The Effect Of In Utero Exposure To Ambient PM_2.5 On Asthma In Rats

2.1Objective The present study aimed to investigate the effects and possible mechanisms of maternal exposure to ambient PM2.5 in Fuzhou during preganacy and on filial respiratory system development induced by ovalbumin.2.2Methods SD rats on the first gestation day were randomly divided into eight groups(n=6 per group): filtered air prenatal exposure plus normal saline(FA pre-NS); filtered air prenatal exposure plus ovalbumin(FA pre-OVA); filtered air postnatal exposure plus normal saline(FA post-NS); filtered air prenatal exposure plus ovalbumin(FA postOVA); PM2.5 prenatal exposure plus NS(PM2.5 pre-NS);PM2.5 prenatal exposure plus ovalbumin(PM2.5 pre-OVA); PM2.5 postnatal exposure plus NS(PM2.5 post-NS);and PM2.5 prenatal exposure plus ovalbumin(PM2.5 post-OVA). Groups PM2.5 post –NS and PM2.5 post –OVA feed in animal laboratory first, Groups PM2.5 pre-NS and PM2.5 pre-OVA were exposed to environmentally relevant PM2.5 in Fuzhou General Hospital throughout the entire pregnancy and lactation period in a "real-world" airborne PM exposure system, while groups FA-NS and FA-HCY were exposed to filtered air. Their offspring were sensitized on postnatal days(PDs) 9 and 15 by intraperitoneal injection of 0.5μg OVA plus 200μg aluminum hydroxide in 20μL PBS buffer. On PNDs 24, 25 and 26, live pups received an airway challenge of OVA for 30 min to establish an animal model of asthma.2.3Results2.3.1 Both PM2.5 pre-exposure and OVA treatment were effective in increasing the levels of IL-4、IL-5(P<0.05) in plasma of young rats.2.3.2 PM2.5 exposure was effective in lowing the concentrations of IFN-γ(P<0.05)in plasma of young rats. Single PM2.5 pre-exposure or OVA treatment or the bothwere effective in increasing the levels of GATA-3 and lowing the concentrations of T-bet in the lung tissue of young rats.2.3.3 Both PM2.5 pre-exposure and OVA treatment were effective in increasing the levels of Micro RNA-146 a and Micro RNA-146b(P<0.05)in the spleen tissue of young rats. There was an interaction in complex intervention in increasing the levels of Micro RNA-146a(P<0.05), however, that was no such effect in Micro RNA-146b(P>0.05).All the results in PM2.5 post-exposure groups were not obviously as well as pre-exposure groups.2.4Conclusions2.4.1 The atmosphere quality of Fuzhou has inflammatory reaction on lung tissue of young rats, moreover, it affects adversely on asthma induced by OVA. Suggesting that PM2.5 pre-exposure may has adverse effects on young rats of asthma.2.4.2 PM2.5 pre-exposure or OVA treatment was effective in increasing the levels of GATA-3 and lowing the concentrations of T-bet in the lung tissue of young rats, Th2 cytokines, ie, IL-4, IL-5 were increased and Th1 cytokines of IFN-γ lowered in plasma correspondly, Suggesting that immune-inflammatory response maybe one of the mechanisms by which PM2.5 affects adversely on young rats asthma induced by OVA. Micro RNA-146 a and Micro RNA-146 b increased in the spleen tissue suggesting that epigenetics may be involved in the effect on young rats asthma.