Abstract
Background: Environmental enteropathy, which is linked to undernutrition and chronic infections, affects the physical and mental growth of children in developing areas worldwide. Key to understanding how these factors combine to shape developmental outcomes is to first understand the effects of nutritional deficiencies on the mammalian system including the effect on the gut microbiota.Objective: We dissected the nutritional components of environmental enteropathy by analyzing the specific metabolic and gut-microbiota changes that occur in weaned-mouse models of zinc or protein deficiency compared with well-nourished controls.Design: With the use of a 1H nuclear magnetic resonance spectroscopy–based metabolic profiling approach with matching 16S microbiota analyses, the metabolic consequences and specific effects on the fecal microbiota of protein and zinc deficiency were probed independently in a murine model.Results: We showed considerable shifts within the intestinal microbiota 14–24 d postweaning in mice that were maintained on a normal diet (including increases in Proteobacteria and striking decreases in Bacterioidetes). Although the zinc-deficient microbiota were comparable to the age-matched, well-nourished profile, the protein-restricted microbiota remained closer in composition to the weaned enterotype with retention of Bacteroidetes. Striking increases in Verrucomicrobia (predominantly Akkermansia muciniphila) were observed in both well-nourished and protein-deficient mice 14 d postweaning. We showed that protein malnutrition impaired growth and had major metabolic consequences (much more than with zinc deficiency) that included altered energy, polyamine, and purine and pyrimidine metabolism. Consistent with major changes in the gut microbiota, reductions in microbial proteolysis and increases in microbial dietary choline processing were observed.Conclusions: These findings are consistent with metabolic alterations that we previously observed in malnourished children. The results show that we can model the metabolic consequences of malnutrition in the mouse to help dissect relevant pathways involved in the effects of undernutrition and their contribution to environmental enteric dysfunction.
Highlights
Many parts of the developing world are still struggling with malnutrition, inadequate clean-water supplies, and a lack of access to basic health care
We have investigated 2 malnourishing mouse diets that reflected major nutritional deficiencies that are common in children who are living in impoverished areas. These diets included a protein-deficient diet that resulted in growth failure and a diet that was devoid of zinc that led to zinc deficiency compared with that shown in zinc-deficient children
Similar phylotypes were observed between defined normal (dN)-fed mice (46 d old) and those fed the defined zinc-deficient (dZD) diet for 10 d (46 d old)
Summary
Many parts of the developing world are still struggling with malnutrition, inadequate clean-water supplies, and a lack of access to basic health care. To better understand the impact of nutritional restrictions on the health and development of an individual, murine models have been developed to experimentally mimic human malnourishing diets These models have previously been shown to replicate the characteristic side effects of malnutrition including reduced infant growth, delayed neurobehavioral development, and permanent alterations in macrophage function [1, 2]. We have investigated 2 malnourishing mouse diets that reflected major nutritional deficiencies that are common in children who are living in impoverished areas These diets included a protein-deficient diet (containing 2% protein; a normal diet typically contains w20% protein) that resulted in growth failure and a diet that was devoid of zinc that led to zinc deficiency compared with that shown in zinc-deficient children. Objective: We dissected the nutritional components of environmental enteropathy by analyzing the specific metabolic and gut-microbiota changes that occur in weaned-mouse models of zinc or protein deficiency compared with well-nourished controls.
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