A polysaccharide extracted from alfalfa activates splenic B cells by TLR4 and acts primarily via the MAPK/p38 pathway

Natural polysaccharides and their derivatives targeting the tumor microenvironment: A review

Polysaccharides have gained attention as valuable supplements and natural medicinal resources, particularly for their anti-tumor properties. Their low toxicity and potent anti-tumor effects make them promising candidates for cancer prevention and treatment. The tumor microenvironment is crucial in tumor development and offers potential avenues for novel cancer therapies. Research indicates that polysaccharides can positively influence the tumor microenvironment. However, the structural complexity of most anti-tumor polysaccharides, often heteropolysaccharides, poses challenges for structural analysis. To enhance their pharmacological activity, researchers have modified the structure and properties of natural polysaccharides based on structure-activity relationships, and they have discovered that many polysaccharides exhibit significantly enhanced anti-tumor activity after chemical modification. This article reviews recent strategies for targeting the tumor microenvironment with polysaccharides and briefly discusses the structure-activity relationships of anti-tumor polysaccharides. It also summarises the main chemical modification methods of polysaccharides and discusses the impact of chemical modifications on the anti-tumor activity of polysaccharides. The review aims to lay a theoretical foundation for the development of anti-tumor polysaccharides and their derivatives.

Corrigendum: Immunomodulatory function and anti-tumor mechanism of natural polysaccharides: a review

[This corrects the article DOI: 10.3389/fimmu.2023.1147641.].

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.

Network pharmacology and molecular docking analysis on the mechanism of Cordyceps militaris polysaccharide regulating immunity through TLR4/TNF-α pathwayss

The role of polysaccharide components in the immune system, especially immunomodulatory effects, has received increasing attention. In this context, in this study, network pharmacology was adopted to explore the hypothesis of a multitarget mechanism for immune modulation by Chrysalis polysaccharides. A total of 174 common targets were screened by network pharmacology, with the main ones being TNF, MAPK3, CASP3, VEGFA, and STAT3, mostly enriched in the Toll pathway. The molecular docking results showed that the polysaccharide fraction of Chrysalis binds well to TNF proteins. Besides, in vitro cellular assays were performed to verify the ability of Chrysalis polysaccharides to regulate macrophage polarization and to screen for macrophage surface receptors. Furthermore, in vivo experiments were conducted to prove the activation of TLR4 and TNF-α protein expression in mice by Chrysalis polysaccharide.

Immunomodulatory function and anti-tumor mechanism of natural polysaccharides: A review

Polysaccharides extracted from natural resources have attracted extensive attention in biomedical research and pharmaceutical fields, due to their medical values in anti-tumor, immunomodulation, drug delivery, and many other aspects. At present, a variety of natural polysaccharides have been developed as adjuvant drugs in clinical application. Benefit from their structural variability, polysaccharides have great potential in regulating cellular signals. Some polysaccharides exert direct anti-tumor effects by inducing cell cycle arrest and apoptosis, while the majority of polysaccharides can regulate the host immune system and indirectly inhibit tumors by activating either non-specific or specific immune responses. As the essential of microenvironment in the process of tumor development has been gradually revealed, some polysaccharides were found to inhibit the proliferation and metastasis of tumor cells via tumoral niche modulation. Here, we focused on natural polysaccharides with biomedical application potential, reviewed the recent advancement in their immunomodulation function and highlighted the importance of their signaling transduction feature for the antitumor drug development.

