title: The NACHT, LRR and PYD Domains-Containing Protein 3 (NLRP3) Inflammasome Mediates Inflammation and Voiding Dysfunction in a Lipopolysaccharide-Induced Rat Model of Cystitis.
abstract: OBJECTIVE
  NOD-like receptors (NLRs) sense sterile and non-sterile signals and form inflammasomes which trigger an inflammatory response through the activation of caspase-1 and release of IL-1β. Recently we have shown the presence of several NLRs in the bladder urothelia and demonstrated the importance of NLRP3 in bladder outlet obstruction and cyclophosphamide-induced cystitis, both models of sterile inflammation. In this study we explore a role for NLRP3 in mediating the response to LPS, a key antigen of uropathogenic bacteria.
  
  
  METHODS
  In order to bypass the protective glycosaminoglycan layer lining the urothelium, LPS was directly injected into the bladder wall of Sprague-Dawley rats. Glyburide (a NLRP3 inhibitor) or vehicle was administered orally prior to and after injection. Rats were analyzed 24 h later. Inflammasome activity (caspase-1 activity, IL-1β release) and inflammation (Evan's Blue extravasation, bladder weight) were assessed, as was physiological bladder function (urodynamics).
  
  
  RESULTS
  Injection of LPS stimulated inflammasome activation (caspase-1 activity) and the release of IL-1β into the urine which was prevented by glyburide. Likewise, LPS increased inflammation, (bladder weight and the extravasation of Evan's blue dye), and this was reversed by glyburide. Functionally, animals injected with saline alone demonstrated decreased voiding volume as measured by urodynamics. In the presence of LPS, additional urinary dysfunction was evident with decreased voiding pressures and threshold pressures. The decrease in voiding pressure was blocked by glyburide but the decrease in threshold pressure was not, suggesting that LPS has significant effects mediated by inflammasome-dependent and -independent mechanisms.
  
  
  CONCLUSIONS
  Overall, the results demonstrate the potential importance of inflammasomes in bacterial cystitis as well as the ability of the bladder wall injection technique to isolate thein vivoeffects of specific inflammasome ligands to the physiological changes associated with cystitis.
authors.affiliation: Department of Surgery, Division of Urology, Duke University Medical Center, Durham, NC, USA; Department of Urology, Medical University of South Carolina, Charleston, SC, USA.
authors.forename: Francis M
authors.initials: FM
authors.lastname: Hughes
authors.affiliation: Department of Urology, Medical University of South Carolina, Charleston, SC, USA.
authors.forename: James G
authors.initials: JG
authors.lastname: Kennis
authors.affiliation: Department of Urology, Medical University of South Carolina, Charleston, SC, USA.
authors.forename: Melissa N
authors.initials: MN
authors.lastname: Youssef
authors.affiliation: Department of Pediatrics, Medical University of South Carolina, Charleston, SC, USA.
authors.forename: Danielle W
authors.initials: DW
authors.lastname: Lowe
authors.affiliation: Department of Pharmaceutical and Biomedical Sciences, Medical University of South Carolina, Charleston, SC, USA.
authors.forename: Brooke E
authors.initials: BE
authors.lastname: Shaner
authors.affiliation: Department of Surgery, Division of Urology, Duke University Medical Center, Durham, NC, USA; Department of Urology, Medical University of South Carolina, Charleston, SC, USA; Department of Pediatrics, Medical University of South Carolina, Charleston, SC, USA; Department of Regenerative Medicine and Cell Biology, Medical University of South Carolina, Charleston, SC, USA.
authors.forename: J Todd
authors.initials: JT
authors.lastname: Purves
keywords: Bladder; Caspase-1; Cystitis; Inflammasome; Inflammation; Innate immunity; Lipopolysaccharide