Novel actions of thyroid hormone.
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Gene Expression↗
Biomedical subjects
L J DeGroot
Publications and source records attributed to L J DeGroot.
T-cell recognition of residue 158-176 in thyrotropin receptor confers risk for development of thyroid autoimmunity in siblings in a family with Graves' disease.
Twenty-two subjects in a family with Graves' Disease and 20 normal subjects unrelated to the family were examined for T-cell responses to rec h TSHR-ECD and its synthetic peptides. Seven of the family members and none of the controls responded positively to rec h TSHR-ECD. Peptide 158-176 was the only residue that showed a high percentage of response among family members, no responses in spouses, and a significant difference compared to unrelated controls. Family members under age of 6 did not differ from spouses in response to rec h TSHR-ECD or any individual peptide. Family members ages 6-12 years were significantly different from spouses in response to peptides 30-49, 158-176, and 172-186. The reactivity of adult family members including 3 Graves' patients was significantly different from spouses in response to peptides 44-62, 132-150, 158-176, and 248-263. The responses of female members of the family were higher than that of the male members and significantly different for peptide 272-291. These data suggest that recognition of peptide 158-176 may be an early event in the pathogenesis of the disease and that recognition of both 158-176 and 248-263 residues may be the cornerstone for establishment of the disease.
Adolescent↗
Plasma thyroid hormone profiles immediately following out-of-hospital cardiac arrest.
Previous studies have shown abnormal thyroid hormone profiles during cardiac arrest. We explored this association further by characterizing plasma thyroid hormone profiles in 473 patients with out-of-hospital cardiac arrest and correlating them with clinical outcomes. Paramedics collected blood at the end of attempted resuscitation regardless of success. Bloods were collected and processed in a similar manner from 18 control subjects randomly selected from the community. Total thyroxine and total triiodothyronine were lower and reverse triiodothyronine and thyrotropin were higher in cardiac arrest patients than control subjects (all p < 0.001). Except for reverse triiodothyronine, findings were similar for a subgroup of cardiac arrest patients considered to be previously healthy (n = 30). Being discharged alive was associated with total thyroxine, total triiodothyronine and reverse triiodothyronine concentrations closer to the control range and thyrotropin concentrations farther from it, namely higher. In a multivariate stepwise model, only total triiodothyronine and thyrotropin were significantly associated with outcome. Whether these profoundly abnormal profiles represent a pre-existing state or a sudden change of thyroid hormone concentrations cannot be answered with this retrospective study. These observations suggest that thyroid hormones may play a role in the etiology of cardiac arrest, its prognosis, or both.
Aged↗
Moderate hypothyroidism in preparation for whole body 131I scintiscans and thyroglobulin testing.
Patients who have undergone thyroidectomy for thyroid carcinoma are frequently subjected to periods of induced severe hypothyroidism in preparation for 131I whole body scanning and measurement of serum TG. These two tests are crucial in evaluating the patient's clinical status and determining administration of 131I or other necessary treatment. Severe hypothyroidism produces fatigue, weight gain, depression, inability to carry out usual activities, and occasionally significant illness. We compared the efficacy of inducing moderate hypothyroidism by cutting replacement therapy in half, to a standard method. In the standard preparation, patients substituted triiodothyronine for thyroxine replacement over a 3-week period, and then omitted hormone therapy for 3 weeks. For the subsequent scan, 6 to 12 months later, the thyroxine dosage was cut in half. TSH levels were assessed 4 weeks later, and if adequately elevated, whole body scanning was conducted at the end of the fifth week. Pulse, weight, clinical symptoms, thyroid hormone levels, and some clinical chemistries were evaluated prior to each scan, and some of the tests were also carried out during the interval between scans. Moderate hypothyroidism induced by the half-dose protocol induced TSH elevations above the target level (25-30 microU/mL) at 5 weeks in most patients. Typically TSH of 15 microU/mL in the previous week predicted adequate elevation of TSH at the time of scan. Half dose therapy can be prolonged, if necessary, especially in patients who begin with extreme suppression of TSH, or if a higher TSH is desired. Pulse, weight gain, and cholesterol were significantly different in the two protocols, and the patient's subjective evaluation of hypothyroid symptoms was significantly reduced. Reduction of thyroxine replacement dosage to half the usual amount, in patients with thyroid cancer, allows after 5 weeks in most patients sufficient elevation of TSH for whole body scanning and measurement of TG levels. This simple and economical procedure drastically reduces symptomatology of hypothyroidism and makes this key procedure much more tolerable to patients.
