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

Colonization during a key developmental window reveals microbiota-dependent shifts in growth and immunity during undernutrition

BACKGROUND

Childhood undernutrition is a major global health challenge with devastating lifelong consequences. Linear growth stunting due to undernutrition has been linked to poor health outcomes, and mothers who experience growth stunting in childhood are more likely to give birth to stunted children later in life. Based on these findings, we hypothesized that intergenerational colonization of mice with microbiota from human donors with undernutrition may recapitulate certain immune and growth changes observed in this disorder.

RESULTS

To test this hypothesis, we developed a gnotobiotic murine model of undernutrition using microbiota from human infants with healthy or stunted growth trajectories. Intergenerational colonization with microbiota derived from children with growth stunting lead to less linear growth and the development of immune features of undernutrition and enteropathy, including intestinal villus blunting, lower liver IGF-1 and accumulation of intraepithelial lymphocytes and plasma cells in the small intestine. In contrast, colonization after weaning lead to fewer host phenotypic changes between these distinct microbial communities.

CONCLUSIONS

These results are broadly consistent with previous findings demonstrating that exposure of the immune system to microbial products during the weaning phase is a critical determinant of later life immune function. Overall, our results suggest intergenerational colonization with human microbiota samples is a useful approach with which to investigate microbiota-dependent changes in growth and immunity in early life. Murine models that capture the intergenerational and multifactorial nature of undernutrition are critical to understanding the underlying biology of this disorder. Video Abstract.

The 2022 Vaccines Against Shigella and Enterotoxigenic Escherichia coli (VASE) Conference: Summary of breakout workshops

The global public health nonprofit organization PATH hosted the third Vaccines Against Shigella and Enterotoxigenic Escherichia coli (VASE) Conference in Washington, DC, from November 29 to December 1, 2022. This international gathering focused on cutting-edge research related to the development of vaccines against neglected diarrheal pathogens including Shigella, enterotoxigenic Escherichia coli (ETEC), Campylobacter, and non-typhoidal Salmonella. In addition to the conference's plenary content, the agenda featured ten breakout workshops on topics of importance to the enteric vaccine field. This unique aspect of VASE Conferences allows focused groups of attendees to engage in in-depth discussions on subjects of interest to the enteric vaccine development community. In 2022, the workshops covered a range of topics. Two focused on the public health value of enteric vaccines, with one examining how to translate evidence into policy and the other on the value proposition of potential combination vaccines against bacterial enteric pathogens. Two more workshops explored new tools for the development and evaluation of vaccines, with the first on integrating antigen/antibody technologies for mucosal vaccine and immunoprophylactic development, and the second on adjuvants specifically for Shigella vaccines for children in low- and middle-income countries. Another pair of workshops covered the status of vaccines against two emerging enteric pathogens, Campylobacter and invasive non-typhoidal Salmonella. The remaining four workshops examined the assessment of vaccine impact on acute and long-term morbidity. These included discussions on the nature and severity of intestinal inflammation; cellular immunity and immunological memory in ETEC and Shigella infections; clinical and microbiologic endpoints for Shigella vaccine efficacy studies in children; and intricacies of protective immunity to enteric pathogens. This article provides a brief summary of the presentations and discussions at each workshop in order to share these sessions with the broader enteric vaccine field.

Small Intestine Bacterial Overgrowth is associated with increased Campylobacter and epithelial injury in duodenal biopsies of Bangladeshi children

Small intestine bacterial overgrowth (SIBO) has been associated with enteric inflammation, linear growth stunting, and neurodevelopmental delays in children from low-income countries. Little is known about the histologic changes or epithelial adherent microbiota associated with SIBO. We sought to describe these relationships in a cohort of impoverished Bangladeshi children. Undernourished 12-18-month-old children underwent both glucose hydrogen breath testing for SIBO and duodenoscopy with biopsy. Biopsy samples were subject to both histological scoring and 16s rRNA sequencing. 118 children were enrolled with 16s sequencing data available on 53. Of 11 histological features, we found that SIBO was associated with one, enterocyte injury in the second part of the duodenum (R = 0.21, p = 0.02). SIBO was also associated with a significant increase in Campylobacter by 16s rRNA analysis (Log 2-fold change of 4.43; adjusted p = 1.9 x 10-6). These findings support the growing body of literature showing an association between SIBO and enteric inflammation and enterocyte injury and further delineate the subgroup of children with environmental enteric dysfunction who have SIBO. Further, they show a novel association between SIBO and Campylobacter. Mechanistic work is needed to understand the relationship between SIBO, enterocyte injury, and Campylobacter.

Effects of L-Carnitine Supplementation on the Rate of Weight Gain and Biomarkers of Environmental Enteric Dysfunction in Children with Severe Acute Malnutrition: A Double-Blind Randomized Controlled Clinical Trial

BACKGROUND

Severe acute malnutrition (SAM) is a major public health concern among low- and middle-income countries, where the majority of the children encountering this acute form of malnutrition suffer from environmental enteric dysfunction (EED). However, evidence regarding the effects of L-carnitine supplementation on the rate of weight gain and EED biomarkers in malnourished children is limited.

OBJECTIVES

We aimed to investigate the role of L-carnitine supplementation on the rate of weight gain, duration of hospital stays, and EED biomarkers among children with SAM.

METHODS

A prospective, double-blind, placebo-controlled, randomized clinical trial was conducted at the Nutritional Rehabilitation Unit (NRU) of Dhaka Hospital, International Centre for Diarrheal Disease Research, Bangladesh. Children with SAM aged 9-24 mo were randomly assigned to receive commercial L-carnitine syrup (100 mg/kg/d) or placebo for 15 d in addition to standard of care. A total of 98 children with Weight-for-Length-z-score (WLZ) < -3 Standard deviation were enrolled between October 2021 and March 2023. Analyses were conducted on an intention-to-treat basis.

RESULTS

The primary outcome variable, "rate of weight gain," was comparable between L-carnitine and placebo groups (2.09 ± 2.23 compared with 2.07 ± 2.70; P = 0.973), which was consistent even after adjusting for potential covariates (age, sex, Weight-for-Age z-score, asset index, and WASH practices) through linear regression [ß: 0.37; 95% confidence interval (CI): -0.63,1.37; P = 0.465]. The average hospital stay was ∼4 d. The results of adjusted median regression showed that following intervention, there was no significant difference in the EED biomarkers among the treatment arms; Myeloperoxidase (ng/mL) [ß: -1342.29; 95% CI: -2817.35, 132.77; P = 0.074], Neopterin (nmol/L) [ß: -153.33; 95% CI: -556.58, 249.91; P = 0.452], alpha-1-antitrypsin (mg/mL) [ß: 0.05; 95% CI: -0.15, 0.25; P = 0.627]. Initial L-carnitine (μmol/L) levels (median, interquartile range) for L-carnitine compared with placebo were 54.84 (36.0, 112.9) and 59.74 (45.7, 96.0), whereas levels after intervention were 102.05 (60.9, 182.1) and 105.02 (73.1, 203.7).

CONCLUSIONS

Although our study findings suggest that L-carnitine bears no additional effect on SAM, we recommend clinical trials with a longer duration of supplementation, possibly with other combinations of interventions, to investigate further into this topic of interest. This trial was registered at clinicaltrials.gov as NCT05083637.

