NLRP3 inflammasome

The NLRP3 inflammasome is a multiprotein complex of the innate immune system, assembled around the sensor protein NOD-like receptor family pyrin domain containing 3 (NLRP3, also called cryopyrin). Together with the adaptor protein ASC and the effector protease caspase-1, it forms a cytosolic signaling platform that converts diverse danger signals into an inflammatory response. Its assembly conventionally requires two steps: a priming signal, typically delivered through toll-like receptor 4 and NF-κB–dependent transcription, which raises NLRP3 and pro-interleukin-1β levels, and an activation signal that triggers oligomerization. Once assembled, the complex activates caspase-1, which cleaves Pro-IL-1β and pro-IL-18 into the mature cytokines interleukin-1β and interleukin-18, and cleaves Gasdermin D to release a pore-forming fragment that drives pyroptotic cell death and cytokine release.

NLRP3 is unusual among innate immune sensors in responding to a broad and chemically unrelated set of stimuli rather than a single ligand, integrating cues such as reactive oxygen species, mitochondrial dysfunction and mitochondrial DNA release, lysosomal destabilization, potassium efflux, and crystalline or aggregated material including amyloid beta. This positions it at the center of sterile inflammation, and it has been implicated in type 2 diabetes and diabetic complications such as diabetic kidney disease and diabetic cognitive impairment, obesity and metabolic dysfunction–associated steatotic liver disease, neurodegenerative and neuroinflammatory conditions including Alzheimer's disease and Parkinson's disease, traumatic brain injury, postoperative cognitive dysfunction, osteoporosis, and fibrotic and ischemic tissue injury. Regulatory inputs studied alongside it include TXNIP, the antioxidant transcription factor Nrf2, Sirt1 signaling, mitophagy, and cross-talk with the cGAS-STING pathway. Pharmacologically, NLRP3 is an actively pursued anti-inflammatory target: the selective small-molecule inhibitor MCC950 is a standard experimental tool, and polyphenols and other natural products such as quercetin and gallic acid, mesenchymal stem cell– and extracellular vesicle–based approaches, nanoparticle formulations, and non-pharmacological interventions including electroacupuncture have all been examined for their ability to suppress inflammasome activation.