WEDNESDAY, Sept. 1 (HealthDay News) -- Secondhand smoke appears
to trigger a complex inflammatory response in the lungs, a study in
The researchers exposed the animals to secondhand smoke five
times per week for two or four months. The exposures occurred in
two three-hour shifts twice a day, separated by a two-hour
"This is much like what a human would be exposed to at a bar or casino," Adelheid Kratzer, an investigator in the pulmonary and critical care division in the department of medicine at the University of Colorado-Denver, said in an American Physiological Society news release.
Two months of exposure to secondhand smoke was enough to cause
significant changes in the rats' lungs, and those changes were even
more notable after four months.
Among the changes the investigators found were:
- Enlargement in the alveolar air space of the lungs, which
suggests the alveolar structure had started to break down, similar
to the way it does in early emphysema. The alveoli are tiny sacs
where the oxygen-carbon dioxide exchange occurs during
- Increased numbers of white blood cells called macrophages in
the alveolar space, indicating an immune system response.
- Elevated levels of the cytokine interleukin-18, which is
produced by macrophages and is associated with strong inflammatory
responses and tissue destruction.
- Inhibited growth and spread of endothelial cells lining the
inside of small blood vessels of the lungs. A decrease in
endothelial cells can reduce the elasticity of the blood vessel
wall and increase its permeability, which can lead to chronic
inflammation that's seen in patients with chronic obstructive
pulmonary diseases, such as emphysema and chronic bronchitis.
The findings, presented at the American Physiological Society
conference held last week in Westminster, Colo., may help efforts
to develop new ways to treat lung damage caused by secondhand
smoke, the researchers said.
The U.S. Centers for Disease Control and Prevention has more
health effects of secondhand smoke.