Autoimmune vitiligo: detection of antibodies to melanin-producing cells

Mitochondria-Melanocyte cellular interactions: An emerging mechanism of vitiligo pathogenesis

Mitochondria has emerged as a potential modulator of melanocyte function other than just meeting its cellular ATP demands. Mitochondrial DNA defects are now an established cause of maternal inheritance diseases. Recent cellular studies have highlighted the mitochondrial interaction with other cellular organelles that lead to disease conditions such as in Duchenne muscular dystrophy, where defective mitochondria was found in melanocytes of these patients. Vitiligo, a depigmentory ailment of the skin, is another such disorder whose pathogenesis is now found to be associated with mitochondria. The complete absence of melanocytes at the lesioned site in vitiligo is a fact; however, the precise mechanism of this destruction is still undefined. In this review we have tried to discuss and link the emerging facts of mitochondrial function or its inter- and intra-organellar communications in vitiligo pathogenesis. Mitochondrial close association with melanosomes, molecular involvement in melanocyte-keratinocyte communication and melanocyte survival are new paradigm of melanogenesis that could ultimately account for vitiligo. This definitely adds the new dimensions to our understanding of vitiligo, its management and designing of future mitochondrial targeted therapy for vitiligo.

Vitiligo-Thyroid Disease Association: When, in Whom, and Why Should It Be Suspected? A Systematic Review

In most dermatological pathologies, the phenomena observed on the skin are a reflection of internal disorders. In patients with associated acral involvement on the dorsal sides of the hands, this "vitiligo phenotype" may lead to the investigation of certain associated pathologies that sometimes have no obvious clinical impact. To assess the link between skin depigmentation and autoimmune pathologies, we conducted a systematic review involving article selection from the PubMed database. Patients with coexisting thyroid pathologies were found to have a predisposition for developing acral vitiligo and depigmentation of the wrists, and autoimmune thyroid pathologies appeared to be the only coexisting autoimmune or inflammatory diseases in vitiligo patients to show a pattern of distribution. The association of concomitant thyroid dysfunction with depigmentation of the hands was found to be so strong that the absence of depigmented macules on the hands may exclude the coexistence of an autoimmune thyroid pathology. Although the frequency of acral involvement in patients with vitiligo and autoimmune pathologies is higher, the mechanism by which thyroid dysfunction influences this distribution pattern remains incompletely elucidated and requires future studies.

Translational Research in Vitiligo

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

The Role of the IL-33/ST2 Immune Pathway in Autoimmunity: New Insights and Perspectives

Interleukin (IL)-33, a member of IL-1 cytokine family, is produced by various immune cells and acts as an alarm to alert the immune system after epithelial or endothelial cell damage during cell necrosis, infection, stress, and trauma. The biological functions of IL-33 largely depend on its ligation to the corresponding receptor, suppression of tumorigenicity 2 (ST2). The pathogenic roles of this cytokine have been implicated in several disorders, including allergic disease, cardiovascular disease, autoimmune disease, infectious disease, and cancers. However, alerted levels of IL-33 may result in either disease amelioration or progression. Genetic variations of IL33 gene may confer protective or susceptibility risk in the onset of autoimmune diseases. The purpose of this review is to discuss the involvement of IL-33 and ST2 in the pathogenesis of a variety of autoimmune disorders, such as autoimmune rheumatic, neurodegenerative, and endocrine diseases.

Vitiligo blood transcriptomics provides new insights into disease mechanisms and identifies potential novel therapeutic targets

BACKGROUND

Significant gaps remain regarding the pathomechanisms underlying the autoimmune response in vitiligo (VL), where the loss of self-tolerance leads to the targeted killing of melanocytes. Specifically, there is incomplete information regarding alterations in the systemic environment that are relevant to the disease state.

METHODS

We undertook a genome-wide profiling approach to examine gene expression in the peripheral blood of VL patients and healthy controls in the context of our previously published VL-skin gene expression profile. We used several in silico bioinformatics-based analyses to provide new insights into disease mechanisms and suggest novel targets for future therapy.

RESULTS

Unsupervised clustering methods of the VL-blood dataset demonstrate a "disease-state"-specific set of co-expressed genes. Ontology enrichment analysis of 99 differentially expressed genes (DEGs) uncovers a down-regulated immune/inflammatory response, B-Cell antigen receptor (BCR) pathways, apoptosis and catabolic processes in VL-blood. There is evidence for both type I and II interferon (IFN) playing a role in VL pathogenesis. We used interactome analysis to identify several key blood associated transcriptional factors (TFs) from within (STAT1, STAT6 and NF-kB), as well as "hidden" (CREB1, MYC, IRF4, IRF1, and TP53) from the dataset that potentially affect disease pathogenesis. The TFs overlap with our reported lesional-skin transcriptional circuitry, underscoring their potential importance to the disease. We also identify a shared VL-blood and -skin transcriptional "hot spot" that maps to chromosome 6, and includes three VL-blood dysregulated genes (PSMB8, PSMB9 and TAP1) described as potential VL-associated genetic susceptibility loci. Finally, we provide bioinformatics-based support for prioritizing dysregulated genes in VL-blood or skin as potential therapeutic targets.

