Pathogenesis Of Graves' Disease Research Articles

Serum Levels of Angiogenic Molecules in Autoimmune Thyroid Diseases and Their Correlation with Laboratory and Clinical Features

Because angiogenesis has a role in the pathogenesis of inflammatory conditions, we studied angiogenesis soluble markers in autoimmune thyroid diseases. The aim of the study was to measure concentrations of angiopoietins, Tie-2, and vascular endothelial growth factor in sera from autoimmune thyroid disease patients. Soluble Tie-2 (sTie-2), angiopoietin-1, angiopoietin-2, and vascular endothelial growth factor were quantified by ELISA in sera from 44 untreated Graves' disease (GD) patients, 25 untreated Hashimoto's thyroiditis (HT) patients, 13 non-GD hyperthyroid patients, and 22 age-matched controls. Subgroups of patients with active and non-active Graves' ophthalmopathy (GO) were analyzed. Correlations among these markers and clinical parameters were assessed by bivariate and multivariate analyses. STIE-2 levels were higher in GD or HT patients compared to controls (P < 0.01). In addition, serum Ang-2 concentrations were higher in untreated GD patients compared to controls, HT patients, or non-GD hyperthyroid patients (P < 0.01), and no difference was observed between HT patients and controls. Significant correlations were found between free T(4)/sTie-2 and free T(4)/Ang-2 levels (r = 0.464, P < 0.01; and r = 0.463, P < 0.01, respectively) as well as between sTie-2/anti-TSH receptor antibody (r = 0.527; P < 0.01) and sTie-2/Ang-2 (r = 0.563; P = 0.001). Furthermore, sTie-2 levels were significantly higher in patients with active GO when compared to those with inactive GO (P < 0.05). Interestingly, Ang-2 levels decreased significantly after treatment with antithyroid drugs (P < 0.01). Ang-2 and sTie-2 could participate in the pathogenesis of GD and potentially be used as markers of GO activity. Antithyroid drugs affect the angiogenic pattern in GD.

A Case of Graves' Disease Combined with Hantaan Virus Infection

Graves' disease (GD) is generally presented by thyrotoxicosis with hyperthyroidism, and it is an organ-specific autoimmune disease induced by thyroid-stimulating hormone receptor autoantibodies. However, among diverse etiologies, viral infections have been suggested to trigger or to be involved in the pathogenesis of GD. Hantaan virus infection causing hemorrhagic fever with renal syndrome (HFRS) is common in South Korea and its pathogenesis is suggested to be an immunologic mechanism. We have experienced a patient who was diagnosed as HFRS with thyrotoxicosis. So we herein report the case as GD combined with the hantaan virus infection.

Association of Graves’ Disease and Prevalence of Circulating IFN-γ-producing CD28− T Cells

Peripheral blood CD4(+) and CD8(+) T-cell subsets lacking surface CD28 have been suggested to predispose patients to immune-mediated disorders. To determine the role of CD28(-) T-cell subset in Graves' disease (GD), we characterized peripheral blood CD4(+)CD28(-) and CD8(+)CD28(-) T cell from early onset GD patients. GD patients had significantly higher percentages of CD4(+)CD28(-) and CD8(+)CD28(-) T cells than did healthy donors. Both CD28(-) T cells expressed mostly CD45RO, suggesting that they are activated and/or are memory T cells. GD patient-derived CD4(+)CD28(-) and CD8(+)CD28(-) T cells produced more intracellular IFN-gamma than their counterparts from healthy donors. Furthermore, CD4(+)CD28(-) and CD8(+)CD28(-) T cells from GD patients with Graves' ophthalmopathy (GO) secreted higher level of intracellular IFN-gamma than those CD28(-) T cells from GD patients without GO. Retrospective analysis showed that the increased levels of CD4(+)CD28(-) T cells and their IFN-gamma-producing subgroups were positively correlated to the serum anti-thyrotropin receptor (TSHR) autoantibodies (TRAb). Our observations suggest that increased IFN-gamma-producing CD28(-) T cells in GD patients may play an important role in the pathogenesis of GD.

