Immunomodulatory potentials of the water-soluble yam (Dioscorea opposita Thunb) polysaccharides for the normal and cyclophosphamide-suppressed mice

Research progress on the structure, derivatives, pharmacological activity, and drug carrier capacity of Chinese yam polysaccharides: A review

Chinese yam is a traditional Chinese medicine that has a long history of medicinal and edible usage in China and is widely utilised in food, medicine, animal husbandry, and other industries. Chinese yam polysaccharides (CYPs) are among the main active components of Chinese yam. In recent decades, CYPs have received considerable attention because of their remarkable biological activities, such as immunomodulatory, antitumour, hypoglycaemic, hypolipidaemic, antioxidative, anti-inflammatory, and bacteriostatic effects. The structure and chemical alterations of polysaccharides are the main factors affecting their biological activities. CYPs are potential drug carriers owing to their excellent biodegradability and biocompatibility. There is a considerable amount of research on CYPs; however, a systematic summary is lacking. This review summarises the structural characteristics, derivative synthesis, biological activities, and their usage as drug carriers, providing a basis for future research, development, and application of CYPs.

The Immunomodulatory Effects of A2 β-Casein on Immunosuppressed Mice by Regulating Immune Responses and the Gut Microbiota

The aim of this study was to investigate the immunomodulatory effects of A2 β-casein (β-CN) in cyclophosphamide-induced immunosuppressed BALB/c mice. Experiments conducted in vitro revealed that A2 β-CN digestive products have potent immunostimulatory activities. Animal studies demonstrated that A2 β-CN improved the immunological organ index reduction trend caused by cyclophosphamide, reduced the pathological damage to the spleen tissue in immunosuppressed mice, increased the release of IL-17A, IgG, and IgA, and reduced the production of IL-4. By regulating the relative abundance of advantageous bacteria like Oscillospira, Lactobacillus, and Bifidobacteria and harmful bacteria like Coprococcus and Desulfovibrionaceae, A2 β-CN improved gut microbiota disorders in immunosuppressed mice. Moreover, A2 β-CN promoted the production of short-chain fatty acids and increased the diversity of the gut microbiota. Therefore, ingestion of A2 β-CN is beneficial to the host's immune system and gut health. These findings provide insights for the future application of A2 β-CN-related dairy products.

Arctoscopus japonicus Lipids Enhance Immunity of Mice with Cyclophosphamide-Induced Immunosuppression

A lipid extract was obtained from eggs of the sailfin sandfish, Arctoscopus japonicus. Immunostimulatory effects of A. japonicus lipids incorporated with PEG6000 (AJ-PEG) on immunosuppressed mice treated with cyclophosphamide (CY) were investigated. AJ-PEG was administered orally to mice at different concentrations of 25 to 100 mg/kg body weight (BW). CY was injected to mice intraperitoneally at 80 mg/kg BW. Administration of AJ-PEG significantly increased the spleen index of CY-treated mice. AJ-PEG also stimulated the proliferation of splenic lymphocytes and natural killer (NK) activity. Immune-associated cytokines such as IL-1β, IL-2, IL-4, IL-6, TNF-α, and IFN-γ as well as TLR4 were overexpressed in splenic lymphocytes. Furthermore, AJ-PEG significantly increased splenic CD4+ and CD8+ T lymphocytes. In peritoneal macrophages, AJ-PEG administration improved proliferation, nitric oxide (NO) production, and phagocytosis. It also upregulated iNOS, COX-2, IL-1β, IL-6, and TNF-α expression. Taken together, these results suggest that AJ-PEG can be used in animal models with immunosuppressive conditions as a potent immunomodulatory agent.

