Abstract
Background Children admitted to hospital with complicated severe malnutrition (CSM) have high mortality despite compliance with standard WHO management guidelines. Limited data suggests a relationship between intestinal dysfunction and poor prognosis in CSM, but this has not been explicitly studied. This study aimed to evaluate the role of intestinal disturbances in CSM mortality.
Abstract
Background
The intestine of children with severe malnutrition (SM) shows structural and functional changes that are linked to increased infection and mortality. SM dysregulates the tryptophan-kynurenine pathway, which may impact
processes such as SIRT1- and mTORC1-mediated autophagy and mitochondrial homeostasis. Using a mouse and
organoid model of SM, we studied the repercussions of these dysregulations on malnutrition enteropathy and the protective capacity of maintaining autophagy activity and mitochondrial health.
Severe malnutrition accounts for half-a-million deaths annually in children under the age of five. Despite improved WHO guidelines, inpatient mortality remains high and is associated with metabolic dysfunction. Previous studies suggest a correlation between hepatic metabolic dysfunction and impaired autophagy. We aimed to determine the role of mTORC1 inhibition in a murine model of malnutrition-induced hepatic dysfunction. Wild type weanling C57/B6 mice were fed a 18 or 1% protein diet for two weeks. A third low-protein group received daily rapamycin injections, an mTORC1 inhibitor. Hepatic metabolic function was assessed by histology, immunofluorescence, gene expression, metabolomics and protein levels. Low protein-fed mice manifested characteristics of severe malnutrition, including weight loss, hypoalbuminemia, hypoglycemia, hepatic steatosis and cholestasis. Low protein-fed mice had fewer mitochondria and showed signs of impaired mitochondrial function. Rapamycin prevented hepatic steatosis, restored ATP levels and fasted plasma glucose levels compared to untreated mice. This correlated with increased content of LC3-II, and decreased content mitochondrial damage marker, PINK1. We demonstrate that hepatic steatosis and disturbed mitochondrial function in a murine model of severe malnutrition can be partially prevented through inhibition of mTORC1. These findings suggest that stimulation of autophagy could be a novel approach to improve metabolic function in severely malnourished children.
ABSTRACT
Hospitalized children with severe malnutrition face high mortality rates and often suffer from hepatic and intestinal dysfunction, with negative impacts on their survival. New treatments cannot be developed without
understanding the underlying pathophysiology. We have established and characterized translational organoid
models of severe malnutrition of the liver and the intestine. In these models, amino acid starvation recapitulates
the expected organ-specific functional changes (e.g., hepatic steatosis, barrier dysfunction) accompanied by
reduced mitochondrial and peroxisomal proteins, and altered intestinal tight junction proteins. Resupplementation of amino acids or pharmacological interventions with rapamycin or fenofibrate lead to partial recovery. Restoration of protein levels aligned with signs of improved peroxisomal function in both organoids, and increased mitochondrial proteins and tight junction protein claudin-3 in intestinal organoids. We
present two organoid models as novel tools to gain mechanistic insights and to act as a testing platform for
potential treatments for intestinal and hepatic dysfunction in severe malnutrition.
Mortality in children with severe malnutrition is strongly related to signs of metabolic dysfunction, such as hypoglycemia. Lower circulating tryptophan levels in children with severe malnutrition suggest a possible disturbance in the tryptophan-nicotinamide adenine dinucleotide (TRP-NAD+) pathway and subsequently in NAD+ dependent metabolism regulator sirtuin1 (SIRT1). Here we show that severe malnutrition in weanling mice, induced by 2-weeks of low protein diet feeding from weaning, leads to an impaired TRP-NAD+ pathway with decreased NAD+ levels and affects hepatic mitochondrial turnover and function. We demonstrate that stimulating the TRP-NAD+ pathway with NAD+ precursors improves hepatic mitochondrial and overall metabolic function through SIRT1 modulation. Activating SIRT1 is sufficient to induce improvement in metabolic functions. Our findings indicate that modulating the TRP-NAD+ pathway can improve liver metabolic function in a mouse model of severe malnutrition. These results could lead to the development of new interventions for children with severe malnutrition.
A better understanding of which children are likely to die during acute illness will help clinicians and policy makers target resources at the most vulnerable children. We used machine learning to characterise mortality in the 30-days following admission and the 180-days after discharge from nine hospitals in low and middle-income countries (LMIC).
Post-hospital discharge mortality is high among undernourished children in many low and middle-income countries. Although a number of quantitative studies have highlighted a range of potential socio-cultural, economic and health system factors influencing paediatric post-discharge treatment-seeking and recovery, few studies have explored family and provider perspectives of the post-discharge period in-depth.
