Effect of Lactobacillus GG on intestinal integrity in Malawian children at risk of tropical enteropathy

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 the gut microbiota of rural Malawian children: An observational study

Environmental enteric dysfunction (EED) is a subclinical condition of the gut characterized by changes in morphology and function with underlying chronic inflammatory responses. This study characterized composition and diversity of the gut microbiota in rural Malawian children with and without signs of EED. Fecal samples were collected from children aged 1-59 months. Neopterin, myeloperoxidase and alpha-1 antitrypsin concentrations were quantified by ELISA and combined to form a composite EED score using principal component analysis. DNA was extracted from fecal samples and V4-16S rRNA gene sequencing was used to characterize the gut microbiota. The concentrations of all three biomarkers decreased with increasing age, which is consistent with other studies of children living in similar low-income settings. Firmicutes, Bacteroidetes, Proteobacteria and Actinobacteria were the dominant phyla while Faecalibacterium and Bifidobacterium were the most prevalent genera. Increased alpha diversity was associated with a reduction in neopterin concentration. Microbiota composition was different between fecal samples with low and high composite EED scores; increased abundance of Succinivibrio was associated with reduced composite EED scores.

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.

The effect of bovine colostrum/egg supplementation compared with corn/soy flour in young Malawian children: a randomized, controlled clinical trial

BACKGROUND

Bovine colostrum with egg powder (BC/egg) is rich in essential amino acids and immunoactive compounds.

OBJECTIVES

This trial tested the hypothesis that a daily supplement of BC/egg would reduce linear growth faltering and environmental enteric dysfunction (EED) in Malawian infants when compared with an isoenergetic ration of corn/soy flour used as a control. EED was defined by a lactulose permeability test.

METHODS

This was a prospective, randomized, blinded, placebo-controlled clinical trial in which 9-mo-old infants received BC/egg or a control for 3 mo. The primary outcomes were change in length-for-age z-score (ΔLAZ) and urinary lactulose excretion (%L) at 12-mo-old. Secondary outcomes included episodes of diarrhea, stunting, EED, and the 16S configuration of the fecal microbiota.

RESULTS

Of the 277 children enrolled, 267 completed the intervention phase of the study. LAZ decreased in all children from 9 to 17 mo, although ΔLAZ was less in children receiving BC/egg from 9 to 12 mo (difference = 0.12 z-scores; P = 0.0011). This difference persisted after feeding was completed, with less ΔLAZ (difference = 0.09 z-scores). A lower prevalence of stunting was seen in the intervention group (n = 47/137) than the control group (n = 62/127) at 17 mo (RR = 0.70; 95% CI: 0.52, 0.94).The median %L at 12 mo of age in the children receiving BC/egg was 0.14%, compared with 0.17% in the control group (P = 0.74). In children with %L >0.45% at enrollment (severe EED), the BC/egg group had more children with normal %L at 12 mo of age (10/20, 50%) than was seen in controls (2/15, 13%; P = 0.024). Episodes of diarrhea and β-diversity of the 16S configuration of fecal microbiota did not differ between the 2 groups.

CONCLUSIONS

Addition of BC/egg to complementary feeding in Malawian infants resulted in less linear growth faltering. This trial was registered at clinicaltrials.gov as NCT03801317.

Growth faltering regardless of chronic diarrhea is associated with mucosal immune dysfunction and microbial dysbiosis in the gut lumen

Despite the impact of childhood diarrhea on morbidity and mortality, our understanding of its sequelae has been significantly hampered by the lack of studies that examine samples across the entire intestinal tract. Infant rhesus macaques are naturally susceptible to human enteric pathogens and recapitulate the hallmarks of diarrheal disease such as intestinal inflammation and growth faltering. Here, we examined intestinal biopsies, lamina propria leukocytes, luminal contents, and fecal samples from healthy infants and those experiencing growth faltering with distant acute or chronic active diarrhea. We show that growth faltering in the presence or absence of active diarrhea is associated with a heightened systemic and mucosal pro-inflammatory state centered in the colon. Moreover, polyclonal stimulation of colonic lamina propria leukocytes resulted in a dampened cytokine response, indicative of immune exhaustion. We also detected a functional and taxonomic shift in the luminal microbiome across multiple gut sites including the migration of Streptococcus and Prevotella species between the small and large intestine, suggesting a decompartmentalization of gut microbial communities. Our studies provide valuable insight into the outcomes of diarrheal diseases and growth faltering not attainable in humans and lays the groundwork to test interventions in a controlled and reproducible setting.

The effect of legume supplementation on the gut microbiota in rural Malawian infants aged 6 to 12 months

BACKGROUND

Common bean and cowpea contain about 25% protein and 25% fiber, and are recommended as complementary foods in sub-Saharan Africa.

OBJECTIVE

The objective of this study was to determine if a daily legume supplement given to Malawian infants aged 6 to 12 mo alters the 16S configuration of the fecal microbiota as read out by amplicon sequence variants (ASVs).

METHODS

This study was conducted within the context of a randomized, double-blind, controlled clinical trial to assess whether cowpea or common bean supplementation reduced intestinal permeability or increased linear growth. There were 2 village clusters in which the study was conducted. Fresh stool collections were flash frozen from 236 infants at ≤6 time points. The stools were sequenced using Earth Microbiome project protocols and data were processed using Qiime and Qiita, open-source, validated software packages. α-diversity was measured using the Faith's test. The 16S configuration was characterized by determining the weighted UniFrac distances of the ASVs and comparing them using permutational multivariate ANOVA.

RESULTS

Among the 1249 samples analyzed, the α-diversity of the fecal microbiome was unchanged among subjects after initiation of legume supplementation. Neither cowpea nor common bean altered the overall 16S configuration at any age. The 16S configuration differed between children with adequate and poor linear growth aged from 6 to 9 mo, but no specific ASVs differed in relative abundance. The 16S configuration differed between children with normal and abnormal intestinal permeability at 9 mo, but no specific ASVs differed in relative abundance. Among categorical characteristics of the population associated with different 16S configurations, village cluster was most pronounced.

CONCLUSION

Legume supplementation in breastfed, rural African infants did not affect the structure of the gut microbial communities until the children were aged 9 mo. This trial was registered at clinicaltrials.gov as NCT02472262.

High prevalence of selected viruses and parasites and their predictors in Malawian children

Enteric pathogens have been related to child undernutrition. Whereas there are lots of data on enteric bacterial microbiota and infections, much less is known about the incidence of prevalence of intestinal colonisation with viruses or important parasitic species. This study assessed the presence of selected viruses and parasites in stools of 469, 354, 468 Malawian children at 6, 12 and 18 months. We also assessed environmental predictors of the presence of viruses and parasites among 6-month infants. Microbial presence was documented using real-time polymerase chain reaction (PCR). Enteroviruses were identified in 68%, 80% and 81% of the stool samples at 6, 12 and 18 months children, rhinovirus in 28%, 18% and 31%, norovirus in 24%, 22% and 16%, parechovirus in 23%, 17% and 17%, rotavirus in 3%, 1% and 0.6%, Giardia lamblia in 9.6%, 23.5% and 26%, and Cryptosporidium (spp.) in 6%, 8% and 2% of the 6, 12 and 18 months stool samples. Dry season (May–October) was associated with a low infection rate of enterovirus, norovirus and Cryptosporidium (spp.). Higher father's education level, less number of person in the household and higher sanitation were associated with a low infection rate of enterovirus, norovirus and rotavirus, respectively. The results suggest that the prevalence of asymptomatic viral and parasitic infections is high among Malawian children and that the family's living conditions and seasonality influence the rate of infections.

