Showing papers by "Mary E. Wlodek published in 2019"

DNA Methyltransferase 1 Controls Nephron Progenitor Cell Renewal and Differentiation.

Abstract: BACKGROUND: Nephron number is a major determinant of long-term renal function and cardiovascular risk. Observational studies suggest that maternal nutritional and metabolic factors during gestation contribute to the high variability of nephron endowment. However, the underlying molecular mechanisms have been unclear. METHODS: We used mouse models, including DNA methyltransferase (Dnmt1, Dnmt3a, and Dnmt3b) knockout mice, optical projection tomography, three-dimensional reconstructions of the nephrogenic niche, and transcriptome and DNA methylation analysis to characterize the role of DNA methylation for kidney development. RESULTS: We demonstrate that DNA hypomethylation is a key feature of nutritional kidney growth restriction in vitro and in vivo, and that DNA methyltransferases Dnmt1 and Dnmt3a are highly enriched in the nephrogenic zone of the developing kidneys. Deletion of Dnmt1 in nephron progenitor cells (in contrast to deletion of Dnmt3a or Dnm3b) mimics nutritional models of kidney growth restriction and results in a substantial reduction of nephron number as well as renal hypoplasia at birth. In Dnmt1-deficient mice, optical projection tomography and three-dimensional reconstructions uncovered a significant reduction of stem cell niches and progenitor cells. RNA sequencing analysis revealed that global DNA hypomethylation interferes in the progenitor cell regulatory network, leading to downregulation of genes crucial for initiation of nephrogenesis, Wt1 and its target Wnt4. Derepression of germline genes, protocadherins, Rhox genes, and endogenous retroviral elements resulted in the upregulation of IFN targets and inhibitors of cell cycle progression. CONCLUSIONS: These findings establish DNA methylation as a key regulatory event of prenatal renal programming, which possibly represents a fundamental link between maternal nutritional factors during gestation and reduced nephron number.

What Evidence Do We Have for Pharmaceutical Galactagogues in the Treatment of Lactation Insufficiency?-A Narrative Review.

Abstract: Inadequate breast milk supply is a frequently reported reason for early discontinuation of breastfeeding and represents a critical opportunity for intervening to improve breastfeeding outcomes. For women who continue to experience insufficient milk supply despite the utilisation of non-pharmacological lactation support strategies, pharmacological intervention with medications used to augment lactation, commonly referred to as galactagogues, is common. Galactagogues exert their pharmacological effects through altering the complex hormonal milieu regulating lactation, particularly prolactin and oxytocin. This narrative review provides an appraisal of the existing evidence regarding the efficacy and safety of pharmaceutical treatments for lactation insufficiency to guide their use in clinical practice. The greatest body of evidence surrounds the use of domperidone, with studies demonstrating moderate short-term improvements in breast milk supply. Evidence regarding the efficacy and safety of metoclopramide is less robust, but given that it shares the same mechanism of action as domperidone it may represent a potential treatment alternative where domperidone is unsuitable. Data on remaining interventions such as oxytocin, prolactin and metformin is too limited to support their use in clinical practice. The review provides an overview of key evidence gaps and areas of future research, including the impacts of pharmaceutical galactagogues on breast milk composition and understanding factors contributing to individual treatment response to pharmaceutical galactagogues.

Periconceptional alcohol exposure causes female-specific perturbations to trophoblast differentiation and placental formation in the rat

Abstract: The development of pathologies during pregnancy, including pre-eclampsia, hypertension and fetal growth restriction (FGR), often originates from poor functioning of the placenta. In vivo models of maternal stressors, such as nutrient deficiency, and placental insufficiency often focus on inadequate growth of the fetus and placenta in late gestation. These studies rarely investigate the origins of poor placental formation in early gestation, including those affecting the pre-implantation embryo and/or the uterine environment. The current study characterises the impact on blastocyst, uterine and placental outcomes in a rat model of periconceptional alcohol exposure, in which 12.5% ethanol is administered in a liquid diet from 4 days before until 4 days after conception. We show female-specific effects on trophoblast differentiation, embryo-uterine communication, and formation of the placental vasculature, resulting in markedly reduced placental volume at embryonic day 15. Both sexes exhibited reduced trophectoderm pluripotency and global hypermethylation, suggestive of inappropriate epigenetic reprogramming. Furthermore, evidence of reduced placental nutrient exchange and reduced pre-implantation maternal plasma choline levels offers significant mechanistic insight into the origins of FGR in this model.

Exercise initiated during pregnancy in rats born growth restricted alters placental mTOR and nutrient transporter expression.

