An overview of the pathogenesis of thyroid autoimmunity

Autoimmune Thyroid Disease and Differentiated Thyroid Carcinoma: A Review of the Mechanisms That Explain an Intriguing and Exciting Relationship

Autoimmune thyroid disease is a complex and highly frequent disease, where a wide variety of genetic, epigenetic and environmental factors (among others) come together and interact, and is characterized by the presence of two clinical outcomes: hypothyroidism (in Hashimoto's thyroiditis) and hyperthyroidism (in Graves-Basedow disease). For its part, differentiated thyroid carcinoma (mainly papillary carcinoma) is the most common type of cancer affecting the thyroid (and one of the most prevalent worldwide). An important co-occurrence between autoimmune thyroid disease and differentiated thyroid carcinoma has been documented. In this article, studies that have evaluated possible associations and relationships between autoimmune thyroid disease and differentiated thyroid cancer are systematically described and summarized. To date, the underlying mechanism that explains this association is inflammation; however, the characteristics and designs of the studies evaluated do not yet allow a causal relationship between the two entities to be established. These aspects have made it difficult to establish "causality" in the continuum of the pathogenesis between both conditions.

Helper T Cell 17 and Regulatory T Cell Levels in Peripheral Blood of Newly Diagnosed Patients with Autoimmune Thyroid Disease: A Meta-Analysis

This article aims to explore associated immune indicators of autoimmune thyroid disease (AITD) through a meta-analysis of published case-control studies on newly diagnosed AITD patients, intending to provide some suggestions for research on the mechanisms of AITD. Six electronic databases were searched for case-control studies on newly diagnosed AITD patients from inception to August 15, 2022. A random-effects model was used to calculate the standardized mean difference (SMD), odds ratio (OR), and 95% confidence interval (95% CI). A total of 26 articles were included in this meta-analysis. Patients with newly diagnosed AITD had higher levels of helper T cell 17 (Th17) (Hashimoto's disease (HT): SMD=2.35, 95% CI: 1.98, 2.72; Graves' disease (GD): SMD=1.61, 95% CI: 1.23, 1.98), lower levels of regulatory T cell (Treg) (HT: SMD=-2.04, 95% CI: -2.67, -1.42; GD: SMD=-1.35, 95% CI: -2.11, -0.58), and lower levels of forkhead box P3 (FoxP3) mRNA (HT: SMD=-2.58, 95% CI: -3.12, -2.05; GD: SMD=-2.13, 95% CI: -2.56, -1.70), compared to the healthy population. In addition, the single nucleotide polymorphism rs3761548 and rs3761549 in the promoter region of FoxP3 showed a higher frequency in the comparison of genotype "CT" only in HT patients than in the healthy population (OR=1.66, 95%CI: 1.18, 2.34). In patients with newly diagnosed AITD, the Th17/Treg ratio imbalance may develop AITD. Monitoring Th17 and Treg levels may become an essential tool to assess the organism's immune homeostasis and hopefully guide clinical diagnosis and treatment.

Selective Silencing of Disease-Associated B Lymphocytes from Hashimoto's Thyroiditis Patients by Chimeric Protein Molecules

Hashimoto's thyroiditis is one of the most common endocrine disorders, affecting up to 20% of the adult population. No treatment or prevention exists except hormonal substitution for hypothyroidism. We hypothesize that it may be possible to selectively suppress anti-thyroglobulin (Tg) IgG antibody-producing B lymphocytes from HT patients by a chimeric protein molecule containing a monoclonal antibody specific for the human inhibitory receptor CR1, coupled to peptide epitopes derived from Tg protein. We expect that this treatment will down-regulate B-cell autoreactivity by delivering a strong inhibitory signal. Three peptides-two epitope-predicted ones derived from Tg and another irrelevant peptide-were synthesized and then coupled with monoclonal anti-human CR1 antibody to construct three chimeric molecules. The binding to CD35 on human B cells and the effects of the chimeric constructs on PBMC and TMC from patients with HT were tested using flow cytometry, ELISpot assay, and immunoenzyme methods. We found that after the chemical conjugation, all chimeras retained their receptor-binding capacity, and the Tg epitopes could be recognized by anti-Tg autoantibodies in the patients' sera. This treatment downregulated B-cell autoreactivity and cell proliferation, inhibited Tg-specific B-cell differentiation to plasmablasts and promoted apoptosis to the targeted cells. The treatment of PBMCs from HT patients with Tg-epitope-carrying chimeric molecules affects the activity of Tg-specific autoreactive B lymphocytes, delivering to them a strong suppressive signal.

Low levels of serum IL-39 are associated with autoimmune thyroid disease

Background

Interleukin (IL)‐39 is a novel member of IL‐12 cytokine family, but its role in autoimmune thyroid diseases (AITD) is unclear. The aim of the present study was to determine serum levels of IL‐39 in Hashimoto's thyroiditis (HT) and Graves' disease (GD) patients.

Methods

A total of 48 patients with HT, 50 patients with GD, and 45 healthy controls (HCs) were recruited for this study. Levels of serum IL‐39 were determined by ELISA.

