New research exposes the epigenetic changes and harmful consequences that can occur as a result of exposure to diesel exhaust fumes. Researchers at the University of British Columbia and Vancouver Coastal Health have found that breathing in diesel exhaust fumes can lead to changes in DNA methylation levels, switching on and off certain genes. Diesel exhaust is given off when an engine burns diesel fuel and, according to the Office of Environmental Health Hazard Assessment, “is a complex mixture of thousands of gases and fine particles (commonly known as soot) that contains more than 40 toxic air contaminants. These include many known or suspected cancer-causing substances, such as benzene, arsenic and formaldehyde.”
In the study published in Particle and Fibre Toxicology, sixteen non-smoking asthmatic individuals volunteered to enter a polycarbonate-enclosed booth and breathe in diluted and aged diesel exhaust fumes. According to the research, the amount they were exposed to is about equivalent to the quality of air along a highway in Beijing or a popular British Columbia port.
The scientists investigated the change in the epigenetic modification known as DNA methylation between two groups – those who were exposed to the diesel exhaust fumes and those who were exposed to only filtered air. Blood samples were initially collected from the participants prior to their exposure and then again 6 and 30 hours post-exposure.
They found that changes in DNA methylation were caused by diesel exhaust exposure. 2,827 different points on their DNA had been differentially methylated, which affected around 400 genes. These genes were involved in protein kinase and NFkB pathways, inflammation and oxidative stress response, repetitive elements, and microRNA. In some areas the exhaust exposure caused hypermethylation and in other areas it led to hypomethylation. Overall, the researchers reported that “CpG sites with significant changes in response to diesel exhaust exposure primarily became less methylated, with a site residing within GSTP1 being among the significant hits.” They also found that changes in DNA methylation as a result of exposure to diesel exhaust were found in “CpG sites overlapping with Alu and LINE1 elements as well as for a site within miR-21.”
These changes demonstrate how sensitive our genetic machinery can be to harmful chemicals, especially air pollution, and that they can occur even without noticeable symptoms.
“Usually when we look at the effects of air pollution, we measure things that are clinically obvious — air flow, blood pressure, heart rhythm,” explained senior author and associate professor in the Division of Respiratory Medicine Dr. Chris Carlsten. “But asthma, higher blood pressure or arrhythmia might just be the gradual accumulation of epigenetic changes. So we’ve revealed a window into how these long-term problems arise. We’re looking at changes ‘deep under the hood.’”
Only two hours of exposure to diesel exhaust fumes was long enough to have an impact on DNA methylation. Dr. Carlsten, who is also the Astra Zeneca Chair in Occupational and Environmental Lung Disease, indicates that this short time frame may have positive implications. He has been working on a national project exploring the effects of environmental factors and epigenetics on lung health.
“Any time you can show something happens that quickly, it means you can probably reverse it — either through a therapy, a change in environment, or even diet,” said Dr. Carlsten.
Dr. Carlsten’s team is now sharing this study’s data – which cataloged the alterations along the entire human genome – with other researchers who are investigating the functions of specific genes.
Source: Learn all about it and read more about their findings here: Ruiwei Jiang, Meaghan J Jones, Francesco Sava, Michael S Kobor, Christopher Carlsten. Short-term diesel exhaust inhalation in a controlled human crossover study is associated with changes in DNA methylation of circulating mononuclear cells in asthmatics. Particle and Fibre Toxicology, 2014; 11 (1) DOI: 10.1186/s12989-014-0071-3
References: Breathing in Diesel Exhaust Leads to Changes “Deep Under the Hood”. The University of British Columbia. 2015.