P0764 - Targeting Pyroptosis to Prevent Hyperoxia-induced Lung Injury in Neonatal Rats

Background:
Bronchopulmonary dysplasia (BPD) is one of the most common long-term complications of preterm infants. Exposure to hyperoxia is known to cause lung injury and subsequent development of BPD in these infants. Gasdermin D (GSDMD) is a key executer of pyroptotic cell death that is activated by inflammatory caspases. Our previous studies have demonstrated that the inflammasome-GSDMD cascade is activated in the neonatal rat model of hyperoxia-induced lung injury. The hypothesis of this study is that hyperoxia exposure induces pyroptosis mediated lung injury, and treatment with necrosulfonamide (NSA), an inhibitor of the GSDMD pore formation, attenuates hyperoxia induced lung injury.

Objective:
To investigate whether NSA attenuates hyperoxia-induced lung injury in neonatal rats.
Methodology:
Newborn rat pups were randomized within 24 h after birth to the following groups: room air (RA) + placebo (PL); RA + NSA; 85% O2 + PL, 85% O2 + NSA. Pups received daily intraperitoneal injections of NSA or placebo from postnatal day 1-14. Rat pups were sacrificed, and heart and lungs were collected for analyses. Lung tissues were analyzed for alveolar development by measuring mean linear intercept (MLI) and vascular density (VD), by immunofluorescence staining for vWF, an endothelial marker. Vascular remodeling was assessed by measuring muscularization of peripheral pulmonary vessels (MV) via alpha smooth muscle actin (SMA) staining. Pulmonary inflammation was assessed by macrophage staining. Right ventricular hypertrophy (RVH) was also assessed by measuring Fulton’s index on the rat hearts. Data are presented as Mean ± SD and significant differences between groups were determined by ANOVA.

Results:
Exposure to hyperoxia resulted in a significant decrease in alveolarization and pulmonary vascularization, as well as increase in vascular remodeling, inflammation and right ventricular hypertrophy. Treatment with NSA significantly improved alveolarization and vascular development, reduced vascular remodeling and right ventricular hypertrophy, and decreased alveolar macrophage infiltration (Table 1).
Conclusions and Significance:
Inhibition of GSDMD-mediated pyroptosis via NSA prevents hyperoxia-induced lung injury in neonatal rats suggesting NSA as a potential novel agent for preventing BPD in neonates.