Association of faecal pH with childhood stunting: Results from a cross-sectional study

The Environmental Enteric Dysfunction Biopsy Initiative (EEDBI) Consortium: mucosal investigations of environmental enteric dysfunction

Environmental enteric dysfunction (EED) is an asymptomatic acquired disorder characterized by upper small bowel inflammation, villus blunting, and gut permeability. It is a major contributor to poor growth in childhood as well as other highly consequential outcomes such as delayed neuorcognitive development. After decades of intermittent interest in this entity, we are now seeing a resurgence in the field of EED. However, recent studies have been hampered by a lack of investigation of the target tissue-the upper small bowel. In 2016, the EEDBI (Environmental Enteric Dysfunction Biopsy Initiative) Consortium was established as a common scientific platform across 3 independent EED biopsy cohort studies in Bangladesh, Pakistan, and Zambia. Two centers in the United States recruited comparison groups of children undergoing endoscopy for clinical indications. The EEDBI Consortium goal was to augment the contributions of the individual centers and answer high-level questions amenable to analysis and interpretation across the studies. Here, we describe the Consortium and its cohorts and recruitment procedures across studies. We also offer details applicable to all papers in this supplement, which describe EED mucosal histology, morphometry, immunohistochemistry, and transcriptomics as well as histology relationship to pathogens and biomarkers.

A pilot study of fecal pH and redox as functional markers in the premature infant gut microbiome

The infant gut microbiome is a crucial factor in health and development. In preterm infants, altered gut microbiome composition and function have been linked to serious neonatal complications such as necrotizing enterocolitis and sepsis, which can lead to long-term disability. Although many studies have described links between microbiome composition and disease risk, there is a need for biomarkers to identify infants at risk of these complications in practice. In this pilot study, we obtained stool samples from preterm infant participants longitudinally during the first postnatal months, and measured pH and redox, as well as SCFA content and microbiome composition by 16S rRNA gene amplicon sequencing. These outcomes were compared to clinical data to better understand the role of pH and redox in infant gut microbiome development and overall health, and to assess the potential utility of pH and redox as biomarkers. We found that infants born earlier or exposed to antibiotics exhibited increased fecal pH, and that redox potential increased with postnatal age. These differences may be linked to changes in SCFA content, which was correlated with pH and increased with age. Microbiome composition was also related to birth weight, age, pH, and redox. Our findings suggest that pH and redox may serve as biomarkers of metabolic state in the preterm infant gut.

Alteration of stool pH and its association with biomarkers of gut enteropathy among slum-dwelling women of reproductive age in Bangladesh

BACKGROUND

Recent evidence suggests that measures of maternal gut enteropathy are associated with unfavorable fetal outcomes. It is, therefore, crucial to identify and treat the features of intestinal enteropathy among reproductive-age women living in areas where enteropathy is highly prevalent. However, there is a lack of non-invasive diagnostic tests to determine EED, making it difficult to identify the disease in field settings. In this study, we tested the potential of fecal pH as a biomarker of gut enteropathy and investigated its relationship with fecal biomarkers of intestinal enteropathy in reproductive-age women living in resource-limited environments.

METHODS

Data on socio-demographic information, anthropometry, and biological samples were collected from 78 apparently healthy women aged between 20 and 27 years from November 2018 to December 2019. The association of stool pH with two fecal biomarkers of gut enteropathy (i.e., intestinal alkaline phosphatase [IAP] and fecal lipocalin-2 [LCN-2] was investigated using multiple linear regression models after adjusting for relevant covariates.

RESULTS

In the adjusted models, alkaline stool pH (pH > 7.2) was found to be significantly associated with a decrease in the fecal IAP level by 1.05 unit (95% CI: -1.68, -0.42; p < 0.001) in the log scale, and acidic stool pH (pH < 6) was found to be significantly associated with an increase in the fecal LCN-2 level by 0.89 units (95% CI: 0.12, 1.67; p < 0.025) in the log scale.

CONCLUSIONS

The study findings demonstrated an association of fecal pH with biomarkers of gut enteropathy indicating its applicability as a simple tool for understanding intestinal enteropathy among reproductive-age women living in resource-limited settings.

Translating neonatal microbiome science into commercial innovation: metabolism of human milk oligosaccharides as a basis for probiotic efficacy in breast-fed infants

For over a century, physicians have witnessed a common enrichment of bifidobacteria in the feces of breast-fed infants that was readily associated with infant health status. Recent advances in bacterial genomics, metagenomics, and glycomics have helped explain the nature of this unique enrichment and enabled the tailored use of probiotic supplementation to restore missing bifidobacterial functions in at-risk infants. This review documents a 20-year span of discoveries that set the stage for the current use of human milk oligosaccharide-consuming bifidobacteria to beneficially colonize, modulate, and protect the intestines of at-risk, human milk-fed, neonates. This review also presents a model for probiotic applications wherein bifidobacterial functions, in the form of colonization and HMO-related catabolic activity in situ, represent measurable metabolic outcomes by which probiotic efficacy can be scored toward improving infant health.

