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Ogiwara T, Araki O, Morimura T, Tsunekawa K, Mori M, Murakami M. A novel mechanism for the inhibition of type 2 iodothyronine deiodinase by tumor necrosis factor α: involvement of proteasomal degradation. Endocr J 2013; 60:1035-45. [PMID: 23719846 DOI: 10.1507/endocrj.ej11-0144] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Thyroxine (T₄) needs to be converted to 3,5,3'-triiodothyronine (T₃) by iodothyronine deiodinase to exert its biological activity. Recent studies revealed the presence of type 2 iodothyronine deiodinase (D2) in human thyroid tissue, human skeletal muscle and other tissues, suggesting that D2 is involved in maintaining plasma T₃ level in human. Tumor necrosis factor α (TNFα) is an inflammatory cytokine of which production is elevated in patients with nonthyroidal illness. Although several lines of evidence suggest the causal role of TNFα in nonthyroidal illness, detailed nature of the effect of TNFα on D2 remains unclear. In the present study, we identified D2 activity and D2 mRNA in TCO-1 cells, which were derived from human anaplastic thyroid carcinoma, and studied the mechanisms involved in the regulation of D2 expression by TNFα. The characteristics of the deiodinating activity in TCO-1 cells were compatible with those of D2 and Northern analysis demonstrated that D2 mRNA was expressed in TCO-1cells. D2 activity and D2 mRNA expression were rapidly increased by dibutyryl cAMP ((Bu)₂cAMP). TNFα showed an inhibitory effect on (Bu)₂cAMP-stimulated D2 activity in spite of little effect on (Bu)₂cAMP-stimulated D2 mRNA expression. MG132, a proteasome inhibitor abolished TNFα suppression of D2 activity whereas BAY11-7082 or 6-amino-4-(4-phenoxyphenylethylamino) quinazoline, inhibitors of nuclear factor-κB (NF-κB) failed to attenuate the effect of TNFα on D2 activity. These data suggest that a posttranslational mechanism through proteasomal degradation but not NF-κB activation is involved in the suppression of D2 by TNFα.
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Monzani A, Moia S, Prodam F, Walker GE, Bellone S, Petri A, Bona G. A novel familial variation of the thyroid hormone receptor beta gene (I276N) associated with resistance to thyroid hormone. Thyroid 2012; 22:440-1. [PMID: 22360271 DOI: 10.1089/thy.2011.0443] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Ehlers M, Thiel A, Bernecker C, Porwol D, Papewalis C, Willenberg HS, Schinner S, Hautzel H, Scherbaum WA, Schott M. Evidence of a combined cytotoxic thyroglobulin and thyroperoxidase epitope-specific cellular immunity in Hashimoto's thyroiditis. J Clin Endocrinol Metab 2012; 97:1347-54. [PMID: 22259066 DOI: 10.1210/jc.2011-2178] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
CONTEXT Hashimoto's thyroiditis (HT) is a common autoimmune disease leading to thyroid destruction due to lymphocytic infiltration. Only rare data are available regarding the recognition of specific cellular antigens, e.g. of thyroperoxidase (TPO) and thyroglobulin (Tg). OBJECTIVE The aim of this study was to quantify and characterize TPO- and Tg-epitope-specific CD8-positive T cells of HT patients. DESIGN Six different human leukocyte antigen (HLA)-A2 restricted, TPO- or Tg-specific tetramers were synthesized and used for measuring CD8-positive T cells in HT patients and controls. RESULTS The frequency of peripheral TPO- and Tg-specific CD8-positive T cells was significantly higher in HLA-A2-positive HT patients (2.8 ± 9.5%) compared with HLA-A2-negative HT patients (0.5 ± 0.7%), HLA-A2-positive nonautoimmune goiter patients (0.2 ± 0.4%), and HLA-A2-positive healthy controls (0.1 ± 0.2%). The frequency of Tg-specific T cells (3.0%) was very similar to those of TPO-specific CD8-positive T cells (2.9%). Subgroup analyses revealed a steady increase of the number of epitope-specific CD8-positive T cells from 0.6 ± 1.0% at initial diagnosis up to 9.4 ± 18.3% in patients with long-lasting disease. Analyses of the number of thyroid-infiltrating cells as well as the cytotoxic capacity revealed a similar picture for TPO- and Tg-specific T cells. CONCLUSION We here report for the first time that both antigens, TPO and Tg, are recognized by CD8-positive T cells and are involved in the thyroid destruction process leading to clinical disease manifestation.
