Fructooligosacharides Reduce Pseudomonas aeruginosa PAO1 Pathogenicity through Distinct Mechanisms

Pseudomonas aeruginosa is ubiquitously present in the environment and acts as an opportunistic pathogen on humans, animals and plants. We report here the effects of the prebiotic polysaccharide inulin and its hydrolysed form FOS on this bacterium. FOS was found to inhibit bacterial growth of strain PAO1, while inulin did not affect growth rate or yield in a significant manner. Inulin stimulated biofilm formation, whereas a dramatic reduction of the biofilm formation was observed in the presence of FOS. Similar opposing effects were observed for bacterial motility, where FOS inhibited the swarming and twitching behaviour whereas inulin caused its stimulation. In co-cultures with eukaryotic cells (macrophages) FOS and, to a lesser extent, inulin reduced the secretion of the inflammatory cytokines IL-6, IL-10 and TNF- a . Western blot experiments indicated that the effects mediated by FOS in macrophages are associated with a decreased activation of the NF- k B pathway. Since FOS and inulin stimulate pathway activation in the absence of bacteria, the FOS mediated effect is likely to be of indirect nature, such as via a reduction of bacterial virulence. Further, this modulatory effect is observed also with the highly virulent ptxS mutated strain. Co-culture experiments of P. aeruginosa with IEC18 eukaryotic cells showed that FOS reduces the concentration of the major virulence factor, exotoxin A, suggesting that this is a possible mechanism for the reduction of pathogenicity. The potential of these compounds as components of antibacterial and anti-inflammatory cocktails is discussed.The authors acknowledge financial support from FEDER funds and Fondo Social Europeo through grants from the Spanish Ministry of Economy and Competitiveness (grants SAF2011-22922, SAF2011-22812) the Andalusian regional government Junta de Andalucía (grant CVI-7335) and the Centre of Networked Biomedical Research on Hepatic and Digestive Diseases (CIBERehd) which is funded by the Carlos III Health Institute and the Ramón Areces Foundation, Spain

Absorption of alpha-ketoglutarate by the gastrointestinal tract of pigs

Only a small percentage of alpha-ketoglutarate (AKG) administered lumenally to pigs appears in the portal circulation. This has been attributed to mucosal metabolism, and possibly by limited absorption. Although transporters for di- and tricarboxylic acids, which includes the sodium-dependent transporter NaDC-1, have been detected in the small intestine, correlations with functional assays are lacking. Therefore, intact tissues from three regions of the small intestine, stomach, and colon of weaned pigs were used to measure rates of AKG absorption. Western analysis was used to detect NaDC-1 in the three regions of small intestine. Rates of AKG absorption were highest in the small intestine, lowest in the colon, and intermediate in the stomach. Immunoreactive NaDC-1 was detected in the small intestine and this coincided with a component of AKG absorption that was inhibited by AKG and succinate. In contrast, absorption of AKG was inhibitable by unlabeled AKG, but not succinate, in the stomach, and by neither in the colon. Feeding studies indicated that the amounts of AKG that might be included in practical diets for pigs would not (1) upregulate rates of AKG absorption or (2) exceed estimated capacities of the small intestine to absorb AKG. The present findings indicate that the efficacy of AKG as an alternative metabolic fuel for enterocytes to spare dietary amino acids is not limited by absorption

A non-terminal surgical procedure for chronic collection of exocrine pancreatic secretions from unrestrained dogs (Canis familiaris)

The ability of dogs to adaptively modulate secretion by the exocrine pancreas to match changes in the amounts and sources of macronutrients is poorly understood. We evaluated the use of re-entrant pancreatic catheters as a non-terminal, temporary approach for the chronic collection of exocrine pancreatic secretion using unrestrained dogs fed diets differing in composition. Re-entrant catheters were surgically placed in the accessory pancreatic duct of two adult mongrel dogs. Secretions were collected for 40 days, during which the dogs were fed three diets with different amounts and sources of macronutrients. The volume of secretion was recorded, protein content was measured, and the activities of trypsin, chymotrypsin, amylase, and lipase were assayed. Inter-dog variation was detected for the volume of secretion (ml/h) but not for protein content (mg/ml) or activities (U/ml) of the enzymes. The volume and composition of the secretion differed among diets. The responses were delayed about 4 days, were transient, and did not coincide with the changes in diet composition. We found that the re-entrant catheters were suitable for studying the exocrine pancreatic secretion of dogs. Our findings were inconclusive about the influence of diet but suggested that adult dogs have a limited and nonspecific response of pancreatic secretion

Functional oligosaccharides: application and manufacture.

Oligosaccharides are attracting increasing interest as prebiotic functional food ingredients. They can be extracted or obtained by enzymatic hydrolysis from a variety of biomass sources or synthesized from simple oligosaccharides by enzymatic transfer reactions. The major prebiotic oligosaccharides on the market are inulin, fructo-oligosaccharides, and galacto-oligosaccharides. They have been evaluated using a range of in vitro and in vivo methods, although there is a need for more large-scale human trials using modern microbiological methods. Prebiotics are being studied for their effects on gut health and well being and specific clinical conditions, including colon cancer, inflammatory bowel disease (IBD), acute infections, and mineral absorption. Developing understanding of the functional ecology of the human gut is influencing current thinking on what a prebiotic might achieve and is providing new targets for prebiotic intervention