title: Hyaluronan activation of the Nlrp3 inflammasome contributes to the development of airway hyperresponsiveness.
abstract: BACKGROUND
  The role of the Nlrp3 inflammasome in nonallergic airway hyperresponsiveness (AHR) has not previously been reported. Recent evidence supports both interleukin (IL) 1β and short fragments of hyaluronan (HA) as contributors to the biological response to inhaled ozone.
  
  
  OBJECTIVE
  Because extracellular secretion of IL-1β requires activation of the inflammasome, we investigated the role of the inflammasome proteins ASC, caspase1, and Nlrp3 in the biological response to ozone and HA.
  
  
  METHODS
  C57BL/6J wild-type mice and mice deficient in ASC, caspase1, or Nlrp3 were exposed to ozone (1 ppm for 3 hr) or HA followed by analysis of airway resistance, cellular inflammation, and total protein and cytokines in bronchoalveolar lavage fluid (BALF). Transcription levels of IL-1β and IL-18 were determined in two populations of lung macrophages. In addition, we examined levels of cleaved caspase1 and cleaved IL-1β as markers of inflammasome activation in isolated alveolar macrophages harvested from BALF from HA-treated mice.
  
  
  RESULTS
  We observed that genes of the Nlrp3 inflammasome were required for development of AHR following exposure to either ozone or HA fragments. These genes are partially required for the cellular inflammatory response to ozone. The expression of IL-1β mRNA in alveolar macrophages was up-regulated after either ozone or HA challenge and was not dependent on the Nlrp3 inflammasome. However, soluble levels of IL-1β protein were dependent on the inflammasome after challenge with either ozone or HA. HA challenge resulted in cleavage of macrophage-derived caspase1 and IL-1β, suggesting a role for alveolar macrophages in Nlrp3-dependent AHR.
  
  
  CONCLUSIONS
  The Nlrp3 inflammasome is required for the development of ozone-induced reactive airways disease.
authors.affiliation: Department of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine, School of Medicine, Duke University Medical Center, Durham, North Carolina 27710, USA.
authors.forename: Feifei
authors.initials: F
authors.lastname: Feng
authors.forename: Zhuowei
authors.initials: Z
authors.lastname: Li
authors.forename: Erin N
authors.initials: EN
authors.lastname: Potts-Kant
authors.forename: Yiming
authors.initials: Y
authors.lastname: Wu
authors.forename: W Michael
authors.initials: WM
authors.lastname: Foster
authors.forename: Kristi L
authors.initials: KL
authors.lastname: Williams
authors.forename: John W
authors.initials: JW
authors.lastname: Hollingsworth
mesh_terms: D000818:Animals; D016535:Bronchial Hyperreactivity / Q000139:chemically induced*; D001992:Bronchoalveolar Lavage Fluid / Q000737:chemistry; D002352:Carrier Proteins / Q000378:metabolism*; D020170:Caspase 1 / Q000378:metabolism; D006820:Hyaluronic Acid / Q000378:metabolism*; D015151:Immunoblotting; D058847:Inflammasomes / Q000172:deficiency* / Q000378:metabolism*; D053583:Interleukin-1beta / Q000378:metabolism; D008297:Male; D016210:Methacholine Chloride / Q000494:pharmacology; D051379:Mice; D008810:Mice, Inbred C57BL; D000071199:NLR Family, Pyrin Domain-Containing 3 Protein; D010126:Ozone / Q000633:toxicity*; D060888:Real-Time Polymerase Chain Reaction
chemical_list: D002352:Carrier Proteins; D058847:Inflammasomes; D053583:Interleukin-1beta; D000071199:NLR Family, Pyrin Domain-Containing 3 Protein; C492716:Nlrp3 protein, mouse; D016210:Methacholine Chloride; D010126:Ozone; D006820:Hyaluronic Acid; D020170:Caspase 1