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

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

Gut microbiota shifts favorably with delivery of handwashing with soap and water treatment intervention in a prospective cohort (CHoBI7 trial)

BACKGROUND

Cholera can result in the expulsion of important microbiota from the gut and result in death if left untreated. The disease transmits mainly via drinking water carrying Vibrio cholerae; and household contacts (HHC) of cholera patients are at elevated risk during the first week of infection. The gut microbiota profiles of HHC-children of cholera patients at Dhaka city slums were investigated before (day 0) and after (day 8) delivery of chlorinated water as part of the major study 'CHoBI7 trial (cholera-hospital-based intervention for 7 days)'.

RESULT

Results of sequencing and analysis of bacterial community DNA revealed the predominance of two bacterial phyla: Bacteroidetes and Firmicutes at day 0 with a relative abundance of 62 ± 6 (mean ± SEM%) and 32 ± 7, respectively. The pattern reversed at day 8 with a decreased relative abundance of Bacteroidetes (39 ± 12; p = 0.034) and an increased abundance of Firmicutes (49 ± 12; p = 0.057). Of 65 bacterial families confirmed at day 0, six belonging to Proteobacteria including Vibrionaceae disappeared at day 8. Interestingly, the relative abundance of four Firmicutes families-Lachnospiraceae, Bifidobacteriaceae, Clostridiaceae, and Ruminococcaceae was increased in all five study children at day 8.

CONCLUSION

The observed exclusion of pathogenic Proteobacteria and enhancement of beneficial Firmicutes in the gut of children delivered with chlorinated water as part of WASH intervention reflect a great promise of the CHoBI7 program in preventing cholera and improving child health.

Harnessing the power of probiotics to enhance neuroplasticity for neurodevelopment and cognitive function in stunting: a comprehensive review

BACKGROUND

Stunting become a global concern because it's not only affecting physical stature, but also affecting on neurodevelopment and cognitive function. These impacts are resulting in long-term consequences especially for human resources, such as poor-quality labor, decreased productivity due to decreasing of health quality, including immunity and cognitive aspect.

DISCUSSION

This comprehensive review found that based on many studies, there is an altered gut microbiota, or dysbiosis, in stunted children, causing the impairment of brain development through Microbiota-Gut Brain Axis (MGB Axis) mechanism. The administration of probiotics has been known affect MGBA by improving the physical and chemical gut barrier integrity, producing antimicrobial substance to inhibit pathogen, and recovering the healthy gut microbiota. Probiotics, along with healthy gut microbiota, produce SCFAs which have various positive impact on CNS, such as increase neurogenesis, support the development and function of microglia, reduce inflammatory signaling, improve the Blood Brain Barrier's (BBB's) integrity, produce neurotropic factors (e.g. BDNF, GDNF), and promote the formation of new synapse. Probiotics also could induce the production of IGF-1 by intestinal epithelial cells, which functioned as growth factor of multiple body tissues and resulted in improvement of linear growth as well as brain development.

CONCLUSION

These properties of probiotics made it become the promising and feasible new treatment approach for stunting. But since most of the studies in this field are conducted in animal models, it is necessary to translate animal data into human models and do additional study to identify the numerous components in the MGB axis and the effect of probiotics on human.

Shigella and childhood stunting: Evidence, gaps, and future research directions

Early childhood growth deficits have been shown to have lifelong health and economic impacts, yet their connection to one of their underlying causes, diarrheal diseases, has remained difficult to characterize. Identifying the processes and mechanisms that underlie this link has remained a challenge due to the complexity of the relationship and limitations in access to more advanced laboratory methods. In recent years, however, several large-scale, multisite studies have extensively investigated and reported the prevalence, etiology, and impacts of diarrheal diseases in children under 5 years (CU5) in low- to middle-income countries (LMICs). These studies, in combination with several single-site studies, have applied more advanced laboratory methods to uncover the etiology, true prevalence, infection mechanisms, and inflammation biomarkers of diarrheal disease. Of the multiple pathogens that have been shown to be strongly associated with diarrheal disease in CU5, Shigella is one of the more prevalent and impactful of these pathogens. In this narrative review, we highlight key insights from these studies and identify knowledge gaps and directions for future research. According to these studies, Shigella is most commonly detected in toddlers and young children; however, it can cause more severe disease and has a greater impact on linear growth for infants. Shigella often has a stronger relationship to linear growth faltering (LGF) than other enteropathogens, with higher Shigella loads resulting in greater growth deficits. Future studies should employ more Shigella-specific molecular assays and identify diarrheal etiologies using standardized diagnostics to improve child anthropometric and Shigella surveillance. Also, they should focus on uncovering the mechanisms of the relationship underlying Shigella and growth faltering to better characterize the role of asymptomatic infections and intestinal inflammation in this relationship.

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

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

Factors Associated with Carriage of Enteropathogenic and Non-Enteropathogenic Viruses: A Reanalysis of Matched Case-Control Data from the AFRIBIOTA Site in Antananarivo, Madagascar

Environmental Enteric Dysfunction (EED) is an associate driver of stunting in poor settings, and intestinal infections indirectly contribute to the pathophysiology underlying EED. Our work aimed at assessing whether enteric viral carriage is determinant to stunting. A total of 464 healthy and asymptomatic children, aged 2 to 5 years, were recruited, and classified as non-stunted, moderately stunted, or severely stunted. Among the recruited children, 329 stool samples were obtained and screened for enteric and non-enteric viruses by real-time polymerase chain reaction. We statistically tested for the associations between enteric viral and potential risk factors. Approximately 51.7% of the stool samples were positive for at least one virus and 40.7% were positive for non-enteric adenoviruses. No statistical difference was observed between virus prevalence and the growth status of the children. We did not find any statistically significant association between viral infection and most of the socio-demographic risk factors studied, except for having an inadequate food quality score or an over-nourished mother. In addition, being positive for Ascaris lumbricoides was identified as a protective factor against viral infection. In conclusion, we did not find evidence of a direct link between stunting and enteropathogenic viral carriage in our population.

Colonization during a key developmental window reveals microbiota-dependent shifts in growth and immunity during undernutrition

Childhood undernutrition is a major global health challenge with devastating lifelong consequences. Linear growth stunting due to undernutrition has been linked to poor outcomes, and mothers who experience stunting are more likely to give birth to stunted children. Murine models that capture the intergenerational and multifactorial nature of undernutrition are critical to understanding the underlying biology of this disorder. Here we report a gnotobiotic mouse model of undernutrition using microbiota from human infants with healthy or stunted growth trajectories. Intergenerational transmission of microbiota from parents to offspring leads to the development of growth and immune features of undernutrition and enteropathy, including reduced linear growth, intestinal villus blunting and accumulation of intraepithelial lymphocytes. In contrast, colonization after weaning reduces sensitivity to detect changes driven by distinct microbial communities. Overall, these results suggest intergenerational colonization is a useful approach with which to investigate microbiota-dependent growth and immunity in early life.

