Environmental enteric dysfunction: pathogenesis, diagnosis, and clinical consequences

Daily Complementary Feeding With Eggs Improves Fibroblast Growth Factor 21 in Infants

This secondary analysis of the Eggcel-growth study investigated the effect of daily egg intake for 6 months in infants aged 6-9 months on environmental enteric dysfunction (EED) biomarkers and the association of EED markers with growth faltering. A randomised controlled trial was conducted in Jouberton, South Africa, among 500 infants randomly assigned equally to either an intervention group receiving a daily chicken egg or a control group. Both groups were followed up for 6 months. Data on infant and maternal sociodemographic information and anthropometric status of infants were collected. EED and inflammatory markers were analysed using Q-Plex Human EED (11-Plex) assay. There was a significant reduction in fibroblast growth factor 21 (FGF21) concentration in the intervention group (B = -0.132; 95% CI -0.255, -0.010; p = 0.035). Baseline, insulin-like growth factor 1 (IGF-1) was positively associated with endpoint length-for-age z-score (LAZ), weight-for-age z-score (WAZ) and weight-for-length z-score (WLZ) and there was an inverse relationship between baseline FGF21 and intestinal fatty acid-binding protein (I-FABP) with endpoint growth indicators. Baseline IGF-1 was positively associated with reduced odds of wasting, stunting and being underweight (p < 0.001) and baseline FGF21 was associated with increased odds of stunting (p = 0.002), wasting (p = 0.031) and being underweight (p = 0.035). There was a 20% increased odds of stunting with baseline I-FABP (p = 0.045) and a 30% increased odds of being underweight with baseline soluble CD14 (p = 0.039). Complementary feeding with eggs decreased growth hormone resistance (reduced FGF21 levels); however, FGF21 and I-FABP levels were linked to increased growth faltering. Trial Registration: ClinicalTrials.gov: NCT05168085.

What works for reducing stunting in low-income and middle-income countries? Cumulative learnings from the Global Stunting Exemplars Project

BACKGROUND

Impaired linear growth and stunting in children under 5 y is a marker of multiple deprivations in low-income and middle-income countries.

OBJECTIVES

We aimed to assess drivers and policies influencing improvements in linear growth and stunting reduction in 10 countries with annual rates of reduction in childhood stunting averaging 1.1% (range: 0.4%-1.7%) at national-level or subnational-level, and to improve a framework of action for other countries to follow.

METHODS

We used mixed methods to assess trends and patterns of improvement in linear growth in children under 5 y using available household-level data and in-depth analysis of programs and their implementation. We assessed patterns of change with multivariate regression analyses of risk factors driving stunting and affecting change. We compared results from the Oaxaca-Blinder decomposition analyses using a hierarchical approach and retrospectively assessed the appropriateness of a previously proposed 10-step process for country-level planning and implementation processes. Limited data precluded robust serial assessment of dietary intake at individual level for children and mothers.

RESULTS

Rapid reduction in childhood stunting is possible and findings across exemplar countries underscore the benefits of indirect and direct interventions in health and other social sectors. These include programs focusing on poverty alleviation; water, sanitation, and hygiene; promotion of girls' education and empowerment; and maternal nutrition. The potential benefits of family planning programs and factors contributing to gains in maternal nutrition were noted. In malarial endemic areas, malaria control programs were associated with improved childhood growth, and patterns of growth indicated continued benefits of childhood disease prevention and management strategies.

CONCLUSIONS

A systematic, evidence-informed approach to improve maternal and child health and nutrition is feasible and, with targeting, can accelerate reduction in linear growth faltering in childhood.

Gastrointestinal changes in paediatric malnutrition that may impact on nutrition choice

Undernutrition is defined as "a condition resulting from imbalanced nutrition or abnormal utilization of nutrients." In this paper, the term malnutrition is used to refer to undernutrition. Malnutrition may be driven by poor socioeconomic conditions or by disease, and it is estimated that disease-related malnutrition (DRM) impacts up to 28% of hospitalized children in Europe. Malnutrition results in alterations in gastrointestinal function that lead to malabsorption of macro- and micro-nutrients. It can lead to altered gut motility and a deficiency of stomach acid, which can result in intestinal colonization by pathogens, causing diarrhoea and high burdens of intestinal infection. The presence of compromised gastrointestinal function in children with DRM is critical as it negatively impacts the efficacy of nutritional support and recovery. When choosing novel strategies and nutritional therapies for malnourished children, consideration should be given to gut-protective interventions that promote better treatment tolerance. When breastmilk is unavailable, whole protein feeds are currently considered as first-line treatment for malnutrition in children with a normal functioning gastrointestinal tract. However, peptide-based feeds have been associated with improved gastrointestinal tolerance and absorption, reduced diarrhoea, reduced inflammation, improved growth and have restored gut integrity compared with free amino acid and whole-protein feeds. At a recent meeting, experts in this area have identified significant research gaps in the literature on peptide-based feeds in children and possible gaps in clinical practice. Whilst the group acknowledges that further work is needed, this paper provides an overview on this topic to further drive research in this area.

Quantifying lactulose and mannitol using LC-MS/MS in a clinical study of children with environmental enteric disease

Dysfunction of the intestinal epithelium barrier (DIEB) is frequent and can lead to serious complications in early childhood when diagnosis and clinical intervention are limited, especially in children with environmental enteric disease and malnutrition. The use of refined analytical techniques is increasingly necessary in this context. This study aimed to validate the high-performance liquid chromatography method coupled with tandem mass spectrometry (LC-MS/MS) to measure DIEB by lactulose:mannitol ratio detection (LM test) in samples of children with different social profiles from Fortaleza, Ceará. The first experimental set was conducted to validate the method through laboratory parameters, such as limit of detection (LD), limit of quantification (LQ), specificity/selectivity, linearity, accuracy, and precision. All validation parameters achieved detection and recovery standards within an acceptable coefficient of variation. Community samples (human development index (HDI) from 0.000 to ≤0.499) were obtained from children from the cohort study Malnutrition-Enteric Diseases, Fortaleza-CE (environmental enteric disease; EED group). The control group samples came from a school located in a region with a high HDI (>0.8). Mannitol excretion was lower in the EED group than in the control group (P<0.0001). On the other hand, LM was higher in this group compared to the control group (P<0.0001). For the first time, a robust analytical approach was used to detect biomarkers of environmental enteropathy (LM) in community samples, confirming with high-sensitivity the damage to the intestinal epithelial barrier function in populations living in low socio-economic conditions.

Faecal biomarkers in children with coeliac disease: A way forward?

AIM

Novel markers to reflect the intestinal damage in coeliac disease are needed. We studied the potential of faecal and serum neopterin, and faecal myeloperoxidase, human β-defensin-2, and lipocalin-2 in a case-control study.

METHODS

Data were collected from medical records and a biobank including newly diagnosed coeliac disease patients, potential coeliac disease patients and non-coeliac controls. Commercially available ELISA assays were used for measuring the biomarkers.

RESULTS

Altogether 19 patients with coeliac disease (median age 9.0 years), 8 with potential coeliac disease (4.0 years) and 18 controls (6.5 years) were included. The highest faecal neopterin levels were seen in potential coeliac disease, followed by controls and coeliac disease (median 513 vs. 372 vs. 255 nmol/L, respectively, p = 0.016). Also, serum neopterin was highest in the potential coeliac disease group (9.8 vs. 5.5 vs. 5.9 nmol/L, p = 0.022). After age adjustment and robust variance estimation, only differences in serum neopterin remained significant. Other markers did not differ between the groups. None of the markers were significantly associated with serum transglutaminase-2 antibody levels.

CONCLUSION

Differences in neopterin levels amongst patients with potential coeliac disease, coeliac disease, and controls suggest that neopterin might serve as an early disease marker.

Mycotoxins and bone growth: a review of the literature on associations between xenobiotic exposure and bone growth and development

Mycotoxins are secondary metabolites of fungi that are known to be associated with linear growth faltering because of their impact on inflammation, intestinal damage, inhibition of protein synthesis, and micronutrient absorption. In this narrative review, we aim to extend this analysis to further explore associations between mycotoxins (aflatoxins, ochratoxins, trichothecenes including deoxynivalenol, T-2 toxin, and fumonisins) and long-bone growth, particularly during the saltatory periods of development. Linear growth is a direct function of skeletal development and long-bone growth. We therefore explored biological pathways and mechanisms of impact of these toxins in both animal and human studies, in addition to the epidemiology literature (post-2020). Given what is known of the effects of individual and combinations of mycotoxins based on the animal literature, we have identified a need for further research and examination of how these toxins and exposures may be studied in humans to elucidate the downstream impact on bone-related biomarkers and anthropometric indices used to identify and predict stunting in population-based studies.

Markers of Environmental Enteric Dysfunction are Associated with Poor Growth and Developmental Outcomes among Young Children in Lusaka, Zambia

OBJECTIVE

To examine cross-sectional relationships between biomarkers of environmental enteric dysfunction (EED), an acquired subclinical condition of the small intestine, and anthropometric and developmental outcomes among children in Lusaka, Zambia.

STUDY DESIGN

Serum samples were collected from 240 children aged 27 to 35 months enrolled in a cluster-randomized trial assessing the effects of growth charts and small-quantity lipid-based nutrient supplements on linear growth. Samples were analyzed using the 11-plex Micronutrient and EED Assessment Tool, which incorporates 2 biomarkers of EED, namely intestinal fatty acid-binding protein (I-FABP), a marker of epithelial damage, and soluble CD14 (sCD14), a marker of microbial translocation. Associations between log2-transformed biomarker concentrations and anthropometric (height-for-age z-score [HAZ], weight-for-height z-score, and weight-for-age z-score) and developmental (Global Scales of Early Development development for age z-score and saccadic reaction time [SRT]) outcomes were assessed using linear regression analyses adjusted for background characteristics.

RESULTS

Mean ± SD HAZ was -1.94 ± 1.10. Higher sCD14 and I-FABP concentrations were significantly associated with lower HAZ (β: -0.21, 95% CI: -0.41, -0.01 and β: -0.20, 95% CI: -0.32, -0.08, respectively). Higher I-FABP concentrations were significantly associated with lower development-for-age z-score (β: -0.22, 95% CI: -0.40, -0.03) and slower SRT (β: 7.37 ms, 95% CI: 2.02, 12.72) as were higher alpha-1-acid glycoprotein concentrations (HAZ β: -0.38, 95% CI: -0.72, -0.03; SRT β: 11.14 ms, 95% CI: 0.94, 21.72).

CONCLUSIONS

In children in Lusaka, biomarkers of EED were associated with poor anthropometric and developmental outcomes, underscoring the need for interventions to address EED to improve child health globally.