Expression of Bcl-2 Family Proteins in Thyrocytes from Young Patients with Immune and Nonimmune Thyroid Diseases

The Bcl-2 family proteins that control homeostasis of cells play an important role in apoptosis. This group consists of antiapoptotic (Bcl-2, Bcl-XL) and proapoptotic (Bcl-2 associated protein X, Bax; B-cell homologous antagonist/killer, Bak) molecules. In the thyroid, abnormal apoptotic activity may be involved in a variety of diseases such as autoimmune thyroid diseases. The aim of the current study was to estimate the expression of pro- and antiapoptotic proteins in thyroid tissues from young patients with Graves’ disease (GD), nontoxic nodular goiter and toxic nodular goiter using Western Blot and immunohistochemistry. Identification of the antiapoptotic Bcl-2 and Bcl-XL molecules in the thyrocytes revealed higher expression of both proteins in patients with GD (assessed as +++/++ and ++/+, respectively). In adolescents with toxic and nontoxic nodular goiter, this expression was lower (Bcl-2 ++/+ , ++/+; Bcl-XL +, +). The tissue material was additionally subjected to Western Blot analysis, which in GD patients showed the presence of Bcl-2 and Bcl-XL in one band p26 kDa. In patients with toxic and nontoxic nodular goiter, the intensity of expression for these two antiapoptotic proteins was lower (referred to band 26 kDa for Bcl-2 and Bcl-XL). Identification of the proapoptotic proteins Bax and Bak revealed their predominance in thyrocytes of GD patients (+, ++/+, respectively) as compared to patients with toxic and nontoxic nodular goiter (0/+, 0/+ for Bax and 0/+, 0/+ for Bak). In GD patients, Western Blot analysis showed Bax expression in one band 21 kDa and Bak in two bands p50, p24 kDa. In patients with nodular goiter, the degree of expression of both proapoptotic proteins was lower and referred to band 21 kDa for Bax (toxic and nontoxic goiter) and 24 kDa for Bak (toxic goiter only). Patients with GD showed a statistically significant correlation between Bcl-2 expression and antibodies against receptor for thyroid stimulating hormone (R = 0.47, p < 0.03); however, such a correlation was not observed in patients with nodular goiter. In conclusion, our findings suggest that the changes in the expression of regulatory proteins of the Bcl-2 family in the thyroid follicular cells indicate the involvement of apoptosis in the pathogenesis of GD.

Pathogenesis of Graves Disease and Mechanism of Action of Thiroid Hormones

Pathogenesis of Graves Disease and Mechanism of Action of Thiroid Hormones

Identification of apoptotic proteins in thyroid gland from patients with Graves' disease and Hashimoto's thyroiditis

Apoptosis, i.e. natural programmed cell death, is a physiological phenomenon indispensable for normal functioning of the organism. The signal to apoptosis can be started practically in any cell. Disturbances in the apoptosis regulation determine the essential link of the pathogenesis of many diseases, including autoimmune thyroid disorders.The aim of the study was to assess the expression of Fas/FasL and caspase eight in the tissues of the thyroid gland in patients with Graves' disease (GD), non-toxic nodular goiter (NTNG) and Hashimoto's thyroiditis (HT). The analysis of Fas/FasL expression was performed by western blot and immunohistochemical investigation with DAB-visualization and Mayer's hematoxylin staining. Caspase-8 expression in thyroid follicular cells was assayed by western blot method.Identification of the proapoptotic proteins FasL and Fas exhibited their pronounced expression in the thyroid tissue in GD patients (++; ++) and HT (+++; +++) as compared to the NTNG group (0/+; 0/+). Among the study groups, the expression of caspase-8 was revealed in band 55 kDa from patients with autoimmune thyroid diseases.In GD patients, the percentage of thyrocytes with FasL expression correlated positively with TRAb (R = 0.58, p < 0.02). However, no such correlations were noted in HT or non-toxic multinodular goiter. There were no significant correlations between thyroid hormones and the percentage of thyrocytes with Fas and FasL expression.In conclusion, our findings suggest that the changes in the expression of apoptotic molecules on the surface of T lymphocytes and thyroid follicular cells in patients with autoimmune thyroid disorders reflect their substantial involvement in the pathogenesis of GD and HT. In addition, analysis of Fas/FasL and caspase-8 expression in thyroid tissue may indicate the disease activity and immunological phenotype.