Abstract: Fetal growth is dependent on effective placental nutrient transportation, which is regulated by mTORC1 modulation of nutrient transporter expression. These transporters are dysregulated in pregnancies affected by uteroplacental insufficiency and maternal obesity. Nutrient transporters and mTOR were altered in placentae of mothers born growth restricted compared to normal birth weight dams, with maternal diet- and fetal sex-specific responses. Exercise initiated during pregnancy (PregEx) downregulated MTOR protein expression, despite an increase in mTOR activation in male associated placentae, and reduced nutrient transporter gene abundance, which was also dependent on maternal diet and fetal sex. Limited changes were characterised with exercise initiated before and continued throughout pregnancy (Exercise) in nutrient transporter and mTOR expression. Maternal exercise during pregnancy (PregEx) differentially regulated mTOR and nutrient transporters in a diet- and sex-specific manner, which likely aims to improve late gestational placental growth and neonatal survival. Adequate transplacental nutrient delivery is essential for fetoplacental development. Intrauterine growth restriction and maternal obesity independently alter placental nutrient transporter expression. Although exercise is beneficial for maternal health, limited studies have characterized how the timing of exercise initiation influences placental nutrient transport. Therefore, this study investigated the impact of maternal exercise on placental mTOR and nutrient transporter expression in growth restricted mothers and if these outcomes were dependent on maternal diet or fetal sex. Uteroplacental insufficiency (Restricted) or sham (Control) surgery was induced on embryonic day (E) 18 in Wistar-Kyoto rats. F1 offspring were fed a Chow or High-fat diet from weaning and at 16 weeks were randomly allocated an exercise protocol; Sedentary, Exercised prior to and during pregnancy (Exercise), or Exercised during pregnancy only (PregEx). Females were mated with normal males (20 weeks) and F2 placentae collected at E20. PregEx reduced mTOR protein expression in all groups and increased mTOR activation in male associated placentae. PregEx decreased the expression of amino acid transporters in a diet and sex-specific manner. Maternal growth restriction altered mTOR and system A amino acid transporter expression in a sex and diet specific manner. These data highlight that maternal exercise initiated during pregnancy alters placental mTOR expression, which may directly regulate amino acid transporter expression, to a greater extent than exercise initiated prior to and continued during pregnancy, in a diet and fetal sex dependent manner. These findings highlight that the timing of exercise initiation is important for optimal placental function. This article is protected by copyright. All rights reserved.

Reducing Pup Litter Size Alters Early Postnatal Calcium Homeostasis and Programs Adverse Adult Cardiovascular and Bone Health in Male Rats

Abstract: The in utero and early postnatal environments play essential roles in offspring growth and development. Standardizing or reducing pup litter size can independently compromise long-term health likely due to altered milk quality, thus limiting translational potential. This study investigated the effect reducing litter size has on milk quality and offspring outcomes. On gestation day 18, dams underwent sham or bilateral uterine vessel ligation surgery to generate dams with normal (Control) and altered (Restricted) milk quality/composition. At birth, pups were cross-fostered onto separate dams with either an unadjusted or reduced litter size. Plasma parathyroid hormone-related protein was increased in Reduced litter pups, whereas ionic calcium and total body calcium were decreased. These data suggest Reduced litter pups have dysregulated calcium homeostasis in early postnatal life, which may impair bone mineralization decreasing adult bone bending strength. Dams suckling Reduced litter pups had increased milk long-chain monounsaturated fatty acid and omega-3 docosahexaenoic acid. Reduced litter pups suckled by Normal milk quality/composition dams had increased milk omega-6 linoleic and arachidonic acids. Reduced litter male adult offspring had elevated blood pressure. This study highlights care must be taken when interpreting data from research that alters litter size as it may mask subtle cardiometabolic health effects.

Breastfeeding a small for gestational age infant, complicated by maternal gestational diabetes: a case report

Abstract: Small for gestational age (SGA) infants are those born small for their gestational age, with weight below the 10th percentile. Not only do SGA infants suffer growth issues after birth, they have elevated risk for the development of metabolic and cardiovascular diseases later in life. Current research has suggested that in cases of SGA infants, maternal milk and breastfeeding are not affected. The mother of an SGA infant was diagnosed with placental insufficiency and Gestational Diabetes Mellitus (GDM) during her pregnancy. The infant was born term, at 38 weeks 3 days, and SGA. The mother had a low milk supply and her milk composition differed from reference values such that the daily infant intake provided less than 50% of the required energy intake at 3 months. In cases of SGA and/or GDM, maternal milk quality and quantity may be compromised. This requires follow-up in order to reduce the disease risk for SGA infants and the corresponding public health implications.

Impact of Intrauterine Growth Restriction on the Capillarization of the Early Postnatal Rat Heart

Abstract: Capillarization plays a key role in the growth of the developing heart. We therefore hypothesized that impaired heart development following intrauterine growth restriction (IUGR) may arise from inadequate myocardial capillary growth. The aims of the study were to examine the effect of IUGR on the growth and diffusion radius of intramyocardial capillaries in rats at postnatal day 1. Uteroplacental insufficiency was induced in rats in late gestation (E18, term = E22) by bilateral uterine artery and vein ligation (restricted offspring N = 12; six males and six females); offspring from sham-operated dams were used as controls (N = 10; five males and five females). At postnatal day 1, the hearts were immersion-fixed and heart volume, capillary length density, capillary diffusion radius, and total capillary length were stereologically determined. Restricted offspring were significantly smaller at birth, with a concomitant reduction in heart volume and total myocardial capillary length compared to controls. Capillary growth was not impaired relative to heart size, with no significant differences in capillary length density or diffusion radius in the myocardium of restricted and control offspring. There were no sex differences in any of the parameters examined. In conclusion, there was no evidence to indicate that microvascular development is compromised in the heart of IUGR offspring at 1 day after birth. Total myocardial capillary length, however, was significantly reduced in the growth restricted offspring and further longitudinal studies are required to elucidate the long-term impact, particularly following hypertrophic cardiac growth. Anat Rec, 302:1580-1586, 2019. © 2018 American Association for Anatomy.

