Immunostimulatory activity of exopolysaccharides from probiotic Lactobacillus casei WXD030 strain as a novel adjuvant in vitro and in vivo

Evaluation of antioxidant and anti-inflammatory properties of Lacticaseibacillus rhamnosus Ram12-derived exopolysaccharide in a D-galactose-induced liver injury mouse model

We investigated the antioxidant and anti-inflammatory properties of Lacticaseibacillus rhamnosus Ram12-derived EPSRam12 in a D-galactose-induced liver injury mouse model. Initially, EPSRam12 was characterized for its composition, molecular weight, and structural features. It was then administered orally to D-galactose-induced mice (which had received an intraperitoneal injection of D-galactose, 100 mg/kg body weight) at doses of 25 mg/kg (low dose) and 50 mg/kg (high dose) for 45 days. After treatment, biochemical markers, antioxidant status, cytokine levels, and liver inflammatory gene expression were evaluated. The results showed that EPSRam12 was a branched chain heteropolysaccharide comprising mannose, rhamnose, and arabinose monosaccharides with molecular weight of 2.6 million Daltons. EPSRam12, with its unique structural features such as hydroxyl and methyl groups, glycosidic bonds, and functional groups like carboxylates and sulfates, demonstrated promising bioactive properties. Administering EPSRam12 to D-galactose-induced mice resulted in a significant increase in antioxidant enzyme activity and a reduction in oxidative stress indicators. Additionally, it exhibited anti-inflammatory effects by modulating cytokine levels, lowering pro-inflammatory markers, and inhibiting key inflammatory pathways in the liver in a dose-dependent manner. Our findings underscore the potential of EPSRam12 as an effective antioxidant and anti-inflammatory agent, with promising applications in functional foods and pharmaceuticals.

Structure characterization and immunological activity of capsular polysaccharide from live and heat-killed Lacticaseibacillus paracasei 6235

Capsular polysaccharide (CPS) as a probiotic component has the ability to regulate the function of the host's immune system. However, how the structure and function of heat-killed CPS are altered remains unclear. In the present study, CPS were isolated and purified from live (LCPS) and heat-killed (HCPS) Lacticaseibacillus paracasei 6235. The differences in structure and immunomodulation between LCPS and HCPS were compared and analyzed. The results demonstrate that after heat killed, the molecular weight of CPS decreased from 23.4 kDa to 17.5 kDa, with the disappearance of galactosamine in the monosaccharide composition, and changes in the microstructure. Methylation analysis and nuclear magnetic resonance analysis revealed that the LCPS and HCPS are similar in structure, which main units of →3,4)-α-D-Glcp-(1→4)-α-D-Galp-(1→3)-β-L-Rhap-(1→6)-β-D-Galp-(1→, and repeating units of →3,4)-α-D-Glcp-(1→, →3)-β-L-Rhap-(1→, and →4)-α-D-Galp-(1→ residues. Furthermore, both LCPS and HCPS significantly downregulated the expression of pro-inflammatory cytokines in RAW264.7 cells induced by LPS. Specifically, HCPS reduced the levels of IL-6 and IL-1β by 79.38 % and 88.42 %, respectively, compared to LCPS. Concurrently, both LCPS and HCPS effectively mitigated inflammatory responses through the NF-κB and MAPK signaling pathways. Moreover, compared to LCPS, HCPS increased the protein expression levels of NF-κB/p-NF-κB and IκB/p-IκB by 26.14 % and 28.92 %, respectively. These results suggest that CPS has a role in modulating immune responses and that HCPS is more effective. This study can be further developed into new products related to postbiotics.

Advances in Microbial Exopolysaccharides: Present and Future Applications

Microbial exopolysaccharides (EPSs) are receiving growing interest today, owing to their diversity in chemical structure and source, multiple functions, and immense potential applications in many food and non-food industries. Their health-promoting benefits for humans deserve particular attention because of their various biological activities and physiological functions. The aim of this paper is to provide a comprehensive review of microbial EPSs, covering (1) their chemical and biochemical diversity, including composition, biosynthesis, and bacterial sources belonging mainly to lactic acid bacteria (LAB) or probiotics; (2) their technological and analytical aspects, especially their production mode and characterization; (3) their biological and physiological aspects based on their activities and functions; and (4) their current and future uses in medical and pharmaceutical fields, particularly for their prebiotic, anticancer, and immunobiotic properties, as well as their applications in other industrial and agricultural sectors.

Advances in serum-free media for CHO cells: From traditional serum substitutes to microbial-derived substances

The Chinese hamster ovary (CHO) cell is an epithelial-like cell that produces proteins with post-translational modifications similar to human glycosylation. It is widely used in the production of recombinant therapeutic proteins and monoclonal antibodies. Culturing CHO cells typically requires the addition of a certain proportion of fetal bovine serum (FBS) to maintain cell proliferation and passaging. However, serum is characterized by its complex composition, batch-to-batch variability, high cost, and potential risk of exogenous contaminants such as mycoplasma and viruses, which impact the purity and safety of the synthesized proteins. Therefore, search for serum alternatives and development of serum-free media for CHO-based protein biomanufacturing are of great significance. This review systematically summarizes the application advantages of CHO cells and strategies for high-density expression. It highlights the developmental trends of serum substitutes from human platelet lysates to animal-free extracts and microbial-derived substances and elucidates the mechanisms by which these substitutes enhance CHO cell culture performance and recombinant protein production, aiming to provide theoretical guidance for exploring novel serum alternatives and developing serum-free media for CHO cells.

