Extracellular vesicle microRNA in early versus late pregnancy with birth outcomes in the MADRES study

Abstract

Circulating miRNA may contribute to the development of adverse birth outcomes. However, few studies have investigated extracellular vesicle (EV) miRNA, which play important roles in intercellular communication, or compared miRNA at multiple time points in pregnancy. In the current study, 800 miRNA were profiled for EVs from maternal plasma collected in early (median: 12.5 weeks) and late (median: 31.8 weeks) pregnancy from 156 participants in the MADRES Study, a health disparity pregnancy cohort. Associations between miRNA and birth weight, birth weight for gestational age (GA), and GA at birth were examined using covariate-adjusted robust linear regression. Differences by infant sex and maternal BMI were also investigated. Late pregnancy measures of 13 miRNA were associated with GA at birth (P_FDR<0.050). Negative associations were observed for eight miRNA (miR-4454+ miR-7975, miR-4516, let-7b-5p, miR-126-3p, miR-29b-3p, miR-15a-5p, miR-15b-5p, miR-19b-3p) and positive associations for five miRNA (miR-212-3p, miR-584-5p, miR-608, miR-210-3p, miR-188-5p). Predicted target genes were enriched (P_FDR<0.050) in pathways involved in organogenesis and placental development. An additional miRNA (miR-107), measured in late pregnancy, was positively associated with GA at birth in infants born to obese women (P_FDR for BMI interaction = 0.011). In primary analyses, the associations between early pregnancy miRNA and birth outcomes were not statistically significant (P_FDR≥0.05). However, sex-specific associations were observed for early pregnancy measures of 37 miRNA and GA at birth (P_FDR for interactions<0.050). None of the miRNA were associated with fetal growth measures (P_FDR≥0.050). Our findings suggest that EV miRNA in both early and late pregnancy may influence gestational duration.

Keywords: Mirna; birth outcomes; extracellular vesicles; pregnancy.

Figure 1.

Volcano plot for late pregnancy EV miRNA and GA at birth (N = 156). The x-axis shows the difference in GA at birth for a doubling in the miRNA count. The y-axis represents the -log₁₀(p-value). Each dot represents a miRNA that was detectable in at least 60% of MADRES participants in either early or late pregnancy. The dashed horizontal line shows the threshold for statistical significance based on a P_FDR<0.050. miRNA that were statistically significant after a more conservative Bonferroni correction (P_Bonferroni<0.050) are annotated. Results are from robust linear regression models, which were adjusted for the GA at sample collection, maternal age, maternal pre-pregnancy BMI, maternal ethnicity by birthplace, recruitment site, infant sex, and laboratory batch. miRNA counts were log₂-transformed. Effect estimates can therefore be interpreted as the difference in the specified outcome for a doubling in miRNA count. Abbreviations Used: EV, extracellular vesicle; FDR, false discovery rate; GA, gestational age; MADRES, Maternal and Developmental Risks from Environmental and Social Stressors study; miRNA, microRNA.

Figure 2.

Top 10 PANTHER pathways associated with predicted target genes identified for late pregnancy EV miRNA associated with GA at birth. PANTHER pathway enrichment analyses were conducted using enrichR [53]. Results are presented in a bubble plot. The dot color represents the -log₁₀(P_FDR) from Fisher’s Exact tests (dark purple represents smaller p-values and light pink represents larger p-values). The dot size indicates the percentage of pathway members that are represented by the predicted target genes identified for late pregnancy miRNA associated with GA at birth (larger dots represent larger percentages). The top 10 PANTHER pathways based on statistical significance are shown on the y-axis and are ordered from smallest to largest P_FDR. Odds ratios from Fisher’s Exact tests are shown on the x-axis. Abbreviations Used: EV, extracellular vesicle; FDR, false discovery rate; GA, gestational age; miRNA, microRNA.