Cationic Nanoparticle-Stabilized Vaccine Delivery System for the H9N2 Vaccine to Promote Immune Response in Chickens

Chinese yam polysaccharides (CYPs) have received wide attention for their immunomodulatory activity. Our previous studies had discovered that the Chinese yam polysaccharide PLGA-stabilized Pickering emulsion (CYP-PPAS) can serve as an efficient adjuvant to trigger powerful humoral and cellular immunity. Recently, positively charged nano-adjuvants are easily taken up by antigen-presenting cells, potentially resulting in lysosomal escape, the promotion of antigen cross-presentation, and the induction of CD8 T-cell response. However, reports on the practical application of cationic Pickering emulsions as adjuvants are very limited. Considering the economic damage and public-health risks caused by the H9N2 influenza virus, it is urgent to develop an effective adjuvant for boosting humoral and cellular immunity against influenza virus infection. Here, we applied polyethyleneimine-modified Chinese yam polysaccharide PLGA nanoparticles as particle stabilizers and squalene as the oil core to fabricate a positively charged nanoparticle-stabilized Pickering emulsion adjuvant system (PEI-CYP-PPAS). The cationic Pickering emulsion of PEI-CYP-PPAS was utilized as an adjuvant for the H9N2 Avian influenza vaccine, and the adjuvant activity was compared with the Pickering emulsion of CYP-PPAS and the commercial adjuvant (aluminum adjuvant). The PEI-CYP-PPAS, with a size of about 1164.66 nm and a ζ potential of 33.23 mV, could increase the H9N2 antigen loading efficiency by 83.99%. After vaccination with Pickering emulsions based on H9N2 vaccines, PEI-CYP-PPAS generated higher HI titers and stronger IgG antibodies than CYP-PPAS and Alum and increased the immune organ index of the spleen and bursa of Fabricius without immune organ injury. Moreover, treatment with PEI-CYP-PPAS/H9N2 induced CD4⁺ and CD8⁺ T-cell activation, a high lymphocyte proliferation index, and increased cytokine expression of IL-4, IL-6, and IFN-γ. Thus, compared with the CYP-PPAS and aluminum adjuvant, the cationic nanoparticle-stabilized vaccine delivery system of PEI-CYP-PPAS was an effective adjuvant for H9N2 vaccination to elicit powerful humoral and cellular immune responses.

The Barrier-Enhancing Function of Soluble Yam (Dioscorea opposita Thunb.) Polysaccharides in Rat Intestinal Epithelial Cells, as Affected by the Covalent Se Conjugation

The non-starch yam polysaccharides (YP) are the bioactive substances of edible yam, while Se is an essential nutrient for the human body. Whether a covalent conjugation of Se to YP might cause bioactivity change for the resultant selenylated YP in the intestine is still insufficiently studied, including the critical intestinal barrier function. In this study, two selenylated YP products, namely, YPSe-I and YPSe-II, with corresponding Se contents of 795 and 1480 mg/kg, were obtained by the reaction of YP and Na2SeO3 in the presence of HNO3 and then assessed for their bioactivities to a cell model (i.e., rat intestinal epithelial IEC-6 cells). The results showed that YP, YPSe-I, and YPSe-II at 5–80 μg/mL dosages could promote cell growth with treatment times of 12–24 h. The three samples also could improve barrier integrity via increasing cell monolayer resistance and anti-bacterial activity against E. coli or by reducing paracellular permeability and bacterial translocation. Additionally, the three samples enhanced F-actin distribution and promoted the expression of the three tight junction proteins, namely, zonula occluden-1, occludin, and claudin-1. Meanwhile, the expression levels of ROCK and RhoA, two critical proteins in the ROCK/RhoA singling pathway, were down-regulated by these samples. Collectively, YPSe-I and, especially, YPSe-II were more potent than YP in enhancing the assessed bioactivities. It is thus concluded that this chemical selenylation of YP brought about enhanced activity in the cells to promote barrier integrity, while a higher selenylation extent of the selenylated YP induced much activity enhancement. Collectively, the results highlighted the important role of the non-metal nutrient Se in the modified polysaccharides.

