Long-chain PUFA ameliorate ETEC-induced intestinal inflammation and cell injury by modulating pyroptosis and necroptosis signaling pathways in IPEC-1 cells

Abstract

Abstract This study was aimed to investigate whether eicosapentaenoic acid (EPA) and arachidonic acid (ARA), the representative n-3 or n-6 polyunsaturated fatty acids (PUFA), could alleviate enterotoxigenic Escherichia coli (ETEC) K88-induced inflammation and injury of intestinal porcine epithelial cells 1 (IPEC-1) by modulating pyroptosis and necroptosis signaling pathways. IPEC-1 cells were cultured with or without EPA or ARA in the presence or absence of ETEC K88. EPA and ARA reduced ETEC K88 adhesion and endotoxin content in the supernatant. EPA and ARA increased transepithelial electrical resistance (TEER) and decreased permeability of fluorescein isothiocyanate-labeled dextran (FD4), and increased membrane protein expression of occludin, ZO-1 and claudin-1, and relieved disturbed distribution of these proteins. EPA and ARA also reduced cell necrosis ratio. EPA or ARA reduced mRNA and concentration of tumor necrosis factor-α (TNF-α), interleukin (IL)-6 and IL-8, and decreased mRNA abundances of intestinal toll-like receptors 4 (TLR4) and its downstream signals. Moreover, EPA and ARA downregulated mRNA expression of nod-like receptor protein 3 (NLRP3), caspase 1 and IL-18, and inhibited protein expression of NLRP3, apoptosis-associated speck-like protein containing a CARD (ASC), gasdermin D and caspase-1. Finally, EPA and ARA reduced mRNA expression of fas-associated death domain protein (FADD), caspase 8, receptor interacting protein kinase (RIP) 1, mixed lineage kinase-like protein (MLKL), phosphoglycerate mutase 5 (PGAM5), motility related protein 1 (Drp1) and high mobility protein 1 (HMGB1), and inhibited protein expression of phosphorylated-RIP1 (p-RIP1), p-RIP3, p-MLKL and HMGB1. These data demonstrate that EPA and ARA prevent ETEC K88-induced cell inflammation and injury, which is partly through inhibiting pyroptosis and necroptosis signaling pathways.