Dust fall PM2.5-induced lung inflammation in rats is associated with hypermethylation of the IFN-γ gene promoter via the PI3K-Akt-DNMT3b pathway

Abstract

Inflammation is one of the major adverse effects of fine particulate matter (PM2.5) on the lung system; however, its mechanisms remain unclear. Rats were exposed to different concentrations of PM2.5 to investigate the mechanism of short-term exposure-induced lung inflammation. The regulation of PI3K-Akt and DNA methyltransferase 3b (DNMT3b) was assessed by using a PI3K inhibitor and a DNA methyltransferase inhibitor. We found that PM2.5 could decrease interferon-γ (IFN-γ) levels and increase interleukin 4 (IL-4), IL-5 and IL-13 levels in bronchoalveolar lavage fluid (BALF) to promote eosinophil infiltration and eventually lead to allergic pulmonary inflammation. Moreover, the CpG island methylation rate of the IFN-γ promoter and the protein expression of DNMT3b, PI3K and p-Akt were increased in lung tissues after PM2.5 exposure. Both inhibitors reversed the CpG island hypermethylation of IFN-γ. In conclusion, in PM2.5-induced lung injury, the activated PI3K-Akt pathway, via an increase in DNMT3b expression, is involved in CpG hypermethylation of the IFN-γ gene promoter.