No abstract

The development of the intestinal microbiota in the first years of life is a dynamic process significantly influenced by early-life nutrition. Pioneer bacteria colonizing the infant intestinal tract and the gradual diversification to a stable climax ecosystem plays a crucial role in establishing host-microbe interactions essential for optimal symbiosis. This colonization process and establishment of symbiosis may profoundly influence health throughout life. Recent developments in microbiologic cultivation-independent methods allow a detailed view of the key players and factors involved in this process and may further elucidate their roles in a healthy gut and immune maturation. Aberrant patterns may lead to identifying key microbial signatures involved in developing immunologic diseases into adulthood, such as asthma and atopic diseases. The central role of early-life nutrition in the developmental human microbiota, immunity, and metabolism offers promising strategies for prevention and treatment of such diseases. This review provides an overview of the development of the intestinal microbiota, its bidirectional relationship with the immune system, and its role in impacting health and disease, with emphasis on allergy, in early life.

The 16S rRNA gene is conserved across all bacteria and as such is routinely targeted in PCR surveys of bacterial diversity. PCR primer design aims to amplify as many different 16S rRNA gene sequences from as wide a range of organisms as possible, though there are no suitable 100% conserved regions of the gene, leading to bias. In the gastrointestinal tract, bifidobacteria are a key genus, but are often under-represented in 16S rRNA surveys of diversity. We have designed modified, ‘bifidobacteria-optimised’ universal primers, which we have demonstrated detection of bifidobacterial sequence present in DNA mixtures at 2% abundance, the lowest proportion tested. Optimisation did not compromise the detection of other organisms in infant faecal samples. Separate validation using fluorescence in situ hybridisation (FISH) shows that the proportions of bifidobacteria detected in faecal samples were in agreement with those obtained using 16S rRNA based pyrosequencing. For future studies looking at faecal microbiota, careful selection of primers will be key in order to ensure effective detection of bifidobacteria.

We showed that a partially hydrolyzed protein infant formula with specific prebiotics modulated the gut microbiota closer to that of breast-fed infants. Additionally, we identified a potential link between microbial activity and onset of eczema, which might reflect a suboptimal implementation of gut microbiota at specific developmental stages in infants at high risk for allergy.

BackgroundPrebiotics and probiotics (synbiotics) can modify gut microbiota and have potential in allergy management when combined with amino-acid-based formula (AAF) for infants with cow’s milk allergy (CMA).MethodsThis multicenter, double-blind, randomized controlled trial investigated the effects of an AAF-including synbiotic blend on percentages of bifidobacteria and Eubacterium rectale/Clostridium coccoides group (ER/CC) in feces from infants with suspected non-IgE-mediated CMA. Feces from age-matched healthy breastfed infants were used as reference (healthy breastfed reference (HBR)) for primary outcomes. The CMA subjects were randomized and received test or control formula for 8 weeks. Test formula was a hypoallergenic, nutritionally complete AAF including a prebiotic blend of fructo-oligosaccharides and the probiotic strain Bifidobacterium breve M-16V. Control formula was AAF without synbiotics.ResultsA total of 35 (test) and 36 (control) subjects were randomized; HBR included 51 infants. At week 8, the median percentage of bifidobacteria was higher in the test group than in the control group (35.4% vs. 9.7%, respectively; P<0.001), whereas ER/CC was lower (9.5% vs. 24.2%, respectively; P<0.001). HBR levels of bifidobacteria and ER/CC were 55% and 6.5%, respectively.ConclusionAAF including specific synbiotics, which results in levels of bifidobacteria and ER/CC approximating levels in the HBR group, improves the fecal microbiota of infants with suspected non-IgE-mediated CMA.

Background: In addition to contemporary lifestyle factors that contribute to the increased obesity prevalence worldwide, early nutrition is associated with sustained effects on later life obesity. We hypothesized that physical properties of dietary lipids contribute to this nutritional programming. We developed a concept infant formula (IMF) with large, phospholipidcoated lipid droplets (Nuturis; Danone Research, Paris, France) and investigated its programming effect on metabolic phenotype later in life. Methods: Male c57Bl/6j mice were fed a control formula (control IMF) or Nuturis (concept IMF) diet between postnatal day (PN)16 and PN42. all mice were subsequently fed a Western-style diet (WsD) until PN126. Body composition was monitored repeatedly by dual-energy X-ray absorptiometry between PN42 and PN126. results: concept IMF slightly increased lean body mass as compared with control IMF at PN42 but did not affect fat mass. Upon 84 d of WsD feeding, the concept IMF group showed reduced fat accumulation as compared with control IMF. In addition, fasting plasma leptin, resistin, glucose, and lipids were significantly lower in the concept IMF group. conclusion: Large phospholipid-coated lipid droplets in young mice reduced fat accumulation and improved metabolic profile in adulthood. These data emphasize that physical properties of early dietary lipids contribute to metabolic programming.

