Further evidence for involvement of both cell mediated and humoral immunity in generalized vitiligo

Histopathological differences between vitiligo and lichen sclerosus et atrophicus using quantitative immunohistochemical analysis

Introduction

Lichen sclerosus et atrophicus (LS) is rare skin condition characterized by the presence of whitish patches primarily affecting the genital and perianal areas, though it can occur other parts of the body. LS may result in skin depigmentation without textural changes and should be differentiated from vitiligo. However, the histopathological features of hypopigmentation during vitiligo and LS have rarely been compared and have not been precisely described using quantitative immunohistochemical analysis. This study, therefore, aimed to investigate and compare the pigmentary characteristics of LS and vitiligo lesions using histochemical and immunohistochemical staining.

Methods

We included 31 and 46 patients diagnosed with LS and vitiligo, respectively, at Ajou University Hospital between March 2009 and March 2020 in this study. Their medical charts and skin biopsy specimens were retrospectively reviewed. Additionally, Fontana-Masson staining for melanin and immunohistochemical staining for Melan-A, NKI/beteb, tyrosinase, and microphthalmia-associated transcription factor was performed.

Results

The melanin content, as well as the number of melanocytes was, in general, significantly higher in the epidermis of patients in the LS group compared with that in the vitiligo group. However, 22.6% of LS tissues showed less melanin pigmentation, 25.8% of LS specimens exhibited a lower number of melanocytes, and 29.0% of LS specimens demonstrated less melanocyte activity when compared with the average of vitiligo specimens.

Conclusion

As lower melanin pigmentation and the near absence number of melanocytes were also observed in several LS specimens, both the clinical and histological findings must be comprehensively reviewed to differentiate vitiligo from LS.

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.

The role of interleukins in vitiligo: a systematic review

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

Vitiligo in Children: A Review of Conventional Treatments

Vitiligo is an important skin disease of childhood, which may lead to deep psychological trauma, resulting in a poor quality of life and low self-esteem. The Authors discuss a short review of the more conventional therapies available for the treatment of vitiligo in children.

Systemic Steroids Suppress Antimelanocyte Antibodies in Vitiligo

Background:

Vitiligo is associated with autoantibodies to melanocytes. The role of these antibodies in the pathogenesis of the disease is still unknown.

Objective:

The purpose of this study was to examine the role of vitiligo antibodies in the pathogenesis of the disease by studying whether or not there is a correlation between changes in their level and response to therapy with systemic steroid.

Methods:

Antibodies to the 40 to 45 kD, 75 kD, and 90 kD vitiligo antigens were measured prior to and following systemic steroid therapy in 10 patients with active vitiligo.

Results:

Four months following initiation of therapy, seven (78%) of nine patients with good clinical response to steroid treatment had a significant decrease in the level of vitiligo antibodies. By contrast, one patient who had no response to treatment had a slight increase in antibody levels.

Conclusion:

These findings suggest that one mechanism by which corticosteroids can cause repigmentation in vitiligo is by decreasing the level of vitiligo antibodies, and support the notion that vitiligo antibodies are involved in the pathogenesis of this disease.

Aspirin in dermatology: Revisited

Aspirin has been one of the oldest drugs in the field of medicine, with a wide range of applications. In dermatology, aspirin has shown benefit in a variety of disorders. Recently, reduction of melanoma risk with aspirin has been demonstrated. Although an analgesic to begin with, aspirin has come a long way; after cardiology, it is now found to be useful even in dermatology.

Relationship between Helicobacter pylori infection and vitiligo: a prospective study

BACKGROUND

Helicobacter pylori is a worldwide bacteria that may affect several extra-gastric systems, including the endocrine, hematologic, vascular, respiratory, immune, and skin. Several skin diseases, including chronic urticaria, alopecia areata, psoriasis, and systemic lupus erythematosis have been found to be associated with H. pylori infection.

AIM

To our knowledge, there are no data showing an association between H. pylori and vitiligo. Therefore, in this study, we wanted to evaluate the relationship between H. pylori and vitiligo.