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Gierach M, Gierach J, Skowrońska A, Rutkowska E, Spychalska M, Pujanek M, Junik R. Hashimoto's thyroiditis and carbohydrate metabolism disorders in patients hospitalised in the Department of Endocrinology and Diabetology of Ludwik Rydygier Collegium Medicum in Bydgoszcz between 2001 and 2010. ENDOKRYNOLOGIA POLSKA 2012; 63:14-17. [PMID: 22378092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
INTRODUCTION Chronic lymphocytic thyroiditis, also known as Hashimoto's thyroiditis, is the most frequent type of thyroiditis. An average of 2% of the population have the disease. It occurs in all age groups, also in children. The main cause of the disease are autoimmune disorders, which results in incresed risk of suffering from type 1 diabetes. Fourthermore, during the course of Hashimoto's thyroiditis, hypothyroidism may cause carbohydrate metabolism disorders. Aim of our study was estimate disturbances of glycaemia in patients with recognized Hashimoto's thyroiditis, hospitalized in Endokrinology and Diabetology Depatment of Collegium Medicum University of Nicolaus Copernicus in Bydgoszcz in years 2001-2010. MATERIAL AND METHODS We examined 54 patients with the diagnosis of Hashimoto thyroiditis based on clinical picture and examination(autoantibodies anti-TPO and anti-Tg). RESULTS In the tested group with Hashimoto's thyroiditis, diabetes has been confirmed in 27.8% of the patients; impaired fasting glycaemia (IFG) or impaired glucose tolerance (IGT) occurred in 16.6%, whereas a normoglycaemia has been confirmed in 55.6% of the pacients. An average age of the patients with Hashimoto's thyroiditis and diabetes at the same time, was 53 years. The patients in which we confirmed the impaired fasting glycaemia or impaired glucose tolerance were on average 49.9 years old. An average age of the patients without any carbohydrate methabolism disorders was on average 43.1 years. CONCLUSIONS Carbohydrate metabolism disorders in the form of type 1 diabetes connected with an autoimmune process, as well as type 2 diabetes connected with the increase of the insulin resistance, occured in average of half of the patients with Hashimoto's thyroiditis.
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Huang MP, Rodgers KA, O'Mara R, Mehta M, Abuzahra HS, Tannenbaum AD, Persons K, Holick MF, Safer JD. The thyroid hormone degrading type 3 deiodinase is the primary deiodinase active in murine epidermis. Thyroid 2011; 21:1263-8. [PMID: 21936673 DOI: 10.1089/thy.2011.0105] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
INTRODUCTION Many tissues express thyroid hormone metabolizing deiodinases that both activate and inactivate thyroid hormones through conversion processes. Many believe that the primary role of thyroid hormone deiodinases is the activation of the prohormone thyroxine (T(4)) to the active hormone triiodothyronine because athyreotic humans can be treated with T(4) alone. In our hands a nonspecific deiodinase inhibitor (iopanoic acid [IOP]) decreased cutaneous cell proliferation in vitro, so we hypothesized that topical IOP would inhibit epidermal proliferation in vivo. METHODS IOP was applied topically to mice. Treatments were applied daily for 1 week. Skin biopsies were either stained for 5-bromo-2-deoxyuridine or flash-frozen to assay for deiodinase activity. RESULTS Topical IOP resulted in a dose-dependent increase in epidermal proliferation. Assay revealed significant inactivating type 3 deiodinase (Dio3) activity in the epidermis but little or no activating (Dio1 or Dio2) activity. Dio3 activity was decreased 44%±21% in epidermis from mice treated with low-dose IOP and 80%±4% in epidermis from mice treated with high-dose IOP (p<0.001). CONCLUSION We hypothesize that keratinocytes express Dio3 in vivo to maintain cutaneous health and prevent the skin from becoming hyperproliferative. Our data support the developing recognition that the primary role of thyroid hormone deiodinases in some tissues may be the degradation of thyroid hormone to protect the tissue against thyrotoxicosis.
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Belevich VK, Senchuk VV. [Biochemical characteristics of iodperoxidase activity of human saliva]. BIOMEDITSINSKAIA KHIMIIA 2011; 57:187-194. [PMID: 21870604 DOI: 10.18097/pbmc20115702187] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Peroxidase-catalyzed oxidation of iodide in human saliva leads to the formation of a brown product with lambda max 287 nm and 353 nm (I3-) identified by the method of UV-spectrophotometry. I3- directly reacts with starch producing the characteristic blue complex. Salivary iodide peroxidase activity was found to be from 1.2 to 2.3 times higher then the activity of salivary peroxidases with natural substrates (SCN- and Cl-). Optimum for the iodide peroxidase activity in human saliva was found to be near pH 5.8. Salivary iodide peroxidase activity progressively lowers with the rise of pH value of the reaction mixture until total loss at the pH>7.4 was observed. Iodide peroxidase activity in human saliva at pH>7.4 is masked due to decomposition of I3- with the increase of pH along with the inhibition of peroxidases and I3- reduction by low molecular weight dialyzable salivary components possibly by Cl- and NCS-. Salivary iodide peroxidase activity was completely inhibited by peroxidase inhibitors (NaN3, 2-mercaptoethanol, thiourea), while addition of the peroxidase alternative substrates (ascorbate, quercetin, thiocyanate) resulted in partial inhibition of iodide peroxidase activity. The results of the study confirm the idea, that high activity of human saliva peroxidase with iodide as a substrate may play a crucial role in the bioavailability and metabolism of biologically active iodide.
