Polysaccharide isolated from Sarcodon aspratus induces RAW264.7 activity via TLR4-mediated NF-κB and MAPK signaling pathways

Sulfate glycosaminoglycan from swim bladder exerts immunomodulatory potential on macrophages via toll-like receptor 4 mediated NF-κB signaling pathways

This study explored the immunomodulatory impact and potential mechanisms on macrophages RAW264.7 using a purified macromolecular sulfate glycosaminoglycan (SBSG) from the swim bladder, whose structure was similar to chondroitin sulfate A. The results showed that SBSG at 0.25-1 mg/mL increased the viability and phagocytosis of RAW264.7 cells. Meanwhile, SBSG promoted the secretion of tumor necrosis factor α (TNF-α), interleukin 10 (IL-10), and nitric oxide (NO), as well as the production of reactive oxygen species (ROS). According to the RT-PCR and Western blot data, SBSG activated TLR4-nuclear factor kappa B (NF-κB) signaling pathways, which decreased the relative mRNA and protein levels of Toll-like receptor 4 (TLR4), IκB kinase β (IKKβ), NF-κB p65, and p-NF-κB p65. The molecular docking and molecular dynamic simulation findings revealed that the main binding force between TLR4 and SBSG was conventional hydrogen bond interaction, resulting in more stable ligand receptor complexes. In summary, SBSG exhibits significant immunomodulatory potential, similar to chondroitin sulfate C. The underlying molecular mechanism involved the binding of SBSG through hydrogen bonding to TLR4 receptors, triggering the NF-κB signaling pathway to downregulate the expression of related genes and proteins. This, in turn, regulated the secretion of various cytokines that were mediated by macrophages to exert the immunity of the body.

Anti-inflammatory effect of proanthocyanidins from blueberry through NF-κβ/NLRP3 signaling pathway in vivo and in vitro

BACKGROUND

Systemic inflammatory response syndrome (SIRS) is an uncontrolled systemic inflammatory response. Proanthocyanidins (PC) is a general term of polyphenol compounds widely existed in blueberry fruits and can treat inflammation-related diseases. This study aimed to explore the regulatory effect of PC on lipopolysaccharide (LPS)-induced systemic inflammation and its potential mechanism, providing effective strategies for the further development of PC.

METHODS

Here, RAW264.7 macrophages were stimulated with LPS to establish an inflammation model in vitro, while endotoxin shock mouse models were constructed by LPS in vivo. The function of PC was investigated by MTT, ELISA kits, H&E staining, immunohistochemistry, and Western blot analysis.

RESULTS

Functionally, PC could demonstrate the potential to mitigate mortality in mice with endotoxin shock, as well as attenuated the levels of inflammatory cytokines (IL-6, TNF-α) and biochemical indicators (AST, ALT, CRE and BUN). Moreover, it had a significant protective effect on lung and kidney tissues damage. Mechanistically, PC exerted anti-inflammatory effects by inhibiting the activation of the NF-κB/NLRP3 signaling pathway.

CONCLUSION

PC might have the potential ability of anti-inflammatory effects via modulation of the NF-κB/NLRP3 signaling pathway.

Structure and immunostimulatory activity studies on two novel Flammulina velutipes polysaccharides: revealing potential impacts of →6)-α-D-Glcp(1→ on the TLR-4/MyD88/NF-κB pathway

Two novel Flammulina velutipes (F. velutipes) polysaccharides, FVPH1 and FVPH2, were isolated and purified after hot water extraction. The structural characterization revealed that the backbone of FVPH1 consisted mainly of →6)-α-D-Glcp(1→, →3,4)-α-D-Galp(1→, →4)-α-L-Fucp(1→, and →4)-β-D-Manp(1→, while the backbone of FVPH2 consisted of →3)-α-D-Galp(1→, →3,4)-α-D-Manp(1→,→6)-α-D-Glcp(1→. The branches of FVPH1 contained →6)-α-D-Glcp(1→ and α-D-Glcp(1→ and the branches of FVPH2 consisted of →3)-α-D-Galp(1→, →6)-α-D-Glcp(1→, and β-L-Fucp(1→. FVPH2 exhibited significantly better immunostimulatory activity than FVPH1 (P < 0.05), as evidenced by the increased expression of NO, IL-1β, IL-6, and TNF-α and pinocytic activity of RAW264.7 cells. As the most abundant structure in the polysaccharides of F. velutipes, the content of →6)-α-D-Glcp(1→ might play a crucial role in influencing the immunostimulatory activity of F. velutipes polysaccharides. The F. velutipes polysaccharide with a lower content of →6)-α-D-Glcp(1→ and a higher branching degree could significantly enhance the immunostimulatory activity of F. velutipes polysaccharides via activating the TLR-4/MyD88/NF-κB pathway more effectively.

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.

Preparation, structural characterization, bioactivities, and applications of Crataegus spp. polysaccharides: A review

Crataegus, is a genus within the Rosaceae family. It is recognized as a valuable plant with both medicinal and edible qualities, earning it the epithet of the "nutritious fruit" owing to its abundant bioactive compounds. Polysaccharides are carbohydrate polymers linked by glycosidic bonds, one of the crucial bioactive ingredients of Crataegus spp. Recently, Crataegus spp. polysaccharides (CPs) have garnered considerable attention due to their diverse range of bioactivities, including prebiotic, hypolipidemic, anticancer, antibacterial, antioxidant, and immunobiological properties. Herein, we provide a comprehensive overview of recent research on CPs. The analysis revealed that CPs exhibited a broad molecular weight distribution, ranging from 5.70 Da to 4.76 × 108 Da, and are composed of various monosaccharide constituents such as mannose, rhamnose, and arabinose. Structure-activity relationships demonstrated that the biological function of CPs is closely associated with their molecular weight, galacturonic acid content, and chemical modifications. Additionally, CPs have excellent bioavailability, biocompatibility, and biodegradability, which make them promising candidates for applications in the food, medicine, and cosmetic industries. The article also scrutinized the potential development and future research directions of CPs. Overall, this article provides comprehensive knowledge and underpinnings of CPs for future research and development as therapeutic agents and multifunctional food additives.

