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A multicomponent toxin from Bacillus cereus incites inflammation and shapes host outcome via the NLRP3 inflammasome.

ABSTRACT: Host recognition of microbial components is essential in mediating an effective immune response. Cytosolic bacteria must secure entry into the host cytoplasm to facilitate replication and, in doing so, liberate microbial ligands that activate cytosolic innate immune sensors and the inflammasome. Here, we identified a multicomponent enterotoxin, haemolysin BL (HBL), that engages activation of the inflammasome. This toxin is highly conserved among the human pathogen Bacillus cereus. The three subunits of HBL bind to the cell membrane in a linear order, forming a lytic pore and inducing activation of the NLRP3 inflammasome, secretion of interleukin-1? and interleukin-18, and pyroptosis. Mechanistically, the HBL-induced pore results in the efflux of potassium and triggers the activation of the NLRP3 inflammasome. Furthermore, HBL-producing B. cereus induces rapid inflammasome-mediated mortality. Pharmacological inhibition of the NLRP3 inflammasome using MCC950 prevents B. cereus-induced lethality. Overall, our results reveal that cytosolic sensing of a toxin is central to the innate immune recognition of infection. Therapeutic modulation of this pathway enhances host protection against deadly bacterial infections.

SUBMITTER: Mathur A

PROVIDER: S-EPMC7685251 | biostudies-literature | 2019 Feb

REPOSITORIES: biostudies-literature

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A multicomponent toxin from Bacillus cereus incites inflammation and shapes host outcome via the NLRP3 inflammasome.

Mathur Anukriti A Feng Shouya S Hayward Jenni A JA Ngo Chinh C Fox Daniel D Atmosukarto Ines I II Price Jason D JD Schauer Kristina K Märtlbauer Erwin E Robertson Avril A B AAB Burgio Gaetan G Fox Edward M EM Leppla Stephen H SH Kaakoush Nadeem O NO Man Si Ming SM

Nature microbiology 20181210 2

Host recognition of microbial components is essential in mediating an effective immune response. Cytosolic bacteria must secure entry into the host cytoplasm to facilitate replication and, in doing so, liberate microbial ligands that activate cytosolic innate immune sensors and the inflammasome. Here, we identified a multicomponent enterotoxin, haemolysin BL (HBL), that engages activation of the inflammasome. This toxin is highly conserved among the human pathogen Bacillus cereus. The three subu ...[more]

PMID: 30531979

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Project description:The NLRP3 (NALP3, cryopyrin) inflammasome, a key component of the innate immune system, facilitates caspase-1 and interleukin (IL)-1? processing, which amplifies the inflammatory response. Here, we investigated whether NLRP3 knockdown decreases neutrophil infiltration, reduces brain edema, and improves neurological function in an intracerebral hemorrhage (ICH) mouse model. We also determined whether mitochondrial reactive oxygen species (ROS) governed by mitochondrial permeability transition pores (mPTPs) would trigger NLRP3 inflammasome activation following ICH.ICH was induced by injecting autologous arterial blood (30?l) into a mouse brain. NLRP3 small interfering RNAs were administered 24 hours before ICH. A mPTP inhibitor (TRO-19622) or a specific mitochondria ROS scavenger (Mito-TEMPO) was coinjected with the blood. In naive animals, rotenone, which is a respiration chain complex I inhibitor, was applied to induce mitochondrial ROS production, and followed by TRO-19622 or Mito-TEMPO treatment. Neurological deficits, brain edema, enzyme-linked immunosorbent assay, Western blot, in vivo chemical cross-linking, ROS assay, and immunofluorescence were evaluated.ICH activated the NLRP3 inflammasome. NLRP3 knockdown reduced brain edema and decreased myeloperoxidase (MPO) levels at 24 hours, and improved neurological functions from 24 to 72 hours following ICH. TRO-19622 or Mito-TEMPO reduced ROS, NLRP3 inflammasome components, and MPO levels following ICH. In naive animals, rotenone administration induced mPTP formation, ROS generation, and NLRP3 inflammasome activation, which were then reduced by TRO-19622 or Mito-TEMPO.The NLRP3 inflammasome amplified the inflammatory response by releasing IL-1? and promoting neutrophil infiltration following ICH. Mitochondria ROS may be a major trigger of NLRP3 inflammasome activation. The results of our study suggest that the inhibition of the NLRP3 inflammasome may effectively reduce the inflammatory response following ICH.ANN NEUROL 2014;75:209-219.

Dataset Information

A multicomponent toxin from Bacillus cereus incites inflammation and shapes host outcome via the NLRP3 inflammasome.

Publications

A multicomponent toxin from Bacillus cereus incites inflammation and shapes host outcome via the NLRP3 inflammasome.

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