Effects of Thyroid Autoimmunity on Early Atherosclerosis in Euthyroid Girls with Hashimoto's Thyroiditis

MYOFIBROBLASTS HINDER RECOVERY OF HASHIMOTO THYROIDITIS IN THE ULTRASTRUCTURAL LEVEL

Background

Hashimoto thyroiditis (HT) is an autoimmune disorder associated with hypothyroidism. Lymphocyte infiltration leading to thyroid follicular cell destruction is counteracted by increased collagen production, deposition and scarring. However, only recently a specific subpopulation of modified fibroblasts with contractile properties, namely "myofibroblasts" (MFBs) have been linked to HT.

Aim

Our ultrastructural study aims to delineate the presence and contribution of MFBs to the fibrotic milieu of HT.

Material and Methods

Tissue biopsies were obtained from 5 HT-diagnosed patients and specimens were examined using a Transmission Electron Microscope (TEM).

Results

Histopathological examination indicated extensive microvilli atrophy and atypical vacuolations of the thyroid follicular cells in the HT samples. In addition to interstitial extravasated lymphocytes, capillaries were encircled by MFBs (mean distance from lumen 1.248± 0.43µm) with the characteristic electron-dense α-smooth muscle actin (α-SMA), confirmable in higher magnifications. Myofibroblastic projections were found to have significantly higher representation near the capillary lumen compared to the impaired endothelial lining (P < 0.01).

Conclusion

Our TEM findings suggest that the intrusion of endothelia by myofibroblastic projections can be a significant factor towards the malfunction of follicular cells in HT patients and offer a paradigmal understanding of the ultrastructural interactions that may underlie the HT pathology.

EVALUATION OF FETUIN-A LEVELS IN THE EARLY STAGE OF AUTOIMMUNE THYROIDITIS

Context

Fetuin-A is a multifunctional protein and is known to be related to metabolic syndrome, vascular calcification, and inflammation.

Objective

The purpose of this study was to determine the effects of serum fetuin-A levels on autoimmune thyroiditis without thyroid dysfunction.

Subjects and Methods

This prospective case-control study was performed at the pediatric endocrinology outpatient clinic of a tertiary health institution in Istanbul, Turkey between July 2022 and October 2022. Serum fetuin-A levels were assessed using a human fetuin-A enzyme-linked immunosorbent assay (ELISA) kit (Elabscience Biotechnology, Houston, TX, USA).

Results

The study included 86 participants, of which 42 were patients with Hashimoto's thyroiditis (HT) and 44 were controls. Autoimmune thyroiditis without thyroid dysfunction was found to be related to lower plasma fetuin-A levels. There were no statistically significant differences in the neutrophil-to-lymphocyte ratio, fasting blood glucose level, insulin level, or HOMA-IR (Homeostatic Model Assessment for Insulin Resistance) value between the groups. A fetuin-A level of ≤162.22 µg/mL (80.95% sensitivity and 70.45% specificity) was found to support the identification of autoimmune thyroiditis.

Conclusions

The findings of our study suggest that autoimmune thyroiditis without thyroid dysfunction is related to lower fetuin-A levels. Low fetuin-A levels are known to be associated with an increased risk of cardiovascular disease, suggesting that careful monitoring is required in patients with low fetuin-A levels.

Advanced glycation end products and their soluble receptor (sRAGE) in patients with Hashimoto's thyroiditis on levothyroxine substitution

Background

Advanced glycation end products (AGEs) are heterogenous group of irreversible chemical moieties originated from non-enzymatic glycation and oxidation of proteins, nucleic acids, and lipids. The engagement of AGEs with their chief cellular receptor (RAGE) activates a myriad of signaling pathways contributing to the progression of chronic diseases like autoimmune thyroiditis, type 2 diabetes mellitus and its complications. Soluble RAGE (sRAGE) prevents AGE-RAGE interaction in a competitive manner.

Objective

We investigated the association between serum AGE, sRAGE and thyroid function in 73 Hashimoto thyroiditis patients (HT) on levothyroxine substitution, and in 83 age, BMI and gender-matched healthy controls.

Methods

The serum AGEs levels were determined by autofluorescence on a multi-mode microplate reader, and the serum sRAGE levels by ELISA method.