Adolescent↗
Immunosuppression of thyroiditis.
Immunization of mice with 50 micrograms human thyroglobulin (TG) in complete Freund's adjuvant leads to histological thyroiditis; production of IgG, IgA, and IgM anti-TG antibodies; and in vitro proliferative responses after incubation of lymphocytes with TG. Oral administration of 500 micrograms TG at four intervals before Tg immunization and once afterward causes up to 80% suppression of these responses. The effect is antigen specific and dose dependent. Feeding TG after immunization produces a 40% reduction in responses. We wished to define the mechanism of this antigen-specific oral tolerization. Popliteal lymph nodes (PLN) of orally tolerized animals (T) are reduced in size compared to those in immunized (I) animals not fed TG. PLN and mesenteric lymph nodes (MLN) of I animals produce interleukin-2 (IL-2) and interferon-gamma (IFN gamma) after in vitro incubation with TG, typical of an inflammatory immune response. PLN and MLN of tolerized animals do not proliferate in response to antigen, do not produce IL-2 or IFN gamma, but do not produce the cytokines IL-4 and transforming growth factor-beta (TGF beta). Mixing in vitro of spleen cells from T and I animals causes a reduction in the immune response when incubated with TG, but no reduction in response to purified protein derivative (PPD) (the antigen in complete Freund's adjuvant). When T splenocytes are incubated with TG and PPD together, the response to TG and PPD is suppressed. Partially purified CD8+ cells from tolerized animals produce IL-4 and TGF beta after exposure to human TG and induce suppression, whereas partially purified CD4+ cells produce IL-2 and IFN gamma and do not cause suppression. MLN cells do not proliferate in response to antigen, but do produce inhibitory cytokines. T animals appear to shift the immune response from a Th-1 helper cell subset response to a Th-2 helper cell immunosuppressive response. In this model, oral tolerization produces a dramatic reduction in the immune response. Exposure of MLN to oral TG appears to cause the production of regulatory cells that migrate to spleen and PLN. In vitro studies demonstrate that on exposure to antigen, these regulatory cells produce IL-4 and TGF beta, which suppress all aspects of specific immune responsiveness and nonspecifically suppress other ongoing immune responses (bystander effect). Oral tolerization may include some element of T cell deletion or anergy. This model defines an experimental system with possible relevance to immunosuppression of human autoimmune thyroid disease.
Administration, Oral↗
Transcriptional regulation of human thyroid hormone receptor beta 1 gene expression: effect of human retinoid X receptor and identification of a transcriptional silencer region.
Effects of human retinoid X receptor alpha (hRXR alpha) and its ligand, 9-cis-retinoic acid, on T3-mediated auto-regulation of hTR beta 1 gene expression were examined using a chloramphenicol acetyltransferase (CAT) reporter system, and a deletional analysis of the promoter. hRXR alpha enhanced T3-dependent CAT induction mediated through the proximal (p) TRE in a ligand (9-cis-retinoic acid) independent manner. In a gel mobility shift assay, hRXR alpha enhanced the binding of hTR beta 1 to the pTRE by the formation of hRXR alpha-hTR beta 1 heterodimers. On the other hand, hRXR alpha and 9-cis-retinoic acid did not show any effects on T3-dependent CAT induction mediated through the distal (d) TRE or the binding of hTR beta 1 to the dTRE. A four hundred-base pair (bp) fragment adjacent upstream of the dTRE showed a T3 independent suppressor effect on the function of the pTRE and dTRE. Thus, this region may be an important regulator of the T3 dependent up-regulation of the TR beta 1 gene expression which is observed only under specific conditions.