Extraction, purification, structure, modification, and biological activity of traditional Chinese medicine polysaccharides: A review

Traditional Chinese medicines (TCM), as the unique natural resource, are rich in polysaccharides, polyphenols, proteins, amino acid, fats, vitamins, and other components. Hence, TCM have high medical and nutritional values. Polysaccharides are one of the most important active components in TCM. Growing reports have indicated that TCM polysaccharides (TCMPs) have various biological activities, such as antioxidant, anti-aging, immunomodulatory, hypoglycemic, hypolipidemic, anti-tumor, anti-inflammatory, and other activities. Hence, the research progresses and future prospects of TCMPs must be systematically reviewed to promote their better understanding. The aim of this review is to provide comprehensive and systematic recombinant information on the extraction, purification, structure, chemical modification, biological activities, and potential mechanism of TCMPs to support their therapeutic effects and health functions. The findings provide new valuable insights and theoretical basis for future research and development of TCMPs.

Effects of Chinese yam polysaccharides on the immune function and serum biochemical indexes of broilers

The purpose of this experiment was to investigate the effects of Chinese yam polysaccharides (CYP) in diets on the immune function of broilers. A total of 360 (1-day-old, sex balance) healthy growing broilers with similar body weight (39.54 ± 0.51 g) were randomly divided into control (0.00 g/kg), CYP I (0.25 g/kg), CYP II (0.50 g/kg), and CYP III (1.00 g/kg) groups. Each group contains 3 replicates with 30 broilers in each replicate, and the feeding trial lasted 48 d. The results showed that compared with the control group, the CYP II group had higher thymus index, serum IgA, complement C3, C4, IGF-I, T₃, T₄, INS, GH, IL-2, IL-4, IL-6, and TNF-α levels (P < 0.05) at 28, 48 d, respectively. In addition, the spleen index, serum IgM and IgG concentrations in CYP II group were higher than those in the control group at 28 d (P < 0.05). Results indicated that 0.50 g/kg CYP supplementation improved the immune function of broilers, and the CYP has a potential biological function as a green additive in broilers.

Monosaccharide composition and in vivo immuno-stimulatory potential of soluble yam (Dioscorea opposita Thunb.) polysaccharides in response to a covalent Se incorporation

The present study aimed to investigate whether selenylation modification could affect compositional features and in vivo immuno-stimulatory potential of yam polysaccharides. In this study, the soluble yam mucilage polysaccharides (YPS) were prepared and selenylated in the HNO₃-Na₂SeO₃ system, and two selenylated polysaccharide products, namely SeYPS-1 and SeYPS-2 with respective Se contents of 719 and 1585 mg/kg, were thus obtained. GC-MS analysis demonstrated that the compositional features of SeYPS-1 and SeYPS-2 were similar to those of YPS. Meanwhile, the immuno-stimulatory potential of the selenylated products, especially SeYPS-2, in the BALB/c mice model was higher than that of YPS, reflected by the elevated contents of serum immunoglobins and increased percentage of CD4⁺ splenic lymphocytes. It was thus confirmed that the selenylation did not change the composition of monosaccharides but endowed YPS with greater immuno-stimulation in the mice, while the higher extent of selenylation also caused a much enhanced immuno-stimulatory potential of SeYPS-2.

Immune-Enhancing Effects of Crude Polysaccharides from Korean Ginseng Berries on Spleens of Mice with Cyclophosphamide-Induced Immunosuppression

