Effects of benzalkonium chloride on histamine H1 receptor mRNA expression in nasal epithelial cells

To better understand the causes of the exacerbation of rhinitis medicamentosa (RM) induced by oxymetazoline (OMZ) or benzalkonium chloride (BKC), we examined the impact of pretreatment with OMZ or BKC on cultured human nasal epithelial cells. We also examined the effect of mometasone furoate (MF) on the cultured human nasal epithelial cells treated with OMZ or BKC.

Cells of the human nasal epithelial cell line HNEpC were treated with OMZ or BKC, and the OMZ- and BKC-induced expression of histamine H1 receptor (H1R) mRNA was assayed using real-time polymerase chain reaction. In some experiments, 1.0×10(-5)M MF was added to the HNEpC cells for 24h before treatment with OMZ or BKC.

Treatment with OMZ slightly increased the expression level of H1R mRNA in HNEpC cells. This enhanced expression was not significantly reduced by pretreatment with MF. In contrast, treatment with BKC remarkably increased the expression level of H1R mRNA in HNEpC cells. In addition, this enhanced expression was significantly reduced by pretreatment with MF.

These results suggest that the increased expression of H1R mRNA due to treatment with OMZ or BKC might be one of the factors underlying the exacerbation of symptoms in patients with RM and those complicated with allergic rhinitis. The concomitant use of a nasal steroid might reduce the exacerbation of symptoms caused by BKC, although there remains a risk of developing histamine hypersensitivity from the long-term use of a topical steroid-containing BKC.