Determinants and Clinical Implications of Thyroid Peroxidase Antibodies in Middle-Aged and Elderly Individuals: The Rotterdam Study.

Background: Thyroid peroxidase antibodies (TPO-Abs) play an important role in autoimmune thyroid disease, but are also prevalent in healthy individuals. However, it is unclear what determinants may influence the occurrence of TPO-Abs in healthy individuals and how TPO-Abs may affect health outcomes in these individuals. We aimed to identify determinants of TPO-Abs in a large, prospective population-based cohort of middle-aged and elderly individuals and to subsequently assess the association between TPO-Abs and risk of overall and cause-specific mortality. Methods: We performed binomial and multinomial logistic regression analyses to obtain odds ratios (ORs) and 95% confidence intervals [95% CIs] for the association of potential determinants based on previous literature with TPO-Ab positivity (>35 kU/L), TPO-Ab detectability (>5 kU/L), and TPO-Ab categories. Cox proportional hazards regression analyses were performed to obtain hazard ratios (HRs) and CIs for the association between TPO-Abs and mortality risk. Results: In 9685 participants (57% women, median baseline age 63.3 years, median follow-up time 10.1 years), we identified female sex (OR = 2.47 [CI 2.13-2.86]) and current smoking (OR = 3.10 [CI 2.66-3.62]) as determinants of TPO-Ab positivity and TPO-Ab detectability, respectively. Higher age (OR = 0.98 [CI 0.97-0.98]) and all categories of alcohol consumption (ORs ranging from 0.71-0.78) were associated with lower odds of TPO-Ab detectability. TPO-Ab detectability was associated with a higher risk of overall (HR = 1.09 [CI 1.01-1.17]), cancer-related (HR = 1.18 [CI 1.01-1.38]), and cardiovascular mortality (HR = 1.21 [CI 1.01-1.45]). Interestingly, this was more prominent in men compared with women (HR for cardiovascular mortality 1.50 vs. 0.99, respectively). Conclusions: In community-dwelling middle-aged and elderly individuals, female sex and current smoking are the most important determinants associated with TPO-Ab levels in the detectable and positive range, whereas alcohol consumption is associated with lower odds of TPO-Abs. The clinical importance of detectable TPO-Ab levels is illustrated by the association with an increased mortality risk, mainly in men. Our results warrant further exploration of the clinical applicability of detectable TPO-Ab levels, potentially as a marker for low-grade inflammation. The Rotterdam Study has been entered into the Netherlands National Trial Register (NTR; www.trialregister.nl) and into the WHO International Clinical Trials Registry Platform (ICTRP; www.who.int/ictrp/network/primary/en/) under shared catalogue number NTR6831.

Genome-wide analysis of thyroid function in Australian adolescents highlights SERPINA7 and NCOA3.

OBJECTIVE: Genetic factors underpin the narrow intraindividual variability of thyroid function, although precise contributions of environmental vs genetic factors remain uncertain. We sought to clarify the heritability of thyroid function traits and thyroid peroxidase antibody (TPOAb) positivity and identify single nucleotide polymorphisms (SNPs) contributing to the trait variance. METHODS: Heritability of thyroid-stimulating hormone (TSH), free T4 (fT4), free T3 (fT3) and TPOAb in a cohort of 2854 euthyroid, dizygous and monozygous twins (age range 11.9-16.9 years) from the Brisbane Longitudinal Twin Study (BLTS) was assessed using structural equation modelling. A genome-wide analysis was conducted on 2832 of these individuals across 7 522 526 SNPs as well as gene-based association analyses. Replication analysis of the association results was performed in the Raine Study (n = 1115) followed by meta-analysis to maximise power for discovery. RESULTS: Heritability of thyroid function parameters in the BLTS was 70.8% (95% CI: 66.7-74.9%) for TSH, 67.5% (59.8-75.3%) for fT4, 59.7% (54.4-65.0%) for fT3 and 48.8% (40.6-56.9%) for TPOAb. The genome-wide association study (GWAS) in the discovery cohort identified a novel association between rs2026401 upstream of NCOA3 and TPOAb. GWAS meta-analysis found associations between TPOAb and rs445219, also near NCOA3, and fT3 and rs12687280 near SERPINA7. Gene-based association analysis highlighted SERPINA7 for fT3 and NPAS3 for fT4. CONCLUSION: Our findings resolve former contention regarding heritability estimates of thyroid function traits and TPOAb positivity. GWAS and gene-based association analysis identified variants accounting for a component of this heritability.

Low intake of iodized salt and iodine containing supplements among pregnant women with apparently insufficient iodine status - time to change policy?

