Histopathology of otitis media with effusion. An electron microscopic study of human temporal bones

Aetiology and pathology of otitis media with effusion in adult life

OBJECTIVES

To gather and analyse information concerning the aetiology and pathology of otitis media with effusion in adults.

METHOD

A review of the English language literature from 1970 to the present was conducted.

RESULTS

The available evidence suggests that otitis media with effusion in adult life is best viewed as a syndrome with a number of causes, including: infiltration of the eustachian tube by nasopharyngeal carcinoma and other local malignancies; changes in the middle ear and eustachian tube induced by radiotherapy; and systemic disease.

CONCLUSION

There is now a body of evidence specifically related to the aetiology and pathology of otitis media with effusion in adult life. However, further research is required to fill in the gaps in our knowledge and understanding of this condition.

Substance P and vasoactive intestinal peptide levels in middle ear effusions of children

CONCLUSION

This is the first report demonstrating high levels of substance P (SP) that inversely correlate with vasoactive intestinal peptide (VIP) levels in middle ear effusions (MEEs) of patients with otitis media with effusion (OME). Increased SP and decreased VIP levels might play a role in the pathogenesis of chronic OME.

OBJECTIVE

The etiology of OME is multifactorial, and neurogenic inflammation may play a significant role. SP and VIP levels were not evaluated previously in MEEs of children with OME.

METHODS

Fifty patients aged 2-12 years (mean age 5.24 ± 2.64) were included in the study. MEEs were classified as mucoid or serous based on the gross appearance. SP and VIP levels were determined using ELISA.

RESULTS

High levels of SP were detected in MEEs. In addition SP levels were significantly higher in serous samples (2910.55 ± 307.96 vs 2218.55 ± 262.30 pg/ml). There were also age-dependent changes, such that SP levels were significantly higher in children aged 2-3 years compared with those who were 4-5 and 6-12 years old. VIP levels were undetectable in 30% of patients and the mean level of VIP was 50.91 ± 16.01 pg/ml in serous middle ear effusions and 54.86 ± 15.91 pg/ml in mucoid MEEs.

The immunoregulatory and allergy-associated cytokines in the aetiology of the otitis media with effusion

Inflammation in the middle ear mucosa, which can be provoked by different primary factors such as bacterial and viral infection, local allergic reactions and reflux, is the crucial event in the pathogenesis of otitis media with effusion (OME). Unresolved acute inflammatory responses or defective immunoregulation of middle inflammation can promote chronic inflammatory processes and stimulate the chronic condition of OME. Cytokines are the central molecular regulators of middle ear inflammation and can switch the acute phase of inflammation in the chronic stage and induce molecular-pathological processes leading to the histopathological changes accompanying OME. In this review we present cytokines identified in otitis media, immunoregulatory [interleukin (IL)-2, IL-10, transforming growth factor-beta]) and allergy associated (IL-4, IL-5, granulocyte-macrophage colony-stimulating factor), as crucial molecular regulators, responsible for chronic inflammation in the middle ear and the chronic condition of OME.

In vitro study of IL-8 and goblet cells: possible role of IL-8 in the aetiology of otitis media with effusion

One of the main characteristics of otitis media with effusion (OME) is the differentiation of basal cells into goblet cells with subsequent proliferation in a modified respiratory epithelium leading to the formation of mucin-rich effusion in the middle ear cleft. In order to determine the effect of pro-inflammatory cytokines identified in OME, e.g. IL-1beta, tumour necrosis factor (TNF)-alpha, IL-6 and IL-8, on goblet cells, and to clarify the role of IL-8 in particular, we used the human goblet cell line HT29-MTX, which secretes two OME-related mucins: MUC5AC and MUC5B. IL-1beta and TNF-alpha stimulated the secretion of IL-8 in HT29-MTX goblet cells. Dose- (2-200 ng/ml) and time- (0-5 days) response studies of IL-8-induced mucin secretion were carried out. IL-8 upregulated the secretion of MUC5AC and MUC5B mucins in a concentration-dependent manner, with a maximum response at an IL-8 concentration of 20 ng/ml. IL-8 (20 ng/ml)-mediated mucin secretion persisted for up to 5 days, with a peak response 72 h after the addition of cytokine. These results suggest that: (i) goblet cells are target cells for the pro-inflammatory cytokines IL-1beta, TNF-alpha and IL-8 and can contribute to the pathogenesis of OME by increasing both the concentration of IL-8 and the secretion of mucin; and (ii) IL-8 stimulates prolonged mucin secretion from goblet cells and may be involved in the maintenance of the disease in the chronic stage.

