Curative effects of combination therapy with lentinan and interleukin-2 against established murine tumors, and the role of CD8-positive T cells

Immunomodulatory Effect of Lentinan on Aberrant T Subsets and Cytokines Profile in Non-small Cell Lung Cancer Patients

As a purified active component from traditional Chinese medicine, lentinan administration can be applied as beneficial chemo-immunotherapy for anti-tumor. In this study, the immunomodulatory effects of lentinan on aberrant T subsets and cytokines profile were evaluated for non-small cell lung cancer (NSCLC). Of all NSCLC patients treated with NP chemotherapeutic protocol (combination of vinorelbin and cisplatin), 73 cases were recruited in this retrospective cohort trial study, of which 38 cases received additional lentinan. The changes of aberrant T subsets and cytokines profile were compared between two groups (chemotherapy in combination with lentinan vs. conserved single chemotherapy) by flow cytometry and molecular biology. Higher subset ratio of CD3⁺CD8⁺ cytotoxic T cells was confirmed in the peripheral blood of NSCLC patients. Chemo-immunotherapy of lentinan resulted in a significant increase of CD3 + CD56+ NKT cells (15.7 ± 3.1%), compared with 8.6 ± 1.4% of NKT cells in single chemotherapy group, and up-regulated CD3⁺CD8⁺ and CD3⁺CD4⁺ subsets as well, but caused the decrease of CD4⁺CD25⁺ Tregs induction, accompanied by significant alleviation of IL-10 and TGF-β1, and elevation of IFN-γ, TNF-α, and IL-12 (P < 0.05). It could be confirmed that lentinan could not only enhance the cellular immunity and promote the beneficial of anti-tumor by associated immunotherapy, but also had the ability to inhibit the expansion of immune suppressive Tregs in the NSCLC patients, in whom there was a raised Tregs induction compared to health control. Lentinan-based chemo-immunotherapy is a promising strategy for anti-tumor via enhancing the proliferation of cytotoxic T cells, followed by the elevation of inflammatory chemokines/cytokines. Meanwhile, the percentage of CD4+ CD25+ Tregs is down-regulated, leading to a shift in the inflammatory status from Th2 to Th1 in NSCLC patients treated with lentinan.

Lentinan ameliorates burn sepsis by attenuating CD4+ CD25+ Tregs

AIM

The aim of our study was to investigate the effect of lentinan on regulatory T cells (Tregs) in sepsis, especially on the generation of interleukin (IL)-10 via regulation of Erk-FoxO1 signaling.

METHODS

BalB/c mice were randomized into five groups: sham group, the group with burns plus Pseudomonas aeruginosa infection, and the groups with burns plus P. aeruginosa infection administered 40, 100, and 250mg/kg of lentinan. The mice were sacrificed on postburn days 0, 1, 2, 3, and 4, respectively, with eight animals per group at each time point. The peripheral blood CD4⁺ CD25⁺ Tregs and CD4⁺ T cells were isolated using magnetic microbeads. The phenotypes were analyzed by flow cytometry. The cytokine levels were determined with enzyme-linked immunosorbent assay (ELISA). Signal transduction was studied by Western blot, quantitative polymerase chain reaction (qPCR), and luciferase assay.

RESULTS

The IL-10-producing capacity of CD4⁺ CD25⁺ Tregs was significantly enhanced in the group with burns plus P. aeruginosa infection, compared with the sham group. Administration of lentinan significantly decreased IL-10 production and FoxP3 expression of CD4⁺ CD25⁺ Tregs. The proliferative activities of CD4⁺ T cells, however, were restored. Lentinan decreased lipopolysaccharide (LPS)-induced IL-10 production in the Tregs isolated from burned mice. In addition, lentinan attenuated LPS-stimulated Erk-FoxO1 activation.

CONCLUSIONS

Lentinan may improve the outcome of postburn sepsis by suppressing LPS-triggered Erk-FoxO1 activation. Consequently, the hyperfunction of CD4⁺ CD25⁺ Tregs is inhibited, leading to a shift in the inflammatory status from Th2 to Th1 in postburn sepsis.