Effects of improved water, sanitation, and hygiene and improved complementary feeding on environmental enteric dysfunction in children in rural Zimbabwe: A cluster-randomized controlled trial

Background

Environmental enteric dysfunction (EED) may be an important modifiable cause of child stunting. We described the evolution of EED biomarkers from birth to 18 months in rural Zimbabwe and tested the independent and combined effects of improved water, sanitation, and hygiene (WASH), and improved infant and young child feeding (IYCF), on EED.

Methodology and findings

The Sanitation Hygiene Infant Nutrition Efficacy (SHINE) trial was a 2x2 factorial cluster-randomised trial of improved IYCF and improved WASH on child stunting and anaemia at 18 months of age. 1169 infants born to HIV-negative mothers provided plasma and faecal specimens at 1, 3, 6, 12, and 18 months of age. We measured EED biomarkers that reflect all domains of the hypothesized pathological pathway. Markers of intestinal permeability and intestinal inflammation declined over time, while markers of microbial translocation and systemic inflammation increased between 1–18 months. Markers of intestinal damage (I-FABP) and repair (REG-1β) mirrored each other, and citrulline (a marker of intestinal epithelial mass) increased from 6 months of age, suggesting dynamic epithelial turnover and regeneration in response to enteric insults. We observed few effects of IYCF and WASH on EED after adjustment for multiple comparisons. The WASH intervention decreased plasma IGF-1 at 3 months (β:0.89, 95%CI:0.81,0.98) and plasma kynurenine at 12 months (β: 0.92, 95%CI:0.87,0.97), and increased plasma IGF-1 at 18 months (β:1.15, 95%CI:1.05,1.25), but these small WASH effects did not translate into improved growth.

Conclusions

Overall, we observed dynamic trends in EED but few effects of IYCF or WASH on biomarkers during the first 18 months after birth, suggesting that these interventions did not impact EED. Transformative WASH interventions are required to prevent or ameliorate EED in low-income settings.

Child stunting remains a global health challenge rooted in an intergenerational cycle of poor health, reduced neurodevelopment and poverty. Environmental enteric dysfunction (EED) is an acquired condition of the small intestine likely resulting from frequent faecal-oral microbial exposure, which is hypothesized to underlie stunting. We found dynamic changes in EED biomarkers between 1 and 18 months of age in a cohort of rural Zimbabwean infants, suggesting a complex developmental period of intestinal maturation, adaptation and response to environmental insults. Randomized improved infant and young child feeding, and improved water, sanitation and hygiene (WASH) interventions had no meaningful impact on EED. Greater investment in transformative WASH is needed to prevent EED in low-income countries.

Environmental enteric dysfunction: a review of potential mechanisms, consequences and management strategies

BACKGROUND

Environmental enteric dysfunction (EED) is an acquired enteropathy of the small intestine, characterized by enteric inflammation, villus blunting and decreased crypt-to-villus ratio. EED has been associated with poor outcomes, including chronic malnutrition (stunting), wasting and reduced vaccine efficacy among children living in low-resource settings. As a result, EED may be a valuable interventional target for programs aiming to reduce childhood morbidity in low and middle-income countries.

MAIN TEXT

Several highly plausible mechanisms link the proposed pathophysiology underlying EED to adverse outcomes, but causal attribution of these pathways has proved challenging. We provide an overview of recent studies evaluating the causes and consequences of EED. These include studies of the role of subclinical enteric infection as a primary cause of EED, and efforts to understand how EED-associated systemic inflammation and malabsorption may result in long-term morbidity. Finally, we outline recently completed and upcoming clinical trials that test novel interventions to prevent or treat this highly prevalent condition.

CONCLUSIONS

Significant strides have been made in linking environmental exposure to enteric pathogens and toxins with EED, and in understanding the multifactorial mechanisms underlying this complex condition. Further insights may come from several ongoing and upcoming interventional studies trialing a variety of novel management strategies.

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.

Unsafe Drinking Water Is Associated with Environmental Enteric Dysfunction and Poor Growth Outcomes in Young Children in Rural Southwestern Uganda

Environmental enteric dysfunction (EED), a subclinical disorder of the small intestine, and poor growth are associated with living in poor water, sanitation, and hygiene (WASH) conditions, but specific risk factors remain unclear. Nested within a birth cohort study, this study investigates relationships among water quality, EED, and growth in 385 children living in southwestern Uganda. Water quality was assessed using a portable water quality test when children were 6 months, and safe water was defined as lacking Escherichia coli contamination. Environmental enteric dysfunction was assessed using the lactulose:mannitol (L:M) test at 12-16 months. Anthropometry and covariate data were extracted from the cohort study, and associations were assessed using linear and logistic regression models. Less than half of the households (43.8%) had safe water, and safe versus unsafe water did not correlate with improved versus unimproved water source. In adjusted linear regression models, children from households with safe water had significantly lower log-transformed (ln) L:M ratios (β: -0.22, 95% confidence interval (CI): -0.44, -0.00) and significantly higher length-for-age (β: 0.29, 95% CI: 0.00, 0.58) and weight-for-age (β: 0.20, 95% CI: 0.05, 0.34) Z-scores at 12-16 months. Furthermore, in adjusted linear regression models, ln L:M ratios at 12-16 months significantly decreased with increasing length-for-age Z-scores at birth, 6 months, and 9 months (β: -0.05, 95% CI: -0.10, -0.004; β: -0.06, 95% CI: -0.11, -0.006; and β: -0.05, 95% CI: -0.09, -0.005, respectively). Overall, our data suggest that programs seeking to improve nutrition should address poor WASH conditions simultaneously, particularly related to household drinking water quality.

Study of Environmental Enteropathy and Malnutrition (SEEM) in Pakistan: protocols for biopsy based biomarker discovery and validation

Background

Environmental Enteropathy (EE), characterized by alterations in intestinal structure, function, and immune activation, is believed to be an important contributor to childhood undernutrition and its associated morbidities, including stunting. Half of all global deaths in children < 5 years are attributable to under-nutrition, making the study of EE an area of critical priority.

Methods

Community based intervention study, divided into two sub-studies, 1) Longitudinal analyses and 2) Biopsy studies for identification of EE features via omics analyses. Birth cohorts in Matiari, Pakistan established: moderately or severely malnourished (weight for height Z score (WHZ) < − 2) children, and well-nourished (WHZ > 0) children. Blood, urine, and fecal samples, for evaluation of potential biomarkers, will be collected at various time points from all participants (longitudinal analyses). Participants will receive appropriate educational and nutritional interventions; non-responders will undergo further evaluation to determine eligibility for further workup, including upper gastrointestinal endoscopy. Histopathological changes in duodenal biopsies will be compared with duodenal biopsies obtained from USA controls who have celiac disease, Crohn’s disease, or who were found to have normal histopathology. RNA-Seq will be employed to characterize mucosal gene expression across groups. Duodenal biopsies, luminal aspirates from the duodenum, and fecal samples will be analyzed to define microbial community composition (omic analyses). The relationship between histopathology, mucosal gene expression, and community configuration will be assessed using a variety of bioinformatic tools to gain better understanding of disease pathogenesis and to identify mechanism-based biomarkers. Ethical review committees at all collaborating institutions have approved this study. All results will be made available to the scientific community.

Discussion

Operational and ethical constraints for safely obtaining intestinal biopsies from children in resource-poor settings have led to a paucity of human tissue-based investigations to understand and reverse EE in vulnerable populations. Furthermore, EE biomarkers have rarely been correlated with gold standard histopathological confirmation. The Study of Environmental Enteropathy and Malnutrition (SEEM) is designed to better understand the pathophysiology, predictors, biomarkers, and potential management strategies of EE to inform strategies to eradicate this debilitating pathology and accelerate progress towards the 2030 Sustainable Development Goals.

