Immunoregulatory Effects Triggered by Lactic Acid Bacteria Exopolysaccharides: New Insights into Molecular Interactions with Host Cells

Transcriptome Analysis Reveals the Role of Sucrose in the Production of Latilactobacillus sakei L3 Exopolysaccharide

Latilactobacillus (L.) sakei is a species of lactic acid bacteria (LAB) mostly studied according to its application in food fermentation. Previously, L. sakei L3 was isolated by our laboratory and possessed the capability of high exopolysaccharide (EPS) yield during sucrose-added fermentation. However, the understanding of sucrose promoting EPS production is still limited. Here, we analyzed the growth characteristics of L. sakei L3 and alterations of its transcriptional profiles during sucrose-added fermentation. The results showed that L. sakei L3 could survive between pH 4.0 and pH 9.0, tolerant to NaCl (<10%, w/v) and urea (<6%, w/v). Meanwhile, transcriptomic analysis showed that a total of 426 differentially expressed genes and eight non-coding RNAs were identified. Genes associated with sucrose metabolism were significantly induced, so L. sakei L3 increased the utilization of sucrose to produce EPS, while genes related to uridine monophosphate (UMP), fatty acids and folate synthetic pathways were significantly inhibited, indicating that L. sakei L3 decreased self-growth, substance and energy metabolism to satisfy EPS production. Overall, transcriptome analysis provided valuable insights into the mechanisms by which L. sakei L3 utilizes sucrose for EPS biosynthesis. The study provided a theoretical foundation for the further application of functional EPS in the food industry.

Bifidobacterium exopolysaccharides: new insights into engineering strategies, physicochemical functions, and immunomodulatory effects on host health

Bifidobacteria are a prominent type of bacteria that have garnered significant research attention for their exceptional probiotic properties and capacity to produce exopolysaccharides (EPSs). These compounds exhibit diverse physical, chemical, and biological characteristics, prompting numerous investigations into their potential applications. Researchers have noted their beneficial effects as immune modulators within the host's body across various industries. Extensive research has been conducted on the immunomodulatory effects of bifidobacteria-derived EPSs, with emerging engineering strategies aimed at enhancing their immune-modulating capabilities. Understanding the structure, physicochemical properties, and biological activities of these compounds is crucial for their effective utilization across different industries. Our review encompassed numerous studies exploring Bifidobacterium and its metabolites, including EPSs, across various sectors, drawing from diverse databases. The distinctive properties of EPSs have spurred investigations into their applications, revealing their potential to bolster the immune system, combat inflammation, and treat various ailments. Additionally, these compounds possess antioxidant and antimicrobial properties, making them suitable for incorporation into a range of products spanning food, health, and medicine.

Genomic and transcriptomic analysis of genes involved in exopolysaccharide biosynthesis by Streptococcus thermophilus IMAU20561 grown on different sources of nitrogen

Exopolysaccharides (EPSs), which are produced by lactic acid bacteria, have been found to improve the texture and functionality of fermented dairy products. In a previous study, four nitrogen sources were identified as affecting the yield, molecular weight and structure of EPSs produced by Streptococcus thermophilus IMAU20561 in M17 medium. In this genomic and transcriptomics study, a novel eps gene cluster responsible for assembly of repeating units of EPS is reported. This eps cluster (22.3 kb), consisting of 24 open reading frames, is located in the chromosomal DNA. To explore the biosynthetic mechanisms in EPS, we completed RNA-seq analysis of S. thermophilus IMAU20561 grown in four different nitrogen sources for 5 h (log phase) or 10 h (stationary phase). GO functional annotation showed that there was a significant enrichment of differentially expressed genes (DEGs) involved in: amino acid biosynthesis and metabolism; ribonucleotide biosynthesis and metabolism; IMP biosynthesis and metabolism; and phosphorus metabolism. KEGG functional annotation also indicated enrichment of DEGs involved in amino acid biosynthesis, glycolysis, phosphotransferase system, fructose, and mannose metabolism. Our findings provide a better understanding the genetic traits of S. thermophilus, the biosynthetic pathways needed for the production of EPS, and a theoretical basis for screening dairy starter cultures.

Characteristics of Lactococcus petauri GB97 lysate isolated from porcine feces and its in vitro and in vivo effects on inflammation, intestinal barrier function, and gut microbiota composition in mice

IMPORTANCE

Weaning is a crucial step in piglet management to improve pork production. During the weaning phase, disruption of epithelial barrier function and intestinal inflammation can lead to decreased absorption of nutrients and diarrhea. Therefore, maintaining a healthy intestine, epithelial barrier function, and gut microbiota composition in this crucial phase is strategic for optimal weaning in pigs. We isolated a lysate of Lactococcus petauri GB97 (LPL97) from healthy porcine feces and evaluated its anti-inflammatory activities, barrier integrity, and gut microbial changes in LPS-induced murine macrophages and DSS-induced colitis mice. We found that LPL97 regulated the immune response by downregulating the TLR4/NF-κB/MAPK signaling pathway both in vitro and in vivo. Furthermore, LPL97 alleviated the disruption of intestinal epithelial integrity and gut microbiota dysbiosis in colitis mice. This study indicates that LPL97 has the potential to be developed as an alternative feed additive to antibiotics for the swine industry.

A Ropy Exopolysaccharide-Producing Strain Bifidobacterium pseudocatenulatum Bi-OTA128 Alleviates Dextran Sulfate Sodium-Induced Colitis in Mice

Inflammatory bowel disease (IBD) is a chronic disease associated with overactive inflammation and gut dysbiosis. Owing to the beneficial effects of bifidobacteria on IBD treatment, this study aimed to investigate the anti-inflammation effects of an exopolysaccharide (EPS)-producing strain Bifidobacterium pseudocatenulatum Bi-OTA128 through a dextran sulfate sodium (DSS)-induced colitis mice model. B. pseudocatenulatum treatment improved DSS-induced colitis symptoms and maintained intestinal barrier integrity by up-regulating MUC2 and tight junctions' expression. The oxidative stress was reduced after B. pseudocatenulatum treatment by increasing the antioxidant enzymes of SOD, CAT, and GSH-Px in colon tissues. Moreover, the overactive inflammatory responses were also inhibited by decreasing the pro-inflammatory cytokines of TNF-α, IL-1β, and IL-6, but increasing the anti-inflammatory cytokine of IL-10. The EPS-producing strain Bi-OTA128 showed better effects than that of a non-EPS-producing stain BLYR01-7 in modulating DSS-induced gut dysbiosis. The Bi-OTA128 treatment increased the relative abundance of beneficial bacteria Bifidobacterium and decreased the maleficent bacteria Escherichia-Shigella, Enterorhabuds, Enterobacter, and Osillibacter associated with intestinal inflammation. Notably, the genera Clostridium sensu stricto were only enriched in Bi-OTA128-treated mice, which could degrade polysaccharides to produce acetic acid and butyrate in the gut. This finding demonstrated a cross-feeding effect induced by the EPS-producing strain in gut microbiota. Collectively, these results highlighted the anti-inflammatory effects of the EPS-producing strain B. pseudocatenulatum Bi-OTA128 on DSS-induced colitis, which could be used as a candidate probiotic supporting recovery from ongoing colitis.

