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.

Transcript Analysis Reveals a Hypoxic Inflammatory Environment in Human Chronic Otitis Media With Effusion

“…We also found significantly elevated VEGF protein in COME fluids when compared to plasma. Other studies have reported the presence of VEGF protein in the effusion and the middle ear mucosa of patients with COME (Jung et al, 1999;Val et al, 2018). The present study finding of hypoxia on transcriptional profiling was the result of an unbiased approach to whole transcript analysis and provides further evidence of wbc hypoxia in human COME.…”

“…The high prevalence of neutrophils in mucoid, serous and intermediate COME effusions in this study is consistent with the proteomic findings of neutrophils and NETs described by . A subsequent proteomic analysis by these authors focusing on the differences between mucoid and serous COME samples indicated that higher neutrophil signature NET's in mucoid COME associated with greater MUC5B, and that serous COME samples have higher early innate immunity markers, complement and immunoglobulins (Val et al, 2018).…”

“…Cytokine analysis reveals a wide spectrum of pro-inflammatory cytokines, among which is IL-8 the neutrophil leukocyte chemotaxic protein (Matkovic et al, 2007;. Hypoxia signaling pathway members such as vascular endothelial growth factor (VEGF) protein and mRNA are also present in the effusion and middle ear mucosa (Jung et al, 1999;Sekiyama et al, 2011;Val et al, 2018).…”

“…The effusion in younger patients with COME is predominantly mucoid rather than serous (Duah et al, 2016). There are microbiome difference between mucoid and serous effusions (Krueger et al, 2017), and proteomic analysis reveals a higher content of MUC5B in mucoid effusions, as well as DNA (Val et al, 2018). Mucoid effusions also have a global tendency to increased pro-inflammatory mediators, but serous effusions have greater acute phase proteins IL-1b and IL-10, suggestive of a differing immunological response (Val et al, 2018).…”

Reviewing the Pathogenic Potential of the Otitis-Associated Bacteria Alloiococcus otitidis and Turicella otitidis

“…In the microbiota of MEF, Alloiococcus appears to be one of the dominant genera (Jervis- Bardy et al, 2015;Chan et al, 2016Chan et al, , 2017bBoers et al, 2018;Lappan et al, 2018;Val et al, 2018;Johnston et al, 2019). Turicella is less often reported, but has been identified as a member of the MEF microbiota in 8 of the 12 MEF microbiota studies reported in Table 3 (Jervis- Bardy et al, 2015;Krueger et al, 2017;Minami et al, 2017;Sillanpää et al, 2017;Boers et al, 2018;Lappan et al, 2018;Val et al, 2018;Johnston et al, 2019). However, due to the compositional nature of microbiome data it remains difficult to interpret which organisms are more abundant than others.…”