CLINICAL TRIAL REGISTRY

ClinicalTrials.gov identifier for parent trial: NCT05120427. https://clinicaltrials.gov/ct2/show/NCT05120427.

Protein supplementation delivered alone or in combination with presumptive azithromycin treatment for enteric pathogens did not improve linear growth in Bangladeshi infants: results of a cluster-randomized controlled trial

BACKGROUND

Protein requirements established for healthy populations may be insufficient to support healthy growth in infants consuming largely cereal-based complementary foods and frequently exposed to enteric pathogens.

OBJECTIVES

This study aimed to assess independent and combined effects of protein supplementation and antibiotic treatment on linear growth of infants aged 6-12 mo.

METHODS

We conducted a 2 × 4 factorial cluster-randomized trial in northwestern Bangladesh, allocating 566 clusters to masked azithromycin (10 mg/kg × 3 d) or placebo at 6 and 9 mo of age and unmasked delivery of an egg white protein-rich blended food supplement (250 kcal; 10 g added protein), a rice-based isocaloric supplement, egg, or nutrition education from 6 to 12 mo. We measured length at 6 and 12 mo. For this cluster-level intention-to-treat analysis of the 2 × 2 antibiotic and protein interventions, we used multiple linear or log-binomial regression with generalized estimating equations to assess changes in length-for-age z (LAZ) score and stunting (LAZ < -2), respectively.

RESULTS

We enrolled 2055 infants (283 clusters) and included 1821 infants (281 clusters) with complete anthropometry data at 6 and 12 mo in our analysis. There were no significant interactions between the protein and antibiotic interventions for any outcomes. Independently, protein supplement did not improve LAZ (β: 0.05; 95% CI: 0.00, 0.11; P = 0.07) or reduce stunting (prevalence ratio: 1.12; 95% CI: 0.85, 1.49; P = 0.41) compared with the isocaloric supplement. The antibiotic intervention had no effect on LAZ (β: -0.05; 95% CI: -0.11, 0.01; P = 0.09) or stunting (prevalence ratio: 0.99; 95% CI: 0.75, 1.31; P = 0.96), relative to the placebo.

CONCLUSIONS

Supplementation to increase intakes of high-quality protein, provided with or without presumptive treatment for enteric pathogens, did not improve linear growth from 6 to 12 mo of age. This trial was registered at clinicaltrials.gov as NCT03683667.

Associations of poor water, sanitation, and hygiene and parasite burden with markers of environmental enteric dysfunction in preschool-age children infected with Schistosoma mansoni in Uganda

BACKGROUND

Environmental enteric dysfunction (EED) is an acquired subclinical condition of the small intestine with lasting health implications for nutritional status, linear growth and development among children. EED is characterised by structural and functional changes to the gut barrier. There are no standardised diagnostic criteria, however, a number of biomarkers have been evaluated to capture EED domains. While the causes of EED are not fully understood, risk factors include poor water, sanitation and hygiene conditions and exposure to enteric pathogens. Very few studies have evaluated the impact of schistosomiasis on EED despite repeated intestinal damage from parasite eggs passing across the gut barrier.

METHODS

In a cohort of 354 preschool-aged children aged 12-47 months with Schistosoma mansoni infection recruited from the Lake Albert region of Uganda, we assessed exposure to water, sanitation and hygiene conditions and measured markers from each EED domain: intestinal inflammation (faecal calprotectin), epithelial damage (serum intestinal fatty-acid binding-protein), increased permeability (urine lactulose to mannitol ratio and faecal alpha-1 antitrypsin) and microbial translocation (serum endotoxin core antibody).

RESULTS

In multivariable linear regression models, we found that children whose drinking water was sourced from Lake Albert had higher concentrations of intestinal fatty-acid binding-protein (β = 0.48, 95% CI 0.20-0.76, p < 0.001), and lack of toilet/latrine access was associated with higher concentrations of calprotectin (β = 0.48, 95% CI 0.18-0.78, p < 0.01). Higher schistosomiasis intensity (eggs per gram of stool) was associated with higher calprotectin (β = 0.10, 95% CI 0.02-0.17, p = 0.01), but not with other EED markers.

CONCLUSIONS

Few studies have investigated schistosomiasis-related morbidities in very young children infected with schistosomiasis. Our findings from Uganda show that poor water, sanitation and hygiene conditions and heavier schistosomiasis burden are associated with intestinal inflammation and damage, contributing to EED. Improved treatment coverage for preschool-aged children infected with schistosomiasis may reduce the burden from EED and associated long-term morbidities.

A New Conceptual Framework for Enhancing Vaccine Efficacy in Malnourished Children

Background

Malnourished children in low- and middle-income countries (LMICs) often exhibit reduced vaccine efficacy, particularly for oral vaccines like polio and rotavirus, due to impaired immune responses. Nutritional deficiencies, such as in vitamin A and zinc, along with environmental factors like poor sanitation, exacerbate this issue. Existing research has explored the individual impacts of malnutrition on vaccine outcomes, but a comprehensive framework that integrates nutritional, immune, and environmental factors has been lacking.

Objective

This article proposes a new conceptual framework that integrates nutritional status, immune function, and environmental context to explain the reduced vaccine efficacy in malnourished populations. The study highlights practical interventions to improve vaccine outcomes in these vulnerable populations.

Methods

A comprehensive literature review was conducted, focusing on vaccine efficacy in malnourished children, with data drawn from cross-sectional surveys, program evaluations, and peer-reviewed studies. Key interventions, including vitamin A supplementation, flexible immunization schedules, and environmental health programs, were analyzed for their impact on improving seroconversion rates.

Results

The review confirms that malnourished children exhibit significantly lower seroconversion rates for vaccines like oral polio and rotavirus, with a 30-40% reduction in efficacy for OPV and up to a 50% reduction for rotavirus. Nutritional interventions, particularly vitamin A supplementation, increased seroconversion rates by up to 30%, while flexible vaccination schedules and environmental improvements further enhanced vaccine responses in severely malnourished populations.

Conclusion

This framework addresses a critical gap in the literature by offering a holistic approach that integrates nutrition, immunization, and environmental health. Global health organizations, such as WHO and UNICEF, must prioritize the integration of nutrition and immunization programs, alongside environmental health initiatives, to reduce the burden of vaccine-preventable diseases in malnourished populations. Future research should focus on longitudinal studies to assess the long-term impact of these integrated interventions.

Small Intestinal Bacterial Overgrowth and Childhood Malnutrition: A Comprehensive Review of Available Evidence

The gut microbiome is essential for children's normal growth and development, with its formation aligning closely with key stages of growth. Factors like birth method, feeding practices, and antibiotic exposure significantly shape the composition and functionality of the infant gut microbiome. Small intestinal bacterial overgrowth (SIBO) involves an abnormal increase in bacteria within the small intestine. This overgrowth can interfere with digestion, impair nutrient absorption, and lead to both local and systemic inflammation, potentially contributing to malnutrition. In this review, we provide a comprehensive overview of the current understanding of the relationship between SIBO and malnutrition, with a particular focus on the pediatric population. SIBO seems to play an important role in nutrient malabsorption through the gut microbiome imbalance, local inflammation, and disruption of the mucosal intestinal barrier. Additionally, SIBO is more prevalent in digestive disorders linked to malabsorption and malnutrition. Different therapeutic strategies for addressing malnutrition-related SIBO have been proposed. While antibiotics are the primary treatment for SIBO, their effectiveness in promoting weight gain among malnourished children remains uncertain. Hence, future research directed at the impact of microbiome imbalance on nutrient intake and absorption could bring to light new strategies for the effective prevention and treatment of malnutrition.

Effects of Vitamin D-3 Supplementation During Pregnancy and Lactation on Maternal and Infant Biomarkers of Environmental Enteric Dysfunction, Systemic Inflammation, and Growth: A Secondary Analysis of a Randomized Controlled Trial

BACKGROUND

Environmental enteric dysfunction (EED) is an acquired, subclinical state of intestinal inflammation common in children and adults in low-income and middle-income countries. Although vitamin D-3 supplementation has purported anti-inflammatory properties, its ability to ameliorate biomarkers of EED remains unclear.

OBJECTIVES

This study aimed to examine the effects of maternal vitamin D-3 supplementation during pregnancy and lactation on biomarkers of EED, systemic inflammation, and growth in women living with HIV and their infants in Dar es Salaam, Tanzania.

METHODS

We conducted subgroup analyses among randomly selected mothers (n = 720) and infants (n = 365 at 6 wk of age, and n = 266 at 6 mo of age) who participated in a randomized, triple-blind, placebo-controlled trial of daily maternal 3000 IU vitamin D-3 supplementation from the second trimester of pregnancy until 1 y postpartum. Biomarkers of EED (soluble CD14 and intestinal fatty acid-binding protein), systemic inflammation (C-reactive protein and α1-acid glycoprotein), and growth factors (insulin-like growth factor 1 and fibroblast growth factor 21) were measured via the Micronutrient and Environmental Enteric Dysfunction Assessment Tool. Anti-flagellin and anti-lipopolysaccharide immunoglobulins were measured via enzyme-linked immunosorbent assay. Comparisons by randomized treatment arm were performed using ordinary least squares regression models with log2-transformed biomarkers.

RESULTS

At 32 wk of gestation, intestinal fatty acid-binding protein (β: -0.19; P = 0.03) and α1-acid glycoprotein (β:-0.11; P = 0.04) were significantly lower in mothers in the vitamin D-3 group than those in mothers in the placebo group. At 6 wk of age, insulin-like growth factor 1 (β:-0.31; P = 0.03) was significantly lower in infants whose mothers were in the vitamin D-3 group than that in infants whose mothers were in the placebo group.

CONCLUSIONS

Vitamin D-3 supplementation during pregnancy and lactation reduced selected EED and systemic inflammation biomarkers among women living with HIV. While the effects of maternal vitamin D-3 supplementation do not appear to extend to infants, there may be an effect on growth factors. This trial was registered at clinicaltrials.gov as NCT02305927 (https://clinicaltrials.gov/study/NCT02305927).