Molecular Insights into the Macrophage Immunomodulatory Effects of Scrophulariae Radix Polysaccharides

Scrophulariae Radix (SR) has been widely used in Chinese herbal compound prescriptions, health care products and functional foods. The present study aimed to investigate the immunomodulatory activity of polysaccharides from SR (SRPs) in macrophages and explore the potential mechanisms. The results showed that four SRPs fractions (SRPs40, SRPs60, SRPs80 and SRPs100) had similar absorption peaks and monosaccharide compositions, but the intensities of absorption peaks and monosaccharide contents were distinguished. All SRPs fractions significantly enhanced the pinocytic activity, promoted the production of NO and TNF-α, increased the mRNA expressions of inflammatory factors (IL-1β, IL-6, TNF-α and PTGS2) and TLR2, and elevated the phosphorylation levels of p38, ERK, JNK, p65 and IκB. Moreover, the production of NO and TNF-α stimulated by SRPs was dramatically suppressed by anti-TLR2 antibody. These results indicated that SRPs activated macrophages through MAPK and NF-κB signaling pathways via recognition of TLR2.

Dietary Artemisia Ordosica Polysaccharide Enhances Spleen and Intestinal Immune Response of Broiler Chickens

The spleen and small intestines are the primary immune organs that provide important immunity against various diseases. Artemisia ordosica polysaccharide (AOP) could be used as an immunologic enhancer to boost immunity in response to infection. This study was performed to explore the effects of the dietary supplementation of AOP on the growth performance and spleen and small intestine immune function in broilers. A total of 288 AA broilers (1 day old) were randomly assigned into six dietary groups. Each group included six replicates of eight broilers per cage. The broilers were fed with a basal diet supplemented with 0 mg/kg (CON), 50 mg/kg chlortetracycline (CTC), 250, 500, 750, and 1000 mg/kg AOP for 42 d. The results showed that dietary AOP supplementation affected broiler growth performance, with 750 and 1000 mg/kg of AOP being able to significantly improve broiler BWG, and 750 mg/kg of AOP was able to significantly reduce the FCR. The dietary AOP supplementation increased the levels of IgA, IgG, IgM, IL-1β, IL-2, and IL-4 in the spleen and small intestine in a dose-dependent manner (p < 0.05). Meanwhile, we found that AOP can promote the mRNA expression of TLR4/MAPK/NF-κB signaling-pathway-related factors (TLR4, MyD88, P38 MAPK, JNK, NF-κB p50, and IL-1β). In addition, the dietary supplementation of 750 mg/kg AOP provides better immunity in the tissue than the CON group but showed no significant difference from the CTC group. Therefore, AOP has an immunoregulatory action and can modulate the immune function of broilers via the TLR4/ NF-ΚB/MAPK signal pathway. In conclusion, dietary supplementation with 750 mg/kg AOP may be alternatives to antibiotics for enhancing broilers' health, immunity, and growth performance.

A zinc-modified Anemarrhena asphodeloides polysaccharide complex enhances immune activity via the NF-κB and MAPK signaling pathways

Anemarrhena asphodeloides polysaccharide (AAP70-1) was reported to have immunomodulatory effects in our previous report. To further improve the immunomodulatory effects of AAP70-1, an A. asphodeloides polysaccharide-zinc complex (AAP-Zn) was synthesized using a ZnCl2 modification method, and the potential mechanisms by which AAP-Zn activates macrophages were investigated. The results showed that the structural features of AAP-Zn were similar to those of AAP70-1 with a Zn content of 0.2 %, confirming that Zn mainly interacted with AAP70-1 by forming ZnO coordination bonds and Zn…OH bonds. In addition, the administration of AAP70-1 and AAP-Zn effectively improved the immunomodulatory effects by enhancing phagocytosis and upregulating the mRNA expression of cytokines (TNF-α, IL-6, IL-1β, and IL-18), as well as increasing the production levels of nitric oxide (NO) and reactive oxygen species (ROS) in zebrafish embryos. The intracellular mechanism by which AAP-Zn activates macrophages was found to involve activation of the NF-κB and MAPK signaling pathways. Our findings suggested that AAP-Zn may be a potential immunopotentiator in the field of biomedicine or functional foods.

Structure Characterization and Immunomodulatory Activity of Misgurnus anguillicaudatus Carbohydrates

Misgurnus anguillicaudatus, also known as oriental weather loach, is widely consumed and favored in East Asia due to its superior nutritional values and excellent flavor. In this study, a crude Misgurnus anguillicaudatus carbohydrates (MAC) was isolated from Misgurnus anguillicaudatus. Subsequently, two parts, which were named MAO and MAP, respectively, were separated from MAC, and their primary structures and immunomodulatory activity were investigated. The results showed that MAO had a molecular weight of 2854 Da, and principally consisted of arabinose (77.11%) and rhamnose (21.97%), together with minor levels of fucose (0.92%); MAP, with a molecular weight of 3873 Da, was mainly composed of fucose (87.55%) and a small amount of rhamnose (8.86%) and galactose (3.59%). The in vitro assay showed that MAC could significantly enhance the proliferation of macrophages without cytotoxicity and increase the production of immune substances (TNF-α, IL-6). Together with Western blot results, we speculated that MAC could stimulate RAW264.7 murine macrophage cells to secrete TNF-α and IL-6 through up-regulating TLR4-MAPK-p38 signaling pathways. The results indicated that MAC could be a potential immune agent and might provide meaningful information for further chain conformation and immune mechanism research.

