Regulation of Enteric Infection and Immunity by Dietary Proanthocyanidins

Abstract

The role of dietary components in immune function has acquired considerable attention in recent years. An important focus area is to unravel the role of bioactive dietary compounds in relation to enteric disease and their impact on gut mucosal immunity. Proanthocyanidins (PAC) are among the most common and most consumed dietary polyphenols, and are characterised by their variable molecular structures and diverse bioactivities. In particular, their anti-oxidative effects and ability to modulate gut microbiota have been widely described. However, there is limited evidence on the mechanism of action of PAC on the immune system, nor is it clearly established how PAC may influence susceptibility to enteric infections. Establishing the sites of action of PAC and their metabolites within the gut environment is fundamental to determine the applicability of PAC against enteric pathogens. Some mechanistic studies have shown that PAC have direct modulatory effects on immune cell signalling, isolated pathogens, and gut mucosal barrier integrity. Boosting the recruitment of immune cells and suppressing the amount of pro-inflammatory cytokines are modulating factors regulated by PAC, and can either be beneficial or detrimental in the course of re-establishing gut homeostasis. Herein, we review how PAC may alter distinct immune responses towards enteric bacterial, viral and parasitic infections, and how the modulation of gut microbiota may act as a mediating factor. Furthermore, we discuss how future studies could help unravel the role of PAC in preventing and/or alleviating intestinal inflammation and dysbiosis caused by enteric disease.

Dietary proanthocyanidins promote localized antioxidant responses in porcine pulmonary and gastrointestinal tissues during Ascaris suum ‐induced type 2 inflammation

“…Previous studies have indicated that immunomodulatory and anti‐inflammatory effects of PAC may derive from changes in the GM and associated metabolite production 13 . Furthermore, A .…”

“…Previous studies have indicated that immunomodulatory and anti-inflammatory effects of PAC may derive from changes in the GM and associated metabolite production. 13 Furthermore, A. suum and other helminths can markedly change host GM composition. 59 Therefore, to explore whether the observed transcriptomic changes induced by diet and infection were accompanied by GM changes, we used 16S rRNA gene amplicon sequencing to characterize both the small and large intestinal GM composition.…”

Phytochemical-induced mucin accumulation in the gastrointestinal lumen is independent of the microbiota

“…In our previous study (12), the pea seed coat supplementation (PA diet) led to faster colonization of C. rodentium , a common enteric mouse pathogen, and we suspect that this is a consequence the direct impact of polyphenols on the mucus layer. Most studies have focused on the beneficial roles that phytochemicals have on health and has been extensively reviewed (32); however, little is mentioned of the phytochemical-mucus interactions in the gut outlined herein. Therefore, in addition to confirming that phytochemical directly increase luminal mucin concentration, an analysis of the colonic microbial community was conducted, with a particular interest in mucolytic microbes that may benefit under these conditions.…”

Dietary Proanthocyanidins Exert Localized Immunomodulatory Effects in Porcine Pulmonary and Gastrointestinal Tissues duringAscaris suum-induced Type 2 inflammation

“…Previous studies have indicated that immunomodulatory and anti-inflammatory effects of PAC may derive from changes in the GM and associated metabolite production 17 . Furthermore, A. suum and other helminths can markedly change host GM composition 59 .…”

“…PAC have been shown to increase the abundance of Lactobacilli and Bifidobacterium species, which are commonly associated with a healthy gut environment, as well as increasing levels of faecal short chain fatty acids (SCFA) such as propionic acid 11, 15, 16 . Thus, the immunomodulatory effects of PAC may be caused by direct interactions with immune cells and/or indirect modulation of immune responses as a result of PAC-induced alteration of the GM 17 . These bioactive effects on intestinal immune cells or the GM may have significant implications for inflammation in the gut, as well as at distant sites, such as the lungs, with increasing evidence suggesting a gut-lung axis and clear connection between gut function, the microbiome, and lung homeostasis 18 .…”