Non-starch polysaccharide from Chinese yam activated RAW 264.7 macrophages through the Toll-like receptor 4 (TLR4)-NF-κB signaling pathway

Prospects of yam (Dioscorea) polysaccharides: Structural features, bioactivities and applications

Yam (Dioscorea) is a tuber crop cultivated for food security, revenue, and medicinal purposes. It has been used to treat diabetes, asthma, diarrhea, and other diseases. The main active ingredients in yam, polysaccharides, are regarded to be the important reason for its widespread applications. Now, a comprehensive review of research developments of yam polysaccharides (YPs) was presented to explore their prospects. We outlined the structural characteristics, biological activities, structure-activity relationships, and potential applications. Around 13 neutral components and 17 acidic components were separated. They exhibited various bioactivities, including immunomodulatory, hypoglycemic, hypolipidemic, antioxidant, gastrointestinal protective, anti-fatigue, and senile disease treatment activities, as well as prebiotic effect. Structure-activity relationships illustrated that unique structural properties, chemical modifications, and carried biopolymers could influence the bioactivities of YPs. The potential applications in medicine, food, and other fields have also been summarized.

A Frontier Review of Nutraceutical Chinese Yam

Yams are the edible subterranean rhizomes, or tubers, of plants from the genus Dioscorea. There are approximately 600 species of yam plants in the world, with more than 90 of these growing in East Asia. One particular species, Dioscorea opposita Thunb., is highly praised as "the Chinese yam". This distinction arises from millennia of storied history, both as a nutritional food source and as a principal ingredient in traditional Chinese medicine. Among the many cultivars of Dioscorea opposita Thunb., Huai Shanyao has been widely regarded as the best. This review surveyed the historical background, physiochemical composition, applications as food and medicine, and research prospects for the Chinese yam. Modern science is finally beginning to confirm the remarkable health benefits of this yam plant, long-known to the Chinese people. Chinese yam promises anti-diabetic, anti-oxidative, anti-inflammatory, immunomodulatory, anti-hyperlipidemic, anti-hypertensive, anti-cancer, and combination treatment applications, both as a functional food and as medicine.

Fermentation enrichment, structural characterization and immunostimulatory effects of β-glucan from Quinoa

We developed an efficient mixed-strain co-fermentation method to increase the yield of quinoa β-glucan (Q+). Using a 1:1 mass ratio of highly active dry yeast and Streptococcus thermophilus, solid-to-liquid ratio of 1:12 (g/mL), inoculum size of 3.8 % (mass fraction), fermentation at 32 °C for 27 h, we achieved the highest β-glucan yield of (11.13 ± 0.80)%, representing remarkable 100.18 % increase in yield compared to quinoa β-glucan(Q-) extracted using hot water. The structure of Q+ and Q- were confirmed through Fourier Transform Infrared (FTIR) and Nuclear Magnetic Resonance (NMR) spectroscopies. Q+ contained 41.66 % β-glucan, 3.93 % protein, 2.12 % uronic acid; Q- contained 37.21 % β-glucan, 11.49 % protein, and 1.73 % uronic acid. The average molecular weight of Q+(75.37 kDa) was lower than that of Q- (94.47 kDa). Both Q+ and Q- promote RAW264.7 cell proliferation without displaying toxicity. They stimulate RAW264.7 cells through the NF-κB and MAPK signaling pathways, primarily inducing NO and pro-inflammatory cytokines by upregulating CD40 expression. Notably, Q+ exhibited stronger immunostimulatory activity compared to Q-. In summary, the fermentation enrichment method yields higher content of quinoa β-glucan with increased purity and stronger immunostimulatory properties. Further study of its bioimmunological activity and structure-activity relationship may contribute to the development of new immunostimulants.