The Effects of Yogurt Supplementation and Nutritional Education on Malnourished Infants: A Pilot RCT in Dhaka's Slums

Our objective was to quantify the effects of yogurt supplementation and nutrition education over three months on the linear growth of infants at risk of stunting. We conducted a three-arm pilot randomized controlled trial: (1) nutrition education for mothers; (2) nutrition education plus a daily yogurt supplement (50 g) for the index child; and (3) usual care (control). Dyads of children aged 4-6 months and at risk of stunting [length-for-age z-score (LAZ) ≤ -1 SD and >-2 SD] and their mothers with ≤10 years of education were eligible for the study. Participants were recruited from five slum areas in Dhaka, Bangladesh. Intention-to-treat (N = 162) and complete-case analyses (N = 127) showed no between-group statistically significant differences in LAZ or weight-for-age (WAZ). However, the yogurt group showed greater change in linear growth compared to the control (LAZ: mean difference 0.20, 95% CI: -0.06, 0.47, p-value 0.13), which was also slightly greater than the education-only group. Children in the yogurt plus group were five times (95% CI: 0.80, 31.80, p-value 0.09) more likely to meet the minimum dietary diversity (MDD) score compared to the control. A 3-month follow-up of this pilot study did not demonstrate that yogurt was beneficial to linear growth. However, there were encouraging trends that merit replication of the intervention with larger samples and longer follow-ups.

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

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

Consequences of Shigella infection in young children: a systematic review

OBJECTIVES

We conducted a systematic review of the longitudinal consequences of Shigella infection in children to inform the value proposition for an effective vaccine.

METHODS

We searched PubMed and Embase for studies published from January 01, 1980 to December 12, 2022 and conducted in low- and middle-income countries that included longitudinal follow-up after Shigella detection among children aged <5 years, irrespective of language. We collected data on all outcomes subsequent to Shigella detection, except mortality.

RESULTS

Of 2627 papers identified, 52 met inclusion criteria. The median sample size of children aged <5 years was 66 (range 5-2172). Data were collected in 20 countries; 56% (n = 29) of the publications included Bangladesh. The most common outcomes related to diarrhea (n = 20), linear growth (n = 14), and the mean total cost of a Shigella episode (n = 4; range: $ 6.22-31.10). Among children with Shigella diarrhea, 2.9-61.1% developed persistent diarrhea (≥14 days); the persistence was significantly more likely among children who were malnourished, had bloody stool, or had multidrug-resistant Shigella. Cumulative Shigella infections over the first 2 years of life contributed to the greatest loss in length-for-age z-score.

CONCLUSION

We identified evidence that Shigella is associated with persistent diarrhea, linear growth faltering, and economic impact to the family.

Environmental enteric dysfunction: gut and microbiota adaptation in pregnancy and infancy

Environmental enteric dysfunction (EED) is a subclinical syndrome of intestinal inflammation, malabsorption and barrier disruption that is highly prevalent in low- and middle-income countries in which poverty, food insecurity and frequent exposure to enteric pathogens impair growth, immunity and neurodevelopment in children. In this Review, we discuss advances in our understanding of EED, intestinal adaptation and the gut microbiome over the 'first 1,000 days' of life, spanning pregnancy and early childhood. Data on maternal EED are emerging, and they mirror earlier findings of increased risks for preterm birth and fetal growth restriction in mothers with either active inflammatory bowel disease or coeliac disease. The intense metabolic demands of pregnancy and lactation drive gut adaptation, including dramatic changes in the composition, function and mother-to-child transmission of the gut microbiota. We urgently need to elucidate the mechanisms by which EED undermines these critical processes so that we can improve global strategies to prevent and reverse intergenerational cycles of undernutrition.

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

BACKGROUND

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

METHODOLOGY

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

FINDINGS

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

CONCLUSIONS

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

Parasites and childhood stunting - a mechanistic interplay with nutrition, anaemia, gut health, microbiota, and epigenetics

Globally, stunting affects approximately 149.2 million children under 5 years of age. The underlying aetiology and pathophysiological mechanisms leading to stunting remain elusive, and therefore few effective treatment and prevention strategies exist. Crucial evidence directly linking parasites to stunting is often lacking - in part due to the complex nature of stunting, as well as a lack of critical multidisciplinary research amongst key age groups. Here, based on available studies, we present potential mechanistic pathways by which parasitic infection of mother and/or infant may lead to childhood stunting. We highlight the need for future multidisciplinary longitudinal studies and clinical trials aimed at elucidating the most influential factors, and synergies therein, that can lead to stunting, and ultimately towards finding solutions to successfully mitigate against it.

Acknowledging the gap: a systematic review of micronutrient supplementation in infants under six months of age

Background: Micronutrient deficiencies remain common worldwide, but the consequences to growth and development in early infancy (under six months of age) are not fully understood. We present a systematic review of micronutrient interventions in term infants under six months of age, with a specific focus on iron supplementation. Methods: We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (Ovid) and Embase (Ovid) from January 1980 through December 2019. Interventions included iron or multiple micronutrients (MMNs). Results: Of 11,109 records identified, 33 publications from 24 trials were included (19 iron and five MMN supplementation trials). All but one trial (evaluating only morbidity and mortality) evaluated the effect of supplementation on biochemical outcomes, ten reported on growth, 15 on morbidity and/or mortality and six on neuro-behavioural development. Low- and middle- income countries made up 88% (22/25) of the total trial locations. Meta-analysis was not possible due to extensive heterogeneity in both exposure and outcome measures.  However, these trials indicated that infants less than six months of age benefit biochemically from early supplementation with iron, but the effect of additional nutrients or MMNs, along with the impacts on growth, morbidity and/or mortality, and neuro-behavioural outcomes remain unclear. Conclusions: Infants less than six months of age appear to benefit biochemically from micronutrient supplementation. However, well-powered randomised controlled trials are required to determine whether routine supplementation with iron or MMNs containing iron should commence before six months of life in exclusively breast-fed infants in low-resource settings.

Acknowledging the gap: a systematic review of micronutrient supplementation in infants under six months of age

Background: Micronutrient deficiencies remain common worldwide, but the consequences to growth and development in early infancy (under six months of age) are not fully understood. We present a systematic review of micronutrient interventions in term infants under six months of age, with a specific focus on iron supplementation. Methods: We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (Ovid) and Embase (Ovid) from January 1980 through December 2019. Interventions included iron or multiple micronutrients (MMNs). Results: Of 11,109 records identified, 32 publications from 23 trials were included (18 iron and five MMN supplementation trials). All 23 trials evaluated the effect of supplementation on biochemical outcomes, ten reported on growth, 14 on morbidity and/or mortality and six on neuro-behavioural development. Low- and middle- income countries made up 88% (21/24) of the total trial locations. Meta-analysis was not possible due to extensive heterogeneity in both exposure and outcome measures.  However, these trials indicated that infants less than six months of age benefit biochemically from early supplementation with iron, but the effect of additional nutrients or MMNs, along with the impacts on growth, morbidity and/or mortality, and neuro-behavioural outcomes remain unclear. Conclusions: Infants less than six months of age appear to benefit biochemically from micronutrient supplementation. However, well-powered randomised controlled trials are required to determine whether routine supplementation with iron or MMNs containing iron should commence before six months of life in exclusively breast-fed infants in low-resource settings.

