6533b830fe1ef96bd12971b3

RESEARCH PRODUCT

Airway inflammation in healthy smokers

subject

description

Cigarette smoking is a risk factor associated with lung cancer and many other neoplasms of various organs, coronary artery disease and numerous vascular disorders, Chronic Obstructive Pulmonary Disease (COPD) and other types of lung diseases [13]. Much work has been done on the in vitro and ex vivo carcinogenetic effects of tobacco smoking while the effects of smoking on innate and adaptive immune function have been studied to a lesser degree. Recent data suggests that cigarette smoke alters the functions of the immune system and increases susceptibility to viral and bacterial infections [4-6]. In the respiratory system along the last years many studies have depicted the changes induced by smoke on various aspects of local immunoregulation and inflammation in patients with various stages of COPD. Less attention has been paid to the changes induced by cigarette smoking on the vast category of individuals defined as “healthy smokers”. This is a population outnumbering COPD patients, as it is estimated that COPD develops in a minority of smokers. “Healthy smokers” data is usually gathered to compare different aspects of airway inflammation with those obtained from patients with COPD with a history of tobacco smoking. The rationale for making this comparison is that the two populations, healthy smokers and COPD patients, were (or are still) exposed to similar burden of tobacco smoke during their life, yet only those who develop a progressive and non reversible airflow limitation over the years may be called patients, as they have COPD. From the COPD point of view this comparison holds its value, as we try to find the “Holy Grail” in the pathogenesis of COPD: the particular aspect or pattern of immunodisregulation that leads to disease only in a fraction of smokers. From the point of view of control individuals who smoke and yet have normal spirometry, this comparison is somehow unfair and may be misleading. They may appear to be healthy, i.e. individuals who do not have all the changes in local inflammation and immunity as seen in COPD patients. Therefore, they may appear as individuals who are in fact healthier than the smokers who develop COPD, as they can cope better than COPD patients with the noxious effects of cigarette smoke. However, when compared with normal individuals who never smoked, the assumption that control smokers are healthy is much less obvious. We believe that in this field a better comprehension of the changes associated and induced by cigarette smoking on the airway inflammation and immunity may help us to redefine, at least from a biological point of view, the real status of “healthy smokers” for these individuals. In the present paper we will review the effects of cigarette smoke on innate and adaptive immune function looking mainly at in vitro data and to the inflammatory changes induced in vivo by cigarette smoke in the bronchial mucosal tissue and bronchoalveolar lavage (BAL) of healthy smokers.