Extracellular polysaccharide of Lactobacillus plantarum enhance immune efficacy of oprH gene recombinant subunit vaccine from Pseudomonas aeruginosa

To evaluate the immune enhancement effect of the extracellular polysaccharide of Lactobacillus plantarum on oprH recombinant subunit vaccine from Pseudomonas aeruginosa, a recombinant subunit vaccine of oprH (rOprH vaccine) was developed. The EP-rOprH vaccine was prepared with the extracellular polysaccharide of L. plantarum as an adjuvant. Mice were vaccinated with the rOprH and EP-rOprH vaccines, and the outer membrane protein (OMP) and inactivated vaccines were used as controls. The levels of serum antibody, interferon-γ (IFN-γ), interleukin (IL-2), and IL-4 were determined after vaccination. Finally, the protective efficacy of the vaccine was evaluated after challenge with virulent P. aeruginosa. Following vaccination, the serum antibody levels were significantly higher in mice vaccinated with the EP-rOprH vaccine than in those vaccinated with the rOprH vaccine (P<0.05). Moreover, the serum antibody levels detected in the EP-rOprH vaccine group were similar to those detected in the OMP vaccine group when P. aeruginosa suspension was used as the coating antigen. However, the levels in the EP-rOprH vaccine group were higher than those in the OMP vaccine and inactivated vaccine groups when the purified rOprH protein was used as the coating antigen (P<0.05). The level of IFN-γ, IL-2, and IL-4 in mice vaccinated with the EP-rOprH vaccine was significantly higher than that in mice vaccinated with the rOprH vaccine (P<0.05) and comparable to that in mice vaccinated with the OMP vaccine. The protective rates were 65%, 80%, 80%, and 95% with the rOprH, EP-rOprH, OMP, and inactivated vaccines, respectively. Thus, the extracellular polysaccharide of L. plantarum significantly enhanced the immune response and protection provided by the recombinant subunit vaccine of oprH.

The Immunomodulatory Effect of β-Glucan Depends on the Composition of the Gut Microbiota

This study aimed to elucidate the relationship between the immunomodulatory effects of β-glucan and the composition of gut microbiota in mice. The mice were fed a diet containing β-glucan for 3 weeks, and feces, blood, and tissues were then collected to analyze the immunomodulatory effect and gut microbiota composition. Based on the results of the analysis of the expression level of immune-associated proteins, the high immunomodulatory effect group (HIE) and low immunomodulatory effect group (LIE) were categorized. Before the β-glucan diet, the proportions of the phylum Bacteroidota, family Muribaculaceae, and family Lactobacillaceae were significantly higher in HIE than in LIE. Furthermore, the genus Akkermansia was absent before the β-glucan diet and increased after β-glucan diet. These microbes had the ability to metabolize β-glucan or were beneficial to health. In conclusion, our findings demonstrate that variation in the composition of gut microbiota among individuals can result in varying expressions of β-glucan functionality. This outcome supports the notion that β-glucan may be metabolized through diverse pathways by gut microbes originally possessed by mice, subsequently producing various metabolites, such as short-chain fatty acids. Alternatively, the viscosity of the intestinal mucosa could be enhanced by β-glucan, potentially promoting the growth of certain bacteria (e.g., the genus Akkermansia). This study provides insights into the intricate interplay between β-glucan, gut microbiota, and immunomodulation.

Understanding Age-Related Longitudinal Dynamics in Abundance and Diversity of Dominant Culturable Gut Lactic Acid Bacteria in Pastured Goats

Understanding gut lactic acid bacteria (LAB) in healthy hosts is an important first step in selecting potential probiotic species. To understand the dynamics of LAB in healthy goats, a cohort of thirty-seven healthy new-born goat kids was studied over a ten-month period. Total LAB was quantified using SYBR green qPCR. Seven hundred LAB isolates were characterized using microscopy, M13 RAPD genotyping and 16S rDNA sequencing. The highest and lowest LAB counts were detected at one week and ten months of age, respectively. Diverse LAB species were detected, whose identity and prevalence varied with age. The main isolates belonged to Limosilactobacillus reuteri, Limosilactibacillus fermentum, Lactobacillus johnsonni, Ligilactobacillus murinus, Ligilactobacillus salivarius, Limosilactobacillus mucosae, Lactiplantibacillus plantarum, Ligilactobacillus agilis, Lactobacillus acidophilus/amyolovolus, Pediococcus spp. and Enterococcus spp. Uniquely, L. reuteri and Pediococcus spp. were most common in pre- and peri-weaned goats, while Lactobacillus mucosae and Enterococcus spp. were predominant in goats one month and older. Based on RAPD genotyping, L. reuteri had the highest genotypic diversity, with age being a factor on the genotypes detected. This data may be relevant in the selection of age-specific probiotics for goats. The findings may also have broader implications by highlighting age as a factor for consideration in probiotic bacteria selection in other animal hosts.

Microbial exopolysaccharides in the biomedical and pharmaceutical industries

The most significant and renewable class of polymeric materials are extracellular exopolysaccharides (EPSs) produced by microorganisms. Because of their diverse chemical and structural makeup, EPSs play a variety of functions in a variety of industries, including the agricultural industry, dairy industry, biofilms, cosmetics, and others, demonstrating their biotechnological significance. EPSs are typically utilized in high-value applications, and current research has focused heavily on them because of their biocompatibility, biodegradability, and compatibility with both people and the environment. Due to their high production costs, only a few microbial EPSs have been commercially successful. The emergence of financial barriers and the growing significance of microbial EPSs in industrial and medical biotechnology has increased interest in exopolysaccharides. Since exopolysaccharides can be altered in a variety of ways, their use is expected to increase across a wide range of industries in the coming years. This review introduces some significant EPSs and their composites while concentrating on their biomedical uses.

Ex Vivo Immunomodulatory Effects of Lactobacillus-, Lacticaseibacillus-, and Bifidobacterium-Containing Synbiotics on Human Peripheral Blood Mononuclear Cells and Monocyte-Derived Dendritic Cells in the Context of Grass Pollen Allergy

Sensing of the intestinal microbiota by the host immune system is important to induce protective immune responses. Hence, modification of the gut microbiota might be able to prevent or treat allergies, mediated by proinflammatory Th2 immune responses. The aim was to investigate the ex vivo immunomodulatory effects of the synbiotics Pollagen® and Kallergen®, containing the probiotic bacterial strains Lactobacillus, Lacticaseibacillus and Bifidobacterium, in the context of grass pollen allergy. Peripheral blood mononuclear cells (PBMCs) from grass pollen-allergic patients and healthy controls were stimulated with grass pollen extract (GPE) and synbiotics and Gata3 expression and cytokine secretion analyzed. Monocyte-derived dendritic cells (MoDCs) cells were matured in the presence of GPE and synbiotics, co-cultured with autologous naïve T cells and maturation markers and cytokine secretion analyzed. GPE stimulation of PBMCs from grass pollen-allergic patients resulted in a significant higher production of the Th2 cytokines IL-4, IL-5, IL-9 and IL-13 compared to healthy controls. Gata3+CD4+ T cell induction was independent of the allergic status. The synbiotics promoted IL-10 and IFN-γ secretion and downregulated the GPE-induced Th2-like phenotype. Co-culturing naïve T cells with MoDCs, matured in the presence of GPE and synbiotics, shifted the GPE-induced Th2 cytokine release towards Th1-Th17-promoting conditions in allergic subjects. The investigated synbiotics are effective in downregulating the GPE-induced Th2 immune response in PBMCs from grass pollen-allergic patients as well as in autologous MoDC-T cell stimulation assays. In addition to increased IL-10 release, the data indicates a shift from a Th2- to a more Th1- and Th17-like phenotype.

