Composition and Variation of Macronutrients, Immune Proteins, and Human Milk Oligosaccharides in Human Milk From Nonprofit and Commercial Milk Banks

BACKGROUND

When human milk is unavailable, banked milk is recommended for feeding premature infants. Milk banks use processes to eliminate pathogens; however, variability among methods exists. Research aim: The aim of this study was to compare the macronutrient (protein, carbohydrate, fat, energy), immune-protective protein, and human milk oligosaccharide (HMO) content of human milk from three independent milk banks that use pasteurization (Holder vs. vat techniques) or retort sterilization.

METHODS

Randomly acquired human milk samples from three different milk banks ( n = 3 from each bank) were analyzed for macronutrient concentrations using a Fourier transform mid-infrared spectroscopy human milk analyzer. The concentrations of IgA, IgM, IgG, lactoferrin, lysozyme, α-lactalbumin, α antitrypsin, casein, and HMO were analyzed by mass spectrometry.

RESULTS

The concentrations of protein and fat were significantly ( p < .05) less in the retort sterilized compared with the Holder and vat pasteurized samples, respectively. The concentrations of all immune-modulating proteins were significantly ( p < .05) less in the retort sterilized samples compared with vat and/or Holder pasteurized samples. The total HMO concentration and HMOs containing fucose, sialic acid, and nonfucosylated neutral sugars were significantly ( p < .05) less in retort sterilized compared with Holder pasteurized samples.

CONCLUSION

Random milk samples that had undergone retort sterilization had significantly less immune-protective proteins and total and specific HMOs compared with samples that had undergone Holder and vat pasteurization. These data suggest that further analysis of the effect of retort sterilization on human milk components is needed prior to widespread adoption of this process.

Survival of Immunoglobulins from Human Milk to Preterm Infant Gastric Samples at 1, 2, and 3 h Postprandial

BACKGROUND

Human milk immunoglobulins (Ig) are an important support for the naïve infant immune system; yet the extent to which these proteins survive within the infant digestive tract, particularly for preterm infants, is poorly studied.

OBJECTIVES

Our objective was to evaluate the survival of human milk Igs in the preterm stomach across postprandial time.

METHODS

Human milk and infant gastric samples were collected from 11 preterm (23-32 weeks gestational age) mother-infant pairs within 7-98 days postnatal age. Preterm gastric samples were collected 1, 2, and 3 h after the beginning of the feeding. Samples were analyzed for concentration of total IgA (secretory IgA [SIgA]/IgA), total secretory component (SC/SIgA/SIgM), total IgM (SIgM/IgM), and IgG via enzyme-linked immunosorbent assay. Ig-chain fragment peptides were determined using peptidomic analysis. One-way analysis of variance with repeated measures followed by Tukey's multiple comparison tests was applied.

RESULTS

Concentrations of total IgA were lower in the gastric contents at 3 h postprandial compared with human milk and gastric contents at 1 and 2 h. Human milk SC/SIgA/SIgM, IgG, and total IgM concentrations remained stable in the preterm stomach across postprandial time. Peptide counts from the Ig alpha-chain and the Ig gamma-chain increased in gastric contents from 1 to 2 h postprandial. Peptide counts from the human milk Ig-chain, Ig-chain, and SC were stable across postprandial time. These peptides from Ig-chains were not present in human milk but were released in the stomach due to their partial degradation.

CONCLUSIONS

Human milk total SC (SIgA/SC/SIgM), total IgM, and IgG survived mostly intact through the preterm infant stomach, while total IgA was -partially digested.

Predictive Value of the Aspartate Aminotransferase to Platelet Ratio Index for Parenteral Nutrition-Associated Cholestasis in Premature Infants With Intestinal Perforation

BACKGROUND

Parenteral nutrition-associated cholestasis (PNAC) is a major cause of morbidity and mortality in premature infants. Early predictors of PNAC would have clinical value. We sought to evaluate risk factors and liver function testing as predictors of PNAC in premature infants with intestinal perforation.

