Occupational exposure to particles and mitochondrial DNA - relevance for blood pressure

• Published in: Environmental health Vol. 16; no. 1; p. 22
• Main Authors: Xu, Yiyi, Li, Huiqi, Hedmer, Maria, Hossain, Mohammad Bakhtiar, Tinnerberg, Håkan, Broberg, Karin, Albin, Maria
• Format: Journal Article
• Language: English
• Published: London BioMed Central 09.03.2017; BioMed Central Ltd
• Subjects: Adult; Air Pollutants, Occupational - adverse effects; Air Pollutants, Occupational - analysis; Analysis; Arbetsmedicin och miljömedicin; Biomarkers; Bisulfite; Blood pressure; Blood Pressure - drug effects; Cardiovascular diseases; Copy number; Deoxyribonucleic acid; DNA; DNA Copy Number Variations - drug effects; DNA methylation; DNA Methylation - drug effects; DNA, Mitochondrial - drug effects; DNA, Mitochondrial - genetics; Dust; Dust - analysis; Earth and Environmental Science; Environment; Environmental Epidemiology; Environmental Health; Environmental Monitoring; Exposure; Fumes; Health risk assessment; Health Sciences; Humans; Hälsovetenskap; Inhalation Exposure - adverse effects; Inhalation Exposure - analysis; Male; Medical and Health Sciences; Medicin och hälsovetenskap; Middle Aged; Mitochondrial DNA; Occupational exposure; Occupational Exposure - adverse effects; Occupational Exposure - analysis; Occupational health; Occupational Health and Environmental Health; Occupational health and safety; Occupational Medicine/Industrial Medicine; Oxidative stress; Particles; Polymerase chain reaction; Public Health; Risk factors; Sampling; Smoking; Statistical analysis; Sweden; tRNA; Welding; Welding fumes; Welding machines; Young Adult; Sweden; ANE, Sweden; Particle; DNA methylation; Mitochondria; Blood pressure; Copy number
• ISSN: 1476-069X; 1476-069X
• DOI: 10.1186/s12940-017-0234-4

Background Particle exposure is a risk factor for cardiovascular diseases. Mitochondrial DNA (mtDNA) is a primary target for oxidative stress generated by particle exposure. We aimed to elucidate the effects of occupational exposure to particle-containing welding fumes on different biomarkers of mtDNA function, and in turn, explore if they modify the association between particle exposure and cardiovascular response, measured as blood pressure. Methods We investigated 101 welders and 127 controls (all non-smoking males) from southern Sweden. Personal sampling of the welders’ exposure to respirable dust was performed during work hours (average sampling time: 6.8 h; range: 2.4-8.6 h) and blood pressure was measured once for each subject. We measured relative mtDNA copy number by quantitative PCR and methylation of the mitochondrial regulatory region D-loop and the tRNA encoding gene MT-TF by bisulfite-pyrosequencing. We calculated the relative number of unmethylated D-loop and MT-TF as markers of mtDNA function to explore the modification of mtDNA on the association between particle exposure and blood pressure. General linear models were used for statistical analyses. Results Welders had higher mtDNA copy number (β = 0.11, p  = 0.003) and lower DNA methylation of D-loop (β = −1.4, p  = 0.002) and MT-TF (β = −1.5, p  = 0.004) than controls. Higher mtDNA copy number was weakly associated with higher personal respirable dust exposure among welders with exposure level above 0.7 mg/m 3 (β = 0.037, p  = 0.054). MtDNA function modified the effect of welding fumes on blood pressure: welders with low mtDNA function had higher blood pressure than controls, while no such difference was found in the group with high mtDNA function. Conclusion Increased mtDNA copy number and decreased D-loop and MT-TF methylation were associated with particle-containing welding fumes exposure, indicating exposure-related oxidative stress. The modification of mtDNA function on exposure-associated increase in blood pressure may represent a mitochondria-environment interaction.