microRNAs in congenital diaphragmatic hernia: insights into prenatal and perinatal biomarkers and altered molecular pathways

Congenital diaphragmatic hernia (CDH) is characterized by a diaphragmatic defect, leading to herniation of abdominal organs into the chest, lung compression, and impaired lung development, often resulting in pulmonary hypertension and lung hypoplasia. Prenatal imaging techniques like ultrasound and MRI provide anatomical predictors of outcomes, but their limitations necessitate novel biomarkers for better prognostic accuracy. This study aims to identify unique circulating maternal, fetal, and neonatal microRNAs (miRNAs) that can distinguish CDH pregnancies from healthy controls and assess their potential as markers of disease severity. We conducted a prospective study involving third-trimester maternal blood, amniotic fluid, cord blood, and neonatal blood samples from pregnancies complicated by CDH and healthy controls. miRNA expression was analyzed using RNA-sequencing, and random forest analysis identified miRNAs distinguishing CDH survivors from nonsurvivors. Pathway enrichment analyses were performed to explore the biological relevance of differentially expressed miRNAs. Significant miRNA expression differences were observed between CDH and control samples across all sample types. In infant blood, 148 miRNAs were up-regulated, and 36 were down-regulated in CDH cases. Pathway analysis revealed that dysregulated miRNAs in CDH targeted pathways related to protein binding, transcription regulation, and signaling pathways implicated in pulmonary hypertension and lung hypoplasia. Random forest analysis identified miRNAs in maternal blood (miR-7850-5p_L-1R+2, miR-942-3p, and miR-197-3p) that distinguished CDH survivors from nonsurvivors, with an receiver operating characteristic area under the curve of 1.0. Circulating miRNAs in maternal blood offer promising biomarkers for predicting CDH outcomes. miRNAs from infant blood provide mechanistic insights and potential targets for therapeutic intervention in critical pathways of pulmonary hypertension and lung hypoplasia. Further studies with larger cohorts are needed to validate these findings and explore the clinical application of miRNA biomarkers in CDH management.