Calcium-independent phospholipase A2 is a novel regulator of NLRP3 inflammasome activation and pro-inflammatory cytokine release 3889

Description Cell membranes are essential for life, establishing barriers between the intracellular and extracellular environment and organizing intracellular organelles. Physical membrane properties, such as fluidity, curvature, and lipid raft formation - key for receptor signaling - are determined by the composition of membrane phospholipids and regulated by enzymes like calcium-independent phospholipase A2 (iPLA2). iPLA2 hydrolyzes phospholipids into lysophospholipids and free fatty acids and is well-known for its role in neurons, where its dysregulation is linked to neurodegenerative diseases like PLA2G6-associated neurodegeneration (PLAN) and Parkinson’s disease. However, its function in immune cells remains poorly understood. Here we show that iPLA2 regulates NLRP3 inflammasome activation and pro-inflammatory cytokine release. siRNA-mediated iPLA2 knockdown in primary human macrophages significantly reduced IL-1β release in response to different NLRP3 activators. This knockdown also decreased NLRP3 and pro-IL-1β expression, inhibited ASC speck formation, and reduced Caspase-1 activation. CRISPR-Cas9-mediated KO of iPLA2 in THP-1 and mouse BMDMs further confirmed a marked reduction in IL-1β release, offering a robust tool for mechanistic studies. Our findings reveal a novel role for iPLA2 in regulating pro-inflammatory immune responses. This highlights its potential involvement in the pathogenesis of neuroinflammatory diseases, expanding its significance beyond the neuronal context.