Protection of Galacto-Oligosaccharide against E. coli O157 Colonization through Enhancing Gut Barrier Function and Modulating Gut Microbiota

Probiotics and prebiotics: new treatment strategies for oral potentially malignant disorders and gastrointestinal precancerous lesions

Oral potentially malignant disorders (OPMDs) and gastrointestinal precancerous lesions (GPLs) are major public health concerns because of their potential to progress to cancer. Probiotics, prebiotics, and engineered probiotics can positively influence the prevention and management of OPMDs and GPLs. This review aims to comprehensively review the application status of probiotics, prebiotics and engineered probiotics in OPMDs and GPLs, explore their potential mechanisms of action, and anticipate their future clinical use.

Harnessing the human gut microbiota: an emerging frontier in combatting multidrug-resistant bacteria

Antimicrobial resistance (AMR) has become a major and escalating global health threat, undermining the effectiveness of current antibiotic and antimicrobial therapies. The rise of multidrug-resistant bacteria has led to increasingly difficult-to-treat infections, resulting in higher morbidity, mortality, and healthcare costs. Tackling this crisis requires the development of novel antimicrobial agents, optimization of current therapeutic strategies, and global initiatives in infection surveillance and control. Recent studies highlight the crucial role of the human gut microbiota in defending against AMR pathogens. A balanced microbiota protects the body through mechanisms such as colonization resistance, positioning it as a key ally in the fight against AMR. In contrast, gut dysbiosis disrupts this defense, thereby facilitating the persistence, colonization, and dissemination of resistant pathogens. This review will explore how gut microbiota influence drug-resistant bacterial infections, its involvement in various types of AMR-related infections, and the potential for novel microbiota-targeted therapies, such as fecal microbiota transplantation, prebiotics, probiotics, phage therapy. Elucidating the interactions between gut microbiota and AMR pathogens will provide critical insights for developing novel therapeutic strategies to prevent and treat AMR infections. While previous reviews have focused on the general impact of the microbiota on human health, this review will specifically look at the latest research on the interactions between the gut microbiota and the evolution and spread of AMR, highlighting potential therapeutic strategies.

Natural anti-adhesive components against pathogenic bacterial adhesion and infection in gastrointestinal tract: case studies of Helicobacter pylori, Salmonella enterica, Clostridium difficile, and diarrheagenic Escherichia coli

Antimicrobial resistance (AMR) poses a global public health concern. Recognizing the critical role of bacterial adhesion in pathogenesis of infection, anti-adhesive therapy emerges as a promising approach to impede initial bacterial attachment, thus preventing pathogenic colonization and infection. Natural anti-adhesive agents derived from food sources are generally safe and have the potential to inhibit the emergence of resistant bacteria. This comprehensive review explored diverse natural dietary components exhibiting anti-adhesive activities against several model enteric pathogens, including Helicobacter pylori, Salmonella enterica, Clostridium difficile, and three key diarrheagenic Escherichia coli (i.e., enterotoxigenic E. coli, enteropathogenic E. coli, and enterohemorrhagic E. coli). Investigating various anti-adhesive products will advance our understanding of current research of the field and inspire further development of these agents as potential nutraceuticals or adjuvants to improve the efficacy of conventional antibiotics.

Relationships between bacteria and the mucus layer

The mucus layer on epithelial cells is an essential barrier, as well as a nutrient-rich niche for bacteria, forming a dynamic, functional and symbiotic ecosystem and first line of defense against invading pathogens. Particularly bacteria in biofilms are very difficult to eradicate. The extensively O-glycosylated mucins are the main glycoproteins in mucus that interact with microbes. For example, mucins act as adhesion receptors and nutritional substrates for gut bacteria. Mucins also play important roles in immune responses, and they control the composition of the microbiome, primarily due to the abundance of complex O-glycans. In inflammation or infection, the structures of mucin O-glycans can change and thus affect mucin function, impact biofilm formation and the induction of virulence pathways in bacteria. In turn, bacteria can support host cell growth, mucin production and can stimulate changes in the host immune system and responses leading to healthy tissue function. The external polysaccharides of bacteria are critical for controlling adhesion and biofilm formation. It is therefore important to understand the relationships between the mucus layer and microbes, the mechanisms and regulation of the biosynthesis of mucins, of bacterial surface polysaccharides, and adhesins. This knowledge can provide biomarkers, vaccines and help to develop new approaches for improved therapies, including antibiotic treatments.

