Effets des régimes hyperprotéiques et des métabolites bactériens dérivés des acides aminés sur la muqueuse du gros intestin

Abstract : Abstract: High-protein diets are frequently consumed but the consequences for the large intestine are not well described. The objective of this thesis was to evaluate the effects of high-protein diets and of amino-acid derived bacterial metabolites on the large intestine mucosa. Animal and in vitro studies showed that two amino acid derived bacterial metabolites (hydrogen sulfide and p-cresol) are toxic for the epithelium when present at high concentration. The results obtained in a clinical trial indicate that quantity and quality of dietary protein do not have major effects on the fecal microbiota composition but modify the fecal and urinary concentration of bacterial metabolites.These changes in luminal environment were not associated with an increase in fecal water cytotoxicity in vitro. Nevertheless, in the rectal mucosa, the increase in protein intake regulated the expression of genes implicated in homeostatic processes and these effects were modulated by the source of protein. However, the level of protein intake had no effect on immune and histological parameters in the mucosa. These results were completed with a study in rats showing a clear transcriptome profile in colonocytes induced by a high-protein diet but that was not associated with detrimental effects in terms of DNA integrity, epithelial renewal and barrier function.
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Martin Beaumont. Effets des régimes hyperprotéiques et des métabolites bactériens dérivés des acides aminés sur la muqueuse du gros intestin. Médecine humaine et pathologie. Université Paris-Saclay, 2016. Français. ⟨NNT : 2016SACLA011⟩. ⟨tel-02303264⟩

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