Non-transcriptional regulation of NLRP3 inflammasome signaling by IL-4

Immunol Cell Biol. 2015 Jul;93(6):591-9. doi: 10.1038/icb.2014.125. Epub 2015 Jan 20.

Abstract

Th2 cytokine IL-4 has been previously shown to suppress the production of proinflammatory cytokines in monocytes. However, the underlying molecular mechanism by which IL-4 signaling antagonizes proinflammatory responses is poorly characterized. In particular, whether IL-4 can modulate inflammasome signaling remains unknown. Here, we provide evidence that IL-4 suppresses NLRP3-dependent caspase-1 activation and the subsequent IL-1β secretion but does not inhibit absent in melanoma 2 (AIM2)- or NLRC4 (NOD-like receptor family, CARD domain-containing 4)-dependent caspase-1 activation in THP-1 and mouse bone marrow-derived macrophages. Upon lipopolysaccharide (LPS) or LPS/ATP stimulation, IL-4 markedly inhibited the assembly of NLRP3 inflammasome, including NLRP3-dependent ASC (apoptosis-associated speck-like protein containing a caspase recruitment domain) oligomerization, NLRP3-ASC interaction and NLRP3 speck-like oligomeric structure formation. The negative regulation of NLRP3 inflammasome by IL-4 was not due to the impaired mRNA or protein production of NLRP3 and proinflammatory cytokines. Supporting this observation, IL-4 attenuated NLRP3 inflammasome activation even in reconstituted NLRP3-expressing macrophages in which NLRP3 expression is not transcriptionally regulated by TLR-NF-κB signaling. Furthermore, the IL-4-mediated suppression of NLRP3 inflammasome was independent of STAT6-dependent transcription and mitochondrial reactive oxygen species (ROS). Instead, IL-4 inhibited subcellular redistribution of NLRP3 into mitochondria and microtubule polymerization upon NLRP3-activating stimulation. Our results collectively suggest that IL-4 could suppress NLRP3 inflammasome activation in a transcription-independent manner, thus providing an endogenous regulatory machinery to prevent excessive inflammasome activation.

Publication types

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

MeSH terms

  • Animals
  • Carrier Proteins / metabolism*
  • Caspase 1 / metabolism
  • Cytokines / genetics
  • Cytokines / metabolism
  • Enzyme Activation / drug effects
  • Humans
  • Inflammasomes / metabolism*
  • Inflammation Mediators / metabolism
  • Interleukin-4 / metabolism*
  • Interleukin-4 / pharmacology
  • Intracellular Space
  • Lipopolysaccharides / immunology
  • Lipopolysaccharides / pharmacology
  • Macrophages / drug effects
  • Macrophages / immunology
  • Macrophages / metabolism
  • Mice
  • NLR Family, Pyrin Domain-Containing 3 Protein
  • Protein Binding
  • Protein Transport
  • Reactive Oxygen Species / metabolism
  • STAT6 Transcription Factor / metabolism
  • Signal Transduction* / drug effects
  • Transcription, Genetic / drug effects

Substances

  • Carrier Proteins
  • Cytokines
  • Inflammasomes
  • Inflammation Mediators
  • Lipopolysaccharides
  • NLR Family, Pyrin Domain-Containing 3 Protein
  • NLRP3 protein, human
  • Reactive Oxygen Species
  • STAT6 Transcription Factor
  • Interleukin-4
  • Caspase 1