Original Article
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World J Gastroenterol. Dec 28, 2014; 20(48): 18207-18215
Published online Dec 28, 2014. doi: 10.3748/wjg.v20.i48.18207
2,4,6-trinitrobenzene sulfonic acid-induced chronic colitis with fibrosis and modulation of TGF-β1 signaling
Emilien Loeuillard, Julien Bertrand, Anni Herranen, Chloé Melchior, Charlène Guérin, Moïse Coëffier, Moutaz Aziz, Pierre Déchelotte, Guillaume Savoye, Rachel Marion-Letellier
Emilien Loeuillard, Julien Bertrand, Anni Herranen, Chloé Melchior, Charlène Guérin, Moïse Coëffier, Pierre Déchelotte, Guillaume Savoye, Rachel Marion-Letellier, INSERM Unit UMR1073, Rouen University and Rouen University Hospital, Rouen Cedex 76183, France
Emilien Loeuillard, Julien Bertrand, Anni Herranen, Chloé Melchior, Charlène Guérin, Moïse Coëffier, Pierre Déchelotte, Guillaume Savoye, Rachel Marion-Letellier, Institute for Research and Innovation in Biomedicine, University of Rouen, Rouen Cedex 76183, France
Chloé Melchior, Guillaume Savoye, Department of Gastroenterology, Rouen University Hospital, Rouen Cedex 76183, France
Moïse Coëffier, Pierre Déchelotte, Nutrition Unit, Rouen University Hospital, Rouen Cedex 76183, France
Moutaz Aziz, Department of Pathology, Rouen University Hospital, Rouen Cedex 76183, France
Author contributions: Déchelotte P, Savoye G and Marion-Letellier R designed the research; Loeuillard E, Bertrand J, Herranen A, Melchior C, Guérin C, Aziz M and Marion-Letellier R performed the research; Loeuillard E, Bertrand J, Coëffier M, Savoye G and Marion-Letellier R analyzed the data; and Savoye G and Marion-Letellier R wrote the paper.
Correspondence to: Rachel Marion-Letellier, PhD, INSERM Unit UMR1073, Rouen University and Rouen University Hospital, 22, Boulevard Gambetta, Rouen Cedex 76183, France. marion_rachel@hotmail.com
Telephone: +33-2-35148245 Fax: +33-2-35148226
Received: May 5, 2014
Revised: June 30, 2014
Accepted: September 5, 2014
Published online: December 28, 2014
Processing time: 245 Days and 10.5 Hours
Abstract

AIM: To investigate whether targeting proteasome might reverse intestinal fibrosis in rats.

METHODS: Chronic colitis was induced in rats by repeated administration of increasing dose of 2,4,6-trinitrobenzene sulfonic acid (TNBS, 15, 30, 45, 60, 60, 60 mg) by rectal injection for 6 wk (from day 0 to day 35), while control rats received the vehicle. TNBS + bortezomib (BTZ) rats received intraperitoneal injections of BTZ twice weekly (from day 37 to day 44) at a dose of 25 mg/kg, whereas the control and TNBS groups received the same amount of the vehicle. Histologic scoring of inflammation and fibrosis was performed. Colonic production of transforming growth factor (TGF)-β was measured by ELISA. Colon fibrosis-related proteins such as phospho-p38, phospho-SMAD2/3, Akt and peroxisome proliferator activated receptor γ (PPARγ) were studied by western blot. Expression of the tight junction proteins, occludin and claudin-1, were assessed by Western blot. Colon proteasome activities (chymotrypsin-like and trypsin-like activities) were assessed.

RESULTS: TNBS-treated rats had a higher colon weight/length ratio compared to control rats (P < 0.01). Furthermore, fibrosis and inflammation scores were higher in TNBS-treated rats compared to control rats (P < 0.01 for both). Colonic production of TGF-β production tended to be higher in TNBS-treated rats (P < 0.06). Fibrosis-related proteins such as phospho-p38, phospho-SMAD2/3, and PPARγ were significantly higher in TNBS-treated rats compared to control rats (all P < 0.05). TNBS rats had a higher expression of Akt compared to control rats (P < 0.01). Tight junction proteins were modified by repeated TNBS challenge: colon occludin expression rose significantly (P < 0.01), whereas claudin-1 expression fell (P < 0.01). Bortezomib inhibition significantly decreased chymotrypsin-like activity (P < 0.05), but had no significant effect on trypsin-like activity (P > 0.05). In contrast, bortezomib had no effect on other studied parameters such as fibrosis score, TGF-β signaling, or tight junction expression (P > 0.05 for all).

CONCLUSION: Rats with TNBS-induced chronic colitis exhibited colon fibrosis associated with higher TGF-β signaling. Proteasome inhibition by bortezomib had no effect on fibrosis in our experimental conditions.

Keywords: Bortezomib; Colitis; Fibrosis; Proteasome

Core tip: Inflammatory bowel disease gives rise to challenging clinical conditions, and many patients have to undergo surgery throughout their life due to irreversible lesions. As no specific treatment is currently available for intestinal fibrosis, we tested an antifibrotic drug that is effective in other chronic inflammatory diseases. In the present study, we found that rats with 2,4,6-trinitrobenzene sulfonic acid-induced chronic colitis exhibited colon fibrosis associated with high expression of transforming growth factor-β signaling, particularly in the Akt pathway. Nevertheless, we failed to inhibit colon fibrosis by proteasome inhibition in our experimental conditions.