Hacking the Immune Response to Solid Tumors: Harnessing the Anti-Cancer Capacities of Oncolytic Bacteria

Oncolytic bacteria are a classification of bacteria with a natural ability to specifically target solid tumors and, in the process, stimulate a potent immune response. Currently, these include species of Klebsiella, Listeria, Mycobacteria, Streptococcus/Serratia (Coley's Toxin), Proteus, Salmonella, and Clostridium. Advancements in techniques and methodology, including genetic engineering, create opportunities to "hijack" typical host-pathogen interactions and subsequently harness oncolytic capacities. Engineering, sometimes termed "domestication", of oncolytic bacterial species is especially beneficial when solid tumors are inaccessible or metastasize early in development. This review examines reported oncolytic bacteria-host immune interactions and details the known mechanisms of these interactions to the protein level. A synopsis of the presented membrane surface molecules that elicit particularly promising oncolytic capacities is paired with the stimulated localized and systemic immunogenic effects. In addition, oncolytic bacterial progression toward clinical translation through engineering efforts are discussed, with thorough attention given to strains that have accomplished Phase III clinical trial initiation. In addition to therapeutic mitigation after the tumor has formed, some bacterial species, referred to as "prophylactic", may even be able to prevent or "derail" tumor formation through anti-inflammatory capabilities. These promising species and their particularly favorable characteristics are summarized as well. A complete understanding of the bacteria-host interaction will likely be necessary to assess anti-cancer capacities and unlock the full cancer therapeutic potential of oncolytic bacteria.

Partial Characterization and Immunomodulatory Effects of Exopolysaccharides from Streptococcus thermophilus SBC8781 during Soy Milk and Cow Milk Fermentation

The immunomodulatory properties of exopolysaccharides (EPSs) produced by Streptococcus thermophilus have not been explored in depth. In addition, there are no comparative studies of the functional properties of EPSs produced by streptococci in different food matrices. In this work, EPSs from S. thermophilus SBC8781 were isolated after soy milk (EPS-s) or cow milk (EPS-m) fermentation, identified, and characterized in their abilities to modulate immunity in porcine intestinal epithelial cells. Fresh soy milk and cow milk were inoculated with S. thermophilus SBC8781 (7 log CFU/mL) and incubated at 37 °C for 24 h. The extraction of EPSs was performed by the ethanol precipitation method. Analytical techniques, including NMR, UV-vis spectroscopy, and chromatography, identified and characterized both biopolymer samples as polysaccharides with high purity levels and similar Mw. EPS-s and EPS-m had heteropolysaccharide structures formed by galactose, glucose, rhamnose, ribose, and mannose, although with different monomer proportions. On the other hand, EPS-s had higher quantities of acidic polymer than EPS-m. The biopolymer production of the SBC8781 strain from the vegetable culture broth was 200-240 mg/L, which was higher than that produced in milk, which reached concentrations of 50-70 mg/L. For immunomodulatory assays, intestinal epithelial cells were stimulated with 100 µg/mL of EPS-s or EPS-m for 48 h and then stimulated with the Toll-like receptor 3 agonist poly(I:C). EPS-s significantly reduced the expression of IL-6, IFN-β, IL-8, and MCP-1 and increased the negative regulator A20 in intestinal epithelial cells. Similarly, EPS-m induced a significant reduction of IL-6 and IL-8 expressions, but its effect was less remarkable than that caused by EPS-s. Results indicate that the structure and the immunomodulatory activity of EPSs produced by the SBC8781 strain vary according to the fermentation substrate. Soy milk fermented with S. thermophilus SBC8781 could be a new immunomodulatory functional food, which should be further evaluated in preclinical trials.

Lactic acid bacteria-derived exopolysaccharide: Formation, immunomodulatory ability, health effects, and structure-function relationship

Exopolysaccharides (EPSs) synthesized by lactic acid bacteria (LAB) have implications for host health and act as food ingredients. Due to the variability of LAB-EPS (lactic acid bacteria-derived exopolysaccharide) gene clusters, especially the glycosyltransferase genes that determine monosaccharide composition, the structure of EPS is very rich. EPSs are synthesized by LAB through the extracellular synthesis pathway and the Wzx/Wzy-dependent pathway. LAB-EPS has a strong immunomodulatory ability. The EPSs produced by different genera of LAB, especially Lactobacillus, Leuconostoc, and Streptococcus, have different immunomodulatory abilities because of their specific structures. LAB-EPS possesses other health effects, including antitumor, antioxidant, intestinal barrier repair, antimicrobial, antiviral, and cholesterol-lowering activities. The bioactivities of LAB-EPS are tightly related to their structures such us monosaccharide composition, glycosidic bonds, and molecular weight (MW). For the excellent physicochemical property, LAB-EPS acts as product improvers in dairy, bakery food, and meat in terms of stability, emulsification, thickening, and gelling. We systematically summarize the detailed process of EPS from synthesis to application, with emphasis on physiological mechanisms of EPS, and specific structure-function relationship, which provides theoretical support for the potential commercial value in the pharmaceutical, chemical, food, and cosmetic industries.

Probiotics and novel probiotic delivery systems

Necrotizing enterocolitis (NEC) is an infectious and inflammatory intestinal disease that is the most common surgical emergency in the premature patient population. Although the etiology of the disease is multifactorial, intestinal dysbiosis is a hallmark of this disease. Based on this, probiotics may play a therapeutic role in NEC by introducing beneficial bacteria with immunomodulating, antimicrobial, and anti-inflammatory functions into the gastrointestinal tract. Currently, there is no Food and Drug Administration (FDA)-approved probiotic for the prevention and treatment of NEC. All probiotic clinical studies to date have administered the bacteria in their planktonic (free-living) state. This review will discuss established probiotic delivery systems including planktonic probiotics, prebiotics, and synbiotics, as well as novel probiotic delivery systems such as biofilm-based and designer probiotics. We will also shed light on whether or not probiotic efficacy is influenced by administration with breast milk. Finally, we will consider the challenges associated with developing an FDA-approved probiotic for NEC.

Beneficial insights into postbiotics against colorectal cancer

Colorectal cancer (CRC) is one of the most prevalent and life-threatening cancer types with limited therapeutic options worldwide. Gut microbiota has been recognized as the pivotal determinant in maintaining gastrointestinal (GI) tract homeostasis, while dysbiosis of gut microbiota contributes to CRC development. Recently, the beneficial role of postbiotics, a new concept in describing microorganism derived substances, in CRC has been uncovered by various studies. However, a comprehensive characterization of the molecular identity, mechanism of action, or routes of administration of postbiotics, particularly their role in CRC, is still lacking. In this review, we outline the current state of research toward the beneficial effects of gut microbiota derived postbiotics against CRC, which will represent the key elements of future precision-medicine approaches in the development of novel therapeutic strategies targeting gut microbiota to improve treatment outcomes in CRC.

Exopolysaccharides from lactic acid bacteria, as an alternative to antibiotics, on regulation of intestinal health and the immune system

Over-use or misuse of antibiotics in livestock and poultry production contributes to the rising threat of antibiotic resistance in animals and has negative ecological effects. Exopolysaccharides from lactic acid bacteria (LAB-EPS) are a class of biological macromolecules which are secreted by lactic acid bacteria to the outside of the cell wall during their growth and metabolism. Numerous studies demonstrated that LAB-EPS have anti-inflammatory and antimicrobial activities and are able to regulate intestinal health and the immune system in livestock. They are biodegradable, nontoxic and bio-compatible, which are considered as ideal alternatives to antibiotics. This review aims to discuss and summarize recent research findings of LAB-EPS on regulation of intestinal health and the immune system in animals, and thus provide scientific justification for commercial applications of LAB-EPS in livestock.

