Modulatory effects of supplementation of Lentinula edodes mycelia extract and l-arginine on the therapeutic efficacy of immunogenic chemotherapy in colon cancer-bearing mice

Some chemotherapeutic drugs can induce cancer cell death and enhance antitumor T-cell immunity in cancer-bearing hosts. Immunomodulatory reagents could augment such chemotherapy-induced effects. We previously reported that oral digestion of Lentinula edodes mycelia (L.E.M.) extract or  l-arginine supplementation can augment antitumor T-cell responses in cancer-bearing mice. In this study, the effects of L.E.M. extract with or without  l-arginine on the therapeutic efficacy of immunogenic chemotherapy by 5-fluorouracil (5-FU)/oxaliplatin (L-OHP) and/or cyclophosphamide (CP) are examined using two mouse colon cancer models. In MC38 and CT26 cancer models, therapy with 5-FU/L-OHP/CP significantly suppressed tumor growth, and supplementation with L.E.M. extract halved the tumor volumes. However, the modulatory effect of L.E.M. extract was not significant. In the CT26 cancer model, supplementation with L.E.M. extract and  l-arginine had no clear effect on tumor growth. In contrast, their addition to chemotherapy halved the tumor volumes, although the effect was not significant. There was no difference in the cytotoxicity of tumor-specific cytotoxic T cells generated from CT26-cured mice treated by chemotherapy alone versus chemotherapy combined with L.E.M. extract/ l-arginine. These results indicate that the antitumor effects of immunogenic chemotherapy were too strong to ascertain the effects of supplementation of L.E.M. extract and  l-arginine, but these reagents nonetheless have immunomodulatory effects on the therapeutic efficacy of immunogenic chemotherapy in colon cancer-bearing mice.

Age-associated impairment of antitumor immunity in carcinoma-bearing mice and restoration by oral administration of Lentinula edodes mycelia extract

Because cancer is associated with aging, immunological features in the aged should be considered in anticancer immunotherapy. In this study, we investigated antitumor immunity in aged mice using a CT26 colon carcinoma model. The tumor growth of CT26 was accelerated in aged mice compared with that in young mice, but this difference was not observed in nude mice. The serum levels of IL-6 and TNF-α were higher in aged mice than those in young mice, irrespective of the CT26-bearing state. The in vitro induction of CT26-specific CTLs from aged mice that were vaccinated with doxorubicin (DTX)-treated CT26 cells was impaired. In vivo neutralization of IL-6, but not TNF-α, showed a tendency to restore the in vitro induction of CT26-specific CTLs from vaccinated aged mice. Analyses on tumor-infiltrating immune cells as early as day 5 after CT26 inoculation revealed that monocytic and granulocytic MDSCs preferentially infiltrated into tumor sites in aged mice compared with young mice. Alternatively, oral administration of Lentinula edodes mycelia (L.E.M.) extract, which has the potential to suppress inflammation in tumor-bearing hosts, decreased the serum levels of IL-6 in aged mice. When administration of L.E.M. extract was started 1 week earlier, CT26 growth was retarded in aged mice and the in vivo priming of tumor-specific CTLs was improved in CT26-vaccinated aged mice. These results indicate early infiltration of MDSCs is related to impaired immunity of aged hosts and that oral administration of L.E.M. extract can mitigate the impairment.

Effective removal of cadmium ions from a simulated gastrointestinal fluid by Lentinus edodes

Lentinus edodes, a functional food, was evaluated as a potential antidote for adsorption/removal of cadmium ion from simulated gastrointestinal fluids. An adsorption/removal capacity of 65.12 mg/g was achieved by L. edodes in solutions with a pH ranging from 2.5 to 6.0, while little if any adsorption was observed in solutions with a pH under 2.5. In solutions with pH 6.0, 84% of the cadmium adsorption by L. edodes occurred in the first minute. Scanning electronic microscopic examination showed that the cell wall polysaccharides of L. edodes provided a rough sponge-like surface for effective cadmium adsorption. FTIR indicated that the carboxyl, hydroxyl and –NH groups of the cell wall polysaccharides and proteins were the primary functional groups that chemically bind with cadmium ions. The energy dispersive spectrometry further revealed that cation exchange might be attributed to cadmium biosorption. These results suggested that L. edodes was effective for cadmium detoxication, especially in low concentration.

