Effects of narrow‐band UVB on nasal symptom and upregulation of histamine H(1) receptor mRNA in allergic rhinitis model rats

BACKGROUND: Phototherapy with narrow‐band ultraviolet B (narrow‐band UVB) is clinically effective treatment for atopic dermatitis. In the present study, we examined the effects of intranasal irradiation with narrow‐band UVB on nasal symptom, upregulation of histamine H(1) receptor (H1R) gene expression and induction of DNA damage in the nasal mucosa of allergic rhinitis (AR) model rat. METHODS: AR model rats were intranasally irradiated with 310 nm of narrow‐band UVB. Nasal mucosal levels of H1R mRNA were measured using real‐time quantitative reverse transcriptase (RT)‐PCR. DNA damage was evaluated using cyclobutane pyrimidine dimer (CPD) immunostaining. RESULTS: In toluene 2,4‐diisocyanate (TDI)‐sensitized rats, TDI provoked sneezes and H1R gene expression in the nasal mucosa. Intranasal pre‐irradiation with 310 nm narrow‐band UVB at doses of 600 and 1400, but not 200 mJ/cm(2) significantly inhibited the number of sneezes and upregulation of H1R gene expression provoked by TDI. CPD‐positive cells appeared in the nasal mucosa after intranasal narrow‐band UVB irradiation at a dose of 1400, but not 200 and 600 mJ/cm(2). The suppression of TDI‐provoked sneezes and upregulation of H1R gene expression lasted 24 hours, but not 48 hours, after narrow‐band UVB irradiation with a dose of 600 mJ/cm(2). CONCLUSIONS: Intranasal pre‐irradiation with narrow‐band UVB dose‐dependently inhibited sneezes and upregulation of H1R gene expression of the nasal mucosa in AR model rats, suggesting that the inhibition of nasal upregulation of H1R gene expression suppressed nasal symptom. The suppression after narrow‐band UVB irradiation at a dose of 600 mJ/cm(2) was reversible without induction of DNA damage. These findings indicated that low‐dose narrow‐band UVB phototherapy could be effectively and safely used for AR treatment in a clinical setting. LEVEL OF EVIDENCE: NA.