Mechanisms of inflammasome activation: recent advances and novel insights

• New inflammasomes and new microbial triggers of inflammasomes have been identified.
• Cytosolic LPS is detected by caspase-11 resulting in its activation.
• A novel pyrin inflammasome responds to pathogen-induced modifications of host proteins.
• Identification of a new NLRP6 pathway controlling mucus production.

Inflammasomes are cytosolic multiprotein platforms assembled in response to invading pathogens and other danger signals. Typically inflammasome complexes contain a sensor protein, an adaptor protein, and a zymogen – procaspase-1. Formation of inflammasome assembly results in processing of inactive procaspase-1 into an active cysteine-protease enzyme, caspase-1, which subsequently activates the proinflammatory cytokines, interleukins IL-1β and IL-18, and induces pyroptosis, a highly-pyrogenic inflammatory form of cell death. Studies over the past year have unveiled exciting new players and regulatory pathways that are involved in traditional inflammasome signaling, some of them even challenging the existing dogma. This review outlines these new insights in inflammasome research and discusses areas that warrant further exploration.