Food hypersensitivity-induced chronic gastrointestinal inflammation in a non-human primate model of diet-induced obesity

Microbiome signature suggestive of lactose-intolerance in rhesus macaques (Macaca mulatta) with intermittent chronic diarrhea

BACKGROUND

Chronic diarrhea is a common cause of mortality and morbidity in captive rhesus macaques (Macaca mulatta). The exact etiology of chronic diarrhea in macaques remains unidentified. The occurrence of diarrhea is frequently linked to dysbiosis within the gut microbiome. Research into microbiome signatures correlated with diarrhea in macaques have predominantly been conducted with single sample collections. Our analysis was based on the metagenomic composition of longitudinally acquired fecal samples from rhesus macaques with chronic diarrhea and clinically healthy rhesus macaques that were obtained over the course of two years. We aimed to investigate potential relationships between the macaque gut microbiome, the presence of diarrhea and diet interventions with a selection of commercially available monkey diets.

RESULTS

The microbiome signature of macaques with intermittent chronic diarrhea showed a significant increase in lactate producing bacteria e.g. lactobacilli, and an increase in fermenters of lactate and succinate. Strikingly, two lactose free diets were associated with a lower incidence of diarrhea.

CONCLUSION

A lactose intolerance mechanism is suggested in these animals by the bloom of Lactobacillus in the presence of lactose resulting in an overproduction of intermediate fermentation products likely led to osmotically induced diarrhea. This study provides new insights into suspected microbiome-lactose intolerance relationship in rhesus macaques with intermittent chronic diarrhea. The integration of machine learning with metagenomic data analysis holds potential for developing targeted dietary interventions and therapeutic strategies and therefore ensuring a healthier and more resilient primate population.

Glycemic Response in Nonhuman Primates Fed Gluten-Free Rice Cakes Enriched with Soy, Pea, or Rice Protein and Its Correlation with Nutrient Composition

Celiac disease (CD) is a chronic disease caused by the consumption of gluten foods and is closely related to type 1 diabetes (T1D). Adherence to a gluten-free (GF) diet is the cornerstone of treating CD, and certain plant proteins added to GF foods affect blood glucose to varying degrees. The aim of this study was to analyze and compare the changes in glycemic index (GI) and incremental area under the postprandial glucose tolerance curve (IAUC) of various foods through consumption of GF foods supplemented with certain plant proteins in non-human primates. The test foods were GF rice cakes with 5%, 10%, and 15% added single plant proteins (rice protein, soy protein, and pea protein) mixed with rice flour, as well as 5%, 10%, and 15% gluten rice cakes, and rice flour alone, for a total of 13 food items, and 12 healthy cynomolgus monkeys were examined for their glucose levels in the blood after fasting and after eating each test food (50 g) for 15, 30, 45, 60, 90, and 120 min after fasting and eating each test food. Fingertip blood glucose levels were measured, and the nutrient content of each food, including protein, fat, starch, ash, and amino acids, was examined. All foods tested had a low GI (<50) when analyzed using one-way ANOVA and nonparametric tests. Postprandial IAUC was significantly lower (p < 0.05) for GF rice cakes with 15% pea protein (499.81 ± 34.46) compared to GF rice cakes with 5% pea protein (542.19 ± 38.78), 15% soy protein (572.94 ± 72.74), and 15% rice protein (530.50 ± 14.65), and GF rice cakes with 15% wheat bran protein (533.19 ± 34.89). A multiple regression analysis showed that glycine was negatively associated with IAUC in GF rice cakes with 5%, 10%, and 15% pea protein added (p = 0.0031 < 0.01). Fat was negatively correlated with IAUC in GF rice cakes supplemented with 5%, 10%, and 15% soy protein (p = 0.0024 < 0.01). In this study, GF rice cakes made with added pea protein were superior to other gluten and GF rice cakes and had a small effect on postprandial glucose.