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Jiskra J, Bartáková J, Holinka Š, Límanová Z, Springer D, Fait T, Antošová M, Telička Z, Potluková E. Low concordance between positive antibodies to thyroperoxidase and thyroid ultrasound autoimmune pattern in pregnant women. Endocr J 2011; 58:849-59. [PMID: 21873803 DOI: 10.1507/endocrj.ej11-0026] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
The diagnostic and prognostic role of thyroid ultrasound (TUS) in pregnant women positive for antibodies to thyroperoxidase (TPOAb) is unclear. The aim of our study was to compare the relation of ultrasound thyroid texture to the thyroid laboratory tests in pregnant women and controls. Using a semi-quantitative assessment we compared TUS in two groups of women with positive TPOAb and/or with thyroid dysfunction (TSH out of 0.06-3.67 mIU/L): 186 women in 1(st) trimester of pregnancy recruited from universal screening and 67 asymptomatic age-comparable non-pregnant non-postpartum women recruited from screening of general population (controls). Women with previous history of thyroid diseases were excluded. Only 64/131 (48.9 %) of TPOAb-positive pregnant women were TUS-positive (TUS with autoimmune pattern) in comparison with 35/49 (71.4 %) TPOAb-positive controls (p <0.011). Pregnant women had more often TSH >10.0 mIU/L if they were TPOAb-positive/TUS-positive as compared to those TPOAb-positive/TUS-negative (8/64 (12.5 %) vs. 0/67 (0 %), p = 0.009). The prevalence of preterm deliveries among TPOAb-positive women was significantly lower if TPOAb-positivity was not accompanied by TUS-positivity (2/67 (3.0 %) vs. 10/64 (15.6 %) in TPOAb-positive/TUS-positive women, p = 0.028). In conclusion, nearly half of the TPOAb-positive pregnant women did not have an autoimmune pattern in TUS. Normal TUS image in TPOAb-positive pregnant women might be a protective factor for preterm delivery.
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Rosene ML, Wittmann G, Arrojo e Drigo R, Singru PS, Lechan RM, Bianco AC. Inhibition of the type 2 iodothyronine deiodinase underlies the elevated plasma TSH associated with amiodarone treatment. Endocrinology 2010; 151:5961-70. [PMID: 20926587 PMCID: PMC2999495 DOI: 10.1210/en.2010-0553] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2010] [Accepted: 09/07/2010] [Indexed: 01/10/2023]
Abstract
The widely prescribed cardiac antiarrhythmic drug amiodarone (AMIO) and its main metabolite, desethylamiodarone (DEA), have multiple side effects on thyroid economy, including an elevation in serum TSH levels. To study the AMIO effect on TSH, mice with targeted disruption of the type 2 deiodinase gene (D2KO) were treated with 80 mg/kg AMIO for 4 wk. Only wild-type (WT) mice controls developed the expected approximate twofold rise in plasma TSH, illustrating a critical role for D2 in this mechanism. A disruption in the D2 pathway caused by AMIO could interfere with the transduction of the T4 signal, generating less T3 and softening the TSH feedback mechanism. When added directly to sonicates of HEK-293 cells transiently expressing D2, both AMIO and DEA behaved as noncompetitive inhibitors of D2 [IC(50) of >100 μm and ∼5 μm, respectively]. Accordingly, D2 activity was significantly decreased in the median eminence and anterior pituitary sonicates of AMIO-treated mice. However, the underlying effect on TSH is likely to be at the pituitary gland given that in AMIO-treated mice the paraventricular TRH mRNA levels (which are negatively regulated by D2-generated T3) were decreased. In contrast, AMIO and DEA both exhibited dose-dependent inhibition of D2 activity and elevation of TSH secretion in intact TαT1 cells, a pituitary thyrotroph cell line used to model the TSH feedback mechanism. In conclusion, AMIO and DEA are noncompetitive inhibitors of D2, with DEA being much more potent, and this inhibition at the level of the pituitary gland contributes to the rise in TSH seen in patients taking AMIO.
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Walpita CN, Crawford AD, Darras VM. Combined antisense knockdown of type 1 and type 2 iodothyronine deiodinases disrupts embryonic development in zebrafish (Danio rerio). Gen Comp Endocrinol 2010; 166:134-41. [PMID: 19800339 DOI: 10.1016/j.ygcen.2009.09.011] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/29/2009] [Revised: 09/18/2009] [Accepted: 09/25/2009] [Indexed: 02/04/2023]
Abstract
Thyroid hormones (THs) are important regulators of gene expression during vertebrate development. In teleosts, early embryos rely on the maternal TH deposit in the egg yolk, consisting predominantly of T(4). Activation of T(4) to T(3) by iodothyronine deiodinases (Ds) may therefore be an important factor in determining T(3)-dependent development. In zebrafish, both Ds capable of T(3) production, D1 and D2, are first expressed very early during embryonic development. We sought to determine their relative importance for zebrafish embryonic development by inhibiting their expression via antisense oligonucleotides against D1 and D2, and by a combined knockdown of both deiodinases. The impact of these treatments on the rate of embryonic development was estimated via three morphological indices: otic vesicle length, head-trunk angle and pigmentation index. Knockdown of D1 alone seemed not to affect developmental progression. In contrast, D2 knockdown resulted in a clear developmental delay in all parameters scored, suggesting that D2 is the major contributor to TH activation in developing zebrafish embryos. Importantly, combined knockdown of D1 and D2 caused not only a more pronounced developmental delay than D2 knockdown alone but also the appearance of dysmorphologies in a substantial minority of treated embryos. This shows that although D1 may not be essential in euthyroid conditions, it may be crucial under depleted thyroid status as is the case when T(3) production by D2 is inhibited. These results indicate that zebrafish embryos are dependent on T(4) uptake and its subsequent activation to T(3), and suggest that substantial inhibition of embryonic T(4) to T(3) conversion reduces intracellular T(3) availability below the threshold level necessary for normal development.