Background: Children with cow's milk allergy (CMA) are at risk for inadequate nutritional intake and growth. Dietary management of CMA, therefore, requires diets that are not only hypoallergenic but also support adequate growth in this population. This study assessed growth of CMA infants when using a new amino acid-based formula (AAF) with prebiotics and probiotics (synbiotics) and evaluated its safety in the intended population. Methods: In a prospective, randomized, double-blind controlled study, full-term infants with diagnosed CMA received either an AAF (control; n = 56) or AAF with synbiotics (oligofructose, long-chain inulin, acidic oligosaccharides, Bifidobacterium breve M-16V) (test; n = 54) for 16 wk. Primary outcome was growth, measured as weight, length and head circumference. Secondary outcomes included allergic symptoms and stool characteristics. Results: Average age (AESD) of infants at inclusion was 4.5 AE 2.4 months. Both formulas equally supported growth according to WHO 2006 growth charts and resulted in similar increases of weight, length and head circumference. At week 16, differences (90% CI) in Z-scores (test-control) were as follows: weight 0.147 (À0.10; 0.39, p = 0.32), length À0.299 (À0.69; 0.09, p = 0.21) and head circumference 0.152 (À0.15; 0.45, p = 0.40). Weight-for-age and length-for-age Z-scores were not significantly different between the test and control groups. Both formulas were well tolerated and reduced allergic symptoms; the number of adverse events was not different between the groups. Conclusions: This is the first study that shows that an AAF with a specific synbiotic blend, suitable for CMA infants, supports normal growth and growth similar to the AAF without synbiotics.This clinical trial is registered as NCT00664768.

BackgroundPerturbation of commensal intestinal microbiota has been associated with several autoimmune diseases. Mice deficient in interleukin-1 receptor antagonist (Il1rn −/− mice) spontaneously develop autoimmune arthritis and are susceptible to other autoimmune diseases such as psoriasis, diabetes, and encephalomyelitis; however, the mechanisms of increased susceptibility to these autoimmune phenotypes are poorly understood. We investigated the role of interleukin-1 receptor antagonist (IL-1Ra) in regulation of commensal intestinal microbiota, and assessed the involvement of microbiota subsets and innate and adaptive mucosal immune responses that underlie the development of spontaneous arthritis in Il1rn −/− mice.ResultsUsing high-throughput 16S rRNA gene sequencing, we show that IL-1Ra critically maintains the diversity and regulates the composition of intestinal microbiota in mice. IL-1Ra deficiency reduced the intestinal microbial diversity and richness, and caused specific taxonomic alterations characterized by overrepresented Helicobacter and underrepresented Ruminococcus and Prevotella. Notably, the aberrant intestinal microbiota in IL1rn −/− mice specifically potentiated IL-17 production by intestinal lamina propria (LP) lymphocytes and skewed the LP T cell balance in favor of T helper 17 (Th17) cells, an effect transferable to WT mice by fecal microbiota. Importantly, LP Th17 cell expansion and the development of spontaneous autoimmune arthritis in IL1rn −/− mice were attenuated under germ-free condition. Selective antibiotic treatment revealed that tobramycin-induced alterations of commensal intestinal microbiota, i.e., reduced Helicobacter, Flexispira, Clostridium, and Dehalobacterium, suppressed arthritis in IL1rn −/− mice. The arthritis phenotype in IL1rn −/− mice was previously shown to depend on Toll-like receptor 4 (TLR4). Using the ablation of both IL-1Ra and TLR4, we here show that the aberrations in the IL1rn −/− microbiota are partly TLR4-dependent. We further identify a role for TLR4 activation in the intestinal lamina propria production of IL-17 and cytokines involved in Th17 differentiation preceding the onset of arthritis.ConclusionsThese findings identify a critical role for IL1Ra in maintaining the natural diversity and composition of intestinal microbiota, and suggest a role for TLR4 in mucosal Th17 cell induction associated with the development of autoimmune disease in mice.Electronic supplementary materialThe online version of this article (doi:10.1186/s40168-017-0278-2) contains supplementary material, which is available to authorized users.