METHODS

Medical records of infants with a gestational age <34 weeks, birth weight <2000 g, and intestinal perforation due to either necrotizing enterocolitis or spontaneous intestinal perforation were reviewed. We analyzed clinical data and the maximum values of the aspartate aminotransferase (AST) to platelet ratio index (APRI), alanine aminotransferase (ALT), AST to ALT ratio, and total bilirubin (TB).

RESULTS

Sixty infants were identified, 17 infants with PNAC and 43 infants without PNAC. Sepsis, time to initiation of enteral feeds after perforation, and duration of PN were associated with PNAC. Within 2 weeks following intestinal perforation, APRI, ALT, and TB each differed significantly between infants who later developed PNAC and those that did not. The best APRI cut-point was 0.4775 within 2 weeks after perforation (area under the receiver operating characteristic curve, 0.90; positive predictive value, 85%; and negative predictive value, 87%); the cut-point for ALT was 13.5 (0.90, 85%, 84%), and the cut-point for TB was 3.55 (0.82, 69%, 83%), respectively, at 2 weeks after perforation. AST to ALT ratio did not differ between groups.

CONCLUSIONS

APRI and ALT had reasonable predictive value for PNAC in premature infants with intestinal perforation, with the APRI the best predictor within 2 weeks after perforation.

Prenatal and postnatal administration of prebiotics and probiotics

Colonization of the neonatal gut by beneficial bacteria is important for the establishment and maintenance of the mucosal barrier, thus protecting the neonate from enteric pathogens and local and systemic inflammation. The neonatal microbiome is influenced by infant diet, environment, and the maternal microbiome. Dysbiosis in pregnancy increases the risk of pre-eclampsia, diabetes, infection, preterm labor, and later childhood atopy. Dysbiosis of the neonatal gut plays an important role in colic in the term infant, in the disease processes which plague preterm infants, including necrotizing enterocolitis and sepsis, and in the long-term outcomes of neonates. Administration of enteral prebiotics, probiotics, and synbiotics during pregnancy, lactation, and postnatal life appears to be a safe and feasible method to alter the maternal and neonatal microbiome, thus improving pregnancy and neonatal outcomes.

The Microbiota of the Extremely Preterm Infant

Colonization of the extremely preterm infant's gastrointestinal tract and skin begins in utero and is influenced by a variety of factors, the most important including gestational age and environmental exposures. The composition of the intestinal and skin microbiota influences the developing innate and adaptive immune responses with short-term and long-term consequences including altered risks for developing necrotizing enterocolitis, sepsis, and a wide variety of microbe-related diseases of children and adults. Alteration of the composition of the microbiota to decrease disease risk is particularly appealing for this ultra-high-risk cohort that is brand new from an evolutionary standpoint.

Analysis of Milk from Mothers Who Delivered Prematurely Reveals Few Changes in Proteases and Protease Inhibitors across Gestational Age at Birth and Infant Postnatal Age

Background: Peptidomics research has demonstrated that protease activity is higher in breast milk from preterm-delivering mothers than from term-delivering mothers. However, to our knowledge, the effect of the degree of prematurity and postnatal age on proteases and protease inhibitors in human milk remains unknown.Objective: We aimed to determine the change of proteases and protease inhibitors in milk from mothers who delivered prematurely across gestational age (GA) and postnatal age.Methods: Milk samples were collected from 18 mothers aged 26-40 y who delivered preterm infants and who lacked mastitis. For analysis, samples were separated into 2 groups: 9 from early GA (EGA) (24-26 wk GA)-delivering mothers and 9 from late GA (LGA) (27-32 wk GA)-delivering mothers. Within the 9 samples in each group, the collection time ranged from postnatal days 2 to 47. The activity and predicted activity of proteases in preterm milk were determined with the use of fluorometric and spectrophotometric assays and peptidomics, respectively. Protease and protease inhibitor concentrations were determined with the use of ELISA. Linear mixed models were applied to compare enzymes across GA and postnatal age.Results: Carboxypeptidase B2, kallikrein, plasmin, elastase, thrombin, and cytosol aminopeptidase were present and active in the milk of preterm-delivering mothers. Most milk protease and antiprotease concentrations did not change with GA or postnatal age. However, the concentration and activity of kallikrein, the most abundant and active protease in preterm milk, increased by 25.4 ng · mL-1 · d-1 and 0.454 μg · mL-1 · d-1 postnatally, respectively, in EGA milk samples while remaining stable in LGA milk samples.Conclusions: This research demonstrates that proteases are active in human milk and begin to degrade milk protein within the mammary gland before consumption by infants. Proteases and protease inhibitors in milk from mothers of premature infants mostly did not vary substantially across GA and postnatal age.

