Cigarette smoke-mediated perturbations of the immune response: A new therapeutic approach with natural compounds

Cigarette smoke (CS) accounts for the outcome of several pathologies, even including lung cancer, cardiovascular disease and chronic obstructive pulmonary disease (COPD). Under healthy conditions, lung immune system becomes tolerant in response to various external stimuli. CS exposure alters the pulmonary immune equilibrium, thus leading to a condition of hyper activation of the local innate and adaptive immunity. COPD is one of the major complications of chronic CS exposure where a pro-inflammatory profile of the pulmonary and systemic immunity is predominant. In this review, alternative treatments with natural products to mitigate CS-mediated pulmonary inflammation are proposed. In particular, polyphenols, a class of natural compounds largely present in fruits and vegetables, have been shown to act as anti-inflammatory agents. Accordingly, recent experimental and clinical evidences support polyphenol-mediated potential health benefits in smokers. For instance, pomegranate juice is able to attenuate the damage provoked by CS on cultured human alveolar macrophages. In addition, maqui beery extract has been proven to normalize H2O2 and interleukin-6 levels in exhaled breath condensate in healthy smokers. However, some limitations of alternative treatments are represented by a better knowledge of the mechanism(s) of action exerted by polyphenols and by the lack of animal models of COPD. In any case, the potential targets of polyphenols in the course of COPD will be outlined with special reference to the activation of T regulatory cells as well as to the inhibition of the polymorphonuclear cell and monocyte respiratory burst and of the NF-κB pathway, respectively