The antioxidant resveratrol down-regulates inflammation in an in vitro model of Pseudomonas aeruginosa infection of lung epithelial cells

Abstract

Pseudomonas aeruginosa is a Gram-negative opportunistic pathogen capable of infecting the lungs and causing severe pulmonary disease in immunocompromised individuals. During the infectious process, P. aeruginosa provokes a potent inflammatory response and induces the release of reactive oxygen species (ROS). Cells undergo oxidative stress when cellular antioxidants are unable to effectively scavenge and detoxify ROS resulting in lung damage. Resveratrol (3,5,4‟-trihydroxystilbene) is a natural polyphenolic compound with recognized antioxidant effects. In this study we have tested the hypothesis that the antioxidant activities of resveratrol can attenuate an inflammatory response in P. aeruginosa-infected cells. Human lung epithelial (A549) cells were pre-treated with resveratrol for 5 hours followed by infection with P. aeruginosa in vitro. Intracellular ROS generation measured with CM-H2DCFDA was used as an indicator of P. aeruginosa-induced oxidative stress. Surface expression of Fas/CD95 and activation of caspases-3 and -7 were used as indicators of cellular apoptosis. To further study the effects of resveratrol we also measured protein expression of intercellular adhesion molecule (ICAM)-1 and gene expression of pattern recognition receptors and enzymes related to inflammation and redox signaling. Resveratrol significantly reduced ROS generation, ICAM-1 expression, human beta-defensin-2 expression, and markers of apoptosis in A549 cells infected with P. aeruginosa, and up-regulated levels of glutathione peroxidase, suggesting that this compound may play an important therapeutic role in protecting the lungs against the deleterious effects of P. aeruginosa infection.