Safety and tolerability of Bifidobacterium longum subspecies infantis EVC001 supplementation in healthy term breastfed infants: a phase I clinical trial

BACKGROUND

Historically, bifidobacteria were the dominant intestinal bacteria in breastfed infants. Still abundant in infants in developing nations, levels of intestinal bifidobacteria are low among infants in developed nations. Recent studies have described an intimate relationship between human milk and a specific subspecies of Bifidobacterium, B. longum subsp. infantis (B. infantis), yet supplementation of breastfed, healthy, term infants with this organism, has not been reported. The IMPRINT Study, a Phase I clinical trial, was initiated to determine the safety and tolerability of supplementing breastfed infants with B. infantis (EVC001).

METHODS

Eighty mother-infant dyads were enrolled in either lactation support plus B. infantis supplementation (BiLS) or lactation support alone (LS). Starting with Day 7 postnatal, BiLS infants were fed 1.8-2.8 × 1010 CFU B. infantis EVC001 daily in breast milk for 21 days. Mothers collected fecal samples, filled out health questionnaires, and kept daily logs about their infants' feeding and gastrointestinal symptoms from birth until Day 61 postnatal. Safety and tolerability were determined from maternal reports.

RESULTS

There were no differences in the mean gestational age at birth, weight 1 and 2 months postnatal, and breast milk intake between groups. The mean Log10 change in fecal Bifidobacterium from Day 6 to Day 28 was higher (p = 0.0002) for BiLS (6.6 ± 2.8 SD) than for LS infants (3.5 ± 3.5 SD). Daily stool number was higher (p < 0.005) for LS and lower (p < 0.05) for BiLS infants during supplementation than at Baseline. During supplementation, watery stools decreased and soft stools increased by 36% over baseline in BiLS infants (p < 0.05) with no significant changes in stool consistency for the LS infants. None of the safety and tolerability endpoints, including flatulence, bloody stool, body temperature, ratings of gastrointestinal symptoms, use of antibiotics or gas-relieving medications, infant colic, jaundice, number of illnesses, sick doctor visits, or diagnoses of eczema were different for the groups at any point.

CONCLUSIONS

The B. infantis EVC001 supplement was safely consumed and well-tolerated. Stools were fewer and better formed in infants in the BiLS group compared with LS group. Adverse events were those expected in healthy infants and not different between groups.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02457338 . Registered May 27, 2015.

Impact of probiotics on necrotizing enterocolitis

A large number of randomized placebo-controlled clinical trials and cohort studies have demonstrated a decrease in the incidence of necrotizing enterocolitis with administration of probiotic microbes. These studies have prompted many neonatologists to adopt routine prophylactic administration of probiotics while others await more definitive studies and/or probiotic products with demonstrated purity and stable numbers of live organisms. Cross-contamination and inadequate sample size limit the value of further traditional placebo-controlled randomized controlled trials. Key areas for future research include mechanisms of protection, optimum probiotic species or strains (or combinations thereof) and duration of treatment, interactions between diet and the administered probiotic, and the influence of genetic polymorphisms in the mother and infant on probiotic response. Next generation probiotics selected based on bacterial genetics rather than ease of production and large cluster-randomized clinical trials hold great promise for NEC prevention.

