Corticosteroid-binding globulin (CBG) reactive centre loop antibodies and surface plasmon resonance interrogate the proposed heat dependent "flip-flop" mechanism of human CBG

Corticosteroid-binding globulin (CBG) is the predominant carrier of cortisol in circulation and is a non-inhibitory member of the serpin superfamily of serine protease inhibitors. In the stressed or "S" conformation, CBG possesses an intact exposed reactive centre loop (RCL) that can be irreversibly cleaved by elastase released from activated human neutrophils whereupon it adopts a relaxed or "R" conformation. The latter conformation has decreased affinity for cortisol, allowing the release of the majority of cortisol at sites of inflammation. Recently there has been speculation that mild increments in heat such as found in pyrexia (39-40°C) may also induce a reversible "flip-flop" of the RCL into the body of the protein structure, without cleavage, facilitating a reversible temperature-dependent release of cortisol. Here we raised a new monoclonal antibody to the RCL of human CBG and used this in concert with an existing RCL antibody and show by surface plasma resonance that, at temperatures up to 40°C, the RCL of purified CBG and the RCL of CBG in intact plasma is accessible to these two antibodies. Together, the epitopes of these antibodies span 11 consecutive amino acids (STGVTLNLTSK) of the 18 residues of the RCL. This adequate antibody cover of the RCL sequence leads to the conclusion that the proposed temperature-dependent "flip-flop" of the RCL of CBG is doubtful.

Identifying a Small Molecule Blocking Antigen Presentation in Autoimmune Thyroiditis

We previously showed that an HLA-DR variant containing arginine at position 74 of the DRβ1 chain (DRβ1-Arg74) is the specific HLA class II variant conferring risk for autoimmune thyroid diseases (AITD). We also identified 5 thyroglobulin (Tg) peptides that bound to DRβ1-Arg74. We hypothesized that blocking the binding of these peptides to DRβ1-Arg74 could block the continuous T-cell activation in thyroiditis needed to maintain the autoimmune response to the thyroid. The aim of the current study was to identify small molecules that can block T-cell activation by Tg peptides presented within DRβ1-Arg74 pockets. We screened a large and diverse library of compounds and identified one compound, cepharanthine that was able to block peptide binding to DRβ1-Arg74. We then showed that Tg.2098 is the dominant peptide when inducing experimental autoimmune thyroiditis (EAT) in NOD mice expressing human DRβ1-Arg74. Furthermore, cepharanthine blocked T-cell activation by thyroglobulin peptides, in particular Tg.2098 in mice that were induced with EAT. For the first time we identified a small molecule that can block Tg peptide binding and presentation to T-cells in autoimmune thyroiditis. If confirmed cepharanthine could potentially have a role in treating human AITD.

Regulatory B and T cell responses in patients with autoimmune thyroid disease and healthy controls

