Dietary non-starch polysaccharides impair immunity to enteric nematode infection.

BACKGROUND: The influence of diet on immune function and resistance to enteric infection and disease is becoming ever more established. Highly processed, refined diets can lead to inflammation and gut microbiome dysbiosis, whilst health-promoting dietary components such as phytonutrients and fermentable fibres are thought to promote a healthy microbiome and balanced mucosal immunity. Chicory (Cichorium intybus) is a leafy green vegetable rich in fibres and bioactive compounds that may promote gut health. RESULTS: Unexpectedly, we here show that incorporation of chicory into semisynthetic AIN93G diets renders mice susceptible to infection with enteric helminths. Mice fed a high level of chicory leaves (10% dry matter) had a more diverse gut microbiota, but a diminished type-2 immune response to infection with the intestinal roundworm Heligmosomoides polygyrus. Furthermore, the chicory-supplemented diet significantly increased burdens of the caecum-dwelling whipworm Trichuris muris, concomitant with a highly skewed type-1 immune environment in caecal tissue. The chicory-supplemented diet was rich in non-starch polysaccharides, particularly uronic acids (the monomeric constituents of pectin). In accordance, mice fed pectin-supplemented AIN93G diets had higher T. muris burdens and reduced IgE production and expression of genes involved in type-2 immunity. Importantly, treatment of pectin-fed mice with exogenous IL-25 restored type-2 responses and was sufficient to allow T. muris expulsion. CONCLUSIONS: Collectively, our data suggest that increasing levels of fermentable, non-starch polysaccharides in refined diets compromises immunity to helminth infection in mice. This diet-infection interaction may inform new strategies for manipulating the gut environment to promote resistance to enteric parasites.

Anti-protozoal activity and metabolomic analyses of Cichorium intybus L. against Trypanosoma cruzi.

Chagas disease, caused by the protozoa Trypanosoma cruzi, is a potentially life-threatening parasitic zoonosis infecting 6-7 million people worldwide, mainly in Latin America. Due to the limited numbers of drugs available against this neglected disease and their frequent adverse effects, novel anti-chagasic agents are urgently needed. Cichorium intybus L. (chicory) is a bioactive plant with potent activity against parasitic nematodes, but its effects on protozoans are poorly known and no studies have explored its trypanocidal potential. Here, we investigated the activity of C. intybus against extracellular and intracellular stages of T. cruzi, including the prediction of trypanocidal compounds by metabolomic analyses and bioactivity-based molecular networking. Purified C. intybus extracts were prepared from leaves and roots of five C. intybus cultivars (cv. 'Benulite', 'Goldine', 'Larigot', 'Maestoso' and 'Spadona'). All C. intybus extracts induced concentration-dependent effects against T. cruzi trypomastigotes. C. intybus leaf extracts had higher trypanocidal selectivity and lower cytotoxicity on mammalian cells than root extracts. The leaf extract of C. intybus cv. Goldine also significantly reduced the number of mammalian cells infected with T. cruzi amastigotes. Metabolomic and bioactivity-based molecular networking analyses revealed 11 compounds in C. intybus leaves strongly linked with activity against trypomastigotes, including the sesquiterpene lactone lactucin, and flavonoid- and fatty acid-derivatives. Furthermore, seven distinct C. intybus molecules (including two sesquiterpene lactone-derivatives) were predicted to be involved in reducing the number of mammalian cells infected with amastigotes. This is the first report of the anti-protozoal activity of C. intybus against trypanosomatid parasites and expands our understanding of the anti-parasitic effects of this plant and its bioactive metabolites. Further studies to elucidate the anti-protozoal compound(s) in C. intybus and their mode(s) of action will improve our knowledge of using this bioactive plant as a promising source of novel broad-spectrum anti-parasitic compounds with associated health benefits and biomedical potential.

Anti-protozoal activity of extracts from chicory (Cichorium intybus) against Cryptosporidium parvum in cell culture.

Cryptosporidium spp. are responsible for severe public health problems and livestock production losses. Treatment options are limited to only one drug available for human and bovine cryptosporidiosis, respectively, and both drugs exhibit only partial efficacy. Sesquiterpene lactones (SL) are plant bioactive compounds that function as a defence mechanism against herbivores. SL have demonstrated anti-parasitic properties against a range of parasitic taxa but knowledge about their anti-Cryptosporidium efficacy is limited. The effect of SL-rich leaf and root extracts from chicory (Cichorium intybus cv. Spadona) was investigated using human colon adenocarcinoma (HCT-8) cells infected with Cryptosporidium parvum. C. parvum oocysts were inoculated onto the cell monolayer and i) incubated for 4 hours with extracts (leaf and root extracts 300, 150, 75, 37.5, 18.75 and 9.375 µg/mL) in triplicates followed by incubation in bioactive free media (sporozoite invasion assays) or ii) incubated for 4 hours in bioactive free media followed by 48-hours incubation with extracts (growth inhibition assays). Extract toxicity on HCT-8 cells was assessed via water-soluble tetrazolium (WST)-1 assay prior to quantifying parasitic growth via immunofluorescence. Both extracts demonstrated dose-dependent inhibition in the growth inhibition assays (p = < 0.0001 for both extracts) but not in the invasion assays. Anti-parasitic activity did not appear to be solely related to SL content, with the extract with lower SL content (leaf) exhibiting higher inhibition at 300 µg/ml. However, given the limited treatment options available for Cryptosporidium spp., our study encourages further investigation into the use of chicory extracts to identify novel active compound(s) inhibiting these protozoa.

Antiparasitic activity of chicory (Cichorium intybus) and its natural bioactive compounds in livestock: a review.

Increasing drug resistance in gastrointestinal (GI) parasites of livestock and concerns about chemical residues in animal products and the environment are driving the development of alternative control strategies that are less reliant on the use of synthetic drugs. An increasingly investigated approach is the use of bioactive forages with antiparasitic properties as part of the animal's diet (nutraceuticals) or as potential sources of novel, natural parasiticides. Chicory (Cichorium intybus) is a multi-purpose crop and one of the most promising bioactive forages in temperate regions, and numerous in vivo trials have explored its potential against parasitic nematodes in livestock. However, it is unclear whether chicory can induce a direct and broad activity against various GI parasites in different livestock species, and the levels of chicory in the diet that are required to exert an efficient antiparasitic effect. Moreover, the mechanisms leading to the reported parasiticidal activity of chicory are still largely unknown, and its bioactive phytochemicals have only recently been investigated. In this review, we summarise the progress in the study of the antiparasitic activity of chicory and its natural bioactive compounds against GI parasites in livestock, through examination of the published literature. The available evidence indicates that feeding chicory can reduce faecal egg counts and/or worm burdens of abomasal nematodes, but not infections with intestinal worms, in ruminants. Highly chicory-rich diets (≥ 70% of chicory dry matter in the diet) may be necessary to directly affect abomasal parasitism. Chicory is known to synthesise several bioactive compounds with potential antiparasitic activity, but most research has been devoted to the role of sesquiterpene lactones (SL). Recent in vitro studies have confirmed direct and potent activity of SL-rich extracts from chicory against different GI helminths of livestock. Chicory SL have also been reported to exhibit antimalarial properties and its potential antiprotozoal activity in livestock remains to be evaluated. Furthermore, the detailed identification of the main antiparasitic metabolites of chicory and their pharmacokinetics need further confirmation. Research gaps and perspectives on the potential use of chicory as a nutraceutical forage and a source of bioactive compounds for parasite control in livestock are discussed.