BACKGROUND: Iodine is an essential nutrient for human health throughout the life cycle, especially during early stages of intrauterine life and infancy, to ensure adequate neurocognitive development. The growing global reliance on desalinated iodine-diluted water raises the specter of increased iodine deficiency in several regions. The case of Israel may be instructive for exploring the link between iodine status and habitual iodine intake in the setting of extensive national reliance on desalinated water. The aim of this study was to explore the relationship between iodine intake, including iodized salt and iodine-containing supplements intake, and iodine status among pregnant women residing in a sub-district of Israel that is highly reliant on desalinated iodine-diluted water. METHODS: A total of 134 consecutive pregnant women were recruited on a voluntary basis from the obstetrics department of the Barzilai University Medical Center during 2018. Blood was drawn from participants to determine levels of serum thyrotropin (TSH), thyroid peroxidase antibodies (TPOAb), thyroglobulin antibodies (TgAb) and thyroglobulin (Tg). An iodine food frequency questionnaire (sIFFQ) was used to assess iodine intake from food, IS and ICS. A questionnaire was used to collect data on demographic and health characteristics. RESULTS: A total of 105 pregnant women without known or reported thyroid disease were included in the study. Elevated Tg values (≥ 13 µg/L), were found among 67% of participants, indicating insufficient iodine status. The estimated iodine intake (median, mean ± SD 189, 187 ± 106 µg/d by sIFFQ) was lower than the levels recommended by the World Health Organization and the Institute of Medicine (250 vs. 220 µg/day respectively). The prevalence of iodized salt intake and iodine containing supplement intake were 4 and 52% (respectively). Values of Tg > 13 µg/L were inversely associated with compliance with World Health Organization and Institute of Medicine recommendations. CONCLUSIONS: While the Israeli Ministry of Health has recommended the intake of iodized salt and iodine containing supplements, this is apparently insufficient for achieving optimal iodine status among Israeli pregnant women. The evidence of highly prevalent probable iodine deficiency in a sample of pregnant women suggests an urgent need for a national policy of iodized salt regulation, as well as guidelines to promote iodine containing supplements and adherence to them by caregivers. In addition, studies similar to this one should be undertaken in additional countries reliant on desalinated iodine-diluted water to further assess the impact of desalinization on maternal iodine status.

Seguimiento del hijo de madre con patología tiroidea autoinmune. ¿Qué no debemos cribar? / Follow-up of infants born to mothers with autoinmune thyroid disease. What should not be screened?

Introducción: La patología tiroidea es un problema frecuente en las mujeres embarazadas. Su etiología suele ser autoinmune siendo la tiroiditis de Hashimoto y la enfermedad de Graves las entidades principales. A pesar de las posibles alteraciones hormonales y del paso transplacentario de anticuerpos estimulantes, la realización de un cribado neonatal específico no ha demostrado su utilidad en el neonato. Pacientes y métodos: Estudio prospectivo (noviembre de 2013-diciembre de 2016) de los hijos de madre con patología tiroidea autoinmune nacidos en un hospital universitario nivel III. Los recién nacidos se seleccionaron en maternidad. Se excluyeron los casos de asfixia perinatal. Los datos se recogieron de las historias clínicas de madres y recién nacidos. Resultados: Se incluyeron 191 recién nacidos. El 90% de las madres estaban diagnosticadas de hipotiroidismo autoinmune, de cuyos hijos solo un 5,8% tuvo alguna alteración analítica tratándose de leves ascensos de tirotropina, con normalización al mes de vida, no correlacionándose con los niveles de anti-TPO. Se diagnosticó una hipertirotropinemia transitoria que precisó tratamiento durante el primer año de vida. El 36,8% de los hijos de madre con Graves tuvo algún control analítico alterado en los primeros 7 días de vida, no diagnosticándose ningún caso de hipertiroidismo y solo una hipertirotropinemia transitoria. Conclusiones: La experiencia de nuestro centro en el manejo del cribado neonatal tiroideo muestra un elevado número de controles analíticos con un escaso rendimiento diagnóstico. No encontramos relación entre niveles de anticuerpos anti-TPO y disfunción tiroidea. Apoyamos las recomendaciones de mantener el cribado neonatal universal como única exploración en los hijos de madre hipotiroidea

Introduction: Thyroid dysfunction is a common problem in pregnant women. It is usually of an autoimmune origin, with Hashimotós thyroiditis and Graveś disease being the most common conditions. Although hormonal changes and transplacental antibody transfer may occur, specific neonatal screening has not been shown to be useful. Patients and method: A prospective study of newborns of women with autoimmune thyroid disease born at a level III university hospital (November 2013-December 2016). Neonates were selected during their stay at the maternity. Babies with perinatal asphyxia were excluded. Data were collected from the clinical histories of mothers and newborns. Results: A total of 191 neonates were included. Ninety percent of mothers had been diagnosed with autoimmune hypothyroidism. Only 5.8% of newborns had some laboratory disorder, consisting of slightly increased thyroid-stimulating hormone levels, which returned to normal at the age of one month and did not correlate to thyroid peroxidase antibody levels. Transient hyperthyrotropinemia was diagnosed in one newborn and required thyroxin treatment during the first year of life. Among newborns from mothers with Graveś disease, 36.8% had some abnormal laboratory value during the first 7 days of life, but there were no cases of hyperthyroidism and only one of transient hyperthyrotropinemia. Conclusions: Experience at our hospital in screening of newborns from hypothyroid mothers reveals a high number of laboratory controls with a poor diagnostic yield. No relationship was found between thyroid peroxidase antibody levels and thyroid dysfunction. We support the recommendations to continue testing serum thyroid-stimulating hormone and FT4 levels at 48h of life in newborns of mothers with autoimmune hypothyroidism