Structural characterization and immunomodulatory activity of a polysaccharide from Dioscotea opposita

The purified polysaccharides fraction, DOP-2, was prepared from Dioscorea opposita Thunb (D. opposita). This study combined in vitro and in vivo experiments to comprehensively investigate the index changes in RAW264.7 cells and immunocompromised mice under DOP-2 intervention, aiming to elucidate the potential mechanisms of immunomodulatory effects of DOP-2. DOP-2 (10 ∼ 500 μg/mL) significantly elevated the levels of NO, interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) factors secreted by RAW264.7 cells, and restored the body weight of immunosuppressed mice and improve the degree of injury to the immune organ index, resulting in significant immunomodulatory effects. Notably, DOP-2 promoted the production of short-chain fatty acids (SCFAs) in immunosuppressed mice and modulated the composition of their gut microflora. These findings highlight the potential benefits of DOP-2 therapy in improving immune function and gut health, and will provide a theoretical basis for the application of D. opposita polysaccharides as an immunomodulatory adjuvant.

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.

Chinese Yam and Its Active Components Regulate the Structure of Gut Microbiota and Indole-like Metabolites in Anaerobic Fermentation In Vitro

As a medicinal and edible plant, Chinese yam (CY) can promote the enrichment of intestinal probiotics. Mucilage polysaccharides, diosgenin and taxifolin are the dominant components of CY. The purpose of this study was to investigate whether the impact of Chinese yam on gut microbiome structure and metabolism is attributable to its components. In the in vitro gastrointestinal digestion and colon fermentation system, the changes in gut microbiota composition and function were determined by 16S rRNA sequencing, and the levels of bacterial metabolites including short-chain fatty acids (SCFAs) and indole-like metabolites were detected by gas chromatography and an enzyme-linked immunoassay. The results show that CY, mucilage polysaccharides, diosgenin and taxifolin could increase the microbial diversity index. Furthermore, probiotics including Lactobacillus and Bacteroides were significantly increased, while harmful bacteria such as Escherichia and Proteus declined. CY could increase the production of SCFAs including acetic acid and butyric acid. Of note, CY and diosgenin displayed similar impacts on enhancing the abundance of Clostridium and promoting the production of indole-3-lactic acid and lactic acid. These findings provide evidence supporting Chinese yam as a natural food to regulate intestinal health. Diosgenin as a component of CY contributes mostly to the impact on regulating intestinal flora.

The elastase and melanogenesis inhibitory and anti-inflammatory activities of phosvitin phosphopeptides produced using high-temperature and mild-pressure (HTMP) pretreatment and enzyme hydrolysis combinations

This study aimed to determine the skin protective effect of egg yolk phosvitin phosphopeptides (PPPs). Phosvitin was separated from the egg yolk, and PPPs were produced using high-temperature and mild-pressure (HTMP) pretreatment and enzyme-sterilization hydrolysis combinations. The elastase and melanogenesis inhibitory activities and anti-inflammatory effects of egg yolk PPPs were determined. All PPPs significantly inhibited elastase activity, but the PPPs prepared with HTMP pretreatment and trypsin-sterilization (HTMP-T-S) combination suppressed the tyrosinase activity the most. PPPs (3 mg/mL) inhibited the α-melanocyte-stimulating hormone-induced melanin production in B16F10 melanoma cells by 31.18 to 38.58%. In addition, PPPs effectively inhibited nitric oxide (NO) production in the LPS (lipopolysaccharide)-stimulated RAW 264.7 macrophages, and the PPPs from HTMP-T-S exhibited the highest inhibitory activity. The protein expressions of pro-inflammatory enzymes, inducible nitric oxide synthase, and cyclooxygenase-2 were down-regulated by the PPPs from the HTMP-T-S. Therefore, PPPs could be used as an anti-melanogenic, anti-elastase, and anti-inflammatory agent for humans and skin care products.

Protective effect of Paecilomyces cicadae TJJ11213 exopolysaccharide on intestinal mucosa and regulation of gut microbiota in immunosuppressed mice

The exopolysaccharide (EPS) form Paecilomyces cicadae TJJ1213 possessed immunomodulatory activity in vitro, but whether it could regulate the immune system and intestinal microbiota in vivo remained unknown. In this study, the cyclophosphamide (CTX)-induced immunosuppressive mouse model was established to explore the immunomodulatory activity of EPS. Results showed that EPS could increase the immune organ indices, promote the secretion of serum immunoglobulins and up-regulate the expression of cytokines. Additionally, EPS could repair CTX-induced intestinal injury by increasing the expression of tight junction proteins and promoting the production of short-chain fatty acids. Moreover, EPS could remarkably enhance immunity through TLR4/MyD88/NF-κB and mitogen-activated protein kinase (MAPK) signaling pathways. Furthermore, EPS regulated intestinal microbiota by increasing the abundance of beneficial bacteria (Muribaculaceae, Lachnospiraceae NK4A136, Bacteroides, Odoribacter) and reducing the level of harmful bacteria (Alistipes, Helicobacter). In conclusion, our study suggested that EPS had the abilities to enhance immunity, restore intestinal mucosal injury and modulate intestinal microbiota, and may serve as a potential prebiotic to maintain health in the future.

