Basic Study
Copyright ©The Author(s) 2017. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Apr 28, 2017; 23(16): 2899-2911
Published online Apr 28, 2017. doi: 10.3748/wjg.v23.i16.2899
Detection and characterization of murine colitis and carcinogenesis by molecularly targeted contrast-enhanced ultrasound
Markus Brückner, Jan Heidemann, Tobias M Nowacki, Friederike Cordes, Jörg Stypmann, Philipp Lenz, Faekah Gohar, Andreas Lügering, Dominik Bettenworth
Markus Brückner, Tobias M Nowacki, Friederike Cordes, Dominik Bettenworth, Department of Medicine B, University Hospital of Münster, D-48149 Münster, Germany
Jan Heidemann, Department of Gastroenterology, Klinikum Bielefeld Mitte, Academic Teaching Hospital, University of Münster, D-33604 Bielefeld, Germany
Jörg Stypmann, Department of Cardiology and Angiology, University Hospital of Münster, D-48149 Münster, Germany
Philipp Lenz, Department of Palliative Care, University Hospital of Münster, D-48149 Münster, Germany
Faekah Gohar, Department of Paediatric Rheumatology and Immunology, University Hospital of Münster, D-48149 Münster, Germany
Andreas Lügering, Medical Care Center Portal 10, D-48155 Münster, Germany
Author contributions: Brückner M and Heidemann J contributed equally to this work and share first authorship; Brückner M, Heidemann J, Lügering A and Bettenworth D contributed to the article design, literature search, manuscript writing and final revision of the article; Brückner M performed ultrasound examinations; Brückner M, Cordes F and Bettenworth D performed the research and analysed the data; Brückner M, Nowacki TM, Cordes F, Stypmann J, Lenz P and Gohar F contributed to manuscript writing and final revision of the article; Gohar F proofread the final revision.
Institutional review board statement: The study was reviewed and approved by the University Hospital of Münster - Department of Medicine B Institutional Review Board.
Institutional animal care and use committee statement: All procedures using animals were reviewed and approved by the local animal subjects committee, University of Münster (permit 84-02.04.2013.A093).
Conflict-of-interest statement: None of the authors has received fees for serving as a speaker or received research funding from with regard to this study. None of the authors owns stocks and/or shares with regards to this study. None of the authors owns patents with regard to this study.
Data sharing statement: Technical appendix, statistical code, and dataset are available from the corresponding author at markus.brueckner@ukmuenster.de.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Correspondence to: Markus Brückner, MD, Department of Medicine B, University Hospital of Münster, Albert-Schweitzer-Campus 1, D-48149 Münster, Germany. markus.brueckner@ukmuenster.de
Telephone: +49-251-8347661 Fax: +49-251-8347570
Received: December 29, 2016
Peer-review started: December 30, 2016
First decision: February 23, 2017
Revised: March 14, 2017
Accepted: March 30, 2017
Article in press: March 30, 2017
Published online: April 28, 2017
Abstract
AIM

To study mucosal addressin cellular adhesion molecule-1 (MAdCAM-1) and vascular endothelial growth factor (VEGF)-targeted contrast enhanced ultrasound (CEUS) for the assessment of murine colitis and carcinogenesis.

METHODS

C57BL/6 mice were challenged with 3% dextran sodium-sulfate (DSS) for three, six or nine days to study the development of acute colitis. Ultrasound was performed with and without the addition of unspecific contrast agents. MAdCAM-1-targeted contrast agent was used to detect and quantify MAdCAM-1 expression. Inflammatory driven colorectal azoxymethane (AOM)/DSS-induced carcinogenesis was examined on day 42 and 84 using VEGF-targeted contrast agent. Highly specific tissue echogenicity was quantified using specialized software. Sonographic findings were correlated to tissue staining, western blot analysis and immunohistochemistry to quantify the degree of inflammation and stage of carcinogenesis.

RESULTS

Native ultrasound detected increased general bowel wall thickening that correlated with more progressed and more severe DSS-colitis (healthy mice: 0.3 mm ± 0.03 vs six days DSS: 0.5 mm ± 0.2 vs nine days DSS: 0.6 mm ± 0.2, P < 0.05). Moreover, these sonographic findings correlated well with clinical parameters such as weight loss (r2 = 0.74) and histological damage (r2 = 0.86) (P < 0.01). In acute DSS-induced murine colitis, CEUS targeted against MAdCAM-1 detected and differentiated stages of mild, moderate and severe colitis via calculation of mean pixel contrast intensity in decibel (9.6 dB ± 1.6 vs 12.9 dB ± 1.4 vs 18 dB ± 3.33, P < 0.05). Employing the AOM/DSS-induced carcinogenesis model, tumor development was monitored by CEUS targeted against VEGF and detected a significantly increased echogenicity in tumors as compared to adjacent healthy mucosa (healthy mucosa, 1.6 dB ± 1.4 vs 42 d, 18.2 dB ± 3.3 vs 84 d, 18.6 dB ± 4.9, P < 0.01). Tissue echogenicity strongly correlated with histological analysis and immunohistochemistry findings (VEGF-positive cells in 10 high power fields of healthy mucosa: 1 ± 1.2 vs 42 d after DSS start: 2.4 ± 1.6 vs 84 d after DSS start: 3.5 ± 1.3, P < 0.01).

CONCLUSION

Molecularly targeted CEUS is a highly specific and non-invasive imaging modality, which characterizes murine intestinal inflammation and carcinogenesis in vivo.

Keywords: Colitis, Dextran sodium-sulfate, AOM-DSS, Carcinogenesis, Ultrasound, Contrast-enhanced ultrasound, Vascular endothelial growth factor, Mucosal addressin cellular adhesion molecule-1

Core tip: Murine models of colitis and carcinogenesis are widely used to study novel diagnostic approaches and to preclinically evaluate promising drug candidates. However, valid assessment of severity of inflammation or cancer development routinely requires post mortem histological analysis. Our study provides evidence that non-invasive contrast enhanced ultrasound (CEUS) is feasible to specifically target intestinal inflammation and carcinogenesis. While MAdCAM-1-directed CEUS follows the severity of murine dextran sodium-sulfate (DSS)-colitis, the use of VEGF- targeted contrast agent allows for characterization of cancer development in the AOM/DSS-induced model of colitis-associated cancer.