Using 18F-NOS PET Imaging to Measure Pulmonary Inflammation in Electronic and Combustible Cigarette Users: A Pilot Study

Electronic cigarette (EC) use has increased dramatically, particularly among adolescents and young adults, which, like cigarette use, can cause inflammation of the lungs and increase the risk of lung disease. MethodsIn this preliminary study, we used positron emission tomography with 18F-6-(1/2)(2-fluoro-propyl)-4-methylpyridin-2-amine (18F-NOS) to quantify inflammation of the lungs in vivo in three age- and sex-matched groups: (1) 5 daily EC users, (2) 5 daily cigarette smokers, and (3) 5 never smoke/vape controls. ResultsEC users showed greater 18F-NOS non-displaceable binding potential (BPND) than cigarette smokers (p = 0.03) and never smoke/vape controls (p = 0.01); whereas BPND in cigarette smokers did not differ from controls (p > 0.1). 18F-NOS lung tissue delivery (K1) and iNOS distribution volume (VT) did not significantly differ between groups. Although there were no group differences in the concentration of the peripheral inflammatory markers TNF-, IL-6 or IL-8, 18F-NOS BPND significantly correlated with the proinflammatory cytokine TNF- (r = 0.87, p = 0.05) in EC users. Additionally, when EC users and cigarette smokers were pooled together, vaping episodes/cigarettes per day correlated with IL-6 levels (r = 0.86, p = 0.006). ConclusionTo our knowledge, this is the first PET imaging study to compare lung inflammation between EC and cigarette users in vivo. We found preliminary evidence EC users had greater pulmonary inflammation than cigarette smokers and never smoke/vape controls, with a positive association between pulmonary and peripheral measures of inflammation.