Structural characterization and immunomodulatory activity of an arabinogalactan from Jasminum sambac (L.) Aiton tea processing waste

An arabinogalactan named JSP-1a was isolated from Jasmine tea processing waste by DEAE Sepharose FF and Sephacryl S-200 HR chromatography. Polysaccharide JSP-1a, with an average molecular weight of 87.5 kDa, was composed of galactose (59.60 %), arabinose (33.89 %), mannose (4.81 %), and rhamnose (1.70 %). JSP-1a was found to be a type II arabinogalactan comprising the main backbone of 1, 6-linked Galp residues, and the side chain containing α-T-Araf, α-1,5-Araf, β-T-Galp, β-1,3-Galp, and β-1,4-Manp residues was attached to the O-3 position of β-1,3,6-Galp residues. Evidence from bioactivity assays indicated that JSP-1a possessed potent immunomodulatory effects on RAW264.7 macrophages: treatment with JSP-1a increased phagocytosis, activated NF-κB p65 translocation, and promoted the production of NO, reactive oxygen species (ROS), the tumor necrosis factor (TNF)-α, and interleukin (IL)-6. Furthermore, inhibition of Toll-like receptor 4 caused the suppression of NO release and cytokines secretion, which indicated that TLR-4/NF-κB pathway might play a significant role in JSP-1a-induced macrophages' immune response. The results of this study could provide a theoretical basis of JSP-1a as a safe immunostimulatory functional foods or a treatment for immunological diseases.

Study on the pharmacodynamic effect of Rhizoma Dioscoreae polysaccharides on cerebral ischemia-reperfusion injury in rats and the possible mechanism

ETHNOPHARMACOLOGICAL RELEVANCE

Rhizoma Dioscoreae (RD) is the rhizome of Dioscorea opposita Thunb., a traditional Chinese medicine, which can treat hypertension, diabetes, cerebral vasospasm headache and Alzheimer's disease. Meanwhile, RD is the main component of Liuwei Dihuang pill, a Chinese patent medicine. Rhizoma Dioscoreae polysaccharides (RDPS) are the primary active ingredient of RD. Modern medical research confirmed RDPS has multiple pharmacological effects, including neuroprotection, immunoregulation, antioxidant effect in many organs. The primary ischemia/hypoxia injury and secondary reperfusion injury are mainly caused by oxidative stress, which caused by hypoxia, such as free radical generation, energy metabolism disorder, intracellular calcium overload, excitatory amino acid release and inflammatory reaction.

AIM OF THE STUDY

We have investigated the pharmacodynamic effect of RDPS on cerebral ischemia-reperfusion (IR) injury in rats and the possible mechanism in vitro.

MATERIALS AND METHODS

The pharmacodynamic effect of RDPS on IR injury in rats was studied by the construction of the occlusion of middle cerebral artery (MCAO) model, measuring the volume of cerebral infarct area, the content of oxidation index, inflammatory cytokines, and the expression of CaMMKβ in brain tissue. The in vitro study was explored by oxygen-glucose deprivation/glycogen reoxygenation (OGD/R) model, construction of the CaMMKβ interference sequence, measuring the expression of CaMMKβ in BV2 cells before and after inhibition of CaMMKβ, and the influence of RDPS on Nrf2/HO-1 signal pathway, in order to investigate the possible mechanism.

