No abstract

Mushrooms are known for their immune-modulating and anti-tumour properties. The polysaccharide fraction, mainly beta-glucans, is responsible for the immune-modulating effects. Fungal beta-glucans have been shown to activate leukocytes, which depend on structural characteristics of beta-glucans. As edible mushrooms come in contact with the intestinal immune system, effects on enterocytes are also interesting. Our aim was to evaluate the effect of mushroom polysaccharide extracts varying in beta-glucan structure on nitric oxide production by bone marrow-derived macrophages (BMMs) from mice and on nuclear factor-kappaB transactivation in human intestinal Caco-2 cells. We demonstrated that extracts from Agaricus bisporus stimulated nitric oxide production by BMM, whereas extracts from Coprinus comatus and spores of Ganoderma lucidum had only minor effects. Furthermore, extracts of A. blazei Murill and Phellinus linteus had no effect at all. Almost all mushroom extracts lowered nuclear factor-kappaB transactivation in Caco-2 cells. Structural analysis of A. bisporus compared with A. blazei Murill suggests that branching of the beta-glucan chain is essential for immune-stimulating activity. In conclusion, extracts from A. bisporus activate BMM, without activating enterocytes. These characteristics make A. bisporus an attractive candidate as a nutritional compound to stimulate the immune response in depressed states of immunity.

No abstract

Yeast, fungal, and dietary beta-glucans have immune-modulating effects in vitro and in vivo, as thought, mainly by affecting leukocytes; however, effects of oat beta-glucan on enterocytes have never been studied. As recognized, supplying oat beta-glucans as such to cells in culture directly is difficult because of solubility problems. Therefore, six ileostomic patients consumed, in random order, a control diet or an oat beta-glucan enriched diet (5 g) and from the collected ileostomic content, fecal water was prepared and added to two small intestinal cell lines (INT407, Caco-2) and two colon cell lines (HT29, T84) together with a cytokine cocktail (IL-1beta + INFgamma + TNFalpha). Several parameters reflecting immune-modulation were measured. As compared to placebo fecal water, beta-glucan enriched fecal water significantly increased IL-8 production in HT29 (5.0%; p = 0.046) and INT407 cells (22.0%; p = 0.028). Intercellular adhesion molecule (ICAM)-1 expression increased in T84 (11.0%; p = 0.028) and Caco-2 cells (20.4%; p = 0.075). These immune-stimulating effects were confirmed by enhancement of inflammatory expression profiles, as determined with an antibody array. Our findings show immune enhancement by fecal water from ileostomic patients consuming oat beta-glucan both in small intestinal and colon cell lines after stimulation, which is in agreement with documented effects in leukocytes. Whether these immune-stimulating effects on enterocytes contribute to the enhanced protection of the host against invading pathogens as observed both in animals and in humans, as well as the underlying mechanism, needs further evaluation.

Introduction: Mushrooms are known for their immune modulating effect for which the polysaccharide fraction, mainly glucans, seem to be responsible. Fungal b-glucans have been studied extensively, whereas little is known about mushroom a-glucans. We have earlier shown that the polysaccharide fraction from the mushroom A. bisporus, consisting 90% of a-glucans, induced in vitro tumor necrosis factor (TNF)a and nitric oxide production. The purpose of this study was to evaluate the effects of consuming. Method: A. bisporus a-glucan on ex vivo cytokine production by human peripheral mononuclear blood cells (PBMCs). A doubleblind randomized trial was designed in which 56 mildly hypercholesterolemic subjects consumed a control fruit juice with no added a-glucans (200 ml/day) for a 2-week run-in period. For the next 5 weeks, the control group (N ¼ 30) continued consumption of the control fruit juice, whereas the intervention group (N ¼ 26) consumed the same fruit juice enriched with a-glucans from A. bisporus (5 g glucans/day). Changes in interleukin (IL)-1b, IL-6 and TNFa cytokine production by lipopolysaccharide (LPS)-stimulated PBMCs were evaluated, as well as changes in T-helper (Th)1/Th2 cytokines by phytohemaggutinin (PHA)-stimulated PBMCs. Results: Consumption of A. bisporus a-glucans lower LPS-induced TNFa production by 69% (P ¼ 0.017) as compared with the control group, whereas no effect on IL-1b and IL-6 was observed. No obvious Th1-Th2 skewing by PHA-stimulated PBMCs was observed. However, we observed a trend towards a decreased production of IL-12 and IL-10. Conclusion: Our current finding suggests that in vivo, a-glucans have lost their efficacy to stimulate the immune response as observed in our in vitro mouse model.