Trial registration

Retrospectively registered; clinicaltrials.gov ID NCT03588013.

Electronic supplementary material

The online version of this article (10.1186/s12887-019-1564-x) contains supplementary material, which is available to authorized users.

Markers of Systemic Inflammation and Environmental Enteric Dysfunction Are Not Reduced by Zinc or Multivitamins in Tanzanian Infants: A Randomized, Placebo-Controlled Trial

OBJECTIVE

To examine whether daily zinc and/or multivitamin supplementation reduce biomarkers of environmental enteric dysfunction (EED), systemic inflammation, or markers of growth in a sample of infants from Dar es Salaam, Tanzania.

STUDY DESIGN

Subgroup analysis of infants participating in a randomized, double-blind, placebo-controlled trial received daily oral supplementation of zinc, multivitamins, zinc + multivitamins, or placebo for 18 months starting at 6 weeks of age. EED (anti-flagellin and anti-lipopolysaccharide immunoglobulins), systemic inflammation (C-reactive protein and alpha-1-acid glycoprotein), and growth biomarkers (insulin-like growth factor-1 and insulin-like growth factor binding protein-3) were measured via enzyme-linked immunosorbent assay in a subsample of 590 infants at 6 weeks and 6 months of age. EED biomarkers also were measured in 162 infants at 12 months of age.

RESULTS

With the exception of anti-lipopolysaccharide IgG concentrations, which were significantly greater in infants who received multivitamins compared with those who did not (1.41 ± 0.61 vs 1.26 ± 0.65, P = .006), and insulin-like growth factor binding protein-3 concentrations, which were significantly lower in children who received zinc compared with those who did not (981.13 ± 297.59 vs 1019.10 ± 333.01, P = .03), at 6 months of age, we did not observe any significant treatment effects of zinc or multivitamins on EED, systemic inflammation, or growth biomarkers.

CONCLUSIONS

Neither zinc nor multivitamin supplementation ameliorated markers of EED or systemic inflammation during infancy. Other interventions should be prioritized for future trials.

TRIAL REGISTRATION

Clinicaltrials.gov: NCT00421668.

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.

Identifying the etiology and pathophysiology underlying stunting and environmental enteropathy: study protocol of the AFRIBIOTA project

BACKGROUND

Globally one out of four children under 5 years is affected by linear growth delay (stunting). This syndrome has severe long-term sequelae including increased risk of illness and mortality and delayed psychomotor development. Stunting is a syndrome that is linked to poor nutrition and repeated infections. To date, the treatment of stunted children is challenging as the underlying etiology and pathophysiological mechanisms remain elusive. We hypothesize that pediatric environmental enteropathy (PEE), a chronic inflammation of the small intestine, plays a major role in the pathophysiology of stunting, failure of nutritional interventions and diminished response to oral vaccines, potentially via changes in the composition of the pro- and eukaryotic intestinal communities. The main objective of AFRIBIOTA is to describe the intestinal dysbiosis observed in the context of stunting and to link it to PEE. Secondary objectives include the identification of the broader socio-economic environment and biological and environmental risk factors for stunting and PEE as well as the testing of a set of easy-to-use candidate biomarkers for PEE. We also assess host outcomes including mucosal and systemic immunity and psychomotor development. This article describes the rationale and study protocol of the AFRIBIOTA project.

METHODS

AFRIBIOTA is a case-control study for stunting recruiting children in Bangui, Central African Republic and in Antananarivo, Madagascar. In each country, 460 children aged 2-5 years with no overt signs of gastrointestinal disease are recruited (260 with no growth delay, 100 moderately stunted and 100 severely stunted). We compare the intestinal microbiota composition (gastric and small intestinal aspirates; feces), the mucosal and systemic immune status and the psychomotor development of children with stunting and/or PEE compared to non-stunted controls. We also perform anthropological and epidemiological investigations of the children's broader living conditions and assess risk factors using a standardized questionnaire.

DISCUSSION

To date, the pathophysiology and risk factors of stunting and PEE have been insufficiently investigated. AFRIBIOTA will add new insights into the pathophysiology underlying stunting and PEE and in doing so will enable implementation of new biomarkers and design of evidence-based treatment strategies for these two syndromes.

Effect of cowpea flour processing on the chemical properties and acceptability of a novel cowpea blended maize porridge

Childhood growth stunting is a pervasive problem in Malawi and is in large part due to low quality complementary foods and chronic gut inflammation. Introducing legumes such as cowpea (Vigna unguiculata) into the complementary diet has the potential to improve childhood growth by improving diet quality through improvements in macro- and micronutrients and also by reducing gut inflammation. However, cowpea is relatively underutilized in complementary feeding in Malawi due to its strong taste, long processing time, and high energy requirements for processing. Effective utilization of cowpea in complementary feeding requires processing which may affect chemical composition as well as sensory quality. The present study evaluated the effect of processing on the retention of zinc, crude fibre, and flavonoid in roasted, boiled, and dehulled cowpea flours, and assessed the acceptability of maize porridge (70%) enriched with one of the three cowpea flours (30%). Roasting, dehulling, and boiling did not have any effect on zinc content. Crude fibre content increased after processing by all methods. Processing had no effect on measurable flavonoids. Roasted, boiled, and dehulled cowpea blended maize porridges were acceptable to children with mean quantities of leftover food of less than 3g from the given 100g. Caregivers also rated the blended flours to be highly acceptable to them as well, with maize porridge blended with dehulled cowpea flour the most acceptable to both children and caregivers. These results demonstrate that cowpea flour, processed by any of these three different methods, could serve as a useful addition to maize porridge for complementary feeding of children in sub-Saharan Africa.

Exploring the relationship between environmental enteric dysfunction and oral vaccine responses

Oral vaccines significantly underperform in low-income countries. One possible contributory factor is environmental enteric dysfunction (EED), a subclinical disorder of small intestinal structure and function among children living in poverty. Here, we review studies describing oral vaccine responses and EED. We identified eight studies evaluating EED and oral vaccine responses. There was substantial heterogeneity in study design and few consistent trends emerged. Four studies reported a negative association between EED and oral vaccine responses; two showed no significant association; and two described a positive correlation. Current evidence is therefore insufficient to determine whether EED contributes to oral vaccine underperformance. We identify roadblocks in the field and future research needs, including carefully designed studies those can investigate this hypothesis further.

Environmental Enteropathy in Undernourished Pakistani Children: Clinical and Histomorphometric Analyses

Despite nutrition interventions, stunting thought to be secondary to underlying environmental enteropathy (EE) remains pervasive among infants residing in resource-poor countries and remains poorly characterized. From a birth cohort of 380 children, 65 malnourished infants received 12 weeks of nutritional supplementation with ready-to-use therapeutic food (RUTF). Eleven children with insufficient response to RUTF underwent upper endoscopy with duodenal biopsies, which were compared with U.S., age-matched specimens for healthy, celiac disease, non-celiac villous atrophy, non-celiac intraepithelial lymphocytosis, and graft-versus-host disease patients. Of the 11 children biopsied, EE was found in 10 (91%) with one subject with celiac disease. Morphometry demonstrated decreased villus-to-crypt (V:C) ratios in EE relative to healthy and non-celiac lymphocytosis patients. Environmental enteropathy villus volumes were significantly decreased relative to healthy controls. In EE, average CD3⁺ cells per 100 epithelial cells and per 1,000 µm² of lamina propria and the number of lamina propria CD20⁺ B-cell aggregates were increased relative to all other groups. Our results indicate that V:C ratios are reduced in EE but are less severe than in celiac disease. Environmental enteropathy intraepithelial and lamina propria T lymphocytosis is of greater magnitude than that in celiac disease. The increases in lamina propria B and T lymphocytes suggest that non-cytolytic lymphocytic activation may be a more prominent feature of EE relative to celiac disease. These results provide new insights into shared yet distinct histological and immunological features of EE and celiac disease in children.