Base Sequence↗
Absence of association between human spumaretrovirus and Graves' disease.
Graves' disease (GD) is an autoimmune thyroid disease. The etiology of GD is still not clear. Both genetic and environmental factors, such as infectious agents, are believed to be involved in its pathogenesis. Recent findings suggest a role for human spumaretrovirus (HSRV) in the pathogenesis of GD. To test this hypothesis, we looked for the HSRV gag region sequence in DNA extracted from the peripheral blood leukocytes and thyroid tissue of patients with GD, and controls. Genomic DNA was subjected to a highly sensitive nested polymerase chain reaction, followed by dot-blot hybridization with an internal probe. HSRV gag region DNA fragments were detected in the peripheral blood leukocytes of patients with GD and controls to a similar extent; 5.3% (2/38) of Caucasian patients with GD, 4.7% (2/43) of Caucasian controls, 4.7% (2/43) of African-American patients with GD, and 6.5% of (3/46) African-American controls. Similar values were obtained for the samples of thyroid tissues; 5.5% (1/18) of Caucasian patients with GD and 5.0% (1/20) of controls. The differences in all these comparisons were not statistically significant. These results do not support a role for HSRV in the pathogenesis of GD.
Base Sequence↗
Expression of human thyrotropin receptor by recombinant adenovirus.
We developed a new system for expressing a functional human thyrotropin receptor in eukaryotic cells using replication-deficient recombinant human type 5 adenovirus. COS-7 cells infected with recombinant adenovirus encoding human thyrotropin receptor cDNA showed specific thyrotropin binding (Kd = 1.8 x 10(-9) M) and cAMP responses after stimulation by human thyrotropin. Cells infected with control virus encoding firefly luciferase cDNA did not show thyrotropin binding nor cAMP responses following incubation with thyrotropin. This system will be useful for analyzing T cell immunity to thyrotropin receptor in patients with Graves' disease by expressing human thyrotropin receptor in patients' antigen-presenting cells.
Adenoviridae↗
Production of thyroid-stimulating antibodies in mice by immunization with T-cell epitopes of human thyrotropin receptor.
We examined whether mice, immunized with TSH receptor (TSH-R) peptides, which are known to be T-cell epitopes in patients with Graves' disease, would show thyroid-stimulating antibody (TSAb). We immunized DBA/1J mice with TSH-R peptide amino acids 132-150, 145-163, 158-176, and 172-186 and with a pool of these four peptides. The antibodies produced in these mice were evaluated by measurement of TSAb activity using Chinese hamster ovary cells expressing human TSH-R. Seven of 20 mice showed TSAb activity that could be partially blocked with TSH-R peptides. To assess the role of T-cell epitope-specific T-cells in the production of TSAb, we transferred a T-cell line developed from a TSAb-positive mouse to other syngeneic DBA/1J mice. Two of 4 recipient mice showed TSAb activities. These findings suggest that specific T-cell epitopes of TSH-R play a crucial role in the production of TSAb.
Amino Acid Sequence↗
Suppression of development of experimental autoimmune thyroiditis by oral administration of thyroglobulin.
Experimental autoimmune thyroiditis (EAT), which to some extent represents an experimental model of human chronic lymphocytic thyroiditis, is an organ-specific autoimmune disease characterized by autoantibody production to thyroid antigens (Ag) and mononuclear infiltration of the thyroid gland. EAT induced by immunization with human thyroglobulin (hTG) with Freund's adjuvant in CBA/J (H-2K) mice is associated with prominent B and T cell responses. We report that oral administration of hTG effectively reduces the immune responses in EAT in mice in an Ag-specific manner. Both cellular and humoral immune responses are reduced in a dose-dependent manner. Histological evidence of disease is dramatically reduced. Suppression of the immune responses is seen 2 weeks after Ag challenge, with partial inhibition of proliferative and antibody responses. Six weeks after immunization, further inhibition is observed of both T and B cell responses. Hyporesponsiveness of T and B cell reactivity is seen only to hTG; T and B cell responses to other immunogens are not affected, including purified protein derivative and the nonrelated Ag BSA. This model may provide the basis for immunotherapy of autoimmune thyroid diseases in man.
