Immunomodulatory potential of polysaccharides derived from plants and microbes: A narrative review

Immune Basis of Therapeutic Effects of Solanum tuberosum L. Polysaccharide on Chronic Peptic Ulcer Healing

Background/Objectives: Polysaccharides are complex molecules with a wide range of biological activities that can be used in various biomedical applications. In this work, the antiulcer effect and influence on the level of pro- and anti-inflammatory cytokines of Solanum tuberosum L. polysaccharide (STP) were studied. Methods: The antiulcer effect of STP was studied in the Okabe chronic peptic ulcer model by evaluating the influence of STP on the ulcer index in Wistar rats, comparing it to omeprazole and ranitidine. Dose-effect analysis was also carried out. The level of pro- and anti-inflammatory cytokines was studied using ELISA kits. Results: After treatment in the polysaccharide groups, ulcer healing is observed in 60-80% of cases, in the omeprazole group in 50%, and in the ranitidine group in 25%. STP intravenous injections lead to the formation of a more differentiated mucous membrane; no coarse scar tissue is formed, which is typical for control and comparison drugs. Glycan causes a significant acceleration of the healing of experimental peptic ulcers in rats. STP appears to modulate pro- and anti-inflammatory cytokines. On the fourth and tenth days, a significant decrease in the levels of pro-inflammatory cytokines IL-1b and IFN-γ was noted in the polysaccharide group compared to the control group, while the level of anti-inflammatory cytokine IL-4 significantly increased. Conclusions: Intravenous administration of STP leads to the restoration of functionality and effective tissue regeneration. The antiulcer activity of STP is based on the regulation of the pro- and anti-inflammatory balance.

Structural characterization and antioxidant activity mechanism of the ferulic acid-rich subfraction from sugar beet pectin

The feruloylated sugar chain in sugar beet pectin (SBP) is a natural polyphenol-polysaccharide complex. Its low abundance often leads to be neglected, thereby hindering its bioactivity and mechnism research. In this study, SBP-3 A, a novel feruloylated polysaccharide fragment, was isolated from sugar beet pectin utilizing enzymatic digestion. The presence of ferulic acid on SBP-3 A was confirmed through high-performance liquid chromatography (HPLC), with a mass fraction of 22.5 μg/mg. The average molecular weight was determined to be 33.31 kDa. Methylation analysis, and nuclear magnetic resonance (NMR) spectra revealed that SBP-3 A is a heteroglycan with the main chain structure of →2)-α-Rhap-(1 → 4)-α-GalpA-(1 → 2)-α-Rhap-(1→, and the branched chain structure of ferulic acid (FA) → 3,4)-β-Galp-(1 → 2,4)-α-Rhap-(1→. Subsequently, the antioxidant activity of SBP-3 A was evaluated using the Caenorhabditis elegans (C. elegans). SBP-3 A improved antioxidant enzymes and non-enzymatic defense system, decreased reactive oxygen species levels, and up-regulated the mRNA expression of sod-3, skn-1, and daf-16, while down-regulated the expression of age-1 in C. elegans. Moreover, SBP-3 A modulated the gut flora by favorably affecting the abundances of Lactobacillus, Ligilactobacillus, and Akkermansia, thereby enhancing antioxidant capacity in C. elegans. Consequently, the aforementioned findings support the potential application of SBP-3 A as a functional food for treating oxidative stress-related illnesses.

Construction of an Innovative Nanogel and Its Applications for Achieving Chemo-Immunotherapy of Tumors

