TNF and bronchopulmonary dysplasia: Meanwhile, the inflammatory factors IL-1β, IL-6, and TNF-α were elevated at the gene level in the BPD group, as reported in a previous publication (Fig. 1h)22, and the expression of IL-33 was significantly increased in the lung tissues from the BPD group at P14 (Fig. 1h, i) and P28 (Fig. 1j).