One
of the most widely prescribed drugs in the United States may have an extra
benefit: protecting people from air pollution.
Statins,
prescribed to lower cholesterol and reduce risks of heart attacks and strokes,
seem to diminish inflammation that occurs after people breathe airborne
particles.
“Health
impacts from spikes in particulates in the air are substantial. Statins seem to
protect not only lungs from these impacts but the heart, too,” said Dr. Norman
Edelman, the American Lung Association's senior medical advisor.
About
one in four Americans over the age of 45 takes statins, including Lipitor,
Zocor and other brand names.
Although
drugs cannot be prescribed to protect people from air pollution, several
studies show that people who take statins have fewer proteins in their blood
that indicate inflammation of tissues, said Dr. Stephan van Eeden, an associate
professor at the University of British Columbia who specializes in lung health.
This inflammation may aggravate respiratory and cardiovascular diseases.
Most
recently, a study of 1,923
U.S. women found that those taking statins are less likely to
have signs of inflammation, said Bart Ostro, an epidemiologist with
California’s Office of Environmental Health Hazard Assessment who led the
study.
“There
are some specific groups [such as diabetics] that seem to have higher levels of
inflammation after long-term exposure,” Ostro said. “On the converse side, we
found that people on statins seem to be protected from the inflammatory effects
of PM2.5.”
In
the women taking statins, there was no association between PM2.5 – the tiny
particles emitted mostly by burning diesel and other fossil
fuels – and the proteins indicating inflammation, while for most of
the other groups the links were quite strong.
It’s
not the first time researchers have noticed this link: University of Michigan
researchers found decreased blood indicators of inflammation in people who took
statins in a study of
92 people in Boston. A national study of
5,778 people also reported that statins canceled out the presence of signs of
inflammation from PM2.5, carbon monoxide and nitrogen dioxide.
Scientists
believe that inflammation is a key factor in heart disease.
“The
older thinking was that plaque in coronary arteries caused heart attacks,”
Edelman said. “Now the thinking is that it’s also due to some living tissue
under plague that gets inflamed and that disrupts the plaque. We already knew
statins ameliorate heart disease, and always thought it was through lipids, but
here’s a new pathway.”
Around
the world, studies have shown that whenever particulates increase, deaths from
heart attacks and respiratory disease rise, too. Experts estimate that
fine particles are linked to about 800,000 deaths annually worldwide.
Particulate
pollution has been on a steady decline in the United States: The national
average for PM2.5 decreased 34 percent from 2000 to 2013, according to the
Environmental Protection Agency. However, high concentrations of the pollution
still persist in some cities with heavy traffic and industry, such as Los
Angeles and Chicago.
When
van Eeden and colleagues gave statins to rabbits before
exposing them to particulate matter they had decreased lung inflammation. In a second study of
rabbits, statins seemed to help clear large particles from the lungs by
promoting the movement of white blood cells to nearby lymph nodes, which
protects the lungs against pending inflammation.
“It’s
clear that if the animals are treated for about a month with statins before
they’re exposed to particles, you can significantly lower the amount of particles
generated in the lungs and decrease the blood vessel inflammatory process,” van
Eeden said.
It’s
not clear how statins may cause fewer particles in the lungs, but van Eeden
said statin-treated rabbits have more particles in lymph nodes, suggesting the
drugs stimulate particles to move to the nodes.
In another animal test mice
given Zocor prior to oil fly ash or particulate exposure did not experience
lung injuries and inflammation like their non-treated counterparts did,
according to a 2011 study in Argentina.
Van
Eeden and colleagues are now trying to figure out if the animal findings hold
true for human lungs. So far, their work looks “very promising,” he said.
His
lab is examining lung tissue from people who had part of a lung removed. Many
were smokers and had a lot of particles in their lungs. They haven’t finished
the study but so far they’re seeing that “it’s quite clear that people who used
statins had less particles in their lungs,” van Eeden said.
“Once
again it suggests anti-inflammatory properties and seems to clear the
particles,” van Eeden said. “And these were people chronically exposed to air
pollution or cigarette smoke.”
However,
it’s too early for doctors to prescribe statins for people exposed to air
pollution, said Dr. Martha Daviglus, a cardiovascular epidemiologist at
Northwestern University and University of Illinois.
“We
need more evidence. We already have a lot of people taking statins for
cholesterol, and we don’t fully know the effect of taking the drugs for years
and years, and decades yet,” Daviglus said.
The
number of people taking the drugs is already expected to rise as
the American Heart Association last year advocated for increased statin use to
combat high cholesterol.
It
remains unclear if people would have to take statins immediately prior to
breathing air pollution, and, if so, for how long, in order for the drugs to
help.
“It
seems they have some good effects with regards to air pollution, but we need to
conduct clinical trials with people living near roads or high-emitting
facilities,” Daviglus said.
Ostro
said it would be “somewhat of a leap” to prescribe statins to mitigate air
pollution impacts, given some of their known side effects, such as liver
problems.
Food
and Drug Administration spokesman Kristofer Baumgartner said that any new
claims about additional benefits for a drug have to be reviewed by a team of
scientists, and the benefit would have to outweigh any risks.
Two
pharmaceutical giants who sell statins, Pfizer and AstraZeneca, would not
comment on the air pollution studies.
There
is no research on whether other anti-inflammatory drugs, such as ibuprofen,
would also protect people from air pollution.
Van
Eeden sees potential for statins to play a role in reducing effects of air
pollution, possibly in the near future. One possible group could be those
suffering from asthma, which causes inflamed and constricted air passages.
“If
this human study confirms what we found in rabbits, then if there is an episode
of air pollution, maybe people at high risk can get a short course of statins
for that period until the air pollution clears,” he said. He is currently
seeking funding to test statins on firefighters to see if they reduce lung
inflammation caused by smoke.
Edelman
said the answer to protecting people is still cleaning the air.
“We
don’t want people to start thinking now we have a drug to control effects of
air pollution so we don’t have to worry about air pollution,” he said. “It’s
still a large threat.”
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For
questions or feedback about this piece, contact Editor in Chief Marla Cone at mcone@ehn.org.