Malignant tumors, also known as cancers, are a global public health problem. Nanogels are promising carriers for the delivery of anticancer medicines. Therefore, based on the unique microenvironment of tumor cells and the advantages of nanogels, a simple and economical one-pot synthesis method was designed to construct natural polysaccharide-based redox-responsive nanogels (LDD NGs). The enhanced permeability and retention (EPR) effect enriched LDD NGs in tumor cells, which then rapidly collapsed and released the natural antitumor drug diosgenin (DG) and the natural polysaccharide lentinan (LNT) via the depletion of a high level of reduced glutathione (GSH) in tumor cells, resulting in a synergistic therapeutic effect of chemotherapy and immunotherapy. In vivo antitumor experiments showed that LDD NGs could inhibit the proliferation and metastasis of the A549 lung cancer cells. Further studies indicated that LDD NGs could increase the production of ROS and induce apoptosis of A549 cells. In addition, LNT released from LDD NGs could promote the proliferation of dendritic cells, increase the production of NO, and upregulate the expressions of the costimulatory molecules CD40, CD80, CD86, and MHC-II. The construction of LDD NGs was a novel drug synthesis approach that could provide fresh ideas for the development of polysaccharide-based redox-responsive drug delivery systems.

Candida albicans infection model in Drosophila melanogaster suggests a strain-specific virulent factor boosting a stormy innate immune response

Intorduction

Pathogens drive the evolution of host defence strategies, with both innate and adaptive immune systems playing key roles. Priming enhances the innate immune system's readiness by functionally reprogramming immune cells after initial exposure to stimuli, like β-glucans. In this sense, Drosophila melanogaster is a valuable model to evaluate the role of innate immunity to control infections.

Objectives

In this study we aimed to set light on the immune priming effect of oral treatment with heat-killed M. manresensis and two different heat-killed C. albicans isolates upon systemic infection by C. albicans in the D. melanogaster model.

Methods

A clinical and a control ATCC 90028 Candida albicans strain were used. Flies were primed through oral administration of heat-killed C. albicans (hkCa), both clinical and control, and hk-Mycolicibacterium manresensis. After priming, flies were systemically infected with both C. albicans isolates. Host survival, pathogen load, and immune response in response to treatment and infection were evaluated.

Results

Both treatments showed a significant capacity to enhance the expression of antimicrobial peptides, in particular Diptericin, and Drosomycin in males. This response had a marked sexual dimorphism due to the difference in Upd3, Nox, and Duox expression. Surprisingly, even when priming was able to avoid the growth of both C. albicans strains, survival was not improved in the case of the clinical isolate, causing an unexpected mortality rate in hours, regardless of the host's sex. Gene expression analysis 24 hours post-infection showed an exacerbated increase in Diptericin, Drosomycin and Upd3 expression upon infection with the clinical strain.

Conclusion

Data herein suggests the presence of a strain-specific component in C. albicans as the booster of a "stormy" innate immune response, which must be further investigated, and position D. melanogaster as a useful model for evaluating virulent factors related to the modulation of the innate immunity.

An antitumor fungal polysaccharide from Fomitopsis officinalis by activating immunity and inhibiting angiogenesis

Macrofungi, a class of unique natural resources, are gaining popularity owing to their potential therapeutic benefits and edibility. From Fomitopsis officinalis, a medicinal macrofungus with anticancer activity, a homogeneous heteropolysaccharide (FOBP50-1) with a molecular weight of 2.21 × 104 g/mol has been extracted and purified. FOBP50-1 was found to be composed of 3-O-methylfucose, fucose, mannose, glucose, and galactose with a ratio of 1: 6.5: 4.4: 8.1: 18.2. The sugar fragments and structure of FOBP50-1 were investigated, which included →6)-α-d-Galp-(1→, →2,6)-α-d-Galp-(1→, →3)-α-l-Fucp-(1→, α-d-Glcp-(1→, →3)-β-d-Manp-(1→, →6)-β-d-Manp-(1→, 3-O-Me-α-l-Fucp-(1→, according to the UV, FT-IR, GC-MS, and NMR data. Besides the structure elucidation, FOBP50-1 showed promising antitumor activity in the zebrafish assays. The following mechanism examination discovered that FOBP50-1 interacted with TLR-4, PD-1, and VEGF to activate immunity and inhibit angiogenesis according to a series of cell, transgenic zebrafish, and surface plasmon resonance (SPR) experiments. The KD values indicating the association of FOBP50-1 with TLR-4, PD-1, and VEGF, were 4.69 × 10-5, 7.98 × 10-6, 3.04 × 10-6 M, respectively, in the SPR experiments. All investigations have demonstrated that the homogenous fungal polysaccharide FOBP50-1 has the potential to be turned into a tumor immunotherapy agent.