Research progress on the mechanisms underlying poultry immune regulation by plant polysaccharides

With the rapid development of poultry industry and the highly intensive production management, there are an increasing number of stress factors in poultry production. Excessive stress will affect their growth and development, immune function, and induce immunosuppression, susceptibility to a variety of diseases, and even death. In recent years, increasing interest has focused on natural components extracted from plants, among which plant polysaccharides have been highlighted because of their various biological activities. Plant polysaccharides are natural immunomodulators that can promote the growth of immune organs, activate immune cells and the complement system, and release cytokines. As a green feed additive, plant polysaccharides can not only relieve stress and enhance the immunity and disease resistance of poultry, but also regulate the balance of intestinal microorganisms and effectively alleviate all kinds of stress faced by poultry. This paper reviews the immunomodulatory effects and molecular mechanisms of different plant polysaccharides (Atractylodes macrocephala Koidz polysaccharide, Astragalus polysaccharides, Taishan Pinus massoniana pollen polysaccharide, and alfalfa polysaccharide) in poultry. Current research results reveal that plant polysaccharides have potential uses as therapeutic agents for poultry immune abnormalities and related diseases.

“King of the forage”—Alfalfa supplementation improves growth, reproductive performance, health condition and meat quality of pigs

As one kind of high-quality feed with rich nutrients, including high quality protein and amino acids, dietary fiber, enriched vitamins and mineral elements and bioactive molecules, alfalfa has been widely used in the production of ruminant livestock. As the understanding of alfalfa becomes more and more comprehensive, it is found that the high-quality nutrients in alfalfa could have positive effects on pigs. An increasing number of researches have shown that supplementing dietary alfalfa to the diet of gestating sows reduced constipation, alleviated abnormal behavior, improved satiety and reproductive performance; supplementing dietary alfalfa to the diet of piglets improved growth performance and intestinal barrier function, reduced intestinal inflammatory response and diarrhea; supplementing dietary alfalfa to the diet of growing-fattening pigs improved production performance and pork quality. Moreover, the mechanisms by which various nutrients of alfalfa exert their beneficial effects on pigs mainly including dietary fiber stimulating intestinal peristalsis, enhancing the activity of digestive enzymes, and promoting the colonization of beneficial bacteria in the intestinal tract through fermentation in the intestine, producing short-chain fatty acids and thus improving intestinal health; high quality protein and amino acids are beneficial to improve animal health condition; rich vitamins and mineral elements play an important role in various physiological functions and growth and development of the body; and bioactive molecules can improve the antioxidant and anti-inflammatory level. Therefore, alfalfa could be used as pig feed ingredient to alleviate various problems in the pig industry and to improve pig production performance. In this review, we detail the current application of alfalfa in pigs and discuss the potential mechanisms involved in how alfalfa improves growth and reproductive performance, pork quality, and intestinal health of the animals, thus laying the foundation for the increased application of high-quality forage in pig production.

Regulation of innate and adaptive immunity using herbal medicine: benefits for the COVID-19 vaccination

Vaccination is a major achievement that has become an effective prevention strategy against infectious diseases and active control of emerging pathogens worldwide. In response to the coronavirus disease 2019 (COVID-19) pandemic, several diverse vaccines against severe acute respiratory syndrome coronavirus 2 have been developed and deployed for use in a large number of individuals, and have been reported to protect against symptomatic COVID-19 cases and deaths. However, the application of vaccines has a series of limitations, including protective failure for variants of concern, unavailability of individuals due to immune deficiency, and the disappearance of immune protection for increasing infections in vaccinated individuals. These aspects raise the question of how to modulate the immune system that contributes to the COVID-19 vaccine protective effects. Herbal medicines are widely used for their immune regulatory abilities in clinics. More attractively, herbal medicines have been well accepted for their positive role in the COVID-19 prevention and suppression through regulation of the immune system. This review presents a brief overview of the strategy of COVID-19 vaccination and the response of the immune system to vaccines, the regulatory effects and mechanisms of herbal medicine in immune-related macrophages, natural killer cells, dendritic cells, and lymphocytes T and B cells, and how they help vaccines work. Later in the article, the potential role and application of herbal medicines in the most recent COVID-19 vaccination are discussed. This article provides new insights into herbal medicines as promising alternative supplements that may benefit from COVID-19 vaccination.

Graphical abstract

http://links.lww.com/AHM/A31.

