Fine Paniculate Matter Constituents, Nitric Oxide Synthase DNA Methylation and Exhaled Nitric Oxide

摘要

It remains unknown how fine participate matter (PM_(2.5)) constituents affect differently the fractional concentration of exhaled nitric oxide (FeNO, a biomarker of airway inflammation) and the DNA methylation of its encoding gene (NOS2A). We aimed to investigate the short-term effects of PM_(2.5) constituents on NOS2A methylation and FeNO. We designed a longitudinal study among chronic obstructive pulmonary disease (COPD) patients with six repeated health measurements in Shanghai, China. We applied linear mixed-effect models to evaluate the associations. We observed that the inverse association between PM_(2.5) and methylation at position 1 was limited within 24 h, and the positive association between PM_(2.5) and FeNO was the strongest at lag 1 day. Organic carbon, element carbon, NO_3~- and NH_4~+ were robustly and significantly associated with decreased methylation and elevated FeNO. An interquartile range increase in total PM_(2.5) and the four constituents was associated with decreases of 1.19, 1.63, 1.62, 1.17, and 1.14 in percent methylation of NOS2A, respectively, and increases of 13.30%, 16.93%, 8.97%, 18.26%, and 11.42% in FeNO, respectively. Our results indicated that organic carbon, element carbon, NO_3~- and NH_4~+ might be mainly responsible for the effects of PM_(2.5) on the decreased NOS2A DNA methylation and elevated FeNO in COPD patients.