Additional Common Bean in the Diet of Malawian Children Does Not Affect Linear Growth, but Reduces Intestinal Permeability

Background

Chronic malnutrition, as manifested by linear growth faltering, is pervasive among rural African children. Improvements in complementary feeding may decrease the burden of environmental enteric dysfunction (EED) and thus improve growth in children during the critical first 1000 d of development.

Objective

We tested the hypothesis that systematically including common bean or cowpea into complementary feeding would reduce EED and growth faltering among children in rural Malawi.

Methods

This was a double-blind clinical trial in which children 12-23 mo of age were randomly assigned to receive complementary feeding with 1 of 3 foods: roasted cowpea or common bean flour, or an isoenergetic amount of corn-soy blend as a control food for 48 wk. Children aged 12-23 mo received 155 kcal/d and thereafter until 35 mo received 200 kcal/d. The primary outcomes were change in length-for-age z score (LAZ) and improvements in a biomarker of EED, the percentage of lactulose (%L) excreted as part of the lactulose:mannitol dual-sugar absorption test. Anthropometric measurements and urinary %L excretion were compared between the 2 intervention groups and the control group separately with the use of linear mixed model analyses for repeated measures.

Results

A total of 331 children completed the clinical trial. Compliance with the study interventions was excellent, with >90% of the intervention flour consumed as intended. No significant effects on LAZ, change in LAZ, or weight-for-length z score were observed due to either intervention legume, compared to the control. %L was reduced with common bean consumption (effect estimate was -0.07 percentage points of lactulose, P = 0.0007). The lactulose:mannitol test was not affected by the legume intervention.

Conclusion

The addition of common bean to complementary feeding of rural Malawian children during the second year of life led to an improvement in a biomarker of gut health, although this did not directly translate into improved linear growth. This trial was registered at clinicaltrials.gov as NCT02472301.

Complementary feeding with cowpea reduces growth faltering in rural Malawian infants: a blind, randomized controlled clinical trial

Background: Growth faltering is common in rural African children and is attributed to inadequate dietary intake and environmental enteric dysfunction (EED).Objective: We tested the hypothesis that complementary feeding with cowpea or common bean flour would reduce growth faltering and EED in 6-mo-old rural Malawians compared with the control group receiving a corn-soy blend.Design: A prospective, double-blind, randomized controlled clinical trial was conducted in which children received daily feeding for 6 mo (200 kcal/d when 6-9 mo old and 300 kcal/d when 10-12 mo old). The primary outcomes were change in length-for-age z score (LAZ) and improvements in EED, as measured by percentage of lactulose excretion (%L). %L <0.2% was considered normal. Anthropometric measurements and %L through urine were compared between each legume group and the control group with Student's t test.Results: Of the 355 infants enrolled, 291 infants completed the trial, and 288 were breastfed throughout the duration of the study. Cowpea and common bean added 4.6-5.2 g protein/d and 4-5 g indigestible carbohydrate/d to the diet. LAZ and weight-for-height z score were reduced in all 3 groups from 6 to 12 mo of age. The changes in LAZ [mean (95% CI)] for the cowpea, common bean, and control groups from 6 to 9 mo were -0.14 (-0.24, -0.04), -0.27 (-0.38, -0.16), and -0.27 (-0.35, -0.19), respectively. LAZ was reduced less in infants receiving cowpea than in those receiving control food from 6 to 9 mo (P = 0.048). The absolute value of %L did not differ between the dietary groups at 9 mo of age (mean ± SD: 0.30 ± 0.43, 0.23 ± 0.21, and 0.26 ± 0.31 for cowpea, common bean, and control, respectively), nor did the change in %L from 6 to 9 mo.Conclusion: Addition of cowpea to complementary feeding in Malawian infants resulted in less linear growth faltering. This trial was registered at clinicaltrials.gov as NCT02472262.

Lactoferrin and lysozyme to reduce environmental enteric dysfunction and stunting in Malawian children: study protocol for a randomized controlled trial

Background

Chronic childhood malnutrition, as manifested by stunted linear growth, remains a persistent barrier to optimal child growth and societal development. Environmental enteric dysfunction (EED) is a significant underlying factor in the causal pathway to stunting, delayed cognitive development, and ultimately morbidity and mortality. Effective therapies against EED and stunting are lacking and further clinical trials are warranted to effectively identify and operationalize interventions.

Methods/design

A prospective randomized placebo-controlled parallel-group randomized controlled trial will be conducted to determine if a daily supplement of lactoferrin and lysozyme, two important proteins found in breast milk, can decrease the burden of EED and stunting in rural Malawian children aged 12–23 months old. The intervention and control groups will have a sample size of 86 subjects each. All field and laboratory researchers will be blinded to the assigned intervention group, as will the subjects and their caregivers. The percentage of ingested lactulose excreted in the urine (Δ%L) after 4 h will be used as the biomarker for EED and linear growth as the measure of chronic malnutrition (stunting). The primary outcomes of interest will be change in Δ%L from baseline to 8 weeks and to 16 weeks. Intention-to-treat analyses will be used.

Discussion

A rigorous clinical trial design will be used to assess the biologically plausible use of lactoferrin and lysozyme as dietary supplements for children at high risk for EED. If proven effective, these safe proteins may serve to markedly reduce the burden of childhood malnutrition and improve survival.

Trial Registration

Clinicaltrials.gov, NCT02925026. Registered on 4 October 2016.

Electronic supplementary material

The online version of this article (doi:10.1186/s13063-017-2278-8) contains supplementary material, which is available to authorized users.

Measurement of gut permeability using fluorescent tracer agent technology

The healthy gut restricts macromolecular and bacterial movement across tight junctions, while increased intestinal permeability accompanies many intestinal disorders. Dual sugar absorption tests, which measure intestinal permeability in humans, present challenges. Therefore, we asked if enterally administered fluorescent tracers could ascertain mucosal integrity, because transcutaneous measurement of differentially absorbed molecules could enable specimen-free evaluation of permeability. We induced small bowel injury in rats using high- (15 mg/kg), intermediate- (10 mg/kg), and low- (5 mg/kg) dose indomethacin. Then, we compared urinary ratios of enterally administered fluorescent tracers MB-402 and MB-301 to urinary ratios of sugar tracers lactulose and rhamnose. We also tested the ability of transcutaneous sensors to measure the ratios of absorbed fluorophores. Urinary fluorophore and sugar ratios reflect gut injury in an indomethacin dose dependent manner. The fluorophores generated smooth curvilinear ratio trajectories with wide dynamic ranges. The more chaotic sugar ratios had narrower dynamic ranges. Fluorophore ratios measured through the skin distinguished indomethacin-challenged from same day control rats. Enterally administered fluorophores can identify intestinal injury in a rat model. Fluorophore ratios are measureable through the skin, obviating drawbacks of dual sugar absorption tests. Pending validation, this technology should be considered for human use.

Age and Sex Normalization of Intestinal Permeability Measures for the Improved Assessment of Enteropathy in Infancy and Early Childhood: Results From the MAL-ED Study

OBJECTIVES

The aim of the study was to describe changes in intestinal permeability in early childhood in diverse epidemiologic settings.

METHODS

In a birth cohort study, the lactulose:mannitol (L:M) test was administered to 1980 children at 4 time points in the first 24 months of life in 8 countries. Data from the Brazil site with an incidence of diarrhea similar to that seen in the United States and no growth faltering was used as an internal study reference to derive age- and sex-specific z scores for mannitol and lactulose recoveries and the L:M ratio.

