title: The NALP3 inflammasome is involved in neurotoxic prion peptide-induced microglial activation.
abstract: BACKGROUND
  Prion diseases are neurodegenerative disorders characterized by the accumulation of an abnormal disease-associated prion protein, PrPSc. In prion-infected brains, activated microglia are often present in the vicinity of PrPSc aggregates, and microglial activation is thought to play a key role in the pathogenesis of prion diseases. Although interleukin (IL)-1β release by prion-induced microglia has been widely reported, the mechanism by which primed microglia become activated and secrete IL-1β in prion diseases has not yet been elucidated. In this study, we investigated the role of the NACHT, LRR and PYD domains-containing protein (NALP)3 inflammasome in IL-1β release from lipopolysaccharide (LPS)-primed microglia after exposure to a synthetic neurotoxic prion fragment (PrP106-126).
  
  
  METHODS
  The inflammasome components NALP3 and apoptosis-associated speck-like protein (ASC) were knocked down by gene silencing. IL-1β production was assessed using ELISA. The mRNA expression of NALP3, ASC, and pro-inflammatory factors was measured by quantitative PCR. Western blot analysis was used to detect the protein level of NALP3, ASC, caspase-1 and nuclear factor-κB.
  
  
  RESULTS
  We found that that PrP106-126-induced IL-1β release depends on NALP3 inflammasome activation, that inflammasome activation is required for the synthesis of pro-inflammatory and chemotactic factors by PrP106-126-activated microglia, that inhibition of NF-κB activation abrogated PrP106-126-induced NALP3 upregulation, and that potassium efflux and production of reactive oxygen species were implicated in PrP106-126-induced NALP3 inflammasome activation in microglia.
  
  
  CONCLUSIONS
  We conclude that the NALP3 inflammasome is involved in neurotoxic prion peptide-induced microglial activation. To our knowledge, this is the first time that strong evidence for the involvement of NALP3 inflammasome in prion-associated inflammation has been found.
authors.affiliation: State Key Laboratories for Agrobiotechnology, Ministry of Agriculture, National Animal Transmissible Spongiform Encephalopathy Laboratory, College of Veterinary Medicine, China Agricultural University, Beijing, 100193, China.
authors.forename: Fushan
authors.initials: F
authors.lastname: Shi
authors.forename: Lifeng
authors.initials: L
authors.lastname: Yang
authors.forename: Mohammed
authors.initials: M
authors.lastname: Kouadir
authors.forename: Yang
authors.initials: Y
authors.lastname: Yang
authors.forename: Jihong
authors.initials: J
authors.lastname: Wang
authors.forename: Xiangmei
authors.initials: X
authors.lastname: Zhou
authors.forename: Xiaomin
authors.initials: X
authors.lastname: Yin
authors.forename: Deming
authors.initials: D
authors.lastname: Zhao
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D002352:Carrier Proteins / Q000502:physiology*; D002478:Cells, Cultured; D058847:Inflammasomes / Q000502:physiology*; D053583:Interleukin-1beta / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D017628:Microglia / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology*; D000071199:NLR Family, Pyrin Domain-Containing 3 Protein; D010446:Peptide Fragments / Q000633:toxicity*; D011328:Prions / Q000633:toxicity*
chemical_list: D002352:Carrier Proteins; D058847:Inflammasomes; D053583:Interleukin-1beta; D000071199:NLR Family, Pyrin Domain-Containing 3 Protein; C492716:Nlrp3 protein, mouse; D010446:Peptide Fragments; D011328:Prions; C082632:prion protein (106-126)