A mechanism of antigen-induced mucus production in nasal epithelium of sensitized rats. A comparison with lipopolysaccharide-induced mucus production.

We produced ovalbumin (OVA)-sensitized rats as an animal model of nasal allergy. Intranasal instillation of OVA induced hypertrophic and metaplastic changes of goblet cells in nasal epithelium of OVA- sensitized rats. Intraepithelial mucosubstance in nasal mucosa increased significantly at 24 h after 3 or 7 d of OVA instillation, accompanied by mucosal infiltration of eosinophils. The effects of H1-antagonist (d-chlorpheniramine malate), H2-antagonist (cimetidine), dexamethasone, indomethacin, cysteinyl leukotrienes (cysLTs)-antagonist (ONO1078), and antirat neutrophil antiserum on OVA-induced changes were examined. Mucus production was significantly inhibited by dexamethasone, and ONO1078, whereas eosinophil infiltration was significantly inhibited by H1-antagonist, dexamethasone, and anti-rat neutrophil antiserum. These results indicate that cysLTs (LTs C4, D4, and E4) may play an important role in antigen-induced mucus production, and that eosinophil infiltration does not relate to mucus production. Intranasal instillation of lipopolysaccharide (LPS) also induced intraepithelial mucus production, and it was significantly inhibited by dexamethasone, indomethacin, and antirat neutrophil antiserum; however, cysLTs antagonist had no effect on LPS-induced change. These results indicate that neutrophil and cyclooxygenase products are important in LPS-induced mucus production, and there are different mechanisms of mucus production between allergic inflammation and LPS stimulation.