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Early restriction of placental growth results in placental structural and gene expression changes in late gestation independent of fetal hypoxemia.

ABSTRACT: Placental restriction and insufficiency are associated with altered patterns of placental growth, morphology, substrate transport capacity, growth factor expression, and glucocorticoid exposure. We have used a pregnant sheep model in which the intrauterine environment has been perturbed by uterine carunclectomy (Cx). This procedure results in early restriction of placental growth and either the development of chronic fetal hypoxemia (PaO2?17 mmHg) in late gestation or in compensatory placental growth and the maintenance of fetal normoxemia (PaO2>17 mmHg). Based on fetal PaO2, Cx, and Control ewes were assigned to either a normoxemic fetal group (Nx) or a hypoxemic fetal group (Hx) in late gestation, resulting in 4 groups. Cx resulted in a decrease in the volumes of fetal and maternal connective tissues in the placenta and increased placental mRNA expression of IGF2, vascular endothelial growth factor (VEGF), VEGFR-2, ANGPT2, and TIE2 There were reduced volumes of trophoblast, maternal epithelium, and maternal connective tissues in the placenta and a decrease in placental GLUT1 and 11?HSD2 mRNA expression in the Hx compared to Nx groups. Our data show that early restriction of placental growth has effects on morphological and functional characteristics of the placenta in late gestation, independent of whether the fetus becomes hypoxemic. Similarly, there is a distinct set of placental changes that are only present in fetuses that were hypoxemic in late gestation, independent of whether Cx occurred. Thus, we provide further understanding of the different placental cellular and molecular mechanisms that are present in early placental restriction and in the emergence of later placental insufficiency.

SUBMITTER: Zhang S

PROVIDER: S-EPMC5357827 | biostudies-literature | 2016 Dec

REPOSITORIES: biostudies-literature

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Early restriction of placental growth results in placental structural and gene expression changes in late gestation independent of fetal hypoxemia.

Zhang Song S Barker Paige P Botting Kimberley J KJ Roberts Claire T CT McMillan Christine M CM McMillen Isabella Caroline IC Morrison Janna L JL

Physiological reports 20161201 23

Placental restriction and insufficiency are associated with altered patterns of placental growth, morphology, substrate transport capacity, growth factor expression, and glucocorticoid exposure. We have used a pregnant sheep model in which the intrauterine environment has been perturbed by uterine carunclectomy (Cx). This procedure results in early restriction of placental growth and either the development of chronic fetal hypoxemia (PaO<sub>2≤</sub>17 mmHg) in late gestation or in compensatory ...[more]

PMID: 27923976

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Project description:Fetal growth restriction (FGR) occurs when the fetus does not reach its genetically programmed intrauterine potential for growth and affects ~5‑10% of pregnancies. This condition is one of the leading causes of perinatal mortality and morbidity associated with obstetric and neonatal complications. Placental dysfunction in FGR causes an impairment in the transfer of nutrients and oxygen from the mother to the developing fetus. Maternal adaptations to placental insufficiency may also play a role in the pathophysiology of FGR. The present study aimed to compare the proteome of the placentas of 18 women with the physiological course of pregnancy and eutrophic fetus [estimated fetal weight (EFW) >10th percentile; control group] and 18 women with late FGR (EFW <10th percentile) diagnosed after 32 weeks of pregnancy, according to the Delphi consensus (study group). The U. Mann‑Whitney test was used to compare two independent groups. The R. Spearman correlation coefficient significance test was used to assess the existence of a relationship between the analyzed measurable parameters. P<0.05 was considered to indicate a statistically significant difference. The tests showed the presence of 356 different proteins which were responsible for the regulation of gene transcription control, inhibiting the activity of proteolytic enzymes, regulation of trophoblast proliferation and angiogenesis and inflammatory response. In the FGR placental proteome, other detected proteins were mostly involved in response to oxidative stress, cellular oxidation and detoxication, apoptosis, hemostatic and catabolic processes, energy transduction protein interactions, cell proliferation, differentiation and intracellular signaling. The present study used chromatographic mass‑spectrometry to compare the placental proteome profiles in pregnancies complicated by late‑onset FGR and normal pregnancy. Comparative analysis of proteomes from normal and FGR placentas showed significant differences. Further research is needed to clarify maternal and fetal adaptations to FGR.

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Project description:Manipulating maternal nutrition during specific periods of gestation can result in re-programming of fetal and post-natal development. In this experiment we investigated how a feed restriction of 85% compared with 140% of total metabolizable energy requirements, fed to cows during mid-to-late gestation, influences phenotypic development of fetuses and mRNA expression of growth (Insulin-Like Growth Factor family and Insulin Receptor (INSR)), myogenic (Myogenic Differentiation 1 (MYOD1), Myogenin (MYOG), Myocyte Enhancer Factor 2A (MEF2A), Serum Response Factor (SRF)) and adipogenic (Peroxisome Proliferator Activated Receptor Gamma (PPARG)) genes in fetal longissimus dorsi (LD) and semitendinosus (ST) muscle. DNA methylation of imprinted genes, Insulin Like Growth Factor 2 (IGF2) and Insulin Like Growth Factor 2 Receptor (IGF2R), and micro RNA (miRNA) expression, were also examined as potential consequences of poor maternal nutrition, but also potential regulators of altered gene expression patterns.While the nutrient restriction impacted dam body weight, no differences were observed in phenotypic fetal measurements (weight, crown-rump length, or thorax circumference). Interestingly, LD and ST muscles responded differently to the differential pre-natal nutrient levels. While LD muscle of restricted fetal calves had greater mRNA abundances for Insulin Like Growth Factor 1 and its receptor (IGF1 and IGF1R), IGF2R, INSR, MYOD1, MYOG, and PPARG, no significant differences were observed for gene expression in ST muscle. Similarly, feed restriction had a greater impact on the methylation level of IGF2 Differentially Methylated Region 2 (DMR2) in LD muscle as compared to ST muscle between treatment groups. A negative correlation existed between IGF2 mRNA expression and IGF2 DMR2 methylation level in both LD and ST muscles. Differential expression of miRNAs 1 and 133a were also detected in LD muscle.Our data suggests that a nutrient restriction of 85% as compared to 140% of total metabolizable energy requirements during the 2nd half of gestation can alter the expression of growth, myogenic and adipogenic genes in fetal muscle without apparent differences in fetal phenotype. It also appears that the impact of feed restriction varies between muscles suggesting a priority for nutrient partitioning depending on muscle function and/or fiber composition. Differences in the methylation level in IGF2, a well-known imprinted gene, as well as differences in miRNA expression, may be functional mechanisms that precede the differences in gene expression observed, and could lead to trans-generational epigenetic programming.

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Dataset Information

Early restriction of placental growth results in placental structural and gene expression changes in late gestation independent of fetal hypoxemia.

Publications

Early restriction of placental growth results in placental structural and gene expression changes in late gestation independent of fetal hypoxemia.

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