Immunohistochemical studies from vitiligo--comparison between active and inactive lesions

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.

The convergence theory for vitiligo: A reappraisal

Vitiligo is characterized by progressive loss of skin pigmentation. The search for aetiologic factors has led to the biochemical, the neurologic and the autoimmune theory. The convergence theory was then proposed several years ago to incorporate existing theories of vitiligo development into a single overview of vitiligo aetiology. The viewpoint that vitiligo is not caused only by predisposing mutations, or only by melanocytes responding to chemical/radiation exposure, or only by hyperreactive T cells, but rather results from a combination of aetiologic factors that impact melanocyte viability, has certainly stood the test of time. New findings have since informed the description of progressive depigmentation. Understanding the relative importance of such aetiologic factors combined with a careful selection of the most targetable pathways will continue to drive the next phase in vitiligo research: the development of effective therapeutics. In that arena, it is likewise important to acknowledge that pathways affected in some patients may not be altered in others. Taken together, the convergence theory continues to provide a comprehensive viewpoint of vitiligo aetiology. The theory serves to intertwine aetiologic pathways and will help to define pathways amenable to disease intervention in individual patients.

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.

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.

Clinicopathologic Analysis of Stable and Unstable Vitiligo: A Study of 66 Cases

Vitiligo is an acquired skin disorder characterized by milky-white macules and absence of functioning melanocytes. The cornerstone of its management is the correct categorization of a case into its 2 broad types-stable and unstable vitiligo. This distinction is at present based mainly on clinical criteria because the histopathological features are not fully established. This study was thus undertaken to examine histopathological features of vitiligo and to come up with a reliable and systematic approach toward this diagnostic challenge. All patients presenting with clinical features of vitiligo at our institution were included in the study. A 3-mm punch biopsy was taken from 3 sites-lesional, perilesional, and normal skin. Histopathological examination was primarily focused on evaluating 5 histopathological variables-spongiosis, epidermal lymphocytes, basal cell vacuolation, dermal lymphocytes, and melanophages. A total number of 66 patients were included in the study. There were 30 patients in stable and 36 in unstable vitiligo groups. It was observed that all 5 histopathological pattens were associated with unstable vitiligo. All the cases were then scored using a scoring system devised by the authors and the scores obtained were correlated with clinical categorization. It was observed that while there is a definite overlap in histological findings in the 2 groups, adoption of a systematic reporting system brings more consistency and objectivity in the diagnosis. The authors have recommended diagnoses that should be reported for the various scores. This in turn will help us to more reliably and confidently manage these patients.

Reduced immunohistochemical expression of adhesion molecules in vitiligo skin biopsies

Because defects in adhesion impairment seem to be involved in the etiopathogenesis of vitiligo, this study aimed to compare the immunohistochemical expression of several adhesion molecules in the epidermis of vitiligo and non lesional vitiligo skin. Sixty-six specimens of lesional and non lesional skin from 33 volunteers with vitiligo were evaluated by immunohistochemistry using anti-beta-catenin, anti-E-cadherin, anti-laminin, anti-beta1 integrin, anti-collagen IV, anti-ICAM-1 and anti-VCAM-1 antibodies. Biopsies of vitiligo skin demonstrated a significant reduction in the expression of laminin and integrin. The average value of the immunohistochemically positive reaction area of the vitiligo specimens was 3053.2μm², compared with the observed value of 3431.8μm² in non vitiligo skin (p=0.003) for laminin. The immuno-positive area was 7174.6μm² (vitiligo) and 8966.7μm² (non lesional skin) for integrin (p=0.042). A reduction in ICAM-1 and VCAM-1 expression in the basal layer of the epidermis in vitiligo samples was also observed (p=0.001 and p<0.001, respectively). However, no significant differences were observed with respect to the expression of beta-catenin, E-cadherin, and collagen IV between vitiligo and non lesional skin. Our results suggest that an impairment in adhesion exists in vitiligo skin, which is supported by the diminished immunohistochemical expression of laminin, beta1 integrin, ICAM-1 and VCAM-1.

Possible patterns of epidermal melanocyte disappearance in nonsegmental vitiligo: a clinicopathological study

BACKGROUND

The depigmentation of vitiligo results in a progressive and chronic melanocyte loss with rare melanocytes occasionally remaining in the epidermis or the hair follicle reservoirs. Destruction by immune infiltrates in close contact with melanocytes within microvesicles and/or detachment of melanocytes followed by their transepidermal elimination should be regarded as possible mechanisms of chronic loss of pigment cells.

