In vitro immunomodulating effect of protein-bound polysaccharide, PSK on peripheral blood, regional nodes, and spleen lymphocytes in patients with gastric cancer

An overview of fungal glycan-based therapeutics

Edible medicinal mushrooms have been traditionally used for health promotion and longevity in China and other East Asian countries for centuries. Structural and pharmacological studies revealed that fungal glycans show multiple physiological and healthy promoting effects including immunomodulation, anti-tumor, anti-aging, anti-oxidation, hypoglycemic, hypolipidemic, anti-radiation, and other effects. Fungal glycans isolated from different kinds of medicinal mushrooms are partially purified and clinically tested. Without serious safety concerns of mostly glycans from edible mushrooms and/or the cultured mycelium, eight of them are approved by Chinese Food and Drug Administration (SFDA) and used clinically in China since 1980s. In this chapter, 185 independent studies involving in biochemical, pharmacological and clinical studies of fungal glycans during the past four decades (1977-2019) from PubMed, CNKI (China National Knowledge Infrastructure) and Wanfang databases are summarized. In future, understanding the fungal glycan-based drugs at molecular biological level would be needed to comprehend the clinical efficacy of glycan-based drugs.

Introduction

This chapter focuses on the discovery of the Major Histocompatibility Complex (MHC) in mice (H-2) and in humans (HLA), and on the role played by the International HLA Workshops in the analysis and characterization of this complex genetic system. The early days of Tumour Immunology and the importance of the definition of Tumour Associated Transplantation Antigens (TATA) are also discussed. Today we know that tumour cells can be killed by T lymphocytes by recognizing tumour antigenic peptides presented by MHC molecules and they can also escape this recognition by losing the expression of MHC molecules. This important phenomenon has been profoundly studied for many years both in my lab in Granada and in other laboratories. The results of this research have important implications for the new generation of cancer immunotherapy that boosts T cell responses. A historical perspective of major discoveries is presented in this chapter, with the names of the scientists that have made a significant contribution to the enormous progress made in the field of Tumour Immunology.

HLA Class-I Expression and Cancer Immunotherapy

The impact of HLA class I loss in cancer immunotherapy is carefully analyzed. Why some metastatic lesions regress and other progress after immunotherapy? Are T lymphocytes responsible for tumour rejection and how these responses can be boosted? These questions are discussed in the context of the molecular mechanisms responsible for MHC/HLA class I alterations. If the metastatic tumour cells harbor "irreversible/hard" HLA lesions, they will escape and kill the host. In contrast, if the molecular lesion is "reversible/soft", tumor cells can potentially recover HLA-class I expression and can finally be destroyed. These important new concepts are integrated together and gain a great importance in the new era of "immune checkpoint antibodies". Finally, the ability to recover HLA-I expression in tumours harboring "structural-irreversible-hard" genetic lesions is seen as a challenge for the future investigation.

A systematic review and meta-analysis of randomized trials on the role of targeted therapy in the management of advanced gastric cancer: Evidence does not translate?

It is still uncertain if targeted therapy-based regimens in advanced gastric cancer actually produce survival benefit. To shed light on this important question, we performed a systematic review and meta-analyses on each relevant targeted-pathway. By searching literature databases and proceedings of major cancer meetings in the time-frame 2005-2014, 22 randomized clinical trials exploring targeted therapy for a total of 7022 advanced gastric cancer patients were selected and included in the final analysis. Benefit was demonstrated for antiangiogenic agents in terms of overall survival (HR 0.759; 95%CI 0.655-0.880; p < 0.001). Conversely no benefit was found for EGFR pathway (HR 1.077; 95%CI 0.847-1.370; p = 0.543). Meta-analysis of HER-2 pathway confirmed improvement in terms of survival outcome, already known for this class of drugs (HR 0.823; 95%CI 0.722-0.939; p = 0.004). Pooled analysis demonstrated a significant survival benefit (OS: HR 0.823; PFS: HR 0.762) with acceptable tolerability profile for targeted-based therapies as compared to conventional treatments. This finding conflicts with the outcome of most individual studies, probably due to poor trial design or patients selection. In conclusion, our findings demonstrate a significant survival benefit for targeted therapy in its whole, which can be ascribed to anti-angiogenic and anti-HER2 agents.

