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The thyrotropin receptor (TSHR) is the thyroid autoantigen against which stimulating autoantibodies are directed in Graves' hyperthyroidism. Recent evidence suggests that TSHR may also serve as an orbital autoantigen in Graves' ophthalmopathy (GO) and that expression of this protein is increased in the fatty connective tissues of the orbit in this condition. It has been shown that orbital fibroblasts from patients with GO increase thyrotropin (TSH)-dependent cyclic adenosine monophosphate (cAMP) production and TSHR gene expression when cultured under conditions known to stimulate adipocyte differentiation. In the current study, we wanted to determine whether treatment of these cells with particular cytokines (each 1 ng/mL) during differentiation might further augment TSHR expression. We found that exposure to interleukin (IL)-6 increased TSHR expression above control levels in cells from patients with GO. In contrast, this cytokine did not affect TSHR expression in normal orbital cells. Neither IL-4 nor IL-1alpha had a significant stimulatory effect in either normal or Graves' cultures. These findings suggest that IL-6 may play a role in the pathogenesis of GO by increasing expression of the putative autoantigen within the adipose/connective tissues of the orbit.

Graves' ophthalmopathy (GO) is an autoimmune disease characterized by an increase in the volume of the orbital fatty/connective tissues and extraocular muscles. This volume change is due to expansion of the adipose tissues and to accumulation of glycosaminoglycans and edema within the connective tissues of the orbit. We have shown previously that a subpopulation of confluent human orbital preadipocyte fibroblasts can be induced in vitro to differentiate into cells with morphological features of adipocytes and that these cultures express functional thyrotropin receptor (TSHR). In order to identify and study these cells further, we examined the expression of leptin protein and TSHR and leptin mRNA in these cultures. Using immunocytochemistry with objective measurement of immunofluorescent staining intensity on digitized microscopic images, we determined leptin protein expression to be 6 to 37 times greater in differentiated cultures than in control cultures. In addition, we showed that the expression of both genes is enhanced in differentiated cultures. We suggest that an unknown humoral stimulus, present in Graves' disease, might act to induce the differentiation of normal orbital fibroblasts into TSHR-bearing adipocytes. This process would be expected to result in expansion of the orbital adipose tissues and increased TSHR expression within the orbit.

Graves' ophthalmopathy (GO) is an orbital autoimmune disease that is closely associated with Graves' hyperthyroidism. Examination of retroorbital tissues in GO reveals an accumulation of glycosaminoglycans, increased fat volume, lymphocytic infiltration, and the presence of several inflammatory cytokines. A subpopulation of human orbital fibroblasts can be differentiated in vitro into cells with the morphologic features of adipocytes. We demonstrated recently that these differentiated cultures show increased expression of functional TSH receptor (TSHr). To determine whether the presence of inflammatory cytokines might impact adipogenesis or TSHr expression in these cultures, we treated orbital fibroblasts from normal individuals or GO patients with tumor necrosis factor-alpha (TNF-alpha), interferon-gamma (IFN-gamma), or transforming growth factor-beta. We found that each of these cytokines inhibits TSH-dependent cAMP production and TSHr gene expression, and that TNF-alpha and IFN-gamma also inhibit morphological adipocyte differentiation. When cytokines were added after differentiation, the inhibition was less pronounced. Our results suggest that TNF-alpha, IFN-gamma, and transforming growth factor-beta may act within the orbit in GO to modulate expression of the putative orbital autoantigen, TSHr. In addition, the former two cytokines may play a role in determining the extent to which the volume of the orbital adipose tissue increases in this condition.

The notion that Graves' ophthalmopathy is an autoimmune disease has been based primarily on the clinical associations between it and Graves' hyperthyroidism, and on the frequently beneficial response of the disease to immunosuppressive therapy. Recent advances in molecular biology have led to new insights into the pathogenesis that support an autoimmune basis for this condition. In particular, there is now compelling--although not definitive--evidence that, if verified, would represent disease transfer by thyroid-secreting hormone receptor-sensitized T cells. Future studies using animal models and in vitro systems will allow definitive identification of the immune cell types, autoantigens, and autoantibodies involved in the pathogenesis of Graves' ophthalmopathy.