Postnatal supplementation with alarmins S100a8/a9 ameliorates malnutrition-induced neonate enteropathy in mice

Malnutrition is linked to 45% of global childhood mortality, however, the impact of maternal malnutrition on the child's health remains elusive. Previous studies suggested that maternal malnutrition does not affect breast milk composition. Yet, malnourished children often develop a so-called environmental enteropathy, assumed to be triggered by frequent pathogen uptake and unfavorable gut colonization. Here, we show in a murine model that maternal malnutrition induces a persistent inflammatory gut dysfunction in the offspring that establishes during nursing and does not recover after weaning onto standard diet. Early intestinal influx of neutrophils, impaired postnatal development of gut-regulatory functions, and expansion of Enterobacteriaceae were hallmarks of this enteropathy. This gut phenotype resembled those developing under deficient S100a8/a9-supply via breast milk, which is a known key factor for the postnatal development of gut homeostasis. We could confirm that S100a8/a9 is lacking in the breast milk of malnourished mothers and the offspring's intestine. Nutritional supply of S100a8 to neonates of malnourished mothers abrogated the aberrant development of gut mucosal immunity and microbiota colonization and protected them lifelong against severe enteric infections and non-infectious bowel diseases. S100a8 supplementation after birth might be a promising measure to counteract deleterious imprinting of gut immunity by maternal malnutrition.

Review article: Faecal biomarkers for assessing small intestinal damage in coeliac disease and environmental enteropathy

BACKGROUND

In coeliac disease and environmental enteropathy, dietary gluten and enteric infections cause reversible inflammation and morphological changes to the small intestinal mucosa that can be detected in biopsy samples obtained by endoscopy. However, there is a clear need for non-invasive biomarkers. Constant shedding of mucosal material into the bowel lumen and faeces, together with easy availability of stool, makes it an interesting sample matrix.

AIMS

To conduct a systematic literature search and summarize the existing evidence for host mucosa-derived faecal biomarkers in evaluating small intestinal damage.

METHODS

We searched for studies on PubMed (MEDLINE) until 1 March 2024.

RESULTS

We identified 494 studies and included 35 original case-control and cohort studies. These assessed host mucosal transcripts and 14 other markers aiming specifically to reflect inflammation and cell-mediated, innate and gluten-induced immune responses. In coeliac disease, faecal calprotectin and anti-gliadin, tissue transglutaminase, endomysium and deamidated gliadin peptide antibodies were the most studied but with inconsistent results. Single studies reported positive findings about microRNA transcripts, β-defensin-2, lipocalin-2, zonulin-related proteins and angiotensin-converting enzyme. In environmental enteropathy, a non-significant association was reported between calprotectin and urine lactulose/mannitol ratio; there were conflicting results for neopterin, myeloperoxidase and host transcripts. Single studies reported a positive association for lactoferrin, and a negative association for regenerating islet-derived protein 1. Studies comparing faecal markers against small intestinal biopsy findings were not identified in environmental enteropathy.

CONCLUSIONS

Further studies are needed to determine reliable faecal markers as a proxy for small intestinal mucosal damage.

The development and validation of a survey to measure fecal-oral child exposure to zoonotic enteropathogens: The FECEZ Enteropathogens Index

Child exposure to animal feces and associated enteropathogens contribute to a significant burden of disease in low- and middle-income countries. However, there are no standardized, validated survey-based approaches to enable accurate assessment of child exposure to zoonotic enteropathogens. We developed and validated a survey-based measure of exposure, the fecal-oral child exposure to zoonotic enteropathogens Index (the FECEZ Enteropathogens Index). First, we identified critical attributes of child exposure through in-depth interviews (IDIs) in Ecuador among individuals who care for animals (n = 29) and mothers of children under two years old (n = 58), and through a systematic review of existing exposure measures. Second, based on these findings, we developed a 105-question survey and administered it to 297 mothers with children under age five. Third, we refined the survey, using principal component analysis to determine the optimal number of components. The final index consisted of 34 items across two sub-domains: the child Environment and child Behavior. Lastly, we compared index scores to two commonly used, unvalidated measures of child exposure-maternal reported household animal ownership and presence of animal feces. Using the FECEZ Enteropathogens Index revealed varying degrees of exposure in our study population, with only two children having no exposure. In contrast, if we had used animal ownership or the presence of animal feces as a measure of exposure, 44% and 33% of children would have been classified as having no exposure, respectively. These common binary exposure measures may be inadequate because they do not provide sufficient information to identify the relative risk of zoonotic pathogen exposure. The FECEZ Enteropathogens Index overcomes this limitation, advancing our ability to assess exposure by quantifying the multiple components of child exposure to zoonotic enteropathogens with higher resolution. Additional testing and evaluation of the index is needed to ensure its reliability, validity, and cross-cultural equivalence in other contexts.

Performance of empirical and model-based classifiers for detecting sucrase-isomaltase inhibition using the13C-sucrose breath test

The13C-sucrose breath test (13C-SBT) has been proposed to estimate sucrase-isomaltase (SIM) activity and is a promising test for SIM deficiency, which can cause gastrointestinal symptoms, and for intestinal mucosal damage caused by gut dysfunction or chemotherapy. We previously showed how various summary measures of the13C-SBT breath curve reflect SIM inhibition. However, it is uncertain how the performance of these classifiers is affected by test duration. We leveraged13C-SBT data from a cross-over study in 16 adults who received 0, 100, and 750 mg of Reducose, an SIM inhibitor. We evaluated the performance of a pharmacokinetic-model-based classifier,ρ, and three empirical classifiers (cumulative percent dose recovered at 90 min (cPDR90), time to 50% dose recovered, and time to peak dose recovery rate), as a function of test duration using receiver operating characteristic (ROC) curves. We also assessed the sensitivity, specificity, and accuracy of consensus classifiers. Test durations of less than 2 h generally failed to accurately predict later breath curve dynamics. The cPDR90 classifier had the highest ROC area-under-the-curve and, by design, was robust to shorter test durations. For detecting mild SIM inhibition,ρhad a higher sensitivity. We recommend13C-SBT tests run for at least a 2 h duration. Although cPDR90 was the classifier with highest accuracy and robustness to test duration in this application, concerns remain about its sensitivity to misspecification of the CO2production rate. More research is needed to assess these classifiers in target populations.

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.

Anthropometry relationship with duodenal histologic features of children with environmental enteric dysfunction: a multicenter cross-sectional study

BACKGROUND

Environmental enteric dysfunction (EED) is a precursor of growth faltering in children living in impoverished conditions who are frequently exposed to environmental toxins and enteropathogens, leading to small bowel inflammatory, malabsorptive, and permeability derangements and low-grade chronic systemic inflammation.

OBJECTIVES

We explored the association between anthropometrics and duodenal histologic features of EED among children from 3 lower middle-income country centers.

METHODS

In this cross-sectional study, Pakistani children (n = 63) with wasting, Bangladesh children (n = 116) with stunting or at risk for stunting (height-for-age Z score [HAZ] <-1 but ≥-2), and Zambian children (n = 108) with wasting or stunting received nutritional intervention. Children with anthropometric status refractory to intervention underwent endoscopy. Linear regression models included anthropometric around endoscopy, scores of histology parameters, and a global index score of EED-the total score percent-5 (TSP-5). Multivariable models were adjusted for center, age, sex, and histology slide quality.

RESULTS

Intersite variation was observed while exploring the association between anthropometrics and the TSP-5; for example, Pakistani children had the worst HAZ, yet their median TSP-5 score was lower than that of the other 2 centers. Even within each site, no overall pattern of higher TSP-5 score was observed with worsening HAZ. During univariate analysis, TSP-5 (coefficient: 0.01; 95% confidence interval [CI]: 0, 0.02), goblet cell depletion (coefficient: 0.22; 95% CI: 0.06, 0.37), and Paneth cell depletion (coefficient: 0.14; 95% CI: 0.01, 0.27) were associated with HAZ scores; however, they lost statistical significance in the multivariable models, with study center most strongly confounding the relationships seen in univariate models between anthropometry and histology.

CONCLUSIONS

This study contributes a crucial negative finding that duodenal morphological features did not associate with anthropometric phenotypes; hence, anthropometric measurements may not be a suitable outcome measure for use in EED trials. Trial outcomes may need to be defined by combining the functional and structural elements of the gut to monitor EED.

Multiplexed immunohistochemical evaluation of small bowel inflammatory and epithelial parameters in environmental enteric dysfunction

BACKGROUND

Environmental enteric dysfunction (EED) is characterized by reduced absorptive capacity and barrier function of the small intestine, leading to poor ponderal and linear childhood growth.

OBJECTIVES

To further define gene expression patterns that are associated with EED to uncover new pathophysiology of this disorder.

METHODS

Duodenal biopsies from cohorts of children with EED from Bangladesh, Pakistan and Zambia were analyzed by immunohistochemistry (IHC) to interrogate gene products that distinguished differentiation and various biochemical pathways in immune and epithelial cells, some identified by prior bulk RNA sequence analyses. Immunohistochemical staining was digitally quantified from scanned images and compared to cohorts of North American children with celiac disease (gluten-sensitive enteropathy) or with no known enteric disease and no pathologic abnormality (NPA) detected in their clinical biopsies.

RESULTS

After multivariable statistical analysis, we identified statistically significant (P < 0.05, 2-tailed t-test) elevated signals representing cluster of differentiation 45 (80%; 95% confidence interval [CI]: 24%, 127%), lipocalin 2 (659%; 95% CI: 198%, 1838%), and regenerating family 1 beta (221%; 95% CI: 47%, 600%) and lower signals corresponding to granzyme B (-74%; 95% CI: -82%, -62%), and sucrase isomaltase (-58%; 95% CI: -75%, -29%) in EED biopsies compared with NPA biopsies. Computerized algorithms also detected statistically significant elevation in intraepithelial lymphocytes (49%; 95% CI: 9%, 105%) and proliferation of leukocytes (267%; 95% CI: 92%, 601%) in EED biopsies compared with NPA biopsies.

CONCLUSIONS

Our results support a model of chronic epithelial stress that decreases epithelial differentiation and absorptive function. The close association of several IHC parameters with manual histologic scoring suggests that automated digital quantification of IHC panels complements traditional histomorphologic assessment in EED.

Biomarker relationships with small bowel histopathology among malnourished children with environmental enteric dysfunction in a multicountry cohort study

BACKGROUND

Validated biomarkers could catalyze environmental enteric dysfunction (EED) research.

OBJECTIVES

Leveraging an EED histology scoring system, this multicountry analysis examined biomarker associations with duodenal histology features among children with EED. We also examined differences in 2-h compared with 1-h urine collections in the lactulose rhamnose (LR) dual sugar test.

METHODS

Three cohorts of undernourished children unresponsive to nutrition intervention underwent esophagogastroduodenoscopy and duodenal biopsies. Histopathology scores were compared to fecal calprotectin (CAL), myeloperoxidase (MPO), neopterin (NEO), and urinary LR ratio and lactulose percentage recovery. Log-transformed biomarkers were used in linear regressions adjusted for age, center, and sample collection-biopsy time interval in multivariable models.

