Dietary resistant potato starch alters intestinal microbial communities and metabolites and markers of immune regulation and barrier function

Authors: TRACHSEL, JULIAN - Orise Fellow; BRIGGS, CASSIDY - Iowa State University; GABLER, NICHOLAS - Iowa State University; Allen, Heather; Loving, Crystal

Submitted to: Frontiers in Immunology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/31/2019
Publication Date: 6/19/2019
Citation: Trachsel, J., Briggs, C., Gabler, N.K., Allen, H.K., Loving, C.L. 2019. Dietary resistant potato starch alters intestinal microbial communities and their metabolites and markers of immune regulation and barrier function in swine. Frontiers in Immunology. 10:1381. https://doi.org/10.3389/fimmu.2019.01381.
DOI: https://doi.org/10.3389/fimmu.2019.01381

Interpretive Summary: The proper balance of commensal gut bacteria is critical for optimum animal health and resistance to disease. In the large intestine, these commensal bacteria turn undigested food into various compounds that nourish host tissues, including the compound butyrate. Butyrate has been shown to improve gut and immune health. In the current study, we evaluated the effects of the non-antibiotic feed additive resistant starch in the diet of nursery-age pigs on the immune system and microbiome. We chose resistant starch because it is not digested by the host and instead passes to the large intestine where bacteria break it down and use the by-products to produce butyrate. Pigs were fed either an unamended diet or diet with resistant potato starch. The results show that pigs fed resistant potato starch have different types of bacteria in their gut than pigs on unamended feed and also have more butyrate produced in their large intestine. In addition, the data indicate favorable changes to immune cell populations in the large intestine that are beneficial to intestinal health, with no negative impact on growth of the pigs. Collectively, these data will be used to inform producers on the ability of resistant starch to enhance intestinal health of pigs.

Technical Abstract: Prebiotics that support the growth and functions of beneficial members of the intestinal microbiota are an attractive non-antibiotic method to improve gut health and reduce the prevalence of certain enteric pathogens. Prebiotics promote bacterial fermentation leading to the production of beneficial metabolites such as butyrate, a short-chain fatty acid known to affect host immune status. Pigs fed a diet amended with 5 percent resistant potato starch (RPS) exhibited alterations associated with gut health relative to swine fed an unamended diet (CON). RPS intake increased abundances of anaerobic Clostridia, specifically members of the genera Terrisporobacter, Sarcina, and Clostridium sensu stricto 1 in feces and several tissues, as well as increased intestinal butyrate, valerate and caproate. Data from functional gene amplicons suggested that the abundance and metabolic activity (butyrate production) of bacteria similar to Anaerostipes hadrus were enhanced by RPS intake. The CON treatment exhibited increased abundances of Proteobacteria from the genera Helicobacter, Sutterella, and Campylobacter (all known to utilize respiratory metabolisms) in several tissues and feces. RPS intake increased the abundance of regulatory T cells in the cecum, but not periphery, and cecal immune status alterations were indicative of enhanced mucosal defenses. A network analysis of host and microbial changes in the cecum revealed that regulatory T cells positively correlated with butyrate concentration, luminal IgA concentration, expression of IL-6 and DEF1B, and several potentially beneficial mucosa-associated bacterial operational taxonomic units (OTUs). Thus, the administration of RPS modulated the microbiota and host immune status in a manner that improved cecal barrier function, promoted immunological tolerance, and reduced the niche for bacterial respiration.