Entamoeba histolytica-induced IL-1β secretion is dependent on caspase-4 and gasdermin D

Mucosal Immunol. 2019 Mar;12(2):323-339. doi: 10.1038/s41385-018-0101-9. Epub 2018 Oct 25.

Abstract

During invasion, Entamoeba histolytica (Eh) encounter macrophages and activate them to elicit tissue damaging pro-inflammatory responses. When Eh binds macrophages via the Gal-lectin, surface EhCP-A5 RGD sequence ligates α5β1 integrin to activate caspase-1 in a complex known as the NLRP3 inflammasome. In this study, we investigated Eh requirements underlying macrophage caspase-4 and -1 activation and the role caspase-4 and gasdermin D (GSDMD) play in augmenting pro-inflammatory cytokine responses. Caspase-4 activation was similar to caspase-1 requiring live Eh attachment via the Gal-lectin and EhCP-A5. However, unlike caspase-1, caspase-4 activation was independent of ASC and NLRP3. Using CRISPR/Cas9 gene editing of caspase-4 and -1 and GSDMD, we determined that caspase-1 and bioactive IL-1β release was highly dependent on caspase-4 activation and cleavage of GSDMD in response to Eh. Formaldehyde cross-linking to stabilize protein-protein interactions in transfected COS-7 cells stimulated with Eh revealed that caspase-4 specifically interacted with caspase-1 in a protein complex that enhanced the cleavage of caspase-1 CARD domains to augment IL-1β release. Activated caspase-4 and -1 cleaved GSDMD liberating the N-terminal p30 pore-forming fragment that caused the secretion of IL-1β. These findings reveal a novel role for caspase-4 as a sensor molecule to amplify pro-inflammatory responses when macrophage encounters Eh.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • COS Cells
  • Caspase 1 / metabolism
  • Caspases, Initiator / genetics
  • Caspases, Initiator / metabolism*
  • Chlorocebus aethiops
  • Clustered Regularly Interspaced Short Palindromic Repeats
  • Entamoeba histolytica / physiology*
  • Entamoebiasis / immunology*
  • Humans
  • Integrin alpha5beta1 / metabolism
  • Interleukin-1beta / metabolism*
  • Intracellular Signaling Peptides and Proteins
  • Macrophages / immunology*
  • Neoplasm Proteins / metabolism*
  • Phosphate-Binding Proteins
  • THP-1 Cells

Substances

  • GSDMD protein, human
  • Integrin alpha5beta1
  • Interleukin-1beta
  • Intracellular Signaling Peptides and Proteins
  • Neoplasm Proteins
  • Phosphate-Binding Proteins
  • CASP4 protein, human
  • Caspases, Initiator
  • Caspase 1