RESULTS

Data on >1 biomarker were available for 120 Bangladeshi (CAL, MPO, NEO, and LR), 63 Pakistani (MPO, NEO, and LR), and 63 Zambian children (CAL). Median age at endoscopy was similar (19 mo) across centers. Median sample collection prior to endoscopy was consistent with each center's study design: 2 wk in Bangladesh (urine and stool) and Zambia (stool), and 6 (urine) and 11 (stool) mo in Pakistan. In multivariable models, intraepithelial lymphocytes were associated with CAL (exponentiated [exp.] coefficient: 1.19; 95% confidence interval [CI]: 1, 1.41), intramucosal Brunner's glands with MPO (exp. coefficient: 1.33; 95% CI: 1.05, 1.69) and NEO (exp. coefficient: 1.37; 95% CI: 1.1, 1.7), and chronic inflammation with NEO (exp. coefficient: 1.61; 95% CI: 1.17, 2.17). Intraepithelial lymphocytes were associated with lactulose % recovery (exp. coefficient: 1.22; 95% CI: 1.05, 1.41). LR recovery was substantially lower in 1-h collections than in 2-h collections.

CONCLUSIONS

Four commonly used markers of enteric dysfunction were associated with specific histologic features. One-hour urine collection may be insufficient to reflect small bowel permeability in LR testing. While acknowledging the challenges with obtaining relevant tissue, these findings form the basis for further EED biomarker validation research.

Duodenal quantitative mucosal morphometry in children with environmental enteric dysfunction: a cross-sectional multicountry analysis

BACKGROUND

Environmental enteric dysfunction (EED), a chronic inflammatory condition of the small intestine, is an important driver of childhood malnutrition globally. Quantifying intestinal morphology in EED allows for exploration of its association with functional and disease outcomes.

OBJECTIVES

We sought to define morphometric characteristics of childhood EED and determine whether morphology features were associated with disease pathophysiology.

METHODS

Morphometric measurements and histology were assessed on duodenal biopsy slides for this cross-sectional study from children with EED in Bangladesh, Pakistan, and Zambia (n = 69), and those with no pathologic abnormality (NPA; n = 8) or celiac disease (n = 18) in North America. Immunohistochemistry was also conducted on 46, 8, and 18 biopsy slides, respectively. Linear mixed-effects regression models were used to reveal morphometric differences between EED compared with NPA or celiac disease and identify associations between morphometry and histology or immunohistochemistry among children with EED.

RESULTS

In duodenal biopsies, median EED villus height (248 μm), crypt depth (299 μm), and villus:crypt (V:C) ratio (0.9) values ranged between those of NPA (396 μm villus height; 246 μm crypt depth; 1.6 V:C ratio) and celiac disease (208 μm villus height; 365 μm crypt depth; 0.5 V:C ratio). Among EED biopsy slides, morphometric assessments were not associated with histologic parameters or immunohistochemical markers, other than pathologist-determined subjective semiquantitative villus architecture.

CONCLUSIONS

Morphometric analysis of duodenal biopsy slides across geographies identified morphologic features of EED, specifically short villi, elongated crypts, and a smaller V:C ratio relative to NPA slides, although not as severe as in celiac slides. Morphometry did not explain other EED features, suggesting that EED histopathologic processes may be operating independently of morphology. Although acknowledging the challenges with obtaining relevant tissue, these data form the basis for further assessments of the role of morphometry in EED.

Histopathology underlying environmental enteric dysfunction in a cohort study of undernourished children in Bangladesh, Pakistan, and Zambia compared with United States children

BACKGROUND

Environmental enteric dysfunction (EED) is an asymptomatic intestinal disorder associated with growth impairment, delayed neurocognitive development, and impaired oral vaccine responses.

OBJECTIVES

We set out to develop and validate a histopathologic scoring system on duodenal biopsies from a cohort study of children with growth failure in Bangladesh, Pakistan, and Zambia ("EED") with reference to biopsies from United States children with no clinically reported histologic pathology (referred to hereafter as "normal") or celiac disease.

METHODS

Five gastrointestinal pathologists evaluated 745 hematoxylin and eosin slide images from 291 children with EED (mean age: 1.6 y) and 66 United States children (mean age: 6.8 y). Histomorphologic features (i.e., villus/crypt architecture, goblet cells, epithelial and lamina propria acute/chronic inflammation, Brunner's glands, Paneth cells, epithelial detachment, enterocyte injury, and foveolar metaplasia) were used to score each histopathologic slide. Generalized estimating equations were used to determine differences between EED, normal, and celiac disease, and receiver operating characteristic curves were used to assess predictive value.

RESULTS

Biopsies from the duodenal bulb showed higher intramucosal Brunner's gland scores and lower intraepithelial lymphocyte scores than from the second or third parts of the duodenum (D2/3), so only D2/3 were included in the final analysis. Although 7 parameters differed significantly between EED and normal biopsies in regression models, only 5 (blunted villus architecture, increased intraepithelial lymphocytosis, goblet cell depletion, Paneth cell depletion, and reduced intramucosal Brunner's glands) were required to create a total score percentage (TSP-5) that correctly identified EED against normal biopsies (AUC: 0.992; 95% CI: 0.983, 0.998). Geographic comparisons showed more severe goblet cell depletion in Bangladesh and more marked intraepithelial lymphocytosis in Pakistan.

CONCLUSIONS

This scoring system involving 5 histologic parameters demonstrates very high discrimination between EED and normal biopsies, indicating that this scoring system can be applied with confidence to studies of intestinal biopsies in EED.

Protection from environmental enteric dysfunction and growth improvement in malnourished newborns by amplification of secretory IgA

Environmental enteric dysfunction (EED) is a condition associated with malnutrition that can progress to malabsorption and villous atrophy. Severe EED results in linear growth stunting, slowed neurocognitive development, and unresponsiveness to oral vaccines. Prenatal exposure to malnutrition and breast feeding by malnourished mothers replicates EED. Pups are characterized by deprivation of secretory IgA (SIgA) and altered development of the gut immune system and microbiota. Extracellular ATP (eATP) released by microbiota limits T follicular helper (Tfh) cell activity and SIgA generation in Peyer's patches (PPs). Administration of a live biotherapeutic releasing the ATP-degrading enzyme apyrase to malnourished pups restores SIgA levels and ameliorates stunted growth. SIgA is instrumental in improving the growth and intestinal immune competence of mice while they are continuously fed a malnourished diet. The analysis of microbiota composition suggests that amplification of endogenous SIgA may exert a dominant function in correcting malnourishment dysbiosis and its consequences on host organisms, irrespective of the actual microbial ecology.

Machine-learning-based integrative -'omics analyses reveal immunologic and metabolic dysregulation in environmental enteric dysfunction

Environmental enteric dysfunction (EED) is a subclinical enteropathy challenging to diagnose due to an overlap of tissue features with other inflammatory enteropathies. EED subjects (n = 52) from Pakistan, controls (n = 25), and a validation EED cohort (n = 30) from Zambia were used to develop a machine-learning-based image analysis classification model. We extracted histologic feature representations from the Pakistan EED model and correlated them to transcriptomics and clinical biomarkers. In-silico metabolic network modeling was used to characterize alterations in metabolic flux between EED and controls and validated using untargeted lipidomics. Genes encoding beta-ureidopropionase, CYP4F3, and epoxide hydrolase 1 correlated to numerous tissue feature representations. Fatty acid and glycerophospholipid metabolism-related reactions showed altered flux. Increased phosphatidylcholine, lysophosphatidylcholine (LPC), and ether-linked LPCs, and decreased ester-linked LPCs were observed in the duodenal lipidome of Pakistan EED subjects, while plasma levels of glycine-conjugated bile acids were significantly increased. Together, these findings elucidate a multi-omic signature of EED.

Performance of empirical and model-based classifiers for detecting sucrase-isomaltase inhibition using the 13 C-sucrose breath test

Background

Environmental enteric dysfunction (EED) is a syndrome characterized by epithelial damage including blunting of the small intestinal villi and altered digestive and absorptive capacity which may negatively impact linear growth in children. The 13 C-sucrose breath test ( 13 C-SBT) has been proposed to estimate sucrase-isomaltase (SIM) activity, which is thought to be reduced in EED. We previously showed how various summary measures of the 13 C-SBT breath curve reflect SIM inhibition. However, it is uncertain how the performance of these classifiers is affected by test duration.

Methods

We leveraged SBT data from a cross-over study in 16 adults who received 0, 100, and 750 mg of Reducose, a natural SIM inhibitor. We evaluated the performance of a pharmacokinetic-model-based classifier, ρ , and three empirical classifiers (cumulative percent dose recovered at 90 minutes (cPDR90), time to 50% dose recovered, and time to peak dose recovery rate), as a function of test duration using receiver operating characteristic curves. We also assessed the sensitivity, specificity, and accuracy of consensus classifiers.

Results

Test durations of less than 2 hours generally failed to accurately predict later breath curve dynamics. The cPDR90 classifier had the highest area-under-the-curve and, by design, was robust to shorter test durations. For detecting mild SIM inhibition, ρ had a higher sensitivity.

Conclusions

We recommend SBT tests run for at least a 2-hour duration. Although cPDR90 was the classifier with highest accuracy and robustness to test duration in this application, concerns remain about its sensitivity to misspecification of CO 2 production rate. More research is needed to assess these classifiers in target populations.

Dietary aflatoxins exposure, environmental enteropathy, and their relation with childhood stunting

Childhood stunting is a global phenomenon affecting more than 149 million children under the age of 5 worldwide. Exposure to aflatoxins (AFs) in utero, during breastfeeding, and consumption of contaminated food affect the gut microbiome, resulting in intestinal dysfunction and potentially contributing to stunting. This review explores the potential relationship between AF exposure, environmental enteropathy and childhood stunting. AFs bind to DNA, disrupt protein synthesis and elicit environmental enteropathy (EE). An EE alters the structure of intestinal epithelial cells, impairs nutrient uptake and leads to malabsorption. This article proposes possible intervention strategies for researchers and policymakers to reduce AF exposure, EE and childhood stunting, such as exposure reduction, the implementation of good agricultural practices, dietary diversification and improving environmental water sanitation and hygiene.

Factors associated with stunting in under-five children with environmental enteropathy in slum areas of Jimma town, Ethiopia

Introduction

Stunting is a major public health issue with a significant influence on the health and development of children in low-income countries, where it affects up to 32% of children. Nutritional intake is impacted by alterations in intestinal permeability and underlying chronic inflammation, which hinder children's normal linear growth. Environmental enteropathy is a poorly understood condition with chronic intestinal inflammation. The purpose of this study was to identify the magnitude of stunting, change in growth, and factors associated with stunting and change in height for the age Z-score of children with an elevated lactulose-to-mannitol ratio.