Panax ginseng C. A. Meyer is well known as traditional herbal medicine, and ginseng berries are known to exhibit potential immune-enhancing functions. However, little is known about the in vivo immunomodulatory activity of Korean ginseng berries. In this study, crude Korean ginseng berries polysaccharides (GBP) were isolated and their immunomodulatory activities were investigated using cyclophosphamide (CY)-induced immunosuppressive BALB/c mice. In CY-treated mice, oral administration of GBP (50-500 mg/kg BW) remarkably increased their spleen sizes and spleen indices and activated NK cell activities. GBP also resulted in the proliferation of splenic lymphocytes (coordinating with ConA: plant mitogen which is known to stimulate T-cell or LPS: endotoxin which binds receptor complex in B cells to promote the secretion of pro-inflammatory cytokines) in a dose-dependent manner. In addition, GBP significantly stimulated mRNA expression levels of immune-associated genes including interleukin-1β (IL-1β), IL-2, IL-4, IL-6, tumor necrosis factor-α (TNF-α), interferon-γ (IFN-γ), toll-like receptor 4 (TLR-4), and cyclooxygenase-2 (COX-2) in CY-treated mice. These results indicate that GBP is involved in immune effects against CY-induced immunosuppression. Thus, GBP could be developed as an immunomodulation agent for medicinal or functional food application.

In Vitro Immuno-Modulatory Potentials of Purslane (Portulaca oleracea L.) Polysaccharides with a Chemical Selenylation

The soluble polysaccharides from a non-conventional and edible plant purslane (Portulaca oleracea L.), namely PSPO, were prepared by the water extraction and ethanol precipitation methods in this study. The obtained PSPO were selenylated using the Na₂SeO₃-HNO₃ method to successfully prepare two selenylated products, namely SePSPO-1 and SePSPO-2, with different selenylation extents. The assay results confirmed that SePSPO-1 and SePSPO-2 had respective Se contents of 753.8 and 1325.1 mg/kg, while PSPO only contained Se element about 80.6 mg/kg. The results demonstrated that SePSPO-1 and SePSPO-2 had higher immune modulation than PSPO (p < 0.05), when using the two immune cells (murine splenocytes and RAW 264.7 macrophages) as two cell models. Specifically, SePSPO-1 and SePSPO-2 were more active than PSPO in the macrophages, resulting in higher cell proliferation, greater macrophage phagocytosis, and higher secretion of the immune-related three cytokines, including tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and IL-1β. Meanwhile, SePSPO-1 and SePSPO-2 were more potent than PSPO in the concanavalin A- or lipopolysaccharide-stimulated splenocytes in cell proliferation, or more able than PSPO in the splenocytes to promote interferon-γ secretion but suppress IL-4 secretion, or more capable of enhancing the ratio of T-helper (CD4⁺) cells to T-cytotoxic (CD8⁺) cells for the T lymphocytes than PSPO. Overall, the higher selenylation extent of the selenylated PSPO mostly caused higher immune modulation in the model cells, while a higher polysaccharide dose consistently led to the greater regulation effect. Thus, it is concluded that the employed chemical selenylation could be used in the chemical modification of purslane or other plant polysaccharides, when aiming to endow the polysaccharides with higher immuno-modulatory effect on the two immune cells.

In Vitro Immunomodulation of the Polysaccharides from Yam (Dioscorea opposita Thunb.) in Response to a Selenylation of Lower Extent

The immunomodulation of chemically selenylated polysaccharides has been attracting more attention recently, but the corresponding performance of the yam polysaccharides (YPS) with lower selenylation extent remains, thus far, unsolved. In this study, the YPS was selenylated with Na₂SeO₃ under acidic conditions generated by HNO₃ to reach two lower selenylation extents, yielding two selenylated YPSs, namely SeYPS-1 and SeYPS-2 with selenium contents of 715 and 1545 mg/kg, respectively. The results indicated that YPS, SeYPS-1, and SeYPS-2 all had in vitro immuno-modulation when using RAW 264.7 macrophages and murine splenocytes as cell models. In detail, the three polysaccharide samples at dose levels of 5–160 μg/mL showed insignificant cytotoxicity to the macrophages and splenocytes with cell exposure times of 12–24 h, because of the measured values of cell viability larger than 100%. However, Na₂SeO₃ at dose levels of 1.3–3.25 μg/mL mostly caused obvious cytotoxic effects on the cells, resulting in reduced cell viability values or cell death, efficiently. The results demonstrated that, compared with YPS, both SeYPS-1 and SeYPS-2 at a lower dose level (5 μg/mL) were more active at promoting phagocytosis activity, increasing the CD4⁺/CD8⁺ ratio of the T-lymphocyte sub-population in the murine splenocyte, improving cytokine secretion, including interleukin-6 (IL-6), IL-1β, and tumor necrosis factor-α in the macrophages, or increasing interferon-γ secretion, but suppressing IL-4 production in the splenocytes. Consistently, SeYPS-2 has more potential than SeYPS-1 at exerting these assessed bioactivities in the cells. Thus, we conclude that a chemical modification of YPS using trace element Se at a lower selenylation extent could bring about higher immunomodulatory activity towards macrophages and splenocytes, while selenylation extent of YPS is a critical factor used to govern the assessed activity changes of YPS.

