Infant Gut Microbiota Composition Research Articles

A gut-focused perinatal dietary intervention is associated with lower alpha diversity of the infant gut microbiota: results from a randomised controlled trial

ABSTRACT Objectives: In experimental models, the prenatal diet influences gut microbiota composition in mothers and offspring; however, it is unclear whether this occurs in humans. We investigated the effects of a gut-focused perinatal dietary intervention on maternal and infant gut microbiota composition four weeks after birth. Methods: This randomised controlled trial randomised pregnant women to receive dietary advice as part of standard care, or additionally receive a dietary intervention focused on the Australian Dietary Guidelines and increasing prebiotic and probiotic/fermented food intakes (ACTRN12616000936426). Study assessments occurred from gestation week 26 (baseline) to four weeks postpartum (follow-up). Faecal samples, collected at baseline for mothers, and follow-up for mothers and infants, underwent 16SrRNA sequencing. The primary outcome was a between-group mean difference in infant faecal Shannon index. Secondary outcomes included between-group differences in other microbiota measures, including maternal change from baseline CLR-transformed Prevotella abundance. Results: Forty-four women and 45 infants completed the study. The mean Shannon index of infants in the intervention group was −0.35 (95% CI: −0.64, −0.06, SD: 0.52) units lower than control group infants, corresponding to a medium effect size (Cohen’s D: −0.74, 95% CI: −1.34, −0.13). The findings were similar using other metrics of α-diversity. There were no between-group differences in β-diversity, nor any differentially abundant taxa in infants. The intervention increased abundances of the genus Prevotella in mothers compared to controls. Discussion: This gut-focused perinatal dietary intervention was associated with differences in the maternal and infant gut microbiota composition. Larger studies are required to replicate and extend these findings.

Microbiota from human infants consuming secretors or non-secretors mothers' milk impacts the gut and immune system in mice.

Early life factors like neonatal diet modulate gut microbiota, which is important for the optimal gut and immune function. One such factor, human milk oligosaccharides (HMOs), the composition of which is determined by maternal secretor status, has a profound effect on infant gut microbiota. However, how the infant gut microbiota composition determined by maternal secretor status or consumption of infant formula devoid of HMOs impacts infant intestinal ammorphology, gene expression, and immune signature is not well explored. This study provides insights into the differential establishment of infant microbiota derived from infants fed by secretor or non-secretor mothers milk or those consuming infant formula and demonstrates that the secretor status of mothers promotes Bifidobacteria and Bacteroides sps. establishment. This study also shows that supplementation of pooled HMOs in mice changed immune cell composition in the spleen and mesenteric lymph nodes and immunoglobulins in circulation. Hence, this study highlights that maternal secretor status has a role in infant gut microbiota composition, and this, in turn, can impact host gut and immune system.

The application of High-Resolution Nuclear Magnetic Resonance (HR NMR) in metabolomic analyses of meconium and stool in newborns. A preliminary pilot study of MABEL project: Metabolomics approach for the assessment of Baby-Mother Enteric Microbiota Legacy

BackgroundThe microbial population living in our intestines plays a key role in several metabolic, nutritional, physiological, and immunological processes. It is known that infant gut microbiota composition has both horizontal transmission delivery and environmental conditions and a vertical one, from mother to child, related to how the infant is fed (breastfed or infant formula). Detailed information on the composition of meconium and feces from newborns may help predict the most prevalent and hazardous conditions affecting pregnancies, mothers, and babies, including pre-term birth, preeclampsia, and gestational diabetes mellitus for example. MethodsThis work aims to demonstrate the feasibility of the whole High-Resolution proton Nuclear Magnetic Resonance (1H HR NMR) procedure in metabolomic analysis in preterm newborns. Thus, multiple samples of meconium and stool were collected from 3 pairs of premature twins and their metabolite profiles were acquired and exploited by combining the NMR technique with univariate and multivariate analysis. ResultsThe analysis showed that an impact on the metabolite profile was visible concerning both the sex of the newborns and the couplet of origin. Most of the variation between twin couplets was seen with butyric acid concentration in meconium/stool samples. ConclusionsDespite the low number of samples, the described NMR procedure showed to be a suitable approach to evaluate the similarities of the molecular profiles of different samples, offering a non-invasive and informative approach to understanding the metabolic and nutritional status of preterm infants. Future metabolomic analysis should be supported by microbiome analysis, such multiomic approach will provide more complex view on development of preterm newborns.