Lentinan: hematopoietic, immunological, and efficacy studies in a syngeneic model of acute myeloid leukemia

Lentinan, a beta-glucan nutritional supplement isolated from the shitake mushroom (Lentula edodes), is a biological response modifier with immunostimulatory properties. Concomitantly, the role of beta-glucans as chemoimmunotherapeutic in a number of solid cancers has been widely documented. We investigated the effects of nutritional grade lentinan upon BN rats and in a preclinical syngeneic model of acute myeloid leukemia. BN rats supplemented daily with lentinan exhibited weight gains, increased white blood cells, monocytes, and circulating cytotoxic T-cells; and had a reduction in anti-inflammatory cytokines IL-4, IL-10, and additionally IL-6. Lentinan treatment of BN rats with BNML leukemia resulted in improved cage-side health and reduced cachexia in the terminal stage of this aggressive disease. Combination of lentinan with standards of care in acute myeloid leukemia, idarubicin, and cytarabine increased average survival compared with monotherapy and reduced cachexia. These results indicate that nutritional supplementation of cancer patients with lentinan should be further investigated.

Lentinan has a stimulatory effect on innate and adaptive immunity against murine Listeria monocytogenes infection

Lentinan, a (1-3)-beta glucan from Lentinus edodes, is licensed as an immunostimulatory drug. We tested the effect of lentinan in the well-established model system of the murine Listeria monocytogenes infection. Pre-treatment of bone marrow macrophages and dendritic cells with lentinan resulted in increased production of TNF-alpha and IL-12 after L. monocytogenes infection in vitro. After lentinan treatment bone marrow macrophages showed increased NO-production and enhanced cytotoxic activity against L. monocytogenes. Pre-treatment of mice with lentinan resulted in increased concentrations of TNF-alpha, IL-12 and IFN-gamma and also an increased number of L. monocytogenes specific CD8 T cells in the spleen. The bacterial burden in spleen and liver of mice was significantly reduced during primary and secondary Listeria infection after lentinan pre-treatment of mice. In summary these results show that lentinan enhances the protective CD8 T-cell response against L. monocytogenes probably by a mechanism that involves the IL-12-mediated augmentation of the specific antilisterial CD8 T-cell response.

Dendritic cells might be one of key factors for eliciting antitumor effect by chemoimmunotherapy in vivo

In this study, we demonstrated that chemoimmunotherapy using S-1, a novel oral fluoropyrimidine anticancer drug, combined with lentinan (LNT), a beta (1 --> 3) glucan, was effective in vivo, and we clarified the augmentation of the function of dendritic cells (DCs) in vivo and in vitro. The survival period of Colon-26-bearing mice treated with S-1 + LNT was significantly more prolonged than that of mice treated with S-1 alone (P < 0.05). On the other hand, LNT did not prolong the survival period when combined with S-1 in Colon-26-bearing athymic mice. The frequency of CD86+ DCs infiltrated into Colon-26 was increased in mice treated with S-1 + LNT, and splenic DCs harvested from mice treated with S-1 + LNT showed more potent T-cell proliferation activity than that of DCs from mice treated with S-1 alone (P < 0.05). Furthermore, the activity of cytotoxic T lymphocytes (CTLs) in splenocytes of S-1 + LNT-treated mice was specific and more potent than that of CTLs from mice treated with S-1 alone (P < 0.05). These results suggest that modulation of specific immunity with LNT has a significant role in enhanced antitumor effects through the modification of DC function. We demonstrated that DCs might play an important role in chemotherapy, and the combination therapy of S-1 and LNT presents a promising chemoimmunotherapy, which might lead to better survival for cancer patients.

