Specific gut microbiome signatures and the associated pro-inflamatory functions are linked to pediatric allergy and acquisition of immune tolerance.

Understanding the functional potential of the gut microbiome is of primary importance for the design of innovative strategies for allergy treatment and prevention. Here we report the gut microbiome features of 90 children affected by food (FA) or respiratory (RA) allergies and 30 age-matched, healthy controls (CT). We identify specific microbial signatures in the gut microbiome of allergic children, such as higher abundance of Ruminococcus gnavus and Faecalibacterium prausnitzii, and a depletion of Bifidobacterium longum, Bacteroides dorei, B. vulgatus and fiber-degrading taxa. The metagenome of allergic children shows a pro-inflammatory potential, with an enrichment of genes involved in the production of bacterial lipo-polysaccharides and urease. We demonstrate that specific gut microbiome signatures at baseline can be predictable of immune tolerance acquisition. Finally, a strain-level selection occurring in the gut microbiome of allergic subjects is identified. R. gnavus strains enriched in FA and RA showed lower ability to degrade fiber, and genes involved in the production of a pro-inflammatory polysaccharide. We demonstrate that a gut microbiome dysbiosis occurs in allergic children, with R. gnavus emerging as a main player in pediatric allergy. These findings may open new strategies in the development of innovative preventive and therapeutic approaches. Trial: NCT04750980.

Selenium nanoparticles in poultry feed modify gut microbiota and increase abundance of Faecalibacterium prausnitzii.

The poultry industry aims to improve productivity while maintaining the health and welfare of flocks. Pathogen control has been achieved through biosecurity, vaccinations and the use of antibiotics. However, the emergence of antibiotic resistance, in animal and human pathogens, has prompted researchers and chicken growers alike to seek alternative approaches. The use of new and emerging approaches to combat pathogen activity including nanotechnology, in particular, silver nanoparticles (NPs), has been found to not only eradicate pathogenic bacteria but also include issues of toxicity and bioaccumulation effects. Other novel metal nanoparticles could provide this pathogen reducing property with a more tailored and biocompatible nanomaterial for the model used, something our study represents. This study investigated the benefits of nanomaterial delivery mechanisms coupled with important health constituents using selenium as a biocompatible metal to minimise toxicity properties. Selenium NPs were compared to two common forms of bulk selenium macronutrients already used in the poultry industry. An intermediate concentration of selenium nanoparticles (0.9 mg/kg) demonstrated the best performance, improving the gut health by increasing the abundance of beneficial bacteria, such as Lactobacillus and Faecalibacterium, and short-chain fatty acids (SCFAs), in particular butyric acid. SCFAs are metabolites produced by the intestinal tract and are used as an energy source for colonic cells and other important bodily functions. Selenium nanoparticles had no significant effect on live weight gain or abundance of potentially pathogenic bacteria.

Gut microbiota composition in relation to the metabolic response to 12-week combined polyphenol supplementation in overweight men and women.

BACKGROUND/OBJECTIVES: The intestinal microbiota may have a profound impact on host metabolism. As evidence suggests that polyphenols affect substrate utilization, the present study aimed to investigate the effects of polyphenol supplementation on intestinal microbiota composition in humans. Furthermore, we examined whether (changes in) gut microbiota composition may determine the metabolic response to polyphenol supplementation. SUBJECTS/METHODS: In this randomized, double-blind, placebo (PLA)-controlled trial, 37 overweight and obese men and women (18 males/19 females, 37.8±1.6 years, body mass index: 29.6±0.5 kg/m2) received either epigallocatechin-3-gallate and resveratrol (EGCG+RES, 282 and 80 mg/day, respectively) or PLA for 12 weeks. Before and after intervention, feces samples were collected to determine microbiota composition. Fat oxidation was assessed by indirect calorimetry during a high-fat mixed meal test (2.6 MJ, 61 energy% fat) and skeletal muscle mitochondrial oxidative capacity by means of ex vivo respirometry on isolated skeletal muscle fibers. Body composition was measured by dual-energy X-ray absorptiometry. RESULTS: Fecal abundance of Bacteroidetes was higher in men as compared with women, whereas other assessed bacterial taxa were comparable. EGCG+RES supplementation significantly decreased Bacteroidetes and tended to reduce Faecalibacterium prausnitzii in men (P=0.05 and P=0.10, respectively) but not in women (P=0.15 and P=0.77, respectively). Strikingly, baseline Bacteroidetes abundance was predictive for the EGCG+RES-induced increase in fat oxidation in men but not in women. Other bacterial genera and species were not affected by EGCG+RES supplementation. CONCLUSIONS: We demonstrated that 12-week EGCG+RES supplementation affected the gut microbiota composition in men but not in women. Baseline microbiota composition determined the increase in fat oxidation after EGCG+RES supplementation in men.