Maternal Exposure to Endocrine-Disrupting Chemicals: Analysis of Their Impact on Infant Gut Microbiota Composition.

Endocrine disruptors (EDCs) are chemicals that interfere with the endocrine system. EDC exposure may contribute to the development of obesity, type 2 diabetes, and cardiovascular diseases by impacting the composition of an infant's gut microbiota during the first 1000 days of life. To explore the relationship between maternal urinary levels of Bisphenol-A and phthalates (UHPLC-MS/MS), and the composition of the infant gut microbiota (16S rDNA) at age 12 months (T3) and, retrospectively, at birth (T0), 1 month (T1), and 6 months (T2), stool samples from 20 infants breastfed at least once a day were analyzed. Metataxonomic bacteria relative abundances were correlated with EDC values. Based on median Bisphenol-A levels, infants were assigned to the over-exposed group (O, n = 8) and the low-exposed group (B, n = 12). The B-group exhibited higher gut colonization of the Ruminococcus torques group genus and the O-group showed higher abundances of Erysipelatoclostridium and Bifidobacterium breve. Additionally, infants were stratified as high-risk (HR, n = 12) or low-risk (LR, n = 8) exposure to phthalates, based on the presence of at least three phthalates with concentrations exceeding the cohort median values; no differences were observed in gut microbiota composition. A retrospective analysis of gut microbiota (T0-T2) revealed a disparity in β-diversity between the O-group and the B-group. Considering T0-T3, the Linear Discriminant Effect Size indicated differences in certain microbes between the O-group vs. the B-group and the HR-group vs. the LR-group. Our findings support the potential role of microbial communities as biomarkers for high EDC exposure levels. Nevertheless, further investigations are required to deeply investigate this issue.

Effect of Probiotic Supplementation on the Gut Microbiota Composition of Infants Delivered by Cesarean Section: An Exploratory, Randomized, Open-label, Parallel-controlled Trial.

Infants born via cesarean section (CS) are at an increased risk of immune-related diseases later in life, potentially due to altered gut microbiota. Recent research has focused on the administration of probiotics in the prevention of gut microbiota dysbiosis in neonates delivered by CS. This study was performed to investigate the effects of probiotic supplementation on the gut microbiota of CS-delivered infants. Thirty full-term neonates delivered by CS were randomized into the intervention (supplemented orally with a probiotic containing Bifidobacterium longum, Lactobacillus acidophilus, and Enterococcus faecalis for 2weeks) and control groups. Stool samples were collected at birth and 2weeks and 42days after birth. The composition of the gut microbiota was analyzed using 16S rRNA sequencing technology. The applied bacterial strains were abundant in the CS-delivered infants supplemented with probiotics. Probiotics increased the abundance of some beneficial bacteria, such as Bacteroides, Acinetobacter, Veillonella, and Faecalibacterium. Low colonization of Klebsiella, a potentially pathogenic bacterium, was observed in the intervention group. Our results showed that probiotics supplemented immediately after CS enriched the gut microbiota composition and altered the pattern of early gut colonization. registration number NCT05086458.

Long-term and trimester-specific effects of prenatal stress on the child gut microbiota