RESULTS

Compared with the model group, the present study showed that RDPS with high-dose and low-dose groups could significantly reduce the volume of cerebral infarction. The content of MDA decreased and the activities of GSH and SOD increased in the two dose groups of RDPS. We confirmed that after RDPS treatment, the levels of IL-6, IL-1 β and TNF-α in brain tissue were lower than those in model group, and the expression of CaMMKβ in brain tissue of rats decreased in the model group, but increased in the groups of RDPS. In the in vitro study, compared with the control group, RDPS could regulate the OGD/R-induced apoptosis of BV2 cells and increase the level of CaMMKβ, Nrf2 and HO-1 induced by OGD/R. To our surprise, these therapeutic effects are no longer present after the inhibition of CaMMKβ protein. The activity of BV2 induced by OGD/R could not be enhanced by RDPS after the inhibition of CaMMKβ protein.

CONCLUSIONS

RDPS has the pharmacodynamic effect in IR injury, which reduce the area of cerebral infarction, up-regulate the activity of anti-oxidant kinase, and down-regulate the inflammatory cytokine. Additionally, RDPS could affect the activation of Nrf2/HO-1 signaling pathway by regulating the expression of CaMMKβ. Our observations justify the RDPS could be a new strategy for IR injury therapy, and the mechanism may be related to the improvement of antioxidant enzyme activity and inhibition of inflammatory reaction.

The inhibitory effect of Yam polysaccharides on acrylamide-induced programmed cell death in RAW 264.7 cells

Acrylamide has been well known for its neurotoxicity, genotoxicity, carcinogenicity, etc. Recently, the immunotoxicity of acrylamide has been reported by different research groups, although the underlying mechanisms of acrylamide endangering immune systems have not been fully elucidated. In this study, mouse monocyte-macrophage cells model was used to clarify the toxic mechanism of acrylamide and the inhibitory effect of Yam polysaccharides (YPS) on acrylamide-induced damage. We found that acrylamide induced RAW 264.7 cell death in a time- and concentration-dependent manner. After acrylamide (2.0, 3.0, 4.0 mmol/L) treatment for 24 h, cell apoptosis, autophagy, and pyroptosis were observed. However, the levels of autophagy and pyroptosis decreased at a high concentration of acrylamide (4.0 mmol/L). Acrylamide upregulated P2X7 expression, but the P2X7 level was not showing a monotone increasing trend. When the P2X7 antagonist was applied, the effect of acrylamide on autophagy and pyroptosis was weakened. Additionally, acrylamide triggered the occurrence of oxidative stress and a decreased nitric oxide (NO) level. However, reactive oxygen species (ROS) generation, the decrease of heme oxygenase-1 (HO-1) expression, and the increase of inducible nitric oxide synthase (iNOS) expression were reversed by the inhibition of P2X7. Yam polysaccharides (50.0 μg/ml) significantly inhibited acrylamide-induced oxidative stress and cell death (including apoptosis, autophagy, and pyroptosis). Yam polysaccharides also effectively reversed the increase of iNOS expression induced by acrylamide. However, Yam polysaccharides promoted the expression of P2X7 rather than prohibit it. These results indicated that acrylamide caused RAW 264.7 cell death due to pro-apoptosis as well as excessive autophagy and pyroptosis. Apoptosis might be more predominant than autophagy and pyroptosis under a higher concentration of acrylamide (4.0 mmol/L). P2X7-stimulated oxidative stress was responsible for acrylamide-induced programmed cell death (PCD), but P2X7 showed limited regulatory effect on apoptosis. Yam polysaccharides with antioxidant activity inhibited acrylamide-induced cell death (apoptosis, autophagy, and pyroptosis), but exerted limited effect on the acrylamide-induced P2X7 expression. These findings would offer an insight into elucidating the immunotoxic mechanism of acrylamide and the potential approaches to control its toxicity.

