CXCL5 and bronchopulmonary dysplasia: Based on the differential transcriptional profiles on day 1 and day 7, we speculate that during BPD pathogenesis, early expression of pro-inflammatory chemokine genes such as CXCL5/6 and CCL3 expands over time to include additional mediators including IL1A and IL1B. These data suggest the first week of life may mark a therapeutic window of opportunity to suppress ongoing or amplified macrophage activation and inflammation.