OBJECTIVES

To assess the frequency of these two histological findings and to establish a direct correlation with clinical features.

METHODS

This was a prospective observational study that took place over 1 year. Each patient received a standardized evaluation that included daylight and Wood's lamp examinations, pictures, biopsies performed on the marginal area, and histological and immunohistological studies. A second examination to assess the activity of the lesions was performed 1 year after inclusion in the study. Clinical changes associated with microvesicles were compared with those associated with detached melanocytes from the basal layer.

RESULTS

This study included 50 patients. The histological findings were classified as inflammatory with isolated microvesicles (29 cases), noninflammatory with only detached melanocytes from the basal layer (12 cases) and a combination of coexisting microvesicles and detached melanocytes (six cases). Correlations were obtained between the histological findings and clinical features (aspect and activity of the lesions) and E-cadherin expression.

CONCLUSIONS

Our data suggest the existence of two patterns of melanocyte disappearance in nonsegmental vitiligo.

Stability in Vitiligo: Is there a Perfect Way to Predict it?

Stability is a hard-to-define concept in the setting of vitiligo, but is nonetheless extremely crucial to the planning of treatment regimens and also in prognosticating for the patient. There are several ways to judge stability in vitiligo, which include clinical features and, recently, many biochemical, cytological and ultrastructural correlates of the same. These recent advances help in not only in prognosticating individual patients but also in elucidating some of the mechanisms for the pathogenesis of vitiligo, including melanocytorrhagy and oxidative damage to melanocytes.

Tumor necrosis factor B (TNFB) genetic variants and its increased expression are associated with vitiligo susceptibility

Genetic polymorphisms in TNFB are involved in the regulation of its expression and are found to be associated with various autoimmune diseases. The aim of the present study was to determine whether TNFB +252A/G (rs909253) and exon 3 C/A (rs1041981) polymorphisms are associated with vitiligo susceptibility, and expression of TNFB and ICAM1 affects the disease onset and progression. We have earlier reported the role of TNFA in autoimmune pathogenesis of vitiligo, and we now show the involvement of TNFB in vitiligo pathogenesis. The two polymorphisms investigated in the TNFB were in strong linkage disequilibrium and significantly associated with vitiligo. TNFB and ICAM1 transcripts were significantly increased in patients compared to controls. Active vitiligo patients showed significant increase in TNFB transcripts compared to stable vitiligo. The genotype-phenotype analysis revealed that TNFB expression levels were higher in patients with GG and AA genotypes as compared to controls. Patients with the early age of onset and female patients showed higher TNFB and ICAM1 expression. Overall, our findings suggest that the increased TNFB transcript levels in vitiligo patients could result, at least in part, from variations at the genetic level which in turn leads to increased ICAM1 expression. For the first time, we show that TNFB +252A/G and exon 3 C/A polymorphisms are associated with vitiligo susceptibility and influence the TNFB and ICAM1 expression. Moreover, the study also emphasizes influence of TNFB and ICAM1 on the disease progression, onset and gender bias for developing vitiligo.

The concept of stability of vitiligo: a reappraisal

Stability is taken as the most important parameter before opting for any transplantation technique to treat vitiligo. But, simultaneous donor site repigmentation and depigmentation of grafts at the recipient site has been noted. Similarly donor site depigmentation with complete repigmentation of the recipient area with pigment growing out from each graft has been observed. Successful repigmentation after regrafting in previous punch failure cases has also been reported. Koebner's phenomenon from history (Kp-h) and test grafting were the only available indicators to assess stability. It is quite ironic to note that even after four decades of experience in vitiligo surgery, there seems to be little consensus among workers regarding the optimal required period of stability. Moreover, the exact concept of stability in vitiligo is itself still not transparent and defined beyond doubt Overdependence on KpH or TG may be sometimes misleading in vitiligo. These two reveal the apparent clinical stability only and that may not be the true reflection of stability status of the disease at the molecular level. Antimelanocyte cytotoxic reactivity was observed among CD8+ TCC isolated from perilesional biopsies of patients with vitiligo. An attempt should be made to clearly fathom and define stability, not merely only on clinical ground but along with electron microscopy and histoenzymological analysis of the perilesional and nonlesional skin of vitiligo patients. Probably some growth factors which are responsible for both mitogenic and melanogenic stimulation of melanocytes should also be taken into account. Some serological test(s) could guide us to measure these growth factors.