We sought to determine whether the predominant orbital T helper (T(H)) cell subset in orbital T cell clones established from patients with Graves' ophthalmopathy (GO) might be related to disease duration. A total of 117 clones were established from orbital adipose/connective tissues of 6 GO patients, and cytokine production was measured in 57 CD3+CD4+ clones. T(H)1-type clones were predominant in cultures from patients with recent onset (<2 yr) Graves' hyperthyroidism (n = 44; TH1/TH0/TH2 = 57/29/14%) or GO (n = 53 clones; TH1/TH0/TH2 = 47/30/23%). In contrast, TH2-type clones predominated in cultures from patients with more remote onset (>2 yr) hyperthyroidism (n = 13; TH1/TH0/TH2 = 0/31/69%; P < 0.005) or GO (n = 4; TH1/TH0/TH2 = 0/25/75%; P = 0.05). In addition, we established T cell clones from 1 TH1-dominant patient with recent-onset thyroid and eye disease using either IL-2 (12.5 ng/mL) alone or IL-2 plus IL-4 (5 ng/mL) and found no shift toward recovery of TH2-type clones in the latter. In conclusion, although the CD3+CD4+ clones characterized were not necessarily tissue antigen specific, our findings suggest that cell-mediated (TH1-type) immune reactions may predominate in the orbit in early GO, whereas humoral immunity (TH2-type) might play the greater role in later stages of the disease.

Although the autoantigen involved in Graves' hyperthyroidism is known to be the TSH receptor (TSHr), whether this antigen plays a primary role in the pathogenesis of Graves' ophthalmopathy (GO) is unclear. We sought to determine whether fibroblasts derived from orbital adipose/connective tissue are capable of differentiating into adipocytes that bear immunoreactive and functional TSHr. In addition, we assessed relative levels of TSHr gene expression in normal and GO orbital adipose/connective tissue specimens. GO and normal orbital preadipocyte fibroblasts, cultured under conditions known to stimulate adipocyte differentiation, showed evidence of adipogenesis and positive immunostaining for TSHr protein. In addition, significantly more cAMP was produced in response to TSH stimulation in the differentiated cultures than in undifferentiated cultures derived from the same individuals' cells. Other studies demonstrated relatively greater TSHr gene expression in GO than in normal orbital tissue specimens. These results indicate that orbital preadipocyte fibroblasts increase their TSHr expression with differentiation and suggest that these cells play an important role in the pathogenesis of GO. Furthermore, our studies support the concept that TSHr may be an important target antigen in this condition. Factors that stimulate adipocyte differentiation and TSHr expression in the orbit in GO have yet to be defined.

Graves' ophthalmopathy (GO) is attributed to an autoimmune process that results in the accumulation in retro-ocular tissue of glycosaminoglycans (GAG) that are in turn responsible for the development of clinical signs and symptoms. Retro-ocular fibroblasts are thought to be the source of GAG production and deposition in GO. In the present study, we investigated interleukin (IL)-1beta-induced oxygen free radical production and the role of oxygen free radicals in IL-1beta-induced GAG production in retro-ocular fibroblasts from both normal subjects and patients with GO. Normal retro-ocular fibroblasts demonstrated no measurable oxygen free radicals whereas GO retro-ocular fibroblasts showed detectable signals by electron paramagnetic resonance (EPR) spectroscopy. IL-1beta increased the free radical production in both cells. Superoxide dismutase (SOD) activity in GO retroocular fibroblasts was higher than that in normal cells. IL-1beta dose- and time-dependently stimulated the SOD activity in both cells, with GO retro-ocular fibroblasts showing less responsiveness. IL-1beta dose-dependently increased [3H]glucosamine incorporation into GAG by both cells. An exogenous oxygen free radical-generating system failed to increase GAG. Scavenging oxygen free radicals by the use of SOD (100 U/mL) and catalase (300 U/mL) partially blocked the IL-1beta-induced GAG production in both cells. These results suggest that stress related oxygen free radicals are present in the retro-ocular tissue in GO and that oxygen free radicals are involved in GAG accumulation induced by cytokine IL-1beta.

