NLRP3 Inflammasome in Otitis Media With Effusion: Insights From Mouse Models and Human Samples.

Abstract

PURPOSE: Otitis media with effusion (OME) is a prevalent pediatric condition, yet its molecular mechanisms remain incompletely understood. The NLRP3 inflammasome is known to regulate inflammation in various diseases, but its role in OME remains unclear. This study aimed to investigate NLRP3 activation in OME using both a murine model and clinical samples. METHODS: Experimental OME was induced in mice via intratympanic injection of lipopolysaccharide (LPS). On day 3 postinduction, middle ear tissues and lavage fluid were collected. Nlrp3 mRNA expression was assessed by qPCR, while cleaved caspase-1 and mature IL-1β protein levels were evaluated by western blotting. IL-1β levels in lavage fluid and serum were measured via ELISA. Human middle ear effusions (MEE) and matched serum samples were collected from pediatric OME patients, and concentrations of IL-1β and IL-18 were measured and normalized to total protein. To assess the functional role of NLRP3, OME was induced in Nlrp3 knockout ( Nlrp3-/- ) and wild-type (WT) mice, followed by otoscopic and histologic evaluation. RESULTS: LPS-induced OME mice exhibited increased expression of NLRP3, cleaved caspase-1, and IL-1β. ELISA confirmed elevated IL-1β in middle ear lavage fluid. In human samples, IL-1β and IL-18 were significantly higher in MEE than in serum. Nlrp3-/- mice showed reduced IL-1β production but no significant differences in histopathology or effusion resolution compared with WT. CONCLUSION: NLRP3 inflammasome contributes to local inflammation in OME but does not significantly alter disease progression, suggesting involvement of additional inflammatory pathways.