The Role of Prebiotics in Modulating Gut Microbiota: Implications for Human Health

The human gut microbiota, an intricate ecosystem within the gastrointestinal tract, plays a pivotal role in health and disease. Prebiotics, non-digestible food ingredients that beneficially affect the host by selectively stimulating the growth and/or activity of beneficial microorganisms, have emerged as a key modulator of this complex microbial community. This review article explores the evolution of the prebiotic concept, delineates various types of prebiotics, including fructans, galactooligosaccharides, xylooligosaccharides, chitooligosaccharides, lactulose, resistant starch, and polyphenols, and elucidates their impact on the gut microbiota composition. We delve into the mechanisms through which prebiotics exert their effects, particularly focusing on producing short-chain fatty acids and modulating the gut microbiota towards a health-promoting composition. The implications of prebiotics on human health are extensively reviewed, focusing on conditions such as obesity, inflammatory bowel disease, immune function, and mental health. The review further discusses the emerging concept of synbiotics-combinations of prebiotics and probiotics that synergistically enhance gut health-and highlights the market potential of prebiotics in response to a growing demand for functional foods. By consolidating current knowledge and identifying areas for future research, this review aims to enhance understanding of prebiotics' role in health and disease, underscoring their importance in maintaining a healthy gut microbiome and overall well-being.

Exopolysaccharides Produced by Bifidobacterium longum subsp. longum YS108R Ameliorates DSS-Induced Ulcerative Colitis in Mice by Improving the Gut Barrier and Regulating the Gut Microbiota

Ulcerative colitis (UC) is a major disease that has endangered human health. Our previous study demonstrated that Bifidobacterium longum subsp. longum YS108R, a ropy exopolysaccharide (EPS)-producing bacterium, could alleviate UC in mice, but it is unclear whether EPS is the key substance responsible for its action. In this study, we proposed to investigate the remitting effect of EPS from B. longum subsp. longum YS108R on UC in a DSS-induced UC mouse model. Water extraction and alcohol precipitation were applied to extract EPS from the supernatant of B. longum subsp. longum YS108R culture. Then the animal trial was performed, and the results indicated that YS108R EPS ameliorated colonic pathological damage and the intestinal barrier. YS108R EPS suppressed inflammation via NF-κB signaling pathway inhibition and attenuated oxidative stress via the Nrf2 signaling pathway activation. Remarkably, YS108R EPS regulated gut microbiota, as evidenced by an increase in short-chain fatty acid (SCFA)-producing bacteria and a decline in Gram-negative bacteria, resulting in an increase of propionate and butyrate and a reduction of lipopolysaccharide (LPS). Collectively, YS108R EPS manipulated the intestinal microbiota and its metabolites, which further improved the intestinal barrier and inhibited inflammation and oxidative stress, thereby alleviating UC.

Unveiling the therapeutic symphony of probiotics, prebiotics, and postbiotics in gut-immune harmony

The gut microbiota and immune system interaction play a crucial role in maintaining overall health. Probiotics, prebiotics, and postbiotics have emerged as promising therapeutic approaches to positively influence this complex axis and enhance health outcomes. Probiotics, as live bacteria, promote the growth of immune cells, shape immune responses, and maintain gut barrier integrity. They modify the gut microbiota by fostering beneficial bacteria while suppressing harmful ones. Additionally, probiotics interact with the immune system, increasing immune cell activity and anti-inflammatory cytokine production. Prebiotics, as indigestible fibers, selectively nourish beneficial microorganisms in the gut, enhancing gut microbial diversity and activity. This, in turn, improves gut health and boosts immune responses while controlling inflammation through its immunomodulatory properties. Postbiotics, produced during probiotic fermentation, such as short-chain fatty acids and antimicrobial peptides, positively impact gut health and modulate immune responses. Ensuring quality control and standardization will be essential for successful clinical implementation of these interventions. Overall, understanding and harnessing the gut microbiota-immune system interplay offer promising avenues for improving digestive and immunological health.