Results

Compared with HC group, levels of serum IL‐39 in patients with HT (p < 0.05) and GD (p < 0.01) were drastically reduced. Among patients with HT, serum IL‐39 levels had a positive correlation with white blood cell count (WBC) count and free triiodothyronine level. Among patients with GD, the levels of IL‐39 in serum were positively correlated with WBC count and C‐reactive protein levels.

Conclusions

IL‐39 may be a new potential predictor for patients with HT and GD.

Are ethnic differences, urinary iodine status, lead and cadmium exposure associated with thyroid autoimmunity and hypothyroid status? A cross-sectional study

OBJECTIVE

We aimed to evaluate the effects of different ethnicities and potential environmental exposure on the prevalence of thyroid autoimmune status and hypothyroid status.

DESIGN

The data were obtained from two cross-sectional studies.

PARTICIPANTS

2105 participants in Shanghai (Han) and 772 participants in Yunnan Honghe Prefecture (Han, Yi, Miao and Hani), aged 18-75 were enrolled.

METHODS

Participants underwent several checkups, including urinary iodine concentration, blood lead (BPb) and blood cadmium (BCd), thyroid peroxidase antibody (TPOAb), thyroglobulin antibody (TgAb), thyroid stimulating hormone (TSH) as well as thyroid ultrasonography (US). Thyroid autoimmune status was defined as: antithyroid antibody positive (ATA+): TPOAb + or TgAb+; and ATA + and US+: TPOAb + or TgAb + together with characteristic US features.

RESULTS

The standardised prevalence of thyroid autoimmune positivity in Yunnan were higher than those in Shanghai (TPOAb+: 13.56% vs 8.27%, p<0.001; TgAb+: 9.28% vs 7.09%, p=0.045; ATA+: 16.96% vs 11.10%, p<0.001; ATA + and US+: 8.96% vs 6.64%, p=0.036). For urinary iodine-to-creatinine ratio (UI/Cr), compared with the level of 100.00-199.99 µg/g, the level of ≥300.00 µg/g had a 1.5-fold risk for ATA + and US+ (OR 1.455, p=0.041). The levels of 200.00-299.99 µg/g and ≥300.00 µg/g were positively associated with hypothyroid status (OR 1.509, p=0.002 and OR 1.338, p=0.043). Compared with the first quartiles, the fourth quartiles of BPb were positively associated with TPOAb+: (OR 1.637, p=0.006), ATA+ (OR 1.435, p=0.025), ATA + and US+ (OR 1.641, p=0.013), hypothyroid status (OR 1.467, p=0.013) and TSH levels (B 0.092, p=0.021). The fourth quartile of BCd was positively associated with the prevalence of ATA+ (OR 1.427, p=0.036).

CONCLUSIONS

Higher levels of UI/Cr, BPb and BCd may be associated with thyroid autoimmunity and hypothyroid status.

Bidirectional Mendelian Randomization Analysis for Vitamin D and Thyroid Peroxidase Antibody

PURPOSE

Whether Vitamin D deficiency or insufficiency is associated with thyroid autoimmunity was debated for long time. This study was still to explore the causal relationship of 25 (OH) D with a thyroid peroxidase antibody (TPOAb).

METHODS

The data were obtained from a cross-sectional study, SPECT-China study, which was performed in 23 sites in East China during 2014 to 2016. 10636 participants were finally included in this study. Genotyped four 25 (OH) D-related and four TPOAb-associated single nucleotide polymorphisms (SNPs) created their genetic risk scores (GRS). Bidirectional mendelian randomization (MR) analysis was used in this study.

RESULTS

25 (OH) D GRS was significantly associated with 25 (OH) D (B -0.093, 95% CI -0.111, -0.074) and TPOAb level (B 0.067, 95% CI 0.002 to 0.132). TPOAb GRS was significantly associated with TPOAb concentration (B 0.345, 95% CI 0.135 to 0.556), but not 25 (OH) D (B -0.030, 95% CI -0.091 to 0.030). Using 25 (OH) D_GRS as instrumental variable in the MR analysis, a causal relationship of genetically determined 25 (OH) D with increased TPOAb concentration (B -0.720, 95% CI -1.429 to -0.012). No relation was found between genetically instrumented TPOAb and 25 (OH) D.

CONCLUSION

A higher VD_GRS was associated with higher risk of increased TPOAb concentration, which supports a causal association between decreased vitamin D and increased concentration of TPOAb in an eastern Chinese population.

Association between IL-18 gene polymorphisms and Hashimoto thyroiditis

BACKGROUND

Hashimoto's thyroiditis (HT), which is also called lymphocytic thyroiditis, is the most frequent autoimmune thyroid disease (AITD), in which T helper-1 lymphocytes mediate the disease. IL-18 is expressed in thyroid follicular cells (TFCs) during HT. The findings of studies aimed at investigating the relationship between IL-18 and HT are highly contradictory. In this study, we aimed to investigate the association between IL-18 gene polymorphisms and HT.

