TGFB1 and bronchopulmonary dysplasia: Consequently, the recruited monocytes and macrophages are the most important source of TGF-β [61] together with a simultaneous increase in secreted cytokines such as interleukin (IL-)1β, IL-6, IL-8, tumor necrosis factor (TNF)-α, monocyte chemo-attractant proteins (MCP) 1 to 3, and the macrophage inflammatory proteins (MIP) 1a and 1b in preterm infants with evolving BPD [57, 62, 63].