A mouse model of vitiligo with focused epidermal depigmentation requires IFN-γ for autoreactive CD8⁺ T-cell accumulation in the skin

Vitiligo is an autoimmune disease of the skin causing disfiguring patchy depigmentation of the epidermis and, less commonly, hair. Therapeutic options for vitiligo are limited, reflecting in part limited knowledge of disease pathogenesis. Existing mouse models of vitiligo consist of hair depigmentation but lack prominent epidermal involvement, which is the hallmark of human disease. They are thus unable to provide a platform to fully investigate disease mechanisms and treatment. CD8⁺ T cells have been implicated in the pathogenesis of vitiligo and expression of interferon-gamma (IFN-γ) is increased in the lesional skin of patients, however it is currently unknown what role IFN-γ plays in disease. Here, we have developed an adoptive transfer mouse model of vitiligo using melanocyte-specific CD8⁺ T cells, which recapitulates the human condition by inducing epidermal depigmentation while sparing the hair. Like active lesions in human vitiligo, histology of depigmenting skin reveals a patchy mononuclear infiltrate and single-cell infiltration of the epidermis. Depigmentation is accompanied by accumulation of autoreactive CD8⁺ T cells in the skin, quantifiable loss of tyrosinase transcript, and local IFN-γ production. Neutralization of IFN-γ with antibody prevents CD8⁺ T cell accumulation and depigmentation, suggesting a therapeutic potential for this approach.

Childhood vitiligo in China: clinical profiles and immunological findings in 620 cases

BACKGROUND

Childhood vitiligo is a common pediatric skin disorder. The pathogenesis of vitiligo is unclear, and immunological dysfunction may play an important role.

OBJECTIVES

This prospective study aimed to profile childhood vitiligo and to discuss its correlation with immunological dysfunction.

METHODS

All of the 620 enrolled patients were aged younger than 14 years, and were assessed with a standard questionnaire. The levels of immunoglobulins, complement, and T-lymphocyte subsets were measured in 270 of these 620 patients.

RESULTS

Of the 620 children, 302 (48.71%) were boys and 318 (51.29%) were girls, with an average disease onset age of 7.57 years. The average duration was 13.45 months. 453 (73.06%) children had head and neck involvement and 160 (25.81%) children had segmental vitiligo. 84 (13.55%) children had a family history. There was a correlation between the disease and seasons. The onset or progression usually occurred in summer and spring. Halo nevus was seen in both segmental and non-segmental vitiligo. Precipitating factors such as stress appeared more commonly in segmental vitiligo. As to the immunological findings, in segmental vitiligo, the levels of C3 and C4 were lower in the active relative to the quiescent stage (p < 0.05); and in non-segmental vitiligo, the percentages of CD3+ and CD4+ lymphocytes and the CD4+/CD8+ ratio were lower in the active relative to the quiescent stage (p < 0.01).

CONCLUSIONS

Childhood vitiligo has its own clinical features. The different types of vitiligo have different characteristics. There is immunological dysfunction in children with vitiligo. Dysfunction of humoral immunity may play a role in the progression of segmental vitiligo, while non-segmental vitiligo is more related to cellular immunity.

Antígenos de histocompatibilidade humanos e dermatologia: da pesquisa para a prática clínica

A participação do sistema de histocompatibilidade humano (HLA: human leukocyte antigens) na patogênese das doenças auto-imunes é bem conhecida. Situado no braço curto do cromossomo 6, o sistema HLA se destaca por seu polimorfismo e por sua capacidade de conferir susceptibilidade ou proteção a diferentes enfermidades. Em Dermatologia, esse sistema desempenha papel importante na patogenia e história natural de várias doenças. A força e o tipo de associação variam com a dermatose e, algumas vezes, com o grupo étnico-racial estudado. O surgimento de métodos moleculares para tipificação dos alelos HLA e as recentes atualizações de sua nomenclatura têm contribuído para o melhor entendimento desse sistema. Infelizmente, essas informações não têm sido veiculadas de maneira adequada na literatura clínica, o que dificulta o entendimento da associação do HLA com as doenças cutâneas. Nesta revisão, são discutidos alguns aspectos do sistema HLA, métodos de detecção, nomenclatura e sua associação com vitiligo, pênfigo, psoríase, lúpus eritematoso, escabiose, leishmaniose cutânea, hanseníase, paracoccidioidomicose e dermatite atópica.

