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Evaluation of Caspase Activation to Assess Innate Immune Cell Death
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Coordinated host responses during pyroptosis: caspase-1-dependent lysosome exocytosis and inflammatory cytokine

Tessa Bergsbaken1, Susan L Fink, Andreas B den Hartigh

  • 1Department of Microbiology, University of Washington, Seattle, WA 98195, USA.

Journal of Immunology (Baltimore, Md. : 1950)
|August 2, 2011
PubMed

Insights

Caspase-1 activation triggers pyroptosis, a cell death process involving cell lysis and inflammation. This study reveals two distinct pathways initiated by caspase-1: lysosome exocytosis and a separate cytokine release pathway, both enhancing pyroptosis's antimicrobial functions.

Area of Science:

  • Cellular Biology
  • Immunology
  • Microbiology

Background:

  • Caspase-1 activation induces pyroptosis, a lytic cell death pathway.
  • Pyroptosis is characterized by inflammatory cytokine release and cell lysis.
  • Nucleotide-binding oligomerization domain-like receptors (NLRs) like NLRC4, NLRP1b, and NLRP3 activate caspase-1.

Purpose of the Study:

  • To investigate the secretion pathways initiated by caspase-1 during pyroptosis.
  • To elucidate the role of lysosome exocytosis in pyroptosis and cytokine release.
  • To understand how these pathways contribute to the antimicrobial nature of pyroptosis.

Main Methods:

  • Studied caspase-1 activation triggered by various NLRs.
  • Investigated lysosome exocytosis and its relation to cellular calcium levels and membrane permeability.
  • Assessed the impact of blocking lysosome exocytosis on cytokine processing and release.

Main Results:

  • Caspase-1 activation leads to lysosome exocytosis, involving increased membrane permeability and intracellular calcium.
  • Blocking lysosome exocytosis did not affect IL-1β and IL-18 processing or release.
  • Two conserved secretion pathways are initiated by caspase-1: lysosome exocytosis and a parallel cytokine release pathway.

Conclusions:

  • Caspase-1 orchestrates at least two distinct secretion pathways during pyroptosis.
  • Lysosome exocytosis and a separate cytokine release pathway contribute to pyroptosis's antimicrobial defense.
  • These findings offer insights into the complex mechanisms of inflammatory cell death and host defense.

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