Synergistic effect of dermatophagoides farinae and lipopolysaccharides in human middle ear epithelial cell

Abstract

Introduction: Although, the concept of one airway one disease including the middle ear space as a part of the united airways is well-recognized, the role of allergen in otitis media with effusion is not clearly understood. We aimed to investigate Dermatophagoides farinae (Der f) and LPS interaction on the induction of epithelial inflammatory response in vitro. Material & Methods: Primary human middle ear epithelial cells were exposed to Der f, LPS or both in different sequences, and the magnitude of each immunologic response was compared. mRNA expression of mucin (MUC) 4, 5AC, 5B, 8, GM-CSF, TNF-α, TLR 4 and MD-2 were evaluated by using real-time PCR. MUC proteins level before and after knocking out the TLR4 and MD-2 via siRNA transfection was assessed. Accordingly, the involved cell signaling pathway was evaluated. Results: The expression of cytokines and MUC 4, 5AC, 5B and 8 genes was augmented by pretreatment of Der f followed by LPS, however, reverse treatment or adding together did not induce the same amount of response. Increased MUC expression was decreased by knockdown of TLR4, but not by the MD-2. The signal intensity of MUC 8 protein was higher in MD-2 over-expressed cells than in cells exposed to LPS only. The nuclear factor-κB translocation was demonstrated in the pretreatment of Der f followed by LPS. Conclusions: When Der f precedes LPS exposure, it can act synergistically in the induction of pro-inflammatory cytokines and mucin gene, suggesting an important role for the development of OME in patients with concealed allergy airway sensitization.