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Abstract
Common environmental exposures may affect thyroid function in humans. Foetuses and infants are most vulnerable to these effects because they need thyroid hormone for normal neurodevelopment. Perchlorate, thiocyanate and nitrate are all competitive inhibitors of the sodium/iodine symporter (NIS) in pharmacologic doses, but their effects on human thyroid function at environmental exposure levels remain unclear. Many compounds, including polychlorinated biphenyls (PCBs), polybrominated diphenylethers (PBDEs), bisphenol-A (BPA) and triclosan, may have direct actions on the thyroid hormone receptor, but these effects are complex and are not yet well understood. Isoflavones inhibit thyroperoxidase (TPO) activity, and, therefore, may cause goitre and hypothyroidism if ingested at high levels, particularly in iodine-deficient individuals. Organochlorine pesticides and dioxins may decrease serum T(4) half-life by activating hepatic enzymes. Additional studies are needed to further elucidate the risk posed by these and other potentially thyroid-disrupting compounds.
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Gómez JJL, Pomar MDB, Casariego AV, Rodríguez IC. [Selective pituitary resistance to thyroid hormone in a patient treated with amiodarone]. ENDOCRINOLOGIA Y NUTRICION : ORGANO DE LA SOCIEDAD ESPANOLA DE ENDOCRINOLOGIA Y NUTRICION 2009; 56:418-421. [PMID: 19959152 DOI: 10.1016/s1575-0922(09)72712-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2009] [Accepted: 09/02/2009] [Indexed: 05/28/2023]
Abstract
Selective pituitary resistance to thyroid hormones is a syndrome that involves inadequate response of thyroid-stimulating hormone to changes in thyroid hormones. Unlike generalized resistance syndromes, this entity produces central hyperthyroidism and clinical thyrotoxicosis. Sometimes the disease may not be properly diagnosed and is treated with drugs with harmful effects on the thyroid, such as amiodarone, hampering diagnosis and possibly exacerbating the disorder. The treatment of this condition can be symptomatic, based on control of tachycardia and anxiety, or etiological, acting on the pituitary to regulate thyrotropin secretion or on the thyroid gland to control thyroid hormone production. We report the case of a patient with pituitary resistance to thyroid hormone, who was treated with amiodarone to control paroxysmal atrial fibrillation.
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Lim CF, Loidl NM, Kennedy JA, Topliss DJ, Stockigt JR. Drug effects on triiodothyronine uptake by rat anterior pituitary cells in vitro. Exp Clin Endocrinol Diabetes 2009; 104:151-7. [PMID: 8740939 DOI: 10.1055/s-0029-1211437] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
In nonthyroidal illness, numerous drugs such as glucocorticoids, dopamine, fenclofenac, furosemide and diphenylhydantoin may modify the close inverse-feedback relationship between circulating thyroid hormones and TSH. Such effects could involve altered hypothalamic TRH secretion, a direct effect on TSH production by the thyrotroph, alterations in circulating free thyroid hormone concentrations, or changes in thyroid hormone uptake by the thyrotroph. We therefore examined the effect of nonsteroidal antiinflammatory drugs (NSAID), diuretics, the synthetic flavonoid EMD 21388, and diphenylhydantoin, on [125I]T3 cellular uptake in rat pituitary primary cell cultures. Uptake of [125I]T3 (cell-associated counts of washed cells) was measured at 15 min after the addition of 50 pmol/L [125I]T3 in protein-free medium (37 degrees C, pH 7.4). Uptake of [125I]T3 by pituitary cells was 6.0 +/- 1.7% of total counts (mean +/- SD, n = 18). Unlabeled T3 (10 mumols/L) displaced 92% of total uptake. The IC50 of unlabeled T3 for the displacement of [125I]T3 was 1.2 mumols/L. T4 and rT3 were approximately 10% as effective as T3 itself in inhibiting [125I]T3 uptake, while triac did not affect cellular [125I]T3 uptake. Inhibition of [125I]T3 uptake at drug concentrations of 100 mumols/L was seen with the diuretics, furosemide (9%), bumetanide (14%), piretanide (12%) and ethacrynic acid (76%), the NSAID, meclofenamic acid (35%) and fenclofenac (52%), EMD 21388 (49%), and the anticonvulsant, diphenylhydantoin (23%). Aspirin, up to 500 mumols/L, had no effect on [125I]T3 uptake. Our results indicate that ethacrynic acid, meclofenamic acid, fenclofenac, EMD 21388 and diphenylhydantoin affect plasma membrane T3 uptake in the pituitary. This potential influence on TSH release will be contrary to the previously-demonstrated direct inhibitory effect of these drugs on TSH release.
