Effects of Dietary Fiber Supplementation on Host Immune Responses and Host Gut Microbiome in Roundworm-infected pigs

Abstract text

Ascaris is one of the most prevalent intestinal parasites in humans and pigs causing stunting and emaciation in infected individuals. For pig farmers this leads to serious economic losses.

The aim of thisl project is to investigate a potential beneficial influence of dietary fibers on an infection with Ascaris suum in pigs.

Dietary fibers increase the viscosity of the ingesta and thereby enlarge the mucus layer. As a consequence, we hypothesize that less larvae penetrate the cecum after infection to start the body migration. In addition, we hypothesize that the helminth-induced regulatory type 2 immune response will be enhanced by the bacterial metabolites derived from the dietary fibers. In particular, we expect short chain fatty acids (SCFA) as metabolites which get fermented by the gut microbiota. SCFAs were shown to activate gut dendritic cells and to induce polarization of Th2 cells which subsequently supports worm clearance. In parallel, we expect increased regulatory T cells which dampen inflammatory processes.

The experimental approach will investigate an alternative method to anthelmintic therapy and vaccination by administering a diet with inulin and sugar beet pulp as a new approach to modulate worm burden and severity of symptoms caused by infection with A. suum in pigs. Readouts will include diet-associated changes of the immune response, the gut microbiome, and infection efficacy in the natural host, the pig.

First in vitro approaches using gas chromatography have detected four different SCFAs in the excretory/secretory products of A. suum. In addition to assessing SCFA production by the parasite, we are examining what effect SCFAs have on porcine PBMC versus mesenteric lymph node derived dendritic cell and monocyte cytokine production. Preliminary data in monocytes confirm the trend that SCFA incubation lead to a decreased tumor necrosis factor production.