Placental expression of miR-21-5p, miR-210-3p and miR-141-3p: relation to human fetoplacental growth.

BACKGROUND/OBJECTIVES: Dysregulation of microRNAs (miRNAs) and their target genes in placental tissue is associated with foetal growth restriction. We aimed to evaluate associations of placental miR-21-5p, miR-141-3p and miR-210-3p expression with maternal, placental and newborn parameters and with placental expression of their potential target genes PTEN, VEGF, FLT and ENG in a set of well-characterized small- (SGA) and appropriate- (AGA) for gestational age full-term singleton pregnancies. SUBJECTS/METHODS: Placental samples (n = 80) from 26 SGA and 54 AGA were collected from full-term singleton pregnancies. Placental transcript abundances of miR-21-5p, miR-141-3p and miR-210-3p were assessed after normalization to a reference miRNA, mir-16-5p by real-time quantitative PCR. Placental transcript abundances of PTEN, VEGF, FLT and ENG were assessed after normalizing to a panel of reference genes. RESULTS: Placental miR-21-5p transcript abundance was negatively associated with placental weight (n = 80, r = -0.222, P = 0.047) and this association was specific to the AGA births (n = 54, r = -0.292, P = 0.032). Placental transcript abundances of miR-210-3p and miR-141-3p were not associated with placental weight or birth weight in all 80 births. However, placental miR-210-3p transcript abundance was positively associated with birth weight specifically in the SGA births (n = 26, r = 0.449, P = 0.021). Placental transcript abundance of miR-21-5p was negatively associated with PTEN transcript abundance (Spearman's ρ = -0.245, P = 0.028) while that of miR-141-3p was positively associated with FLT (Spearman's ρ = 0.261, P = 0.019) and ENG (Spearman's ρ = 0.259, P = 0.020) transcript abundances in all 80 births. CONCLUSION: We conclude that placental miR-21-5p and miR-210-3p may be involved in fetoplacental growth. However, this regulation is unlikely to be mediated through placental expression of PTEN, VEGF, FLT or ENG.

Placental expression of RNU44, RNU48 and miR-16-5p: stability and relations with fetoplacental growth.

BACKGROUND/OBJECTIVES: The current study aimed to identify suitable reference miRNA for placental miRNA expression analysis in a set of well-characterized and fetal-sex balanced small- (SGA) and appropriate- (AGA) for gestational age full-term singleton pregnancies. SUBJECTS/METHODS: In this retrospective study, placental samples (n = 106) from 35 SGA (19 male and 16 female) and 71 AGA (30 male and 41 female) full-term singleton pregnancies were utilized. Placental transcript abundance of three widely used reference miRNAs [miR-16-5p and Small nucleolar RNAs (snoRNAs) RNU44 and RNU48] were assessed by real-time quantitative PCR. Raw cycle threshold (Ct) analysis and RefFinder tool analysis were conducted for evaluating stability of expression of these miRNAs. RESULTS: Raw Ct values of miR-16-5p were similar between SGA and AGA births (P = 0.140) and between male and female births within SGA (P = 0.159) and AGA (P = 0.060) births while that of RNU44 and RNU48 were higher in SGA births (P = 0.008 and 0.006 respectively) and in male births within the SGA group (P = 0.005) for RNU44 and in female births within the AGA group (P = 0.048) for RNU48. Across all 106 samples tested using the RefFinder tool, miR-16-5p and RNU44 were equally stable reference miRNAs. CONCLUSION: We recommend miR-16-5p and RNU44 as suitable reference miRNAs for placental samples from settings similar to our study.

Placental expression of leptin: fetal sex-independent relation with human placental growth.

OBJECTIVES: Leptin (LEP) is a vital placental hormone that is known to affect different aspects of placental function and fetal development. The present study aimed to determine the association of placental LEP transcript abundance with maternal, placental, and newborn parameters. SUBJECTS/METHODS: In this retrospective case-control study, placental samples (n = 105) were collected from small (SGA) and appropriate (AGA) for gestational age full-term singleton pregnancies (n = 44 SGA and n = 61 AGA). Placental transcript abundance of LEP was assessed by real-time quantitative PCR after normalization to a reference gene panel. LEP methylation was measured using a quantitative MethyLight assay in a subset of samples (n = 54). RESULTS: Placental LEP transcript abundance was negatively and significantly associated with placental weight (ß = -3.883, P = 0.015). This association continued to be significant in the SGA group (ß = -10.332, P = 0.001), both in female (ß = -15.423, P = 0.021) and male births (ß = -10.029, P = 0.007). LEP transcript abundance was not associated with LEP methylation levels (Spearman's ρ = 0.148, P = 0.287). CONCLUSION: We conclude that placental upregulation of LEP is an integral and fetal sex-independent component of placental growth restriction, which can be potentially targeted through maternal dietary modifications to improve fetoplacental growth.

Placental expression of ENG, VEGF, and FLT: Gender-specific associations with maternal vitamin B12 status.