METHODS

This study is a prospective study carried out in our Gastroenterology and Dermatology and Venereology departments of the Ankara Education and Research Hospital (Ankara, Turkey) between July 2013 and December 2013. Seventy-nine consecutive patients with vitiligo and 72 patients with telogen effluvium (TE) were recruited from the dermatology outpatient clinic. A total of 133 patients with vitiligo (n=68) and TE (n=65) [excluding 18 patients who had suspicious urea breath test (UBT) results] were included in the study. All individuals were tested for H. pylori IgG and CagA. Also, a UBT was performed to detect the presence of H. pylori infection.

RESULTS

There were significantly higher rates of H. pylori positivity, H. pylori CagA, and IgG in serum in the vitiligo group than in the TE group (p<0.05). The number of patients with dyspepsia was significantly higher in the vitiligo group than in the TE group. No statistically significant relationship was seen between H. pylori positivity, CagA, H. pylori IgG, dyspepsia, and the Vitiligo Disease Activity score (p>0.05). Also, when patients with vitiligo were divided into localized and generalized types of vitiligo, there was no association between vitiligo involvement pattern and H. pylori positivity, CagA, H. pylori IgG, and dyspepsia (p>0.05).

CONCLUSION

Additional studies are necessary to evaluate the effect of H. pylori eradication on the clinical course of vitiligo. Further studies are also needed to explain the relationship between H. pylori and the pathogenesis of vitiligo.

Vitiligo: interplay between oxidative stress and immune system

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

Autoimmunity associated with immunotherapy of cancer

In this age of promise of new therapies for cancer, immunotherapy is emerging as an exciting treatment option for patients. Vaccines and cytokines are being tested extensively in clinical trials, and strategies using monoclonal antibodies and cell transfer are mediating dramatic regression of tumors in patients with certain malignancies. However, although initially advocated as being more specific for cancer and having fewer side effects than conventional therapies, it is becoming increasingly clear that many immunotherapies can lead to immune reactions against normal tissues. Immunotoxicities resulting from treatment can range from relatively minor conditions, such as skin depigmentation, to severe toxicities against crucial organ systems, such as liver, bowel, and lung. Treatment-related toxicity has correlated with better responses in some cases, and it is probable that serious adverse events from immune-mediated reactions will increase in frequency and severity as immunotherapeutic approaches become more effective. This review introduces immunotherapeutic approaches to cancer treatment, provides details of toxicities arising from therapy, and discusses future potential ways to avoid or circumvent these side effects.

Vitiligo, reactive oxygen species and T-cells

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

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.

Mechanisms of spatial and temporal development of autoimmune vitiligo in tyrosinase-specific TCR transgenic mice

Generalized vitiligo is thought to have an autoimmune etiology and has been correlated with the presence of CD8 T cells specific for melanocyte differentiation Ag. However, limited animal models for the disease have hampered its understanding. Thus, we generated TCR transgenic mice that recognize an epitope of the melanocyte protein, tyrosinase. These animals develop vitiligo with strikingly similar characteristics to the human disease. Vitiligo develops temporally and spatially, with juvenile lesions forming bilaterally in head and facial areas, and only arising later in the body of adult animals. Vitiligo is entirely dependent on CD8 T cells, whereas CD4 T cells exert a negative regulatory effect. Importantly, CD8 T cells can be pervasively present in the skin in the steady state without inducing vitiligo in most areas. This points to developmental differences in melanocyte susceptibility and/or immunological effector mechanisms over time, or in different body locations. Disease is strongly dependent on both IFN-gamma and CXCR3, whereas dependence on CCR5 is more limited, and both CCR4 and perforin are dispensable. Genetic ablation of CXCR3 or IFN-gamma also resulted in scarce CD8 T cell infiltration into the skin. Our results identify unexpected complexity in vitiligo development and point toward possible therapeutic interventions.

Autoimmunity as an aetiological factor in vitiligo

Vitiligo is a common dermatological disorder characterized by the presence on the skin of depigmented macules resulting from the destruction of cutaneous melanocytes. Autoimmunity is an important hypothesis with regard to vitiligo aetiology and the evidence for autoimmune responses being involved in the pathogenesis of this disorder will be discussed in the present review. All immune system compartments, including innate and adaptive immunity have been implicated in vitiligo development. Particularly relevant are autoantibodies and autoreactive T cells in vitiligo patients that have cytotoxic effects upon pigment cells. Furthermore, predisposition to vitiligo appears to be associated with certain alleles of the major histocompatibility complex class II antigens as well as with other autoimmune-susceptibility genes. Moreover, the association of vitiligo with autoimmune disorders, the animal models of the disease, and the positive response to immunosuppressive therapeutic agents emphasize the role of autoimmunity in the development of this disorder.

