Decreased Expression of TLR-9 and Cytokines in the Presence of Bacteria in Patients with Otitis Media with Effusion

OBJECTIVES Toll-like receptor (TLR)-9 recognizes unmethylated cytidine-phosphate-guanosine (CpG) motifs in bacteria. Therefore, the expression of TLR-9 may differ according to the results of bacterial culture, and thus a change in proinflammatory cytokine induction can also be expected. The authors aimed to assess the differences and relationships between the expression of TLR-9, cytokines, and nitric oxide synthase (NOS) in otitis media with effusion (OME) based on bacterial culture results. METHODS Sixty-eight patients with OME were divided into culture-positive and culture-negative groups based on middle ear culture results. mRNA expression of TLR-9, NOS, and cytokines was measured and analyzed. RESULTS Bacteria were detected in 38.2% of patients, and the distribution was as follows: coagulase negative Staphylococcus (10.3%), Staphylococcus aureus (8.8%), Streptococcus pneumonia (5.9%), and Bacillus spp. and Haemophilus influenza combined (2.9%). There were no significant differences in epidemiologic characteristics according to the culture results. Down-regulation of TLR-9 was observed in the culture-positive group (P=0.019). Cytokines including interleukin (IL)-12 (r=-0.582), tumor necrosis factor (TNF)-α (r=-0.569), interferon (IFN)-γ (r=-0.442), IL-6 (r=-0.395) and inducible NOS (r=-0.256) tended to decrease with the detection of bacteria. CONCLUSION The expression of TLR-9 significantly decreased in OME with confirmed bacterial pathogens. IL-12, TNF-α, IFN-β, IL-6 expression tended to decrease with the detection of bacteria. The presence of bacterial pathogens in OME may be related to abnormalities in the innate immune system.