Geography of intestinal permeability and absorption

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.

Dietary intervention with edible film-coated multistrain probiotic Lacticaseibacilli in nondairy food matrices significantly increased the recovery of fecal viable Lacticaseibacilli and improved the performance of several colonic biomarkers among slightly malnourished preschool children

Probiotic enriched dairy products are widely consumed in Western countries for their beneficial effects on the gastrointestinal tract and overall health. The present study aims to investigate the beneficial effects of probiotic Lacticaseibacilli (LAB) strains in non-dairy food matrices. A blend of edible film-coated probiotic LAB, L. plantarum, L. paracasei, and L. rhamnosus, were incorporated into plain biscuits and dry dates. Design of the randomized controlled study: Children of both sexes (mean age 55.7 ± 14.5 months) attending kindergarten in Tersa, a poor urban Giza district, were recruited and randomized into 5 groups of equal numbers. Treatment groups: (1) placebo biscuits, (2) functional probiotic biscuits (0.18 billion colony forming units (cfu) of LAB) (3) functional probiotic + inulin biscuits (0.2 billion cfu of LAB + 2 g of chicory inulin); (4) placebo dates and (5) functional probiotic dates (0.3 billion cfu of viable multistrain LAB). The supplements were served 5 days a week and each child had to consume 21 servings of the supplement. The primary outcome was an increase in the fecal recovery of viable LAB after the intake of 21 servings (T1) compared to the respective baseline counts (T0). The secondary outcomes include the determination of fecal short-chain fatty acids (SCFA) and secretory immunoglobulin A (s-Ig A) using ELISA and fecal ammonia excretion. Results: Statistically significant % increases in the recoveries of fecal viable LAB were found among the children consuming 21 servings of supplements 2, 3, and 5 compared to the respective count at T0. Similar significant increases were found in the fecal concentrations of SCFA and s-Ig A among the children consuming 21 servings of supplements 2, 3 and 5 compared to the respective counts at T0. On the other hand, the concentration of toxic ammonia excretion decreased significantly in the feces of all children consuming probiotic-containing supplements (groups 2, 3, and 5) at T1 compared to the respective concentrations obtained at T0. Conclusion: Multistrain microencapsulated probiotic Lacticaseibacilli in functional biscuits and dry dates successfully tolerated the acidic gastric transit and exerted their bioactive action on the colonic microbiome. The synbiotic supplement exhibited a higher production rate of colonic SCFA. Probiotic-enriched products that confer definitive health benefits are convenient and do not need to be kept under refrigeration. Manipulating the composition and function of the microbiome in childhood through probiotic/+ prebiotic interventions is cost-effective with long-term beneficial health outcomes. This study was approved by the Medical Research Ethics Committee, National Research Center and registered as Clinical Trial 16/422. Written informed consent was obtained from the mothers of all participating children.

A critical examination of human data for the biological activity of quercetin and its phase-2 conjugates

This critical review examines evidence for beneficial effects of quercetin phase-2 conjugates from clinical intervention studies, volunteer feeding trials, and in vitro work. Plasma concentrations of quercetin-3-O-glucuronide (Q3G) and 3'-methylquercetin-3-O-glucuronide (3'MQ3G) after supplementation may produce beneficial effects in macrophages and endothelial cells, respectively, especially if endogenous deglucuronidation occurs, and lower blood uric acid concentration via quercetin-3'-O-sulfate (Q3'S). Unsupplemented diets produce much lower concentrations (<50 nmol/l) rarely investigated in vitro. At 10 nmol/l, Q3'S and Q3G stimulate or suppress, respectively, angiogenesis in endothelial cells. Statistically significant effects have been reported at 100 nmol/l in breast cancer cells (Q3G), primary neuron cultures (Q3G), lymphocytes (Q3G and3'MQ3G) and HUVECs (QG/QS mixture), but it is unclear whether these translate to a health benefit in vivo. More sensitive and more precise methods to measure clinically significant endpoints are required before a conclusion can be drawn regarding effects at normal dietary concentrations. Future requirements include better understanding of inter-individual and temporal variation in plasma quercetin phase-2 conjugates, their mechanisms of action including deglucuronidation and desulfation both in vitro and in vivo, tissue accumulation and washout, as well as potential for synergy or antagonism with other quercetin metabolites and metabolites of other dietary phytochemicals.

The energetics of childhood: Current knowledge and insights into human variation, evolution, and health

How organisms capture and ultimately use metabolic energy-a limiting resource of life-has profound implications for understanding evolutionary legacies and current patterns of phenotypic variation, adaptation, and health. Energetics research among humans has a rich history in biological anthropology and beyond. The energetics of childhood, however, remains relatively underexplored. This shortcoming is notable given the accepted importance of childhood in the evolution of the unique human life history pattern as well as the known sensitivity of childhood development to local environments and lived experiences. In this review, I have three objectives: (1) To overview current knowledge regarding how children acquire and use energy, highlighting work among diverse human populations and pointing to recent advances and remaining areas of uncertainty; (2) To discuss key applications of this knowledge for understanding human variation, evolution, and health; (3) To recommend future avenues for research. A growing body of evidence supports a model of trade-offs and constraint in childhood energy expenditure. This model, combined with advancements on topics such as the energetics of immune activity, the brain, and the gut, provides insights into the evolution of extended human subadulthood and the nature of variation in childhood development, lifetime phenotype, and health.

Implementation strategies for improving vitamin D status and increasing vitamin D intake in the UK: current controversies and future perspectives: proceedings of the 2nd Rank Prize Funds Forum on vitamin D

A multi-disciplinary expert group met to discuss vitamin D deficiency in the UK and strategies for improving population intakes and status. Changes to UK Government advice since the 1st Rank Forum on Vitamin D (2009) were discussed, including rationale for setting a reference nutrient intake (10 µg/d; 400 IU/d) for adults and children (4+ years). Current UK data show inadequate intakes among all age groups and high prevalence of low vitamin D status among specific groups (e.g. pregnant women and adolescent males/females). Evidence of widespread deficiency within some minority ethnic groups, resulting in nutritional rickets (particularly among Black and South Asian infants), raised particular concern. Latest data indicate that UK population vitamin D intakes and status reamain relatively unchanged since Government recommendations changed in 2016. Vitamin D food fortification was discussed as a potential strategy to increase population intakes. Data from dose-response and dietary modelling studies indicate dairy products, bread, hens' eggs and some meats as potential fortification vehicles. Vitamin D3 appears more effective than vitamin D2 for raising serum 25-hydroxyvitamin D concentration, which has implications for choice of fortificant. Other considerations for successful fortification strategies include: (i) need for 'real-world' cost information for use in modelling work; (ii) supportive food legislation; (iii) improved consumer and health professional understanding of vitamin D's importance; (iv) clinical consequences of inadequate vitamin D status and (v) consistent communication of Government advice across health/social care professions, and via the food industry. These areas urgently require further research to enable universal improvement in vitamin D intakes and status in the UK population.

Epithelial Abnormalities in the Small Intestine of Zambian Children With Stunting

Background

Environmental enteropathy (EE) contributes to impaired linear growth (stunting), in millions of children worldwide. We have previously reported that confocal laser endomicroscopy (CLE) shows fluorescein leaking from blood to gut lumen in vivo in adults and children with EE. We set out to identify epithelial lesions which might explain this phenomenon in Zambian children with stunting non-responsive to nutritional support.

Methods

We performed confocal laser endomicroscopy (CLE) in 75 children and collected intestinal biopsies for histology in 91 children. CLE videos were evaluated, employing the Watson score to determine severity of leakiness. Morphometry was carried out on well-orientated mucosa and 3 biopsies were examined by electron microscopy.

Results

Confocal laser endomicroscopy demonstrated substantial leakage from circulation to gut lumen in 73 (97%) children. Histology consistently showed characteristic changes of EE: villus blunting, lamina propria and epithelial inflammation, and depletion of secretory cells (Paneth cells and goblet cells). Epithelial abnormalities included marked variability in epithelial height, disorganised and shortened microvilli, dilated intercellular spaces, pseudostratification, formation of synechiae between epithelium on adjacent villi, crypt destruction, and abundant destructive lesions which may correspond to the microerosions identified on CLE.

Conclusion

Epithelial abnormalities were almost universal in Zambian children with non-responsive stunting, including epithelial microerosions, cell-cell adhesion anomalies, and defects in secretory cells which may all contribute to impairment of mucosal barrier function and microbial translocation.