Structure Characterization of Polysaccharide from Chinese Yam (Dioscorea opposite Thunb.) and Its Growth-Promoting Effects on Streptococcus thermophilus

To clarify the mechanisms underlying the growth-promoting effects of yam polysaccharide on Streptococcus thermophilus (S. thermophilus), the yam polysaccharide was extracted using a deep eutectic solvents (DESs) method and separated into four fractions by DEAE-cellulose 52. These fractions were used as the alternative carbon source to substitute lactose to compare their growth-promoting effects on S. thermophilus. Furthermore, their molecular weight, monosaccharide and functional groups' composition, microscopic forms and other basic structure characterizations were analyzed. The results showed that all the fractions could significantly promote S. thermophilus growth, and fractions exhibited significantly different growth-promoting effects, whose viable count increased by 6.14, 6.03, 11.48 and 11.29%, respectively, relative to those in the M17 broth medium. Structure-activity relationship analysis revealed that the high growth-promoting activity of yam polysaccharide might be more dependent on the higher molecular weight, the higher galacturonic acid content and its complex spatial configuration, and the existence of β-glycosides would make the yam polysaccharide have a better growth-promoting effect on S. thermophilus.

Effects of the polysaccharides extracted from Chinese yam (Dioscorea opposita Thunb.) on cancer-related fatigue in mice

The aim of this study was to investigate the anti-fatigue activity of Chinese Yam polysaccharides (CYPs). The structural characterization of CYPs was conducted using Fourier transform-infrared spectroscopy, nuclear magnetic resonance spectroscopy, gel permeation chromatography-light scattering-refractive index, and ion chromatography. The weight-loaded swimming capability, behavior performance, tumor growth, content of adenosine triphosphate (ATP), and biochemical markers of CYP in a cancer-related fatigue mouse model were tested. The results showed that CYP is a mixture with an average M_w of 75.57 kDa and is mainly composed of rhamnose, glucuronic acid, glucose, galactose, and arabinose with a molar ratio of 0.01 : 0.06 : 1.00 : 0.17 : 0.01. CYP increased the exhausting swimming time, which was decreased in the cisplatin (DDP) control group and the model group. CYP also increased the content of ATP in musculus gastrocnemius, which was down-regulated by DDP; the DDP had significantly enhanced the contents of interleukin-1β (IL-lβ), malondialdehyde (MDA), blood urea nitrogen (BUN) and lactic dehydrogenase (LDH) and inhibited the activity of superoxide dismutase (SOD) in the muscle. Administration of CYP decreased the levels of IL-lβ, MDA, BUN and LDH, and up-regulated the SOD activity. The DDP + CYP group presented a decreased tumor volume and a lower tumor weight as compared with the model group. Moreover, the mice in the CYP or DDP + CYP groups had heavier body weights than the mice in the model group and DDP group. These results suggest that CYP should improve cancer-related fatigue via the regulation of inflammatory responses, oxidative stress and increase in energy supplementation.

