Association of Maternal Hypothyroidism With Cardiovascular Diseases in the Offspring

THRA1/PGC-1α/SIRT3 pathway regulates oxidative stress and is implicated in hypertension of maternal hypothyroid rat offspring

Many epidemiologic and animal studies have shown that maternal hypothyroidism is associated with an increased risk of hypertension in offspring in later life. In this study, we established a maternal hypothyroidism rat model to explore the underlying mechanism that contributes to elevated blood pressure in adult male offspring of hypothyroid mothers. The levels of thyroid hormones (THs) in the offspring were measured using ELISA kits. Blood pressure (BP) and depressor response were recorded in conscious, freely moving rats. Vascular reactivity was conducted in isolated mesenteric arteries (MAs) using a myograph. We used real-time quantitative PCR (RT-qPCR) and Western blots to examine the mRNA and protein expression of relevant molecules in MAs. The A7r5 cells were transfected with small interfering RNA (siRNA) to further investigate the gene functions. The following findings were observed: Basal systolic BP and diastolic BP was significantly increased, accompanied by attenuated depressor response and decreased vascular sensitivity to sodium nitroprusside (SNP). Reactive Oxygen Species (ROS) levels in the MAs were enhanced, along with decreased expression of the THRA1/PGC-1α/SIRT3 pathway. In A7r5 cells, triiodothyronine (T3) pretreatment improved the PGC-1α/SIRT3 pathway and reduced ROS levels after H2O2-induced oxidative stress. In contrast, the knockdown of THRA1 or SIRT3 diminished the above effects of T3. Down-regulation of THRA1 contributed to a decline in the PGC-1α/SIRT3 pathway, which causes an increased production of ROS. This indicates that the T3-THRA1/PGC-1α/SIRT3 pathway plays a protective role in the regulation of BP and may be a potential therapeutic strategy against hypertension.

Sex-specific effect of maternal thyroid peroxidase antibody exposure during pregnancy on 5- to 6-year-old children's cardiometabolic risk score: the Ma'anshan birth cohort study

OBJECTIVE

To explore the association between maternal thyroid peroxidase antibody (TPOAb) exposure and 5- to 6-year-old children's cardiometabolic risk (CMR).

METHODS

A total of 2129 mother-child pairs were recruited from the Ma'anshan Birth Cohort (MABC) study. Serum TPOAb was retrospectively measured in pregnant women using an electrochemiluminescence immunoassay. CMR score was evaluated by the serum glycolipids, blood pressure, and waist circumference for children aged 5-6 years. Growth mixture modelling was used to fit trajectories of TPOAb levels throughout pregnancy. Multiple linear regression models and logistic regression models were used for statistical analyses.

RESULTS

Two thousand one hundred twenty-nine mother-child pairs (mean [SD] age, 26.6 [3.6] years) were enrolled for the final study. Maternal TPOAb exposure in the first trimester increased children's overall CMR, glucose level, HOMA-IR, triglyceride level, boys' overall CMR, boys' glucose level, and girls' glucose level. TPOAb exposure in the first trimester was also associated with lower boys' high-density lipoprotein cholesterol (HDL-C) level. In the second trimester, maternal TPOAb exposure was positively associated with children's triglyceride level. Compared with low TPOAb trajectory, children with high maternal TPOAb trajectory had an increased risk of developing high CMR (OR = 3.40; 95% CI, 1.30-8.90), hyperglycemia (OR = 5.20; 95% CI, 2.20-12.28), insulin-resistance (adjusted OR = 2.12; 95% CI, 1.10-4.07), and hypertriglyceridemia (OR = 2.55; 95% CI, 1.06-6.14).

CONCLUSIONS

The first trimester of pregnancy is a critical period for maternal TPOAb exposure to affect CMR in children, with some sex specificity, mainly to the detriment of boys.

Maternal hypothyroidism and subsequent metabolic outcomes in children: a systematic review and meta-analysis

INTRODUCTION

As the fetus relies on maternal thyroid hormones in early pregnancy, maternal hypothyroidism plays an important role in fetal development. However, the association between maternal hypothyroidism and metabolic disease in offspring is unclear.