A child is not an adult: development of a new in vitro model of the toddler colon

Early life is a critical period where gut ecosystem and functions are being established with significant impact on health. For regulatory, technical, and cost reasons, in vitro gut models can be used as a relevant alternative to in vivo assays. An exhaustive literature review was conducted to adapt the Mucosal Artificial Colon (M-ARCOL) to specific physicochemical (pH, transit time, and nutritional composition of ileal effluents) and microbial parameters from toddlers in the age range of 6 months-3 years, resulting in the Tm-ARCOL. In vitro fermentations were performed to validate this newly developed colonic model compared to in vivo toddler data. Results were also compared to those obtained with the classical adult configuration. Fecal samples from 5 toddlers and 4 adults were used to inoculate bioreactors, and continuous fermentations were performed for 8 days. Gut microbiota structure (lumen and mucus-associated microbiota) and functions (gas and short-chain fatty acids) were monitored. Clearly distinct microbial signatures were obtained between the two in vitro conditions, with lower α-diversity indices and higher abundances of infant-related microbial populations (e.g., Bifidobacteriaceae, Enterobacteriaceae) in toddler versus adult conditions. In accordance with in vivo data, methane was found only in adult bioreactors, while higher percentage of acetate but lower proportions of propionate and butyrate was measured in toddlers compared to adults. This new in vitro model will provide a powerful platform for gut microbiome mechanistic studies in a pediatric context, both in nutritional- (e.g., nutrients, probiotics, prebiotics) and health-related (e.g., drugs, enteric pathogens) studies. KEY POINTS: • Development of a novel in vitro colonic model recapitulating the toddler environment. • Specific toddler versus adult digestive conditions are preserved in vitro. • The new model provides a powerful platform for microbiome mechanistic studies.

The impact of environmental pH on the gut microbiota community structure and short chain fatty acid production

Environmental pH is a critical parameter for maintenance of the gut microbiota. Here, the impact of pH on the gut microbiota luminal and mucosal community structure and short chain fatty acid (SCFA) production was evaluated in vitro, and data compiled to reveal a donor-independent response to an increase or decrease in environmental pH. The results found that raising environmental pH significantly increased luminal community richness and decreased mucosal community evenness. This corresponded with an increased abundance of Ruminococcaceae Ruminococcus, and Erysipelotrichaceae Erysipelatoclostridium, and a decreased abundance of Coriobacteriaceae Collinsella, and Enterobacteriaceae Shigella for both the luminal and mucosal communities. Total SCFA levels were significantly higher, primarily due to an increase in acetic and 2-methylbutanoic acids. Lowering pH decreased luminal community evenness and decreased mucosal community evenness and richness. This corresponded with an increased abundance of Lachnospiraceae Enterocloster, Veillonellaceae Megasphaera, Veillonellaceae Sporomusa, Erysipelotrichaceae Eubacterium, and Alcaligenaceae Sutterella, and decreased abundance of Odoribacteraceae Butyricimonas, Fusobacteriaceae Fusobacterium, Veillonellaceae Phascolarctobacterium, and multiple Enterobacteriaceae species for both the luminal and mucosal communities. Total SCFA levels were significantly lower, with an observed drop in acetic and propionic acids, and increased butyric and valeric acids. Taken together, these results indicate that alterations to environmental pH can modulate the gut microbiota community structure and function, and some changes may occur in a donor-independent manner.

Early probiotic supplementation with B. infantis in breastfed infants leads to persistent colonization at 1 year

BACKGROUND

Recent studies have reported a dysfunctional gut microbiome in breastfed infants. Probiotics have been used in an attempt to restore the gut microbiome; however, colonization has been transient, inconsistent among individuals, or has not positively impacted the host's gut.

METHODS

This is a 2-year follow-up study to a randomized controlled trial wherein 7-day-old infants received 1.8 × 10¹⁰ colony-forming unit Bifidobacterium longum subsp. infantis (B. infantis) EVC001 (EVC) daily for 21 days or breast milk alone (unsupplemented (UNS)). In the follow-up study, mothers (n = 48) collected infant stool at 4, 6, 8, 10, and 12 months postnatal and completed the health-diet questionnaires.

