Background: Hyperreactivity of the nasal mucosa is a characteristic of nasal allergy. During pregnancy, aggravation of nasal allergic symptoms is occasionally observed in subjects with nasal allergy.
Methods: Using the reverse transcription-polymerase chain reaction and Southern blot hybridization method, we investigated histamine H1 receptor mRNA (H1R mRNA) expressions in specimens of nasal epithelial layer obtained by scraping, as well as cultured human nasal epithelial cells (HNECs) and human mucosal microvascular endothelial cells (HMMECs). We compared the expressions on the specimens from patients with nasal allergy with those with nonallergic rhinitis or those from normal volunteers. In addition, we investigated the effects of female hormones on the H1R mRNA expressions in HNECs and HMMECs.
Results: H1R mRNA was detected in scraped specimens of nasal epithelial layer, as well as in HNECs and HMMECs. The mRNA expressions in nasal mucosal scraped specimens of epithelial layers and HNECs were more marked in patients with nasal allergy than in the other two groups. In addition, the present study demonstrates that the female hormones beta-estradiol and progesterone significantly increase the expressions of H1R mRNA on HNECs and HMMECs.
Conclusion: The increase of the expressions of H1R mRNA may explain, in part, the nasal hyperreactivity to histamine observed in patients with nasal allergy. It has also been suggested that sex hormones are related to the preponderance of females in the incidence of allergic rhinitis after puberty, and that they are related, at least partially, to the aggravation of the nasal hyperreactivity symptoms during pregnancy through the enhanced expression of H1R mRNA on HNECs and HMMECs.