Reduced Fractional Absorption of Zinc in Children With Environmental Enteropathy in Zambia

OBJECTIVES

We measured fractional absorption of zinc (FAZ) in children with environmental enteropathy (EE) and carried out transcriptomic analysis of biopsies from these children in order to compare FAZ to histology of intestinal biopsies, expression of zinc transporter genes, and biomarkers of enteropathy.

METHODS

Fractional absorption of a standardized aqueous dose of zinc was measured by a dual isotope ratio technique in a cohort of children ages between 9 and 24 months in Lusaka, Zambia, who all had non-responsive stunting. Gene expression analysis was carried out on biopsies through RNA sequencing using an Illumina HiSeq2000 platform.

RESULTS

All 33 children had histological features of environmental enteropathy and plasma zinc concentrations below the lower limit of normal. Measured FAZ ranged from 0.18 to 0.93; all values >0.55 were observed in girls. FAZ was negatively correlated with faecal myeloperoxidase (MPO) (ρ = -0.51, n = 17; P = 0.04) and faecal calprotectin (ρ = -0.50, n = 16; P = 0.05), but not blood biomarkers. Of 41 genes with known roles in zinc metabolism, only three metallothionein genes were significantly correlated with FAZ.

CONCLUSIONS

Zinc homeostasis is impaired in children with environmental enteropathy, and was inversely correlated with mucosal inflammation. Reduced FAZ without specific changes in expression of most zinc transporter genes could be explained by reduced absorptive surface area due to villus/microvillus atrophy.

Gene expression profiles compared in environmental and malnutrition enteropathy in Zambian children and adults

BACKGROUND

Environmental enteropathy (EE) contributes to growth failure in millions of children worldwide, but its relationship to clinical malnutrition has not been elucidated. We used RNA sequencing to compare duodenal biopsies from adults and children with EE, and from children with severe acute malnutrition (SAM), to define key features of these malnutrition-related enteropathies.

METHODS

RNA was extracted and sequenced from biopsies of children with SAM in hospital (n=27), children with non-responsive stunting in the community (n=30), and adults living in the same community (n=37) using an identical sequencing and analysis pipeline. Two biopsies each were profiled and differentially expressed genes (DEGs) were computed from the comparisons of the three groups. DEG lists from these comparisons were then subjected to analysis with CompBio software to assemble a holistic view of the biological landscape and IPA software to interrogate canonical pathways.

FINDINGS

Dysregulation was identified in goblet cell/mucin production and xenobiotic metabolism/detoxification for both cohorts of children, versus adults. Within the SAM cohort, substantially greater induction of immune response and barrier function, including NADPH oxidases was noted, concordant with broadly reduced expression of genes associated with the brush border and intestinal structure/transport/absorption. Interestingly, down regulation of genes associated with the hypothalamic-pituitary-adrenal axis was selectively observed within the cohort of children with stunting.

INTERPRETATION

Gene expression profiles in environmental enteropathy and severe acute malnutrition have similarities, but SAM has several distinct transcriptional features. The intestinal capacity to metabolise drugs and toxins in malnourished children requires further study.

FUNDING

Bill & Melinda Gates Foundation (OPP1066118).

Understanding the role of the gut in undernutrition: what can technology tell us?

Gut function remains largely underinvestigated in undernutrition, despite its critical role in essential nutrient digestion, absorption and assimilation. In areas of high enteropathogen burden, alterations in gut barrier function and subsequent inflammatory effects are observable but remain poorly characterised. Environmental enteropathy (EE)-a condition that affects both gut morphology and function and is characterised by blunted villi, inflammation and increased permeability-is thought to play a role in impaired linear growth (stunting) and severe acute malnutrition. However, the lack of tools to quantitatively characterise gut functional capacity has hampered both our understanding of gut pathogenesis in undernutrition and evaluation of gut-targeted therapies to accelerate nutritional recovery. Here we survey the technology landscape for potential solutions to improve assessment of gut function, focussing on devices that could be deployed at point-of-care in low-income and middle-income countries (LMICs). We assess the potential for technological innovation to assess gut morphology, function, barrier integrity and immune response in undernutrition, and highlight the approaches that are currently most suitable for deployment and development. This article focuses on EE and undernutrition in LMICs, but many of these technologies may also become useful in monitoring of other gut pathologies.

Tenth year reenrollment randomized trial investigating the effects of childhood probiotics and calcium supplementation on height and weight at adolescence

Microbiota and its modification with specific probiotics in early life could provide long term health benefits. Probiotics and calcium strengthen intestinal integrity and may support linear growth. This study investigated the long-term effects of childhood probiotics and calcium supplementation on growth in adolescence. We re-enrolled 238 adolescents aged 11-18 years from 494 children 10-years after 6-months of supplementation with either low-lactose milk fortified with low levels of calcium (LC, ∼50 mg/day, n = 53/124), with regular levels of calcium (RC, ∼440 mg/day, n = 70/126), or with regular calcium + 5 x 108 CFU/day Lactobacillus reuteri DSM 17938 (Reuteri, n = 55/124), or regular calcium + 5 x 108 CFU/day L. casei CRL 431 (Casei, n = 60/120). Changes in height-for-age z-score (HAZ) and body mass index-for-age z-score (BMIZ) were determined from the end of intervention to re-enrollment. General linear models were used to assess the effects on HAZ and BMIZ of group, gender, living area, maternal education, family income, physical activity, diet quality, nutritional status, and gut integrity as determined by urinary lactulose/mannitol ratio (L:M). Adolescent mean age was 15.3 years, mean HAZ was - 1.11, mean BMIZ was - 0.2 and median L:M (n = 155) was 0.23. Changes in HAZ and BMIZ were not significantly different between Casei, Reuteri, LC compared to RC. However, a significant decrease in BMIZ was observed among female adolescents in the Casei compared to RC group (- 0.5 SD, 95% CI - 0.8 to - 0.003, p = 0.048). Childhood probiotic and calcium supplementation may therefore selectively affect female adolescents.Clinical trial registration: This follow-up study has been registered at www.clinicaltrials.gov , Registry name: Rina Agustina, Registration number: NCT04046289, First Registration Date 06/08/19. web link: https://www.clinicaltrials.gov/ct2/show/NCT04046289 .

The contribution of environmental enteropathy to the global problem of micronutrient deficiency

Sometimes referred to as hidden hunger, micronutrient deficiencies persist on a global scale. For some micronutrients this appears to be due to inadequate intake, for others intake may not match increased requirements. However, for most micronutrient deficiencies there is uncertainty as to the dominant driver, and the question about the contribution of malabsorption is open. Environmental enteropathy (EE), formerly referred to as tropical enteropathy and also referred to as environmental enteric dysfunction, is an asymptomatic disorder of small intestinal structure and function which is very highly prevalent in many disadvantaged populations. Recent studies of the pathology and microbiology of this disorder suggest that it is driven by very high pathogen burdens in children and adults living in insanitary environments and is characterised by major derangements of the epithelial cells of the intestinal mucosa. Transcriptomic data suggest that it may lead to impaired digestion and absorption of macronutrients. Given the very high prevalence of EE, marginal malabsorption could have large impacts at population scales. However, the relative contributions of inadequate soil and crop micronutrient contents, inadequate intake, malabsorption and increased requirements are unknown. Malabsorption may compromise attempts to improve micronutrient status, but with the exception of zinc there is currently little evidence to confirm that malabsorption contributes to micronutrient deficiency. Much further research is required to understand the role of malabsorption in hidden hunger, especially in very disadvantaged populations where these deficiencies are most prevalent.

Adaptation of the small intestine to microbial enteropathogens in Zambian children with stunting

Environmental enteropathy is a major contributor to growth faltering in millions of children in Africa and South Asia. We carried out a longitudinal, observational and interventional study in Lusaka, Zambia, of 297 children with stunting (aged 2-17 months at recruitment) and 46 control children who had good growth (aged 1-5 months at recruitment). Control children contributed data only at baseline. Children were provided with nutritional supplementation of daily cornmeal-soy blend, an egg and a micronutrient sprinkle, and were followed up to 24 months of age. Children whose growth did not improve over 4-6 months of nutritional supplementation were classified as having non-responsive stunting. We monitored microbial translocation from the gut lumen to the bloodstream in the cohort with non-responsive stunting (n = 108) by measuring circulating lipopolysaccharide (LPS), LPS-binding protein and soluble CD14 at baseline and when non-response was declared. We found that microbial translocation decreased with increasing age, such that LPS declined in 81 (75%) of 108 children with non-responsive stunting, despite sustained pathogen pressure and ongoing intestinal epithelial damage. We used confocal laser endomicroscopy and found that mucosal leakiness also declined with age. However, expression of brush border enzyme, nutrient transporter and mucosal barrier genes in intestinal biopsies did not change with age or correlate with biomarkers of microbial translocation. We propose that environmental enteropathy arises through adaptation to pathogen-mediated epithelial damage. Although environmental enteropathy reduces microbial translocation, it does so at the cost of impaired growth. The reduced epithelial surface area imposed by villus blunting may explain these findings.

