Endotoxin and Lysosomal Protease Activity in Acute and Chronic Otitis Media with Effusion

Abstract

Endotoxin levels and lysosomal protease (collagenase, cathepsin B, and lysozyme) activity were measured in 104 middle ear effusions (MEEs) from patients with otitis media with effusion (OME). The MEE samples were classified into four groups: pediatric serous, mucoid, and acute, and adult serous. Endotoxin levels and lysosomal protease activity in MEEs were significantly different in the following order: adult less than serous less than mucoid less than acute groups, indicating that both endotoxin and lysosomal proteases are more closely related to the pathogenesis of pediatric chronic OME than to adult OME. In pediatric serous and mucoid effusions, endotoxin level had a significant correlation with activity of the lysosomal proteases. In conclusion, endotoxin enhances leukocyte infiltration into the middle ear, and lysosomal proteases released from leukocytes damage the middle ear mucosa and thereby prolong mucosal inflammation, which may be responsible for delayed recovery from acute OME.

The Role of Inflammatory Mediators in the Pathogenesis of Otitis Media and Sequelae

“…Endotoxin is reported to be present in a high percentage of middle ear effusions and even in nonpurulent MEEs (198-200). In an experiment examining the endotoxin levels in mucoid, serous, adult, and acute MEEs, endotoxin was found in 76.8% of the mucoid effusions, 55.6% of the serous effusions, 47.8% of effusions from adult patients, and 100% of acute effusions (201). …”

Nitrotyrosine in Otitis Media with Effusion

“…The scatterplots of NTc showed distribution into three age groups. According to this distribution, the OME patients were divided into three age groupsa group less than 16 years old (group A; n = 13), a group between 16 and 50 years old (group B; n = 14), and a group over 50 years old (group C; n =63) -and statistical analysis was performed.…”

O papel dos fatores genéticos na otite média

“…Yellon et al (1991) (50) demonstraram, nas secreções do ouvido médio de portadores de otite secretora crônica, a presença de significativas quantidades de citocinas, do tipo interleucina-1, interleucina-2, fator de necrose tumoral alfa e gama interferon, além de ausência do fator estimulante de granulócitos e macrófagos e interleucina-4. As propriedades ativadoras de ação citotóxica, osteoclástica e fibroblástica podem ser responsáveis pela lesão da mucosa, erosão óssea e fibrose e, deste modo, pela surdez que se observa em alguns casos de otite média secretora crônica (51) . As evidências indicam que a função diferenciada dos macrófagos tem um possível fator de controle central, na persistência da efusão do ouvido médio.…”

“…A participação, neste processo, de células mediadas pelo processo inflamatório, pode contribuir de forma importante para a otite média secretora crônica, como parece sugerir a presença de neutrófilos, linfócitos, macrófagos e remanescentes celulares dos fluidos da efusão, do espaço subepitelial e do espaço do ouvido médio. Contribuições adicionais de anticorpo, complemento, coagulação, fibrinólises, prostaglandinas e outros sistemas, têm sido identificadas na otite média com efusão (51) . Maxwell et al (1994) (54) demonstraram que a interleucina-8, juntamente com a interleucina-1 beta e o fator de necrose tumoral beta, são responsáveis pelo acúmulo de leucócitos no espaço do ouvido mé-dio e pela ativação desses leucócitos, com subseqüente lesão do tecido.…”