BACKGROUND: Increasing evidence indicates that oxidative stress and interferon γ (IFNγ)-driven cellular immune responses are responsible for the pathogenesis of vitiligo. However, the connection between oxidative stress and the local production of IFNγ in early vitiligo remains unexplored. The aim of this study was to identify the mechanism underlying the production of IFNγ by mast cells and its impact on vitiligo pathogenesis. METHODS: Skin specimens from the central, marginal, and perilesional skin areas of active vitiligo lesions were collected to characterize changes of mast cells, CD8 + T cells, and IFNγ-producing cells. Cell supernatants from hydrogen peroxide (H 2 O 2 )-treated keratinocytes (KCs) were harvested to measure levels of soluble stem cell factor (sSCF) and matrix metalloproteinase (MMP)-9. A murine vitiligo model was established using Mas-related G protein-coupled receptor-B2 (MrgB2, mouse ortholog of human MrgX2) conditional knockout (MrgB2 -/- ) mice to investigate IFNγ production and inflammatory cell infiltrations in tail skin following the challenge with tyrosinase-related protein (Tyrp)-2 180 peptide. Potential interactions between the Tyrp-2 180 peptide and MrgX2 were predicted using molecular docking. The siRNAs targeting MrgX2 and the calcineurin inhibitor FK506 were also used to examine the signaling pathways involved in mast cell activation. RESULTS: IFNγ-producing mast cells were closely aligned with the recruitment of CD8 + T cells in the early phase of vitiligo skin. sSCF released by KCs through stress-enhanced MMP9-dependent proteolytic cleavage recruited mast cells into sites of inflamed skin (Perilesion vs . lesion, 13.00 ± 4.00/high-power fields [HPF] vs . 26.60 ± 5.72/HPF, P <0.05). Moreover, IFNγ-producing mast cells were also observed in mouse tail skin following challenge with Tyrp-2 180 (0 h vs . 48 h post-recall, 0/HPF vs . 3.80 ± 1.92/HPF, P <0.05). The IFNγ + mast cell and CD8 + T cell counts were lower in the skin of MrgB2 -/- mice than in those of wild-type mice (WT vs . KO 48 h post-recall, 4.20 ± 0.84/HPF vs . 0.80 ± 0.84/HPF, P <0.05). CONCLUSION Mast cells activated by MrgX2 serve as a local IFNγ producer that bridges between innate and adaptive immune responses against MCs in early vitiligo. Targeting MrgX2-mediated mast cell activation may represent a new strategy for treating vitiligo.
Vitiligo/metabolism* ; Mast Cells/immunology* ; Animals ; Interferon-gamma/metabolism* ; Mice ; Humans ; Melanocytes/metabolism* ; Receptors, G-Protein-Coupled/genetics* ; Mice, Knockout ; Mice, Inbred C57BL ; Male ; Female ; Matrix Metalloproteinase 9/metabolism* ; Stem Cell Factor/metabolism*

OBJECTIVETo detect the serum levels of melanocyte antibodies and explore the relation between melanoma antigen recognized by T-cells (MART-1) and vitiligo in children.

METHODSThe serum samples were collected from children with vitiligo to test the autoantibodies, and divided into low- and high-titer group according to the test results. Melanocytes were incubated with the serum samples, and the changes of melanocyte surface antigen were evaluated using specific MART-1 antibody.

RESULTSThe serum melanocyte antibody levels in children with vitiligo were significantly higher than those in normal subjects. The expression level of melanocyte surface antigen MART-1 increased obviously after incubation of the melanocyte with high antibody titer serum samples, and MART-1 was found to specifically bind to specific MART-1 antibody.

CONCLUSIONMelanocytes MART-1 may correlate to the autoimmune mechanism in children with vitiligo.

Adolescent ; Autoantibodies ; blood ; Child ; Child, Preschool ; Enzyme-Linked Immunosorbent Assay ; Female ; Humans ; MART-1 Antigen ; immunology ; Male ; Melanocytes ; immunology ; T-Lymphocytes ; immunology ; Vitiligo ; immunology

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.
Antibodies/*analysis ; Antigens/immunology ; Blotting, Western ; Human ; Melanocytes/*immunology ; Reference Values ; Support, Non-U.S. Gov't ; Vitiligo/*immunology/*pathology

Vitiligo is frequently associated with autoimmune diseases, such as multiple glandular insuffi ciencies and thyroid diseases. In addition, various circulating antiorgan antibodies are found in patients with vitiligo. This raises the possibility that vitiligo might also be an antibody associated au toimmune disease. Variou. alterations in peripheral mononuclear cells, especially T-cells and T-cell subsets have been desiribed in patients with vitiligo. The discovery of circulating antimelanocyte antibodies in patients with vitiligo demonstrateci that vitiligo may be associted with alterations in the specific immunity to melanocytes. These vit iligo antibodies, which are more common in patients with vitiligo than in normal individuals, react with cell surface pigment cell antigens with MWs of approximately 150, 90, 75, 40-45, and 35 kDa, and can kill rnelanocytes in vitro. It has been suggested tiat melanocytes are much more sensitive to toxic or immune mediatece injury that other cutaneou; cell types, thus explaining their apparently selective destruction in vitiligo despite the rather bro d specificity of these vitiligo antibodies. However vitiligo autoantibodies are not found in all vitilio patients. Some of t,hem are present in patients without vitiligo. Tak ing into account the common occurrence of circulation autoantibodies irrelevant to the pathogene sis of the cutaneous hypomelanosis in vitiligo patients, the pathogenetic role of these vitiligo anti bodies has not yet been demonstrated, and the possibility that they represent an impertineni epiphenomenon in vitiligo cannot be ruled out.
Allergy and Immunology* ; Antibodies ; Autoantibodies ; Autoimmune Diseases ; Humans ; Hypopigmentation ; Melanocytes ; Sensitivity and Specificity ; T-Lymphocyte Subsets ; T-Lymphocytes ; Thyroid Diseases ; Vitiligo*