New Treatment Modalities for Vitiligo

The development of effective treatment modalities for vitiligo is dependent on an understanding of the events leading to depigmentation. However, the exact pathogenesis of vitiligo is still mostly unknown. Abnormalities in both humoral and cell-mediated immunity have been documented in vitiligo patients and they present a basis for using immunomodulating agents, such as corticosteroids and macrolide immunomodulators, in the treatment of vitiligo. Macrolide immunomodulators, such as tacrolimus and pimecrolimus, which can be used topically, are known as topical immunomodulators (TIMs). TIMs inhibit the action of calcineurin, and consequently inhibit T-cell activation and the production of various cytokines; this is considered the working mechanism of action of TIMs in vitiligo. Several small studies and case reports on the use of TIMs in vitiligo have been published so far. Tacrolimus achieves better results on the face and neck than on other body areas. Particular advantages of TIMs are safety in treating these areas because of lack of skin atrophy and good tolerability. The incidence of application site adverse events in vitiligo seems to be lower than in the treatment of atopic dermatitis. On the face and neck, TIMs may become a useful tool in the treatment of adults and children with vitiligo despite possibly lower efficacy than topical corticosteroids. Further, larger, controlled clinical studies are warranted to determine the definite role of TIMs as monotherapy or in combination with other modalities in the treatment of vitiligo.

Evidence for an autoimmune pathogenesis of vitiligo

Vitiligo is a depigmenting disorder characterized by the development of white patches in various distributions, which are due to the loss of melanocytes from the epidermis. A variety of arguments from clinical observations to research findings in human and animal models support the hypothesis of autoimmunity and are reviewed in this article. The association with autoimmune diseases and organ-specific autoantibodies is well known. Various effective treatment options have an immunosuppressive effect. Today the autoimmune pathogenesis of the disease has become a rapidly evolving field of research. Detection of circulating melanocyte antibodies in human and animal models implicates a possible role of humoral immunity. Histological and immunohistochemical studies in perilesional skin suggest the involvement of cellular immunity in vitiligo. Recently, T-cell analyses in peripheral blood further support this hypothesis. Interestingly, new insights in the association of vitiligo and melanoma may help to clarify the role of autoimmunity in the development of vitiligo.

Topical tacrolimus for repigmentation of vitiligo

We describe 6 patients with generalized vitiligo who responded to treatment with tacrolimus ointment. Moderate to excellent repigmentation was achieved in 5 patients. Although the number of cases in this noncontrolled, nonblinded series is small, tacrolimus ointment may be an efficacious and safe treatment option for vitiligo.

Transfer of vitiligo after allogeneic bone marrow transplantation

Adoptive transfer of donor immunity has been demonstrated in animals after bone marrow transplantation (BMT). In humans, several autoimmune diseases have been similarly transferred. Although BMT may, per se, be associated with a modulation of the recipient's immune system, which could trigger or even cause autoimmune diseases, both animal experiments and experience with humans show the likeliness of adoptive transfer of donor immunity to the recipient. We describe a patient with multiple myeloma in whom generalized vitiligo developed within 3 months after allogeneic BMT from his HLA-matched sister with vitiligo. We believe that a form of adoptive transfer of donor immunity to the recipient might play a role in the development of vitiligo. In spite of this, neither de novo development of vitiligo in a genetically predisposed patient nor autoimmune phenomena associated with graft-versus-host disease can be completely excluded as a contributing factor for development of vitiligo in our patient. To our knowledge, this is the first case report of transfer of vitiligo after BMT from a donor with vitiligo.

Vitiligo melanocytes in long-term culture show normal constitutive and cytokine-induced expression of intercellular adhesion molecule-1 and major histocompatibility complex class I and class II molecules

The aetiology of vitiligo remains unclear. An autoimmune involvement has been suggested and, in this study, we examine whether melanocytes cultured from unaffected regions of the skin of vitiligo patients are more susceptible to immune attack by investigating constitutive and cytokine-stimulated expression of intercellular adhesion molecule-1 (ICAM-1) (under three media variants) and major histocompatibility complex (MHC) class I and class II (under one medium). Both normal and vitiligo melanocytes had similarly low constitutive expression of ICAM-1 and MHC class II molecules, whereas > 95% of cells had high constitutive expression of MHC class I. Normal and vitiligo melanocytes showed similar and significant increases in the expression of all three immune-related molecules in response to the cytokine, interferon-gamma. The expression of ICAM-1 was also similarly increased by the cytokine, tumour necrosis factor-alpha in both cells. Additionally, it was noted that, once the melanocyte cultures were established under experimental conditions, the rate of proliferation of vitiligo melanocytes did not differ significantly from that of normal melanocytes. In conclusion, we suggest that vitiligo melanocytes, once in culture, do not have intrinsic differences from normal melanocytes with respect to the expression of immune-related molecules.