CONCLUSIONS

We examined the VL-blood transcriptome in context with our (previously published) VL-skin transcriptional profile to address a major gap in knowledge regarding the systemic changes underlying skin-specific manifestation of vitiligo. Several transcriptional "hot spots" observed in both environments offer prioritized targets for identifying disease risk genes. Finally, within the transcriptional framework of VL, we identify five novel molecules (STAT1, PRKCD, PTPN6, MYC and FGFR2) that lend themselves to being targeted by drugs for future potential VL-therapy.

Cellular stress and innate inflammation in organ-specific autoimmunity: lessons learned from vitiligo

For decades, research in autoimmunity has focused primarily on immune contributions to disease. Yet recent studies report elevated levels of reactive oxygen species and abnormal activation of the unfolded protein response in cells targeted by autoimmunity, implicating cellular stress originating from the target tissue as a contributing factor. A better understanding of this contribution may help to answer important lingering questions in organ-specific autoimmunity, as to what factors initiate disease and what directs its tissue specificity. Vitiligo, an autoimmune disease of the skin, has been the focus of translational research for over 30 years, and both melanocyte stress and immune mechanisms have been thought to be mutually exclusive explanations for pathogenesis. Chemical-induced vitiligo is a unique clinical presentation that reflects the importance of environmental influences on autoimmunity, provides insight into a new paradigm linking cell stress to the immune response, and serves as a template for other autoimmune diseases. In this review, I will discuss the evidence for cell stress contributions to a number of autoimmune diseases, the questions that remain, and how vitiligo, an underappreciated example of organ-specific autoimmunity, helps to answer them.

Spontaneous Involution of Congenital Melanocytic Nevus With Halo Phenomenon

Congenital melanocytic nevus (CMN) is a neural crest-derived hamartoma, which appear at or soon after birth. CMN has a dynamic course and may show variable changes over time, including spontaneous involution. Spontaneous involution of CMN is a rare phenomenon and is often reported in association with halo phenomenon or vitiligo. The mechanism of halo phenomenon is yet to be investigated but is suggested to be a destruction of melanocytes by immune responses of cytotoxic T cells or IgM autoantibodies. Here, the authors report an interesting case of spontaneously regressed medium-sized CMN with halo phenomenon and without vitiligo, which provides evidence that cytotoxic T cells account for the halo formation and pigmentary regression of CMN.

Identification of tyrosinase inhibitors from traditional Chinese medicines for the management of hyperpigmentation

The inhibition of tyrosinase is the most effective method to decrease melanin synthesis during the process of pigmentation. We aimed to find compounds from traditional Chinese medicines (TCM) that are more effective than the most commonly used tyrosinase inhibitor, arbutin. First, we employed homology modeling to construct a tyrosinase-modeled structure, and structure-based virtual screening to screen from 61,000 TCM compounds. We also adopted the following quantitative structure-activity relationship (QSAR) models for ligand-based validation: support vector machine, multiple linear regression, and Bayesian network. Molecular dynamics (MD) simulation was used to confirm the stability of ligand binding. We found that merresectine C might more effectively bind and inhibit the activity of tyrosinase than arbutin. This study provides useful evidence for the potential development of a novel non-toxic bleaching or whitening ingredient.

Recalcitrant hypocalcaemia in autoimmune enteropathy

Autoimmune polyendocrinopathy candidiasis ectodermal dystrophy syndrome is a monogenic disorder associated with autoimmune destruction of both endocrine and nonendocrine tissues. The classic triad includes candidiasis, hypoparathyroidism, and Addison disease. Up to 25% of patients with autoimmune polyendocrinopathy candidiasis ectodermal dystrophy syndrome also have gastrointestinal manifestations, which can have an impact on the management of other aspects of the disease. The management of the case discussed was challenging because of the complex interplay between the manifestations and treatment of his hypoparathyroidism, Addison disease, and autoimmune enteropathy. Attempts at management of hypocalcemia were largely unsuccessful until the introduction of immunosuppressive therapy for autoimmune enteropathy. This case supports early consideration of immunosuppression in this condition.

Narrow-band UVB irradiation stimulates the migration and functional development of vitiligo-IgG antibodies-treated pigment cells

BACKGROUND

The pathogenesis of vitiligo remains unclear. Most authorities favoured the autoimmune cause for the strong associations of vitiligo with multiple autoimmune diseases and the presence of autoantibodies in vitiligo patients. Narrow-band UVB (NBUVB) irradiation has been considered to be an effective treatment for vitiligo with simple treatment procedure and decreased accumulated ultraviolet exposure doses.

OBJECTIVES

The aim this study was to investigate the effects of NBUVB irradiation on normal IgG antibodies (N-IgG) or vitiligo IgG antibodies (V-IgG)-treated NCCmelan5 cells in terms of proliferation, migration and melanin formation.