Safety and Ethics in Endoscopic Studies in Children: Evidence From the BEECH Study in Zambia

BACKGROUND

Environmental enteropathy is an example of a poorly-understood intestinal disorder affecting millions of children worldwide, characterized by malabsorption and stunting. Although there is increasing interest in non-invasive means of assessing intestinal structure and function, the potential value of intestinal biopsy for histology, immunostaining, RNA sequencing and epigenetic work means that endoscopic biopsy remains extremely valuable. We here report our experience in the BEECH (Biomarkers of Environmental Enteropathy in CHildren) study of stunting in Zambia, in the belief that it may help address the knowledge gap regarding the safety of endoscopic biopsy in vulnerable young children.

METHODS

We report our experience of safety in 119 children undergoing endoscopic biopsy in the BEECH study in Lusaka Children's Hospital, Lusaka, and discuss ethical considerations in this light.

RESULTS

Upper gastrointestinal endoscopy was performed on children with stunting (length-for-age z score -2 or less) not responsive to nutritional interventions. Conscious sedation was provided by anaesthetists. Of 119 children, 5 (4%) developed transient desaturation, but no serious adverse events were experienced; no clinical, demographic or anaesthetic characteristics were identified as predictive of desaturation. Two children derived clinically useful information from the endoscopy, one life-saving. Of 105 lactase tests, 59 (54%) showed hypolactasia.

DISCUSSION

Children with stunting underwent endoscopy safely, and some derived clinical benefit. Safety and the possibility of clinical benefit are usually felt to be preconditions for the ethical justification for endoscopy for research in children, and we believe that these conditions were met in this study.

Efficiency of Vitamin D Supplementation in Healthy Adults is Associated with Body Mass Index and Baseline Serum 25-Hydroxyvitamin D Level

Vitamin D (VitD) has a critical role in phosphorous-calcium metabolism as well as an important role in the immune system. In the human body, VitD is synthesized as cholecalciferol in the skin, but this process requires sunlight (UVB) radiation. Numerous reports showed high prevalence of VitD deficiency, particularly during the winter season, indicating the importance of VitD supplementation. Various factors can affect the absorption of VitD, including dosage and formulation. The primary study objective was to examine the efficiency of supplementation with three different formulations containing cholecalciferol in comparison with the control group. The secondary objective was to identify other factors affecting increase in serum 25-OH-VitD. A randomized controlled intervention study was conducted in Slovenia during wintertime (January- March) on 105 apparently healthy subjects (aged 18-65 years) with suboptimal VitD status (25-OH-VitD 30-50 nmol/L). Subjects were randomized into four groups: three treatment groups receiving (A) capsules with starch-adsorbed VitD, (B) oil-based Valens VitD oral spray, or (C) water-based Valens VitD oral spray and a control group (D) which did not receive supplemental VitD. Two months of supplementation with cholecalciferol (1000 IU; 25 µg daily) resulted in significant increase in serum 25-OH-VitD levels in comparison with control group (pooled Δc 32.8 nmol/L; 95% CI: 23.0, 42.5, p < 0.0001). While we did not observe any significant differences between the tested formulations, the efficiency of supplementation was associated with body mass index and baseline serum 25-OH-VitD level. Higher supplementation efficiency was observed in participants with normal body weight (BMI < 25) and in those with more pronounced VitD insufficiency. We also determined that tested dosage was not sufficient to achieve recommended 25-OH-VitD levels in all subjects.

The Gastrointestinal Exertional Heat Stroke Paradigm: Pathophysiology, Assessment, Severity, Aetiology and Nutritional Countermeasures

Exertional heat stroke (EHS) is a life-threatening medical condition involving thermoregulatory failure and is the most severe condition along a continuum of heat-related illnesses. Current EHS policy guidance principally advocates a thermoregulatory management approach, despite growing recognition that gastrointestinal (GI) microbial translocation contributes to disease pathophysiology. Contemporary research has focused to understand the relevance of GI barrier integrity and strategies to maintain it during periods of exertional-heat stress. GI barrier integrity can be assessed non-invasively using a variety of in vivo techniques, including active inert mixed-weight molecular probe recovery tests and passive biomarkers indicative of GI structural integrity loss or microbial translocation. Strenuous exercise is strongly characterised to disrupt GI barrier integrity, and aspects of this response correlate with the corresponding magnitude of thermal strain. The aetiology of GI barrier integrity loss following exertional-heat stress is poorly understood, though may directly relate to localised hyperthermia, splanchnic hypoperfusion-mediated ischemic injury, and neuroendocrine-immune alterations. Nutritional countermeasures to maintain GI barrier integrity following exertional-heat stress provide a promising approach to mitigate EHS. The focus of this review is to evaluate: (1) the GI paradigm of exertional heat stroke; (2) techniques to assess GI barrier integrity; (3) typical GI barrier integrity responses to exertional-heat stress; (4) the aetiology of GI barrier integrity loss following exertional-heat stress; and (5) nutritional countermeasures to maintain GI barrier integrity in response to exertional-heat stress.

Tryptophan, glutamine, leucine, and micronutrient supplementation improves environmental enteropathy in Zambian adults: a randomized controlled trial

BACKGROUND

Environmental enteropathy (EE) refers to villus blunting, reduced absorption, and microbial translocation in children and adults in tropical or deprived residential areas. In previous work we observed an effect of micronutrients on villus height (VH).

OBJECTIVE

We aimed to determine, in a randomized controlled trial, if amino acid (AA) or multiple micronutrient (MM) supplementation can improve intestinal structure or barrier dysfunction in Zambian adults with EE.

METHODS

AA (tryptophan, leucine, and glutamine) and/or MM supplements were given for 16 wk in a 2 × 2 factorial comparison against placebo. Primary outcomes were changes in VH, in vivo small intestinal barrier dysfunction assessed by confocal laser endomicroscopy (CLE), and mechanistic (or mammalian) target of rapamycin complex 1 (MTORC1) nutrient responsiveness in lamina propria CD4+ lymphocytes.

RESULTS

Over 16 wk AA, but not MM, supplementation increased VH by 16% (34.5 μm) compared with placebo (P = 0.04). Fluorescein leak, measured by CLE, improved only in those allocated to both AA and MM supplementation. No effect was seen on MTORC1 activation, but posttreatment MTORC1 and VH were correlated (ρ = 0.51; P = 0.001), and change in MTORC1 was correlated with change in VH in the placebo group (ρ = 0.63; P = 0.03). In secondary analyses no effect was observed on biomarkers of microbial translocation. Metabolomic analyses suggest alterations in a number of microbial- and host-derived metabolites including the leucine metabolite β-hydroxy-β-methylbutyrate, which was increased by AA supplementation and correlated with VH.

CONCLUSIONS

In this phase 2 trial, AA supplementation protected against a decline in VH over the supplementation period, and improved barrier function when combined with micronutrients. Leucine and MTORC1 metabolism may be involved in the mechanism of effect. This trial was registered at www.pactr.org as PACTR201505001104412.

Comparative effectiveness of vitamin D supplementation via buccal spray versus oral supplements on serum 25-hydroxyvitamin D concentrations in humans: a systematic review protocol

REVIEW QUESTIONS

The questions of this review are.

Supplementation With Lactoferrin and Lysozyme Ameliorates Environmental Enteric Dysfunction: A Double-Blind, Randomized, Placebo-Controlled Trial

INTRODUCTION

Environmental enteric dysfunction (EED) predisposes children throughout the developing world to high rates of systemic exposure to enteric pathogens and stunting. Effective interventions that treat or prevent EED may help children achieve their full physical and cognitive potential. The objective of this study is to test whether 2 components of breast milk would improve a biomarker of EED and linear growth during the second year of life.

METHODS

A prospective, randomized, double-blind, placebo-controlled clinical trial among children aged 12-23 months was conducted in rural Malawi. The experimental group received a daily supplement of 1.5 g of lactoferrin and 0.2 g of lysozyme for 16 weeks. The primary outcome was an improvement in EED, as measured by the change in the percentage of ingested lactulose excreted into the urine (Δ%L).

