A study published in the journal Thorax compares the pulmonary effects of vaping nicotine and cannabis. The study finds that cannabis is more harmful to lung health than nicotine.
Background
Large electronic vaporizers specifically for inhaling cannabis were first developed in the 1990s. In the 2000s, relatively smaller portable vaporizers were introduced as “e-cigarettes” to inhale nicotine.
Aerosols emitted from vaping devices contain psychoactive substances (nicotine and cannabinoids) and respiratory toxicants (formaldehyde and benzaldehydes). Because of the lipophilic properties of cannabinoids, solvents used in cannabinoid-vaping devices are different from that used in nicotine-vaping devices.
Studies investigating the health impacts of vaping nicotine have indicated that nicotine aerosols can disrupt the functioning of immune cells, suppress innate immune responses in nasal epithelial cells, and induce chronic respiratory disorders. However, not enough studies are available to determine the health effects of vaping cannabinoids.
In the current study, scientists have compared the pulmonary effects of vaping nicotine and cannabinoids in both in vivo and in vitro setups.
Study design
The study investigated the pulmonary effects of vaping cannabidiol (50 mg/ml) and nicotine (5.0%) in mice and human lung epithelial cells.
For in vivo experiments, both male and female mice were exposed to one puff of nicotine or cannabidiol aerosols for five days a week. The exposure was continued for two weeks. For in vitro experiments, human lung cells were directly exposed to freshly produced aerosols in a closed exposure system.
The health effects of exposed substances were assessed by measuring lung inflammation, oxidative stress, lung damage, cytotoxicity, and paracellular permeability.
Health effects of nicotine and cannabidiol
The study findings revealed that cannabidiol vaping has a more detrimental impact on the immune and pulmonary systems than nicotine vaping. Exposure to cannabidiol aerosols induced a proinflammatory microenvironment in the lung, as demonstrated by increased accumulation of inflammatory immune cells with elevated activity of tissue-damaging factors (myeloperoxidase and neutrophil elastase).
Cannabidiol exposure caused significantly higher induction of inflammatory and lung damage markers than nicotine exposure. Specifically, mice exposed to cannabidiol aerosols showed higher levels of CD4+ and CD8+ T cells and higher infiltration of neutrophils in the lung compared to nicotine-exposed mice. Moreover, cannabidiol exposure disrupted lung epithelial barrier integrity and induced human lung epithelial cell death.
As mentioned by the scientists, increased lung infiltration of neutrophils in cannabidiol-exposed mice is primarily responsible for the induction of inflammatory microenvironment and oxidative stress in the pulmonary system, which are collectively responsible for lung damage. Neutrophils are the primary source of two tissue-damaging factors myeloperoxidase and neutrophil elastase.
Furthermore, the study found that cannabidiol exposure causes an induction in immunosuppressive T regulatory cells and a reduction in interleukin 2 (IL-2), leading to disruption of T cell functions and suppression of adaptive immune responses in the lungs of exposed mice. These changes could increase the susceptibility of mice to respiratory infections.
A significant reduction in the number of anti-inflammatory macrophages was observed in the lungs of cannabidiol-exposed mice. This could potentially cause lung immune dysfunction and lung damage and increase lung infection risk. Common flavoring chemicals used in cannabidiol vaping products could further augment cannabidiol-induced lung macrophage dysfunction.
Further characterization of pulmonary cells revealed the presence of lung macrophages with lipid deposits. Since exogenous lipoid pneumonia with lipid deposit-containing lung macrophages is a hallmark of vaping-related lung injury, this observation indicates that cannabidiol vaping could be associated with severe respiratory health deterioration.
Study significance
The study demonstrates that cannabis vaping could be more harmful than nicotine vaping in terms of inducing lung inflammation, pulmonary barrier integrity disruption, and lung damage.
Cannabis vaping could also increase the risk of respiratory infection, suppress the immune responses to vaccinations, and worsen the respiratory symptoms of patients with pre-existing lung inflammatory diseases.