ObjectiveStress is common among pregnant individuals and is associated with an altered gut microbiota composition in infants. It is unknown if these compositional changes persist into the preschool years when the gut microbiota reaches an adult-like composition. This study aimed to investigate if indicators of prenatal stress (i.e., psychological distress and stress-related physiology) are associated with children’s gut microbiota composition and metabolites at 3–4 years of age. MethodsMaternal-child pairs (n = 131) were from the Alberta Pregnancy Outcomes and Nutrition (APrON) cohort. Each trimester, psychological distress was measured as symptoms of anxiety (Symptom Checklist-90-R) and depressed mood (Edinburgh Postnatal Depression Scale), whereas salivary cortisol was quantified as a measure of stress-related physiology. Child stool samples were collected at 3–4 years to evaluate gut microbiota composition using 16S rRNA gene sequencing and fecal metabolome using liquid chromatography with tandem mass spectrometry (LC-MS/MS). Associations between prenatal distress and cortisol with the gut microbiota were determined using Pearson and Spearman correlations and corrected for multiple testing. Associations between prenatal distress and cortisol with the fecal metabolome were assessed using Metaboanalyst. ResultsSymptoms of depressed mood during the 2nd and 3rd trimesters and anxiety during the 2nd trimester of pregnancy were associated with increased alpha diversity of the child’s gut microbiota. Cortisol levels during the 1st trimester were also associated with increased Faith PD diversity (r = 0.32), whereas cortisol levels during the 2nd trimester were associated with reduced Shannon diversity (r = −0.27). Depression scores during the 2nd and 3rd trimesters were associated with reductions in the relative abundances of Eggerthella, Parasutterella, and increases in Ruminococcaceae (rs = −0.28, rs = −0.32, rs = 0.32, respectively), as well as the fecal metabolome (e.g., branched-chain amino acid metabolism). Cortisol levels during the 2nd trimester correlated with 7 bacterial taxa, whereas 1st-trimester cortisol levels were associated with the child’s fecal metabolome. ConclusionsPrenatal distress and cortisol were associated with both child gut microbiota composition and fecal metabolome at preschool age. Understanding these associations may allow for the identification of microbiota-targeted interventions to support child developmental outcomes affected by prenatal stress.

Sources of gut microbiota variation in a large longitudinal Finnish infant cohort.

Although the infant gut microbiota has been extensively studied, comprehensive assessment on the microbiota determinants including technical variables has not been performed in large infant cohorts. We studied the effect of 109 variables on the 16S rRNA gene amplicon-based gut microbiota profiles of infants sampled longitudinally from three weeks to two years of life in the Finnish HELMi birth cohort. Spot faecal samples from both parents were included for intra-family analyses, totalling to 7657 samples from 985 families that were evaluated for beta-diversity patterns using permutational multivariate analysis on Bray-Curtis distances, and differential abundance testing and alpha-diversity for variables of interest. We also assessed the effect of different taxonomic levels and distance methods. In time point-specific models, the largest share of variation explained, up to 2-6%, were seen in decreasing order for the DNA extraction batch, delivery mode and related perinatal exposures, defecation frequency and parity/siblings. Variables describing the infant gastrointestinal function were continuously important during the first two years, reflecting changes in e.g., feeding habits. The effect of parity/siblings on infant microbiota was modified by birth mode and exposure to intrapartum antibiotics, exemplifying the tight interlinkage of perinatal factors relevant for infant microbiota research. In total, up to 19% of the biological microbiota variation in the infant gut could be explained. Our results highlight the need to interpret variance partitioning results in the context of each cohort's characteristics and microbiota processing. Our study provides a comprehensive report of key factors associated with infant gut microbiota composition across the two first years of life in a homogenous cohort. The study highlights possible important future research areas and confounding factors to be considered. This research was supported by Business Finland, Academy of Finland, Foundation for Nutrition Research and the Doctoral Program in Microbiology and Biotechnology, University of Helsinki, Finland.

2'-Fucosyllactose (2'-FL) changes infants gut microbiota composition and their metabolism in a host-free human colonic model

BackgroundBreast milk is critical for neonates, providing the necessary energy, nutrients, and bioactive compounds for growth and development. Research indicated that human milk oligosaccharides (HMOs) have been shown to shape a beneficial gut microbiota, as well as their metabolism (e.g. short-chain fatty acids). 2′-Fucosyllactose (2′-FL) is one major HMO that composed of 30% of total HMOs. ObjectivesThis study aimed to understand the impact of 2′-FL on the composition and metabolism of infant gut microbiota. MethodsOur study utilized an in-vitro human colonic model (HCM) to investigate the host-free interactions between 2′-FL and infant gut microbiota. To simulate the infant gut microbiota, we inoculated the HCM system with eight representative bacterial species from infant gut microbiota. The effects of 2′-FL on the gut microbial composition and their metabolism were determined through real-time quantitative PCR and liquid-chromatography mass spectrometry (LC/MS). The obtained data were analyzed using Compound Discoverer 3.1 and MetaboAnalyst 4.0. ResultsOur study findings suggest that the intervention of 2′-FL in HCM resulted in a significant change in the abundance of representative bacterial species. PCR analysis showed a consistent increase in the abundance of Parabacteroides. distasonis in all three colon sections. Furthermore, analysis of free fatty acids revealed a significant increase in their levels in the ascending, transverse, and descending colons, except for caproic acid, which was significantly reduced to a non-detectable level. The identification of significant extracellular polar metabolites, such as glutathione and serotonin, enabled us to distinguish between the metabolomes before and after 2′-FL intervention. Moreover, correlation analysis revealed a significant association between the altered microbes and microbial metabolites. ConclusionsIn summary, our study demonstrated the impact of 2′-FL intervention on the defined composition of infant gut microbiota and their metabolic pathways in an in vitro setting. Our findings provide valuable insights for future follow-up investigations into the role of 2′-FL in regulating the growth and development of infant gut microbiota in vivo.

