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IMMUNOPROPHYLAXIE DES CANCERS COLORECTAUX PAR DES GLUCIDES INDIGESTIBLES FERMENTABLES: ETUDES CHEZ LA SOURIS MIN

Abstract : Dietary fiber may prevent colorectal cancer, but this hypothesis is still controversial. One proposed mechanism is the production of butyrate by fermentation. We tested two different butyrogenic fibers (short-chain fructooligosaccharides and type III resistant starch) in opposition to a weak butyrate-producing fiber (wheat bran starch free) in the Min mouse, a genetic model of spontaneous intestinal carcinogenesis. Only the sc-FOS diet protected against colon cancer. It suggests the action of another protecting factor besides butyrate: the chemical nature of the fiber and/or the prebiotic properties of sc-FOS (via lactic bacteria which can act on the immune process). In accordance with this hypothesis, we have observed an amplification of the intestinal immune system. Secondly, two resistant starchs with different chemical properties did not reduce the total number of tumours but reduced the number of small tumours. The addition of lyophilised bifidobacteria to the starch-resistant diet reduced the number of small tumours but increased the number of large tumours showing the concept of the dual immunofacilitation/immunoprotection process. A depletion of T lymphocytes of mice fed with sc-FOS doubled the number of colon tumours in comparison with immunocompetent mice, arguing for the participation of the immune system in the protection. By phenotyping of intra-epithelial lymphocyte, a significant decrease of interleukin 2 receptor was found only in sc-FOS diet. This is a possible indication of a temporary anergy of the local immune system or of the involvement of another activation pathway of the colon IELs. In order to classify the mechanisms, we isolated cell lines conditionally immortalized healthy (Apc +/+) and mutated (Apc Min/+) from of breeding Min mice with immortomouse. This cell culture model using a filter co-culture system allows us to study the influence of indigestible carbohydrates and their fermentation products on lympho-epithelial interactions during carcinogenesis.
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https://tel.archives-ouvertes.fr/tel-00343810
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Submitted on : Tuesday, December 2, 2008 - 6:30:53 PM
Last modification on : Friday, October 23, 2020 - 4:37:28 PM
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  • HAL Id : tel-00343810, version 1
  • PRODINRA : 250147

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Fabrice Pierre. IMMUNOPROPHYLAXIE DES CANCERS COLORECTAUX PAR DES GLUCIDES INDIGESTIBLES FERMENTABLES: ETUDES CHEZ LA SOURIS MIN. Immunologie. Université de Nantes, 1999. Français. ⟨tel-00343810⟩

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