Middle ear specific proteins in glue ears

Pattern changes of mucin gene expression with pneumococcal otitis media

OBJECTIVE

mucins, known to be important components of the mucociliary transport system in the middle ear and Eustachian tube, are subject to changes under inflammatory conditions. Which mucin genes are up-regulated or activated during an inflammatory reaction of the middle ear and Eustachian tube, however, is poorly understood. The purpose of this study was to characterize mucin gene expression in middle ears and Eustachian tubes with pneumococcal ear infection.

METHODS

sixteen rats received intrabullar inoculation of Streptococcus pneumoniae type 6A at 2.5x10(6) colony forming units (CFU). Four animals were sacrificed on days 1, 3, 7, and 14, respectively. The profile of mucin gene expression in the middle ear and Eustachian tube was examined by reverse transcription polymerase chain reaction (RT-PCR) at the above time points. Sixteen rats that received intrabullar inoculation of phosphate-buffered saline (PBS) served as controls.

RESULTS

the Muc2 mucin gene was expressed in middle ear mucosa of the control rats. Following pneumococcal inoculation, Muc1-Muc5 mucin genes were expressed in the middle ear mucosa in a time-dependent manner. In the Eustachian tube, the Muc2, Muc4 and Muc5 mucin genes were expressed in both control and pneumococcal inoculation groups.

CONCLUSION

Muc1, Muc3, Muc4, and Muc5 mucin genes were activated in the middle ear mucosa by pneumococci, which may contribute to hyper-production of mucin in acute pneumococcal otitis media.

Sugar components of glycoprotein fractions in middle ear effusions

We analyzed the sugar components of the glycoprotein fractions in human middle ear fluid samples by using gas chromatography. All ear effusions included serous, seromucinous and mucoid samples, and contained appreciable amounts of fucose, mannose, galactose, glucose, N-acetyl glucosamine and sialic acid. Total sugar content to protein was significantly higher in mucoid effusions than in serous effusions. Among the sugar components, the contents of sialic acid, N-acetyl glucosamine, fucose and galactose were much higher in the mucoid effusions. The data show new evidence that some glycoproteins having high proportions of sialic acid, N-acetyl glucosamine, fucose and galactose appear in the middle ear fluid of the glue ear.

Inflammatory cell subpopulations in the middle ear mucosa of ears with effusion

Middle ear mucosal biopsies were taken from 11 patients with middle ear effusion. In 8 cases the specimens were sufficiently large to allow detailed studies of the submucosal cellular components. It appears that in noncomplicated serous middle ear effusion, due to mechanical obstruction of the Eustachian tube, the submucosa is not infiltrated by inflammatory cells. In all types of mucoid effusion of variable duration, various lymphocyte classes, i.e. T- and B-lymphocytes and plasma cells, were present, suggesting a normal cellular immune response. The lack of granulocytes seems to indicate that there is no submucosal infection.

Azidocillin and ampicillin concentrations in middle ear effusion

The penetration of azidocillin and ampicillin into the middle ear effusion after oral administration was studied and compared with blood levels of the drugs. In acute otitis media one hour after a single oral dose of azidocillin (15 mg/kg) 1.56 +/- 0.44 microgram/ml of the drug was found in the effusion fluid; after 2 hours the fluid contained 3.21 +/- 0.87 microgram/ml and after 12 hours,0.84 +/- 0.13 microgram/ml. The concentrations of ampicillin were 1.15 +/- 0.23 microgram/ml after one hour, 2.17 +/- 0.46 microgram/ml after 2 hours and 1.09 +/- 0.22 microgram/ml after 8 hours following a single oral dose of 10 mg/kg. Both drugs stay longer in the middle ear secretion than in the blood. This persistence supports the administration of azidocillin twice daily in acute otitis media. In contrast, the penetration of the drugs into the middle ear effusion fluid was poor in secretory otitis media, where the levels of the drugs were significantly lower.