Anticancer properties of polysaccharides isolated from fungi of the Basidiomycetes class

Basidiomycete mushrooms represent a valuable source of biologically active compounds with anticancer properties. This feature is primarily attributed to polysaccharides and their derivatives. The anticancer potential of polysaccharides is linked to their origin, composition and chemical structure, solubility and method of isolation. Moreover, their activity can be significantly increased by chemical modifications. Anticancer effects of polysaccharides can be expressed indirectly (immunostimulation) or directly (cell proliferation inhibition and/or apoptosis induction). Among the wide range of polysaccharides with documented anticancer properties, lentinan, polysaccharide-K (PSK) and schizophyllan deserve special attention. These polysaccharides for many years have been successfully applied in cancer treatment and their mechanism of action is the best known.

Biological mechanism and clinical effect of protein-bound polysaccharide K (KRESTIN(®)): review of development and future perspectives

The mechanism of action of protein-bound polysaccharide K (PSK; KRESTIN(®)) involves the following actions: (1) recovery from immunosuppression induced by humoral factors such as transforming growth factor (TGF)-β or as a result of surgery and chemotherapy; (2) activation of antitumor immune responses including maturation of dendritic cells, correction of Th1/Th2 imbalance, and promotion of interleukin-15 production by monocytes; and (3) enhancement of the antitumor effect of chemotherapy by induction of apoptosis and inhibition of metastasis through direct actions on tumor cells. The clinical effectiveness of PSK has been demonstrated for various cancers. In patients with gastric or colorectal cancer, combined use of PSK with postoperative adjuvant chemotherapy prolongs survival, and this effect has been confirmed in multiple meta-analyses. For small-cell lung carcinoma, PSK in conjunction with chemotherapy prolongs the remission period. In addition, PSK has been shown to be effective against various other cancers, reduce the adverse effects of chemotherapy, and improve quality of life. Future studies should examine the effects of PSK under different host immune conditions and tumor properties, elucidate the mechanism of action exhibited in each situation, and identify biomarkers.

ECA39 is a novel distant metastasis-related biomarker in colorectal cancer

AIM

To investigate the possible role of polysaccharide-K (PSK) -related markers in predicting distant metastasis and in the clinical outcome of colorectal cancer (CRC).

METHODS

Firstly, we used protein microarrays to analyze the in vitro expression profiles of potential PSK-related markers in the human colorectal adenocarcinoma cell line SW480, which carries a mutant p53 gene. Then, we investigated the clinical implications of these markers in the prognosis of CRC patients.

RESULTS

ECA39, a direct target of c-Myc, was identified as a candidate protein affected by the anti-metastatic effects of PSK. Immunohistochemistry revealed that ECA39 was expressed at significantly higher levels in tumor tissues with distant metastases compared to those without (P<0.00001). Positive ECA39 expression was shown to be highly reliable for the prediction of distant metastases (sensitivity: 86.7%, specificity: 90%, positive predictive value: 86.7%, negative predictive value: 90%). A significantly higher cumulative 5-yr disease free survival rate was observed in the ECA39-negative patient group (77.3%) compared with the ECA39-positive patient group (25.8%) (P<0.05).

CONCLUSION

Our results suggest that ECA39 is a dominant predictive factor for distant metastasis in patients with advanced CRC and that its suppression by PSK might represent a useful application of immunotherapy as part of a program of integrated medicine.

Identification of the protein components of protein-bound polysaccharide (PSK) that interact with NKL cells

We identified the protein components of a protein-bound polysaccharide (PSK) that are responsible for the biological function of this immunomodulator in its interaction with NKL cells, an NK-derived cell line previously known to be activated by this extract, obtained from the basidiomycete Coriolus versiocolor. In addition, we show that PSK protein interacts with NKL cells through a different receptor from that used by IL-2. This was deduced from the different molecular weights of the PSK/NKL and IL-2/NKL receptor complexes. We show that PSK is composed of a highly glycosylated 12-kDa protein. Protein-bound polysaccharide interacts in vitro with an NKL receptor of approximately 48 kDa, whereas IL-2 shows a similar interaction with NKL receptor proteins of approximately 64 and 75 kDa. Our results may explain why PSK and IL-2 use completely different intracellular routes for their biological activities in NKL cells-i.e., regulating different PKC isozymes, mitogen-activated protein kinases, and nuclear transcription factors.

