Developmental programming: Impact of preconceptional and gestational exposure to a real-life environmental chemical mixture on maternal steroid, cytokine and oxidative stress milieus in sheep

BACKGROUND

Gestational exposure to environmental chemicals (ECs) is associated with adverse, sex-specific offspring health effects of global concern. As the maternal steroid, cytokine and oxidative stress milieus can have critical effects on pregnancy outcomes and the programming of diseases in offspring, it is important to study the impact of real-life EC exposure, i.e., chronic low levels of mixtures of ECs on these milieus. Sheep exposed to biosolids, derived from human waste, is an impactful model representing the ECs humans are exposed to in real-life. Offspring of sheep grazed on biosolids-treated pasture are characterized by reproductive and metabolic disruptions.

OBJECTIVE

To determine if biosolids exposure disrupts the maternal steroid, cytokine and oxidative stress milieus, in a fetal sex-specific manner.

METHODS

Ewes were maintained before mating and through gestation on pastures fertilized with biosolids (BTP), or inorganic fertilizer (Control). From maternal plasma collected mid-gestation, 19 steroids, 14 cytokines, 6 oxidative stress markers were quantified. Unpaired t-test and ANOVA were used to test for differences between control and BTP groups (n = 15/group) and between groups based on fetal sex, respectively. Correlation between the different markers was assessed by Spearman correlation.

RESULTS

Concentrations of the mineralocorticoids - deoxycorticosterone, corticosterone, the glucocorticoids - deoxycortisol, cortisol, cortisone, the sex steroids - androstenedione, dehydroepiandrosterone, 16-OH-progesterone and reactive oxygen metabolites were higher in the BTP ewes compared to Controls, while the proinflammatory cytokines IL-1β and IL-17A and anti-inflammatory IL-36RA were decreased in the BTP group. BTP ewes with a female fetus had lower levels of IP-10.

DISCUSSION

These findings suggest that pre-conceptional and gestational exposure to ECs in biosolids increases steroids, reactive oxygen metabolites and disrupts cytokines in maternal circulation, likely contributors to the aberrant phenotypic outcomes seen in offspring of BTP sheep - a translationally relevant precocial model.

Placental hypoxia: What have we learnt from small animal models?

Intrauterine hypoxia is a feature of pregnancy complications, both at high altitude and sea level. To understand the placental response to reduced oxygen availability, small animal models of maternal inhalation hypoxia (MIH) or reduced uterine perfusion pressure (RUPP) may be utilised. The aim of this review was to compare the findings of those studies to identify the role of oxygen availability in adapting placental structural and functional phenotypes in relation to fetal outcome. It also sought to explore the evidence for the involvement of particular genes and protein signalling pathways in the placenta in mediating hypoxia driven alterations. The data available demonstrate that both MIH and RUPP can induce placental hypoxia, which affects placental structure and vascularity, as well as glucose, amino acid, calcium and possibly lipid transport capacity. In addition, changes have been observed in HIF, VEGF, insulin/IGF2, AMPK, mTOR, PI3K and PPARγ signalling, which may be key in linking together observed phenotypes under conditions of placental hypoxia. Many different manipulations have been examined, with varied outcomes depending on the intensity, timing and duration of the insult. Some manipulations have detrimental effects on placental phenotype, viability and fetal growth, whereas in others, the placenta appears to adapt to uphold fetal growth despite the challenge of low oxygen. Together these data suggest a complex response of the placenta to reduced oxygen availability, which links to changes in fetal outcomes. However, further work is required to explore the role of fetal sex, altered maternal physiology and placental molecular mechanisms to fully understand placental responses to hypoxia and their relevance for pregnancy outcome.

Preeclampsia and low sodium (PALS): A case and systematic review

Normal physiologic changes in pregnancy include mild hyponatremia. In some cases of preeclampsia, more significant hyponatremia has been associated with syndrome of inappropriate antidiuretic hormone secretion and hypervolemic hyponatremia. A 45-year-old gravida 2, para 0010 with a dichorionic twin gestation was diagnosed with preeclampsia at 30 weeks 6 days and noted to have concomitant hyponatremia of 125 mEq/L at our institution. Her hyponatremia was initially managed with furosemide and water restriction. She was delivered at 33 weeks 5 days due to worsening preeclampsia and continued significant hyponatremia despite treatment. Her hyponatremia resolved within 48 h after delivery. Our objectives were to discuss trends, treatment, and outcomes of cases with hyponatremia in preeclampsia. We performed a systematic review of the literature using Ovid Medline (1963-2017), Scopus (1962-2017), and PubMed (1963-2017, including Cochrane database). Relevant articles describing any case report of hyponatremia in preeclampsia were identified from the above databases without any time, language, or study limitations. Studies were deemed eligible for inclusion if they described a case of hyponatremia in the setting of preeclampsia. 18 manuscripts detailing 55 cases were identified. Pertinent demographic data and laboratory values were extracted. Maternal management strategy, diagnosis, delivery, and neonatal outcome data were also collected. Mean, range, standard deviation, and percentage calculations were used as applicable. Advanced maternal age (46 %), nulliparity (79 %), and multifetal gestation (34 %) were noted in patients with preeclampsia and low sodium. Hyponatremia was detected on average at 34 weeks gestation. 64 % were diagnosed with preeclampsia with severe features. When reported, diagnoses related to hyponatremia were syndrome of inappropriate antidiuretic hormone secretion (41 %) or hypervolemic hyponatremia (59 %). Indications for delivery included severe hyponatremia unresponsive to conservative measures in addition to other known obstetric or preeclamptic indications. Hyponatremia resolved within 48 h on average in cases where postpartum resolution was reported. It may be prudent to screen women with preeclampsia for electrolyte disturbances as part of their evaluation, especially in the setting of severe features. Initially, hyponatremia may be treated with medical management. In addition to established obstetric or preeclamptic indications, delivery may be considered if severe hyponatremia no longer responds to conservative measures.