TNF gene polymorphisms in Graves’ disease: TNF-308 A/G meta-analysis

Autoimmune thyroid diseases (AITDs), including Graves’ disease (GD) and Hashimoto thyroiditis, are associated with human MHC polymorphisms. The present study analysed two polymorphisms within tumour necrosis factor (TNF) genes (TNF-308 A/G SNP and TNFb (CT)n microsatellite) in a sample of 106 GD patients and 199 controls from the Tunisian population. The present study was designed to investigate genetic association of these polymorphisms (taken separately or considered as a haplotype) with GD development. Statistical analysis confirmed the association between the TNF-308 A allele and GD (p=0.002), previously reported in a Tunisian familial study. The data from the present study suggest that the TNF-308 A allele plays a role in GD pathogenesis in the Tunisian population. This association was further confirmed by a meta-analysis on eight published studies (p<0.0001). Haplotype analysis with GD revealed an associated haplotype (TNFb3–TNF-308 G haplotype: c=13.16; p=0.0003).

Association analysis of interleukin gene polymorphisms in autoimmune thyroid diseases in the Tunisian population.

Autoimmune thyroid diseases (AITDs), including Graves' disease (GD) and autoimmune hypothyroidism (AH), are inherited as complex traits. Among the genes contributing to AITDs susceptibility are genes of the IL-1 family. IL-1 regulates T and B lymphocyte maturation, including the induction of several cytokines and cytokine receptors. Therefore, disturbances of this balance may not only play a role in inflammation but also in the pathogenesis of autoimmunity. In order to investigate genetic association of IL-1 gene polymorphisms with AITDs, we performed both a familial study in a large Tunisian pedigree with high prevalence of AITDs (64 patients and 176 controls), and a case-control study (131 GD unrelated patients and 225 healthy controls). PCR and PCR-RFLP methods were used to analyse respectively a VNTR in the IL-1RN gene and three SNPs in both IL-1B genes (-511 C/T and +3954 C/T) and IL-1A (-889 C/T). The family-based association study showed an association of the IL-1B+3954 C/T polymorphism (p=0.02) and two haplotypes IL-1RN*3/C/T/T and IL-1RN*1/C/T/T (p=0.009 and p=0.047 respectively) with AITDs. The case-control study is the first study revealing a significant association of the IL-1A-889 C/T polymorphism (chi2=10.23; p=0.0014) with susceptibility to GD. Our data suggest that the IL-1 gene cluster may harbour susceptibility genes for AITDs and GD pathogenesis in the Tunisian population.

The Role of Apoptosis in Thyroid Autoimmunity

There is increasing evidence showing that apoptosis plays a role in the development of the autoimmune thyroid diseases-Hashimoto's (lymphocytic) thyroiditis (HT) and Graves' disease (GD). The immune pathogenesis of HT and GD is not yet fully understood, but evidence points toward several steps. A defect in CD4(+)CD25(+) T regulatory cells breaks the immunological tolerance of the host and induces an abnormal production of cytokines, which facilitates the initiation of apoptosis. Though apoptosis appears to play a role in the pathogenesis of both HT and GD, the mechanisms that mediate these processes appear different. The induction of apoptosis in HT results in the destruction of thyrocytes, while apoptosis in the GD leads to damage of thyroid-infiltrating lymphocytes. The differences in the apoptotic mechanisms produce two very different forms of thyroid autoimmune responses, eventually developing into HT and GD, respectively.

