MicroRNA-320а as a novel biomarker at preclinical stage of necrotizing enterocolitis in term neonates with congenital heart defects.

Background: Necrotizing enterocolitis (NEC) remains a prominent gastrointestinal emergency among infants, particularly term infants with congenital heart defects (CHD) being at high risk. The molecular processes that contribute to NEC have yet to be completely understood. The high mortality rates necessitate an active search for noninvasive biomarkers that can aid in the preclinical diagnosis and prognosis of NEC. MicroRNAs (miRs), which are involved in many biological processes in both health and disease, have been discovered to play an important role in regulating inflammation and immune responses via various signaling pathways.

Aim: To determine the plasma levels of miR-155, miR-221, miR-223, miR-320a, miR-451a as potential NEC biomarkers in term newborns with CHD.

Methods: This prospective cohort study included twenty-tree term newborns with CHD who underwent cardiac surgery on the median day of life (DOL) = 7. Nine of them developed NEC (Bell's stage IIA and IIIA) within 1 week of cardiac surgery (NEC newborns). Blood samples were collected before (median DOL = 5) and following (median DOL = 13) cardiac surgery. Levels of plasma miR-155-5p, miR-221-3p, miR-223-3p, miR-320a-3p, and miR-451a were determined using real-time polymerase chain reaction. The functional analysis was executed using the DIANA-miRPath v4.0.

Results: Preoperatively, NEC newborns had significantly lower plasma levels of miR-155 (2.70-fold, P = 0.020), miR-223 (2.42-fold, P = 0.030), and miR-320a (3.62-fold, P = 0.006) than newborns without NEC. Postoperatively, miR-451a levels differed significantly between the newborn groups, showing a 4.70-fold decrease (P = 0.014) in expression when clinical NEC symptoms appeared. According to receiver operating characteristic analysis, miR-320a was found to be the most effective predictive biomarker for NEC [area under the curve (AUC) = 0.835, 63% sensitivity, 100% specificity], while miR-451a was identified as a NEC biomarker (AUC = 0.835, 85.7% sensitivity, 76.9% specificity). Preoperatively, miR-155-5p, miR-223-3p, and miR-320a-3p were differentially expressed and targeted the forkhead box O and Hippo pathways (P < 0.01).

Conclusion: Our study demonstrates, for the first time, that plasma miR-320a-3p levels can be used as a preclinical biomarker for NEC in term newborns with CHD.