⁺ T cell growth, as well as promoted the proliferation of melanocytes by inducing an increase in the percentage of Treg cells. By contrast, the miR-155 antagonist inhibited the proliferation of melanocytes by decreasing the percentage of Treg cells. miR-155 protected melanocyte survival by increasing the number of Treg cells and by decreasing the number of CD8⁺ T cells. Therefore, these data may provide a new prospect for the treatment of vitiligo.

Identification of gene expression levels in primary melanoma associated with clinically meaningful characteristics

Factors influencing melanoma survival include sex, age, clinical stage, lymph node involvement, as well as Breslow thickness, presence of tumor-infiltrating lymphocytes based on histological analysis of primary melanoma, mitotic rate, and ulceration. Identification of genes whose expression in primary tumors is associated with these key tumor/patient characteristics can shed light on molecular mechanisms of melanoma survival. Here, we show results from a gene expression analysis of formalin-fixed paraffin-embedded primary melanomas with extensive clinical annotation. The Cancer Genome Atlas data on primary melanomas were used for validation of nominally significant associations. We identified five genes that were significantly associated with the presence of tumor-infiltrating lymphocytes in the joint analysis after adjustment for multiple testing: IL1R2, PPL, PLA2G3, RASAL1, and SGK2. We also identified two genes significantly associated with melanoma metastasis to the regional lymph nodes (PIK3CG and IL2RA), and two genes significantly associated with sex (KDM5C and KDM6A). We found that LEF1 was significantly associated with Breslow thickness and CCNA2 and UBE2T with mitosis. RAD50 was the gene most significantly associated with survival, with a higher level of expression associated with worse survival.

Perspectives of New Advances in the Pathogenesis of Vitiligo: From Oxidative Stress to Autoimmunity

Vitiligo is an autoimmune cutaneous disease in which melanocytes are destroyed by CD8⁺ T cells resulting in disfiguring white spots. From the very beginning of the disease, oxidative stress plays a significant role in promoting the onset of vitiligo, as noted by many studies. Multiple factors lead to the overproduction of reactive oxygen species (ROS), and collaboratively cause ROS accumulation in vulnerable melanocytes. However, ROS are responsible for melanocyte damage manifested by the level of molecules, organelles, and cells, and the generation of autoantigens, through different pathways related to the dysregulation of melanocytes. Recent studies have shown that presentation of autoantigens is mediated by innate immunity, which bridges the gap between oxidative stress and adaptive immunity. The recruitment of CD8⁺ T cells induced by cytokines and chemokines guarantees the final destruction of epidermal melanocytes. Moreover, emerging concerns regarding regulatory T cells and resident memory T cells help explain the reinstatement and relapse of vitiligo. Here, we provide new perspectives in the advances in understanding of this disease pathogenesis and we attempt to find more interrelationships between oxidative stress and autoimmunity.

Vitiligo: Focus on Clinical Aspects, Immunopathogenesis, and Therapy

Vitiligo is an acquired chronic depigmenting disorder of the skin, with an estimated prevalence of 0.5% of the general population, characterized by the development of white macules resulting from a loss of epidermal melanocytes. The nomenclature has been revised after an extensive international work within the vitiligo global issues consensus conference, and vitiligo (formerly non-segmental vitiligo) is now a consensus umbrella term for all forms of generalized vitiligo. Two other subsets of vitiligo are segmental vitiligo and unclassified/undetermined vitiligo, which corresponds to focal disease and rare variants. A series of hypopigmented disorders may masquerade as vitiligo, and some of them need to be ruled out by specific procedures including a skin biopsy. Multiple mechanisms are involved in melanocyte disappearance, namely genetic predisposition, environmental triggers, metabolic abnormalities, impaired renewal, and altered inflammatory and immune responses. The auto-immune/inflammatory theory is the leading hypothesis because (1) vitiligo is often associated with autoimmune diseases; (2) most vitiligo susceptibility loci identified through genome-wide association studies encode immunomodulatory proteins; and (3) prominent immune cell infiltrates are found in the perilesional margin of actively depigmenting skin. However, other studies support melanocyte intrinsic abnormalities with poor adaptation of melanocytes to stressors leading to melanocyte instability in the basal layer, and release of danger signals important for the activation of the immune system. Recent progress in the understanding of immune pathomechanisms opens interesting perspectives for innovative treatment strategies. The proof of concept in humans of targeting of the IFNγ /Th1 pathway is much awaited. The interplay between oxidative stress and altered immune responses suggests that additional strategies aiming at limiting type I interferon activation pathway as background stabilizing therapies could be an interesting approach in vitiligo. This review covers classification and clinical aspects, pathophysiology with emphasis on immunopathogenesis, and promising therapeutic approaches.