Results

Mean AGE level was lower (10.71 vs 11.45 AU/µg protein; p=0.046), while mean sRAGE level was higher (923 vs 755 pg/mL; p<0.0005) in the serum of HT patients than the controls. AGE correlated with age, while sRAGE correlated negatively with BMI in both groups. We found negative correlation between AGE and fT3 levels (r=-0.32; p=0.006) and sRAGE and TSH levels (r=-0.27; p=0.022) in HT patients, while we failed to find association between AGE, sRAGE and parameters of thyroid function in the control group. Median AGE/sRAGE ratio was lower in HT patients than in controls (2.4, IQR 1.9 - 3.1 vs 3.3, IQR 2.3 - 4.1 AU/pg; p < 0.001). In HT patients, the AGE/sRAGE ratio correlated positively with BMI and correlated negatively with fT3.

Conclusion

According to our results in HT patients lower TSH and higher fT3 levels within the reference range is accompanied by a favorable AGE/RAGE balance. Further investigations are needed to confirm these results.

Utility of Epicardial Fat Thickness in Subclinical Hypothyroid Children to Determine Existence of Subclinical Atherosclerosis in Them

Context

Adult studies have shown the association of subclinical hypothyroid (SCH) with various cardiovascular dysfunction, which indicates SCH may be a potentially modifiable risk factor of CV disease and mortality. However, there is still controversy about the association of cardiovascular dysfunction in children with SCH. Epicardial fat thickness (EFT) is a reliable and sensitive marker of cardiovascular risk and has become an emerging modality to predict CV risks.

Aims

To measure the EFT in children with subclinical hypothyroidism and compare with healthy children. To find its correlation with subclinical atherosclerosis. To compare EFT between TPO positive and TPO negative subclinical hypothyroid patients.

Materials and Methods

Children of subclinical hypothyroidism (TSH >5 mIU/ml with normal FT3, FT4, and age and sex matched control were included as per inclusion and exclusion criteria. Clinical data was collected from all study subjects. Thyroid function tests including FT3, FT4 and TSH, TPO antibody, fasting insulin, hsCRP, Lp(a), USG neck for carotid intima media thickness (CIMT), USG brachial artery for flow mediated dilation (FMD) and echocardiography for epicardial fat thickness (EFT) were done in all patients.

Results

A total 42 number of SCH and 50 age and sex matched controls were recruited and screened for various parameters of subclinical atherosclerosis. EFT was significantly higher in the cases than in the controls (6.27 mm vs 4.54 mm) with P value < 0.001. Brachial FMD was significantly lower in cases than the cohort (4.5% vs 8.93%, P < 0.001). Difference in CIMT was not significant amongst the cases and controls. EFT failed to correlate with the level of TSH though it had significant positive correlation with hsCRP. The patients who were TPO positive, had higher fasting insulin, HOMAIR, hsCRP, Lp(a) than those who were TPO negative.

Conclusion

Results of this study show the presence of subclinical atherosclerosis in children with SCH regardless of the aetiologies. The patients of Hashimoto thyroiditis had significantly high insulin resistance and inflammation than the SCH patients of other aetiologies.

Metabolic Characteristics of Hashimoto's Thyroiditis Patients and the Role of Microelements and Diet in the Disease Management-An Overview

Hashimoto’s thyroiditis (HT) is the most common autoimmune disease and the leading cause of hypothyroidism, in which damage to the thyroid gland occurs due to the infiltration of lymphocytes. It is characterized by increased levels of antibodies against thyroid peroxidase and thyroglobulin. In this review, we present the metabolic profile, the effectiveness of micronutrient supplementation and the impact of dietary management in patients with HT. For this current literature review, the databases PubMed, Cochrane, Medline and Embase were reviewed from the last ten years until March 2022. This article provides a comprehensive overview of recent randomized controlled trials, meta-analyses, and clinical trials. Many patients with HT, even in the euthyroid state, have excess body weight, metabolic disorders, and reduced quality of life. Due to frequent concomitant nutritional deficiencies, the role of vitamin D, iodine, selenium, magnesium, iron and vitamin B12 is currently debated. Several studies have underlined the benefits of vitamin D and selenium supplementation. There is still no specific diet recommended for patients with HT, but a protective effect of an anti-inflammatory diet rich in vitamins and minerals and low in animal foods has been suggested. There is insufficient evidence to support a gluten-free diet for all HT patients. Pharmacotherapy, along with appropriate nutrition and supplementation, are important elements of medical care for patients with HT. The abovementioned factors may decrease autoantibody levels, improve thyroid function, slow down the inflammatory process, maintain proper body weight, relieve symptoms, and prevent nutritional deficiencies and the development of metabolic disorders in patients with HT.