Immunocytochemical characteristics of thyrocytes in radioiodine refractory metastases of papillary thyroid cancer.

The aim of the work was to carry out an immunocytochemical (ICC) study of thyroid peroxidase (TPO) and thyroglobulin (Tg) expression in the punctates of the radioiodine (RI) refractory and RI uptake metastases of thyroid papillary carcinoma (PTC), on the basis of which it is possible to develop new methods of preoperative prediction of RI resistance and RI therapy efficiency for thyroid papillary carcinoma metastases. MATERIALS AND METHODS: The ICC research was carried out on a fine needle aspiration biopsy material of 104 metastases that were found after thyroidectomy and RI therapy, i.e. in postoperative period (79 - radioiodine-refractory metastases, 25 - radioiodine-uptake metastases). The ICC analysis of TPO and Tg expression in PTC was performed with the use of monoclonal antibodies against TPO and Tg. RESULTS: RI-refractory (RIRM) and RI-uptake metastases of PTC significantly differ by the percentage of cells expressing TPO and Tg (p < 0.05, and p < 0.05 respectively). The effectiveness of RI therapy was different for patients with different percentages of TPO-positive cells. CONCLUSION: A statistically significant difference was demonstrated in the expression of TPO in a punctates of RI-resistant and RI-sensitive metastatic TPC, based on which a new method for preoperative prediction of RI resistance and RI therapy efficiency was developed. It was shown that ICC determination of Tg expression in metastases is effective in preoperative monitoring of RI resistance of PTC if the part of Tg-positive cells in punctates is lower than 56%. The comprehensive study of the ICC profile of thyrocytes in RI-uptake metastases punctates allows us to develop a personified approach to prediction, monitoring and therapy of patients with PTC.

Thyroid peroxidase (TPO) expressed in thyroid and breast tissues shows similar antigenic properties.

BACKGROUND: Thyroid peroxidase (TPO) is essential for physiological function of the thyroid gland. The high prevalence of thyroid peroxidase antibodies (TPOAbs) in patients with breast cancer and their protective role had previously been demonstrated, indicating a link between breast cancer and thyroid autoimmunity. Recently, TPO was shown to be present in breast cancer tissue samples but its antigenicity has not been analyzed. METHODS: In this study, we investigated TPO expression levels in a series of fifty-six breast cancer samples paired with normal (peri-tumoral) tissue and its antigenic activity using a panel of well-characterized murine anti-human TPOAbs. RESULTS: We have shown that TPO transcripts were present in both normal and cancer tissue samples, although the amounts in the latter were reduced. Additionally, we observed that TPO levels are lower in more advanced cancers. TPO protein expression was confirmed in all tissue samples, both normal and cancerous. We also found that the antigenicity of the immunodominant regions (IDRs) in breast TPO resembles that of thyroid TPO, which is crucial for effective interactions with human TPOAbs. CONCLUSIONS: Expression of TPO in breast cancer together with its antigenic activity may have beneficial effects in TPOAb-positive breast cancer patients. However, further studies are needed to confirm the beneficial role of TPOAbs and to better understand the underlying mechanism.

A Nonradioactive DEHAL Assay for Testing Substrates, Inhibitors, and Monitoring Endogenous Activity.

Iodotyrosine deiodinase (DEHAL1) is a crucial enzyme in iodine homeostasis. Unbound mono- and diiodotyrosines are indispensable byproducts of thyroid hormone biosynthesis. Their iodine needs to be recovered to avoid iodine deficiency, as observed in genetic defects in DEHAL1. Despite its importance, the enzyme is rarely studied. The deiodination process can be monitored by radioactive tracers or via techniques involving mass spectrometry. However, isotope-labeled molecules are expensive, not always commercially available, and their use is legally restricted, whereas mass spectrometry requires sophisticated, costly, and sensitive instrumentation. To circumvent these difficulties, we adapted the nonradioactive iodothyronine deiodinase assay to determine DEHAL1 activity by a colorimetric readout, based on the Sandell-Kolthoff reaction. DEHAL1 was recombinantly expressed and used to optimize the assay in microtiter format. We applied the setup to scenarios of alternative substrate screening or search for compounds potentially acting as endocrine disrupting compounds, without identifying novel readily accepted substrates or inhibitors yet. Next, the assay was adapted to ex vivo material, and activity was reliably determined from rodent kidney and other tissues. Analyzing two mouse models of hyperthyroidism, we observed a decreased renal Dehal1 activity and mRNA expression. Our results show that this nonradioactive DEHAL1 assay is suited to screen for potential endocrine disrupters and to monitor endogenous Dehal1 expression. We harmonized the assay protocols to enable iodothyronine deiodinase and DEHAL1 activity measurements from the same samples. Hereby, a more complete view on iodine metabolism by these predominant deiodinating activities can be obtained from a given sample by a similar process flow.