HO-1 regulates the function of Treg: Association with the immune intolerance in vitiligo

In vitiligo, cutaneous depigmentation is accompanied by increased T cell cytolytic activity targeting melanocytes, indicating that autoimmune tolerance is disrupted. The inhibited amount and function of Tregs have been indicated to be involved in the autoimmune intolerance in vitiligo, however, with the conclusion still controversial and the involved mechanism unknown. In this study, we explored the molecular and cellular alterations accounting for the impaired Treg response in vitiligo. Our results showed that the amount of Tregs was drastically reduced in peripheral blood of active vitiligo patients. Furthermore, the immunoregulatory function of Tregs was attenuated, with lower expression of CTLA4, IL‐10 and TGF‐β. Moreover, the expression of HO‐1, a functional modulator of Tregs, was decreased in vitiligo Tregs, and the concentrations of HO‐1 metabolites, including bilirubin, CoHb and iron, were correspondingly decreased in serum of vitiligo patients. In addition, we treated the Tregs from vitiligo patients with Hemin, an agonist of HO‐1, and found that enhanced HO‐1 expression restored the function of Tregs by up‐regulating IL‐10 expression. Our study demonstrates the essential role of HO‐1 in the impaired Treg response in vitiligo and indicates the potential of HO‐1 as a therapeutic target in vitiligo management.

Regulatory T cells in autoimmune skin diseases

CD4⁺ Foxp3⁺ regulatory T cells (Tregs) are suppressors of immune activation and play a crucial role in the maintenance of peripheral tolerance. Mutations of Foxp3 result in fatal autoimmunity in multiple organs, including the skin, in both humans and mice. Many studies have demonstrated the altered frequency and functions of Tregs, changes in cytokine and chemokine levels related to Tregs and the differences in genetic background regarding Tregs in autoimmune skin disorders. Recent studies have extended our knowledge of certain properties of Tregs, especially skin-resident Tregs. In addition, some novel therapies have been performed by modulating the number and the function of Tregs. This review focuses on the role of Tregs in some autoimmune skin disorders, including alopecia areata, vitiligo, pemphigoid and pemphigus, and systemic sclerosis, and discusses questions that remain to be addressed.

Superoxide Dismutase 1 and 2 Gene Polymorphism in Turkish Vitiligo Patients

Vitiligo is an acquired disease of unknown etiology. Several theories have been proposed to understand the pathogenesis. The role of oxidative stress has been getting more important in recent years. One of the primary antioxidant enzymes in vitiligo is the superoxide dismutase (SOD). The aim of this study is to investigate the polymorphisms of the SOD1 and SOD2 in Turkish vitiligo patients. One hundred one vitiligo patients and 99 healthy controls without family history of vitiligo were included into the study. The SOD1 35 A/C and SOD2 A16V (C/T) polymorphisms were analyzed by polymerase chain reaction-restriction fragment length polymorphim (PCR-RFLP). Vitiligo patients and control group of SOD1 35 A/C and SOD2 A16V (C/T) polymorphism allele frequencies were compared by using χ² tests. The distribution of the SOD1 35 AA and AC genotypes were similar in vitiligo patients and control group. When the patient and the control groups were compared for the SOD2 Ala9Val (C/T) polymorphism, a significant difference was determined for the distribution of the genotypes [p = 0.047, odds ratio (OR) = 2.075, 95% confidence interval (95% CI) = 1.008-4.272]. The relative risk for development of vitiligo was found as a 2-fold increase in the TT genotype. The increase of TT homozygosity in the vitiligo cases creates the problem on the transfer of the enzyme to the mitochondria and thus, the SODs antioxidant effect may decrease in vitiligo but the polymorphism was not determined in all patients, so this study needs to be substantiated by other studies containing a higher number of patients.

