A549 cells exposed to a marijuana smoke extract affect mono-layer integrity related to oxidative stress state

Marijuana smoke contains several toxic compounds that may induce dysregulation of oxidative mechanisms and barrier system in airway alveolar cells. This study aimed to assess whether marijuana smoke extract (MSE) modifies mono-layer integrity and antioxidant effects on the alveolar epithelial cells. A549 cells were exposed to MSE (0.1 to 5 microg/mL) or cannabinoid (+)-WIN 55,212-2 (WIN; 0.01 to 1 microM) for 24 h. Epithelial integrity and protein expression of claudin (Cl)-2, Cl-5, and occludin (Ocl) were evaluated by transepithelial electrical resistance (TEER), permeability assay, Western blot, immunofluorescence, and qPCR. TEER decreased after MSE or WIN exposure, whereas the monolayer permeability increased. Protein expression and localization of Cl-2 and Ocl were reduced after MSE treatment. However, WIN increased Cl-2 protein and decreased Cl-5 and Ocl. Differential gene expressions were observed between treatments. Malondialdehyde (MDA) production and advanced oxidation protein products (AOPP) determination showed that MSE increased AOPP, whereas WIN augmented the MDA production and decreased AOPP levels. The activity of antioxidant enzymes shows an increase in catalase, glutathione-S-transferase, γ-glutamyl transferase and arginase after MSE treatment and a decrease with WIN. Data indicates that MSE exposure alters epithelial integrity and the alveolar cells antioxidant response that, finally, may lead to lung damage.