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Heemstra KA, Soeters MR, Fliers E, Serlie MJ, Burggraaf J, van Doorn MB, van der Klaauw AA, Romijn JA, Smit JW, Corssmit EP, Visser TJ. Type 2 iodothyronine deiodinase in skeletal muscle: effects of hypothyroidism and fasting. J Clin Endocrinol Metab 2009; 94:2144-50. [PMID: 19293265 DOI: 10.1210/jc.2008-2520] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
CONTEXT The iodothyronine deiodinases D1, D2, and D3 enable tissue-specific adaptation of thyroid hormone levels in response to various conditions, such as hypothyroidism or fasting. The possible expression of D2 mRNA in skeletal muscle is intriguing because this enzyme could play a role in systemic as well as local T3 production. OBJECTIVE We determined D2 activity and D2 mRNA expression in human skeletal muscle biopsies under control conditions and during hypothyroidism, fasting, and hyperinsulinemia. DESIGN This was a prospective study. SETTING The study was conducted at a university hospital. PATIENTS We studied 11 thyroidectomized patients with differentiated thyroid carcinoma (DTC) on and after 4 wk off T4( replacement and six healthy lean subjects in the fasting state and during hyperinsulinemia after both 14 and 62 h of fasting. MEAN OUTCOME MEASURES D2 activity and D2 mRNA levels were measured in skeletal muscle samples. RESULTS No differences were observed in muscle D2 mRNA levels in DTC patients on and off T4 replacement therapy. In healthy subjects, muscle D2 mRNA levels were lower after 62 h compared to 14 h of fasting. Insulin increased mRNA expression after 62 h, but not after 14 h of fasting. Skeletal muscle D2 activities were very low and not influenced by hypothyroidism and fasting. CONCLUSION Human skeletal muscle D2 mRNA expression is modulated by fasting and insulin, but not by hypothyroidism. The lack of a clear effect of D2 mRNA modulation on the observed low D2 activities questions the physiological relevance of D2 activity in human skeletal muscle.
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Safer JD, Persons K, Holick MF. A thyroid hormone deiodinase inhibitor can decrease cutaneous cell proliferation in vitro. Thyroid 2009; 19:181-5. [PMID: 19191748 DOI: 10.1089/thy.2008.0227] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
BACKGROUND Although cutaneous manifestations associated with thyroid dysfunction are classic, the potential for thyroid hormone or its antagonists to treat dermatological disease has not been explored with rigor. The predominant circulating thyroid hormone is the pro-hormone, thyroxine (T(4)). Skin, like many tissues, expresses thyroid hormone deiodinases to convert T(4) to the active thyroid hormone, triiodothyronine (T(3)). Previously, we determined that T(3) is necessary for optimal growth of keratinocytes and fibroblasts. The first hypothesis of this experiment was that the deiodinase inhibitor iopanoic acid (IOP) could inhibit cutaneous cell proliferation. The second hypothesis of this experiment was that the action of IOP could be attributed to its inhibition of conversion of T(4) to T(3). Although IOP is known to inhibit T(4) to T(3) conversion, the inhibition of cutaneous cell proliferation by IOP might conceivably result from other properties of IOP. METHODS In separate experiments, primary culture human keratinocytes and dermal fibroblasts were incubated overnight with IOP. RESULTS Proliferation was inhibited in a dose-dependent manner in both cell lines. Overnight incubation with T(3) restored the proliferation but overnight incubation with T(4) did not. CONCLUSION The study is the first to demonstrate that IOP inhibits cutaneous cell proliferation and that supplemental T(3) is sufficient to correct at least part of the inhibition caused by IOP. The data suggest that IOP decreases cutaneous cell proliferation by inhibition of intracellular T(4) to T(3) conversion. The data provide indirect evidence of the presence of type 1 or type 2 iodothyronine deiodinase activity in skin cells. The data support our previous hypothesis that T(3) is necessary for normal cutaneous proliferation.
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Palazzolo DL, Jansen KP. The minimal arsenic concentration required to inhibit the activity of thyroid peroxidase activity in vitro. Biol Trace Elem Res 2008; 126:49-55. [PMID: 18685814 DOI: 10.1007/s12011-008-8183-y] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/18/2008] [Accepted: 06/12/2008] [Indexed: 10/21/2022]
Abstract
Arsenical compounds are known to interfere with normal thyroid function. Therefore, we designed an experiment to determine the minimal concentration of arsenic trioxide (As2O3) required to inhibit thyroid peroxidase (TPO) activity in vitro. The activity of commercially prepared human TPO was assayed spectrophotometrically in the absence (control) or presence of arsenic (0.1, 1.0, 5.0, and 10 ppm) during a 10-min incubation period. The results of this study indicate a significant dose-response relationship with the highest concentration of arsenic producing the greatest amount of TPO inhibition. Compared to controls, 0.1 ppm arsenic had no effect on TPO activity. Incubation for 2 min in the presence of 1.0, 5.0, or 10 ppm arsenic inhibited TPO activity to 4%, 9%, and 9% of control, respectively. After 10 min incubation in the presence of 1.0 or 5.0 ppm arsenic, TPO activity returned to 92% and 54% of control, respectively, while the presence of 10 ppm arsenic further inhibited TPO activity to 1% of control. In summary, arsenic trioxide inhibits in vitro TPO activity in a dose-dependent manner, and the minimal dose required to inhibit this activity is between 0.1 and 1 ppm.