Altered expression of four miRNA (miR-1238-3p, miR-202-3p, miR-630 and miR-766-3p) and their potential targets in peripheral blood from vitiligo patients

Vitiligo is an acquired skin disease with pigmentary disorder. Autoimmune destruction of melanocytes is thought to be major factor in the etiology of vitiligo. miRNA-based regulators of gene expression have been reported to play crucial roles in autoimmune disease. Therefore, we attempt to profile the miRNA expressions and predict their potential targets, assessing the biological functions of differentially expressed miRNA. Total RNA was extracted from peripheral blood of vitiligo (experimental group, n = 5) and non-vitiligo (control group, n = 5) age-matched patients. Samples were hybridized to a miRNA array. Box, scatter and principal component analysis plots were performed, followed by unsupervised hierarchical clustering analysis to classify the samples. Quantitative reverse transcription polymerase chain reaction (RT-PCR) was conducted for validation of microarray data. Three different databases, TargetScan, PITA and microRNA.org, were used to predict the potential target genes. Gene ontology (GO) annotation and pathway analysis were performed to assess the potential functions of predicted genes of identified miRNA. A total of 100 (29 upregulated and 71 downregulated) miRNA were filtered by volcano plot analysis. Four miRNA were validated by quantitative RT-PCR as significantly downregulated in the vitiligo group. The functions of predicted target genes associated with differentially expressed miRNA were assessed by GO analysis, showing that the GO term with most significantly enriched target genes was axon guidance, and that the axon guidance pathway was most significantly correlated with these miRNA. In conclusion, we identified four downregulated miRNA in vitiligo and assessed the potential functions of target genes related to these differentially expressed miRNA.

A similar local immune and oxidative stress phenotype in vitiligo and halo nevus

BACKGROUND

Vitiligo and halo nevus are two common T-cell-mediated skin disorders. Although autoimmunity has been suggested to be involved in both diseases, the relationship between vitiligo and halo nevus is not fully understood.

OBJECTIVE

The aim of the current study was to investigate whether vitiligo and halo nevus share the same immunological and oxidative stress response.

METHODS

Infiltrations of T cells, and expressions of chemokine receptors (CXCR3, CCR4, CCR5) and cytotoxic markers (Granzyme B, Perforin) in the lesions of vitiligo and halo nevus were examined by immunohistochemistry. Enzyme-linked immunosorbent assay was performed to analyze the expressions of chemokines in the serum samples and cytotoxic markers secreted by CD8⁺ T cells which were sorted from the peripheral blood mononuclear cells in healthy donors, vitiligo and halo nevus patients. Tissue levels of chemokine receptors and CXCR3 ligands in healthy controls, vitiligo patients and halo nevus patients were determined by qRT-PCR analysis. The percentages of CXCR3⁺ CD4⁺ T and CXCR3⁺ CD8⁺ T cells from the peripheral blood samples were examined by flow cytometry. Tissue and serum hydrogen peroxide (H₂O₂) concentrations were measured using H₂O₂ assay kit.

RESULTS

Immunohistochemistry revealed a significant T-cell response, with pronounced dermal infiltrates of CD8⁺ T cells in vitiligo and halo nevus. The inflammatory cytotoxic markers such as Granzyme B and Perforin were also elevated in vitiligo and halo nevus, suggesting inflammatory responses in situ. By qRT-PCR and ELISA assay, we found significantly increased expressions of the chemokine receptor CXCR3 and its ligands, especially the accumulated CXCL10 in the skin lesions of vitiligo and halo nevus. Moreover, the level of H₂O₂, a key player involved in regulation of the immune response was significantly upregulated in the skin lesions of vitiligo and halo nevus. In addition, the increased H₂O₂ concentration correlated positively with CXCL10 level in skin lesions of vitiligo and halo nevus.

CONCLUSIONS

These results demonstrate a H₂O₂-involved autoimmune phenotype in vitiligo and halo nevus, characterized by increased level of IFN-γ-inducible chemokine pair CXCL10-CXCR3, as well as a dense CD8⁺ T infiltration in the skin lesions, thus suggesting a similar pathogenesis of the two diseases.