Intestinal perforation in the premature infant

OBJECTIVE

To compare demographic data, prenatal and postnatal characteristics, laboratory data, and outcomes in a cohort of premature infants with spontaneous ileal perforation (SIP), surgical necrotizing enterocolitis (sNEC) and matched controls.

METHODS

A retrospective case-control study of infants with intestinal perforation with a birth weight (BW) less than 2,000 grams and gestational age (GA) less than 34 weeks and infants without perforation matched for BW (±150 grams) and GA (±1week).

RESULTS

130 premature infants were included, 30 infants with SIP, 35 infants with sNEC and 65 control infants. The median age of onset was 5 days postnatal age in SIP versus 25 days in sNEC (p < 0.001) and the peak onset was at 26 weeks corrected GA for SIP and 30 weeks corrected GA for sNEC. Infants with perforation had significantly higher rates of mortality (p < 0.001) and common morbidities associated with prematurity. Administration of corticosteroids and indomethacin did not differ among groups. SIP was more common among infants born to young mothers (p = 0.04) and less common in infants receiving caffeine (p = 0.02). sNEC was less common among infants receiving early red cell transfusion (p = 0.01). Perforation and sNEC trended towards less common in infants receiving inhaled nitric oxide.

CONCLUSION

SIP and sNEC are distinct clinical entities. Potential protective effects of caffeine, inhaled nitric oxide, and early transfusion should be further studied.

Postnatal growth restriction augments oxygen-induced pulmonary hypertension in a neonatal rat model of bronchopulmonary dysplasia

BACKGROUND

Prematurity and fetal growth restriction are risk factors for pulmonary hypertension (PH) in infants with bronchopulmonary dysplasia (BPD). Neonatal rats develop PH and vascular remodeling when exposed to hyperoxia. We hypothesize that postnatal growth restriction (PNGR) due to under-nutrition increases the severity of PH induced by hyperoxia in neonatal rats.

METHODS

Pups were randomized at birth to litters maintained in room air or 75% oxygen (hyperoxia), together with litters of normal milk intake (10 pups) or PNGR (17 pups). After 14 d, right ventricular hypertrophy (RVH) was assessed by Fulton's index (right ventricular weight/left ventricular plus septal weight) and PH by echocardiography. Lungs were analyzed by immunohistochemistry, morphometrics, western blotting, and metabolomics.

RESULTS

Hyperoxia and PNGR each significantly increased pulmonary arterial pressure, RVH and pulmonary arterial medial wall thickness, and significantly decreased pulmonary vessel number. These changes were significantly augmented in pups exposed to both insults. Hyperoxia and PNGR both significantly decreased expression of proteins involved in lung development and vasodilation.

CONCLUSION

PNGR induces right ventricular and pulmonary vascular remodeling and augments the effects of oxygen in neonatal rats. This may be a powerful tool to investigate the mechanisms that induce PH in low-birth-weight preterm infants with BPD.

Prevention of Necrotizing Enterocolitis Through Manipulation of the Intestinal Microbiota of the Premature Infant

PURPOSE

In spite of four decades of research, necrotizing enterocolitis (NEC) remains the most common gastrointestinal complication in premature infants with high mortality and long-term morbidity. The composition of the intestinal microbiota of the premature infant differs dramatically from that of the healthy term infant and appears to be an important risk factor for NEC.

METHODS

We review the evidence of an association between intestinal dysbiosis and NEC and summarize published English language clinical trials and cohort studies involving attempts to manipulate the intestinal microbiota in premature infants.

FINDINGS

Promising NEC prevention strategies that alter the intestinal microbiota include probiotics, prebiotics, synbiotics, lacteroferrin, and human milk feeding.

IMPLICATIONS

Shaping the intestinal microbiota of the premature infant through human milk feeding and dietary supplements decreases the risk of NEC. Further studies to identify the ideal microbial composition and the most effective combination of supplements are indicated.

