Evaluating the role of Th0 and Th1 clones in autoimmune thyroid disease by use of Hu-SCID chimeras

Decreased β-catenin expression contributes to IFNγ-induced chemokine secretion and lymphocyte infiltration in Hashimoto's thyroiditis

Hashimoto's thyroiditis (HT) is a very common organ-specific autoimmune disease characterized by lymphocyte infiltration and the destruction of thyroid follicular cells (TFCs), in which IFN-γ and chemokines play pivotal roles. Moreover, β-catenin has been implicated in the regulation of T cell infiltration. However, whether β-catenin is involved in Hashimoto's thyroiditis is unknown. Here, we examined β-catenin expression in thyroid tissues and investigated its role in the pathogenesis of HT. The results showed that β-catenin expression was markedly reduced in the thyroid tissues of HT patients; more importantly, IFN-γ treatment markedly reduced the expression of β-catenin and was accompanied by the secretion of chemokines such as CCL5, CXCL16, GRO-β, and GRO-γ in TFCs in vitro, which was attributed to GSK-3β/β-catenin signaling pathway activation. Collectively, the decreased expression of β-catenin might contribute to IFNγ-induced chemokine secretion and lymphocyte infiltration in the development of HT.

Uterus globulin associated protein 1 (UGRP1) is a potential marker of progression of Graves' disease into hypothyroidism

Approximately 20% of Graves' disease (GD) patients may result eventually in hypothyroidism in their natural course. Uterus globulin-associated protein 1 (UGRP1) was associated with GD in our previous study. Here we investigated the role of UGRP1 in the development of autoimmune thyroid disease (AITD). The results showed that UGRP1 was expressed in the thyrocytes of most Hashimoto's thyroiditis (HT) patients and a proportion of GD patients (293 HT and 198 GD). The pathologic features of UGRP1-positive thyrocytes resembled "Hürthle cells", and were surrounded by infiltrated leukocytes. The positivity rate of TPOAb in UGRP1-positive GD patients was much higher than that in -negative GD patients. Moreover, UGRP1 was co-expressed with Fas and HLA-DR in the thyrocytes of AITD patients. We also found IL-1β but not Th1 or Th2 cytokines was able to upregulate the expression of UGRP1. Our findings indicated that UGRP1 may be a novel marker in thyrocytes to predict GD patients who develop hypothyroidism.

The Role of Iodine and Selenium in Autoimmune Thyroiditis

Iodine and selenium (Se) are both essential elements to thyroid hormone economy, while they represent key players in the development of autoimmune thyroiditis.Chronic high iodine intake has been associated in various studies with increased frequency of autoimmune thyroiditis. In susceptible individuals, iodine excess increases intra-thyroid infiltrating Th17 cells and inhibits T regulatory (TREG) cells development, while it triggers an abnormal expression of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) in thyrocytes, thus inducing apoptosis and parenchymal destruction. As was shown in a mouse model, high iodine supply leads to changes in the immunogenicity of the thyroglobulin molecule, upregulation of vascular intercellular adhesion molecule-1 (ICAM-1), and reactive oxygen species (ROS) generation in the thyrocytes. Serum Se levels were found decreased in Hashimoto thyroiditis and especially in Graves' disease as well as in thyroid-associated ophthalmopathy patients, the levels being related to the pathogenesis and outcome. Selenium is strongly involved, via the variable selenoproteins, in antioxidant, redox, and anti-inflammatory processes. Selenium enhances CD4+/CD25 FOXP3 and T regulatory cells activity while suppressing cytokine secretion, thus preventing apoptosis of the follicular cells and providing protection from thyroiditis. Selenium supplementation may be useful in autoimmune thyroid diseases, though, while usually well-tolerated, it should not be universally recommended, and it is also likely to be helpful for those with low Se status and autoimmunity. Broadly speaking, the achievement and maintenance of "selenostasis" as well as adequate urinary iodine excretion are mandatory to control disease, while, putatively, they may additionally be critical to preventing disease.

