Lipid peroxidation of polyunsaturated fatty acids triggers a pro-inflammatory cytokine response in intestinal epithelial cells

Introduction:

Glutathione peroxidase 4 (GPX4) is an anti-oxidative acting enzyme reducing lipid peroxides within biomembranes and is linked to the development of Crohn's disease (CD) by genetic association. Lipid peroxidation (LPO) especially affects polyunsaturated fatty acids (PUFAs), because their double bonds are prone to oxidation. PUFAs are enriched in a common western style diet, as they are mainly found in red meat and eggs. How dietary PUFAs affect the development of CD is currently unknown.

Materials and Methods:

GPX4 siRNA silencing was established in MODE-K cells, a small intestinal epithelial cell line (IECs). Silenced cells were stimulated with saturated (palmitic acid: PA), monounsaturated (oleic acid: OA, palmitoleic acid: POA) as well as omega-3 and omega-6 PUFAs (stearidonic acid: SDA, eicosapentaenoic acid: EPA, docosapentaenoic acid: DPA, arachidonic acid: AA, docosahexaenoic acid: DHA), respectively. LPO was measured with BODIPY 581/591 C11 by flow cytometry, cytokines in cell supernatant with respective ELISA-kits.

Results:

GPX4-silenced IECs exhibited increased levels of LPO, which was aggravated by the stimulation with omega-6 PUFA arachidonic acid and a range of omega-3 PUFAs. Further, stimulation with PUFAs led to an increased release of IL-6, CXL-1 as well as other pro-inflammatory cytokines and chemoattractants. Interestingly saturated and monounsaturated fatty acids like did not induce cytokine production or LPO in GPX4-silenced IECs.

Conclusion:

Our data provides evidence that specific dietary components induce inflammation in GPX4-deficient IECs. Specifically, PUFAs but not saturated or monounsaturated fatty acids provoke the production of lipid peroxides and the release of proinflammatory cytokines in GPX4-deficient IECs. We identified a non-toxic dietary component capable of inducing inflammation in susceptible intestinal epithelial cells.