Receptor basis of biological activity of polysaccharides

Polysaccharides, the most diverse forms of organic molecules in nature, exhibit a large number of different biological activities, such as immunomodulatory, radioprotective, antioxidant, regenerative, metabolic, signaling, antitumor, and anticoagulant. The reaction of cells to a polysaccharide is determined by its specific interaction with receptors present on the cell surface, the type of cells, and their condition. The effect of many polysaccharides depends non-linearly on their concentration. The same polysaccharide in different conditions can have very different effects on cells and organisms, up to the opposite; therefore, when conducting studies of the biological activity of polysaccharides, both for the purpose of developing new drugs or approaches to the treatment of patients, and in order to clarify the features of intracellular processes, information about already known research results is needed. There is a lot of scattered data on the biological activities of polysaccharides, but there are few reviews that would consider natural polysaccharides from various sources and possible molecular mechanisms of their action. The purpose of this review is to present the main results published at different times in order to facilitate the search for information necessary for conducting relevant studies.

Polymeric biomaterial-inspired cell surface modulation for the development of novel anticancer therapeutics

Immune cell-based therapies are a rapidly emerging class of new medicines that directly treat and prevent targeted cancer. However multiple biological barriers impede the activity of live immune cells, and therefore necessitate the use of surface-modified immune cells for cancer prevention. Synthetic and/or natural biomaterials represent the leading approach for immune cell surface modulation. Different types of biomaterials can be applied to cell surface membranes through hydrophobic insertion, layer-by-layer attachment, and covalent conjugations to acquire surface modification in mammalian cells. These biomaterials generate reciprocity to enable cell-cell interactions. In this review, we highlight the different biomaterials (lipidic and polymeric)-based advanced applications for cell-surface modulation, a few cell recognition moieties, and how their interplay in cell-cell interaction. We discuss the cancer-killing efficacy of NK cells, followed by their surface engineering for cancer treatment. Ultimately, this review connects biomaterials and biologically active NK cells that play key roles in cancer immunotherapy applications.

Characteristics of exopolysaccharides produced by isolates from natural bioflocculant of Ruditapes philippinarum conglutination mud

Three novel types of exopolysaccharides (EPS) EPS-S8, EPS-S5, and EPS-F10 were extracted and purified from bacterial isolates Bacillus sp. GHS8, Pseudoalteromonas sp. GHS5 and Psychrobacter sp. GHF10, which were originated from natural bioflocculant of Ruditapes philippinarum conglutination mud (RPM), respectively. The EPS had similar function groups C-H, N-H, C-O, and C = O. The EPS were composed of different monosaccharides (EPS-F10, Man: GlcN: GlcUA: GalUA = 1:0.66:5.75:0.51; EPS-S5, Man: Gal: GlcN: Rib = 1: 0.50: 2.94: 0.26; EPS-S8, Man: Gal: GlcN = 1:1.54:7.69). The molecular weights (Mw) of EPS were ordered as 51.4 kDa (EPS-S5) > 9.15 kDa (EPS-S8) > 4.41 kDa (EPS-F10). Three types of EPS all showed higher peak flocculation activities than the reported crude EPS from the RPM. Besides, the EPS also exhibited efficient decoloration and antioxidation activities, especially for EPS-S8, which might be due to the low Mw and specific monosaccharide composition.

