N-GSDMD trafficking to neutrophil organelles facilitates IL-1β release independently of plasma membrane pores and pyroptosis

Nat Commun. 2020 May 5;11(1):2212. doi: 10.1038/s41467-020-16043-9.

Abstract

Gasdermin-D (GSDMD) in inflammasome-activated macrophages is cleaved by caspase-1 to generate N-GSDMD fragments. N-GSDMD then oligomerizes in the plasma membrane (PM) to form pores that increase membrane permeability, leading to pyroptosis and IL-1β release. In contrast, we report that although N-GSDMD is required for IL-1β secretion in NLRP3-activated human and murine neutrophils, N-GSDMD does not localize to the PM or increase PM permeability or pyroptosis. Instead, biochemical and microscopy studies reveal that N-GSDMD in neutrophils predominantly associates with azurophilic granules and LC3+ autophagosomes. N-GSDMD trafficking to azurophilic granules causes leakage of neutrophil elastase into the cytosol, resulting in secondary cleavage of GSDMD to an alternatively cleaved N-GSDMD product. Genetic analyses using ATG7-deficient cells indicate that neutrophils secrete IL-1β via an autophagy-dependent mechanism. These findings reveal fundamental differences in GSDMD trafficking between neutrophils and macrophages that underlie neutrophil-specific functions during inflammasome activation.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Autophagosomes / metabolism
  • Autophagy / genetics
  • Caspase 1 / metabolism
  • Cell Membrane / metabolism*
  • Cell Membrane Permeability / genetics
  • Humans
  • Inflammasomes / metabolism
  • Interleukin-1beta / metabolism*
  • Intracellular Signaling Peptides and Proteins / genetics
  • Intracellular Signaling Peptides and Proteins / metabolism*
  • Leukocyte Elastase / genetics
  • Leukocyte Elastase / metabolism
  • Macrophages / metabolism
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Neutrophils / metabolism*
  • Organelles / metabolism*
  • Phosphate-Binding Proteins / genetics
  • Phosphate-Binding Proteins / metabolism*
  • Protein Transport
  • Pyroptosis / genetics

Substances

  • GSDMD protein, human
  • IL1B protein, human
  • Inflammasomes
  • Interleukin-1beta
  • Intracellular Signaling Peptides and Proteins
  • Phosphate-Binding Proteins
  • Leukocyte Elastase
  • Caspase 1