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Just two hours of exposure to diesel exhaust fumes
can lead to fundamental health-related changes in
biology by switching some genes on, while switching
others off, according to researchers at the
University of British Columbia and Vancouver Coastal
Health.
The study involved putting volunteers in a
polycarbonate-enclosed booth — about the size of a
standard bathroom — while breathing in diluted and
aged exhaust fumes that are about equal to the air
quality along a Beijing highway, or under certain
conditions at busy ports, rail yards, mines and
industrial sites.
A student participates in the study while seated in
a booth.
"The researchers examined how such exposure
affected the chemical “coating” that attaches to
many parts of a person’s DNA.
That carbon-hydrogen coating, called methylation,
can silence or dampen a gene, preventing it from
producing a protein – sometimes to a person’s
benefit, sometimes not. Methylation is one of
several mechanisms for controlling gene expression,
which is the focus of a rapidly growing field of
study called epigenetics.
The study, published this month in Particle and
Fibre Toxicology, found that diesel exhaust caused
changes in methylation at about 2,800 different
points on people’s DNA, affecting about 400 genes.
In some places it led to more methylation; in more
cases, it decreased methylation.
How these changes in gene expression translate to
health is the next step for researchers. But this
study shows how vulnerable our genetic machinery can
be to air pollution, and that changes are taking
place even if there are no obvious symptoms.
“Usually when we look at the effects of air
pollution, we measure things that are clinically
obvious – air flow, blood pressure, heart rhythm,”
said senior author Dr. Chris Carlsten, an associate
professor in the Division of Respiratory Medicine.
“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.’”
Carlsten’s team, having catalogued the changes along
the entire human genome, is now sharing its data
with scientists who are further exploring the
function of specific genes.
For more information
Particle and Fibre Toxicology
Short-term diesel exhaust inhalation in a controlled
human crossover study is associated with changes in
DNA methylation of circulating mononuclear cells in
asthmatics
The
University of British Columbia
MDN |