The increased but non-predominant expression of Th17- and Th1-specific cytokines in Hashimoto's thyroiditis but not in Graves' disease

Hashimoto's thyroiditis (HT) is considered to be mediated mainly by Th1 cells, but it is not known whether Graves' disease (GD) is associated with Th1 or Th2 predominance. Th17 cells, a novel subset of Th cells, play a crucial role in the pathogenesis of various autoimmune disorders. In the present study, the expression of IL-17A and IFN-γ was investigated in patients with HT or GD. mRNA expression of IL-17A and IFN-γ in peripheral blood mononuclear cells (PBMC) from 43 patients with autoimmune thyroid disease (AITD) and in thyroid tissues from 40 AITD patients were measured by real-time quantitative PCR. The protein expression of IL-17A and IL-23p19 was examined by immunohistochemistry in thyroid tissues from 28 AITD patients. The mRNA levels of IL-17A and IFN-γ were higher in both PBMC and thyroid tissues of HT patients than in controls (mRNA levels are reported as the cytokine/β-actin ratio: IL-17 = 13.58- and 2.88-fold change and IFN-γ = 16.54- and 2.74-fold change, respectively, P < 0.05). Also, the mRNA levels of IL-17A and IFN-γ did not differ significantly in GD patients (P > 0.05). The high protein expression of IL-17A (IOD = 15.17 ± 4.8) and IL-23p19 (IOD = 16.84 ± 7.87) in HT was confirmed by immunohistochemistry (P < 0.05). The similar high levels of IL-17A and IFN-γ suggest a mixed response of Th17 and Th1 in HT, where both cells may play important roles in the destruction procedure by cell-mediated cytotoxicity.

Exon 33 T/T genotype of the thyroglobulin gene is a susceptibility gene for Graves' disease in Taiwanese and exon 12 C/C genotype protects against it

This study investigates whether Tg gene polymorphisms can be associated with Graves' disease (GD) in a Taiwanese population and identifies potential polygenic susceptive genes for GD. The findings of such a study may have important implications for prognostic prediction and treatment of GD. We performed case control association studies for the 3 discovered Tg single nucleotide polymorphisms (SNPs) (E10, E12, E33) in 215 GD patients and 141 controls. The three SNPs were identified within the Tg gene. These SNPs were analysed by a fluorescent-based restriction fragment length polymorphism method (RFLP) and PCR. The genotype and allele frequencies at E10SNP158, E12SNP and E33SNP in GD patients were compared with those of the controls. In addition, we analysed the interactions between these SNPs and the clinical and laboratory variables. We found a significant difference in the T/T genotype of E33SNP and G/G genotype of E12SNP compared with the control group (p<0.001). We also found the E33SNP T/T genotype to be positively associated with development of GD, whereas the E12SNP G/G genotype protected it.

Cytotoxic T lymphocyte-associated molecule-4 polymorphisms in Turkish Graves' disease patients and association with probability of remission after antithyroid therapy

BACKGROUND

One of the candidate genes for susceptibility to Graves' disease (GD) is cytotoxic T lymphocyte-associated molecule-4 (CTLA-4), a negative regulator of T-cell activation. In order to elucidate the relationship of GD with the A/G polymorphism in exon 1 and the C/T polymorphism in the promoter region of the CTLA-4 gene, the frequency of these two polymorphisms was identified in 98 healthy individuals and 77 patients with GD.

METHODS

Polymorphisms were analyzed using a PCR-RFLP method. We also examined the relationship between the A/G polymorphism and various clinical and laboratory variables among patients with GD. All patients were treated with an initial dose of propranolol (40-60 mg /day) and PTU (300-400 mg/day). Subjects remained on this treatment for a minimum of 6 months and were followed in our clinic for 1 year after cessation of treatment.

RESULTS

The frequency of the GG genotype was significantly higher among patients with GD than among controls of both sexes (P<0.05; odds ratio=3.145, 95% CI=1.212-8.161). There was no difference between patients and controls with regard to the C/T polymorphism. There was no statistical difference in age, sex, cigarette smoking, initial serum thyroid hormone levels, initial goiter size, initial TSH-receptor antibodies, or NOSPECS classification for orbitopathy among the patients with the three different genotypes (GG, AG, and AA). Of the patients with the AA genotype, 17 of 29 (58.6%) were in remission 1 year after PTU withdrawal, while 18 of 33 patients (54.4%) with the AG genotype were in remission 1 year later. However, only 3 of 15 patients (20%) with the GG genotype were in remission 1 year after withdrawal of antithyroid drug therapy (P=0.016 GG/AA, P=0.025 GG/AG). Using 1 year after discontinuation of antithyroid drug therapy as the cut-off point for multivariate logistic regression analysis, we found that the GG genotype, TSH at the end of therapy, and age were independent risk factors for recurrence.

CONCLUSION

We conclude that the occurrence of GD is linked to the A/G polymorphism of the CTLA molecule in the Turkish population and is associated with a lower chance of remission after discontinuation of PTU treatment.

