Medium- and long-chain fatty acids differentially modulate interleukin-8 secretion in human fetal intestinal epithelial cells

The primary therapeutic effects of enteral nutrition in patients with Crohn's disease have been reported previously. Although the quantity and type of fat in enteral nutrition are considered to be important, it is unclear how fat modulates mucosal inflammatory responses in the intestine. In the present study, we evaluated the effects of medium-chain and long-chain fatty acids (MCFA and LCFA) on interleukin (IL)-8 secretion in a fetal intestinal epithelial cell line, intestine-407 cells. IL-8 expression was evaluated at the protein and mRNA levels. The activation of nuclear factor-kappaB was assessed with an electrophoretic gel mobility shift assay. The addition of oleic acid (LCFA) micelles, but not octanoic acid (MCFA) micelles, weakly but significantly enhanced basal IL-8 secretion in the intestine-407 cells. The addition of MCFA (5 mmol/L) induced a 40% increase in IL-1 beta -induced IL-8 secretion and a 35% increase in tumor necrosis factor (TNF)-alpha -induced IL-8 secretion, respectively. The addition of LCFA (5 mmol/L) induced a 140% increase in IL-1 beta -induced IL-8 secretion and a 110% increase in TNF-alpha -induced IL-8 secretion, respectively. These responses were also observed at the mRNA levels. The electrophoretic gel mobility shift assay indicated that both MCFA and LCFA enhanced IL-1 beta- and TNF-alpha -induced nuclear factor-kappaB activation. We demonstrated the proinflammatory activities of MCFA and especially LCFA. It is likely that medium-chain triglycerides may be more suitable than long-chain triglycerides as an energy source in enteral diets in the treatment of patients with Crohn's disease.