OBJECTIVE

To examine the association between maternal hypothyroidism in pregnancy and metabolic outcomes (obesity, hypertension, type 2 diabetes mellitus, and dyslipidemia) in children < 18 years.

METHODS

We systematically searched 5 databases from inception to May 2023. Eligible studies included cohort, case-control, and randomized controlled trials involving children born to mothers with or without hypothyroidism in pregnancy. Data were pooled across studies using random-effects models for outcomes reported in at least three studies. Quality assessment was performed using the ROBINS-E tool for observational studies and the Cochrane Risk of Bias tool for trials.

RESULTS

The search identified 3221 articles, of which 7 studies were included (1 trial, 6 observational). All studies were conducted outside of North America and ranged in size from 250 to > 1 million children. The follow-up time ranged from 6 to 20 years. Included studies support an increased risk of hypertension and glucose dysregulation in offspring exposed to maternal hypothyroidism (hypertension: OR 1.08, 95% CI 0.75, 1.57 and HR 1.81, 95% CI 1.21, 2.69; diabetes: RR 2.7, 95% CI 0.7, 10). In the pooled analysis, maternal hypothyroidism was not associated with obesity in offspring (OR 1.04, 95% CI 0.64, 1.70).

CONCLUSION

This study found inconsistent evidence on the association between maternal hypothyroidism in pregnancy and metabolic outcomes in offspring, though associations with hypertension and glucose dysregulation are possible.

HDAC1/2/3-mediated downregulation of neurogranin is involved in cognitive impairment in offspring exposed to maternal subclinical hypothyroidism

Subclinical hypothyroidism (SCH) in pregnancy is the most common form of thyroid dysfunction in pregnancy, which can affect fetal nervous system development and increase the risk of neurodevelopmental disorders after birth. However, the mechanism of the effect of maternal subclinical hypothyroidism on fetal brain development and behavioral phenotypes is still unclear and requires further study. In this study, we constructed a mouse model of maternal subclinical hypothyroidism by exposing dams to drinking water containing 50 ppm propylthiouracil (PTU) during pregnancy and found that its offspring were accompanied by severe cognitive deficits by behavioral testing. Mechanistically, gestational SCH resulted in the upregulation of protein expression and activity of HDAC1/2/3 in the hippocampus of the offspring. ChIP analysis revealed that H3K9ac on the neurogranin (Ng) promoter was reduced in the hippocampus of the offspring of SCH, with a significant reduction in Ng protein, leading to reduced expression levels of synaptic plasticity markers PSD95 (a membrane-associated protein in the postsynaptic density) and SYN (synaptophysin, a specific marker for presynaptic terminals), and impaired synaptic plasticity. In addition, administration of MS-275 (an HDAC1/2/3-specific inhibitor) to SCH offspring alleviated impaired synaptic plasticity and cognitive dysfunction in offspring. Thus, our study suggests that maternal subclinical hypothyroidism may mediate offspring cognitive dysfunction through the HDAC1/2/3-H3K9ac-Ng pathway. Our study contributes to the understanding of the signaling mechanisms underlying maternal subclinical hypothyroidism-mediated cognitive impairment in the offspring.

Association of maternal thyroid disease with obesity in child

OBJECTIVES

During pregnancy, many women develop thyroid disorders, which can result in fetal and neonatal development defects. We investigated whether maternal thyroid dysfunction would affect their children's growth and obesity.

STUDY DESIGN

We conducted a nationwide population-based cohort study using a combination of data from several Korean nationwide registries to investigate the association between maternal thyroid dysfunction, offspring growth, and obesity. Childhood growth was repeatedly measured at three periods of age from 42 to 80 months, using body mass index (BMI).

RESULTS

A total of 1,123,499 women were enrolled in this study; 78,902 (7.0 %) had pre-pregnancy thyroid disease. Significant association was found between maternal hyperthyroidism and obesity in all children aged 42-66 months (42-54 months, adjusted odds ratio (aOR) 0.93, 95 % confidence interval (CI) 0.89-0.98; 54-66 months, aOR 0.93, 95 % CI 0.87-0.99), but not at later ages. In the analysis by sex, maternal hyperthyroidism was associated with childhood obesity in boys, whereas it was not associated with those in girls of any age. No association was observed between maternal hypothyroidism and child BMI or obesity.