Ready-to-Use Therapeutic Foods Fail to Improve Vitamin A and Iron Status Meaningfully during Treatment for Severe Acute Malnutrition in 6-59-Month-old Cambodian Children

Severe acute malnutrition (SAM) remains a global health concern. Studies on the impact of ready-to-use therapeutic foods (RUTFs) on micronutrient status during SAM treatment are almost nonexistent. The objective was to investigate the impact of RUTFs on the iron and vitamin A status of 6-59-month-old children receiving SAM treatment. Biomarkers of vitamin A status (retinol-binding protein, RBP), iron status (ferritin and soluble transferrin receptor, sTfR), and inflammation (C-reactive protein, CRP, and alpha-1 acid glycoprotein, AGP) were collected at admission and discharge (week 8) during an RUTF effectiveness trial. Vitamin A deficiency was defined as RBP <0.70 µmol/L, low body iron as body iron (BI) <0 mg/kg and deficient iron stores as ferritin <12 µg/L. Data were available for 110 and 75 children at admission and discharge, respectively. There was no significant difference in haemoglobin, ferritin, sTfR, BI or RBP concentrations between admission and discharge. At discharge, BI was 0.2 mg/kg lower, and there was a tendency towards a slightly lower RBP concentration, but the prevalence of vitamin A deficiency was low at admission and discharge (6% and 3%, respectively). The small impact of both RUTFs on improving vitamin A and iron status during SAM treatment calls for further research on the bioavailability of micronutrients to enhance the effectiveness of SAM treatment on micronutrient status.

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

Introduction

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

Methods

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

Results

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

Conclusion

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

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Maternal and child FUT2 and FUT3 status demonstrate relationship with gut health, body composition and growth of children in Bangladesh

Fucosyltransferase 2 (FUT2) and 3 (FUT3) may influence host biological functions. We aim to assess the relationship between maternal and child FUT2 (Secretor) and FUT3 (Lewis) status with growth, body composition, gut health and histologic features in Bangladeshi children. We conducted a case-control study where secretor and Lewis status were ascertained from saliva samples of 408 mother-child dyads. Upper-arm fat area estimate (UFE) and total upper arm area (TUA) were found higher among children of Lewis negative mothers (p = 0.01 and p = 0.07, respectively). Changes in UFE after nutrition intervention were significantly greater among Lewis positive children than those of negative for Lewis (p = 0.05). Significant differences were observed for child UFE based on secretor and Lewis status of the mothers (p = 0.04). Lewis positive children had greater changes in WAZ (p = 0.07) and WLZ (p = 0.02) than Lewis negative children at the end of nutrition intervention. Fecal Reg1B was elevated in secretor positive children compared to their counterparts (p = 0.03). Lewis negative children had higher concentrations of MPO compared to Lewis positive children (p = 0.08). We also observed a higher frequency of subtotal villous atrophy among secretor negative and Lewis positive children (p = 0.09 and p = 0.01, respectively) than those of their counterparts. The findings provide insights for further studies to elucidate causal influences.

The Childhood Acute Illness and Nutrition (CHAIN) network nested case-cohort study protocol: a multi-omics approach to understanding mortality among children in sub-Saharan Africa and South Asia

Introduction: Many acutely ill children in low- and middle-income settings have a high risk of mortality both during and after hospitalisation despite guideline-based care. Understanding the biological mechanisms underpinning mortality may suggest optimal pathways to target for interventions to further reduce mortality. The Childhood Acute Illness and Nutrition (CHAIN) Network ( www.chainnnetwork.org) Nested Case-Cohort Study (CNCC) aims to investigate biological mechanisms leading to inpatient and post-discharge mortality through an integrated multi-omic approach. Methods and analysis; The CNCC comprises a subset of participants from the CHAIN cohort (1278/3101 hospitalised participants, including 350 children who died and 658 survivors, and 270/1140 well community children of similar age and household location) from nine sites in six countries across sub-Saharan Africa and South Asia. Systemic proteome, metabolome, lipidome, lipopolysaccharides, haemoglobin variants, toxins, pathogens, intestinal microbiome and biomarkers of enteropathy will be determined. Computational systems biology analysis will include machine learning and multivariate predictive modelling with stacked generalization approaches accounting for the different characteristics of each biological modality. This systems approach is anticipated to yield mechanistic insights, show interactions and behaviours of the components of biological entities, and help develop interventions to reduce mortality among acutely ill children. Ethics and dissemination. The CHAIN Network cohort and CNCC was approved by institutional review boards of all partner sites. Results will be published in open access, peer reviewed scientific journals and presented to academic and policy stakeholders. Data will be made publicly available, including uploading to recognised omics databases. Trial registration NCT03208725.

Minimally invasive biomarkers in human and non-human primate evolutionary biology: Tools for understanding variation and adaptation

BACKGROUND

The use of minimally invasive biomarkers (MIBs - physiological biomarkers obtained from minimally invasive sample types) has expanded rapidly in science and medicine over the past several decades. The MIB approach is a methodological strength in the field of human and non-human primate evolutionary biology (HEB). Among humans and our closest relatives, MIBs provide unique opportunities to document phenotypic variation and to operationalize evolutionary hypotheses.

AIMS

This paper overviews the use of MIBs in HEB. Our objectives are to (1) highlight key research topics which successfully implement MIBs, (2) identify promising yet under-investigated areas of MIB application, and (3) discuss current challenges in MIB research, with suggestions for advancing the field.

DISCUSSION AND CONCLUSIONS

A range of MIBs are used to investigate focal topics in HEB, including energetics and life history variation/evolution, developmental plasticity, and social status and dominance relationships. Nonetheless, we identify gaps in existing MIB research on traits such as physical growth and gut function that are central to the field. Several challenges remain for HEB research using MIBs, including the need for additional biomarkers and methods of assessment, robust validations, and approaches that are standardized across labs and research groups. Importantly, researchers must provide better support for adaptation and fitness effects in hypothesis testing (e.g., by obtaining complementary measures of energy expenditure, demonstrating redundancy of function, and performing lifetime/longitudinal analyses). We point to continued progress in the use of MIBs in HEB to better understand the past, present, and future of humans and our closest primate relatives.

Single-cell profiling of environmental enteropathy reveals signatures of epithelial remodeling and immune activation

Environmental enteropathy (EE) is a subclinical condition of the small intestine that is highly prevalent in low- and middle-income countries. It is thought to be a key contributing factor to childhood malnutrition, growth stunting, and diminished oral vaccine responses. Although EE has been shown to be the by-product of a recurrent enteric infection, its full pathophysiology remains unclear. Here, we mapped the cellular and molecular correlates of EE by performing high-throughput, single-cell RNA-sequencing on 33 small intestinal biopsies from 11 adults with EE in Lusaka, Zambia (eight HIV-negative and three HIV-positive), six adults without EE in Boston, United States, and two adults in Durban, South Africa, which we complemented with published data from three additional individuals from the same clinical site. We analyzed previously defined bulk-transcriptomic signatures of reduced villus height and decreased microbial translocation in EE and showed that these signatures may be driven by an increased abundance of surface mucosal cells-a gastric-like subset previously implicated in epithelial repair in the gastrointestinal tract. In addition, we determined cell subsets whose fractional abundances associate with EE severity, small intestinal region, and HIV infection. Furthermore, by comparing duodenal EE samples with those from three control cohorts, we identified dysregulated WNT and MAPK signaling in the EE epithelium and increased proinflammatory cytokine gene expression in a T cell subset highly expressing a transcriptional signature of tissue-resident memory cells in the EE cohort. Together, our work elucidates epithelial and immune correlates of EE and nominates cellular and molecular targets for intervention.