Structural characterization and anti-lipotoxicity effects of a pectin from okra (Abelmoschus esculentus (L.) Moench)

Okra (Abelmoschus esculentus (L.) Moench) is rich in various bioactive ingredients and used as a medicinal plant in traditional medicine. In the present study, to find the polysaccharide with anti-lipotoxicity effects from okra and clarify its structure, a pectin OP-1 was purified from okra, which had a backbone containing →4)-α-GalpA-(1 → residues, and 1,5-Ara linked the main chain through the O-3 of the residue →3,4)-α-GalpA-(1→, and the C-6 of residue 1, 4-α-GalpA replaced by methyl ester. In vitro experiments showed that OP-1 pretreatment alleviated oleic acid (OA)-induced lipid accumulation, ROS generation, apoptosis, transaminase leakage, and inflammatory cytokine secretion in HepG2 cells, resulting in reduced lipotoxicity. Further molecular results revealed that OP-1 increased Adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK) phosphorylation and affected the expression of AMPK downstream targets, including inhibit SREBP1c and FAS, as well as activate CPT-1A. Impressively, AMPK inhibitor dorsomorphin (Compound C) blocked the effects of OP-1 against lipotoxicity. The effects of OP-1 on lipid metabolism were also diminished by dorsomorphin. Our results demonstrated that OP-1 possesses a potent function in preventing lipotoxicity via regulating AMPK-mediated lipid metabolism and provide a novel insight into the future utilization of okra polysaccharide.

Immunoregulatory effects of Tetrastigma hemsleyanum polysaccharide via TLR4-mediated NF-κB and MAPK signaling pathways in Raw264.7 macrophages

Polysaccharide of Tetrastigma hemsleyanum (THP) exert antioxidant, antibacterial, lipid-lowering, and anti-inflammatory properties, especially some evidences have highlighted the efficiency of it as an anti-tumor agent. However, as a biological macromolecule with bidirectional immune regulation, the immunological enhancement effects of THP on macrophages and its underlying mechanisms are still largely unknown. In the present study, THP was prepared and characterized, and then the effect of THP on Raw264.7 cell activation was investigated. Structural characteristics of THP showed that the average molecular weight was 370.26 kDa, and the main monosaccharide composition was galactose, glucuronic acid, mannose, and glucose at a ratio of 31.56: 25.15: 19.44: 12.60, with high viscosity causing by relative high uronic acid. For immunomodulatory activity investigation, THP promoted the production of NO, IL-6 and TNF-α, as well as the expression of IL-1β, MCP-1, iNOS and COX-2, which were almost completely inhibited by TLR4 antagonist. Further study showed that THP could activate NF-κB and MAPK signaling pathways, and thus enhanced the phagocytic activity of Raw264.7 macrophages. In conclusion, the present study provided evidences that THP could be served as a new immunomodulator in both functional foods and the pharmaceutical field.

Characterization of macrophage activation after treatment with polysaccharides from ginseng according to heat processing

The worldwide persistence of infectious diseases is a significant public health issue. Consequently, studying immunomodulatory ingredients present in natural products, such as ginseng, is important for developing new treatment options. Here, we extracted three different types of polysaccharides from white (P-WG), red (P-RG), and heat-processed (P-HPG) ginseng and analyzed their chemical properties and immunostimulatory activity against RAW 264.7 murine macrophages. Carbohydrates were the main components of all three polysaccharide types, while uronic acid and protein levels were relatively low. Chemical analysis indicated that the content of carbohydrates (total sugar) increased with processing temperature, while that of uronic acid decreased. Treatment with P-WG, P-RG or P-HPG stimulated nitric oxide (NO) production and increased tumor necrosis factor alpha (TNF-α) and interleukin (IL)-6 levels in RAW 264.7 macrophages, with P-WG showing the highest activity among the three polysaccharides. The expression of inducible NO synthase, which affects NO secretion, was highest in the macrophages treated with P-WG. Analysis of intracellular signaling pathways showed that mitogen-activated protein kinases (ERK, JNK, and p38) and NF-kB p65 were strongly phosphorylated by P-WG in macrophages but were only moderately phosphorylated by P-RG and P-HPG. Collectively, these results suggest that the polysaccharides isolated from ginseng undergo different changes in response to heat processing and display different chemical compositions and immune-enhancing activities.

Purification, structural elucidation and biological activities of exopolysaccharide produced by the endophytic Penicillium javanicum from Millettia speciosa Champ

An acid polysaccharide, named HP, was produced by endophytic Penicillium javanicum MSC-R1 isolated from southern medicine Millettia speciosa Champ. The molecular weight of HP was 37.8 kDa and consisted of Ara f, Galр, Glcр, Manр, and GlcрA with a molar ratio of 1.09: 3.47: 68.48: 16.59: 8.85. The glycosidic linkage of HP was proven to be →3, 4)-α-D-Glcр-(1→6)-α-D-Manр-(1→, →3, 4)-α-D-Glcр-(1→4)-α-D-Glcр-(1→, →3), →6)-α-D-Manр-(1→4)-α-D-Glcр-(1→, →3), β-D-Galр-(1→3)-α-D-Glcр-(1→, →4), →5)-α-L-Ara f -(1→3)-α-D-Glcр-(1→, →4), →6)-α-D-Manр-(1→4)-α-D-GlcAр-(1→ and →4)-α-D-GlcAр-(1→4)-α-D-Glcр-(1→, →3). Additionally, 250 μg/mL of HP possessed nontoxicity to RAW 264.7 cells and exhibited anti-inflammation activity. HP could significantly restrain the amount of tumor necrosis factor-α, interleukin-6 and NO release in RAW264.7, which property is possibly associated with its abundant glucosidic linkage. These results indicated that HP could be regarded as a ponderable ingredient for the health-beneficial functional foods.

Effects of Sparassis latifolia neutral polysaccharide on immune activity via TLR4-mediated MyD88-dependent and independent signaling pathways in RAW264.7 macrophages

Background

Sparassis latifolia (S. latifolia) is a precious edible fungus with multiple biological activities. To date, no study has been investigated the underlying molecular mechanism of immunoregulation caused by the neutral polysaccharide of S. latifolia.