Effects of microalgae, with or without xylanase supplementation, on serum immunoglobulins, cecal short-chain fatty acids, microbial diversity, and metabolic pathways of broiler chickens

Modern broilers are highly susceptible to environmental and pathogenic threats, leading to gut disorders and poor nutrient utilization if not managed properly. Nutritional programming using several feedstuffs and coproducts to manage gut health has been studied. This study used microalgae as a functional compound and xylanase enzyme in broilers' diets as a strategy to manage gut health. A total of 162 one-day-old unsexed Cobb 500 broiler chicks were randomly assigned to 1 of the 3 dietary treatments: a) corn-soybean meal-based control diet (CON), b) 3% microalgae (MAG), and c) MAG with xylanase enzyme (MAG+XYN). The chicks were reared for 35 days (d) on a floor pen system maintaining standard environment conditions to evaluate the effects of microalgae, with or without xylanase supplementation, on serum immunoglobulins, cecal short-chain fatty acids (SCFA) production, cecal microbial diversity, and metabolic pathways. No significant differences were found for serum immunoglobulin and cecal SCFA among the treatment groups (P > 0.05). Relative microbial abundance at the genus level showed that MAG and MAG+XYN groups had a diverse microbial community on d 3 and d 35. However, no bacterial genus had a significant difference (P > 0.05) in their relative abundance on d 3, but 16 genera showed significant differences (P < 0.05) in their relative abundance among the dietary treatments on d 35. Most of these bacteria were SCFA-producing bacteria. Moreover, MAG and MAG+XYN-fed broilers had better responses than CON groups for metabolic pathways (D-mannose degradation, pectin degradation I and II, β-1-4-mannan degradation, tetrahydrofolate biosynthesis, glutathione biosynthesis, glutathione-peroxide redox reactions, lactate fermentation to propionate, acetate, and hydrogen, etc.) both on d 3 and d 35. The results suggest that using microalgae, with or without xylanase, had no statistical impact on serum immunoglobulins and cecal SCFA production in broilers. However, an improvement in the cecal microbial diversity and metabolic pathways, which are essential indicators of gut health and nutrient utilization, was observed. Most of the improved metabolic pathways were related to fiber utilization and oxidative stress reduction.

Immunological Regulation of Gut-Tropic Immune Cells by Extracellular Vesicles

The remarkable diversity of lymphocytes, essential components of the immune system, serves as an ingenious mechanism for maximizing the efficient utilization of limited host defense resources. While cell adhesion molecules, notably in gut-tropic T cells, play a central role in this mechanism, the counterbalancing molecular details have remained elusive. Conversely, we've uncovered the molecular pathways enabling extracellular vesicles secreted by lymphocytes to reach the gut's mucosal tissues, facilitating immunological regulation. This discovery sheds light on immune fine-tuning, offering insights into immune regulation mechanisms.

Akkermansia muciniphila and Alcohol-Related Liver Diseases. A Systematic Review

SCOPE

Akkermansia muciniphila (A. muciniphila) are Gram negative commensal bacteria, degrading mucin in the intestinal mucosa, modulating intestinal permeability and inflammation in the digestive tract, liver, and blood. Some components can promote the relative abundance of A. muciniphila in the gut microbiota, but lower levels of A. muciniphila are more commonly found in people with obesity, diabetes, metabolic syndromes, or inflammatory digestive diseases. Over-intake of ethanol can also induce a decrease of A. muciniphila, associated with dysregulation of microbial metabolite production, impaired intestinal permeability, induction of chronic inflammation, and production of cytokines.

METHODS AND RESULTS

Using a PRISMA search strategy, a review is performed on the bacteriological characteristics of A. muciniphila, the factors capable of modulating its relative abundance in the digestive tract and its probiotic use in alcohol-related liver diseases (alcoholic hepatitis, cirrhosis, hepatocellular carcinoma, hepatic transplantation, partial hepatectomy).

