Medium and Long Chain Fatty Acids Differentially Modulate Apoptosis and Release of Inflammatory Cytokines in Human Liver Cells

Medium chain fatty acids (MCFA) can be more easily absorbed and supply energy more rapidly than long chain fatty acids (LCFA). However, little is known about the inflammatory response by the treatment of MCFA in human liver cells. Thus this study used human liver cells (LO2) to evaluate the effects of MCFA on apoptosis and inflammatory response. Tetrazolim-based colorimetric assay and lactate dehydrogenase assay were used to measure the viability of LO2 cells, isolated spleens and liver cells from BALB/C mice. Inverted fluorescence microscopy and flow cytometry were used to assess the cell apoptosis. Activity of superoxide dismutase and malondialdehyde level were measured to determine the oxidative damage. mRNA or protein levels of classical pro-inflammatory cytokines were analyzed by quantitative real-time polymerase chain reaction (qPCR), enzyme-linked immunosorbent assay and western blotting. The results showed that the liver cells treated with the fatty acids at 200 μM for 24 h exhibited good viability. Fatty acids induced inflammatory cytokines at transcriptional and translational levels to a lesser extent than lipopolysaccharide. LCFA (oleic acid) up-regulated tumor necrosis fator-α, monocyte chemoattractant-1 and interleukin-1β while down-regulated IL-6 and IL-8 secretion to a higher extent than MCFA in mRNA and protein levels. These findings suggested that MCFA may induce apoptosis to a less extent and exert more gentle inflammation than LCFA in human liver cells.