Thyroid function alterations attributed to high iodide supplementation in maternal rats and their offspring

Study of iodine transport and thyroid hormone levels in the human placenta under different iodine nutritional status

Iodine and thyroid hormones (TH) transport in the placenta are essential for fetal growth and development, but there is little research focus on the human placenta. The research aimed to investigate iodine and TH transport mechanisms in the human placenta. The placenta was collected from sixty healthy pregnant women. Urinary iodine concentration (UIC), serum iodine concentration (SIC), placenta iodine storage (PIS) and the concentration of serum and placenta TH were examined. Five pregnant women were selected as insufficient intake (II), adequate intake (AI) and above requirements intake (ARI) groups. Localisation/expression of placental sodium/iodide symporter (NIS) and Pendrin were also studied. Results showed that PIS positively correlated with the UIC (R = 0·58, P < 0·001) and SIC (R = 0·55, P < 0·001), and PIS was higher in the ARI group than that in the AI group (P = 0·017). NIS in the ARI group was higher than that in the AI group on the maternal side of the placenta (P < 0·05). NIS in the II group was higher than that in the AI group on the fetal side (P < 0·05). In the II group, NIS on the fetal side was higher than on the maternal side (P < 0·05). Pendrin was higher in the II group than in the AI group on the maternal side (P < 0·05). Free triiodothyronine (r = 0·44, P = 0·0067) and thyroid-stimulating hormone (r = 0·75, P < 0·001) between maternal and fetal side is positively correlated. This study suggests that maternal iodine intake changes the expression of NIS and Pendrin, thereby affecting PIS. Serum TH levels were not correlated with placental TH levels.

Iodide intake during pregnancy and lactation stimulates KLF9, BDNF expression in offspring brain with elevated DHA, EPA metabolites

To investigate the effect of different iodide intake during pregnancy and lactation on thyroid function, docosahexaenoic acid (DHA), Eicosapentaenoic acid (EPA) metabolites, the expression of Krüppel-like factor KLF9 (KLF9), brain-derived neurotrophic factor (BDNF) in brain in offspring rats. In both male and female offspring rats, serum FT3, FT4 levels and the expression of KLF9, thyroid hormone receptors (TR)α, TRβ and BDNF in the hippocampal region and cerebellum were significantly increased in 5 times higher-than-normal pregnant iodide intake (5 HI) and 10 times higher-than-normal pregnant iodide intake (10 HI) group. The median levels of DHA metabolite (17-HDoHE) and EPA metabolites (15-HEPE, 17,18-EEQ, 9-HEPE and 14,15-DiHETE) were significantly increased in 5 HI and 10 HI group of offspring rats. Serum DHA, EPA metabolites and KLF9 as well as BDNF expression in brain might be potential iodine status biomarkers to reflect brain development in offspring.

Cordyceps sinensis-derived fungus Isaria felina ameliorates experimental autoimmune thyroiditis in mice

AIMS

This study aimed to investigate the therapeutic effect of Cordyceps sinensis-derived fungus Isaria felina on experimental autoimmune thyroiditis (EAT).

METHODS

A NaI-induced EAT mouse model was established. The mice received oral administration of vehicle, low-dose Isaria felina (300 mg/kg), or high-dose Isaria felina (600 mg/kg) once a day for four weeks before euthanasia. Enzyme-linked immunosorbent assays (ELISA) was performed to measure serum thyroid-stimulating hormone (TSH) levels, thyroid antibodies, and cytokines. Hematoxylin and eosin (H&E) staining was conducted to assess histopathological changes in the thyroid tissue samples of mice. TUNEL and Bcl-2 immunohistochemistry (IHC) were performed to evaluate cell apoptosis, and cleaved caspase-3 IHC was performed to detect the relative expression in the thyroid tissue samples.

RESULTS

Compared with KIO₃ and KI water, NaI water consumption successfully induced EAT in mice, as evidenced by significantly increased circulating TSH and thyroid antibody levels, along with typical histopathological abnormalities of autoimmune thyroiditis (AIT) in the thyroid tissue samples. Compared with vehicle or low-dose Isaria felina, high-dose Isaria felina treatment resulted in significant reductions in white cell counts and circulating TSH, thyroid antibody, and cytokine levels of EAT mice. High-dose Isaria felina also alleviated histopathological abnormalities and attenuated TUNEL staining, Bcl-2 protein expression, and cleaved caspase-3 expression in the thyroid tissue samples.

CONCLUSION

High-dose Isaria felina treatment alleviates thyroid inflammation and cell apoptosis in EAT, serving as a novel, promising therapeutic agent for AIT.

The protective effect of iodide intake adjustment and 1,25(OH)2D3 supplementation in rat offspring following excess iodide intake

BACKGROUND

In this study, we aimed to investigate the effect of iodide intake adjustment, 1,25(OH)₂D₃ supplementation, or both, on the thyroid gland of rat offspring.

