[Evaluation of the effect of erythromycin on otitis media with effusion in experimental rat models]

The clinical efficacy of erythromycin (EM) therapy has been demonstrated in otitis media with effusion (OME). However, the mechanism of action of this drug is not clear. In this study, to elucidate the possible mechanism of action of EM, we examined the effect of the drug on the expression of neutrophil adhesion molecules such as L-selectin and Mac-1. Furthermore, we examined production of leukotrienes B4, C4 (LTB4, C4) and prostaglandin E2 (PGE2) in rat OME induced by injection of a lipopolysaccharide. EM down-regulated L-selectin expression, and inhibited up regulation of Mac-1 expression on peripheral blood neutrophils. Also it inhibited the accumulation of inflammatory cells such as neutrophils and macrophages in middle ear effusion (MEE). Furthermore, EM suppressed the exudation of plasma protein and the production of LTB4, C4 and PGE2, in OME. These results suggest that EM may exert the antiinflammatory effect on MEE through suppression of leukocyte accumulation the middle ear by affecting the expression of adhesion molecules on leukocytes and inhibiting the production of arachidonic acid metabolitis.