Effect of Pre- and Postnatal Exposure to urban PM2.5 on the Transcriptome of the Developing and Early-Life Mouse Lung

Over the last years, evidence has grown that exposure to air pollution, in addition to impairing lung function and health in individuals of all age, can be linked to negative effects in newborn when present during pregnancy. Data suggests that intrauterine exposure of fetuses (exposure of the mother to air pollution during pregnancy) in fact exerts a negative impact on lung development. However, the means by which exposure during pregnancy affects lung development, have not been studied in depth yet. In this study, we investigated alterations of the transcriptome of the developing lung in a mouse model of gestational and early-life postnatal exposure to urban PM2.5 (from Sao Paulo, Brazil). Pregnant BALB/c mouse dams were randomly assigned to two study groups: one group exposed to a PM2.5 dose equivalent to 600µg/m3 for 1h daily (exposed group), the other group kept in filtered air during the whole study period (control group). Exposure to PM2.5 was started on embryonic day 5.5 (E5.5, time of placental implantation), dams from both groups were sacrificed and fetus lungs submitted to transcriptomic analysis at E14.5 (pseudoglandular stage of lung development, n=4 per group) and E18.5 (saccular stage, n=4 per group). The offspring of mice that carried out the whole pregnancy was furthermore exposed (and kept in filtered air, repectively) after birth until being sacrificed on the 40th day of life (P40, state of finished lung alveolarization, n=5 per group). This study included no cross-over, i.e. the offspring of PM2.5-expsosed dams was exposed until P40 alike and vice-versa.