TGFB1 and Respiratory distress: Clinically, the levels of TGF-β1 in tracheal aspirates of preterm infants are related to the extent of lung inflammation, fibrosis, abnormal lung development, and outcomes (25) and are higher among preterm infants with respiratory distress syndrome who did not receive surfactant therapy compared with infants receiving exogenous surfactant and without respiratory distress (26).