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Resume Objectif Le but de ce travail etait d’explorer l’expression colique de l’INF-γ et de l’IL-10 chez des patients atteints de maladie de Crohn (MC) ou de rectocolite ulcero-hemorragique (RCH). Methodes Quatorze patients atteints de MC et 11 atteints de RCH ont ete inclus, ainsi que 7 sujets temoins. L’etude de l’expression colique de l’INF-γ et de l’IL-10 a ete realisee sur des biopsies de colon sain et malade, en utilisant la technique de transcription inverse et d’amplification genique (RT-PCR) en temps reel (Taqman). Les resultats ont ete exprimes sous forme de rapport entre la quantite d’ARN messager (ARNm) de la cytokine et celle d’une molecule de reference, l’ARN ribosomal 18S, puis multiplie par 10 8 . Resultats En cas de maladie de Crohn, le colon exprimait plus d’INF-γ et d’IL-10 par rapport aux temoins (medianes respectives : 23,03 vs 1,87, p = 0,042 et 20,61 vs 2,13, p = 0,08). Une puissante correlation positive a ete trouvee entre l’expression colique de l’IL-10 et celle de l’INF-γ au cours de la MC (r = 0,9, p Au niveau des sites lesionnels de RCH, l’expression de l’INF-γ ainsi que celle de l’IL-10 etaient comparables a celles observees chez les temoins (7,18 vs 2,18, p = 0,36 et 3,66 vs 1,87, p = 0,44). Conclusion Au cours de la maladie de Crohn, l’expression de l’IL-10 et celle de l’INF-γ etaient plus elevees que chez les temoins et etroitement correlees.

International audience; The digestive tract is one of the ecosystems that harbors the largest number and greatest variety of bacteria. Among them, certain bacteria have developed various strategies, including the synthesis of virulence factors such as toxins, to interact with the intestinal mucosa, and are responsible for various pathologies. A large variety of bacterial toxins of different sizes, structures and modes of action are able to interact with the gastrointestinal mucosa. Some toxins, termed enterotoxins, directly stimulate fluid secretion in enterocytes or cause their death, whereas other toxins pass through the intestinal barrier and disseminate by the general circulation to remote organs or tissues, where they are active. After recognition of a membrane receptor on target cells, toxins can act at the cell membrane by transducing a signal across the membrane in a hormone-like manner, by pore formation or by damaging membrane compounds. Other toxins can enter the cells and modify an intracellular target leading to a disregulation of certain physiological processes or disorganization of some structural architectures and cell death. Toxins are fascinating molecules, which mimic or interfere with eukaryotic physiological processes. Thereby, they have permitted the identification and characterization of new natural hormones or regulatory pathways. Besides use as protective antigens in vaccines, toxins offer multiple possibilities in pharmacology, such as immune modulation or specific delivery of a protein of interest into target cells.

International audience; Toxins are potent molecules used by various bacteria to interact with a host organism. Some of them specifically act on neuronal cells (clostridial neurotoxins) leading to characteristics neurological affections. But many other toxins are multifunctional and recognize a wider range of cell types including neuronal cells. Various enterotoxins interact with the enteric nervous system, for example by stimulating afferent neurons or inducing neurotransmitter release from enterochromaffin cells which result either in vomiting, in amplification of the diarrhea, or in intestinal inflammation process. Other toxins can pass the blood brain barrier and directly act on specific neurons.