OBJECTIVES: Adequate vitamin B12 is a requisite during pregnancy and its deficiency is linked with increased risk for adverse outcomes, likely mediated by impaired placental angiogenesis. Thus, we aimed to test associations of maternal vitamin B12 status with the placental expression of angiogenesis-associated genes ENG, VEGF, and FLT. SUBJECTS/METHODS: In this retrospective case-control study, placental and maternal trimester 1 blood samples (n = 104) were collected from small for gestational age (SGA) and appropriate for gestational age (AGA) full-term singleton pregnancies. Maternal trimester 1 vitamin B12 status was measured. Placentae and neonates were weighed at birth. Realtime quantitative PCR was performed to assess placental transcript abundance of ENG, VEGF, and FLT normalized to a panel of reference genes. Associations of placental transcript abundance of the genes with maternal trimester 1 vitamin B12 status were evaluated. RESULTS: Placental ENG transcript abundance associated negatively with maternal trimester 1 vitamin B12 status (ß = -0.461, P = 0.017, n = 104). This association was specific to the female births (ß = -0.590, P = 0.014, n = 60). Placental VEGF transcript levels were negatively associated with maternal trimester 1 vitamin B12 status only in the female births (ß = -1.995, P = 0.029). Placental FLT transcript levels were not associated with maternal trimester 1 vitamin B12 status. CONCLUSION: Maternal trimester 1 vitamin B12 status was associated negatively with placental ENG and VEGF expression predominantly in the female births. Therefore, we hypothesize that the placenta adapts to low maternal vitamin B12 status by up-regulating angiogenic pathways in a gender-specific manner.

Eccentric placentae have reduced surface area and are associated with lower birth weight in babies small for gestational age.

Placental structure and function determine birth outcomes. Placental mass does not always correlate with fetal birth weight (BW) in uncomplicated pregnancies which raises the possibility of other variables such as placental shape and cord insertion being the determinants of placental efficiency. In total, 160 women with singleton pregnancy, recruited into a pregnancy cohort were studied. Placental weight (PW) was measured and other data were obtained from clinical records. Birth outcomes were classified as small for gestational age (SGA) and appropriate for gestational age (AGA) based on fetal gender, gestational age (GA) and BW. High-resolution images of the chorionic plate were recorded. The shape of the placenta and the insertion of the cord were measured using eccentricity index (EI) and cord centrality index (CCI). Only placentae with eccentrically inserted cords (n=136) were included. The mean BW and PW were 2942 (±435) g and 414 (±82) g with average GA of 38.6 weeks. The mean CCI and EI was 0.483 (±0.17) and 0.482 (±0.16). Neither of these correlated with placental efficiency. However, EI showed negative correlation with placental surface area and breadth. Upon sub-grouping the cohort into SGA (n=32) and AGA (n=104), the SGA babies with the highest EI (third tertile) had significantly lower BW than those with the least eccentric placentae (first tertile). Although eccentric-shaped placentae were present in both SGA and AGA groups, the effect on BW was observed only in the SGA group.

Placental expression of DNA methyltransferase 1 (DNMT1): Gender-specific relation with human placental growth.

AIMS: Placental physiology and morphology is critically regulated by DNA methylation. As such, placental global DNA methylation and transcript abundance of placental DNA methyltransferases (DNMT1 and DNMT3A) may relate to placental and fetal growth in human pregnancies. We aimed to test correlations of human fetoplacental parameters and birth weight with the placental expression of DNA methyltransferases (DNMT1 and DNMT3A) and placental global methylation. SUBJECTS AND METHODS: Placentae (n = 109) were collected from small- (SGA) and appropriate- (AGA) for gestational age full-term singleton pregnancies (n = 56 SGA and 53 AGA). Placentae and neonates were weighed at birth. Realtime quantitative PCR was performed to assess placental transcript abundance of DNMT1, DNMT3A and DNTMT3B normalized to a panel of reference genes. LINE-1 methylation was measured using a quantitative MethyLight assay in a subset of samples (n = 68). Associations of placental transcript abundances of DNMT1, DNMT3A and DNMT3B and of LINE-1 methylation levels with maternal, placental and neonatal parameters were tested. RESULTS: Placental DNMT1 transcript abundance associated positively with placental weight (ß = 10.21, P = 0.013). This association was specific to the AGA births (ß = 12.77, P = 0.022) and was absent in the SGA births. Association of DNMT1 expression with placental weight and birth weight within the AGA births was specific to the female gender (Birth weight: ß = 83.61, P = 0.043; Placental weight: ß = 23.92, P = 0.025). Placental DNMT1 transcript levels were not different according to SGA status or gender. Placental DNMT3A transcript levels and LINE-1 methylation levels did not show any associations with maternal, placental and neonatal parameters. CONCLUSIONS: Placental DNMT1 expression was found to be associated positively with placental weight and birth weight, specifically in the female AGA births. Thus, we hypothesize that placental DNMT1 participates in fetoplacental growth in a fetal gender-specific manner.

Placental expression of the insulin receptor binding protein GRB10: Relation to human fetoplacental growth and fetal gender.

INTRODUCTION: Imprinted genes play an important role in mammalian fetoplacental growth and development. We have evaluated whether the placental expression of two imprinted genes, growth factor receptor-binding protein 10 (GRB10) and pleckstrin homology-like domain, family A, member 2 (PHLDA2) correlate with human fetoplacental growth parameters. METHODS: Placentae (n = 77) were collected from small- (SGA) and appropriate- (AGA) for gestational age full-term singleton pregnancies (n = 36 SGA and 41 AGA). Placentae and neonates were weighed at birth. Realtime quantitative PCR was performed to assess placental transcript abundance of GRB10 and PHLDA2 normalized to a panel of reference genes. RESULTS: Placental GRB10 transcript abundance associated positively with placental weight (r = 0.307, P = 0.007), birth weight (r = 0.267, P = 0.019) and neonatal head circumference (r = 0.280, P = 0.014). Placental GRB10 transcript levels were significantly lower in male SGA placentae compared to the male AGA placentae. Placental PHLDA2 transcript abundance did not show any associations with maternal, placental or neonatal parameters. DISCUSSION: Placental GRB10 expression was found to be associated positively with placental weight, birth weight, and neonatal head circumference, especially in males. Hence, we speculate that placental GRB10 plays a role in regulating fetoplacental growth and thereby in the pathophysiology of fetal growth restriction in the context of fetal gender.