Association between human beta defensin expression and cholesteatoma formation

Objective To investigate an association between human beta defensin (hBD) expression and cholesteatoma formation. Methods hBD-2 mRNA expressions were assessed in healthy external acoustic meatus skin organ cultures before and after stimulation with Pseudomonas aeruginosa. In addition, hBD-1 and hBD-2 protein production of stimulated and non-stimulated external acoustic meatus skin was visualized by immunohistochemistry. Furthermore, hBD-1 and hBD-2 mRNA expression was analyzed in 25 external acoustic meatus skin, 29 cholesteatoma, and 18 non-cholesteatoma control samples. Non-stimulated meatal tissue preparation did not express hBD-2, whereas incubation with P. aeruginosa demonstrated hBD-2 induction. Results The hBD-1 mRNA expression was detected in cholesteatoma (14/17), meatal skin, and middle ear mucosa (11/18). hBD-2 mRNA expression was shown in eight cholesteatoma (28.5%) and in three middle ear mucosa tissue samples (37.5%). Conclusion Our data suggest constitutional hBD-1 and inducible hBD-2 expression in chronic middle ear infection and cholesteatoma. Failure of hBD-1 and hBD-2 expression might dispose to exacerbation of cholesteatoma disease. The organ culture model of the external acoustic meatus skin is effective in order to evaluate germ stimulation experiments.