The Shigella Vaccines Pipeline

Shigella is the leading cause of global diarrheal deaths that currently lacks a licensed vaccine. Shigellosis drives antimicrobial resistance and leads to economic impact through linear growth faltering. Today, there is a robust pipeline of vaccines in clinical development which are broadly divided into parenteral glycoconjugate vaccines, consisting of O-antigen conjugated to carrier proteins, and oral live attenuated vaccines, which incorporate targeted genetic mutations seeking to optimize the balance between reactogenicity, immunogenicity and ultimately protection. Proof of efficacy has previously been shown with both approaches but for various reasons no vaccine has been licensed to date. In this report, we outline the requirements for a Shigella vaccine and describe the current pipeline in the context of the many candidates that have previously failed or been abandoned. The report refers to papers from individual vaccine developers in this special supplement of Vaccines which is focused on Shigella vaccines. Once readouts of safety and immunogenicity from current trials of lead candidate vaccines among the target population of young children in low- and middle-income countries are available, the likely time to licensure of a first Shigella vaccine will become clearer.

Infection With Escherichia Coli Pathotypes Is Associated With Biomarkers of Gut Enteropathy and Nutritional Status Among Malnourished Children in Bangladesh

Escherichia coli (E. coli) pathotypes are the most common cause of diarrhea, especially in developing countries. Environmental Enteric Dysfunction (EED) is presumed to be the result of infection with one or more pathotypes and can affect intestinal health and childhood growth. We sought to investigate the association of E. coli pathotypes infection with biomarkers of EED and nutritional status among slum-dwelling malnourished children in Bangladesh. This study comprised a total of 1050 stunted and at risk of stunting children. TaqMan Array Card assays were used to determine the presence of E. coli pathotypes in feces. Prevalence of infection with EAEC was highest (68.8%) in this cohort of children, followed by EPEC (55.9%), ETEC (44%), Shigella/EIEC (19.4%) and STEC (3.2%). The levels of myeloperoxidase and calprotectin were significantly higher in EAEC (P=0.02 and P=0.04), EPEC (P=0.02 and P=0.03) and Shigella/EIEC (P=0.05 and P=0.02) positive participants while, only calprotectin was significantly higher in ETEC (P=0.01) positive participants. Reg1B was significantly higher in participants with EAEC (P=0.004) while, neopterin levels were significantly lower in ETEC (P=0.003) and Shigella/EIEC (P=0.003) positive cases. A significant positive relationship was observed between EAEC and fecal levels of Reg1B (β = 0.28; 95% CI = 0.12, 0.43; p-value<0.001). Besides, ETEC was found to be positively and significantly associated with the levels of calprotectin (β = 0.14; 95 percent CI = 0.01, 0.26; p-value=0.037) and negatively with neopterin (β = -0.16; 95% CI = -0.30, -0.02; p-value=0.021). On the other hand, infection with EPEC was found to be negatively associated with length-for-age (β = -0.12; 95% CI = -0.22, -0.03; p-value=0.011) and weight-for-age (β = -0.11; 95% CI = -0.22, -0.01; p-value=0.037). The study findings suggest that infection with certain E. coli pathotypes (EAEC and ETEC) influences gut health and EPEC is associated with linear growth and underweight in Bangladeshi children.

The Childhood Acute Illness and Nutrition (CHAIN) network nested case-cohort study protocol: a multi-omics approach to understanding mortality among children in sub-Saharan Africa and South Asia

Introduction: Many acutely ill children in low- and middle-income settings have a high risk of mortality both during and after hospitalisation despite guideline-based care. Understanding the biological mechanisms underpinning mortality may suggest optimal pathways to target for interventions to further reduce mortality. The Childhood Acute Illness and Nutrition (CHAIN) Network ( www.chainnnetwork.org) Nested Case-Cohort Study (CNCC) aims to investigate biological mechanisms leading to inpatient and post-discharge mortality through an integrated multi-omic approach. Methods and analysis; The CNCC comprises a subset of participants from the CHAIN cohort (1278/3101 hospitalised participants, including 350 children who died and 658 survivors, and 270/1140 well community children of similar age and household location) from nine sites in six countries across sub-Saharan Africa and South Asia. Systemic proteome, metabolome, lipidome, lipopolysaccharides, haemoglobin variants, toxins, pathogens, intestinal microbiome and biomarkers of enteropathy will be determined. Computational systems biology analysis will include machine learning and multivariate predictive modelling with stacked generalization approaches accounting for the different characteristics of each biological modality. This systems approach is anticipated to yield mechanistic insights, show interactions and behaviours of the components of biological entities, and help develop interventions to reduce mortality among acutely ill children. Ethics and dissemination. The CHAIN Network cohort and CNCC was approved by institutional review boards of all partner sites. Results will be published in open access, peer reviewed scientific journals and presented to academic and policy stakeholders. Data will be made publicly available, including uploading to recognised omics databases. Trial registration NCT03208725.

Changes in Systemic Regulatory T Cells, Effector T Cells, and Monocyte Populations Associated With Early-Life Stunting

Stunting and environmental enteric dysfunction (EED) may be responsible for altered gut and systemic immune responses. However, their impact on circulating immune cell populations remains poorly characterized during early life. A detailed flow cytometry analysis of major systemic immune cell populations in 53 stunted and 52 non-stunted (2 to 5 years old) children living in Antananarivo (Madagascar) was performed. Compared to age-matched non-stunted controls, stunted children aged 2-3 years old had a significantly lower relative proportion of classical monocytes. No significant associations were found between stunting and the percentages of effector T helper cell populations (Th1, Th2, Th17, Th1Th17, and cTfh). However, we found that HLA-DR expression (MFI) on all memory CD4⁺ or CD8⁺ T cell subsets was significantly lower in stunted children compared to non-stunted controls. Interestingly, in stunted children compared to the same age-matched non-stunted controls, we observed statistically significant age-specific differences in regulatory T cells (Treg) subsets. Indeed, in 2- to 3-year-old stunted children, a significantly higher percentage of memory Treg, whilst a significantly lower percentage of naive Treg, was found. Our results revealed that both innate and adaptive systemic cell percentages, as well as activation status, were impacted in an age-related manner during stunting. Our study provides valuable insights into the understanding of systemic immune system changes in stunted children.

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

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

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

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

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

Gut–brain Axis: Impact of Intestinal Inflammation and Micronutrient Deficiency on Psychomotor Development and Cognitive Functions in Egyptian Children with UndernutritionGut–brain Axis: Impact of Intestinal Inflammation and Micronutrient Deficiency on Psychomotor Development and Cognitive Functions in Egyptian Children with Undernutrition

Cognitive impairment, growth faltering and stunting are pervasive in many countries. mostly causes are unknown. Role of intestinal inflammation in such cases should be minded especially in low- and middle-income countries. We assessed serum markers of inflammation, fecal markers of intestinal inflammation and serum micronutrients in cases with aged 1 to 10 years who suffer from moderate or severe malnutrition “weight-for-age z-score and height-for-age z- Score (WAZ or HAZ) less than -2 SD”. Cognitive abilities were assessed using Wechsler intelligence scale for preschool and school children, Bayley scale III. 55.6% of preschool cases were below average or had mild or moderate intelligence retardation while 24.5% of school cases and 5% of children below 2 years were below average regarding cognitive functions. Cases showed statistically significant reduction of vitamin D, zinc and iron as compared to control. Serum markers of inflammation (alpha 1- glycoprotein (a1-AGP), endotoxin core protein (EndoCAB)) and fecal markers of intestinal inflammation (alpha 1 antitrypsin (AAT) and neopterin (NEOP)) were significant higher in cases than controls. School children showed negative correlation between processing functions and( a1-AGP), positive correlation between perceptual reasoning and serum vitamin A. Children below 2 years, showed negative correlations between motor function and (AAT), (a1-AGP), tumor necrosis factor- alpha (TNF-a) and (EndoCAB), positive correlation between language and serum zinc. In conclusion, our study showed impaired neurocognitive and psychomotor functions in malnourished stunted children. Also, vitamins and minerals deficiency and increased markers of intestinal inflammation were observed in cases compared to healthy control.

