Protease-Activated Receptor 4 Induces Bladder Pain through High Mobility Group Box-1 Journal Article

Authors: Kouzoukas, D. E.; Ma, F.; Meyer-Siegler, K. L.; Westlund, K. N.; Hunt, D. E.; Vera, P. L.
Article Title: Protease-Activated Receptor 4 Induces Bladder Pain through High Mobility Group Box-1
Abstract: Pain is the significant presenting symptom in Interstitial Cystitis/Painful Bladder Syndrome (IC/PBS). Activation of urothelial protease activated receptor 4 (PAR4) causes pain through release of urothelial macrophage migration inhibitory factor (MIF). High Mobility Group Box-1 (HMGB1), a chromatin-binding protein, mediates bladder pain (but not inflammation) in an experimental model (cyclophosphamide) of cystitis. To determine if PAR4-induced bladder hypersensitivity depends on HMGB1 downstream, we tested whether: 1) bladder PAR4 stimulation affected urothelial HMGB1 release; 2) blocking MIF inhibited urothelial HMGB1 release; and 3) blocking HMGB1 prevented PAR4-induced bladder hypersensitivity. HMGB1 release was examined in immortalized human urothelial cultures (UROtsa) exposed to PAR4-activating peptide (PAR4-AP; 100 muM; 2 hours) or scrambled control peptide. Female C57BL/6 mice, pretreated with a HMGB1 inhibitor (glycyrrhizin: 50 mg/kg; i.p.) or vehicle, received intravesical PAR4-AP or a control peptide (100 muM; 1 hour) to determine 1) HMGB1 levels at 1 hour in the intravesical fluid (released HMGB1) and urothelium, and 2) abdominal hypersensitivity to von Frey filament stimulation 24 hours later. We also tested mice pretreated with a MIF blocker (ISO-1: 20 mg/kg; i.p.) to determine whether MIF mediated PAR4-induced urothelial HMGB1 release. PAR4-AP triggered HMGB1 release from human (in vitro) and mice (in vivo) urothelial cells. Intravesical PAR4 activation elicited abdominal hypersensitivity in mice that was prevented by blocking HMGB1. MIF inhibition prevented PAR4-mediated HMGB1 release from mouse urothelium. Urothelial MIF and HGMB1 represent novel targets for therapeutic intervention in bladder pain conditions.
Keywords: Female; Humans; Animals; Mice, Inbred C57BL; Cell Line; HMGB1 Protein/antagonists inhibitors/metabolism; Macrophage Migration-Inhibitory Factors/antagonists inhibitors/metabolism; Pelvic Pain/metabolism/pathology/prevention control; Receptors, Thrombin/metabolism; Urinary Bladder/metabolism/pathology
Journal Title: PloS one
Volume: 11
Issue: 3
ISSN: 1932-6203; 1932-6203
Publisher: Unknown  
Journal Place: United States
Date Published: 2016
Start Page: e0152055
Language: ENG
Notes: LR: 20161019; GR: DK0093496/DK/NIDDK NIH HHS/United States; JID: 101285081; 0 (HMGB1 Protein); 0 (Macrophage Migration-Inhibitory Factors); 0 (Receptors, Thrombin); 0 (protease-activated receptor 4); OID: NLM: PMC4806866; 2015/11/25 [received]; 2016/03/08 [accepted]; epublish