Isolation, Characterization and Antioxidant Activity of Yam Polysaccharides

This study aimed to characterize the structure of Chinese yam (Dioscoreae Rhizoma) polysaccharide (CYP) and to investigate its protective effect against H₂O₂-induced oxidative damage in IEC-6 cells. The chemical composition and structural characteristics of the samples were analyzed by chemical and instrumental methods, including high-performance gel permeation chromatography, high-performance anion-exchange chromatography (HPAEC), Fourier transformed infrared (FT-IR), ultraviolet (UV), and scanning electron microscopy (SEM). Antioxidant activity was evaluated by establishing a cellular model of oxidative damage. The molecular weight of CYP was 20.89 kDa. Analysis of the monosaccharide composition revealed that CYP was primarily comprised of galactose (Gal), glucose (Glu), and galacturonic acid (GalA), and the ratio between them was 28.57:11.28:37.59. Pretreatment with CYP was able to improve cell viability, superoxide dismutase (SOD) activity, and reduce intracellular reactive oxygen species (ROS) production and malondialdehyde (MDA) content after H₂O₂ injury. CYP also attenuated oxidative damage in cells through the mitogen-activated protein kinase (MAPK) signaling pathway. This study showed that CYP was an acidic heteropolysaccharide with a good protective effect against oxidative damage, and it thus has good prospects in food and biopharmaceutical industries.

Sulfated Chinese yam polysaccharide enhances the immunomodulatory activity of RAW 264.7 cells via the TLR4-MAPK/NF-κB signaling pathway

In this study, Chinese yam polysaccharide (CYP) was isolated from yam by hydroextraction and alcoholic precipitation. Subsequently, the chlorosulfate-pyridine (CSA-Pyr) method was used to obtain the sulfated Chinese yam polysaccharide derivative (S-CYP) to evaluate its immunomodulatory activity in RAW 264.7 cells and to investigate its mechanism of action. The results revealed that the sulfated modification altered the physicochemical properties of CYP but had no impact on the main chain structure. S-CYP demonstrated excellent immunomodulatory activity by increasing the viability of RAW 264.7 macrophage cells and stimulating the production of reactive oxygen species (ROS), nitric oxide (NO), tumor necrosis factor-α (TNF-α) and interleukin (IL)-6. Moreover, signal transduction experiments showed that S-CYP induced the activation of mitogen-activated protein kinase (MAPK) and nuclear factor-κB (NF-κB) pathways through toll-like receptor 4 (TLR4), dramatically increasing p-ERK, p-JNK and p-p38 proteins. Meanwhile, immunofluorescence results showed that S-CYP could significantly promote the entry of NF-κB p65 into the nucleus, which is essential for triggering the NF-κB pathway. Furthermore, blocking antibody experiments revealed that specific inhibitors of TLR4, MAPKs, and NF-κB suppressed the generation of TNF-α and IL-6 in RAW 264.7 cells. These findings suggested that both CYP and S-CYP could be used as immunomodulatory agents and may have potential application prospects in the food and pharmaceutical industries.

Structural Elucidation and Immunostimulatory Activities of Quinoa Non-starch Polysaccharide Before and After Deproteinization

Non-starch polysaccharides derived from natural resources play a significant role in the field of food science and human health due to their extensive distribution in nature and less toxicity. In this order, the immunostimulatory activity of a non-starch polysaccharide (CQNP) from Chenopodium quinoa was examined before and after deproteination in murine macrophage RAW 264.7 cells. The chemical composition of CQNP and deproteinated-CQNP (D-CQNP) were spectrometrically analysed that revealed the presence of carbohydrate (22.7 ± 0.8% and 39.5 ± 0.8%), protein (41.4 ± 0.5% and 20.8 ± 0.5%) and uronic acid (8.7 ± 0.3% and 6.7 ± 0.2%). The monosaccharide composition results exposed that CQNP possesses a high amount of arabinose (34.5 ± 0.3) followed by galactose (26.5 ± 0.2), glucose (21.9 ± 0.3), rhamnose (7.0 ± 0.1), mannose (6.0 ± 0.1) and xylose (4.2 ± 0.2). However, after deproteination, a difference was found in the order of the monosaccharide components, with galactose (41.1 ± 0.5) as a major unit followed by arabinose (34.7 ± 0.5), rhamnose (10.9 ± 0.2), glucose (6.6 ± 0.2), mannose (3.4 ± 0.2) and xylose (3.2 ± 0.2). Further, D-CQNP potentially stimulate the RAW 264.7 cells through the production of nitric oxide (NO), upregulating inducible nitric oxide synthase (iNOS) and various pro-inflammatory cytokines including interleukin (IL)-1β, IL-6, IL-10, and tumor necrosis factor-alpha (TNF-α). Moreover, stimulation of RAW 264.7 cells by D-CQNP takes place along the NF-κB and the MAPKs signaling pathways through the expression of cluster of differentiation 40 (CD40). This results demonstrate that RAW 264.7 cells are effectively stimulated after removal of the protein content in C. quinoa non-starch polysaccharides, which could be useful for develop a new immunostimulant agent.

