LXRβ-Selective Agonism Enhances CYP2J2-Mediated DHA Epoxide Generation to Resto…

This hypothesis proposes that LXRβ-selective agonists enhance CYP2J2 expression and activity to increase protective DHA epoxide generation, simultaneously addressing both cholesterol dysregulation and membrane rigidification in Alzheimer’s disease. LXR signaling is known to upregulate cytochrome P450 enzymes involved in lipid metabolism, including CYP2J2, through direct transcriptional control. By selectively activating LXRβ, this approach would increase endogenous CYP2J2-mediated conversion of DHA to protective epoxides that prevent Aβ-induced synaptic membrane rigidification, while concurrently promoting cholesterol efflux from activated microglia and enhancing APOE lipidation. This dual mechanism addresses the critical pathophysiology where Aβ oligomers increase membrane cholesterol content by ~40% and expand raft domains in cortical neurons. The LXRβ-mediated upregulation of CYP2J2 would provide a sustainable source of protective epoxides, potentially overcoming the pharmacokinetic limitations of direct DHA supplementation where epoxides have 2-4 hour half-lives due to rapid sEH metabolism. LXRβ activation would also induce ABCA1/ABCG1 transporters to reduce microglial cholesterol accumulation and improve APOE particle formation for enhanced Aβ clearance. This integrated approach leverages LXRβ’s natural role as a cholesterol sensor and metabolic regulator to coordinately enhance protective lipid metabolism pathways. The hypothesis predicts that LXRβ-selective agonists (avoiding LXRα-mediated hepatic lipogenesis) would restore synaptic membrane fluidity through enhanced endogenous DHA epoxide production while simultaneously improving glial cholesterol homeostasis and APOE function, providing synergistic neuroprotection against Alzheimer’s pathology.