MiR-29b Is Associated with Perinatal Inflammation in Extremely Preterm Infants

BACKGROUND: Inflammation is strongly associated with premature birth and neonatal morbidities. Increases in infant haptoglobin (Hp&HpRP) and IL-6 levels are indicators of intra-amniotic inflammation (IAI) and have been linked to poor neonatal outcomes. Inflammation causes epigenetic changes, specifically suppression of miR-29 expression. The current study sought to determine whether miR-29b levels in cord blood or neonatal venous blood are associated with IAI, identified by elevated IL-6 and haptoglobin, and subsequent clinical morbidities in the infant. METHODS: We tested 92 cord blood samples from premature newborns and 18 venous blood samples at 36 weeks corrected gestational age. MiR-29b, haptoglobin (Hp&HpRP), and IL-6 were measured by PCR and ELISA respectively. RESULTS: Decreased levels of miR-29b were observed in infants exposed to IAI with elevated Hp&HpRP and IL-6 levels and in infants delivered by spontaneous preterm birth. Lower miR-29 levels were also observed in women diagnosed with histological chorioamnionitis or funisitis and in infants with cerebral palsy. Higher levels of miR-29 were measured in infants small for gestational age (SGA) and in venous samples from older infants. CONCLUSION: MiR-29 may be an additional biomarker of IAI and a potential therapeutic target for treating poor newborn outcomes resulting from antenatal exposure to IAI.