Does chronic low-grade inflammation increase EPA turnover and worsen consequences of low EPA?

Mechanistic pathways of inflammation resolution

• Eicosapentaenoic acid (EPA) serves as the obligate substrate for the synthesis of E-series specialized pro-resolving mediators (SPMs), including resolvins RvE1, RvE2, and RvE3.
• This metabolic pathway initiates when EPA is converted to 18-hydroxyeicosapentaenoic acid (18-HEPE) via endothelial or epithelial COX-2 or cytochrome P450 monooxygenases, followed by sequential oxygenation by 5-lipoxygenase (5-LOX) in leukocytes.
• Operating at nanomolar concentrations, these resolvins bind to specific G-protein-coupled receptors (such as ChemR23 and BLT1) to actively restrict neutrophil infiltration, suppress pro-inflammatory cytokines (including TNF-α and IL-6), and enhance macrophage-mediated efferocytosis.

Inflammation-driven EPA turnover and deficiency

• Chronic low-grade inflammation activates phospholipases, particularly phospholipase A2 (PLA2), which selectively liberate EPA from cell membrane phospholipids to fuel SPM synthesis.
• This ongoing utilization increases metabolic flux and functional consumption of EPA, accelerating the depletion of tissue reserves during chronic inflammatory states.
• Because EPA is the precursor for these critical "stop signals," low systemic EPA levels directly limit 18-HEPE and E-series resolvin biosynthesis, leading to a failed resolution program and persistent, unresolved inflammation.

Bottom line

• Chronic low-grade inflammation accelerates the metabolic consumption and turnover of EPA via phospholipase activation; consequently, maintaining adequate EPA levels is vital, as a deficiency prevents the generation of pro-resolving mediators and leads to persistent, unresolved systemic inflammation.