Effect of tobacco smoke and nicotine on immune response in tuberculosis infection and other lung diseases

The problem of smoking, as well as incidence of tuberculosis, has existed for a long time. The latest WHO data indicate that 1.3 million people die from tuberculosis, and another 7 millions die from smoking every year. Tobacco smoke contains many harmful chemicals, including carbon monoxide, nicotine, nitrogen oxides, and cadmium. A number of studies indicate a high prevalence of smoking among patients with tuberculosis. In most cases, infection with Mycobacterium tuberculosis does not lead to active disease, due to the development of a balanced, homeostatic immune response. The key protective components are inflammatory responses aimed at inhibition of the pathogen growth, its sequestration and final elimination. At the same time, excessive or inadequate immune response may lead to granuloma destruction, tissue damage and, as a result, prolonged duration of treatment due to decreased respiratory function of the lungs. Along with pro-inflammatory mediators, anti-inflammatory mediators are synthesized in the host organism, which can positively or negatively affect the course of disease, depending on the place and time of their production. The balance between pro-and anti-inflammatory mediators in terms of time and expression level plays a crucial role in determining the outcome of infection. In our review, we consider the impact of tobacco smoke on various components of the human immune system, as well as upon the course and outcome of tuberculosis and other lung diseases. In addition, we would like to draw the reader’s attention to the need of adjusting pathogenetic therapy of bronchopulmonary diseases, taking into account the patient’s smoking habits. Tobacco smoking is one of the main causes of the severe course of many infectious and non-infectious diseases of the bronchopulmonary system. The decay products of cigarette smoke disrupt the functioning of the ciliated epithelium of respiratory tract, the production of the mucous component in the bronchi, and reduce the effectiveness of the surfactant system. These negative events interfere with protective mechanisms of the human respiratory system. It is worth of note that tobacco smoke also exerts a systemic effect on the immune system. Data are accumulating on the association between the terms of exposure to tobacco smoke, and a range of adverse tunerculosis manifestations, such as extent of infection, severity of course, reactivation, treatment outcome, and mortality. At the same time, epidemiological studies are able to reveal the associations, but they do not allow us to determine exact causal relationships.