NEUROPROTECTIVE EFFECTS OF ANTIOXIDANT NITRONES THROUGH MODULATION OF THE NLRP3 INFLAMMASOME IN MICROGLIA

Recent advances in the understanding of the molecular pathophysiology of ischemic stroke have driven the search for neuroprotective, antioxidant and anti-inflammatory agents capable of modulating key events of the ischemic cascade. Nitrones, compounds known for their antioxidant properties, have emerged as promising candidates for this purpose. In this study, we evaluated the anti-inflammatory potential of five nitrones (ChN2, QN23, HBN6, PBN and QN6), previously shown to be effective in in vitro and in vivo models of cerebral ischemia, and of N-acetylcysteine (NAC), focusing on their effects on NLRP3 inflammasome activation and its contribution to neuroprotection. Experiments were performed in BV2 microglial cells stimulated with lipopolysaccharide (LPS) and adenosine triphosphate (ATP), and treated with the different compounds during both the priming and activation phases of the inflammasome, only during priming, or only during activation. NLRP3 expression, ASC speck formation, and caspase-1 and interleukin-1β (IL-1β) cleavage were analyzed under these conditions. In addition, treatment effects on cellular metabolic activity were assessed in both microglial cells and human SH-SY5Y neuroblastoma cells exposed to microglia-conditioned media. All tested compounds reduced NLRP3 inflammasome activation and downstream effectors to varying extents, particularly when administered during the priming phase. Quinolylnitrones QN6 and QN23 showed the greatest efficacy in reducing inflammatory marker expression and in reversing neuronal viability loss induced by an inflammatory microglial environment. Overall, these findings suggest that the neuroprotective effects previously described for QN6 and QN23 against cerebral ischemia may be mediated, at least in part, by modulation of the NLRP3 inflammasome.