Effects of intraperitoneal and intranasal application of Lentinan on cellular response in rats

Nutritive profile, pharmaceutical potentials, and structural analysis of multifunctional bioactive fungal polysaccharides-A review

Asian nations have long used edible fungi as food and medicine. Polysaccharides are among the main building units of the cell walls of fungi. Fungal polysaccharides have been documented in the medicinal and industrial sectors as products with a vast array of various biological activities and applications such as antitumor, antioxidant, anticancer, immunomodulation, and antiviral activities, etc. The goal of this review is to give insights into the various biological activities of mushroom polysaccharides and their potential as a medicine for human health. The extraction, purity, and structural analysis of fungal polysaccharides were also reviewed in this work. Also, future prospective, and challenges for fungal polysaccharides in pharmaceutical applications can be found in this review. Overall, this review serves as a valuable resource in exploring the therapeutic potential and applications of fungal polysaccharides. By building upon the existing knowledge base and addressing critical research gaps, researchers can find new opportunities for utilizing fungal polysaccharides as valuable therapeutic agents and functional ingredients in pharmaceuticals, nutraceuticals, and biotechnology.

Fungal polysaccharides from Inonotus obliquus are agonists for Toll-like receptors and induce macrophage anti-cancer activity

Fungal polysaccharides can exert immunomodulating activity by triggering pattern recognition receptors (PRRs) on innate immune cells such as macrophages. Here, we evaluate six polysaccharides isolated from the medicinal fungus Inonotus obliquus for their ability to activate mouse and human macrophages. We identify two water-soluble polysaccharides, AcF1 and AcF3, being able to trigger several critical antitumor functions of macrophages. AcF1 and AcF3 activate macrophages to secrete nitric oxide and the pro-inflammatory cytokines tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6). Combined with interferon-γ, the fungal polysaccharides trigger high production of IL-12p70, a central cytokine for antitumor immunity, and induce macrophage-mediated inhibition of cancer cell growth in vitro and in vivo. AcF1 and AcF3 are strong agonists of the PRRs Toll-like receptor 2 (TLR2) and TLR4, and weak agonists of Dectin-1. In comparison, two prototypical particulate β-glucans, one isolated from I. obliquus and one from Saccharomyces cerevisiae (zymosan), are agonists for Dectin-1 but not TLR2 or TLR4, and are unable to trigger anti-cancer functions of macrophages. We conclude that the water-soluble polysaccharides AcF1 and AcF3 from I. obliquus have a strong potential for cancer immunotherapy by triggering multiple PRRs and by inducing potent anti-cancer activity of macrophages.

Metabolism and Biodegradation of β-Glucan in vivo

The β-Glucans widely exist in plants and edible fungi, and their diverse bioactivities and good physicochemical properties have been widely reported. In addition, β-glucan intravenous injections (such as lentinan and schizophyllan) have been clinically used as immunomodulators and antitumor polysaccharides. However, the pharmacokinetic studies of β-glucans only stay on the level of plasma concentration and biodistribution in vivo, and little is known about their metabolism and degradation in vivo, which severely limits the further application of β-glucans in the field of medicine and biomaterials. The aim of this paper is to explore the metabolism and degradation process of lentinan (as a representative of β-glucans) in vivo by labeling it with water-soluble fluorescein 5-([4, 6-Dichlorotriazin-2-yl]amino)fluorescein (DTAF). Fluorescently labeled lentinan (FLNT) was intravenously administered to rats at a single dose of 8 mg/kg. The degradation of LNT in blood, liver, kidney, and urine was evaluated by the gel permeation chromatography. Our results showed that although LNT could be degraded in blood, liver, kidney, and urine, there were still some prototypes until excreted in urine due to the incomplete degradation of LNT in each step. To the best of our knowledge, this is the first report to comprehensively study LNT metabolic degradation in rats. These results provide an important reference for further exploration and application of LNT and other β-glucans.

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.

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.

Inhibitory effects of sulfated lentinan with different degree of sulfation against tobacco mosaic virus (TMV) in tobacco seedlings

The inhibitory effects of sulfated lentinan with different degrees of sulfation against tobacco mosaic virus (TMV) and the underlying mechanism were investigated. The results indicated that plants treated with increasing concentrations of sulfated lentinan, with increasing numbers of treatments and with increasing time after treatment had a decrease in the number of necrotic lesions, indicating a long-term protection against TMV that mimics vaccination. In addition, the levels of TMV-capsid protein (CP) transcripts decreased in distant leaves, indicating that sulfated lentinan induces systemic protection against TMV. The activities of the defense enzymes phenylalanine ammonia lyase (PAL) and lipoxygenase (LOX) and the amounts of several phenylpropanoid compounds (PPCs) were measured in control and treated plants without infection. A progressive increase in PAL activity was observed with increasing time after treatment, together with the accumulation of free and conjugated PPCs. In contrast, LOX activity remained unchanged. Interestingly, the increase in PAL activity showed a linear correlation with the decrease in necrotic lesions and the decrease in TMV-CP transcript level. Thus, sulfated lentinan induced systemic and long-term protection against TMV in tobacco plants that is determined, at least in part, by a sustained activation of PAL and the accumulation of PPCs with potential antiviral activity.