METHODS

Cultured NCCmelan5 cells were treated with (i) NBUVB irradiation alone, (ii) N-IgG or V-IgG alone, and (iii) combination of N-IgG or V-IgG with NBUVB irradiation. The proliferation of NCCmelan5 cells were evaluated using BrdU incorporation assay. Western blotting was used to determine the expressions of phosphorylated p125(FAK) (pp125(FAK)) and tyrosinase in NCCmelan5 cells. The locomotion of NCCmelan5 cells was assessed using time-lapse assay and in vitro wound scratch assay.

RESULTS

Neither N-IgG nor V-IgG significantly affected the proliferation of NCCmelan5 cells. The migration, melanin formation and tyrosinase expression in NCCmelan5 cells were decreased by V-IgG. NBUVB irradiation increased the proliferation of V-IgG treated NCCmelan5 cells. In addition, NBUVB irradiation enhanced the mobility of V-IgG-treated NCCmelan5 cells via upregulation of pp125(FAK). The melanogenesis and tyrosinase expression in V-IgG-treated NCCmelan5 cells were promoted using NBUVB irradiation.

CONCLUSIONS

Our study demonstrated that the deleterious effects of V-IgG in the pathogenesis of vitiligo might be overcome by NBUVB irradiation.

Patients affected by vitiligo and autoimmune diseases do not show antibodies interfering with the activity of the melanocortin 1 receptor

BACKGROUND

Vitiligo is an acquired depigmenting disorder characterized by the loss of melanocytes from the epidermis with the development of white patches in various distribution. The pathogenesis of vitiligo is still unknown, but the association with autoimmune disorders and organ specific autoantibodies, supports the hypothesis of an autoimmune pathogenesis.

AIM

The aim of the present study was to investigate if autoantibodies present in sera of patients affected by vitiligo may be able to interfere with the activity of the αMSH on the melanocortin 1 receptor (MC1R). MATERIALS/ SUBJECTS AND METHODS: IgG from the sera of 41 patients with vitiligo associated or not with thyroid autoimmune diseases or other autoimmune pathologies were incubated with HBL20 cells (human malignant melanocytes expressing the MC1R) in the presence of a sub-maximal dose of αMSH. A normal IgG range was determined by using IgG extracted from 30 control sera of normal subjects.

RESULTS

None of the IgG from vitiligo patients was able to inhibit αMSH-stimulated cAMP production in HBL20 cells.

CONCLUSIONS

Autoantibodies against MC1R are rare or absent in sera of vitiligo patients.

The role of T cells in cutaneous autoimmune disease

T cells assume a fundamental function in immunosurveillance and maintenance of the cutaneous immune barrier, yet derangement of their requisite role effects a range of cutaneous autoimmune diseases with significant associated morbidity. While blistering skin diseases, such as pemphigus vulgaris (PV), pemphigus foliaceus (PF) and bullous pemphigoid (BP) are mediated by antibodies directed against autoantigens found in the skin, recent evidence has shown that T cell activation is crucial for the initiation and coordination of this humoral response. Non-blistering skin diseases, such as alopecia areata (AA), vitiligo (VL) and psoriasis (PS) are increasingly believed to be directly mediated by the activities of autoreactive T cells. Here, we examine T lymphocyte control of antibody-mediated and cell-mediated processes involved in the pathoimmunology of the above mentioned skin diseases.

Vitiligo e emoções

FUNDAMENTOS: O vitiligo acomete, em média, 1% da população mundial. Mais de 75% dos pacientes têm autoimagem depreciativa em relação à doença. Seu impacto emocional é muitas vezes negligenciado pelo cuidador, influenciando negativamente o prognóstico. OBJETIVO: Verificar o efeito do vitiligo sobre as emoções e discutir as últimas descobertas sobre a interação mente? corpo e seu desdobramento sobre a doença. MÉTODOS: Cem pacientes com diversas formas de vitiligo responderam, na primeira consulta, a uma pergunta sobre as emoções que a presença das manchas lhes provocava. RESULTADOS: Entre os que apresentavam manchas em áreas expostas, 80% queixaram-se de emoções desagradáveis, em contraposição a 37% dos que tinham manchas em áreas não expostas. As emoções mais referidas foram medo (71%), vergonha (57%), insegurança (55%), tristeza (55%) e inibição (53%). CONCLUSÃO: Qualquer doença crônica produz nos seres humanos uma vivência negativa propiciada pela expectativa de sofrimento. O vitiligo é um desafio à autoestima. Além de uma orientação científica adequada, o paciente de vitiligo carece de conforto emocional. A resposta e a adesão ao tratamento e até mesmo a resiliência diante de eventuais falhas terapêuticas dependem da boa relação médico-paciente. Numa época em que dispomos de respeitável terapêutica, torna-se indispensável que o dermatologista se mostre apto a avaliar seu paciente holisticamente.