Combining a peptide vaccine with oral ingestion of Lentinula edodes mycelia extract enhances anti-tumor activity in B16 melanoma-bearing mice

New anticancer vaccines must overcome regulatory T cell (Treg)-mediated immunosuppression. We previously reported that oral ingestion of Lentinula edodes mycelia (L.E.M.) extract restores melanoma-reactive T cells in melanoma-bearing mice via a mitigation of Treg-mediated immunosuppression. In this study, we investigated the effect of oral ingestion of the extract on peptide vaccine-induced anti-tumor activity. The day after subcutaneous inoculation in the footpad with B16 melanoma, mice were freely fed the extract and were vaccinated with a tyrosinase-related protein 2(180-188) peptide. The peptide vaccine was repeated thrice weekly. Melanoma growth was significantly suppressed in mice treated with both the peptide vaccine and L.E.M. extract compared with mice treated with vaccine or extract alone, and the effect was CD8(+) T cell-dependent. The combination therapy increased H-2K(b)-restricted and B16 melanoma-reactive T cells in the draining lymph nodes and spleen. Flow cytometric and immunohistological analyses revealed that the combination therapy significantly decreased the percentage of Tregs in the draining lymph nodes and spleen of melanoma-bearing mice compared to treatment with vaccine or extract alone. Kinetic analyses of peptide-specific T cells and Tregs revealed that induction of peptide-specific T cells by the peptide vaccine alone was transient, but when combined with L.E.M. extract, it efficiently prolonged the duration of peptide-specific T cell induction without increasing the percentage of Tregs. These results indicate that combination therapy enhances peptide vaccine-induced anti-tumor activity due to attenuation of the increase in the percentage of Tregs in tumor-bearing hosts.

Efficacy of orally administered Lentinula edodes mycelia extract for advanced gastrointestinal cancer patients undergoing cancer chemotherapy: a pilot study

This study investigated the influence of Lentinula edodes mycelia extract (LEM), an oral immunomodulator, on immune function and adverse events from chemotherapy. Subjects comprised 1 gastric and 7 colorectal cancer patients. The first course of treatment was chemotherapy alone and the second was chemotherapy plus concomitant administration of LEM. Adverse events and interferon (IFN)-γ production by CD4+ T, CD8+ T and CD56+ NK/NKT cells were evaluated at the end of each course. Grade 1 or 2 adverse events were observed at the end of the first course for 6 of 8 patients. In comparison, no patients displayed any adverse events at the end of the second course. Tendencies toward improved IFN-γ production by CD4+ T, CD8+ T and CD56+ NK/NKT cells was also seen. These results suggest that concomitant use of LEM with chemotherapy can decrease the incidence of adverse effects from cancer chemotherapy among patients with advanced cancer.

In vitro cytostatic and immunomodulatory properties of the medicinal mushroom Lentinula edodes

Lentinula edodes, known as "shiitake" is one of the widely used medicinal mushrooms in the Orient. Antitumour activity of extracts of this mushroom has been widely demonstrated in animals and humans. However, this activity was shown to be host mediated and not by direct cytotoxic activity to cancer cells. This study demonstrates cytotoxic and cell growth inhibitory (cytostatic) effect of aqueous extracts of the mushroom on MCF-7 human breast adenocarcinoma cell line using an MTT cytotoxicity assay. Such effect was demonstrated with fruit body and mycelial extracts, the difference being that there was no significant suppression on normal cells with the latter. Furthermore mycelial extracts did not induce any cytostatic effect in both cancer and normal cell lines based on a DNA synthesis assay. The significant suppression of the proliferation of cancer cells was reflected by the comparatively low IC(50) values and the simultaneous higher respective values on normal fibroblast cells. The immunostimulatory activity of both fruit body and mycelial extracts was tested by the lymphocyte transformation test (LTT), which is based on the capacity of active immunomodulators to augment the proliferative response of rat thymocytes to T mitogens in vitro. Both fruit body and mycelial preparations were able to enhance the proliferation of rat thymocytes directly and act as co-stimulators in the presence of the T-mitogen PHA. Interestingly both extracts, similarly to zymosan showed SI(comit)/SI(mit) ratios of about 2, indicating adjuvant properties. Overall L. edodes aqueous extracts have demonstrated direct inhibition of the proliferation of human breast cancer cells in vitro and immunostimulatory properties in terms of mitogenic and co-mitogenic activity in vitro.