Structural characterization of mushroom polysaccharides by cyclic ion mobility-mass spectrometry

Polysaccharides are biopolymers known to possess various bioactivities. Because of their molecular complexity, the structural characterization of polysaccharides remains challenging, and difficult to be completed with a single analytical method. In this study, a novel approach for the characterization of linkages and anomeric configuration of polysaccharides was proposed. Based on ion mobility-mass spectrometry (IM-MS), a database containing 5 glucotriose standards was set up. Information about the arrival time distribution and fragmentation patterns of these standards were included. The method was validated by three commercially available purified polysaccharides, namely laminarin, dextrin, and dextran, each having distinct connectivity and configuration of the glycosidic bonds. Lastly, the method was successfully applied to analyze polysaccharides prepared from three medicinal mushrooms, namely Xylaria nigripes, Grifola frondosa, and Laetiporus sulphureus. The results showed that water-soluble non-digestible polysaccharides of X. nigripes and G. frondosa were mainly composed of (1→3)-β-glucan, while that of L. sulphureus was composed of (1→3)-ɑ-glucan. The present method has the advantages of being simple in sample preparation and short analysis time.

Antitumor effect of a polysaccharide from Pseudostellaria heterophylla through reversing tumor-associated macrophages phenotype

Tumor-associated macrophages (TAMs), which are predominant tumor-infiltrating immune cells in the tumor microenvironment, participate in promoting the occurrence and metastasis of tumor cells. Reprogramming TAMs has become a promising immunotherapeutic approach for novel cancer treatments. In this study, a homogeneous polysaccharide (PHP-1) was obtained from Pseudostellaria heterophylla, and its antitumor and immunological activities, as well as the underlying molecular mechanisms were explored. These findings suggested that PHP-1 can switch M2 macrophages to the M1 type, thereby promoting tumor cell apoptosis in vitro. In addition, PHP-1 can modulate the TAMs phenotype, maintain the CD4⁺/CD8⁺ lymphocyte balance, and exert antitumor effects in H22 tumor-bearing mice. Mechanistically, PHP-1 is recognized by the TLR4 receptor, promotes Ca²⁺ release, and activates the NF-κB and MAPK signaling pathways to reset the M2-type macrophages. These findings indicate that PHP-1 from P. heterophylla can function as a tumor immunotherapeutic modulator.

Structural characterization of a polysaccharide from Trametes sanguinea Lloyd with immune-enhancing activity via activation of TLR4

A bioactive polysaccharide (TS2-2A) with a molecular weight of 15 kDa was isolated from Trametes sanguinea Lloyd, a medicinal food homologous fungus, by water extraction-alcohol precipitation and chromatographic separation. NMR analysis of polysaccharide and MS/MS analysis of its oligosaccharide indicated that TS2-2A featured a novel straight chain with a backbone of 1,3-α-d-glucopyranose and 1,4-β-d-glucopyranose at a molar ratio of 1:4. Moreover, TS2-2A, recognized by Toll-like receptor 4 (TLR4), stimulated RAW 264.7 macrophages to release related cytokines and contributed to immune-enhancing effects. Briefly, with remarkable immune-enhancing activity and noncytotoxicity, TS2-2A was proposed to be a potential immune enhancer for supplementing drugs or functional foods.

Changes in immune genes expression, immune response, digestive enzymes -antioxidant status, and growth of catla (Catla catla) fed with Astragalus polysaccharides against edwardsiellosis disease