Basic research confirms coexistence of acquired Blaschkolinear Vitiligo and acrofacial Vitiligo

We report about a female patient with bilateral and unilateral blaschkolinear depigmentation on the extremities and coexistence of acrofacial vitiligo, who initially presented her first signs of depigmentation at the age of 32 years. The patient was otherwise healthy. The correct diagnosis was based on the latest up to date technology utilizing in vivo FT-Raman and Fluorescence spectroscopy, Wood's light examination of the depigmented skin and immunoreactivity of epidermal catalase expression in 3 mm punch biopsies from the linear depigmented area. The results yielded decreased catalase protein expression compared to healthy controls as well as complete absence of melanocytes. FT-Raman spectroscopy identified the presence of hydrogen peroxide (H(2)O(2)) in the mM range and Fluorescence spectroscopy demonstrated H(2)O(2)-mediated oxidation of tryptophan residues in the depigmented area. The results were in agreement with vitiligo. Repigmentation of the linear lesion was initiated after reduction/removal of epidermal H(2)O(2) with pseudocatalase PC-KUS further supporting the correct diagnosis. To the best of our knowledge this is the first case documented with vitiligo following Blaschko lines in coexistence with classical acrofacial vitiligo. This observation raises the question whether besides H(2)O(2)-mediated stress in association with genomic mosaicism could play a role in some cases with vitiligo.

Assessment of the immune system in 55 Iranian patients with vitiligo

BACKGROUND

Vitiligo is an acquired idiopathic hypomelanotic disorder characterized by circumscribed depigmented macules resulting from the loss of cutaneous melanocytes.

OBJECTIVE

In order to evaluate the immune system of Iranian patients with vitiligo, this study was accomplished.

METHODS

Fifty-five Iranian patients with vitiligo and 60 healthy persons as control were investigated in this study. The laboratory techniques were included: antimelanocyte antibody (AMA) and antinuclear antibody (ANA) with indirect immunoflorescent test, C3 and C4 levels with single radial immunodiffusion (SRID), and rheumatoid factor (RF) with enzyme-linked immunosorbent assay (ELISA).

RESULTS

AMA was positive in 17 patients (30.9%) and was negative in the entire control group (P < 0.0001). ANA was positive in 4 patients (7.3%), which was insignificantly higher than control group (1.7%). IgM-RF was positive in 6 patients (10.8%) while it was negative in the entire control group (P = 0.027). C3 and C4 values decreased in 14 patients (25.5%), which was significantly higher than control group (P < 0.001).

CONCLUSION

The important role of the immune system in the pathogenesis of vitiligo could be suggested. In addition, the autoimmune hypothesis of vitiligo could be confirmed based on the results of this study.

Transfer of efficient anti-melanocyte T cells from vitiligo donors to melanoma patients as a novel immunotherapeutical strategy

BACKGROUND

Vitiligo is a relatively common progressive depigmentary condition that is believed to be due to the autoimmune-mediated loss of epidermal melanocytes. High frequencies of self-reactive T lymphocytes directed toward melanocyte differentiation antigens are found in vitiligo patients and might be directly responsible for the pathogenesis of the disease. An interesting aspect of vitiligo is its relation to melanoma: cytotoxic T lymphocytes directed to self antigens shared by normal melanocytes and melanoma cells are found in both conditions, but the resulting immune reactions are completely different. From this standpoint, the selective destruction of pigment cells that occurs in cases of vitiligo is the therapeutic goal sought in melanoma research.

PRESENTATION OF THE HYPOTHESIS

Our working hypothesis is that vitiligo patients might represent a unique source of therapeutic cells to be used in allo-transfer for HLA-matched melanoma patients. The adoptive transfer of ex-vivo generated autologous tumor-specific T cells is a therapy that has met with only limited success, essentially because of inability to isolate therapeutically valuable T cells from the majority of tumor patients. Ideally, model systems where strong and efficient responses against the same (tumor) antigens are achieved would represent a better source of therapeutic cells. We believe it is possible to identify one such model in the melanoma-vitiligo dichotomy: T lymphocytes specific for different melanocyte differentiation antigens are found in vitiligo and represent the effective anti-melanocyte reactivity that is often ineffective in melanoma.