Administration, Oral↗
T-cell reactivity to recombinant human thyrotropin receptor extracellular domain and thyroglobulin in patients with autoimmune and nonautoimmune thyroid diseases.
Grave's disease and Hashimoto's thyroiditis are common organ-specific disorders characterized by an immune response toward a number of thyroid proteins, including TSH receptor (TSHR), thyroid peroxidase, and thyroglobulin (Tg). Although considerable progress has been made in understanding and mapping the autoantibody response to TSHR, much less is known about recognition of TSHR by pathogenic T-cells in human disease. To identify such reactions, we analyzed the T-cell proliferative responses of peripheral blood lymphocytes (PBMC) to human recombinant TSHR extracellular domain (hrecTSHR-ECD amino acids 19-417) expressed in Escherichia coli and to Tg. Forty-two patients with autoimmune thyroid disease (AITD), 13 patients with non-AITD, and 20 normal subjects were studied. PBMC from 40% of patients with AITD and 46% of patients with non-AITD reacted significantly to hrecTSHR-ECD. The reactivity to Tg was less than that to TSHR-ECD in both groups. Five percent of normal subjects showed a response to hrecTSHR-ECD and none to Tg. TSHR-specific T-cell lines were developed in 16 of 26 AITD patients and 3 of 10 non-AITD patients. CD8-positive T-cell depletion from PBMC of 8 patients with AITD by the indirect panning method did not enhance the reactivity to hrecTSHR-ECD, except in 1 patient. We conclude that TSHR-specific T-cells are present in the circulation of patients with AITD and are presumably involved in the pathogenesis of thyroid autoimmunity. The lower, but positive, reactivity to hrecTSHR-ECD found in patients with non-AITD was unexpected and may be related to lymphocytic infiltrates in the thyroid of 7 of the 11 patients.
Adult↗
CTLA-4 gene polymorphism associated with Graves' disease in a Caucasian population.
Graves' disease (GD) is an autoimmune thyroid disease. Multiple genetic factors are believed to be involved in its pathogenesis, but the factors are largely unknown, except for sex (female disease preponderance) and the role of human leukocyte antigen (HLA) genes on chromosome 6. To understand the mechanisms underlying the development of GD, a search for non-HLA-linked genes is crucial, and we tested several candidate genes, including the CTLA-4 gene on chromosome 2q33. CTLA-4 molecules may either facilitate or down-regulate the second signal to T-cells, which is provided by the interaction between the two accessory molecules CD28 and B7. One hundred and thirty-three Caucasian patients (26 males) with GD and 85 local controls were included in this study. Polymerase chain reaction was used to amplify DNA containing the (AT)n repeat within the 3'-untranslated region of exon 3 of the CTLA-4 gene. The 5'-forward primer was radiolabeled, and amplified products were resolved on 5-7% sequencing gels. All subjects were previously typed for HLA class II alleles. Twenty-one alleles were observed with sizes ranging from 88-134 basepairs. In the association analysis, the genotype frequencies between GD patients and controls differed significantly (P = 0.012), and the difference was attributable to a higher frequency of the 106-basepair allele among patients (relative risk, 2.82). When the patients were subdivided with respect to sex and HLA, the phenotype frequencies of allele 106 was higher in the female patients with protective HLA specificities (DQA1*0201 positive/DQA1*0501 negative) than in those with susceptible HLA specificities (DQA1*0201 negative/DQA1*0501 positive; 81.8% vs. 45.5%; P = 0.026). The CTLA-4 gene or a closely associated gene (including CD28) confers susceptibility to GD. This association may be more important in female patients with protective HLA specificities, who otherwise would be at low risk of developing the disease.
Abatacept↗
Graves' disease in severe combined immunodeficient mice.