Materials and methods

To investigate immunomodulatory mechanism of S. latifolia neutral polysaccharide (SLNP), SLNP was obtained from S. latifolia and its structure, immune receptors and regulation mechanism were studied.

Results

S. latifolia neutral polysaccharide consisted of arabinose, galactose, glucose, xylose, and mannose with a molar ratio of 6:12:63:10:5. SLNP was a pyran polysaccharide with a relative molecular weight of 3.2 × 105 Da. SLNP promoted the proliferation of RAW264.7, which further induced the secretions of nitric oxide, TNF-α, IL-6, and IFN-β, and upregulated the immune receptor TLR4 expression. Moreover, SLNP increased remarkably the levels of TRAF6, IRF3, JNK, ERK, p38, and p38 mRNA and protein mediated by TLR4.

Conclusion

S. latifolia neutral polysaccharide regulated the immune function of RAW264.7 through MyD88-dependent and -independent signaling pathways mediated by TLR4 receptor, which suggests that SLNP is a new immunomodulator.

Immunoenhancement activity of Bletilla striata polysaccharide through MAPK and NF-κB signalling pathways in vivo and in vitro

Bletilla striata (Thunb.) Reichb.f., is a traditional Chinese medicine, and the Bletilla striata polysaccharide (BSP) is one of the principal components extracted from Bletilla striata with various biological activities. Previous studies have shown that many natural polysaccharides have significant immunomodulatory activities. However, as a plant polysaccharide, the research of BSP on immunomodulatory activities is limited. In this study, we aim to investigate the immunomodulatory effect of BSP in vivo and further explore its underlying mechanism in vitro. In vivo, a cyclophosphamide (CTX)-induced immunosuppression mice mode was established by intraperitoneal injection of CTX, and the immune-enhancing effect of BSP (25, 50 and 100 mg/kg) on immunosuppressed mice were evaluated. The result indicated that BSP could significantly improve the immune organ index and the content of immunoglobulin, TNF-α and IL-4 in serum. It was also found that BSP could clearly ameliorate the spleen damage induced by CTX. Meanwhile, the result showed that BSP could not only improve the proliferation of splenocytes, but also activate the lactate dehydrogenase (LDH) and acid phosphatase (ACP) in mouse spleen tissue. In vitro, potential mechanism was further revealed in macrophages. The result supported that BSP could activate macrophages with high phagocytic ability, and induce macrophages to secrete cytokines. Finally, it revealed that activation of NF-κB and MAPK signalling pathway should be the underlying mechanism of the immunoenhancment of BSP.

Immunomodulatory activity of Senegalia macrostachya (Reichenb. ex DC.) Kyal. & Boatwr seed polysaccharide fraction through the activation of the MAPK signaling pathway in RAW264.7 macrophages

Senegalia macrostachya (Reichenb. ex DC.) Kyal. & Boatwr seed (SMS) is a wild legume used as food and medicine in many African countries. In the current study, a novel polysaccharide (SMSP2) was extracted from SMS using hot water and purified with DEAE-52 cellulose. Its structure was characterized, and the immunomodulatory activity and possible molecular mechanism in murine macrophage RAW264.7 were explored. The results revealed that SMSP2 was a uronic acid-rich polysaccharide (51.6%, w/w) with a molecular weight of 52.07 kDa. The neutral sugars were mainly arabinose, xylose, mannose, and galactose at a molar ratio of 1.00 : 0.84 : 0.90 : 0.07. Interestingly, SMSP2 treatment markedly promoted macrophage proliferation and phagocytosis and induced the expression of inflammatory mediators, such as nitric oxide (NO), tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, IL-6, and IL-10. SMSP2-induced macrophage stimulation occurs through the activation of the mitogen-activated protein kinase (MAPK) signaling pathway. Moreover, macrophage surface complement receptor 3 (CR3) might play an important role in SMSP2-induced macrophage activation. This study revealed that SMSP2 is a potent immunomodulator, which could be used as a functional food and a pharmaceutical adjuvant in treating immune-compromising diseases.

Structural characterization and immunomodulatory effects of extracellular polysaccharide from Lactobacillus paracasei VL8 obtained by gradient ethanol precipitation

In this study, gradient ethanol precipitation method was applied to obtain the extracellular polysaccharides of Lactobacillus paracasei VL8 (VL8-EPS). The yields, physicochemical properties, and immunomodulatory effects of VL8-EPS obtained by precipitation at different ethanol concentrations (30%, 50%, and 70%, v/v) were compared. The results showed that VL8-EPSs were high molecular weight sulfated heteropolysaccharides, composed mainly of glucose and galactose, and the alteration of ethanol concentration had an effect on their chemical compositions, molecular weight distributions, monosaccharide composition, and surface structure, while the primary structure remained the same. Among the three polysaccharide fractions, VL8-EPS50 displayed better immunomodulatory activities compared with VL8-EPS30 and VL8-EPS70. VL8-EPS50 was found to exert immunomodulatory effects by enhancing the phagocytic activity of RAW264.7 cells and to promote their secretion of more nitric oxide; it also showed stronger thermal and solution stability. In summary, there was a correlation between the structural characteristics of polysaccharides and their immunomodulatory activity, and VL8-EPS50 was preferentially used for in vivo immunomodulatory activity. Practical Application This study opens up the source of raw materials for functional foods, which can provide some theoretical basis for the research and development of extracellular polysaccharides of lactic acid bacteria and promote their application in the future development of food industry.

