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La malabsorption du lactose : Etude des modulations du microbiote intestinal et de l’adaptation de l’hôte malabsorbeur. Evaluation d’un nouveau marqueur diagnostique

Abstract : According to health care professionals, lactose intolerance is poorly managed because of a lack of reliability of the diagnostic tools and an insufficient knowledge of the mechanisms triggering the intolerance symptoms.The general purpose of this work is to improve the care of lactose intolerance with: i. the evaluation of a new diagnostic marker of lactose malabsorption after an acute ingestion, ii. the in vivo study of intestinal microbiota modulations (in terms of composition and activity) and of the host's physiology after both acute and chronic ingestions of lactose.The animal and clinical studies presented in this work revealed the purpose of indirect calorimetry, especially of the Respiratory Quotient (RQ), as a non invasive technique to detect lactose malabsorption. The animal studies, performed on rats, underlined the modulation of the intestinal microbiota and the adaptation of the malabsorber host, after lactose ingestion. Acute lactose ingestion leads to a rise of the colonic concentrations in SCFA and lactate, and to their absorption. The SCFA are then used as energetic subtrates by the host. Chronic lactose ingestion (6 days) also leads to a rise of the colonic concentrations in SCFA and lactate. However, the modification of the intestinal microbiota composition suggests an enhanced turn-over of the lactose metabolites. Concomitantly, a reduction of the inflammatory parameters of the colonic mucosa was underlined.To conclude, indirect calorimetry is a useful technique to detect lactose malabsorption and could be combined with other techniques for an optimised diagnostic. Besides, the enhancement of the SCFA absorption and the modulation of the intestinal microbiota (both composition and activity) may be successful alternatives to optimise the tolerance.Keywords: diagnostic of lactose malabsorption, respiratory quotient, SCFA colonic concentration and absorption, intestinal microbiota modulation, host adaptation.
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Virginie Alexandre. La malabsorption du lactose : Etude des modulations du microbiote intestinal et de l’adaptation de l’hôte malabsorbeur. Evaluation d’un nouveau marqueur diagnostique. Médecine humaine et pathologie. AgroParisTech, 2012. Français. ⟨NNT : 2012AGPT0081⟩. ⟨tel-03612077⟩

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