Characterization of mucoid and serous middle ear effusions from patients with chronic otitis media: implication of different biological mechanisms?

Abstract

BackgroundChronic Otitis Media with effusion (COME) is characterized by persistent middle ear effusions that are in most cases highly viscous, but some patients present with serous fluid. This study aimed at comprehensively characterizing the macromolecular composition of mucoid vs. serous MEEs.MethodsMEEs from patients with COME were analyzed for proteins by Mass Spectrometry (MS) and western blot techniques, total DNA quantity, bacterial DNA (16S sequencing) and cytokine content. Proteomics datasets were studied in Ingenuity pathway analysis (IPA).ResultsMucoid samples showed a global tendency of increased pro- inflammatory mediators. IL1-β and IL-10 were significantly more abundant in serous samples (p<0.01). Mucoid samples had higher DNA quantity (p=0.04), more likely to be positive in MUC5B protein (p=0.008) and higher peptide counts (12786 vs 2225), as well as an overall larger number of identified proteins (331 vs 177), compared to serous. IPA found the mucoid sample dataset to be related to immune cell function and epithelial remodeling whereas the serous sample dataset showed acute responses and blood related proteins. Interestingly, serous samples showed more bacterial DNA than mucoid ones, with less bacterial genera variability.ConclusionThis study demonstrates divergent immune responses in children with COME by effusion quality.