Immunomodulatory activity and protective effect of a capsular polysaccharide in Caenorhabditis elegans, isolated from Lactobacillus fermentum GBJ

A capsular polysaccharide, namely CPS-2, was isolated from Lactobacillus fermentum GBJ, purified using DEAE-52 anion exchange chromatography, and structurally characterized. We found that CPS-2 is homogenous, has an average molecular weight of 377 KDa, and is mainly composed of galactose and glucose at a molar ratio of 1.54:1.00. Its backbone comprises α-D-Galp-(1 → 3), α-D-Galp-(1 → 3,6), β-D-Glcp-(1 → 2), β-D-Galp-(1 → 6), and α-D-Galp-(1 → 4) residues with a side chain of β-D-Glcp-(1→). CPS-2 exerts an immunomodulatory effect by improving the proliferation and phagocytosis of macrophage RAW264.7 and promoting the secretion of NO and cytokines. The maximum secretion levels of IL-1β, IL-6, IL-10, and TNF-α were 1.96-, 0.11-, 0.22-, and 0.46-fold higher than those of the control, respectively. Furthermore, CPS-2 could significantly enhance the antioxidant system, extend lifespan, and improve stress tolerance of Caenorhabditis elegans at both exposure doses of 31.25 and 62.5 μg/mL. The average lifespan of nematodes reached a maximum in the 62.5 μg/mL-treated group after 10.39 days, 6.56 h, and 23.56 h in normal, oxidative stress, and heat shock environment, with extension percentages of 16.61 %, 43.23 %, and 15.77 %, respectively; therefore, CPS-2 displays an anti-aging effect. The significant bioactivity of CPS-2 promotes its application as a promising immunomodulatory and anti-aging ingredient in the food or pharmaceutical field.

Exopolysaccharide from Weissella confusa J4-1 inhibits colorectal cancer via induction of cell cycle arrest

Exopolysaccharide (EPS), a bioproduct of lactic acid bacteria (LAB), has various health-promoting biological activities that may be beneficial for cancer therapy. This in vivo and in vitro study aimed to elucidate the anti-colorectal cancer (CRC) capacity of a homopolysaccharide EPS obtained from Weissella confusa J4-1 (EPSJ4-1) isolated from the faeces of healthy infants. We confirmed that EPSJ4-1 contained glucose and effectively suppressed the proliferation, migration, and invasion of CRC cells. EPSJ4-1 treatment significantly retarded the growth of HT-29 tumour xenografts without causing cytotoxicity to normal organs. EPSJ4-1 exerts an inhibitory effect on cell proliferation by inducing G0/G1 phase cell cycle arrest in CRC cells. Furthermore, EPSJ4-1 upregulated p21 levels and downregulated mutant p53 and cyclin kinase 2 levels. This is the first study to demonstrate the antitumour effects of EPS from W. confusa on CRC via cell cycle arrest and inhibition of cell migration and invasion, suggesting that EPSJ4-1 has the potential to be developed as a nutraceutical or pharmaceutical drug to prevent and treat CRC.

The Mechanisms of Probiotics, Prebiotics, Synbiotics, and Postbiotics in Oral Cancer Management

Oral carcinogenesis is preceded by oral diseases associated with inflammation such as periodontitis and oral candidiasis, which are contributed by chronic alcoholism, smoking, poor oral hygiene, and microbial infections. Dysbiosis is an imbalance of microbial composition due to oral infection, which has been reported to contribute to oral carcinogenesis. Therefore, in this review, we summarised the role of probiotics, prebiotics, synbiotics, and postbiotics in promoting a balanced oral microbiome, which may prevent oral carcinogenesis due to oral infections. Probiotics have been shown to produce biofilm, which possesses antibacterial activity against oral pathogens. Meanwhile, prebiotics can support growth and increase the benefit of probiotics. In addition, postbiotics possess antibacterial, anticariogenic, and anticancer properties that potentially aid in oral cancer prevention and treatment. The use of probiotics, prebiotics, synbiotics, and postbiotics for oral cancer management is still limited despite their vast potential, thus, discovering their prospects could herald a novel approach to disease prevention and treatment while participating in combating antimicrobial resistance.

Effect of combined in ovo administration of zinc glycine chelate (Zn-Gly) and a multistrain probiotic on the modulation of cellular and humoral immune responses in broiler chickens

The aim of the study was to determine the effect of in ovo administration of zinc glycine chelate (Zn-Gly), and a multistrain probiotic on the hatchability and selected parameters of the cellular and humoral immune response of chickens. The study was conducted on 1,400 fertilized eggs from commercial broiler breeders (Ross x Ross 708). Material for the study consisted of peripheral blood and spleens of chicks taken 12 h and 7 d after hatching. The results showed that both combined and single in ovo administration of the multistrain probiotic and zinc glycine chelate significantly reduced hatchability of chicks. The flow cytometry study showed that the highest percentage of CD4+ T cells, CD4+CD25+, and high expression of KUL01 in the serum were obtained in the group supplemented with probiotic and Zn-Gly both 12 h and 7 d after hatching. In birds supplemented with probiotic and zinc chelate, a high percentage of TCRγδ+ cells was found in serum and spleen 12 h after hatching and in serum after 7 d. The percentage of Bu-1A+ lymphocytes in serum and spleen 12 h and 7 d after hatching was the highest in the group supplemented with probiotic and Zn-Gly. The highest expression of CD79A was observed in the group supplemented only with zinc chelate. There were no significant differences in the percentage of CD4+ cells in the spleens of birds in the groups receiving the multistrain probiotic at 12 h after hatching, and after 7 d, the percentage of CD4+ T cells was lower in the experimental groups than in the control group. The percentage of CD8+ cells in the serum of birds after hatching was lower in the group supplemented with multistrain probiotic and Zn-Gly than in the control group, but reached the highest value on d 7 after hatching. The obtained results confirm the strong effect of the combined administration of a multistrain probiotic and Zn-Gly chelate on lymphocyte proliferation and stimulation of cellular immune mechanisms in birds.

Effects of the Exopolysaccharide from Lactiplantibacillus plantarum HMX2 on the Growth Performance, Immune Response, and Intestinal Microbiota of Juvenile Turbot, Scophthalmus maximus

In this study, the exopolysaccharide (EPS) from Lactiplantibacillus plantarum (HMX2) was isolated from Chinese Northeast Sauerkraut. Its effects on juvenile turbot were investigated by adding different concentrations of HMX2-EPS (C: 0 mg/kg, H1: 100 mg/kg, H2: 500 mg/kg) to the feed. Compared with the control group, HMX2-EPS significantly improved the growth performance of juvenile turbot. The activities of antioxidant enzymes, digestive enzymes, and immune-related enzymes were significantly increased. HMX2-EPS could also increase the secretion of inflammatory factors and enhance the immune response of turbot by regulating the IFN signal transduction pathway and exhibit stronger survival rates after the A. hydrophila challenge. Moreover, HMX2-EPS could improve the diversity of intestinal microbiota in juvenile fish, increase the abundance of potential probiotics, and reduce the abundance of pathogenic bacteria. The function of gut microbes in metabolism and the immune system could also be improved. All results showed better effects with high concentrations of HMX2-EPS. These results indicated that HMX2-EPS supplementation in the diet could promote growth, improve antioxidant activity, digestive capacity, and immunity capacity, and actively regulate the intestinal microbiota of juvenile turbot. In conclusion, this study might provide basic technical and scientific support for the application of L. plantarum in aquatic feed.