The Relationships among Plasma Fetuin-B, Thyroid Autoimmunity, and Fertilization Rate In Vitro Fertilization and Embryo Transfer

OBJECTIVE

The objective of the study is to investigate the relationships between fetuin-B, thyroid autoimmunity (TAI), and pregnancy outcomes in women undergoing in vitro fertilization and embryo transfer (IVF-ET). Design, Patients, and Measurements. In this prospective study, 180 women who were preparing for pregnancy with IVF-ET were included. There were 120 women with TAI positive and 60 negative controls matched with age and BMI.

RESULTS

The 180 women had mean ± SD age of 31.4 ± 4.0 years, with a mean ± SD BMI of 21.0 ± 1.6 kg/m². There was a significant difference in the level of fetuin-B in women with TAI positive compared with TAI negative group (65.2 ± 18.5 vs. 76.4 ± 25.1, P=0.001). Fetuin-B had a negative relationship with thyroid antibodies even after adjusting for other variables (OR (95%CI) = 0.98 (0.96-0.99), P=0.002). Compared with women with TAI negative, those with TAI positive had a significantly higher risk of low fertilization (20.0% vs. 6.7%; P=0.035). And we found no difference in terms of pregnancy, abortion, implantation, and live birth rate between the two groups. Logistic regression analysis showed that both fetuin-B and TAI were the independent factors to lead the low fertilization of IVF-ET (OR (95%CI) = 0.96 (0.94-0.99) and 4.084 (1.39-15.30), P=0.004 and 0.019, respectively).

CONCLUSION

Fetuin-B was significantly associated with TAI and low fertilization rate in women undergoing IVF-ET. Decreased fetuin-B in women with TAI may be the underlying reason for the lower IVF-ET success rate.

The effect of Thyroid Autoimmunity on Dyslipidemia in patients with Euthyroid Hashimoto Thyroiditis

Background & Objective:

The relationship between thyroid disorders and dyslipidemia has now been clearly demonstrated, but the relationship between thyroid autoimmunity and dyslipidemia in euthyroid patients is still controversial. Our aim in this study was to determine whether there is a risk of dyslipidemia in our patients with euthyroid hashimoto thyroiditis.

Methods:

Fifty-five autoantibody positive hashimoto patients and 55 antibody negative control groups who came to Sakarya University Medicine Faculty Endocrinology Outpatient Clinics between January 2018 and November 2019 were included in our case control study. The groups were similar in terms of age, cardiovascular risk factors and BMI. Both groups were compared according to the lipid profile results.

Results:

All type of lipids; including LDL (p = 0.008), HDL (p = 0.041), triglyceride (p = 0.045) and total cholesterol (p = 0.002), were higher in the patient group, and these differences were statistically significant. Anti-TPO and Anti-TG antibody titers and lipid levels were evaluated by separate correlation analysis. There was a significant positive correlation between Anti-TPO and LDL (r = 0.331, p <0.001), triglyceride (r = 0.267, p = 0.005) and total cholesterol (r = 0.316, p = 0.001), however no significant correlation was observed between Anti-TPO and HDL. Similarly, there was a significant positive correlation between Anti-TG and LDL (r = 0.318, p = 0.001), triglyceride (r = 0.218, p = 0.022), and total cholesterol (r = 0.301, p = 0.001), but HDL correlation relationship was not detected.

Conclusion:

The relationship between thyroid autoimmunity and dyslipidemia has been demonstrated in our study even in the euthyroid phase. Whether antibody positive patients should be followed more closely for dyslipidemia and cardiovascular events is still controversial. This question will be answered with larger randomized controlled trials.

Autoimmune diseases in patients undergoing percutaneous coronary intervention: A risk factor for in-stent restenosis?

BACKGROUND AND AIMS

Despite the relation between autoimmune diseases and increased atherosclerotic risk is established, the influence of autoimmune disorders on in-stent restenosis (ISR) after percutaneous coronary intervention (PCI) is only partly known. ISR is an aberrant reparative process mainly characterized by an increased number of vascular smooth muscle cells and excessive deposition of extracellular proteoglycans and type III collagen. Chronic inflammation, always present in autoimmune diseases, modulates the endothelial response to PCI. Aim of this review is to resume the current evidence on the association between ISR and autoimmune diseases, focusing on pathogenic mechanisms and therapeutic targets.

METHODS

We conducted a comprehensive review of the literature on the relationship between ISR and insulin-dependent diabetes mellitus (IDDM), rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), antiphospholipid-antibodies syndrome (APS), inflammatory bowel diseases (IBD), and Hashimoto's thyroiditis (HT).