TESTING THE HYPOTHESIS

Melanocyte-specific T cell clones can be isolated from the peripheral blood of vitiligo patients and tested for their capacity to efficiently expand in vitro without loosing their cytotoxic activity and to migrate to the skin. Cytotoxicity against melanoma patients' non-tumor cells can also be tested. In addition, it would be interesting to attempt an in vivo animal model. If the results obtained from these validation steps will be satisfactory, it might be possible to plan the clinical grade preparation of relevant clones for transfer.

IMPLICATIONS OF THE HYPOTHESIS

When translated into a clinical trial, the possibility of in vitro selecting few effective tumor-specific T cell clones for infusion, inherent with this approach, could enhance the therapeutic graft-versus-tumor effect while possibly decreasing the risk of graft-versus-host disease.

Melanocyte-specific, cytotoxic T cell responses in vitiligo: the effective variant of melanoma immunity?

Vitiligo is a relatively common progressive depigmentary condition that is believed to be due to the autoimmune-mediated loss of epidermal melanocytes. An interesting aspect of vitiligo is its relation to melanoma: cytotoxic T lymphocytes directed to self-antigens shared by normal melanocytes and melanoma cells are found in both conditions and might prove important in melanocyte destruction, yet the resulting immune reactions are completely different. From this standpoint, the selective destruction of pigment cells that occurs in cases of vitiligo is the therapeutic goal sought in melanoma research. In the present article, we will address these issues by reviewing current literature on the subject as well as by posing some speculations.

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.

Genes of the LMP/TAP cluster are associated with the human autoimmune disease vitiligo

Genes within the class II region of the major histocompatibility complex (MHC), including genes involved in antigen processing and presentation, have been reported to be associated with several autoimmune diseases. We report here that the LMP/TAP gene region is significantly associated with vitiligo, a disorder in which biochemical defects and/or autoimmune destruction cause melanocyte loss and resulting skin depigmentation. Case/control analyses revealed genetic association of vitiligo in Caucasian patients with an early age of onset with the transporter associated with antigen processing-1 (TAP1) gene. A family-based association method revealed biased transmission of specific alleles from heterozygous parents to affected offspring for the TAP1 gene, as well as for the closely linked LMP2 and LMP7 genes encoding subunits of the immunoproteasome. No association with vitiligo was found for the MECL1 gene, which encodes a third immunoproteasome subunit and is unlinked to the MHC class II region. These results suggest a possible role for the MHC class I antigen processing and/or presentation pathway in the antimelanocyte autoimmune response involved in vitiligo pathogenesis.

Vitiligo

O vitiligo é doença de pele de causa desconhecida que acomete cerca de 1% da população, comprometendo de modo semelhante homens e mulheres, preferencialmente entre 10 e 30 anos de idade. Alguns fatores precipitantes para essa doença são: estresse físico e emocional, traumas mecânicos e substâncias químicas, como derivados do fenol. Doenças auto-imunes, principalmente as tireoidianas, podem estar associadas ao vitiligo. Novas terapias têm sido propostas, como o uso de imunomoduladores tópicos, aliadas àquelas já consolidadas, como os psoralenos e os corticosteróides; o sucesso terapêutico, entretanto, está estritamente relacionado à qualidade da relação médico/paciente.

Participation of the intestinal epithelium and mast cells in local mucosal immune responses in commercial poultry