Intercellular adhesion molecule 1 gene polymorphisms do not contribute to Graves’ disease in Chinese patients

In order to study the association of G241R polymorphism of ICAM-1 gene with an earlier onset of Graves' disease (GD) and the susceptibility of K469E polymorphism to Graves' ophthalmopathy (GO) in Chinese population. A case-control and replication study was performed in 212 GD patients and 204 healthy subjects to analyze the genotypes. Furthermore the distribution of ICAM-1 genotypes was investigated in subgroups of patients with GD according to the onset age and the ophthalmopathy. No G241R polymorphism of ICAM-1 gene was detected in Chinese. No significant differences of allele and genotype frequencies regarding K469E polymorphism were found between GD patients and healthy controls (chi2 = 0.092, P = 0.762; chi2 = 1.089, P = 0.580). In addition, the genotype-phenotype correlation was not identified either. We found no association of G241R and K469E polymorphisms of the ICAM-1gene with the development of GD in a Chinese population. However, we could not rule out possible contributions of other polymorphisms of the ICAM-1gene to the pathogenesis of GD. Therefore, further studies are needed to elucidate the role of ICAM-1gene in Graves' disease in different population.

Relationship between CTLA-4 and CD28 Molecule Expression on T Lymphocytes and Stimulating and Blocking Autoantibodies to the TSH-Receptor in Children with Graves’ Disease

The present study was performed to elucidate the relationship between CTLA-4/CD28 molecules and stimulating (TSAb) and blocking (TBAb) antibodies to the TSH-receptor (TSH-R) in Graves’ disease. CD28 and CD152 (CTLA-4) are glycoprotein molecules which provide a potent costimulatory signal for T-cell activation and proliferation via interactions with their ligands, B7.1/B7.2 molecules, which are present on the surface of antigen-presenting cells. The aim of the study was to estimate the expression of cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4, CD152), CD28, B7.1 (CD80), and B7.2 (CD86) molecules on peripheral blood cells in patients with Graves’ disease (GD) (n = 55, mean age 15.5 ± 5.1 years) and nontoxic nodular goiter (NTNG) (n = 55, mean age 15.2 ± 4.5 years), in comparison with sex and age-matched healthy control subjects (n = 55, mean age 15.2 ± 3.9 years). The expression of the costimulatory molecules on mononuclear cells was analyzed by three-color flow cytometry using a Coulter EPICS XL cytometer. Detection of TSAb and TBAb to the TSH-R using JPO9 CHO cells in unfractionated serum was measured by a highly sensitive commercial radioimmunoassay. When compared with healthy control subjects and euthyroid patients with GD, untreated patients with GD showed a significant increase of CD152+ (p < 0.001, p < 0.001) and CD28+ (p < 0.01, NS) T lymphocytes, respectively. After 6–12 months of methimazole therapy, the percentage of these cells in the peripheral blood of hyperthyroid patients returned to normal values. In addition, patients with GD showed an increase in the percentage of both B7.1 (3.8%) and B7.2 (18.4%) molecules on activated monocytes, compared to patients with NTNG (0.5% p < 0.05, 2.5% p < 0.01, respectively) and healthy control subjects (0.2% p < 0.05, 0.8% p < 0.003, respectively). In patients with untreated GD there was a statistically significant positive correlation between the expression of CTLA-4 on the surface of peripheral blood T cells and the index of TSAb antibodies (R = 0.54, p < 0.001) as well as a negative correlation with TBAb antibody titer (R = –0.58, p < 0.001). However, no such correlations were noted with regard to CD28 and anti-TPO, anti-TG, and TRAb antibodies. We conclude that changes in the expression of costimulatory molecules on the surface of peripheral blood T cells and their significant relationship with the level of antithyroid antibodies indicate an involvement of these molecules in the pathogenesis of GD.

Serum Antibodies against Hepatitis C Virus in Iranian Patients with Graves' Disease.

