Journal
JOURNAL OF ALLERGY AND CLINICAL IMMUNOLOGY
Volume 109, Issue 1, Pages 75-81Publisher
MOSBY, INC
DOI: 10.1067/mai.2002.120274
Keywords
asthma; bronchial epithelium; erbB receptor; epidermal growth factor; transforming growth factor alpha; phosphorylation; wound repair
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Background: The c-erbB family of receptor tyrosine kinases act in a combinatorial fashion to regulate cell behavior. Disturbances in this system have been associated with neoplastic and inflammatory diseases. Objectives: Although expression of the epidermal growth factor receptor (EGFR; c-erbB1) is increased in the bronchial epithelium in asthma, there is no information on expression of other members of the c-erbB receptor and ligand family that can modulate EGFR function. Methods: Immunohistochemistry was used to compare expression of EGFR, c-erbB2, c-erbB3, epidermal growth factor, heparin-binding epidermal growth factor-like growth factor, and transforming growth factor a in bronchial biopsy specimens from normal and asthmatic subjects. Scrape-wounded monolayers of 16HBE 14o(-) cells were used as an in vitro model of damage and repair. Changes in EGFR, c-erbB2, and cerbB3 distribution were measured by means of immunocytochemistry, whereas tyrosine phosphorylation was measured by means of immunoprecipitation and Western blotting. Results: Although epithelial staining for the EGFR was significantly increased in asthmatic epithelium (P <.001), there was no difference in staining for the other receptors and ligands studied. In scrape-wounded epithelial monolayers, tyrosine phosphorylation of EGFR, c-erbB2, and c-erbB3 occurred immediately after damage; however, only EGFR showed a change in expression in response to damage. Conclusions: Even though EGFR levels are increased in asthma, this is not linked to changes in expression of its activating ligands or other c-erbB receptors. Because bronchial epithelial cells respond to physical damage through activation of several c-erbB family members, the shift in favor of increased EGFR levels in asthma may lead to altered epithelial function by influencing the number and type of heterodimeric signaling complexes, assuming sufficient ligand availability.
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