Exopolysaccharides from vaginal lactobacilli modulate microbial biofilms

BACKGROUND

Exopolysaccharides (EPS) secreted by beneficial lactobacilli exert a plethora of positive activities, but little is known about their effects on biofilms of opportunistic vaginal pathogens and especially on biofilms of lactobacilli themselves. Here, the EPS produced by six vaginal lactobacilli, belonging to Lactobacillus crispatus (BC1, BC4, BC5) and Lactobacillus gasseri (BC9, BC12, BC14) species were isolated from cultural supernatants and lyophilized.

RESULTS

Lactobacillus EPS were chemically characterized in terms of monosaccharide composition by liquid chromatography (LC) analysis coupled to UV and mass spectrometry (MS) detection. Moreover, the ability of EPS (0.1, 0.5, 1 mg/mL) to stimulate the biofilm formation of lactobacilli and to inhibit the formation of pathogens' biofilms was evaluated by crystal violet (CV) staining and 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay. Isolated EPS (yields 133-426 mg/L) were heteropolysaccharides mainly composed of D-mannose (40-52%) and D-glucose (11-30%). For the first time we demonstrated that Lactobacillus EPS were able to stimulate in a dose-dependent manner (p < 0.05) the formation of biofilms of ten strains belonging to L. crispatus, L. gasseri and Limosilactobacillus vaginalis species, in terms of cell viability (84-282% increase at 1 mg/mL) and especially biofilm biomass (40-195% increase at 1 mg/mL), quantified with MTT assay and CV staining, respectively. EPS released from L. crispatus and L. gasseri were found to better stimulate the biofilms of the same producer species rather than that of other species, including producing strains themselves and other strains. Conversely, the biofilm formation of bacterial (Escherichia coli, Staphylococcus spp., Enterococcus spp. and Streptococcus agalactiae) and fungal (Candida spp.) pathogens was inhibited. The anti-biofilm activity was dose-dependent and was more marked for L. gasseri-derived EPS (inhibition up to 86%, 70%, and 58% at 1 mg/mL, 0.5 mg/mL, and 0.1 mg/mL, respectively), whilst L. crispatus-derived EPS resulted overall less efficient (inhibition up to 58% at 1 mg/mL and 40% at 0.5 mg/mL) (p < 0.05).

CONCLUSIONS

Lactobacilli-derived EPS favour the biofilm formation of lactobacilli preventing, at the same time, that of opportunistic pathogens. These results support the possible employment of EPS as postbiotics in medicine as a therapeutic/preventive strategy to counteract vaginal infections.

Structural and Functional Characterization of Exopolysaccharide Produced by a Novel Isolate Bacillus sp. EPS003

An exopolysaccharide (EPS)-producing soil bacterium was isolated and characterized using 16S rRNA as Bacillus sp. EPS003. EPS was precipitated using ethanol and % composition of total carbohydrate, and protein was determined. Monosaccharide composition was identified using thin layer chromatography (TLC), and it was found to be a levan. Fourier transform infrared (FTIR) spectrum revealed the peaks for carboxyl, hydroxyl, and amide functional groups. ¹H nuclear magnetic resonance (NMR) spectrum further confirmed the presence of fructose monomer. Field emission scanning electron microscopic images (FE-SEM) revealed porous and amorphous characteristics of EPS which was further confirmed with broad peaks in X-ray diffraction (XRD) spectrum. Elemental composition was determined using energy-dispersive X-ray analysis (EDAX). Thermogravimetric analysis (TGA) of EPS resulted in a residual mass of 33.81% at 548 °C indicating high thermal stability. In addition, solubility index and water-holding capacity of EPS were found to be 56% and 264%, respectively, making EPS suitable for various applications. Further, antioxidant potential of EPS was studied using hydroxyl and DPPH radical scavenging assays. In vitro cytotoxicity assessment using L929 cells and SK-MEL-3 cell lines clearly indicated that the EPS produced by the novel isolate Bacillus sp. EPS003 could serve as a potential anticancer agent.

Physicochemical and rheological characterizations of a novel exopolysaccharide EPSKar1 and its iron complex EPSKar1-Fe: Towards potential iron-fortification applications

Iron is a micronutrient essential for human health and physiology. Iron-deficiency anemia, the most common form of anemia, may occur from an iron homeostasis imbalance. Iron fortification is a promising and most sustainable and affordable solution to tackle the global prevalence of this anemia. Herein, we investigate physicochemical, rheological and stability characteristics of a novel exopolysaccharide 'EPSKar1' (derived from Lacticaseibacillus rhamnosus strain Kar1) and its iron complex 'EPSKar1-Fe (II)'. Our findings demonstrate that EPSKar1 is a high molecular-weight (7.8 × 10⁵ Da) branched-chain heteropolysaccharide composed of galactose, N-acetylglucosamine, and mannose in a molar ratio of 8:4:1, respectively, and exhibits strong emulsifying and water-holding capacities. We find that EPSKar1 forms strong complexes with Fe, wherein the interactions between EPSKar1-Fe (II) complexes are mediated by sulfate, carboxyl, and hydroxyl groups. The rheological analyses reveal that the EPSKar1 and EPSKar1-Fe (II) complexes exhibited shear thickening and thinning properties in skim milk and water, respectively; however, the suspension of EPSKar1 in skim milk is viscoelastic with predominantly elastic response (G'>G" and tan δ < 1). In comparison, EPSKar1-Fe (II) complex exhibits remarkable stability under various processing conditions, highlighting its usefulness for the development of fortified dairy products. Together, these findings underpin considerable prospects of EPSKar1-Fe (II) complex as a novel iron-fortifier possessing multifarious rheological benefits for food applications.

