Calpain drives pyroptotic vimentin cleavage, intermediate filament loss, and cell rupture that mediates immunostimulation

Proc Natl Acad Sci U S A. 2019 Mar 12;116(11):5061-5070. doi: 10.1073/pnas.1818598116. Epub 2019 Feb 22.

Abstract

Pyroptosis is an inflammatory form of programmed cell death following cellular damage or infection. It is a lytic process driven by gasdermin D-mediated cellular permeabilization and presumed osmotic forces thought to induce swelling and rupture. We found that pyroptotic cells do not spontaneously rupture in culture but lose mechanical resilience. As a result, cells were susceptible to rupture by extrinsic forces, such as shear stress or compression. Cell analyses revealed that all major cytoskeleton components were disrupted during pyroptosis and that sensitivity to rupture was calpain-dependent and linked with cleavage of vimentin and loss of intermediate filaments. Moreover, while release of lactate dehydrogenase (LDH), HMGB1, and IL-1β occurred without rupture, rupture was required for release of large inflammatory stimuli-ASC specks, mitochondria, nuclei, and bacteria. Importantly, supernatants from ruptured cells were more immunostimulatory than those from nonruptured cells. These observations reveal undiscovered cellular events occurring during pyroptosis, define the mechanisms driving pyroptotic rupture, and highlight the immunologic importance of this event.

Keywords: calpain; intermediate filaments; pyroptosis; rupture; vimentin.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Alarmins / metabolism
  • CARD Signaling Adaptor Proteins / metabolism
  • Calpain / metabolism*
  • Caspase 1 / metabolism
  • Compressive Strength
  • Cytoskeleton / metabolism
  • Cytosol / metabolism
  • Humans
  • Immunization*
  • Inflammasomes
  • Intermediate Filaments / metabolism*
  • Neoplasm Proteins / metabolism
  • Pyroptosis*
  • Stress, Mechanical
  • THP-1 Cells
  • Vimentin / metabolism*

Substances

  • Alarmins
  • CARD Signaling Adaptor Proteins
  • GSDMD protein, human
  • Inflammasomes
  • Neoplasm Proteins
  • PYCARD protein, human
  • Vimentin
  • Calpain
  • Caspase 1