Graves' disease (GD) is an autoimmune thyroid disorder involving an antibody (TSAb) directed against the TSH receptor (TSHR) producing thyroid stimulation. We have developed an animal model of GD by engrafting peripheral blood mononuclear cells or T cell lines plus autologous thyroid tissue into severe combined immunodeficient (SCID) mice. We xenografted Graves' thyroid tissue from six patients into six groups of SCID mice. Autologous PBMC and T cell lines reactive to recombinant human TSHR extracellular domain and non-TSHR lines were injected ip into the designated groups. In some of the studies, thyroid tissue was irradiated with 2000 rads before xenografting. Irradiation of xenografts induced thyroid tissue damage and release of thyroid antigens and hormones. Mice reconstituted with peripheral blood mononuclear cells or nonspecific T cell lines did not simulate GD. However, we achieved production of TSAb, elevation of serum T3, and TSAb-dependent survival and function of human Graves' thyroid tissue in SCID mice reconstituted with TSHR-specific T cell lines. We reconstituted SCID mice with PBMC and TSHR-specific T cell lines that recognized TSHR peptide 158-176. This may be in vivo evidence of the importance of peptide 158-176 as an immunodominant epitope on the TSHR extracellular domain.
Adult↗
Morbidity and mortality in follicular thyroid cancer.
The natural history and results of treatment have been analyzed in a group of 49 patients with follicular thyroid carcinoma who were followed for an average of 10.7 yr. Striking differences between the course of follicular thyroid carcinoma and the course of papillary carcinoma are evident. Deaths from cancer were double (16% for follicular), age at diagnosis was older, and age at death was younger. All deaths and recurrences happened within 13 yr, in contrast to the continued experience of deaths and recurrences in papillary cancer, even through 40 yr of observation. Adverse outcome correlated with extent of disease at diagnosis and with size of primary tumor, but did not correlate with vessel invasion, extent of capsule invasion, degree of dedifferentiation, extent of primary surgery, or radioactive iodide ablation. These observations are again in striking contrast to experience with papillary cancer. No patient with intrathyroidal disease who was under age 45 at diagnosis and with a primary tumor of less than 2.5 cm died. Our observations suggest that follicular cancer, even if apparently intrathyroidal, carries a high mortality rate in patients over age 45 or in those with tumors larger than 2.5 cm at the time of diagnosis and suggest that we must consider additional therapeutic measures in this group of patients, including larger radioiodine doses for initial therapy, external radiotherapy, and even possibly prophylactic chemotherapy.
Adenocarcinoma, Follicular↗
Functional analysis of a proline to serine mutation in codon 453 of the thyroid hormone receptor beta 1 gene.
Mutations in the gene encoding human thyroid hormone receptor beta (hTR beta) have been associated with generalized resistance to thyroid hormone (GRTH). This disorder is associated with significant behavioral abnormalities. We examined the hTR beta gene in a family with members who manifest inappropriately normal TSH, elevated free T4, and free and total T3. Sequence analysis showed a cytosine to thymine transition at nucleotide 1642 in one allele of the index patient's genomic DNA. This altered proline to serine at codon 453. The resulting mutant receptor when expressed in vitro bound DNA with high affinity, but the T3 affinity of the receptor was impaired. The mutant TR demonstrated a dominant negative effect when cotransfected with two isoforms of wild-type receptor and also in the presence of TR variant alpha 2 in COS-1 cells. Mutations of codon 453 occur more frequently than at other sites, and four different amino acid substitutions have been reported. Significant differences in phenotype occur among affected individuals, varying from normality to moderately severe GRTH. There is no clear correlation between Ka or in vitro function of the mutant receptor, and phenotype. This study extends the association between GRTH and illness, and indicates that early diagnosis and counseling are needed in families with TR beta 1 abnormalities.
Adult↗
Therapeutic controversies. Retro-orbital radiation and radioactive iodide ablation of the thyroid may be good for Graves' ophthalmopathy.
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Graves Disease↗
T-cells recognize multiple epitopes in the human thyrotropin receptor extracellular domain.