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Focosi D, Caracciolo F, Galimberti S, Papineschi F, Petrini M. Long-term propylthiouracil use and acute myeloid leukemia: a case report and review of the literature. Ann Hematol 2007; 87:233-5. [PMID: 17846771 DOI: 10.1007/s00277-007-0369-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2007] [Accepted: 03/26/2007] [Indexed: 11/28/2022]
MESH Headings
- Adult
- Antimetabolites/administration & dosage
- Antimetabolites/adverse effects
- Antineoplastic Combined Chemotherapy Protocols/administration & dosage
- Chromosomes, Human, Pair 2/genetics
- Chromosomes, Human, Pair 21/genetics
- Cytarabine/administration & dosage
- Etoposide/administration & dosage
- Female
- Hematopoietic Stem Cell Transplantation
- Humans
- Idarubicin/administration & dosage
- Iodide Peroxidase/antagonists & inhibitors
- Leukemia, Myeloid, Acute/enzymology
- Leukemia, Myeloid, Acute/genetics
- Leukemia, Myeloid, Acute/therapy
- Peroxidase/antagonists & inhibitors
- Propylthiouracil/administration & dosage
- Propylthiouracil/adverse effects
- Remission Induction
- Time Factors
- Translocation, Genetic
- Transplantation, Homologous
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Mori K, Yoshida K, Nakagawa Y, Hoshikawa S, Ozaki H, Ito S, Watanabe C. Methylmercury inhibition of type II 5'-deiodinase activity resulting in a decrease in growth hormone production in GH3 cells. Toxicology 2007; 237:203-209. [PMID: 17582671 DOI: 10.1016/j.tox.2007.05.012] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2007] [Revised: 05/11/2007] [Accepted: 05/14/2007] [Indexed: 11/22/2022]
Abstract
We have recently reported that methylmercury (MeHg) inhibits type II iodothyronine 5'-deiodinase (D2) activity in mouse neuroblastoma NB41A3 cells. In the present study, we determined the biological significance of D2 inhibition by MeHg. GH3 rat pituitary tumor cells were treated with MeHg and D2 activity and production of a thyroid hormone-responsive gene product, growth hormone (GH) were analyzed. MeHg inhibited D2 activity and decreased thyroxine (T4)-induced, but not 3,3',5-triiodothyronine (T3)-induced GH secretion in GH3 cells. Our results suggest that MeHg inhibition of D2 activity might be involved in the inhibition of GH production in GH3 cells. Thus, D2 inhibition could be a novel mechanism involved in MeHg toxicity.
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Tan SW, Zoeller RT. Integrating basic research on thyroid hormone action into screening and testing programs for thyroid disruptors. Crit Rev Toxicol 2007; 37:5-10. [PMID: 17364703 DOI: 10.1080/10408440601123396] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Thyroid hormone signaling is highly conserved among all the vertebrates, and appears to be present in some invertebrates. Both the components that comprise the system and its general role in development and physiology are evolutionarily conserved, although specific events regulated by thyroid hormones, such as amphibian metamorphosis, may differ among taxonomic groups. The articles in this issue review the thyroid systems of mammals (specifically humans and rodents), fish, amphibians, and birds, and the states of the assays and endpoints used to detect disruption of the thyroid system within a toxicological paradigm. It must be noted that while reptiles represent an enormously important group, they were excluded because there was not enough information in the literature on thyroid toxicology in reptiles at the time that this series of reviews was drafted. Each review highlights the best assays for current regulatory use and those that may be considered for development for future use and research. However, it is important to remember that thyroid research is moving ahead at a fast pace. New thyroid research will impact the design of future thyroid assays used for the detection of thyroid system disruption in ways that may not be anticipated at the time of this writing. Several new areas of exploration are discussed that reveal potential sites of disruption in the thyroid system, including (1) the importance of the neural drive for TSH upregulation, (2) thyroid hormone transport, including cellular transporters like monocarboxylate anion transporter 8 (MCT8) that can regulate thyroid hormone action at the cellular level, and thyroid hormone-binding proteins in the serum that have been shown to differentially bind to environmental chemicals (e.g., certain PCB congeners), and (3) the deiodinases as a target for disruption of thyroid hormone activity in the peripheral thyroid system. The review papers in this issue represent the current state of thyroid assays and endpoints for detection of chemicals that disrupt the thyroid system.
