Orchestration of pathogen recognition by inflammasome diversity: Variations on a common theme.

Innate immunity is a crucial part of the immune system, capable of mounting specific host responses against distinct pathogens. An integral component of the innate immune system is a network of pathogen recognition receptors, which are present at the surface of the cell or in the cytoplasm. Nucleotide oligomerization domain (Nod)-like receptors form the largest known family of intracellular innate immune sensors of microbes and danger signals that initiate early host responses. Some Nod-like receptors, such as NALP, NAIP and IPAF, form molecular machines termed inflammasomes, which are involved in the activation of inflammatory cytokines such as IL-1beta and IL-18. The diversity and the role of the different types of inflammasomes remain poorly defined. In this issue of the European Journal of Immunology, it is reported that the Gram-negative human pathogen Pseudonomas aeruginosa specifically activates an IPAF inflammasome. This finding, in combination with other recently published reports, reveals how different pathogens engage distinct types of inflammasomes, further highlighting the diversity and plasticity of inflammasomes activation.