RESULTS

A total of 6602 tests demonstrated mannitol recovery, lactulose recovery, and the L:M ratio were associated with country, sex, and age. There was heterogeneity in the recovery of both probes between sites with mean mannitol recovery ranging for 1.34% to 5.88%, lactulose recovery of 0.19% to 0.58%, and L:M ratios 0.10 to 0.17 in boys of 3 months of age across different sites. We observed strong sex-specific differences in both mannitol and lactulose recovery, with boys having higher recovery of both probes. Alterations in intestinal barrier function increased in most sites from 3 to 9 months of age and plateaued or diminished from 9 to 15 months of age.

CONCLUSIONS

Alterations in recovery of the probes differ markedly in different epidemiologic contexts in children living in the developing world. The rate of change in the L:M-z ratio was most rapid and consistently disparate from the reference standard in the period between 6 and 9 months of age, suggesting that this is a critical period of physiologic impact of enteropathy in these populations.

A Combined Intervention of Zinc, Multiple Micronutrients, and Albendazole Does Not Ameliorate Environmental Enteric Dysfunction or Stunting in Rural Malawian Children in a Double-Blind Randomized Controlled Trial

BACKGROUND

Environmental enteric dysfunction (EED) and linear growth stunting affect many rural agrarian children in the developing world and contribute to the persistently high rates of stunting that are observed worldwide. Effective interventions to consistently ameliorate EED are lacking.

OBJECTIVE

We tested whether a bundle of safe and affordable interventions would decrease EED and stunting over 12-24 wk in a cohort of rural Malawian children 12-35 mo old.

METHODS

This was a randomized, double-blind, placebo-controlled clinical trial in which the intervention group received a single dose of albendazole and 14 d of zinc at enrollment and after 20 wk. The intervention group also received a daily multiple micronutrient powder throughout the 24 wk of study. The primary outcomes were improvements in EED, as measured by the urinary lactulose-to-mannitol ratio (L:M ratio) from dual-sugar absorption testing, and linear growth. Urinary L:M ratios and anthropometric measurements were evaluated after 12 and 24 wk of intervention and compared with a placebo group that did not receive any of these interventions.

RESULTS

A total of 254 children were enrolled at a mean age of 24 mo; 55% were female. Their mean weight-for-age z score was -1.5, and their mean length-for-age z score was -0.9. After 12 and 24 wk of study, increases in the L:M ratio did not differ between the intervention group (0.071 and 0.088 units, respectively) and the placebo group (0.073 and 0.080 units, respectively) (P = 0.87 and 0.19, respectively). Relative changes in length and weight also did not differ significantly between groups at any time point.

CONCLUSION

The combined usage of albendazole, zinc, and a daily multiple micronutrient powder did not decrease EED or stunting in this population of agrarian children 12-35 mo old in rural Malawi. Alternative interventions to improve these diseases should be investigated. This trial was registered at clinicaltrials.gov as NCT02253095.

Environmental Enteric Dysfunction Is Associated With Poor Linear Growth and Can Be Identified by Host Fecal mRNAs

OBJECTIVE

Environmental enteric dysfunction (EED) can be assessed by the lactulose:mannitol (L:M) test. Our objective was to determine if selected host fecal transcripts were correlated with EED, and whether transcripts and clinical characteristics could be used to predict EED in rural African children.

METHODS

Demographic and sanitation characteristics, along with L:M testing and host fecal transcript analyses from 798 asymptomatic Malawian children aged 12 to 61 months were compared with linear growth over the subsequent 3 months. Fecal host mRNA analysis included quantification of expression of 18 transcripts associated with L:M. Permeability was categorized as normal (L:M ≤ 0.15), moderate (0.15<L:M<0.45) and severe (L:M ≥ 0.45), and random forest predictive models were created.

RESULTS

L:M was inversely correlated with linear growth over the subsequent 3 months (r = -0.32, P < 0.001) and severe EED was associated with stunting (P < 0.0001). Age younger than 24 months, weight-for-height z score <0, domesticated animals in the child's sleep environment, lack of a pit latrine combined with a potentially contaminated water source, and a recent history of diarrhea were associated with severe EED. A random forest model using CD53, HLA-DRA, MUC12, and TNF was 84% sensitive for severe EED and 83% sensitive for no EED.

CONCLUSIONS

Selected host fecal transcripts can be used in a random forest model as a noninvasive biomarker for categories of EED in rural African children.

The Sanitation Hygiene Infant Nutrition Efficacy (SHINE) Trial: Rationale, Design, and Methods

Child stunting and anemia are intractable public health problems in developing countries and have profound short- and long-term consequences. The Sanitation Hygiene Infant Nutrition Efficacy (SHINE) trial is motivated by the premise that environmental enteric dysfunction (EED) is a major underlying cause of both stunting and anemia, that chronic inflammation is the central characteristic of EED mediating these adverse effects, and that EED is primarily caused by high fecal ingestion due to living in conditions of poor water, sanitation, and hygiene (WASH). SHINE is a proof-of-concept, 2 × 2 factorial, cluster-randomized, community-based trial in 2 rural districts of Zimbabwe that will test the independent and combined effects of protecting babies from fecal ingestion (factor 1, operationalized through a WASH intervention) and optimizing nutritional adequacy of infant diet (factor 2, operationalized through an infant and young child feeding [IYCF] intervention) on length and hemoglobin at 18 months of age. Within SHINE we will measure 2 causal pathways. The program impact pathway comprises the series of processes and behaviors linking implementation of the interventions with the 2 child health primary outcomes; it will be modeled using measures of fidelity of intervention delivery and household uptake of promoted behaviors and practices. We will also measure a range of household and individual characteristics, social interactions, and maternal capabilities for childcare, which we hypothesize will explain heterogeneity along these pathways. The biomedical pathway comprises the infant biologic responses to the WASH and IYCF interventions that ultimately result in attained stature and hemoglobin concentration at 18 months of age; it will be elucidated by measuring biomarkers of intestinal structure and function (inflammation, regeneration, absorption, and permeability); microbial translocation; systemic inflammation; and hormonal determinants of growth and anemia among a subgroup of infants enrolled in an EED substudy. This article describes the rationale, design, and methods underlying the SHINE trial.

CLINICAL TRIALS REGISTRATION

NCT01824940.

Plasma Tryptophan and the Kynurenine-Tryptophan Ratio are Associated with the Acquisition of Statural Growth Deficits and Oral Vaccine Underperformance in Populations with Environmental Enteropathy

Early childhood enteric infections have adverse impacts on child growth and can inhibit normal mucosal responses to oral vaccines, two critical components of environmental enteropathy. To evaluate the role of indoleamine 2,3-dioxygenase 1 (IDO1) activity and its relationship with these outcomes, we measured tryptophan and the kynurenine–tryptophan ratio (KTR) in two longitudinal birth cohorts with a high prevalence of stunting. Children in rural Peru and Tanzania (N = 494) contributed 1,251 plasma samples at 3, 7, 15, and 24 months of age and monthly anthropometrics from 0 to 36 months of age. Tryptophan concentrations were directly associated with linear growth from 1 to 8 months after biomarker assessment. A 1-SD increase in tryptophan concentration was associated with a gain in length-for-age Z-score (LAZ) of 0.17 over the next 6 months in Peru (95% confidence interval [CI] = 0.11–0.23, P < 0.001) and a gain in LAZ of 0.13 Z-scores in Tanzania (95% CI = 0.03–0.22, P = 0.009). Vaccine responsiveness data were available for Peru only. An increase in kynurenine by 1 μM was associated with a 1.63 (95% CI = 1.13–2.34) increase in the odds of failure to poliovirus type 1, but there was no association with tetanus vaccine response. A KTR of 52 was 76% sensitive and 50% specific in predicting failure of response to serotype 1 of the oral polio vaccine. KTR was associated with systemic markers of inflammation, but also interleukin-10, supporting the association between IDO1 activity and immunotolerance. These results strongly suggest that the activity of IDO1 is implicated in the pathophysiology of environmental enteropathy, and demonstrates the utility of tryptophan and kynurenine as biomarkers for this syndrome, particularly in identifying those at risk for hyporesponsivity to oral vaccines.

