Protective effects of a protein-bound polysaccharide, PSK, on Candida albicans infection in mice via tumor necrosis factor-alpha induction

Antifungal and anticancer effects of a polysaccharide-protein complex from the gut bacterium Raoultella ornithinolytica isolated from the earthworm Dendrobaena veneta

The polysaccharide-protein complex (PPC) isolated from metabolites of gut bacteria Raoultella ornithinolytica from Dendrobaena veneta earthworms exhibits activity against Candida albicans, in breast ductal carcinoma (line T47D) and in the endometrioid ovarian cancer line (TOV-112D) in vitro. The action against C. albicans was analyzed using light, SEM, TEM, and AFM microscopes. The changes observed indicated two directions of the action of the complex, that is, disturbance of metabolic activity and cell wall damage. The PPC is an adhesion-promoting complex inducing death of C. albicans cells by necrosis. Owing to its significant effect on C. albicans, the complex is a promising source of antifungal compounds. The PPC showed a minimal cytotoxic effect against human skin fibroblasts; however, the cytotoxicity against the T47D line was determined at 20% and 15% against the TOV-112D line. The action of the PPC against the T47D line exerted a cytopathic effect, whereas in the TOV-112D line, it caused a reduction in the cell number. The PPC induced death of tumor cells by apoptosis and necrosis. In view of the negligible cytotoxicity on fibroblasts, the PPC will be subjected to chemical modifications to increase its antitumor activity for prospective medical applications.

Protective effect of Artin M from extract of Artocarpus integrifolia seeds by Th1 and Th17 immune response on the course of infection by Candida albicans

The immunoregulatory effect of Artin M and jacalin from extract of Artocarpus integrifolia seeds (jack extract) against infection with Candida albicans was investigated. Swiss mice received jack extract containing 500 μg protein/ml PBS intraperitoneally (i.p.) or PBS alone and after 72 h were infected i.p. with C. albicans CR15 (10(7)) and sacrificed after 30 min, 2, 6, 24, and 72 h. ELISA analysis revealed that in jack extract-treated mice IFN-γ was predominantly produced versus IL-10 in control mice. These results suggest that jack extract induced a protective immune response, since C. albicans clearance was complete at 72 h postinfection. Jack extract presents two lectins (Artin M and jacalin) with distinct biological properties. Artin M was able to induce IL-12 production by macrophages. Also, Artin M in different concentrations, associated with jacalin or in jack extract induced both IFN-γ and IL-17 production. As a consequence, phagocytic and candidacidal activity increased significantly. Alanine aminotransferase activity (ALT) was used as parameter for damage of the liver. The activity of ALT correlated with inoculum size that increased significantly in control group, however, mice pretreated with jack extract 3 days before infection presented normal ALT. Mice pretreated with jack extract that received a lethal inoculum of Candida presented 90% survival versus 20% among controls or mice pretreated with jacalin. Thus, the results suggest that Artin M by itself, associated with jacalin or present in jack extract is able to induce protective Th1 and Th17 immune responses against Candida albicans infection.

Aureobasidium-derived soluble branched (1,3-1,6) beta-glucan (Sophy beta-glucan) enhances natural killer activity in Leishmania amazonensis-infected mice

The beta-glucans derived from yeast cell walls have been reported for having many immunomodulatory activities in vivo and in vitro. In this study, Aureobasidium-derived soluble branched (1,3-1,6) beta-glucan (Sophy beta-glucan) was checked for natural killer (NK) activity and for the production of IFN-gamma and IL-4 in Leishmania amazonensis infection. The main experiment was performed with a group of female C57BL/6 and BALB/c mice, orally supplemented with 5% of Sophy beta-glucan and infected with promastogotes of L. amazonensis (1 x 10(7)) into the footpad. Increase in the footpad thickness with time was observed in BALB/c mice in spite of the oral Sophy beta-glucan supplement, but it was less in C57BL/6 mice. The difference in overall mean footpad thickness between 'infection only' versus 'infection + glucan' groups was statistically significant (P < 0.001). High NK activity in C57BL/6 than BALB/c mice was observed in 'glucan only' group compared to the control group and also in 'infection + glucan' group compared to 'infection only' group. The difference in the NK activity among these groups was significant (P < 0.05). The IFN-gamma level increased at weeks 7 and 8 post-infection in C57BL/6 mice and was significantly high in 'infection + glucan' group compared to the 'infection only' group (P < 0.05). IL-4 levels did not increase up to detectable levels throughout the study. The results led a conclusion that Sophy beta-glucan enhances NK activity and cellular immunity in L. amazonensis-infected mice.

