Experimental otitis media with effusion induced by leukotriene D4

Objective: inflammatory mediators such as prostaglandins (PGs), leukotrienes (LTs), and platelet-activating factor (PAF) have been identified in human middle ear effusions (MEEs), as well as in the experimentally induced MEEs of animals. However, the exact function of LTs in the middle ear cavity is still unknown. In this study, the role of LTs was investigated using an experimental model in which OME was induced by LTD4. Methods: to examine whether leukotrienes (LTs) induce otitis media with effusion (OME), 2×10−6, 2×10−5, 1×10−4 and 2×10−4 M of LTD4 was injected into the rat ear. The severity of OME was assessed based on the histological findings. The concentrations of IL1-β, TNF-α, and GRO/CINC-1 in MEE were also measured. Additionally the therapeutic efficacy of a specific LTs antagonist, pranlukast on experimental OME was investigated. Results: all ears developed middle ear effusion (MEE) within 24 h and about 50% of the animals continued to demonstrate MEE for 14 days in the 1×10−4 and 2×10−4 M groups. The cytokine levels seemed to correspond well with the persistence of OME. The oral administration of a specific LTs antagonist, pranlukast, was found to alleviate the experimental OME. Conclusion: these findings suggest that LTs appear to plays an important role in the pathogenesis of OME.