CONCLUSION

Several studies have shown that supplementation with A. muciniphila can improve ethanol-related hepatic pathologies, and highlight the interest in using this bacterial species as a probiotic.

The potential of dietary fiber in building immunity against gastrointestinal and respiratory disorders

The numerous health benefits of dietary fibers (DFs) justify their inclusion in human diets and biomedical products. Given the short- and long-term human impacts of the COVID-19 virus on human health, the potential of DFs in building immunity against gastrointestinal and respiratory disorders is currently receiving high attention. This paper reviews the physicochemical properties of DFs, together with their immune functions and effects on the gastrointestinal tract and respiratory system mainly based on research in the last ten years. Possible modes of action of DFs in promoting health, especially building immunity, are explored. We seek to highlight the importance of understanding the exact physical and chemical characteristics and molecular behaviors of DFs in providing specific immune function. This review provides a perspective beyond the existing recognition of DFs' positive effects on human health, and offers a theoretical framework for the development of special DFs components and their application in functional foods and other therapeutic products against gastrointestinal and respiratory disorders. DFs enhance immunity from gastrointestinal and respiratory diseases to promote host health.

The function of human milk oligosaccharides and their substitute oligosaccharides as probiotics in gut inflammation

Gut inflammation seriously affects the healthy life of patients, and has a trend of increasing incidence rate. However, the current methods for treating gut inflammation are limited to surgery and drugs, which can cause irreversible damage to patients, especially infants. As natural oligosaccharides in human breast milk, human milk oligosaccharides (HMOs) function as probiotics in treating and preventing gut inflammation: improving the abundance of the gut microbiota, increasing the gut barrier function, and reducing the gut inflammatory reaction. Meanwhile, due to the complexity and high cost of their synthesis, people are searching for functional oligosaccharides that can replace HMOs as a food additive in infants milk powder and adjuvant therapy for chronic inflammation. The purpose of this review is to summarize the therapeutic and preventive effects of HMOs and their substitute functional oligosaccharides as probiotics in gut inflammation, and to summarize the prospect of their application in infant breast milk replacement in the future.

Synthesis of bioactive oligosaccharides and their potential health benefits

Oligosaccharides, a low polymerization degree of carbohydrate, possess various physiological activities, such as anti-diabetes, anti-obesity, anti-aging, anti-viral, and gut microbiota regulation, having a widely used in food and medical fields. However, due to the limited natural oligosaccharides, many un-natural oligosaccharides from complex polysaccharides are being studied for amplifying the available pool of oligosaccharides. More recently, various oligosaccharides were developed by using several artificial strategies, such as chemical degradation, enzyme catalysis, and biosynthesis, then they can be applied in various sectors. Moreover, it has gradually become a trend to use biosynthesis to realize the synthesis of oligosaccharides with clear structure. Emerging research has found that un-natural oligosaccharides exert more comprehensive effects against various human diseases through multiple mechanisms. However, these oligosaccharides from various routes have not been critical reviewed and summarized. Therefore, the purpose of this review is to present the various routes of oligosaccharides preparations and healthy effects, with a focus on diabetes, obesity, aging, virus, and gut microbiota. Additionally, the application of multi-omics for these natural and un-natural oligosaccharides has also been discussed. Especially, the multi-omics are needed to apply in various disease models to find out various biomarkers to respond to the dynamic change process of oligosaccharides.