Identification of CHEK1, SLC26A4, c-KIT, TPO and TG as new biomarkers for human follicular thyroid carcinoma.

The search for preoperative biomarkers for thyroid malignancies, in particular for follicular thyroid carcinoma (FTC) diagnostics, is of utmost clinical importance. We thus aimed at screening for potential biomarker candidates for FTC. To evaluate dynamic alterations in molecular patterns as a function of thyroid malignancy progression, a comparative analysis was conducted in clinically distinct subgroups of FTC and poorly differentiated thyroid carcinoma (PDTC) nodules. NanoString analysis of FFPE samples was performed in 22 follicular adenomas, 56 FTC and 25 PDTC nodules, including oncocytic and non-oncocytic subgroups. The expression levels of CHEK1, c-KIT, SLC26A4, TG and TPO were significantly altered in all types of thyroid carcinomas. Based on collective changes of these biomarkers which correlating among each other, a predictive score has been established, allowing for discrimination between benign and FTC samples with high sensitivity and specificity. Additional transcripts related to thyroid function, cell cycle, circadian clock, and apoptosis regulation were altered in the more aggressive oncocytic subgroups only, with expression levels correlating with disease progression. Distinct molecular patterns were observed for oncocytic and non-oncocytic FTCs and PDTCs. A predictive score correlation coefficient based on collective alterations of identified here biomarkers might help to improve the preoperative diagnosis of FTC nodules.

Determination of thyrotropin reference values in an adult Mexican population / Determinación de los valores de referencia para la tirotropina en una población mexicana adulta

BACKGROUND AND OBJECTIVE: The upper limit of TSH reference level is controversial. The purpose of our study was to determine TSH reference values in a Mexican population in accordance with the National Academy of Clinical Biochemistry (NACB) criteria and in correlation with thyroid ultrasound (US) examination. PATIENTS AND METHODS: The study was conducted in volunteers with no known thyroid disease. We recruited 482 subjects, most of them medical or administrative staff from our hospital. They answered a questionnaire on demographic data, family history, co-morbidities, and drug use. Their thyroid hormone levels and thyroid antibodies were determined, and a complete physical examination and thyroid US were performed. The population used to establish the TSH reference intervals was selected according to the NACB criteria and their normal thyroid structural and echogenic characteristics in US examination. RESULTS: Among 482 subjects (209 males) with a median age of 26 years, prevalence rates of TPOAb and TgAb were 9.3% and 10.3% respectively. Mean TSH level in the overall population was 1.90 ± 1.94, with a 97.5 th percentile of 6.76 mIU/L. The reference population was limited to 282 subjects (41.5% were excluded) with a mean TSH of 1.86 ± 1.63 and a 97.5 th percentile of 4.88 mIU/L. No sex difference was found (p = 0.287). Median urinary iodine level in the reference population was 267¿g/L IQR (161.3-482.5). CONCLUSIONS: The TSH reference interval in the reference population was 0.71 (CI 0.65 - 0.77) to 4.88 mIU/L (CI 4.5 - 5.3); these limits may be influenced by iodine nutritional status in this population

ANTECEDENTES Y OBJETIVO: Existe controversia respecto al límite superior de referencia para TSH. El objetivo del estudio fue determinar los valores de referencia para TSH en una población mexicana de acuerdo con los criterios de la National Academy of Clinical Biochemistry (NACB) y en correlación con el examen ultrasonográfico (US) tiroideo. PACIENTES Y MÉTODOS: El estudio se realizó en voluntarios sin enfermedad tiroidea conocida. Se reclutaron 482 individuos, personal sanitario y administrativo del hospital, que respondieron un cuestionario sobre datos demográficos, antecedentes familiares, co-morbilidades y medicamentos consumidos, y a los que se les practicó determinación de hormonas tiroideas, anticuerpos anti-tiroideos, exploración y US tiroideo. La población escogida para establecer los intervalos de referencia de TSH fue seleccionada con los criterios de la NACB más la normalidad estructural y ecogénica del tiroides por US. RESULTADOS: En los 482 sujetos (209 hombres) con mediana de edad de 26 años, la prevalencia de TPOAb fue de 9,3% y TgAb 10,3%. La media de TSH para la población total fue 1,90n ± 1,94, con percentil 97,5 de 6,76 mUI/L. La población de referencia se limitó a 282 sujetos (41,5% fueron excluidos); la TSH media de esta población fue de 1,86±1,63, con percentil 97,5 de 4,88 mUI/L, sin diferencia entre géneros (p = 0,287). La mediana para la yoduria de la población referencia fue 267¿g/L RIQ (161,3-482,5). CONCLUSIONES: El intervalo de referencia para la TSH fue de 0,71 (IC 0,65 - 0,77) a 4,88 mUI/L (IC 4,5 - 5,3); el resultado posiblemente está influido por el estado nutricional de yodo de esta población

Prevalence of thyroid dysfunction with adequate and excessive iodine intake in Hebei Province, People's Republic of China.