PRObiotics and SYNbiotics to improve gut health and growth in infants in western Kenya (PROSYNK Trial): study protocol for a 4-arm, open-label, randomised, controlled trial

Background

Malnutrition amongst under-fives remains common in resource-poor countries and is resistant to current interventions. New opportunities have emerged to target “environmental enteric dysfunction” (EED) that refers to the abnormal gut structure and function that results from colonisation of the gut with pathogenic microbes and compromises nutrition and growth in early life. Although the gut microbiome may provide a defence against ingested gut pathogens through colonisation resistance, its development is adversely affected by multiple environmental factors. Dietary supplements of pro- or synbiotics may build the resilience of the gut microbiome against these environmental factors and boost colonisation resistance. We aim to assess whether dietary supplementation of newborns in rural Kenya with pro/synbiotics prevents or ameliorates EED and improves growth.

Methods

Six hundred newborns less than 4 days old will be recruited from Homa Bay County Teaching and Referral Hospital, western Kenya. Newborns will be randomly allocated, stratified by HIV exposure, in a 1:1:1:1 ratio to one of 4 study arms to receive either of two synbiotics, a probiotic or no supplement. Supplements will be given daily for 10 days and then weekly until 6 months of age. Participants will be followed until the age of 2 years. The primary outcome is systemic inflammation at 6 months assessed by plasma alpha-1-acid glycoprotein. Secondary outcomes include biomarkers of gut health and growth, anthropometric indices, morbidity and mortality.

Discussion

As dietary supplements with pro- or synbiotics may improve gut health and can be administered in early life, our findings may inform the package of interventions to prevent malnutrition and improve growth in Africa and similar low-resource settings.

Trial registration

Pan African Clinical Trials Registry, Trial number: PACTR202003893276712. Date: 02/03/2020 https://pactr.samrc.ac.za/TrialDisplay.aspx?TrialID=9798

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-022-06211-1.

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

Background

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

Methods

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

Results

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

Conclusion

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

Reduced infant rhesus macaque growth rates due to environmental enteric dysfunction and association with histopathology in the large intestine

Environmental enteric dysfunction is associated with malnutrition as well as infant growth stunting and has been classically defined by villous blunting, decreased crypt-to-villus ratio, and inflammation in the small intestine. Here, we characterized environmental enteric dysfunction among infant rhesus macaques that are naturally exposed to enteric pathogens commonly linked to human growth stunting. Remarkably, despite villous atrophy and histological abnormalities observed in the small intestine, poor growth trajectories and low serum tryptophan levels were correlated with increased histopathology in the large intestine. This work provides insight into the mechanisms underlying this disease and indicates that the large intestine may be an important target for therapeutic intervention.

Environmental enteric dysfunction (EED), a subclinical disorder of intestinal function, is associated with malnutrition, infant growth stunting and pathologies in the small intestine. Here the authors report that infant rhesus macaques that are naturally exposed to enteric pathogens commonly linked to human growth stunting present with EED and growth faltering that associates with large intestine pathologies.

Nutrition and Food Security in Bangladesh: Achievements, Challenges, and Impact of the COVID-19 Pandemic

BACKGROUND

Bangladesh has experienced remarkable transformation in demographic, health, and nutritional status of the population. The changes have exposed the population to a number of challenges, the detrimental effect of which on health and nutrition is likely to be increased by the coronavirus disease 2019 (COVID-19) pandemic. We provide an overview of health and nutritional challenges in Bangladesh in relation to demographic transition and the COVID-19 pandemic.

METHODS

We identified and reviewed recent reports, published articles, and pertinent gray literature on nutrition and food security in Bangladesh to provide historical and contextual information.

RESULTS

The review identifies the progress as well as existing burden regarding nutrition and food security in Bangladesh and highlights the challenges in the coming days in regard to population growth and the COVID-19 pandemic. The country is on track to reduce all forms of childhood undernutrition, while the proportion of nutrition-related noncommunicable diseases is rising owing to changes in dietary intake, low physical activity, and sedentary lifestyle.

CONCLUSIONS

Despite remarkable progress, health and nutritional status of the population in Bangladesh faces challenges, particularly in relation to demographic transition and compounded by the COVID-19 pandemic, which require concerted attention from policymakers as well as stakeholders.

Serum Biomarkers of Environmental Enteric Dysfunction and Growth Perspective in Egyptian Children

BACKGROUND: Environmental enteric dysfunction (EED) is a chronic subclinical condition, contributed to limited sources and poor countries. EED pathology is concerned with small intestine structure and function, which affect the macronutrients and micronutrients absorption with consequent growth faltering. AIM: This study aimed to evaluate some serum biomarkers involved in EED and determine their association with stunting and faltering growth in children; zonulin, endotoxin core antibody (EndoCAb), high-sensitive C-reactive protein (hsCRP), alpha-1-acid glycoprotein (AGP), and tumor necrosis factor (TNF), serum iron, and Vitamins A and D. PATIENTS AND METHODS: This case–control study enrolled 105 children aged from 1 to 10 years old, having weight-for-age z-scores and height-for-age z-scores (WAZ or HAZ) ranging from −1.5 to −2. They were compared with control group consisted of 100 children having WAZ or HAZ > −1 of matched age and sex. Assessment of serum markers levels of enteric dysfunction (zonulin and EndoCAb), markers of systemic inflammation (Hs CRP and AGP), along with serum micronutrients (vitamin A, vitamin D and iron) in children with malnutrition in comparison to controls. RESULTS: There was a highly significant decrease as regarding the anthropometric measurements; weight, height, BMI, and arm circumference. Moreover, significant increase in serum zonulin, EndoCAb, HsCRP, and AGP and highly significant decrease of serum Vitamin D and iron in cases group as compared to control group. Height Z score showed negative correlation with zonulin, HsCRP, and AGP and positive correlation with Vitamin D. Weight Z score showed negative correlation with zonulin, HsCRP, and AGP and positive correlation with Vitamin D and Vitamin A. Regression analysis noted increase of zonulin and α1AGP as high associative markers with height Z score affection, however, increase of zonulin was high associative markers with weight Z score affection. CONCLUSION: Faltering growth is associated with elevated serum systemic markers of intestinal inflammation (HsCRP and α1AGP). EED may be a cause of faltering growth.

Bile Acid Profiling Reveals Distinct Signatures in Undernourished Children with Environmental Enteric Dysfunction

BACKGROUND

Intestinal inflammation and malabsorption in environmental enteric dysfunction (EED) are associated with early childhood growth faltering in impoverished settings worldwide.

OBJECTIVES

The goal of this study was to identify candidate biomarkers associated with inflammation, EED histology, and as predictors of later growth outcomes by focusing on the liver-gut axis by investigating the bile acid metabolome.

