Keywords: 
• formaldehyde /
• mice /
• oxidative stress /
• asthma model /
• pulmonary tissue /
• IL-17 expression

Abstract: In this study, an ovalbumin (OVA)-sensitized mice asthma model was established to investigate the effect of different exposure duration of 3.0 mg·m^-3 formaldehyde (FA) in pulmonary oxidative stress and IL-17 expression. 48 male Balb/c mice were randomly divided into 6 groups: (1) saline control group, (2) OVA-sensitized group, (3) OVA-combined with 0.5 h FA group, (4) OVA-combined with 1 h FA group, (5) OVA-combined with 1.5 h FA group, (6) OVA-combined with 2 h FA group. The mouse asthma model was developed by OVA sensitization and challenge. The mice were inhaled with different exposure duration of 3.0 mg·m^-3 FA from day 1 to 35 and were sensitized with OVA+Al(OH)₃ (5 mg OVA and 175 mg Al(OH)₃ in 30 mL saline each time) or saline (30 mL saline each time) by intraperitoneal injection on day 11, 18 and 25. This was then followed by an aerosol challenge in 1% OVA (30 min·d^-1) from day 29 to 35 (7 times) using an ultrasonic nebulizer. On the 36th day, the organ coefficient of mice lung was counted, then the contents of reactive oxygen species (ROS), glutathione (GSH) and malondialdehyde (MDA) of mice lung were measured, and the concentrations of interleukin-17 (IL-17A) were detected by using ELISA. Pulmonary histopathological examination was also conducted. The results showed that compared with control group, the OVA-combined with 1.5 h FA group and OVA-combined with 2 h FA group increased ROS, MDA and IL-17A contents significantly (P<0.01). The results of IL-17 and oxidative stress biomarkers (ROS, GSH and MDA contents) as well as histopathological examination supported the notion that long time (>1.5 h) exposure of 3.0 mg·m^-3 FA may promote and aggravate allergic asthma. Increased ROS, GSH and MDA contents in this mouse model suggested that oxidative stress might be one of the molecular mechanisms of the aggravation effect induced by FA.