The β-(1→6)-branched β-(1→3) glucohexaose and its analogues containing an α-(1→3)-linked bond have similar stimulatory effects on the mouse spleen as Lentinan

The stimulatory effects of the synthetic beta-(1-->6)-branched beta-(1-->3) glucohexaose and its analogues containing an alpha-(1-->3)-linked bond on the mouse spleen were studied for elucidation of the mechanism of their antitumor activity, and their stimulatory effects were compared with Lentinan. The mouse spleen's weight was increased after the intraperitoneal (i.p.) injection of the oligosaccharides compared with the saline group. In addition, routinely hematoxylin and eosin (HE)-stained spleen sections showed that the injection also changed the spleen's histopathology. RNA samples were isolated from splenocytes of oligosaccharides, Lentinan or saline-injected mice. Reverse transcription-polymerase chain reaction (RT-PCR) and Northern blot showed that the administration of the oligosaccharides or Lentinan enhanced mouse spleen mRNA production of TNF-alpha but not IL-2. The injection also enhanced Concanavalin A (Con A)-induced mouse splenocytes proliferation, but the in vitro administration of the oligosaccharides did not have the proliferation-enhancing effect. Taken together, these results suggest that the synthetic beta-(1-->6)-branched beta-(1-->3) glucohexaose and its analogues containing an alpha-(1-->3)-linked bond have similar stimulatory effects as Lentinan. Additionally, they may exert their antitumor effects through the induction of splenocytes mediated immune responses.

Activation of selective transcription factors and cytokines by water-soluble extract from Lentinus lepideus

We isolated a water-soluble extract, PG101, from cultured mycelia of Lentinus lepideus. Treatment of human peripheral blood mononuclear cells (PBMCs) with PG101 increased levels of TNF-alpha, IL-1beta, IL-10, and IL-12 by 100- to 1000-fold, whereas GM-CSF and IL-18 were activated by an order of magnitude. On the contrary, IFN-gamma and IL-4 were not affected. The response to PG101 occurred in a dose- and time-dependent manner. From the human PBMCs treated with PG101, TNF-alpha was a first cytokine to be activated, detectable at 2 hr post-treatment followed by IL-1beta at 6 hr post-treatment. IL-12 and IL-10 were the next to follow. GM-CSF and IL-18 both showed significant increases 24 hr after treatment. When PBMCs were sorted into various cell types, monocyte/macrophages, but not T and B cells, were the major target cell type responsive to PG101. Consistent with this result, the profile of cytokine expression upon PG101 treatment was comparable between PBMCs and a human promonocytic cell line (U937), whereas cell lines of T cell and myeloid origins did not respond to PG101. Data from a transient transfection assay involving specific reporter plasmids indicated that cellular transcription factor such as NF-kappaB, but not AP-1, was highly activated by PG101. Results from a gel retardation assay and the experiment involving a specific NF-kappaB inhibitor confirmed the involvement of NF-kappaB. Despite its significant biological effect on various cytokines, PG101 remained nontoxic in both rats and PBMCs even at a biological concentration approximately 20 times greater. PG101 demonstrates great potential as a therapeutic immune modulator.

A novel hepatic-targeting system for therapeutic cytokines that delivers to the hepatic asialoglycoprotein receptor, but avoids receptor-mediated endocytosis

PURPOSE

To demonstrate the utilities of a synthetic low-affinity ligand ((Gal)3) for the asialoglycoprotein receptor (ASGP-R) as a hepatic targeting device for therapeutic cytokines.

METHODS

The site-specific incorporation of (Gal)3 or a typical high-affinity ligand (GaINAc)3 into IL-2 was catalyzed by microbial transglutaminase. The anti-tumor activities, pharmacokinetic profiles and receptor-mediated endocytosis in hepatocytes of the ligand-IL-2 conjugates were examined in mouse.

RESULTS

The (Gal)3 has approximately 50 times lower affinity to ASGP-R than (GalNAc)3. Nevertheless, the antitumor effects were in the order of (Gal)3-IL-2 > unmodified IL-2 > (GalNAc)3-IL-2. The systemic elimination and the hepatic uptake of (GalNAc)374L-2 were more rapid than (Gal)3-IL-2. The ratio of the rate constant representing dissociation from the cell-surface receptor (k(off) to that representing endocytosis of the ligand (k(int) was greater for (Gal)3-IL-2 than (GalNAc)s-IL-2, suggesting that (Gal)3-IL-2 preferably avoids internalization due to its lower affinity to the receptor. The simulation studies demonstrated that (Gal)3-L-2 was present in the hepatic extracellular space for a longer period than (GaINAc)3 IL-2.

