Dataset Information

Canonical Inflammasomes Drive IFN-? to Prime Caspase-11 in Defense against a Cytosol-Invasive Bacterium.

ABSTRACT: The inflammatory caspases 1 and 11 are activated in response to different agonists and act independently to induce pyroptosis. In the context of IL-1?/IL-18 secretion, however, in vitro studies indicate that caspase-11 acts upstream of NLRP3 and caspase-1. By contrast, studying infection in vivo by the cytosol-invasive bacterium Burkholderia thailandensis, we find that caspase-1 activity is required upstream of caspase-11 to control infection. Caspase-1-activated IL-18 induces IFN-? to prime caspase-11 and rapidly clear B. thailandensis infection. In the absence of IL-18, bacterial burdens persist, eventually triggering other signals that induce IFN-?. Whereas IFN-? was essential, endogenous type I interferons were insufficient to prime caspase-11. Although mice transgenic for caspase-4, the human ortholog of caspase-11, cleared B. thailandensis in vivo, they did not strictly require IFN-? priming. Thus, caspase-1 provides priming signals upstream of caspase-11 but not caspase-4 during murine defense against a cytosol-invasive bacterium.

SUBMITTER: Aachoui Y

PROVIDER: S-EPMC4567510 | biostudies-literature | 2015 Sep

REPOSITORIES: biostudies-literature

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Canonical Inflammasomes Drive IFN-γ to Prime Caspase-11 in Defense against a Cytosol-Invasive Bacterium.

Aachoui Youssef Y Kajiwara Yuji Y Leaf Irina A IA Mao Dat D Ting Jenny P-Y JP Coers Jörn J Aderem Alan A Buxbaum Joseph D JD Miao Edward A EA

Cell host & microbe 20150827 3

The inflammatory caspases 1 and 11 are activated in response to different agonists and act independently to induce pyroptosis. In the context of IL-1β/IL-18 secretion, however, in vitro studies indicate that caspase-11 acts upstream of NLRP3 and caspase-1. By contrast, studying infection in vivo by the cytosol-invasive bacterium Burkholderia thailandensis, we find that caspase-1 activity is required upstream of caspase-11 to control infection. Caspase-1-activated IL-18 induces IFN-γ to prime cas ...[more]

PMID: 26320999

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Project description:Inflammasome activation is important for antimicrobial defense because it induces cell death and regulates the secretion of IL-1 family cytokines, which play a critical role in inflammatory responses. The inflammasome activates caspase-1 to process and secrete IL-1β. However, the mechanisms governing IL-1α release are less clear. Recently, a non-canonical inflammasome was described that activates caspase-11 and mediates pyroptosis and release of IL-1α and IL-1β. Caspase-11 activation in response to Gram-negative bacteria requires Toll-like receptor 4 (TLR4) and TIR-domain-containing adaptor-inducing interferon-β (TRIF)-dependent interferon production. Whether additional bacterial signals trigger caspase-11 activation is unknown. Many bacterial pathogens use specialized secretion systems to translocate effector proteins into the cytosol of host cells. These secretion systems can also deliver flagellin into the cytosol, which triggers caspase-1 activation and pyroptosis. However, even in the absence of flagellin, these secretion systems induce inflammasome activation and the release of IL-1α and IL-1β, but the inflammasome pathways that mediate this response are unclear. We observe rapid IL-1α and IL-1β release and cell death in response to the type IV or type III secretion systems of Legionella pneumophila and Yersinia pseudotuberculosis. Unlike IL-1β, IL-1α secretion does not require caspase-1. Instead, caspase-11 activation is required for both IL-1α secretion and cell death in response to the activity of these secretion systems. Interestingly, whereas caspase-11 promotes IL-1β release in response to the type IV secretion system through the NLRP3/ASC inflammasome, caspase-11-dependent release of IL-1α is independent of both the NAIP5/NLRC4 and NLRP3/ASC inflammasomes as well as TRIF and type I interferon signaling. Furthermore, we find both overlapping and non-redundant roles for IL-1α and IL-1β in mediating neutrophil recruitment and bacterial clearance in response to pulmonary infection by L. pneumophila. Our findings demonstrate that virulent, but not avirulent, bacteria trigger a rapid caspase-11-dependent innate immune response important for host defense.

Dataset Information

Canonical Inflammasomes Drive IFN-? to Prime Caspase-11 in Defense against a Cytosol-Invasive Bacterium.

Publications

Canonical Inflammasomes Drive IFN-γ to Prime Caspase-11 in Defense against a Cytosol-Invasive Bacterium.

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