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Konoplia EF, Vereshchako GG, Gorokh GA, Andronov EV, Luk'ianenko OV. [The irradiation consequencees of animals with alloxan-induced diabetes]. RADIATSIONNAIA BIOLOGIIA, RADIOECOLOGIIA 2007; 47:476-480. [PMID: 17953435] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
The effects of external acute irradiation at dose 1.0 Gy on biologic, haematologic and metabolic changes in blood of alloxan-induced diabetic rats were studied. It was found that the deterioration of diabetic animals occurs in different terms after irradiation exposure, resulting in considerable body weight decrease, well-marked hyperglycemia, abrupt falling of leukocytic system parameters, intensification energetic processes of extant lymphocytes, imbalance of lipid metabolism and thyroid state, as well as significant inhibition of 5'-deiodinase activity in liver tissue.
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Schmutzler C, Bacinski A, Gotthardt I, Huhne K, Ambrugger P, Klammer H, Schlecht C, Hoang-Vu C, Grüters A, Wuttke W, Jarry H, Köhrle J. The ultraviolet filter benzophenone 2 interferes with the thyroid hormone axis in rats and is a potent in vitro inhibitor of human recombinant thyroid peroxidase. Endocrinology 2007; 148:2835-44. [PMID: 17379648 DOI: 10.1210/en.2006-1280] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Endocrine disrupting chemicals (EDCs), either plant constituents or contaminants deriving from industrial products, may interfere with the thyroid hormone (TH) axis. Here, we examined whether selected EDCs inhibit the key reactions of TH biosynthesis catalyzed by thyroid peroxidase (TPO). We used a novel in vitro assay based on human recombinant TPO (hrTPO) stably transfected into the human follicular thyroid carcinoma cell line FTC-238. F21388 (synthetic flavonoid), bisphenol A (building block for polycarbonates), and the UV filter benzophenone 2 (BP2) inhibited hrTPO. BP2 is contained in numerous cosmetics of daily use and may be in regular contact with human skin. Half-maximal inhibition in the guaiacol assay occurred at 450 nmol/liter BP2, a concentration 20- and 200-fold lower than those required in case of the TPO-inhibiting antithyroid drugs methimazole and propylthiouracil, respectively. BP2 at 300 nmol/liter combined with the TPO substrate H(2)O(2) (10 mumol/liter) inactivated hrTPO; this was, however, prevented by micromolar amounts of iodide. BP2 did not inhibit iodide uptake into FRTL-5 cells. In BP2-treated rats (333 and 1000 mg/kg body weight), serum total T(4) was significantly decreased and serum thyrotropin was significantly increased. TPO activities in the thyroids of treated animals were unchanged, a finding also described for methimazole and propylthiouracil. Thus, EDCs, most potently BP2, may disturb TH homeostasis by inhibiting or inactivating TPO, effects that are even more pronounced in the absence of iodide. This new challenge for endocrine regulation must be considered in the context of a still prevailing iodide deficiency in many parts of the world.
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Archambeaud F, Orgiazzi J. Encéphalopathie corticosensible associée à une thyroïdite auto-immune: une entité revisitée. ANNALES D'ENDOCRINOLOGIE 2007; 68:92-3. [PMID: 17544359 DOI: 10.1016/j.ando.2007.03.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Laurberg P, Vestergaard H, Nielsen S, Christensen SE, Seefeldt T, Helleberg K, Pedersen KM. Sources of circulating 3,5,3'-triiodothyronine in hyperthyroidism estimated after blocking of type 1 and type 2 iodothyronine deiodinases. J Clin Endocrinol Metab 2007; 92:2149-56. [PMID: 17389703 DOI: 10.1210/jc.2007-0178] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
CONTEXT Graves' hyperthyroidism and multinodular toxic goiter lead to high serum T(3) compared with serum T(4). The source of this high T(3) has not been clarified. OBJECTIVE Our objective was to assess the role of iodothyronine deiodinase type 1 (D1) and type 2 (D2) for T(3) production and to estimate the sources of T(3) in hyperthyroidism. DESIGN AND SETTING The study was a prospective, randomized, open-labeled study in a secondary care setting. PATIENTS AND METHODS Consecutive patients with hyperthyroidism caused by Graves' disease or by multinodular toxic goiter were randomized to be treated with high-dose propylthiouracil (PTU) to block D1, PTU plus KI, or PTU plus sodium ipodate to additionally block D2. T(3) and T(4) were measured in serum, and we estimated the sources of T(3). RESULTS PTU reduced the T(3)/T(4) in serum to 47.7 +/- 2.5% (mean +/- sem) of the initial value on d 4 of therapy in patients with Graves' disease. The addition of KI to PTU led to a greater fall in T(3) and T(4), but the balance was unaltered. After PTU plus ipodate, T(3)/T(4) on d 4 was lower, 34.1 +/- 1.2% of the initial value. Similar variations were observed in patients with multinodular toxic goiter. Thus, the major source of the excess T(3) was D1-catalyzed T(4) deiodination, with a minor role for D2. It was estimated that the majority of this D1-catalyzed T(3) production takes place in the hyperactive thyroid gland. CONCLUSION Although thyroidal T(3) contributes only around 20% of total T(3) production in normal individuals, this is much higher in patients with a hyperactive thyroid, ranging up to two thirds. The major part is produced from T(4) deiodinated in the thyroid.