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.

Peptides Released from Extruded Adzuki Bean Protein through Simulated Gastrointestinal Digestion Exhibit Anti-inflammatory Activity

Increasing attention has been focused on plant-derived peptides because of their potential bioactivities. In this study, bioactive peptides were released from extruded adzuki bean protein by simulated gastrointestinal digestion. A peptide (KQS-1) sequenced as KQSESHFVDAQPEQQQR was separated and identified using ultrafiltration, pre-high-performance liquid chromatography (HPLC), and ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). KQS-1 was shown to exert significant anti-inflammatory effects in lipopolysaccharide (LPS)-induced RAW 264.7 macrophages by reducing the production of IL-1, IL-6, TNF-α, and MCP-1 to 38.31, 6.07, 43.96, and 41.74%, respectively. The involved signaling pathways were identified by transcriptome analysis. Overall, 5236 differentially expressed genes (DEGs) were identified. Gene ontology (GO) functions demonstrated that DEGs were significantly related to the NF-κB pathway. In conclusion, KQS-1 prevented the activation and expression of NF-κB/caspase-1 by upstream and downstream factors. These findings highlight the bioactivity of adzuki bean peptides.

Structural characteristics of a mannoglucan isolated from Chinese yam and its treatment effects against gut microbiota dysbiosis and DSS-induced colitis in mice

A water-soluble polysaccharide named CYP-1 was isolated from Chinese yam. CYP-1 was characterized as a mannoglucan having a backbone consisting predominately of 1,4-α-linked Glcp branched at O-2, O-3, and O-6 position by t-α-linked Manp with a molecular weight of 2.86 kDa. CYP-1 could inhibit the overproduction of pro-inflammatory cytokines (such as TNF-α and IL-1β) in LPS-induced RAW 264.7 cells and DSS-induced colitis mice. Oral administration of CYP-1 dramatically alleviated colonic pathological damage, suppressed the activation of colonic inflammatory signaling pathways (such as NF-κB and NLRP3 inflammasome), recovered the mRNA expression of junctional proteins (such as ZO-1, claudin-1, occludin, and connexin-43), and modulated the gut microbiota by decreasing the abundances of Alistipes, Helicobacter, and an unidentified Enterobacteriaceae, in DSS-induced colitis mice. Overall, the present study elucidated that a new polysaccharide structure CYP-1 from Chinese yam and its therapeutic potential as a prebiotic for the prevention of inflammatory bowel disease.

The Immunoenhancement Effects of Polyethylenimine-Modified Chinese Yam Polysaccharide-Encapsulated PLGA Nanoparticles as an Adjuvant

Background

Poly(lactic-co-glycolic acid) (PLGA) has been extensively applied for sustained drug delivery and vaccine delivery system. However, vaccines delivered by PLGA nanoparticles alone could not effectively activate antigen-presenting cells (APCs) to induce strong immune responses.

Purpose

The aim of the present study was to design polyethylenimine (PEI)-modified Chinese yam polysaccharide (CYP)-encapsulated PLGA nanoparticles (CYPP-PEI) as a vaccine delivery system and evaluate the adjuvant activities in vitro and in vivo.

Materials and Methods

Cationic-modified nanoparticles exhibited high antigen absorption and could be efficiently taken by APCs to enhance the immune responses. Therefore, PEI-modified CYP-encapsulated PLGA nanoparticles (CYPP-PEI) were prepared. The storage stability and effective adsorption capacity for porcine circovirus-2 (PCV-2) antigen of these antigen-absorbed nanoparticles were measured for one month. Furthermore, the adjuvant activity of CYPP-PEI nanoparticles was evaluated on macrophages in vitro and through immune responses triggered by PCV-2 antigen in vivo.