Maternal vaginal fluids play a major role in the colonization of the neonatal intestinal microbiota.

Caesarean section (CS) is associated with newborns' health risks due to the blocking of microbiome transfer. The gut microbiota of CS-born babies was different from those born vaginally, which may be attributed to reduced exposure to maternal vaginal microbes during labour. To understand the microbial transfer and reduce CS disadvantages, the effect of vaginal microbiota exposure on infant gut microbiota composition was evaluated using 16s rDNA sequencing-based techniques. Pregnant women were recruited in the Women and Children's Hospital, School of Medicine, Xiamen University from June 1st to August 15th, 2017. Maternal faeces (n = 26), maternal vaginal fluids (n = 26), and neonatal transitional stools (n = 26) were collected, while the participants underwent natural delivery (ND) (n = 6), CS (n = 4) and CS with the intervention of vaginal seedings (I) (n = 16). 26 mothers with the median age 26.50 (25.00-27.25) years showed no substantial clinical differences. The newborns' gut microbiota altered among ND, CS and I, and clustered into two groups (PERMANOVA P = 0.001). Microbial composition of ND babies shared more features with maternal vaginal samples (PERMANOVA P = 0.065), while the microbiota structure of ND babies was obviously different from that of sample of maternal faeces. The genus Bacteroides in CS-born babies with intervention approached to vaginal-born neonates, compared with CS-born neonates without intervention. Neonatal gut microbiota was dependent on the delivery mode. And the gut microbiota CS newborns with vaginal seeding shared more features with those of ND babies, which hinted the aberrant gut microbiota composition initiated by CS might be partly mitigated by maternal vaginal microbiota exposure.

Early development of infant gut microbiota in relation to breastfeeding and human milk oligosaccharides.

Infant gut microbiota composition is influenced by various factors early in life. Here, we investigate associations between infant gut microbiome development, infant age, breastfeeding duration, and human milk oligosaccharides (HMO) composition in breastmilk. A total of 94 mother-infant pairs were recruited as part of the Cambridge Baby Growth and Breastfeeding Study (CBGS-BF) (Cambridge, UK). Infant stool samples (n = 337) were collected at 2 week, 6 week, 3 month, and 6 month of age. The 16S rRNA V3-V4 rRNA region was sequenced using MiSeq Illumina to determine microbiota composition and diversity. Mother's hindmilk samples were collected at birth, 2 week, 6 week, 3 month, and 6 month postpartum. Concentrations of five neutral [2'FL, 3'FL, lacto-N-fucopentaose 1 (LNFP1), LNnT, LNT] and two acidic (3'SL, and 6'SL) HMOs were measured in all milk samples using High-Performance Anion-Exchange Chromatography with Pulsed Amperometric Detection (HPAEC-PAD). We explored the associations between infant gut microbiome parameters and age, duration of exclusive breastfeeding (EBF), and levels of individual HMOs. Bifidobacterium was the most abundant genus in infant stool at all-time points, irrespective of breastfeeding duration, with an overall mean relative abundance of 70%. The relative abundance of B. bifidum in stool from infants who were breastfed for longer than 6 months was significantly higher compared to the infant breastfed up to 3 months (p = 0.0285). Alpha-diversity (both Shannon and ASV-level Richness) of infant gut microbiota showed a biphasic change with infant age, decreasing from 2 weeks until 3 months and then increasing until 6 months of age. Bifidobacterium relative abundance was associated with higher concentrations of 2'FL and LNFP1 in breastmilk across all time-points (p = 0.049 and 0.017, respectively), with trends toward a higher abundance of B. longum species. No significant association with Bifidobacterium was found for breastmilk LNnT, 3'SL, and 6'SL levels. Our study is in line with previous data demonstrating that EBF duration in the first months of life impacts infant gut microbiota composition. The observed links between specific HMOs in breastmilk and bacteria in infant stool provide evidence of how mother's milk affects infant microbiome development.

