Mutins are the major glycoprotein component of respiratory tract secretions. Little is known about their expression in the upper respiratory tract. In order to define this expression, in situ hybridization was performed on 19 normal and 4 vasomotor rhinitis (VMR) inferior turbinâtes to identify mutin mRNA. MUC1, MUC2, MUC4, MUC5AC, MUC5B, and MUC7 were expressed in both the normal and VMR turbinâtes. MUC 4 and MUC5AC were the most highly expressed mutins. MU Cl, MUC2, MUC4, and MUC5AC were expressed mainly by the epithelial border, whereas MUC5B and MUC7 were expressed by the submucosal glands. MUC1 and MUC4 exhibited a diffuse expression by multiple cell types along the mucosal border, whereas MUC2 and MUC5AC expression appeared to be limited to a subpopulation of epithelial cells, most likely goblet cells. Although MUC1, MUC4, and MUC5AC showed sporadic submucosal glandular expression, MUC5B and MUC7 appeared to be the predominant submucosal gland mutins in the inferior turbinâtes. MUC3 and MUC6 expression, which have been found primarily in the gastric mucosa, were not seen in any of the inferior turbinate samples examined. The only difference seen between normal and VMR turbinâtes was a slight decrease in MUC1 expression in the VMR group. The variety of mutins expressed and the diversity of their expression patterns may have significance in terms of the rhéologie and particle clearance properties of nasal secretions. Understanding the expression patterns in normal turbi-nates will serve as the foundation for further study of these mucins in disease states.
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