Autoimmune diseases occur due to faulty self-tolerance. Graves' disease (GD) and Hashimoto's thyroiditis (HT) are classic examples of organ-specific autoimmune diseases. GD is an auto-antibody-mediated disease where autoantibodies are produced against the thyroid stimulating hormone receptor (TSHR). HT is primarily a T-cell mediated disease, and whether B cells play a pathogenic role in the pathogenesis is still unclear. Both GD and HT are characterized by infiltration of the thyroid gland by self-reactive T cells and B cells. In the first paper of this thesis, the role of regulatory B cells (Bregs) and regulatory T cells (Tregs) were investigated in the context of GD and HT. First, we studied the role of the thyroid self-antigen, thyroglobulin (TG) in healthy donors. The self-antigen TG, but not the foreign recall antigen tetanus toxoid (TT), was able to induce interleukin 10 (IL-10) secretion by B cells and CD4+ T cells. These IL-10 producing B cells (B10 cells) from healthy donors were enriched with the CD5+ and CD24hi phenotype. In addition, TG was able to induce IL-6 production by B cells. In contrast, TT induced production of Th1-type pro-inflammatory cytokines including interferon-gamma (IFN-γ) and IL-2. In the second paper, the frequency and phenotype of B10 was investigated in healthy donors and patients with GD or HT.  The frequencies of B10 cells were similar in the three groups, irrespective of whether IL-10 was induced by a combination of phorbol 12-myristate 13-acetate (PMA) and ionomycin, by CpG oligodeoxynucletodies (ODN) 2006, or by TG. Several phenotypes have been associated with B10 cells such as CD5+, CD25+, TIM-1+, CD24hiCD38hi and CD27+CD43+. We found that larger proportions of B10 cells in patients with GD or HT were CD25+ and TIM-1+ than B10 cells in healthy donors. In healthy donors, B10 cells were CD24hiCD38-, whereas for HT patients these cells were primarily CD24intCD38int. For GD patients, we found lower proportions of B10 cells within the CD27+CD43- and CD27-CD43- fractions than for healthy donors. Our data show that GD and HT are not associated with decreased frequencies of B10 cells. Accordingly, B10 cells may not be confined to one phenotype or subset of B cells. In the third paper, we studied the balance between IL-17-producing CD4+ T cells (Th17 cells) and IL-10-producing CD4+ T cells (Th10 cells) in healthy donors and patients with GD or HT. In HT patients, we found increased proportions of naïve Th17 cells after stimulation with the thyroid self-antigen thyroid peroxidase (TPO) and the Escherichia coli lipopolysaccharide (E. coli LPS).  The proportions of Th10 cells were similar in healthy donors and in HT patients after antigen-specific stimulation. After TG stimulation, an increased Th17:Th10 ratio was found in HT patients within the naïve T cell compartment. Taken together, these data indicate that the thyroid self-antigens TG and TPO induced a skewed Th17:Th10 differentiation in HT patients. IL-6 and TGF-β have been reported to be important for human Th17 differentiation and, accordingly, HT patients showed higher baseline production of IL-6 and TGF-β1 than healthy donors. Moreover, the baseline expression of mRNA encoding the transcription factor Forkhead box protein 3 (FOXP3) was similar in HT patients and healthy donors, but HT patients displayed higher constitutive expression of the splice variant FOXP3Δ2, lacking exon 2, than healthy donors. Full-length FOXP3 has been shown to inhibit Th17 differentiation, while FOXP3Δ2 does not. Thus, increased IL-6 and TGF-β1 in the microenvironment and the increased expression of FOXP3Δ2 may contribute to the skewing of Th17 cells in HT patients. In conclusion, the human thyroid self-antigen TG is able to induce antigen-specific production of IL-10 in CD19+ B cells and CD4+ T cells among healthy donors and patients with GD or HT. Our data indicates that patients with GD or HT were not impaired in producing IL-10 and thus an immunoregulatory response. Additionally, TPO, a thyroid self-antigen, induced a higher frequency of Th17 cells in HT. This indicates that Th17 cells may play an important role in HT pathogenesis.

Thyroglobulin Autoantibodies Are Associated with Refractoriness to Antithyroid Drug Treatment for Graves' Disease

Objective The recurrence rate associated with antithyroid drug (ATD) treatment for Graves' disease (GD) is high compared with that for radioiodine therapy or surgery. It is important to identify patients in whom remission is unlikely, so that they are not given treatment that is destined to fail. The objective of this study was thus to evaluate factors influencing the prognosis of GD patients treated with ATDs. Patients One hundred and sixty-one patients were divided into two groups: 100 patients who could not discontinue ATDs for eight years or more (refractory group) and 61 patients who achieved remission within eight years after starting ATD treatment (nonrefractory group). The groups were compared in terms of age, thyroid function and thyroid-related autoantibodies at diagnosis, and the durations to the recovery of thyroid function and thyroid-related autoantibodies. Results The baseline levels of free triiodothyronine (T3), free thyroxine (T4), thyroid-stimulating antibodies (TSAbs) and thyroid-stimulating hormone (TSH) receptor antibodies (TRAbs) were high, and the age at diagnosis and the baseline level of thyroglobulin autoantibodies (TgAbs) were low in the refractory group compared with those in the nonrefractory group. The durations to the recovery of TSH, free T4, TRAb and TSAb levels were longer in the refractory group than in the nonrefractory group. No significant difference was observed with regard to thyroid peroxidase autoantibodies. Conclusion We compared the clinical features of these two groups in order to identify factors influencing the prognosis of GD patients treated with ATDs. A low baseline level of TgAbs is associated with the refractoriness of GD to ATD treatment.

Postpartum thyroid dysfunction in women with autoimmune thyroiditis

INTRODUCTION

Autoimmune thyroiditis (AIT) is a predisposing factor for developing postpartum thyroid dysfunction (PPTD).

AIM

To study the characteristics of PPTD in women with AIT.

METHODS

Thirty-eight women with pre-existing AIT were included in the study. Thyroid-stimulating hormone, free triiodthyronine, free thyroxine, thyroid peroxidase antibodies, thyroglobulin antibodies were measured and ultrasound evaluation of the thyroid gland was performed in the first trimester of pregnancy and during the first year following delivery.

