Viruses -and Cigarettes Smoking

Published on August 6, 2008 4:09 AM

Scientists found that flu virus symptoms that are often mild and transient in non-smokers can seriously sicken smokers. They also identified the mechanism by which viruses and cigarette smoke interact to increase lung inflammation and damage.

Until recently, scientists haven't been able to explain why smokers have more exaggerated responses to viral infections. Smokers have been more likely than non-smokers to die during previous influenza epidemics and are more prone to chronic obstructive pulmonary disease (COPD).

Furthermore, children who are exposed to second-hand smoke have more severe responses when infected with respiratory synctial virus (RSV). RSV disease spectrum includes a wide array of respiratory symptoms, from rhinitis and Otitis Media to pneumonia and bronchiolitis, the latter two diseases being associated with substantial morbidity and mortality.

A new study in mice has provided an insight into why viral infections have more severe consequences in individuals exposed to cigarette smoke than in those not exposed to it.

This experiment showed that the immune systems of mice exposed to cigarette smoke from as little as two cigarettes a day for two weeks overreacted when they were also exposed to a mimic of the flu virus. The mice's immune systems cleared the virus normally but the exaggerated inflammation caused increased levels of tissue damage.

The scientists said that the anti-viral responses in the cigarette smoke exposed mice were not only not defective, but were hyperactive. These findings suggest that smokers do not get in trouble because they can't clear or fight off the virus, but they get in trouble because they overreact to it.

The team researchers found that mice with viral infections that had been exposed to cigarette smoke had accelerated emphysema and airway scarring.

Now scientists are sure that they can find the ways for to prevent the destruction of lung tissue and the higher illness and death among smokers.