Critical role of metabotropic glutamate receptor 4 in bone marrow-derived dendritic cells in the Th17 cell differentiation and the melanogenesis of B16 cells

Vitiligo is an acquired pigmentary disorder resulting from selective destruction of melanocytes. Emerging studies have suggested that T helper cell 17 (Th17) is potentially implicated in vitiligo development and progression. It was recently discovered that metabotropic glutamate receptor 4 (mGluR4) can modulate Th17-mediated adaptive immunity. However, the influence of mGluR4 on melanogenesis of melanocytes has yet to be elucidated. In the present study, we primarily cultured mouse bone marrow-derived dendritic cells (BMDC) and then knocked down and over-expressed mGluR4 using transfection. Transduced BMDC were co-cultured with CD4+ T cells and the expression of Th17-related cytokines were measured. The morphology and melanogenesis of B16 cells were observed after being treated with co-culture medium of CD4+ T cells and transduced BMDC. We found that mGluR4 knockdown did not affect the co-stimulatory CD80 and CD86 upregulation after lipopolysaccharide stimulation but did increase the expression of Th17-related cytokines, and further down-regulated the expression of microphthalmia-associated transcription factor (MITF) and the downstream genes, decreased melanin production, and destroyed the morphology of B16 cells. Conversely, over-expression of mGluR4 reduced the expression of CD80 and CD86, suppressed the production of Th17-related cytokines, increased the expression of MITF, and did not destroy the morphology of B16 cells. Our study confirmed that mGluR4 modulated the Th17 cell polarization and resulted in the alteration of melanogenesis and morphology of B16 cells. Collectively, these findings suggest mGluR4 might be a potent target involved in the immune pathogenesis of vitiligo.

Vulvar vitiligo-like depigmentation and multiple halos of hypomelanosis at the trunk following treatment with imiquimod 5% cream for vulvar condylomata: casual or related events?

A 25-year-old Caucasian female with multiple genital warts involving the vulvar area was treated with imiquimod 5% cream. During follow-up the patient developed areas of hypopigmentation at the site of application of imiquimod cream and areas of hypomelanosis around multiple preexisting nevi of the trunk. At 18 months follow-up genital depigmentation persisted and halo nevi of the trunk were still present. Different mechanisms of imiquimod-induced depigmentation have been reported. Halo nevi are considered expression of an autoimmune response. In the case presented here, it might be conceivable that both vitiligo-like depigmentation at the site of application and halo of hypomelanosis around melanocytic nevi have been induced by the same immunologic mechanism elicited by topical application of imiquimod.

Vitiligo - Part 1

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

Evaluation of subtypes of peripheral blood lymphocytes in patients with vitiligo

Vitiligo is characterized with white patches on the skin and alteration of melanocytes in dermoepidermal junction. Autoimmune mechanisms with an underlying genetic predisposition are the most likely causes of vitiligo. This study was performed to evaluate immune disturbance in vitiligo and clarify its more details. A total of 29 vitiligo patients and 21 healthy controls were included in this case control study. Complete blood count was measured and peripheral blood samples were evaluated floweytometrically for surface antigenic markers including CD3, CD4, CD8, CD19, CD16, CD56 and CD25 for determining the percentage and total number of various lymphocyte subgroups. Patients with different clinical subtypes were compared with each other and controls in terms of the flowcytometry results. Obtained information was assessed by SPSS statistical software. Total numbers of CD3+, CD8+ T cells, B cells and CD25+ cells were significantly increased in generalized type vitiligo patients in comparison with localized type. CD25+ cells were also increased significantly in generalized and stable types of vitiligo compared with healthy controls and finally the total number of lymphocytes was significantly decreased in localized type vitiligo patients in comparison with healthy controls.. Our data indicate cellular immune disturbance in vitiligo. Disorders of immune regulatory system may play a major role in this context. Significant CD25+ or regulatory T cells increment in different clinical subtypes of the disease is in favor of the above hypothesis. Later and larger studies may result in new and effective routs of treatment for vitiligo acting through regulating immune system

Vitiligo y tiroiditis de Hashimoto: asociación o síndrome autoinmune? / Vitiligo and Hashimoto's thyroiditis: an association or an autoimmune syndrome?