Methods

An observational follow-up study was conducted to follow children with an elevated lactulose-to-mannitol ratio for changes in their linear growth. A lactulose-mannitol test was performed to identify children with elevated lactulose-to-mannitol ratios, indicative of environmental enteropathy. After a 1-year follow-up, anthropometry was repeated to assess their linear growth. A multivariable logistic regression analysis was performed to identify the independent predictors for stunting in children with elevated lactulose-to-mannitol ratios. All tests were two-sided, and a p-value of <0.05 was considered significant.

Results

The prevalence of stunting in children with an elevated L:M at baseline and end line was found to be 72.4% (95% CI: 60.3, 84.5) and 78.4% (95% CI: 66.7, 90.2), respectively. In a multivariate analysis, a low dietary diversity score (<4 food groups), presence of flies and insects in the toilet area, poor handwashing practices during a critical time, and MUAC z < -2 were significantly associated with stunting. Flies and insects in the toilet area and unsafe disposal of feces were significantly associated with changes in HAZ in children with elevated lactulose-to-mannitol ratios, an indicator of environmental enteropathy.

Conclusion

Most of the children with an elevated lactulose-to-mannitol ratio in the study population were stunted, and no significant change in their linear growth was observed after 1-year follow-up. Therefore, further investigation and urgent intervention are needed to prevent environmental enteropathy and stunting among under-five children in this community who are exposed to very poor sanitary conditions and other risk factors for malnutrition.

Prevalence and Correlates of Stunting among a High-Risk Population of Kenyan Children Recently Hospitalized for Acute Illnesses

Stunting (length/height-for-age z-score < -2) is associated with significant morbidity and mortality among children under 5 years of age in sub-Saharan Africa. Children who are stunted and recently hospitalized for acute illness may be at particularly elevated risk for post-discharge mortality. In this cross-sectional analysis, we measured the prevalence of stunting at hospital discharge and identified host, caregiver, and environmental correlates of stunting among children aged 1-59 months in Western Kenya enrolled in the Toto Bora Trial. Child age- and site-adjusted prevalence ratios were estimated using Poisson regression. Of the 1,394 children included in this analysis, 23% were stunted at hospital discharge. Older children (12-23 months and 24-59 months versus 0-5 months) had a higher prevalence of stunting (adjusted prevalence ratio [aPR]: 1.58; 95% CI: 1.04-2.36 and aPR: 1.59; 95% CI: 1.08-2.34, respectively). HIV-exposed, uninfected children (aPR: 1.94; 95% CI: 1.39-2.70), children with HIV infection (aPR: 2.73; 95% CI: 1.45-5.15), and those who were never exclusively breastfed in early life (aPR 2.51; 95% CI: 1.35-4.67) were more likely to be stunted. Caregiver education (primary school or less) and unimproved sanitation (pit latrine without slab floor or open defecation) were associated with increased risk of stunting (aPR: 1.94; 95% CI: 1.54-2.44; aPR: 1.99; 95% CI: 1.20-3.31; aPR: 3.57; 95% CI: 1.77-7.21, respectively). Hospital discharge represents an important opportunity for both identifying and delivering targeted interventions for nutrition-associated poor outcomes among a high-risk population of children.

NAD+ precursors and bile acid sequestration treat preclinical refractory environmental enteric dysfunction

Environmental enteric dysfunction (EED) is a diffuse small bowel disorder associated with poor growth, inadequate responses to oral vaccines, and nutrient malabsorption in millions of children worldwide. We identify loss of the small intestinal Paneth and goblet cells that are critical for innate immunity, reduced villous height, increased bile acids, and dysregulated nicotinamide adenine dinucleotide (NAD+) synthesis signaling as potential mechanisms underlying EED and which also correlated with diminished length-for-age z score. Isocaloric low-protein diet (LPD) consumption in mice recapitulated EED histopathology and transcriptomic changes in a microbiota-independent manner, as well as increases in serum and fecal bile acids. Children with refractory EED harbor single-nucleotide polymorphisms in key enzymes involved in NAD+ synthesis. In mice, deletion of Nampt, the gene encoding the rate-limiting enzyme in the NAD+ salvage pathway, from intestinal epithelium also reduced Paneth cell function, a deficiency that was further aggravated by LPD. Separate supplementation with NAD+ precursors or bile acid sequestrant partially restored LPD-associated Paneth cell defects and, when combined, fully restored all histopathology defects in LPD-fed mice. Therapeutic regimens that increase protein and NAD+ contents while reducing excessive bile acids may benefit children with refractory EED.

Genetic variation in environmental enteropathy and stunting in Zambian children: A pilot genome wide association study using the H3Africa chip

PURPOSE

Stunting is known to be heavily influenced by environmental factors, so the genetic contribution has received little attention. Here we report an exploration of genetic influences in stunted Zambian children with environmental enteropathy.

METHOD

Children with stunting (LAZ < -2) were enrolled and given nutritional therapy. Those that were non-responsive to therapy were designated as cases, and children with good growth (LAZ > -1) from the same community as controls. Blood and stool samples were taken to measure biomarkers of intestinal inflammation, epithelial damage, and microbial translocation. Single nucleotide polymorphism array genotyping was carried out on saliva samples using the H3Africa consortium array.

RESULTS

Genome wide associations were analysed in 117 cases and 41 controls. While no significant associations with stunting were observed at P<5x10-8, likely due to the small sample size, interesting associations were observed at lower thresholds. SNPs associated with stunting were in genomic regions known to modulate neuronal differentiation and fatty acid biosynthesis. SNPs associated with increased microbial translocation were associated with non-integrin membrane ECM interactions, tight junctions, hemostasis, and G-alpha signalling events. SNPs associated with increased inflammation were associated with, ECM interactions, purine metabolism, axon guidance, and cell motility. SNPs negatively associated with inflammation overlapped genes involved in semaphoring interactions. We explored the existing coeliac disease risk HLA genotypes and found present: DQ2.5 (7.5%), DQ8 (3.5%) and DQ2.2 (3.8%); however, no children were positive for coeliac antibodies. We detected HLA-DRB:1301 and HLA-C:1802 with high odds ratios and P<0.05 in stunted children compared to controls.

CONCLUSION

Genetic variations associated with stunting and the enteropathy underlying it, include variants associated with multiple pathways relating to gene expression, glycosylation, nerve signalling, and sensing of the nutritional and microbiological milieu.

Plasma proteomic signatures of enteric permeability among hospitalized and community children in Kenya and Pakistan

We aimed to establish if enteric permeability was associated with similar biological processes in children recovering from hospitalization and relatively healthy children in the community. Extreme gradient boosted models predicting the lactulose-rhamnose ratio (LRR), a biomarker of enteric permeability, using 7,500 plasma proteins and 34 fecal biomarkers of enteric infection among 89 hospitalized and 60 community children aged 2-23 months were built. The R2 values were calculated in test sets. The models performed better among community children (R2: 0.27 [min-max: 0.19, 0.53]) than hospitalized children (R2: 0.07 [min-max: 0.03, 0.11]). In the community, LRR was associated with biomarkers of humoral antimicrobial and cellular lipopolysaccharide responses and inversely associated with anti-inflammatory and innate immunological responses. Among hospitalized children, the selected biomarkers had few shared functions. This suggests enteric permeability among community children was associated with a host response to pathogens, but this association was not observed among hospitalized children.

Campylobacter vaccination reduces diarrheal disease and infant growth stunting among rhesus macaques

Campylobacter-associated enteric disease is estimated to be responsible for more than 160 million cases of gastroenteritis each year and is linked to growth stunting of infants living under conditions of poor sanitation and hygiene. Here, we examine naturally occurring Campylobacter-associated diarrhea among rhesus macaques as a model to determine if vaccination could reduce severe diarrheal disease and infant growth stunting. Compared to unvaccinated controls, there are no Campylobacter diarrhea-associated deaths observed among vaccinated infant macaques and all-cause diarrhea-associated infant mortality is decreased by 76% (P = 0.03). By 9 months of age, there is a 1.3 cm increase in dorsal length that equaled a significant 1.28 LAZ (Length-for-Age Z score) improvement in linear growth among vaccinated infants compared to their unvaccinated counterparts (P = 0.001). In this work, we show that Campylobacter vaccination not only reduces diarrheal disease but also potentially serves as an effective intervention that improves infant growth trajectories.

Environmental enteropathy and its association with water sanitation and hygiene in slum areas of Jimma Town Ethiopia

BACKGROUND

Environmental Enteropathy is an inflammatory condition of the gut that leads to intestinal barrier dysfunction. It is a common problem in resource-limited countries and results from exposure to larger quantities of fecal bacteria to poor personal hygiene and environmental sanitation. Due to poor intestinal permeability, there is a problem with absorption of nutrients, which in turn leads to growth faltering, poor cognitive development, and oral-vaccine failure. The aim of this study was to identify the children with an elevated lactulose to mannitol ratio (indicative of possible environmental enteropathy) and its association with water sanitation and hygiene in slum areas of Jimma Town so as to mitigate the problem of malnutrition in under-five children.

METHODS

A community-based cross-sectional study was carried out from January to April 2021. A Lactulose mannitol test was performed to determine the prevalence of elevated lactulose to mannitol ratio (possibly environmental enteropathy) in children aged 12 to 59 months. A pretested questionnaire was used to collect data on water sanitation and hygiene (WASH) indicators and sociodemographic characteristics. A multivariable logistic regression analysis was used to isolate independent predictors for possible environmental enteropathy. All tests were two-sided and statistical significance was declared at P<0.05.

RESULTS

The results of this study showed that 19.3% (95%CI: 14.8-23.7) of children had an increased lactulose to mannitol ratio (>0.15). On multivariable logistic regression analysis, the variables drinking water from unimproved water sources (AOR 3.741; 95%CI: 0.914-15.310,p = 0.048), unsafe coverage of water storage (AOR 0.363; 95%CI: 0.169-0.777, P = 0.009), public latrine utilization (AOR 0.139 95%CI: 0.024-0.816, P = 0.029),and hand washing less than 3 critical time of hand washing practices (AOR 4.369;95%CI: 1.411-13.524,P = 0.011) were significantly associated with an increased in lactulose mannitol ratio (possible indicative of intestinal permeability/environmental enteropathy).

CONCLUSION

This study showed that one fifth of under-five children in Jimma Town had an elevated lactulose to mannitol ratio (possibly environmental enteropathy). The WASH sectors and other governmental organizations should give emphasis to areas with poor water sanitation and hygiene to mitigate the problem of environmental enteropathy and related consequences like growth faltering, poor cognitive development, and oral-vaccine failure in the study area.

