Low concentration of oleic acid exacerbates LPS-induced cell death and inflammation in human alveolar epithelial cells

Purpose: The current study aimed to investigate in vitro effects of oleic acid on lipopolysaccharide (LPS)-induced acute lung injury in the human lung epithelial cells (A549). Materials and Methods: The cell viability was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) tests. Selected gene expression levels were analyzed by Real-Time Quantitative-Polymerase Chain Reaction (RT-qPCR). Results: 24hours of LPS (100ng/mL) exposure decreased the cells' viability by 44.6% compared to untreated control. Low concentration (2.5nM) of oleic acid slightly suppressed the cell survival by 9.1% analyzed 24hours after incubation. However, oleic acid pretreatment before LPS exposure significantly increased cell survival loss to 63.9%. LPS exposure decreased the expressions of catalase (CAT) and glutathione peroxidase (GPx) mRNA levels by 2.8 and 2.5 fold, respectively. Moreover, pretreatment of the cells with oleic acid strengthened LPS-decreased expressions of CAT and GPx genes by 3.5 and 6.7 fold, respectively. The mRNA expressions of superoxide dismutase (SOD), induced nitric oxide synthase (iNOS), interleukin-1 beta, IL-12, COX-2, caspase-3 and caspase-8 were increased by 2.4, 2.2, 2.2, 2.3, 3.0, 2.6, and 2.5 fold, respectively, by LPS, and oleic acid pretreatment significantly potentiated the effect of LPS. Conclusion: Oleic acid worsens LPS-induced cell death by potentiating oxidative stress and inflammation in A549 lung epithelial cells.