Improvement of alveolarization arrest in newborn rats with bronchopulmonary dysplasia via inhibiting alveolar epithelial cell pyroptosis

Abstract

Objective·To study the effect of gasdermin D (GSDMD) inhibitor necrosulfonamide (NSA) on alveolarization arrest in lipopolysaccharide (LPS)-induced bronchopulmonary dysplasia (BPD) newborn rats via inhibiting alveolar epithelial cell pyroptosis.Methods·Pregnant SD rats were randomly assigned to four groups as follows: control, BPD, BPD with NSA and NSA group, and then were prepared to receive intra-amniotic injection of LPS. Lung tissues of newborn rats on the first, third and seventh day after birth were stained by hematoxylin-eosin (H-E) to observe lung development. The expressions of GSDMD-N-terminal in lungs of newborn rats in each group were detected by immunofluorescence. The mRNA levels of interleukin-1β (IL-1β) of newborn rats' lungs was detected by real-time PCR. In vitro, the mouse alveolar epithelial cell line MLE-12 was cultured and treated with LPS/adenosine triphosphate (ATP) and NSA. The cell viability of MLE-12 cells was detected by CCK-8 method, the pyroptosis was detected by Hoechst 33342 and propidium iodide (PI) staining, and the expressions of surfactant protein C (SFTPC) and GSDMD-N protein in MLE-12 cells were detected by immunofluorescence.Results·In vivo, intra-amniotic injection of LPS hindered lung development, resulting in the pathological hallmarks of BPD. The GSDMD-N expression of alveolar epithelial cells increased in the BPD rat model established by intra-amniotic injection of LPS, while NSA treatment significantly improved the lung development of BPD rats and inhibited the IL-1β mRNA expression (both P<0.05). In vitro, the study confirmed that LPS/ATP treatment decreased the viability of alveolar epithelial cells MLE-12 and induced pyroptosis, while NSA treatment increased alveolar epithelial cell viability and inhibited pyroptosis (both P<0.05). In addition, NSA treatment upregulated the SFTPC expression and inhibited the GSDMD-N expression in LPS/ATP-stimulated alveolar epithelial cells (both P<0.05).Conclusion·Inhibiting the alveolar epithelial cell pyroptosis can improve the alveolar development in BPD newborn rats.

Keywords

• bronchopulmonary dysplasia
• pyroptosis
• gasdermin d (gsdmd)
• alveolar epithelial cell