Air Pollution Could Alter Tags on DNA and Increase Risk for Neurodegenerative Disease

Not only is air pollution a major environmental concern, but it poses major health issues. New research suggests that inhaling extremely small particles known as fine particulate matter could add epigenetic marks to DNA. This may potentially lead to stroke, Alzheimer’s disease, Parkinson’s disease, cognitive impairments and neurodevelopmental disorders.

We’re certainly learning more about how our exposure to environmental toxins, especially pollution, affects the chemical tags that attach to our DNA and our health. Previous studies have linked traffic-related air pollution to an increase in histone acetylation, an epigenetic mark found on histone proteins. Similar research uncovered an association between inhaling diesel exhaust fumes and epigenetic changes that affected around 400 genes.

In a new study published in Toxicology, a team of researchers set out to investigate the role of oxidative stress and DNA hydroxymethylation caused by particulate matter from air pollution, in the development of neurodegenerative disease. 5-hydroxymethylcytosine (5-hmC) is an interesting epigenetic modification and its potential function continues to be explored.

First, they collected actual fine particulate matter from a busy street in Shanghai, China. Then they used a cell culture to administer different doses of the pollution material. As a result of exposing the cells to the pollution, they detected cell cycle arrest, cell apoptosis and cell proliferation inhibition in neuronal cells.

Next, to measure 5-hmC content and investigate the epigenetic impact, the group performed immunofluorescence using a 5-hmC antibody from EpiGentek and found an increase in total 5-hmC. They confirmed the rise in 5-hmC levels using the MethylFlash Hydroxymethylated DNA 5-hmC Quantification Kit (Colorimetric) from EpiGentek.

To look at the epigenetic mark in further detail, they drilled down and investigated the 5-hmC levels in promoter regions of 11 target genes using EpiGentek’s EpiQuik Hydroxymethylated DNA Immunoprecipitation (hMeDIP) Kit. This assay performs antibody-based capture of hydroxymethylated DNA fragments and enabled the team to detect specific levels of the epigenetic tag on certain genes.

The researchers found that exposure to the pollution increased global DNA hydroxymethylation as well as gene-specific DNA hydroxymethylation of neuronal genes. This mark has been shown to be stimulated by oxidative stress and gives us more insight into which environmental toxins may play a role in the development of neurodegenerative disease.

“We revealed that oxidative stress-mediated neurocytotoxicity and abnormal DNA hydroxymethylation were involved in the mechanisms for the neuronal pathology of [fine particulate matter],” the researchers reported.

These results give us insight into the epigenetic impact of pollution and how it might affect neuronal growth and disease. According to the researchers, future directions for addressing the interactions between environmental toxins and epigenetic marks should focus on in vivo animal models or clinical samples.

Source: Wei H. et al. (2017). Role of oxidative stress and DNA hydroxymethylation in the neurotoxicity of fine particulate matter. Toxicology, 380:94-103. doi: 10.1016/j.tox.2017.01.017