RESULTS

Patients affected with IDDM, RA, SLE, APS, IBD and HT proved to face higher rates of ISR compared to the general population. The endothelial dysfunction seems the principal common pathogenic pathway for ISR and is attributed to both the immune system disorder and the systemic inflammation. Some evidence suggested that methotrexate and anti-tumor necrosis factor treatments can be effective in reducing ISR, while antibodies against vascular cell adhesion molecule-1 and intercellular adhesion molecule-1 showed to reduce neointimal hyperplasia in animal models.

CONCLUSIONS

Autoimmune diseases are a risk factor for ISR. The study of the potential cardiovascular benefits of the current therapies, mainly anti-inflammatory drugs, and the pursuit of innovative treatments appear of paramount interest.

The Relationship Between the Impairment of Endothelial Function and Thyroid Antibodies in Hashimoto's Thyroiditis Patients with Euthyroidism

Endothelial dysfunction is the important early step in the development of atherosclerosis. Hypothyroidism caused by Hashimoto's thyroiditis and other thyroid disease is one of the risk factors of endothelial dysfunction. The present study tried to investigate the endothelial function and its associated factors in Hashimoto thyroiditis with euthyroidism. A total of 95 newly diagnosed Hashimoto's thyroiditis patients with euthyroidism and 45 healthy controls were studied. Hashimoto's patients were divided into 3 subgroups namely, single thyroglobulin antibody (TGAb) positive subgroup, single thyroid peroxidase antibody (TPOAb) positive subgroup, and both TGAb and TPOAb positive subgroup. Endothelial function was tested by the reactive hyperemia index (RHI). Hashimoto's thyroiditis patients had lower RHI than healthy controls (1.73±0.42 vs 1.96±0.51, p<0.05). Hashimoto's thyroiditis with single TGAb positive patients had higher RHI than single TPOAb positive (1.98±0.57 vs. 1.69±0.33, p<0.05) and TGAB + TPOAb positive patients (1.98±0.57 vs. 1.68±0.42, p<0.05). RHI were negatively associated with total cholesterol (TC, r=-0.215, p<0.05), low density lipoprotein cholesterol (LDL-C, r=-0.268, p<0.05), triglyceride (TG, r=-0.192, p<0.05), and TPOAb (r=-0.288, p<0.05). In the regression analysis, LDL-C (β=-0.146, p<0.05), TG (β=-0.034, p<0.05) and TPOAb (β=-0.001, p<0.05) were independently associated with RHI. Hashimoto's patients had poor endothelial function. TPOAb levels were negatively associated with endothelial function.

Serum cystatin C is closely associated with euthyroid Hashimoto's thyroiditis in adult female Chinese patients

Objective

The aim of our study was to explore the association between serum cystatin C (CysC) and euthyroid Hashimoto’s thyroiditis.

Methods

There were 119 female euthyroid Hashimoto’s thyroiditis patients and 225 healthy controls who were recruited. Serum CysC, thyroid function, thyroid autoantibodies, fasting glucose, liver enzymes, and lipid profile were determined. Clinical parameters were compared between two groups.

Results

Serum CysC levels were significantly higher in euthyroid Hashimoto’s thyroiditis patients compared with controls. In the lowest, middle, and highest tertile groups of CysC, the percentage of Hashimoto’s thyroiditis was 15.9%, 34.2%, and 53.5%, respectively. The percentage of Hashimoto’s thyroiditis was significantly higher in the highest tertile than in the lowest and middle tertiles. Spearman’s correlation analysis showed that serum CysC levels were negatively correlated with free triiodothyronine (FT₃), and positively correlated with serum thyroid peroxidase antibody (TPOAb) and thyroglobulin antibody (TGAb). Logistic regression analysis showed that serum CysC was independently related to the status of euthyroid Hashimoto’s thyroiditis.

Conclusions

The present study shows the first evidence suggesting that serum CysC levels are positively correlated with TPOAb and TGAb. Serum CysC might underlie the pathophysiologic features of euthyroid Hashimoto’s thyroiditis.

Does Hashimoto's Thyroiditis Increase the Risk of Cardiovascular Disease in Young Type 1 Diabetic Patients?