This work was part of a large, multi-country prospective cohort study, the Childhood Acute Illness and Nutrition (CHAIN) Network. We conducted a qualitative sub-study to understand the post-discharge treatment-seeking and recovery experiences of families of undernourished children aged 2–23 months admitted in a rural and urban icddr,b (International Centre for Diarrhoeal Disease Research, Bangladesh) hospital. Methods included repeat in-depth interviews (73 interviews in total) with 29 family members of 17 purposively selected children. These data were supplemented by interviews with 33 health workers, and by observations in hospitals and homes.
Important drivers of treatment-seeking perceived to support recovery included advice provided to family members while in hospital, media campaigns on hygiene practice, availability of free treatment, and social and financial support from family members, relatives and neighbours. Key perceived challenges included low household incomes, mothers having to juggle multiple responsibilities in addition to caring for the sick child, lack of support (sometimes violence) from the child’s father, and family members’ preference for relatively accessible drug shops, physicians or healers over hospital admission.
Development of interventions that address the challenges that families face is essential to support post-discharge adherence to medical advice and recovery. Potential interventions include strengthening information giving during hospitalization on what post-discharge care is needed and why, reducing direct and indirect costs associated with hospital visits, engaging fathers and other ‘significant others’ in post-discharge advice, and building mobile phone-based support for follow-up care.
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Despite adherence to WHO guidelines, inpatient mortality among sick children admitted to hospital with complicated severe acute malnutrition (SAM) remains unacceptably high. Several studies have examined risk factors present at admission for mortality. However, risks may evolve during admission with medical and nutritional treatment or deterioration. Currently, no specific guidance exists for assessing daily treatment response. This study aimed to determine the prognostic value of monitoring clinical signs on a daily basis for assessing mortality risk during hospitalization in children with SAM.
This is a secondary analysis of data from a randomized trial (NCT02246296) among 843 hospitalized children with SAM. Daily clinical signs were prospectively collected during ward rounds. Multivariable extended Cox regression using backward feature selection was performed to identify daily clinical warning signs (CWS) associated with time to death within the first 21 days of hospitalization. Predictive models were subsequently developed, and their prognostic performance evaluated using Harrell’s concordance index (C-index) and time-dependent area under the curve (tAUC).
Inpatient case fatality ratio was 16.3% (n=127). The presence of the following CWS during daily assessment were found to be independent predictors of inpatient mortality: symptomatic hypoglycemia, reduced consciousness, chest indrawing, not able to complete feeds, nutritional edema, diarrhea, and fever. Daily risk scores computed using these 7 CWS together with MUAC<10.5cm at admission as additional CWS predict survival outcome of children with SAM with a C-index of 0.81 (95% CI 0.77–0.86). Moreover, counting signs among the top 5 CWS (reduced consciousness, symptomatic hypoglycemia, chest indrawing, not able to complete foods, and MUAC<10.5cm) provided a simpler tool with similar prognostic performance (C-index of 0.79; 95% CI 0.74–0.84). Having 1 or 2 of these CWS on any day during hospitalization was associated with a 3 or 11-fold increased mortality risk compared with no signs, respectively.
This study provides evidence for structured monitoring of daily CWS as recommended clinical practice as it improves prediction of inpatient mortality among sick children with complicated SAM. We propose a simple counting-tool to guide healthcare workers to assess treatment response for these children.
Intestinal disorders such as environmental enteric dysfunction (EED) are prevalent in low- and middle-income countries (LMICs) and important contributors to childhood undernutrition and mortality. Autopsies are rarely performed in LMICs but minimally invasive tissue sampling is increasingly deployed as a more feasible and acceptable procedure, although protocols have been devoid of intestinal sampling to date. We sought to determine (1) the feasibility of postmortem intestinal sampling, (2) whether autolysis precludes enteric biopsies’ utility, and (3) histopathologic features among children who died during hospitalization with acute illness or undernutrition.
Transabdominal needle and endoscopic forceps upper and lower intestinal sampling were conducted among children aged 1 week to 59 months who died while hospitalized in Blantyre, Malawi. Autolysis ratings were determined for each hematoxylin and eosin slide, and upper and lower intestinal scoring systems were adapted to assess histopathologic features and their severity.
Endoscopic and transabdominal sampling procedures were attempted in 28 and 14 cases, respectively, with >90% success obtaining targeted tissue. Varying degrees of autolysis were present in all samples and precluded histopathologic scoring of 6% of 122 biopsies. Greater autolysis in duodenal samples was seen with longer postmortem interval (Beta = 0.06, 95% confidence interval, 0.02–0.11). Histopathologic features identified included duodenal Paneth and goblet cell depletion. Acute inflammation was absent but chronic inflammation was prevalent in both upper and lower enteric samples. Severe chronic rectal inflammation was identified in children as young as 5.5 weeks.
Minimally invasive postmortem intestinal sampling is feasible and identifies histopathology that can inform mortality contributors.
The Childhood Acute Illness and Nutrition Network (CHAIN) is a multinational research group that aims to optimize the management and care of highly vulnerable children in resource-limited settings to improve survival, growth and development.
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