Dermatological manifestations of autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy syndrome

BACKGROUND

Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy syndrome (APECED; OMIM 240300) is a rare autosomal recessive disorder defined by a variable combination of endocrine failure, chronic mucocutaneous candidiasis (CMC), and dystrophy of the dental enamel and nails. APECED is caused by mutations in the autoimmune regulator gene (AIRE). Alopecia areata (AA) and vitiligo are diseases with autoimmune pathogeneses, and have been recognized as part of the APECED complex. There are rare reports of other cutaneous manifestations.

OBJECTIVES

We sought to delineate the dermatological features of APECED in an Irish case series with emphasis on timing of their appearance and association with disease severity. Furthermore, we looked for evidence of genotype: phenotype correlation. Finally, we wanted to determine if the ectodermal changes described represent a primary ectodermal dysplasia or whether the ectodermal manifestations are secondary phenomena.

METHODS

Irish patients with APECED were invited to attend a multidisciplinary clinic (Dermatology, Endocrinology, Dentistry and Ophthalmology) held in Our Lady's Hospital for Sick Children, Dublin. Clinical data were compiled from case notes and questionnaires. All patients had a detailed cutaneous examination. Blood samples were obtained for mutational analysis.

RESULTS

Eighteen patients (seven males and 11 females) from 15 families were interviewed and examined. The mean age at diagnosis was 6 years (range 8 months-18 years). All patients had evidence of CMC, 13 (72%) had candidal onychomycosis or paronychia, six (33%) had AA and two had vitiligo. In the case of two patients the diagnosis was made on recognition of dermatological manifestations and confirmed by mutational analysis. Both patients developed Addison's disease on follow-up. CMC was an early feature, often predating diagnosis (10 of 18). AA and vitiligo presented later, and may reflect more severe disease in these cases. There was no correlation between the AIRE mutations identified on mutational analysis and the clinical presentation. We found no evidence of an isolated nail dystrophy or features consistent with a primary ectodermal dysplasia.

CONCLUSIONS

APECED is a rare but complex and potentially life-threatening autoimmune disease. CMC is a common and early feature; diagnosis at this stage may pre-empt life-threatening endocrinological crises. It is important for dermatologists to be aware of this association as they are likely to be the earliest clinicians who encounter these children. AA and vitiligo in our series occurred in the setting of established disease. The term "ectodermal dystrophy" is misleading as the ectodermal features described in our series and in the literature are most likely to be secondary phenomena.

Estudo comparativo entre vitiligo, nevo halo e lúpus eritematoso vitiligóide por meio de métodos imunológicos, histológicos e imuno-histoquímicos

FUNDAMENTOS: O estudo compara o vitiligo, o nevo halo (NH) e lúpus eritematoso vitiligóide (LEV) do ponto de vista imunológico, histológico e histoquímico. OBJETIVOS: Avaliar diferenças imuno-histoquímicas entre essas doenças e investigar se a despigmentação do LEV deve-se à destruição pós-inflamatória ou à agressão imunológica aos melanócitos. MÉTODOS: Foram avaliados 20 pacientes com vitiligo, 17 com vitiligo e NH, cinco com NH isolado e 15 com LEV. Detecção de anticorpos: IF direta e indireta com células névicas e de melanoma. Citotoxicidade: atividade NK contra células de melanoma. Estudo anátomo-histoquímico: exame histológico com hematoxilina e eosina, Fontana-Masson, Dopa e Dopa mais prata (D+P) e exame histoquímico com proteína S-100. RESULTADOS: Doentes com vitiligo, NH e LEV apresentaram anticorpos antimelanócitos. Tanto no vitiligo e NH, como no LEV, demonstrou-se a presença de fatores de risco favorecedores da citotoxicidade celular. A coloração com D+P foi superior às colorações tradicionais e à proteína S-100 na detecção de melanócitos e melanina nas lesões de vitiligo, NH e LEV. CONCLUSÕES: Demonstrou-se a existência de anticorpos antimelanócitos no vitiligo e NH. É possível que a despigmentação no LEV se deva a fenômenos imunológicos semelhantes aos do vitiligo e NH. A detecção de melanócitos nas lesões de vitiligo sugere mais inibição funcional do que destruição dessas células.

CTLA4 polymorphisms are associated with vitiligo, in patients with concomitant autoimmune diseases

The cytotoxic T lymphocyte antigen4 (CTLA4) gene plays a critical role in the control of T cell activation. The gene encodes a surface molecule with inhibitory effects on activated T cells. Several studies have disclosed an association between the previously known variants of the CTLA4 gene and autoimmune disorders, but no study has as yet found any definite association between vitiligo and the CTLA4 polymorphisms. A recent study identified new candidate susceptibility polymorphisms in this region, associated with differential gene splicing and thereby the relative abundance of soluble CTLA4. To assess these new polymorphisms in patients with vitiligo, we genotyped 100 vitiligo patients and 140 healthy controls from the UK, for these novel polymorphisms. No association was found in patients with isolated vitiligo, but a significant association was seen in patients with vitiligo and other autoimmune diseases. The results indicate that the polymorphisms in the CTLA4 gene region confer susceptibility to vitiligo when occurring together with other autoimmune diseases, but not in patients with isolated vitiligo. This raises the possibility that there are two distinct forms of vitiligo where only a subgroup of patients may have a disease caused by the autoimmune destruction of melanocytes.

