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PSK

Effect of PSK, a protein-bound polysaccharide from Coriolus versicolor, on drug-metabolizing enzymes in sarcoma-180 bearing and normal mice.

The effects of PSK and Propionibacterium acnes (anaerobic Corynebacterium) on hepatic drug-metabolizing enzymes were studied using sarcoma-180 bearing and non-tumor bearing mice. PSK had no influence on aminopyrine N-demethylase and aniline hydroxylase activities, cytochrome P-450 concentration in hepatic microsomes, and the reductase activity of cytochrome c in normal mice. The content of cytochrome P-450 was not significantly reduced in S-180 bearing mice. On the other hand, P. acnes administration significantly decreased the amount of cytochromes P-450 and b5 and aminopyrine N-demethylase activity. When FT-207 (Tegafur) was administered orally to S-180 bearing mice combined with the immunoadjuvants, only P. acnes significantly reduced the 5-FU levels in the serum and some organs.

Morphological and biochemical alterations of macrophages produced by a glycan, PSK.

A glycan extracted from Coriolus versicolor (PSK, Krestin) which has antitumor and immunomodulator properties produced marked morphological and biochemical changes when added to cultures of mouse peritoneal macrophages. The cells were more spread and elongated than in control cultures, and these changes were accompanied by alterations in the rate of protein and DNA synthesis. In PSK-treated murine peritoneal macrophages the rate of protein synthesis increased above the level seen in control cultures after two days and reached a level twenty-fold higher than control on day four; this elevated rate of protein synthesis was maintained throughout the seven-day observation period. DNA synthesis was induced after four days in the presence of PSK, and reached a level ten-fold higher than control baseline on day five. This induction of DNA synthesis, however, could not be attributed to a mitogenic activity on lymphocytes. The alterations caused by PSK in macrophage metabolism may be related to the immunomodulating and antitumor activities of PSK in vivo.[…]

[Effect of a protein-bound polysaccharide, PSK, on human hemopoietic progenitors]

Using in vitro clonal culture assays, we investigated the effects of PSK, a protein-bound polysaccharide derived from the cultured mycelium of CM101, Coriolus versicolor (Fr.) Quél in Basidiomycetes, on human hemopoietic progenitors. PSK alone did not stimulate colony formation by human bone marrow progenitors. Although 1-100 micrograms/ml of PSK had no effects on colony formation stimulated by erythropoietin and medium conditioned by phytohemagglutinin-stimulated leukocytes, more than 1 mg/ml of PSK inhibited all types of colony formation. In contrast, medium conditioned by PSK-stimulated leukocytes significantly stimulated formation of various types of colonies including erythroid bursts, granulocyte and/or macrophage colonies, eosinophil colonies, megakaryocyte colonies and mixed hemopoietic colonies. It is speculated that administration of the optimal dose of PSK can reduce the hematological suppression of antitumor drugs.[…]

Stimulation of interferon-gamma-induced human myelogenous leukemic cell differentiation by high molecular weight PSK subfraction.

PSK, a protein-bound polysaccharide extracted from the mycelia of Coriolus versicolor (Fr.) Quel, stimulated tumor necrosis factor-induced cytotoxicity against mouse L-929 fibroblast. PSK also stimulated interferon-gamma-induced differentiation of human myelogenous leukemic U-937 and THP-1 cells. The differentiated cells had higher proportions of cells that expressed NBT-reducing activity and alpha-naphthyl acetate esterase activity. Among four PSK subfractions, the highest molecular weight fraction (MW greater than 200 kD) had the most potent stimulating activity. This is the first report regarding direct PSK modulation of cytokine action.[…]

Competitive action of a biological response modifier, PSK, on a humoral immunosuppressive factor produced in tumor-bearing hosts.

