A 12-week aerobic training program in an urban environment: effect on blood gene expression profiles and subclinical inflammatory markers

Abstract

Background Exposure to particulate matter (PM) air pollution is known to contribute to inflammatory processes in humans. Aerobic exercise increases the ventilation rate, hence also the exposure to PM. Aims We investigated the impact of PM exposure during a 12-week aerobic training program on healthy volunteers by analyzing subclinical parameters at the start and at the end of the program. Methods One group (n=15) trained in an urban environment, whereas the second group (n=9) trained in a rural environment. Ultrafine Particle (UFP) concentrations were measured during each training session. Differential leukocyte counts, exhaled NO (eNO) and blood transcriptomics profiles were determined. Results Urban UFP concentrations were higher (p = 0.003) than in the rural environment. Leukocyte count (p = 0.022), neutrophil count (p = 0.04), and exhaled nitric oxide (p = 0.003) increased significantly in the urban group at the end of the program, and not in the rural group. A total of 816 genes were altered in expression (multiplicity corrected p-value<0.05 and absolute fold change > 1.5) in the urban group (399 upregulated genes, 417 downregulated genes), and 709 genes showed differential expression (665 upregulated genes, 44 downregulated genes) in the rural group. The expressions of 254 genes were altered in both groups. Gene Ontology analysis associated 55 genes to stress response. For example, an upregulation of interleukin 1 beta, superoxide dismutase and toll-like receptor 4 was observed in both groups. The analysis also revealed an interaction effect for 246 genes. Thirty nine genes were upregulated and two hundred and seven genes were downregulated when the urban group was compared to the rural group. This indicates that gene expression signals were changed depending on the location where the participants were exercising. Conclusions Our study has revealed that subclinical measurements and blood molecular patterns are significantly affected when healthy individuals exercising in an urban environment are compared to a rural environment.