Activation of Ffar4 differentially affects 5-LOX metabolites in cultured microglia
Research Poster Health & Life Sciences 2025 Graduate ExhibitionPresentation by Haley Guffey
Exhibition Number 151
Abstract
5-lipoxygenase (5-LOX) converts arachidonic acid (AA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) into bioactive metabolites, and the enzyme is elevated in brains of Alzheimer’s disease (AD) patients post-mortem. In primary cardiomyocytes, activation of free fatty acid receptor 4 (Ffar4) induces the appearance of 18-HEPE, an EPA metabolite that precedes the E-series resolvins. We hypothesized that activation of Ffar4 in microglia would also induce an 18-HEPE response to complement the 5-LOX response. Using cultured IMG microglia, we challenged cells with TNF- at 0, 10, or 20 ng/ml, and with vehicle or 10 uM of TUG-891. All treatments received apoA-I, LXR, and cAMP to ensure lipid export, and a 5 M solution of AA, EPA, and DHA as a substrate for metabolite production. Concentrations were analyzed via LC-MS/MS. With TUG-891 present, 10 and 20 ng/ml TNF- induced an intracellular increase in the DHA 5-LOX metabolite 4-HDoHE (p = 0.01 and p = 0.02, respectively) and the AA 5-LOX metabolite 5-HETE (p = 0.04 and p = 0.01), but not the EPA 5-LOX metabolite 5-HEPE (p = 0.28 and p = 0.08). Of these, TUG-891 induced an increase in only 5-HETE (p = 0.004) upon exposure to 20 ng/ml TNF-. 18-HEPE levels were unchanged with TUG-891 in TNF--exposed cells (p = 0.06); instead, a 12-HEPE response was observed (p = 0.0007). Altogether, responses of 5-LOX metabolites and HEPEs vary upon Ffar4 activation. Future studies should assess 5-LOX metabolite and other HEPE production upon Ffar4 activation in AD animal models.
Importance
5-lipoxygenase (5-LOX) converts polyunsaturated fatty acids (PUFAs) into bioactive metabolites, and the enzyme is elevated in brains of Alzheimer’s disease (AD) patients post-mortem. In primary cardiomyocytes, activation of free fatty acid receptor 4 (Ffar4) induces the appearance of 18-HEPE, an EPA metabolite that precedes the E-series resolvins. Resolvins possess anti-inflammatory properties; thus, stimulating activation of Ffar4 may be beneficial in the reduction of inflammation. Being that brains of AD patients are in a state of chronic inflammation, it is imperative to investigate the roles of Ffar4 and 5-LOX in brain cells that provoke inflammation.