CONCLUSIONS

The (Gal)3 ligand increases the therapeutic efficacy of IL-2 by enhancing its exposure to the cell-surface. The k(off)/k(int) affects the targeting efficacy of the conjugates to ASGP-R.

Polysaccharide isolated from the radix of Platycodon grandiflorum selectively activates B cells and macrophages but not T cells

Many polysaccharides isolated from plants are considered to be biological response modifiers and have been shown to enhance various immune responses in vivo and in vitro. Here, we demonstrate that polysaccharide isolated from the radix of Platycodon grandiflorum (PG) has a unique mode of immunostimulation with regard to its cell-type specificity. PG was found to markedly increase polyclonal IgM antibody production and the proliferation of B cells, and to activate iNOS transcription and NO production in macrophages. Moreover, the intraperitoneal administration of PG in mice resulted in increased IgM antibody production in B cells, which were immunized by using T-dependent antigen sheep red blood cells (sRBCs). However, PG did not affect the proliferation of T cells, the IL-2 expression of Th1 cells, or the IL-4 expression of Th2 cells. Although PG and lipopolysaccharide (LPS) had a similar mode of action in B cells and macrophages, they were differentiated by the fact that PG-induced cellular activation was not inhibited by polymyxin B, a specific inhibitor of LPS. Anti-CD19 or anti-CD79b antibody blocked B cell proliferation and anti-CD14 or anti-CD 11b antibody decreased macrophage NO production, indicating the possible cellular binding sites of PG. Our results demonstrate that PG is a specific activator of B cells and macrophages but not of T cells, and suggest that PG is quite distinct from other well-known immunostimulants, such as lentinan and schizophyllan, which mainly act upon macrophages and T cells.

Dietary conjugated linoleic acid modulates phenotype and effector functions of porcine CD8(+) lymphocytes

In vivo vaccination and challenge studies have demonstrated that CD8(+) lymphocytes are essential for the development of cell-mediated protection against intracellular pathogens and neoplastic cells. Depletion of peripheral blood CD8(+) cells interferes with clearance of viruses and intracellular fungi, induction of delayed type hypersensitivity responses and antitumoral activity. In contrast to humans or mice, porcine peripheral CD8(+) lymphocytes are characterized by a heterogeneous expression pattern (i.e., CD8alphabeta and CD8alphaalpha) that facilitates the study of distinctive traits among minor CD8(+) cell subsets. A factorial (2 x 2) arrangement within a split-plot design, with 16 blocks of two littermate pigs as the experimental units for immunization treatment (i.e., unvaccinated or vaccinated with a proteinase-digested Brachyspira hyodysenteriae bacterin) and pig within block as the experimental unit for dietary treatment (soybean oil or conjugated linoleic acid) were used to investigate the phenotypic and functional regulation of CD8(+) cells by dietary conjugated linoleic acid (CLA). Dietary CLA supplementation induced in vivo expansion of porcine CD8(+) cells involving T-cell receptor (TCR)gammadeltaCD8alphaalpha T lymphocytes, CD3(-)CD16(+)CD8alphaalpha (a porcine natural killer cell subset), TCRalphabetaCD8alphabeta T lymphocytes and enhanced specific CD8(+)-mediated effector functions (e.g., granzyme activity). Expansion of peripheral blood TCRalphabetaCD8alphabeta cells was positively correlated (r = 0.89, P < 0.01) with increased percentages of CD8alphabeta(+) thymocytes. Functionally, CLA enhanced the cytotoxic potential of peripheral blood lymphocytes and proliferation of TCRgammadeltaCD8alphaalpha cells. Collectively, these results indicate that dietary CLA enhances cellular immunity by modulating phenotype and effector functions of CD8(+) cells involved in both adaptive and innate immunity.