METHODS AND RESULTS

The study included 97 patients diagnosed with HT and 86 volunteers in the healthy control group. The IL18-607C/A (rs1946518) and -137G/C (rs187238) genotypes were determined using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. No significant difference in the mean age or sex was observed between the groups (p = 0.763 and p = 0.658, respectively). The -137 IL18 CG genotype was more frequent in HT patients than in controls. In HT patients, the risk of the IL-18 CG genotype was more than 2.237 times higher (OR 2.237%95 Cl 1.195-4.187, p = 0.039) than that of the G/G genotype. Additionally, the -607 AC genotype was more frequent in the control group than in the HT group (in individuals with the IL18 CG genotype).

CONCLUSIONS

According to our results, the CG genotype might be a risk factor for HT. Conversely, there is a possibility that the AC genotype plays a protective role against the condition. However, further studies will contribute to new solutions by revealing the molecular and cellular mechanisms of HT.

Association of Phthalate Exposure with Thyroid Function and Thyroid Homeostasis Parameters in Type 2 Diabetes

AIMS

Phthalates, which are recognized environmental endocrine-disrupting chemicals, are associated with thyroid hormone disruption. We aimed to evaluate the relationship of phthalate metabolites with thyroid function and thyroid homeostasis parameters in type 2 diabetes and to explore whether thyroid autoimmunity status and metformin, the most common antidiabetic drug, may influence such associations.

METHODS

Concurrent urine and blood samples were collected from 639 participants with type 2 diabetes in the METAL (Environmental Pollutant Exposure and Metabolic Diseases in Shanghai) study. We measured urinary concentrations of thirteen phthalate metabolites along with serum levels of thyroid-stimulating hormone (TSH), total T₄ and T₃, free T₄ (FT₄) and T₃ (FT₃), thyroid peroxidase antibody (TPOAb), and thyroglobulin antibody (TgAb). Four parameters of thyroid homeostasis, including the sum activity of step-up deiodinases (SPINA-GD), thyroid secretory capacity (SPINA-GT), Jostel's TSH index (TSHI), and thyrotroph thyroid hormone resistance index (TTSI), were also calculated.

RESULTS

Among all participants, after full adjustment, multivariable regression analysis showed that some urine phthalate metabolites were negatively associated with TSH, TSHI, and TTSI levels and positively associated with FT₃, T₃, SPINA-G_D, and SPINA-G_T levels. None of the urine phthalate metabolites exhibited a significant association with thyroid autoimmunity. The associations of phthalate metabolites with thyroid function and thyroid homeostasis parameters differed based on thyroid autoantibody and metformin treatment status.

CONCLUSIONS

Urinary phthalate metabolites may be associated with thyroid function and thyroid homeostasis parameters among participants with type 2 diabetes. Furthermore, our present study suggested that thyroid autoantibody status and metformin treatment status are potential mediators of such associations.

Immunomodulatory effect of vitamin D and its potential role in the prevention and treatment of thyroid autoimmunity: a narrative review

The main role of vitamin D is to control mineral homeostasis. However, recent studies suggested the existence of a number of extraskeletal effects. Among the latter, preclinical studies provided consistent data on the involvement of vitamin D in innate and adaptive immunity and autoimmunity. Molecular biology studies showed that both vitamin D receptor and vitamin D enzymatic complexes are expressed in a large number of cells and tissues unrelated to mineral homeostasis. In contrast, only a few randomized clinical trials in humans investigated the possible role of vitamin D in the prevention or treatment of immunological disorders. In this regard, low serum vitamin D levels have been reported in observational trials in human autoimmune disorders. The aim of the present paper was to review the potential implications of vitamin D in immune modulation, with special focus on thyroid autoimmune disorders.

Toxic Effects of the Mixture of Phthalates and Bisphenol A-Subacute Oral Toxicity Study in Wistar Rats

Phthalates and bisphenol A, classified as endocrine disruptors, have weak estrogenic, anti-androgenic properties, and affect thyroid hormone regulation. The aim of this study on male rats was to compare the subacute toxic effects of low doses of single compounds (bis (2 -ethylhexyl) phthalate (DEHP), dibutyl phthalate (DBP), and bisphenol A (BPA)) with the effects of their mixture through different biochemical, hormonal, and hematological parameters. Rats were divided into five experimental groups: Control (corn oil), DEHP (50 mg/kg b.w./day), DBP (50 mg/kg b.w./day), BPA (25 mg/kg b.w./day), and MIX (50 mg/kg b.w./day DEHP + 50 mg/kg b.w/day DBP + 25 mg/kg b.w./day BPA). Animals were sacrificed after 28 days of oral treatment and blood was collected for further analysis. The results demonstrated that the mixture produced significant changes in lipid profile, liver-related biochemical parameters, and glucose level. Furthermore, the opposite effects of single substances on the thyroxine level have been shown in comparison with the mixture, as well as a more pronounced effect of the mixture on testosterone level. This study contributes to the body of knowledge on the toxicology of mixtures and gives one more evidence of the paramount importance of mixture toxicity studies, especially in assessing the endocrine disruptive effects of chemicals.