RESULTS

Among 214 children who completed the study, there was a significant difference in Δ%L between the control and experimental groups over 8 weeks (an increase of 0.23% vs 0.14%, respectively; P = 0.04). However, this relative improvement was not as strongly sustained over the full 16 weeks of the study (an increase of 0.16% vs 0.11%, respectively; P = 0.17). No difference in linear growth over this short period was observed. The experimental intervention group had significantly lower rates of hospitalization and the development of acute malnutrition during the course of the study (2.5% vs 10.3%, relative risk 0.25; P < 0.02).

DISCUSSION

Supplementation with lactoferrin and lysozyme in a population of agrarian children during the second year of life has a beneficial effect on gut health. This intervention also protected against hospitalization and the development of acute malnutrition, a finding with a significant clinical and public health importance. This finding should be pursued in larger studies with longer follow-up and optimized dosing.

Pathophysiology of environmental enteric dysfunction and its impact on oral vaccine efficacy

Environmental enteric dysfunction (EED) refers to a subclinical disorder of intestinal function common in tropical countries and in settings of poverty and economic disadvantage. The enteropathy that underlies this syndrome is characterized by mucosal inflammation and villus blunting mediated by T cell activation. Epithelial cell disruption and microbial translocation drive systemic inflammation. EED in young children is associated geographically with growth failure, malnutrition, and greatly impaired responses to oral vaccines, notably rotavirus and poliovirus vaccines. In this review, we describe the pathophysiology of EED and examine the evidence linking EED and oral vaccine failure. This evidence is far from conclusive. Although our understanding of EED is still sketchy, there is limited evidence of disturbed innate immunity, B cell disturbances including aggregation into lymphoid follicles, and autoantibody generation. Pathways of T cell activation and the possibility of dendritic cell anergy, which could help explain oral vaccine failure, require further work.

Characterisation of environmental enteropathy biomarkers and associated risk factors in children in the context of a WASH trial in Timor-Leste

Environmental enteropathy (EE) is characterised by subclinical inflammation and hyperpermeability of the small intestine, hypothesised to be caused by recurrent ingestion of faecal bacteria. It has been suggested that EE may be a contributor to malnutrition and growth delays seen in children living in unsanitary conditions. We measured putative faecal EE markers myeloperoxidase (MPO) (ng/mL) and alpha-1-antitrypsin (AAT) (mg/g) in stool samples collected from 133 children aged 1-5 years in 16 communities enrolled in the WASH for WORMS randomised controlled trial in Timor-Leste. Samples were collected two years after a community-wide water, sanitation and hygiene (WASH) intervention that was integrated with regular deworming. Mixed effects multivariable linear regression models were used to examine the impact of the study intervention and of various WASH and infection-related factors on EE biomarkers. Children who lived in communities that received both the WASH intervention and deworming had similar AAT values as those who lived in communities that received only deworming (regression coefficient -0.14, p = 0.583), but they had a trend towards lower MPO values (coeff -0.51, p = 0.055). Younger children showed significantly higher MPO levels (coeff: -0.29, p = 0.002). No WASH variables or parasitic infections were associated with AAT levels. Household water being stored in covered containers was associated with lower MPO levels (coeff -1.75, p = 0.046). We found little evidence that a community-based WASH intervention had an impact on EE over a two-year period.

Impaired Barrier Function and Autoantibody Generation in Malnutrition Enteropathy in Zambia

Intestinal damage in malnutrition constitutes a threat to the survival of many thousands of children globally. We studied children in Lusaka, Zambia, with severe acute malnutrition (SAM) and persistent diarrhea using endoscopy, biopsy and analysis of markers and protective proteins in blood and intestinal secretions. We carried out parallel investigations in apparently healthy adults, and analyzed biomarkers only in apparently healthy children. Villus height and crypt depth did not differ in children with SAM and adult controls, but epithelial surface was reduced in children with SAM (median 445, interquartile range (IQR) 388, 562 μm per 100 μm muscularis mucosae) compared to adults (578, IQR 465,709; P = 0.004). Histological lesions and disruptions of claudin-4 and E-cadherin were most pronounced in children with SAM. Circulating lipopolysaccharide, a marker of bacterial translocation, was higher in malnourished children (251, IQR 110,460 EU/ml) than in healthy children (51, IQR 0,111; P = 0.0001). Other translocation markers showed similar patterns. Anti-Deamidated Gliadin Peptide IgG concentrations, although within the normal range, were higher in children with SAM (median 2.7 U/ml, IQR 1.5–8.6) than in adults (1.6, 1.4–2.1; P = 0.005), and were inversely correlated with villus height (ρ = − 0.79, n = 13, P = 0.001). Malnutrition enteropathy is associated with intestinal barrier failure and immune dysregulation.

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Enteropathy in children with severe acute malnutrition is characterized by variable villus blunting and epithelial disruption.

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Biomarkers indicate very high levels of microbial translocation from intestinal lumen to systemic circulation.

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Coeliac-type autoantibodies were associated with villus blunting, microbial translocation markers and mortality.

There is abundant evidence that childhood malnutrition is a major contributor to mortality in many low and middle income countries. Mortality remains unacceptably high. Here we show that severe acute malnutrition was characterized by very high levels of microbial translocation and inflammation, and severe mucosal damage with disturbed tight junction protein expression. Antibodies to tissue transglutaminase and deamidated gliadin peptides, although within the normal range, correlated with villus morphology, translocation markers and death. Malnutrition enteropathy permits mucosal inflammation, microbial translocation and immune dysregulation.

Infant Nutritional Status, Feeding Practices, Enteropathogen Exposure, Socioeconomic Status, and Illness Are Associated with Gut Barrier Function As Assessed by the Lactulose Mannitol Test in the MAL-ED Birth Cohort

The lactulose mannitol (LM) dual sugar permeability test is the most commonly used test of environmental enteropathy in developing countries. However, there is a large but conflicting literature on its association with enteric infection and host nutritional status. We conducted a longitudinal cohort using a single field protocol and comparable laboratory procedures to examine intestinal permeability in multiple, geographically diverse pediatric populations. Using a previously published systematic review to guide the selection of factors potentially associated with LM test results, we examined the relationships between these factors and mucosal breach, represented by percent lactulose excretion; absorptive area, represented by percent mannitol excretion; and gut barrier function, represented by the L/M ratio. A total of 6,602 LM tests were conducted in 1,980 children at 3, 6, 9, and 15 months old; percent lactulose excretion, percent mannitol excretion, and the L/M ratio were expressed as age- and sex-specific normalized values using the Brazil cohort as the reference population. Among the factors considered, recent severe diarrhea, lower socioeconomic status, and recent asymptomatic enteropathogen infections were associated with decreased percent mannitol excretion and higher L/M ratios. Poorer concurrent weight-for-age, infection, and recent breastfeeding were associated with increased percent lactulose excretion and increased L/M ratios. Our results support previously reported associations between the L/M ratio and factors related to child nutritional status and enteropathogen exposure. These results were remarkably consistent across sites and support the hypothesis that the frequency of these exposures in communities living in poverty leads to alterations in gut barrier function.

Tropical Enteropathies

PURPOSE OF REVIEW

The term 'tropical enteropathy' originated in observations in the 1960s that small intestinal morphology and function differed in the tropics from the norms found in temperate climates. It was subsequently shown that this enteropathy is more closely related to environmental conditions than latitude, and it was re-labelled 'environmental enteropathy'. It is now recognised that environmental enteropathy (also now called environmental enteric dysfunction) has implications for the health and linear growth of children in low- and middle-income countries, and it may underlie poor responses to oral vaccination in these countries. The purpose of this review is to define and clarify this enteropathy despite the confusing terminology it has attracted and to contrast it with other enteropathic states.

RECENT FINDINGS

Recent work has begun to demonstrate the nature of the mucosal lesion and the relationship with microbial translocation which is currently thought to link a failure of mucosal barrier function and the cascade of systemic inflammation which inhibits growth. The evidence is still correlative rather than definitive, but derives some additional support from animal models. There are some common features between environmental enteropathy and other enteropathies, but there are important differences also. The mechanism of the link between enteropathy and vaccine failure is not understood, and neither is it clear how the more severe form of enteropathy, which we refer to as malnutrition enteropathy, is driven by nutrient depletion and intestinal infection. Tropical enteropathies form a group of disorders which include environmental and nutritional enteropathies. The long-term health implications of these disorders for health in low-income countries are just being explored, but the scale of their effects is very large, with millions of people affected.