Probiotics and Innate and Adaptive Immune Responses in Premature Infants

Premature infants are at increased risk for morbidity and mortality due to necrotizing enterocolitis (NEC) and sepsis. Probiotics decrease the risk of NEC and death in premature infants; however, mechanisms of action are unclear. A wide variety of probiotic species have been evaluated for potential beneficial properties in vitro, in animal models, and in clinical trials of premature infants. Although there is variation by species and even strain, common mechanisms of protection include attenuation of intestinal inflammation, apoptosis, dysmotility, permeability, supplanting other gut microbes through production of bacteriocins, and more effective use of available nutrients. Here, we review the most promising probiotics and what is known about their impact on the innate and adaptive immune response.

Human milk oligosaccharides in premature infants: absorption, excretion, and influence on the intestinal microbiota

BACKGROUND

Human milk oligosaccharides (HMOs) shape the intestinal microbiota in term infants. In premature infants, alterations in the intestinal microbiota (dysbiosis) are associated with risk of necrotizing enterocolitis (NEC) and sepsis, and the influence of HMOs on the microbiota is unclear.

METHODS

Milk, urine, and stool specimens from 14 mother-premature infant dyads were investigated by mass spectrometry for HMO composition. The stools were analyzed by next-generation sequencing to complement a previous analysis.

RESULTS

Percentages of fucosylated and sialylated HMOs were highly variable between individuals but similar in urine, feces, and milk within dyads. Differences in urine and fecal HMO composition suggest variability in absorption. Secretor status of the mother correlated with the urine and fecal content of specific HMO structures. Trends toward higher levels of Proteobacteria and lower levels of Firmicutes were noted in premature infants of nonsecretor mothers. Specific HMO structures in the milk, urine, and feces were associated with alterations in fecal Proteobacteria and Firmicutes.

CONCLUSION

HMOs may influence the intestinal microbiota in premature infants. Specific HMOs, for example those associated with secretor mothers, may have a protective effect by decreasing pathogens associated with sepsis and NEC, while other HMOs may increase dysbiosis in this population.

Loss of signal transducer and activator of transcription 1 is associated with prostate cancer recurrence

STAT1 loss has previously been implicated in cell line studies to modify prostate cancer cell growth and survival, however the clinical significance of this has not previously been established. This study investigated if STAT1 loss was associated with patient outcome measures and the phenotypic consequence of STAT1 silencing. STAT1 expression was assessed in two patient cohorts with localised (n = 78) and advanced prostate cancer at initial diagnosis (n = 39) by immunohistochemistry (IHC). Impact of STAT1 silencing on prostate cancer cells lines was assessed using Cell Death detection ELISA, TLDA gene signature apoptosis arrays, WST-1 assay, xCELLigence system, clonogenic assay, and wound healing assay. In the localised patient cohort, low expression of STAT1 was associated with shorter time to disease recurrence (3.8 vs 7.3 years, P = 0.02) and disease specific survival (6.6 vs 9.3 years, P = 0.05). In the advanced patient cohort, low expression was associated with shorter time to disease recurrence (2.0 vs 3.9 years, P = 0.001). When STAT1 was silenced in PC3 cells (AR negative) and LNCaP cells (AR positive) silencing did not influence levels of apoptosis in either cell line and had little effect on cell viability in the LNCaP cells. In contrast, STAT1 silencing in the PC3 cells resulted in a pronounced increase in cell viability (WST-1 assay: mock silenced vs STAT1 silenced, P < 0.001), clonagenicity (clonogenic assay: mock silenced vs STAT1 silenced, P < 0.001), and migration (wound healing: mock silenced vs STAT1 silenced, P < 0.001). In conclusion, loss of STAT1 may promote prostate cancer recurrence in AR negative patients via increasing cell viability. © 2015 Wiley Periodicals, Inc.

Infant Maturity at Birth Reveals Minor Differences in the Maternal Milk Metabolome in the First Month of Lactation

BACKGROUND

Human milk is the gold standard of nutrition for infants, providing both protective and essential nutrients. Although much is known about milk from mothers giving birth to term infants, less is known about milk from mothers giving birth to premature infants. In addition, little is known about the composition and diversity of small molecules in these milks and how they change over the first month of lactation.