RESULTS

Thyroid dysfunction was recognized in 68.4% of the patients - 28.9% presented with hypothyroidism and 39.5 % with thyrotoxicosis. The immunological and morphological parameters did not differ between euthyroid women and those with thyroid dysfunction. At the end of the postpartum period restoration of euthyroid state (being on the treatment before pregnancy) was observed in 15.4% of patients with PPTD, while 84.6% required increase of the levothyroxine dose. The analysis found a significantly lower volume of the thyroid gland, shorter duration of the disease, a lower dose of levothyroxine before and during gestation in patients with impaired thyroid function at the end of the postpartum period.

CONCLUSION

The risk of PPTD in women with AIT predating pregnancy is higher among women with preserved thyroid functional capacity motivating a thorough assessment of thyroid hormone levels and close follow-up of those women during the postpartum period.

Thyroid Dysfunction in Patients with Metastatic Carcinoma Treated with Sunitinib: Is Thyroid Autoimmunity Involved?

BACKGROUND

Sunitinib is a tyrosine kinase inhibitor (TKI) inducing thyroid dysfunction, but the precise mechanism(s) involved remains to be explained, including the role of thyroid autoimmunity. The objective of this study was to evaluate thyroid function, parameters of autoimmunity, and thyroid ultrasound findings in patients with metastatic cancer and normal thyroid function/autoimmunity before the initiation of sunitinib therapy. This was a prospective, observational cohort study.

METHODS

Twenty-seven patients with metastatic carcinomas at comparable tumor stages were evaluated over 12-18 months after initiating therapy with sunitinib given at a daily oral dose of 50 mg for four weeks (ON), followed by one to two weeks off therapy (OFF). Serum thyrotropin (TSH), free thyroxine (fT4), free triiodothyronine (fT3), and antithyroglobulin (TgAb), and antithyroid peroxidase (TPOAb) autoantibodies were measured in all cases. Thyroid morphology and volume were evaluated by echo-color Doppler ultrasound.

RESULTS

A total of 16/27 patients (60%) became hypothyroid (TSH range 7-114 mIU/L) within 30-120 days of therapy. The thyroid volume decreased in 24/27 (89%) patients (from M = 14.6 mL, SD = 6.4 mL to M = 3.8 mL, SD = 2.6 mL after 12 months; p < 0.001), together with the appearance of mild to severe hypoechogenicity. TPOAb (40-3000 IU/mL) became detectable in 7/27 (25%) patients, and TPOAb-positive patients displayed a higher degree of hypothyroidism and volume reduction. The progression-free survival (PFS) was significantly longer in patients developing TPOAb (10.8 months) than in the other group of patients (5.8 months).

CONCLUSIONS

These data confirm the thyroid inhibitory effect of sunitinib, in keeping with the key role of kinases in controlling thyroid function and growth. However, the novel appearance of TPOAb in a subgroup of patients with more severe hypothyroidism and longer survival indicates that sunitinib may also trigger/exacerbate thyroid autoimmunity contributing to thyroid failure. The development of TPOAb was associated with a longer PFS.

A novel FoxD3 Variant Is Associated With Vitiligo and Elevated Thyroid Auto-Antibodies

CONTEXT

Vitiligo frequently coincides with autoimmune endocrinopathies, particularly Hashimoto's thyroiditis (HT). Genetic susceptibility may underlie this coincident occurrence. One candidate region is the autoimmunity susceptibility locus on chromosome 1, which encompasses forkhead transcription factor D3 (FoxD3), a gene involved in embryonal melanogenesis. We identified a promotor variant (rs78645479) in an index case of vitiligo + HT + candidiasis and evaluated its clinical and functional relevance.

DESIGN

We genotyped 281 patients with variable autoimmune endocrinopathies: HT, Graves' disease (GD), type 1 diabetes (T1D), Addison's disease (AD), autoimmune polyglandular syndrome (APS), and/or vitiligo and 1858 controls. Furthermore, we experimentally assessed the effect of the variant on promotor activity and assessed the expression of FoxD3 in human thyroid tissue samples.

RESULTS

Patients with vitiligo had a higher frequency of the risk allele (30%) compared with healthy controls (18.2%). In addition, the variant was associated with the incidence of elevated anti-TPO antibodies and anti-Tg antibodies, but not with TSH, FT3, or FT4 levels and also not with GD, T1D, AD, or APS. Functionally, the variant increased transcriptional activity in Jurkat and in Hek293 cells. We confirmed gene expression of FoxD3 in human thyroid tissue, which seemed elevated in thyroid tissue samples of some patients with GD and nonautoimmune goiter but not in patients with HT.

