Effect of smoking cessation on chronic waterpipe smoke inhalation-induced airway hyperresponsiveness, inflammation and oxidative stress

Waterpipe smoking (WPS) prevalence is increasing globally. Clinical and laboratory investigations reported that WPS triggers impairment of pulmonary function, inflammation and oxidative stress. However, little is known if smoking cessation (SC) would reverse the adverse pulmonary effects induced by WPS. Therefore, we evaluated the impact of WPS inhalation for 3 months followed by 3 months of SC (air exposure) compared with those exposed for either 3 or 6 months to WPS or air (control) in C57BL/6 mice. To this end, various physiological, biochemical and histological endpoints were evaluated in the lung tissue. Exposure to WPS caused focal areas of dilated alveolar spaces, foci of widening of interalveolar spaces with peribronchiolar moderate mixed inflammatory cells consisting of lymphocytes, macrophages and neutrophil polymorphs. The latter effects were mitigated by SC. Likewise, SC reversed the increase of airway resistance, and reduced the increase in the levels of myeloperoxidase, matrix metallopeptidase 9, granulocyte-macrophage colony-stimulating factor, tumor necrosis factor α, inteleukin (IL)-6 and IL-1β in lung tissue induced by WPS. In addition, SC attenuated the increase of oxidative stress markers including 8-isoprostane, glutathione and catalase induced by WPS. Similarly, DNA damage, apoptosis and the expression of NFκ-β in lung induced by WPS inhalation were alleviated by CS. In conclusion, our data demonstrated, for the first time, that SC mitigated WPS inhalation induced increase in airway resistance, inflammation, oxidative stress, DNA injury and apoptosis, illustrating the benefits of SC on lung physiology.