Effect of SC or IP route sensitization on airway inflammation and immunological response
Compared with the respective control groups, mice sensitized with HSE by either the IP or SC routes both developed severe AHR to Mch, characterized by significantly greater Penh values at 6.25, 12.5, 25 and 50 mg/mL of Mch inhalation (Fig. 2A, P<0.01 or P<0.05). These changes were accompanied by recruitment of total white blood cells and inflammatory cell subpopulations (e.g., eosinophils and neutrophils) to the airways (Fig. 2C1,P<0.01, respectively); elevated levels of IL-13 (Fig. 2D2, P<0.01) and IL-10 (Fig. 2D4, P<0.05) in the BALF; inflammatory infiltrates around bronchi; and elevated mucus production (Fig. 3C, P<0.01).In contrast, IL-13 (Fig. 2D2) levels and IL-10 (Fig. 2D4) levels in SHS, and IFN-γ (Fig. 2D3) levels in both BALF and SHS, did not show any clear changes in HSE-sensitized mice, compared with the respective control groups.
In addition, compared with mice in the SC.PBS group, mice sensitized with HSE by the SC route developed higher HSE-specific serum IgE levels (Fig. 2B, P<0.01); higher numbers (Fig. 2C1,P<0.01) and percentages (Fig. 2C2, P<0.01) of BALF eosinophils; and higher production of IL-4 in BALF (Fig. 2D1, P<0.01) and SHS (Fig. 2D1, P<0.05). However, these characteristics were not observed in the IP.HSE group, compared with the IP.PBS group (Fig. 2B, C1, C2, and D1).
Notably, HSE-specific serum IgE levels (Fig. 2B, P<0.01); numbers (Fig. 2C1, P<0.01) and percentages (Fig. 2C2, P<0.01) of BALF eosinophils; and production of IL-4 in BALF (Fig. 2D1, P<0.05) and SHS (Fig. 2D1, P<0.05) were all significantly higher in the SC.HSE group than in the IP.HSE group.
Futhermore, the protein profile of HSE (determined by SDS-PAGE) is shown in Fig. 4A; the molecular weight of the proteins mainly ranged from 10 kDa to 100 kDa. Most sera from animals in the SC.HSE and IP.HSE groups exhibited IgE reactivity against HSE proteins with apparent molecular masses of 48–100 kDa (Fig. 4B). There were no significant differences in the distribution of immunoreactive bands between animals in the SC.HSE and IP.HSE groups. Pooled sera of animals in the control group showed no binding of IgE to HSE.