CCL3 and bronchopulmonary dysplasia: Compared to patients without BPD or with only mild BPD, preterm infants that eventually developed severe BPD (still requiring positive pressure support or >0.30 FiO2 at 36 weeks corrected gestational age) expressed higher levels of inflammatory genes on day 7, including IFITM2, IRAK3, CCL3, IL1A, and IL1B (Fig. 1g, h).