Causal Pathways from Enteropathogens to Environmental Enteropathy: Findings from the MAL-ED Birth Cohort Study

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Children living in these settings had a high prevalence of enteropathogens, high levels of intestinal inflammation, abnormal intestinal permeability, high markers of systemic inflammation, and postnatal acquired linear growth deficits when compared to children living in the US or Europe

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This study contributes empiric evidence to demonstrate that enteric infection alters both fecal markers of inflammation and permeability

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Current markers of enteropathy fail to account for a large portion of the observed shortfalls in linear growth in these populations, and markers of systemic inflammation appear as the most promising predictive biomarkers for identifying linear growth failure in children

Environmental enteropathy (EE) is hypothesized as a mediator of growth faltering, but few prospective studies have evaluated pathways linking enteropathogen exposure, intestinal inflammation and permeability, and growth. The MAL-ED study represents a novel analytical framework and explicitly evaluates multiple putative EE pathways in combination and using an unprecedented quantity of data. Despite evidence that gut inflammation and altered gut permeability are frequently present and that associations between enteropathogen exposure and gut dysfunction exist, the observed attributable effects of EE on growth faltering in young children were small.

Background

Environmental enteropathy (EE), the adverse impact of frequent and numerous enteric infections on the gut resulting in a state of persistent immune activation and altered permeability, has been proposed as a key determinant of growth failure in children in low- and middle-income populations. A theory-driven systems model to critically evaluate pathways through which enteropathogens, gut permeability, and intestinal and systemic inflammation affect child growth was conducted within the framework of the Etiology, Risk Factors and Interactions of Enteric Infections and Malnutrition and the Consequences for Child Health and Development (MAL-ED) birth cohort study that included children from eight countries.

Methods

Non-diarrheal stool samples (N = 22,846) from 1253 children from multiple sites were evaluated for a panel of 40 enteropathogens and fecal concentrations of myeloperoxidase, alpha-1-antitrypsin, and neopterin. Among these same children, urinary lactulose:mannitol (L:M) (N = 6363) and plasma alpha-1-acid glycoprotein (AGP) (N = 2797) were also measured. The temporal sampling design was used to create a directed acyclic graph of proposed mechanistic pathways between enteropathogen detection in non-diarrheal stools, biomarkers of intestinal permeability and inflammation, systemic inflammation and change in length- and weight- for age in children 0–2 years of age.

Findings

Children in these populations had frequent enteric infections and high levels of both intestinal and systemic inflammation. Higher burdens of enteropathogens, especially those categorized as being enteroinvasive or causing mucosal disruption, were associated with elevated biomarker concentrations of gut and systemic inflammation and, via these associations, indirectly associated with both reduced linear and ponderal growth. Evidence for the association with reduced linear growth was stronger for systemic inflammation than for gut inflammation; the opposite was true of reduced ponderal growth. Although Giardia was associated with reduced growth, the association was not mediated by any of the biomarkers evaluated.

Interpretation

The large quantity of empirical evidence contributing to this analysis supports the conceptual model of EE. The effects of EE on growth faltering in young children were small, but multiple mechanistic pathways underlying the attribution of growth failure to asymptomatic enteric infections had statistical support in the analysis. The strongest evidence for EE was the association between enteropathogens and linear growth mediated through systemic inflammation.

Funding

Bill & Melinda Gates Foundation.

Dynamics and Trends in Fecal Biomarkers of Gut Function in Children from 1-24 Months in the MAL-ED Study

Growth and development shortfalls that are disproportionately prevalent in children living in poor environmental conditions are postulated to result, at least in part, from abnormal gut function. Using data from The Etiology, Risk Factors, and Interactions of Enteric Infections and Malnutrition and the Consequences for Child Health and Development (MAL-ED) longitudinal cohort study, we examine biomarkers of gut inflammation and permeability in relation to environmental exposures and feeding practices. Trends in the concentrations of three biomarkers, myeloperoxidase (MPO), neopterin (NEO), and α-1-antitrypsin (AAT), are described from fecal samples collected during the first 2 years of each child's life. A total of 22,846 stool samples were processed during the longitudinal sampling of 2,076 children 0–24 months of age. Linear mixed models were constructed to examine the relationship between biomarker concentrations and recent food intake, symptoms of illness, concurrent enteropathogen infection, and socioeconomic status. Average concentrations of MPO, NEO, and AAT were considerably higher than published references for healthy adults. The concentration of each biomarker tended to decrease over the first 2 years of life and was highly variable between samples from each individual child. Both MPO and AAT were significantly elevated by recent breast milk intake. All three biomarkers were associated with pathogen presence, although the strength and direction varied by pathogen. The interpretation of biomarker concentrations is subject to the context of their collection. Herein, we identify that common factors (age, breast milk, and enteric infection) influence the concentration of these biomarkers. Within the context of low- and middle-income communities, we observe concentrations that indicate gut abnormalities, but more appropriate reference standards are needed.

Vitamin D3 supplementation in healthy adults: a comparison between capsule and oral spray solution as a method of delivery in a wintertime, randomised, open-label, cross-over study

Vitamin D is typically supplied in capsule form, both in trials and in clinical practice. However, little is known regarding the efficacy of vitamin D administered via oral sprays - a method that primarily bypasses the gastrointestinal absorption route. This study aimed to compare the efficacy of vitamin D3 liquid capsules and oral spray solution in increasing wintertime total 25-hydroxyvitamin D (25(OH)D) concentrations. In this randomised, open-label, cross-over trial, healthy adults (n 22) received 3000 IU (75 µg) vitamin D3 daily for 4 weeks in either capsule or oral spray form. Following a 10-week washout phase, participants received the opposite treatment for a final 4 weeks. Anthropometrics and fasted blood samples were obtained before and after supplementation, with samples analysed for total 25(OH)D, creatinine, intact parathyroid hormone and adjusted Ca concentrations. At baseline, vitamin D sufficiency (total 25(OH)D>50 nmol/l), insufficiency (31-49 nmol/l) and clinical deficiency (<30 nmol/l) were evident in 59, 23 and 18 % of the participants, respectively. Overall, baseline total mean 25(OH)D concentration averaged 59·76 (sd 29·88) nmol/l, representing clinical sufficiency. ANCOVA revealed no significant difference in the mean and standard deviation change from baseline in total 25(OH)D concentrations between oral spray and capsule supplementation methods (26·15 (sd 17·85) v. 30·38 (sd 17·91) nmol/l, respectively; F=1·044, adjusted r 2 0·493, P=0·313). Oral spray vitamin D3 is an equally effective alternative to capsule supplementation in healthy adults.

Assessment of Environmental Enteric Dysfunction in the SHINE Trial: Methods and Challenges

Environmental enteric dysfunction (EED) is a virtually ubiquitous, but poorly defined, disorder of the small intestine among people living in conditions of poverty, which begins early in infancy and persists. EED is characterized by altered gut structure and function, leading to reduced absorptive surface area and impaired intestinal barrier function. It is hypothesized that recurrent exposure to fecal pathogens and changes in the composition of the intestinal microbiota initiate this process, which leads to a self-perpetuating cycle of pathology. We view EED as a primary gut disorder that drives chronic systemic inflammation, leading to growth hormone resistance and impaired linear growth. There is currently no accepted case definition or gold-standard biomarker of EED, making field studies challenging. The Sanitation Hygiene Infant Nutrition Efficacy (SHINE) trial in Zimbabwe is evaluating the independent and combined effects of a package of infant feeding and/or water, sanitation, and hygiene interventions on stunting and anemia. SHINE therefore provides an opportunity to longitudinally evaluate EED in a well-characterized cohort of infants, using a panel of biomarkers along the hypothesized causal pathway. Our aims are to describe the evolution of EED during infancy, ascertain its contribution to stunting, and investigate the impact of the randomized interventions on the EED pathway. In this article, we describe current concepts of EED, challenges in defining the condition, and our approach to evaluating EED in the SHINE trial.

Environmental Enteropathy: Elusive but Significant Subclinical Abnormalities in Developing Countries

Environmental enteropathy/Environmental enteric dysfunction (EE/EED) is a chronic disease of small intestine characterized by gut inflammation and barrier disruption, malabsorption and systemic inflammation in the absence of diarrhea. It is predominantly diseases of children in low income countries and is hypothesized to be caused by continuous exposure to fecally contaminated food, water and fomites. It had not been recognized as a priority health issue because it does not cause overt symptoms and was seen in apparently healthy individuals. However, there is a growing concern of EE/EED because of its impact on longitudinal public health issues, such as growth faltering, oral vaccine low efficacy and poor neurocognitive development. Recent works have provided important clues to unravel its complex pathogenesis, and suggest possible strategies for controlling EE/EED. However, effective diagnostic methods and interventions remain unsettled. Here, we review the existing literature, especially about its pathogenesis, and discuss a solution for children living in the developing world.