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Wong E, Rosen LS, Mulay M, Vanvugt A, Dinolfo M, Tomoda C, Sugawara M, Hershman JM. Sunitinib induces hypothyroidism in advanced cancer patients and may inhibit thyroid peroxidase activity. Thyroid 2007; 17:351-5. [PMID: 17465866 DOI: 10.1089/thy.2006.0308] [Citation(s) in RCA: 145] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
OBJECTIVE Sunitinib is a novel tyrosine kinase inhibitor with antitumor and antiangiogenic effects. An observed higher than expected rate of hypothyroidism in sunitinib-treated patients prompted assessment of the incidence of hypothyroidism. DESIGN Patients taking sunitinib had their thyroid function tests (TFTs) assessed via chart review. To explore potential effects on the thyroid, we examined the antiperoxidase activity of sunitinib by in vitro testing its effect on guaiacol oxidation and protein iodination by lactoperoxidase. MAIN OUTCOME Of the 89 patients who took sunitinib, 49 patients were excluded from analysis for several reasons. Of the remaining 40 patients, 21 (53%, 24% of the original 89) developed elevated thyrotropin (TSH) after a median of 5 months (range 1-36 months). Median TSH was 21.4 mU/L (range 4.6-174 mU/L). In vitro, sunitinib had antiperoxidase activity that was about one-fourth the potency of propylthiouracil. CONCLUSIONS Of the 40 patients who had TFTs assessed after starting sunitinib, 53% developed elevated TSH. We recommend that all patients treated with sunitinib be monitored for hypothyroidism. The mechanism of the antithyroid effect appears to be inhibition of peroxidase activity. Further research is needed to confirm the mechanism by which sunitinib induces hypothyroidism.
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Tindall AJ, Morris ID, Pownall ME, Isaacs HV. Expression of enzymes involved in thyroid hormone metabolism during the early development of Xenopus tropicalis. Biol Cell 2007; 99:151-63. [PMID: 17073826 DOI: 10.1042/bc20060074] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
BACKGROUND INFORMATION There are significant indications that amphibians require TH (thyroid hormones) prior to their involvement in the regulation of metamorphosis and before the development of a functional thyroid. RESULTS In order to investigate the potential role for TH in pre-metamorphic Xenopus tropicalis we have cloned cDNAs for, and analysed the expression of, TPO (thyroid peroxidase), 5'DII (type II iodothyronine deiodinase) and 5DIII (type III iodothyronine deiodinase), enzymes involved in TH metabolism. Zygotic expression of TPO was detected in neurula stage embryos. Expression was observed in the notochord and later in the thyroid. The notochord was also a common site of expression for 5'DII and 5DIII. Other sites of 5'DII expression are the otic vesicles, retina, liver, blood-forming region, branchial arches and brain. 5DIII is also expressed in the brain, retina, liver, developing pro-nephros, blood-forming region and branchial arches. Embryos exposed to the TPO inhibitor methimazole showed a distinctive dose-dependent phenotype of a crimped notochord and shortened axis, together with alterations in (125)I(-) uptake. CONCLUSIONS These data suggest a novel extrathyroidal role for TH during early development, and support the proposal that embryos require thyroid signalling for normal development prior to metamorphosis.
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Thomasz L, Aran M, Pizarro RA, Ibañez J, Pisarev MA, Converso D, Juvenal GJ, Krawiec L. Inhibition of peroxidase and catalase activities and modulation of hydrogen peroxide level by inositol phosphoglycan-like compounds. Horm Metab Res 2007; 39:14-9. [PMID: 17226108 DOI: 10.1055/s-2007-957341] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Inositol phosphoglycan-like compounds are produced by the hydrolysis of the membrane bound glycosyl phosphoinositides. Besides being short term mediators of insulin action, they inhibit peroxidases and catalase, increasing the concentration of cellular hydrogen peroxide. Although high concentrations of hydrogen peroxide are toxic, moderate increases of its basal level are signals for different metabolic pathways. The inhibitor, localized in the cytosol of the cell, acts on peroxidases and catalase of the same tissue (homologous action) and of other tissues or organisms (heterologous action). The inositol phosphoglycan-like compound inhibits peroxidases with different prosthetic groups, i.e. containing iron such as: thyroid peroxidase, lactoperoxidase, horseradish peroxidase, soy bean peroxidase; and containing selenium such as glutathione peroxidase and 2-cys peroxiredoxin with no prosthetic group. Besides peroxidases, the inositol phosphoglycan-like compound inhibits catalase, another heme enzyme. The inhibition kinetics demonstrates a noncompetitive effect. The site of action is not the prosthetic group, given that the inhibitor does not produce any effect on the peak in the Soret region in the presence or absence of hydrogen peroxide. In conclusion, the inositol phosphoglycan-like compound is the general inhibitor of peroxidases and catalase involved in the modulation of hydrogen peroxide level that acts in different metabolic pathways as a signal transducer.
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