Immunomodulatory effects of low dose cis-Diaminedichloroplatinum (cisplatin) combined with UFT and PSK in patients with advanced colorectal cancer

It is well known that cell-mediated immunity is suppressed in patients with neoplastic diseases. We have reported that soluble receptors for interleukin-2 (sIL-2R) and tumor necrosis factor (sTNF-R1) are elevated in the serum of patients with advanced colorectal cancer. The presence of these soluble receptors and immunosuppressive cytokines, including interleukin-10 (IL-10), might be important in the mechanisms of immunosuppression. cis-Diaminedichloroplatinum (cisplatin) has been reported to immunomodulate, especially when used in low dose in combination with 5-Fluorouracil (5-FU). In this study, cisplatin and UFT, a form of uracil and tegafur which is a prodrug of 5-FU, were administered with immunomodulator Polysaccharide K (PSK) to ten patients with colorectal cancer, who showed distant metastasis in the liver or lung, and the serum levels of sIL-2R and sTNF-R1 and the production of gamma-interferon (gamma-INF) and interleukin-10 by peripheral blood mononuclear cells were measured. The serum concentrations of sIL-2R and the production of IL-10 were reduced (p < 0.05) after 2 months of treatment. Thus, this combination appeared to have immunomodulative potential in patients with advanced colorectal cancer.

Protein-bound polysaccharide (PSK) induces cytotoxic activity in the NKL human natural killer cell line

We studied the effect of protein-bound polysaccharide PSK on the activation of the human natural killer cell line NKL. We observed an increased natural killer cytotoxic activity against different tumor cells (K562, Daudi, and U937) when a standard 2- to 3-h 51chromium release assay was performed. The results parallel those obtained after treatment of the NKL cell line with interleukin-2. The highest cytotoxic activity was reached at a concentration of 100 microg/ml of PSK. This natural killer activation was inhibited when the PSK dose was 1,000 microg/ml. None of the cell surface markers that were analyzed by fluorescence-activated cell sorting showed variations after PSK or interleukin-2 treatment of NKL cells. These markers included CD2, CD11b, CD11c, CD18, CD16, CD54, CD56, CD98, CD25, CD122, HLA class I, HLA class II, CD94, ILT2, p58.1, p70, and NKp46. One of these markers (NKp46) is a major triggering receptor reported to be involved in the natural cytotoxicity of fresh or cultured human natural killer cells. In our study, another triggering receptor must be implicated in PSK-induced natural killer lysis. Our data suggest that PSK is an important biological response modifier of natural killer cells in vitro and may prove to be useful for the study of human natural killer cell biology.

Gut bacterial translocation during total parenteral nutrition in experimental rats and its countermeasure

BACKGROUND

The use of total parenteral nutrition (TPN) is commonly associated with mucosal lining of the intestinal tract, causing degenerative changes within the gut-associated lymphoid tissue (GALT). These phenomena are probably caused by the translocation of indigenous intestinal bacteria into other organs and tissues where they induce infections.

METHODS

Using TPN model rats, this paper looks at the result of the investigation of the action of PSK (proteoglycan), a biological response modifier, which appears to suppress bacterial translocation and maintain local immunity activity.

RESULTS

Culture of mesenteric lymph nodes obtained post-TPN demonstrate a bacterial rate as high as 60%. Immunohistochemical examination indicates a reduction in the number of plasma cells and a decrease in S-IgA production and secretion. A similar reduction in S-IgA within bile and portal venous blood was also confirmed. Continuous oral administration of PSK in a daily dose of 1,000 mg/kg had a protective effect against the degeneration of GALT. A staining in immunocytes of Peyer's patches using immunohistochemical study was performed after administration of PSK and revealed constant levels of MHC-I, MHC-II, T helper cells, and interleukin-2 producing cells, supporting the protective role of PSK against degeneration of GALT with a subsequent reduction in bacterial translocation.

CONCLUSIONS

Proteoglycan can restore the impaired local immunity in the intestinal tract to normal levels and suppression of the bacterial translocation to provide an important function for patients receiving TPN treatment.