Enhanced Th1 and Th17 responses in peripheral blood in active non-segmental vitiligo

Accumulating studies have indicated that vitiligo, especially non-segmental vitiligo (NSV), is one kind of autoimmune diseases and CD4⁺ T cells play important roles in the pathogenesis. However, there have been very limited data on the detailed changes of each of the CD4⁺ T cell subsets in periphery in active NSV. To clarify this issue, we collected the peripheral blood mononuclear cells (PBMCs) from 30 patients with active NSV and 30 age- and sex-matched healthy controls. The percentages of circulating Th1, Th2, Th17 and Tregs were evaluated using flow cytometry and the expressions of their specific transcription factors T-bet, GATA3, RORγt and FOXP3 at mRNA level and protein levels were qualified by qPCR and flow cytometry, respectively. Meanwhile, the expression levels of IFN-γ, IL-4, TGF-β, and IL-17A in serum were measured. We found that in patients with NSV, the percentages and absolute numbers of circulating Th1 and Th17 were both significantly higher than those of healthy controls, while the percentages of Th2 and Tregs and absolute numbers showed no significant difference compared to healthy controls. Moreover, the ratios of Th1/Tregs and Th17/Tregs in circulation were both statistically elevated in active NSV. Similar results were got in qualification of their corresponding transcription factors at mRNA level and protein levels. Compared with healthy controls, the expression level of IL-17A was significantly increased in serum of patients with NSV, while the productions of IFN-γ, IL-4, TGF-β had no significant change. These data suggested that in circulating CD4⁺ T cell subsets, Th1 and Th17 played the major role in cellular immunity in the progression of vitiligo. The immune lever in circulation was inclined to effector CD4⁺ T cells not suppressor CD4⁺ T cells that may result in the loss of self-tolerance to melanocytes.

Induction of regulatory T cells: A role for probiotics and prebiotics to suppress autoimmunity

Regulatory T cells (Tregs) are comprised of a heterogeneous population of cells that play a vital role in suppressing inflammation and maintaining immune tolerance. Given the crucial role of Tregs in maintaining immune homeostasis, it is probably not surprising that many microbial species and their metabolites have the potential to induce Tregs. There is now great interest in the therapeutic potential of probiotics and prebiotics based strategies for a range of autoimmune disorders. This review will summarise recent findings concerning the role of probiotics and prebiotics in induction of Tregs to ameliorate the autoimmune conditions. In addition, the article is focused to explain the different mechanisms of Treg induction and function by these probiotics and prebiotics, based on the available studies till date. The article further proposes that induction of Tregs by probiotics and prebiotics could lead to the development of new therapeutic approach towards curbing the autoimmune response and as an alternative to detrimental immunosuppressive drugs.

Decreased Circulating T Regulatory Cells in Egyptian Patients with Nonsegmental Vitiligo: Correlation with Disease Activity

Background. Vitiligo is an acquired depigmentary skin disorder resulting from autoimmune destruction of melanocytes. Regulatory T cells (Tregs), specifically CD4⁺CD25⁺ and Forkhead box P3⁺ (FoxP3⁺) Tregs, acquired notable attention because of their role in a variety of autoimmune pathologies. Dysregulation of Tregs may be one of the factors that can break tolerance to melanocyte self-antigens and contribute to vitiligo pathogenesis. Methods. In order to sustain the role of Tregs in pathogenesis and disease activity of vitiligo, surface markers for CD4⁺CD25⁺ and FoxP3⁺ peripheral Tregs were evaluated by flow cytometry in 80 Egyptian patients with nonsegmental vitiligo in addition to 60 healthy control subjects and correlated with clinical findings. Results. Vitiligo patients had significantly decreased numbers of both peripheral CD4⁺CD25⁺ and FoxP3⁺ T cells compared to control subjects (11.49%  ± 8.58% of CD4⁺ T cells versus 21.20%  ± 3.08%, and 1.09%  ± 0.96% versus 1.44%  ± 0.24%, resp., P < 0.05 for both). Peripheral numbers of CD4⁺CD25⁺ and FoxP3⁺ Tregs correlated negatively with VIDA score. Conclusion. Treg depletion with impaired immune downregulatory function might play a key role in the autoimmune conditions beyond nonsegmental vitiligo particularly in active cases. Effective Treg cell-based immunotherapies might be a future hope for patients with progressive vitiligo.

