Effectiveness of Dp2 nasal therapy for Dp2- induced airway inflammation in mice: using oral Ganoderma lucidum as an immunomodulator.

Nasal immunotherapy with allergen has been reported to be effective for airway allergic disease. A group of 50 male Balb/c mice were immunized intraperitoneally with recombinant Dermatophagoides pteronyssinus group 2 (rDp2), then oral feeding with Ganoderma lucidum (known as "Ling Zhi," LZ OT) and intranasal therapy with native Dp2 (Dp2 NT) were given, the mice then received intratracheal challenge with rDp2 at 28 days and 35 days after immunization. Airway hypersensitivity to methacholine was measured 30 min (early phase) and 24 h (late phase) after the second challenge. The cytokine producing CD4 cells in PBL and interferon-gamma (IFN-gamma) concentrations in bronchoalveolar lavage fluid and sera were measured on 37 days after immunization. Both Dp2 NT and LZ OT downregulated total inflammatory cell infiltration in the airway. Dp2 NT reduced IL-5+/CD4+ cells and increased IFN-gamma+/CD4+ cells. When LZ OT was added to Dp2 NT, the reduction of IL-5+/CD4+ cells was diminished and the increment of IFN-gamma+/CD4+ cells was increased. LZ OT alone increased both IL-5+/CD4+ cells and IFN-gamma+/CD4+ cells. When LZ OT was added to Dp2 NT, IgG2a was further increased to a significant level. LZ OT alone significantly suppressed IgG1 and increased IgG2a production. When lung function was measured after therapy, early phase airway hypersensitivity to methacholine significantly suppressed by Dp2 NT, while late phase hypersensitivity was suppressed but not to a significant level. When LZ OT was added to Dp2 NT, the suppression of late phase airway hypersensitivity to methacholine reached a significant level. In this mouse model of Dp2-induced airway hypersensitivity, Dp2 NT downregulated airway inflammatory cell infiltration and decreased immediate airway hypersensitivity to methacholine. When LZ OT was coadministered, the airway lymphocytes and circulatory IFN-gamma+/CD4+ were both increased and late phase airway hypersensitivity was decreased. These results suggest that Dp2 NT might have a therapeutic effect on Dp2-induced airway hypersensitivity and LZ OT might also have an effect on Dp2 NT immunotherapy.