Therapeutic Potential of Gut Microbiota and Its Metabolite Short-Chain Fatty Acids in Neonatal Necrotizing Enterocolitis

Short chain fatty acids (SCFAs), the principle end-products produced by the anaerobic gut microbial fermentation of complex carbohydrates (CHO) in the colon perform beneficial roles in metabolic health. Butyrate, acetate and propionate are the main SCFA metabolites, which maintain gut homeostasis and host immune responses, enhance gut barrier integrity and reduce gut inflammation via a range of epigenetic modifications in DNA/histone methylation underlying these effects. The infant gut microbiota composition is characterized by higher abundances of SCFA-producing bacteria. A large number of in vitro/vivo studies have demonstrated the therapeutic implications of SCFA-producing bacteria in infant inflammatory diseases, such as obesity and asthma, but the application of gut microbiota and its metabolite SCFAs to necrotizing enterocolitis (NEC), an acute inflammatory necrosis of the distal small intestine/colon affecting premature newborns, is scarce. Indeed, the beneficial health effects attributed to SCFAs and SCFA-producing bacteria in neonatal NEC are still to be understood. Thus, this literature review aims to summarize the available evidence on the therapeutic potential of gut microbiota and its metabolite SCFAs in neonatal NEC using the PubMed/MEDLINE database.

A pilot study to disentangle the infant gut microbiota composition and identification of bacteria correlates with high fat mass.

Background: At birth, the human intestine is colonized by a complex community of microorganisms known as gut microbiota. These complex microbial communities that inhabit the gut microbiota are thought to play a key role in maintaining host physiological homeostasis. For this reason, correct colonization of the gastrointestinal tract in the early stages of life could be fundamental for human health. Furthermore, alterations of the infant microbiota are correlated with the development of human inflammatory diseases and disorders. In this context, the possible relationships between intestinal microbiota and body composition during infancy are of great interest. Methods: In this study, we have performed a pilot study based on 16S rRNA gene profiling and metagenomic approaches on repeatedly measured data on time involving a cohort of 41 Italian newborns, which is aimed to investigate the possible correlation between body fat mass percentage (FM%) and the infant gut microbiota composition. Results and conclusion: The taxonomical analysis of the stool microbiota of each infant included in the cohort allowed the identification of a specific correlation between intestinal bacteria, such as Bifidobacterium and Veillonella, and the increase in FM%. Moreover, the analysis of the infant microbiome's metabolic capabilities suggested that the intestinal microbiome functionally impacts the human host and its possible influence on host physiology.

Antibiotic treatments to mothers during the perinatal period leaving hidden trouble on infants

Antibiotic application during the perinatal period is unavoidable in the clinic, but the potential effects on mothers and infants remain unknown. Herein, 25 breast milk samples from mothers who received cefuroxime (CXM) or CXM + cefoxitin (CFX) treatments and fecal samples from their infants were collected to investigate the undesirable effects of antibiotics on the microbiota of mothers and neonates. Furthermore, five fecal samples of infants, whose mothers had antibiotic treatments, were collected at a 6-month postpartum follow-up visit to evaluate the long-term effects on infants’ gut microbiota. Moreover, the relative abundance of antibiotic resistance genes (ARGs) in fecal samples was compared to investigate the transfer of ARGs in the infant gut microbiota. The results indicated that the antibiotic treatments had no influence on the microbiota of breast milk. The dominant bacterial phyla in the fecal samples changed to Firmicutes and Proteobacteria after antibiotic treatments, while the bacterial community showed a recuperative trend at the follow-up visits. In addition, the abundance of ARGs in the infant gut microbiota demonstrated a declining trend in the CXM- and CXM + CFX-treated groups, while ARG abundance presented a significant increasing trend after a 6-month recovery period.Conclusion: Antibiotic treatments for mothers during the perinatal period disturb the gut microbiota in neonates. The infants’ gut microbiota would partly return to their initial state after rehabilitation, but the transfer of ARGs would leave the hidden trouble of antibiotic resistance. Overall, the data presented here can help to guide the scientific use of antibiotics during the perinatal period and provide potential approaches to mitigate the negative consequences.What is Known:• Antibiotic application during the perinatal period is unavoidable in the clinic.• Misuse of antibiotics can cause various unintended consequences, especially for antibiotic resistance.What is New:• Antibiotic treatments had no influence on the microbiota of breast milk but greatly disturbed the gut microbiota composition in infants.• The gut microbiota in infants would partly return to its initial state after rehabilitation but the transfer of ARGs would leave the hidden trouble of antibiotic resistance.