Association between Uranium Exposure and Thyroid Health: A National Health and Nutrition Examination Survey Analysis and Ecological Study

Besides specific, incidental radiation exposure, which has been associated with increased thyroid cancer risk, the effects of exposure to background radiation from uranium, a naturally occurring, radioactive, and ubiquitous element, on the thyroid gland has not been widely studied. We therefore investigated the association between uranium exposure and thyroid health in the US. Using the National Health and Nutrition Examination Survey (NHANES), we assessed the association between urinary uranium levels and thyroid-related antibodies, including thyroglobulin antibodies (TgAb) and anti-thyroid peroxidase (anti-TPO), in the general population. Secondly, we performed an ecological study of age-adjusted thyroid cancer incidence rates per state and sources of uranium exposure. We included 3125 eligible participants from the NHANES and found a significant association between increased TgAb and increased urinary uranium levels when analyzed as quartiles (p = 0.0105), while no association was found with anti-TPO. In addition, although no significant correlation was found in the ecological study, certain states had high age-adjusted thyroid cancer incidence rates and a high number of uranium activity locations and high uranium concentrations in water. The present study suggests that uranium exposure may affect thyroid health, which warrants increased sampling of soil and water in high-risk states.

Autoimmune diseases in Turner syndrome: an overview

Turner syndrome (TS) results from a sex-chromosomal anomaly characterized by presence of one normal X chromosome and the loss of the second X-chromosome in phenotypic females. Autoimmunity has been recognized as one of the more prominent characteristics of TS. The risk of autoimmune diseases in patients with TS is approximately twice as high as in the general female population. The spectrum includes, Hashimoto’s thyroiditis, coeliac disease (CD), type 1 diabetes (T1DM), alopecia areata, inflammatory bowel disease, juvenile rheumatoid arthritis and some cutaneous disorders as vitiligo and Halo nevus. This review will address the autoimmune disorders associated with TS, their pathophysiologic mechanisms and clinical characteristics. (www.actabiomedica.it)

Effects of vitamin D supplements on frequency of CD4+ T-cell subsets in women with Hashimoto's thyroiditis: a double-blind placebo-controlled study

BACKGROUND

Vitamin D is a modulator of immune functions. Investigations on the mechanisms of vitamin D action and pathogenesis of Hashimoto's thyroiditis (HT) have revealed that vitamin D can reduce damages to thyroid cells caused by autoreactive immune cells.

METHODS

Totally, 48 female patients with HT disease were introduced to the study by endocrinologists. Patients were divided into two major groups of 24 individuals and treated weekly with 50,000 IU of cholecalciferol (vitamin D group) or placebo (placebo group) using oral administration for 3 months. Eventually, 17 of the 24 patients in each group finished the study. Before and after supplementation, frequencies of Th1, Th17, Th2 and Tr1 cells and mean fluorescent intensity (MFI) of the associated cytokines, including IFN-γ, IL-17, IL-4 and IL-10, were assessed using flow cytometry. Furthermore, gene expression of IL-10 was assessed using real-time PCR.

RESULTS

Results of this study showed that cholecalciferol supplementation caused a significant decrease in Th17/Tr1 ratio. The proportion and MFI of Th1, Th2, Tr1 and Th17 cells included no significant changes in vitamin D group, compared to those in placebo group. Expression rate and MFI of IL-10 increased in both groups. This increase was higher in vitamin D group than placebo group with no significance.

CONCLUSIONS

In this novel preliminary clinical trial study, supplementation with cholecalciferol in HT patients for 3 months changed the balance of CD4⁺ T-cell subsets to improve the disease control. However, further studies are necessary to investigate effects of vitamin D on immune functions in HT patients.

Analysis of Regulatory T Cell Subsets and Their Expression of Helios and PD-1 in Patients with Hashimoto Thyroiditis

Hashimoto thyroiditis (HT) is an autoimmune disease that presumably arises consequent to loss of immune tolerance to autoantigen in thyroid. Regulatory T cells (Tregs) are considered to play a vital role in maintaining the immune balance, as they own intensive suppressive function. This study was undertaken to analyze numbers of Tregs and their expressions of Helios and PD-1 in HT patients. It also aimed to explore the relationship of these with thyroid function and specific autoantibodies. Peripheral blood mononuclear cells (PBMCs) were extracted from blood of 20 healthy controls (HC) and 42 HT patients with varying thyroid functions (10 overt hypothyroidism, 12 subclinical hypothyroidism, and 20 euthyroidism). We performed flow cytometry analysis in PBMCs to detect CD4⁺CD25⁺Foxp3⁺Tregs and their subsets, including CD45RO⁺Foxp3^high activated Treg cells (aTregs), CD45RO^-Foxp3^low resting Tregs cells (rTregs), and CD45RO⁺Foxp3^low secreting Treg cells (sTregs), as well as the expression of Helios and PD-1 on these cells. The results showed that the percentage of Tregs, aTregs was significantly lower in HT patients and it showed inverse correlation to thyroid function states, in comparison with these in healthy controls. In addition, patients with HT showed decreased expression of Helios in aTregs, while having increased expression of PD-1 in Tregs and sTregs. The levels of Tregs, aTregs, and Helios expressing aTregs were all negatively correlated with antithyroid antibodies. In conclusion, the deficiency of Tregs frequency and aberrant expressions of Helios and PD-1 may possibly contribute to thyroid immune damage in HT.

