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

Abstract

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.