Listeria monocytogenes-infected human peripheral blood mononuclear cells produce IL-1beta, depending on listeriolysin O and NLRP3

J Immunol. 2010 Jan 15;184(2):922-30. doi: 10.4049/jimmunol.0901346. Epub 2009 Dec 11.

Abstract

Different NOD-like receptors, including NLRP1, NLRP3, and NLRC4, as well as the recently identified HIN-200 protein, AIM2, form multiprotein complexes called inflammasomes, which mediate caspase-1-dependent processing of pro-IL-1beta. Listeria monocytogenes is an intracellular pathogen that is actively phagocytosed by monocytes/macrophages and subsequently escapes from the phagosome into the host cell cytosol, depending on its pore-forming toxin listeriolysin O (LLO). In this study, we demonstrate that human PBMCs produced mature IL-1beta when infected with wild-type L. monocytogenes or when treated with purified LLO. L. monocytogenes mutants lacking LLO or expressing a noncytolytic LLO as well as the avirulent Listeria innocua induced strongly impaired IL-1beta production. RNA interference and inhibitor experiments in human PBMCs as well as experiments in Nlrp3 and Rip2 knockout bone marrow-derived macrophages demonstrated that the Listeria-induced IL-1beta release was dependent on ASC, caspase-1, and NLRP3, whereas NOD2, Rip2, NLRP1, NLRP6, NLRP12, NLRC4, and AIM2 appeared to be dispensable. We found that L. monocytogenes-induced IL-1beta production was largely dependent on phagosomal acidification and cathepsin B release, whereas purified LLO activated an IL-1beta production independently of these mechanisms. Our results indicate that L. monocytogenes-infected human PBMCs produced IL-1beta, largely depending on an LLO-mediated phagosomal rupture and cathepsin B release, which is sensed by Nlrp3. In addition, an LLO-dependent but cathepsin B-independent NLRP3 activation might contribute to some extent to the IL-1beta production in L. monocytogenes-infected cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Bacterial Toxins
  • Carrier Proteins / physiology*
  • Cathepsin B / metabolism
  • Cell Line
  • Heat-Shock Proteins / physiology*
  • Hemolysin Proteins / physiology*
  • Humans
  • Interleukin-1beta / biosynthesis*
  • Leukocytes, Mononuclear / metabolism
  • Leukocytes, Mononuclear / microbiology*
  • Listeria monocytogenes / immunology*
  • Listeria monocytogenes / pathogenicity
  • Macrophages
  • Mice
  • Mice, Inbred C57BL
  • NLR Family, Pyrin Domain-Containing 3 Protein
  • Phagosomes

Substances

  • Bacterial Toxins
  • Carrier Proteins
  • Heat-Shock Proteins
  • Hemolysin Proteins
  • Interleukin-1beta
  • NLR Family, Pyrin Domain-Containing 3 Protein
  • NLRP3 protein, human
  • Cathepsin B
  • hlyA protein, Listeria monocytogenes