The melanin-concentrating hormone receptor 1, a novel target of autoantibody responses in vitiligo

Vitiligo is a common depigmenting disorder resulting from the loss of melanocytes in the skin. The pathogenesis of the disease remains obscure, although autoimmune mechanisms are thought to be involved. Indeed, autoantibodies and autoreactive T lymphocytes that target melanocytes have been reported in some vitiligo patients. The objective of this study was to identify pigment cell antigens that are recognized by autoantibodies in vitiligo. Using IgG from vitiligo patients to screen a melanocyte cDNA phage-display library, we identified the melanin-concentrating hormone receptor 1 (MCHR1) as a novel autoantigen related to this disorder. Immunoreactivity against the receptor was demonstrated in vitiligo patient sera by using radiobinding assays. Among sera from healthy controls and from patients with autoimmune disease, none exhibited immunoreactivity to MCHR1, indicating a high disease specificity for Ab's against the receptor. Inhibition of MCH binding to its receptor by IgG from vitiligo patients was also shown.     

Free triiodothyronine has a distinct circadian rhythm that is delayed but parallels thyrotropin levels

CONTEXT: TSH is known to have a circadian rhythm, but the relationship between this and any rhythm in T(4) and T(3) has not been clearly demonstrated. OBJECTIVE: With a view to optimizing thyroid hormone replacement therapy, we have used modern assays for free T(4) (FT4) and free T(3) (FT3) to investigate circadian rhythmicity. SETTING: The study was performed at a university hospital. DESIGN AND SUBJECTS: This was a cross-sectional study in 33 healthy individuals with 24-h blood sampling (TSH in 33 and FT4 and FT3 in 29 individuals) and cosinor analysis. RESULTS: Of the individuals, 100% showed a sinusoidal signal in TSH, for FT4 76%, and for FT3 86% (P < 0.05). For FT4 and FT3, the amplitude was low. For TSH the acrophase occurred at a clock time of 0240 h, and for FT3 approximately 90 minutes later at 0404 h. The group cosinor model predicts that TSH hormone levels remain above the mesor between 2020 and 0820 h, and for FT3 from 2200-1000 h. Cross correlation of FT3 with TSH showed that the peak correlation occurred with a delay of 0.5-2.5 h. When time-adjusted profiles of TSH and FT3 were compared, there was a strong correlation between FT3 and TSH levels (rho = 0.80; P < 0.0001). In contrast, cross correlation revealed no temporal relationship between FT4 and TSH. CONCLUSIONS: FT3 shows a circadian rhythm with a periodicity that lags behind TSH, suggesting that the periodic rhythm of FT3 is due to the proportion of T(3) derived from the thyroid. Optimizing thyroid hormone replacement may need to take these rhythms into account.     

The relationship of HLA-DR3 and outcome after antithyroid drugs to the IgG subclass distribution of thyroid autoantibodies in Graves' disease

We have examined the IgG subclass distribution of thyroglobulin (Tg) and microsomal (M) autoantibodies in 31 patients with Graves' disease before and after treatment with carbimazole. IgG1 and IgG2 subclass antibodies were detected before treatment in nearly all patients, and in over a third there was an excess of activity in the IgG3 and IgG4 subclasses. There were significant differences between the IgG subclasses composing Tg and M antibodies (less IgG1 and IgG3 but more IgG2 in the latter). Patients who were HLA-DR3-positive had significantly lower levels of IgG4 in M antibodies than in those who were DR3-negative. A variety of changes were found after treatment, and these depended on whether the patient entered remission or relapse. In particular, IgG1 levels of M antibodies were consistently higher in the relapse group, whereas after 1 year in remission IgG4 levels fell, and IgG2 levels rose. These results show preferential production of certain IgG subclasses composing thyroid autoantibodies in Graves' disease which appears to be associated with HLA-DR3 status and the response to antithyroid drugs.     