Evaluation of widely consumed botanicals as immunological adjuvants

BACKGROUND

Many widely used botanical medicines are claimed to be immune enhancers. Clear evidence of augmentation of immune responses in vivo is lacking in most cases. To select botanicals for further study based on immune enhancing activity, we study them here mixed with antigen and injected subcutaneously (s.c.). Globo H and GD3 are cell surface carbohydrates expressed on glycolipids or glycoproteins on the cell surface of many cancers. When conjugated to keyhole limpet hemocyanin (KLH), mixed with an immunological adjuvant and administered s.c. the magnitude of the antibody responses against globo H, GD3 and KLH depend largely on the potency of the adjuvant. We describe here the results obtained using this s.c. immunization model with seven botanicals purported to have immune stimulant effects.

METHODS

Groups of 5-10 mice were immunized with globo H-KLH or GD3-KLH mixed with botanical, saline or positive control immunological adjuvant, s.c. three times at 1 week intervals. Antibody responses were measured 1 and 2 weeks after the 3rd immunization. The following seven botanicals and fractions were tested: (1) H-48 (Honso USA Co.), (2) Coriolus versicolor raw water extract, purified polysaccharide-K (PSK) or purified polysaccharide-peptide (PSP) (Institute of Chinese Medicine (ICM)), (3) Maitake extract (Yukiguni Maitake Co. Ltd. and Tradeworks Group), (4) Echinacea lipophilic, neutral and acidic extracts (Gaia Herbs), (5) Astragalus water, 50% or 95% ethanol extracts (ICM), (6) Turmeric supercritical (SC) or hydro-ethanolic (HE) extracts (New Chapter) or 60% ethanol extract (ICM) and (7) yeast beta-glucan (Biotec Pharmacon). Purified saponin extract QS-21 (Antigenics) and semisynthetic saponin GPI-0100 (Advanced BioTherapies) were used as positive control adjuvants. Sera were analyzed by ELISA against synthetic globo H ceramide or GD3 and KLH.

RESULTS

Consistent significant adjuvant activity was observed after s.c. vaccination with the Coriolus extracts (especially PSK), a 95% ethanol extract of Astragalus and yeast beta-glucan, and (to a lesser extent) Maitake. Antibodies against KLH in all cases and against globo H in most cases were induced by these botanicals. Little or no adjuvant activity was demonstrated with H-48 or Echinacea extracts or the Astragalus water extract. Experiments with GD3-KLH as immunogen confirmed the adjuvant activity of the Coriolus, yeast beta-glucan and Astragalus extracts. While extraction with ethanol concentrated the active ingredients in Astragalus, it had no impact on Coriolus where the 90% ethanol precipitate and solute were equally active.

CONCLUSIONS

Some, but not all, botanicals purported to be immune stimulants had adjuvant activity in our model. PSK and Astragalus were surprisingly active and are being further fractionated to identify the most active adjuvant components.

PROTECTIVE EFFECT OF A PROTEIN-BOUND POLYSACCHARIDE, PSK, ON CLP-INDUCED SEPSIS IN MICE TRANSPLANTED ORTHOTOPICALLY WITH COLON TUMOR