METHODS

Undernourished rural Pakistani infants (n = 365) with weight-for-height Z score (WHZ) < -2 were followed up to the age of 24 mo and monitored for growth, infections, and EED. Well-nourished local children (n = 51) were controls, based on consistent WHZ > 0 and height-for-age Z score (HAZ) > -1 on 2 consecutive visits at 3 and 6 mo. Serum bile acid (sBA) profiles were measured by tandem MS at the ages of 3-6 and 9 mo and before nutritional intervention. Biopsies and duodenal aspirates were obtained following upper gastrointestinal endoscopy from a subset of children (n = 63) that responded poorly to nutritional intervention. BA composition in paired plasma and duodenal aspirates was compared based on the severity of EED histopathological scores and correlated to clinical and growth outcomes.

RESULTS

Remarkably, >70% of undernourished Pakistani infants displayed elevated sBA concentrations consistent with subclinical cholestasis. Serum glycocholic acid (GCA) correlated with linear growth faltering (HAZ, r = -0.252 and -0.295 at the age of 3-6 and 9 mo, respectively, P <0.001) and biomarkers of inflammation. The proportion of GCA positively correlated with EED severity for both plasma (rs = 0.324 P = 0.02) and duodenal aspirates (rs = 0.307 P = 0.06) in children with refractory wasting that underwent endoscopy, and the proportion of secondary BA was low in both undernourished and EED children.

CONCLUSIONS

Dysregulated bile acid metabolism is associated with growth faltering and EED severity in undernourished children. Restoration of intestinal BA homeostasis may offer a novel therapeutic target for undernutrition in children with EED. This trial was registered at clinicaltrials.gov as NCT03588013.

Benefits and Risks of Smallholder Livestock Production on Child Nutrition in Low- and Middle-Income Countries

Livestock production may improve nutritional outcomes of pregnant women and children by increasing household income, availability of nutrient-dense foods, and women's empowerment. Nevertheless, the relationship is complex, and the nutritional status of children may be impaired by presence of or proximity to livestock and their pathogens. In this paper, we review the benefits and risks of livestock production on child nutrition. Evidence supports the nutritional benefits of livestock farming through income, production, and women's empowerment. Increasing animal source food consumption requires a combination of efforts, including improved animal management so that herd size is adequate to meet household income needs and consumption and addressing sociocultural and gendered norms. Evidence supports the inclusion of behavior change communication strategies into livestock production interventions to facilitate the sustainability of nutritional benefits over time, particularly interventions that engage women and foster dimensions of women's empowerment. In evaluating the risks of livestock production, evidence indicates that a broad range of enteric pathogens may chronically infect the intestines of children and, in combination with dietary deficits, may cause environmental enteric dysfunction (EED), a chronic inflammation of the gut. Some of the most important pathogens associated with EED are zoonotic in nature with livestock as their main reservoir. Very few studies have aimed to understand which livestock species contribute most to colonization with these pathogens, or how to reduce transmission. Control at the point of exposure has been investigated in a few studies, but much less effort has been spent on improving animal husbandry practices, which may have additional benefits. There is an urgent need for dedicated and long-term research to understand which livestock species contribute most to exposure of young children to zoonotic enteric pathogens, to test the potential of a wide range of intervention methods, to assess their effectiveness in randomized trials, and to assure their broad adaptation and sustainability. This review highlights the benefits and risks of livestock production on child nutrition. In addition to identifying research gaps, findings support inclusion of poor gut health as an immediate determinant of child undernutrition, expanding the established UNICEF framework which includes only inadequate diet and disease.

Daily Rice Bran Consumption for 6 Months Influences Serum Glucagon-Like Peptide 2 and Metabolite Profiles without Differences in Trace Elements and Heavy Metals in Weaning Nicaraguan Infants at 12 Months of Age

BACKGROUND

Environmental enteric dysfunction (EED) is associated with chronic gut inflammation affecting nutrient absorption and development of children, primarily in low- and middle-income countries. Several studies have shown that rice bran (RB) supplementation provides nutrients and modulates gut inflammation, which may reduce risk for undernutrition.

OBJECTIVE

The aim was to evaluate the effect of daily RB dietary supplementation for 6 mo on serum biomarkers in weaning infants and associated changes in serum and stool metabolites.

METHODS

A 6-mo randomized-controlled dietary intervention was conducted in a cohort of weaning 6-mo-old infants in León, Nicaragua. Anthropometric indices were obtained at 6, 8, and 12 mo. Serum and stool ionomics and metabolomics were completed at the end of the 6-mo intervention using inductively coupled plasma MS and ultra-high performance LC-tandem MS. The ɑ1-acid glycoprotein, C-reactive protein, and glucagon-like peptide 2 (GLP-2) serum EED biomarkers were measured by ELISA.

RESULTS

Twenty-four infants in the control group and 23 in the RB group successfully completed the 6-mo dietary intervention with 90% dietary compliance. RB participants had higher concentrations of GLP-2 as compared with control participants at 12 mo [median (IQR): 743.53 (380.54) pg/mL vs. 592.50 (223.59) pg/mL; P = 0.04]. Metabolite profiles showed significant fold differences of 39 serum metabolites and 44 stool metabolites from infants consuming RB compared with control, and with significant metabolic pathway enrichment scores of 4.7 for the tryptophan metabolic pathway, 5.7 for polyamine metabolism, and 5.7 for the fatty acid/acylcholine metabolic pathway in the RB group. No differences were detected in serum and stool trace elements or heavy metals following daily RB intake for 6 mo.

CONCLUSIONS

RB consumption influences a suite of metabolites associated with growth promotion and development, while also supporting nutrient absorption as measured by changes in serum GLP-2 in Nicaraguan infants. This clinical trial was registered at https://clinicaltrials.gov as NCT02615886.

Intergenerational Association of Short Maternal Stature with Stunting in Yanomami Indigenous Children from the Brazilian Amazon

To describe the factors associated to stunting in <5-year-old Yanomami Brazilian children, and to evaluate the association of short maternal stature to their offspring’s stunting. A cross-sectional study carried out in three villages in the Yanomami territory. We performed a census, in which all households with children < 5-years-old were included. The length/height-for-age z-score <−2 standard deviations was used to classify the children as stunted. Short maternal height was defined as <145 cm for adult women, and <−2 standard deviations of the height-for-age z-score for adolescent women. We used adjusted Poisson regression models to estimate prevalence ratios (PR) along the 90% confidence interval. We evaluated 298 children. 81.2% of children suffered from stunting and 71.9% of the mothers from short stature. In the bivariate analysis, a significant association of stunting with short maternal stature, gestational malaria and child’s place of birth were observed. Considering the variables of the children under five years of age, there were significant associations with age group, the child’s caregiver, history of malaria, pneumonia, and malnutrition treatment. In the adjusted hierarchical model, stunting was 1.22 times greater in the offspring of women with a short stature (90% CI: 1.07–1.38) compared to their counterparts. Brazilian Amazonian indigenous children living in a remote area displayed an alarming prevalence of stunting, and this was associated with short maternal height, reinforcing the hypothesis of intergenerational chronic malnutrition transmission in this population. In addition, children above 24 months of age, who were born in the village healthcare units and who had had previous treatment in the past for stunting presented higher rates of stunting in this study.