Effects of Caulis Spatholobi Polysaccharide on Immunity, Intestinal Mucosal Barrier Function, and Intestinal Microbiota in Cyclophosphamide-Induced Immunosuppressive Chickens

The protective effects of Caulis Spatholobi polysaccharide (CSP) on immune function, intestinal mucosal barrier, and intestinal microflora in cyclophosphamide (CY)-induced immunosuppressed chickens have been rarely reported. This study was designed to investigate the cecal microbiota in chickens and to elucidate the immune mechanism involved in the CSP effect on CY induced-immunosuppressed chickens. A total of 288 cocks were equally divided into six groups and used to evaluate the immune effect of CSP. Results showed that the CSP increased the body weight and immune organ index of immunosuppressed chickens, significantly increased the secretion of cytokines (IL-4, IL-10) and immunoglobulins (IgG, IgM) in sera of chickens, and restored the body immune function. The CSP reduced intestinal injury of the jejunum and ileum, increased the ratio of the intestinal villus height to crypt depth (V/C), improved the expression of tight junction protein, and protected intestinal health. The CSP activated the toll-like receptor (TLR)/MyD88/NF-κB pathway and enhanced the expression of TLR4, MyD88, NF-κB, Claudin1, and Zo-1, protecting the intestinal tract. High-throughput sequencing of the 16S rRNA gene showed that CSP increased species richness, restored CY-induced intestinal microbiome imbalance, and enhanced the abundance of Lactobacillus in the intestinal tract. In conclusion, our study provided a scientific basis for CSP as an immune enhancer to regulate intestinal microflora and protect intestinal mucosal damage in chickens.

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.

Protective effect of Yangxue Jiedu Soup against psoriasis-like lesions by regulating TLR4/NF-κB signaling pathway mediated by secretion of exosome HSP70

Psoriasis is a common chronic inflammatory hypertrophic skin disease characterized by abnormal proliferation and differentiation of keratinocyte and immune T cell. The pathogenesis of psoriasis has not been fully elucidated and there is no effective therapy in clinic. As a traditional Chinese medicine formula, Yangxue Jiedu Soup (YJS) has been used to treat inflammatory diseases caused by Yin Deficiency and Blood Dryness. The purpose of present study was to investigate the therapeutic effect and molecular mechanism of YJS on psoriasis model mice. Results showed that YJS effectively inhibited the hypertrophy, erythema and scales of psoriasis-like lesions to alleviate the pathological changes of skin lesions, and further decreased the production of TNF-α, IL-6, IL-1β, IFN-γ, IL-17 and IL-23. Meanwhile, YJS also significantly reduced keratinocyte proliferation and maintained immune system balance by inhibiting the expression of PCNA, Ki-67, CD4 + and CD8 + in psoriasis mice. Moreover, the results further indicated that YJS could inhibit TLR4 activation and NF-κB p65 nuclear transfer by suppressing HSP70 secretion to attenuate the inflammatory response in IMQ-induced mice, which provided a theoretical basis for the clinical use of YJS in the treatment of psoriasis.

A Novel Polysaccharide Isolated From Fresh Longan (Dimocarpus longan Lour.) Activates Macrophage via TLR2/4-Mediated PI3/AKT and MyD88/TRAF6 Pathways

A novel immunomodulatory polysaccharide (LP4) with a molecular weight 6.31 × 10⁴ g/mol was purified from fresh longan pulp. It was composed of mannose, glucose, glucuronic acid, galactose, xylose, arabinose, galacturonic acid, fucose, and rhamnose in a molar percentage of 36:31:10:7:4:4:3:2:2, and mainly linked by (1→6)-β-Man, (1→4)-β-Glc and (1→6)-α-Glc. LP4 can obviously enhance the phagocytosis of macrophages and promote the proliferation of lymphocytes. After treating macrophages with LP4 (12.5–50 μg/ml), the production of IL-1β and TNF-α was significantly increased. These increases of cytokines were suppressed when the TLR2/TLR4 receptors were inhibited by anti-TLR2 and/or anti-TLR4 antibodies. Moreover, the mRNA expression of INOS, AKT, PI3K, TRAF6 and MyD88 was significantly suppressed by TLR2/TLR4 antibodies. These results indicated that LP4 induced macrophage activation mainly via the TLR2 and TLR4-induced PI3K/AKT and MyD88/TRAF6 pathways.

Interaction between polysaccharides and toll-like receptor 4: Primary structural role, immune balance perspective, and 3D interaction model hypothesis

Various structural types of polysaccharides are recognized by toll-like receptor 4 (TLR4). However, the mechanism of interaction between the polysaccharides with different structures and TLR4 is unclarified. This review summarized the primary structure of polysaccharides related to TLR4, mainly including molecular weight, monosaccharide composition, glycosidic bonds, functional groups, and branched-chain structure. The optimal primary structure for interacting with TLR4 was obtained by the statistical analysis. Besides, the dual-directional regulation of TLR4 signaling cascade by polysaccharides was also elucidated from an immune balance perspective. Finally, the 3D interaction model of polysaccharides to TLR4-myeloid differentiation factor 2 (MD2) complex was hypothesized according to the LPS-TLR4-MD2 dimerization model and the polysaccharides solution conformation. The essence of polysaccharides binding to TLR4-MD2 complex is a multivalent non-covalent bond interaction. All the arguments summarized in this review are intended to provide some new insights into the interaction between polysaccharides and TLR4.

Ovotransferrin exerts bidirectional immunomodulatory activities via TLR4-mediated signal transduction pathways in RAW264.7 cells

The immune regulation function of ovotransferrin (OVT) explored using the RAW264.7 was induced by lipopolysaccharide (LPS) as vitro model in this study. The results showed that RAW264.7 cultured with OVT (200 μg/ml) alone not only enhanced the phagocytic activity and the production and expression of inflammatory factors, but also expression of toll-like receptor 4 (TLR4) gene was significantly promoted by OVT. OVT (50 μg/ml) significantly inhibited the secretion and expression of inflammatory factors in LPS-stimulated RAW264.7, but CD14 and TLR4 genes expressions were no obvious effects. Inflammatory cytokines and NO secreted by OVT-induced macrophages pretreated with inhibitors of TLR4 were down-regulated. We further verified the effects of OVT on inflammatory signaling pathway-related proteins through immunofluorescence and western blotting, MyD88, TLR4 and the phosphorylation of IκBα and p65 were significantly promoted by OVT, but there was no significant effects on the phosphorylation of IRF3. OVT promoted the phosphorylation of ERK and p38 in RAW264.7 and inhibited the phosphorylated expression of MAPK in LPS-mediated inflammation. These results indicated that OVT had the bidirectional immunoregulatory function through TLR4-mediated NF-κB/MAPK signaling pathway, that is, anti-inflammatory effect of low concentration and immune-enhancing activity of high concentration were showed. That provides a theoretical utilization for the development and utilization of OVT.

