Evaluation of intestinal anti-inflammatory activity of 4-methylesculetin in experimental model of DSS-induced colitis in mice genetically selected lines

Abstract

The idiopathic inflammatory bowel disease (IBD) comprises two types of chronic intestinal disorders: Crohn's disease and ulcerative colitis, which etiology has not yet been defined, but it is known that interaction of immune system, genetic susceptibility, environmental factors and microbiota are related to IBD development. The current used therapy does not represent a cure for these diseases; the drugs are expensive and show several serious side effects. Based on this information, studies for development of new treatment strategies are important. Among the most widely used experimental models for colitis induction, the model of dextran sulfate sodium (DSS)-induced colitis is an important model for evaluation of substances, since this experimental model mimetizes human ulcerative colitis, allowing the study IBD pathogenesis, including the immune mechanisms involved in the disease. However, this experimental model has much variation because the animals show different susceptibility and responsiveness to colitis induction. So the use of animals that show a pattern and homogeneous response represent a model much more reliable to evaluated substances that might act in colonic inflammation. Data obtained in our previous study showed that 4-methylesculetin acts as potent antioxidant compound and ameliorated intestinal inflammation induced by TNBS in rats. Thus, the aim of this project is to evaluate the intestinal anti-inflammatory activity of 4-methylesculetin in experimental model of DSS-induced colitis in two new experimental lines, comprising AIRmax (which are mice that develop intense inflammatory response) and AIRmin (which are animals with slight inflammatory response). For these purposes, the induction of the inflammatory process will be carried out in mice (n=10) that received sterile filtered water containing 2.5% DSS for 5 days followed by 2 days of regular drinking water. The treatments will be administrated orally (4-methylesculetin at the dose of 5 mg/Kg or sulphasalazine 150 mg/Kg) and will start simultaneously with the administration of DSS and will last until day 7. The animals will be evaluated on various parameters, including a disease activity index (DAI) which will be obtained from three main signs: weight loss, diarrhea and rectal bleeding. After the death of the animals, the colon will be removed and analyzed for intestinal damage considering macroscopic (weight/length colonic ratio, presence of adhesions between bowel and adjacent organs, analysis of the severity and extension of intestinal injury), biochemical (myeloperoxidase, glutathione, TNF-± and IL-1²) and histological parameters. (AU)