OBJECTIVE: To explore (i) the prevalence of thyroid dysfunction in populations with adequate and excessive iodine intakes and (ii) the effect of iodine exposure on the prevalence of thyroid dysfunction. DESIGN: Cross-sectional study was conducted in Hebei in 2010. The population was classified as having adequate or excessive iodine intake according to the iodine concentration in drinking water. Demographic information was collected by questionnaire. Levels of serum thyroid hormones, thyroid autoantibodies and iodine in drinking water and urine were measured. SETTING: Villages with adequate or excessive drinking water iodine in Hebei Province, People's Republic of China. SUBJECTS: A total of 854 men and women aged 20-50 years who had lived in the surveyed areas for over 5 years, including 348 from the adequate iodine area (AIA) and 506 from the excessive iodine area (EIA). RESULTS: Median urinary iodine concentration was 185 µg/l in AIA and 1152 µg/l in EIA. The prevalence of thyroid dysfunction in AIA was 10.3%, which included 1.1% with hypothyroidism and 8.1% with subclinical hypothyroidism; and 20.6% in EIA, which included 3.6% with hypothyroidism and 13.6% with subclinical hypothyroidism. The positive rates of thyroglobulin antibody were 16.1% in AIA and 11.9% in EIA; the positive rates of thyroperoxidase antibody were 20.7% in AIA and 16.4% in EIA. CONCLUSIONS: Excessive iodine intake may lead to increased prevalence of biochemical thyroid dysfunction, especially biochemical hypothyroidism. This is not related to an increase in prevalence of thyroid antibodies. Women are more susceptible to iodine excess.

Prolonged food deprivation increases mRNA expression of deiodinase 1 and 2, and thyroid hormone receptor ß-1 in a fasting-adapted mammal.

Food deprivation in mammals is typically associated with reduced thyroid hormone (TH) concentrations and deiodinase content and activity to suppress metabolism. However, in prolonged-fasted, metabolically active elephant seal pups, TH levels are maintained, if not elevated. The functional relevance of this apparent paradox is unknown and demonstrates variability in the regulation of TH levels, metabolism and function in food-deprived mammals. To address our hypothesis that cellular TH-mediated activity is upregulated with fasting duration, we quantified the mRNA expression and protein content of adipose and muscle deiodinase type I (DI1) and type II (DI2), and TH receptor beta-1 (THrß-1) after 1, 3 and 7 weeks of fasting in northern elephant seal pups (N=5-7 per week). Fasting did not decrease the concentrations of plasma thyroid stimulating hormone, total triiodothyronine (tT3), free T3, total thyroxine (tT4) or free T4, suggesting that the hypothalamic-pituitary-thyroid axis is not suppressed, but rather maintained during fasting. Mean mRNA expression of adipose DI1 and DI2 increased threefold and fourfold, respectively, and 20- and 30-fold, respectively, in muscle. With the exception of adipose DI1, protein expression of adipose DI2 and muscle DI1 and DI2 increased twofold to fourfold. Fasting also increased adipose (fivefold) and muscle (fourfold) THrß-1 mRNA expression, suggesting that the mechanisms mediating cellular TH activity are upregulated with prolonged fasting. The data demonstrate a unique, atypical mechanism of TH activity and regulation in mammals adapted to prolonged food deprivation in which the potential responsiveness of peripheral tissues and cellular TH activity are increased, which may contribute to their lipid-based metabolism.

Thyroid hormones and their placental deiodination in normal and pre-eclamptic pregnancy.

