Exposure to hypergravity increases serum interleukin-5 and pulmonary infiltration in mice with allergic asthma

OBJECTIVE We evaluated the effect of acute hypergravity (HG) on the immune response in a murine model of allergic asthma. MATERIAL AND METHODS Twenty-eight BALB/c mice were used. Group A (control group, n = 7) mice were sensitized and challenged with normal saline. Group B (control HG exposure group, n = 7) mice were sensitized, challenged with saline, and exposed to acute HG (+10 Gz) for 4 hours. Group C (asthma group, n = 7) mice were challenged with intraperitoneal and intranasal ovalbumin (OVA) to induce asthma. Group D (asthma HG exposure group, n = 7) mice were exposed to HG for 4 hours after the induction of asthma. We estimated the total and OVA-specific serum IgE, serum titers of various cytokines, and the number of eosinophils, neutrophils, and lymphocytes in bronchoalveolar lavage (BAL) fluid. Histopathology of the lung was also evaluated. RESULTS The serum level of interleukin (IL)-5 was significantly higher in Group D (12.9 ±4.9 pg/ml) compared to that in Group C (4.7 ±6.5 pg/ml, p = 0.017). In BAL fluid, the number of neutrophils was significantly increased in Group D compared to Group C (p = 0.014). Group D demonstrated a higher infiltration of inflammatory cells (9973.8 ±1642.7 cells/mm(2)) compared to Group C (7666.3 ±586.5 cells/mm(2), p = 0.017). This tendency of increase in infiltration was not significant in non-asthmatic animals (Group A: 4488.8 ±176.1 cells/mm(2) vs. Group B: 4946.3 ±513.7 cells/mm(2), p > 0.05). CONCLUSIONS Acute HG exacerbated the allergic response by increasing serum IL-5 levels and promoting pulmonary infiltration of inflammatory cells.