Hashimoto Thyroiditis and Dyslipidemia in Childhood: A Review

Hashimoto autoimmune thyroiditis (AIT) is the most common cause of acquired hypothyroidism in the pediatric population. Development of AIT is mediated mainly by cellular immune response directed toward thyroid autoantigens, leading to inflammation and impaired function of thyroid gland. Both thyroid dysfunction and inflammation affect the metabolism of plasma lipoproteins. The alterations in lipid profile worsen with the advancement of hypothyroidism, ranging from discrete changes in euthyroid AIT patients, to atherogenic dyslipidemia in the overt hypothyroidism. In this review, characteristics of dyslipidemia in pediatric AIT patients, and the consequences in respect to the risk for cardiovascular disease (CVD) development are discussed. Additionally, benefit of L-thyroxine treatment on serum lipid profile in pediatric AIT patients is addressed. Finally, potential usefulness of novel lipid biomarkers, such as proprotein convertase subtilisin/kexin type 9 (PCSK9), non-cholesterol sterols, low-density lipoprotein particle size and number, and high-density lipoprotein structure and functionality in AIT patients is also covered. Further longitudinal studies are needed in order to elucidate the long-term cardiovascular outcomes of dyslipidemia in pediatric patients with Hashimoto AIT.

Are Thyroid Autoimmune Diseases Associated with Cardiometabolic Risks in a Population with Normal Thyroid-Stimulating Hormone?

Background

The interrelation between thyroid autoimmunity and cardiovascular risks is complex and has not been confirmed. This study aimed at evaluating whether there exists a relationship between thyroid autoimmune diseases (AITDs) and cardiometabolic risks in a large population with normal thyroid-stimulating hormone (TSH) levels.

Methods

The data was obtained from a cross-sectional study (SPECT-China study). This study enrolled 9082 subjects (3948 males and 5134 females) above 18 years with normal TSH levels. AITD was defined according to the positivity of TPOAb and TgAb as well as thyroid ultrasonography (US) findings.

Results

After full adjustment, TPOAb and/or TgAb positivity (TPO/TgAb (+)) was significantly associated with higher BMI, waist circumference (WC), and HbA1c only in women (P = 0.004, 0.026 and 0.032, respectively), while both TPO/TgAb positivity and US positivity (TPO/TgAb (+) and US (+)) were positively associated with BMI and WC in both genders (P = 0.002 and 0.020 in men; P < 0.001and <0.001 in women). TPO/TgAb (+) and US (+) were positively associated with HOMA-IR in women (P = 0.021) as well. Binary logistic analysis showed that AITDs had increased risks of central obesity, hyperlipidemia, and metabolic syndrome only in women (all P < 0.05). Moreover, TPO/TgAb (+) and US (+) were associated with an increased risk of obesity for both genders (P = 0.014 in men and P = 0.006 in women).

Conclusions

Thyroid autoimmunity was positively associated with HbA1c, HOMA-IR, obesity, central obesity, hyperlipidemia, and metabolic syndrome, especially in women. This highlighted that AITDs may be potential risk factors for cardiometabolic disorders even if one's TSH was within the reference range.

The association of non-alcoholic fatty liver disease with thyroid peroxidase and thyroglobulin antibody: A new insight from SPECT-China study

Non-alcoholic fatty liver disease (NAFLD) has been studied with inflammation and immune, but the link with thyroid autoimmunity is unreported. This study aimed to explore the direct association of NAFLD with thyroid autoimmune disease (AITD) among participants with normal thyroid stimulating hormone (TSH) levels. The data were obtained from a cross-sectional study (SPECT-China). A total of 7982 participants were enrolled. Participants underwent several checkups including peroxidase antibody (TPOAb), thyroglobulin antibody (TgAb), thyroid, and liver ultrasonography (US). The prevalence of NAFLD was higher in TPOAb and/or TgAb positive [TPO/TgAb (+)] group and TPOAb and/or TgAb together with US positive [TPO/TgAb (+) and US (+)] group for both genders. After full adjustment, binary logistic analysis showed the presence of NAFLD was positively associated with the serum level of TPOAb in men (p < .001) and TgAb in women (p = .001). Both TPO/TgAb (+) and TPO/TgAb (+) and US (+) were associated with an increased risk of NAFLD in both genders [TPO/TgAb (+): odds ratio (OR) 1.474, 95% confidence interval (CI) 1.102, 1.970 in men and OR 1.308, 95%CI 1.061, 1.612 in women; TPO/TgAb (+) and US (+): OR 1.796, 95%CI 1.143, 2.820 in men and OR 1.380, 95%CI 1.058, 1.801 in women]. Thus, we got a conclusion that the prevalence of NAFLD was positively associated with the level and the positivity of TPOAb and TgAb among participants with normal TSH levels. This is the first report suggesting that there might exist common pathways in the pathogenesis of NAFLD and thyroid autoimmunity.