AHR promoter variant modulates its transcription and downstream effectors by allele-specific AHR-SP1 interaction functioning as a genetic marker for vitiligo

Vitiligo is an acquired depigmentation disorder largely caused by defective melanocyte- or autoimmunity-induced melanocyte destruction. The aryl hydrocarbon receptor (AHR) is essential for melanocyte homeostasis and immune process, and abnormal AHR was observed in vitiligo. We previously identified the T allele of AHR -129C > T variant as a protective factor against vitiligo. However, biological characterization underlying such effects is not fully certain, further validation by mechanistic research is warranted and was conducted in the present study. We showed that -129T allele promoted AHR transcriptional activity through facilitating its interaction with SP1 transcription factor (SP1) compared with -129C allele. We subsequently found reduced peripheral AHR and SP1 transcript expressions in vitiligo and a negative correlation of AHR level with disease duration. We also investigated AHR-related cytokines and observed increased serum TNF-α concentration and diminished serum levels of IL-10 and TGF-β1 in vitiligo. Further genetic analysis showed that -129T carriers possessed higher levels of AHR and IL-10 than -129C carriers. Therefore, our study indicates that the modulation of AHR transcription by a promoter variant has a profound influence on vitiligo, not only advancing our understanding on AHR function but also providing novel insight into the pathogenesis of degenerative or autoimmune diseases including vitiligo.

Alteration in regulatory T cells and programmed cell death 1-expressing regulatory T cells in active generalized vitiligo and their clinical correlation

BACKGROUND

Vitiligo is an autoimmune depigmentation disease, and defects in regulatory T cells (Tregs) have been proposed in the pathogenesis of generalized vitiligo (GV). However, the role of programmed cell death (PD)1(+) Tregs has not been studied.

OBJECTIVES

To investigate the status of Tregs, PD1(+) Tregs and associated parameters in active GV (aGV) during the first episode of disease attack and to establish the clinical correlation.

METHODS

The percentages of circulating Tregs, PD1(+) Tregs and CD3(+) CD4(+) PD1(+) T cells were evaluated in 50 patients with aGV and 51 controls. Expression levels of FOXP3, TGFB1, CTLA4 and genes for chemokine receptors (CCR4, CCR7) and their ligands (CCL21, CCL22) were quantified in peripheral blood and in lesional, perilesional, nonlesional and normal skin sections. The corresponding proteins were immunolocalized in tissue of aGV.

RESULTS

The percentage of Tregs was decreased (P = 0·001) and that of PD1(+) Tregs increased (P = 0·001) in peripheral blood of patients with aGV compared with controls. The abundance of TGFB1 and CCL21 mRNA was significantly decreased in the peripheral blood of patients with aGV. Significant differences in forkhead box P3, transforming growth factor-β and CCL21 protein expression were found in skin sections.

CONCLUSIONS

Deficiency in Treg frequency and decreased expression of Treg-associated parameters (TGFB and CCL21) suggested a possible defect in Tregs that may alter their suppression function and skin homing in aGV. The increased PD1(+) Tregs suggests that the PD1/PD ligand pathway may be involved in aGV and may have a role in Treg exhaustion. Further study is required to delineate the effect of PD1 in regulating Treg function in aGV.

Regulatory T cells in vitiligo: Implications for pathogenesis and therapeutics

Vitiligo is a hypomelanotic autoimmune skin disease arising from a breakdown in immunological self-tolerance, which leads to aberrant immune responses against melanocytes. Regulatory T cells (Tregs) are crucial to the development of self-tolerance and so are major foci in the study of autoimmune pathogenesis of vitiligo. This review will summarise recent findings concerning the role of Tregs in the pathogenesis of vitiligo. In addition, as antigen-specific Tregs are a potential route for the reinstatement of immune tolerance, new strategies that expand or induce de novo generation of Tregs and which are currently being investigated as therapies for other autoimmune diseases, will be discussed. These approaches will highlight the opportunities for Treg cell-based therapeutics in vitiligo.

