The Modulatory Effect of Common Dietary Fatty Acids on IPEC‐J2 Transport of Lipopolysaccharide and Monolayer Barrier Integrity in vitro

Abstract

Recent evidence has demonstrated the ability of dietary fatty acid composition to influence postprandial endotoxemia in humans and swine. However, the mechanism(s) by which fatty acids affect transport of lipopolysaccharide (LPS) across the intestinal epithelium has not yet been fully elucidated. To study this, we utilized non‐transformed porcine jejunum‐derived IPEC‐J2 cells. This cell line is well‐recognized to form confluent polarized monolayers with apical and basolateral regions, allowing for an in vitro model of the intestinal epithelium. The present study investigated the effect dietary fatty acids and inflammation had on intestinal permeability of LPS and barrier integrity in IPEC‐J2 monolayers. We hypothesized that treatment of IPEC‐J2 monolayer with saturated or n‐6 polyunsaturated fatty acids (PUFA) would enhance fluorescein‐isothiocyanate (FITC)‐LPS apical‐to‐basolateral permeability and reduce transepithelial resistance (TER); whereas n‐3 PUFA would attenuate this response. Secondly, we hypothesized that lauric acid would amplify the reduction in monolayer integrity associated with pre‐treatment with LPS. IPEC‐J2 cell monolayers were grown to confluency (>1kΩ) on 0.4 μm Transwell® inserts. In experiment 1, these monolayers were treated with either 50 or 100 μM of docosahexaenoic acid, lauric acid, arachidonic acid or vehicle for 48 hours before TER and FITC‐LPS determination of barrier integrity. In experiment 2, monolayers were treated with either 5 μg/mL LPS, LPS plus 100 μM lauric acid or saline vehicle for 24 hours and then TER and FITC‐LPS determination of barrier integrity assessed. In experiment 1, TER and FITC‐LPS permeability was not altered by fatty acid type or concentration. For experiment 2, compared to the saline control, LPS caused a significant time‐dependent reduction in TER (p<0.001); however, the co‐inclusion of lauric acid fatty acids did not have any additive effect on TER (p>0.05). Although TER was reduced, surprisingly we reported no treatment differences in apical to basolateral FITC‐LPS permeability. In conclusion, fatty acid treatment did not modulate barrier inflammation and permeability in in vitro IPEC‐J2 monolayers. However, live Gram‐negative bacteria or their bacterial cellular membrane fragments may be a better model to study the effects of fatty acids on LPS permeability.Support or Funding InformationResearch supported by the Agriculture and Food Research Initiative Grant No. 2014‐67017‐21778 from the USDA NIFA.