Caspase-11: the driving factor for noncanonical inflammasomes.

Inflammasomes are large multiprotein platforms that mediate the processing of caspase-1, which in turn promotes the maturation and release of IL-1β and IL-18 in response to microbial and danger signals. While the canonical pathway of inflammasome activation has been known for some time, a novel mechanism of noncanonical inflammasome activation mediated by caspase-11 was more recently identified. This pathway engages caspase-11 to trigger both caspase-1-dependent and -independent production of the inflammatory cytokines IL-1β, IL-18, and IL-1α, as well as to promote pyroptosis, a form of genetically programmed cell death that is associated with the release of such cytokines. In this review, we gather together studies on both the mechanisms and implications of caspase-11-mediated noncanonical inflammasome activation, and discuss the emerging importance of this pathway in regulating host defense against intracellular bacterial pathogens.