CONCLUSION

In addition to a possible association of rs78645479 in FoxD3 with vitiligo, our data on the association of this FoxD3 variant with thyroid autoantibodies suggest a potential involvement of FoxD3 in thyroid immunoregulation.

Marginal Iodine Status and High Rate of Subclinical Hypothyroidism in Washington DC Women Planning Conception

INTRODUCTION

Subclinical hypothyroidism during pregnancy has been associated with adverse maternal and fetal outcomes. A subset of pregnant women in the United States have been shown to have mild iodine deficiency. No study has evaluated the thyroid and iodine status of women who are planning to become pregnant in the near future.

METHODS

Thyroid function tests, thyroid antibodies, and urine iodine levels were evaluated in women presenting for preconception screening and counseling. A thyrotropin (TSH) level above 3.0 mIU/L was considered abnormal.

RESULTS

One hundred and forty one women enrolled in the study. The median TSH level was 1.70 mIU/L (range 0.43-5.3 mIU/L). Sixteen women (11%) had a TSH above the upper limit of normal (>3.0 mIU/L). Eleven women (8%) were positive for TPO-Ab and 21 women (15%) for TgAb. Twenty-three women (16%) were positive for at least one thyroid antibody (TPOAb and/or TgAb). Median serum TSH concentrations were higher in women with detectable antithyroid antibodies than in women who were antibody negative (2.2 mIU/L vs. 1.7 mIU/L; p=0.005). The median urinary iodine concentration was 100.5 μg (range 19-843 μg/L).

DISCUSSION

The present cohort exhibited the lowest median urinary iodine concentration levels to date reported in the United States for women in their childbearing years. One out of every nine women (11%) had thyroid function tests consistent with subclinical hypothyroidism.

[Autoimmune thyroiditis and thyroid cancer]

Association between autoimmune thyroiditis (CLT) and thyroid cancer remains not clear. Although both diseases often occur simultaneously in histological samples, it is not yet clear whether CLT can be regarded as a risk factor for thyroid malignancy. This review focus on the known epidemiological and molecular genetics links between both diseases. Most studies have shown a significant association between thyroid cancer and positive antibodies to thyroglobulin and histological evidence of CLT, as well. Both disorders share some risk factors (greater incidence in women, in areas with adequate supply of iodine and in patients after radiotherapy of the neck) and molecular genetics linkage. For example: RET/PTC rearrangements could be more often found in carcinomas associated with CLT, but this mutation could be found in benign lesions such as CLT, as well. CLT seems to be a positive prognostic factor in patients with differentiated thyroid cancer. It is associated with less invasive forms of tumor, lower occurrence of infiltrated lymphatic nodes and a lower risk of recurrence.

Effects of Selenium Supplementation on Spontaneous Autoimmune Thyroiditis in NOD.H-2h4 Mice

BACKGROUND

Recent clinical studies have demonstrated the suppressive effect of selenium (Se) treatment on serum thyroid-specific antibody titers in patients with autoimmune thyroiditis (AIT), but the mechanism underlying this process is not clear. The aim of the present study was to investigate the effects of selenium on the incidence and severity of AIT, titers of thyroid autoantibodies, and selenoprotein expression in thyroid in a spontaneous autoimmune thyroiditis (SAT) model.

METHODS

NOD.H-2(h4) mice at four weeks of age were randomly divided into control, iodine supplement (SAT), and selenium supplement groups (SAT+Se). Mice were given 0.005% sodium iodide water for eight weeks to induce SAT and then 0.3 mg/L sodium selenite in drinking water for 8 weeks and 16 weeks. The severity of lymphocytic infiltration in the thyroid, serum thyroglobulin antibody (TgAb) titers, serum selenium concentration, expression of glutathione peroxidase-1 (GPx1), thioredoxin reductase-1 (Txnrd1), and peroxiredoxin 5 were measured.

RESULTS

Serum selenium concentration significantly increased after selenium supplementation. Serum TgAb levels were significantly lower in the selenium group compared with the SAT group (p<0.05). The prevalence of thyroiditis and the degree of infiltration of lymphocytes decreased gradually over time in the group provided with selenium supplementation. The expression of GPx1 and Txnrd1 by Western blotting were found to be significantly higher in the SAT+Se group than in other groups (p<0.05).

CONCLUSIONS

These results indicate that selenium treatment can increase the function of antioxidation by upregulating the expression of selenoproteins in the thyroid and have an inhibitory effect on TgAb titers, which may have an impact on AIT.

