What happens to lung cells that are exposed to cannabis smoke?

Aguiar JA, Huff RD, Tse W, Stampfli MR, McConkey BJ, Doxey AC, Hirota JA. Transcriptomic and barrier responses of human airway epithelial cells exposed to cannabis smoke. Physiological Report 2019;7(20):e14249

The original open access article can be found on the PMC or Wiley websites

Why was this study conducted?
Combustion (smoking) is the most common way of consuming cannabis so the growing recreational and medicinal use of cannabis will probably increase cannabis smoke exposure. Decades of research have documented the adverse effects of tobacco smoke on the lungs and the airway epithelium (the thin tissue lining the airway), but much less is known about the effects of cannabis smoke. To help inform cannabis policies and user practices, Canadian researchers conducted in vitro research comparing tobacco and cannabis smoke using a line of human epithelial cells.

What does this study add?
Cells exposed to cannabis smoke demonstrated changes linked to DNA replication and oxidative stress, impairment in barrier function and antiviral immune responses, and an augmented pro-inflammatory cytokine profile. The cannabis-induced responses were similar to those observed for tobacco smoke, suggesting parallel implications for the lung health of smokers.

Is there anything else I should know?
Research on tobacco smoke has the advantage of a single, mostly consistent product, which contributes to experimental reproducibility and robustness. However, the situation is more complex in cannabis smoke research, as different strains vary in their cannabinoid content. The study tried to use a cannabis strain generally representative of what is available in the medicinal cannabis market in Canada; it was 13% tetrahydrocannabinolic acid (THCA, that converts to THC when heated) but contained no cannabidiol (CBD). More research is needed to see how these results from cell-based research with a single cannabis strain apply to human health.