Gut Microbiota of Young Children Living in Four Brazilian Cities.

Recent studies have demonstrated that gut microbiota development is influenced by human biogeographic factors such as race, ethnicity, diet, lifestyle or culture-specific variations, and other environmental influences. However, biogeographic variation in gut microbiota assembly remains largely unexplored in Latin America. In this paper, we compared food recall information and microbiota composition of toddlers living in geographically separated urban populations within four states of Brazil. 16S RNA gene sequencing revealed that alpha diversity was similar between the four different populations. Gut microbiota compositions were dominated by members of the phyla Firmicutes and Bacteroidetes, resembling a more adult-like microbiota as compared with those of Western European toddlers of similar age. These findings suggest that inter-individual and nutrition-induced differences were apparent in the fecal microbiota. We conclude that urban dietary pattern plays a larger role in influencing the gut microbiota composition than do biogeographic factors.

Differentiation of Bifidobacterium longum subspecies longum and infantis by quantitative PCR using functional gene targets.

BACKGROUND: Members of the genus Bifidobacterium are abundant in the feces of babies during the exclusively-milk-diet period of life. Bifidobacterium longum is reported to be a common member of the infant fecal microbiota. However, B. longum is composed of three subspecies, two of which are represented in the bowel microbiota (B. longum subsp. longum; B. longum subsp. infantis). B. longum subspecies are not differentiated in many studies, so that their prevalence and relative abundances are not accurately known. This may largely be due to difficulty in assigning subspecies identity using DNA sequences of 16S rRNA or tuf genes that are commonly used in bacterial taxonomy. METHODS: We developed a qPCR method targeting the sialidase gene (subsp. infantis) and sugar kinase gene (subsp. longum) to differentiate the subspecies using specific primers and probes. Specificity of the primers/probes was tested by in silico, pangenomic search, and using DNA from standard cultures of bifidobacterial species. The utility of the method was further examined using DNA from feces that had been collected from infants inhabiting various geographical regions. RESULTS: A pangenomic search of the NCBI genomic database showed that the PCR primers/probes targeted only the respective genes of the two subspecies. The primers/probes showed total specificity when tested against DNA extracted from the gold standard strains (type cultures) of bifidobacterial species detected in infant feces. Use of the qPCR method with DNA extracted from the feces of infants of different ages, delivery method and nutrition, showed that subsp. infantis was detectable (0-32.4% prevalence) in the feces of Australian (n = 90), South-East Asian (n = 24), and Chinese babies (n = 91), but in all cases at low abundance (<0.01-4.6%) compared to subsp. longum (0.1-33.7% abundance; 21.4-100% prevalence). DISCUSSION: Our qPCR method differentiates B. longum subspecies longum and infantis using characteristic functional genes. It can be used as an identification aid for isolates of bifidobacteria, as well as in determining prevalence and abundance of the subspecies in feces. The method should thus be useful in ecological studies of the infant gut microbiota during early life where an understanding of the ecology of bifidobacterial species may be important in developing interventions to promote infant health.

Effect of Synbiotic on the Gut Microbiota of Cesarean Delivered Infants: A Randomized, Double-blind, Multicenter Study.

We determined the effect of short-chain galacto-oligosaccharides (scGOS), long-chain fructo-oligosaccharides (lcFOS) and Bifidobacterium breve M-16V on the gut microbiota of cesarean-born infants. Infants were randomized to receive a standard formula (control), the same with scGOS/lcFOS and B. breve M-16V (synbiotic), or with scGOS/lcFOS (prebiotic) from birth until week 16, 30 subjects born vaginally were included as a reference group. Synbiotic supplementation resulted in a higher bifidobacteria proportion from day 3/5 (P < 0.0001) until week 8 (P = 0.041), a reduction of Enterobacteriaceae from day 3/5 (P = 0.002) till week 12 (P = 0.016) compared to controls. This was accompanied with a lower fecal pH and higher acetate. In the synbiotic group, B. breve M-16V was detected 6 weeks postintervention in 38.7% of the infants. This synbiotic concept supported the early modulation of Bifidobacterium in C-section born infants that was associated with the emulation of the gut physiological environment observed in vaginally delivered infants.

Hypoxia increases adipogenesis and affects adipocytokine production in orbital fibroblasts-a possible explanation of the link between smoking and Graves' ophthalmopathy.

AIM: To assess the effects of hypoxia on human orbital fibroblasts (OF) on adipogenesis and adipocytokine production. METHODS: Human OF were derived from tissues obtained from patients with Graves' ophthalmopathy (GO) and from patients without known thyroid diseases undergoing blepharoplasty. The OF were cultured separately under normoxic and hypoxic conditions. Comparisons of adipocytokine concentrations using multiplex ELISA and lipid accumulation in the cells using Oil Red O staining were subsequently performed. RESULTS: There was increased adipogenesis in OF from GO subject when exposed to hypoxic culture conditions. This was not observed in OF from normal controls. Hypoxia led to an increase in leptin and a decrease in MCP-1 secretion in OF cultures. CONCLUSION: Hypoxia induces adipogenesis in OF and may represent a mechanism by which smoking contributes to deterioration of GO. We also found novel changes to leptin and MCP-1 production in OF cultures exposed to hypoxia suggesting important roles of these cytokines in the disease process.