Higher body mass index and larger waist circumference may be predictors of thyroid carcinoma in patients with Hürthle-cell lesion/neoplasm fine-needle aspiration diagnosis

OBJECTIVE

High body mass index (BMI) has been found to be associated with raised thyroid cancer risk, particularly in women. We examined the associations for BMI and waist circumference (WC) with thyroid cancer risk among women with Hürthle-cell lesion/neoplasm (HLN) on fine-needle aspiration biopsy (FNAB) with the hypothesis that BMI and WC could guide the management of these challenging indeterminate lesions.

METHODS

This cross-sectional study included 224 women with HLN who underwent thyroidectomy. In all patients, TSH and thyroid auto-antibodies were evaluated, and thyroid nodule features were recorded. Patients were grouped according to BMI (<30 or ≥30 kg/m(2)) and WC (<88 or ≥88 cm). Relationships of thyroid cancer with BMI and WC were assessed using logistic regression analysis.

RESULTS

Mean weight, BMI (31·26 ± 5·1 vs 26·47 ± 5·9, P < 0·001), WC (98·23 ± 7·6 vs 86·18 ± 11, P = 0·001), and proportion of patients with high BMI (≥30 kg/m(2)) (65·9 vs 33·8%, P < 0·001) or large WC (≥88 cm) (84·1 vs 47·9%, P < 0·001) were significantly higher in malignant group compared to benign group. In regression analysis, BMI and WC significantly associated with existence of malignancy. Malignancy risk was 3·819-fold higher (95% CI: 2·068-7·054) in BMI≥30 kg/m(2) group compared to BMI<30 kg/m(2), which was independent of TSH and age. Large WC was also associated with increased risk (OR = 5·593, 95% CI: 2·736-11·434). Baseline tumour characteristics were similar according to BMI and WC groups.

CONCLUSIONS

A great BMI and large WC were associated with higher thyroid cancer risk in patients with FNAB diagnosis of HLN. Further studies are needed to use BMI or WC in the management of patients with HLN.

Thyroid Autoimmunity is Associated with Decreased Cytotoxicity T Cells in Women with Repeated Implantation Failure

Thyroid autoimmunity (TAI), which is defined as the presence of autoantibodies against thyroid peroxidase (TPO) and/or thyroglobulin (TG), is related to repeated implantation failure (RIF). It is reported that TAI was involved in reproductive failure not only through leading thyroid function abnormality, but it can also be accompanied with immune imbalance. Therefore, this study was designed to investigate the association of thyroid function, immune status and TAI in women with RIF. Blood samples were drawn from 72 women with RIF to evaluate the prevalence of TAI, the thyroid function, the absolute numbers and percentages of lymphocytes. The prevalence of thyroid function abnormality in RIF women with TAI was not significantly different from that in RIF women without TAI (c(2) = 0.484, p > 0.05). The absolute number and percentage of T cells, T helper (Th) cells, B cells and natural killer (NK) cells were not significantly different in RIF women with TAI compared to those without TAI (all p > 0.05). The percentage of T cytotoxicity (Tc) cells was significantly decreased in RIF women with TAI compared to those without TAI (p < 0.05). Meanwhile, Th/Tc ratio was significantly increased (p < 0.05). These results indicated that the decreased Tc percentage and increased Th/Tc ratio may be another influential factor of adverse pregnancy outcomes in RIF women with TAI.

Clinical Outcome of Remnant Thyroid Ablation with Low Dose Radioiodine in Korean Patients with Low to Intermediate-risk Thyroid Cancer

Radioiodine activity required for remnant thyroid ablation is of great concern, to avoid unnecessary exposure to radiation and minimize adverse effects. We investigated clinical outcomes of remnant thyroid ablation with a low radioiodine activity in Korean patients with low to intermediate-risk thyroid cancer. For remnant thyroid ablation, 176 patients received radioiodine of 1.1 GBq, under a standard thyroid hormone withdrawal and a low iodine diet protocol. Serum levels of thyroid stimulating hormone stimulated thyroglobulin (off-Tg) and thyroglobulin-antibody (Tg-Ab), and a post-therapy whole body scan (RxWBS) were evaluated. Completion of remnant ablation was considered when there was no visible uptake on RxWBS and undetectable off-Tg (<1.0 ng/mL). Various factors including age, off-Tg, and histopathology were analyzed to predict ablation success rates. Of 176 patients, 68.8% (n = 121) who achieved successful remnant ablation were classified into Group A, and the remaining 55 were classified into Group B. Group A presented with significantly lower off-Tg at the first radioiodine administration (pre-ablative Tg) than those of Group B (1.2 ± 2.3 ng/mL vs. 6.2 ± 15.2 ng/mL, P = 0.027). Pre-ablative Tg was the only significant factor related with ablation success rates. Diagnostic performances of pre-ablative Tg < 10.0 ng/mL were sensitivity of 99.1%, specificity of 14.0%, positive predictive value of 71.1%, and negative predictive value of 87.5%, respectively. Single administration of low radioiodine activity could be sufficient for remnant thyroid ablation in patients with low to intermediate-risk thyroid cancer. Pre-ablative Tg with cutoff value of 10.0 ng/mL is a promising factor to predict successful remnant ablation.

