Policing the cytosol—bacterial-sensing inflammasome receptors and pathways

Pattern recognition receptors recognize signals originating from pathogens and comprise a large part of the arsenal in innate immune responses. The NOD-like receptors (NLRs) are one particular class of these receptors that survey the cytoplasm for signs of pathogen invasion. Upon detection, they trigger the formation of a macromolecular complex called the inflammasome that is required for elimination of the pathogen, as well as amplifying a pro-inflammatory response. Although the core machinery has been defined, recent data emphasize the complexity of how NLR inflammasomes function. Here, we highlight new discoveries that reveal how precisely fine-tuned NLR inflammasome functions are, and how that may be modulated by antagonistic effects of concomitant inflammasome activation as well as novel regulatory factors.

► Recent developments implicate simultaneous engagement of multiple NLR inflammasomes. ► Recent data indicate the possibility of alternate outputs of NLR inflammasomes. ► Novel regulators of NLR inflammasomes integrate multiple immune signaling pathways. ► Elucidation of caspase-11 function in cytosolic-sensing pathways.