Hepatitis C virus (HCV) infection has been associated with a plethora of immune and autoimmune perturbations. A variety of conditions ranging from endocrinopathies to different skin diseases has been described in HCV infection. The aim of this study was to investigate the prevalence and clinical significance of HCV infection in patients with graves' disease (GD). A total of 55 patients with GD (30 women, 25 men, mean age: 35.24 +/- 12.27 years) and 50 control subjects (28 women, 22 men, mean age: 33.34 +/- 11.99 years) were examined. Third generation ELISA test was used for detection of antibodies to HCV in human sera, and anti-HCV seropositivity was confirmed by recombinant immunoblot assay (RIBA).All normal controls were anti-HCV negative whereas anti-HCV antibody was present in 1 patient with GD and confirmed by Western blotting. These results indicate that there was no significant difference of anti-HCV antibodies between patients and controls.In this study no relationship was found between GD and HCV infection, which imply that hepatitis C virus has not a direct causal role in the pathogenesis of GD, however, this does not rule out a "hit and run" virus induced disease.

Association between the TAP1 Gene Codon 637 Polymorphism and Graves' Disease

A total of 95 patients with Graves' disease (GD) and 105 normal healthy controls were enrolled in this study to determine how a single site polymorphism of the transporter associated with antigen processing 1 (TAP1) gene contributes to the pathogenesis of GD. The polymorphism was detected using polymerase chain reaction (PCR)-based restriction analysis. Associations between GD and the two-site polymorphisms of the TAP1 gene at codons 333 and 637 were evaluated. No significant differences were revealed comparing GD patients and normal individuals for the distributions of genotypes and allelic variants at codon 333 (p=0.253 and p=0.891, respectively). By contrast, the distributions for the AA homozygote at codon 637 were reduced and those for the GA heterozygote were increased comparing the two groups (p<0.0001). The allelic analysis also demonstrated lower A and higher G allele frequencies (p=0.0008; OR=2.745, 95% CI=1.482-5.085) comparing the GD patients with the normal healthy controls. This shows that the single-site polymorphism of the TAP1 gene at codon 637 may be an indicator for predicting development of GD.

CTLA-4 AT-repeat polymorphism reduces the inhibitory function of CTLA-4 in Graves' disease.

Graves' disease (GD) is thought to be an autoimmune disease with a strong genetic component. Candidate genes include human leukocyte antigen (HLA) class II genes and CTLA-4. The CTLA-4 gene has a variable length AT-repeat polymorphism in the 3'-untranslated region. We previously found that the AT-repeat of 104 bp or longer was associated with GD. In this study, we categorized patients with GD and normal controls (NC) by genotyping the CTLA-4 AT-repeat and investigated the function of CTLA-4. Peripheral blood mononuclear cells (PBMC) and DNA were prepared from adult Caucasians (NC = 34, GD = 37). Genotypes of the AT-repeat polymorphism were divided into three groups according to their alleles. We related the CTLA-4 polymorphism in each genotype to augmentation of T-cell proliferation induced by a soluble anti-CTLA-4 antibody during incubation with irradiated Epstein-Barr virus (EBV)-transformed B cells. Proliferation of T cells from subjects with the 86/86 bp (shorter) allele was less than T cells from patients with longer alleles. The length of the AT-repeat allele correlated inversely with augmentation of proliferation after CTLA-4 blockade in subjects with GD. The CTLA-4 AT-repeat polymorphism affects the inhibitory function of CTLA-4. The long AT-repeat allele is associated with reduced control of T-cell proliferation and thus contributes to the pathogenesis of GD.

Current perspective on the pathogenesis of Graves' disease and ophthalmopathy.