Immune-related effects of compound astragalus polysaccharide and sulfated epimedium polysaccharide on newborn piglets

This study aimed to evaluate the immune effects of compound astragalus polysaccharide and sulfated epimedium polysaccharide (APS-sEPS) on the peripheral blood lymphocyte and intestinal mucosa in newborn piglets. A total of 40 newborn piglets were randomly divided into four groups during a 25-day experiment, including APS-sEPS, APS, sEPS and control group. The results showed that supplementation with APS-sEPS to newborn piglets remarkably increased the physiological parameters, especially the WBC. In peripheral blood, piglets that received APS-sEPS showed the highest proliferation of T lymphocytes, the percentage of CD3 + CD4+ and CD3 + CD8+ cells were the highest on days 15 and 25 (p < 0.05). The serum concentrations of IFN-γ on days 7 and 15, and IL-4, IL-10, sIgA on days 7, 15 and 25 in APS-sEPS group were significantly higher than those in the control group (p < 0.05). Furthermore, the villus length and the ratio of villus length to crypt depth in APS-sEPS group were both significantly increased compared to that of control group (p < 0.05). In the duodenum, jejunum and illume, the concentrations of IFN-γ, IL-10, total IgG and sIgA in APS-sEPS group were all significantly higher than that in control group (p < 0.05). In intestinal mucosa, APS-sEPS significantly increased the expression of NF-κB and IRF-3 mRNA in each section of small intestine of piglets. Nevertheless, in the illume segment, the effect of APS-sEPS was more significant than that of APS and sEPS (p < 0.05). The expression of TLR4 was more significant than that of control group in duodenum only. The results from the present research provide evidence that the suckling piglets administered with APS-sEPS supplement exhibited enhanced immune function of peripheral blood lymphocyte and expression of specific antibodies, and ameliorated intestinal morphological development and increased activities of humoral immune response in the small intestine, which would be related to the activation of the TLR4-NF-κB signaling pathway and IRF3.

Polysaccharide MCP extracted from Morchella esculenta reduces atherosclerosis in LDLR-deficient mice

The pharmaceutical application of fungal polysaccharides has been extensively studied based on their multiple biological activities. However, the effect of Morchella esculenta polysaccharides on the development of atherosclerosis remains unknown. This study aims to investigate the anti-atherosclerotic effect of a novel polysaccharide (MCP) extracted from Morchella esculenta. The average molecular weight of MCP is 1.69 × 10⁵ Da, and it is composed of glucose, mannose and galactose in the molar ratio of 1 : 1.9 : 0.51. LDLR-deficient (LDLR^-/-) mice were fed high-fat diet (HFD) and administered intragastrically (i.g.) with saline or MCP dissolved in saline for 15 weeks. We found that MCP inhibited en face and sinus lesions. Moreover, serum levels of total and low-density lipoprotein cholesterol and triglyceride were decreased by MCP. The HFD-induced hepatic lipid accumulation was also attenuated by MCP. The underlying molecular mechanisms of anti-atherogenic and lipogenic effects of MCP might be attributed to reduced cholesterol synthesis by activating AMPKα signaling pathway and inhibiting SREBP2 expression. In addition, MCP-decreased serum triglyceride level is related to inhibiting LXRα expression. Taken together, these results indicate that MCP markedly alleviates atherosclerosis and M. esculenta can be used as a functional food additive to benefit patients with atherosclerosis.

Polysaccharides in natural products that repair the damage to intestinal mucosa caused by cyclophosphamide and their mechanisms: A review

Cyclophosphamide (CTX) is a commonly used antitumor drug in clinical practice, and intestinal mucosal injury is one of its main toxic side effects, which seriously affects the treatment tolerance and prognosis of patients. Therefore, the prevention of intestinal mucosal injury is a research hotspot. Studies have shown that polysaccharides can effectively prevent and improve CTX-induced intestinal mucosal injury and immune system disorders. Recent research has elucidated the structure, biological function, and physicochemical properties of polysaccharides that prevent intestinal mucosal injury, and the potential mechanisms whereby they have this effect. In this paper, we review the recent progress made in understanding the effects of polysaccharides on intestinal mucosal injury and their protective mechanism in order to provide a reference for further research on the prevention of intestinal mucosal injury and the mechanisms involved in nutritional intervention.

The water-soluble non-starch polysaccharides from natural resources against excessive oxidative stress: A potential health-promoting effect and its mechanisms

The water-soluble non-starch polysaccharides isolated from natural resources have become research hotpots in the field of food science and human health due to widely distributed in nature and low toxicity. It has indicated that the health-promoting effect of water-soluble non-starch polysaccharides were partly attributable to against excessive oxidative stress. Indeed, excessive oxidative stress in the body has been reported in occurrence of disease. The water-soluble non-starch polysaccharides from natural resources exhibit antioxidant activity to against oxidative stress via scavenging free radicals promoting antioxidant enzymes activity and/or regulating antioxidant signaling pathways. In this review, the water-soluble non-starch polysaccharides as medicine agent and the factor affecting antioxidant as well as the relationship between oxidative stress and disease are summarized, and the mechanisms of water-soluble non-starch polysaccharides therapy in disease are also discussed. It will provide a theoretical basis for natural polysaccharides used for the treatment of diseases.

