482-P: Eicosapentaenoic Acid (EPA) Alleviates LPS-Induced Oxidative Stress via the PPARα-NF-κB Axis

Introduction and Objective: Metabolic endotoxemia, fueled by lipopolysaccharide (LPS) translocation, promotes chronic inflammation and insulin resistance in obesity and type 2 diabetes. Eicosapentaenoic acid (EPA/C20:5) exhibits anti-inflammatory and antioxidative effects, yet its precise mechanism against LPS-induced oxidative stress in macrophages remains unclear. This study investigates EPA’s protective role via the FABP5/PPARα/NF-κB axis. Methods: THP-1 monocytes were differentiated into macrophages and pretreated with EPA or vehicle for 24 hours, followed by overnight LPS stimulation. Gene expression was analyzed by TaqMan; protein levels by Western blot, flow cytometry, and ELISA. Mitochondrial membrane potential and ROS were measured with JC-1 and DCFH-DA assays, respectively. Pharmacological inhibition of PPARα was performed with GW9662. Results: EPA pretreatment significantly dampened LPS-induced inflammatory responses, as evidenced by reduced IL-1β and IL-6 expression, decreased IL-1β secretion, and a lower percentage of HLA-DR+ macrophages. Concomitantly, ER stress markers (ATF4, DDIT3, HSPA5/GRP78, BIP, and CHOP) were downregulated at both gene and protein levels. EPA also mitigated oxidative stress, indicated by lower expression of HIF1α, decreased ROS levels, and preserved mitochondrial membrane potential. Mechanistically, EPA stimulated PPARα and FABP5 expression while inhibiting NF-κB activation, independent of TLR4-IRF5 signaling. Notably, blocking PPARα with GW9662 abolished these protective effects, underscoring the necessity of PPARα activation in EPA-mediated cytoprotection. Conclusion: EPA ameliorates LPS-induced oxidative stress and inflammation in macrophages by activating PPARα and FABP5 while inhibiting NF-κB, offering a potential therapeutic strategy to counter inflammation in metabolic disorders. Disclosure H. Alabduljader: None. H. AlSaeed: None. A. Alrabeea: None. F. Almulla: None. R. Ahmad: None. F. Alrashed: None. Funding Kuwait Foundation for the Advancement of Sciences (KFAS) RA CB-2019-002