Growth factors and their receptors in the middle ear mucosa during otitis media.
OBJECTIVE
The hyperplastic response of the middle ear mucosa during bacterial otitis media is thought to be mediated by the actions of growth factors and their respective receptors. The purpose of the study was to explore the expression of growth factors known to stimulate epithelial cells in other systems, as well as their receptors, in the middle ear mucosa during otitis media.


METHODS
Expression of mRNA growth factors and receptors was measured over time after inoculation of the rat middle ear with bacteria.


METHODS
The middle ears of 12 male Sprague-Dawley rats were injected with 10(5)/mL Haemophilus influenzae strain 3655 (nontypeable, biotype II). Three rats were killed at 6, 24, 48, and 72 hours. Three untreated rats were also killed to serve as negative controls. The middle ear mucosa samples were surgically removed and homogenized. Reverse transcription-polymerase chain reaction was performed on each sample with primers for rat epidermal growth factor, epidermal growth factor receptor (ErbB), heparin binding epidermal-like growth factor, hepatocyte growth factor, hepatocyte growth factor receptor, keratinocyte growth factor, betacellulin, amphiregulin, and neuregulin-alpha.


RESULTS
Hepatocyte growth factor and epidermal growth factor receptor primers demonstrated polymerase chain reaction products of the expected size that were not displayed in the normal middle ear mucosa. Keratinocyte growth factor and hepatocyte growth factor receptor demonstrated polymerase chain reaction products at all time points tested. Betacellulin and neuregulin-alpha products were present at all time points except 72 hours after infection.


CONCLUSIONS
The results of the study support a role for growth factors in the middle ear mucosa during otitis media. These bioactive ingredients contribute to mucosal hyperplasia.
Palacios
Sean D
SD
Department of Surgery, University of California, San Diego School of Medicine and Veterans Affairs Medical Center, La Jolla 92093, USA.
Pak
Kwang
K
Rivkin
Alexander Z
AZ
Bennett
Thecla
T
Ryan
Allen F
AF
D000818:Animals; D004432:Ear, Middle / Q000378:metabolism; D004848:Epithelium / Q000378:metabolism; D006133:Growth Substances / Q000378:metabolism*; D006192:Haemophilus Infections / Q000378:metabolism; D006193:Haemophilus influenzae; D006965:Hyperplasia; D008297:Male; D010033:Otitis Media / Q000378:metabolism* / Q000382:microbiology; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D017978:Receptors, Growth Factor / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction
D006133:Growth Substances; D012333:RNA, Messenger; D017978:Receptors, Growth Factor