Graves' disease after interleukin-2 therapy in a patient with human immunodeficiency virus infection

Interleukin-2 (IL-2) is a cytokine that regulates the proliferation and differentiation of lymphocytes, and is currently used clinically in the treatment of assorted malignancies. Additionally, IL-2 is being actively investigated in clinical trials for treatment of human immunodeficiency virus (HIV) infection. Patients treated with IL-2 are susceptible to autoimmune thyroid disease (AITD), presenting as thyroiditis, which leads to either thyrotoxicosis or hypothyroidism, if not correctly and promptly identified and treated. IL-2-induced hypothyroidism can also sometimes follow a thyrotoxic phase. However, the development of Graves' disease (GD) in this clinical setting has not been reported to date. Here, we report the case of a 39-year-old HIV-infected man in whom GD developed after IL-2 therapy. We correlated the immunologic parameters pertinent to the patient's HIV infection status with clinical, hormonal, and serologic evidence of GD during its emergence. This revealed an association between peripheral blood cell numbers of specific lymphocyte subpopulations (CD4(+), CD3(+)CD25(+), and naïve T-cells) and serum levels of markers for AITD (free thyroxine [T(4)] and thyroid-stimulating immunoglobulin). Interestingly, no association was found between natural killer (NK) cell numbers and AITD markers. The immunopathogenesis of GD in this patient may be similar to that hypothesized for the GD that occurs in immune-reconstituted patients after combination antiretroviral therapy. From a practical standpoint, we propose that patients who have received or are receiving treatment with IL-2 who show signs of hyperthyroidism need to be carefully evaluated for GD.

Cytotoxic T lymphocyte-associated molecule-4 polymorphism and relapse of Graves' hyperthyroidism after antithyroid withdrawal

We studied the A/G single nucleotide polymorphism (SNP) at position 49 in exon 1 of the cytotoxic T lymphocyte-associated molecule-4 gene in 148 Chinese Graves' disease (GD) patients and 171 controls. Our primary aim was to test for the association of this SNP with the relapse of the hyperthyroidism after antithyroid withdrawal. Our secondary aim was to investigate the relationship between GD patients and controls according to the SNP genotypes. All GD patients were divided into the following three groups according to the time of relapse after drug discontinuation: group 1, early relapse within 9 months; group 2, relapse between 10 and 36 months; and group 3, relapse 3 or more years after discontinuation of treatment. There was a significant difference of genotype frequencies (P < 0.001) and allele frequencies (P < 0.001) among the three groups of patients. The frequency of the G/G genotype decreased from 79% to 64% and 39% in groups 1, 2, and 3, respectively. Compared with controls, a strong association (P < 0.001) of G allele was found for group 1, and moderate significance (P = 0.04) was found for group 2, but no association (P = 0.33) was found for group 3. At the end of treatment, the percentage of patients with persistent TSH-receptor antibody was statistically different (A/A, 9.0%; A/G, 20.8%; G/G, 45.5%; P = 0.004). Using 3 yr as the cutoff point for multivariate logistic regression analysis, we found that the G/G genotype (adjusted odds ratio, 3.1 compared with A/G plus A/A; 95% confidence interval, 1.3-7.1), larger goiter size at the end of treatment, and positive TSH-receptor antibody at the end of treatment were independent risk factors of recurrence. We conclude that the A/G polymorphism of the cytotoxic T lymphocyte-associated molecule-4 gene affects the progress of GD. The G/G genotype is associated with poor outcome.

Peptide scanning for thyrotropin receptor T-cell epitopes in mice vaccinated with naked DNA

Vaccinating mice with DNA encoding the thyrotropin receptor (TSHR), the major autoantigen in Graves' disease, induces memory T cells that secrete interferon-gamma (IFN-gamma) in response to TSHR antigen. We used a panel of 29 synthetic TSHR peptides encompassing the ectodomain and three extracellular loops to identify T-cell epitopes after TSHR-DNA vaccination of BALB/c, NOD.H-2h4, and AKR/N mice. These strains were chosen because of their previous use in animal models of thyroid autoimmunity. In initial studies, challenge of splenocytes with TSHR protein induced IFN-gamma and tumor necrosis factor-alpha (TNF-alpha) production in all three strains of mice. BALB/c mice recognized three peptides, all in the TSHR A subunit. These peptides differed from the four peptides recognized by nonobese diabetic (NOD mice NOD H-2h4). Three of the latter were also in the A subunit. The fourth was within the intervening C peptide region excised on TSHR cleavage into A and B subunits. Because of high and erratic responses in AKR/N mice, their TSHR T-cell epitopes could not be determined. In summary, we report that TSHR DNA vaccination of BALB/c and NOD.H-2h4 mice, with different major histocompatibility complex (MHC) class II genes (I-Ad and I-Ak, respectively), recognize restricted, nonoverlapping TSHR T-cell epitopes, nearly all in the TSHR A subunit.