The intestinal mucosa of commercial poultry is continually subjected to invasion or colonization by a wide array of potentially hostile enteric pathogens. Although, recent investigations have focused on lymphocyte involvement in immune responses in the intestine, lymphocyte-mediated immunity alone will not explain the barrier nature of mucosal membranes associated with rejection of many enteric pathogens upon secondary homologous challenge. Our laboratories have focused on nontraditional elements of mucosal immunity in poultry to better understand host-pathogen interactions in the intestine. Following classical and novel immunization procedures, we have identified an antigen-specific mechanism of immediate responsiveness of the mucosal epithelium characterized by epithelial chloride secretion. This mechanism, characteristic of intestinal anaphylaxis, is mediated by local immune elements. Similar mechanisms in mammals contribute to the barrier nature of mucosal membranes during pathogen challenge. To identify cells participating in these and similar responses, additional studies have described a role for mast cells in acute phase responses in the intestines of chickens experimentally challenged with Eimeria. To a more practical end, other experiments in our laboratories have characterized drinking water administration of BSA for elicitation of local and systemic antibody responses. These experiments have shown ad libitum drinking water administration of BSA to be as effective as i.p. administration of BSA; they present a novel approach to immunization of commercial poultry with protein vaccines. These investigations support continued research on host-pathogen interactions within the intestine of commercial poultry to better understand and control enteric pathogens through vaccination or immunomodulation.

Apoptosis in feathers of Smyth line chickens with autoimmune vitiligo

Vitiligo is an acquired dermatological disorder characterized by a loss of epidermal melanocytes resulting in depigmentation of the skin. Mechanisms underlying the destruction of melanocytes in vitiligo remain unclear. An animal model to study spontaneously occurring autoimmune vitiligo is the mutant Smyth line (SL) of chickens. This investigation was designed to determine whether the pathogenesis of depigmentation in Smyth line chicken vitiligo (SLV) involves an apoptotic mechanism. Terminal deoxynucleotide transferase-mediated fluorescein-dUTP nick end labeling (TUNEL) was used to detect in situ cell apoptosis in cryostat sections of 2-week-old regenerating feathers. Two-week-old regenerating feathers were obtained from SL chickens and their normally pigmented controls including the parental Brown line (BL) and Light Brown Leghorn (LBL) chickens at 6, 8, 10 and 12 weeks of age. In feathers from vitiliginous SL chickens, the number of TUNEL+ cells was significantly (P<or=0.05) higher than that in the feathers of non-vitiliginous SL, BL or LBL chickens. These TUNEL+ cells were primarily located in the epithelial barb ridge where melanocyte cell bodies are located. The extent of this apoptosis in the feathers of SLV chickens varied with the severity of depigmentation of the feathers (i.e., highest in active depigmentation), suggesting a close association between apoptosis and the disappearance of melanocytes. In addition to TUNEL staining, most sections were double-stained with monoclonal antibodies specific to either CD8 or MHC class II molecules to further explore the relationship between CD8+ feather-infiltrating lymphocytes and this increase in apoptotic cells. Compared to normally pigmented controls, the number of CD8+ and MHC class II+ cells in the feather pulp and the barb ridge increased 2-4 weeks before the visible onset of SLV, and was directly related to the changes in the number of TUNEL+ cells prior to, at onset and during depigmentation. Moreover, some of these infiltrating CD8+ cells were localized next to or near the TUNEL+ cells. These observations suggest that enhanced apoptosis in the feather of SLV chickens is a pathogenic mechanism involved in the death of melanocytes and appears to be induced by infiltrating cytotoxic T lymphocytes (CD8+).

Epidemiology of vitiligo and associated autoimmune diseases in Caucasian probands and their families

Generalized vitiligo is an autoimmune disorder characterized by acquired white patches of skin and overlying hair, the result of loss of melanocytes from involved areas. The most common disorder of pigmentation, vitiligo occurs with a frequency of 0.1-2.0% in various populations. Family clustering of cases is not uncommon, in a non-Mendelian pattern suggestive of multifactorial, polygenic inheritance. We surveyed 2624 vitiligo probands from North America and the UK regarding clinical characteristics, familial involvement, and association with other autoimmune disorders, the largest such survey ever performed. More than 83% of probands were Caucasians, and the frequency of vitiligo appeared approximately equal in males and females. The frequency of vitiligo in probands' siblings was 6.1%, about 18 times the population frequency, suggesting a major genetic component in disease pathogenesis. Nevertheless, the concordance of vitiligo in monozygotic twins was only 23%, indicating that a non-genetic component also plays an important role. Probands with earlier disease onset tended to have more relatives affected with vitiligo, suggesting a greater genetic component in early onset families. The frequencies of six autoimmune disorders were significantly elevated in vitiligo probands and their first-degree relatives: vitiligo itself, autoimmune thyroid disease (particularly hypothyroidism), pernicious anaemia, Addison's disease, systemic lupus erythematosus, and probably inflammatory bowel disease. These associations indicate that vitiligo shares common genetic aetiologic links with these other autoimmune disorders. These results suggest that genomic analysis of families with generalized vitiligo and this specific constellation of associated autoimmune disorders will be important to identify the mechanisms of genetic susceptibility to autoimmunity.