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EE/EED is acquired by the close contact with unsanitary condition, and abnormalities of EE/EED are reversible over time.

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EE/EED should be diagnosed as young as possible because poor growth is often evident within 1-2 years of life.

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EE/EED should be diagnosed by simple, noninvasive and low-cost methods, such as fecal biomarkers.

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It is hard to diagnose EE/EED and to predict consequences by a single marker/test due to the complexity in pathogenesis.

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Interventions for EE/EED other than sanitary reform are under investigation although no reports showed favorable outcomes currently.

Diarrheal disease and enteric infections in LMIC communities: how big is the problem?

Studies of enteric diseases have historically focused on observations of clinical diarrhea as a cause of mortality and morbidity. Emerging evidence suggests that diarrhea dramatically underestimates both exposure to enteropathogens and the long-term consequences arising from infection. High burden of pathogens in the gut, even in the absence of diarrhea, is common in infants in low and middle income countries. Continual challenge by pathogens, in conjunction with an inadequate diet stimulates an inflammatory disease that alters the structure of the gut, metabolic and immunological pathways and changes the microbiome. Both diarrhea and enteropathogen infection have been associated with reduced growth, reduced cognitive development, and reduced vaccine efficacy suggesting that the burden of diarrheal disease is dramatically underestimated.

Preventing environmental enteric dysfunction through improved water, sanitation and hygiene: an opportunity for stunting reduction in developing countries

In 2011, one in every four (26%) children under 5 years of age worldwide was stunted. The realization that most stunting cannot be explained by poor diet or by diarrhoea, nor completely reversed by optimized diet and reduced diarrhoea has led to the hypothesis that a primary underlying cause of stunting is subclinical gut disease. Essentially, ingested microbes set in motion two overlapping and interacting pathways that result in linear growth impairment. Firstly, partial villous atrophy results in a reduced absorptive surface area and loss of digestive enzymes. This in turn results in maldigestion and malabsorption of much needed nutrients. Secondly, microbes and their products make the gut leaky, allowing luminal contents to translocate into systemic circulation. This creates a condition of chronic immune activation, which (i) diverts nutrient resources towards the metabolically expensive business of infection fighting rather than growth; (ii) suppresses the growth hormone‐IGF axis and inhibits bone growth, leading to growth impairment; and (iii) causes further damage to the intestinal mucosa thereby exacerbating the problem. As such, the unhygienic environments in which infants and young children live and grow must contribute to, if not be the overriding cause of, this environmental enteric dysfunction. We suggest that a package of baby‐WASH interventions (sanitation and water improvement, handwashing with soap, ensuring a clean play and infant feeding environment and food hygiene) that interrupt specific pathways through which feco‐oral transmission occurs in the first two years of a child's life may be central to global stunting reduction efforts.

Environmental enteric dysfunction: an overview

BACKGROUND

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. Understanding of EED and its possible consequences for health is currently limited.

OBJECTIVE

A narrative review of the current understanding of EED: epidemiology, pathogenesis, therapies, and relevance to child health.

METHODS

Searches for key papers and ongoing trials were conducted using PUBMED 1966-June 2014; ClinicalTrials.gov; the WHO Clinical Trials Registry; the Cochrane Library; hand searches of the references of retrieved literature; discussions with experts; and personal experience from the field.

RESULTS

EED is established during infancy and is associated with poor sanitation, certain gut infections, and micronutrient deficiencies. Helicobacter pylori infection, small intestinal bacterial overgrowth (SIBO), abnormal gut microbiota, undernutrition, and toxins may all play a role. EED is usually asymptomatic, but it is important due to its association with stunting. Diagnosis is frequently by the dual sugar absorption test, although other biomarkers are emerging. EED may partly explain the reduced efficacy of oral vaccines in low- and middle-income countries and the increased risk of serious infection seen in children with undernutrition.

CONCLUSIONS

Despite its potentially significant impacts, it is currently unclear exactly what causes EED and how it can be treated or prevented. Ongoing trials involve nutritional supplements, water and sanitation interventions, and immunomodulators. Further research is needed to better understand this condition, which is of likely crucial importance for child health and development in low- and middle-income settings.

Fecal Markers of Environmental Enteropathy are Associated with Animal Exposure and Caregiver Hygiene in Bangladesh

Undernutrition is estimated to be an underlying cause of over half of all deaths in young children globally. There is a growing body of literature suggesting that increased exposure to enteric pathogens is responsible for environmental enteropathy (EE), a disorder associated with impaired growth in children. To determine if household unsanitary environmental conditions were significantly associated with EE and stunting in children, we conducted a cohort of 216 children (≤ 30 months) in rural Bangladesh. Stool was analyzed for four fecal markers of EE: alpha-1-antitrypsin, myeloperoxidase, and neopterin combined to form an EE disease activity score, and calprotectin. We observed a significant association between having an animal corral in a child's sleeping room and elevated EE scores (1.0 point difference, 95% confidence interval [CI]: 0.13, 1.88) and a two times higher odds of stunting (height-for-age z-score < -2) (odds ratio [OR]: 2.53, 95% CI: 1.08, 5.43) after adjusting for potential confounders. In addition, children of caregivers with visibly soiled hands had significantly elevated fecal calprotectin (μg/g) (384.1, 95% CI: 152.37, 615.83). These findings suggest that close contact with animals and caregiver hygiene may be important risk factors for EE in young children. These findings are consistent with the hypothesis that unsanitary environmental conditions can lead to EE in susceptible pediatric populations.

Multiple micronutrient supplementation transiently ameliorates environmental enteropathy in Malawian children aged 12-35 months in a randomized controlled clinical trial

BACKGROUND

Environmental enteropathy (EE) is subclinical, diffuse villous atrophy characterized by T cell infiltration of the small intestinal mucosa associated with nutrient malabsorption and stunting. EE is assessed by the lactulose:mannitol (L:M) test, whereby nonmetabolized sugars are ingested and quantified in the urine. Multiple micronutrient (MN) deficiency morphologically mimics EE, and ω-3 (n-3) polyunsaturated fatty acids reduce mucosal inflammation in Crohn disease.

OBJECTIVE

We tested the hypothesis that supplementary MNs, with or without fish oil (FO), would improve L:M in rural Malawian children aged 1-3 y compared with a control (C) group receiving a placebo.

METHODS

The MNs and FO provided the Recommended Dietary Intake for 26 vitamins, minerals, eicosapentaenoic acid, and docosahexaenoic acid. This was a 3-arm, randomized, double-blind, placebo-controlled clinical trial, with the primary outcomes being the change in L:M (ΔL:M) after 12 and 24 wk of supplementation. Comparisons were made for ΔL:M after 12 and 24 wk within each group by using a Wilcoxon matched pairs signed rank test, because the data are not normally distributed.

RESULTS

A total of 230 children had specimens adequate for analysis; all had an abnormal baseline L:M, defined as >0.10. After 12 wk, children who received MNs + FO had a ΔL:M [mean (95% CI)] of -0.10 (-0.04, -0.15; P = 0.001), and children receiving only MNs had ΔL:M of -0.12 (-0.03, -0.21; P = 0.002). After 24 wk, children who received MNs + FO had a ΔL:M of -0.09 (-0.03, -0.15; P = 0.001); children receiving only MNs had a ΔL:M of -0.11 (-0.02, -0.20; P = 0.001), and the C group had ΔL:M of -0.07 (0.02, -0.16); P = 0.002). Linear growth was similar in all groups, ∼4.3 cm over 24 wk.

CONCLUSION

Although the effect was modest, these data suggest MNs can transiently ameliorate EE in rural African children. The trial was registered at clinicaltrials.gov as NCT01593033.

Noncommunicable diseases in HIV infection in low- and middle-income countries: gastrointestinal, hepatic, and nutritional aspects

The purpose of this review was to outline the interaction between HIV and noncommunicable diseases affecting the gastrointestinal (GI) tract, liver, and nutritional disorders in low- and middle-income countries (LMICs), and to identify research priorities. Noncommunicable GI tract disorders are only moderately influenced by HIV, and peptic ulceration is actually less common. However, the impact of HIV on GI cancers needs further investigation. HIV interacts strongly with environmental enteropathy, exacerbating malabsorption of nutrients and drugs. HIV has 2 major effects on noncommunicable liver disease: drug-induced liver injury and nonalcoholic fatty liver disease (particularly in persons of African genetic descent). The effect of HIV on nutrition was one of the first markers of the epidemic in the 1980s, and HIV continues to have major nutritional consequences. Childhood malnutrition and HIV frequently coexist in some regions, for example, southern Africa, resulting in powerful negative interactions with poorer responses to standard nutritional rehabilitation. HIV and nutritional care need to be better integrated, but many questions on how best to do this remain unanswered. Across the spectrum of GI, hepatic, and nutritional disorders in HIV infection, there is increasing evidence that the microbiome may play an important role in disease pathogenesis, but work in this area, especially in low- and middle-income countries, is in its infancy.

