E-cigarettes compromise the gut barrier and trigger gut inflammation

E-cigarette and vaping device use continue to rise, particularly in adolescents and young adults, but the safety of inhaling the multitude of chemicals within e-cigarette aerosols has been questioned. While several studies have evaluated vaping effects on the lungs and heart; effects on the gastrointestinal tract remain unknown. Using established murine models of acute (1 week) and chronic (3 month) daily e-cigarette aerosol inhalation, both with nicotine-containing and vehicle control e-liquids, murine colon transcriptomics and organoid co-culture models, we assessed the effects of e-cigarette use on the gut barrier and mucosal health. Histologic analyses revealed that chronic exposure to nicotine-free e-cigarette aerosols induced mucosal inflammation. Transcriptome analyses revealed that chronic, but not acute, nicotine-free e-cigarette use significantly reduced expression of tight junction markers, including occluding, and drove expression of pro-inflammatory cytokines. Exposure of murine and human enteroid-derived monolayers (EDMs) to nicotine-free e-cigarette aerosols alone, or in co-culture with invasive E. coli, confirmed that repetitive exposure was sufficient to recapitulate the key findings observed in vivo, i.e., barrier-disruption, downregulation of occludin, inflammation, and an accentuated risk of and response to bacterial infection. These data highlight an unexpected harmful effect of e-cigarette use on the gut barrier and pinpoint non-nicotine chemical components common across >90% of e-cigarette e-liquids as the source of harm. Given the ever-expanding importance of the integrity of the gut barrier for host fitness, and impact of gut mucosal inflammation on a multitude of chronic diseases, these findings are broadly relevant to medicine and public health.