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.

Vitiligo: a manifestation of apoptosis?

Vitiligo is a common cutaneous disorder that has significant biological and social consequences for those affected. It is characterized by a loss of melanocytes from the epidermis, which results in the absence of melanin, i.e. depigmentation. There are numerous hypotheses about the etiology of vitiligo, but no data to definitively prove one theory over another. It is likely that there are numerous causes for the loss of these melanocytes. One way to approach the identification of the etiology is to determine the mechanism by which the melanocytes are destroyed. The two known mechanisms for the destruction of cells are necrosis and apoptosis. One purpose of this paper is to review the extant data that might suggest which of the two mechanisms is operative against melanocytes in patients with vitiligo. The histological data, and some laboratory data, support apoptosis, rather than necrosis, as the mechanism for removal of melanocytes. Apoptosis can be induced by a variety of factors, including immune cytokines, some environmental chemicals (for example substituted hydroquinones such as monobenzone) or other molecular mechanisms. Current therapies, such as corticosteroids and ultraviolet light, do affect apoptosis in a variety of ways. Confirmation of apoptosis as a mechanism, and identification of how apoptosis is initiated to produce vitiligo, can serve as a basis for devising medications that might stop the progression of the disorder. The problem of vitiligo would be essentially solved if there was a medication that is well tolerated in children, adults and pregnant women, and that would halt the progression of the depigmentation. The study of apoptosis, mechanisms of its induction, and the ways to block apoptosis, is one possible way to find both the causes of depigmentation and medications to prevent its progression.

Autoimmune aspects of vitiligo

Vitiligo is a depigmenting disorder characterised by the loss of melanocytes from the cutaneous epidermis. Although the exact cause of the condition remains to be established, an autoimmune aetiology has been suggested and several observations support this theory. These will be the topic of discussion in this review. In brief, the disease is frequently associated with other disorders which have an autoimmune origin such as autoimmune thyroiditis and insulin-dependent diabetes mellitus. Furthermore, circulating antibodies and T lymphocytes which react against melanocyte antigens are present in the sera of a significant proportion of vitiligo patients compared with healthy individuals. Immunosuppressive therapies which are reasonably effective in treating the condition, well-studied animal models of the disease as well as the association of vitiligo with MHC antigens, all add credence to the hypothesis that immune mechanisms play a role in the development of vitiligo.

Levels of neuropeptide-Y in the plasma and skin tissue fluids of patients with vitiligo

In order to study the possible role of neuropeptide-Y (NPY) in the pathogenesis of vitiligo, the authors measured the levels of NPY in the plasma from 47 patients with vitiligo compared with 25 healthy volunteers, and the tissue fluids of skin lesions and uninvolved skin from 32 patients, employing a NPY 125I RIA Kit. The results showed that the levels of NPY in the patients with vitiligo of all of the generalized, local and segmental types were significantly higher than the normal controls. In both local and segmental type, the levels in progressive stage were significantly higher than those in stable stage, while in generalized type, there was no significant difference between those in progressive stage and stable stage. The levels of NPY in the tissue fluids from skin lesions were significantly higher than those from uninvolved skin in both the local type and segmental type, while in the generalized type, there was no significant difference between the NPY level in the tissue fluid from skin lesion and that from uninvolved skin. It is speculated that NPY may play certain roles in the pathogenesis of vitiligo, via neuro-immunity mechanism or neuronal affection on the melanocytes.