β-Glucan, a “Specific” Biologic Response Modifier That Uses Antibodies to Target Tumors for Cytotoxic Recognition by Leukocyte Complement Receptor Type 3 (CD11b/CD18)

β-Glucans were identified 36 years ago as a biologic response modifier that stimulated tumor rejection. In vitro studies have shown that β-glucans bind to a lectin domain within complement receptor type 3 (CR3; known also as Mac-1, CD11b/CD18, or αMβ2-integrin, that functions as an adhesion molecule and a receptor for factor I-cleaved C3b, i.e., iC3b) resulting in the priming of this iC3b receptor for cytotoxicity of iC3b-opsonized target cells. This investigation explored mechanisms of tumor therapy with soluble β-glucan in mice. Normal mouse sera were shown to contain low levels of Abs reactive with syngeneic or allogeneic tumor lines that activated complement, depositing C3 onto tumors. Implanted tumors became coated with IgM, IgG, and C3, and the absent C3 deposition on tumors in SCID mice was reconstituted with IgM or IgG isolated from normal sera. Therapy of mice with glucan- or mannan-rich soluble polysaccharides exhibiting high affinity for CR3 caused a 57–90% reduction in tumor weight. In young mice with lower levels of tumor-reactive Abs, the effectiveness of β-glucan was enhanced by administration of a tumor-specific mAb, and in SCID mice, an absent response to β-glucan was reconstituted with normal IgM or IgG. The requirement for C3 on tumors and CR3 on leukocytes was highlighted by therapy failures in C3- or CR3-deficient mice. Thus, the tumoricidal function of CR3-binding polysaccharides such as β-glucan in vivo is defined by natural and elicited Abs that direct iC3b deposition onto neoplastic cells, making them targets for circulating leukocytes bearing polysaccharide-primed CR3. Therapy fails when tumors lack iC3b, but can be restored by tumor-specific Abs that deposit iC3b onto the tumors.

Synergistic antimetastatic effects of lentinan and interleukin 2 with pre- and post-operative treatments

The antimetastatic activity of a combination of lentinan and interleukin 2 (IL-2) was evaluated against spontaneously metastatic 3-methylcholanthrene-induced DBA/2.MC.CS.T fibrosarcoma. Although pre-operative treatment with either IL-2 or lentinan alone exerted little effect on the reduction of lung metastasis colony numbers (7.1% or 28.4% reduction, respectively), the combination exhibited a synergistic effect (85% reduction). Furthermore, 3 of 13 mice given the pre-operative combination treatment achieved complete cure, while no mice given saline did. Although the post-operative combination treatment also reduced the colony number (71% reduction), it caused little prolongation of survival and no mouse achieved complete cure. Synergistic effects were observed between pre- and post-operative treatments with lentinan and IL-2: 8 of 12 mice were completely cured. The anti-metastatic activity was abolished in mice treated simultaneously with antibodies to CD4 and CD8 antigens, whereas either CD4, CD8, or NK1.1 antibody alone was ineffective. Analysis of the cellular mechanism involved in the antimetastatic activity revealed the involvement of a tumor-associated antigen-specific delayed-type hypersensitivity response. These data suggest that the life-prolonging effect of the combination of lentinan and IL-2 is mediated by antigen-specific T cells and that the combination of pre- and post-operative therapy with lentinan and IL-2 may be effective to prevent cancer recurrence and metastasis after surgical resection.

Antitumor and immunological activity of lentinan in comparison with LPS

Lentinan manifests marked antitumor and antimetastatic activity in numerous tumor/host systems, and prevents chemical and viral carcinogenesis. Modulation of immune or vascular functions by lentinan is involved in its antitumor effects. The impact of lentinan on the functions of macrophages is distinct from that of LPS. One of the effects of lentinan on the vascular system is the vascular dilatation and hemorrhage (VDH) reaction, and the effect can be monitored as augmented skin reactions to vasoactive mediators. Lentinan induces the VDH-like reaction at the tumor site, resulting in the induction of hemorrhagic necrosis and complete regression of the tumor. In contrast to LPS-induced tumor necrosis (Shwartzman's-like reaction), lentinan-induced tumor necrosis is T-cell dependent.