Prenatal diet buffers infant epigenetic changes linked to pollution and transient wheeze

Prenatal air pollution exposure is associated with childhood asthma, particularly among biological males. The mechanisms remain unclear, but may involve lasting epigenetic changes, such DNA methylation (DNAm), that occur during gestation in response to oxidative stress and inflammation. Higher maternal intake of "protective" micronutrients, like antioxidants, could buffer pollution-induced oxidative stress and inflammation to mitigate potentially adverse DNAm differences contributing to asthma. Using data from 515 CANDLE participants, we examined associations between prenatal NO2, PM2.5, and PM10 and cord blood DNAm, evaluated DNAm mediation of pollution associations with childhood wheeze phenotypes (transient, persistent, and late-onset), and assessed buffering of DNAm by maternal polyunsaturated fatty acid, vitamin C, or folate intake, and overall diet quality measured by the Alternative Healthy Eating Index-Pregnancy (AHEI-P). We identified 19, seven, and five regional DNAm differences associated NO2, PM2.5, and PM10. Mediation analyses suggested a role for HLA-DPA1/DPB1 DNAm in NO2 and PM2.5 associations with transient wheeze. To assess buffering, we fit pollutant-by-diet interaction models, defining buffering as an interaction opposite in sign to the main pollutant effect. One or more micronutrients or AHEI-P attenuated pollutant effects at 16 of 19 NO2-associated DMRs, including HLA-DPA1/DPB1, and all PM2.5- and PM10-associated DMRs. However, attenuation of HLA-DPA1/DPB1 DNAm did not significantly reduce the indirect effect of NO2 on transient wheeze. In sex-stratified analyses, biological males exhibited lower PM2.5-associated DNAm in SERPINB9, a gene linked to lung function. These findings suggest prenatal air pollution alters DNAm, which may contribute to transient wheeze, with some differences partially buffered by maternal diet. Significance StatementPrenatal air pollution exposure contributes to child wheeze and asthma, potentially through the oxidative stress response and subsequent changes to infant DNA methylomes. Here, we used data from the CANDLE cohort to identify cord blood DNAm differences associated with NO2, PM2.5, or PM10. We examined if any alterations mediated the relationship between prenatal air pollution exposures and transient, persistent, or late-onset wheeze at age 4 to 6 years. Some of these DNAm differences appeared to be at least partially buffered by maternal micronutrients and/or overall diet quality.