Zinc deficiency in children with environmental enteropathy-development of new strategies: report from an expert workshop

Zinc deficiency is a major cause of childhood morbidity and mortality. The WHO/UNICEF strategy for zinc supplementation as adjunctive therapy for diarrhea is poorly implemented. A conference of experts in zinc nutrition and gastrointestinal disorders was convened to consider approaches that might complement the current recommendation and what research was needed to develop these approaches. Several key points were identified. The design of novel zinc interventions would be facilitated by a better understanding of how disturbed gut function, such as environmental (or tropical) enteropathy, affects zinc absorption, losses, and homeostasis. Because only 10% of zinc stores are able to be rapidly turned over, and appear to be rapidly depleted by acute intestinal illness, they are probably best maintained by complementary regular supplementation in a primary prevention strategy rather than secondary prevention triggered by acute diarrhea. The assessment of zinc status is challenging and complex without simple, validated measures to facilitate field testing of novel interventions. Zinc bioavailability may be a crucial factor in the success of primary prevention strategies, and a range of options, all still inadequately explored, might be valuable in improving zinc nutrition. Some therapeutic actions of zinc on diarrhea seem attributable to pharmacologic effects, whereas others are related to the reversal of deficiency (ie, nutritional). The distinction between these 2 mechanisms cannot be clarified given the insensitivity of serum zinc to identify subclinical deficiency states. Why zinc seems to be less effective than expected at all ages, and ineffective for secondary prevention of diarrhea in children <12 mo of age, remains unclear. It was concluded that a reframing of the current recommendation is warranted with consideration of how to better optimize and deliver zinc and whether to provide a complementary public health primary prevention zinc strategy. This requires careful consideration of the zinc product to be used as well as strategies for its delivery.

Geographic variation in the eukaryotic virome of human diarrhea

Little is known about the population of eukaryotic viruses in the human gut (“virome”) or the potential role it may play in disease. We used a metagenomic approach to define and compare the eukaryotic viromes in pediatric diarrhea cohorts from two locations (Melbourne and Northern Territory, Australia). We detected viruses known to cause diarrhea, non-pathogenic enteric viruses, viruses not associated with an enteric reservoir, viruses of plants, and novel viruses. Viromes from Northern Territory children contained more viral families per sample than viromes from Melbourne, which could be attributed largely to an increased number of sequences from the families Adenoviridae and Picornaviridae (genus enterovirus). qRT-PCR/PCR confirmed the increased prevalence of adenoviruses and enteroviruses. Testing of additional diarrhea cohorts by qRT-PCR/PCR demonstrated statistically different prevalences in different geographic sites. These findings raise the question of whether the virome plays a role in enteric diseases and conditions that vary with geography.

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22 different viral families detected in pediatric diarrhea.

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More viral families in diarrhea from Northern Territory than diarrhea from Melbourne.

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Adenoviridae and Picornaviridae more common in Northern Territory than in Melbourne.

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qRT-PCR/PCR confirmed the increased prevalence of adenoviruses and enteroviruses.

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Viromes in patients with diarrhea differ between two different geographic sites.

Zinc or albendazole attenuates the progression of environmental enteropathy: a randomized controlled trial

BACKGROUND & AIMS

Environmental enteropathy (EE) is a subclinical condition among children in the developing world, characterized by T-cell infiltration of the small-bowel mucosa and diffuse villous atrophy. EE leads to macronutrient and micronutrient malabsorption and stunting, with a resultant increased risk for infection and reduced cognitive development. We tested the hypothesis that zinc and albendazole treatments would reduce the severity of EE in rural African children.

METHODS

In a randomized, double-blind, placebo-controlled trial in rural southern Malawi, asymptomatic children, 1 to 3 years old and at high risk for EE, received either a single dose of albendazole, a 14-day course of 20 mg zinc sulfate, or a placebo. Subjects were given the dual-sugar absorption test, and the ratio of lactulose to mannitol (L:M) in urine was used to determine the severity of EE at baseline and 34 days after completion of the assigned regimen. The primary outcome was the change in the L:M.

RESULTS

A complete set of urine samples was obtained from 222 of 234 children enrolled and analyzed. The mean baseline L:M was 0.32 ± 0.18 among all children and did not differ among groups (normal L:M range, <0.12). At the end of the study, the L:M ratio had increased more in the placebo group (0.12 ± 0.31) than in the zinc group (0.03 ± 0.20; P < .03) or the albendazole group (0.04 ± 0.22; P < .04).

CONCLUSIONS

Treatment with zinc or albendazole protects against a significant increase in the L:M ratio, a biomarker for EE, in asymptomatic rural Malawian children. These findings could provide insight into the etiology and pathogenesis of EE. Clinicaltrials.gov Number: NCT01440608.

Seroepidemiology of hepatitis E virus infection in an urban population in Zambia: strong association with HIV and environmental enteropathy

BACKGROUND

Hepatitis E virus (HEV) infection causes major epidemics of infectious hepatitis, with high mortality rates in pregnant women. Recent reports indicate that HEV coinfections with human immunodeficiency virus (HIV) may have a more protracted course. However, the impact of HEV infections in communities heavily affected by HIV remains poorly studied. We set out to examine age-related seroprevalence in a community where we have previously carried out studies on environmental enteropathy.

METHODS

Blood samples from 194 children and 106 adults were examined for immunoglobulin G and immunoglobulin M antibodies for HEV. HEV data were correlated with HIV status and morphometric analysis of small intestinal biopsies.

RESULTS

Seroprevalence rose throughout childhood, from 8% in children aged 1-4 years, to 36% in children aged 10-14 years. In adults, the overall prevalence was 42%, with 28% in HIV-seronegative adults and 71% in HIV-seropositive adults (odds ratio, 6.2; 95% confidence interval, 2.2-18; P = .0001). In adults, villous height and crypt depth measurements showed that HEV seropositivity was associated with worse enteropathy (P = .05 and P = .005, respectively).

CONCLUSIONS

HEV infection is common in Zambia. In adults it is strongly associated with HIV status, and also with environmental enteropathy.

Stunting is characterized by chronic inflammation in Zimbabwean infants

BACKGROUND

Stunting affects one-third of children in developing countries, but the causes remain unclear. We hypothesized that enteropathy leads to low-grade inflammation, which suppresses the growth hormone-IGF axis and mediates stunting.

METHODS

We conducted a case-control study of 202 HIV-unexposed Zimbabwean infants who were stunted (height-for-age Z-score (HAZ) <-2; cases) or non-stunted (HAZ >-0.5; controls) at 18 months. We measured biomarkers of intestinal damage (I-FABP), inflammation (CRP, AGP, IL-6) and growth hormone-IGF axis (IGF-1, IGFBP3) in infant plasma at 6 weeks and 3, 6, 12 and 18 months, and in paired maternal-infant plasma at birth. Adjusted mean differences between biomarkers were estimated using regression models. Multivariate odds ratios of stunting were estimated by logistic regression.

RESULTS

At birth, cases were shorter (median (IQR) HAZ -1.00 (-1.53, -0.08) vs 0.03 (-0.57, 0.62,); P<0.001) than controls and their mothers had lower levels of IGF-1 (adjusted mean difference (95%CI) -21.4 (-39.8, -3.1) ng/mL). From 6 weeks to 12 months of age, levels of CRP and AGP were consistently higher and IGF-1 and IGFBP3 lower in cases versus controls; IGF-1 correlated inversely with inflammatory markers at all time-points. I-FABP increased between 3-12 months, indicating extensive intestinal damage during infancy, which was similar in cases and controls. In multivariate analysis, higher log10 levels of CRP (aOR 3.06 (95%CI 1.34, 6.99); P = 0.008) and AGP (aOR 7.87 (95%CI 0.74, 83.74); P = 0.087) during infancy were associated with stunting. There were no associations between levels of I-FABP, IL-6, sCD14 or EndoCAb and stunting.