Infant Fecal Fermentations with Galacto-Oligosaccharides and 2′-Fucosyllactose Show Differential Bifidobacterium longum Stimulation at Subspecies Level

The objective of the current study was to evaluate the potential of 2′-FL and GOS, individually and combined, in beneficially modulating the microbial composition of infant and toddler (12–18 months) feces using the micro-Matrix bioreactor. In addition, the impacts of GOS and 2′-FL, individually and combined, on the outgrowth of fecal bifidobacteria at (sub)species level was investigated using the baby M-SHIME® model. For young toddlers, significant increases in the genera Bifidobacterium, Veillonella, and Streptococcus, and decreases in Enterobacteriaceae, Clostridium XIVa, and Roseburia were observed in all supplemented fermentations. In addition, GOS, and combinations of GOS and 2′-FL, increased Collinsella and decreased Salmonella, whereas 2′-FL, and combined GOS and 2′-FL, decreased Dorea. Alpha diversity increased significantly in infants with GOS and/or 2′-FL, as well as the relative abundances of the genera Veillonella and Akkermansia with 2′-FL, and Lactobacillus with GOS. Combinations of GOS and 2′-FL significantly stimulated Veillonella, Lactobacillus, Bifidobacterium, and Streptococcus. In all supplemented fermentations, Proteobacteria decreased, with the most profound decreases accomplished by the combination of GOS and 2′-FL. When zooming in on the different (sub)species of Bifidobacterium, GOS and 2’-FL were shown to be complementary in stimulating breast-fed infant-associated subspecies of Bifidobacterium longum in a dose-dependent manner: GOS stimulated Bifidobacterium longum subsp. longum, whereas 2′-FL supported outgrowth of Bifidobacterium longum subsp. infantis.

Galacto-Oligosaccharides Increase the Abundance of Beneficial Probiotic Bacteria and Improve Gut Architecture and Goblet Cell Expression in Poorly Performing Piglets, but Not Performance

Poorly performing piglets receiving commercial milk replacers do not benefit from the naturally occurring probiotic galacto-oligosaccharides otherwise found in sow milk. Study objectives were to investigate the effects of complete milk replacer supplemented with galacto-oligosaccharides on the microbiome, gut architecture and immunomodulatory goblet cell expression of poorly performing piglets that could benefit from milk replacement feeding when separated from sows and housed with fit siblings in environmentally controlled pens. The study is novel in that it is one of the first to investigate the effects of supplementing complete milk replacer with galacto-oligosaccharides in poorly performing piglets. Gastrointestinal tract samples were collected from piglets, and the microbiome composition was assessed by 16s ribosomal ribonucleic acid gene sequencing. Gut architectural features, villus/crypt ratio and enumeration of goblet cells in tissues were assessed by histopathological techniques. The most abundant taxa identified at the genus level were Lactobacillus, Streptococcus, Prevotella, Lactococcus and Leuconostoc. Milk replacer plus galacto-oligosaccharides significantly improved gut architectural features and villus/crypt ratio throughout the gastrointestinal tract, increased the number of goblet cells and revealed a differential abundance of beneficial probiotic bacteria, particularly Lactobacillus and Bifidobacterium. In these respects, galacto-oligosaccharide-supplemented milk replacer may be a useful addition to animal husbandry in poorly performing, non-thriving animals when moved to environmentally controlled pens away from sows and fit siblings, thereby modulating the microbiome and gastrointestinal tract performance.

Direct Action of Non-Digestible Oligosaccharides against a Leaky Gut

The epithelial monolayer is the primary determinant of mucosal barrier function, and tight junction (TJ) complexes seal the paracellular space between the adjacent epithelial cells and represent the main "gate-keepers" of the paracellular route. Impaired TJ functionality results in increased permeation of the "pro-inflammatory" luminal contents to the circulation that induces local and systemic inflammatory and immune responses, ultimately triggering and/or perpetuating (chronic) systemic inflammatory disorders. Increased gut leakiness is associated with intestinal and systemic disease states such as inflammatory bowel disease and neurodegenerative diseases such as Parkinson's disease. Modulation of TJ dynamics is an appealing strategy aiming at inflammatory conditions associated with compromised intestinal epithelial function. Recently there has been a growing interest in nutraceuticals, particularly in non-digestible oligosaccharides (NDOs). NDOs confer innumerable health benefits via microbiome-shaping and gut microbiota-related immune responses, including enhancement of epithelial barrier integrity. Emerging evidence supports that NDOs also exert health-beneficial effects on microbiota independently via direct interactions with intestinal epithelial and immune cells. Among these valuable features, NDOs promote barrier function by directly regulating TJs via AMPK-, PKC-, MAPK-, and TLR-associated pathways. This review provides a comprehensive overview of the epithelial barrier-protective effects of different NDOs with a special focus on their microbiota-independent modulation of TJs.