Results

The PCV-2 absorbed CYPP-PEI nanoparticles showed excellent storage stability and high absorption efficiency of PCV-2 antigen. In vitro, CYPP-PEI nanoparticles promoted antigen uptake, enhanced surface molecular expressions of CD80 and CD86, and improved cytokine secretion of TNF-α, IFN-γ, and IL-12p70 in macrophages. After immunization with CYPP-PEI/PCV-2 formulation in mice, the expressions of surface activation markers on dendritic cells which located in draining lymph nodes were increased, such as MHCI, MHCII, and CD80. In addition, CYPP-PEI nanoparticles induced dramatically high PCV-2-specific IgG levels which could last for a long time and stimulated the secretion of subtype antibodies and cytokines. The results showed that CYPP-PEI could induce Th1/Th2 mixed but Th1-biased type immune responses.

Conclusion

Polyethylenimine-modified Chinese yam polysaccharide-encapsulated PLGA nanoparticle was a potential vaccine delivery system to trigger strong and persistent immune responses.

Poly(amino acids) as a potent self-adjuvanting delivery system for peptide-based nanovaccines

To be optimally effective, peptide-based vaccines need to be administered with adjuvants. Many currently available adjuvants are toxic, not biodegradable; they invariably invoke adverse reactions, including allergic responses and excessive inflammation. A nontoxic, biodegradable, biocompatible, self-adjuvanting vaccine delivery system is urgently needed. Herein, we report a potent vaccine delivery system fulfilling the above requirements. A peptide antigen was coupled with poly-hydrophobic amino acid sequences serving as self-adjuvanting moieties using solid-phase synthesis, to produce fully defined single molecular entities. Under aqueous conditions, these molecules self-assembled into distinct nanoparticles and chain-like aggregates. Following subcutaneous immunization in mice, these particles successfully induced opsonic epitope-specific antibodies without the need of external adjuvant. Mice immunized with entities bearing 15 leucine residues were able to clear bacterial load from target organs without triggering the release of soluble inflammatory mediators. Thus, we have developed a well-defined and effective self-adjuvanting delivery system for peptide antigens.

Chinese yam peel enhances the immunity of the common carp (Cyprinus carpio L.) by improving the gut defence barrier and modulating the intestinal microflora

The Chinese yam peel (CYP) is a by-product of yam processing that is rich in various nutrients and a good source for feed additives. This study investigated the effects of CYP on the intestinal microbiota and gut defence barrier of the common carp (Cyprinus carpio L.). Different groups of experimental fish were fed a normal control diet (NC), a low CYP diet (LYP) and a high CYP diet (HYP) for 8 weeks. After the feeding trial, the fish were assessed for intestinal enzyme activity, intestinal histology, immune-related gene expression, intestinal SCFAs and intestinal microbiota. Our results indicated that the intestinal integrity and antioxidant enzyme (CAT and SOD) activity in the common carp were enhanced following CYP supplementation. The mRNA levels of anti-inflammatory (TGF-β), tight binding protein (occludin and ZO-1) and pathway factor genes (TLR4 and NF-κB) were significantly upregulated in the HYP group (P＜0.05), which was accompanied by an increase in the level of pro-inflammatory IL-1β in the gut (P＜0.05). High-throughput sequencing revealed that Fusobacteria, Proteobacteria, and Bacteroidetes bacteria were most abundant in the microbial community in the gut of the common carp. The relative abundances of Bacteroides, Flavobacterium and Lactobacillus were increased, while the abundances of pathogenic microorganisms such as Enterobacteriaceae, Shewanella, Pseudomonas and Vibrio were reduced after treatment with CYP. Furthermore, the concentrations of acetic acid, propionic acid, butyric acid and total short-chain fatty acids (SCFAs) in the gut were also increased (P＜0.05). Finally, our results revealed correlations between gut microbiota, SCFAs, non-specific immunity and antioxidant enzymes in CYP-fed carp. These results suggest that CYP-supplemented feed could improve the immunity of the common carp by modulating the intestinal microflora and enhancing the gut defence barrier and has the potential to be used as an immunostimulating feed additive in aquaculture.

