title: NLRP3 inflammasome-mediated neutrophil recruitment and hypernociception depend on leukotriene B(4)  in a murine model of gout.
abstract: OBJECTIVE
  Deposition of monosodium urate monohydrate (MSU) crystals in the joints promotes an intense inflammatory response and joint dysfunction. This study evaluated the role of the NLRP3 inflammasome and 5-lipoxygenase (5-LOX)-derived leukotriene B(4)  (LTB(4) ) in driving tissue inflammation and hypernociception in a murine model of gout.
  
  
  METHODS
  Gout was induced by injecting MSU crystals into the joints of mice. Wild-type mice and mice deficient in NLRP3, ASC, caspase 1, interleukin-1β (IL-1β), IL-1 receptor type I (IL-1RI), IL-18R, myeloid differentiation factor 88 (MyD88), or 5-LOX were used. Evaluations were performed to assess neutrophil influx, LTB(4)  activity, cytokine (IL-1β, CXCL1) production (by enzyme-linked immunosorbent assay), synovial microvasculature cell adhesion (by intravital microscopy), and hypernociception. Cleaved caspase 1 and production of reactive oxygen species (ROS) were analyzed in macrophages by Western blotting and fluorometric assay, respectively.
  
  
  RESULTS
  Injection of MSU crystals into the knee joints of mice induced neutrophil influx and neutrophil-dependent hypernociception. MSU crystal-induced neutrophil influx was CXCR2-dependent and relied on the induction of CXCL1 in an NLRP3/ASC/caspase 1/IL-1β/MyD88-dependent manner. LTB(4)  was produced rapidly after injection of MSU crystals, and this was necessary for caspase 1-dependent IL-1β production and consequent release of CXCR2-acting chemokines in vivo. In vitro, macrophages produced LTB(4)  after MSU crystal injection, and LTB(4)  was relevant in the MSU crystal-induced maturation of IL-1β. Mechanistically, LTB(4)  drove MSU crystal-induced production of ROS and ROS-dependent activation of the NLRP3 inflammasome.
  
  
  CONCLUSIONS
  These results reveal the role of the NLRP3 inflammasome in mediating MSU crystal-induced inflammation and dysfunction of the joints, and highlight a previously unrecognized role of LTB(4)  in driving NLRP3 inflammasome activation in response to MSU crystals, both in vitro and in vivo.
authors.affiliation: Universidade Federal de Minas Gerais, Minas Gerais, Brazil.
authors.forename: Flávio A
authors.initials: FA
authors.lastname: Amaral
authors.forename: Vivian V
authors.initials: VV
authors.lastname: Costa
authors.forename: Livia D
authors.initials: LD
authors.lastname: Tavares
authors.forename: Daniela
authors.initials: D
authors.lastname: Sachs
authors.forename: Fernanda M
authors.initials: FM
authors.lastname: Coelho
authors.forename: Caio T
authors.initials: CT
authors.lastname: Fagundes
authors.forename: Frederico M
authors.initials: FM
authors.lastname: Soriani
authors.forename: Tatiana N
authors.initials: TN
authors.lastname: Silveira
authors.forename: Larissa D
authors.initials: LD
authors.lastname: Cunha
authors.forename: Dario S
authors.initials: DS
authors.lastname: Zamboni
authors.forename: Valerie
authors.initials: V
authors.lastname: Quesniaux
authors.forename: Raphael S
authors.initials: RS
authors.lastname: Peres
authors.forename: Thiago M
authors.initials: TM
authors.lastname: Cunha
authors.forename: Fernando Q
authors.initials: FQ
authors.lastname: Cunha
authors.forename: Bernhard
authors.initials: B
authors.lastname: Ryffel
authors.forename: Daniele G
authors.initials: DG
authors.lastname: Souza
authors.forename: Mauro M
authors.initials: MM
authors.lastname: Teixeira
mesh_terms: D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism*; D020170:Caspase 1 / Q000378:metabolism; D016207:Cytokines / Q000378:metabolism; D006073:Gout / Q000139:chemically induced / Q000276:immunology / Q000378:metabolism*; D006930:Hyperalgesia / Q000276:immunology / Q000378:metabolism*; D058847:Inflammasomes / Q000276:immunology / Q000378:metabolism*; D007249:Inflammation / Q000276:immunology / Q000378:metabolism; D053583:Interleukin-1beta / Q000378:metabolism; D007975:Leukotriene B4 / Q000276:immunology / Q000378:metabolism*; D008264:Macrophages / Q000276:immunology / Q000378:metabolism; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D000071199:NLR Family, Pyrin Domain-Containing 3 Protein; D020556:Neutrophil Infiltration / Q000502:physiology*; D009504:Neutrophils / Q000276:immunology / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism; D013583:Synovial Membrane / Q000276:immunology / Q000378:metabolism; D014527:Uric Acid / Q000494:pharmacology
chemical_list: D002352:Carrier Proteins; D016207:Cytokines; D058847:Inflammasomes; D053583:Interleukin-1beta; D000071199:NLR Family, Pyrin Domain-Containing 3 Protein; C492716:Nlrp3 protein, mouse; D017382:Reactive Oxygen Species; D007975:Leukotriene B4; D014527:Uric Acid; D020170:Caspase 1