Immunomodulatory effects of wheat bran arabinoxylan on RAW264.7 macrophages via the NF-κB signaling pathway using RNA-seq analysis

Arabinoxylan (AX) extracted from wheat bran has attracted much attention due to its immunomodulatory activity. However, the molecular mechanisms underlying this activity remain unclear. In this study, we conducted a comprehensive transcriptional study to investigate genetic changes related to AX and identified 2325 differentially expressed genes (DEGs). Gene Ontology classification revealed that the DEGs were mainly enriched in a series of immune-related processes. Kyoto Encyclopedia of Genes and Genomes pathway analysis revealed that immune-related pathways were significantly enriched in top 20 pathways, including the nuclear factor-kappa B (NF-κB) signaling pathway and the TNF signaling pathway. Validation using quantitative polymerase chain reaction analysis revealed dynamic changes in the mRNA levels of immune-related Cd40, Csf1, Csf2, Fas, IL-1β, IL-6, IL-5, Irf1, and Tnfaip3, which were significantly up-regulated in the AX-treated group. Moreover, AX treatment led to the up-regulation of the nuclear translocation of NF-κB and its upstream target proteins such as PDK1, Akt, IκB-α, and GSK-3β. The dataset compiled from this study provides valuable information for further research on the complex molecular mechanisms associated with AX and the identification of target genes.

Mycoplasma pneumoniae lipids license TLR-4 for activation of NLRP3 inflammasome and autophagy to evoke a proinflammatory response

Mycoplasma pneumoniae is an obligate pathogen that causes pneumonia, tracheobronchitis, pharyngitis and asthma in humans. It is well recognized that membrane lipoproteins are immunostimulants exerting as lipopolysaccharides (LPS) and play a crucial role in the pathogenesis of inflammatory responses upon M. pneumoniae infection. Here, we report that the M. pneumoniae-derived lipids are another proinflammatory agents. Using an antibody-neutralizing assay, RNA interference or specific inhibitors, we found that Toll-like receptor 4 (TLR-4) is essential for M. pneumoniae lipid-induced tumour necrosis factor (TNF)-α and interleukin (IL)-1β production. We also demonstrate that NLR family pyrin domain containing 3 inflammasome (NLRP3) inflammasome, autophagy and nuclear factor kappa B (NF-κB)-dependent pathways are critical for the secretion of proinflammatory cytokines, while inhibition of TLR-4 significantly abrogates these events. Further characterization revealed that autophagy-mediated inflammatory responses involved the activation of NF-κB. In addition, the activation of NF-κB promoted lipid-induced autophagosome formation, as revealed by assays using pharmacological inhibitors, 3-methyladenine (3-MA) and Bay 11-7082, or silencing of atg5 and beclin-1. These findings suggest that, unlike the response to lipoprotein stimulation, the inflammation in response to M. pneumoniae lipids is mediated by the TLR-4 pathway, which subsequently initiates the activation of NLRP3 inflammasome and formation of a positive feedback loop between autophagy and NF-κB signalling cascade, ultimately promoting TNF-α and Il-1β production in macrophages.

Comparison of Physicochemical Characteristics and Macrophage Immunostimulatory Activities of Polysaccharides from Chlamys farreri

To address the structure-activity relationship of Chlamys farreri polysaccharides on their immunostimulatory efficacy, two polysaccharides (CFP-1 and CFP-2) were extracted from Chlamys farreri by hot water extraction, and separated through column chromatography. The isolated CFPs were chemically analyzed to clarify their physicochemical characteristics and cultured with murine macrophage RAW264.7 cells, in order to evaluate their immunostimulatory efficacy. Despite the fact that both CFP-1 and CFP-2 were mainly comprised of glucose lacking the triple-helix structure, as revealed through preliminary physicochemical analyses, obvious differences in regard to molecular weight (Mw), glucuronic acid content (GAc) and branching degree (BD) were observed between CFP-1 and CFP-2. In in vitro immunostimulatory assays for macrophage RAW264.7 cells, it was demonstrated that CFP-2 with larger Mw, more GAc and BD could evidently promote phagocytosis and increase the production of NO, IL-6, TNF-α and IL-1β secretion, by activating the expression of iNOS, IL-6, TNF-α and IL-1β genes, respectively. Hence, CFP-2 shows great promise as a potential immunostimulatory agent in the functional foods and nutraceutical industry, while CFP-1, with lower molecular weight, less GAc and BD, displays its weaker immunostimulatory efficacy, based on the indistinctive immunostimulatory parameters of CFP-1.

Structure and immunostimulating activity of a galactofuranose-rich polysaccharide from the bamboo parasite medicinal fungus Shiraia bambusicola

ETHNOPHARMACOLOGICAL RELEVANCE

Shiraia bambusicola is a parasitic fungus on the twigs of bamboos. Its relatively large stroma has high medicinal value and can treat a variety of diseases such as rheumatoid arthritis, cold stomach pain, sciatica, injuries, chronic bronchitis, and infantile. It is widely distributed in many provinces in Southern China and also is also found in Japan.

AIM OF THE STUDY

Medicinal fungi were important resources for bioactive polysaccharides. To explore bioactive polysaccharides from Shiraia bambusicola, a heteropolysaccharide SB2-1 was purified and obtained from S. bambusicola and its immunostimulating activity was researched.

MATERIALS AND METHODS

The polysaccharide from S. bambusicola was extracted and purified using enzyme assisted extraction, ethanol precipitation, anion-exchange and size-exclusion chromatography. Molecular weight of polysaccharide was estimated by high performance gel permeation chromatography. Monosaccharide compositions were determined by high performance liquid chromatography after pre-column derivatization and UV detection. Structure information was elucidated by IR spectrum, GC-MS analysis after methylation and gradual acid hydrolysis of the polysaccharide. The RAW264.7 cells were used to study the immunostimulating activity in vitro.