Induction in the mouse of gene expression of immunomodulating cytokines by mushroom polysaccharide-protein complexes

Two antitumor polysaccharide-protein complexes, PSPC and PSK from mushrooms, were compared for their modulating effect on cytokine and cytokine receptor gene expression. RNA samples were isolated from the splenocytes and peritoneal exudate cells of the untreated or treated mice. Reverse transcription-polymerase chain reaction (RT-PCR) was used to analyze the cytokine gene expression. Nine out of 17 cytokine mRNAs and 5 out of 6 cytokine receptor mRNAs were detected in the splenocytes and peritoneal exudate cells from both untreated and treated mice. However, IL-4 was only detected in the splenocytes while IL-7 and IL-1R(typeI) were only detected in the peritoneal exudate cells. Among the 9 cytokine genes, the expression level of M-CSF was up-regulated in splenocytes and peritoneal exudate cells of the mice by PSPC and PSK. The expression level of TNF-alpha was only up-regulated in the peritoneal exudate cells by PSK, but not by PSPC.

Possible predictive markers of immunotherapy in esophageal cancer: retrospective analysis of a randomized study. The Cooperative Study Group for Esophageal Cancer in Japan

The aim of this report is to evaluate retrospectively the data from a prospective randomized study of 158 esophageal cancer patients who actually completed therapy with protein-bound polysaccharide P (PSK) and the 5-year survivals with and without raised alpha 1-antichymotrypsin and sialic acid levels to determine the value of these parameters in predicting effectiveness of immunotherapy. There was a significant difference in survival between the patients with and without PSK therapy. The survival of the radiochemotherapy plus PSK group treated for > 3 months was significantly better than that of the radiochemotherapy group. Among the patients with abnormal levels of alpha 1-antichymotrypsin and sialic acid, those who received PSK may have a significantly better survival than those without PSK. These results indicate that the preoperative serum levels of alpha 1-antichymotrypsin and sialic acid may possibly predict the effectiveness of immunotherapy using PSK.

Mechanism of stimulation of human natural killer cytotoxicity by arabinogalactan from Larix occidentalis

Cultures of human peripheral blood mononuclear cells (PBMC) as well as cultures of preseparated peripheral non-adherent cells (PNAC) and monocytes showed enhancement of natural killer (NK) cytotoxicity against K562 tumor cells when pretreated with arabinogalactan from Larix occidentalis for 48-72 h. Lack of enhanced responses of PBMC (37% of donors) did not necessarily mean that PNAC and monocyte cultures were also non-responsive to arabinogalactan treatment. Moreover, PBMC, PNAC and monocytes of individual donors could exhibit various responses to arabinogalactan when cultures derived from bleedings after intervals of several months were assayed. Arabinogalactan-mediated enhancement of NK cytotoxicity was not initiated directly but was found to be governed by the cytokine network. Generally, arabinogalactan pretreatment induced an increased release of interferon gamma (IFN gamma), tumor necrosis factor alpha, interleukin-1 beta (IL-1 beta) and IL-6 but only IFN gamma was involved in enhancement of NK cytotoxicity since cytotoxicity enhancement of PBMC and PNAC but not that of monocytes could be blocked when anti-IFN gamma antibodies were present during pretreatment. The presence of anti-IL-2 antibodies completely blocked NK cytotoxicity enhancement of PBMC and only moderately that of PNAC and monocytes. This blocking effect was also observed when no detectable increase of IL-2 release could be recorded. The receptor specificity of arabinogalactan is not well characterized. Initial information obtained from comparative studies indicated that arabinogalactan presumably interacts with a receptor that showed specificity for a NK-cytotoxicity-enhancing oligo-saccharide from Viscum album extracts since the action of both components was not synergistic but rather competitive.

Postoperative PSK and OK-432 immunochemotherapy for patients with gastric cancer

We evaluated the effects of chemotherapy given postoperatively with and without immunomodulators on the survival of patients who had undergone resection for gastric cancer. We conducted a retrospective survey of data on 963 Japanese patients treated at our department of surgery between 1965 and 1987. Data related to the duration of postoperative survival were calculated for those who received chemotherapy, i.e. an individualized combination of various agents given with or without the immunomodulators PSK, a protein extract of the fungus Coriolus versicolor, and/or OK-432, a preparation of an attenuated strain of Streptococcus (immunochemotherapy). Postoperative immunochemotherapy was more often prescribed for patients with advanced disease. The survival of patients who received immunochemotherapy was shorter than that of patients who received only chemotherapy. In a subgroup of patients adjusted for disease stage, the survival of those on chemotherapy versus immunochemotherapy did not differ significantly at any stage. For optimal results, a protocol for postoperative immunochemotherapy needs to be designed and investigated prospectively and according to the stage of gastric cancer. The stage III gastric cancers seem amenable to a favorable response.

