Preconceptional smoking alters spermatozoal miRNAs of murine fathers and affects offspring's body weight.

BACKGROUND: Active smoking has been reported among 7% of teenagers worldwide, with ages ranging from 13 to 15 years. An epidemiological study suggested that preconceptional paternal smoking is associated with adolescent obesity in boys. We developed a murine adolescent smoking model before conception to investigate the paternal molecular causes of changes in offspring's phenotype. METHOD: Male and female C57BL/6J mice were exposed to increasing doses of mainstream cigarette smoke (CS) from onset of puberty for 6 weeks and mated with room air (RA) controls. RESULTS: Thirteen miRNAs were upregulated and 32 downregulated in the spermatozoa of CS-exposed fathers, while there were no significant differences in the count and morphological integrity of spermatozoa, as well as the proliferation of spermatogonia between CS- and RA-exposed fathers. Offspring from preconceptional CS-exposed mothers had lower body weights (p = 0.007). Moreover, data from offspring from CS-exposed fathers suggested a potential increase in body weight (p = 0.062). CONCLUSION: We showed that preconceptional paternal CS exposure regulates spermatozoal miRNAs, and possibly influences the body weight of F1 progeny in early life. The regulated miRNAs may modulate transmittable epigenetic changes to offspring, thus influence the development of respiratory- and metabolic-related diseases such as obesity, a mechanism that warrants further studies for elaborate explanations.

Critical age windows in the impact of lifetime smoking exposure on respiratory symptoms and disease among ever smokers.

BACKGROUND: Despite extensive knowledge of smoking effects on respiratory disease, there is no study including all age windows of exposure among ever smokers. The objective of this study was to assess the effects from smoking exposure in utero, early childhood, adolescence and adulthood on respiratory health outcomes in adult male and female ever smokers. METHODS: Respiratory health outcomes were assessed in 10,610 participants of the European Community Respiratory Health Survey (ECRHS) I who reported a history of ever smoking by questionnaire. The associations of maternal smoking in utero, maternal smoking during childhood, age of smoking debut and pack-years of smoking with respiratory symptoms, obstructive diseases and bronchial hyperreactivity were analysed using generalized linear regression, non-linearity between age of smoking debut and outcomes were assessed by Generalized additive mixed models. RESULTS: Respiratory symptoms and asthma were more frequent in adults if their mother smoked during pregnancy, and, in men, also if mother smoked in childhood. Wheeze and ≥3 respiratory symptoms declined with later smoking debut among women [≤10 years: OR = 3.51, 95% CI 1.26, 9.73; 11-12 years: 1.57[1.01-2.44]; 13-15 years: 1.11[0.94-1.32] and ≤10 years: 3.74[1.56-8.83]; 11-12 years: 1.76[1.19-2.56]; 13-15 years: 1.12[0.94-1.35], respectively]. Effects of increasing number of packyears were pronounced in women (Chronic Obstructive Pulmonary Disease (COPD): OR/10 packyears women: 1.33 [1.18, 1.50], men: 1.14 [1.04, 1.26] pinteraction = 0.01). CONCLUSIONS: Among ever smokers, smoking exposure in each stage of the lifespan show persistent harmful effects for adult respiratory health, while women appeared to be more vulnerable to an early age of smoking debut and amount of smoking in adulthood.