Associations between time-weighted personal air pollution exposure and amino acid metabolism in healthy adults
Environmental exposure has a huge impact on human health and disease. Air pollution is thought to disrupt amino acid metabolism, in turn affecting cardiopulmonary health. Varying exposure times make it difficult to compare results of different studies and hamper the elucidation of molecular mechanisms. In addition, response to air pollution may be transient, which means well-defined exposure times are necessary when looking for associations between amino acids and the grade of air pollution.
A study led by Prof. Gong from Peking University in China used targeted metabolomics to explore this question. Time-weighted personal exposures to air pollutants O3, PM2.5, NO2, and SO2 were calculated over four defined time windows of 12h, 24h, 1 week, and 2 weeks. They hypothesized a correlation between these well-defined exposures and the plasma amino acid levels of their study participants.
While NO2 and SO2 exposure showed little evidence for associations, the alterations in plasma amino acids were more significantly mediated by O3 and PM2.5 exposure. The effects of increasing levels of O3 and PM2.5 showed opposing directions for several metabolites, suggesting alterations of amino acid metabolism in different pathways. Increasing O3 concentration at the 12h and 24h window was significantly associated with higher levels of urea cycle metabolites aspartate, glutamate, and ornithine.
PM2.5 concentrations showed significant correlations with increased levels of asparagine and glutamine related to the 12h and 24h time windows. Notably, most of these associations attenuated with longer exposure times, indicating a short-term perturbation of amino acid metabolism by O3 and PM2.5. The exposure to PM2.5 and O3 showed opposing effects on taurine levels, suggesting the deregulation of amino acid metabolism by oxidative stress.
These results highlight the importance of selecting clearly defined exposure times and concentrations for the investigation of air pollution effects on human metabolism. The insight into the mechanism of amino acid perturbations by air pollution might help to prevent and to treat cardiopulmonary diseases.
Hu et al. Associations between time-weighted personal air pollution exposure and amino acid metabolism in healthy adults. (2021) Environ Int | https://doi.org/10.1016/j.envint.2021.106623