Characterization of Regulatory B Cells in Graves' Disease and Hashimoto's Thyroiditis

A hallmark of regulatory B cells is IL-10 production, hence their designation as IL-10⁺ B cells. Little is known about the ability of self-antigens to induce IL-10⁺ B cells in Graves’ disease (GD), Hashimoto’s thyroiditis (HT), or other autoimmune disease. Here we pulsed purified B cells from 12 HT patients, 12 GD patients, and 12 healthy donors with the thyroid self-antigen, thyroglobulin (TG) and added the B cells back to the remaining peripheral blood mononuclear cells (PBMCs). This procedure induced IL-10⁺ B-cell differentiation in GD. A similar tendency was observed in healthy donors, but not in cells from patients with HT. In GD, B cells primed with TG induced IL-10-producing CD4⁺ T cells. To assess the maximal frequency of inducible IL-10⁺ B cells in the three donor groups PBMCs were stimulated with PMA/ionomycin. The resulting IL-10⁺ B-cell frequency was similar in the three groups and correlated with free T₃ levels in GD patients. IL-10⁺ B cells from both patient groups displayed CD25 or TIM-1 more frequently than did those from healthy donors. B-cell expression of two surface marker combinations previously associated with regulatory B-cell functions, CD24^hiCD38^hi and CD27⁺CD43⁺, did not differ between patients and healthy donors. In conclusion, our findings indicate that autoimmune thyroiditis is not associated with reduced frequency of IL-10⁺ B cells. These results do not rule out regulatory B-cell dysfunction, however. The observed phenotypic differences between IL-10⁺ B cells from patients and healthy donors are discussed.

Effects of isolated positive maternal thyroglobulin antibodies on brain development of offspring in an experimental autoimmune thyroiditis model

BACKGROUND

Autoimmune thyroiditis (AIT) is a very common endocrine disorder in pregnancy. However, the effect of maternal positive thyroglobulin antibodies (TgAb) on brain development of offspring remains unclear. This study used an experimental autoimmune thyroiditis model in CBA/J mice and determined whether isolated positive maternal TgAb directly affected learning and memory abilities of offspring.

METHODS

An experimental autoimmune thyroiditis model was established in CBA/J mice through immunization with murine thyroglobulin (mTg). Measuring thyroid function and serum TgAb titer confirmed the presence of isolated positive maternal TgAb. Offspring serum TgAb titer, MCT8, Reelin, RC3, and BNDF mRNA expression in the brain, and brain histology were measured on postnatal days 0, 10, and 40 (PND0, PND10, PND40), and nerve cell migration (BrdU labeling) at PND40. Morris water maze, long-term potentiation (LTP), and LTP-related factor ERK1/2 levels were measured at PND40 to determine offspring spatial learning and memory development.

RESULTS

Maternal serum TgAb titers increased and remained elevated through pregnancy compared to controls. Thyrotropin and thyroid hormone levels were normal. The T group offspring (Tg immunized) had higher TgAb titers than the control (C) group. However, antibody titers time-dependently decreased. MCT8, Reelin, RC3, and BDNF mRNA expression in the whole brain were similar in the T and C groups on PND0, PND10, and PND40. Neuronal distribution and BrdU from the cerebral cortex and hippocampus were similar in the T and C group offspring. Morris water maze tests, excitatory postsynaptic field potentials, and ERK1/2 levels were also similar between the T and C groups.

CONCLUSIONS

Isolated positive maternal TgAb did not clearly influence the learning ability and memory of offspring, or nerve cell migration, despite a transient increase in TgAb in immunized mice.

Serum thyroid hormone autoantibodies in type 1 diabetes mellitus

CONTEXT

Autoimmune thyroid diseases (AITDs) can be associated with type 1 diabetes (DM1). The prevalence of serum antibodies against thyroid hormones (THAb) in subjects with autoimmune diseases other than DM1 is increasing. No data are available for DM1.

OBJECTIVE

The objectives were evaluate the rate of associated AITD; the rate of positiveness for serum THAb; the panel of THAb based on thyroid hormone interaction and on Ig class; and the association of AITD alone, THAb alone, or AITD plus THAb with diabetes-related complications.

