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.

Serum antibodies to collagen XIII: a further good marker of active Graves' ophthalmopathy.

OBJECTIVE: In Graves' ophthalmopathy (GO) intercellular adhesion molecule-1 (ICAM-1) is thought to play a key role in lymphocyte infiltration into the orbit, and serum levels of its soluble form are positively correlated to clinical activity score (CAS). Serum antibodies against collagen XIII (CollXIIIAb), a plasma membrane protein expressed at a low level in almost all connective tissue-producing cells, have been detected in GO, but their significance is unclear. The aim of this study was to search for CollXIIIAb in Graves' patients with and without ophthalmopathy and to correlate their levels with CAS and with serum soluble ICAM-1 (sICAM-1) values. PATIENTS: We studied 66 patients with Graves' disease whose sera had been previously tested for sICAM-1 levels, grouped as follows: 28 with moderate and active ophthalmopathy (group 1), 12 of them hyperthyroid (group 1a) and 16 euthyroid (group 1b); 13 with mild and inactive ophthalmopathy and normal thyroid function (group 2); 25 without ophthalmopathy (group 3), 11 of them hyperthyroid (group 3a) and 14 euthyroid (group 3b). Finally, 26 sera of normal controls were studied. MEASUREMENTS: CollXIIIAb were evaluated by an enzyme-linked immunosorbent assay (ELISA) method. RESULTS: In group 1 patients, CollXIIIAb were detected at high levels in 8/12 (66.6%) in group 1a [optical density (OD) ranging from 0.529 to 0.894] and in 10/16 (62.5%) in group 1b (OD 0.560-0.855). In group 2 patients, CollXIIIAb were detected but at low levels (OD 0.205-0.260) in 4/13 patients (30.7%). In group 3 patients, CollXIIIAb were present at low levels in 6/11 (54.5%) of group 3a and in 5/14 (35.7%) of group 3b (OD 0.215-0.290 and 0.144-0.245, respectively). CollXIIIAb were detected in only 4/26 normal controls (15%) but at low levels (OD 0.150-0.185). CollXIIIAb values in both groups 1a and 1b were significantly higher than those of the remaining groups. A positive correlation between CollXIIIAb levels and CAS but not thyroid hormone levels was found in groups 1a, 1b and 2. Moreover, a positive correlation between CollXIIIAb levels and sICAM-1-values was also evidenced in all three groups. CONCLUSIONS: Our results suggest that CollXIIIAb could be considered as a further good marker of active inflammatory processes involving the adipose connective tissue in GO. In particular, the high levels of CollXIIIAb in sera of Graves' patients with active ophthalmopathy could reflect an increased expression of type XIII collagen on the membrane of activated fibroblasts in these patients. Thus, the evaluation of these antibodies could be added to other known markers as a useful and inexpensive tool in monitoring Graves' patients and in modulating the treatment of GO.

Extraocular muscle antibodies and the occurrence of ophthalmopathy in Graves' disease.

OBJECTIVE: The aim of this study was twofold: first to investigate the presence of extraocular muscle antibodies (EMAb) in sera of Graves' patients with ophthalmopathy characterized by clinical extraocular muscle (EM) involvement; second to evaluate in Graves' patients without ophthalmopathy whether longitudinal variations of EMAb have a predictive role for the development of eye disease. PATIENTS: We evaluated sera of Graves' patients previously tested for G2sAb and FpAb; in particular, sera of 32 patients with moderate or severe ophthalmopathy and EM involvement: 18 with active disease (group 1), 14 with inactive disease (group 2). Moreover, we evaluated longitudinally sera of 19 Graves' patients without ophthalmopathy previously tested for anti-GS2 (G2sAb) and antiflavoprotein antibodies (FpAb; group 3). During the 18-month follow-up, four of them did not develop ophthalmopathy (group 3a), and 15 did: seven developed eye disease (group 3b) with clinical EM involvement. In particular, moderate disease and clinical activity score (CAS) >/= 4 in four of them, severe ophthalmopathy and CAS /= 4 without EM involvement (group 3c). MEASUREMENTS: EMAb were evaluated in all samples by indirect immunofluorescence method. RESULTS: EMAb were detected in 13 out of 18 patients (72.2%) in group 1 (titre 1/32-1/128) and in five out of 14 patients (35.7%) in group 2 (titre 1/2-1/8). As regards to group 3, at the start of the study EMAb were detected in 13 out of 19 patients (72%) at titres 1/2-1/8; during the follow-up they became or persisted negative in all patients in group 3a, while they increased at titres ranging from 1/64 to 1/128 in all patients in group 3b before the onset of ophthalmopathy. Finally, in group 3c, four patients showed a mild increase (1/8-1/16) of EMAb before the onset of eye disease, while four patients were negative during the entire follow-up. CONCLUSIONS: Our results indicate that EMAb are a good marker of ophthalmopathy with EM involvement and their titre is higher in patients with active than in those with inactive disease. Thus, even if our results must be confirmed on a larger cohort of patients, the increase of EMAb in patients with Graves' disease could be considered as a risk factor for the development of ophthalmopathy with subclinical/clinical EM impairment. In this connection we propose the evaluation of EMAb, in Graves' patients with subclinical and clinical ophthalmopathy, as a simple and sensitive marker of the EM inflammatory process.