Objective: To review illness-associated changes in thyroid hormone levels with respect to the alterations in metabolism, regulation, and transport of thyroid hormones present in such a setting., Methods: We summarize normal pituitary-thyroid function and categorize the types of changes that have been noted during illness. In addition, we examine studies that have addressed the metabolic status of patients with low thyroid hormone levels and the potential utility of thyroid hormone treatment in severely ill patients., Results: The finding of altered thyroid hormone levels in hospitalized patients confirms the participation of these factors in the adaptive response to illness. Thyroid hormone alterations that occur during illness can be classified into three categories: (1) decreased production of triiodothyronine, (2) decreased serum binding of thyroid hormones, and (3) decreased secretion of thyrotropin. Study of these hormonal changes has provided insight into normal thyroid hormone regulation and metabolism as well as into neuroendocrine adaptations to illness., Conclusion: It seems reasonable to conclude that illness-associated changes in thyroid hormone levels are generally beneficial to the patient as a whole; however, the possibility of concomitant regional or individual tissue hypothyroidism exists. Conclusions about the potential utility of pharmacologic administration of triiodothyronine in selected diseases and clinical settings must await additional clinical trials. Finally, the predictable occurrence of altered thyroid hormone levels in hospitalized patients necessitates caution in both the selection and the interpretation of thyroid hormone tests in this patient population.

Interactions between between orbital fibroblasts and immunocompetent cells that infiltrate or reside within the orbit are thought to be important in the pathogenesis of thyroid eye disease (TED). These interactions are mediated primarily by cytokines; interferon-gamma, tumor necrosis factor-alpha, interleukin-1alpha and leukoregulin are of particular interest in this regard. These mediators induce or enhance the in vitro expression of immunomodulatory proteins in orbital fibroblasts, and stimulate proliferative and metabolic activities of these cells. The stimulation by particular cytokines of glycosaminoglycan synthesis in orbital fibroblasts is an important factor in the development of the clinical disease. A similarly important pathophysiological role for cytokines has been defined in rheumatoid arthritis. In this disease, the chronic erosive changes in the cartilage and bone of the joints result from cytokine-stimulated production of collegenases and other neutral proteases by synovial cells and articular chondrocytes. Advances in the understanding of the pathogenesis of rheumatologic joint disease has led to treatment trials aimed at immune-modulation, including trials of anticytokine therapy. Lessons learned in early clinical trials using these biological therapies in the treatment of rheumatoid arthritis can be applied to studies of similar agents in the treatment of TED.

Our laboratory has shown recently that the thyrotropin receptor (TSHr) is expressed in orbital adipose/connective tissues from patients with Graves' ophthalmopathy (GO), and that this receptor is not demonstrable in orbital tissues from normal individuals. In order to study the regulation of TSHr expression in the orbit in GO, we treated cultures of Graves' orbital preadipocyte fibroblasts with the TSHr ligand thyrotropin (TSH; 100 mU/L). We found increased expression of both intact (2.4 kb) and variant (1.3 kb) TSHr mRNA and of TSHr protein in orbital fibroblasts following 72 hr treatment with TSH. These studies suggest that the expression of this receptor in the orbit in vivo may be stimulated by TSH or other TSHr ligands, and that this stimulation may be important in the development of GO.

Because the thyrotropin receptor (TSHR) has long been considered a thyroid-specific protein, its presence in extrathyroidal tissues has been controversial. In this study, we sought to detect and quantify this potentially low abundance mRNA in various extrathyroidal tissues using liquid hybridization analysis (LHA) and to detect protein with immunohistochemical studies. Strongly positive protected bands, indicating the presence of both intact (2.4 kb) and variant (1.3 kb) TSHr mRNA, were apparent in LHA gel lanes corresponding to normal thyroid, Graves' thyroid, and thymus. Less abundant protected bands of the same sizes were present in lanes corresponding to normal adrenal, and samples from normal kidney were faintly positive. The full-length transcript:variant transcript ratio was approximately 1:1 in all positive tissues. Immunohistochemical analysis of TSHR-like reactivity in paraffin-embedded thymus, adrenal, and kidney revealed specific staining in each of these tissues. No TSHR mRNA or TSHR-like immunoreactivity was detected in samples from several other normal human tissues. We conclude that measurable TSHR mRNA and protein expression is not restricted to the thyroid gland. Further study is warranted to determine whether these extrathyroidal receptors play a role in normal physiology or in disease.