Early-life gut microbiota and attention deficit hyperactivity disorder in preadolescents.

Gut microbiota maturation coincides with nervous system development. Cross-sectional data suggest gut microbiota of individuals with and without attention deficit hyperactivity disorder (ADHD) differs. We hypothesized that infant gut microbiota composition is associated with later ADHD development in our on-going birth cohort study, WHEALS. Gut microbiota was profiled using 16S ribosomal RNA and the internal transcribed spacer region 2 (ITS2) sequencing in stool samples from 1 month and 6 months of age. ADHD was defined by parent-reported or medical record doctor diagnosis at age 10. A total of 314 children had gut microbiota and ADHD data; 59 (18.8%) had ADHD. After covariate adjustment, bacterial phylogenetic diversity (p = 0.017) and bacterial composition (unweighted UniFrac p = 0.006, R2 = 0.9%) at age 6 months were associated with development of ADHD. At 1 month of age, 18 bacterial and 3 fungal OTUs were associated with ADHD development. At 6 months of age, 51 bacterial OTUs were associated with ADHD; 14 of the order Lactobacillales. Three fungal OTUs at 6 months of age were associated with ADHD development. Infant gut microbiota is associated with ADHD development in pre-adolescents. Further studies replicating these findings and evaluating potential mechanisms of the association are needed. Cross-sectional studies suggest that the gut microbiota of individuals with and without ADHD differs. We found evidence that the bacterial gut microbiota of infants at 1 month and 6 months of age is associated with ADHD at age 10 years. We also found novel evidence that the fungal gut microbiota in infancy (ages 1 month and 6 months) is associated with ADHD at age 10 years. This study addresses a gap in the literature in providing longitudinal evidence for an association of the infant gut microbiota with later ADHD development.

Free threonine in human breast milk is related to infant intestinal microbiota composition

BackgroundAccumulating evidence indicates that free amino acids (FAA) might be bioactive compounds with potential immunomodulatory capabilities. However, the FAA composition in human milk is still poorly characterized with respect to its correlation to maternal serum levels and its physiological significance for the infant. Studies addressing the relation of human milk FAA to the infants' intestinal microbiota are still missing.MethodsAs part of a pilot study, maternal serum and breast milk FAA concentrations as well as infant intestinal microbiota (16S rRNA) were determined 2 months after birth. The study cohort consisted of 41 healthy mothers and their term delivered, healthy infants with normal birthweight. The relationship between maternal serum and milk FAA was determined by correlation analyses. Associations between (highly correlated) milk FAA and infant intestinal beta diversity were tested using PERMANOVA, LefSe and multivariate regression models adjusted for common confounders.ResultsSeven breast milk FAA correlated significantly with serum concentrations. One of these, threonine showed a negative association with abundance of members of the class Gammaproteobacteria (R2adj = 17.1%, p = 0.006; β= − 0.441). In addition, on the level of families and genera, threonine explained 23.2% of variation of the relative abundance of Enterobacteriaceae (R2adj; p = 0.001; β = − 0.504) and 11.1% of variability in the abundance of Escherichia/Shigella (R2adj, p = 0.025; β = − 0.368), when adjusted for confounders.ConclusionOur study is the first to suggest potential interactions between breast milk FAA and infant gut microbiota composition during early lactation. The results might be indicative of a potential protective role of threonine against members of the Enterobacteriaceae family in breast-fed infants. Still, results are based on correlation analyses and larger cohorts are needed to support the findings and elucidate possible underlying mechanisms to assess the complex interplay between breast milk FAA and infant intestinal microbiota in detail.

Investigating the infant gut microbiota in developing countries: worldwide metagenomic meta-analysis involving infants living in sub-urban areas of Côte d'Ivoire.