We investigated the effect of PSK, a protein-bound polysaccharide obtained from the basidiomycetes Coriolus versicolor, on an immunosuppressive factor produced in tumor-bearing animals. Oral administration of PSK suppressed the growth of the tumor in C3H/He mice bearing X5563 plasmacytoma or MH134 hepatoma, but affected mice bearing MM102 mammary tumor little. PSK prevented the reduction in splenic lymphocyte blastogenesis caused by phytohemagglutinin that occurs in mice bearing X5563 tumors or MH134 hepatoma. The lymphocyte blastogenesis affected little by tumor or PSK in mice bearing MM102 tumors. The effect of sera on the blastogenesis of lymphocytes caused by phytohemagglutinin was different with different tumors in the C3H/He mice. Serum of mice bearing X5563 tumors inhibited blastogenesis, but serum of mice bearing MH134 hepatoma or MM102 tumors promoted it. The sera of mice bearing MH134 hepatoma contained both inhibitory and promotive factors; those of mice bearing X5563 tumors contained an inhibitory factor, and those of mice bearing MM102 tumors contained a promotive factor. The oral administration of PSK reduced the inhibition caused by the sera of mice bearing X5563 tumors. The promotive activity of sera from mice bearing MH134 hepatoma was augmented by PSK; that of sera in mice bearing MM102 tumors was not affected by PSK. Living Bacillus Calmette-Guérin did not have such effects in any of these mice. Serum immunosuppressive activity was also reduced by PSK in various tumor lines of rodents. These results suggest that PSK acts by reducing the activity of immunosuppressive factors produced in tumor-bearing hosts.[…]

Stimulation of human peripheral blood polymorphonuclear cell iodination by PSK subfractions.

A protein-bound polysaccharide, PSK, extracted from the mycelium of Coriolus versicolor (Fr.) Quel, stimulated the iodination (incorporation of radioactive iodine into an acid-insoluble fraction) of human peripheral blood polymorphonuclear cells (PMN), human promyelocytic leukemic HL-60 cells and human myeloblastic leukemic ML-1 cells. In contrast, PSK did not significantly increase the iodination of other cultured cell lines (U-937, THP-1, L-929, T98G, BALB 3T3). The PSK stimulation of iodination of both PMN and HL-60 cells depended on incubation time and temperature, and was significantly suppressed by the presence of myeloperoxidase inhibitors. Among various PSK subfractions, the highest molecular weight fraction (MW greater than 200 kD), or the fraction precipitated at pH 4.0-4.5, stimulated the iodination most. In contrast, natural and chemically modified glucans had little or no stimulation activity. The active PSK subfractions synergistically enhanced TNF stimulation of PMN iodination. The data suggest the presence of some unique components in PSK which directly stimulate the iodination of myeloperoxidase-positive cells.[…]

Cell surface changes of in situ macrophages induced by superimposed antigen.

Mice received an injection of sheep erythrocytes (SRBC) into the footpad ” prepared” or “not prepared” with a 7-day-prior injection of a protein-bound polysaccharide from Coriolus versicolor (PSK; Krestin), and the ultrastructure of in situ macrophages was studied at various intervals after the injection. A single SRBC injection into the footpad induced linear cell arrangements of several macrophages. The macrophages showed no prominent morphological alterations after SRBC digestion. When PSK-stimulated subcutaneous macrophages were challenged by SRBC, they rapidly sent out numerous long cytoplasmic projections which radiated in all directions. Such projections of neighboring macrophages tended to contact one another. At the following stage, a pronounced sequential alteration was noted, characterized by the interlocking of elongated projections. This provided massive aggregations of “activated” macrophages. These observations suggest the possibility that intercellular communication among “activated” macrophages was elicited, particularly in the subcutaneous region, and maintained through an intensive interaction of cytoplasmic projections. Further, the present results histologically support our previous report which shows that the “PSK-prepared” footpad site but not the “prepared” one supports development of a splenic humoral immune response following injection of superimposed SRBC.[…]

Effects of a protein-bound polysaccharide from a basidiomycetes against hepatocarcinogenesis induced by 3′-methyl-4-dimethylaminoazobenzene in rats.