DESIGN

This was an observational, prospective study with 6-year (2005-2011) follow-up.

SETTING

The setting was an outpatient diabetes clinic.

PATIENTS

Fifty-two consecutive subjects (53.8% males; mean age, 37.4 ± 7.4 y; diabetes duration, 19.9 ± 8.2 y) with DM1. All participants completed the study.

MAIN OUTCOME MEASURES

Main outcome measures were AITD rate; THAb positivity according to hormone interaction and Ig class; association of AITD and THAb with diabetes-related complications.

RESULTS

AITD rate increased from baseline (34.6%) to follow-up (38.5%). Subjects with DM1 had a high prevalence of THAb (92.3%). The presence of AITD at baseline was associated with subsequent development of macroangiopathy (0 vs 33% at baseline and follow-up, respectively; P = .029). Some THAb patterns, the majority having T3 binding in common, were associated with the progression and development of diabetes-related complications.

CONCLUSIONS

THAb synthesis in DM1 might be driven by increased glycosylation of thyroglobulin. Anti T3-THAb may cause a relative "tissue hypothyroidism" by sequestering thyroid hormone, this at least partially contributing to worsening diabetes-related vascular complications. In a clinical setting THAb positivity could identify subjects more likely to develop diabetes complications.

Altered balance between self-reactive T helper (Th)17 cells and Th10 cells and between full-length forkhead box protein 3 (FoxP3) and FoxP3 splice variants in Hashimoto's thyroiditis

T helper type 17 (Th17) cells play a pathogenic role in autoimmune disease, while interleukin (IL)-10-producing Th10 cells serve a protective role. The balance between the two subsets is regulated by the local cytokine milieu and by the relative expression of intact forkhead box protein 3 (FoxP3) compared to FoxP3Δ2, missing exon 2. Th17 and Th10 cell differentiation has usually been studied using polyclonal stimuli, and little is known about the ability of physiologically relevant self-antigens to induce Th17 or Th10 cell differentiation in autoimmune thyroid disease. We subjected mononuclear cells from healthy donors and patients with Hashimoto's thyroiditis (HT) or Graves' disease (GD) to polyclonal stimulation, or stimulation with human thyroglobulin (TG), human thyroid peroxidase (TPO), or Esherichia coli lipopolysaccharide (LPS). TPO and LPS induced increased differentiation of naive CD4(+) CD45RA(+) CD45R0(-) T cells from HT patients into Th17 cells. Th10 cell proportions were decreased in HT after polyclonal stimulation, but were comparable to those of healthy donors after antigen-specific stimulation. Taken together, our data show that an increased Th17 : Th10 ratio was found in HT patients after stimulation with thyroid-specific self-antigens. We also observed an elevated baseline production of IL-6 and transforming growth factor (TGF)-β1 and of mRNA encoding FoxP3Δ2 rather than intact FoxP3. This may contribute to the skewing towards Th17 cell responses in HT.

Associations between thyroid autoantibody status and abnormal pregnancy outcomes in euthyroid women

We investigated whether thyroid autoantibody status influences pregnancy outcomes in euthyroid women, by comparing abnormal pregnancy outcome rates between those who tested positive for thyroid autoantibodies (Ab+) and those who tested autoantibody-negative (Ab-). Euthyroid pregnant women (n=7,641) underwent tests for serum thyroid peroxidase antibody (TPOAb) and thyroglobulin antibody (TgAb). The subjects were divided into 4 groups according to thyroid antibody status: TPOAb-/TgAb- (92.9%); TPOAb+/TgAb- (3.2%); TPOAb-/TgAb+ (2.0%); and TPOAb+/TgAb+ (1.9%). The incidence rates of the following abnormal pregnancy outcomes were compared among the 4 groups and analyzed by Fisher's exact test: gestational diabetes, gestational hypertension, placenta previa, placental abruption, premature rupture of fetal membrane (PROM), intrauterine growth restriction, fetal distress, fetal anomalies, stillbirth, preterm birth, and low birth weight. Among the 4 groups, there were no significant differences in age, gestational age, or in the incidence rates of abnormal pregnancy outcomes, except for PROM and low birth weight. The highest incidence rates for PROM and low birth weight were in the TPOAb-/TgAb+ and TPOAb+/TgAb+ subjects, respectively. TgAb positivity and TPOAb positivity were associated with PROM and low birth weight, respectively. Underlying factors that govern the association between thyroid autoantibodies and PROM and low birth weight require further investigation.

