A major role for proteolytic activity and proteinase-activated receptor-2 in the pathogenesis of infectious colitis

doi:10.1073/pnas.0409535102

A major role for proteolytic activity and proteinase-activated receptor-2 in the pathogenesis of infectious colitis

^*Proteinases and Inflammation Network, Mucosal Inflammation Research Group, Department of Pharmacology and Therapeutics, and ^¶Department of Medicine, Faculty of Medicine, University of Calgary, Calgary, AB, Canada T2N 4N1; ^†Hospital for Sick Children, University of Toronto, Toronto, ON, Canada MG5 1X8; ^‡Drug Discovery, Johnson & Johnson Pharmaceutical Research and Development, Spring House, PA 19477; and ^§Celera Genomics, South San Francisco, CA 94080

Edited by Pedro M. Cuatrecasas, University of California at San Diego School of Medicine, La Jolla, CA, and approved April 25, 2005 (received for review December 20, 2004)

Abstract

Citrobacter rodentium is a bacterial pathogen that causes a murine infectious colitis equivalent to enterohemorrhagic Escherichia coli infection in humans. Colonic luminal fluid from C. rodentium-infected mice, but not from sham-infected mice, contains active serine proteinases that can activate proteinase-activated receptor-2 (PAR₂). We have identified granzyme A and murine trypsins to be present in C. rodentium-infected luminal fluid, as determined by mass spectrometry and Western blot analysis. Inflammatory indices (colonic mucosa macroscopic damage score, increased intestinal wall thickness, granulocyte infiltration, and bacterial translocation from the colonic lumen to peritoneal organs) were all increased in C. rodentium-infected mice, compared with sham-infected mice. Soybean trypsin inhibitor-treated wild-type mice and untreated PAR₂-deficient (PAR₂ ^-/-) mice (compared with their wild-type littermates) both had substantially reduced levels of C. rodentium-induced inflammation. These data point to an important role for both pathogen-induced host serine proteinases and PAR₂ in the setting of infectious colitis.

Footnotes

↵ ∥ To whom correspondence should be addressed. E-mail: nvergnol{at}ucalgary.ca.
Author contributions: K.K.H., P.M.S., and N.V. designed research; K.K.H., P.M.S., and L.C. performed research; P.A.-G., Z.P., and A.B. contributed new reagents/analytic tools; K.K.H., P.M.S., and N.V. analyzed data; K.K.H., P.M.S., M.D.H., J.L.W., and N.V. wrote the paper.
This paper was submitted directly (Track II) to the PNAS office.
Abbreviations: PAR₂, proteinase-activated receptor-2; STI, soybean trypsin inhibitor; AMC, 7-amino-4-methylcoumarin; Boc, tert-butyloxycarbonyl.