Heated tobacco product aerosol exposure induces lung inflammation associated with altered miR-96-5p and FoxO3a expression in mice

Heated tobacco products (HTPs) have recently become increasingly popular among smokers, mainly in Europe and the Western Pacific region, based on the argument that they are healthier alternatives to conventional cigarettes. However, scientific evidence in support of this argument is insufficient. The aim of the present study was to determine the effects of exposure to HTPs aerosol on the lungs of mice. 10-week-old wild-type male mice (C57BL6/JJcl) were exposed to (low- and high-dose) HTPs aerosol. After two months of exposure, bronchoalveolar lavage fluid (BALF) was collected, then the lungs were dissected and processed for histological evaluation. Inflammation was evaluated by a semiquantitative scoring system. We also determined the expression levels of key inflammation-related mRNAs and aryl hydrocarbon receptor (AhR)-regulated microRNAs. Expression levels of proteins targeted by the microRNAs with altered expression are further measured. HTPs aerosol exposure significantly increased the perivascular inflammation score and the expression of the pro-inflammatory cytokine IL-6, while IL-1β numerically increased and IL-10, an anti-inflammatory cytokine, numerically decreased with increasing doses. The exposure also significantly downregulated the expression of miR-96-5p among AhR-regulated microRNAs and upregulated the expression of its target protein, forkhead box O3a (FoxO3a). HTPs aerosol exposure induced lung inflammation associated with altered expression of miR-96-5p and FoxO3a in mice.