Guava (Psidium guajava L.) seed: A low-volume, high-value byproduct for human health and the food industry

Guava processing industries generate peel and seeds as primary waste fractions. Guava seeds obtained after fruit processing possess untapped potential in the field of food science due to the presence of a diversity of nutritional and bioactive compounds. Along with offering a detailed understanding of the nutritional attributes of guava seeds, the present review comprehensively elaborates on the therapeutic activities of their bioactive compounds, their techno-functional properties, and their other edible and nonedible applications. The limited molecular and biochemical mechanistic studies outlining the antioxidant, immunomodulatory, anticancer, antimicrobial, neuroprotective and antidiabetic activities of guava seeds available in the literature are also extensively discussed in this review. The use of guava seed constituents as food additives and food functional and structural modulators, primarily as fat reducers, emulsifiers, water and oil holding agents, is also conceptually explained. Additional human intervention and molecular mechanistic studies deciphering the effects of guava seeds on various diseases and human health are warranted.

Structural characterization and anti-inflammatory activity of a pectin polysaccharide AP2-c from the lignified okra

In this paper, a pectin polysaccharide AP2-c with molecular weight 6.69 × 10⁵  Da was obtained from the lignified okra. The monosaccharide composition analysis indicated that AP2-c consisted of galactose, rhamnose and galacturonic acid in a molar ratio of 2.3: 1.5: 1.5. The structural characterization indicated that the main chain of AP2-c was composed of →2)-α-L-Rhap-(1→ and →4)-α-D-GalAp-(1→. →2)-α-L-Rhap-(1→ was branched at position O-4 and the branched chain consisted of →3,6)-β-D-Galp-(1→, →6)-β-D-Galp-(1→, α-L-Rhap-(1→ and β-D-Galp-(1→. AP2-c could inhibit the mRNA expression levels of TNF-α, IL-1β and iNOS in LPS-induced macrophages with a dose-dependent manner. Furthermore, AP2-c inhibited the phosphorylation of IκB and p65 via NF-κB pathway. The results indicated that AP2-c had obvious anti-inflammatory activity. PRACTICAL APPLICATIONS: When okra seeds were harvested, lignified okra was always abandoned as waste and had not been fully used for exploitation. Nevertheless, it accounted for more than half of the total plant's weight and was abundant in cell wall polysaccharides, which were the main components of okra to perform a variety of biological functions. In the research, the purified pectin polysaccharide AP2-c was obtained from lignified okra and its physicochemical properties, structural features and anti-inflammatory activity were systematically researched. It was detected that AP2-c exhibited anti-inflammatory activity by blocking NF-κB pathway and thus lowering the expression of related inflammatory factors. The results have significant implications for the value-added application of okra and its processing side products can obviously help to promote the anti-inflammatory application of AP2-c and avoid wasting resources.

Antioxidant, antibacterial, antitumor, antifungal, antiviral, anti-inflammatory, and nevro-protective activity of Ganoderma lucidum: An overview

Ganoderma lucidum is a very medicinal mushroom that has been utilized in Oriental medicine for many years. It has a wide range of pharmacological and therapeutic properties, and has been used for many years as a health promoter. It contains various biologically active compounds that improve the immune system and have antioxidant, antitumor, anti-inflammatory, antifungal, and antimicrobial properties. Active compounds include triterpenoids and polysaccharides, as well as proteins, lipids, phenolics, sterols, etc. In the following review, we summarize briefly their biological activities, such as antioxidant, anti-bacterial, anti-fungal, antitumor, anti-viral, and anti-inflammatory activity. Although Ganoderma has a number of medicinal effects that have been confirmed by the in vitro and in vivo studies summarised in this review, there are some limitations. Clinical trials face mainly a lack of pure constituents. Accurate identification of the compounds obtained is also problematic. In addition, most of the included studies were small, and there were concerns about the methodological quality of each study. Studies have shown that Ganoderma has valuable potential for the prevention and treatment of cancer. In any case, G. lucidum cannot be used as first-line therapy for cancer.