Graves' disease (GD) is a very common autoimmune disorder of the thyroid in which stimulatory antibodies bind to the thyrotropin receptor and activate glandular function, resulting in hyperthyroidism. In addition, some patients with GD develop localized manifestations including ophthalmopathy (GO) and dermopathy. Since the cloning of the receptor cDNA, significant progress has been made in understanding the structure-function relationship of the receptor, which has been discussed in a number of earlier reviews. In this paper, we have focused our discussion on studies related to the molecular mechanisms of the disease pathogenesis and the development of animal models for GD. It has become apparent that multiple factors contribute to the etiology of GD, including host genetic as well as environmental factors. Studies in experimental animals indicate that GD is a slowly progressing disease that involves activation and recruitment of thyrotropin receptor-specific T and B cells. This activation eventually results in the production of stimulatory antibodies that can cause hyperthyroidism. Similarly, significant new insights have been gained in our understanding of GO that occurs in a subset of patients with GD. As in GD, both environmental and genetic factors play important roles in the development of GO. Although a number of putative ocular autoantigens have been identified, their role in the pathogenesis of GO awaits confirmation. Extensive analyses of orbital tissues obtained from patients with GO have provided a clearer understanding of the roles of T and B cells, cytokines and chemokines, and various ocular tissues including ocular muscles and fibroblasts. Equally impressive is the progress made in understanding why connective tissues of the orbit and the skin in GO are singled out for activation and undergo extensive remodeling. Results to date indicate that fibroblasts can act as sentinel cells and initiate lymphocyte recruitment and tissue remodeling. Moreover, these fibroblasts can be readily activated by Ig in the sera of patients with GD, suggesting a central role for them in the pathogenesis. Collectively, recent studies have led to a better understanding of the pathogenesis of GD and GO and have opened up potential new avenues for developing novel treatments for GD and GO.

Graves’ IgG activate upstream enhancer of the sodium/iodide symporter

Graves’ thyroid tissue has been shown to express elevated levels of human sodium/iodide symporter (hNIS) mRNA and protein. In the present work, we demonstrate for the first time that hNIS gene expression in Graves’ disease (GD) is up-regulated by Graves’ IgG. Here, in transient transfection experiments using FRTL-5 cells, hNIS promoter and enhancer/luciferase construct showed an up to six-fold increase in transcriptional activity after incubation with purified Graves’ IgG. Mutation of a CRE site in hNIS enhancer inhibited Graves’ IgG response. In addition, mutation of a novel putative regulatory region in hNIS promoter reduced the stimulation three-fold. This discovered putative regulatory sequence might play a role in hNIS up-regulation by Graves’ IgG and TSH. The data presented here complement our current knowledge of the pathogenesis of GD and will contribute to a better understanding of mechanisms regulating the thyroid iodide concentrating activity.

Generation of a transgenic animal model of hyperthyroid Graves' disease.

Graves' disease (GD) is an organ-specific autoimmune disease characterized by hyperthyroidism. Agonistic anti-thyrotropin receptor antibodies (thyroid-stimulating antibodies, TSAb), which mimic the thyrotropin (TSH) action, are thought to cause GD. The precise immunological mechanism of TSAb production, however, remains elusive. Previous immunization approaches using TSH receptor led to transient hyperthyroidism, but did not seem sufficient for comprehensive understanding of the development of autoimmune responses. To create GD-related autoimmunity in mice, we here generated TSAb-transgenic mice in which a patient-derived TSAb is expressed in B cells. Expression of the human TSAb in mice resulted in various manifestations of hyperthyroidism including increased free thyroxine levels with concomitantly decreased TSH levels, increased thyroid uptake of technetium pertechnetate, hyperthermia and thyroid hyperplasia. We found a correlation between the serum levels of human TSAb immunoglobulin and free thyroxine. In addition, conventional B cells expressing the TSAb were partially deleted in the periphery while B1 cells expressing the TSAb persisted and accumulated in the peritoneal cavity, a finding consistent with previous demonstrations that the maintenance of B1 cells plays an important role in the development of autoimmune diseases. Thus, our transgenic mouse may provide a novel and useful animal model for elucidating the pathogenesis and pathophysiology of GD.