Estrogen receptor β activation stimulates the development of experimental autoimmune thyroiditis through up-regulation of Th17-type responses

Estrogens play important roles in autoimmune thyroiditis, but it remains unknown which estrogen receptor (ER) subtype mediates the stimulatory effects. Herein we treated ovariectomized mice with ERα or ERβ selective agonist followed by thyroglobulin-immunization to induce experimental autoimmune thyroiditis (EAT), and observed the aggravation of EAT after diarylpropionitrile (DPN, ERβ selective agonist) administration. The mRNA levels of interleukin(IL)-17A, IL-21 and RORγt and percentages of T helper (Th) 17 cells were up-regulated in the splenocytes of DPN-treated mice. Activated ERβ was found directly binding to IL-17A and IL-21 gene promoters, and also indirectly promoting IL-21 and RORγt gene transcription through interaction with NF-κB. The expressions of co-stimulatory molecules were increased on antigen-presenting cells (APCs) after DPN administration. It suggests that ERβ is the predominant ER subtype responsible for EAT development, and its activation may enhance Th17-type responses through genomic pathways and alteration of APCs' activities.

Physiological low-dose oestrogen promotes the development of experimental autoimmune thyroiditis through the up-regulation of Th1/Th17 responses

Previous studies have reported a preponderance of autoimmune thyroiditis (AIT) in females, but the detailed mechanisms have not been elucidated. In this study, we explored the effects of oestrogen on experimental AIT (EAT) and its potential mechanisms in an ovariectomised mouse model through the supplementation of high (equivalent to the level during pregnancy) or low (equivalent to the level at the oestrus stage) doses of oestradiol (E2). We found that EAT incidence, the intrathyroidal inflammatory score, serum anti-thyroglobulin IgG2b levels, splenic mRNA expression of Th1- and Th17-specific transcription factors and typical cytokines and the proportion of IL-12-producing dendritic cells were significantly increased in EAT mice treated with low-dose E2 compared with those in the control group. However, they were not changed when administered with high-dose E2. These findings indicate that low physiological levels of E2 can stimulate the occurrence and development of EAT through the up-regulation of Th1/Th17 responses.

Oral exposure to dibutyl phthalate exacerbates chronic lymphocytic thyroiditis through oxidative stress in female Wistar rats

Chronic lymphocytic thyroiditis (CLT) is a common autoimmune disorder. The possible pathogenic role and mechanism of dibutyl phthalate (DBP) in CLT is still controversial. Experiments were conducted after 35-days of oral exposure to the three concentrations of DBP or saline, and three immunizations with thyroglobulin (TG). Healthy female Wistar rats were randomly divided into ten exposure groups (n = 8 each): (A) saline control, (B) 0.5 mg/kg/d DBP, (C) 5 mg/kg/d DBP, (D) 50 mg/kg/d DBP, (E) TG-immunized group, (F) TG- combined with 0.5 mg/kg/d DBP, (G) TG- combined with 5 mg/kg/d DBP, (H) TG- combined with 50 mg/kg/d DBP, (I) TG- combined with 50 mg/kg/d DBP plus 100 mg/kg/d vitamin C; (J) 100 mg/kg/d vitamin C. We showed that oral exposure DBP can aggravate CLT in rats. This deterioration was concomitant with increased thyroid auto antibodies, Th1/Th2 imbalance and Th17 immune response, activated pro-inflammatory and apoptosis pathways, and increased thyroid dysfunction in rats. Our results also suggested that DBP could promote oxidative damage. The study also found that vitamin C reduced the levels of oxidative stress and alleviated CLT. In short, the study showed that DBP exacerbated CLT through oxidative stress.

A Higher Ratio of Estradiol to Testosterone Is Associated with Autoimmune Thyroid Disease in Males

BACKGROUND

Autoimmune thyroid disease (AITD) is highly prevalent. Although AITD is less common in males, it is unclear whether estradiol (E₂) combined with total testosterone (T) contributes to the prevalence of AITD. This study evaluated the association between the E₂/T ratio and the prevalence of AITD in males.

METHODS

The data were obtained from a cross-sectional population-based study, the SPECT-China study, 2014-2015. A total of 4109 males ≥18 years of age were enrolled in this study. Participants underwent several checkups, which included assays of serum E₂, T, thyroid peroxidase antibody (TPOAb), and thyroglobulin antibody (TgAb) levels, as well as thyroid ultrasonography (US). AITD was defined based on the presence of TPOAb and TgAb levels, and the presence of thyroid US findings.

RESULTS

Overall, the prevalence of positivity for TPOAb and/or TgAb (TPO/TgAb[+]) was 11.02%, and the positivity for TPOAb and/or TgAb together with US (TPO/TgAb[+] and US[+]) was 4.58%. The E₂/T ratio levels were significantly higher in the TPO/TgAb(+) group and the TPO/TgAb(+) and US(+) group (7.91 ± 8.03 vs. 7.19 ± 10.30, p = 0.003; 8.78 ± 11.26 vs. 7.19 ± 10.30, p = 0.001) compared to the TPO and TgAb(-) group. The prevalence of TPO/TgAb(+) and US(+) significantly increased with an increasing E₂/T ratio (p = 0.013). Binary logistic analysis showed that increased E₂/T ratio levels were associated with an increased risk of AITD (TPO/TgAb[+]: odds ratio = 1.35, p = 0.002; TPO/TgAb[+] and US[+]: odds ratio = 1.48, p = 0.006).

