1a.Objectives (from AD-416)
ARS is interested in determining the impact of dietary induced changes in intestinal microflora that affect inflammatory aspects of obesity. In-house research has demonstrated that the pig can be used to model changes in immunological and anti-inflammatory responses to diets that correspond to changes in bacteria in the gut. Feeding a conventional diet containing added levels of fructose, fat, and cholesterol (HF/HFr/HC) compared to a conventional diet increased aspects of the metabolic syndrome in juvenile Ossabaw pigs.
1b.Approach (from AD-416)
Fecal material from Ossabaw sows prior to weaning and their piglets pre- and post-weaning will be evaluated for changes in microbial populations. The analysis will provide a measure of robust changes in bacterial populations that result from dramatic changes in diet pre- and post weaning. Additional changes in bacterial populations will be evaluated following a comparative regimen of feeding a conventional diet compared to one with added HF/HFr/HC and detection of single copy genes for Bifidobacterium and Lactobacillus species measured by real time PCR along with other genera and species including Eubacteria, pan Bifidobacterium, pan Lactobacillus, Escherichia coli, Clostridium difficile, and Bacteriodes fragilis. Changes in innate and acquired immune response patterns in the local tissues and selected circulating markers in whole blood will be evaluated by gene expression, histology, and physiology. This information will be used by both ARS and the cooperator to jointly develop studies that focus on how major modifications of diet affect intestinal microbial populations associated with host change that affect intestinal health.
A component of this project has been the analysis of the intestinal bacterial populations in the Ossabaw pig; the data have shown that certain bacterial phyla virtually disappeared from the lumen of pigs on a obesigenic high fat/high fructose/high cholesterol diet and other phyla were expanded. Pigs fed a Bifidobacterium probiotic and the obesigenic diet, however, altered the distribution of bacterial genera in both the lumen and mucosa compared to those fed a probiotic-free placebo. Pyrosequencing of luminal bacterial in the colon and bacterial associated with colonic mucosal tissue showed changes that were dependent on the diet and on the probiotic. Associations between these changes in bacterial populations and inflammatory and metabolic parameters in the host can be linked to control strategies. These studies provide a solid foundation for additional testing of diet and food-derived compounds thought to prevent or ameliorate expression of chronic disease and to determine mechanisms of action at the molecular, cellular, and whole-animal level. Activities are monitored by the ARS scientists involved through periodic meetings, email, and conference calls with scientists at George Mason University.