EPA and DHA inhibit endocytosis of claudin-4 and protect against deoxynivalenol-induced intestinal barrier dysfunction through PPARγ dependent and independent pathways in jejunal IPEC-J2 cells

Peroxisome proliferator activated receptor gamma (PPAR gamma) activation has been shown to protect against intestinal injury induced by different stimuli. PPAR gamma is known to regulate tight junction proteins (TJP) in epithelial cells. Both eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are natural PPAR gamma agonists, but the implication of PPAR gamma in their physiological effects on the gut is poorly understood. Therefore, this study was conducted to investigate the mechanism of EPA and DHA effects on intestinal epithelial cell barrier function in IPEC-J2 cells exposed to deoxynivalenol (DON), a known food mycotoxin that is toxic to both humans and animals. Exposure of cells to EPA and DHA significantly increased mRNA expression of a PPAR gamma target gene, AP2, and concomitantly increased the protein expression of claudin-4. Treatment with EPA and DHA also reversed the endocytosis and degradation of claudin-4 caused by DON exposure. EPA and DHA also restored the membrane presence of claudin-4 and ZO-1 that was disrupted by DON. However, the protective effects of EPA and DHA against DON exposure was abolished by a specific PPAR gamma antagonist (T0070907), confirming the importance of PPAR gamma in regulating TJP expression by the fatty acids. Effect of PPAR gamma activation by EPA and DHA also included the restoration of transepithelial electrical resistance (TEER) and reduction of fluorescein isothiocyanate-labeled dextran (FITC-dextran) permeability that have been perturbed by DON. However, the effectiveness of EPA and DHA in opposing DON-induced decrease in TEER and the increase in FITC-dextran permeability was not affected by PPAR gamma inhibition, potentially suggesting the involvement of other PPAR gamma-independent mechanisms in the observed benefits from EPA and DHA. Collectively, this study shows that the protective effects of EPA and DHA against DON-induced intestinal barrier disruption are through both PPAR gamma-dependent and-independent pathways. Therefore, EPA and DHA containing ingredients could be used to prevent the DON-induced gut barrier dysfunction in humans and animals.