TNF and infection: Together with other BPD risk factors like mechanical ventilation and hyperoxia, infection triggers the release of a series of pro-inflammatory substances including IL-6, IL-1β, IL-8, tumor necrosis factor alpha (TNF-α), NLR family pyrin domain containing 3 (NLRP3), and collagen I. These inflammatory mediators restrict the activity of vascular endothelial growth factor and surfactant proteins in the immature lungs of premature infants.