Flexible Colonoscopy in Mice to Evaluate the Severity of Colitis and Colorectal Tumors Using a Validated Endoscopic Scoring System

Abstract

The use of modern endoscopy for research purposes has greatly facilitated our understanding of gastrointestinal pathologies. In particular, experimental endoscopy has been highly useful for studies that require repeated assessments in a single laboratory animal, such as those evaluating mechanisms of chronic inflammatory bowel disease and the progression of colorectal cancer. However, the methods used across studies are highly variable. At least three endoscopic scoring systems have been published for murine colitis and published protocols for the assessment of colorectal tumors fail to address the presence of concomitant colonic inflammation. This study develops and validates a reproducible endoscopic scoring system that integrates evaluation of both inflammation and tumors simultaneously. This novel scoring system has three major components: 1) assessment of the extent and severity of colorectal inflammation (based on perianal findings, transparency of the wall, mucosal bleeding, and focal lesions), 2) quantitative recording of tumor lesions (grid map and bar graph), and 3) numerical sorting of clinical cases by their pathological and research relevance based on decimal units with assigned categories of observed lesions and endoscopic complications (decimal identifiers). The video and manuscript presented herein were prepared, following IACUC-approved protocols, to allow investigators to score their own experimental mice using a well-validated and highly reproducible endoscopic methodology.

Genetic deletion of the bacterial sensor NOD2 improves murine Crohn's disease-like ileitis independent of functional dysbiosis

“…Inflammation was evaluated using a decimal-scoring system validated for the integrated endoscopic assessment of colonic inflammation and colorectal cancer in mice 35 .…”

Protective Role for TWEAK/Fn14 in Regulating Acute Intestinal Inflammation and Colitis-Associated Tumorigenesis

“…Endoscopy images were obtained on an Olympus BX41 microscope (magnification, 100× and 200×; objective, 10×; eyepiece, 10×). Colonoscopy was performed on day 7 and day 21 after DSS administration, and inflammation was evaluated using a previously validated endoscopic scoring system (15). Briefly, the system considers four different parameters to evaluate colonic inflammation: perianal findings (diarrhea, bloody feces or rectal prolapse); wall transparency (based on the ability to see the blood vessels of the colonic mucosa); intestinal bleeding (spontaneous or induced by the endoscope because of the mucosal friability), and focal lesions (edema, erosions and ulcers).…”

Choline Deficiency Causes Colonic Type II Natural Killer T (NKT) Cell Loss and Alleviates Murine Colitis under Type I NKT Cell Deficiency

“…Spontaneous bleeding was defined as naturally occurring mucosal hemorrhaging not associated with traumatic endoscopy, and transparency was defined as the ability to visualize intramural blood vessels in the colon and those of other surrounding viscera [26]. …”