Smoking in Early Developmental Windows Selectively Affects Male Flies

Prenatal cigarette smoke exposure (CSE) is a major risk factor of developing childhood asthma. Moreover, the likelihood of developing asthma may be propagated across generations. Drosophila melanogaster has already been successfully used to explore mechanisms of innate immune dysfunctions and epithelial remodeling, both hallmarks of asthma. Being characterized by short generation time and high fertility, the fly emerges as a useful model to study conserved mechanisms of transgenerational epigenetic inheritance. We aim at establishing a transgenerational Drosophila smoke model to identify highly conserved mechanisms modulated by CSE. Larvae were exposed to mainstream CS (4 puffs/min) generated by a standard smoking machine (SCIREQ, Emka). Cotinine levels were assessed in whole larvae by ELISA (Calbiotech). Expression of Cyp18a1 (Cyp1a1 homolog involved in xenobiotic metabolism) was measured both in whole larvae and isolated airways by qPCR. Larval viability was determined by counting numbers of living larvae, pupae and emerging adults. Survival of the latter was assessed. In whole larvae, cotinine level rose steadily after CSE (3-fold). The expression level of Cyp18a1 was significantly increased in whole larvae up to 60 minutes after CSE (p<0.037). In isolated airways, Cyp18a1 expression was elevated 3-fold (p<0.237). CSE during the larval stage did not affect the survival of emerging adults. However, the mortality rate of male but not female larvae was significantly enhanced (p<0.029). We established a juvenile Drosophila smoke model and observed a sex difference in sensitivity to CSE. In transgenerational studies, we will investigate if epigenetic mechanisms mediate CS-induced alterations in the airway epithelium.