Dietary polyphenols modulate mucosal immune responses and gut microbiota composition in pigs infected with Ascaris suum. Pigs infected with Ascaris suum

Proanthocyanidins (PAC) are a class of polyphenols found in many plants. Diets rich in PAC are thought to have beneficial effects on gut health, such as regulation of parasite burdens and modulation of mucosal immune and inflammatory responses. Here, we examined the interactions between a PAC-rich diet supplement and Ascaris suum infection in pigs. Pigs were fed either a basal diet or the same diet supplemented with PAC-rich grape pomace (GP), and then half of the animals were inoculated with A. suum. Parasite establishment was not altered by GP-supplementation. However, the bioactive diet significantly increased numbers of eosinophils induced by A. suum infection in the duodenum, jejunum and ileum, and modulated gene expression in the jejunal mucosa of infected pigs. GP-supplementation increased the concentration of propionic acid in the colon, whilst both GP-supplementation and A. suum infection decreased concentrations of isobutyric and isovaleric acid. The effects of both GP-supplementation and A. suum on the composition of the host prokaryotic gut microbiota were qualitatively similar, however A. suum had a stronger influence than diet. Our results demonstrate that a PAC-rich diet supplement in pigs significantly modulates the host response to helminth infection. Our results indicate an important influence of diet on immune function during parasite infection, which may potentially be exploited to improve gut health.