An Exposome Perspective on Environmental Enteric Dysfunction

BACKGROUND

Environmental exposures to chemicals have been shown to influence gastrointestinal function, yet little is known regarding whether chemical mixtures may be involved in the development of a subclinical enteric dysfunction found in infants and children born into poor hygiene and sanitation. Advances in gastrointestinal and immunotoxicology fields merit inclusion in complex discussions of environmental enteric dysfunction (EED) that severely affects children in developing countries.

OBJECTIVE

We aimed to highlight exposome approaches for investigating the potential influence of environmental chemical exposures on EED development, including a role for toxicant modulation of gut immune system and microbiome function.

DISCUSSION

A major focus on fecal-oral contamination in impoverished living conditions already exists for EED, and should now expand to include environmental chemicals such as pesticides and heavy metals that may be anthropogenic or dietary or from microbial sources. A comprehensive characterization of environmental chemical exposures prenatally and occurring in infants and young children will enhance our knowledge of any associated risks for EED and stunting.

CONCLUSIONS

Integrating EED, chemical exposure, and stunting at various ages during childhood will enhance our apparent limited view when evaluating EED. Etiology and intervention studies should evaluate the suite of environmental chemical exposures as candidates in the composite of EED biomarkers.

CITATION

Mapesa JO, Maxwell AL, Ryan EP. 2016. An exposome perspective on environmental enteric dysfunction. Environ Health Perspect 124:1121-1126; http://dx.doi.org/10.1289/ehp.1510459.

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.

Environmental Enteric Dysfunction in Children

Diarrheal diseases are a major cause of childhood death in resource-poor countries, killing approximately 760,000 children younger than 5 years each year. Although deaths due to diarrhea have declined dramatically, high rates of stunting and malnutrition have persisted. Environmental enteric dysfunction (EED) is a subclinical condition caused by constant fecal-oral contamination with resultant intestinal inflammation and villous blunting. These histological changes were first described in the 1960s, but the clinical effect of EED is only just being recognized in the context of failure of nutritional interventions and oral vaccines in resource-poor countries. We review the existing literature regarding the underlying causes of and potential interventions for EED in children, highlighting the epidemiology, clinical and histologic classification of the entity, and discussing novel biomarkers and possible therapies. Future research priorities are also discussed.

Droplet digital PCR quantifies host inflammatory transcripts in feces reliably and reproducibly

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Direct measurement of gut epithelial immunology is difficult.

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Fecal host transcript can measured using conservative transcript isolation and droplet digital PCR.

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A new method to non-invasively elucidate gut immunology is described.

The gut is the most extensive, interactive, and complex interface between the human host and the environment and therefore a critical site of immunological activity. Non-invasive methods to assess the host response in this organ are currently lacking. Feces are the available analyte which have been in proximity to the gut tissue.

We applied a method of concentrating host transcripts from fecal specimens using a existing bead-based affinity separation method for nucleic acids and quantified transcripts using droplet digital PCR (ddPCR) to determine the copy numbers of a variety of key transcripts in the gut immune system. ddPCR compartmentalizes the reaction in a small aqueous droplet suspended in oil, and counts droplets as either fluorescent or non-fluorescent. Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) was used to normalize transcript concentration.

This method was applied to 799 fecal samples from rural Malawian children, and over 20,000 transcript concentrations were quantified. Host mRNA was detected in >99% samples, a threshold for target detection was established at an average expression of 0.02 copies target/GAPDH, above which correlation coefficient between duplicate measurements is >0.95. Quantities of transcript detected using ddPCR were greater than standard qPCR. Fecal sample preservation at the time of collection did not require immediate freezing or the addition of buffers or enzymes. Measurements of transcripts encoding immunoactive proteins correlated with a measure of gut inflammation in the study children, thereby substantiating their relevance. This method allows investigators to interrogate gene expression in the gut.

Common beans and cowpeas as complementary foods to reduce environmental enteric dysfunction and stunting in Malawian children: study protocol for two randomized controlled trials

Background

Interventions to decrease the burden of childhood malnutrition are urgently needed, as millions of children die annually owing to undernutrition and hundreds of millions more are left cognitively and physically stunted. Environmental enteric dysfunction (EED), a pervasive chronic subclinical inflammatory condition among children that develops when complementary foods are introduced, places them at high risk of stunting, malabsorption, and poor oral vaccine efficacy. Improved interventions to reduce the burden of EED and stunting are expected to markedly improve the nutritional status and survival of children throughout resource-limited settings.

Methods/Design

We will conduct, in parallel, two prospective randomized controlled clinical trials to determine whether common beans or cowpeas improve growth, ameliorate EED, and alter the intestinal microbiome during a high-risk period in the lives of rural Malawian children. Study 1 will enroll children at 6 months of age and randomize them to receive common beans, cowpeas, or a standard complementary food for 6 months. Anthropometry will be compared among the three groups; EED will be assessed using a dual-sugar absorption test and by quantifying human intestinal mRNA for inflammatory messages; and the intestinal microbiota will be characterized by deep sequencing of fecal DNA, to enumerate host microbial populations and their metabolic capacity. Study 2 will enroll children 12–23 months old and follow them for 12 months, with similar interventions and assessments as Study 1.

Discussion

By amalgamating the power of rigorous clinical trials and advanced biological analysis, we aim to elucidate the potential of two grain legumes to reduce stunting and EED in a high-risk population. Legumes have potential as an affordable and effective complementary food intervention, given their cultural acceptability, nutritional content, and agricultural feasibility in sub-Saharan Africa.

Trial registration

Clinicaltrials.gov NCT02472262 and NCT02472301.

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.

Plasma endotoxin core antibody concentration and linear growth are unrelated in rural Malawian children aged 2-5 years

BACKGROUND

Environmental enteropathy is subclinical inflammation of the upper gastrointestinal tract associated with reduced linear growth in developing countries. Usually investigators have used biopsy or a dual sugar absorption test to assess environmental enteropathy. Such tests are time and resource intensive, restricting their utility as screening methods. Serum endotoxin core antibody (EndoCab) concentration is a potential indicator of intestinal inflammation and integrity, and thus may be useful to predict environmental enteropathy. We analyzed the association of serum EndoCab levels versus linear growth and lactulose-mannitol assay results in 2-5 year old rural Malawian children.

METHODS

This was an observational study of 388 rural, asymptomatic Malawian children who had anthropometric measurements taken at least every 3 months since birth. In June and July 2011, dual sugar permeability tests were performed and serum samples were drawn for EndoCab assays. Pearson correlation, Student's t test and multivariable linear regression were used to compare ln EndoCab concentrations with height-for-age z scores (HAZ) at time of sampling and 3 months later. Identical analysis was also performed for ln EndoCab versus measurements from dual sugar permeability testing performed in conjunction with serum sampling. In a subgroup of children with anthropometric data in the months prior to serum sampling, Pearson correlation was used to estimate the relationship between ln EndoCab and recent linear growth.

RESULTS

Ln EndoCab concentrations were not correlated with HAZ at time of measurement (B = -0.078, P = 0.14) nor change in HAZ over the subsequent 3 months HAZ (B = -0.018, P = 0.27). EndoCab concentration was not associated with %lactulose excretion (B < 0.001, P = 0.98) nor the lactulose:mannitol ratio (B = 0.021, P = 0.62). Subgroup analysis also did not reveal any significant association between EndoCab and recent growth.