The impact of caseinate oligochitosan-glycation by transglutaminase on amino acid compositions and immune-promoting activity in BALB/c mice of the tryptic caseinate hydrolysate

Caseinate was glycated with oligochitosan via transglutaminase (TGase) action and then hydrolyzed by trypsin to generate glycated caseinate hydrolysate (GCNH) that was investigated for in vivo immune-promoting activity. Caseinate hydrolysate (CNH) containing glucosamine of 5.7 g/kg had amino acid compositions similar to GCNH. In normal BALB/c mice, GCNH at 100-400 mg/(kg d) showed higher immune-promoting activity than CNH via increasing serum IgM, IgA, and IgG by 1.5-24.5%, enhancing spleen and thymus indices by 9.7-26.2%, or increasing splenocyte lymphocyte proliferation and natural killer (NK) cell activity by 1.2-11.5%. GCNH also exerted higher activity than CNH in the suppressed BALB/c mice through increasing serum IgM, IgA, and IgG by 2.6-10.5%, enhancing spleen and thymus indices by 0.4-50.1%, or increasing splenocyte lymphocyte proliferation and NK cell activity by 3.4-18.9%. The results highlight that this TGase-type oligochitosan-glycation is potential to generate functional protein ingredients that possess improved immune-promoting activity once hydrolyzed by trypsin.

Recent progress in the research of yam mucilage polysaccharides: Isolation, structure and bioactivities

Yam (Dioscorea spp.), known as an edible and medicinal tuber crop in China, has been used historically for the treatment of diabetes, diarrhea, asthma, and other ailments in traditional Chinese medicine. Moreover, it has been consumed as starchy food for thousands of years in China. Modern phytochemistry and pharmacological experiments have been proved that non-starch polysaccharide is one of the main bioactive substances of yam. Many studies have been focused on the isolation and identification of polysaccharides and their bioactivities of Chinese yam. However, due to the difference in the variety of raw materials and the method of polysaccharides extracting, the structure and biological activity of the obtained polysaccharides also differ. It has been demonstrated that Chinese yam polysaccharide has various important biological activities, such as hypoglycemia, immunomodulatory, antioxidant, and antitumor activities. This paper is aimed at summarizing previous and current references of the isolation processes, structural features and bioactivities of yam polysaccharides. The review will serve as a useful reference material for further investigation and application of yam polysaccharides in functional foods and medicine fields.

Immunomodulatory Effect of Tremella Polysaccharides against Cyclophosphamide-Induced Immunosuppression in Mice

Polysaccharides are closely associated with immune regulation, but there are different polysaccharide effects from different sources. In this study, the aim was to investigate the effect of tremella polysaccharides (TP) in cyclophosphamide-induced immunodeficient mice. We observed the thymus and spleen index, liver and spleen pathological changes, and the levels of IL-2, IL-12, INF-γ, TGF-β and Ig G in serum, and we also noted the mRNA expression of IL-1β, IL-4, IL-12 and TGF-β in liver and spleen. Besides, we also measured the best effects of different doses of TP (Low-TP was 20 mg/kg·BW, Middle-TP was 40 mg/kg·BW, and High-TP was 80 mg/kg·BW) on cyclophosphamide-induced immunosuppressed mice. The results were remarkable, and suggested that TP had a significant effect for enhancing immunity in cyclophosphamide-induced immunosuppression, and the immune enhancement of High-TP had the best results in TP-treated mice. It could significantly increase the thymus and spleen index, alleviate pathological features of immunosuppression such as the arrangement of liver sinusoid and hepatic plates was disordered, massive inflammatory cells infiltrated and fatty degeneration of hepatocytes in liver, and red pulp and white pulp were intermixed, splenic corpuscles demolished and disappeared, splenic sinusoid extended, and lymphocytes of spleen were reduced in spleen. Besides, it could also up-regulate serum levels of IL-2, IL-12, INF-γ and Ig G, reduce the level of TGF-β in serum, markedly promote mRNA expression of IL-1β, IL-4 and IL-12 in liver and spleen, and suppress mRNA expression of TGF-β. Above all, TP showed preventive effect for cyclophosphamide-induced immunosuppressed mice.