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Novel Cecum Cannulated Pig Model to Investigate the Human Microbiota Through Inter Species Transfer of Gut Microbiota From Humans to Pigs
Recent studies of the human microbiome have helped understand how changes in the microbial community affects human health and physiology, yet they fail to identify the mechanisms and signals underlying how the microbiota impacts human physiology and health. This is mainly because of the lack of a good animal model to investigate the human microbiome over time. The main goal of this research project was to develop a new cecum-cannulated humanized pig model through fecal transplants from humans to pigs to identify the signals of the microbiome that affects the obese phenotype. To this end, we derived 15 germ-free pigs and performed inter- intra-species fecal microbiota transplantation experiments to demonstrate that a human gut associated microbiota can colonize and be maintained within the gnotobiotic pig. The pigs derived through cesarean sectioning were divided into 3 treatment groups and were inoculated with either an obese human gut microbiota , lean gut microbiota,, or a conventional pig microbiota. The pigs with an obese donor microbiota were fed a 40% fat and carbohydrate diet and the pigs that received a lean or conventional pig microbiota was maintained on a 5% fat and carbohydrate diet. Fecal samples were collected weekly to monitor establishment of the gut microbial community. At 7 wk of age, 2 pigs from each treatment were cecum cannulated to evaluate the effect of cannulation on the microbial community structure. The pigs were maintained for an additional 2 wk before euthanization. Microbial community was evaluated using 16S rRNA sequencing using an ION Torrent Personnel Genome machine. This pilot study demonstrated that germfree piglets receiving the human microbiota developed a donor like microbial community each similar to the respective obese or lean donor (PERMANOVA P < 0.05) with minimal animal-to-animal variation. Comparison of the microbiotas of humans, germfree pig recipients of (obese, lean, and conventional), revealed that the microbiota of germfree piglets receiving human microbiota was more similar to human donor microbiota than conventionally raised pigs suggesting the establishment of a human gut flora within the pig (PERMANOVA P< 0.05). The humanized pig model has potential to help understand structure function relationships of the human microbiome. With the cecum cannulation, longitudinal sampling can be performed at the site of microbial action allowing the investigation of microbial gene expression. This model will provide an opportunity to better understand how microbial gene expression effects host gene expression and in turn host physiology.
Keywords: pig model, 16S human microbiota, microbiota transplantation