CONCLUSION

EndoCab titers were not correlated with measurements of growth or intestinal permeability in rural pre-school aged Malawian children.

Use of the lactulose to mannitol ratio to evaluate childhood environmental enteric dysfunction: a systematic review

Childhood gut dysfunction (enteropathy) is common in resource-poor environments. Stunting is its presumed major consequence. Identification of biomarkers of gut dysfunction could identify the presence of, and, ideally, assess interventions for, enteropathy. Classically, enteropathy has been identified histopathologically. However, less invasive assays may be more sensitive for detecting earlier perturbations reflecting specific functional derangements. The most commonly used test has been the urinary lactulose to mannitol ratio (L:M), which primarily assesses gut leakiness, and which also measures absorption. We systematically reviewed the L:M literature published from 2000 to 2010 pertinent to children in developing country settings, and identified 25 relevant publications representing heterogeneous studies. We conclude that the L:M test has many attributes, including reflecting 2 physiologic processes (absorption and permeability) and likely correlation with growth failure consequent to child gut dysfunction. However, improved test technical performance, data reporting, and correlation with host phenotypes are needed to maximize the utility of this test.

The "Performance of Rotavirus and Oral Polio Vaccines in Developing Countries" (PROVIDE) study: description of methods of an interventional study designed to explore complex biologic problems

Oral vaccines appear less effective in children in the developing world. Proposed biologic reasons include concurrent enteric infections, malnutrition, breast milk interference, and environmental enteropathy (EE). Rigorous study design and careful data management are essential to begin to understand this complex problem while assuring research subject safety. Herein, we describe the methodology and lessons learned in the PROVIDE study (Dhaka, Bangladesh). A randomized clinical trial platform evaluated the efficacy of delayed-dose oral rotavirus vaccine as well as the benefit of an injectable polio vaccine replacing one dose of oral polio vaccine. This rigorous infrastructure supported the additional examination of hypotheses of vaccine underperformance. Primary and secondary efficacy and immunogenicity measures for rotavirus and polio vaccines were measured, as well as the impact of EE and additional exploratory variables. Methods for the enrollment and 2-year follow-up of a 700 child birth cohort are described, including core laboratory, safety, regulatory, and data management practices. Intense efforts to standardize clinical, laboratory, and data management procedures in a developing world setting provide clinical trials rigor to all outcomes. Although this study infrastructure requires extensive time and effort, it allows optimized safety and confidence in the validity of data gathered in complex, developing country settings.

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.

Environmental and NSAID-enteropathy: dysbiosis as a common factor

At first sight, environmental enteropathy and NSAID enteropathy may appear to have little in common. One occurs almost exclusively in poor countries and the other primarily in rich countries. One is the consequence of unhygienic living conditions, while the other is a consequence of use of a drug for relief of pain and inflammation. However, there may be a common pathogenic link between these two conditions, namely a significant alteration in the microbiome (dysbiosis), and this raises the possibility of common approaches to treatment. Correction of the dysbiosis that is central to the intestinal tissue injury and dysfunction observed in environmental and nonsteroidal anti-inflammatory drug (NSAID)-induced enteropathies is a logical approach to bringing about restoration of intestinal function. For both conditions, removal of the trigger for dysbiosis is the simplest approach, but is not always feasible. Correcting the underlying dysbiosis through the use of probiotics or prebiotics may be a viable option.

Lactulose: mannitol diagnostic test by HPLC and LC-MSMS platforms: considerations for field studies of intestinal barrier function and environmental enteropathy

OBJECTIVES

The lactulose:mannitol (L:M) diagnostic test is frequently used in field studies of environmental enteropathy (EE); however, heterogeneity in test administration and disaccharide measurement has limited the comparison of results between studies and populations. We aim to assess the agreement between L:M measurement between high-performance liquid chromatography with pulsed amperometric detection (HPLC-PAD) and liquid chromatography-tandem mass spectrometry (LC-MSMS) platforms.

METHODS

The L:M test was administered in a cohort of Peruvian infants considered at risk for EE. A total of 100 samples were tested for lactulose and mannitol at 3 independent laboratories: 1 running an HPLC-PAD platform and 2 running LC-MSMS platforms. Agreement between the platforms was estimated.

RESULTS

The Spearman correlation between the 2 LC-MSMS platforms was high (ρ ≥ 0.89) for mannitol, lactulose, and the L:M ratio. The correlation between the HPLC-PAD platform and LC-MSMS platform was ρ = 0.95 for mannitol, ρ = 0.70 for lactulose, and ρ = 0.43 for the L:M ratio. In addition, the HPLC-PAD platform overestimated the lowest disaccharide concentrations to the greatest degree.

CONCLUSIONS

Given the large analyte concentration range, the improved accuracy of LC-MSMS has important consequences for the assessment of lactulose and mannitol following oral administration in populations at risk for EE. We recommend that researchers wishing to implement a dual-sugar test as part of a study of EE use an LC-MSMS platform to optimize the accuracy of results and increase comparability between studies.

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.

Mesalazine in the initial management of severely acutely malnourished children with environmental enteric dysfunction: a pilot randomized controlled trial

BACKGROUND

Environmental enteric dysfunction (EED) is an acquired syndrome of impaired gastrointestinal mucosal barrier function that is thought to play a key role in the pathogenesis of stunting in early life. It has been conceptualized as an adaptive response to excess environmental pathogen exposure. However, it is clinically similar to other inflammatory enteropathies, which result from both host and environmental triggers, and for which immunomodulation is a cornerstone of therapy.

METHODS

In this pilot double-blind randomized placebo-controlled trial, 44 children with severe acute malnutrition and evidence of EED were assigned to treatment with mesalazine or placebo for 28 days during nutritional rehabilitation. Primary outcomes were safety and acceptability of the intervention.

RESULTS

Treatment with mesalazine was safe: there was no excess of adverse events, evidence of deterioration in intestinal barrier integrity or impact on nutritional recovery. There were modest reductions in several inflammatory markers with mesalazine compared to placebo. Depression of the growth hormone--insulin-like growth factor-1 axis was evident at enrollment and associated with inflammatory activation. Increases in the former and decreases in the latter correlated with linear growth.

CONCLUSIONS

Intestinal inflammation in EED is non-essential for mucosal homeostasis and is at least partly maladaptive. Further trials of gut-specific immunomodulatory therapies targeting host inflammatory activation in order to optimize the growth benefits of nutritional rehabilitation and to address stunting are warranted. Funded by The Wellcome Trust.

TRIAL REGISTRATION

Registered at Clinicaltrials.gov NCT01841099.

Childhood malnutrition: toward an understanding of infections, inflammation, and antimicrobials

BACKGROUND

Undernutrition in childhood is estimated to cause 3.1 million child deaths annually through a potentiating effect on common infectious diseases, such as pneumonia and diarrhea. In turn, overt and subclinical infections, and inflammation, especially in the gut, alter nutrient intake, absorption, secretion, diversion, catabolism, and expenditure.

OBJECTIVE

A narrative overview of the current understanding of infections, inflammation, and antimicrobials in relation to childhood malnutrition.

METHODS

Searches for pivotal papers were conducted using PUBMED 1966-January 2013; hand searches of the references of retrieved literature; discussions with experts; and personal experience from the field.

