Modulation of Inflammasome Activity for the Treatment of Auto-inflammatory Disorders

The innate immune system orchestrates inflammatory responses to microorganisms or danger-associated molecular patterns generated, for example, by the deposition of uric acid in the joints of gout patients. The innate immune system comprises multiple germ-line encoded receptors, of which the nucleotide-binding domain and leucine-rich repeat containing receptors (NLRs) are crucial for the maturation of pro-inflammatory cytokines. NLRs oligomerize to form large multi-protein complexes termed inflammasomes that generate active caspase-1 fragments leading to the cleavage and secretion of mature cytokines such as IL-1 beta and IL-18. At least four independent inflammasomes have been identified, NLRP1, NLRP3, IPAF, and AIM2. These inflammasomes assemble in response to different stimuli to confer specificity and are also subject to negative regulatory mechanisms to ensure that once a productive inflammatory response has been mounted, inflammatory cytokine production is restrained. A number of human conditions are characterized by unrestrained inflammasome activation. As much is now known about how inflammasomes are regulated, it is hoped that this can be channeled into the development of novel therapeutics, for example, those that may block the upstream activation and assembly of inflammasomes.