We investigated the effects of a protein-bound polysaccharide, PSK, on the resistance of tumor-bearing mice against sepsis induced by cecal ligation and puncture (CLP). (a) In BALB/c mice that had received intracecal transplantation of colon 26 (C26) tumor, CLP with a 21-gauge needle significantly shortened the survival time, compared with that of non-tumor-bearing mice. Oral administration of PSK to such mice resulted in a significant prolongation of the survival time and increase of the survival rates. The effects were dependent on the timing of PSK administration and the dose. (b) CLP significantly increased the IL-10 level in serum, the IL-10 gene expression by spleen cells, the number of IL-10-producing CD4-positive T cells, and the productivity of IL-10 by spleen of tumor-bearing mice compared with that of non-tumor-bearing mice. PSK administration to such mice suppressed the increase. Further, PSK prevented the reduction of gene expression of IFN-gamma and the number of IFN-gamma-producing CD4-positive T cells and IFN-gamma productivity by spleen cells of tumor-bearing CLP-treated mice. (c) Treatment with anti-IFN-gamma monoclonal antibody before CLP significantly reduced the effects of PSK. These findings suggest that the protective effect of PSK on the CLP-induced sepsis in mice transplanted orthotopically with C26 tumor is possibly mediated by suppression of IL-10 and promotion of IFN-gamma.

Protein-bound polysaccharide isolated from basidiomycetes inhibits endotoxin-induced activation by blocking lipopolysaccharide-binding protein and CD14 functions

The protein-bound polysaccharide isolated from basidiomycetes (PSK) is a biological response modifier capable of exhibiting various biological activities, such as antitumor and antimicrobial effects. In the present study, we found that PSK suppressed interleukin (IL)-6 production in murine peritoneal macrophages stimulated with endotoxic lipopolysaccharide (LPS) and its synthetic lipid A (compound 506). Nitric oxide production and p38 mitogen-associated protein kinase phosphorylation induced in a murine macrophage cell line, J774-A1, by LPS and compound 506 were also inhibited by PSK. Further, PSK distinctly suppressed nuclear factor-kappaB activation in Ba/F3 cells expressing mouse Toll-like receptor 4 and MD-2, following stimulation with LPS and compound 506, however, not with Taxol. These PSK-induced inhibitory activities were caused by inhibition of the physical associations of LPS with LPS-binding protein (LBP) and CD14. PSK also protected mice from LPS-induced lethality, presumably by down-regulating IL-6 and tumor necrosis factor-alpha concentrations in serum. These findings indicate that PSK, which also has an ability to regulate LBP/CD14 functions, may be useful for clinical control of endotoxic sepsis.

Immunostimulating properties of intragastrically administered Acetobacter-derived soluble branched (1,4)-beta-D-glucans decrease murine susceptibility to Listeria monocytogenes

We previously found that AC-1, an extracellular polysaccharide, produced by Acetobacter xylinum and composed of (1,4)-beta-D-glucan with branches of glucosyl residues, showed a strong activity to induce production of interleukin-12 (IL-12) p40 and tumor necrosis factor alpha by macrophages in vitro via Toll-like receptor 4 (TLR-4) signaling. In the present study, we examined the effect of oral administration of AC-1 on protective immunity against Listeria monocytogenes. Mice were given AC-1 or phosphate-buffered saline (PBS) intragastrically 2 days before, on the day of, and 2 days after an intraperitoneal inoculation of L. monocytogenes. The survival rate of AC-1-treated mice was significantly improved and bacterial growth in AC-1-treated mice was severely retarded compared to those of PBS-treated mice after infection with L. monocytogenes. IL-12 p40 levels in serum and magnitudes of CD4+ Th1 and CD8+ Tc1 responses against Listeria antigen were significantly higher in AC-1-treated mice than in PBS-treated mice. The effect of AC-1 on antilisterial activity was diminished in C3H/HeJ mice carrying mutated TLR-4. Thus, AC-1, a potent IL-12 inducer through TLR-4, enhanced protective immunity against L. monocytogenes via augmentation of Th1 responses. These results suggest that infectious processes driven by intracellular microorganisms could be prevented to develop by the (1,4)-beta-D-glucan.

