Cell-specific toxicity of short-term JUUL aerosol exposure to human bronchial epithelial cells and murine macrophages exposed at the air-liquid interface

Respir Res. 2020 Oct 17;21(1):269. doi: 10.1186/s12931-020-01539-1.


Backgroud: JUUL, an electronic nicotine delivery system (ENDS), which first appeared on the US market in 2015, controled more than 75% of the US ENDS sales in 2018. JUUL-type devices are currently the most commonly used form of ENDS among youth in the US. In contrast to free-base nicotine contained in cigarettes and other ENDS, JUUL contains high levels of nicotine salt (35 or 59 mg/mL), whose cellular and molecular effects on lung cells are largely unknown. In the present study, we evaluated the in vitro toxicity of JUUL crème brûlée-flavored aerosols on 2 types of human bronchial epithelial cell lines (BEAS-2B, H292) and a murine macrophage cell line (RAW 264.7).

Methods: Human lung epithelial cells and murine macrophages were exposed to JUUL crème brûlée-flavored aerosols at the air-liquid interface (ALI) for 1-h followed by a 24-h recovery period. Membrane integrity, cytotoxicity, extracellular release of nitrogen species and reactive oxygen species, cellular morphology and gene expression were assessed.

Results: Crème brûlée-flavored aerosol contained elevated concentrations of benzoic acid (86.9 μg/puff), a well-established respiratory irritant. In BEAS-2B cells, crème brûlée-flavored aerosol decreased cell viability (≥ 50%) and increased nitric oxide (NO) production (≥ 30%), as well as iNOS gene expression. Crème brûlée-flavored aerosol did not affect the viability of either H292 cells or RAW macrophages, but increased the production of reactive oxygen species (ROS) by ≥ 20% in both cell types. While crème brûlée-flavored aerosol did not alter NO levels in H292 cells, RAW macrophages exposed to crème brûlée-flavored aerosol displayed decreased NO (≥ 50%) and down-regulation of the iNOS gene, possibly due to increased ROS. Additionally, crème brûlée-flavored aerosol dysregulated the expression of several genes related to biotransformation, inflammation and airway remodeling, including CYP1A1, IL-6, and MMP12 in all 3 cell lines.

Conclusion: Our results indicate that crème brûlée-flavored aerosol causes cell-specific toxicity to lung cells. This study contributes to providing scientific evidence towards regulation of nicotine salt-based products.

Keywords: Air–liquid interface (ALI); Electronic nicotine delivery system (ENDS); Electronic-cigarettes; JUUL; Vaping.

MeSH terms

  • Aerosols / administration & dosage
  • Aerosols / toxicity*
  • Animals
  • Cell Line
  • Cell Survival / drug effects
  • Cell Survival / physiology
  • Electronic Nicotine Delivery Systems*
  • Flavoring Agents / administration & dosage
  • Flavoring Agents / toxicity*
  • Humans
  • Macrophages / drug effects*
  • Macrophages / metabolism
  • Mice
  • RAW 264.7 Cells
  • Respiratory Mucosa / cytology
  • Respiratory Mucosa / drug effects*
  • Respiratory Mucosa / metabolism
  • Vaping / adverse effects*
  • Vaping / metabolism


  • Aerosols
  • Flavoring Agents