Genome analysis and 2'-fucosyllactose utilization characteristics of a new Akkermansia muciniphila strain isolated from mice feces

Akkermansia muciniphila is considered to be a next-generation probiotic, and closely related to host metabolism and immune response. Compared with other probiotics, little is known about its genomic analysis. Therefore, further researches about isolating more A. muciniphila strains and exploring functional genes are needed. In the present study, a new strain isolated from mice feces was identified as A. muciniphila (Muc^X). Whole-genome sequencing and annotation revealed that Muc^X possesses key genes necessary for human milk oligosaccharides (HMO) utilization, including α-L-fucosidases, β-galactosidases, exo-α-sialidases, and β-acetylhexosaminidases. The complete metabolic pathways for γ-aminobutyric acid and squalene and genes encoding functional proteins, such as the outer membrane protein Amuc_1100, were annotated in the Muc^X genome. Comparative genome analysis was used to identify functional genes unique to Muc^X compared to six other A. muciniphila strains. Results showed Muc^X genome possesses unique genes, including sugar transporters and transferases. Single-strain incubation revealed faster utilization of 2'-fucosyllactose (2'-FL), galacto-oligosaccharides, and lactose by Muc^X than by A. muciniphila DSM 22959. This study isolated and identified an A. muciniphila strain that can utilize 2'-FL, and expolored the genes related to HMO utilization and special metabolites, which provided a theoretical basis for the further excavation of A. muciniphila function and the compound application with fucosylated oligosaccharides.

Phage Cocktail Targeting STEC O157:H7 Has Comparable Efficacy and Superior Recovery Compared with Enrofloxacin in an Enteric Murine Model

O157:H7 is the most important Shiga toxin-producing Escherichia coli (STEC) serotype in relation to public health. Given that antibiotics may contribute to the exacerbation of STEC-related disease and an increased frequency of antibiotic-resistant strains, bacteriophage (phage) therapy is considered a promising alternative. However, phage therapy targeting enteric pathogens is still underdeveloped with many confounding effects from the microbiota. Here we comprehensively compared the therapeutic efficacy of a phage cocktail with the antibiotic enrofloxacin in a mouse model of STEC O157:H7 EDL933 infection. Enrofloxacin treatment provided 100% survival and the phage cocktail treatment provided 90% survival. However, in terms of mouse recovery, the phage cocktail outperformed enrofloxacin in all measured outcomes. Compared with enrofloxacin treatment, phage treatment led to a faster elimination of enteric pathogens, decreased expression levels of inflammatory markers, increased weight gain, maintenance of a stable relative organ weight, and improved homeostasis of the gut microbiota. These results provide support for the potential of phage therapy to combat enteric pathogens and suggest that phage treatment leads to enhanced recovery of infected mice compared with antibiotics. IMPORTANCE With the increasing severity of antibiotic resistance and other adverse consequences, animal experiments and clinical trials investigating the use of phages for the control and prevention of enteric bacterial infections are growing. However, the effects of phages and antibiotics on organisms when treating intestinal infections have not been precisely studied. Here, we comprehensively compared the therapeutic efficacy of a phage cocktail to the antibiotic enrofloxacin in a mouse model of STEC O157:H7 EDL933 infection. We found that, despite a slightly lower protection rate, phage treatment contributed to a faster recovery of infected mice compared with enrofloxacin. These results highlight the potential benefits of phage therapy to combat enteric infections.

