Effect of acute exposure to electronic cigarette on bronchoalveolar lavage fluid and pulmonary surfactant protein in mice / 预防医学

ABSTRACT

Objective@#To assess the effects of acute exposure to electronic cigarette ( e-cigarette ) on leukocyte and total protein levels in bronchoalveolar lavage fluid ( BALF ) and pulmonary surfactant protein expression in a mouse model, so as to provide insights into the elucidation of the mechanism underlying the damages to the respiratory system caused by e-cigarette.@*Methods@#Twenty-one C57BL/6N female mice were randomly divided into the blank control group, the solvent control group and the nicotine group. Mice in the solvent control group and the nicotine group were exposed to the solvent aerosol or e-cigarette aerosol containing 25 mg/mL nicotine for 3 hours daily, while mice in the blank control group were bred in clean air. Following 3-day exposure, mouse BALF and lung specimens were collected. The cell morphology was observed using microscopy following Wright-Giemsa staining and the leukocyte count was estimated in BALF, while the total protein expression was quantified using bicinchoninic acid ( BCA ) assay. In addition, the mRNA expression of pulmonary surfactant protein genes was detected in mouse lung specimens using quantitative real-time PCR ( qPCR ) assay.@*Results@#All mice in three groups grew well without obvious abnormality or death seen. Wright-Giemsa staining showed a higher number of mononuclear macrophages in mouse BALF in the nicotine group than in the blank control group and the solvent control group. The leukocyte counts were ( 2.00±0.77 )×107, ( 1.79±0.99 )×107 and ( 4.00±1.35 )×107 cells/L ( F=9.199, P=0.002 ), and the total protein levels were ( 0.16±0.03 ), ( 0.12±0.02 ) and ( 0.16±0.04 ) mg/mL in mouse BALF in the blank control group, solvent control group and nicotine group ( F=3.610, P=0.048 ), and the relative mRNA expression of pulmonary surfactant protein B (SP-B) and SP-D was 1.00±0.14, 0.82±0.12 and 0.74±0.07 ( F=5.491, P=0.028 ), and 1.00±0.06, 0.90±0.02 and 0.71±0.15 in mouse lung specimens, respectively ( F=10.460, P=0.005 ). The leukocyte count was significantly higher in the nicotine group than in the blank control group and solvent control group (P=0.007, 0.003), and the total protein content was higher in the nicotine group than in the solvent control group ( P=0.060 ), while the relative SP-B mRNA expression was lower in the nicotine group than in the blank control group ( P=0.025 ), and the relative SP-D mRNA expression was lower in the nicotine group than in the blank control group and solvent control group ( P=0.004, 0.041 ).@*Conclusion@#Acute exposure to e-cigarette results in elevated intrapulmonary inflammatory responses, pulmonary capillary barrier impairment and reduced pulmonary surfactant protein expression.