Local immune response in skin of generalized vitiligo patients. Destruction of melanocytes is associated with the prominent presence of CLA+ T cells at the perilesional site

In situ immune infiltrates in lesional, perilesional, and nonlesional skin biopsies from patients with vitiligo were analyzed by immunohistochemistry and compared with immune infiltrates found in the skin of normal healthy donors and relevant disease controls. An increased influx of activated skin-homing T cells and macrophages were seen in the perilesional biopsies. The overall percentages of cutaneous leukocyte-associated antigen-positive (CLA+) T cells were similar to those found in normal healthy donors. This is compatible with the similar expression of E-selectin. Most strikingly, however, the CLA+ T cells in perilesional skin were mainly clustered in the vicinity of disappearing melanocytes, and 60% to 66% of these interacting T cells expressed perforin and granzyme-B. The perforin+/granzyme-B+ cells were not seen in locations different from that of disappearing melanocytes. Interestingly, the majority of the infiltrating T cells were HLA-DR/CD8+. Another hallmark of the present study is the focal expression of intercellular adhesion molecule (ICAM)-1 and HLA-DR in the epidermis at the site of interaction between the immune infiltrates and the disappearing melanocytes. The data presented in this study are consistent with a major role for skin-homing T cells in the death of melanocytes seen in vitiligo.

In vivo delayed-type hypersensitivity in 109 patients with vitiligo

BACKGROUND

Although the etiology of the depigmentation disorder vitiligo is still not completely understood, many investigators believe that an autoimmune reaction may play a major role. In this regard, T-lymphocyte-mediated immunity has been implicated frequently in the pathogenesis of the disease. Most studies have applied in vitro testing of cell-mediated immunity, however, rather than in vivo measurements. Therefore, our study was undertaken to define the cutaneous delayed-type hypersensitivity (DTH) in vivo reaction in association with the absence/presence of serum thyroid autoantibodies, which are a good representative marker for autoimmunity in patients with vitiligo.

METHODS

DTH was evaluated in the normal pigmented skin of 109 vitiligo patients (29 men and 80 women) and in the depigmented skin of 27 of this group (5 men and 22 women) using the dermal application of seven common recall antigens together with a negative control. Individuals were considered to be hypoergic if the DTH sum score was </= 5 mm in women or </= 10 mm in men, or if they responded to only one or two antigens.

RESULTS

The mean sum score was 10.2 +/- 8.4 with an average of 2.3 +/- 1.6 positive reactions in depigmented skin vs. a sum score of 12.4 +/- 9. 0 with an average number of 2.6 +/- 1.6 positive reactions in normal pigmented skin. There was no statistically significant difference between depigmented and normal pigmented skin using the paired t-test (P > 0.05). Further evaluation of these data showed no significant correlation between the presence of thyroid autoantibodies as well as selected clinical parameters and an aberration in cutaneous DTH.

CONCLUSIONS

In contrast to earlier reports, our in vivo studies of cutaneous DTH reactions revealed no clinically significant aberrant cellular immunity in this patient group. These results indicate that the immune reaction in vitiligo may be only a secondary event in the pathogenesis of the disease.

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.

Vitiligo. Therapeutic advances

Vitiligo often induces severe cosmetic disfigurement in patients. Both nonsurgical (medical) and surgical approaches for repigmenting vitiliginous macules are described (Table 1). Currently PUVA therapy appears to be the best method in providing reasonable hope for achieving repigmentation. Guidelines for both topical and systemic PUVA are available. Furthermore, surgical graft of autologous epidermal sheet or cultured melanocytes (often combined with keratinocyte co-culture) can be introduced to repigment the depigmented areas where PUVA is ineffective. PUVA therapy after autologous skin graft can enhance the repigmenting efficiency. Although PUVA with or without surgical procedure represents a useful tool in vitiligo treatment, we should look for other new treatment modalities based upon better understanding of basic biology of melanin pigmentation and pathophysiology of this disease. A recent development of topical pseudocatalase and calcium application combined with UVB phototherapy may be one of the typical examples in this respect. Many patients are significantly affected psychologically by the disease. Physicians should attempt to assess the degree of psychological impairment caused by vitiligo. Supportive care should always be offered if necessary in order to minimize these problems appropriately. In closing, normal skin of vitiligo patients can be totally depigmented by monobenzyl ether of hydroquinone in order to match the skin color in certain generalized vitiligo patients. There is a recent case report of extensive vitiligo with rapid repigmentation of depigmenting vitiliginous skin within a few weeks after discontinuing successful depigmentation therapy by monobenzyl ether of hydroquinone.