RESULTS

Physicochemical and structural analyses showed that SB2-1 was a neutral heteropolysaccharide with molecular weight at 22.2 kDa and consisted of glucose, galactose and mannose at a ratio of 2.0:1.5:1.0. The structure of SB2-1 was a branched polysaccharides composed of a mannan core and side chains consisted of glucose and galactose. The mannan core was composed of (1→2)-Manp as the main chain. Glucose with (1→4)-D-Glcp, (1→2)-D-Glcp and (1→6)-D-Glcp at different degrees of polymerization were linked at C-6 and C-3 of the (1→2)-Manp as the side chains. The galactose with the linages of (1→6)-D-Galf, →2)-D-Galf(1→ and terminal D-Galf(1→ also existed in the side chain. The study on the immunostimulating activities of SB2-1 and its core structure P-2 were investigated on RAW264.7 macrophages. The results showed that SB2-1 could activate RAW264.7 macrophage and significantly improve its phagocytic ability by neutral red uptake experiment. Meanwhile, SB2-1 increased significantly higher inducible nitric oxide synthase (iNOS) production and the productions of IL-1, IL-6, IL-12 and TNF-α. The effect of SB2-1 was better than its core structure P-2 produced by gradual acid hydrolysis, which meant the side chains played an important role in the immunostimulating activities.

CONCLUSIONS

The investigation demonstrated that the galactofuranose-containing mannogalactoglucan was characteristic polysaccharides in S. bambusicola and could enhance the activation of macrophages.

Isolation, structural elucidation, and immunoregulation properties of an arabinofuranan from the rinds of Garcinia mangostana

In our search for bioactive polysaccharides as immunomodulatory agents, an arabinofuranan (GMP90-1) was purified and characterized from the rinds of Garcinia mangostana L. GMP90-1 (absolute molecular weight: 5.30 × 10³ g/mol) was found to be composed of arabinose, galactose, and rhamnose. The backbone of GMP90-1 was determined as (1→5)-linked α-l-Araf, (1→2,3,5)-linked α-l-Araf, (1→3,5)-linked α-l-Araf, (1→6)-linked β-d-Galp, and (1→2)-linked α-l-Rhap. Conformational analysis revealed GMP90-1 to exist as a rigid rod structure in sodium chloride solution. To explore its potential as immunomodulatory agents, an in vitro cell screening was performed and GMP90-1 was found to significantly enhance the phagocytic uptake of neutral red and improve the secreted level of nitric oxide (NO), interleukin (IL)-6, IL-1β, and tumor necrosis factor-α (TNF-α) of macrophages. Furthermore, the cellular immunomodulatory activities were confirmed by the in vivo zebrafish experiment, which suggested that GMP90-1 with immunomodulatory effects could be considered as a potential immunomodulatory for immune diseases.

Yolkin Isolated from Hen Egg Yolk as a Natural Immunoregulator, Activating Innate Immune Response in BMDM Macrophages

One of the goals of biomedical sciences is to search and identify natural compounds that are safe, have no side effects, and possess immunostimulatory activity. It has been proven that medicines of natural origin can be effective agents, supporting the therapy of many diseases, not only in the weakened immune system of the body but also in the prevention of many diseases in healthy people. It has been shown that yolkin, a polypeptide complex isolated from hen egg yolk as a fraction accompanying immunoglobulin Y (IgY), possesses potential biological activity. However, the mechanism of its action has not been explained. The objective of this investigation was to examine the molecular mechanisms of innate immune response, activated in response to yolkin, in murine bone marrow-derived macrophages (BMDM). It was shown that yolkin induced phosphorylation of extracellular signal-kinases (ERK1/2) and c-Jun N-terminal kinase (JNK) and upregulated expression and production of type I interferons, TNF-α (tumor necrosis factor α), and nitric oxide (NO), in BMDM cells. Using pharmacological inhibitors of ERK 1/2 and JNK kinases, we revealed that the JNK signaling cascade is required for yolkin-induced inducible NOS expression and upregulation of NO production in mouse macrophages. Using the TLR4-deficient BMDM cell line, we established that yolkin can activate macrophages in a TLR4-dependent manner. It was also shown that NO, TNF-α, and type I IFNs (α/β) produced by BMDM cells in response to yolkin triggered antiviral activity. These data indicate that yolkin affects the regulation of the immune system and antiviral response; therefore, it can be used as an effective immunostimulator of the innate immunity or as a supplement of the conventional therapy of immunodeficiency.

Isolation, purification, characterization and immunostimulatory activity of an exopolysaccharide produced by Lactobacillus pentosus LZ-R-17 isolated from Tibetan kefir

In this study, three strains of lactic acid bacteria isolated from Tibetan kefir grains, including two strains of Lactobacillus pentosus LZ-R-17 and L. helveticus LZ-R-5, and one strain of Lactococcus lactis subsp. lactis LZ-R-12. The ability of three strains to produce exopolysaccharide (EPS) was tested, and L. pentosus LZ-R-17 was found to have the highest EPS yield. One EPS (R-17-EPS) was isolated from the fermented milk by L. pentosus LZ-R-17 and purified by DEAE-52 anion exchange chromatography. Furthermore, R-17-EPS preliminary structure and macrophage immunomodulatory activity in vitro were investigated. On the basis of the analytical results of ultraviolet-visible spectrum, Fourier transform-infrared spectrum, monosaccharide composition analysis and one-dimensional and two-dimensional nuclear magnetic resonance (NMR) spectra, R-17-EPS was found to have an average molecular weight of 1.20 × 106 Da and was composed of galactose and glucose residues with a molar ratio of 1.00:3.15. NMR analysis revealed that the R-17-EPS was a linear hetero-galactoglucan containing repeating units of →2)-α-D-Galp-(1 → 4)-β-D-Glcp-(1 → 4)-β-D-Glcp-(1 → 4)-β-D-Glcp-(1→. In addition, R-17-EPS could effectively enhanced the proliferation, phagocytosis, nitric oxide and cytokines production of RAW264.7 cells, suggesting that R-17-EPS had potent immunostimulatory activity and could be explored as immunomodulator in functional food and/or medicine fields.

Sarcodon aspratus polysaccharides ameliorated obesity-induced metabolic disorders and modulated gut microbiota dysbiosis in mice fed a high-fat diet

The polysaccharides isolated from the fruit body of S. aspratus (SATPs) might be a potential health supplement or prebiotic in the prevention of obesity and associated metabolic disorders.