title: Cathepsin S is activated during colitis and causes visceral hyperalgesia by a PAR2-dependent mechanism in mice.
abstract: OBJECTIVE
  Although proteases control inflammation and pain, the identity, cellular origin, mechanism of action, and causative role of proteases that are activated during disease are not defined. We investigated the activation and function of cysteine cathepsins (Cat) in colitis.
  
  
  METHODS
  Because protease activity, rather than expression, is regulated, we treated mice with fluorescent activity-based probes that covalently modify activated cathepsins. Activated proteases were localized by tomographic imaging of intact mice and confocal imaging of tissues, and were identified by electrophoresis and immunoprecipitation. We examined the effects of activated cathepsins on excitability of colonic nociceptors and on colonic pain, and determined their role in colonic inflammatory pain by gene deletion.
  
  
  RESULTS
  Tomography and magnetic resonance imaging localized activated cathepsins to the inflamed colon of piroxicam-treated il10(-/-) mice. Confocal imaging detected activated cathepsins in colonic macrophages and spinal neurons and microglial cells of mice with colitis. Gel electrophoresis and immunoprecipitation identified activated Cat-B, Cat-L, and Cat-S in colon and spinal cord, and Cat-S was preferentially secreted into the colonic lumen. Intraluminal Cat-S amplified visceromotor responses to colorectal distension and induced hyperexcitability of colonic nociceptors, which required expression of protease-activated receptor-2. Cat-S deletion attenuated colonic inflammatory pain induced with trinitrobenzene sulfonic acid.
  
  
  CONCLUSIONS
  Activity-based probes enable noninvasive detection, cellular localization, and proteomic identification of proteases activated during colitis and are potential diagnostic tools for detection of predictive disease biomarkers. Macrophage cathepsins are activated during colitis, and Cat-S activates nociceptors to induce visceral pain via protease-activated receptor-2. Cat-S mediates colitis pain and is a potential therapeutic target.
authors.affiliation: Department of Surgery, University of California, San Francisco, California, USA.
authors.forename: Fiore
authors.initials: F
authors.lastname: Cattaruzza
authors.forename: Victoria
authors.initials: V
authors.lastname: Lyo
authors.forename: Ella
authors.initials: E
authors.lastname: Jones
authors.forename: David
authors.initials: D
authors.lastname: Pham
authors.forename: James
authors.initials: J
authors.lastname: Hawkins
authors.forename: Kimberley
authors.initials: K
authors.lastname: Kirkwood
authors.forename: Eduardo
authors.initials: E
authors.lastname: Valdez-Morales
authors.forename: Charles
authors.initials: C
authors.lastname: Ibeakanma
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Vanner
authors.forename: Matthew
authors.initials: M
authors.lastname: Bogyo
authors.forename: Nigel W
authors.initials: NW
authors.lastname: Bunnett
mesh_terms: D000818:Animals; D002401:Cathepsin B / Q000378:metabolism; D056668:Cathepsin L / Q000378:metabolism; D002403:Cathepsins / Q000378:metabolism*; D003092:Colitis / Q000139:chemically induced / Q000150:complications* / Q000378:metabolism*; D003106:Colon / Q000378:metabolism / Q000473:pathology; D003424:Crohn Disease; D004195:Disease Models, Animal; D017353:Gene Deletion; D006930:Hyperalgesia / Q000209:etiology* / Q000378:metabolism*; D016753:Interleukin-10 / Q000235:genetics / Q000378:metabolism; D008264:Macrophages / Q000378:metabolism; D008279:Magnetic Resonance Imaging; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009619:Nociceptors / Q000378:metabolism; D010894:Piroxicam / Q000009:adverse effects; D044464:Receptor, PAR-2 / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology; D059265:Visceral Pain / Q000378:metabolism*
chemical_list: D044464:Receptor, PAR-2; D016753:Interleukin-10; D010894:Piroxicam; D002403:Cathepsins; D002401:Cathepsin B; D056668:Cathepsin L; C028217:cathepsin S