Exopolysaccharide-producing Lacticaseibacillus paracasei strains isolated from kefir as starter for functional dairy products

Exopolysaccharides (EPS) produced by lactic acid bacteria are molecules of great interest for the dairy food industry. Lacticaseibacillus paracasei CIDCA 8339, CIDCA 83123, and CIDCA 83124 are potentially probiotic strains isolated from kefir grains whose EPS-production on MRS broth is dependent on incubation temperature. The aim of the present work is to evaluate the effect of fermentation temperature on the characteristics of EPS produced in milk by L. paracasei strains and the consequent impact on the rheological properties of the fermented products. Additionally, the protective effect of these EPS against Salmonella infection was evaluated in vitro. Acid gels with each strain were obtained by milk fermentation at 20°C, 30°C, and 37°C evidencing for all the strains a reduction in growth and acidification rate at lower temperature. Lacticaseibacillus paracasei CIDCA 83123 showed low fermentation rate at all temperatures requiring between 3 and 8 days to obtain acids gels, whereas CIDCA 8339 and 83124 needed between 24 and 48 h even when the temperature was 20°C. Fermentation temperature led to changes in crude EPS characteristics of the three strains, observing an increase in the relative amount of the high molecular weight fraction when the fermentation temperature diminished. Additionally, EPS₈₃₁₂₄ and EPS₈₃₁₂₃ presented modifications in monosaccharide composition, with a reduction of rhamnose and an increase of amino-sugars as temperature rise. These changes in the structure of EPS₈₃₁₂₄ resulted in an increase of the apparent viscosity of milks fermented at 20°C (223 mPa.s) and 30°C (217 mPa.s) with respect to acid gels obtained at 37°C (167 mPa.s). In order to deepen the knowledge on EPS characteristics, monosaccharide composition of low and high molecular weight EPS fractions were evaluated. Finally, it was evidenced that the preincubation of intestinal epithelial cells Caco-2/TC-7 with EPS₈₃₃₉ and EPS₈₃₁₂₄ partially inhibit the association and invasion of Salmonella. In light of these results, it can be concluded that the selection of the EPS-producing strain along with the appropriate fermentation conditions could be an interesting strategy to improve the technological properties of these L. paracasei fermented milks with potential protective effects against intestinal pathogens.

Immunomodulatory Effect of Lactobacillus reuteri (Limosilactobacillus reuteri) and Its Exopolysaccharides Investigated on Epithelial Cell Line IPEC-J2 Challenged with Salmonella Typhimurium

The gastrointestinal tract is the largest and most complex component of the immune system. Each component influences the production and regulation of cytokines secreted by intestinal epithelial cells. The aim of this study was to see how the probiotic strain Limosilactobacillus reuteri L26 and its exopolysaccharide (EPS) affect porcine intestinal-epithelial cells IPEC-J2 infected with Salmonella Typhimurium. The results revealed that Salmonella infection up-regulated all studied pro-inflammatory cytokines such as TNF-α, IL-8, IL-6 and TLR4, TLR5 signaling pathways, while decreasing the expression of TGF-β. An immunosuppressive activity was found in EPS-treated wells, since the transcriptional levels of the studied pro-inflammatory cytokines were not increased, and the pretreatment with EPS was even able to attenuate up-regulated pro-inflammatory genes induced by Salmonella infection. However, there was a significant increase in the expression of mRNA levels of IL-8 and TNF-α in L26-treated cells, although this up-regulation was suppressed in the case of pretreatment. The immunoregulatory function of L. reuteri was also confirmed by the increased level of mRNA expression for TGF-β, a known immunosuppressive mediator. The most relevant finding of this ex vivo study was a case of immunity modulation, where the probiotic strain L. reuteri stimulated the innate immune-cell response which displayed both anti- and pro-inflammatory activities, and modulated the expression of TLRs in the IPEC-J2 cell line. Our findings also revealed that the pretreatment of cells with either EPS or live lactobacilli prior to infection has a suppressive effect on the inflammatory response induced by Salmonella Typhimurium.

Biofilm-based delivery approaches and specific enrichment strategies of probiotics in the human gut

The use of probiotics has been one of the effective strategies to restructure perturbed human gut microbiota following a disease or metabolic disorder. One of the biggest challenges associated with the use of probiotic-based gut modulation strategies is to keep the probiotic cells viable and stable during the gastrointestinal transit. Biofilm-based probiotics delivery approaches have emerged as fascinating modes of probiotic delivery in which probiotics show significantly greater tolerance and biotherapeutic potential, and interestingly probiotic biofilms can be developed on food-grade surfaces too, which is ideal for the growth and proliferation of bacterial cells for incorporation into food matrices. In addition, biofilms can be further encapsulated with food-grade materials or with bacterial self-produced biofilms. This review presents a newly emerging and unprecedently discussed techniques for the safe delivery of probiotics based on biofilms and further discusses newly emerging prebiotic materials which target specific gut microbiota groups for growth and proliferation.

Probiotic-Based Bacteriocin: Immunity Supplementation Against Viruses. An Updated Review

Viral infections are a major cause of severe, fatal diseases worldwide. Recently, these infections have increased due to demanding contextual circumstances, such as environmental changes, increased migration of people and product distribution, rapid demographic changes, and outbreaks of novel viruses, including the COVID-19 outbreak. Internal variables that influence viral immunity have received attention along with these external causes to avert such novel viral outbreaks. The gastrointestinal microbiome (GIM), particularly the present probiotics, plays a vital role in the host immune system by mediating host protective immunity and acting as an immune regulator. Bacteriocins possess numerous health benefits and exhibit antagonistic activity against enteric pathogens and immunobiotics, thereby inhibiting viral infections. Moreover, disrupting the homeostasis of the GIM/host immune system negatively affects viral immunity. The interactions between bacteriocins and infectious viruses, particularly in COVID-19, through improved host immunity and physiology are complex and have not yet been studied, although several studies have proven that bacteriocins influence the outcomes of viral infections. However, the complex transmission to the affected sites and siRNA defense against nuclease digestion lead to challenging clinical trials. Additionally, bacteriocins are well known for their biofunctional properties and underlying mechanisms in the treatment of bacterial and fungal infections. However, few studies have shown the role of probiotics-derived bacteriocin against viral infections. Thus, based on the results of the previous studies, this review lays out a road map for future studies on bacteriocins for treating viral infections.

Recent advances in antiviral effects of probiotics: potential mechanism study in prevention and treatment of SARS-CoV-2

SARS-CoV-2 is responsible for coronavirus disease 2019 (COVID-19), progressively extended worldwide countries on an epidemic scale. Along with all the drug treatments suggested to date, currently, there are no approved management protocols and treatment regimens for SARS-CoV-2. The unavailability of optimal medication and effective vaccines against SARS-CoV-2 indicates the requirement for alternative therapies. Probiotics are living organisms that deliberate beneficial effects on the host when used sufficiently and in adequate amounts, and fermented food is their rich source. Probiotics affect viruses by antiviral mechanisms and reduce diarrhea and respiratory tract infection. At this point, we comprehensively evaluated the antiviral effects of probiotics and their mechanism with a particular focus on SARS-CoV-2. In this review, we suggested the conceptual and potential mechanisms of probiotics by which they could exhibit antiviral properties against SARS-CoV-2, according to the previous evidence concerning the mechanism of antiviral effects of probiotics. This study reviewed recent studies that speculate about the role of probiotics in the prevention of the SARS-CoV-2-induced cytokine storm through the mechanisms such as induction of anti-inflammatory cytokines (IL-10), downregulation of pro-inflammatory cytokines (TNF-α, IL-2, IL-6), inhibition of JAK signaling pathway, and act as HDAC inhibitor. Also, the recent clinical trials and their outcome have been reviewed.

