Docosahexaenoic acid alleviates cell injury and improves barrier function by suppressing necroptosis signalling in TNF-α-challenged porcine intestinal epithelial cells

Long-chain n-3 polyunsaturated fatty acids are known to have beneficial effects on intestinal health. However, the underling mechanisms are largely unknown. The present study was conducted to investigate whether docosahexaenoic acid (DHA) attenuates TNF-α-induced intestinal cell injury and barrier dysfunction by modulating necroptosis signalling. Intestinal porcine epithelial cell line 1 was cultured with or without 12.5 µg/ml DHA, followed by exposure to 50 ng/ml TNF-α for indicated time periods. DHA restored cell viability and cell number triggered by TNF-α. DHA also improved barrier function, which was indicated by increased trans-epithelial electrical resistance, decreased FD4 flux and increased membrane localisation of zonula occludins (ZO-1) and claudin-1. Moreover, DHA suppressed cell necrosis in TNF-α-challenged cells, as shown in the IncuCyte ZOOM™ live cell imaging system and transmission electron microscopy. In addition, DHA decreased protein expression of TNF receptor, receptor interacting protein kinase 1, RIP3 and phosphorylation of mixed lineage kinase-like protein, phosphoglycerate mutase family 5, dynamin-related protein 1 and high mobility group box-1 protein. Furthermore, DHA suppressed protein expression of caspase-3 and caspase-8. Collectively, these results indicate that DHA is capable of alleviating TNF-α-induced cell injury and barrier dysfunction by suppressing the necroptosis signalling pathway.