Retroocular fibroblast proliferation is believed to be a key component in the pathogenesis of Graves' ophthalmopathy. In the present study, we assessed the ability of superoxide radicals, generated using the xanthine oxidase/hypoxanthine system to induce cellular proliferation in cultured human retroocular fibroblasts obtained from two patients with severe Graves' ophthalmopathy and two control patients undergoing corrective eye surgery. In tissue obtained from patients with Graves' ophthalmopathy, fibroblast proliferation, as assessed by [3H]-thymidine incorporation, was induced by superoxide radicals in a dose-dependent manner. Xanthine oxidase or hypoxanthine alone had no proliferative effect, and control retroocular fibroblasts showed no proliferation in response to superoxide generation. Preincubation with the antithyroid drug methimazole, at concentrations ranging from 0-25 microM, prevented superoxide-induced fibroblast proliferation in a dose-response pattern. Preincubation with the xanthine oxidase inhibitor, allopurinol (1.0 mM) or the antioxidant nicotinamide (10 microM) also inhibited superoxide-induced fibroblast proliferation, whereas propylthiouracil (10 microM) had little effect. These studies suggest a pathway through which oxygen free radicals may contribute to the retroocular fibroblast proliferation observed in patients with Graves' ophthalmopathy.

Infiltration of the retroocular space by inflammatory cells and the accumulation of glycosaminoglycans are histological characteristics of Graves' ophthalmopathy. Various cytokines, released by infiltrating immunocompetent cells and resident connective tissue cells, play a pivotal role in the evolution of this disease. The predominant cytokines secreted by orbital T cells during the course of the disease may govern the activity and stage of the local autoimmune process. Cytokine effects of potential relevance to the pathogenesis of Graves' ophthalmopathy include their ability to stimulate orbital fibroblasts to proliferate and secrete excess quantities of glycosaminoglycans. The edema associated with these hydrophilic macromolecules is directly responsible for many of the characteristic clinical features of the disease. In addition, certain cytokines induce or enhance the expression on orbital fibroblasts of immunomodulatory proteins. We review current evidence supporting the notion that cytokines are central to the development and evolution of Graves' ophthalmopathy.

Background: Disorders of the thyroid are common in pregnancy. In particular, a thyroid nodule is frequently discovered before or during pregnancy., Objective: To develop guidelines for the management of thyroid nodules during pregnancy., Methods: We reviewed the cases of 40 pregnant patients with thyroid nodules evaluated during a 10-year period Cytological findings were compared with available histological findings, and concordance rates were determined. The rank sum test was used for statistical analysis., Results: Fine-needle aspirations of thyroid nodules in 62% of patients were benign cytologically (25 patients). Of 8 patients with negative cytological results who had thyroidectomy, all had benign disease histologically (100% concordance rate). Cytological findings of papillary cancer (3 patients) strongly correlated with final histological diagnosis (100% concordance rate), whereas papillary cancer was confirmed histologically in only 2 of 4 patients with cytological findings suspicious for this disease (50% concordance rate). All 3 nodules with cytological findings suspicious for follicular neoplasm were benign adenomas histologically. Of 2 nodules suspicious for Hürthle cell neoplasm, l was Hürthle cell adenoma and the other was Hürthle cell carcinoma (100% concordance rate). Thyroidectomy during the second trimester of pregnancy or the early postpartum period was successful., Conclusions: The approach to thyroid nodules in pregnancy should be similar to that for nonpregnant patients. Thyroidectomy should be performed (1) during the second trimester for malignant lesions and cytological findings suspicious for papillary cancer and (2) in the postpartum period for cytological findings suspicious for follicular neoplasm.

