The Aggravation of PM_2.5 on Asthma Mediated by Histone Deacetylase

Objective To investigate whether the asthma in rats aggravated by PM_2.5 was mediated by histone acetylation pathway.

Methods Forty-five male Sprague-Dawley rats were randomly divided into five groups:one normal saline group, one asthma group (stimulated by OVA) and three PM_2.5 asthma groups (stimulated by low, medium and high doses of PM_2.5 and OVA). The levels of HDAC1 and HDAC2 mRNA and protein were detected by qRT-PCR and Western blot respectively. The levels of H3K9 and H3K18 were measured by ELISA and immunohistochemistry.

Results The level of HDAC2 mRNA in medium and high dose PM_2.5 asthma groups, the expression of HDAC1 protein in medium dose PM_2.5 asthma group and the expression of HDAC2 protein in high dose PM_2.5 asthma group were lower than that in asthma group (P < 0.05). The level of H3K9ac in low, medium and high dose PM_2.5 asthma group were higher than that in asthma group, the level of H3K18ac in high dose PM_2.5 asthma group was higher than that in asthma group and low and medium dose PM_2.5 asthma groups (P < 0.05). The expression of H3K9ac, H3K18ac protein was mainly concentrated in bronchial epithelial cells, and the expression in asthma group was higher than that in saline control group (P < 0.05); the expression in medium and high dose PM_2.5 asthma groups was higher than that in asthma group (P < 0.05).

Conclusion By means of decreasing the expression of HDAC2 gene and HDAC1 and HDAC2 protein, PM_2.5 might increase the acetylation of histone H3K9 and H3K18, thus aggravate asthma in rats.