A CTLA-4 gene polymorphism is associated with both Graves' disease and autoimmune hypothyroidism

OBJECTIVEThe autoimmune thyroid diseases, Graves' disease and autoimmune hypothyroidism, result from a complex interaction between genetic, environmental and endogenous factors. The genetic loci conferring susceptibility remain unclear. A recent report has demonstrated an association between a microsatellite polymorphism of the CTLA-4 gene (allele 106) on chromosome 2q33 and Graves' disease in Caucasian patients in the USA. The aim of the present study was to confirm this association in UK patients and to determine whether this polymorphism is also associated with autoimmune hypothyroidism.
DESIGNAnalysis of Caucasian patients with autoimmune thyroid disease from a single clinic, compared to local Caucasian controls.
PATIENTSWe studied 112 patients with Graves' disease, 44 with autoimmune hypothyroidism and 91 controls.
MEASUREMENTSCTLA-4 microsatellite gene polymorphisms were determined by polymerase chain reaction amplification of genomic DNA and resolution of the products on sequencing gels.
RESULTSAs in previous studies, 21 alleles of the CTLA-4 microsatellite region were detected. Allele 106 was significantly increased in patients with Graves' disease ( P =0.006) and in those with autoimmune hypothyroidism ( P =0.02) when compared to controls. There was no significant difference between the groups in the distribution of the other alleles and no association between allele 106 and sex, HLA-DR or -DQ specificities or the presence of ophthalmopathy in the Graves' patients.
CONCLUSIONSThese results confirm that the CTLA-4 gene, or one closely associated with it, confers susceptibility to Grave's disease but is not specific as the CTLA-4 106 allele is also associated with autoimmune hypothyroidism. This association seems to be with autoimmune thyroid disease in general.     

Failure to demonstrate cell-mediated immune responses to thyroid antigens in Graves' disease using in vitro assays of lymphokine-mediated migration inhibition

The use of in vitro assays of cell-mediated immunity has provided evidence of a defect in thyroid antigen-specific T suppressor cells in the peripheral blood of patients with autoimmune diseases. We employed a direct assay of T lymphocyte migration inhibition in an attempt to demonstrate cell-mediated immune responses to thyroid antigens in untreated patients with hyperthyroid Graves' disease and examined the influence of (1) a variety of antigen preparations, (2) different assay conditions, and (3) the HLA-DR3 status of normal subjects on this system. There was no significant difference in the migration of lymphocytes from 13 untreated patients with hyperthyroid Graves' disease to a crude 800 X g supernatant antigen preparation of normal human thyroid when incubated at either 20 or 37 C compared with the response of 13 normal subjects. The mean migration index was 57 +/- 22 (+/- SD) in the Graves' patients compared with 65.2 +/- 19.9 in the normal subjects at 20 C and 83 +/- 16.9 in the Graves' patients compared with 86.6 +/- 15.1 in the normal subjects at 37 C. Similarly, there was no significant difference in the migration indices obtained with T cells from Graves' patients and normal subjects using an 800 X g supernatant prepared from the thyroid glands of 2 patients with Graves' disease, incubated at 20 or 37 C (44.0 +/- 22.5 in the Graves' patients compared with 45.7 +/- 12.8 in the normal subjects at 20 C and 67.9 +/- 20.8 in the patients compared with 72 +/- 12.6 in the controls at 37 C). In contrast, the migration indices calculated for 20 C incubation were significantly lower than the corresponding value at 37 C using 800 X g normal thyroid antigen (P less than 0.05) and 800 X g Graves' thyroid antigen (P less than 0.01) in both patient and control groups. An identically prepared uterine antigen produced a similar reduction in the migration indices at 20 C compared with those at 37 C in 6 normal donors (P less than 0.05), but no temperature effect was found when 8 normal subjects were tested with purified protein derivative of tuberculin. The responses of 12 normal individuals to 800 X g supernatants of the normal and Graves' thyroid antigens were not influenced by the HLA-DR3 antigen.(ABSTRACT TRUNCATED AT 400 WORDS)     

The calcium-sensing receptor is a target of autoantibodies in patients with autoimmune polyendocrine syndrome type 1

CONTEXT: Autoimmune polyendocrine syndrome type 1 (APS1) is an autosomal recessive disorder caused by mutations in the autoimmune regulator gene. Hypoparathyroidism occurs in 80% of patients with APS1 and has been suggested to result from an autoimmune reaction against the calcium-sensing receptor (CaSR) on parathyroid cells. However, the detection of CaSR antibodies in APS1 remains controversial, with some studies disputing the relevance of the receptor as an autoantigen. OBJECTIVE: The aim of this study was to analyze a defined set of APS1 patient sera for the presence of CaSR antibodies using different assay systems. RESULTS: APS1 patients and individuals with other autoimmune disorders along with healthy subjects were tested for antibody binding to the CaSR. In an immunoprecipitation assay with the CaSR expressed in human embryonic kidney 293 cells, 12 of 14 (85.7%) APS1 and two of 28 (7.1%) Graves' disease patients were considered positive for CaSR antibodies. The prevalence of receptor antibodies was significantly greater than that in the cohort of healthy individuals only in the APS1 patient group (P < 0.0001). In a flow cytometry assay, seven of 14 (50.0%) APS1 patient sera showed binding to the extracellular domain of the CaSR. The prevalence of receptor antibodies in the APS1 patient group was significantly greater than that in the group of healthy controls (P = 0.023). No CaSR antibodies could be detected in any patients or controls using a radiobinding assay. CONCLUSION: The CaSR is an autoantigen in APS1, but detection of antibodies against the receptor appears to be influenced by the assay system used.     