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.

The effect of antisense tyrosinase-related protein 1 on melanocytes and malignant melanoma cells

BACKGROUND

Tyrosinase-related proteins (TRPs) include tyrosinase, TRP-1 and TRP-2. The functions of tyrosinase and TRP-2 have been determined, but the biological role of TRP-1 is still controversial and is not well known in humans.

OBJECTIVES

To study further the biological role of the human TRP-1 gene in melanocytes and melanoma cells.

METHODS

TRP-1 cDNA was subcloned into eukaryotic expression vector pcDNA3.1 in the reverse direction, and antisense recombinant vector was transfected into melanocytes and a melanoma cell line using Lipofectamine 2000. Positive cells were selected by geneticin. TRP-1 mRNA level was measured by reverse transcription-polymerase chain reaction (RT-PCR), and TRP-1 protein level by Western blot. Cell cycles were determined by flow cytometry, and the activity of tyrosinase was evaluated by L-DOPA reaction. Light microscopy, electron microscopy and flow cytometry were used to observe cell morphology and apoptosis. For in vivo assays, the antitumour activity of antisense TRP-1 against the malignant melanoma (MM) cell line, Libr, was evaluated in an animal-tumour model of subcutaneous tumours.

RESULTS

Positive transfected cells steadily expressed TRP-1 antisense RNA. RT-PCR and Western blot showed a low level of TRP-1 mRNA and TRP-1 protein, respectively. Cell cycles were blocked in the G1 stage, and the activity of tyrosinase decreased significantly (P < 0.01). Light and electron microscopy showed abnormal cell morphology, and apoptosis was detected. The neoplasia activity of antisense TRP-1-transfected MM cells was significantly lower than that of MM cells (P < 0.01).

CONCLUSIONS

TRP-1 plays an important role in the proliferation, morphology and tyrosinase activity of melanocytes and melanoma cells.

A critical appraisal of vitiligo etiologic theories. Is melanocyte loss a melanocytorrhagy?

Common generalized vitiligo is an acquired depigmenting disorder characterized by a chronic and progressive loss of melanocytes from the epidermis and follicular reservoir. However, the mechanism of melanocyte disappearance has never been clearly understood, and the intervention of cellular and humoral autoimmune phenomena as primary events remains unproven. In this review, is discussed the data supporting the major theories of vitiligo, namely melanocyte destruction (autoimmune, neural and impaired redox status) and melanocyte inhibition or defective adhesion. Based on recent morphologic findings in vivo supporting a chronic detachment and transepidermal loss of melanocytes in common generalized vitiligo, a new theory is suggested proposing melanocytorrhagy as the primary defect underlying melanocyte loss, integrating most of the possible triggering/precipitating/enhancing effects of other known factors.

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.

Autoimmune adrenal insufficiency and autoimmune polyendocrine syndromes: autoantibodies, autoantigens, and their applicability in diagnosis and disease prediction

Recent progress in the understanding of autoimmune adrenal disease, including a detailed analysis of a group of patients with Addison's disease (AD), has been reviewed. Criteria for defining an autoimmune disease and the main features of autoimmune AD (history, prevalence, etiology, histopathology, clinical and laboratory findings, cell-mediated andhumoral immunity, autoantigens and their autoepitopes, genetics, animal models, associated autoimmune diseases, pathogenesis, natural history, therapy) have been described. Furthermore, the autoimmune polyglandular syndromes (APS) associated with AD (revised classification, animal models, genetics, natural history) have been discussed. Of Italian patients with primary AD (n = 317), 83% had autoimmune AD. At the onset, all patients with autoimmune AD (100%) had detectable adrenal cortex and/or steroid 21-hydroxylase autoantibodies. In the course of natural history of autoimmune AD, the presence of adrenal cortex and/or steroid 21-hydroxylase autoantibodies identified patients at risk to develop AD. Different risks of progression to clinical AD were found in children and adults, and three stages of subclinical hypoadrenalism have been defined. Normal or atrophic adrenal glands have been demonstrated by imaging in patients with clinical or subclinical AD. Autoimmune AD presented in four forms: as APS type 1 (13% of the patients), APS type 2 (41%), APS type 4 (5%), and isolated AD (41%). There were differences in genetics, age at onset, prevalence of adrenal cortex/21-hydroxylase autoantibodies, and associated autoimmune diseases in these groups. "Incomplete" forms of APS have been identified demonstrating that APS are more prevalent than previously reported. A varied prevalence of hypergonadotropic hypogonadism in patients with AD and value of steroid-producing cells autoantibodies reactive with steroid 17alpha-hydroxylase or P450 side-chain cleavage enzyme as markers of this disease has been discussed. In addition, the prevalence, characteristic autoantigens, and autoantibodies of minor autoimmune diseases associated with AD have been described. Imaging of adrenal glands, genetic tests, and biochemical analysis have been shown to contribute to early and correct diagnosis of primary non-autoimmune AD in the cases of hypoadrenalism with undetectable adrenal autoantibodies. An original flow chart for the diagnosis of AD has been proposed.

