Cytosolic double-stranded RNA activates the NLRP3 inflammasome via MAVS-induced membrane permeabilization and K+ efflux

J Immunol. 2014 Oct 15;193(8):4214-4222. doi: 10.4049/jimmunol.1400582. Epub 2014 Sep 15.

Abstract

The nucleotide-binding oligomerization domain-like receptor pyrin domain-containing 3 (Nlrp3) inflammasome plays an important role in inflammation by controlling the maturation and secretion of the cytokines IL-1β and IL-18 in response to multiple stimuli including pore-forming toxins, particulate matter, and ATP. Although the pathways activated by the latter stimuli lead to a decrease in intracellular K(+) concentration, which is required for inflammasome activation, the mechanism by which microbial RNA activates Nlrp3, remains poorly understood. In this study, we found that cytosolic poly(I:C), but not total RNA from healthy macrophages, macrophages undergoing pyroptosis, or mitochondrial RNA, induces caspase-1 activation and IL-1β release through the Nlrp3 inflammasome. Experiments with macrophages deficient in Tlr3, Myd88, or Trif, indicate that poly(I:C) induces Nlrp3 activation independently of TLR signaling. Further analyses revealed that the cytosolic sensors Rig-I and melanoma differentiation-associated gene 5 act redundantly via the common adaptor mitochondrial antiviral signaling (Mavs) to induce Nlrp3 activation in response to poly(I:C), but not ATP or nigericin. Mechanistically, Mavs triggered membrane permeabilization and K(+) efflux independently of the inflammasome which were required for poly(I:C)-induced Nlrp3 activation. We conclude that poly (I:C) activates the inflammasome through an Mavs-dependent surveillance pathway that converges into a common K(+) lowering step in the cytosol that is essential for the induction of Nlrp3 activation.

Publication types

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

MeSH terms

  • Adaptor Proteins, Signal Transducing / immunology*
  • Adaptor Proteins, Vesicular Transport / genetics
  • Animals
  • Carrier Proteins / immunology*
  • Caspase 1 / immunology
  • Cytosol
  • DEAD Box Protein 58
  • DEAD-box RNA Helicases / immunology
  • Inflammation / immunology
  • Interferon-Induced Helicase, IFIH1
  • Interleukin-18 / biosynthesis
  • Interleukin-18 / metabolism
  • Interleukin-1beta / biosynthesis
  • Interleukin-1beta / metabolism
  • Ion Transport
  • Macrophages / immunology
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Myeloid Differentiation Factor 88 / genetics
  • NLR Family, Pyrin Domain-Containing 3 Protein
  • Poly I-C / immunology
  • Potassium / metabolism*
  • RNA, Bacterial / immunology
  • RNA, Double-Stranded / immunology*
  • RNA, Viral / immunology
  • Signal Transduction / immunology
  • Toll-Like Receptor 3 / genetics

Substances

  • Adaptor Proteins, Signal Transducing
  • Adaptor Proteins, Vesicular Transport
  • Carrier Proteins
  • IL1B protein, mouse
  • IPS-1 protein, mouse
  • Interleukin-18
  • Interleukin-1beta
  • Myd88 protein, mouse
  • Myeloid Differentiation Factor 88
  • NLR Family, Pyrin Domain-Containing 3 Protein
  • Nlrp3 protein, mouse
  • RNA, Bacterial
  • RNA, Double-Stranded
  • RNA, Viral
  • TICAM-1 protein, mouse
  • TLR3 protein, mouse
  • Toll-Like Receptor 3
  • Caspase 1
  • Ddx58 protein, mouse
  • Ifih1 protein, mouse
  • DEAD Box Protein 58
  • DEAD-box RNA Helicases
  • Interferon-Induced Helicase, IFIH1
  • Poly I-C
  • Potassium