Microbial exopolysaccharides-β-glucans-as promising postbiotic candidates in vaccine adjuvants

The urgent task of creating new, enhanced adjuvants is closely related to our comprehension of their mechanisms of action. A few adjuvants have shown sufficient efficacy and low toxicity to be allowed for use in human vaccines, despite the fact that they have a long history and an important function. Adjuvants have long been used without a clear understanding of how precisely they augment the immune response. The rational production of stronger and safer adjuvants has been impeded by this lack of information, which necessitates more mechanistic research to support the development of vaccines. Carbohydrate structures-polygalactans, fructans, β-D-glucans, α-D-glucans, D-galactose, and D-glucose-are desirable candidates for the creation of vaccine adjuvants and immunomodulators because they serve important functions in nature and are often biocompatible, safe, and well tolerated. In this review, we have discussed recent advances in microbial-derived carbohydrate-based adjuvants, their immunostimulatory activity, and the implications of this for vaccine development, along with the critical view on the microbial sources, chemical composition, and biosynthetic pathways.

Stimulating immunoglobulin response by intramuscular delivery of exopolysaccharides-adjuvanted mannheimiosis vaccine in goats

Background and Aim

Pneumonic mannheimiosis (PM) is a common respiratory bacterial disease among small ruminants. Despite numerous management methods, vaccination remains a suitable strategy to combat or reduce PM in goats and sheep. Thus, a study was conducted in Malaysia to evaluate the immunogenicity of exopolysaccharide-adjuvanted Mannheimia haemolytica A2 vaccine (EPS-MHA2) under laboratory and field conditions for its potential use as an efficient vaccine against PM.

Materials and Methods

This study induced immunoglobulin (Ig) responses following intramuscular (IM) delivery of the EPS-MHA2 vaccine on 12 goats for about 7 months. Goats were divided into three groups, with three goats per group, and they were vaccinated intramuscularly as follows: Group 1 was vaccinated with an adjuvanted vaccine prepared from formalin-killed M. haemolytica serotypes A2 and EPS excipient; Group 2 was vaccinated with formalin-killed M. haemolytica seed only, whereas Group 3 was injected with phosphate-buffered saline (PBS) as the negative control. Measures of specific immunity included serum IgM, IgG, and IgA as well as bronchoalveolar lavage fluid secretory IgA and the size and number of the bronchus-associated lymphoid tissue (BALT).

Results

From the 1^st day of vaccination, Groups 1 and 2 showed a significant (p < 0.05) increase in serum IgM, IgG, and IgA levels. However, the antibodies started to decline 5-week post-vaccination, indicating that the booster dose was necessary. On the second exposure to the same vaccine (booster), the level of antibodies showed a significant increase (p < 0.05), particularly IgG. All groups were challenged intratracheally by virulent MHA2 2 weeks after the decline of second antibodies on the administration of booster. All goats were euthanatized and necropsied 4-week post-challenge. The number and size of the BALT in Group 1 goats significantly increased compared with those in Group 2 and the unvaccinated control. Bacteriological parameters were evaluated, in which MHA2 was reisolated successfully from lung samples in Group 3. The IgA level produced by the group vaccinated with EPS-MHA2 was significantly (p < 0.001) higher than that the MHA2 vaccine and PBS groups. All data obtained were analyzed statistically using a one-way analysis of variance. The results indicate that IM injection of EPS-MHA2 vaccine significantly enhanced the immune response against MHA2.

Conclusion

Therefore, the addition of EPS to MHA2 (EPS-MHA2 vaccine) can effectively protect goats from lethal mannheimiosis infection. Factors such as the ideal concentration of EPS should be further studied to verify its application potential as a vaccine adjuvant, and the extraction of EPS from different microalgae species should be further investigated. This study showed a novel and exciting set of data and a vaccination system, in which the suppressive effects of mannheimiosis may be further investigated.

Immunostimulatory Activity of Lactic Acid Bacteria Cell-Free Supernatants through the Activation of NF-κB and MAPK Signaling Pathways in RAW 264.7 Cells

Lactic acid bacteria (LAB) can improve host health and has strong potential for use as a health functional food. Specific strains of LAB have been reported to exert immunostimulatory effects. The primary goal of this study was to evaluate the immunostimulatory activities of novel LAB strains isolated from humans and foods and to investigate the probiotic properties of these strains. Cell-free supernatants (CFS) obtained from selected LAB strains significantly increased phagocytosis and level of nitric oxide (NO) and pro-inflammatory cytokines such as tumor necrosis factor (TNF)-α and interleukin (IL)-6 in RAW264.7 macrophage cells. The protein expression of inducible NO synthase (iNOS) and cyclooxygenase (COX)-2, which are immunomodulators, was also upregulated by CFS treatment. CFS markedly induced the phosphorylation of nuclear factor-κB (NF-κB) and MAPKs (ERK, JNK, and p38). In addition, the safety of the LAB strains used in this study was demonstrated by hemolysis and antibiotic resistance tests. Their stability was confirmed under simulated gastrointestinal conditions. Taken together, these results indicate that the LAB strains selected in this study could be useful as probiotic candidates with immune-stimulating activity.

Bacterial polysaccharides-A big source for prebiotics and therapeutics

Bacterial polysaccharides are unique due to their higher purity, hydrophilic nature, and a finer three-dimensional fibrous structure. Primarily, these polymers provide protection, support, and energy to the microorganism, however, more recently several auxiliary properties of these biopolymers have been unmasked. Microbial polysaccharides have shown therapeutic abilities against various illnesses, augmented the healing abilities of the herbal and Western medicines, improved overall health of the host, and have exerted positive impact on the growth of gut dwelling beneficial bacteria. Specifically, the review is discussing the mechanism through which bacterial polysaccharides exert anti-inflammatory, antioxidant, anti-cancer, and anti-microbial properties. In addition, they are holding promising application in the 3D printing. The review is also discussing a perspective about the metagenome-based screening of polysaccharides, their integration with other cutting-edge tools, and synthetic microbiome base intervention of polysaccharides as a strategy for prebiotic intervention. This review has collected interesting information about the bacterial polysaccharides from Google Scholar, PubMed, Scopus, and Web of Science databases. Up to our knowledge, this is the first of its kind review article that is summarizing therapeutic, prebiotics, and commercial application of bacterial polysaccharides.

