Metabolic Profiling Reveals a Glycolytic Shift and an <scp>IRG1</scp> /Itaconate/ <scp>NF2L2</scp> Axis Regulating Neurotoxic Oxidative Stress in Inflammatory Microglia

Polar metabolic profiling, as well as bioenergetic assays, were used to characterize microglial responses to lipopolysaccharide, which induces a pro-inflammatory state, and interleukin-4, which is associated with an anti-inflammatory phenotype. BV2 microglial cells and primary microglia were used for these investigations. Results revealed that lipopolysaccharide-treated microglia exhibited an increased aerobic glycolytic activity measured by extracellular flux analysis, accompanied by increased levels of endogenous itaconate, a metabolite produced by the IRG1 enzyme. Increased itaconate levels observed by LC-HRMS were found to be associated with a stabilization of the NF2L2/NRF2 transcription factor. Attenuation of the Acod1 gene leads to increased pro-inflammatory cytokine production, as measured by ELISA, while having no effect on LPS-induced oxidative stress or neurotoxicity, an effect only observed upon silencing Nfe2l2. This suggests that an IRG1/itaconate/NRF2 axis functions as a feedback mechanism. The study underscores the dual role of metabolic reprogramming in microglial activation, balancing inflammation and neuroprotection, and suggests potential therapeutic targets for neuroinflammatory diseases by modulating itaconate and NF2L2/NRF2-related pathways. This work highlights the complexity and therapeutic potential of targeting microglial metabolism in CNS disorders.