Sodium Humate Alleviates Enterotoxigenic Escherichia coli-Induced Intestinal Dysfunction via Alteration of Intestinal Microbiota and Metabolites in Mice

Enterotoxigenic Escherichia coli (ETEC) can damage intestinal epithelial barrier function and lead to serious intestinal diarrhea in newborns and young animals. Sodium humate (HNa) is natural organic bioactive compound possessing antibacterial, anti-inflammatory, and anti-diarrheal properties. This study investigated the alleviative potential of HNa on the impaired intestinal barrier and intestinal inflammation, and regulatory effects on gut microbiota and metabolites in ETEC K88 infected mice. A total of 30 female mice were randomly assigned into three groups. The mice in the control and ETEC groups were gavaged with 0.2 mL of sterile saline, while the mice in the ETEC + HNa group were gavaged with 0.2 mL of 5% HNa, daily. On day 8, the mice in ETEC and ETEC + HNa group were challenged with ETEC K88. The trial lasted for 12 days. HNa administration elevated ETEC K88-induced body weight loss and ameliorated jejunum and colon pathological injury. HNa also reduced the levels of pro-inflammatory cytokines in the serum, jejunum, and colon. Additionally, HNa reduced intestinal barrier damage by up-regulating the expression of tight junction proteins (TJPs) and mucosal repair factors. 16s rDNA gene sequencing results showed that HNa increased the abundance of beneficial bacteria Lactobacillus, Prevotella_9, and Odoribacter but decreased the abundance of pathogenic bacteria Escherichia and Gastranaerophilales in the feces of mice. Moreover, metabolomic analysis revealed that the concentrations of 15 metabolites, the pathways of protein digestion and absorption, and propanoic acid metabolism were changed by HNa administration. In conclusion, HNa could alleviate ETEC K88-induced intestinal dysfunction through restoring intestinal barrier integrity, modulating gut microbiota, and metabolites.

Modulation of Gut Microbiota and Immune System by Probiotics, Pre-biotics, and Post-biotics

The human gastrointestinal tract harbours a complex microbial community, which interacts with the mucosal immune system closely. Gut microbiota plays a significant role in maintaining host health, which could supply various nutrients, regulate energy balance, modulate the immune response, and defence against pathogens. Therefore, maintaining a favourable equilibrium of gut microbiota through modulating bacteria composition, diversity, and their activity is beneficial to host health. Several studies have shown that probiotics and pre-biotics could directly and indirectly regulate microbiota and immune response. In addition, post-biotics, such as the bioactive metabolites, produced by gut microbiota, and/or cell-wall components released by probiotics, also have been shown to inhibit pathogen growth, maintain microbiota balance, and regulate an immune response. This review summarises the studies concerning the impact of probiotics, pre-biotics, and post-biotics on gut microbiota and immune systems and also describes the underlying mechanisms of beneficial effects of these substances. Finally, the future and challenges of probiotics, pre-biotics, and post-biotics are proposed.

Protective Effect of Probiotics Isolated from Traditional Fermented Tea Leaves (Miang) from Northern Thailand and Role of Synbiotics in Ameliorating Experimental Ulcerative Colitis in Mice

This study aimed to investigate the protective effect of probiotics and synbiotics from traditional Thai fermented tea leaves (Miang) on dextran sulfate sodium (DSS)-induced colitis in mice, in comparison to sulfasalazine. C57BL/6 mice were treated with probiotics L. pentosus A14-6, CMY46 and synbiotics, L. pentosus A14-6 combined with XOS, and L. pentosus CMY46 combined with GOS for 21 days. Colitis was induced with 2% DSS administration for seven days during the last seven days of the experimental period. The positive group was treated with sulfasalazine. At the end of the experiment, clinical symptoms, pathohistological changes, intestinal barrier integrity, and inflammatory markers were analyzed. The probiotics and synbiotics from Miang ameliorated DSS-induced colitis by protecting body weight loss, decreasing disease activity index, restoring the colon length, and reducing pathohistological damages. Furthermore, treatment with probiotics and synbiotics improved intestinal barrier integrity, accompanied by lowing colonic and systemic inflammation. In addition, synbiotics CMY46 combined with GOS remarkedly elevated the expression of IL-10. These results suggested that synbiotics isolated from Miang had more effectiveness than sulfasalazine. Thereby, they could represent a novel potential natural agent against colonic inflammation.