Se sospecha de ciertos virus y otros agentes como causantes de la tiroiditis de Hashimoto, siendo bien conocida la asociación con otras entidades inmunes, entre ellas el vitiligo. Una vez disparados los fenómenos inmunológicos se generan anticuerpos contra los antígenos microbianos (o de otro tipo), pero también Ac. contra antígenos propios como los de la estructura tiroidea y la piel. En el vitiligo hay alta incidencia de anticuerpos organoespecíficos, pero también otros anticuerpos no organoespecíficos, sugiriéndose para los síndromes autoinmunes múltiples y las colagenopatías un fuerte parentesco clínico, laboratorial y quizá etiológico. En este caso clínico en particular la tarea del dermatólogo cobró importancia pues toda la investigación generada se debió a la repentina aparición de vitiligo en un paciente con síntomas vagos

Avaliaçäo da funçäo tireóidea e presença de anticorpos antitireóideos em crianças com vitiligo / Evaluation of thyroid function and the presence of thyroid antibodies in children with vitiligo

Uma amostra de 32 crianças e adolescentes portadoras de vitiligo localizado ou generalizado, foi avaliada para a presença de história familiar de doenças auto-imunes, disfunçäo tireóidea e presença de anticorpos antitireóideos. História familiar para tireoidopatia foi encontrada em 15,6 por cento do total da amostra e para vitiligo em 18,7 por cento. A funçäo tireóidea, avaliada através das dosagens de T3, T4 e TSH medidos por quimioluminescência, foi normal em todos os casos. Os anticorpos antitireoglobulina e antiperoxidase foram positivos em, respectivamente, 2 pacientes (6,25 por cento) e 8 pacientes (25 por cento). Concluiu-se pela alta frequência de anticorpos antitireóideos em crianças com vitiligo, o que sugere a necessidade de avaliaçäo tireóidea inicial destas crianças e posterior acompanhamento, com a finalidade de detecçäo precoce de disfunçäo tireóidea clínica ou subclínica

Detection of antibodies to melanocytes in vitiligo by western immunoblotting

To more fully define the nature of the antibody response to melanocytes which is associated with vitiligo, a Western immunoblot assay was used to test the sera of 28 patients with vitiligo (21 with active non-segmental, and 7 with stable segmental diseases) and 26 normal individuals for antibodies to antigens in detergent extracts of melanocyte membrane fractions. Antibodies to melanocytes were found in 26 (93%) of the patients with vitiligo, and in 16 (62%) of the control individuals. Patients with vitiligo and control individuals both had antibodies to an 80 approximately 83 kD antigen. The patient with vitiligo, in addition, had antibody responses to antigens with MWs of 45, 65, and 110 kD. Antibodies to these antigens were present in 46, 25, and 31% of vitiligo patients, but in only 19%. 0%, amd 0%, respectively, of the normal individuals. The heterogeneity of the antibody responses to melanocytes in vitiligo was further confirmed by the presence of antibodies to at least 3 distinct antigens in one-third of vitiligo patients but in none of the normal individuals. There was no difference in antibody response between patients with generalized and segmental vitiligo, suggesting that the pathogenesis of diseases was similar in both cases.

Detection of antibodies to human melanoma cell in vitiligo by western blot analysis

Vitiligo is a disease in which melanocytes are selectively destroyed. The disease is thought to be an autoimmune process being there are antibodies to pigment cells in the sera of patients and animals with vitiligo. In the present study, sera from vitiligo patients were examined for reactivity with the human melanoma cell line, SK-Mel-28, by Western blot analysis of solubilized membrane antigens of these cells to identify the pigment cell antigens defined by antibodies in the patients with vitiligo. Antibody reactivity to human melanoma cells (SK-Mel-28) was investigated in 14 patients with vitiligo, and 16 with normal control individuals. Antibodies to the 116-113, 60, 40 KD antigens were associated with vitiligo being present in 79%, 86%, and 43% respectively of the patients with vitiligo, but in only 6%, 38% and 6% of the normal controls. In contrast, antibodies to the 160-155, 78 and 64 KD antigens were equally common in vitiligo and in normal individuals. The results suggest that autoreactivity to pigment cells occurs more commonly in patients with vitiligo than in the normal control and high autoreactivity to pigment cells in the vitiligo sera might be an impertinent epiphemenon to destroyed pigment cell.

Immunohistochemical studies from vitiligo: comparison between active and inactive lesions

Vitiligo is an acquired, progressive depigmenting disorder of unknown etiology. In this study, to clarify pathogenesis of vitiligo, the marginal skin of actively spreading and stable vitiligo was examined using ICAM-1, HLA-DR, CD4 and CD8 monoclonal antibodies. In immunohistochemical study, ICAM-1 was expressed in four of five epidermis in active lesions, but not in stable lesion. Dermal ICAM-1 was also expressed in all active and stable lesions. HLA-DR was also expressed in all active epidermis in active lesions, but two of five epidermis in stable lesion. Dermal HLA-DR was also expressed in all active and stable lesion. CD4 lymphocytes were expressed more strongly in active lesion, but CD8 lymphocytes were not different in both lesions. There was no significant difference of degree of positivity with CD4 and CD8 in normal control specimens. In conclusion, we think that ICAM-1 and HLA-DR expression, cytokines released from keratinocytes, melanocytes or lymphocytes and infiltration of activated T-lymphocytes play an important role in disease activity.