Pre-eclampsia is associated with lower serum selenium concentrations and glutathione peroxidase expression/activity; total thyroid hormones are also lower. OBJECTIVES, STUDY DESIGN AND MAIN OUTCOME MEASURES: We hypothesised that the placental selenoprotein deiodinase (D3) will be protected in pre-eclampsia due to the hierarchy of selenoprotein biosynthesis in selenium deficiency. Venous blood and tissue from three standardised placental sites were obtained at delivery from 27 normotensive and 23 pre-eclamptic women. mRNA expression and enzyme activity were assessed for both deiodinases (D2 and D3); protein expression/localisation was also measured for D3. FT4, FT3 and TSH concentrations were measured in maternal and umbilical cord blood. RESULTS: No significant differences in D3 mRNA or protein expression between normotensive and pre-eclamptic pregnancies. There was a significant effect of sampling site on placental D3 activity only in pre-eclamptic women (P = 0.034; highest activity nearest the cord). A strong correlation between D3 mRNA expression and enzyme activity existed only in the pre-eclamptic group; further strengthened when controlling for maternal selenium (P < 0.002). No significant differences were observed between groups for any of the maternal thyroid hormones; umbilical TSH concentrations were significantly higher in the pre-eclamptic samples (P < 0.001). CONCLUSIONS: D3 mRNA and protein expression appear to be independent of selenium status. Nevertheless, the positive correlation between D3 mRNA expression and activity evident only in pre-eclampsia, suggests that in normotensive controls, where selenium is higher, translation is not affected, but in pre-eclampsia, where selenium is low, enzyme regulation may be altered. The raised umbilical TSH concentrations in pre-eclampsia may be an adaptive fetal response to maximise iodide uptake.

Possible link between Hashimoto's thyroiditis and oral lichen planus: a novel association found.

OBJECTIVES: Hashimoto's thyroiditis as well as lichen planus has been associated to a number of disorders, generally of auto-immune origin. A novel possible association between oral lichen planus (OLP) and Hashimoto's thyroiditis (HT) is here proposed on the basis of a cross-sectional survey. MATERIALS AND METHODS: One hundred and five unrelated OLP patients were considered. Diagnosis of HT was based on positive serum anti-TPO, anti-Tg, TSH levels and the typical ultrasound pattern of the thyroid gland. RESULTS: In the present survey, the prevalence of HT in the OLP group was 14.3 % whereas the prevalence of HT-related hypothyroidism in the general population was reported to be equal to 1 %. By Fisher's exact test, it was revealed that the difference between our data and historical prevalence of HT was found statistically significant. CONCLUSION: Actually, there is no definitive hypothesis that could explain the coexistence of OLP and HT. However, considering the onset timing of HT followed by OLP in 93.3 % of our series, we suspected a causal or predisposing role for HT. Specifically, we believe that in HT patients, circulating thyroid antibodies could contribute to trigger an organ-specific auto-immune response also in the oral mucosa or skin, leading to the development of LP lesions. CLINICAL RELEVANCE: Because of the large number of cases of asymptomatic chronic auto-immune thyroiditis, it would be useful that women over 40 years of age affected by OLP were screened for thyroid dysfunction, particularly HT.

Increased type 3 deiodinase expression in papillary thyroid carcinoma.

BACKGROUND: Thyroid hormone regulates a wide range of cellular activities, including the balance between cell proliferation and differentiation. The thyroid-hormone-inactivating type 3 deiodinase (DIO3, D3) has been shown to be reactivated in human neoplasias. Here, we evaluated DIO3 expression in human papillary thyroid carcinoma (PTC). METHODS: Tumor and surrounding normal thyroid tissue were collected from 26 unselected patients with PTC. Clinical data were retrospectively reviewed in medical records. DIO3 mRNA levels were measured by real-time polymerase chain reaction and D3 activity by paper-descendent chromatography. Studies of DIO3 gene regulation were performed in a human PTC-derived cell line (K1 cells). BRAF(V600E) mutation was identified in DNA from paraffin-embedded tissues by direct sequencing. Immunohistochemistry analyses were performed using a specific human D3 antibody. RESULTS: Increased D3 activity was detected in all 26 PTC samples analyzed as compared with adjacent thyroid tissue. The augmentations in D3 activity were paralleled by increased DIO3 mRNA levels (approximately fivefold). In PTC-derived cells, DIO3 transcripts were further upregulated by the transforming growth factor ß1 (TGFß1). Interestingly, preincubation with mitogen-activated protein kinase (MAPK) cascade inhibitors U0126 (ERK pathway) and SB203580 (p38 pathway) decreased DIO3 mRNA levels and blocked the TGFß1-induced increase in DIO3 transcripts, suggesting that D3 induction might be mediated through the MAPK signaling pathway. Accordingly, DIO3 mRNA and activity levels were significantly higher in BRAF(V600E)-mutated samples (p=0.001). Increased D3 activity was correlated with tumor size (r=0.68, p=0.003), and associated with lymph node (p=0.03) or distant metastasis (p=0.006) at diagnosis. Conversely, decreased levels of the thyroid-hormone-activating type 2 deiodinase (DIO2) gene were observed in PTC, which might contribute to further decreases in intracellular thyroid hormone levels. Increased D3 expression was also observed in follicular thyroid carcinoma but not in medullary or anaplastic thyroid carcinoma samples. CONCLUSIONS: These results indicate that the malignant transformation of thyroid follicular cell toward PTC promotes opposite changes in DIO3 and DIO2 expression by pretranscriptional mechanisms. The association between increased levels of D3 activity and advanced disease further supports a role for intracellular triiodothyronine concentration on the thyroid tumor cell proliferation or/and dedifferentiation.

