E-cigarette use causes a unique innate immune response in the lung, involving increased neutrophilic activation and altered mucin secretion

Rationale: E-cigarettes have become increasingly popular and little is known about their potential adverse health effects.Objectives: To determine the effects of e-cigarette use on the airways.Methods: Induced sputum samples from cigarette smokers, e-cigarette users, and nonsmokers were analyzed by quantitative proteomics, and the total and individual concentrations of mucins MUC5AC and MUC5B were determined by light scattering/refractometry and labeled mass spectrometry, respectively. Neutrophil extracellular trap (NET) formation rates were also determined for the same groups.Measurements and Main Results: E-cigarette users exhibited significant increases in aldehyde-detoxification and oxidative stress–related proteins associated with cigarette smoke compared with nonsmokers. The levels of innate defense proteins associated with chronic obstructive pulmonary disease, such as elastase and matrix metalloproteinase-9, were significantly elevated in e-cigarette users as well. E-cigarette users’ sputum also u...