Effect of PSK and its subfractions on peripheral blood lymphocytes mediated cytotoxicity against urinary bladder tumor cells

Our previous studies have indicated that the protein-bound polysaccharide Kreha (PSK) enhances the cytotoxic activity of peripheral blood lymphocytes (PBL) against the T24 human urinary bladder tumor cell line in patients with bladder tumor. Since PSK consists of a mixture of various kinds of protein-bound polysaccharides, the present study was designed to examine which subfractions of PSK mediated the enhancement of cytotoxicity. When PSK was separated according to size, treatment of PBL with the 50 kilodalton (kd) or less fraction killed T24 cells more efficiently than unfractionated PSK-treated PBL. The higher molecular weight fractions did not enhance killing above the control level. PSK was fractionated on a diethylaminoethyl (DEAE)-cellulose column to obtain a protein rich fraction that absorbed onto the column and a polysaccharide rich fraction that did not. PBL treated with the polysaccharide rich fraction were able to kill T24 cells more effectively than unfractionated PSK-treated PBL. The protein rich fraction had no effect on the killing. Further fractionation of the polysaccharide rich fraction was performed by differential precipitation with ammonium sulfate. PBL treated with the precipitated fraction at 70-80% saturation (PSK Fraction D) enhanced cytotoxicity equal to that of the polysaccharide rich fraction. Treatment of PBL with the other fractions did not augment the cytotoxicity. These enhancement by PSK fractions were observed in healthy donors and also in patients with bladder tumor. An increase of the proliferative response of PBL to PSK Fraction D as well as unfractionated PSK was observed. Treatment of PBL with PSK Fraction D had no effect on the proportion of PBL binding to T24 cells, thus suggesting a post-binding effect. The structure of PSK Fraction D as inferred from the results of methylation analysis was mainly an alpha-glucan. These results demonstrate that PSK mediated enhancement of cytotoxicity and proliferation of PBL may be largely due to an alpha-glucan of less than 50 kd.

Antitumor activity of polysaccharide from a Chinese medicinal herb, Acanthopanax giraldii Harms

The results of experiments with Acanthopanax giraldii polysaccharide (AGP) demonstrated that it inhibited the growth of solid Sarcoma 180 and prolonged the survival time significantly. In tumor-bearing mice, AGP enhanced the phagocytosis and chemiluminescence of macrophages. By the immunofluorescent method, binding of the third component of complement (C3) cleavage product to macrophages and proportion of C3 positive cells were increased. In crossed immunoelectrophoresis, human serum C3 was converted by AGP and appeared as the 3rd peak. The height of the 3rd peak was directly proportional to doses of AGP. The residual CH50 units of human serum decreased dose-dependently. These results suggest that the antitumor activity of AGP is related to the enhancement of immune responses.

Immunomodulation by orally administered protein-bound polysaccharide PSK in patients with gastrointestinal cancer

The present study was designed to assess the effects of the protein-bound polysaccharide PSK on the immunological status of patients with gastrointestinal cancer. Twenty-nine gastric and 18 colorectal cancer patients were randomly assigned to either the control or PSK group. Patients in the PSK group were given 3.0 g of PSK orally before surgery, either daily or every other day. Patients in the control group received no PSK. The data of peripheral blood lymphocytes (PBL) were compared before and after administration of PSK, and those of the regional node lymphocytes (RNL) were compared between the control and the PSK group. The results indicate that the effects of PSK were significantly influenced by the duration of administration, but not by the frequency of administration. In the patients belonging to the short term PSK group (administration less than 14 days), the response of the PBL to PSK and Con A become significantly stronger compared to before the administration of PSK, whereas the cytotoxicity against K562 and KATO-3, and the proportion of CD16+ cells increased significantly in those patients belonging to the long term PSK group (greater than or equal to 14 days). In addition, the proportion of CD9 + 11b + suppressor T cells decreased in the RNL of the short term PSK group, whereas the proportion of CD4 + Leu8 - helper T cells in the RNL increased in the long term PSK group. These results suggest that the oral administration of PSK leads to the suppression of suppressor cells in the RNL.(ABSTRACT TRUNCATED AT 250 WORDS)