Change of Th17 and expression of RORγt in a murine model of allergic rhinitis after a stimulation of allergen and corticosteroid

Abstract

To study the effects of allergen and corticosteroid on T help 17 (Th17) and orphan nuclear receptor gammat (RORγt) in allergic-rhinitis mice. Experimental allergic rhinitis (AR) was induced by the extract of dermatophagoides pteronyssinus (DP) including 2% ovalbumin (OVA) sensitization in 30 male mice with DP allergen group (n = 10), intranasal corticosteroid (budesonide, BUD) group (n = 10) or without treatment (model group, n = 10). And another 10 were included into the normal control group. The murine levels of Th17 were measured by flow cytometry (FCM). The expression of RORγt mRNA was measured by reverse transcription-polymerase chain reaction (RT-PCR) while that of RORγt protein in nasal mucosa detected by immunohistochemical staining. The expression of RORγt in nasal mucosa of AR model was higher than that in the control group (25 ± 5 vs 48 ± 10, P < 0.01). But its expression declined significantly after the administration of local corticosteroid (48 ± 10 vs 31 ± 6, P < 0.01). The levels of RORγt mRNA and Th17 in the AR model group were significantly higher than those in the control group (18.4% ± 1.3% vs 27.5% ± 1.6%, 0.43 ± 0.04 vs 0.64 ± 0.05, both P < 0.01). The levels of RORγt mRNA and Th17 in the spleen of AR mice were significantly reduced by allergen dosing (27.5% ± 1.6% vs 20.0% ± 2.1%, 0.64 ± 0.05 vs 0.54 ± 0.03, both P < 0.01) but not by corticosteroid (P > 0.05). Allergen may affect the systemic immunity to inhibit the RORγt expression and block the Th17 differentiation in AR model. Local steroid only produces a marked effect through a down-regulated RORγt expression in nasal mucosa.