The transcription factors SOX9 and SOX10 are vitiligo autoantigens in autoimmune polyendocrine syndrome type I

Vitiligo is common in the hereditary disorder autoimmune polyendocrine syndrome type I (APS I). Patients with APS I are known to have high titer autoantibodies directed against various tissue-specific antigens. Using sera from APS I patients for immunoscreening of a cDNA library from human scalp, we identified the transcription factors SOX9 and SOX10 as novel autoantigens related to this syndrome. Immunoreactivity against SOX9 was found in 14 (15%) and against SOX10 in 20 (22%) of the 91 APS I sera studied. All patients reacting with SOX9 displayed reactivity against SOX10, suggesting shared epitopes. Among the 19 patients with vitiligo, 12 (63%) were positive for SOX10 (p < 0.0001). Furthermore, three of 93 sera from patients with vitiligo unrelated to APS I showed strong reactivity against SOX10, which may indicate a more general role of SOX10 as an autoantigen in vitiligo.

Chronic mucocutaneous candidiasis

Chronic mucocutaneous candidiasis should be viewed as a spectrum of disorders in which the patients have persistent and/or recurrent candidiasis of the skin, nails and mucous membranes. Some of the conditions have genetic predispositions. A common immunologic abnormality is failure of the patient's T lymphocytes to produce cytokines that are essential for expression of cell-mediated immunity to Candida. Antifungal drugs are effective in clearing the infections, and treatments that restore cellular immunity have produced long term remissions.

Detection of antigen-specific cytotoxic T lymphocytes: significance for investigative dermatology

Novel recombinant tetrameric complexes of HLA class I molecules allow the direct visualization of antigen-specific CD8+ T cells using flow cytometry. By facilitating the quantification, isolation and phenotypic analysis of CD8+ T cells, the use of HLA tetramers has extended our understanding of the role of cellular immunity in various disease settings. Recently the technique has also been applied to the study of cutaneous disease and provides insights into mechanisms of dermatopathology.

Antibodies against hair follicles are associated with alopecia totalis in autoimmune polyendocrine syndrome type I

In the autosomal recessively inherited autoimmune polyendocrine syndrome type I (APS I) patients have autoantibodies directed against several endocrine and nonendocrine organs. Alopecia areata is present in about one-third of the patients and usually in the more severe forms, alopecia universalis or totalis. Sera from 39 patients with APS I, diluted 1:150, were used in indirect immunofluorescence staining of cryo-sections from normal human scalp. Two hair follicle staining patterns were observed. A cytoplasmic staining of the differentiating matrix, cuticle, and cortex keratinocytes in the anagen hair follicle was seen in five (13%) APS I sera. All these five patients had alopecia totalis, representing 63% of the eight patients with alopecia totalis (p < 0.0001). Furthermore, four (10%) of the APS I sera stained the nuclei of the melanocytes in the hair follicle. Two of these patients had vitiligo. None of 20 healthy control sera stained the keratinocyte cells or the melanocyte nuclei. These data show that many patients with APS I have high-titer autoantibodies directed against the anagen matrix, cuticle, and cortex keratinocytes and a melanocyte nuclear antigen, and also that the hair follicle keratinocyte staining is associated with alopecia, especially alopecia totalis. This study emphasizes the role of the differentiating anagen keratinocytes as an important structure in the autoimmune etiology of alopecia, both in APS I and at least in a subgroup of patients with alopecia areata unrelated to APS I.

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.

Peripheral T-cell activation in non-segmental vitiligo

Vitiligo is a hypopigmentary dermatosis of probable autoimmune origin. Previously reported aberrations in peripheral blood mononuclear cells (PBMC), especially T cells and T cell subsets, have been inconsistent. Lymphocyte subpopulations were examined using flow cytometry and monoclonal antibodies against CD4, CD8, CD20, CD25, CD45RA, and HLA-DR in 34 patients with non-segmental vitiligo. Twelve patients had not received any previous treatment and 22 had previously received at least one course of PUVA therapy that was discontinued at least four months prior to our study. Compared to matched controls, we found significant increases in CD25 and HLA-DR in vitiligo patients (p = 0.000). An inverse correlation was observed between HLA-DR and patient status with regard to treatment (p = 0.001). These results suggest a role for T cells in the pathogenesis of vitiligo and imply that previous PUVA therapy may be reflected by an alteration in circulating DR +ve cells.