CONCLUSIONS

The association between maternal thyroid function and obesity in offspring is attenuated from early to late childhood, suggesting that many other factors may be involved in developing childhood obesity.

Fetal cardiac left ventricle functional changes in pregnancies with maternal hypothyroidism

OBJECTIVES

To evaluate fetal cardiac function in cases with overt and subclinical hypothyroidism and to determine the effect of levothyroxine (LT4) treatment and Anti-thyroid peroxidase (Anti-TPO) antibody status on fetal cardiac functions in cases with subclinical hypothyroidism.

METHODS

Within the scope of the study, fetuses of 23 overt hypothyroid, 52 subclinical hypothyroid and 250 control group pregnant women were evaluated. Fetal cardiac function was assessed via cardiac Doppler.

RESULTS

Isovolumetric relaxation time (IRT) and myocardial performance index (MPI) values in the overt hypothyroid group were significantly higher than both the subclinical hypothyroid group (p: .006, p: .000, respectively) and the control group (p: .000, p: .000, respectively). In addition, both IRT and MPI were significantly higher in the subclinical hypothyroid group than in the control group (p: .000, p: .000, respectively). In the subclinical hypothyroid group, there was no significant difference in terms of cardiac function parameters in the fetuses of pregnant women who received LT4 therapy and those who did not. When pregnant women with subclinical hypothyroidism were evaluated according to their Anti-TPO antibody status, IRT and MPI values were found to be significantly higher in fetuses of Anti-TPO (+) pregnant women (respectively, p: .005, p: .019).

CONCLUSION

In the presence of maternal overt or subclinical hypothyroidism, fetal cardiac functions may be affected as early as the second trimester. Anti-TPO antibody positivity in cases with subclinical hypothyroidism seems to negatively affect fetal cardiac functions.

Effects of maternal hypothyroidism on postnatal cardiomyocyte proliferation and cardiac disease responses of the progeny

Maternal hypothyroidism (MH) could adversely affect the cardiac disease responses of the progeny. This study tested the hypothesis that MH reduces early postnatal cardiomyocyte (CM) proliferation so that the adult heart of MH progeny has a smaller number of larger cardiac myocytes, which imparts adverse cardiac disease responses following injury. Thyroidectomy (TX) was used to establish MH. The progeny from mice that underwent sham or TX surgery were termed Ctrl (control) or MH (maternal hypothyroidism) progeny, respectively. MH progeny had similar heart weight (HW) to body weight (BW) ratios and larger CM size consistent with fewer CMs at postnatal day 60 (P60) compared with Ctrl (control) progeny. MH progeny had lower numbers of EdU+, Ki67+, and phosphorylated histone H3 (PH3)+ CMs, which suggests they had a decreased CM proliferation in the postnatal timeframe. RNA-seq data showed that genes related to DNA replication were downregulated in P5 MH hearts, including bone morphogenetic protein 10 (Bmp10). Both in vivo and in vitro studies showed Bmp10 treatment increased CM proliferation. After transverse aortic constriction (TAC), the MH progeny had more severe cardiac pathological remodeling compared with the Ctrl progeny. Thyroid hormone (T4) treatment for MH mothers preserved their progeny's postnatal CM proliferation capacity and prevented excessive pathological remodeling after TAC. Our results suggest that CM proliferation during early postnatal development was significantly reduced in MH progeny, resulting in fewer CMs with hypertrophy in adulthood. These changes were associated with more severe cardiac disease responses after pressure overload.NEW & NOTEWORTHY Our study shows that compared with Ctrl (control) progeny, the adult progeny of mothers who have MH (MH progeny) had fewer CMs. This reduction of CM numbers was associated with decreased postnatal CM proliferation. Gene expression studies showed a reduced expression of Bmp10 in MH progeny. Bmp10 has been linked to myocyte proliferation. In vivo and in vitro studies showed that Bmp10 treatment of MH progeny and their myocytes could increase CM proliferation. Differences in CM number and size in adult hearts of MH progeny were linked to more severe cardiac structural and functional remodeling after pressure overload. T4 (synthetic thyroxine) treatment of MH mothers during their pregnancy, prevented the reduction in CM number in their progeny and the adverse response to disease stress.