PSK, extracted from mycelia of a strain of Coriolus versicolor, was administered to groups of 20 male Wistar rats before and during treatment with 3′-methyl-4-dimethylaminoazobenzene (3-MDAB). After 24 weeks, the survival rates were significantly higher in the groups given PSK before or with the 3-MDAB than in groups not given PSK or given PSK after 12 weeks of 3-MDAB treatment. Blood alpha-fetoprotein levels, determined every four weeks, increased in all groups after 3-MDAB treatment, but were significantly lower in the groups given PSK before or with the 3-MDAB than in the other groups. The results indicate that PSK had a suppressive effect on 3-MDAB-induced hepatocarcinogenesis.[…]

Chloromethane, Methyl Donor in Veratryl Alcohol Biosynthesis in Phanerochaete chrysosporium and Other Lignin-Degrading Fungi.

Chloromethane, a gaseous natural product implicated in methylation processes in Phellinus pomaceus, has been shown to act as methyl donor in veratryl alcohol biosynthesis in the lignin-degrading fungi Phanerochaete chrysosporium, Phlebia radiata, and Coriolus versicolor, none of which released detectable amounts of CH(3)Cl during growth. When P. chrysosporium was grown in a medium containing CH(3)Cl, levels of CH(3) incorporation into the 3- and 4-O-methyl groups of veratryl alcohol were very high and initially similar to those observed when the medium was supplemented with l-[methyl-H(3)]methionine. When CH(3)Cl was added to cultures actively synthesizing veratryl alcohol, incorporation of CH(3) was very rapid, with 81% of veratryl alcohol labeled after 12 h. By contrast, incorporation of CH(3) from l-[methyl-H(3)]methionine was comparatively slow, attaining 10% after 12 h. It is proposed that these lignin-degrading fungi possess a tightly channeled multienzyme system in which CH(3)Cl biosynthesis is closely coupled to CH(3)Cl utilization for methylation of veratryl alcohol precursors.[…]

Induction of immunopotentiation activity by a protein-bound polysaccharide, PSK (review).

A protein-bound polysaccharide, PSK, extracted from the mycelium of Coriolus versicolor (Fr.) Quel, has been recognized for its host-mediated induction of antitumor and antimicrobial activities in mice. Intravenous administration of PSK, in association with OK-432 (Picibanil), transiently induced endogenous production of a cytotoxic factor (CF) (possibly tumor necrosis factor, TNF) in normal mice. The ability to produce CF depended greatly on both dose and interval between administration of the PSK and OK-432. Although PSK has been reported to contain several active ingredients, unfractionated PSK has been used in almost all experiments performed so far. We recently reported that, of the four subfractions separated by successive filtration through membrane filters, only the highest molecular weight fraction F4 (MW greater than 200 kD) induced significant antimicrobial activity in mice. PSK stimulated the NBT-reducing activity of mouse peritoneal macrophages and the iodination (incorporation of radioactive iodine into an acid-insoluble fraction) of human peripheral blood polymorphonuclear cells (PMN). Among the subfractions of PSK, the highest molecular weight fraction F4, and the fraction precipitated at pH 4.0-4.5 (Fr. 4), stimulated macrophage NBT-reducing activity and PMN iodination most. In contrast, natural and chemically modified glucans had little or no stimulating activity. PSK, F4 or Fr. 4 additively or synergistically stimulated TNF-induced cytotoxicity against L-929 cells, differentiation of human myelogenous leukemia cell lines toward monocytes/macrophages, and iodination of human peripheral blood PMN. The active PSK subfractions significantly reduced the down regulation of specific 125I-TNF or 125I-IFN-gamma binding to cellular receptors. These data suggest that (i) immunopotentiation activity of PSK might be ascribed, at least in part, to stimulation of cytokine action and production, and (ii) PSK might have some unique structural features.[…]