The early-life gut microbiome and vaccine efficacy

Vaccines are one of the greatest successes of public health, preventing millions of cases of disease and death in children each year. However, the efficacy of many vaccines can vary greatly between infants from geographically and socioeconomically distinct locations. Differences in the composition of the intestinal microbiome have emerged as one of the main factors that can account for variations in immunisation outcomes. In this Review, we assess the influence of the gut microbiota upon early life immunity, focusing on two important members of the microbiota with health-promoting and immunomodulatory properties: Bifidobacterium and Bacteroides. Additionally, we discuss their immune stimulatory microbial properties, interactions with the host, and their effect on vaccine responses and efficacy in infants. We also provide an overview of current microbiota-based approaches to enhance vaccine outcomes, and describe novel microbe-derived components that could lead to safer, more effective vaccines and vaccine adjuvants.

The Regulation of Micro-Organisms' Extra-Cellular Polysaccharides on Immunity: A Meta-Analysis

Extra-cellular polysaccharides (EPSs) have excellent immunomodulatory functions. In order to further promote their application, we studied the ability of extra-cellular polysaccharides from different sources to regulate immunity. We studied the association of extra-cellular polysaccharides with immune factors (Interleukin (IL-2, IL-4, IL-10), Interferon γ (IFN-γ), tumor necrosis factor-α (TNF-α), Immunoglobulin A (IgA), and Immunoglobulin G (IgG)) and different concentrations of EPSs and interfering media on experimental results by using a forest plot under fixed-effect or random-effects models. Through Google, PubMed, Embase, ScienceDirect, and Medline, from 2000 to 2021, 12 articles were included. We found that exopolysaccharides (from bacteria or fungi) could significantly increase the immune index of spleen and thymus, spleen index (SMD: 2.11, ‘95%CI: [1.15, 3.08]’; p < 0.01), and thymus index (SMD: 1.62, ‘95%CI: [0.93, 2.32]’; p = 0.01 < 0.05). In addition, exopolysaccharides had a significant effect on TNF-α (SMD: 0.94, ‘95%CI: [0.29, 1.59]’; p = 0.01 < 0.05). For IL-4 (SMD: 0.49, ‘95%CI: [0.01, 0.98]’; p = 0.046 < 0.05), extra-cellular polysaccharides had a statistically significant effect on immunity. Although the data of other immune factors were not ideal, the comprehensive analysis showed that exopolysaccharides also had an effect on the release of these five immune factors. In the sub-group analysis, different concentrations of EPSs affected the results of experiments on the spleen and thymus, and the CY intervention had a relatively significant effect on immune regulation. Taken together, our study highlighted that EPSs have a significant impact on immune regulation.

Immunostimulatory Effect of Heat-Killed Probiotics on RAW264.7 Macrophages

Probiotics modulate the gut microbiota, which in turn regulate immune responses to maintain balanced immune homeostasis in the host. However, it is unclear how probiotic bacteria regulate immune responses. In this study we investigated the immunomodulatory effects of heat-killed probiotics, including Lactiplantibacillus plantarum KC3 (LP3), Lactiplantibacillus plantarum CKDB008 (LP8), and Limosilactobacillus fermentum SRK414 (LF4), via phagocytosis, nitric oxide (NO), and pro-inflammatory cytokine production in macrophages. We thus found that heat-killed LP8 could promote the clearance of foreign pathogens by enhancing the phagocytosis of macrophages. Treatment with heat-killed LP8 induced the production of NO and pro-inflammatory cytokines, including TNF-α, IL-6, and IL-1β. In addition, heat-killed LP8 suppressed the production of NO and cytokines in LPS-induced RAW264.7 cells, suggesting that heat-killed LP8 exerts immunomodulatory effects depending on the host condition. In sum, these results indicate that heat-killed LP8 possesses the potential for immune modulation while providing a molecular basis for the development of functional probiotics prepared from inactivated bacterial cells.

The modulation and mechanism of probiotic-derived polysaccharide capsules on the immune response in allergic diseases

Allergic diseases, derived from the dysregulation of immune tolerance mechanisms, have been rising in the last two decades. Recently, increasing evidence has shown that probiotic-derived polysaccharide capsules exhibit a protective effect against allergic diseases, involving regulation of Th1/Th2 balance, induction of differentiation of T regulatory cells and activation of dendritic cells (DCs). DCs have a central role in controlling the immune response through their interaction with gut microbiota via their pattern recognition receptors, including Toll-like receptors and C-type-lectin receptors. This review discusses the effects and critical mechanism of probiotic-derived polysaccharide capsules in regulating the immune system to alleviate allergic diseases. We first describe the development of immune response in allergic diseases and recent relevant findings. Particular emphasis is placed on the effects of probiotic-derived polysaccharide capsules on allergic immune response. Then, we discuss the underlying mechanism of the impact of probiotic-derived polysaccharide capsules on DCs-mediated immune tolerance induction.

The effects of dietary immunostimulants on the innate immune response of Indian major carp: A review

Immunostimulants, as feed additives, play an important role in maintaining fish health and enhancing their overall growth by providing resistance against diseases in cultured fish. At the initial stages of life of fish, innate immunity is the essential mechanism in their survival. Later, innate immunity has an instructive role in adapting acquired immune response and homeostasis through different receptor proteins. Several studies have been conducted to analyze the effect of dietary immunostimulants like algae, plant extracts, vitamins, herbs, probiotics, and prebiotics-containing diets in Indian major carps. Many bacterial, fungal and viral pathogens are responsible for high death rates in both wild and cultured fish. It's a major limiting factor for world aquaculture industries. Recognition of invading pathogens by different pathogen recognition receptor plays an important role for the activation of different pathways to initiate protective immune responses. Hence, there is a growing need to control the devastating effects of diseases without recourse to toxic chemicals or antibiotics. Keeping with alternative approaches without using toxic chemicals to control fish diseases in mind, many immunostimulants are used, which enhance immune responses along with their gene expression level through different signaling pathway. The objective of this review is to summarize and evaluate the current knowledge of various immunostimulants and their immune responses in three Indian major carps namely Catla catla, Labeo rohita and Cirrhinus mrigala, which are preferred by the people.