Effects of Lentinus edodes mycelia on dietary-induced atherosclerotic involvement in rabbit aorta

Lentinus edodes mycelia lowers cholesterol levels and acts as an immunomodulator and tumor-inhibitor in animal models. Lentinus edodes mycelia contains eritadenine (C(9)H(11)O(4)N(5)) and glucans among other biological compounds. However, whether or not Lentinus edodes mycelia is anti-atherogenic remains unknown. We examined the effect of Lentinus edodes mycelia (L.E.M) on atherosclerosis in a rabbit model. Thirty-two Japanese white male rabbits were fed with 1.0% cholesterol for 8 weeks, then divided into groups and given 1) 1.0% cholesterol for over 8 weeks (control), 2) 1.0% cholesterol and 1.0% L.E.M for over 8 weeks, 3) 1.0% cholesterol and 2.0% L.E.M for over 8 weeks, and 4) 1.0% cholesterol and 4.0% L.E.M for over 8 weeks (n=8 each group). Total cholesterol (TC) was measured periodically throughout the experiment. After the experimental periods, the aortas were removed and atherosclerotic lesions were examined histologically, immunohistochemically and morphometrically to determine surface involvement (SI) and an atherosclerotic index (AI). Body weight and TC did not significantly differ among the four groups. Decreases in SI were significant in the 1% L.E.M (26.2+/-10.8%) and 2% L.E.M (29.3+/-15.7%) groups compared with the control (48.7+/-15.3%; p < 0.05). The AI was significantly decreased in the 1% L.E.M (6.62+/-4.31) and 2% L.E.M (7.49+/-3.49) groups compared with the control (16.96+/-9.21; p < 0.05). Foam cells aggregated in thickened intima of dietary-induced atherosclerotic lesions in the rabbit aorta. In contrast, the numbers of foam cells in the intima decreased in the experimental group. No-cholesterol-lowering action or dose-dependant effects of L.E.M were determined in this study, but atherosclerotic development was significantly inhibited, indicating that L.E.M had anti-atherogenic properties. L.E.M may inhibit atherosclerotic development in rabbit aorta and be beneficial as a nutritional supplement.

Effects of a mushroom mycelium extract on the treatment of prostate cancer

OBJECTIVES

To determine whether supplemental amounts of a polysaccharide/oligosaccharide complex obtained from a shiitake mushroom extract (SME) would lower the prostate-specific antigen (PSA) level in patients with prostate cancer.

METHODS

A total of 62 men (mean age 73.2 years, range 53.6 to 85.5) with histologically proven prostate cancer who had two consecutive elevated PSA readings were accrued to the study during a 3-month period. This was an open-label study in which the patients received oral administration of capsules containing SME given three times daily for 6 months. The endpoint for the trial was the lowering of the PSA levels.

RESULTS

Of the 62 men enrolled in the study, 61 were assessable. At 4 months, 1 patient withdrew because of unrelated surgery and 7 withdrew because of disease progression; none had responded with a decrease of greater than 50% in the PSA level. By 6 months, a total of 23 patients had progression and none had responded. Thirty-eight patients had stable PSA levels after 6 months. Although not the primary endpoint of the study, in other studies these patients could have been included as responders. When the patients' rates of PSA rise before study entry were analyzed, 4 (7%) had stabilized disease while taking SME. Thus, the final results for our study patients were 0 with a complete response, 0 with a partial response, 4 (7%) with stable disease, and 23 of 61 with progression while taking SME.

CONCLUSIONS

SME alone is ineffective in the treatment of clinical prostate cancer.

Cholesterol-lowering effects of maitake (Grifola frondosa) fiber, shiitake (Lentinus edodes) fiber, and enokitake (Flammulina velutipes) fiber in rats

The effects of mushroom fibers on serum cholesterol and hepatic low-density lipoprotein (LDL) receptor mRNA in rats were investigated. Rats were fed a cholesterol-free diet with 50 g/kg cellulose powder (CP), 50 g/kg maitake (Grifola frondosa) fiber (MAF), 50 g/kg shiitake (Lentinus edodes) fiber (SF), or 50 g/kg enokitake (Flammulina velutipes) fiber (EF) for 4 weeks. There were no significant differences in the body weight, food intake, liver weight, cecum weight, and cecum pH among the groups. Cecal acetic acid, butyric acid, and total short-chain fatty acid (SCFA) concentrations in the SF and EF groups were significantly higher than those in the other groups. The serum total cholesterol concentration in the CP group was significantly higher than that in the MAF and EF groups. The very LDL (VLDL) + intermediate-density lipoprotein (IDL) + LDL-cholesterol concentration in the CP group was significantly higher than that in the MAF, SF, and EF groups, whereas the high-density lipoprotein (HDL)-cholesterol concentration in the EF group was significantly lower than that in the other groups at the end of the 4-week feeding period. The hepatic LDL receptor mRNA level in the EF group was significantly higher than that in the CP group. The fecal cholesterol excretion in the MAF, SF, and EF groups was significantly higher than that in the CP group. The results of this study demonstrate that MAF and EF lowered the serum total cholesterol level by enhancement of fecal cholesterol excretion, and in particular, by enhancement of hepatic LDL receptor mRNA in EF group.