Primer: inflammasomes and interleukin 1beta in inflammatory disorders

Inflammasomes are large, multimeric protein complexes that link the sensing of microbial products and metabolic stress to the proteolytic processing of prointerleukin (pro-IL)-1beta to its active form. NALP1 and NALP2 are founding members of the Nod-like receptor family. Other Nod-like receptors, including NALP3 and NOD2, which are associated with inflammatory disorders, have also been described. The NALP1 and NALP3 inflammasomes are located in the cytoplasm and can, therefore, detect intracellular infection through recognition of microbial pathogen-associated molecular patterns. The inflammasome pathways cooperate with Toll-like receptor pathways to mediate a rapid and appropriate response to pathogens and genotoxic stress. Mutations in both pyrin and NALP3 components of inflammasomes are associated with innate-immune-mediated diseases (familial Mediterranean fever and the 'cryopyrinopathies'), and aberrant IL-1beta processing has been reported in several autoinflammatory conditions, including Muckle-Wells syndrome, chronic infantile neurologic, cutaneous and articular syndrome/neonatal onset multisystem inflammatory disease, and gout. The effectiveness of IL-1beta blockade in treating many of these conditions has transformed the understanding and management of these disorders and also highlighted the role of aberrant IL-1beta signaling in other conditions, such as adult-onset Still's disease and systemic juvenile idiopathic arthritis.