In recent decades, infants' gut microbiota has aroused constant scientific interest, primarily due to early‐ and long‐term repercussions on the host health. In this context, nutritional challenges such as those found in less developed countries can influence infants' gut microbiota development, thus generating potentially critical health outcomes. However, comprehensive investigations regarding species‐level differences in the infant gut microbiota's composition between urbanized and rural countries are still missing. In this study, 16S rRNA and Shallow Shotgun metagenomics sequencing were exploited to dissect the microbial community's species‐level composition of 11 faecal samples collected from infants living in a semi‐urban area of Sub‐Saharan Africa, i.e. Côte d'Ivoire. Moreover, the generated data were coupled with those retrieved from public available metagenomic repositories, including two rural communities and 13 urban communities of industrialized countries. The meta‐analysis led to the identification of Infant Species Community States Type (ISCSTs) and microbial species covariances, which were exploited to reveal key signatures of infants living in rural and semi‐urban societies. Remarkably, analysis of rural and semi‐urban datasets revealed shifts from ISCSTs prevalent in urbanized populations with putative health implications. Thus, indicating the need for population‐wide investigations aimed to define the factors determining such potentially harmful gut microbial communities' signatures.

Abstract MP43: Breast Milk-dependent Associations Of Infant Gut Microbiota With Childhood BMI Z Score

Introduction: The prevalence of overweight and obesity in children ages 2-5 years continues to rise in the US. Experimental germ-free animal models indicate gut microbiota can cause excess weight gain. Observational human studies, mostly cross-sectional, also suggest gut microbiota is associated with obesity, but these studies have largely been conducted in older children and adults. Infants have a unique gut microbiota composition and function, under strong influence by human milk. Bifidobacteria, in particular, is hypothesized to be beneficial in the presence of human milk oligosaccharides. To our knowledge, no longitudinal studies have examined the association of the infant gut microbiota with childhood BMI, taking into account intake of human milk. Hypothesis: We hypothesized that infant gut microbiota composition, in particular relative abundance of Bifidobacteria, in the first year is prospectively associated with differences in child BMI from ages 2-5 years and associations are modified by duration of human milk feeding. Methods: We examined longitudinal data from mother-child dyads in the New Hampshire Birth Cohort, which began enrolling pregnant women from New Hampshire in 2009. We measured the infant gut microbiota using 16S rRNA sequencing at 6 weeks and 12 months of age. We estimated alpha diversity using the Shannon diversity index. Child BMI z scores (BMI-z) at 2-5 years of age were calculated using sex- and age-specific WHO growth charts. We used unadjusted and multivariable adjusted linear mixed models. We adjusted for pre-pregnancy BMI, birth weight, delivery mode, and infant BMI-z at 12 months (in 12-month microbiota models). We considered effect measure modification by breastfeeding duration. Results: Our analytic sample comprised 148 and 146 infants with microbiota data at 6 weeks and 12 months, respectively, and at least 1 BMI-z from ages 2-5 years. Shannon diversity at 6 weeks and 12 months of age, and top genera at 6 weeks were not significantly associated with child BMI-z. Abundance of 12-month Bifidobacterium was associated with lower BMI-z (-0.12; 95% CI (-0.25, 0.006)) and interacted with breastfeeding duration (p interaction <0.01); among infants consuming breast milk ≥6 months Bifidobacterium was associated with a 0.22 (95% CI: 0.06, 0.37) lower child BMI-z. Lower abundance of 12-month Prevotella , a bacteria linked to obesity in adults, was suggestively associated with lower child BMI-z and this association was also modified by breastfeeding duration (p interaction=0.01), such that it was only significant among infants breastfed < 6 months (0.34; 95% CI: 0.09, 0.60). Both interactions were consistent when breastfeeding duration was dichotomized at 12 months. Conclusion: Higher percent Bifidobacterium and lower Prevotella at 12 months was prospectively associated with lower childhood BMI-z, and both associations were modified by breastfeeding duration.

Association Between the Mode of Delivery and Infant Gut Microbiota Composition Up to 6 Months of Age: A Systematic Literature Review Considering the Role of Breastfeeding.