Functional and health-promoting properties of probiotics' exopolysaccharides; isolation, characterization, and applications in the food industry

Exopolysaccharides (EPS) are extracellular sugar metabolites/polymers of some slim microorganisms and, a wide variety of probiotics have been broadly investigated for their ability to produce EPS. EPS originated from probiotics have potential applications in food, pharmaceutical, cosmetology, wastewater treatment, and textiles industries, nevertheless slight is recognized about their function. The present review purposes to comprehensively discuss the structure, classification, biosynthesis, extraction, purification, sources, health-promoting properties, techno-functional benefits, application in the food industry, safety, toxicology, analysis, and characterization methods of EPS originated from probiotic microorganisms. Various studies have shown that probiotic EPS used as stabilizers, emulsifiers, gelling agents, viscosifiers, and prebiotics can alter the nutritional, texture, and rheological characteristics of food and beverages and play a major role in improving the quality of these products. Numerous studies have also proven the beneficial health effects of probiotic EPS, including antioxidant, antimicrobial, anti-inflammatory, immunomodulatory, anticancer, antidiabetic, antibiofilm, antiulcer, and antitoxin activities. Although the use of probiotic EPS has health effects and improves the organoleptic and textural properties of food and pharmaceutical products and there is a high tendency for their use in related industries, the production yield of these products is low and requires basic studies to support their products in large scale.

Exopolysaccharides Produced by Lactic Acid Bacteria: From Biosynthesis to Health-Promoting Properties

The production of exopolysaccharides (EPS) by lactic acid bacteria (LAB) has attracted particular interest in the food industry. EPS can be considered as natural biothickeners as they are produced in situ by LAB and improve the rheological properties of fermented foods. Moreover, much research has been conducted on the beneficial effects of EPS produced by LAB on modulating the gut microbiome and promoting health. The EPS, which varies widely in composition and structure, may have diverse health effects, such as glycemic control, calcium and magnesium absorption, cholesterol-lowering, anticarcinogenic, immunomodulatory, and antioxidant effects. In this article, the latest advances on structure, biosynthesis, and physicochemical properties of LAB-derived EPS are described in detail. This is followed by a summary of up-to-date methods used to detect, characterize and elucidate the structure of EPS produced by LAB. In addition, current strategies on the use of LAB-produced EPS in food products have been discussed, focusing on beneficial applications in dairy products, gluten-free bakery products, and low-fat meat products, as they positively influence the consistency, stability, and quality of the final product. Highlighting is also placed on reports of health-promoting effects, with particular emphasis on prebiotic, immunomodulatory, antioxidant, cholesterol-lowering, anti-biofilm, antimicrobial, anticancer, and drug-delivery activities.

From Pre- and Probiotics to Post-Biotics: A Narrative Review

BACKGROUND AND AIMS

gut microbiota (GM) is a complex ecosystem containing bacteria, viruses, fungi, and yeasts. It has several functions in the human body ranging from immunomodulation to metabolic. GM derangement is called dysbiosis and is involved in several host diseases. Pre-, probiotics, and symbiotics (PRE-PRO-SYMB) have been extensively developed and studied for GM re-modulation. Herein, we review the literature data regarding the new concept of postbiotics, starting from PRE-PRO-SYMB.

METHODS

we conducted a search on the main medical databases for original articles, reviews, meta-analyses, randomized clinical trials, and case series using the following keywords and acronyms and their associations: gut microbiota, prebiotics, probiotics, symbiotic, and postbiotics.

RESULTS

postbiotics account for PRO components and metabolic products able to beneficially affect host health and GM. The deeper the knowledge about them, the greater their possible uses: the prevention and treatment of atopic, respiratory tract, and inflammatory bowel diseases.

CONCLUSIONS

better knowledge about postbiotics can be useful for the prevention and treatment of several human body diseases, alone or as an add-on to PRE-PRO-SYMB.

Adjuvant Effect of Orally Applied Preparations Containing Non-Digestible Polysaccharides on Influenza Vaccination in Healthy Seniors: A Double-Blind, Randomised, Controlled Pilot Trial

Senior individuals can suffer from immunosenescence and novel strategies to bolster the immune response could contribute to healthy ageing. In this double-blind, randomised, controlled pilot trial, we investigated the ability of non-digestible polysaccharide (NPS) preparations to enhance the immune response in a human vaccination model. In total, 239 subjects (aged 50-79 years) were randomised to consume one of five different NPS (yeast β-glucan (YBG), shiitake β-glucan (SBG), oat β-glucan (OBG), arabinoxylan (AX), bacterial exopolysaccharide (EPS)) or control (CTRL) product daily for five weeks. After two weeks of intervention, subjects were vaccinated with seasonal influenza vaccine. The post-vaccination increases in haemagglutination inhibition antibody titres and seroprotection rate against the influenza strains were non-significantly enhanced in the NPS intervention groups compared to CTRL. Specifically, a trend towards a higher mean log2 fold increase was observed in the AX group (uncorrected p = 0.074) combined with a trend for an increased seroprotection rate, AX group (48.7%) compared to CTRL (25.6%) (uncorrected p = 0.057), for the influenza A H1N1 strain. Subjects consuming AX also had a reduced incidence of common colds compared to CTRL (1 vs. 8; p = 0.029 in Fisher exact test). No adverse effects of NPS consumption were reported. The findings of this pilot study warrant further research to study AX as an oral adjuvant to support vaccine efficacy.

