Threonine utilization for synthesis of acute phase proteins, intestinal proteins, and mucins is increased during sepsis in rats

International audienceWe hypothesized that the dietary threonine demand for the anabolic response may be increased more than that of other essential amino acids during sepsis. Using a flooding dose of either L-[1-13C]valine or L-[U-13C]threonine, we measured valine and threonine utilization for syntheses of plasma proteins (minus albumin), and wall, mucosal, and mucin proteins of the small intestine in infected (INF; d2 and d6 of postinfection) and control pair-fed (PF) rats. At d2, the protein absolute synthesis rate (ASR) of INF rats was 21% (mucins) to 41% (intestinal wall) greater than that of PF when measured using valine as tracer, and 45% (mucosa) to 113% (mucins) greater than that of PF when measured with threonine as tracer. Plasma protein ASR was higher in INF than in PF rats, reaching 5- to 6-fold the value of PF. The utilization of both amino acid tracers for the protein synthesis was significantly increased by the infection in all compartments studied. The daily increased absolute threonine utilization for protein synthesis in gut wall plus plasma proteins was 446 micromol/d compared with 365 micromol/d for valine, and it represented 2.6 times the dietary threonine intake of rats at d2. Most changes in protein ASR and threonine utilization observed at d6 of postinfection were limited. In conclusion, sepsis increased the utilization of threonine for the anabolic splanchnic response. Because this threonine requirement is likely covered by muscle protein mobilization, increasing the threonine dietary supply would be an effective early nutritional management for patients with sepsis

Specific amino acids increase mucin synthesis and microbiota in dextran sulfate sodium-treated rats

International audienceDuring the anabolic response associated with inflammation, mucin synthesis and colonic protection may be compromised by the limited availability of specific amino acids. We therefore determined the effect of dietary amino acid supplementation on the microbiota, mucin status, and mucosal damage in dextran sulfate sodium (DSS)-treated rats. From 8 d before to 28 d after colitis induction, male Sprague-Dawley rats (10 mo old, n = 8/group) were fed a control diet supplemented or not with 2 different doses of an amino acid cocktail containing L-threonine, L-serine, L-proline, and L-cysteine. All diets were isonitrogenous (adjusted with L-alanine). The higher dose of amino acids increased the number of Muc2-containing goblet cells in the surface epithelium of the ulcerated area, stimulated mucin production in the colon, and restored the mucin amino acid composition and mucosal content to healthy, control values. The colonic mucin synthesis rate was specifically stimulated by 95%, whereas the protein turnover was unchanged. All bacterial populations, markedly altered by the DSS treatment, were promoted. In conclusion, in inflammatory situations, an increase in threonine, serine, proline, and cysteine dietary supply can promote mucin synthesis, reequilibrate the gut microbiota, and thus favor colonic protection and mucosal healing