Differential response of gel-forming mucins to pathogenic middle ear bacteria.

OBJECTIVE

To assess the differential response of the secretory gel forming mucins (GFM) to the most common bacterial pathogens causing otitis media, Streptococcus pneumoniae (SP), nontypeable Haemophilus influenza (NTHi), and Moraxella catarrhalis (Mcat), in a culture model of human middle ear epithelium (HMEEC).

METHODS

In vitro cultured HMEEC was exposed to 5 μg/ml of bacterial whole cell lysate (WCL). RNA was extracted to generate cDNA. The expression levels of each of the targeted mucin transcripts, MUC2, MUC5AC, MUC5B and MUC19, were detected by quantitative PCR.

RESULTS

The submerged HMEEC exposed to NTHi-86028NP WCL demonstrated a significant increase of MUC2, MUC5AC and MUC5B as compared to the control non-treated cells while MUC19 transcript level remained unchanged. WCL of additional major OM pathogens significantly increase the transcription of these three mucin genes as well. A combination of NTHi and SP further synergistically induced MUC2 and MUC5AC gene expression however, not all NTHi strains synergized with SP in the induction. Addition of Mcat WCL to the synergized combination of NTHi and SP did not participate in the synergistic response of mucins.

CONCLUSION

The specific pathogen combinations were important in determining the degree of synergistic effects to GFM expression. The current data are substantive in guiding future work to extend our understanding of OM pathogens and GFMs.