Vaccine Composition Formulated with a Novel Lactobacillus-Derived Exopolysaccharides Adjuvant Provided High Protection against Staphylococcus aureus

A vaccine that effectively targets methicillin-resistant Staphylococcus aureus (MRSA) is urgently needed, and has been the focus of studies by numerous research groups, but with limited success to date. Recently, our team found that exopolysaccharides derived from probiotic Lactobacilluscasei strain WXD030 as an adjuvant-formulated OVA could upregulate IFN-γ and IL-17 expression in CD4⁺ T cells. In this study, we developed a vaccine (termed rMntC-EPS) composed of S. aureus antigen MntC and Lactobacillus casei exopolysaccharides, which conferred high levels of protection against S. aureus infection. Methods: Six–eight-week-old female mice were vaccinated with purified rMntC-EPS30. The immune protection function of rMntC-EPS30 was assessed by the protective effect of rMntC-EPS30 to S. aureus-induced pulmonary and cutaneous infection in mice, bacterial loads and H&E in injury site, and ELISA for inflammation-related cytokines. The protective mechanism of rMntC-EPS30 was assessed by ELISA for IgG in serum, cytokines in the spleen and lungs of vaccinated mice. In addition, flow cytometry was used for analyzing cellular immune response induced by rMntC-EPS30. For confirmation of our findings, three kinds of mice were used in this study: IL-17A knockout mice, IFN-γ knockout mice and TCRγ/δ knockout mice. Results: rMntC-EPS30 conferred up to 90% protection against S. aureus pulmonary infection and significantly reduced the abscess size in the S. aureus cutaneous model, with clearance of the pathogen. The rMntC-EPS vaccine could induce superior humoral immunity as well as significantly increase IL-17A and IFN-γ production. In addition, we found that rMntC-EPS vaccination induced robust Th 17/γδ T 17 primary and recall responses. Interestingly, this protective effect was distinctly reduced in the IL-17A knockout mice but not in IFN-γ knockout mice. Moreover, in TCRγ/δ knockout mice, rMntC-EPS vaccination neither increased IL-17A secretion nor provided effective protection against S. aureus infection. Conclusions: These data demonstrated that the rMntC formulated with a novel Lactobacillus-derived Exopolysaccharides adjuvant provided high protection against Staphylococcus aureus. The rMntC-EPS vaccine induced γδ T cells and IL-17A might play substantial roles in anti-S. aureus immunity. Our findings provided direct evidence that rMntC-EPS vaccine is a promising candidate for future clinical application against S. aureus-induced pulmonary and cutaneous infection.

Exopolysaccharides from probiotic bacteria and their health potential

Exopolysaccharides (EPS) are extracellular macromolecules excreted as tightly bound capsule or loosely attached slime layer in microorganisms. They play most prominent role against desiccation, phagocytosis, cell recognition, phage attack, antibiotics or toxic compounds and osmotic stress. In the last few decades, natural polymers have gained much attention among scientific communities owing to their therapeutic potential. In particular the EPS retrieved from probiotic bacteria with varied carbohydrate compositions possess a plenty of beneficial properties. Different probiotic microbes have unique behavior in expressing their capability to display significant health promoting characteristics in the form of polysaccharides. In this new era of alternative medicines, these polysaccharides are considered as substitutes for synthetic drugs. The EPS finds applications in various fields like textiles, cosmetics, bioremediation, food and therapeutics. The present review is focused on sources, chemical composition, biosynthetic pathways of EPS and their biological potential. More attention has been given to the scientific investigations on antimicrobial, antitumor, anti-biofilm, antiviral, anti-inflammatory and immunomodulatory activities.

The effects of exopolysaccharides and exopolysaccharide-producing Lactobacillus on the intestinal microbiome of zebrafish (Danio rerio)

BACKGROUND

Numerous studies have reported the health-promoting effects of exopolysaccharides (EPSs) in in vitro models; however, a functional evaluation of EPSs will provide additional knowledge of EPS-microbe interactions by in vivo intestinal microbial model. In the present study, high-throughput amplicon sequencing, short-chain fatty acid (SCFAs) and intestinal inflammation evaluation were performed to explore the potential benefits of exopolysaccharides (EPSs) and EPS-producing Lactobacillus (HNUB20 group) using the healthy zebrafish (Danio rerio) model.

RESULTS

The results based on microbial taxonomic analysis revealed that the abundance of four genera, Ochrobactrum, Sediminibacterium, Sphingomonas and Sphingobium, were increased in the control group in comparison to HNUB20 group. Pelomonas spp. levels were significantly higher and that of the genera Lactobacillus and Brachybacterium were significantly decreased in EPS group compared with control group. PICRUSt based functional prediction of gut microbiota metabolic pathways indicated that significantly lower abundance was found for transcription, and membrane transport, whereas folding, sorting and degradation and energy metabolism had significantly higher abundance after HNUB20 treatment. Two metabolic pathways, including metabolism and endocrine functions, were more abundant in the EPS group than control group. Similar to the HNUB20 group, transcription was also decreased in the EPS group compared with the control group. However, SCFAs and immune indexes indicated EPS and HNUB20 performed limited efficacy in the healthy zebrafish.

CONCLUSIONS

The present intestinal microbial model-based study indicated that EPSs and high-yield EPS-producing Lactobacillus can shake the structure of intestinal microbiota, but cannot change SCFAs presence and intestinal inflammation.

Postbiotics-A Step Beyond Pre- and Probiotics

As an imbalance in the intestinal microbiota can lead to the development of several diseases (e.g., type 1 diabetes, cancer, among others), the use of prebiotics, probiotics, and postbiotics to alter the gut microbiome has attracted recent interest. Postbiotics include any substance released by or produced through the metabolic activity of the microorganism, which exerts a beneficial effect on the host, directly or indirectly. As postbiotics do not contain live microorganisms, the risks associated with their intake are minimized. Here, we provided a critical review of postbiotics described in the literature, including their mechanisms of action, clinical characteristics, and potential therapeutic applications. We detailed the pleiotropic effects of postbiotics, including their immunomodulatory, anti-inflammatory, antioxidant, and anti-cancer properties. Although the use of postbiotics is an attractive strategy for altering the microbiome, further study into its efficacy and safety is warranted.