Iodotyrosine deiodinase defect identified via genome-wide approach.

CONTEXT: Diagnosis of congenital hypothyroidism is hampered by the heterogeneity of inborn errors of thyroid metabolism and the possible delay in hypothyroidism development leading to missed cases by neonatal screen. OBJECTIVE: In the current study, we used a whole-genome approach to identify the mutation responsible for severe hypothyroidism and a huge goiter in the eldest child born to healthy first cousins. RESULTS: We identified a homozygous mutation of the iodotyrosine deiodinase gene (IYD). We delineated the phenotype of this defect in detail, including urinary monoiodotyrosine (MIT) and diiodotyrosine (DIT) excretion. Moreover, a 4.5-yr-old sister was found homozygous for the mutation. Her clinical and biological data were normal, except for elevated MIT and DIT excretion. The urinary loss of MIT and DIT iodine observed in most affected individuals was quite limited compared to the total iodine loss, except for the hypothyroid homozygote. Hypothyroidism could therefore be partially induced by a relative iodine deficiency caused by urinary iodine loss through MIT and DIT excretion, even in cases of normal iodine intake. The wide inter- and intrafamilial variability of the disease severity remains unclear. CONCLUSIONS: Besides refining the phenotype of the IYD defect, our observation shows that a global, genome-wide approach to the heterogeneous inborn thyroid defects was efficient in rapidly identifying the mutation in the proband and the disease recurrence in the still euthyroid sister. Although facilitated by consanguinity in this family, novel sequencing techniques will soon make whole-genome approaches readily amenable to more common cases.

Combined immunohistochemistry for thyroid peroxidase, galectin-3, CK19 and HBME-1 in differential diagnosis of thyroid tumors.

We evaluated some proposed molecular thyroid tumor markers: thyroid peroxidase (TPO), galectin-3, cytokeratin-19, and HBME-1, individually and in combination, by immunohistochemistry in a total of 242 archival thyroid tissue sections. The expression of each individual marker was most helpful for the diagnosis of papillary carcinoma and its follicular variant. However, none of them was sensitive and specific enough to discriminate between Hürthle adenoma and carcinoma. Galectin-3 and HBME-1 could be used as single discriminators between follicular thyroid adenoma and carcinoma, but HBME-1 is the better choice. As a single test, all analyzed tumor markers had sufficient power to predict differentiated thyroid cancer, with sensitivities ranging from 66.5% to 82.2%. The sensitivity was improved by using combinations of some proposed markers. Only two antigens, HBME-1 and TPO, had distinct predictive values for different diagnostic alternatives i.e. a sequential combination improved diagnostic accuracy between follicular thyroid adenoma and the follicular variant of papillary thyroid carcinoma to 92.6% and consequently, between overall benign and malignant thyroid tumors to 89.1%. HBME-1 is the most accurate ancillary stain in discriminating well-differentiated thyroid carcinomas from benign tumors, although the addition of TPO did improve accuracy and served as a useful confirmatory marker.

The thyroid hormone-inactivating type III deiodinase is expressed in mouse and human beta-cells and its targeted inactivation impairs insulin secretion.

Deiodinases are selenoproteins that activate or inactivate thyroid hormone. During vertebrate development, these pathways control thyroid hormone action in a cell-specific fashion explaining how systemic thyroid hormone can affect local control of tissue embryogenesis. Here we investigated the role of the thyroid hormone-inactivating deiodinase (D3) in pancreatic islet function and glucose homeostasis. D3 expression was determined by real-time PCR, immunofluorescence, and enzyme activity. Embryonic and adult wild-type mice and Mice with targeted disruption of Dio3 gene (D3KO) as well as human fetal pancreas and adult islets were studied. Insulin secretion was evaluated in adult mouse isolated islets. We found Dio3 gene expression and protein highly expressed in embryonic and adult pancreatic islets, predominantly in ß-cells in both humans and mice. However, mRNA levels were barely detectable for both the thyroid hormone-activating deiodinases types 1 and 2. D3KO animals were found to be glucose intolerant due to in vitro and in vivo impaired glucose-stimulated insulin secretion, without changes in peripheral sensitivity to insulin. D3KO neonatal (postnatal day 0) and adult pancreas exhibited reduced total islet area due to reduced ß-cell mass, insulin content, and impaired expression of key ß-cells genes. D3 expression in perinatal pancreatic ß-cells prevents untimely exposure to thyroid hormone, the absence of which leads to impaired ß-cell function and subsequently insulin secretion and glucose homeostasis. An analogous role is likely in humans, given the similar D3 expression pattern.

Type-2 iodothyronine 5'deiodinase in skeletal muscle of C57BL/6 mice. I. Identity, subcellular localization, and characterization.

