Localization and Functionality of the Inflammasome in Neutrophils

Research output: Contribution to journalJournal articleResearchpeer-review

  • Martina Bakele
  • Melanie Joos
  • Sofia Burdi
  • Nicolas Allgaier
  • Simone Pöschel
  • Birgit Fehrenbacher
  • Martin Schaller
  • Veronica Marcos
  • Jasmin Kümmerle-Deschner
  • Nikolaus Rieber
  • Niels Borregaard
  • Amir Yazdi
  • Andreas Hector
  • Dominik Hartl

Neutrophils represent the major fraction of circulating immune cells and are rapidly recruited to sites of infection and inflammation. The inflammasome is a multiprotein complex that regulates the generation of IL-1 family proteins. The precise subcellular localization and functionality of the inflammasome in human neutrophils are poorly defined. Here we demonstrate that highly purified human neutrophils express key components of the NOD-like receptor family, pyrin domain containing 3 (NLRP3), and absent in melanoma 2 (AIM2) inflammasomes, particularly apoptosis-associated speck-like protein containing a CARD (ASC), AIM2, and caspase-1. Subcellular fractionation and microscopic analyses further showed that inflammasome components were localized in the cytoplasm and also noncanonically in secretory vesicle and tertiary granule compartments. Whereas IL-1β and IL-18 were expressed at the mRNA level and released as protein, highly purified neutrophils neither expressed nor released IL-1α at baseline or upon stimulation. Upon inflammasome activation, highly purified neutrophils released substantially lower levels of IL-1β protein compared with partially purified neutrophils. Serine proteases and caspases were differentially involved in IL-1β release, depending on the stimulus. Spontaneous activation of the NLRP3 inflammasome in neutrophils in vivo affected IL-1β, but not IL-18 release. In summary, these studies show that human neutrophils express key components of the inflammasome machinery in distinct intracellular compartments and release IL-1β and IL-18, but not IL-1α or IL-33 protein. Targeting the neutrophil inflammasome may represent a future therapeutic strategy to modulate neutrophilic inflammatory diseases, such as cystic fibrosis, rheumatoid arthritis, or sepsis.

Original languageEnglish
JournalThe Journal of Biological Chemistry
Volume289
Issue number8
Pages (from-to)5320-5329
Number of pages10
ISSN0021-9258
DOIs
Publication statusPublished - 21 Feb 2014

    Research areas

  • Adult, Carrier Proteins, Caspases, Cell Compartmentation, Gene Expression Profiling, Humans, Inflammasomes, Interleukins, Intracellular Space, Neutrophils, Protein Transport, RNA, Messenger, Serine Proteases, Subcellular Fractions

ID: 138215373