The effect of four level of Astragalus polysaccharides (APs) supplementation diets, (CD: control diet and three experiment diet (E), EA: 100 mg kg^-1 APs; EB: 200 mg kg-1 APs; EC: 300 mg kg^-1 APs) on growth, changes in haemato-biochemical parameters and metabolic-digestive enzymes, enhancement of antioxidant activity, innate-adaptive immune response, and cytokine gene expression were studied in catla (Catla catla) against Edwardsiella tarda. The healthy and challenged groups fed the CD displayed no mortality, while fish fed EA or EC revealed 10% mortality, but the mortality was only 5% in diet EB. Fish fed diet EB and EC revealed significantly better growth rates and high RBC count during the experimental period. Albumin and globulin levels were significant improved when fish were fed the diet EB and EC from weeks 6-8. The superoxide dismutase (SOD) was significant ameliorated by EB feeding from weeks 4-8. In contrast, serum myeloperoxidase (MPO), catalase (CAT), malondialdehyde (MDA)/lipid peroxidation (LPO), glutathione peroxidase (GPx), respiratory burst activity (RBA), bactericidal action (BCA), serum lysozyme activity (SLA), nitric oxide synthase (NOS), head kidney leukocytes response proliferation (HKLP), hemolytic action (HLA), hydrogen peroxides (H₂O₂), and immunoglobulin (Ig) were significantly improved from week 6-8. Groups fed the APs enriched diets had significant ameliorated interleukin (IL)-1β and interferon (IFN)-γ mRNA expression after 6 and 8 weeks of feeding. However, IL-10 and major histocompatibility complex (MHC)-1 mRNA expressions were significant enhanced in catla fed all APs diets on week 8. APs enriched diets revealed significant improved tumor necrosis factor (TNF)-α and TNF receptor-associated factor-6 (TRAF6) mRNA expression on week 4, but toll-like receptor-2 (TLR2) and TLR4 mRNA expression were significant enhanced by diet EB and EC after weeks 6 and 8. Similarly, the lysozyme (Lyz)-C and Lyz-G mRNA levels in the head kidney (HK) increased by APs feeding on weeks 6 and 8, whereas the EB diet, the expression of nucleotide binding oligomerization domain-1 (NOD1) was significantly improved on weeks 6 and 8, but NOD2 mRNA expression was only significant enhanced after 8 weeks of diet EB. By feeding healthy catla and E. tarda challenged fish fed diet EB, resulted in significantly increased growth, haemato-biochemical indices, metabolic-digestive enzymes, antioxidant activities, innate-adaptive immune responses, and cytokine gene expression mainly between 6 and 8 weeks.

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.

Immune-Enhancing Effects of a Novel Glucan from Purple Sweet Potato Ipomoea batatas (L.) Lam on RAW264.7 Macrophage Cells via TLR2- and TLR4-Mediated Pathways

PSPP-1 was obtained from purple sweet potato, and the effects of PSPP-1 on the immune modulation on macrophage cells were investigated for the first time. PSPP-1 promoted RAW264.7 proliferation and increased the total cell percentage in DNA synthesis and mitosis phases, and the cell morphology changed in volume and appearance. Additionally, the RAW264.7 immune functions of phagocytic activity and nitric oxide, reactive oxygen species, and cytokine production were improved by PSPP-1. The western blot experiment showed that PSPP-1 could activate toll-like receptor 2 and toll-like receptor 4-mediated pathways, and the expressions of proteins in MyD88-dependent, mitogen-activated protein kinase (MAPK)-signaling, NF-κB-signaling, AP-1 signaling, and TRIF-dependent pathways were improved markedly. Molecular docking and Biolayer Interferometry study further indicated that PSPP-1 could recognize and bind TLR2 and TLR4 by targeting the binding sites with a strong affinity. It suggested that PSPP-1 could enhance immunity via TLR2- and TLR4-mediated pathways, and it could be explored as an immunomodulatory agent.

Development of Broad-Spectrum Antiviral Agents-Inspiration from Immunomodulatory Natural Products

Developing broad-spectrum antiviral drugs remains an important issue as viral infections continue to threaten public health. Host-directed therapy is a method that focuses on potential targets in host cells or the body, instead of viral proteins. Its antiviral effects are achieved by disturbing the life cycles of pathogens or modulating immunity. In this review, we focus on the development of broad-spectrum antiviral drugs that enhance the immune response. Some natural products present antiviral effects mediated by enhancing immunity, and their structures and mechanisms are summarized here. Natural products with immunomodulatory effects are also discussed, although their antiviral effects remain unknown. Given the power of immunity and the feasibility of host-directed therapy, we argue that both of these categories of natural products provide clues that may be beneficial for the discovery of broad-spectrum antiviral drugs.