Polysaccharide from alfalfa activates RAW 264.7 macrophages through MAPK and NF-κB signaling pathways

Alfalfa polysaccharide (APS), a bioactive compound extracted from alfalfa, has been proposed to exhibit potential growth-promoting and immune-enhancing functions. But, little is known about the cellular immunomodulatory and intrinsic molecular mechanisms. Here we extracted the APS, and performed in vitro experiments to characterize the immunomodulatory functions as well as the molecular mechanisms of APS on RAW 264.7 macrophages cells. Chemical analyses showed that APS was mainly composed of fucose, arabinose, galactose, glucose, xylose, mannose, galacturonic acid and glucuronic acid. The results of in vitro assays demonstrated that 50 and 100 μg/mL APS increased the cell viability of RAW 264.7 cells. The secretion and gene expression of NO/iNOS, IL-6 and TNF-α in APS-induced macrophage cell were significantly enhanced. However, APS-induced TNF-α production was decreased by blocking the MAPK or NF-κB signaling pathways, especially for the blockade of p38. Moreover, APS enhanced the phosphorylation of p38, ERK, and JNK, promoted the degradation of IκBα, and increased the nuclear translocation of NF-κB p65 subunit. Therefore, we demonstrated that APS could improve the immune functions of RAW 264.7 macrophages cells by promoting the cell viability and increasing secretion and gene expressions of NO/iNOS, IL-6 and TNF-α through the MAPK and NF-κB signaling pathways.

In vitro antioxidant and immunostimulating activities of polysaccharides from Ginkgo biloba leaves

Ginkgo biloba leaves (GBLs) are used as herbal dietary supplements and medicine worldwide. In this study, crude GBL polysaccharides (GBPSs) were extracted and further purified on a DEAE (diethylaminoethanol) Sepharose Fast Flow column to obtain GBPS-2 and GBPS-3. The molecular weights of GBPS-2 and GBPS-3 were 672 and 723 kDa, respectively. GBPS-2 and GBPS-3 were typical acidic heteropolysaccharides, composed of mannose (Man), rhamnose (Rha), glucuronic acid (GlcA), galacturonic acid (GalA), glucose (Glc), galactose (Gal), and arabinose (Ara) (molar ratio: 0.08:0.12:0.16:0.06:0.11:1.00:0.32) and Man, Rha, GlcA, GalA, Gal, and Ara (molar ratio: 0.92:1.00:0.83:0.11:0.42:0.23), respectively. GBPS-2 and GBPS-3 exhibited limited scavenging abilities for the hydroxyl and 2,2‑diphenyl‑1‑picrylhydrazyl radicals as well as noticeable scavenging effects on superoxide radicals and 2,2'‑azino‑bis(3‑ethylbenzothiazoline‑6‑sulphonic acid) radicals. Furthermore, GBPS-2 and GBPS-3 significantly increased the phagocytosis of macrophages and promoted the production of NO, tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6. Thus, GBPS-2 and GBPS-3 exhibit potential application as functional food supplements.

Macrophage immunomodulatory activity of the polysaccharide isolated from Collybia radicata mushroom

Polysaccharides from Collybia radicata mushroom (CRP) possess many functions, such as antiviral, anti-aging and hypolipidemic activities. However, little is known about their immunomodulatory activity. To address this issue, we did a thorough research into their immune effects on murine macrophages. The results showed that the 14942Da polysaccharide not only obviously improved the proliferation and phagocytosis of macrophages, but also induced the secretion of nitric oxide (NO), inducible nitric oxide synthase (iNOS) and cytokines, such as tumor necrosis factor-α (TNF-α) and interleukin factors (IL-1β, IL-6 and IL-10). At a concentration of 850.0μgmL^-1, the polysaccharide stimulated their proliferation and phagocytosis to 2.1 and 3.4 times, respectively, as compared to the negative group. Meanwhile, it raised the production of NO by inducing iNOS in a concentration-dependent manner. Furthermore, it enhanced the release of these cytokines to multiples from 2.3 to 3.6 times. As an inhibitor of TLR4 (Toll-like Receptor 4), TAK242 suppressed the secretion of NO, iNOS and cytokines above 51%, and ORP acted on the cells mainly via TLR4. Consequently, the polysaccharide has a potent immunomodulatory activity by stimulating macrophages and can be considered as a novel potential immunopotentiator in medical and food industries.