Background: Immunological and hormonal disorders have undoubted influence on the development of atherosclerotic process. Autoimmune diseases accompanying type 1 diabetes (T1D) may additionally accelerate atherosclerosis progression and increase the risk of cardiovascular events in the future. The influence of subclinical hypothyroidism on the cardiovascular system, in particular, has recently aroused great interest. The aim of our study was to assess intima-media thickness (cIMT) of common carotid arteries and the occurrence of classical atherosclerosis risk factors together with selected new biomarkers of cardiovascular diseases in young patients with type 1 diabetes mellitus coexisting with Hashimoto's disease (HD). Patients and Methods: The study included 50 adolescents and young adults with T1D with mean age 17.1 ± 3 years, with mean diabetes duration of 10.5 ± 3.3 years, including 20 patients with diagnosed HD: T1D and HD(+), and 30 patients with no additional diseases: T1D and HD(-). Twenty-two healthy, age-matched volunteers formed control group (C). We analyzed mean HbA₁c value from all years of disease, BMI, blood pressure, lipids, new biomarkers of atherosclerosis (hsCRP, adiponectin, myeloperoxidase, NT-proBNP peptide, vitamin D), and cIMT of common carotid arteries. Results: In the group of patients with T1D and HD(+), significantly higher BMI was found: 23.3 ± 4.4 vs. 21.28 ± 2.9 in group HD(-) and 19.65 ± 2.4 kg/m² in group C (p = 0.003), and higher waist circumference: 79 ± 10.9 vs. 75.10 ± 7.6 in group HD(-) vs. 69.0 ± 7.4 cm in group C (p < 0.001). The mean value of HbA₁c was higher in group T1D and HD(+): 8.8% than in group HD(-): 8.1% (p = 0.04). Significantly higher concentration of hsCRP and lower vitamin D were observed in T1D and HD(+) in comparison to T1D and HD(-) and the control group. The IMT index in the HD(+) group was 0.46 ± 0.05 mm and was comparable to the HD(-) group but significantly higher than in healthy controls: 0.41 ± 0.03 mm (P < 0.05). Conclusions: Young patients with type 1 diabetes mellitus and with coexisting Hashimoto's thyroiditis have a higher BMI, a higher waist circumference, and a higher HbA₁c value, which altogether may cause faster development of macroangiopathy in the near future. Additional risk for cardiovascular disease may result from low vitamin D and increased hsCRP concentration in this group of patients. Coexistence of Hashimoto's thyroiditis did not significantly affect the cIMT value in the studied population.

Impact of Abdominal Obesity on Thyroid Auto-Antibody Positivity: Abdominal Obesity Can Enhance the Risk of Thyroid Autoimmunity in Men

BACKGROUND

The interrelation between obesity and autoimmune thyroid diseases is complex and has not been confirmed. The aim of the present study was to observe the relationship between thyroid autoimmunity and obesity, especially abdominal obesity, in a large population.

METHODS

A total of 2253 residents who had lived in Xinjiang for more than 3 years were enrolled. Serum thyroid hormone concentration, thyroid autoantibodies, lipid parameters, Weight, height, and waist and hip circumference were measured.

RESULTS

The prevalence of thyroid peroxidase antibody (TPOAb) and/or thyroglobulin antibody (TgAb) positive was 32.1% (21.2% in men and 37% in women, P < 0.01). Compared with women, men had significantly higher TG levels, waist circumference, and hip circumference levels (P < 0.01), while women showed higher TSH, TPOAb, and TgAb levels (P < 0.01). The prevalence of overweight and obesity was 71.1% in men and 63.5% in women. Men had a higher prevalence of abdominal obesity than women (56.6% in men and 47.6% in women, P < 0.01). TPOAb correlates positively with waist circumference (r = 0.100, P < 0.05) in men. Binary logistic analysis showed that TPOAb positivity had increased risks of abdominal obesity in men, and the OR was 1.1044 (95% CI 1.035, 1.151, P < 0.05).

CONCLUSION

Our results indicate that men had higher lipid levels, thicker waist circumference, and higher prevalence of overweight, obesity, and abdominal obesity. Abdominal obesity is a risk factor for TPOAb positivity in men, suggesting that abdominal obesity can enhance the risk of thyroid autoimmunity in men.

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.

Hyperhomocysteinemia in acute iatrogenic hypothyroidism: the relevance of thyroid autoimmunity

PURPOSE

Hyperhomocysteinemia is a known cardiovascular risk factor and a key player in the inflammatory activation of autoimmune diseases. Hashimoto's thyroiditis (HT) is the leading cause of hypothyroidism which, in itself, has been associated with a significant raise of homocysteine (Hcy) levels and increased cardiovascular risk. Our aim was to assess the impact of HT on Hcy levels in patients with acute hypothyroidism.

