P083 Dietary-derived ω-3 and ω-6 polyunsaturated fatty acids trigger an inflammatory response in intestinal epithelial cells with chemically inhibited GPX4 activity

Abstract Background The incidence of inflammatory bowel diseases (IBD) has increased drastically in recent years, which is mainly explained by environmental factors and changes in our diet. Recent studies indicated that a Western-style diet, characterized by an increased caloric intake and consumption of long-chain fatty acids such as polyunsaturated fatty acids (PUFAs), triggers inflammation in metabolic active tissues, termed metabolic inflammation. We recently demonstrated that ω-3 and ω-6 PUFAs fuel an inflammatory response in intestinal epithelial cells (IECs) with genetically reduced expression of the anti-oxidative enzyme glutathione peroxidase 4 (GPX4), and similarly a Western-style diet enriched with PUFAs triggered severe enteritis in mice with reduced GPX4 specifically in IECs (i.e., Gpx4+/-IEC mice). Here, we investigated if PUFAs similarly trigger an inflammatory response in IECs with chemically inhibited GPX4 activity. Methods Experiments were performed with an immortalised murine IEC line (MODE-K) cells. Cells were stimulated with the ω-3 PUFA stearidonic acid (50 µM), the ω-6 PUFA arachidonic acid (20 µM) or a respective control and the GPX4 inhibitor (1S,3R)-RSL3 (RSL3). Cell death, production of inflammatory cytokines, stress at the endoplasmic reticulum (ER) and activation of mitogen-activated protein kinases (MAPKs) were examined. Results Treatment with RSL3 induced cell death in IECs in a dose dependent manner. For further experiments, we worked with 20 nM RSL3, as this concentration already induced some amount of cell death but approximately 75% of cells were still viable. Stimulation with both ω-3 and ω-6 PUFAs triggered the production of interleukin 6 (IL-6) and chemokine (C-X-C motif) ligand 1 (CXCL1) in RSL3 co-treated IECs. Moreover, co-treating of RSL3 and PUFAs induced ER stress and activation of the ER stress sensor inositol-requiring enzyme 1 alpha (IRE1α), an inflammatory signalling hub, in IECs which was paralleled by the activation of MAPKs and especially the c-Jun N-terminal kinase (JNK) branch. Conclusion Our findings demonstrate that the chemical inhibition of GPX4 was sufficient to fuel inflammation in IECs in response to PUFAs, which we previously similarly observed in IECs with genetic depletion of Gpx4.