Colchicine-induced ciliated vacuoles in tracheal mucosa

In most cells the microtubules are destroyed and disappear after administration of colchicine in concentrations as low as 10(-6) M; colchicine inhibits the polymerization of tubulin and destroys the microtubules. Ciliary microtubules have resistance to colchicine but can, on the other hand, be destroyed by high concentrations of colchicine. In this study, we treated rabbits with considerably high concentrations (10 or 20 mg/100 g body weight) of colchicine for four successive weeks and examined the effects on the tracheal cilia. Abdominal administration of colchicine did not affect the morphology and structure of the cilia projecting on the cellular surface. However, ciliated vacuoles were observed in tracheal epithelial cells of rabbits treated with colchicine. The occurrence of such ciliated vacuoles depended on the dosage of colchicine: 2.4 +/- 0.4 per 100 microns epithelial length when treated with 10 mg/100 g body weight of colchicine, and 3.8 +/- 0.3 per 100 microns epithelial length when treated with 20 mg/100 g body weight. Some cilia present in ciliated vacuoles were pathological. In conclusion, a considerably high dosage of colchicine can inhibit ciliary microtubules during ciliogenesis, resulting in ciliated vacuoles.

Experimental otitis media with effusion induced by lipopolysaccharide from Klebsiella pneumoniae. Mucociliary pathology of the eustachian tube

Otitis media with effusion (OME) is generally benign and self-limiting but is often recurrent and can change into a chronic type. We have previously reported that intratympanic inoculation of lipopolysaccharide (LPS) from Klebsiella pneumoniae can develop experimental OME in the guinea pig. However, OME induced by 10 micrograms/ml of LPS was of a self-limiting type. Our hypothesis was that a higher concentration of LPS might develop a chronic OME because LPS reduces the ciliary activity in the tubotympanum in a dose related manner. In our present study we inoculated 100 micrograms/ml of LPS from K. pneumoniae into the tympanic cavity of the guinea pig, in the hope of illuminating a possible mechanism predisposing to the chronicity of the disease. A longer-term OME was observed after tympanic inoculation of 100 micrograms/ml of LPS. Ciliary activity in the Eustachian tube was depressed for a longer term by this dose than by the previous one. In addition to mucociliary pathologies and general inflammatory changes similar to those induced by 10 micrograms/ml of LPS, intracytoplasmic ciliary cysts were observed after inoculation of 100 micrograms/ml of LPS, which appeared to show disturbed ciliogenesis and chronic mucociliary lesions. In conclusion, intratympanic inoculation of a higher concentration of LPS developed a longer-term OME in the guinea pig, which was supported by functional as well as morphological examinations.

Ciliated mucous cells found in the nasal mucosa of a patient with Kartagener's syndrome

Transmission electron microscopy revealed the presence of ciliated cells containing many mucous secretory granules in the nasal surface epithelium of a 13-year-old patient suffering from Kartagener's syndrome. In these cells, mucous secretory granules were accumulated in the apical cytoplasm, and the Golgi apparatus was well developed in the supranuclear region. Mucous secretory granules were discharged infrequently through the apical cell membranes by single or compound exocytosis. The cells were considered to be ciliated mucous cells, which have already been reported to be present in the lower respiratory tract but not in the upper respiratory tract.