OBJECTIVE

The objective was to understand how milk metabolites vary over the first month of lactation in mothers giving birth to term and preterm infants.

METHODS

(1)H nuclear magnetic resonance (NMR) metabolomics was used to characterize metabolites that were present in micromolar to molar concentrations in colostrum (day 0-5 postpartum), transition milk (day 14), and mature milk (day 28) from mothers who delivered term (n = 15) and preterm (n = 13) infants. Principal components analysis, linear mixed-effects models (LMMs), and linear models (LMs) were used to explore the relation between infant maturity and the postpartum day of collection of milk samples.

RESULTS

By using a standard NMR metabolite library, 69 metabolites were identified in the milks, including 15 sugars, 23 amino acids and derivatives, 11 energy-related metabolites, 10 fatty acid-associated metabolites, 3 nucleotides and derivatives, 2 vitamins, and 5 bacteria-associated metabolites. Many metabolite concentrations followed a similar progression over time in both term and preterm milks, with more biological variation in metabolite concentrations in preterm milk. However, although lacto-N-neotetraose (LMM, P = 4.0 × 10(-5)) and lysine (LM, P = 1.5 × 10(-4)) significantly decreased in concentration in term milk over time, they did not significantly change in preterm milk.

CONCLUSION

Overall, the metabolic profile of human milk is dynamic throughout the first month of lactation, with more variability in preterm than in term milk and subtle differences in some metabolite concentrations. This trial was registered at clinicaltrials.gov as NCT01841268.

Endogenous human milk peptide release is greater after preterm birth than term birth

BACKGROUND

Hundreds of naturally occurring milk peptides are present in term human milk. Preterm milk is produced before complete maturation of the mammary gland, which could change milk synthesis and secretion processes within the mammary gland, leading to differences in protein expression and enzymatic activity, thereby resulting in an altered peptide profile.

OBJECTIVE

This study examined differences in peptides present between milk from women delivering at term and women delivering prematurely.

METHODS

Nano-LC tandem mass spectrometry was employed to identify naturally occurring peptides and compare their abundances between term and preterm human milk samples at multiple time points over lactation. Term milk samples were collected from 8 mothers and preterm milk was collected from 14 mothers. The 28 preterm and 32 term human milk samples were divided into 4 groups based on day of collection (<14, 14-28, 29-41, and 42-58 d).

RESULTS

Preterm milk peptide counts, ion abundance, and concentration were significantly higher in preterm milk than term milk. Bioinformatic analysis of the cleavage sites for peptides identified suggested that plasmin was more active in preterm milk than term milk and that cytosol aminopeptidase and carboxypeptidase B2 likely contribute to extensive milk protein breakdown. Many identified milk peptides in both term and preterm milk overlapped with known functional peptides, including antihypertensive, antimicrobial, and immunomodulatory peptides.

CONCLUSION

The high protein degradation by endogenous proteases in preterm milk might attenuate problems because of the preterm infant's immature digestive system. This trial was registered at clinicaltrials.gov as NCT01817127.

Following the digestion of milk proteins from mother to baby

Little is known about the digestive process in infants. In particular, the chronological activity of enzymes across the course of digestion in the infant remains largely unknown. To create a temporal picture of how milk proteins are digested, enzyme activity was compared between intact human milk samples from three mothers and the gastric samples from each of their 4-12 day postpartum infants, 2 h after breast milk ingestion. The activities of 7 distinct enzymes are predicted in the infant stomach based on their observed cleavage pattern in peptidomics data. We found that the same patterns of cleavage were evident in both intact human milk and gastric milk samples, demonstrating that the enzyme activities that begin in milk persist in the infant stomach. However, the extent of enzyme activity is found to vary greatly between the intact milk and gastric samples. Overall, we observe that milk-specific proteins are cleaved at higher levels in the stomach compared to human milk. Notably, the enzymes we predict here only explain 78% of the cleavages uniquely observed in the gastric samples, highlighting that further investigation of the specific enzyme activities associated with digestion in infants is warranted.