In Graves' disease (GD), the TSH receptor (TSHR) is believed to be the major target of an autoimmune response. T-Lymphocytes regulate the immune system. To assess the interaction of T-cells with TSHR in the pathogenesis of GD, we tested the T-cell response of peripheral blood mononuclear cells and T-cell lines to the recombinant human TSHR extracellular domain (rhTSHR-ECD) and 31 synthetic peptides corresponding to the entire TSHR-ECD in 20 patients with GD, 8 patients with Hashimoto's thyroiditis, 7 with colloid nodular goiter (CNG), and 20 normal controls. Comparing patients from different groups with normal subjects, there was a significant response to rhTSHR-ECD and thyroglobulin in GD patients (P < 0.001) and HT patients (P < 0.05), but not in CNG patients (P > 0.1). All 20 patients with GD responded to at least one peptide. The reactivity in GD patients was heterogeneous and spanned the entire TSHR-ECD. However, the reactivity was significantly different from that in controls for peptide regions 44-88, 119-176, 227-263, and 343-376, and the stimulation index (SI) values were significantly different for peptides 272-291 and 301-320. Significant differences were confined to peptides 158-176 and 343-362 and the region 227-263 for comparison of the number of positive responses in patients and controls to individual peptides. Forty-six percent of human leukocyte antigen-DQA1 0501 allele-positive Graves' patients responded to peptides 158-176 and 248-263 (SI = 3 or more) compared to 14% of allele-negative patients. In HT and CNG patients, the response was mainly to peptides in the carboxy-terminal half of the TSHR-ECD. Concordance of the reactivity in T-cell lines and peripheral blood mononuclear cells was observed in 36% of direct comparisons in GD. Eighty-five percent and 90% of GD patients were positive for microsomal antibody and TSHR antibody, respectively, and 59% of microsomal antibody-positive and 67% of TSHR antibody-positive patients responded to rhTSHR-ECD (SI = 2 or more). However, there was no significant correlation between antibody-positive patients and reactivity to specific peptides. Using multiple criteria to define immunodominance, peptides 158-176, 237-252, 248-263, and 343-362 seem to be important epitopes and may be critical for T-cell triggering in GD.
Adult↗
Proliferative responses of T-cells to thyroid antigens and synthetic thyroid peroxidase peptides in autoimmune thyroid disease.
We studied the immune responses of 33 patients with autoimmune thyroid disease (AITD; including 17 with Hashimoto's thyroiditis and 16 with Graves' disease), 5 patients with non-AITD, 12 control subjects (CS), and 2 subjects with a family history of autoimmunity to the main thyroid antigens. These antigens included thyroid peroxidase (TPO), thyroglobulin (Tg), TSH receptor (TSH-R), and 13 overlapping TPO peptides. T-cell lines (TCL) were isolated from peripheral blood mononuclear cells (PBMC) after incubation with TPO, Tg, or a protein derivative of tuberculin (PPD). PBMC and TCL were used in a 3- to 5-day microproliferation assay. Peripheral lymphocytes from most AITD patients responded with a stimulation index of 3 or more to TPO, Tg, and/or TSH-R (60-88%) as well as to two or more TPO peptides. Lymphocytes from 3 of 5 patients with non-AITD and 2 subjects with a family history of autoimmunity were also reactive to thyroid antigens. TPO TCL showed a high proliferative response to TPO and its peptides, whereas Tg TCL were less reactive and PPD TCL were nonreactive to these antigens. Six of the 13 peptides tested produced highly significant stimulation in PBMC (CS, 0-17%; AITD, 60-92%) and TPO TCL (73-91%). The amino acid sequences of these putative epitopes were located in TPO regions 100-119, 211-223, 261-275, 420-434, 625-644, and 882-901. These results demonstrate T-cell responses to the main thyroid antigens, including TPO, Tg, and TSH-R, and confirm the heterogeneity of TPO T-cell epitopes in patients with AITD. Amino acid residues 100-119, 420-434, 625-644, and 882-901 are the most common sites recognized by TPO TCL, indicating that they may be immunogenic epitopes in AITD.
Adult↗