Epidemiology of small intestinal bacterial overgrowth

Small intestinal bacterial overgrowth (SIBO) is defined as an increase in the bacterial content of the small intestine above normal values. The presence of SIBO is detected in 33.8% of patients with gastroenterological complaints who underwent a breath test, and is significantly associated with smoking, bloating, abdominal pain, and anemia. Proton pump inhibitor therapy is a significant risk factor for SIBO. The risk of SIBO increases with age and does not depend on gender or race. SIBO complicates the course of a number of diseases and may be of pathogenetic significance in the development of their symptoms. SIBO is significantly associated with functional dyspepsia, irritable bowel syndrome, functional abdominal bloating, functional constipation, functional diarrhea, short bowel syndrome, chronic intestinal pseudo-obstruction, lactase deficiency, diverticular and celiac diseases, ulcerative colitis, Crohn's disease, cirrhosis, metabolic-associated fatty liver disease (MAFLD), primary biliary cholangitis, gastroparesis, pancreatitis, cystic fibrosis, gallstone disease, diabetes, hypothyroidism, hyperlipidemia, acromegaly, multiple sclerosis, autism, Parkinson's disease, systemic sclerosis, spondylarthropathy, fibromyalgia, asthma, heart failure, and other diseases. The development of SIBO is often associated with a slowdown in orocecal transit time that decreases the normal clearance of bacteria from the small intestine. The slowdown of this transit may be due to motor dysfunction of the intestine in diseases of the gut, autonomic diabetic polyneuropathy, and portal hypertension, or a decrease in the motor-stimulating influence of thyroid hormones. In a number of diseases, including cirrhosis, MAFLD, diabetes, and pancreatitis, an association was found between disease severity and the presence of SIBO. Further work on the effect of SIBO eradication on the condition and prognosis of patients with various diseases is required.

Intestinal Epithelial Digestive, Transport, and Barrier Protein Expression Is Increased in Environmental Enteric Dysfunction

Environmental enteric dysfunction (EED) is characterized by malabsorption and diarrhea that result in irreversible deficits in physical and intellectual growth. We sought to define the expression of transport and tight junction proteins by quantitative analysis of duodenal biopsies from patients with EED. Biopsies from Pakistani children with confirmed EED diagnoses were compared to those from age-matched North American healthy controls, patients with celiac disease, and patients with nonceliac disease with villous atrophy or intraepithelial lymphocytosis. Expression of brush border digestive and transport proteins and paracellular (tight junction) proteins was assessed by quantitative multiplex immunofluorescence microscopy. EED was characterized by partial villous atrophy and marked intraepithelial lymphocytosis. Epithelial proliferation and enteroendocrine, tuft, and Paneth cell numbers were unchanged, but there was significant goblet cell expansion in EED biopsies. Expression of proteins involved in nutrient and water absorption and that of the basolateral Cl- transport protein NKCC1 were also increased in EED. Finally, the barrier-forming tight junction protein claudin-4 (CLDN4) was significantly upregulated in EED, particularly within villous enterocytes. In contrast, expression of CFTR, CLDN2, CLDN15, JAM-A, occludin, ZO-1, and E-cadherin was unchanged. Upregulation of a barrier-forming tight junction protein and brush border and basolateral membrane proteins that support nutrient and water transport in EED is paradoxical, as their increased expression would be expected to be correlated with increased intestinal barrier function and enhanced absorption, respectively. These data suggest that EED activates adaptive intestinal epithelial responses to enhance nutrient absorption but that these changes are insufficient to restore health.

Essential Fatty Acid Deficiency Associates with Growth Faltering and Environmental Enteric Dysfunction in Children

Environmental enteric dysfunction (EED) is characterized by intestinal inflammation, malabsorption and growth-faltering in children with heightened exposure to gut pathogens. The aim of this study was to characterize serum non-esterified fatty acids (NEFA), in association with childhood undernutrition and EED, as potential biomarkers to predict growth outcomes. The study comprised a cohort of undernourished rural Pakistani infants (n = 365) and age-matched controls followed prospectively up to 24 months of age. Serum NEFA were quantified at ages 3–6 and 9 months and correlated with growth outcomes, serum bile acids and EED histopathological biomarkers. Serum NEFA correlated with linear growth-faltering and systemic and gut biomarkers of EED. Undernourished children exhibited essential fatty acid deficiency (EFAD), with low levels of linoleic acid and total n-6 polyunsaturated fatty acids, compensated by increased levels of oleic acid and increased elongase and desaturase activities. EFAD correlated with reduced anthropometric Z scores at 3–6 and 9 months of age. Serum NEFA also correlated with elevated BA and liver dysfunction. Essential fatty acid depletion and altered NEFA metabolism were highly prevalent and associated with acute and chronic growth-faltering in EED. The finding suggests that targeting early interventions to correct EFAD and promote FA absorption in children with EED may facilitate childhood growth in high-risk settings.

Assessing environmental enteric dysfunction via multiplex assay and its relation to growth and development among HIV-exposed uninfected Tanzanian infants

BACKGROUND

Environmental enteric dysfunction (EED) may contribute to poor growth and development in young children. While validated EED biomarkers are currently lacking, multiplex assays are able to capture multiple domains of the condition. The purpose of this exploratory study was to examine the relationship between biomarkers of EED and subsequent growth and development among Tanzanian HIV-exposed uninfected (HEU) infants.

METHODOLOGY

We enrolled 467 infants of mothers living with HIV who had participated in a trial of vitamin D3 supplementation during pregnancy. Infant serum samples collected at 6 weeks (n = 365) and 6 months (n = 266) were analyzed for anti-flagellin and anti-lipopolysaccharide (LPS) IgA and IgG via ELISA as well as the 11-plex Micronutrient and EED Assessment Tool (MEEDAT), which incorporates two biomarkers of EED [intestinal fatty acid-binding protein (I-FABP) and soluble CD14 (sCD14)]. Outcomes were 12-month growth [length-for-age z-score (LAZ), weight-for-length z-score (WLZ), and weight-for-age z-score (WAZ)] and development [Caregiver Reported Early Development Instruments (CREDI) z-scores] and were assessed using linear regression.

FINDINGS

In primary analyses, higher quartiles of 6-month anti-LPS IgG concentrations were significantly associated with lower LAZ at 12 months (ptrend = 0.040). In secondary analyses, higher log2-transformed 6-week anti-flagellin IgA and 6-month anti-LPS IgA concentrations were significantly associated with lower LAZ at 12 months. No associations were observed between I-FABP or sCD14 and infant growth. However, higher log2-transformed 6-week sCD14 concentrations were significantly associated with lower overall CREDI z-scores, while higher log2-transformed 6-month I-FABP concentrations were significantly associated with higher overall CREDI z-scores.

CONCLUSIONS

Unlike anti-flagellin and anti-LPS Igs, MEEDAT's biomarkers of EED (I-FABP and sCD14) were not associated with subsequent linear growth among HEU infants in Tanzania. The relationship between EED and infant development warrants further study.

Impact of enteropathogens on faltering growth in a resource-limited setting

Introduction

Environmental enteropathy is an important contributor to childhood malnutrition in the developing world. Chronic exposure to fecal pathogens leads to alteration in intestinal structure and function, resulting in impaired gut immune function, malabsorption, and growth faltering leading to environmental enteropathy.

Methods

A community-based intervention study was carried out on children till 24 months of age in Matiari district, Pakistan. Blood and fecal specimens were collected from the enrolled children aged 3-6 and 9 months. A real-time PCR-based TaqMan array card (TAC) was used to detect enteropathogens.

Results

Giardia, Campylobacter spp., enteroaggregative Escherichia coli (EAEC), Enteropathogenic Escherichia coli (EPEC), Enterotoxigenic Escherichia coli (ETEC), and Cryptosporidium spp. were the most prevailing enteropathogens in terms of overall positivity at both time points. Detection of protozoa at enrollment and 9 months was negatively correlated with rate of change in height-for-age Z (ΔHAZ) scores during the first and second years of life. A positive association was found between Giardia, fecal lipocalin (LCN), and alpha 1-Acid Glycoprotein (AGP), while Campylobacter spp. showed positive associations with neopterin (NEO) and myeloperoxidase (MPO).

Conclusion

Protozoal colonization is associated with a decline in linear growth velocity during the first 2 years of life in children living in Environmental enteric dysfunction (EED) endemic settings. Mechanistic studies exploring the role of cumulative microbial colonization, their adaptations to undernutrition, and their influence on gut homeostasis are required to understand symptomatic enteropathogen-induced growth faltering.

Enteric Permeability, Systemic Inflammation, and Post-Discharge Growth Among a Cohort of Hospitalized Children in Kenya and Pakistan

OBJECTIVES

To determine whether gut permeability is associated with post-discharge growth and systemic inflammation among hospitalized children in low- and middle-income countries.

METHODS

Children aged 2-23 months being discharged from Civil Hospital Karachi (Pakistan) and Migori County Referral Hospital (Kenya) underwent lactulose-rhamnose ratio (LRR) permeability testing and were compared to age-matched children from their home communities. Linear mixed effect models estimated the associations between LRR among discharged children with change in length-for-age (LAZ) and weight-for-age z score (WAZ) at 45, 90, and 180 days after discharge. Linear regression tested if relationships between LRR, systemic inflammation [C-reative protein (CRP), Cluster of Differentiation 14 (CD14), Tumour Necrosis Factor Alpha (TNFα), Interleukin-6 (IL-6)], and enterocyte damage [Intestinal Fatty-Acid Binding protein (I-FABP)] differed between the hospitalized and community groups.

RESULTS

One hundred thirty-seven hospitalized and 84 community participants were included. The hospitalized group had higher log-LRR [0.43, 95% confidence interval (CI): 0.15-0.71, P = 0.003] than the community children. Adjustment for weight-for-length z score at discharge attenuated this association (0.31, 95% CI: 0.00-0.62, P = 0.049). LRR was not associated with changes in WAZ or LAZ in the post-discharge period. Associations between LRR and CRP (interaction P = 0.036), TNFα ( P = 0.017), CD14 ( P = 0.078), and IL-6 ( P = 0.243) differed between community and hospitalized groups. LRR was associated with TNFα ( P = 0.004) and approached significance with CD14 ( P = 0.078) and IL-6 ( P = 0.062) in community children, but there was no evidence of these associations among hospitalized children.

CONCLUSIONS

Although increased enteric permeability is more prevalent among children being discharged from hospital compared to children in the community, it does not appear to be an important determinant of systemic inflammation or post-discharge growth among hospitalized children.

The role of environmental enteric dysfunction in the pathogenesis of Schistosoma mansoni-associated morbidity in school-aged children

Background

Studies have implicated schistosomiasis as a cause of intestinal barrier disruption, a salient feature of environmental enteric dysfunction (EED), as eggs translocate from the sterile bloodstream through the gut wall. We examined the longitudinal impact of praziquantel (PZQ) treatment on a) EED biomarkers and b) Insulin growth factor I (IGF-1), a key driver of childhood linear growth, since EED has been implicated in linear growth stunting.

