Inhibiting NLRP3 inflammasome with MCC950 ameliorates perioperative neurocognitive disorders, suppressing neuroinflammation in the hippocampus in aged mice

Perioperative neurocognitive disorders (PND) are characterized by deficits in cognitive functions in the elderly following anesthesia and surgery. Effective clinical interventions for preventing this disease are limited. Growing evidence demonstrates that activation of NOD-like receptor protein3 (NLRP3) inflammasome is involved in neurodegenerative diseases. We therefore hypothesized that activation of NLRP3 inflammasome is linked to neuroinflammation and the subsequent cognitive impairments that occurred in an animal model of PND. In this study, 18-month-old C57BL/6 mice were subjected to an exploratory laparotomy under isoflurane anesthesia to mimic clinical human abdominal surgery. For interventional studies, mice received NLRP3 specific inhibitor MCC950 (10 mg/kg) or the vehicle only intraperitoneally. Behavioral studies were performed at 6 and 7 d after surgery using open field and fear conditioning tests, respectively. Interleukin-1 beta (IL-1 beta), interleukin-18 (IL-18), tumor necrosis factor-alpha (TNF-alpha), ionized calcium-binding adaptor molecule-1 (IBA1) positive cells, glial fibrillary acidic protein (GFAP) positive cells, NLRP3, apoptosis-associated speck-like protein containing a CARD (ASC), and cleaved caspase-1 were measured at 3 days post-surgery. Brain-derived neurotrophic factor (BDNF) and postsynaptic density protein 95 (PSD95) were measured at 7 days post-surgery. Our data indicates that surgery-induced cognitive impairments were associated with significant increases in IL-1 beta, IL-18, TNF-alpha, NLRP3, ASC, cleaved caspase-1, IBA1-positive cells and GFAP-positive cells, and decreases in BDNF and PSD95 expression in the hippocampus. Notably, administration with MCC950 attenuated inflammatory changes and rescued surgery-induced cognitive impairments. Our study suggests that surgery induces neuroinflammation and cognitive deficits that are partly attributed to the activation of NLRP3 inflammasome in the hippocampus of aged mice.