miR-197 Targets NLRP3 3' UTR and Correlates with NLRP3/Caspase-1/IL-18 Signaling in Hyperoxia-Stimulated Neonatal BPD...

Reduced circulating miR-197 was previously observed in preterm infants who later developed bronchopulmonary dysplasia (BPD), but its relationship with NLRP3 inflammasome signaling remains unclear. This study examined miR-197 expression, NLRP3 inflammasome-related markers, and the interaction between miR-197 and the NLRP3 3' UTR in a neonatal hyperoxia model. Neonatal C57BL/6J mice were exposed to 60% oxygen or room air from birth, and lung tissues were collected on postnatal days 1, 7, 14, and 21. Lung injury and alveolar development were assessed by histology, radial alveolar count, mean linear intercept, and lung wet-to-dry ratio. miR-197 and NLRP3 expression and NF-κB-, caspase-1-, and IL-18-related proteins were evaluated by RT-qPCR and Western blotting. A dual-luciferase reporter assay in MLE12 cells tested the interaction between miR-197 and the NLRP3 3' UTR. Hyperoxia increased lung wet-to-dry ratios and mean linear intercept, reduced radial alveolar count, and caused progressive alveolar simplification. miR-197 expression decreased, whereas NLRP3 mRNA increased, at all examined time points; NLRP3 protein and inflammasome-related protein changes were most evident from postnatal day 7 onward. The miR-197 mimic reduced luciferase activity in the wild-type but not mutant NLRP3 3' UTR reporter. These findings show that neonatal hyperoxia is associated with reduced miR-197 and increased NLRP3/inflammasome-related signaling and support a sequence-specific interaction between miR-197 and the NLRP3 3' UTR, although causal regulation in vivo requires further investigation.