Submitted on April 29, 2008
Revised on July 15, 2008
Accepted on July 16, 2008
Role of MutS Homologue 2 (MSH2) in Intestinal Myofibroblast Proliferation During Crohn's Disease Stricture Formation
Martin Floer1, David G Binion2, Victoria M. Nelson, Sharon Manley, Michael Wellner, Saba Sadeghi, Behnaz Behmaram, Chloe Sewell, Mary F. Otterson, Torsten Kucharzik3, and Parvaneh Rafiee4*
1 University of Muenster
2 Froedtert Memorial Luthern Hospital
3 University of Meunster
4 Medical College of Wisconsin
* To whom correspondence should be addressed. E-mail: prafiee{at}mcw.edu.
Tissue remodeling and mesenchymal cell accumulation accompanies chronic inflammatory disorders involving joints, lung, vasculature and bowel. Chronic inflammation may alter DNA-mismatch repair (MMR) systems in mesenchymal cells, but is not defined in Crohn's disease (CD) and its associated intestinal remodeling and stricture formation. We determined whether DNA-MMR alteration plays a role in the pathogenesis of CD tissue remodeling. Control and CD bowel tissues were used to generate primary cultures of muscularis mucosa myofibroblasts which were assessed directly or following stimulation with TNF-
/LPS or H2O2. MSH2, MSH3 and MSH6 expression in tissues and myofibroblasts were determined. Immunohistochemical staining revealed an increased expression of MSH2 in CD muscularis mucosa and submucosal tissues compared to controls or uninvolved CD tissue and MSH2 expression was increased in CD myofibroblasts compared to control cells. TNF-/LPS and H2O2 further enhanced MSH2 expression in both control and CD cells which was decreased by simvastatin. There were no significant changes in MSH3 and MSH6 expression. PCNA and ki67 staining of CD tissue revealed increased proliferation in the muscularis mucosa and submucosa of chronically inflamed tissues and enhanced proliferation was seen in CD myofibroblasts compared with controls. Simvastatin reversed the effects of inflammatory stress on the DNA-MMR and inhibited proliferation of control and CD myofibroblasts. Gene silencing with MSH2 siRNA selectively decreased CD myofibroblast proliferation. These data demonstrate a potential role for MSH2 in the pathogenesis of non-neoplastic mesenchymal cell accumulation and intestinal remodeling in CD chronic inflammation.