Current advances and potential trends of the polysaccharides derived from medicinal mushrooms sanghuang

For thousands of years, sanghuang is distinctive as a general designation for a group of precious and rare Chinese medicinal mushrooms. Numerous investigations have revealed that polysaccharide is one of the important biological active ingredients of sanghuang with various excellent biological activities, including antioxidant, anti-aging, anti-tumor, immunomodulatory, anti-inflammatory, anti-diabetic, hepatoprotective, and anti-microbial functionalities. For the past two decades, preparation, structural characterization, and reliable bioactivities of the polysaccharides from fruiting bodies, cultured mycelia, and fermentation broth of sanghuang have been arousing extensive interest, and particularly, different strains, sources, and isolation protocols might result in obvious discrepancies in structural features and bioactivities. Therefore, this review summarizes the recent reports on preparation strategies, structural features, bioactivities, and structure-activity relationships of sanghuang polysaccharides, which will enrich the knowledge on the values of natural sanghuang polysaccharides and support their further development and utilization as therapeutic agents, vaccines, and functional foods in tonic and clinical treatment.

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.

Sulfated Galactofucans: An Outstanding Class of Fucoidans with Promising Bioactivities

Fucoidans encompass versatile and heterogeneous sulfated biopolysaccharides of marine origin, specifically brown algae and marine invertebrates. Their chemistry and bioactivities have been extensively investigated in the last few decades. The reported studies revealed diverse chemical skeletons in which l-fucose is the main sugar monomer. However, other sugars, i.e., galactose, mannose, etc., have been identified to be interspersed, forming several heteropolymers, including galactofucans/fucogalactans (G-fucoidans). Particularly, sulfated galactofucans are associated with rich chemistry contributing to more promising bioactivities than fucans and other marine polysaccharides. The previous reports in the last 20 years showed that G-fucoidans derived from Undaria pinnatifida were the most studied; 21 bioactivities were investigated, especially antitumor and antiviral activities, and unique biomedical applications compared to other marine polysaccharides were demonstrated. Hence, the current article specifically reviews the biogenic sources, chemistry, and outstanding bioactivities of G-fucoidans providing the opportunity to discover novel drug candidates.

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.

Role of the dietary components in food allergy: A comprehensive review

Currently, the increasing incidence of food allergy is considered a major public health and food safety concern. Importantly, food-induced anaphylaxis is an acute, life-threatening, systemic reaction with varied clinical presentations and severity that results from the release of mediators from mast cells and basophils. Many factors are blamed for the increasing incidence of food allergy, including hygiene, microbiota (composition and diversity), inopportune complementary foods (a high-fat diet), and increasing processed food consumption. Studies have shown that different food components, including lipids, sugars, polyphenols, and vitamins, can modify the immunostimulating properties of allergenic proteins and change their bioavailability. Understanding the role of the food components in allergy might improve diagnosis, treatment, and prevention of food allergy. This review considers the role of the dietary components, including lipids, sugars, polyphenols, and vitamins, in the development of food allergy as well as results of mechanistic investigations in in vivo and in vitro models.

Recent Advancements in Microbial Polysaccharides: Synthesis and Applications

Polysaccharide materials are widely applied in different applications including food, food packaging, drug delivery, tissue engineering, wound dressing, wastewater treatment, and bioremediation sectors. They were used in these domains due to their efficient, cost-effective, non-toxicity, biocompatibility, and biodegradability. As is known, polysaccharides can be synthesized by different simple, facile, and effective methods. Of these polysaccharides are cellulose, Arabic gum, sodium alginate, chitosan, chitin, curdlan, dextran, pectin, xanthan, pullulan, and so on. In this current article review, we focused on discussing the synthesis and potential applications of microbial polysaccharides. The biosynthesis of polysaccharides from microbial sources has been considered. Moreover, the utilization of molecular biology tools to modify the structure of polysaccharides has been covered. Such polysaccharides provide potential characteristics to transfer toxic compounds and decrease their resilience to the soil. Genetically modified microorganisms not only improve yield of polysaccharides, but also allow economically efficient production. With the rapid advancement of science and medicine, biosynthesis of polysaccharides research has become increasingly important. Synthetic biology approaches can play a critical role in developing polysaccharides in simple and facile ways. In addition, potential applications of microbial polysaccharides in different fields with a particular focus on food applications have been assessed.