epidermal-growth-factor and Rhinitis--Allergic--Seasonal

We were interested in exploring the molecular mechanisms underlying the observed difference in histamine (H) responsiveness between seasonal allergic rhinitic (SAR) and nonrhinitic (NR) subjects. We hypothesized that SAR subjects express higher nasal mucosal histamine receptor 1 (H1R) and 2 (H2R) levels than do NR subjects. In addition, we examined expression of genes involved in regulating the glandular response, including epidermal growth factor (EGF), EGF receptor (EGFR), and mucins (Muc5Ac and Muc5B).. Fourteen subjects, seven SAR and seven NR, were provoked during pollen season with doubling doses of H (0.125-8.0 mg/ml). Nasal airway resistance (NAR) was measured by active posterior rhinomanometry. Provocation was halted when NAR exceeded 150% of baseline. Prior to provocation, nasal scrapings were obtained and mRNA quantified using two-step real-time PCR.. The mean PD50 (concentration of H producing a 50% increase in NAR) was significantly lower in the SAR than NR group (0.36 vs 1.32 mg/ml; P < 0.05). The ratio of relative gene copy numbers between the SAR and NR groups were as follows: H1R, 0.85 (P = 0.52); H2R, 0.67 (P = 0.35); EGF, 1.02 (P = 0.93), and EGFR, 103.5 (P < 0.05).. There were no significant differences in H1R or H2R mRNA levels between SAR and NR subjects in-season, despite observed differences in H reactivity. SAR subjects, however, did show a significant elevation in EGFR expression, consistent with the observation of mucus hypersecretion in allergic rhinitis.

Topics: Adult; Aged; Airway Resistance; Case-Control Studies; Epidermal Growth Factor; ErbB Receptors; Female; Gene Dosage; Histamine; Humans; Male; Middle Aged; Nasal Cavity; Nasal Provocation Tests; Receptors, Histamine H1; Receptors, Histamine H2; Rhinitis, Allergic, Seasonal; RNA, Messenger; Up-Regulation

The nasal epithelium protects the underlying tissue from damage. Epithelial cell growth is controlled by epidermal growth factor (EGF) and is possibly affected by toxic proteins, e.g. eosinophil cationic protein (ECP). The aims of this study were to examine nasal fluid epithelial cell counts and their relations to EGF, eosinophils and ECP in 23 patients with seasonal allergic rhinitis and 20 healthy controls. Nasal fluid epithelial cell counts were lower in patients than in controls. EGF levels did not differ between patients and controls, and correlated with epithelial cell counts in controls but not in patients. Eosinophils and ECP were higher in patients than in controls, but did not correlate with epithelial cell counts. The role of growth factors, such as EGF, in regulating epithelial cells merits further study.

Topics: Adolescent; Adult; Aged; Blood Proteins; Cell Count; Eosinophil Granule Proteins; Eosinophils; Epidermal Growth Factor; Humans; Middle Aged; Nasal Mucosa; Rhinitis, Allergic, Seasonal; Ribonucleases