Expression of the regenerating gene family in inflammatory bowel disease mucosa: Reg Ialpha upregulation, processing, and antiapoptotic activity.
BACKGROUND
The pathophysiology of inflammatory bowel disease (IBD) reflects a balance between mucosal injury related to an ongoing inflammatory process and mucosal reparative mechanisms. Proreparative mucosal factors may offer new therapeutic paradigms. Transcriptional profiling can be applied to identify candidate gene products involved in colonic mucosal regeneration.


METHODS
Resection specimens from patients who underwent colonic resection for IBD or non-IBD indications were analyzed by performing Affymetrix GeneChip hybridization (Affymetrix, Inc., Santa Clara, Calif) and histopathologic scoring. Expression and physiologic processing of Reg Ialpha, the most highly expressed member of the regenerating (Reg) gene family, was further studied by performing specific immunohistochemistry, protein sequencing, and mass spectroscopy.


RESULTS
Foregut-derived tissues normally express human Reg proteins with minimal expression in the colon. In the setting of tissue injury associated with IBD, Reg Ialpha Reg Ibeta, and Reg III mRNA were highly expressed in colonic mucosa. Paired histopathologic scoring demonstrated that Reg expression was not related to the presence or the degree of mucosal inflammation. Studies of the Reg Ialpha protein revealed evidence of proteolytic cleavage at the N-terminus. In IBD, intact Reg Ialpha protein was expressed by the metaplastic Paneth granular cell population. Whereas Reg Ialpha cleaved at the N-terminus, it was also deposited throughout the lamina propria. Reg Ialpha treatment was shown to reduce epithelial apoptosis that occurred in response to treatment with hydrogen peroxide.


CONCLUSIONS
Ectopic expression, physiologic processing, and directed tissue deposition of Reg Ialpha are components of the colonic mucosal regenerative response in IBD. Reg Ialpha may serve to reduce epithelial apoptosis in inflammation.
Dieckgraefe
Brian K
BK
Department of Medicine, Washington University School of Medicine, St Louis, MO 63110, USA. dieck@im.wustl.edu
Crimmins
Dan L
DL
Landt
Vonnie
V
Houchen
Courtney
C
Anant
Shrikant
S
Porche-Sorbet
Rhonda
R
Ladenson
Jack H
JH
D017209:Apoptosis; D002135:Calcium-Binding Proteins / Q000096:biosynthesis* / Q000235:genetics / Q000494:pharmacology; D003093:Colitis, Ulcerative / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D003424:Crohn Disease / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D004847:Epithelial Cells / Q000187:drug effects / Q000473:pathology; D019084:Fluorescent Antibody Technique, Indirect; D020869:Gene Expression Profiling; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D007124:Immunoenzyme Techniques; D007413:Intestinal Mucosa / Q000378:metabolism* / Q000473:pathology; D051847:Lithostathine; D009419:Nerve Tissue Proteins; D020411:Oligonucleotide Array Sequence Analysis; D010189:Pancreatic Juice / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D011994:Recombinant Proteins / Q000494:pharmacology; D014407:Tumor Cells, Cultured
D002135:Calcium-Binding Proteins; D051847:Lithostathine; D009419:Nerve Tissue Proteins; C497617:REG1A protein, human; D012333:RNA, Messenger; D011994:Recombinant Proteins; D006861:Hydrogen Peroxide