PM2.5 exposure and cold stress exacerbates asthma in mice by increasing histone acetylation in IL-4 gene promoter in CD4+ T cells

Asthma is a common chronic inflammatory disease which severely reduces the quality of life in patients. Studies have demonstrated that both PM2.5 and cold stress contribute to the development of asthma. However, the combined effects of these two risking factors are unknown. In this study, we investigated the combined effects of PM2.5 exposure and cold stress (PMCS) on asthma, as well as the underlying mechanisms by using a murine model. After different exposures, the immune-pathological changes and redox states in groups were evaluated. Besides, the balance of T(H)1/T(H)2 cells and the acetylation levels of H3K9 and H3K14 in IL-4 gene promotor were detected. Our results showed that, compared with other exposures, PMCS led to an increased inflammation and redox levels in mice. It also significantly increased the percentage of T(H)2 T cells, which was correlated with hyperacetylation of H3K9 and H3K14 in IL-4 gene promoter in CD4(+)T cells. Furthermore, a significantly increased P300 and decreased HDAC1 were detected in CD4 + T cells in PMCS group. In conclusion, our findings demonstrated that PMCS exacerbated asthma in mice by increasing H3K9 and H3K14 acetylation in IL-4 gene promoter in CD4 + T cells, and P300 and HDAC1 might contribute to their combined effects.