Inflammatory and functional responses after (bio)diesel exhaust exposure in an asthmatic mice model – A comparison between diesel and biodiesel

Background: Since biodiesel (BD) combustion produces less particulate matter than diesel (D), BD exposure is expected to cause less adverse effects on allergic asthma. However, limited data is available regarding BD health effects. Objective: This study was designed to determine whether biodiesel exhaust (BDE) exposure in a mouse model of allergic asthma shows different effects on inflammatory and functional responses compared to DE exposure. Methods: BALb/c mice were sensitized weekly with 100µg HDM dissolved in 50 µL of PBS, or solely PBS. From day 9 till day 17 they were exposed daily to filtered air, 600 µg/m 3 diesel emissions or 600 µg/m 3 BD emissions. Total and differential BAL cell counts, BAL cytokine levels and lung function were assessed 24 hours after the last exposure. Results: Total cell counts of sensitized mice exposed to diesel (DS) were significantly higher than both sensitized mice exposed to filtered air (FAS) and biodiesel (BDS) (p=0.021; p=0.03 respectively). This was also evident in differential cell counts for neutrophils (p=0.005; p=0.004) and macrophages (p=0.01; p=0.036 respectively). IL1β showed a significant increase for DS compared to FAS (p=0.009), and control mice exposed to diesel (DC) showed higher IL1β levels than control mice exposed to filtered air (FAC) (p=0.042). There were no significant differences between DE and BDE exposures. Airway hyperresponsiveness in control groups was lower in BDE exposed mice as compared to DE. Sensitized mice remained similar. Conclusion: The results indicate that BDE has less effect on inflammatory and functional parameters than DE in both allergic asthmatic and control mice.