Effect of mushroom polysaccharides from Pleurotus eryngii on obesity and gut microbiota in mice fed a high-fat diet.

PURPOSE: Mushrooms are reported to have a variety of health-promoting activities. However, little information is available on the effects of intake of polysaccharides from Pleurotus eryngii on obesity. In this study, we investigated the effects of P. eryngii polysaccharides on obesity and gut microbiota in mice fed a high-fat diet. METHODS: Soluble polysaccharides were extracted from P. eryngii using hot water. C57BL/6J mice were fed a standard diet (ST), a high-fat diet (HF), or HF with 1% or 5% P. eryngii polysaccharide fraction (LP or HP) for 16 weeks. Adipose tissues were weighed and blood parameters were measured. Expression of genes involved in fatty acid and cholesterol metabolism was assessed by real-time quantitative PCR. The gut microbiota composition was analysed by 16S rRNA gene sequencing. RESULTS: Body weight gain and mesenteric fat tissue were lower in the HP group than in the HF group. In the HP group, serum total cholesterol and LDL cholesterol levels decreased, and lipid and total bile acids in faeces increased. Mice in the HP group showed increased expression of the LDLR gene in the liver and GPR43 in fat. The relative abundance of Firmicutes was significantly higher in the HF and HP groups than in the ST group. The abundance of some short-chain fatty acid-producing gut bacteria was altered by P. eryngii polysaccharides. CONCLUSIONS: These results provide the first evidence that P. eryngii polysaccharides have anti-obesity and LDL cholesterol-lowering effects in obese mice through increased excretion of bile acids and lipids and altered microbiota.

Grifola frondosa (Maitake) extract activates PPARδ and improves glucose intolerance in high-fat diet-induced obese mice.

Grifola frondosa is a mushroom that has anti-obesity effects, but the detailed mechanism is poorly understood. In this study, we found that lipid soluble extracts derived from G. frondosa (GFE) had peroxisome proliferator-activated receptor δ (PPARδ) agonist activity, inducing the expression of PPARδ-target genes in vitro. Furthermore, administration of GFE to high-fat diet-induced obese mice lowered the total blood cholesterol levels, upregulated the expression of PPARδ-target genes in skeletal muscles and improved glucose intolerance. Additionally, analyses of C2C12 myotubes revealed that GFE restored glucose uptake, which was inhibited by sodium palmitate, to normal levels. Unexpectedly, such acceleration was not abolished by a PPARδ antagonist. These results suggest that G. frondosa is a novel functional food that may prevent life-style related diseases like obesity and diabetes, and that these beneficial effects are likely to be mediated through the activation of PPARδ and a PPARδ-independent insulin signaling pathway.

Dendritic cell inhibitory receptor 4 (DCIR4) is preferentially expressed on inflammatory and patrolling monocytes.

Dendritic cell inhibitory receptor 4 (DCIR4, Clec4a1) is a lectin receptor and a member of mouse dendritic cell immunoreceptor family. Due to the lack of antibodies against DCIR4, expression of DCIR4 protein remains unknown. In this study, we established a specific monoclonal antibody against DCIR4 and investigated the expression of DCIR4 among immune cells. We found that DCIR4 was expressed on non-granulocytic subsets of CD11b+ cells in various immune organs including bone marrow, peripheral blood, spleen, skin-associated lymph nodes and mesenteric lymph nodes. DCIR4+ CD11b+ cells were dichotomized into DCIR4High and DCIR4Low cells distinguished by different levels of DCIR4 expression. By screening a panel of cell surface markers for expression, we found that in bone marrow, blood and spleen the DCIR4Low and the DCIR4High cells were Ly-6C+ CD43Low CD11c- inflammatory- monocytes and Ly-6C- CD43HIgh CD11c+ patrolling monocytes, respectively. Using in vitro differentiation system, we also found that differentiation of Ly-6C+ monocytes into dendritic cells greatly diminished expression of DCIR4, while that into macrophages did not significantly affect DCIR4 expression. The establishment of the anti-DCIR4 antibody enables clearer definition of monocytes and provides a novel tool to investigate biology of monocytes and their progenies.

Effects of an ergothioneine-rich Pleurotus sp. on skin moisturizing functions and facial conditions: a randomized, double-blind, placebo-controlled trial.

Background: L-ergothioneine (EGT), an antioxidative and anti-inflammatory amino acid, is abundant in various mushroom fruiting bodies. Meanwhile, the effects of EGT-containing mushrooms on human skin are unknown. This study investigated the effects of oral ingestion of a novel EGT-rich strain of Pleurotus species (hiratake) on skin conditions in humans. Methods: We conducted a 12-week, randomized, double-blind, placebo-controlled, parallel-group trial to evaluate skin moisturizing functions and facial conditions in 80 healthy women who were randomly assigned to either a group that was supplemented with hiratake tablets containing 25 mg of EGT/day or a placebo group. Skin moisture content, transepidermal water loss (TEWL), and facial scores (VISIA scores) were measured at baseline, 8 weeks, and 12 weeks of supplementation. Results: At 8 weeks, the skin moisture content was significantly higher on the temple in the hiratake group than in the placebo group. The hiratake group also exhibited a significant increase in skin moisture content on the arm at 8 and 12 weeks compared with baseline. At 12 weeks, wrinkle and texture scores were significantly better in the hiratake group than in the placebo group, and plasma EGT concentrations in the hiratake group were 4.7-fold higher than baseline (from 3.4 to 15.9 µM). Furthermore, EGT concentrations in plasma were significantly correlated with improvements in skin moisture content and TEWL on the arm, implying that these skin moisturizing benefits could be partly attributed to EGT. A stratified analysis of participants with a low baseline plasma EGT concentration (< 3.3 µM) revealed that skin moisture content on the temple was significantly higher at 8 and 12 weeks, and skin moisture content on the arm at 12 weeks tended to be higher (p = 0.074), in the hiratake group than in the placebo group. These findings suggested that oral ingestion of EGT-rich hiratake can improve skin moisturizing functions. Conclusion: EGT-rich hiratake may help maintain skin conditions in healthy women, and EGT may play a role in these beneficial effects.