Autoimmune polyglandular syndromes

Autoimmune polyglandular syndrome type 1 (APS1) is characterized by a variable combination of disease components: (1) mucocutaneous candidiasis; (2) autoimmune tissue destruction; (3) ectodermal dystrophy. The disease is caused by mutations in a single gene called APECED (autoimmune polyendocrinopathy-candidiasis-ectodermal-dystrophy) or AIRE (autoimmune regulator) coding for a putative transcription factor featuring two zinc-finger (PHD-finger) motifs. APS1 shows a penetrance of 100%, lack of female preponderance and lack of association with HLA-DR. Typically, onset of APS1 occurs in childhood and multiple autoimmune manifestations evolve throughout lifetime. Organ-specific autoantibodies associated with hypoparathyroidism, adrenal and gonadal failures, IDDM, hepatitis and vitiligo are discussed, and autoantibody patterns in APS1 patients are compared with autoantibodies in APS type 2 (APS2). APS2 is characterized by adult onset adrenal failure associated with IDDM and/or hyperthyroidism. APS2 is believed to be polygenic, characterized by dominant inheritance and association with HLA DR3.

Vitiligo

The destruction of melanocytes is the cause of depigmented maculae that clinically represent the disease vitiligo. Although the cause is unknown, various theories such as the autoimmune, autocytotoxic, and neural hypotheses have been proposed. Extensive research has provided numerous answers regarding the pathogenesis, histopathologic evidence, and treatment of vitiligo. This discussion of vitiligo summarizes the varied clinical presentations of the disease, theories attempting to explain the mechanism of melanocyte destruction, histopathologic findings, and different treatment modalities currently available.

Suplatast tosilate (IPD), a new immunoregulator, is effective in vitiligo treatment

The major type of vitiligo is considered to be an autoimmune disorder. Anti-melanocyte antibodies are frequently detected in sera of patients with this disease. Interleukin (IL)-4 released from Th2 cells is an important factor in stimulating autoantibody production by B-cells. In this study, seven patients with vitiligo treated with suplatast tosilate (IPD), three showed repigmentation and improvement of their lesions after administration of the drug. IPD halted the continuous spread of the lesions in three of the other patients, and, in two of them, also reduced microsome test and thyroid test titers. The efficacy of IPD in treating vitiligo was thought to be due to the suppressive effect of this drug on IL-4 production. No side effect was observed. Thus IPD may represent a new alternative in vitiligo treatment due to its inhibition of autoimmunity by the suppression of IL-4.

The clinical significance of antityrosinase antibodies in melanoma and related hypopigmentary lesions

Antityrosinase antibody is a newly detected antibody in the sera of patients with melanoma or vitiligo. The serum level of the antibody is measured by enzyme-linked immunosorbent assay (ELISA). The autoantigen is tyrosinase itself, the enzyme that participates in pigment (melanin) formation by both melanocytes and melanoma cells Antityrosinase IgG antibodies were found to be present in high titers in sera of patients with vitiligo in comparison to patients with melanoma or healthy volunteers. The level of antityrosinase antibodies in patients with metastatic melanoma was significantly higher than the level in healthy subjects, but insignificantly higher than the level in patients with no evidence of disease. Patients with melanoma and MAH (melanoma-associated hypopigmentation; vitiligo-like) had the same level of antityrosinase antibodies as the controls or the patients with metastatic melanoma. This observation reflected the possible absorption of antityrosinase antibodies by melanoma antigens, and pointed to the participation of the antibodies in the destruction of normal melanocytes in patients with melanoma, as part of the immune reaction towards this disease. The most interesting observation was the high level of antityrosinase antibodies in patients with vitiligo in comparison with the low level in patients with melanoma, patients with MAH, and patients with NED. Although the cutaneous manifestations of vitiligo and MAH are similar and result from destruction of melanocytes by specific antibodies, the two situations are immunologically different. The serum level of free antityrosinase antibodies could not serve as marker for the state of the disease or disease progression or relapse, as no significant difference could be detected between the levels in patients without evidence of disease to those with metastatic melanoma; nor could the levels of antityrosinase antibodies differentiate between the different sites of the primary lesion. However, we have shown that antityrosinase antibodies could be used for monitoring the response to active specific immunotherapy by injection of anti-idiotypic antibodies mimicking the HMW-MAA. In the future, antityrosinase antibodies may be incorporated into immunotherapy for malignant melanoma.

Recent investigations on vitiligo vulgaris

Vitiligo is a depigmenting disorder of the skin caused by destruction of melanocytes. The depigmented skin has several abnormal functions, including some autonomic nervous functions. The inflammatory response in the depigmented skin is muted. Recent genetic and epidemiologic studies indicate that vitiligo affects men and women equally. The prevalence in the population is about one in 200. Vitiligo seems to be transmitted as a polygenic trait. New data suggest that it is not associated with autoimmune endocrine disorders, but more comprehensive studies are required.

Melanoma-associated hypopigmentation: where are the antibodies?