Effect of Oral Nutritional Supplementation on Growth in Children with Undernutrition: A Systematic Review and Meta-Analysis

Oral nutritional supplements (ONS) are used to promote catch-up growth in children with undernutrition. We conducted a systematic review and meta-analysis to summarize the evidence of ONS intervention effects on growth for 9-month- to 12-year-old children who were undernourished or at nutritional risk. Eleven randomized controlled trials met the inclusion criteria; trials compared changes in anthropometric measures in children using ONS or ONS + DC (dietary counselling) to measures for those following usual diet or placebo or DC alone. The RCTs included 2287 children without chronic diseases (mean age 5.87 years [SD, 1.35]; 56% boys). At follow-up time points up to 6 months, results showed that children in the ONS intervention group had greater gains in weight (0.423 kg, [95% confidence interval 0.234, 0.613], p < 0.001) and height (0.417 cm [0.059, 0.776], p = 0.022) versus control; greater gains in weight (0.089 kg [0.049, 0.130], p < 0.001) were evident as early as 7–10 days. Longitudinal analyses with repeated measures at 30, 60, and 90 days showed greater gains in weight parameters from 30 days onwards (p < 0.001), a trend towards greater height gains at 90 days (p = 0.056), and significantly greater gains in height-for-age percentiles and Z-scores at 30 and 90 days, respectively (p < 0.05). Similar results were found in subgroup analyses of studies comparing ONS + DC to DC alone. For children with undernutrition, particularly those who were mildly and moderately undernourished, usage of ONS in a nutritional intervention resulted in significantly better growth outcomes when compared to control treatments (usual diet, placebo or DC alone).

Rotavirus vaccines performance: dynamic interdependence of host, pathogen and environment

INTRODUCTION

As of January 2021, rotavirus vaccination programs have been implemented in 109 countries and their use has resulted in a positive impact on rotavirus-related diarrheal hospitalizations and mortality in children below 5 years of age. Despite these successes, several countries in Africa and Asia where disease burden is high have not yet implemented rotavirus vaccination at all or at a scale sufficient enough to demonstrate impact. This could be, among other reasons, due to poor vaccine coverage and the modest levels of efficacy and effectiveness of the vaccines in these resource-limited settings.

AREAS COVERED

We review various factors related to the human host (malnutrition, maternally derived antibodies and breastfeeding, genetic factors, blood group, and co-administration with oral polio vaccine), rotavirus pathogen (force of infection, strain diversity and coinfections), and the environment (related to the human microbiome) which reflect complex and interconnected processes leading to diminished vaccine performance in resource-limited settings.

EXPERT OPINION

Addressing the limiting factors for vaccine efficacy is needed but likely to take a long time to be resolved. An immediate solution is to increase the immunization coverage to higher values generating an overall effect of adequate proportion of protected population to reduce the prevalence of rotavirus disease.

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

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

Small and Large Intestine (I): Malabsorption of Nutrients

Numerous disorders can alter the physiological mechanisms that guarantee proper digestion and absorption of nutrients (macro- and micronutrients), leading to a wide variety of symptoms and nutritional consequences. Malabsorption can be caused by many diseases of the small intestine, as well as by diseases of the pancreas, liver, biliary tract, and stomach. This article provides an overview of pathophysiologic mechanisms that lead to symptoms or complications of maldigestion (defined as the defective intraluminal hydrolysis of nutrients) or malabsorption (defined as defective mucosal absorption), as well as its clinical consequences, including both gastrointestinal symptoms and extraintestinal manifestations and/or laboratory abnormalities. The normal uptake of nutrients, vitamins, and minerals by the gastrointestinal tract (GI) requires several steps, each of which can be compromised in disease. This article will first describe the mechanisms that lead to poor assimilation of nutrients, and secondly discuss the symptoms and nutritional consequences of each specific disorder. The clinician must be aware that many malabsorptive disorders are manifested by subtle disorders, even without gastrointestinal symptoms (for example, anemia, osteoporosis, or infertility in celiac disease), so the index of suspicion must be high to recognize the underlying diseases in time.

Revisiting maternal and child undernutrition in low-income and middle-income countries: variable progress towards an unfinished agenda

13 years after the first Lancet Series on maternal and child undernutrition, we reviewed the progress achieved on the basis of global estimates and new analyses of 50 low-income and middle-income countries with national surveys from around 2000 and 2015. The prevalence of childhood stunting has fallen, and linear growth faltering in early life has become less pronounced over time, markedly in middle-income countries but less so in low-income countries. Stunting and wasting remain public health problems in low-income countries, where 4·7% of children are simultaneously affected by both, a condition associated with a 4·8-times increase in mortality. New evidence shows that stunting and wasting might already be present at birth, and that the incidence of both conditions peaks in the first 6 months of life. Global low birthweight prevalence declined slowly at about 1·0% a year. Knowledge has accumulated on the short-term and long-term consequences of child undernutrition and on its adverse effect on adult human capital. Existing data on vitamin A deficiency among children suggest persisting high prevalence in Africa and south Asia. Zinc deficiency affects close to half of all children in the few countries with data. New evidence on the causes of poor growth points towards subclinical inflammation and environmental enteric dysfunction. Among women of reproductive age, the prevalence of low body-mass index has been reduced by half in middle-income countries, but trends in short stature prevalence are less evident. Both conditions are associated with poor outcomes for mothers and their children, whereas data on gestational weight gain are scarce. Data on the micronutrient status of women are conspicuously scarce, which constitutes an unacceptable data gap. Prevalence of anaemia in women remains high and unabated in many countries. Social inequalities are evident for many forms of undernutrition in women and children, suggesting a key role for poverty and low education, and reinforcing the need for multisectoral actions to accelerate progress. Despite little progress in some areas, maternal and child undernutrition remains a major global health concern, particularly as improvements since 2000 might be offset by the COVID-19 pandemic.

Biomarkers of environmental enteric dysfunction are differently associated with recovery and growth among children with moderate acute malnutrition in Sierra Leone

BACKGROUND

Environmental enteric dysfunction (EED) may influence growth during and recovery from moderate acute malnutrition (MAM), however, biomarkers to assess these relations have yet to be identified.

OBJECTIVES

The objectives of this study were to: 1) develop a score for EED based on host fecal mRNA transcripts, 2) compare biomarkers of EED with each other, and 3) examine associations between the EED biomarkers and recovery from MAM and growth outcomes.

METHODS

In a cohort of 520 Sierra Leonean MAM children, biomarkers of EED included the lactulose: mannitol (L: M) test, 15 host fecal mRNA transcripts, and host fecal proteins [α-1-antitrypsin (AAT), myeloperoxidase (MPO), neopterin (NEO)]. Anthropometry data were also collected and z scores were computed for length-for-age (LAZ) and weight-for-length (WLZ). Recovery from MAM was defined as midupper arm circumference ≥12.5 cm. Factor analysis was used to identify EED scores using the mRNA transcripts, and mixed effects regression was conducted to test for associations.

RESULTS

The 15 host fecal mRNA transcripts were clustered into 3 scores: gut inflammation (GI) score, gut structure (GS) score, and gut defense (GD) score. We found agreement between certain inflammation markers (GI score and MPO), and permeability markers (GS score and AAT; AAT and the L: M excretion ratio). Antimicrobial gut defense (GD score) was inversely associated with percent lactulose excreted, a measure of intestinal permeability. LAZ (β: -0.08; 95% CI: -0.14, -0.02) and WLZ (β: -0.03; 95% CI: -0.06, -0.01) were negatively associated with GI score. A high GD score (β: 0.36; 95% CI: 0.08, 0.64) and low AAT (β: -1.35; 95% CI: -2.35, -0.36) were associated with recovery from MAM.

CONCLUSIONS

Scores derived from host fecal mRNA transcript variably correlated with the L: M test and host fecal proteins. Markers of intestinal inflammation, permeability, and defense were associated with growth outcomes and recovery from MAM.