Tobacco use is the main cause of chronic obstructive pulmonary disease (COPD), showed a lot of studies. COPD is a group of diseases of the lungs in which the airways become narrowed. This leads to a limitation of the flow of air to and from the lungs causing shortness of breath. In contrast to asthma, the limitation of airflow is poorly reversible and usually gets progressively worse over time.
COPD is caused by noxious particles or gases, most commonly from smoking, which triggers an abnormal inflammatory response in the lung. In the United States, 80 to 90% of cases of COPD are due to smoking. Not all smokers will develop COPD, but regular smokers have at least a 25% risk after 25 years. The likelihood of developing COPD increases with increasing age as the cumulative smoke exposure increases. Inhaling the smoke from other peoples' cigarettes can lead to impaired lung growth and could be a cause of COPD too.
But cigarette smoking also may change the body’s immune responses to bacteria that commonly cause exacerbations of the disease, according to a new research.
Martin Stämpfli, Ph.D., an associate professor at McMaster University, said: "It is well established that smoking is the main risk factor for COPD. But our research also suggests that cigarette smoke substantially changes the immune response to bacteria, which means that patients with COPD who smoke are weakening their body’s ability to deal effectively with bacterial invaders. This may cause even further progression of the disease.
Researchers continued to study the effects of cigarette smoking for to see whether and how cigarette smoke would change the inflammatory response to the bacteria that is the culprit behind many COPD exacerbations.

Researchers tested the effects of cigarette smoke exposure on inflammation and immune response in mice that were exposed to cigarette smoke twice daily five days a week for either eight weeks or four days then challenged with an intranasal vaccination of NTHI. Control mice were not exposed to cigarette smoke, but were inoculated with NTHI as were the cigarette smoke-exposed mice.

The researchers found that mice that were exposed to cigarette smoke, whether for four days or for eight weeks, showed distinct moves in their immune-response profile, namely an increase in inflammation of the lungs after the NTHI challenge, increased weight-loss in response to the bacterial infection.