Cesarean section (CS), breastfeeding, and geographic location can influence the infant microbiota. In this systematic review, evidence of the association between mode of delivery and infant gut microbiota up to 6 months of age was evaluated, as was the role of breastfeeding in this association, according to PRISMA guidelines. The Pubmed, Web of Science, Scopus, Embase, Medical Database, and Open Grey databases were searched. A total of 31 observational studies with ≥2 infant stool collections up to the sixth month of age and a comparison of gut microbiota between CS and vaginal delivery (VD) were included. Infants born by CS had a lower abundance of Bifidobacterium and Bacteroides spp. at almost all points up to age 6 months. Populations of Lactobacillus, Bifidobacterium longum, Bifidobacterium catenulatum, and Escherichia coli were reduced in infants delivered by CS. Infants born by CS and exclusively breastfed had greater similarity with the microbiota of infants born by VD. Species of Bifidobacterium and Bacteroides are potentially reduced in infants born by CS. Geographic location influenced bacterial colonization. PROSPERO registration no. 42017071285.

Early Life Microbiota Colonization at Six Months of Age: A Transitional Time Point.

BackgroundEarly life gut microbiota is involved in several biological processes, particularly metabolism, immunity, and cognitive neurodevelopment. Perturbation in the infant’s gut microbiota increases the risk for diseases in early and later life, highlighting the importance of understanding the connections between perinatal factors with early life microbial composition. The present research paper is aimed at exploring the prenatal and postnatal factors influencing the infant gut microbiota composition at six months of age.MethodsGut microbiota of infants enrolled in the longitudinal, prospective, observational study “A.MA.MI” (Alimentazione MAmma e bambino nei primi MIlle giorni) was analyzed. We collected and analyzed 61 fecal samples at baseline (meconium, T0); at six months of age (T2), we collected and analyzed 53 fecal samples. Samples were grouped based on maternal and gestational weight factors, type of delivery, type of feeding, time of weaning, and presence/absence of older siblings. Alpha and beta diversities were evaluated to describe microbiota composition. Multivariate analyses were performed to understand the impact of the aforementioned factors on the infant’s microbiota composition at six months of age.ResultsDifferent clustering hypotheses have been tested to evaluate the impact of known metadata factors on the infant microbiota. Neither maternal body mass index nor gestational weight gain was able to determine significant differences in infant microbiota composition six months of age. Concerning the type of feeding, we observed a low alpha diversity in exclusive breastfed infants; conversely, non-exclusively breastfed infants reported an overgrowth of Ruminococcaceae and Flavonifractor. Furthermore, we did not find any statistically significant difference resulting from an early introduction of solid foods (before 4 months of age). Lastly, our sample showed a higher abundance of clostridial patterns in firstborn babies when compared to infants with older siblings in the family.ConclusionOur findings showed that, at this stage of life, there is not a single factor able to affect in a distinct way the infants’ gut microbiota development. Rather, there seems to be a complex multifactorial interaction between maternal and neonatal factors determining a unique microbial niche in the gastrointestinal tract.

The Effects of Human Milk Oligosaccharide Supplementation During Critical Periods of Development on the Mesolimbic Dopamine System

Human milk oligosaccharides (HMO)s are a key component in human milk and represent an important dietary modulator of infant gut microbiota composition and associated gut-brain axis development and homeostasis. The brain reward system, specifically the mesolimbic dopamine (DA) projections from the ventral tegmental area (VTA) to nucleus accumbens (NAc) is involved in the motivation and preference for food. The objective of the present study was to determine if HMO fortified diets given during the critical period of reward system development (p21) could affect the structure of the reward system. At weaning (p21), Sprague-Dawley rats were randomized to one of four fortified diet groups: Control, 3′sialyllactose (3′FL), 2′-fucosyllactose (2′FL), or a combination of 3′SL and 2′FL (3′SL + 2′FL). Messenger RNA (mRNA) expression was quantified for DA and appetite associated markers in the VTA and NAc and western blots measured the immediate early gene FosB and its isoform ΔFosB. Females fed the 3′SL + 2′FL fortified diet displayed a decrease in DAT expression in the VTA and an increase in leptin expression in the NAc. Females displayed an overall lower expression of NAc D2, VTA ghrelinR, and VTA leptin. In males, VTA DAT and FosB were negatively correlated with body weight and systemic leptin. Sex differences in the expression of DA markers underscore the need to investigate this phenomenon and understand the functional significance in preventing or treating obesity. This study highlights sex differences in response to HMO supplementation and the need for further investigations into the functional significance of nutritional interventions during DA system development.