Synergistic Hypolipidemic and Immunomodulatory Activity of Lactobacillus and Spirulina platensis

Hyperlipidemia is a significant risk factor for atherosclerosis and coronary heart disease (CHD). The aim of this study was to investigate hypolipidemic effects of Lactobacillus, Spirulina and their combination on Swiss albino mice fed a regular or high-cholesterol diet. Rosuvastatin was used as a reference drug The highest body weight, total cholesterol (TC), triglycerides (TG), low-density lipoprotein cholesterol LDL-C and the lowest high-density lipoprotein cholesterol were recorded in a positive control group (G5). Treatment with Lactobacillus or Spirulina or by their combination resulted in a significant decrease in body weight, TC, TG, LDL-C and significant increase in HDL-C (p < 0.05) in both mice fed a regular diet or high-cholesterol diet. The treatments induced a significant increase in Hb, MCHC and HCT levels in mice fed a regular diet (p < 0.05). They did not induce a significant effect on these parameters in mice fed a high-cholesterol diet, while treatment with standard rosuvastatin induced a significant decrease in these parameters (p < 0.05). The treatments induced a significant increase in the platelet count and WBC number in mice fed a regular diet p < 0.05), while they induced significant decrease in these parameters in mice fed a high-cholesterol diet p < 0.05. They also stimulated the innate immunity represented by both monocyte and neutrophil cells in mice fed a regular diet, while this immunity was reduced in mice fed a high-cholesterol diet. It also caused a marked reduction in inflammation and an improvement in the congestion of cardiac tissues, the aorta, and the spleen. The treatment of hyperlipidemic mice with combination of Lactobacillus and Spirulina gave similar results to those obtained with treatment by rosuvastatin.

Gut commensal Limosilactobacillus reuteri induces atypical memory-like phenotype in human dendritic cells in vitro

Memory-like responses in innate immune cells confer nonspecific protection against secondary exposures. A number of microbial agents have been found to induce enhanced or diminished recall responses in innate cells, however, studies investigating the ability of probiotic bacteria to trigger such effects are lacking. Here, we show that priming of human monocytes with a secretome from the gut probiotic bacterium Limosilactobacillus (L.) reuteri induces a mixed secondary response phenotype in monocyte-derived dendritic cells (mo-DCs), with a strong IL-6 and IL-1β response but low TNFα, IL-23 and IL-27 secretion. Instead, blood DC priming with L. reuteri-secretome resembles a tolerant state upon secondary exposure. A similar pattern was found in conventional and gut-like (retinoic acid exposed) DCs, although retinoic acid hampered TNFα and IL-6 production and enrichment of histone modifications in L. reuteri-secretome primed mo-DC cultures. Further, we show that the memory-like phenotype of mo-DCs, induced by priming stimuli, is important for subsequent T helper (Th) cell differentiation pathways and might determine the inflammatory nature of Th cells. We also show enhanced recall responses characterized by robust inflammatory cytokines and lactate production in the gut-like mo-DCs derived from β-glucan primed monocytes. Such responses were accompanied with enriched histone modifications at the promoter of genes associated with a trained phenotype in myeloid cells. Altogether, we demonstrate that a gut commensal-derived secretome prompts recall responses in human DCs which differ from that induced by classical training agents such as β-glucan. Our results could be beneficial for future therapeutic interventions where T cell responses are needed to be modulated.

Biological Functions of Exopolysaccharides from Lactic Acid Bacteria and Their Potential Benefits for Humans and Farmed Animals

Lactic acid bacteria (LAB) synthesize exopolysaccharides (EPS), which are structurally diverse biopolymers with a broad range of technological properties and bioactivities. There is scientific evidence that these polymers have health-promoting properties. Most commercialized probiotic microorganisms for consumption by humans and farmed animals are LAB and some of them are EPS-producers indicating that some of their beneficial properties could be due to these polymers. Probiotic LAB are currently used to improve human health and for the prevention and treatment of specific pathologic conditions. They are also used in food-producing animal husbandry, mainly due to their abilities to promote growth and inhibit pathogens via different mechanisms, among which the production of EPS could be involved. Thus, the aim of this review is to discuss the current knowledge of the characteristics, usage and biological role of EPS from LAB, as well as their postbiotic action in humans and animals, and to predict the future contribution that they could have on the diet of food animals to improve productivity, animal health status and impact on public health.

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.

Rotavirus Interactions With Host Intestinal Epithelial Cells

Rotavirus (RV) is the foremost enteric pathogen associated with severe diarrheal illness in young children (<5years) and animals worldwide. RV primarily infects mature enterocytes in the intestinal epithelium causing villus atrophy, enhanced epithelial cell turnover and apoptosis. Intestinal epithelial cells (IECs) being the first physical barrier against RV infection employs a range of innate immune strategies to counteract RVs invasion, including mucus production, toll-like receptor signaling and cytokine/chemokine production. Conversely, RVs have evolved numerous mechanisms to escape/subvert host immunity, seizing translation machinery of the host for effective replication and transmission. RV cell entry process involve penetration through the outer mucus layer, interaction with cell surface molecules and intestinal microbiota before reaching the IECs. For successful cell attachment and entry, RVs use sialic acid, histo-blood group antigens, heat shock cognate protein 70 and cell-surface integrins as attachment factors and/or (co)-receptors. In this review, a comprehensive summary of the existing knowledge of mechanisms underlying RV-IECs interactions, including the role of gut microbiota, during RV infection is presented. Understanding these mechanisms is imperative for developing efficacious strategies to control RV infections, including development of antiviral therapies and vaccines that target specific immune system antagonists within IECs.

Immunomodulation Potential of Probiotics: A Novel Strategy for Improving Livestock Health, Immunity, and Productivity

Over the past decade, the use of probiotics as feed supplements in animal production has increased considerably due to the ban on antibiotic growth promoters in livestock. This review provides an overview of the current situation, limitation, and prospects for probiotic formulations applied to livestock. Recently, the use of probiotics in livestock has been suggested to significantly improve their health, immunity, growth performance, nutritional digestibility, and intestinal microbial balance. Furthermore, it was reported that the use of probiotics in animals was helpful in equilibrating their beneficial microbial population and microbial turnover via stimulating the host immune response through specific secretions and competitive exclusion of potentially pathogenic bacteria in the digestive tract. Recently, there has been great interest in the understanding of probiotics targeted diet and its ability to compete with harmful microbes and acquire their niches. Therefore, the present review explores the most commonly used probiotic formulations in livestock feed and their effect on animal health. In summary, this article provides an in-depth knowledge about the formulation of probiotics as a step toward a better alternative to antibiotic healthy growth strategies.