Autoimmune response to the thyroid in humans: thyroid peroxidase--the common autoantigenic denominator

Autoimmunity to thyroid peroxidase (TPO), manifest as high affinity IgG class autoantibodies, is the common denominator of human thyroid autoimmunity, encompassing patients with overt hyper- or hypothyroidism as well as euthyroid individuals with subclinical disease. The identification and cloning of TPO (the "thyroid microsomal antigen") provided the critical tool for analyzing B and T cell reactivity to this major thyroid autoantigen. In particular, the availability of immunoreactive TPO permitted the isolation of essentially the entire repertoire of human monoclonal antibodies, a feat unparalled in an organ-specific autoimmune disease. These recombinant autoantibodies (expressed as Fab) provide insight into the genes encoding their H and L chains as well as the conformational epitopes on TPO with which serum autoantibodies interact. Analyses of TPO autoantibody epitopic "fingerprints" indicate a lack of epitope spreading as well as a genetic basis for their inheritance. Limited data are available for the responses and cytokine profiles of T cells to endogenously processed TPO. Moreover, the role of thyroid cells in initiating the autoimmune response to TPO, and of B cells in expanding and/or modulating the response of sensitized T cells, has yet to be established. Finally, because autoantibody (and likely T cell) responses to TPO parallel those to TSH receptor and thyroglobulin, manipulation of T and B cell responses to TPO may provide the basis for the development of immunospecific therapy for autoimmune thyroid disease in general.

Helper T cells in antibody-mediated, organ-specific autoimmunity

The production of pathogenic autoantibodies in organ-specific autoimmune diseases is largely T cell dependent. For many of these diseases, the precise specificities and cytokine profiles of the T cells that respond to the corresponding autoantigens have now been identified. This knowledge has been exploited to treat some models of antibody-mediated autoimmunity using peptides corresponding to the dominant helper epitopes, giving impetus to the development of a similar approach in the equivalent human diseases.

CD30 expression and interleukin-4 and interferon-gamma production of intrathyroidal lymphocytes in Graves' disease

We reported that serum levels of interleukin-5 (IL-5) and soluble CD30, mainly secreted from T helper 2 (Th2) cells, were increased in Graves' disease. To clarify the immune balance of Th1/Th2 within the Graves' thyroid gland, we have compared the expression of CD30, a preferential marker for T cells producing type 2 cytokines, and the production of interferon-gamma (IFN-gamma) and IL-4 between intrathyroidal lymphocytes (ITL) and peripheral blood lymphocytes (PBL). In PBL, none of these parameters were different between patients and normal subjects. The proportion of CD30+ cells in ITL was markedly higher (5.1%+/-2.8%, p < 0.0001) than that in patients' PBL (0.4%+/-0.3%). Likewise, both the proportions of IFN-gamma+ (14.8%+/-5.5%) and IL-4+ cells (2.4%+/-0.5%) in ITL were higher than those in PBL (9.6%+/-2.5%; p < 0.01, 1.5%+/-0.4%; p < 0.0001, respectively). The proportion of type 0 (both IFN-gamma and IL-4 positive, 1.0%+/-0.4% p < 0.001), type 1 (IFN-gamma positive, 14.0%+/-5.6%, p < 0.01) or type 2 cells (IL-4 positive, 1.4%+/-0.5%, p < 0.05) in ITL was significantly higher as compared with those in PBL (0.4%+/-0.1%, 9.0%+/-2.4%, 1.1%+/-0.3%, respectively). The ratios of ITL/PBL in CD30+ (23.3+/-30.6) and type 0 cells (2.5+/-1.2) were higher than the ratios in other subsets. The proportion of CD30+ cells correlated with the proportion of type 0 cells (r = 0.686, p < 0.01), but not with type 1 or type 2 cells. These findings suggest that there is no obvious deviation of Th2/Th1 profile in the Graves' thyroid gland, although intrathyroidal CD30+ T cells and Th0 cells may play some role in the development of autoimmune abnormalities in Graves' disease.