CONCLUSIONS

Stunting began in utero and was associated with low maternal IGF-1 levels at birth. Inflammatory markers were higher in cases than controls from 6 weeks of age and were associated with lower levels of IGF-1 throughout infancy. Higher levels of CRP and AGP during infancy were associated with stunting. These findings suggest that an extensive enteropathy occurs during infancy and that low-grade chronic inflammation may impair infant growth.

Interactions between zinc deficiency and environmental enteropathy in developing countries

Zinc deficiency affects one-fifth of the world's population and leads to substantial morbidity and mortality. Environmental enteropathy (EE), a subclinical pathology of altered intestinal morphology and function, is almost universal among people living in developing countries and affects long-term growth and health. This review explores the overlapping nature of these 2 conditions and presents evidence for their interaction. EE leads to impaired zinc homeostasis, predominantly due to reduced absorptive capacity arising from disturbed intestinal architecture, and zinc deficiency exacerbates several of the proposed pathways that underlie EE, including intestinal permeability, enteric infection, and chronic inflammation. Ongoing zinc deficiency likely perpetuates the adverse outcomes of EE by worsening malabsorption, reducing intestinal mucosal immune responses, and exacerbating systemic inflammation. Although the etiology of EE is predominantly environmental, zinc deficiency may also have a role in its pathogenesis. Given the impact of both EE and zinc deficiency on morbidity and mortality in developing countries, better understanding the relation between these 2 conditions may be critical for developing combined interventions to improve child health.

Household environmental conditions are associated with enteropathy and impaired growth in rural Bangladesh

We assessed the relationship of fecal environmental contamination and environmental enteropathy. We compared markers of environmental enteropathy, parasite burden, and growth in 119 Bangladeshi children (≤ 48 months of age) across rural Bangladesh living in different levels of household environmental cleanliness defined by objective indicators of water quality and sanitary and hand-washing infrastructure. Adjusted for potential confounding characteristics, children from clean households had 0.54 SDs (95% confidence interval [CI] = 0.06, 1.01) higher height-for-age z scores (HAZs), 0.32 SDs (95% CI = -0.72, 0.08) lower lactulose:mannitol (L:M) ratios in urine, and 0.24 SDs (95% CI = -0.63, 0.16) lower immunoglobulin G endotoxin core antibody (IgG EndoCAb) titers than children from contaminated households. After adjusting for age and sex, a 1-unit increase in the ln L:M was associated with a 0.33 SDs decrease in HAZ (95% CI = -0.62, -0.05). These results are consistent with the hypothesis that environmental contamination causes growth faltering mediated through environmental enteropathy.

Detection of low-concentration host mRNA transcripts in Malawian children at risk for environmental enteropathy

BACKGROUND AND OBJECTIVE

Transcriptomic analysis of fecal samples is an emerging method for the diagnosis of gastrointestinal pathology because it is noninvasive and requires minute volumes of analyte; however, detection of mRNA in low copy numbers in human stool is challenging. Our objective was to develop a method for detecting human mRNA suggestive of environmental enteropathy (EE) in feces.

METHODS

Stool samples from 70 Malawian children, 34 without EE and 36 with EE, as defined by dual sugar absorption, were used to develop the methodology for mRNA detection. Multiple RNA isolation techniques and polymerase chain reaction formats were tested to detect 38 potential mRNA biomarkers suggestive of EE, and the results compared.

RESULTS

RNA isolation using magnetic bead extraction best recovered host mRNA in stool, and digital droplet polymerase chain reaction was the most sensitive format to detect low copy numbers of mRNA. In all of the 70 samples, >20 copies of glyceraldehyde-3-phosphate dehydrogenase/200 mg of stool were detected. Copy numbers of potential biomarkers were normalized to glyceraldehyde-3-phosphate dehydrogenase, to account for interspecimen differences in concentration of human mRNA. Of the 38 transcripts chosen for initial evaluation, 24 had copy numbers >10 in all of the samples tested. Of the 6 potential markers measured in all of the 70 samples, REG4 best differentiated children with and without EE.

CONCLUSIONS

A reproducible and reliable method to quantify human mRNA in stool present in low copy numbers has been developed, and may prove useful in investigations of EE and possibly other inflammatory gut conditions.

Long-chain PUFA supplementation in rural African infants: a randomized controlled trial of effects on gut integrity, growth, and cognitive development

BACKGROUND

Intestinal damage and malabsorption caused by chronic environmental enteropathy are associated with growth faltering seen in infants in less-developed countries. Evidence has suggested that supplementary omega-3 (n-3) long-chain PUFAs (LC-PUFAs) might ameliorate this damage by reducing gastrointestinal inflammation. LC-PUFA supplementation may also benefit cognitive development.

OBJECTIVE

We tested whether early n-3 LC-PUFA supplementation improves infant intestinal integrity, growth, and cognitive function.

DESIGN

A randomized, double-blind, controlled trial [200 mg DHA and 300 mg EPA or 2 mL olive oil/d for 6 mo] was conducted in a population of 172 rural Gambian infants aged 3-9 mo. The primary endpoints were anthropometric measures and gut integrity [assessed by using urinary lactulose:mannitol ratios (LMRs)]. Plasma fatty acid status, intestinal mucosal inflammation (fecal calprotectin), daily morbidity, and cognitive development (2-step means-end test and an attention assessment) were secondary endpoints.

RESULTS

PUFA supplementation resulted in a significant increase in plasma n-3 LC-PUFA concentrations (P < 0.001 for both DHA and EPA) and midupper arm circumference (MUAC) (effect size: 0.31 z scores; 95% CI: 0.06, 0.56; P = 0.017) at 9 mo of age. At 12 mo, MUAC remained greater in the intervention group, and we observed significant increases in skinfold thicknesses (P ≤ 0.022 for all). No other significant differences between treatment groups were detected for growth or LMRs at 9 mo or for secondary outcomes.

CONCLUSIONS

Fish-oil supplementation successfully increased plasma n-3 fatty acid status. However, in young, breastfed Gambian infants, the intervention failed to improve linear growth, intestinal integrity, morbidity, or selected measures of cognitive development. The trial was registered at www.isrctn.org as ISRCTN66645725.

Abnormal gut integrity is associated with reduced linear growth in rural Malawian children

The aim of the present study was to investigate the relation of environmental enteropathy, as measured by the dual sugar absorption test, to linear growth faltering in 2- to 5-year-old Malawian children. Dietary quality, food insecurity, anthropometry, and site-specific sugar testing were measured in 418 children, and anthropometry was reassessed 3 months later. A linear regression model predicting linear growth was created. Better growth was associated with less urinary lactulose excretion, more clean water usage, not sleeping with animals, and no previous history of malnutrition. Eighty-seven percent of children studied demonstrated evidence of environmental enteropathy. In conclusion, abnormal gut integrity is associated with reduced linear growth in a population of rural African preschool-age children.

Polyethylene glycol versus dual sugar assay for gastrointestinal permeability analysis: is it time to choose?

Background

Increased intestinal permeability is an important measure of disease activity and prognosis. Currently, many permeability tests are available and no consensus has been reached as to which test is most suitable. The aim of this study was to compare urinary probe excretion and accuracy of a polyethylene glycol (PEG) assay and dual sugar assay in a double-blinded crossover study to evaluate probe excretion and the accuracy of both tests.

Methods

Gastrointestinal permeability was measured in nine volunteers using PEG 400, PEG 1500, and PEG 3350 or lactulose-rhamnose. On 4 separate days, permeability was analyzed after oral intake of placebo or indomethacin, a drug known to increase intestinal permeability. Plasma intestinal fatty acid binding protein and calprotectin levels were determined to verify compromised intestinal integrity after indomethacin consumption. Urinary samples were collected at baseline, hourly up to 5 hours after probe intake, and between 5 and 24 hours. Urinary excretion of PEG and sugars was determined using high-pressure liquid chromatography-evaporative light scattering detection and liquid chromatography-mass spectrometry, respectively.

Results

Intake of indomethacin increased plasma intestinal fatty acid-binding protein and calprotectin levels, reflecting loss of intestinal integrity and inflammation. In this state of indomethacin-induced gastrointestinal compromise, urinary excretion of the three PEG probes and lactulose increased compared with placebo. Urinary PEG 400 excretion, the PEG 3350/PEG 400 ratio, and the lactulose/rhamnose ratio could accurately detect indomethacin-induced increases in gastrointestinal permeability, especially within 2 hours of probe intake.

Conclusion

Hourly urinary excretion and diagnostic accuracy of PEG and sugar probes show high concordance for detection of indomethacin-induced increases in gastrointestinal permeability. This comparative study improves our knowledge of permeability analysis in man by providing a clear overview of both tests and demonstrates equivalent performance in the current setting.