Sources and Composition
Sources
Trametes versicolor, more commonly known as Turkey Tail Mushroom,
Historically, Turkey Tail polysaccharide (specifically PSK) have been used in Japan as anti-cancer adjuvants alongside other cancer therapies; first approved in 1977 as a prescription medication (in regards to isolated PSK) and in 1987 PSK itself accounted for more than 25% of total national expenditure for anticancer agents in Japan.[1]
Composition
The main bioactives in Turkey Tail are:
Neurology
Pain
PSP has been tested in rats to assess its interactions with pain (hot-plate test for tactile heat pain, acetic acid writhing test for chemical pain) and PSP appeared to have weak pain sensitizing effects relative to control.[6] This increase in pain sensitivity appears to have been related to pro-inflammatory effects of PSP, and was significantly inhibited by anti-inflammatories.[6]
Inflammation and Immunology
Mononuclear Cells
PSK may stimulate proliferation of PBMCs while inducing accumulation of interleukins (particularly IL-1α) within the cell.[6] Increased IL-8 levels result after stimulation of PBMCs by PSK, and this has been found in persons following oral ingestion of 1g PSK (with spikes appearing in 42-44% of persons within 3 hours, assay could not detect less than 25pg/mL) to a fairly variable level of 30-125pg/mL (data extracted from graph).[7]
Natural Killer Cells
The polysaccharide PSK appears to be a TLR2 agonist, and can stimulate Natural Killer (NK) cells to produce IFN-γ and increase their cytotoxicity;[8] although it is contested as to whether this is direct or indirect NK cell activation (may be vicarious through Dendritic Cells).[9][10] Abolishment of the TLR2 receptor in mice abolishing NK cell activity induced by PSK.[8]
Interactions between tumors and Turkey Tail mushroom are partially dependent on NK cells, and mostly dependent on both NK cells and T-Cells.[7]
In women with breast cancer who had NK cell activity significantly reduced due to radiotherapy, a trend towards increasing NK cell activity was noted with 6g daily after 4 weeks but aside from not being present at 6 weeks nor being present with 9g ingestion this failed to be statistically significant.[11] This same trend existed for NK cell count.[11]
T-Cells
In vitro, incubation of 10-200ug/mL PSK appears to increase CD4+ and CD8+ T-cells and overall splenocyte proliferation.[8]
An increased level of cytotoxic T-cells against tumors has been noted in animals fed PSK (100mg/kg) after injection of tumor cells.[8]
Total levels of CD8 cytotoxic T-cells appear to increase after ingestion of 3-9g Turkey Tail over 6 weeks in women with breast cancer, but this was not statistically significant.[11]
B-Cells
Although increasing splenocyte proliferation, 10-200mcg/mL PSK appears to reduce the percentage of B-Cells in vitro from 46.8+/-0.6% to 22.4+/-1.9%[8] which may be related to the ability of PSK to suppress B-Cell growth via IL-15 secretion from T-Cells.[12]
A trend to increase CD19+ B-cells was noted in women given 6-9g Turkey Tail daily for 6 weeks.[11]
Interactions with Cancer
Breast Cancer
Mechanistically, the polysaccharide PSK appears to activate PBMCs via the TLR2 receptor directly and PBMCs then activate Natural Killer (NK) cells to release IFN-γ and lyse breast cancer cells.[13] TLR2 activation appears to enhance NK cell activity (as well as TLR8,9),[14] and PSK has once been demonstrated to enhance breast cancer therapries that target HER2 (a protein that is seen as a breast cancer therapeutic target[15]); with this study noting augmentation of Trastuzumab (Herceptin™).[13]
In women with breast cancer (Stage I-III) consuming Turkey Tail mycelia powder at 3, 6, or 9g daily (two divided doses) over 6 months resulted in normalization of lymphocyte counts that were reduced by radiotherapy at only 6-9g daily (3g not being significantly different than placebo) with the measurement after 6 weeks exceeding pre-radiation levels.[11]
Leukemia
In promyelocytic leukemia cells (HL-60), incubation of various extracts of Turkey Tail resulted in both the ethanolic and water extracts suppressing cell viability in a concentration dependent manner with more efficacy in the water extract; with 7.5-10mcg/mL suppressing viability to lower than 25% of baseline.[5]
Proliferation also appears to have been reduced at 5-10mcg/mL water extract of Turkey Tail that was associated with a decrease of cells in S phase (41.2% to 11.3%) with concomitant increases in G1 and G2/M phases.[5]
In regards to cytokines, a suppression of IL-8 was noted in HL-60 cells.[5]
Safety and Toxicicity
Up to 9g of Turkey Tail daily for 6 months in women with Breast Cancer has failed to note any significant side effects and was deemed well tolerated.[11]
