Environmental tobacco smoke (ETS) in allergic asthma: A parallel exposure study in human subjects and sensitized allergic Balb/c mice

Introduction: The present study focused on the acute effects of short term (3 hours) exposure to ETS in allergic asthma, in a mouse model as well as in asthmatics. Methods: Analogously 23 non-smoking asthmatics as well as 54 allergen challenged Balb/c mice were exposed to artificially produced ETS in increasing concentrations (I=250 μg/m 3 , II= 450 μg/m 3 , III=850 μg/m 3 ) or to ambient air (control group). In human asthmatics, lung function, exhaled NO and exhaled CO was assessed. Serum samples were analyzed for cytokine profile and distribution of immune cells. Symptom severity was assessed via asthma control test (ACT) and visual analogue scale (VAS) questionnaires. Whole body plethysmography was performed in mice before, after and one day after ETS treatment. The immunological status of mice was assessed by analysing serum cytokines and BALF cell composition. Results: Human asthmatics exposed to ETS II and ETS III had significantly lower FeNO levels, a decrease in lung function of small airways (MEF25, MEF50) and an increase in VAS scores compared to controls. In sera ETS II led to a more antiinflammatory cytokine profile (IL10) whereas ETS III showed a proinflammatory cytokine milieu (IL8, TNF-α) compared to controls. Airway hyperreactivity in mice exposed to ETS II and ETS III was increased. Provocation with metacholine resulted in similar hyperreactivity in both groups. However, control mice displayed an improved recovery after provocation compared to ETS III exposed animals. Conclusion: The data indicate a direct and dose dependent effect of ETS exposure on lung function as well as respiratory inflammation in human asthmatics and sensitized allergic mice.