RT-PCR shows that mouse skeletal muscle contains type-2 iodothyronine deiodinase (D2) mRNA. However, the D2 activity has been hard to measure. Except for newborn mice, muscle homogenates have no detectable activity. However, we have reported D2 activity in mouse muscle microsomes. As the mRNA, activity is higher in slow- than in fast-twitch muscle. We addressed here the major problems in measuring D2 activity in muscle by: homogenizing muscle in high salt to improve yield of membranous structures; separating postmitochondrial supernatant between 38 and 50% sucrose, to eliminate lighter membranes lacking D2; washing these with 0.1 M Na(2)CO(3) to eliminate additional contaminating proteins; pretreating all buffers with Chelex, to eliminate catalytic metals; and eliminating the EDTA from the assay, as this can bind iron that enhances dithiothreitol oxidation and promotes peroxidation reactions. Maximum velocity of T(3) generation by postgradient microsomes from red muscles was approximately 1100 fmol/(h · mg) protein with a Michaelis-Menten constant for T(4) of 1.5 nM. D2-specific activity of Na(2)CO(3)-washed microsomes was 6-10 times higher. The enrichment in D2 activity increased in parallel with the capacity of microsomes to load (sarco/endoplasmic reticulum Ca(2+)-ATPase) and bind Ca(2+) (calsequestrin), indicating that D2 resides in the inner sarcoplasmic reticulum, close to the nuclei. The presence of D3 in the sarcolemma suggests that the most of D2-generated T(3) acts locally. Estimates from maximum velocity, Michaelis-Menten constant, and muscle T(4) content suggest that mouse red, type-1, aerobic mouse muscle fibers can generate physiologically relevant amounts of T(3) and, further, that muscle D2 plays an important role in thyroid hormone-dependent muscle thermogenesis.

Accumulation and debromination of decabromodiphenyl ether (BDE-209) in juvenile fathead minnows (Pimephales promelas) induces thyroid disruption and liver alterations.

Polybrominated diphenyl ether (PBDE) flame retardants are known to affect thyroid hormone (TH) regulation. The TH-regulating deiodinases have been implicated in these impacts; however, PBDE effects on the fish thyroid system are largely unknown. Moreover, the liver as a potential target of PBDE toxicity has not been explored in young fish. This study measured decabromodiphenyl ether (BDE-209) effects on TH regulation by measuring deiodinase activity in juvenile fathead minnows (Pimephales promelas). Dietary accumulations and debromination of BDE-209 were also measured, and the morphology of thyroid and liver tissues was examined. Juvenile fathead minnows (28 days old) received a 28-day dietary treatment of BDE-209 at 9.8 ± 0.16 µg/g of food at 5% of their body weight per day followed by a 14-day depuration period in which they were fed clean food. Chemical analysis revealed that BDE-209 accumulated in tissues and was metabolized to reductive products ranging from penta- to octaBDEs with 2,2',4,4',5,6'-hexabromodiphenyl ether (BDE-154) being the most accumulative metabolite. By day 28 of the exposure, rates of outer and inner ring deiodination (ORD and IRD, respectively) of thyroxine (T4) were each reduced by ∼74% among treatments. Effects on T4-ORD and T4-IRD remained significant even after the 14-day depuration period. Histological examination of treated fish showed significantly increased thyroid follicular epithelial cell heights and vacuolated hepatocyte nuclei. Enlarged biliary passageways may be the cause of the distinctive liver phenotype observed, although further testing is needed. Altogether, these results suggest that juvenile fish may be uniquely susceptible to thyroid disruptors like PBDEs.

[The disruptive effect of N'N-methylene-bis on the function of FRTL-5 cells].

OBJECTIVE: To study the impact of N' N-methylene-bis on thyroglobulin produced by FRTL-5 cells, and to explore the potential of using FRTL-5 cells to screen environmental thyroid hormone disruptors in vitro. METHODS: The FRTL-5 cells were treated with 0.1, 1.0 and 10.0 microg/mL N'N-methylene-bis for 48 hours, respectively. The concentrations of thyroglobulin in the medium of the treated cells were detected by radioimmunoassay. The expression of thyroid peroxidases in the FRTL-5 cells was assessed by enzyme cytochemistry technique. The ultrastructure of the cells was also observed. RESULTS: The FRTL-5 cells treated with 0.1 and 1.0 microg/mL of N' N-methylene-bis produced less thyroglobulin than the controls (P < 0.05). No thyroglobulin was detected with the cells treated with 10.0 microg/mL of N' N-methylene-bis. No difference in the expression of thyroid peroxidases was found between the treated cells and the controls. The treated cells had expanded rough endoplasmic reticulum. CONCLUSION: N' N-methylene-bis disrupts the bio-function of thyroid by damaging the rough endoplasmic reticulum of thyroid follicular cells. FRTL-5 cells can be used for screening thyroid hormone disruptors in vitro.