Relationship between levels of soluble interleukin-2 receptors and the types and activity of vitiligo

Levels of serum-soluble interleukin-2 receptors (serum sIL-2R) are thought to indicate the activation of immunocompetent cells, mainly lymphocytes. Elevated levels of serum sIL-2R have been observed in various infectious and autoimmune diseases and also after organ transplantation. It has been hypothesized that autoimmune mechanisms are involved in the pathogenesis of vitiligo. Therefore, we studied serum sIL-2R levels in relation to disease types and activity of vitiligo. We used sera separated from venous blood samples from 12 patients with dermatomally distributed type B vitiligo, 17 patients with non-dermatomally distributed type A vitiligo during the active stage, 9 patients with type A vitiligo during the inactive stage, and 12 normal control subjects. Serum sIL-2R levels were similar in type B vitiligo patients and the controls but were significantly elevated in patients with active type A vitiligo compared with controls and inactive type A vitiligo patients. It is suggested that the immune system is activated in patients with type A vitiligo during the active stage and that autoimmune mechanisms may play a role only in type A vitiligo.

Vitiligo

Vitiligo involves a progressive loss of melanocytes from the epidermis and hair follicles. Milky-white patches appear resulting in cosmetic disfiguration that is most apparent in dark-skinned individuals. The disease is further classified according to distribution pattern and extent of depigmentation. The presence of several clinical subtypes may reflect the diversity in causative factors. To select appropriate therapeutic measures it is important to distinguish vitiligo from other disorders that affect melanocyte function. Although vitiligo has a characteristic clinical appearance and histological features, the presence of early or atypical lesions often requires the exclusion of other disorders such as postinflammatory hypopigmentation and piebaldism. Multiple hypotheses have been put forward to explain vitiligo. An inherited tendency to develop depigmentation may involve the inherent aberrancies that have been observed in nonlesional vitiligo melanocytes in vivo as well as in vitro. These abnormalities potentially render vitiliginous melanocytes more vulnerable to assaults from extracellular factors. Such factors include keratinocyte physiology, extracellular matrix composition, humoral and cellular immunity, and environmental agents. Therapies aimed at repopulation of lesional skin include phototherapy, application of topical corticosteroids, and transplantation of skin or skin cells. Moreover, micropigmentation or camouflage can be used to restore a pigmented appearance to lesional skin. In patients in which vitiligo affects extensive areas of the body, depigmentation may be the treatment of choice. In all, this acquired pigmentary disorder can be treated in a variety of ways and should not be regarded as an untreatable affliction.

Tumour necrosis factors and several interleukins inhibit the growth and modulate the antigen expression of normal human melanocytes in vitro

In the present study the action of various cytokines as regulators of human melanocyte growth and differentiation was examined in vitro. Primary melanocyte cultures were obtained in complete medium free of 12-O-tetradecanoylphorbol-13-acetate or serum. First passage melanocytes were treated with various concentrations of recombinant tumour necrosis factor alpha and beta (rTNF-alpha, rTNF-beta), as well as with various recombinant interleukins (rIL-1a, rIL-1b, rIL-2, rIL-3, rIL-4 and rIL-6) for 6 days in complete medium and for 6 and 12 days in a mitogen-reduced medium variant. The 4-methylumbelliferyl heptanoate fluorometric microassay and Ki-67 staining were used for assessing cell proliferation, and the immunophenotype was evaluated using various monoclonal antibodies. Melanocyte proliferation in complete medium was inhibited by rTNF-alpha (-24%), rTNF-beta (-17%), rIL-1a (-21%), rIL-1b (-18%) and rIL-6 (-29%); in contrast, rIL-2, rIL-3 and rIL-4 had no antiproliferative effect. Measurements of Ki-67-positive nuclei confirmed these results. In the reduced medium variant, none of the above cytokines inhibited melanocyte proliferation. Recombinant TNF-alpha and rTNF-beta markedly reduced the expression of the pigment cell-associated antigens HMB-45 and K.1.2, and they enhanced the expression of VLA-2, ICAM-1 and HLA class I antigens and strongly induced HLA-DR. Similar changes were induced by rIL-1a, rIL-b and rIL-6, and rIL-2 decreased the expression of HLA class I antigens and of ICAM-1. In conclusion, several cytokines inhibited the growth and modulated the phenotype of melanocytes in vitro.(ABSTRACT TRUNCATED AT 250 WORDS)