Middle Ear Epithelium has Inflammatory Capacity

Abstract

Endotoxin, tumour necrosis factor- &#102 (TNF- &#102 ), interleukin-1 &#103 (IL-1 &#103 ) and intercellular adhesion molecule-1 (ICAM-1) were detected in 88%, 51%, 58% and 66% of 152 middle ears from patients suffering from otitis media with effusion. In this study the hypothesis that bacterial endotoxin, TNF- &#102 , IL-1 &#103 and ICAM-1 induce the inflammatory process characteristic of otitis media with effusion was tested. Cultures of rabbit middle ear epithelium were exposed to endotoxin, TNF- &#102 or IL-1 &#103 . The expression of ICAM-1 on the cell surfaces was measured with a direct enzyme-linked immunosorbent assay on the cell layer. For TNF- &#102 , 5 ng/ml significantly increased ICAM-1 expression, whereas 100 ng/ml had a toxic effect. For IL-1 &#103 , as little as 1 ng/ml produced a significant increase in ICAM-1 expression. Endotoxin stimulated ICAM-1 expression less strongly in concentrations from 100 ng/ml to 100 &#119 g/ml. The findings indicate that stimulation of ICAM-1 by endotoxin is mediated, at least in part, by TNF- &#102 and IL-1 &#103 . It is concluded that endotoxin induces sustained inflammation in OME, and that this inflammation is mediated, at least in part, by the primary cytokines TNF- &#102 and IL-1 &#103 .