Methodology

290 children infected with S. mansoni in Brazil were treated with PZQ at baseline. EED biomarkers lipopolysaccharide (LPS) and intestinal fatty acid binding-protein (I-FABP) were measured, as well as IGF-1 at baseline, 6 and 12-months. Multivariate regression analysis was applied to assess associations between S. mansoni intensity and plasma biomarkers (LPS, I-FABP, and IGF-1), controlling for potential confounding variables.

Principal findings

At baseline, S. mansoni infection intensities were 27.2% light, 46.9% moderate, and 25.9% heavy. LPS concentrations were significantly reduced at the 12-month visit compared to baseline (p = 0.0002). No longitudinal changes were observed for I-FABP or IGF-1 in the 6- or 12-month periods following baseline treatment. After 6-months, I-FABP concentration was significantly higher in high vs low intensity (p = 0.0017). IGF-1 concentrations were significantly lower among children with high and moderate vs low intensity infections at each study visit.

Conclusions/significance

We report that S. mansoni infection impacts LPS, I-FABP and IGF-1. These findings suggest a mechanistic role for EED in schistosomiasis-related morbidities, particularly linear growth.

Schistosoma mansoni is a tropical parasitic infection that causes intestinal schistosomiasis. In infected humans, the parasite worms shed eggs that migrate across the gut barrier, which damages intestinal structure and function. In children, intestinal schistosomiasis leads to anemia, undernutrition, and linear growth stunting. The mechanistic pathways between schistosomiasis and stunting are not fully understood, but this research explores the role of environmental enteric dysfunction (EED) in schistosomiasis-related morbidity. EED is an intestinal condition that affects children living in areas of poor water, sanitation, and hygiene and also leads to impaired growth and stunting. In a longitudinal cohort of Brazilian children infected with S. mansoni, we measured blood biomarkers of EED and linear growth at three time points over 12 months. All of the children were treated for schistosomiasis at baseline, and after 12 months, we observed a significant decrease in a marker of EED, suggesting improvement in gut integrity. We also found that children who had higher parasite egg burden at the baseline visit had lower levels of insulin-like growth factor-1, a hormone that drives growth in children. Our findings suggest that EED may play a role in schistosomiasis-related stunting and furthers our understanding for S. mansoni pathogenesis in children.

de Souza P, Costa H, Houpt ER, Bessong PO, Mduma ER, Lima AAM, Guerrant RL. Impact of Shigella infections and inflammation early in life on child growth and school-aged cognitive outcomes: Findings from three birth cohorts over eight years

Background

Shigella infections cause inflammation, which has been hypothesized to mediate the associations between Shigella and child development outcomes among children in low-resource settings. We aimed to assess whether early life inflammation and Shigella infections affect school-aged growth and cognitive outcomes from 6–8 years of age.

Methodology/principal findings

We conducted follow-up assessments of anthropometry, reasoning skills, and verbal fluency in 451 children at 6–8 years of age in the Brazil, Tanzania, and South Africa sites of MAL-ED, a longitudinal birth cohort study. We estimated the associations between Shigella burden and inflammation with linear growth at 2, 5, and 6–8 years of age, and with the cognitive test scores using linear regression and adjusting for potential confounding variables. We also assessed whether inflammation mediated the associations between Shigella and school-aged outcomes using a regression-based approach to mediation analysis. A high prevalence of Shigella was associated with a 0.32 (95% CI: 0.08, 0.56) z-score lower height-for-age z-score (HAZ) at 6–8 years compared to a low prevalence of Shigella. Intestinal inflammation had a smaller association with HAZ at 6–8 years. Shigella burden had small and consistently negative associations with cognitive outcomes in Brazil and Tanzania, but not South Africa, and the estimates were not statistically significant. Systemic inflammation was strongly associated with lower verbal fluency scores in Brazil (semantic fluency z-score difference: -0.57, 95% CI: -1.05, -0.10; phonemic fluency z-score difference: -0.48, 95% CI: -0.93, -0.03). There was no evidence that intestinal inflammation mediated the association between Shigella and HAZ or cognitive outcomes.

Conclusions/significance

While Shigella infections were consistently associated with long-term deficits in linear growth, the estimates of the negative associations between Shigella and cognitive outcomes were imprecise and only observed in the Brazil and Tanzania sites. Systemic inflammation was strongly associated with lower semantic and phonemic fluency scores in Brazil only, highlighting the site-specificity of effects.

Shigella infections are common among children in low-resource settings and cause inflammation, which may contribute to poor child development outcomes. We studied children from birth to 6–8 years of age in Brazil, Tanzania, and South Africa to assess whether Shigella infections and markers of inflammation in the first 2 years of life were associated with child development outcomes at school age, including height and cognitive assessment scores. Shigella infections were consistently associated with long-term deficits in linear growth. However, the associations between Shigella and cognitive outcomes were smaller, not statistically significant, and inconsistent across the three sites. There was no evidence that inflammation caused by Shigella explained the associations between Shigella and school-aged outcomes. Systemic inflammation was strongly associated with lower cognitive assessment scores in Brazil but not in the other sites, highlighting the differences in determinants of child development across settings. Quantifying the impact and understanding mechanisms for the effect of early life exposures to Shigella on long-term cognitive outcomes remains challenging.

13C-sucrose breath test for the non-invasive assessment of environmental enteropathy in Zambian adults

Objectives

Environmental enteropathy (EE) is a subclinical disorder highly prevalent in tropical and disadvantaged populations and is thought to play a role in growth faltering in children, poor responses to oral vaccines, and micronutrient deficiencies. This study aims to evaluate the potential of a non-invasive breath test based on stable isotopes for evaluation of impaired digestion and absorption of sucrose in EE.

Methods

We optimized a ¹³C-sucrose breath test (¹³C-SBT) in 19 young adults in Glasgow, United Kingdom. In a further experiment (in 18 adults) we validated the ¹³C-SBT using Reducose, an intestinal glucosidase inhibitor. We then compared the ¹³C-SBT to intestinal mucosal morphometry, immunostaining for sucrose-isomaltase (SI) expression, and SI activity in 24 Zambian adults with EE.

Results

Fully labeled sucrose (0.3 mg/kg) provided clear breath enrichment signals over 2–3 h in both British and Zambian adults, more than fivefold higher than naturally enriched sucrose. Reducose dramatically impaired ¹³C-sucrose digestion, reducing 4 h ¹³CO₂ breath recovery by > 50%. Duodenal biopsies in Zambian adults confirmed the presence of EE, and SI immunostaining was present in 16/24 adults. The kinetics of ¹³CO₂ evolution were consistently faster in participants with detectable SI immunostaining. Although sucrase activity was strongly correlated with villus height (r = 0.72; P < 0.05) after adjustment for age, sex and body mass index, there were no correlations between ¹³C-SBT and villus height or measured sucrase activity in pinch biopsies.

Conclusion

A ¹³C-SBT was developed which was easy to perform, generated clear enrichment of ¹³CO₂ in breath samples, and clearly reports sucrase activity. Further work is needed to validate it and understand its applications in evaluating EE.

Association between intestinal bacterial carriage, biomarkers of environmental enteric dysfunction, and stunting in rural Malawian children

Background. Available data from murine studies suggest that intestinal bacteria may have a role in modulating growth phenotypes in the host. We investigated the prevalence of four gut bacteria known in murine models to impair growth (Bifidobacterium longum, Faecalibacterium prausnitzii, Dorea formicigenerans, and Akkermansia muciniphila), the level of fecal biomarkers of environmental enteric dysfunction (EED) and stunting in rural Malawian children. Methods. DNA and protein were extracted from fecal samples of rural Malawian children (aged 1-59 months) at a baseline cross-sectional survey in the Mangochi district of Malawi conducted within the framework of the Macrolides Oraux pour Réduire les Décès avec un Oeil sur la Résistance (MORDOR) trial. Intestinal carriage of bacteria was measured by PCR. Neopterin (NEO), myeloperoxidase (MPO), and alpha-1 antitrypsin (AAT), biomarkers of EED, were measured by an enzyme-linked immunosorbent assay (ELISA) test. Height-for-age Z (HAZ) score <-2 defined stunting. Tests of proportions and regression models were used to explore the relationship between bacterial carriage, EED, and stunting. Results. Fecal samples from 613 children were available for laboratory analyses. F. prausnitzii and D. formicigenerans were prevalent in over 70% of children while B. longum was the least prevalent. B. longum carriage in younger children was associated with elevated EED biomarkers. Two thirds of children had elevated NEO, 33% had elevated MPO, and 16% had elevated AAT. Stunting was found in 38%. No significant associations were found between EED biomarkers or intestinal bacteria carriage and stunting. Conclusion. Intestinal carriage of these four bacteria was not associated with stunting in Malawian children. Carriage was also not associated with EED, nor EED biomarker levels associated with stunting. Further factors acting in concert are necessary to impact EED, perturb growth, and alter gut bacterial carriage.

Food Safety Practices and Stunting among School-Age Children—An Observational Study Finding from an Urban Slum of Bangladesh

Background: Food safety incorporates the handling, preparation, and storage of food materials in ways that prevent foodborne illness. We aimed to investigate the typical food safety practices in a Bangladeshi slum context and to explore if stunting among school-age children was associated with various components of food safety. Method: We analysed the MAL-ED birth cohort data from the Bangladesh site. A total of 265 healthy children were enrolled in the study; we could follow up and collect food safety-related data from 187 participants. Results: The average age of the children was 6.5 years (standard deviation or SD 0.04) and 49% of them were female. About 26% of the children were stunted. In our bivariate analysis, caregivers’ handwashing practice after using the toilet, treatment of drinking water, presence of insects/pests in the cooking area, and child’s eating ready-made/street food more than three times per day were significantly associated with stunting. After adjusting for pertinent factors, treatment of drinking water (adjusted odds ratio or AOR = 2.50, 95% confidence interval or CI: 1.03, 6.05), and child’s eating ready-made/street food more than three times/day (AOR = 2.34, 95%CI: 1.06, 5.15) remained significantly associated with stunting. Conclusions: Diverse aspects of food safety practices have a substantial association with stunting among school-age children living in an unhygienic slum environment in Dhaka, Bangladesh.

