Mycobacterium abscessus activates the NLRP3 inflammasome via Dectin-1-Syk and p62/SQSTM1

Immunol Cell Biol. 2012 Jul;90(6):601-10. doi: 10.1038/icb.2011.72. Epub 2011 Aug 30.

Abstract

Numerous atypical mycobacteria, including Mycobacterium abscessus (Mabc), cause nontuberculous mycobacterial infections, which present a serious public health threat. Inflammasome activation is involved in host defense and the pathogenesis of autoimmune diseases. However, inflammasome activation has not been widely characterized in human macrophages infected with atypical mycobacteria. Here, we demonstrate that Mabc robustly activates the nucleotide binding and oligomerization domain-like receptor family pyrin domain containing 3 (NLRP3) inflammasome via dectin-1/Syk-dependent signaling and the cytoplasmic scaffold protein p62/SQSTM1 (p62) in human macrophages. Both dectin-1 and Toll-like receptor 2 (TLR2) were required for Mabc-induced mRNA expression of pro-interleukin (IL)-1β, cathelicidin human cationic antimicrobial protein-18/LL-37 and β-defensin 4 (DEFB4). Dectin-1-dependent Syk signaling, but not that of MyD88, led to the activation of caspase-1 and secretion of IL-1β through the activation of an NLRP3/apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC) inflammasome. Additionally, potassium efflux was required for Mabc-induced NLRP3/ASC inflammasome activation. Furthermore, Mabc-induced p62 expression was critically involved in NLRP3 inflammasome activation in human macrophages. Finally, NLRP3/ASC was critical for the inflammasome in antimicrobial responses to Mabc infection. Taken together, these data demonstrate the induction mechanism of the NLRP3/ASC inflammasome and its role in innate immunity to Mabc infection.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptor Proteins, Signal Transducing / metabolism*
  • Antimicrobial Cationic Peptides
  • Carrier Proteins / metabolism*
  • Caspase 1 / genetics
  • Caspase 1 / metabolism
  • Cathelicidins / biosynthesis
  • Cell Line
  • Humans
  • Inflammasomes / immunology*
  • Inflammasomes / metabolism
  • Interleukin-1beta / biosynthesis
  • Interleukin-1beta / genetics
  • Intracellular Signaling Peptides and Proteins / metabolism*
  • Lectins, C-Type / metabolism*
  • Macrophages / immunology*
  • Macrophages / microbiology*
  • Mycobacterium Infections, Nontuberculous / immunology
  • Myeloid Differentiation Factor 88
  • NLR Family, Pyrin Domain-Containing 3 Protein
  • Nontuberculous Mycobacteria / immunology*
  • Potassium / metabolism
  • Protein-Tyrosine Kinases / metabolism*
  • RNA Interference
  • RNA, Small Interfering
  • Sequestosome-1 Protein
  • Signal Transduction
  • Syk Kinase
  • Toll-Like Receptor 2 / genetics
  • Toll-Like Receptor 2 / metabolism
  • beta-Defensins / biosynthesis

Substances

  • Adaptor Proteins, Signal Transducing
  • Antimicrobial Cationic Peptides
  • CLEC7A protein, human
  • Carrier Proteins
  • Cathelicidins
  • DEFB4A protein, human
  • Inflammasomes
  • Interleukin-1beta
  • Intracellular Signaling Peptides and Proteins
  • Lectins, C-Type
  • MYD88 protein, human
  • Myeloid Differentiation Factor 88
  • NLR Family, Pyrin Domain-Containing 3 Protein
  • NLRP3 protein, human
  • RNA, Small Interfering
  • SQSTM1 protein, human
  • Sequestosome-1 Protein
  • Toll-Like Receptor 2
  • beta-Defensins
  • ropocamptide
  • Protein-Tyrosine Kinases
  • SYK protein, human
  • Syk Kinase
  • Caspase 1
  • Potassium