Periconceptional ethanol exposure induces a sex specific diuresis and increase in AQP2 and AVPR2 in the kidneys of aged rat offspring.

Abstract: Maternal alcohol consumption can impair renal development and program kidney dysfunction in offspring. Given that most women who drink alcohol cease consumption upon pregnancy recognition, we aimed to investigate the effect of alcohol around the time of conception (PC:EtOH) on offspring renal development and function. Rats received a liquid diet ±12.5% v/v ethanol from 4 days before to 4 days after mating. At postnatal day 30, nephron number was assessed. Urine flow and electrolyte (Na, K, Cl) excretion was measured at 6 and 19 months and blood pressure at 12 months. At 19 months, kidneys were collected for gene and protein analysis and assessment of collecting duct length. At postnatal day 30, PC:EtOH offspring had fewer nephrons. At 6 months, PC:EtOH exposure did not alter urine flow nor affect blood pressure at 12 months. At 19 months, female but not male offspring exposed to PC:EtOH drank more water and had a higher urine flow despite no differences in plasma arginine vasopressin (AVP) concentrations. Aqp2 mRNA and Avpr2 mRNA and protein expression was increased in kidneys from female PC:EtOH offspring but collecting duct lengths were similar. Immunofluorescent staining revealed diffuse cytoplasmic distribution of AQP2 protein in kidneys from PC:EtOH females, compared with controls with apical AQP2 localization. PC:EtOH resulted in a low nephron endowment and in female offspring, associated with age-related diuresis. Changes in expression and cellular localization of AQP2 likely underpin this disturbance in water homeostasis and highlight the need for alcohol to be avoided in early pregnancy.

The transgenerational effect of maternal and paternal F1 low birth weight on bone health of second and third generation offspring.

Abstract: Low birth weight programs diseases in adulthood, including adverse bone health. These diseases can have intergenerational and transgenerational origins, whereby transmission to subsequent generations occurs via both parental lines. Uteroplacental insufficiency surgery (Restricted) or sham surgery (Control) was performed on gestational day 18, in F0 Wistar-Kyoto rats. F1 Restricted males and females mated with breeders in order to generate F2 offspring of maternal and paternal lineages. F2 males and females were randomly selected for breeding to generate F3 offspring. F2 and F3 offspring did not have differences in birth weight irrespective of F1 low birth weight and parental line. Maternal line females had minor alterations to trabecular content and density at 6 months, these differences were not sustained at 12 months. Maternal line males had changes to trabecular content at 6 and 12 months; however, differences were no longer present at 16 months. Despite altered bone geometry at 12 and 16 months, bending strength remained unaffected at both ages. Bone health of paternal line females was not affected at 6 and 12 months. Paternal line males at 6 months had changes to trabecular and cortical content; cortical thickness, periosteal circumference and bending strength; however, these differences were no longer sustained at 12 and 16 months. Our data demonstrate that there is no transgenerational transmission of adverse bone health in F2 and F3 offspring, derived from low F1 birth weight females and males. Our results are novel, as bone health across generations and both parental lines has not been investigated in a model of low birth weight due to uteroplacental insufficiency.

Treadmill Exercise before and during Pregnancy Improves Bone Deficits in Pregnant Growth Restricted Rats without the Exacerbated Effects of High Fat Diet.

Abstract: Growth restriction programs adult bone deficits and increases the risk of obesity, which may be exacerbated during pregnancy. We aimed to determine if high-fat feeding could exacerbate the bone deficits in pregnant growth restricted dams, and whether treadmill exercise would attenuate these deficits. Uteroplacental insufficiency was induced on embryonic day 18 (E18) in Wistar Kyoto (WKY) rats using bilateral uterine vessel ligation (restricted) or sham (control) surgery. The F1 females consumed a standard or high-fat (HFD) diet from 5 weeks, commenced treadmill exercise at 16 weeks, and they were mated at 20 weeks. Femora and plasma from the pregnant dams were collected at post-mortem (E20) for peripheral quantitative computed tomography (pQCT), mechanical testing, histomorphometry, and plasma analysis. Sedentary restricted females had bone deficits compared to the controls, irrespective of diet, where such deficits were prevented with exercise. Osteocalcin increased in the sedentary restricted females compared to the control females. In the sedentary HFD females, osteocalcin was reduced and CTX-1 was increased, with increased peak force and bending stress compared to the chow females. Exercise that was initiated before and continued during pregnancy prevented bone deficits in the dams born growth restricted, whereas a HFD consumption had minimal bone effects. These findings further highlight the beneficial effects of exercise for individuals at risk of bone deficits.