Placental mtDNA copy number and methylation in association with macrosomia in healthy pregnancy.

INTRODUCTION: Fetal growth and development depend on metabolic energy from placental mitochondria. However, the impact of placental mitochondria on the occurrence of macrosomia remains unclear. We aimed to explore the association between macrosomia without gestational diabetes mellitus (non-GDM) and changes in placental mitochondrial DNA (mtDNA) copy number and methylation. METHODS: Fifty-four newborns with macrosomia and 54 normal birthweight controls were enrolled in this study. Placental mtDNA copy number and mRNA expression of nuclear genes related to mitochondrial replication or ATP synthesis-related genes were measured by real-time quantitative polymerase chain reaction (qPCR). Methylation levels of the non-coding regulatory region D-loop and ATP synthesis-related genes were detected by targeted bisulfite sequencing. RESULTS: Newborns with macrosomia had lower placental mtDNA copy number and higher methylation rates of the CpG15 site in the D-loop region (D-CpG15) and CpG6 site in the cytochrome C oxidase III (COX3) gene (COX3-CpG6) than normal birth weight newborns. After adjusting for potential covariates (gestational age, prepregnancy BMI, and infant sex), decreased placental mtDNA copy number (adjusted odds ratio [aOR] = 2.09, 95% confidence interval [CI] 1.03-4.25), elevated methylation rate of D-CpG15 (aOR = 2.06, 95% CI 1.03-4.09) and COX3-CpG6 (aOR = 2.13, 95% CI 1.08-4.20) remained significantly associated with a higher risk of macrosomia. DISCUSSION: Reduced mtDNA copy number and increased methylation levels of specific loci at mtDNA would increase the risk of macrosomia. However, the detailed molecular mechanism needs further identification.

Placental and cord blood brain derived neurotrophic factor levels are decreased in nondiabetic macrosomia.

PURPOSE: To measure levels of placental brain derived neurotrophic factor (BDNF) gene expression and umbilical cord blood BDNF in neonates with nondiabetic macrosomia and determine associations between these levels and macrosomia. METHODS: This case-control study included 58 nondiabetic macrosomic and 59 normal birth weight mother-infant pairs. Data were collected from interviews and our hospital's database. BDNF gene expression was quantified in placental tissues using quantitative real-time polymerase chain reaction (n = 117). Umbilical cord blood BDNF levels were measured by enzyme-linked immunosorbent assay (n = 90). Multivariate logistic regression models were used to evaluate associations between BDNF levels and macrosomia. RESULTS: Placental BDNF gene expression (P = 0.026) and cord blood BDNF (P = 0.008) were lower in neonates with nondiabetic macrosomia than in normal birth weight controls. Cord blood BDNF was significantly lower in vaginally delivered macrosomic neonates than vaginally delivered controls (P = 0.014), but cord BDNF did not differ between vaginal and cesarean section delivery modes in macrosomic neonates. Cord blood BDNF was positively associated with gestational age in control neonates (r = 0.496, P < 0.001), but not in macrosomic neonates. Cord blood BDNF was positively associated with placental BDNF relative expression (r s = 0.245, P = 0.02) in the total group. Higher cord blood BDNF levels were independently associated with protection against nondiabetic macrosomia (adjusted odds ratio 0.992; 95% confidence interval 0.986-0.998). CONCLUSIONS: Both placental BDNF gene expression and cord blood BDNF were downregulated in neonates with nondiabetic macrosomia compared with normal birth weight neonates. Cord BDNF may partly derive from BDNF secreted by the placenta. Higher cord plasma BDNF levels protected against nondiabetic macrosomia.

Decreased miR-143 and increased miR-21 placental expression levels are associated with macrosomia.

Macrosomia, a birth weight ≥ 4,000 g, is associated with maternal and infant health problems. The dysregulation of microRNAs (miRNAs) in the placenta is associated with adverse birth outcomes, yet whether aberrantly expressed placental miRNAs are associated with macrosomia remains unknown. The aim of the current study was to characterize the expression of three placental miRNAs (miR­6, ­21 and ­143) and evaluate their association with macrosomia. The miRNA expression in placental tissues from 67 macrosomic pregnancies and 64 normal pregnancies were analyzed using reverse transcription­quantitative polymerase chain reaction. The expression of miR­21 was observed to be elevated in macrosomic placenta compared with control samples, while miR­143 expression was significantly lower than in control placenta (P<0.05). No significant differences were identified in the miR­16 expression levels between the groups (P=0.955). Following division of miRNA expression levels by quartile, logistic regression models demonstrated that the odds of macrosomia increased with miR­21 expression quartile: Q2, odds ratio (OR)=6.67 [95% confidence interval (CI), 1.39­32.05]; Q3, OR=4.10 (95% CI, 0.88­19.11); Q4, OR=16.19 (95% CI, 2.46­106.68). Conversely, higher levels of miR­143 expression were protective against macrosomia: Q2, OR=0.22 (95% CI, 0.049­0.98); Q3, OR=0.11 (95% CI, 0.024­0.55), and Q4, OR=0.16 (95% CI, 0.032­0.79). Thus, statistical analysis demonstrated that high levels of miR­21 expression and low levels of miR­143 expression predict the risk for macrosomia, indicating an interaction between the two miRNAs. Bioinformatic analysis suggested that they are likely to function in the mitogen­activated protein kinases signaling pathway to influence the risk of macrosomia. The results of the present study provide evidence that placental miR-21 and -143 are important in the formation of macrosomia.

Birth weight is associated with placental fat mass- and obesity-associated gene expression and promoter methylation in a Chinese population.

OBJECTIVE: To explore the relationship between birth weight and fat mass- and obesity-associated (FTO) gene expression and promoter methylation status in the Chinese population. METHODS: Seventy-five neonates and their mothers were recruited from Yuying Children's Hospital of Wenzhou Medical University. Subjects were divided into three groups by birth weight: low (< 3,500 g, n = 20), medium (3,500-3,999 g, n = 30) and high (≥ 4,000 g, n = 25). Placental FTO transcript levels and promoter methylation were determined by quantitative PCR and Sequenom MassARRAY®. RESULTS: Placental FTO mRNA expression was significantly increased in the high- and medium-weight groups compared to the low-weight group (p = 0.023). Methylation rates of CpG11 sites were significantly decreased in high-birth weight newborns (p = 0.018). Multiple linear regressions showed placental FTO mRNA, maternal pre-pregnancy body mass index (BMI) and CpG11 methylation rate were independently associated with increased fetal birth weight. Additionally, FTO mRNA expression was negatively associated with CpG6.7.8.9 methylation in mothers that underwent C-section. CONCLUSIONS: High placental FTO expression is associated with increased birth weight in Chinese neonates, and FTO promoter methylation level at a specific CpG site is negatively associated with birth weight. Further work is needed to determine the functionality of this CpG site in placentas.