Clinical and pathogenic aspects of otitis media

The first part of this thesis evaluates two different treatment strategies in tympanostomy tube associated otorrhea. The second explores the tentative relation between the appearance of otitis media with effusion and the immunological activity in the adenoid, focusing on Toll-like receptor (TLR) 4 and TLR7 along with the nitric oxide (NO) inducing enzymes eNOS and iNOS. The third part investigates if TLRs and Nod-like receptors (NLRs) can be found in the middle ear mucosa and if their expression is affected by chronic middle ear disease. Finally, the prerequisites for local NO production in the middle ear during health and disease is studied. With the duration of otorrhea as primary outcome variable no difference was seen when tympanostomy tube associated otorrhea was treated topically with or without concomitant systemic antibiotics. This implies that topical treatment alone is sufficient in most cases of tube-associated otorrhea, and that a watch-and-wait policy can be recommended vis-à-vis the use of systemic antibiotics. Bacterial cultures showed a clear dominance of typical middle ear pathogens indicating that the otorrhea episodes reflected new episodes of acute otitis media. TLR4, TLR7, eNOS and iNOS mRNA together with their corresponding proteins could be demonstrated in all adenoids tested. Adenoids from children with otitis media with effusion exhibited higher expression of TLR7 and lower expression of iNOS than controls. Since TLR7 interacts with single-stranded virus RNA it might be that viral infections via this receptor trigger immune reactions in the adenoid that contributes to the development of otitis media with effusion. NO is known to induce anti-microbial effects. A reduced ability to produce NO, reflected in low iNOS levels, might therefore signal an increased risk for developing middle ear disease. mRNA and protein representing TLR3, TLR4, TLR5, TLR7 along with the Nod-like receptors (NLRs) Nod2 and NALP3 were found in the middle ear mucosa. Patients with chronic middle ear disease exhibited lower expression of TLR4, TLR5, TLR7 and Nalp3 than controls, whereas Nod2 was up-regulated. The finding of TLRs and NLRs represent possible activation sites in what has previously been considered as a compartment low in immunological activity. It opens new perspectives on how the middle ear can be defended against invading micro-organisms. Further, it is not inconceivable that an abnormal set of innate immune receptors can affect the development and outcome of chronic middle ear disease. eNOS mRNA was detected in the middle ear mucosa whereas iNOS expression was generally low. Mucosa from patients with chronic middle ear disease displayed reduced levels of eNOS in comparison to controls. Gas sampled from the middle ear contained more NO than gas sampled from the ear channel of the contra lateral ear. Together, this indicates that NO might be a natural component of the middle ear gas milieu important for maintaining a healthy local environment. LIST OF PUBLICATIONS The present thesis is based on the following papers, which will be referred to by their Roman numerals I. Granath A, Rynnel-Dagöö B, Backheden M, Lindberg K Tube associated otorrhea in children with recurrent acute otitis media; results of a prospective randomized study on bacteriology and topical treatment with or without systemic antibiotics International Journal of Pediatric Otorhinolaryngology 2008; 72:1225-1233 II. Granath A, Uddman R, Cardell LO Increased TLR7 expression in the adenoids among children with otitis media with effusion Acta Oto-Laryngologica 2010; 130: 57-61 III. Granath A, Norrby-Teglund A, Uddman R, Cardell LO Reduced iNOS expression in adenoids from children with otitis media with effusion Pediatric Allergy and Immunology 2010; in press IV. Granath A, Uddman R, Cardell LO Deranged Tolland Nod-like receptor expression in the middle ear mucosa in patients with chronic middle ear disease Submitted V. Granath A, Weitzberg E, Cardell LO Nitric oxide production in human middle ear mucosa Manuscript