The impact of the milk glycobiome on the neonate gut microbiota

Human milk is a complete source of nourishment for the infant. Exclusive breastfeeding not only sustains the infant's development but also guides the proliferation of a protective intestinal microbiota. Among the many components of milk that modulate the infant gut microbiota, the milk glycans, which comprise free oligosaccharides, glycoproteins, and glycolipids, are increasingly recognized as drivers of microbiota development and overall gut health. These glycans may display pleiotropic functions, conferring protection against infectious diseases and also acting as prebiotics, selecting for the growth of beneficial intestinal bacteria. The prebiotic effect of milk glycans has direct application to prevention of diseases such as necrotizing enterocolitis, a common and devastating disease of preterm infants. In this article, we review the impact of the human (and bovine) milk glycome on gut health through establishment of a milk-oriented microbiota in the neonate.

Human milk glycomics and gut microbial genomics in infant feces show a correlation between human milk oligosaccharides and gut microbiota: a proof-of-concept study

Human milk oligosaccharides (HMOs) play a key role in shaping and maintaining a healthy infant gut microbiota. This article demonstrates the potential of combining recent advances in glycomics and genomics to correlate abundances of fecal microbes and fecal HMOs. Serial fecal specimens from two healthy breast-fed infants were analyzed by bacterial DNA sequencing to characterize the microbiota and by mass spectrometry to determine abundances of specific HMOs that passed through the intestinal tract without being consumed by the luminal bacteria. In both infants, the fecal bacterial population shifted from non-HMO-consuming microbes to HMO-consuming bacteria during the first few weeks of life. An initial rise in fecal HMOs corresponded with bacterial populations composed primarily of non-HMO-consuming Enterobacteriaceae and Staphylococcaeae. This was followed by decreases in fecal HMOs as the proportion of HMO-consuming Bacteroidaceae and Bifidobacteriaceae increased. Analysis of HMO structures with isomer differentiation revealed that HMO consumption is highly structure-specific, with unique isomers being consumed and others passing through the gut unaltered. These results represent a proof-of-concept and are consistent with the highly selective, prebiotic effect of HMOs in shaping the gut microbiota in the first weeks of life. The analysis of selective fecal bacterial substrates as a measure of alterations in the gut microbiota may be a potential marker of dysbiosis.

Bifidobacterium longum subsp. infantis in experimental necrotizing enterocolitis: alterations in inflammation, innate immune response, and the microbiota

BACKGROUND

Probiotics decrease the risk of necrotizing enterocolitis (NEC). We sought to determine the impact of Bifidobacterium longum subsp. infantis (B. infantis) in the established rat model of NEC.

METHODS

Rat pups delivered 1 d prior to term gestation were assigned to one of three groups: dam fed (DF), formula fed (FF), or fed with formula supplemented with 5 × 10(6) CFU B. infantis per day (FF+Binf). Experimental pups were exposed to hypoxia and cold stress. Ileal tissue was examined for pathology and expression of inflammatory mediators, antimicrobial peptides, and goblet-cell products. Ceca were assessed for bacterial composition by analysis of the 16S rRNA sequence.

RESULTS

Administration of B. infantis significantly reduced the incidence of NEC, decreased expression of Il6, Cxcl1, Tnfa, Il23, and iNOS, and decreased expression of the antimicrobial peptides Reg3b and Reg3g. There was significant microbial heterogeneity both within groups and between experiments. The cecal microbiota was not significantly different between the FF and FF+Binf groups. Bifidobacteria were not detected in the cecum in significant numbers.

CONCLUSION

In the rat model, the inflammation associated with NEC was attenuated by administration of probiotic B. infantis. Dysbiosis was highly variable, precluding determination of the precise role of the microbiota in experimental NEC.