Effects of corticosteroid on mRNA levels of histamine H1 receptor in nasal mucosa of healthy participants and HeLa cells

The purpose of this study is to examine the effect of intranasal corticosteroid (INCS) administration on histamine H1 receptor (H1R) gene expression in the nasal mucosa of healthy participants and the effects of dexamethasone on basal and histamine-induced H1R mRNA expression, and histamine-induced phosphorylation of extracellular signal-regulated kinase (ERK) in HeLa cells. Sixteen healthy participants were given INCS once daily for a week. After pretreatment of dexamethasone, HeLa cells were treated with histamine. Levels of H1R mRNA and phosphorylation of ERK were measured using real time PCR and immunoblot analysis, respectively. Levels of H1R mRNA in the nasal mucosa of healthy participants receiving INCS was significantly decreased. Dexamethasone suppressed basal levels of H1R mRNA, and histamine-induced up-regulation of H1R mRNA and ERK phosphorylation in HeLa cells. These data suggested that corticosteroid inhibited both basal transcription and histamine-induced transcriptional activation of H1R through its suppression of ERK phosphorylation in the signaling pathway involved in H1R gene transcription. It is further suggested that pre-seasonal prophylactic administration of INCS suppresses both basal and pollen-induced upregulation of H1R gene expression in the nasal mucosa of patients with pollinosis, leading to prevention of the exacerbation of nasal symptoms during peak pollen season.