CONCLUSIONS

AITD is highly prevalent in males in China. Higher E₂/T ratios were significantly associated with AITD among males. Further studies will be needed to assess whether there is a causal relationship between E₂/T ratios and AITD.

Imbalances in T Cell-Related Transcription Factors Among Patients with Hashimoto's Thyroiditis

OBJECTIVES

Imbalances in effector T cell functioning have been associated with a number of autoimmune diseases, including Hashimoto's thyroiditis (HT). Differentiation of effector T helper (Th) 1, Th2, Th17 and regulatory T cell (Treg) lymphocytes is regulated by transcription factors, including Th1-specific T box (T-bet), GATA binding protein-3 (GATA₃), retinoid-related orphan receptor (ROR)-α and forkhead box P3 (FOXP3). This study aimed to investigate Th1/Th2, Th1/Treg, Th2/Treg and Th17/Treg balances at the level of these transcription factors.

METHODS

This study took place between October 2015 and August 2016. Peripheral blood mononuclear cells were collected from a control group of 40 healthy women recruited from the Zahedan University of Medical Sciences, Zahedan, Iran, and a patient group of 40 women with HT referred to the Hazrat Ali Asghar Hospital, Zahedan. Total ribonucleic acid extraction was performed and the gene expression of transcription factors was quantitated using a real-time polymerase chain reaction technique.

RESULTS

Expression of T-bet and GATA₃ was significantly elevated, while FOXP3 expression was significantly diminished among HT patients in comparison with the controls (P = 0.03, 0.01 and 0.05, respectively). Expression of RORα was higher among HT patients, although this difference was not significant (P = 0.15). Expression of T-bet/FOXP3, GATA₃/FOXP3 and RORα/FOXP3 ratios were increased among HT patients in comparison with the controls (P <0.02, <0.01 and <0.01, respectively).

CONCLUSION

These results indicate that HT patients have imbalances in Th1/Treg, Th2/Treg and Th17/Treg lymphocytes at the level of the transcription factors, deviating towards Th1, Th2 and Th17 cells. Correction of these imbalances may therefore be therapeutic.

Thyroid Autoimmunity: Role of Anti-thyroid Antibodies in Thyroid and Extra-Thyroidal Diseases

Autoimmune diseases have a high prevalence in the population, and autoimmune thyroid disease (AITD) is one of the most common representatives. Thyroid autoantibodies are not only frequently detected in patients with AITD but also in subjects without manifest thyroid dysfunction. The high prevalence raises questions regarding a potential role in extra-thyroidal diseases. This review summarizes the etiology and mechanism of AITD and addresses prevalence of antibodies against thyroid peroxidase, thyroid-stimulating hormone receptor (TSHR), and anti-thyroglobulin and their action outside the thyroid. The main issues limiting the reliability of the conclusions drawn here include problems with different specificities and sensitivities of the antibody detection assays employed, as well as potential confounding effects of altered thyroid hormone levels, and lack of prospective studies. In addition to the well-known effects of TSHR antibodies on fibroblasts in Graves' disease (GD), studies speculate on a role of anti-thyroid antibodies in cancer. All antibodies may have a tumor-promoting role in breast cancer carcinogenesis despite anti-thyroid peroxidase antibodies having a positive prognostic effect in patients with overt disease. Cross-reactivity with lactoperoxidase leading to induction of chronic inflammation might promote breast cancer, while anti-thyroid antibodies in manifest breast cancer might be an indication for a more active immune system. A better general health condition in older women with anti-thyroid peroxidase antibodies might support this hypothesis. The different actions of the anti-thyroid antibodies correspond to differences in cellular location of the antigens, titers of the circulating antibodies, duration of antibody exposure, and immunological mechanisms in GD and Hashimoto's thyroiditis.

Pathogenesis of thyroid autoimmune disease: the role of cellular mechanisms

Hashimoto's thyroiditis (HT) and Graves' disease (GD) are two very common organ-specific autoimmune diseases which are characterized by circulating antibodies and lymphocyte infiltration. Although humoral and cellular mechanisms have been classically considered separately in the pathogenesis of autoimmune thyroid diseases (AITD), recent research suggests a close reciprocal relationship between these two immune pathways. Several B- and T-cell activation pathways through antigen-presenting cells (APCs) and cytokine production lead to specific differentiation of T helper (Th) and T regulatory (Treg) cells. This review will focus on the cellular mechanisms involved in the pathogenesis of AITD. Specifically, it will provide reasons for discarding the traditional simplistic dichotomous view of the T helper type 1 and 2 pathways (Th1/Th2) and will focus on the role of the recently characterized T cells, Treg and Th17 lymphocytes, as well as B lymphocytes and APCs, especially dendritic cells (DCs).