Exopolysaccharides from Lactobacillus kiferi as adjuvant enhanced the immuno-protective against Staphylococcus aureus infection

Exopolysaccharides from lactic acid bacteria (LAB) have gained more attention due to their health benefits. Most research on LAB EPS focuses on antitumor and antioxidant activities. To our knowledge, the immunoadjuvant activity of LAB EPS has not been thoroughly studied. In this study, the EPS produced by Lactobacillus kiferi WXD029 were purified by ethanol precipitation and column chromatography fractionation. The molecular weight of the EPS was 3.423 × 10⁵ Da and was mainly composed of Glu, GlcN, and GalN in a molar ratio of 3.1:1:1. In vitro, EPS could significantly enhance the proliferation and phagocytic activity as well as induce the production of NO, TNF-α, IL-1β, and IL-6 in RAW264.7 cells. In vivo, the EPS adjuvant could increase the titers of S.aureus antigen-specific antibodies and markedly enhanced T cell proliferation. Notably, EPS adjuvant also induced a strong potential Th1, Th2 and Th17-cell mixture responses. Furthermore, immunization with S.aureus antigen plus EPS adjuvant induced a protective effect when compared with S.aureus antigen alone in murine bacteremia, pneumonia and mastitis model. Collectively, these results suggest that EPS derived from probiotic Lactobacillus kiferi strain is promising as an efficient adjuvant candidate for the prevention of S. aureus infections.

The Effects of Oral Rehmannia glutinosa Polysaccharide Administration on Immune Responses, Antioxidant Activity and Resistance Against Aeromonas hydrophila in the Common Carp, Cyprinus carpio L

The effects of the oral administration of Rehmannia glutinosa polysaccharide (RGP-1) on the immunoregulatory properties, antioxidant activity, and resistance against Aeromonas hydrophila in Cyprinus carpio L. were investigated. The purified RGP-1 (250, 500, and 1,000 μg/mL) was co-cultured with the head kidney cells of the common carp. The proliferation and phagocytosis activities of the head kidney cells, and the concentration of nitric oxide (NO) and cytokines in the culture medium were determined. Next, 300 common carps (47.66 ± 0.43 g) were randomly divided into five groups; the two control groups (negative and positive) were administered sterile PBS and the three treatment groups were administered different concentrations of RGP-1 (250, 500, and 1,000 μg/mL) for seven days. Subsequently, the positive and treatment groups were infected with A. hydrophila, and the negative group was administered sterile PBS for 24 h. The concentration of NO, cytokines, lysozyme (LZM), and alkaline phosphatase (AKP) in serum, the total antioxidant capacity (T-AOC), the levels of malonaldehyde (MDA) and glutathione (GSH), and the total activities of superoxide dismutase (T-SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) in the hepatopancreas of the common carp were tested. We observed that RGP-1 could significantly enhance the proliferation and phagocytosis activities (P < 0.05), besides inducing the production of NO, pro-inflammatory cytokines (TNF-α, IL-1β, IL-6, IL-12) and anti-inflammatory cytokines (IL-10, TGF-β) (P < 0.05) in vitro. The in vivo experimental results revealed that RGP-1 significantly enhanced NO production, protein levels of pro-inflammatory cytokines (TNF-α, IL-1β, IL-6, IL-12), LZM and AKP activities, and the antioxidant content (T-AOC, SOD, CAT, GSH, GSH-Px, and MDA) compared to that observed in the negative group prior to A. hydrophila infection (P < 0.05). NO, pro-inflammatory cytokines, LZM and AKP activities were significantly lower than that in the positive group after infection (P < 0.05). However, whether infected or not, the expression of anti-inflammatory cytokines (IL-10, TGF-β) increased significantly in the RGP-1-treated groups (P < 0.05). Therefore, the results suggested that RGP-1 could enhance the non-specific immunity, antioxidant activity and anti-A. hydrophila activity of the common carp, and could be used as a safe and effective feed additive in aquaculture.

Effects of an exopolysaccharide from Lactococcus lactis Z-2 on innate immune response, antioxidant activity, and disease resistance against Aeromonas hydrophila in Cyprinus carpio L

Microbial exopolysaccharides (EPS) from Lactococcus have been found to have an important role in the probiotic activity of this bacterium; however, the immunomodulatory and antioxidant activities have not been fully explored in aquaculture. In the present study, we investigated EPS-2 from Lactococcus lactis Z-2, isolated from healthy common carp, for its immunomodulatory and antioxidant effects and disease resistance against Aeromonas hydrophila in Cyprinus carpio L. We found that the molecular weight of EPS-2 was 18.65 KDa. The monosaccharide composition of this polymer was rhamnose, xylose, mannose, glucose, and galactose at a molar percentage of 13.3%, 14.1%, 18.5%, 27.4%, and 26.7%, respectively. EPS-2 treatment could modulate the immune responses in vitro and in vivo. In vitro tests showed that EPS-2 could significantly enhance the proliferation and phagocytosis activities (P < 0.05) as well as induce the production of nitic oxide (NO), pro-inflammatory cytokines (TNF-α, IL-1β, IL-6), and anti-inflammatory cytokines (IL-10, TGF-β) (P < 0.05) in head kidney cells. When the fish were gavaged with three different concentrations of EPS-2 (250, 500, 1000 μg/mL) for 7 days and infected with A. hydrophila, different expression patterns of the NO, cytokines, lysozyme (LZM), and alkaline phosphatase (AKP) in the serum and of antioxidants (T-AOC, SOD, CAT, GSH, GSH-Px and MDA) in hepatopancreas were observed. Before infection with A. hydrophila, EPS-2 supplementation significantly up-regulated the NO production, protein levels of pro-inflammatory cytokines (TNF-α, IL-1β, IL-6), LZM and AKP activities, and levels of antioxidant molecules compared to those in the negative (G1) group (P < 0.05), whereas levels of NO and pro-inflammatory cytokines and LZM and AKP activities were significantly lower than those in the positive (G2) group after infection (P < 0.05). However, whether infected or not, the expression levels of anti-inflammatory cytokines (IL-10, TGF-β) were significantly increased in the EPS-2 treatment groups (P < 0.05). These results indicate that EPS-2 has immunomodulatory and antioxidant effects on common carp, both in vitro and/or in vivo, and can be applied as a common carp feed supplement to enhance fish immunity and disease resistance against A. hydrophila.