Objective: to reproduce an asthma model in ovalbumin (OVA)-sensitized Balb/C mice by OVA challenge and Lipopolysaccharide (LPS) induction.
Methods: one hundred and twenty BALB/C mice were randomly divided into 6 groups: PBS control group (A group, PBS sensitization and PBS challenge), OVA group (B group, OVA sensitization and OVA challenge), low-dose LPS/LPS group (C1 group, 50 microg LPS sensitization and 50 microg LPS challenge), high-dose LPS/LPS group (C2 group, 100 microg LPS sensitization and 100 microg LPS challenge), low-dose OVA/LPS group (D1 group, OVA sensitization, OVA challenge and 50 microg LPS induction) and high-dose OVA/LPS group (D2 group, OVA sensitization. OVA challenge and 100 microg LPS induction). Asthmatic symptoms were observed. Airway responsiveness were assessed and lung resistance (R(L)) was calculated using a proprietary software program. Cells in bronchoalveolar lavage fluid (BALF) were counted and lung histopathology was evaluated by HE staining.
Results: (1) asthma symptoms in either D1 group or D2 group was more severe than other groups, especially in D2 group. (2) The level of total BALF cells, macrophages, lymphocytes, eosinophils, and neutrophils in either D1 group or D2 group was significantly higher than that in A group (P < 0.05, P < 0.01). The level of total BALF cells, lymphocytes, eosinophils, and neutrophils in D1 group was significantly higher than that in B group (P < 0.01, respectively). The level of total BALF cells, macrophages, lymphocytes, and neutrophils in D2 group was significantly higher than those in B group (P < 0.05, respectively). (3) When mice were stimulated by Ach (5.0 g/L), R(L) in either D1 group [(9.32 +/- 1.51) cm H2Oxml(-1)xs(-1) (1 cm H2O = 0.098 kPa)] or D2 group [(44.21 +/- 2.88) cm H2Oxml(-1)xs(-1)] was significantly higher than that in A group [(2.41 +/- 0.35) cm H2Oxml(-1)xs(-1)] and B group [(5.96 +/- 1.83) cm H2Oxml(-1)xs(-1)] (P < 0.01, respectively). (4) More marked and extensive asthma-specific changes in lung was observed in either D1 group or D2 group, especially in D2 group.
Conclusion: LPS induction in OVA-sensitized Balb/C mice can lead to more severe airway inflammation and greater airway hyperresponsiveness.