Complex Association Analysis of Graves Disease Using a Set of Polymorphic Markers

Graves disease is complex autoimmune thyrotoxicosis. A number of genes may contribute to the development of the disorder. Some of them may be genes that encode cytotoxic T-lymphocyte-associated serine esterase-4 (CTLA4), subunit 2 of large multifunctional protease (LMP2), thyroid-stimulating hormone receptor (TSHR), and interleukin 1 receptor antagonist (IL1RN). We studied polymorphism of Ala17Thr CTLA4, H60R LMP2, Pro52Thr TSHR, and IL1RN–VNTR in healthy controls (n = 93) and patients with Graves disease (n = 78) using PCR. To study CTLA4, H60R, and TSHR polymorphism, PCR products were digested with MboI, Hin6I and PsyI, respectively. Comparative analysis using χ2 test showed significant differences in allele and genotype frequency of Ala17Thr polymorphic marker between the two groups studied. Thus, the CTLA4 gene may be involved in the pathogenesis of Graves disease in a Moscow population.

Changes in Th1/Th2 cytokine balance in Graves' desease.

Graves' disease (GD) is characterised by hyperthyroidism, caused by stimulatory thyrotropin receptor (TSHR) antibodies. Recent research shows that an important factor in the pathogenesis of autoimmune diseases is the change in the balance between Th1 cytokines, which promote cell mediated immunity, and Th2 cytokines, which promote humoral immunity. There are contradictory data about this balance shift in GD. Our objective was to determine the Th1/Th2 cytokine balance shift in patients with newly diagnosed GD, when compared to the same balance in healthy controls. We isolated mononuclear cells (MNC) from the peripheral blood of healthy donors and from patients with newly diagnosed GD before treatment. The MNC were activated with ionomycin in combination with phorbol 12-myristate 13-acetate (PMA). After 40-hour incubation, the concentrations of the cytokines produced (IFN-γ, IL-4, IL-10, IL-12) in the culture supernatants were measured by ELISA (Endogen, USA). The MNC cultures from patients with GD produced significantly less IL-12 and significantly more IL-10 and IL-4 than MNC cultures from healthy controls. All calculated ratios of Th1 against Th2 cytokines in MNC cultures from patients with GD were significantly lower than in MNC cultures from healthy controls. Our results show a systemic shift of cytokine production in patients with GD toward the Th2 cytokine response, thus confirming the key role of TSHR antibodies and humoral immunity in the pathogenesis of GD.

Animal models of Graves' disease.

Graves' disease (GD) is an autoimmune condition in which goitre and hyperthyroidism are induced by thyroid stimulating antibodies (TSAB) which mimic the action of thyrotrophin (TSH). The target of the autoimmune response is the thyrotrophin receptor (TSHR) and, since its cloning, a number of differing approaches have been adopted in an attempt to develop an animal model of GD. Methods in which synthetic peptides or fragments of the receptor produced in bacteria or insect cells have been injected into animals together with immunological adjuvants have had only limited success in inducing some of the signs and symptoms of GD. Genetic immunisation resulted in thyroiditis in the majority, but TSAB formation in only a minority, of treated inbred mice. Transfer of receptor in vitro primed T cells to syngeneic naive recipients, with priming either using a bacterial fusion protein or genetic immunisation, induced destructive thyroiditis in non-obese diabetic (NOD) mice but lymphocytic thyroiditis in BALBc mice. Furthermore, the orbits of 17/22 of the BALBc animals, but not the NOD animals, with thyroiditis had orbital changes similar to those seen in thyroid eye disease. TSAB and elevated thyroxine levels were induced in AKR/N mice injected with fibroblasts expressing the full length human TSHR and murine major histocompatibility complex (MHC) class II homologous to the recipient mice. No thyroiditis was induced but preliminary results from a different group using the same protocol suggest that receptor autoantibodies and thyroid dysfunction could be transferred using T cells primed in vitro with the receptor and MHC-II expressing cells. The majority of the studies described above have studied inbred mouse strains. In a novel departure, the NMR outbred strain has been treated by genetic immunisation with very promising results, including the induction of increased thyroxine levels in 4/30 female mice, accompanied by TSAB in addition to thyroiditis, and with signs of hyperactivity and orbital pathology. This review discusses the various protocols together with the information regarding the pathogenesis of GD which each has contributed, and concludes with an evaluation of how close we are to mimicking this polygenic, multifactorial disease.