👤 Laura J Myhill

Dietary fibre is an important regulator of the gut microbiome and is associated with many health benefits. However, high levels of fibre intake have also been reported to exacerbate some diseases. Here, we show that mice fed semi-synthetic diets supplemented with purified inulin fibre develop chronic infections with the parasitic whipworm Trichuris muris, concomitant with dysregulated innate antimicrobial defences, exacerbated mucosal inflammation, and altered tryptophan metabolism. Inhibition of tryptophan catabolism or neutralizing either IL-27 or IL-18 restored infection resistance. Inulin-fed mice developed gut microbiota dysbiosis during parasite infection, with Proteobacteria becoming dominant. However, despite drastic differences in gut microbiota compositions in control- and inulin-fed mice, microbiota transfer and depletion experiments demonstrated that dietary inulin triggered chronic T. muris infection in a microbiota-independent manner. Importantly, removing inulin from the diet within a critical immune development window rapidly restored anti-parasite immunity, indicating direct, time-dependent modulation of mucosal immune responses. These data reveal T. muris-induced dysbiosis as a consequence rather than a causative factor of diet-driven changes in host susceptibility, and establish a direct link between dietary fibre and host defence at mucosal surfaces. Video Abstract. Show less

Garlic is a source of bioactive phytonutrients that may have anti-inflammatory or immunomodulatory properties. The mechanism(s) underlying the bioactivity of these compounds and their ability to regulate responses to enteric infections remains unclear. This study investigates if a garlic-derived preparation (PTSO-PTS) containing two organosulfur metabolites, propyl-propane thiosulfonate (PTSO), and propyl-propane thiosulfinate (PTS), regulate inflammatory responses in murine macrophages and intestinal epithelial cells (IEC) in vitro, as well as in a model of enteric parasite-induced inflammation. PTSO-PTS decreases lipopolysaccharide-induced secretion of TNFα, IL-6, and IL-27 in macrophages. RNA-sequencing demonstrates that PTSO-PTS strongly suppresses pathways related to immune and inflammatory signaling. PTSO-PTS induces the expression of a number of genes involved in antioxidant responses in IEC during exposure to antigens from the parasite Trichuris muris. In vivo, PTSO-PTS does not affect T. muris establishment or intestinal T-cell responses but significantly alters cecal transcriptomic responses. Notably, a reduction in T. muris-induced expression of Tnf, Saa2, and Nos2 is observed. Garlic-derived organosulfur compounds exert anti-inflammatory effects in macrophages and IEC, and regulate gene expression during intestinal infection. These compounds and related organic molecules may thus hold potential as functional food components to improve gut health in humans and animals. Show less