A longitudinal study of thyroid autoantibodies in pregnancy: the importance of test timing

OBJECTIVE

Thyroid peroxidase antibodies (TPOAb) and thyroglobulin antibodies (TGAb) are frequently measured to investigate thyroid dysfunction in pregnancy. Despite the recognized fall of these autoantibodies in pregnancy, there is limited guidance on the timing of such testing. We assessed optimal test timing of TPOAb/TGAb for the detection of Hashimoto's thyroiditis and post-partum thyroid dysfunction (PPTD).

DESIGN

Prospective longitudinal study with recruitment in Trimester 1.

PATIENTS

Healthy women ≤13 weeks' gestation from Mercy Hospital for Women, a tertiary obstetric hospital in Melbourne.

MEASUREMENTS

Serum TPOAb, TGAb, TSH and fT4 were measured at Trimester 1 (T1), Trimester 2(T2), Trimester 3(T3) and postpartum (PP) in each participant. Post-partum thyroid dysfunction (PPTD) was defined if TSH deviated from the assay's nonpregnant reference interval. Longitudinal random-effect logistic regression was used to investigate the association between time and positive/negative thyroid autoantibody status.

RESULTS

Samples from 140 women at T1 (12·0: 10·3-13·0) (median: IQR weeks' gestation); 95 at T2 (24·3: 23·0-25·9), 79 at T3 (35·9: 34·8-36·7) and 83 at PP (12·4: 10·8-14·6 weeks post-partum) were attained. At T1, 13 (9%) and 15 (11%) women had positive TPOAb and TGAb, respectively. The odds of having a positive TPOAb were 96% lower at T2 [OR = 0·04 (95% CI: 0·02-0·8; P = 0·03)] and 97% lower at T3 [OR = 0·03 (95% CI: 0·001-0·6; P = 0·02)] than at T1. Similarly, the odds of having a positive TGAb were 99·4% lower [OR = 0·006 (95% CI: 0-0·3; P = 0·01)] at T2, and 99·5% lower [OR = 0·005 (95% CI: 0-0·4; P = 0·02)] at T3 than at T1. The ROC analysis diagnostic ORs for a positive TPOAb and/or TGAb to predict PPTD were 7·8 (95% CI: 2·2-27·6), 1·2 (95% CI: 0-8·9), 2·0 (95% CI: 0-16·8), and 12·2 (95% CI: 3·3-44·9) at T1, T2, T3 and post-partum, respectively.

CONCLUSIONS

A significant proportion of pregnant women lose their thyroid autoantibody positivity after T1. The gestation-dependent loss of TPOAb/TGAb positivity and reduction in diagnostic accuracy for predicting PPTD limits the value of testing at T2 and T3.

Changes in anti-thyroglobulin IgG glycosylation patterns in Hashimoto's thyroiditis patients

OBJECTIVE

Sera of Hashimoto's thyroiditis (HT) patients are known to exhibit elevated levels of anti-thyroglobulin IgG (TgAb IgG). Therefore, TgAb IgG represents a hallmark of this debilitating autoimmune disease. The aim of our study was to investigate the differential expression of specific glycosylation patterns of TgAb IgG from HT patients and healthy blood donors.

METHODS

HT patients (n = 32) were divided into two subgroups, medium level group (mHT, n = 15) and high level group (hHT, n = 17), according to the serum levels of TgAb detected by electrochemiluminescence immunoassay. TgAb IgG was purified by affinity chromatography from the sera of the HT group and control group (n = 15). MALDI-QIT-TOF-MS/MS spectrometry was performed to identify the glycosylation profiles of purified TgAb IgG. Lectin microarray technology was used to compare the abundance of different glycans found on TgAb IgG between HT patients and controls, and between the mHT and hHT groups.

RESULTS

The results by MALDI-QIT-TOF-MS/MS showed that the glycosylation profiles of TgAb IgG were similar between the mHT, hHT, and control groups. Furthermore, the lectin microarray showed that compared to the control group (all P < .001), there were higher levels present of (1) mannose (detected as lectin LCA, VFA, and MNA-M); (2) terminal sialic acid (detected as SNA-I and PSA); (3) core fucose (detected as LcH); and (4) Gal(β1-4)GlcNAc(β1-2)Man glycans (detected as PHA-L) on TgAb IgG from the HT group. A similar trend was observed between the hHT and mHT group, with elevated levels of mannose, terminal sialic acid, core fucose, and Gal(β1-4)GlcNAc(β1-2)Man glycans on TgAb IgG found in the hHT group compared with the mHT group (all P < .05).

CONCLUSIONS

TgAb IgG of HT patients exhibits higher glycosylation levels than those observed for TgAb IgG of healthy controls. Our results provide new clues for exploring the role of TgAb in the pathogenesis of HT.