Radioiodine treatment for benign thyroid diseases

Radioiodine has been in use for over 60 years as a treatment for hyperthyroidism. Major changes in clinical practice have occurred with the realization that accurate dosimetry is incapable of avoiding the risks of hypothyroidism, while more accurate assessment of the risks of other adverse effects of radioiodine such as ophthalmopathy and carcinogenesis have become available. More is also known of the potential for pretreatment with an antithyroid drug to affect the outcome of radioiodine treatment. However, we are still uncertain of the benefits of radioiodine treatment in subclinical hyperthyroidism. During the last two decades there has been wider acceptance of radioiodine as a safe and effective therapy for benign, nontoxic goitre, coupled with waning enthusiasm for the use of levothyroxine, as the risks and benefits of this option have become more apparent. The use of recombinant TSH offers the prospect that radioiodine treatment of nontoxic goitre can be simplified and improved, although more studies of this strategy are urgently required.     

Invasive aspergillosis of paranasal tissues in children with malignancies

Paranasal aspergillosis was encountered in five children with relapsed malignancies. All had received broad-spectrum antibiotics within two weeks of development of aspergillosis, and all had absolute granulocyte counts less than 200/mm3 for at least three weeks. None had received prior antifungal therapy. There was an average delay of eight days before the correct diagnosis was established by either biopsy or culture. These data emphasize the need to obtain surveillance cultures of the upper respiratory tract passages in severely neutropenic patients receiving prolonged antibiotic therapy, and raise a question concerning prophylactic use of antifungal therapy in this group.     

Analysis of a microsatellite polymorphism of the cytotoxic T-lymphocyte antigen-4 gene in patients with vitiligo

The CTLA-4 gene encodes a T-cell receptor that is involved in the regulation of T-cell activation. Recent studies have demonstrated an association of a microsatellite polymorphism [variant lengths of a dinucleotide (AT)n repeat] lying in exon 3 of the CTLA-4 gene, specifically a 106-bp allele, with autoimmune disorders, such as Graves' disease, autoimmune Addison's disease and autoimmune hypothyroidism. The aim of the present study was to determine whether the same polymorphism of the CTLA-4 gene was associated with vitiligo, a disorder that may have an autoimmune origin and can be present in patients who have one or more autoimmune diseases. CTLA-4 gene microsatellite polymorphisms were determined for 74 vitiligo patients (53 without any autoimmune disorder; 21 with one or more autoimmune disease) and 173 healthy controls, who had no clinical evidence of either vitiligo or any other autoimmune disorder, by polymerase chain reaction amplification of genomic DNA and resolution of the products on polyacrylamide sequencing gels. The frequency of the 106-bp allele was significantly increased (chi2 = 5. 2; P = 0.02) in vitiligo patients as a whole, in comparison with control subjects. However, when the patients were classified according to the absence or presence of an autoimmune disorder, the frequency of the 106-bp allele was significantly increased (chi2 = 14.8; P = 0.0001) only in the group of vitiligo patients who also had an autoimmune disease. However, the fact that 17 of 21 patients also had either autoimmune thyroiditis or autoimmune Addison's disease probably accounts for the apparent association of vitiligo and the 106-bp allele in this patient group. However, it was found that the relative risk of 3.2, conferred by the 106-bp allele in this group of vitiligo patients, was greater than that found for patients with only either Graves' disease, autoimmune hypothyroidism or autoimmune Addison's disease, with values of 2.1, 2.2 and 2.2, respectively. For the group of patients without an autoimmune disorder, there was no significant difference (chi2 = 0.2; P = 0.64) in the frequency of the 106-bp allele when compared with control subjects. These results indicate that there is no association between the 106-bp allele and vitiligo, at least when the disorder occurs in the absence of an autoimmune disease.