Evolution of inflammasome functions in vertebrates: Inflammasome and caspase-1 trigger fish macrophage cell death but are dispensable for the processing of IL-1β

Innate Immun. 2012 Dec;18(6):815-24. doi: 10.1177/1753425912441956. Epub 2012 Mar 28.

Abstract

Members of the nucleotide binding and oligomerization domain-like receptors (NLRs) and the PYD and CARD domain containing adaptor protein (PYCARD) assemble into multi-protein platforms, termed inflammasomes, to mediate in the activation of caspase-1 and the subsequent secretion of IL-1β and IL-18, and the induction of pyroptotic cell death. While the recognition site for caspase-1 is well conserved in mammals, most of the non-mammalian IL-1β genes cloned so far lack this conserved site. We report here that stimulation or infection of seabream macrophages (MØ) led to the caspase-1-independent processing and release of IL-1β. In addition, several classical activators of the NLRP3 inflammasome failed to activate caspase-1 and to induce the processing and release of IL-1β. Furthermore, the processing of IL-1β in seabream MØ is not prevented by caspase-1 or pan-caspase inhibitors, and recombinant seabream caspase-1 failed to process IL-1β. However, the pharmacological inhibition of caspase-1 impaired Salmonella enterica sv. Typhimurium-induced cell death. These results suggest a role for the inflammasome and caspase-1 in the regulation of pyroptotic cell death in fish and support the idea that its use as a molecular platform for the processing of pro-inflammatory cytokines arose after the divergence of fish and tetrapods.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Chloromethyl Ketones / pharmacology
  • Animals
  • Biological Evolution
  • CARD Signaling Adaptor Proteins
  • Caspase 1 / immunology
  • Caspase 1 / metabolism*
  • Cell Death / drug effects
  • Cell Death / immunology
  • Cells, Cultured
  • Cytoskeletal Proteins / immunology
  • DNA, Bacterial / immunology
  • Flagellin / immunology
  • Inflammasomes / drug effects
  • Inflammasomes / immunology*
  • Interleukin-1beta / immunology
  • Interleukin-1beta / metabolism*
  • Macrophages / drug effects
  • Macrophages / immunology*
  • Macrophages / microbiology
  • Protein Multimerization
  • Protein Processing, Post-Translational / drug effects
  • Protein Processing, Post-Translational / immunology
  • Salmonella Infections, Animal / immunology*
  • Salmonella typhi / immunology*
  • Sea Bream / immunology*
  • Sea Bream / microbiology

Substances

  • Amino Acid Chloromethyl Ketones
  • CARD Signaling Adaptor Proteins
  • Cytoskeletal Proteins
  • DNA, Bacterial
  • Inflammasomes
  • Interleukin-1beta
  • N-acetyl-tyrosyl-valyl-alanyl-aspartyl chloromethyl ketone
  • PYCARD protein, human
  • Flagellin
  • Caspase 1