Effect of Molecules' Physicochemical Properties on Whey Protein/Alginate Hydrogel Rheology, Microstructure and Release Profile.

The encapsulation of molecules with different physicochemical properties (theophylline, blue dextran, salicylic acid and insulin) in whey protein (WP) and alginate (ALG) microparticles (MP) for oral administration was studied. MP based on WP/ALG were prepared by a cold gelation technique and coated with WP solution after reticulation. Molecules influenced polymer solution viscosity and elasticity, resulting in differences regarding encapsulation efficiency (from 23 to 100%), MP structure and swelling (>10%) and in terms of pH tested. Molecule release was due to diffusion and/or erosion of MP and was very dependent on the substance encapsulated. All the loaded MP were successfully coated, but variation in coating thickness (from 68 to 146 µm) and function of the molecules encapsulated resulted in differences in molecule release (5 to 80% in 1 h). Gel rheology modification, due to interactions between WP, ALG, calcium and other substances, was responsible for the highlighted differences. Measuring rheologic parameters before extrusion and reticulation appeared to be one of the most important aspects to study in order to successfully develop a vector with optimal biopharmaceutical properties. Our vector seems to be more appropriate for anionic high-molecular-weight substances, leading to high viscosity and elasticity and to MP enabling gastroresistance and controlled release of molecules at intestinal pH.

Anti-infectious properties of the probiotic Saccharomyces cerevisiae CNCM I-3856 on enterotoxigenic E. coli (ETEC) strain H10407.

Enterotoxigenic Escherichia coli (ETEC) are major food-borne pathogens responsible for traveler's diarrhea. The production of adhesins and the secretion of enterotoxins constitute the major virulence traits of the bacteria. Treatments are mainly symptomatic and can involve antibiotherapy. However, given the rise of antibiotic resistance worldwide, there is an urgent need for the development of new preventive strategies for the control of ETEC infections. Among them, a promising approach is the use of probiotics. The aim of this study was to investigate, using complementary in vitro and in vivo approaches, the inhibitory potential of the yeast Saccharomyces cerevisiae CNCM I-3856 against the human ETEC reference strain H10407. In conventional culture media, S. cerevisiae significantly reduced ETEC growth and toxin production. The yeast also inhibited bacterial adhesion to mucin-agar and intestinal Caco-2/TC7 cells in a dose-dependent manner. Lastly, pre-treatment with S. cerevisiae inhibited interleukin-8 production by ETEC-infected intestinal cells. In streptomycin-treated mice, the probiotic yeast decreased bacterial colonization, mainly in the ileum, the main site of ETEC pathogenesis. For the first time, this study shows that the probiotic yeast S. cerevisiae CNCM I-3856 can exert an anti-infectious activity against a human ETEC strain through a multi-targeted approach, including inhibition of bacterial growth and toxin production, reduction of bacterial adhesion to mucins and intestinal epithelial cells, and suppression of ETEC-induced inflammation. Interestingly, the highest activity was obtained with a prophylactic treatment. Further studies will aim to assess the effect of the yeast on ETEC survival and virulence under human simulated digestive conditions.

Immunonutrition stimulates immune functions and antioxidant defense capacities of leukocytes in radiochemotherapy-treated head & neck and esophageal cancer patients: A double-blind randomized clinical trial.

BACKGROUND: Immunonutrition has been reported to improve the immune status of perioperative cancer patients, thereby reducing complications and length of hospital stay. AIM: This study aimed to assess whether immunonutrition enriched in arginine, EPA & DHA and nucleotides could impact the immune cells responses in head & neck and esophageal cancer patients treated by radiochemotherapy (RCT). METHODS: A double-blind clinical trial was carried out in 28 patients randomized into two groups, receiving either an immunomodulating enteral nutrition formula (IEN, n = 13, Impact(®), Nestlé) or an isoenergetic isonitrogenous standard enteral nutrition formula (SEN, n = 15) throughout RCT (5-7 weeks). After isolation from whole blood, immune cells metabolism and functions were assessed at the beginning (Db) and at the end (De) of RCT. RESULTS: Immunonutrition maintained CD4(+)/CD8(+) T-lymphocyte counts ratio and CD3 membrane expression between Db and De. Polymorphonuclear cells CD62L and CD15 densities and ROS production were increased in IEN patients. Peripheral blood mononuclear cells (PBMC) production of pro-inflammatory prostaglandin-E2 was stable in IEN patients and lower than in SEN patients at De. Genes coding for immune receptors, antioxidant enzymes and NADPH oxidase subunits were overexpressed in the PBMC of IEN vs SEN patients at De. CONCLUSION: Immunonutrition can enhance immune cell responses through the modulation of their phenotypes and functions. By modulating the gene expression of immune cells, immunonutrition could make it easier for the organism to adapt to the systemic inflammation and oxidative stress induced by RCT. CLINICAL TRIAL REGISTRATION: This clinical trial has been registered on ClinicalTrial.gov website: NCT00333099.

Genetically engineered yeasts as a new delivery vehicle of active compounds to the digestive tract: in vivo validation of the concept in the rat.

An innovative "biodrug" concept based on oral administration of living recombinant microorganisms as a vehicle to deliver active compounds directly into the digestive tract has recently been developed. To validate this concept, we studied a recombinant Saccharomyces cerevisiae strain in order to investigate its viability and its ability to produce a protein (glutathione-S-transferase (GST)-V(5)H(6)) in the rat. Following oral administration, the recombinant yeast showed a survival rate of around 40% in the upper parts of the digestive tract, but was more sensitive to the conditions in the large intestinal, where viability dropped to 1%. Western blot analysis was able to detect the model protein throughout the digestive tract, including stomach, duodenum, jejunum (proximal, median and distal), ileum, cecum and colon. The gastrointestinal sac technique was employed to quantify GST-V(5)H(6) in all the digestive compartments. These results suggest that S. cerevisiae may represent a useful host for producing compounds of interest directly in the digestive tract.

Recombinant Saccharomyces cerevisiae strain expressing a model cytochrome P450 in the rat digestive environment: viability and bioconversion activity.

An innovative "biodrug" concept, based on the oral administration of living recombinant microorganisms, has recently emerged for the prevention or treatment of various diseases. An engineered Saccharomyces cerevisiae strain expressing plant P450 73A1 (cinnamate-4-hydroxylase [CA4H] activity) was used, and its survival and ability to convert trans-cinnamic acid (CIN) into p-coumaric acid (COU) were investigated in vivo. In rats, the recombinant yeast was resistant to gastric and small intestinal secretions but was more sensitive to the conditions found in the large intestine. After oral administration of yeast and CIN, the CA4H activity was shown in vivo, with COU being found throughout the rat's digestive tract and in its urine. The bioconversion reaction occurred very fast, with most of the COU being produced within the first 5 min. The gastrointestinal sac technique demonstrated that the recombinant yeast was able to convert CIN into COU (conversion rate ranging from 2 to 5%) in all the organs of the rat's digestive tract: stomach, duodenum, jejunum, ileum, cecum, and colon. These results promise new opportunities for the development of drug delivery systems based on engineered yeasts catalyzing a bioconversion reaction directly in the digestive tract.