Differential properties of mucous glycoproteins produced by allergic inflammation and lipopolysaccharide stimulation in rat nasal epithelium.

To examine the differential properties of mucous glycoproteins, we produced hyperplastic and metaplastic changes in goblet cells of rat nasal epithelium by intranasal instillation of ovalbumin (OVA) in OVA-sensitized rats, and by intranasal lipopolysaccharides (LPS) instillation. The epithelial mucosubstance was quantitatively examined by AB-PAS and lectin histochemistry. The newly produced mucin after OVA challenge or LPS instillation contained a high amount of sulfomucin and a low amount of neutral glycoprotein: LPS-induced mucin contained more sulfomucin (70.1% of total) and less neutral glycoprotein (8.6%) than OVA-induced mucin (sulfomucin 33.6%, neutral glycoprotein 41.8%). Four of the lectins, PNA, MAL II, SNA, UEA I, stained some of the mucosubstance, indicating the presence of galactose-N-acetylgalactosamine, α2,3-linked and α2,6-linked sialic acid-galactose, and fucose residues. After LPS instillation, the reactivity was higher for galactose-N-acetylgalactosamine (64.8% of total) and α2,3-linked sialic acid-galactose (75.8%) than after saline instillation (3.5 and 19.1%, respectively) or OVA challenge (5.8 and 32.3%). A 2-fold increase in mucin mRNA (rat Muc5ac) expression was induced after LPS instillation or OVA challenge. These results indicate that mucin mRNA expression increases similarly after LPS instillation or OVA challenge, however, carbohydrate compositions of newly produced mucin are different between the two groups.