Recent reports have suggested that the HLA alleles DRB3*0101 or DQA1*0501 confer greater susceptibility to Graves' disease than does the DR3 allele. We have reported previously that a non-HLA-linked allele, a polymorphism in codon 52 of the human thyrotropin receptor gene, is highly associated with Graves' disease in females. To determine which of these four susceptibility alleles confers greater independent risk for the development of Graves' disease, we analyzed the alleles in 134 North American Caucasian females who have Graves' disease (n = 69) or are normal controls (n = 65) in a logistic regression model. While we found each of these alleles to be associated with Graves' disease when analyzed independently (corrected p < 0.01 for each of 4 alleles tested), only DR3 (p = 0.0001) and the thyrotropin receptor polymorphism (p = 0.0060) maintained a statistically significant independent association when assessed in conjunction with each of the other alleles in a logistic model. We conclude that DR3 confers the greatest susceptibility to Graves' disease (odds ratio = 7.6) of the alleles within the HLA locus, and that any association between DRB3*0101 or DQA1*0501 and Graves' disease may be a result of the tight linkage disequilibrium between these alleles and DR3. In addition, we found the non-HLA-linked thyrotropin receptor codon 52 polymorphism to confer significant independent risk of Graves' disease (odds ratio = 9.0). Further, because 6 of 6 individuals who possessed both DR3 and the thyrotropin receptor polymorphism had Graves' disease, while no individual in the normal control group possessed both alleles, study of a larger population to assess the potential synergism between these 2 alleles is warranted.

To determine whether T cells infiltrating thyroid, orbital and pretibial tissue of patients with Graves' ophthalmopathy (GO) and pretibial dermopathy (PTD) represent a primary immune response that is directed against certain antigenic determinants shared between these involved tissues, we characterized these T cells at the molecular level. T cell antigen receptor (TcR) variable (V) region gene usage in thyroid, orbital, pretibial tissue and peripheral blood mononuclear cells of patients with GD, GO and PTD was assessed using RT-PCR and 22 V alpha and 23 V beta gene-specific oligonucleotide primers, followed by Southern hybridization analysis using TcR C-region-specific, digoxigenin-labelled oligonucleotide probes. In some instances, CDR3- and junctional regions of TcR V beta genes were sequenced. Marked restriction and similarities of V alpha and V beta gene usage were detected in samples derived from patients with active GO and PTD of recent onset. Moreover, sequence analysis of junctional domains of V beta families revealed oligoclonality of some intrathyroidal, orbital and pretibial T cell populations as well as the presence of conserved junctional motifs shared by T cells derived the thyroid gland and the extrathyroidal sites. These data suggest that similar antigenic determinants may be responsible for the recruitment and oligoclonal expansion of T cells both within the thyroid gland and at the involved extrathyroidal sites in Graves' disease.

It is unknown whether T cells infiltrating the pretibial skin of patients with thyroid-related pretibial dermopathy represent a primary immune response or participate in a nonspecific inflammatory process. To characterize these T cells at the molecular level, we examined the T-cell antigen receptor variable region gene usage in pretibial skin biopsy specimens obtained from patients with early and late stages of pretibial dermopathy and from individuals with unrelated inflammatory conditions of the pretibial skin. RNA extracted from pretibial biopsy specimens and peripheral blood lymphocytes was reverse transcribed and amplified with the polymerase chain reaction and 22 V alpha and 23 V beta gene-specific oligonucleotide primers. The resulting T-cell receptor (TcR) V alpha and V beta transcripts were verified by Southern hybridization analysis using TcR C-region-specific, digoxigenin-labeled oligonucleotide probes. Compared with matched peripheral blood lymphocytes, the pretibial TcR V alpha and V beta gene repertoire expressed was heterogeneous but revealed marked restriction of V alpha and V beta gene usage in samples derived from patients with active inflammatory pretibial dermopathy of recent onset. In contrast, greater diversity of the TcR V alpha gene repertoire and loss of TcR V beta gene restriction were noted in patients with long-standing, clinically inactive pretibial dermopathy. TcR V gene usage in pretibial tissue and peripheral blood lymphocyte samples obtained from control subjects was unrestricted. Limited variability of TcR V gene usage in early pretibial dermopathy may reflect a primary immune response of antigen-specific T lymphocytes infiltrating the pretibial skin in thyroid-related pretibial dermopathy.