Inmunofenotipos leucocitarios en el vitiligo / Leukocitaries immunophenotipes at the vitiligo

El vitiligo es una enfermedad pigmentaria, que afecta al sistema melanocítico y acarrea como consecuencia la no producción de melanina, definido clínicamente como máculas acrómicas. En el presente se evaluaron los distintos inmunofenotipos que participan en esta patología. Para ello se emplearon diversos anticuerpos monoclonales utilizando la técnica de inmunoperoxidasa. En este contexto, se estudiaron 10 pacientes con vitiligo, excluyendo otras enfermedades hipomelanocíticas. Las biopsias fueron congeladas en nitrógeno líquido y cortadas en un criomicrotomo (3-4) micromicras de espesor) y posteriormente cuantificados los siguientes anticuerpos monoclonales: CD4, CD8, CD1, ICAM-1, alfa-beta y gamma-delta. Los resultados obtenidos muestran una elevada densidad de células mononucleares que expresan en fenotipo CD4+, CD8+, CD1+, y alfa-beta en comparación con otros trabajos previos realizados en piel normal. El incremento de células de Langerhans (mayor o igual 1433 cel/mm2), como células presentadoras de antígeno y accesorias de la piel, podría jugar un papel importante en el control de la generación de la respuesta inmune cutánea. Por otro lado, los linfocitos T que expresan fenotípicamente CD4+ y CD8+, mostraron una acumulación selectiva hacia la zona basal y la relación CD4/CD8 en los infiltrados fue de 1,38 considerado dentro de los valores normales. Por otro lado la expresión del ICAM-1 por los queratinocitos en la epidermis (n=8 de un total de 10), sugiere un estado pro-inflamatorio que puede contribuir con la patología de la enfermeda

studio in vitro e in situ de la respuesta inmune en el eritema discrómico perstans y vitiligo / Study in vitro e in situ of the immune responsein the Erythema dyschromicum perstans and vitiligo

El eritema discrómico perstans (EDP) y el vitiligo son dermatosis pigmentarias cutáneas de etiología desconocida, en las que existen evidencias que sugieren una importante participación del sistema inmune. En el presente trabajo, se estudiaron los infiltrados leucocitarios de ambas enfermedades. La caracterización linfocitaria in situ se realizó en pacientes con EDP mas clofazima y piel de voluntarios sin lesiones cutáneas aparentes. Los resultados obtenidos muestran que la administración de la droga estimula la acumulación de linfocitos T cooperador de las zonas afectadas de la piel

Estudio de la inmunidad celular in situ en eritema discrómico perstans y vitiligo / Study in situ of the cellular immunity in erythema dyschromicum perstans and vitiligo

El Eritema Discrómico Perstans (EDP) y el Vitiligo son dos dermatosis pigmentarias cutáneas de etiología desconocida. En el presente estudio los infiltrados leucocitarios de EDP (n=10) y de Vitiligo (n=5) fueron estudiados, usando la técnica de la inmunoperoxidasa de avidinabiotina (ABC) y anticuerpos monoclonales que reconocen las siguientes subpoblaciones celulares: T-Supresor-Citotóxico (CD8=Leu-2), T-cooperadores (CD4=OKT4), T-Supresores (Leu-15), Pan T (Leu-4), Macrófagos (Leu-M3) y células de Langerhans (CD1=Leu-6); y marcadores celulares para antígeno la, Gamma Interferón, Interleucina-2 y receptor para Interleucina-2. El análisis inmunocitoquímico mostró una acumulación selectiva de células T-Citotóxicas Leu-4+, Leu-2+, Leu-15-en la epidermis tanto de EDP como de lesiones recientes de Vitiligo. Además, un aumento en el número de células de Langerhans epidérmicas Leu-6 se observó en algunos de los casos de EDP y de Vitiligo. La relación CD4/CD8 en las lesiones y en la piel no envuelta para ambos desórdenes no mostró diferencias significativas, no obstante valores menores que uno se apreciaron sólo en los infiltrados de piel lesionada. Los macrófagos en los infiltrados dérmicos de EDP se encontraban generalmente yuxtapuestos al pigmento melánico. Los linfocitos que expresaban en su superficie antígenos tipo TAC, IL-2 y Gamma Interferón, fueron muy pocas en los infiltrados dérmicos. Algunas células NK se encontraban también presentes en la epidermis enferma. Estas observaciones morfológicas sugieren una importante participación de la inmunidad celular en la discromia de diversos desórdenes pigmentarios cutáneos