RESULTS

Fecal B. infantis was 2.5-3.5 log units higher at 6-12 months in the EVC group compared with the UNS group (P < 0.01) and this relationship strengthened with the exclusion of infants who consumed infant formula and antibiotics. Infants in the EVC group had significantly higher Bifidobacteriaceae and lower Bacteroidaceae and Lachnospiraceae (P < 0.05). There were no differences in any health conditions between the two groups.

CONCLUSIONS

Probiotic supplementation with B. infantis within the first month postnatal, in combination with breast milk, resulted in stable colonization that persisted until at least 1 year postnatal.

IMPACT

A dysfunctional gut microbiome in breastfed infants is common in resource-rich nations and associated with an increased risk of immune diseases. Probiotics only transiently exist in the gut without persistent colonization or altering the gut microbiome. This is the first study to show that early probiotic supplementation with B. infantis with breast milk results in stable colonization of B. infantis and improvements to the gut microbiome 1 year postnatal. This study addresses a key gap in the literature whereby probiotics can restore the gut microbiome if biologically selected microorganisms are matched with their specific food in an open ecological niche.

Effect of Lactobacillus plantarum DAD-13 and Fructo-oligosaccharides on Short-Chain Fatty Acid Profile and Nutritional Status in Indonesian Stunting Children

BACKGROUND: Chronic gut inflammation is a generalized disturbance of small intestine structure and function is likely to play a large role in the incidence of stunting. It will be disturbances the absorption of nutrients, therefore, it can indirectly reduce on nutritional status. AIM: The aim of this study is to examine the effect of Lactobacillus plantarum DAD-13 and fructooligosaccharide on short-chain fatty acid (SCFA) profile and nutritional status in Indonesian stunting children. METHODS: The study design was used double-blind randomized placebo-controlled trial, 39 stunting children under five received daily oral supplementations of L. plantarum DAD-13 1 × 1010 cfu and fructooligosaccharide 700 mg (symbiotic group) or placebo group for 90 days. SCFA profile was analyzed using gas chromatography and nutritional status was assessed by WAZ, HAZ, and WHZ. RESULTS: The result shows in symbiotic and control group, the mean age was 26 ± 8.34 and 29 ± 5.78, and the mean weight was 8.5 ± 0.94 kg and 9.0 ± 0.82 kg, while the mean height was 78.96 ± 5.4 cm and 80.9 ± 4.55 cm, respectively. Concentrations of acetate, propionate, and butyrate in the symbiotic group after consumption were 17.10 ± 2.97, 7.70 ± 2.05, and 7.47 ± 1.76 while in placebo group 12.44 ± 3.61, 5.20 ± 1.66, and 6.12 ± 1.16, respectively. There was a significant difference in the mean SCFA concentration between the symbiotic and placebo groups (p < 0.05), where the SCFA concentration in the symbiotic group was significantly higher than the placebo group. Nutritional status (WAZ, HAZ, and WHZ) was observed significantly in symbiotic group (p < 0.05), only on WHZ has cutoff point >-2SD after the intervention, while WAZ and HAZ <-2SD. CONCLUSIONS: L. plantarum DAD-13 and fructooligosaccharide 90 days supplementation have increase acetate, butyrate, and propionate that are important fuels for intestinal epithelial cells that can play an important role in the maintenance of health.

Integrating the Ecosystem Services Framework to Define Dysbiosis of the Breastfed Infant Gut: The Role of B. infantis and Human Milk Oligosaccharides

Mounting evidence supports a connection between the composition of the infant gut microbiome and long-term health. In fact, aberrant microbiome compositions during key developmental windows in early life are associated with increased disease risk; therefore, making pertinent modifications to the microbiome during infancy offers significant promise to improve human health. There is growing support for integrating the concept of ecosystem services (the provision of benefits from ecosystems to humans) in linking specific microbiome functions to human well-being. This framework is widely applied in conservation efforts of macro-ecosystems and offers a systematic approach to guide restoration actions aimed to recover critical ecological functions. The aim of this work is to apply the ecosystem services framework to integrate recent studies demonstrating stable alteration of the gut microbiome of breastfed infants when Bifidobacterium longum subsp. infantis EVC001, a gut symbiont capable of efficiently utilizing human milk oligosaccharides into organic acids that are beneficial for the infant and lower intestinal pH, is reintroduced. Additionally, using examples from the literature we illustrate how the absence of B. infantis results in diminished ecosystem services, which may be associated with health consequences related to immune and metabolic disorders. Finally, we propose a model by which infant gut dysbiosis can be defined as a reduction in ecosystem services supplied to the host by the gut microbiome rather than merely changes in diversity or taxonomic composition. Given the increased interest in targeted microbiome modification therapies to decrease acute and chronic disease risk, the model presented here provides a framework to assess the effectiveness of such strategies from a host-centered perspective.