METHODS

The offspring of female rats administered 100 times the normal dose of iodide (100 HI; 750 μg/d) during pregnancy and lactation were divided into four different treatment groups. They were either having their iodide intake adjusted from 100 HI to normal iodide intake (7.5 μg/day) or supplemented with 25-hydroxy vitamin D₃ [1,25(OH)₂D₃; 5 μg·kg^-1·day^-1], or both, for 4 weeks. Thyroid sodium pertechnetate (Na^99mTcO₄) uptake percentages were measured using single-photon emission computed tomography, while serum levels of free triiodothyronine (FT3), free thyroxine (FT4), thyroglobulin antibody (TgAb), thyroid peroxidase antibody (TPOAb), and vitamin D3 (VD3) were monitored using enzyme-linked immunosorbent assay. The messenger ribonucleic acid expression of interleukin (IL)-17A, interferon gamma (IFN-γ), and IL-10 in the thyroid gland was measured using quantitative real-time polymerase chain reaction, while the protein expression of thyroid-hormone-receptor α1 (TRα1) and thyroid-hormone-receptor β1 (TRβ1) in the thyroid gland was detected using Western blotting. Haematoxylin and eosin (H & E) and immunofluorescence staining were also used to assess thyroid follicular structure and lymphocytic infiltration in the thyroid glands.

RESULTS

The immunofluorescence staining showed CD4⁺ co-localized with TRβ1 or the vitamin D receptor in thyroid gland cells of rats that were continuously treated with 100 HI. Following iodide adjustment, 1,25(OH)₂D₃ supplementation, or both, an increase in serum levels of FT3, free thyroxine, and VD3, protein expression of TRα1 and TRβ1 in the thyroid gland cells, and Na^99mTcO₄ thyroid uptake percentages was observed. The mRNA expression levels of IL-17A and IFN-γ, decreased, while the mRNA expression levels of IL-10 increased in the thyroid cells of each treatment group, except the group with continuous 100 HI intake.

CONCLUSION

Iodide adjustment, 1,25(OH)₂D₃ supplementation, or both may increase the serum levels of FT3, FT4, and VD3, as well as the protein expression levels of TRα1 and TRβ1, in thyroid cells. In addition, iodide adjustment, 1,25(OH)₂D₃ supplementation, or both, may potentially reverse the imbalance in pro-inflammatory and anti-inflammatory cytokines (IL-17A, IFN-γ, and IL-10) caused by 100 HI, which may be beneficial in improving Na^99mTcO₄ thyroid uptake percentages.

Susceptibility of influenza viruses to hypothiocyanite and hypoiodite produced by lactoperoxidase in a cell-free system

Lactoperoxidase (LPO) is an enzyme found in several exocrine secretions including the airway surface liquid producing antimicrobial substances from mainly halide and pseudohalide substrates. Although the innate immune function of LPO has been documented against several microbes, a detailed characterization of its mechanism of action against influenza viruses is still missing. Our aim was to study the antiviral effect and substrate specificity of LPO to inactivate influenza viruses using a cell-free experimental system. Inactivation of different influenza virus strains was measured in vitro system containing LPO, its substrates, thiocyanate (SCN^-) or iodide (I^-), and the hydrogen peroxide (H₂O₂)-producing system, glucose and glucose oxidase (GO). Physiologically relevant concentrations of the components of the LPO/H₂O₂/(SCN^-/I^-) antimicrobial system were exposed to twelve different strains of influenza A and B viruses in vitro and viral inactivation was assessed by determining plaque-forming units of non-inactivated viruses using Madin-Darby canine kidney cells (MDCK) cells. Our data show that LPO is capable of inactivating all influenza virus strains tested: H1N1, H1N2 and H3N2 influenza A viruses (IAV) and influenza B viruses (IBV) of both, Yamagata and Victoria lineages. The extent of viral inactivation, however, varied among the strains and was in part dependent on the LPO substrate. Inactivation of H1N1 and H1N2 viruses by LPO showed no substrate preference, whereas H3N2 influenza strains were inactivated significantly more efficiently when iodide, not thiocyanate, was the LPO substrate. Although LPO-mediated inactivation of the influenza B strains tested was strain-dependent, it showed slight preference towards thiocyanate as the substrate. The results presented here show that the LPO/H₂O₂/(SCN^-/I^-) cell-free, in vitro experimental system is a functional tool to study the specificity, efficiency and the molecular mechanism of action of influenza inactivation by LPO. These studies tested the hypothesis that influenza strains are all susceptible to the LPO-based antiviral system but exhibit differences in their substrate specificities. We propose that a LPO-based antiviral system is an important contributor to anti-influenza virus defense of the airways.