Soymilk-fermented with Lactobacillus delbrueckii subsp. delbrueckii TUA4408L improves immune-health in pigs

Lactobacillus delbrueckii subsp. delbrueckii TUA4408L has the ability to grow and ferment soymilk and is able to modulate the innate immune response of intestinal epithelial cells in vitro. These two properties prompt us to evaluate whether the soymilk fermented with the TUA4408L strain can induce beneficial immunomodulatory effects in vivo. For this purpose, pigs were selected as a preclinical model. The studies performed here demonstrated that the L. delbrueckii subsp. delbrueckii TUA4408L-fermented soymilk (TUA4408L FSM) reduced blood markers of inflammation and differentially regulated the expression of inflammatory and regulatory cytokines in the intestinal mucosa. These immunological changes induced by the TUA4408L FSM were associated to an enhanced resistance to pathogenic Escherichia coli and an improved grow performance and meat quality of pigs. The experiments and analysis in our study indicate that the immunobiotic TUA4408L FSM could be an interesting non-dairy functional food to beneficially modulate the intestinal immune system, improve protection against pathogens and reduce inflammatory damage. The preclinical study carried out here in pigs could have a better correlation in humans, compared to a rodent model. However, the clinical relevance of these findings still needs to be confirmed by further research, for example, in controlled human challenge studies.

Probiotic Molecules That Inhibit Inflammatory Diseases

Consumption of probiotics for health purposes has increased vastly in the past few decades, and yet the scientific evidence to support health benefits from probiotics is only beginning to emerge. As more probiotics are studied, we are beginning to understand the mechanisms of action by which they benefit human health, as well as to identify the bacterial molecules responsible for these benefits. A new era of therapeutics is on the horizon in which purified molecules from probiotics will be used to prevent and treat diseases. In this review, we summarize the active molecules from probiotic bacteria that have been shown to affect innate and adaptive immunity and have health benefits in experimental settings. We focus particularly on the cellular and molecular mechanisms of the probiotic Bacillus subtilis and its active molecule, exopolysaccharide (ESPBs).

Immunomodulatory potential of four candidate probiotic Lactobacillus strains from plant and animal origin using comparative genomic analysis

Probiotic strains from different origins have shown promise in recent decades for their health benefits, for example in promoting and regulating the immune system. The immunomodulatory potential of four Lactobacillus strains from animal and plant origins was evaluated in this paper based on their genomic information. Comparative genomic analysis was performed through genome alignment, average nucleotide identity (ANI) analysis and gene mining for putative immunomodulatory genes. The genomes of the four Lactobacillus strains show relative similarities in multiple regions, as observed in the genome alignment. However, ANI analysis showed that L. mucosae LM1 and L. fermentum SK152 are the most similar when considering their nucleotide sequences alone. Gene mining of putative immunomodulatory genes studied from L. plantarum WCFS1 yielded multiple results in the four potential probiotic strains, with L. plantarum SK151 showing the largest number of genes at around 74 hits, followed by L. johnsonii PF01 at 41 genes when adjusted for matches with at least 30 % identity. Looking at the immunomodulatory genes in each strain, L. plantarum SK151 and L. johnsonii PF01 may have wider activity, covering both immune activation and immune suppression, as compared to L. mucosae LM1 and L. fermentum SK152, which could be more effective in activating immune cells and the pro-inflammatory cascade rather than suppressing it. The similarities and differences between the four Lactobacillus species showed that there is no definitive trend based on the origin of isolation alone. Moreover, higher percentage identities between genomes do not directly correlate with higher similarities in potential activity, such as in immunomodulation. The immunomodulatory function of each of the four Lactobacillus strains should be observed and verified experimentally in the future, since some the activity of some genes may be strain-specific, which would not be identified through comparative genomics alone.

Effects of Dietary Enterococcus faecalis YFI-G720 on the Growth, Immunity, Serum Biochemical, Intestinal Morphology, Intestinal Microbiota, and Disease Resistance of Crucian Carp (Carassius auratus)

Diseases of crucian carp (Carassius auratus) are closely related to intestinal parameters. Enterococcus faecalis has strong colonization ability in the intestinal tract, and produces natural antibiotics, bacteriocin, and other bacteriostatic substances, which can effectively inhibit some pathogenic bacteria and improve the intestinal microenvironment. This study aimed to assess the effects of E. faecalis YFI-G720 which was isolated from the intestinal of crucian carp on the growth, immunity, intestinal health, and disease resistance of crucian carp. Fish (48.16 ± 0.55 g) were fed four diets, commercial diet or diet containing E. faecalis at 105 CFU/g (EF1), 106 CFU/g (EF2), or 107 CFU/g (EF3) for 28 days. The results showed that supplementation of E. faecalis significantly improved the weight gain ratio (WGR) and the specific growth rate (SGR) compared with control group (p < 0.05). Intestinal mucosal epithelial cells in EF2 were intact and normal, but there was obvious vacuolation in CG. Compared with CG, serum C3 and IgM in EF2 were significantly increased at the end of the experiment (p < 0.05), and serum alkaline phosphatase was significantly higher in all experimental groups (p < 0.05). Among studied immune-related genes, expression was detected by qPCR, C3, IgM, and IL-1βwere upregulated in all experimental groups to varying degrees from 14 days, with highest expression in EF2 at 28 days. Intestinal microbiota structure analyzed through high-throughput sequencing, and the results showed that the relative abundance of Aeromonas and Acinetobacter decreased while Cetobacterium increased in all experimental groups, with the greatest changes in EF2. Challenge tests showed that fish fed E. faecalis were more resistant to Aeromonas veronii (p < 0.05). In conclusion, dietary E. faecalis YFI-G720 at 106 CFU/g can improve the health status, immune parameters, intestinal microbiota composition, and disease resistance of crucian carp.

<i>Lactococcus lactis</i> subsp. <i>cremoris</i> C60 induces macrophages activation that enhances CD4+ T cell-based adaptive immunity

Lactococcus lactis subsp. cremoris C60 is a probiotic strain that induces diverse functional modifications in immune cells. In this report, as a novel effect of C60 on myeloid lineage cells, we show that C60 enhances the immunological function of macrophages that consequently promotes CD4+ T cell activity in an antigen-dependent manner. Heat-killed (HK) C60 induced the production of pro-inflammatory cytokines in thioglycolate-elicited peritoneal macrophages (TPMs) much stronger than Toll-like receptor (TLR) ligand stimulation. The HK-C60 treatment also augmented the expression of antigen-presenting and co-stimulatory molecules, such as major histocompatibility complex (MHC) class II, CD80, and CD86, as well as antigen uptake in TPMs. These HK-C60-mediated functional upregulations in TPMs resulted in the promotion of CD4+ T cell activation in an antigen-dependent manner. Interestingly, the TPMs that originated from the mice fed the HK-C60 diet showed pre-activated characteristics, which was confirmed by the upregulation of cytokine production and antigen presentation-related molecule expression under lipopolysaccharide (LPS) stimulation. Furthermore, the antigen-dependent CD4+ T cell activation was also enhanced by the TPMs. This implied that antigen presentation activity was enhanced in the TPMs that originated from the HK-C60 diet mice. Thus, C60 effectively upregulates the immunological function of macrophages that directly connects to CD4+ T cell-based adaptive immunity.

Strategies for circadian rhythm disturbances and related psychiatric disorders: A new cue based on plant polysaccharides and intestinal microbiota

Circadian rhythm is essential to human physiological homeostasis and health. The oscillation of host circadian rhythm affects the composition and function of intestinal microbiota, meanwhile, the normal operation of host...