Rheumatic symptoms in autoimmune thyroiditis

Autoimmune thyroiditis (ATD) is generally regarded as a classic example of single organ autoimmunity with a high association with endocrine thyroid disorders. However, it is closely associated with several autoimmune diseases including rheumatologic syndromes and has long been known to have several rheumatic manifestations particularly in association with hypothyroidism. More recently, it has also been implicated in rheumatologic syndromes in the absence of hypothyroidism or subclinical hypothyroidism. There is also an emerging body of evidence that ATD is highly linked to chronic generalized pain syndromes including fibromyalgia. This review examines the rheumatic symptoms of ATD described in the current literature and discusses the clinical relevance of ATD in general rheumatology.

Leptin in autoimmune diseases

The past twenty years of research on leptin has provided crucial information on the link between metabolic state and immune system function. Adipocytes influence not only the endocrine system but also the immune response, through several cytokine-like mediators known as adipokines, which include leptin. Initially described as an antiobesity hormone, leptin has subsequently been shown also to influence hematopoiesis, thermogenesis, reproduction, angiogenesis, and more importantly immune homeostasis. As a cytokine, leptin can affect thymic homeostasis and the secretion of acute-phase reactants such as interleukin-1 (IL-1) and tumor-necrosis factor-alpha (TNF-α). Leptin links nutritional status and proinflammatory T helper 1 (Th1) immune responses and the decrease in leptin plasma concentration during food deprivation leads to impaired immune function. Conversely, elevated circulating leptin levels in obesity appear to contribute to the low-grade inflammatory background which makes obese individuals more susceptible to increased risk of developing cardiovascular diseases, diabetes, or degenerative disease including autoimmunity and cancer. In this review, we provide an overview of recent advances on the role of leptin in the pathogenesis of several autoimmune disorders that may be of particular relevance in the modulation of the autoimmune attack through metabolic-based therapeutic approaches.

An overview of the pathogenic mechanisms of autoimmune thyroid disorders

<title>Abstract Objectives, recent epidemiologic studies in humans suggest an increased prevalence of thyroiditis associated with the excessive administration of iodine. More than three times of recommended daily intake of iodine was observed among people in North America. These people generally presented higher level of anti-thyroglobulin antibody, anti-thyroperoxidase antibody, serum thyroid-stimulating hormone and exacerbation of lymphocytic infiltration in thyroid, which indicated the overconsumption of iodine could induce hypothyroidism and enhance the autoimmune response. However, the precise mechanism of excessive iodine intake induced autoimmune thyroid disease remains largely unknown.</p><p>Over half a century has elapsed since the 1956 identification of thyroglobulin antibodies and the devising of the first experimental model of autoimmune thyroiditis. Since then an incredible amount of experimental work has led to an ever deeper understanding of the nature of thyroid auto-antigens, the main immune mechanisms responsible for Hashimoto's thyroiditis and graves’ disease, their genetics, and therir environmental risk factor. Yet, in the majority of genetically predisposed people the individual trigger of thyroid autoimmunity remains obscure. Similarly, effective prevention strategies still remain to be established and, hopefully, will be the target of future studies.</p>

Endocrine autoimmunity in Turner syndrome

BACKGROUND

Turner syndrome is caused by numeric and structural abnormalities of the X chromosome. An increased frequency of autoimmunity as well as an elevated incidence of autoantibodies was observed in Turner patients. The aim of this study was to conduct a retrospective analysis of the incidence of autoimmunity in 66 Italian patients affected by Turner syndrome.

METHODS

Sixty-six unselected and consecutive Italian Turner patients were recruited. The association between age, karyotype and the presence of clinical/pre-clinical autoimmune disorders and of autoantibodies was examined.

RESULTS

Out of the 66 Turner patients, 26 had thyroid autoimmune disorders (39.4%), 14 patients had Hashimoto's thyroiditis with clinical or subclinical hypothyroidism (21.2%) and 12 patients had circulating anti-thyroid antibodies, echographic pattern of diffuse hypoechogenicity and normal thyroid hormone levels (18.2%). None were affected by Graves' disease. We analyzed the overall incidence of thyroid autoimmunity within the 3 different age groups 0-9.9, 10-19.9 and 20-29.9 years. No statistically significant difference was observed in the incidence of thyroid autoimmunity within the age-groups (χ2-test p > 0.05).Out of the 66 patients, 31 patients had the 45,X karyotype; within this first group 14 out of 31 patients were affected by autoimmune thyroid disease. A second group of 29 patients included 19 patients with mosaicism, 5 patients with deletions and 5 patients with ring chromosome; out of these 29 patients 7 were affected by autoimmune thyroid disease. A third group included 6 patients with X isochromosome; 5 out of 6 were affected by autoimmune thyroid disease. A statistically significant difference in the frequency of thyroid autoimmunity within the different karyotype groups was observed (χ2-test p = 0.0173).When comparing the X isochromosome group with the pooled group of other karyotypes, of note, the frequency of thyroid autoimmunity was statistically higher in the X isochromosome group (Fisher exact test p = 0.0315).

CONCLUSIONS

Our data confirm a high frequency of thyroid autoimmunity in Italian Turner patients. Patients with X isochromosome are more prone to develop thyroid autoimmunity. Further, an early assay of autoantibodies and monitoring thyroid hormones is fundamental for detecting hypothyroidism earlier and start adequate replacement therapy.