RESULTS

Although the epidemiological evidence for increased susceptibility to life-threatening infections associated with malnutrition is strong, we are only just beginning to understand some of the mechanisms involved. Nutritional status and growth are strongly influenced by environmental enteric dysfunction (EED), which is common among children in developing countries, and by alterations in the gut microbiome. As yet, there are no proven interventions against EED. Antibiotics have long been used as growth promoters in animals. Trials of antibiotics have shown striking efficacy on mortality and on growth in children with uncomplicated severe acute malnutrition (SAM) or HIV infection. Antibiotics act directly by preventing infections and may act indirectly by reducing subclinical infections and inflammation. We describe an ongoing multicenter, randomized, placebo-controlled trial of daily cotrimoxazole prophylaxis to prevent death in children recovering from complicated SAM. Secondary outcomes include growth, frequency and etiology of infections, immune activation and function, the gut microbiome, and antimicrobial resistance. The trial is expected to be reported in mid-2014.

CONCLUSIONS

As well as improving nutritional intake, new case management strategies need to address infection, inflammation, and microbiota and assess health outcomes rather than only anthropometry.

The stunting syndrome in developing countries

Linear growth failure is the most common form of undernutrition globally. With an estimated 165 million children below 5 years of age affected, stunting has been identified as a major public health priority, and there are ambitious targets to reduce the prevalence of stunting by 40% between 2010 and 2025. We view this condition as a 'stunting syndrome' in which multiple pathological changes marked by linear growth retardation in early life are associated with increased morbidity and mortality, reduced physical, neurodevelopmental and economic capacity and an elevated risk of metabolic disease into adulthood. Stunting is a cyclical process because women who were themselves stunted in childhood tend to have stunted offspring, creating an intergenerational cycle of poverty and reduced human capital that is difficult to break. In this review, the mechanisms underlying linear growth failure at different ages are described, the short-, medium- and long-term consequences of stunting are discussed, and the evidence for windows of opportunity during the life cycle to target interventions at the stunting syndrome are evaluated.

High dose multiple micronutrient supplementation improves villous morphology in environmental enteropathy without HIV enteropathy: results from a double-blind randomised placebo controlled trial in Zambian adults

BACKGROUND

Environmental enteropathy (EE) is an asymptomatic abnormality of small bowel structure and function, which may underlie vaccine inefficacy in the developing world. HIV infection co-exists in many of these populations. There is currently no effective treatment. We conducted a secondary analysis of a randomised controlled trial of high dose multiple micronutrient (MM) supplementation on small bowel architecture in EE in participants with or without HIV infection.

METHODS

In a double-blind parallel-group trial of the effect of MM on innate immune responses to oral vaccines, consenting Zambian adults were randomised to receive 6 weeks of 24 micronutrients as a daily capsule or placebo. HIV status was established after randomisation. Proximal jejunal biopsies were obtained after the supplementation period. Villous height, crypt depth, villous width, villous perimeter per 100 μm muscularis mucosa (a measure of epithelial surface area), and villous cross sectional area per 100 μm muscularis mucosa (a measure of villous compartment volume) were measured in orientated biopsy sections using semi-automated image analysis. Analysis was by intention to treat.

RESULTS

18 patients received MM and 20 placebo. 6/18 MM and 9/20 placebo patients had HIV. In HIV negative patients given MM compared to placebo, mean villous height was 24.0% greater (293.3 v. 236.6 μm; 95% CI of difference 17.7-95.9 μm; P = 0.006), mean villous area was 27.6% greater (27623 v. 21650 μm2/100 μm; 95% CI of difference 818-11130 μm2/100 μm; P = 0.03), and median villous perimeter was 29.7% greater (355.0 v. 273.7 μm/100 μm; 95% CI of difference 16.3-146.2 μm/100 μm; P = 0.003). There was no significant effect on crypt depth or villous width. No effect was observed in HIV positive patients. There were no adverse events attributable to MM.

CONCLUSIONS

MM improved small bowel villous height and absorptive area, but not crypt depth, in adults with EE without HIV. Nutritional intervention may therefore selectively influence villous compartment remodelling. In this small study, there was a clear difference in response depending on HIV status, suggesting that EE with superimposed HIV enteropathy may be a distinct pathophysiological condition.

Cluster-randomised controlled trials of individual and combined water, sanitation, hygiene and nutritional interventions in rural Bangladesh and Kenya: the WASH Benefits study design and rationale

INTRODUCTION

Enteric infections are common during the first years of life in low-income countries and contribute to growth faltering with long-term impairment of health and development. Water quality, sanitation, handwashing and nutritional interventions can independently reduce enteric infections and growth faltering. There is little evidence that directly compares the effects of these individual and combined interventions on diarrhoea and growth when delivered to infants and young children. The objective of the WASH Benefits study is to help fill this knowledge gap.

METHODS AND ANALYSIS

WASH Benefits includes two cluster-randomised trials to assess improvements in water quality, sanitation, handwashing and child nutrition-alone and in combination-to rural households with pregnant women in Kenya and Bangladesh. Geographically matched clusters (groups of household compounds in Bangladesh and villages in Kenya) will be randomised to one of six intervention arms or control. Intervention arms include water quality, sanitation, handwashing, nutrition, combined water+sanitation+handwashing (WSH) and WSH+nutrition. The studies will enrol newborn children (N=5760 in Bangladesh and N=8000 in Kenya) and measure outcomes at 12 and 24 months after intervention delivery. Primary outcomes include child length-for-age Z-scores and caregiver-reported diarrhoea. Secondary outcomes include stunting prevalence, markers of environmental enteropathy and child development scores (verbal, motor and personal/social). We will estimate unadjusted and adjusted intention-to-treat effects using semiparametric estimators and permutation tests.

ETHICS AND DISSEMINATION

Study protocols have been reviewed and approved by human subjects review boards at the University of California, Berkeley, Stanford University, the International Centre for Diarrheal Disease Research, Bangladesh, the Kenya Medical Research Institute, and Innovations for Poverty Action. Independent data safety monitoring boards in each country oversee the trials. This study is funded by a grant from the Bill & Melinda Gates Foundation to the University of California, Berkeley.

REGISTRATION

Trial registration identifiers (http://www.clinicaltrials.gov): NCT01590095 (Bangladesh), NCT01704105 (Kenya).

Intestinal mucosal permeability of children with cefaclor-associated serum sickness-like reactions

Although the serum sickness-like reaction (SSLR) in children after the administration of cefaclor has long been recognized, the exact mechanism of cefaclor-associated SSLR remains unclear. This study aims to investigate the association between intestinal mucosal permeability and cefaclor-associated SSLR in children. A total of 82 pediatric patients with upper respiratory tract infection following the cefaclor therapy was divided into cefaclor-associated SSLR positive group and negative group based on the presence or absence of SSLR after taking cefaclor, and 30 healthy volunteers served as control group. Urinary lactulose/mannitol (L/M) ratios and serum diamine oxidase (DAO) levels were determined in all cases on days 7, 9, 11, 13, and 15 after oral administration of cefaclor. The children in the control group were given the same measurements after enrollment in this study. From days 7 to 13, the urinary L/M ratio of children with cefaclor SSLR gradually increased and reached to the highest level of 0.38 ± 0.14 on day 13. Compared with the cefaclor-associated SSLR negative group and control group, urinary L/M ratios increased significantly in the cefaclor SSLR positive group on days 7, 9, 11, 13, and 15 after taking cefaclor, and serum levels of DAO following the treatment of cefaclor increased significantly in children with cefaclor SSLR on days 9, 11, 13, and 15. No significant difference in urinary L/M ratios and serum levels of DAO between SSLR negative group and control group through the entire experiment was observed. In conclusion, administration of cefaclor may induce SSLR in children by increasing the intestinal mucosal permeability and/or affecting the integrity of the intestinal mucosa. Determinations of urinary L/M ratios and serum DAO levels may be helpful for observing or predicting the occurrence of SSLR after administration of cefaclor, which will encourage physicians to proceed with extreme caution when prescribing cefaclor for pediatric patients.

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.