We have demonstrated previously and association between a polymorphism in the human thyrotropin receptor gene and an increased prevalence of autoimmune thyroid disease in individuals bearing this polymorphic allele. The polymorphism involves the nucleotide base substitution of a cytosine for the wild-type adenine at the first position of codon 52 and is found generally in the heterozygotic state. Such change results in the substitution of a threonine for the wild-type proline at this position in the receptor protein sequence. The resulting protein would lack a beta turn (at position 52) in a potential loop conformation, and thus would have a significantly altered three-dimensional conformation. The biologic consequences of this conformational change in the receptor are unknown, but may involve altered function or immunogenicity. We report here two individuals with normal thyroid function who are homozygous for the thyrotropin receptor polymorphism, suggesting that the altered receptor is able to respond normally to thyrotropin with respect to the maintenance of the euthyroid state.

Treatment with the antiarrhythmic agent amiodarone results in alterations in thyroid hormone metabolism, and can induce either hypothyroidism or hyperthyroidism (amiodarone-associated thyrotoxicosis, AAT). AAT occurs in patients both with and without preexisting goiter. In our study of the nongoitrous variety, the effect in vitro of amiodarone treatment and of concurrent treatment with potential inhibitors on thyroid cells (FRTL-5) was assessed by measuring the release of radiolabeled chromium (51Cr). In addition, thyroid histopathology was evaluated in autopsy specimens from six amiodarone-treated patients who had no pretreatment evidence of thyroid disease. Histopathologic examination revealed minimal or no evidence of thyroid follicular damage in specimens from amiodarone-treated euthyroid patients (n = 4). In contrast, moderate to severe follicular damage and disruption were present in glands from patients with AAT (n = 2). Studies in vitro showed amiodarone to be cytotoxic to thyroid cells; this effect was inhibited by treatment with dexamethasone (10(-3) mmol) or perchlorate (2.5 micrograms/mL). In summary, we demonstrate evidence in vitro and in vivo of amiodarone-induced thyroid follicular damage and disruption in specimens from patients with nongoitrous AAT and in cultured normal thyroid cells. In addition, we demonstrate inhibition of this effect following treatment in vitro with dexamethasone or perchlorate. Our findings support the concept that nongoitrous (type I) AAT results from direct drug toxicity with disruption of thyroid follicles and subsequent release of preformed thyroid hormone.

Purpose: To examine the signal transduction pathways involved in the activation of orbital fibroblast effector functions relevant to the pathogenesis of Graves' ophthalmopathy (GO). To determine, using antisense technology, whether the c-myc protooncogene is involved in cell proliferation and glycosaminoglycan (GAG) synthesis in cultured orbital fibroblasts (OF)., Methods: The effects of a 16-mer c-myc antisense phosphorothioate oligodeoxynucleotide (S-ODN) on OF monolayers derived from orbital connective tissue of patients with severe GO (n = 6) and healthy individuals (n = 3) were investigated. Quiescent OF monolayers were treated with serum or cytokines and were exposed to increasing concentrations of a c-myc antisense S-ODN and several control S-ODN. Cell proliferation was quantitated by direct cell counting and by immunocytochemistry for the nuclear Ki-67 antigen. Glycosaminoglycan synthesis was examined by [3H] GAG analysis. The effects of the c-myc antisense S-ODN and control S-ODN on c-myc mRNA and protein product levels were analyzed using reverse-transcriptase polymerase chain reaction, immunocytochemistry, and immunoblotting, respectively., Results: Transient suppression of c-myc mRNA and the c-myc protein product by a c-myc antisense S-ODN (2 to 8 microM) strongly inhibited cell proliferation and GAG synthesis in OF derived from patients with GO and healthy individuals. These effects occurred in a dose-dependent manner and were specific for the c-myc antisense S-ODN used. Cell morphology or viability were not affected., Conclusions: The c-myc protooncogene and its protein product are involved in the proliferative and metabolic activities of OF exposed to serum or cytokines in vitro. C-myc appears to be an essential component of at least two OF cellular activities likely to contribute to the orbital tissue alterations in GO.