Molecular and Cellular Mechanisms Influenced by Postbiotics

In recent years, commensal bacteria colonizing the human body have been recognized as important determinants of health and multiple pathologic conditions. Among the most extensively studied commensal bacteria are the gut microbiota, which perform a plethora of functions, including the synthesis of bioactive products, metabolism of dietary compounds, and immunomodulation, both through attenuation and immunostimulation. An imbalance in the microbiota population, i.e., dysbiosis, has been linked to many human pathologies, including various cancer types and neurodegenerative diseases. Targeting gut microbiota and microbiome-host interactions resulting from probiotics, prebiotics, and postbiotics is a growing opportunity for the effective treatment of various diseases. As more research is being conducted, the microbiome field is shifting from simple descriptive analysis of commensal compositions to more molecular, cellular, and functional studies. Insight into these mechanisms is of paramount importance for understanding and modulating the effects that microbiota, probiotics, and their derivatives exert on host health.

The Probiotic Properties of Lactic Acid Bacteria and Their Applications in Animal Husbandry

The intestinal tract of animals is a complex ecosystem in which nutrients, microbiota and host cells interact extensively. Probiotics can be considered as part of the natural microbiota of the gut and are involved in improving homeostasis. Lactic acid bacteria (LAB) is a general term for a class of non-spore forming, gram-positive bacteria whose main product of fermented sugar is lactic acid. LAB are considered to be a type of probiotic due to their health-promoting effects on the host, and are very effective in the treatment of human and animal diseases. LAB have been widely used as a class of microbial agents in the field of livestock and poultry breeding. They are also considered to be the best substitutes for antibiotics to improve animal health. Here, we review the biological functions, probiotic characteristics and applications of LAB in livestock and poultry breeding. This review is designed to provide a theoretical base for the in-depth exploration and promotion of LAB use in animal diets.

Common Inflammatory Mechanisms in COVID-19 and Parkinson's Diseases: The Role of Microbiome, Pharmabiotics and Postbiotics in Their Prevention

In the last decade, metagenomic studies have shown the key role of the gut microbiome in maintaining immune and neuroendocrine systems. Malfunction of the gut microbiome can induce inflammatory processes, oxidative stress, and cytokine storm. Dysfunction of the gut microbiome can be caused by short-term (virus infection and other infectious diseases) or long-term (environment, nutrition, and stress) factors. Here, we reviewed the inflammation and oxidative stress in neurodegenerative diseases and coronavirus infection (COVID-19). Here, we reviewed the renin-angiotensin-aldosterone system (RAAS) involved in the processes of formation of oxidative stress and inflammation in viral and neurodegenerative diseases. Moreover, the coronavirus uses ACE2 receptors of the RAAS to penetrate human cells. The coronavirus infection can be the trigger for neurodegenerative diseases by dysfunction of the RAAS. Pharmabiotics, postbiotics, and next-generation probiotics, are considered as a means to prevent oxidative stress, inflammatory processes, neurodegenerative and viral diseases through gut microbiome regulation.

Nutritional and ethnomedicinal scenario of koumiss: A concurrent review

Fermented foods are an essential source of nutrition for the communities living in developing areas of the world. Additionally, traditional fermented products are a rich source of various bioactive components. Experimental research regarding the functional exploration of these products is a way forward for better human health. Among fermented foods, Koumiss is rich in vitamins especially vitamin C and minerals, i.e., phosphorus and calcium. In addition, it is also rich in vitamins A, E, B2, B12, and pantothenic acid. High concentrations of lactose in milk favor bacterial fermentation, as the original cultures decompose it into lactic acid. Koumiss contains essential fatty acids such as linoleic and linolenic acid. Koumiss offers many health benefits including boosting the immune system and maintains blood pressure, good effect on the kidneys, endocrine glands, gut system, liver, and nervous and vascular system. The rich microflora from the fermented product has a pivotal role in maintaining gut health and treating various digestive diseases. The core focus of the current review paper is to highlight the nutritional and therapeutic potential, i.e., anticarcinogenic, hypocholesterolemia effect, antioxidative properties, antibacterial properties, antibacterial spectrum, intestinal enlargement, and β-galactosidase activity, of Koumiss as a traditional fermented product. Moreover, history and production technology of the Koumiss are also the main part of this review paper.

Characterization and Antioxidant Activity of Released Exopolysaccharide from Potential Probiotic Leuconostoc mesenteroides LM187

A released exopolysaccharide (rEPS)-producing strain (LM187) with good acid resistance, bile salt resistance, and cholesterol-lowering properties was isolated from Sichuan paocai and identified as Leuconostoc mesenteroides subsp. mesenteroides. The purified rEPS, designated as rEPS414, had a uniform molecular weight of 7.757 × 10⁵ Da. Analysis of the monosaccharide composition revealed that the molecule was mainly composed of glucose. The Fourier transform-infrared spectrum showed that rEPS414 contained both α-type and β-type glycosidic bonds. ¹H and ¹³C nuclear magnetic resonance spectra analysis showed that the purified rEPS contained arabinose, galactose, and rhamnose, but less uronic acid. Scanning electron microscopy demonstrated that the exopolysaccharide displayed a large number of scattered, fluffy, porous cellular network flake structures. In addition, rEPS414 exhibited strong in vitro antioxidant activity. These results showed that strain LM187 and its rEPS are promising probiotics with broad prospects in industry.

Effect of Lactobacillus johnsonii Strain SQ0048 on the TLRs-MyD88/NF-κB Signaling Pathway in Bovine Vaginal Epithelial Cells

Vaginal inflammation is a common disease of the dairy cows' reproductive tract. Lactic acid bacteria can combat purulent inflammation caused by pathogenic bacteria and regulate the NF-κB signaling pathway mediated by toll-like receptors (TLRs) in the inflammatory response. We studied the effect of Lactobacillus johnsonii SQ0048, an isolate with antibacterial activity, on the NF-κB signaling pathway in cow vaginal epithelial cells. The expression levels of serial effectors related to the TLRs-MyD88/NF-κB signaling pathway (TLR2, TLR4, MyD88, IKK, NF-κB, IL-1β, IL-6, TNF-α, and IL-10) were measured with real-time polymerase chain reaction (RT-PCR), ELISA, and Western blot analyses. TLR2 and TLR4 were activated by SQ0048 cells, as noted by increased mRNA expression levels of TLR2 and TLR4 in SQ0048-treated bovine vaginal epithelial cells relative to control cells (P <0.01). SQ0048 treatment also significantly increased MyD88 and IKK expression, and activated NF-κB in vaginal epithelial cells (P <0.01). In addition, SQ0048 treatment also significantly increased mRNA expression levels of IL-1β, IL-6, and TNF-α, but decreased IL-10 mRNA expression levels (P <0.01). These data indicate that strain SQ0048 presence can improve the immune functions of cow vaginal epithelial cells by activating TLRs-MyD88/NF-κB signaling pathways. However, further in vivo studies are required to confirm these findings.

The Potential Role of RP105 in Regulation of Inflammation and Osteoclastogenesis During Inflammatory Diseases

Inflammatory diseases have a negative impact on bone homeostasis via exacerbated local and systemic inflammation. Bone resorbing osteoclasts are mainly derived from hematopoietic precursors and bone marrow monocytes. Induced osteoclastogenesis during inflammation, autoimmunity, metabolic diseases, and cancers is associated with bone loss and osteoporosis. Proinflammatory cytokines, pathogen-associated molecular patterns, or endogenous pathogenic factors induce osteoclastogenic differentiation by binding to the Toll-like receptor (TLR) family expressed on surface of osteoclast precursors. As a non-canonical member of the TLRs, radioprotective 105 kDa (RP105 or CD180) and its ligand, myeloid differentiation protein 1 (MD1), are involved in several bone metabolic disorders. Reports from literature had demonstrated RP105 as an important activator of B cells, bone marrow monocytes, and macrophages, which regulates inflammatory cytokines release from immune cells. Reports from literature had shown the association between RP105 and other TLRs, and the downstream signaling mechanisms of RP105 with different “signaling-competent” partners in immune cells during different disease conditions. This review is focused to summarize: (1) the role of RP105 on immune cells’ function and inflammation regulation (2) the potential regulatory roles of RP105 in different disease-mediated osteoclast activation and the underlying mechanisms, and (3) the different “signaling-competent” partners of RP105 that regulates osteoclastogenesis.