Glucan-like synthetic oligosaccharides: iterative synthesis of linear oligo-beta-(1,3)-glucans and immunostimulatory effects

Small reducing and linear oligo-beta-(1,3)-glucans, which are able to act as phytoallexin elicitors or as immunostimulating agents in anticancer therapy, were synthesized according to an iterative strategy that involved a unique key monosaccharidic donor. To avoid anomeric mixtures, the reducing entity of the target oligomers was first locked with benzyl alcohol and further selective deprotection of the 3-OH with DDQ afforded the desired building block as an acceptor. The latter was then used in a second cycle of glycosylation/deprotection to afford the desired disaccharide, and successive reiterations of this process provided the desired oligomers. Unusual conformational behaviors were observed by standard NMR sequences and supported by NOESY studies. Finally, removal of protecting groups afforded free tri-, tetra-, and pentaglucosides in good overall yields. Two oligosaccharides representing linear laminaritetraose and laminaripentaose were compared to the recently described beta-(1,3)-glucan phycarine. Following an intraperitoneal injection, the influx of monocytes and granulocytes into the blood and macrophages into the peritoneal cavity was comparable to that caused by phycarine. Similarly, both oligosaccharides stimulated phagocytic activity of granulocytes and macrophages. Using ELISA, we also demonstrated a significant stimulation of secretion of IL-1beta. Together these results suggest that the synthetic oligosaccharides have similar stimulatory effects as natural beta-(1,3)-glucans.

Effects of marine beta-1,3 glucan on immune reactions

Glucans have a long history as nonspecific biological modulators. A novel glucan-Phycarine-was isolated from sporophytes of Laminaria digitata. Phycarine showed significant stimulation of phagocytic activity as well as potentiation of synthesis and release of IL-1, IL-6 and TNF-alpha. In addition, Phycarine increased NK cell-mediated killing of tumor cells both in vitro and in vivo while acting via complement receptor type 3 (CR3) receptors.

Protective Effects of a Protein-Bound Polysaccharide, PSK, Against Candida albicans Infection in Syngeneic Tumor-Bearing Mice via Th1 Cell Functions

We investigated the effects of a protein-bound polysaccharide, PSK, on the resistance of tumor-bearing mice against Candida albicans infection. In BALB/c mice that had received subcutaneous (sc) transplantation of fibrosarcoma Meth A, viable fungal counts were increased in the kidney and the mean survival period was shortened after challenge with C. albicans, compared with healthy mice. Oral administration of PSK to such mice resulted in a significant decrease of viable fungal counts and a prolongation of the mean survival period. The ratio of CD4-positive T cells in the spleen was decreased in noninfected tumor-bearing mice and the decrease was prevented by PSK, although in vitro anticandida activities of phagocytes were not significantly affected by tumor burden or PSK. Further, intracellular interferon (IFN)-gamma productivity was enhanced and the number of IFN-gamma-producing CD4-positive T cells was enhanced by PSK. PSK enhanced the gene expression of interleukin (IL)-12 and IFN-gamma in the spleen of tumor-bearing mice inoculated with C. albicans. Treatments with anti-IL-12 or anti-IFN-gamma antibody reduced the anti-infectious effects of PSK. These findings suggest that the protective effect of PSK on sublethal inoculation with C. albicans in tumor-bearing mice is possibly mediated by Th1 cell functions.

Protective effects of a protein-bound polysaccharide, PSK, on Candida albicans infection in mice via tumor necrosis factor-alpha induction

We investigated the protective mechanism of a protein-bound polysaccharide, PSK, against lethal infection with Candida albicans (C. albicans) in mice. (1) In BALB/c mice inoculated intravenously with C. albicans, the intraperitoneal (ip) administration of PSK increased survival rates and prolonged the survival period depending on the time of administration, the dosage, and the size of fungal inoculum; the maximal effect was obtained when PSK 250 mg/kg was ip administered to mice 24 h before inoculation of 1 x 10(6) C. albicans (30 days survivors showed 60% and the mean survival period of mice with fatal infection increased 209%). (2) The protective effect of PSK was significantly decreased in mice treated with cyclophosphamide or carrageenan, or in mice treated previously with anti-tumor necrosis factor-alpha (TNF-alpha) antibody. (3) The administration of PSK significantly enhanced the expression of TNF-alpha gene in spleen and increased leukocyte functions from 6 h to 1 day after inoculation. (4) When the PSK fraction subjected to hydrolysis with beta1-3 glucanase or hydrazine was used instead of PSK, the anti-fungal activities were significantly decreased. These findings suggested that the protective effect of PSK on lethal C. albicans infection in mice was mainly produced via TNF-alpha functions, and that beta 1-3 glucan and protein moiety in PSK molecule were involved in the expression of the activities.