Cochlear cytokine gene expression in murine acute otitis media.
OBJECTIVE
Recurrent acute otitis media (AOM) causes sensorineural hearing loss by unknown mechanisms. It is widely accepted that inflammatory cytokines diffuse across the round window membrane to exert cytotoxic effects. This study addresses whether inner ear cells are capable of expressing genes for inflammatory cytokines.


METHODS
The authors conducted a prospective animal study.


METHODS
BALB/C mice underwent transtympanic injection of heat-killed Haemophilus influenzae to create an acute inflammatory response. These mice were compared with a control group in addition to a group of uninjected mice found to have otomicroscopic changes consistent with persistent or chronic otitis media. The cochleas of these mice were obtained, their RNA harvested, and cytokine gene expression analyzed using prefabricated cDNA arrays.


RESULTS
Four groups of mice (control, 3-day postinjection, 7-day postinjection, and mice with chronic otitis media) with five mice in each group were analyzed. Numerous classes of genes were found to be upregulated or downregulated by more than twofold. Some genes differed from control mice by more than 10-fold. These genes included numerous fibroblast growth factors, interleukins, tumor necrosis factors, and colony-stimulating factors.


CONCLUSIONS
The genes of numerous inflammatory cytokines are either up- or downregulated by murine inner ear cells in response to either acute or chronic inflammation of the middle ear. This study provides a novel site of production of cytokines that may be responsible for the damage seen in sensorineural hearing loss.
Ghaheri
Bobak A
BA
Department of Otolaryngology/Head and Neck Surgery, Oregon Health & Science University, Portland, Oregon, USA. ghaherib@ohsu.edu
Kempton
J Beth
JB
Pillers
De-Ann M
DA
Trune
Dennis R
DR
D000208:Acute Disease; D000818:Animals; D003051:Cochlea; D016207:Cytokines / Q000235:genetics* / Q000378:metabolism; D004195:Disease Models, Animal; D007758:Ear, Inner / Q000166:cytology; D015870:Gene Expression; D005786:Gene Expression Regulation; D006192:Haemophilus Infections / Q000235:genetics*; D006193:Haemophilus influenzae; D006319:Hearing Loss, Sensorineural / Q000209:etiology*; D051379:Mice; D008807:Mice, Inbred BALB C; D010033:Otitis Media / Q000150:complications / Q000235:genetics* / Q000378:metabolism; D012313:RNA / Q000235:genetics / Q000378:metabolism
D016207:Cytokines; D012313:RNA