Early Macrophage Activation in Preterm Newborns and Respiratory Disease

Abstract

Monocyte-macrophages have a role in host defense and tissue remodeling. Classically activated (M1) and alternatively activated (M2) macrophages from preterm newborns are analyzed, and the role in acute respiratory distress syndrome(RDS) and bronchopulmonary dysplasia (BPD) is evaluated. Observational study was conducted on the blood samples (BSS) and tracheal aspirates (TAs) collected at 48 to 72 hours of life in preterm newborns. Flow-cytometry was performed to identify monocytes and M1 or M2. Prenatal factors, gestational age, birth weight, acute RDS and BPD were assessed and related to the M1 and M2levels andM2/M1. Onehundred nine subjectswere included, and100were followed up. M1 and M2 increase and decrease, respectively, according to the gestational age and birth weight. HigherM2 and lower M1 levels inTAs were found after maternal chorioamnionitis. BPD patients have low M1 with high M2 in blood samples (BSS), as well as in tracheal aspirates (TAs). No relationwas found between activation pattern and prenatal variables or the RDS grade. The correlation between gestational age or birth weight and M1 could reflect amore maturemacrophage system, capable to push undifferentiatedmacrophages toward the classical pathway. We speculate that adequate early classical macrophage activation could be crucial to protect lungs from post-natal injuries, preventing the development of BPD.