Double-Barrel Shotgun: Probiotic Lactic Acid Bacteria with Antiviral Properties Modified to Serve as Vaccines

Contrary to the general belief that the sole function of probiotics is to keep intestinal microbiota in a balanced state and stimulate the host’s immune response, several studies have shown that certain strains of lactic acid bacteria (LAB) have direct and/or indirect antiviral properties. LAB can stimulate the innate antiviral immune defence system in their host, produce antiviral peptides, and release metabolites that prevent either viral replication or adhesion to cell surfaces. The SARS-CoV (COVID-19) pandemic shifted the world’s interest towards the development of vaccines against viral infections. It is hypothesised that the adherence of SARS-CoV spike proteins to the surface of Bifidobacterium breve could elicit an immune response in its host and trigger the production of antibodies. The question now remains as to whether probiotic LAB could be genetically modified to synthesize viral antigens and serve as vaccines—this concept and the role that LAB play in viral infection are explored in this review.

Oral Vaccination with Hepatitis E Virus Capsid Protein and Immunobiotic Bacterium-Like Particles Induce Intestinal and Systemic Immunity in Mice

The hepatitis E virus (HEV) genotype 3 (GT3) is an emergent pathogen in industrialized countries. It is transmitted zoonotically and may lead to chronic hepatitis in immunocompromised individuals. We evaluated if the major antigen of HEV, the capsid protein, can be used in combination with immunobiotic bacterium-like particles (IBLP) for oral vaccination in a mouse model. We have cloned and expressed the RGS-His₅-tagged HEV GT3 capsid protein (ORF2) in E. coli and purified it by NiNTA. IBLP were obtained from two immunobiotic Lactobacillus rhamnosus strains acid- and heat-treated. ORF2 and the IBLP were orally administered to Balb/c mice. After three oral immunizations (14-day intervals), blood, intestinal fluid, Peyer´s patches, and spleen samples were drawn. IgA- and IgG-specific antibodies were determined by ELISA. Mononuclear cell populations from Peyer's patches and spleen were analyzed by flow cytometry, and the cytokine profiles were determined by ELISA to study cellular immunity. Orally administered recombinant ORF2 and IBLP from two L. rhamnosus strains (CRL1505 and IBL027) induced both antigen-specific humoral and cellular immune responses in mice. IBLP027 was more effective in inducing specific secretory IgA in the gut. IFN-γ, TNF-α, and IL-4 were produced by Peyer's plaques lymphocytes stimulated with ORF2 ex vivo suggesting a mixed Th1/Th2-type adaptive immune response in immunized mice. Oral vaccines are not invasive, do not need to be administered by specialized personal, and elicit both systemic and local immune responses at the port of entry. Here, we present an experimental oral vaccine for HEV GT3, which could be further developed for human and/or veterinary use.

Sourdough Biotechnology Applied to Gluten-Free Baked Goods: Rescuing the Tradition

Recent studies suggest that the beneficial properties provided by sourdough fermentation may be translated to the development of new GF products that could improve their technological and nutritional properties. The main objective of this manuscript is to review the current evidence regarding the elaboration of GF baked goods, and to present the latest knowledge about the so-called sourdough biotechnology. A bibliographic search of articles published in the last 12 years has been carried out. It is common to use additives, such as hydrocolloids, proteins, enzymes, and emulsifiers, to technologically improve GF products. Sourdough is a mixture of flour and water fermented by an ecosystem of lactic acid bacteria (LAB) and yeasts that provide technological and nutritional improvements to the bakery products. LAB-synthesized biopolymers can mimic gluten molecules. Sourdough biotechnology is an ecological and cost-effective technology with great potential in the field of GF products. Further research is necessary to optimize the process and select species of microorganisms robust enough to be competitive in any circumstance.

Exopolysaccharides as Antimicrobial Agents: Mechanism and Spectrum of Activity

Exopolysaccharides (EPSs) are metabolites synthesized and excreted by a variety of microorganisms, including lactic acid bacteria (LAB). EPS serve several biological functions such as interactions between bacteria and their environments, protection against hostile conditions including dehydration, the alleviation of the action of toxic compounds (bile salts, hydrolyzing enzymes, lysozyme, gastric, and pancreatic enzymes, metal ions, antibiotics), and stresses (changing pH, osmolarity), and evasion of the immune response and phage attack. Bacterial EPSs are considered valuable by the food, pharmaceutical, and nutraceutical industries, owing to their health-promoting benefits and rheological impacts. Numerous studies have reported the unusual antimicrobial activities of various EPS against a wide variety of pathogenic microbes (bacteria, virus, and fungi). This review aims to provide a comprehensive examination of the in vitro and in vivo antimicrobial activities of different EPSs, mainly against foodborne bacterial, fungal, and viral pathogens. The mechanism of EPS action against these pathogens as well as the methods used to measure antimicrobial activities are critically reviewed.

Immunobiotic Feed Developed with Lactobacillus delbrueckii subsp. delbrueckii TUA4408L and the Soymilk By-Product Okara Improves Health and Growth Performance in Pigs

Lactobacillus delbrueckii subsp. delbrueckii TUA4408L is able to differentially modulate the innate immune response of porcine intestinal epithelial cells triggered by TLR4 activation. This strain also has a remarkable ability to grow on plant substrates. These two immunological and biotechnological characteristics prompted us to evaluate whether the soymilk by-product okara fermented with the TUA4408L strain can serve as an immunobiotic feed with the ability to beneficially modulate the intestinal immunity of piglets after weaning to improve their productivity. Our in vivo studies demonstrated that the administration of immunobiotic TUA4408L-fermented okara feed significantly increased piglet growth performance and meat quality. These positive effects were associated with the ability of the TUA4408L-fermented okara feed to beneficially modulate both intestinal microbiota and immunity in pigs. The immunobiotic feed improved the abundance of the beneficial bacteria Lactobacillus and Lactococcus in the gut of pigs, reduced blood markers of inflammation, and differentially regulated the expression of inflammatory and regulatory cytokines in the intestinal mucosa. These findings indicate that the immunobiotic TUA4408L-fermented okara feed could be an economical and environmentally friendly option to improve the growth performance and immune health of pigs.

The Immunomodulatory Properties of β-2,6 Fructans: A Comprehensive Review

Polysaccharides such as β-2,1-linked fructans including inulin or fructose oligosaccharides are well-known prebiotics with recognised immunomodulatory properties. In recent years, other fructan types covering β-2,6-linked fructans, particularly microbial levans, have gained increasing interest in the field. β-2,6-linked fructans of different degrees of polymerisation can be synthesised by plants or microbes including those that reside in the gastrointestinal tract. Accumulating evidence suggests a role for these β-2,6 fructans in modulating immune function. Here, we provide an overview of the sources and structures of β-2,6 fructans from plants and microbes and describe their ability to modulate immune function in vitro and in vivo along with the suggested mechanisms underpinning their immunomodulatory properties. Further, we discuss the limitations and perspectives pertinent to current studies and the potential applications of β-2,6 fructans including in gut health.