Growth Factors and Their Receptors in the Middle Ear Mucosa During Otitis Media

• Published in: The Laryngoscope 2002-03, Vol.112 (3), p.420-423
• Main Authors: Palacios, Sean D., Pak, Kwang, Rivkin, Alexander Z., Bennett, Thecla, Ryan, Allen F.
• Format: Article
• Language: English
• Subjects: Animals; Ear, Middle - metabolism; Epithelium - metabolism; growth factors; Growth Substances - metabolism; Haemophilus Infections - metabolism; Haemophilus influenzae; Hyperplasia; Male; Middle ear mucosa; otitis media; Otitis Media - metabolism; Otitis Media - microbiology; Rats; Rats, Sprague-Dawley; receptors; Receptors, Growth Factor - metabolism; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger - metabolism
• ISSN: 0023-852X; 1531-4995
• DOI: 10.1097/00005537-200203000-00002

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. Study Design 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 105/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‐α. 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‐α 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.