Antibodies to the B16 melanoma cell line and to tyrosinase have been recently defined in our laboratory in sera of patients with vitiligo, melanoma, melanoma-associated hypopigmentation (MAH), and in healthy subjects. The antibody titers in each subject were measured by enzyme-linked immunosorbent assay, were compared with the mean optical density (OD) of the control group, and were expressed as relative OD. The titers of anti-B16 antibodies (relative OD +/- standard error) were 1.000 (0.058) in the controls, 1.025 (0.077) in patients with metastatic melanoma, 0.5862 (0.15) in MAH, 1.377 in surgery-induced MAH, 1.087 in vaccination with anti-idiotypic antibodies, and 2.098 (0.15) in autoimmune vitiligo. The titers in vitiligo were significantly higher (p < 0.0001) than in MAH or in healthy controls. Antityrosinase antibodies were found in titers of 1.000 (0.1024) in the controls, 1.516 (0.225) in metastatic melanoma, 1.027 (0.180) in MAH, 1.075 in surgery-induced MAH, 2.308 in vaccination-induced MAH, and 4.536 in vitiligo. Differences were found between vitiligo and MAH (p = 0.008), surgery-induced MAH (p = 0.009), vaccination-induced MAH (p = 0.059), and healthy subjects (p < 0.0001). The results of this study point to the cross-antigenicity between melanocytes and melanoma cells, and to participation of antibodies against melanoma-associated membrane antigens in the mechanism leading to the development of MAH in patients with melanoma.

The nature of autoantigens targeted in autoimmune endocrine diseases

Autoimmune endocrine diseases result from autoimmune processes involving autoreactive T cells and/or autoantibodies. Considerable progress has been made in elucidating the self- (auto-) antigens involved in these processes. These include tissue-specific membrane receptors, enzymes and secreted hormones. As discussed here by Yao-Hua Song and colleagues, diagnostic and therapeutic applications should now result from these discoveries.

Organ-specific autoantibodies in vitiligo patients and their relatives

BACKGROUND

Recent data have supported an autoimmune etiology of vitiligo. Genetic factors also seem to play an important role in this disorder. The purpose of this study was to determine the presence and frequency of organ-specific autoantibodies in vitiligo patients and their relatives.

METHODS

Twenty patients with vitiligo and two first or second degree relatives of each patient were interviewed and their sera analyzed for the presence of antithyroglobulin (ATg), antithyroid microsomal (ATM), antiparietal cell (APC), and antiadrenal (AAd) autoantibodies. The sera of 20 normal patients were used as control.

RESULTS

A significantly increased frequency of ATg, ATM, and APC antibodies was found in vitiligo patients when compared to normal controls. First and second degree relatives had significantly increased frequencies of ATg and ATM. A high incidence of autoimmune/endocrine diseases was found in the patients' relatives, including a 25% prevalence of vitiligo.

CONCLUSIONS

These findings not only support an autoimmune etiology for vitiligo, but also highlight the strong genetic contribution to this pigmentary disorder.

Hydroalcoholic human placental extract: skin pigmenting activity and gross chemical composition

BACKGROUND

Vitiligo is a pigmentary disorder of the skin of unknown etiology. It is thought to be of autoimmune origin after demonstration of antibody-mediated destruction of melanocytes. Photochemotherapeutic PUVA therapy is widely used in vitiligo with about 33% success. Aqueous or hydroalcoholic extracts of human placenta of ill-defined composition have also been used therapeutically for vitiligo. A hydroalcoholic human placental extract has been developed by us with pigmenting activity based on experimental therapies. Its chemical analysis was the primary objective of this study.

METHODS

For the guinea pig experiment, 20 drops of the extract or vehicle (60% alcohol) as control was topically applied around the nipples covering the areola zones of male immature white guinea pigs (wt. 175-250 g) daily for 60 days with 15 minutes infrared (IR) exposure used for vascular dilatation and enhancement of the absorption of the extract. Standard methods have been followed for all chemical analyses.

RESULTS

The guinea pig experiment showed clear pigmentation and hypertrophy of the experimental nipples to varying degrees. Chemical analysis of the extract revealed the presence of small-molecular-weight proteins/peptides, lipids (including glycosphingolipids), carbohydrates, sialic acids, cholesterol, triglycerides, high density lipoproteins (HDL), and others, including amino acids, nucleotides, carotenes, vitamins, etc.

CONCLUSION

Glycosphingolipids, known modulators of B and T cells, were reported capable of inducing adhesion, spreading, and motility of melanoma. It is present in the extract and, therefore, may lead to skin pigmentation through induction of melanocytes. Endothelin, a 21-amino acid peptide, detected in human placenta and possibly extractable by our process, has been reported to be indispensable for melanocyte growth.

HLA antigens in Omani patients with vitiligo

Fifty native Omanis with vitiligo were studied to compare the incidence of HLA ABC and DR antigens with a control population. HLA Bw6 was found in 82% of patients compared with 49% controls (Pc = 0.0009 RR = 4.56) and HLA DR7 occurred in 40% of patients and 9% in controls (Pc = 0.00075 RR = 6.17). HLA DR7 was significantly increased in those patients with acrofacial, compared to focal disease (57% vs. 24% P = 0.038). Sixty-six per cent of the patients in this study had parents who were consanguineous and a positive family history was only found in this group with an incidence of 32%. HLA Bw4 segregated 100% with patients with a positive family history compared with 48% in consanguineous patients without a positive family history (Pc = 0.011 RR = 23). Vitiligo appears to be associated with different HLA antigens in different ethnic groups.