METHODS

We prospectively enrolled 121 patients (mean age: 46 years, F/M = 102/19) with acute post-surgical hypothyroidism. Based on the presence of anti-thyroid antibodies and the histological description of an inflammatory infiltrate, 26 and 95 patients were classified as HT and non-HT, respectively. Several parameters including thyroid-stimulating hormone (TSH), levels of serum free T3 and free T4, weight, glucose levels, total cholesterol, creatinine, vitamin B₁₂, ferritin and erythrocyte sedimentation rate were obtained from all patients and correlated with Hcy levels.

RESULTS

Median Hcy level in the whole cohort was 16.8 µmol/L (normal values: < 12 µmol/l). Among all parameters analysed, only Hcy levels were significantly different between HT and non-HT patients (median Hcy = 19.7 vs 16.2 µmol/L, respectively; p = 0.018, Mann-Whitney U test). Analysis of covariance showed the presence of HT to be the strongest predictor of Hcy levels (coefficient = 0.25534, p = 0.001). Serum TSH was not significantly associated with Hcy levels (p = 0.943).

CONCLUSION

In patients with iatrogenic hypothyroidism, those with HT have significantly higher Hcy levels than those without HT. The increase of Hcy levels appears to be mainly determined by the HT-related immune-inflammatory condition.

Depletion of Regulatory T Cells in Visceral Adipose Tissues Contributes to Insulin Resistance in Hashimoto's Thyroiditis

Hashimoto's Thyroiditis (HT) is a common organ-specific autoimmune disorder associated with a high incidence, and insulin resistance is highly related to autoimmune. Here, we examined the insulin sensitivity in HT patients and found decreased insulin sensitivity occurred in HT patients. To explore the relationship between impaired insulin sensitivity and immune status, we established HT model mice which showed similar pathological features and immune features to HT patients. In HT model mice, reinfusion of regulatory T cells (Tregs) from peripheral blood of normal mice could improve insulin sensitivity and decrease the inflammation. Anti-CD25 antibodies blocked beneficial effects from reinfusion of Tregs, but delayed administration of anti-CD25 antibodies could not abolished the effect from Tregs. Delayed administration of anti-CD25 antibodies abolished exogenous Tregs in peripheral blood, but there were increased exogenous Tregs located to visceral adipose tissues (VATs) which modulated the expression of cytokines in VATs. These findings suggest that insulin resistance exists in HT patients and it associates with the decreased Tregs and increased inflammation in the VATs.

Association Between Thyroid Hormones, Thyroid Antibodies, and Cardiometabolic Factors in Non-Obese Individuals With Normal Thyroid Function

BACKGROUND

Hypothyroidism is an important risk factor for cardiovascular diseases, and autoimmune thyroiditis (AIT) is the leading cause of hypothyroidism. Recent studies showed that even AIT patients with euthyroidism still had an increased number of early atherosclerotic lesions. However, the precise mechanism is not yet known. This study aimed to investigate the association of thyroid function, thyroid autoimmunity, and cardiometabolic risk factors in non-obese AIT patients with euthyroidism.

METHODS

A total of 5,608 non-obese individuals including 1,402 AIT patient and 4,206 sex-, age-, and body mass index (BMI)-matched healthy controls were recruited.

RESULTS

The AIT patients had significantly lower free T3 and free T4 levels, and higher TSH, antithyroid peroxidase antibodies (TPOAb) and TgAb levels. The elevated levels of high sensitivity C reactive protein (hsCRP) and homeostasis model assessment of insulin resistance (HOMA-IR) were observed in the AIT patients than the controls [hsCRP: 0.65 (0.27-1.33) vs. 0.20 (0.03-0.74) mg/L; HOMA-IR: 2.78 ± 1.60 vs. 2.33 ± 1.49; all P < 0.05]. Thyroid function was not associated with metabolic parameters and inflammatory makers, while the TPOAb titer was positively associated with the HOMA-IR and hsCRP levels after adjustment for confounding factors (all P < 0.05). Multivariate regression analysis demonstrated that the TPOAb level was an independent influencing factor for the HOMA-IR and hsCRP levels (HOMA-IR: β = 0.058, P < 0.05; hsCRP: β = 0.108, P < 0.05).

CONCLUSION

The TPOAb level is associated with HOMA-IR and hsCRP levels independently of thyroid function in non-obese individuals. Mild deviation of thyroid function within the normal range, chronic inflammation, and insulin resistance may be the links between AIT and atherosclerosis in the non-obese population.