Pm2.5 Affects Immune Tolerance Establishment Of New Born Mice By Reducing PD-L1 Expression

OBJECTIVE: This study was to define whether particulate matter 2.5(PM2.5)exposure affects immune tolerance of neonatal mice via regulating PD-L1 expression.METHODS: One-week-old BALB/c mice were exposed to PM2.5 for8 days.From day 8 to day 18,the mice were treated with 5 ?g house dust mite(HDM)(i.n.)every two days.Adenovirus carried PD-L1 overexpression vectors infected into the mice via nasal inhalation 6 days after PM2.5 exposure.Airway hyper-responsiveness(AHR)was examined in mice 19 days after PM2.5 exposure,and the related parameters of airway inflammation were studied on day 22.RESULTS: PM2.5 and HDM co-exposure reduced PD-L1 expression but highly increased inflammatory cells infiltration,which was reversed by PD-L1 overexpression.PM2.5 and HDM co-exposure also elevated serum IL-4,5 and 13 level,reduced TGF-? level.PM2.5 exposure alone slightly increased DCs numbers while reduced numbers of APCs expressing PD-L1 and Treg cells.CONCLUSION: Early PM2.5 exposure reduced PD-L1 expression in the lung of neonatal mice,which interfered the immune tolerance establishment and subsequently resulted in allergic airway inflammation.