Trends of blood pressure and heart rate in normal pregnancies: a systematic review and meta-analysis

BACKGROUND

Current reference ranges for blood pressure and heart rate throughout pregnancy have a poor evidence base.

METHODS

This is a systematic review and meta-analysis. We included studies measuring blood pressure or heart rate from healthy pregnant women within defined gestational periods of 16 weeks or less. We analysed systolic blood pressure, diastolic blood pressure and heart rate by gestational age. We assessed effects of measurement year and method.

RESULTS

We included 39 studies undertaken in 1967-2017, containing 124,349 systolic measurements from 36,239 women, 124,291 diastolic measurements from 36,181 women and 10,948 heart rate measurements from 8317 women. Mean (95% CI) systolic blood pressure was lowest at 10 weeks gestation, 110.4 (108.5, 112.3) mmHg, rising to 116.0 (113.6, 118.4) mmHg at 40 weeks, mean (95% CI) change 5.6 (4.0, 7.2) mmHg. Mean (95% CI) diastolic blood pressure was lowest at 21 weeks gestation, 65.9 (64.2, 67.7) mmHg; rising to 72.8 (71.0, 74.6) mmHg at 40 weeks, mean (95% CI) change 6.9 (6.2, 7.5) mmHg. Mean (95% CI) heart rate rose from 79.3 (75.5, 83.1) beats/min at 10 weeks to 86.9 (82.2, 91.6) beats/min at 40 weeks gestation, mean (95% CI) change 7.6 (1.8, 13.4) beats/min. Studies using manual measurement reported higher diastolic blood pressures than studies using automated measurement, mean (95 CI) difference 4.9 (0.8, 8.9) mmHg. Diastolic blood pressure increased by 0.26 (95% CI 0.10-0.43) mmHg/year. Including only higher-quality studies had little effect on findings, with heterogeneity remaining high (I2 statistic > 50%).

CONCLUSIONS

Significant gestational blood pressure and heart rate changes occur that should be taken into account when assessing pregnant women. Commonly taught substantial decreases in blood pressure mid-pregnancy were not seen and heart rate increases were lower than previously thought. Manual and automated blood pressure measurement cannot be used interchangeably. Increases in diastolic blood pressure over the last half-century and differences between published studies show contemporary data are required to define current normal ranges.

STUDY REGISTRATION

PROSPERO CRD42014009673.

Maternal buprenorphine treatment during pregnancy and maternal physiology

BACKGROUND

Buprenorphine, used for opioid use disorder (OUD) treatment during pregnancy, provides unknown effects on maternal physiological activity. The primary aim of this report is to document acute effects of buprenorphine administration on indicators of maternal autonomic functioning. Effects of maternal buprenorphine dose and other substance exposures on maternal measures were examined, as were neonatal abstinence syndrome (NAS) outcomes.

METHODS

Forty-nine pregnant, buprenorphine-maintained women yielded maternal physiologic information (heart rate and variability, electrodermal activity, and respiratory rate) at 24, 28, 32 and 36 weeks gestation. Monitoring at trough and peak maternal medication levels was implemented to ascertain acute physiologic effects of buprenorphine administration.

RESULTS

Buprenorphine administration accelerated maternal heart rate and reduced variability at two gestational ages (24 and 36 weeks) and suppressed sympathetic (electrodermal) activation at 24, 28 and 32 weeks at times of peak maternal medication levels. Maternal autonomic parameters were unrelated to polysubstance exposure with the exception of cigarette smoking. Heavier smoking dampened maternal heart rate variability across gestation and potentiated reactivity to buprenorphine at 24 and 36 weeks. Heavier smoking was also associated with reduced electrodermal activity at 36 weeks. Buprenorphine dose was unrelated to observed effects. Larger degree of maternal heart rate reactivity to buprenorphine administration was related to more severe NAS expression.

CONCLUSIONS

These findings detail the maternal autonomic response to buprenorphine administration but also illustrate the significant effect of concurrent cigarette use on maternal autonomic regulation. This suggests the importance of smoking-reduction strategies in the comprehensive, medication-assisted treatment of women with OUD.

The role of maternal T cell and macrophage activation in preterm birth: Cause or consequence?

The role of the immune system in term (TL) and preterm labor (PTL) is unknown. Despite the fact that globally, PTL remains the most important cause of childhood mortality. Infection, typically of the fetal membranes, termed chorioamnionitis, is the best-understood driver of PTL, but the mechanisms underpinning other causes, including idiopathic and stretch-induced PTL, are unclear, but may well involve activation of the maternal immune system. The final common pathway of placental dysfunction, fetal membrane rupture, cervical dilation and uterine contractions are highly complex processes. At term, choriodecidual rather than myometrial inflammation is thought to drive the onset of labor and similar findings are present in different types of PTL including idiopathic PTL. Although accumulated data has confirmed an association between the immune response and preterm birth, there is yet a need to understand if this response is an initiator or a consequence of tissue-level dysregulation. This review focuses on the potential role of macrophages and T cells in innate and adaptive immunity relevant to preterm birth in humans and animal models.