Inhibitory effect of sulfated lentinan and lentinan against tobacco mosaic virus (TMV) in tobacco seedlings

The antiviral activities of sulfated lentinan (sLNT) and lentinan (LNT) against tobacco mosaic virus (TMV) in tobacco seedlings and the underlying mechanism were investigated. Compared with LNT, sLNT showed significantly higher inhibitory effects on viral infection and TMV multiplication in a dose-dependent way, which might be due to its binding with TMV coat protein. In addition, both sLNT and LNT induced the transient production of H2O2 and expression of some defense-related genes (stilbene synthase, glucanase, acidic chitinase class IV, phenylalanine ammonia-lyase and 5-epi-aristolochene synthase) both locally and systemically. These results suggested that sLNT and LNT could control TMV incidence and the action mechanism might be associated with the affinity towards TMV coat protein and activation of some defense genes.

Combined immunomodulating effects of BCG and Lentinan after intranasal application in guinea pigs

The ability of a Shiitake (Lentinus edodes) medical mushroom-derived bioactive polymer Lentinan (Ajinomoto, Japan) to modulate the immune response makes it a potential candidate for combination therapy with BCG, or as adjunct for BCG vaccination, especially in high-risk individuals. We studied the combined immune-potential effectiveness of intranasal application of Lentinan (at a dose of 1 mg/kg, three times at 2-day intervals), followed by administration of BCG (strain Sofia SL-222 at a dose of 1 x 10(8) CFU, once) in guinea pigs. Samples of broncho-alveolar lavage fluid, as well as tissue fragments of lungs, spleens and lymph nodes were obtained from four groups (combined treatment with Lentinan and BCG; only with Lentinan; only with BCG; control with saline) of animals at different intervals--1, 14 and 45 days after last treatment and were evaluated by several parameters (establishing the number, H2O2 and nitrite production, and killing ability against Mycobacterium tuberculosis and Staphylococcus aureus of alveolar macrophages; spleen index, BCG CFU in spleens and histomorphological observations). Our attention was focused both on local effects in lungs, and systematical effects in reticuloendothelial system. The results indicate that intranasal application of BCG alone, or in combination with Lentinan induced high level of alveolar macrophage activation. Pre-treatment with Lentinan enhanced the local immunohistological response to BCG in lung and reduced the generalized side effects.

Induction of secretory and tumoricidal activities in peritoneal macrophages activated by an acidic heteropolysaccharide (ARAGAL) from the gum of Anadenanthera colubrina (Angico branco)

The immunomodulatory and anti-tumoral effects of an acidic heteropolysaccharide containing mainly galactose and arabinose (ARAGAL), isolated from the gum of the leguminous tree Anadenanthera colubrina (Angico branco) native to Brazil, were studied. It has been demonstrated that activation of mice peritoneal macrophages both in vivo and in vitro, increases phagocytic ability and anion superoxide production. In order to obtain further insights on the biological effects of ARAGAL, the capacity of eliciting peritoneal macrophages and tumor necrosis factor-alpha (TNF-alpha) production, and anti-tumoral effect against Sarcoma 180 (S-180), are now evaluated. Cell eliciting activity was observed in ARAGAL-treated animals in a dose dependent manner. Treatment of animals with 50, 100 or 200 mg/kg of ARAGAL increased peritoneal exudate cell (PEC) numbers by approximately 18, approximately 44 and approximately 88%, respectively. ARAGAL also increased 26-fold TNF-alpha production by peritoneal macrophages. Macrophages, treated in vitro for 18 h with ARAGAL, were able to kill Sarcoma 180 cells, as observed by their structures inside the macrophage cytoplasm. ARAGAL (100 mg/kg) showed anti-tumoral activity against S-180 in ascites or solid tumors, the tumoral inhibition being 63 and 38%, respectively. The results suggest a possible role as a BRM for ARAGAL.

Effect of an acidic heteropolysaccharide (ARAGAL) from the gum of Anadenanthera colubrina (Angico branco) on peritoneal macrophage functions

Brazilian flora are a source of interesting polysaccharides which, either in their native state or when submitted to structural modifications, might have potential applications as biological response modifiers (BRM). A complex acidic heteropolysaccharide, containing mainly galactose and arabinose (ARAGAL), isolated from the gum of the native leguminous tree Anadenanthera colubrina (Angico branco), was studied for its immunological properties on peritoneal exudate cells, namely their superoxide anion production, phagocytic activity, morphological alterations and percentage content of activated macrophages. Activation of macrophages showing increased cytoplasm, bright and large nuclei, various cytoplasmatic projections and spreading ability, was detected following in vitro cell exposure to ARAGAL or in cells obtained from treated animals. In vitro exposure to ARAGAL increased the occurrence of activated macrophages in a time- and a dose-dependent pattern, since approximately 82% of the cells were activated in the presence of 300 microg/ml of ARAGAL after 24 h of incubation and approximately 91% after 48 h. The occurrence of activated macrophages was also evident in cell preparations from ARAGAL-treated mice, their percentage showing a dose-dependent pattern. There were approximately 60, 75 and 75% following treatment with 100, 250 and 500 mg/kg of ARAGAL, respectively. A phagocytic assay showed that 25 microg/ml ARAGAL was sufficient to impose a maximum phagocytic ability, although this effect was dose-dependent. O(2)(-) production by macrophages from ARAGAL-treated mice was 70% higher than that of cells from untreated mice. Moreover, cells from treated mice responded to PMA, the effect being 25% higher than that of the control using untreated mice. These results thus suggest a possible role of ARAGAL from A. colubrina as a BRM.