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Acute and chronic model induced by Dextran sulfate sodium (DSS)

🔍 WHY IS IT USEFUL?
Dextran sulfate sodium (DSS) is widely used to generate murine models of ulcerative colitis due to its ability to selectively damage the intestinal epithelium and compromise the integrity of the mucosal barrier in the distal colon and rectum. This damage induces clinical manifestations consistent with human pathologies: weight loss, diarrhea, and occult blood in the stool, making it a validated tool for translational IBD studies.
It is used to test the therapeutic efficacy of new drugs.

🔍 HOW DOES THE MODEL WORK?
The acute phase is characterized by strong activation of neutrophils and macrophages. In the chronic phases,

The image shows the progression of the acute and chronic phases of colon inflammation induced by DSS.
In the acute colitis model induced by DSS, 8–12-week-old C57/Bl6 mice undergo an oral cycle (via drinking water) of 2.5–3% DSS (molecular weight 40 kDa), consisting of 7 days of DSS exposure followed by 3–7 days of purified water. In the chronic colitis model, 8–12-week-old C57/Bl6 mice undergo 3 oral cycles of 2% DSS, each consisting of 7 days of DSS exposure followed by 7 days of purified water.
THE ACUTE AND CHRONIC MODEL IS ALSO SUCCESSFULLY PERFORMED IN RATS.

PARAMETERS EVALUATED

1) Clinical parameters: Body weight loss and Disease Activity Index (DAI)
2) Endoscopic parameters: Mucosal translucency, changes in vascular pattern, fibrin deposits, mucosal granularity
We routinely perform endoscopic analyses in murine models of IBD. The experimental endoscopy setup, called the “Coloview system,” consists of a miniature endoscope (1.9 mm outer diameter), a xenon light source, a three-chip camera, and an air pump (Karl Storz, Tuttlingen, Germany). The endoscopic procedure is displayed on a color monitor, and an endoscopic score is assigned based on the following parameters: colon translucency (0–3 points), mucosal granularity (0–3 points), vascular pattern morphology (0–4 points), and presence of fibrin (0–4 points). The cumulative score ranges from 0 (no signs of inflammation) to 14 (very severe endoscopic signs of inflammation).(1)
(1) D’Alessio S et al. J Clin Invest. 2014;124(9):3863-3878. https://doi.org/10.1172/JCI72189.
3) Histological parameters: RACHMILEWITZ (1) and DIELEMAN (2) score
We routinely perform histological analyses on murine colon tissues. A trained pathologist, blinded to the treatment, evaluates inflammation and epithelial repair processes to assign a histological score, according to the criteria described by Rachmilewitz¹ or Dieleman² et al. Representative images show that in healthy mice (e.g., Healthy + Vehicle), the tissue layers (mucosa, muscularis mucosae, and submucosa) appear well-structured. In mice with severe DSS-induced colitis (e.g., DSS + Vehicle), the stratification of the layers is no longer preserved: a massive inflammatory infiltrate (red circles) completely fills both the mucosa and submucosa, and the crypts are severely damaged (yellow circle) in most of the distal colon. The epithelium is almost completely eroded, indicating the presence of ulcerations.

(1) Rachmilewitz, D. et al. Gastroenterology 2002; 122: 1428–1441;
(2)Dieleman, Palmen, Akol, et al. Clin Exp Immunol 1998; 114: 385–391.
M: Mucosa; MM: Musculati mucosae; SM: Submucosa.

4) IMMUNOHISTOCHEMICAL ANALYSES. We routinely perform immunohistochemical analyses on any type of murine tissue, including intestinal tissue.
5) ADDITIONAL ANALYSES: FACS, RNA sequencing, Metagenomics, Lipidomics, Integrated bioinformatic analyses, Multiplex, RT-PCR, ELISA kits for cytokines and chemokines
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