Pirfenidone Alleviates Intrauterine Infection‐Induced Lung Injuries in Neonates by Targeting Transforming Growth Factor Beta 1/Sma‐ and Mad‐Related Protein Signaling Pathway

Objective: To explore the effect and mechanism of pirfenidone (PFD) on lung injuries in newborn rats caused by intrauterine inflammation. Methods: In vivo, we established the intrauterine inflammation model with lipopolysaccharide (LPS) injection in pregnant rats. The administration of PFD in pregnant rats was performed to evaluate its beneficial effect against intrauterine inflammation‐induced lung injuries in neonatal rats. Lung tissues of newborns from three groups of pregnant rats (Saline + DMSO, LPS + DMSO, and LPS + PFD) were collected. Immunohistochemistry (IHC) and Western blot were used to detect the fibrotic‐related protein expressions. In vitro, LPS‐induced mouse lung epithelial cells (MLE 12) were employed to explore the underlying mechanism of PFD against intrauterine inflammation‐induced lung injury in neonates. Results: In vivo, the radial alveolar count (RAC) was decreased, the mean linear intercept (MLI) was increased, and the lung injury score was high in intrauterine inflammation (LPS + DMSO‐treated pregnant rats) induced lung injuries in newborns. The protein level of matrix metallopeptidase 9 (MMP‐9), TGF‐β1 (transforming growth factor beta 1), phospho‐Smad2 (Sma‐ and mad‐related protein 2), and phosphor‐Smad3 (Sma‐ and mad‐related protein 3) levels were upregulated in neonatal lungs with intrauterine infection. Lung injuries were alleviated in LPS + PFD groups, and the protein levels of TGF‐β1, p‐Smad2, p‐Smad3, and MMP‐9 were reduced. In vitro, PFD attenuated the LPS‐induced inflammatory response and reduced the expressions of MMP‐9, TIMP‐1, and Collagen IV in lung epithelial cells through the TGF‐β1/Smad2/3 signaling pathway. Conclusions: PFD alleviates intrauterine infection‐induced lung injuries in neonates by targeting transforming growth factor beta 1/Sma‐ and mad‐related protein signaling pathway. The inhibition of TGF‐β1 signaling by PFD prevents the neonatal lung injuries by reducing MMP‐9 and Collagen IV protein levels. This study provides theoretical basis and insights for PFD‐mediated intervention of lung injury in neonates with intrauterine infection.