Astrocytes and Microglia in Stress-Induced Neuroinflammation: The African Perspective

Background: Africa is laden with a youthful population, vast mineral resources and rich fauna. However, decades of unfortunate historical, sociocultural and leadership challenges make the continent a hotspot for poverty, indoor and outdoor pollutants with attendant stress factors such as violence, malnutrition, infectious outbreaks and psychological perturbations. The burden of these stressors initiate neuroinflammatory responses but the pattern and mechanisms of glial activation in these scenarios are yet to be properly elucidated. Africa is therefore most vulnerable to neurological stressors when placed against a backdrop of demographics that favor explosive childbearing, a vast population of unemployed youths making up a projected 42% of global youth population by 2030, repressive sociocultural policies towards women, poor access to healthcare, malnutrition, rapid urbanization, climate change and pollution. Early life stress, whether physical or psychological, induces neuroinflammatory response in developing nervous system and consequently leads to the emergence of mental health problems during adulthood. Brain inflammatory response is driven largely by inflammatory mediators released by glial cells; namely astrocytes and microglia. These inflammatory mediators alter the developmental trajectory of fetal and neonatal brain and results in long-lasting maladaptive behaviors and cognitive deficits. This review seeks to highlight the patterns and mechanisms of stressors such as poverty, developmental stress, environmental pollutions as well as malnutrition stress on astrocytes and microglia in neuroinflammation within the African context.

Mucosal-Associated Invariant T (MAIT) cells are highly activated in duodenal tissue of humans with Vibrio cholerae O1 infection: A preliminary report

Mucosal-associated invariant T (MAIT) cells are unconventional T lymphocytes with a semi-conserved TCRα, activated by the presentation of vitamin B metabolites by the MHC-I related protein, MR1, and with diverse innate and adaptive effector functions. The role of MAIT cells in acute intestinal infections, especially at the mucosal level, is not well known. Here, we analyzed the presence and phenotype of MAIT cells in duodenal biopsies and paired peripheral blood samples, in patients during and after culture-confirmed Vibrio cholerae O1 infection. Immunohistochemical staining of duodenal biopsies from cholera patients (n = 5, median age 32 years, range 26-44, 1 female) identified MAIT cells in the lamina propria of the crypts, but not the villi. By flow cytometry (n = 10, median age 31 years, range 23-36, 1 female), we showed that duodenal MAIT cells are more activated than peripheral MAIT cells (p < 0.01 across time points), although there were no significant differences between duodenal MAIT cells at day 2 and day 30. We found fecal markers of intestinal permeability and inflammation to be correlated with the loss of duodenal (but not peripheral) MAIT cells, and single-cell sequencing revealed differing T cell receptor usage between the duodenal and peripheral blood MAIT cells. In this preliminary report limited by a small sample size, we show that MAIT cells are present in the lamina propria of the duodenum during V. cholerae infection, and more activated than those in the blood. Future work into the trafficking and tissue-resident function of MAIT cells is warranted.

High prevalence of small intestine bacteria overgrowth and asymptomatic carriage of enteric pathogens in stunted children in Antananarivo, Madagascar

Environmental Enteric Dysfunction (EED) refers to an incompletely defined syndrome of inflammation, reduced absorptive capacity, and reduced barrier function in the small intestine. It is widespread among children and adults in low- and middle-income countries and is also associated with poor sanitation and certain gut infections possibly resulting in an abnormal gut microbiota, small intestinal bacterial overgrowth (SIBO) and stunting.

We investigated bacterial pathogen exposure in stunted and non-stunted children in Antananarivo, Madagascar by collecting fecal samples from 464 children (96 severely stunted, 104 moderately stunted and 264 non-stunted) and the prevalence of SIBO in 109 duodenal aspirates from stunted children (61 from severely stunted and 48 from moderately stunted children). SIBO assessed by both aerobic and anaerobic plating techniques was very high: 85.3% when selecting a threshold of ≥10⁵ CFU/ml of bacteria in the upper intestinal aspirates. Moreover, 58.7% of the children showed more than 10⁶ bacteria/ml in these aspirates. The most prevalent cultivated genera recovered were Streptococcus, Neisseria, Staphylococcus, Rothia, Haemophilus, Pantoea and Branhamella. Feces screening by qPCR showed a high prevalence of bacterial enteropathogens, especially those categorized as being enteroinvasive or causing mucosal disruption, such as Shigella spp., enterotoxigenic Escherichia coli, enteropathogenic E. coli and enteroaggregative E. coli. These pathogens were detected at a similar rate in stunted children and controls, all showing no sign of severe diarrhea the day of inclusion but both living in a highly contaminated environment (slum-dwelling). Interestingly Shigella spp. was the most prevalent enteropathogen found in this study (83.3%) without overrepresentation in stunted children.

About 2 million children under the age of 5 suffer from stunted growth in Madagascar. Although deficient diet is the major cause of undernutrition, impaired absorption or assimilation caused by Environmental Enteric dysfunction (EED) has been proposed to play an important role in stunting. EED is widespread among children and adults in low- and middle-income countries (LMIC) and is also associated with undernutrition, poor sanitation, certain gut infections resulting in an abnormal gut microbiota and small intestinal bacterial overgrowth (SIBO) although the role of SIBO in EED remains unclear. The current study highlights the presence at high concentrations of bacterial taxa usually found in the oro-pharyngeal sphere in a high number of duodenal fluids of stunted children. This uncommon presence suggests a decompartmentalization of the gastrointestinal tract and a possible pro-inflammatory effect due to the ectopic presence of some of these bacteria in the duodenum.

The study also points to a high prevalence of enteropathogens (especially Shigella spp.) in the feces of both stunted and control children, hence preventing from proposing a direct association with stunting. This suggests that, beside combatting poverty and improving diet, environmental sanitation, quality of water sources, hygiene promotion and health education are key points to mitigate stunting and restore nutritional benefits.

Cessation of exclusive breastfeeding and seasonality, but not small intestinal bacterial overgrowth, are associated with environmental enteric dysfunction: A birth cohort study amongst infants in rural Kenya

Background

Environmental Enteric Dysfunction (EED) is a chronic intestinal inflammatory disorder of unclear aetiology prevalent amongst children in low-income settings and associated with stunting. We aimed to characterise development of EED and its putative risk factors amongst rural Kenyan infants.

Methods

In a birth cohort study in Junju, rural coastal Kenya, between August 2015 and January 2017, 100 infants were each followed for nine months. Breastfeeding status was recorded weekly and anthropometry monthly. Acute illnesses and antibiotics were captured by active and passive surveillance. Intestinal function and small intestinal bacterial overgrowth (SIBO) were assessed by monthly urinary lactulose mannitol (LM) and breath hydrogen tests. Faecal alpha-1-antitrypsin, myeloperoxidase and neopterin were measured as EED biomarkers, and microbiota composition assessed by 16S sequencing.

Findings

Twenty nine of the 88 participants (33%) that underwent length measurement at nine months of age were stunted (length-for-age Z score <-2). During the rainy season, linear growth was slower and LM ratio was higher. In multivariable models, LM ratio, myeloperoxidase and neopterin increased after cessation of continuous-since-birth exclusive breastfeeding. For LM ratio this only occurred during the rainy season. EED markers were not associated with antibiotics, acute illnesses, SIBO, or gut microbiota diversity. Microbiota diversified with age and was not strongly associated with complementary food introduction or linear growth impairment.

Interpretation

Our data suggest that intensified promotion of uninterrupted exclusive breastfeeding amongst infants under six months during the rainy season, where rainfall is seasonal, may help prevent EED. Our findings also suggest that therapeutic strategies directed towards SIBO are unlikely to impact on EED in this setting. However, further development of non-invasive diagnostic methods for SIBO is required.

Funding

This research was funded in part by the Wellcome Trust (Research Training Fellowship to RJC (103376/Z/13/Z)). EPKP was supported by the MRC/DfID Newton Fund (MR/N006259/1). JAB was supported by the MRC/DFiD/Wellcome Trust Joint Global Health Trials scheme (MR/M007367/1) and the Bill & Melinda Gates Foundation (OPP1131320). HHU was supported by the NIHR Oxford Biomedical Research Centre (IS-BRC-1215-20008).

Fecal biomarkers of environmental enteric dysfunction and associated factors among children aged 24-59 months in east Dembiya district, northwest Ethiopia

Background

Environmental enteric dysfunction is a subclinical intestinal disorder characterized by gut inflammation accompanied by morphological changes, such as blunted villi and crypt hyperplasia. This is a common illness in low and middle-income countries. However, environmental enteric dysfunction evidence is limited in Ethiopia. Accordingly, this study was conducted to measure fecal biomarkers of environmental enteric dysfunction and associated factors among children aged 24–59 months in rural northwest Ethiopia.

Methods

A community-based cross-sectional study was employed among 235 randomly selected children in a rural setting of the east Dembiya district. Stool samples were collected without fixative and analyzed for fecal biomarkers of environmental enteric dysfunction (Alpha-1-antitrypsin, neopterin, and myeloperoxidase) using commercial enzyme-linked immunosorbent assay kits and analyzed for intestinal parasites using wet mount and Kato-Katz techniques. Child behaviors related with exposure to enteropathogens, condition of the living environment and socio-demographic information were collected using interviewer-administered questionnaire and structure observation. We fitted multivariable linear regression model to assess the association between environmental factors and concentration of fecal biomarkers of environmental enteric dysfunction in the stool. Statistically significant associations were declared based on adjusted betas with the corresponding 95% confidence interval and p-value < 0.05.

Results

The median concentration of fecal markers of environmental enteric dysfunction was 350 μg/ml for Alpha-1-antitrypsin, 3320.2 ng/ml for myeloperoxidase, and 1562 nmol/l for neopterin. The median concentration of Alpha-1-antitrypsin among 161 (68.5%), myeloperoxidase among 168 (71.5%), and neopterin among 188 (80%) of the stool samples were above the normal values in non-tropical settings. Moreover, 100 (42.6%) of the children had high EED disease activity score (above the median score). The elevated concentrations of fecal biomarkers of gut inflammation and the high EED disease activity score were significantly associated with open defecation practice, mouthing of soil contaminated materials, Escherichia coli (E. coli)  contamination of drinking water, E. coli contamination of foods, E. coli contamination of soil, and intestinal parasites.

Conclusion

Overall, Alpha-1-antitrypsin, myeloperoxidase, and neopterin levels among the children in the studied region were highly elevated in comparison to populations in high-income countries. Moreover, the EED disease activity score in significant proportion of children was high, suggesting widespread intestinal inflammation and increased intestinal permeability. Extensive E. coli contamination of the living environment (drinking water, ready-to-eat foods, and courtyard soil), hygiene and sanitation behaviors (such as open defecation and mouthing of soil contaminated materials), and a high burden of intestinal parasites were identified as factors associated with the elevated concentration of fecal biomarkers of environmental enteric dysfunction. Parental care to children to avoid mouthing of soil contaminated materials and other risky behaviors that increase exposure enteric infections, and protecting the living environment (water, food and soil) from fecal contamination are important.