Vitiligo--part 1

Vitiligo is a chronic stigmatizing disease, already known for millennia, which mainly affects melanocytes from epidermis basal layer, leading to the development of hypochromic and achromic patches. Its estimated prevalence is 0.5% worldwide. The involvement of genetic factors controlling susceptibility to vitiligo has been studied over the last decades, and results of previous studies present vitiligo as a complex, multifactorial and polygenic disease. In this context, a few genes, including DDR1, XBP1 and NLRP1 have been consistently and functionally associated with the disease. Notwithstanding, environmental factors that precipitate or maintain the disease are yet to be described. The pathogenesis of vitiligo has not been totally clarified until now and many theories have been proposed. Of these, the autoimmune hypothesis is now the most cited and studied among experts. Dysfunction in metabolic pathways, which could lead to production of toxic metabolites causing damage to melanocytes, has also been investigated. Melanocytes adhesion deficit in patients with vitiligo is mainly speculated by the appearance of Köebner phenomenon, recently, new genes and proteins involved in this deficit have been found.

Serum miRNA expression profiles change in autoimmune vitiligo in mice

It is widely believed that non-segmental vitiligo results from the autoimmune destruction of melanocytes. MicroRNAs (miRNAs), a class of small non-coding RNAs that negatively regulate gene expression, are involved in the immune cell development and function and regulate the development of autoimmune diseases. Recent studies demonstrate that functional miRNAs can be detected in the serum and serve as biomarkers of various diseases. In the present study, we used a mouse autoimmune vitiligo model, in which melanocyte autoreactive CD4+ T cells were adoptively transferred into Rag1(-/-) host mice. Serum miRNA expression was profiled in vitiligo developed mice and control mice using TaqMan RT-PCR arrays. We have found that the expressions of 20 serum miRNAs were changed in vitiligo mice compared to control mice. Three increased miRNAs, miR-146a, miR-191, and miR-342-3p, were further confirmed by a single TaqMan RT-PCR. Our findings suggest that miRNAs may be involved in vitiligo development and serum miRNAs could serve as serum biomarkers for vitiligo in mice.

Association between FOXP3 polymorphisms and vitiligo in a Han Chinese population

BACKGROUND

Vitiligo is an autoimmune chronic depigmentation disorder caused by melanocyte loss. Previous studies found that CD4(+)CD25(+) regulatory T-cell (Treg) dysfunction was involved in the pathogenesis of vitiligo and that gene polymorphisms in forkhead box P3 (FOXP3) - a master regulator of Treg development and function - were associated with susceptibility to some autoimmune disorders. Therefore, we hypothesized that functional polymorphisms of the FOXP3 gene might be associated with vitiligo via dysregulation of Treg cells.

OBJECTIVES

To evaluate whether FOXP3 polymorphisms are associated with vitiligo risk.

MATERIAL AND METHODS

In this hospital-based case-control study of 682 patients with vitiligo and 682 vitiligo-free age- and sex-matched controls, we genotyped three single nucleotide polymorphisms (SNPs) of the FOXP3 gene - rs2232365, rs3761548 and rs5902434 - by performing polymerase chain reaction with sequence-specific primers (PCR-SSP).

RESULTS

Significantly increased vitiligo risk was associated with the rs2232365 GG [odds ratio (OR) 1·68, 95% confidence interval (CI) 1·17-2·39, P = 0·004] and rs3761548 AA (OR 1·82, 95% CI 1·10-3·01, P = 0·033) genotypes compared with the rs2232365 AA and rs3761548 CC genotypes. On combined analysis of these three variant alleles, we found that individuals carrying 2-6 variant alleles had significantly increased vitiligo risk (OR 1·34, 95% CI 1·08-1·66). This risk was more pronounced in the following subgroups: age > 20 years, male sex, active vitiligo, nonsegmental vitiligo and other accompanying autoimmune diseases.

CONCLUSIONS

FOXP3 gene polymorphisms contributed to vitiligo risk in a Han Chinese population.