Abstract
Inflammatory bowel disease (IBD) including Crohn’s disease and ulcerative colitis are characterized by chronic, progressive and relapsing inflammatory disorders. Existing evidence indicate that IBD is associated with a higher risk of developing CAC, which is directly related to the duration and extent of colitis. Thus, animal models have been developed to understand the biology of colitis and CAC. The most commonly used model of colitis is to treat with dextran sodium sulfate (DSS). DSS given in the drinking water is toxic to the colonic epithelial lining and induces bloody diarrhea, ulceration and inflammation, similar to colitis in IBD patients. To study CAC, DSS treatment is combined with a single intraperitoneal injection of the DNA alkylation reagent Azoxymethane (AOM).
Keywords: inflammation, tumor, intestine, mouse, carcinogen
Materials and Reagents
Equipment
Procedure
Representative data
Figure 1. Example of a longitudinally open colon at day 100 of AOM/DSS-treatment showing colon tumors (arrows). Tumors are counted macroscopically and tumor sizes are determined using a digital caliper. Figure 2. Example of H&E-stained colon sections at day 100 of AOM/DSS-treatment showing colon tumors (arrows) and the adjacent normal colon tissue
Notes
This protocol is highly dependent on the mouse genetic background, the animal housing conditions and the AOM and DSS batches. The working concentration of DSS should be determined empirically in pilot experiments. We have used the AOM/DSS protocol to induce colon tumors in mostly C57BL/6 background and mostly FVB background as well as in mixed C57BL/6-129v mice. In all cases, tumors were observed in 100% of the mice analyzed at day 100 of AOM/DSS treatment. If no tumors are detected at this time point, AOM concentration and/or DSS concentration should be increased. For the colitis experiment, between 2% and 5% DSS for 5 days should be enough to induce epithelial damage. Alternatively, the DSS treatment can be extended if little or no damage is observed at day 7.
Acknowledgments
Our work is supported by the Fundación BBVA and by grants from the Spanish MICINN (BFU2010-17850) and the European Commission FP7 (INFLA-CARE 223151 and ERC 294665). This protocol is a modification of the protocol published by Neufert et al. (2007).
References
If you have any questions/comments about this protocol, you are highly recommended to post here. We will invite the authors of this protocol as well as some of its users to address your questions/comments. To make it easier for them to help you, you are encouraged to post your data including images for the troubleshooting.