Prenatal hypothyroidism diminished exogenous NO-mediated diastolic effects in fetal rat thoracic aorta smooth muscle via increased oxidative stress

Maternal hypothyroidism is an important problem of modern healthcare and is reported to increase the risk of cardiovascular diseases in the offspring later in life. However, it is unclear whether hypothyroidism during pregnancy causes vascular damage in the fetal period. We established the prenatal hypothyroidism rat model and collected the fetuses at the 21th day of gestation (GD21). Thyroid hormone concentrations in maternal and offspring blood serum were assessed by enzyme-linked immunosorbent assay (ELISA). The thoracic aortas of the fetuses were isolated for microvessel functional testing and histochemical stainings. qPCR and Western blot were performed to access mRNA and protein expression. We found that the concentrations of thyroid hormones in the serum of pregnant rats and fetuses were significantly suppressed at GD21. The responses of the fetal thoracic aortas to SNP were significantly attenuated in the PTU group. However, no statistical difference was found between the two groups when treated with either inhibitor (ODQ) or activator (BAY58-2667) of sGC. The production of O₂^-• in the arterial wall was significantly increased in hypothyroid fetuses. Moreover, the level of NADPH oxidase (NOX) was increased, while superoxide dismutase 2 (SOD2) was down-regulated in the PTU group, ultimately contributing to the increased production of superoxide. Additionally, decreased SNP-mediated vasodilation found in fetal vessels was improved by either NOX inhibitor (Apocynin) or SOD mimic (Tempol). These results indicate that increased oxidative stress is probably the cause of the diminished diastolic effect of exogenous NO in the thoracic artery of prenatal hypothyroidism exposed fetuses.

Region-specific effects of antenatal/early postnatal hypothyroidism on endothelial NO-pathway activity in systemic circulation

Background

Antenatal/early postnatal hypothyroidism weakens NO-mediated anticontractile influence of endothelium in coronary arteries of adult rats, but it remains unclear whether this occurs in other vascular regions. We hypothesized that developmental thyroid deficiency is followed by region-specific changes in the endothelial NO-pathway activity in systemic vasculature. To explore this, we estimated the effects of antenatal/early postnatal hypothyroidism on NO-pathway activity and its potential local control mechanisms in rat mesenteric and skeletal muscle (sural) arteries.

Methods

Dams were treated with 6-propyl-2-thiouracil (PTU) in drinking water (0.0007%) during pregnancy and 2 weeks postpartum; control (CON) females received PTU-free water. Adult offspring (10–12-weeks) arteries were studied by wire myography, qPCR, and Western blotting.

Results

Endothelium removal or inhibition of NO-synthase with L-NNA augmented contractile responses to α₁-adrenoceptor agonist methoxamine. In PTU compared to CON group, these effects were stronger in sural arteries, but did not differ in mesenteric arteries. The responses of both arteries to NO-donor DEA/NO were similar in CON and PTU rats. mRNA contents of deiodinase 2 and thyroid hormone receptor α were similar in mesenteric arteries of two groups but were elevated in sural arteries of PTU group compared to CON. The abundance of eNOS protein was higher in sural arteries of PTU compared to CON rats.

Conclusion

Antenatal/early postnatal hypothyroidism is followed by an increase in NO-mediated anticontractile influence in sural, but not in mesenteric arteries of adult animals. The diversity of hypothyroidism effects may be due to different alterations of local T3 synthesis/reception in different vascular beds.

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Antenatal hypothyroidism increases anticontractile NO-effect in sural arteries.

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Antenatal hypothyroidism doesn't change anticontractile effect in mesenteric arteries.

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Diverse hypothyroidism effects may be due to the differences in local T3 signaling.