Pediococcus pentosaceus IM96 Exerts Protective Effects against Enterohemorrhagic Escherichia coli O157:H7 Infection In Vivo

Enterohemorrhagic Escherichia coli (EHEC) is a notorious and prevalent foodborne pathogen which can cause serious intestinal diseases. The antagonistic activity of probiotics against EHEC is promising, but most of the studies concerning this subject have been carried out in vitro. Specifically, the interaction between Pediococcus pentosaceus and EHEC O157:H7 in vivo has not been reported yet. In this study, we investigated the protective effect of P. pentosaceus IM96 on EHEC O157:H7-infected female mice in vivo. The results demonstrated that P. pentosaceus IM96 reduced the level of pro-inflammatory factors and increased the level of anti-inflammatory factors of EHEC O157:H7-infected mice. Furthermore, P. pentosaceus IM96 alleviated intestinal mucosal damage and increased the level of MUC-2, tight junction (TJ) proteins, and short chain fatty acids (SCFAs). The intestinal microbial community structure and the diversity and richness of the microbiota were also changed by P. pentosaceus IM96 treatment. In summary, P. pentosaceus IM96 exerted protective effects against EHEC O157:H7 via alleviating intestinal inflammation, strengthening the intestinal barrier function, and regulating intestinal microbiota, suggesting that P. pentosaceus IM96 might serve as a potential microbial agent to prevent and treat intestinal diseases caused by EHEC O157:H7 infection in the future.

Xylo-oligosaccharide alleviates Salmonella induced inflammation by stimulating Bifidobacterium animalis and inhibiting Salmonella colonization

Xylo-oligosaccharide (XOS), which is considered as a potential prebiotic, exhibits multiple beneficial effects on modulation of gut microbiota, strength of intestinal barrier, and inhibition of intestinal inflammation. The objective of this study is to investigate whether XOS protects against Salmonella infection by modulating gut microbiota, enhancing the intestinal barrier, and resisting colonization. C57BL/6 male mice received water supplementation with 5% XOS for 14 days before Salmonella Typhimurium infection. The results showed that XOS suppressed the Salmonella-induced inflammation, but had limited effects on tight junction molecules and mRNA expression of mucus proteins, except for claudin-1 in the colon. Data of 16S rDNA sequencing indicated that XOS modulated gut microbiota composition by significantly stimulating Bifidobacterium animalis (B. animalis), and reducing Salmonella counts. Therefore, the potential protective effects of B. animalis against Salmonella challenge were investigated as well. Bifidobacterium animalis subsp lactis BB-12 (BB12), which could markedly increase in XOS, was selected to treat mice. Similarly, Salmonella-induced inflammatory reactions were alleviated by BB12 but tight junction molecules and mucin proteins in the colonic tissues were not affected. Administration of BB12 remarkably decreased the copies of Salmonella in cecal digesta post Salmonella infection. Additionally, the decrease concentrations of cecal propionate and total short-chain fatty acids (SCFAs) in Salmonella-infected mice were reversed by BB12 treatment, and propionate performed a strong inhibitory effect on Salmonella growth in vitro. Besides that, BB12 could directly restrict Salmonella proliferation in vitro. Moreover, BB12 reduced the adhesion ability of Salmonella on the Caco-2 cells model. Our results suggest that XOS could be considered as a candidate of functional food to protect against Salmonella infection by stimulating Bifidobacterium, which then resists Salmonella colonization by maintaining the intestinal SCFAs levels and suppressing adhesibility.

Anticandidal Activities by Lactobacillus Species: An Update on Mechanisms of Action

Lactobacilli are among the most studied bacteria in the microbiome of the orodigestive and genitourinary tracts. As probiotics, lactobacilli may provide various benefits to the host. These benefits include regulating the composition of the resident microbiota, preventing - or even potentially reverting- a dysbiotic state. Candida albicans is an opportunistic pathogen that can influence and be influenced by other members of the mucosal microbiota and, under immune-compromising conditions, can cause disease. Lactobacillus and Candida species can colonize the same mucosal sites; however, certain Lactobacillus species display antifungal activities that can contribute to low Candida burdens and prevent fungal infection. Lactobacilli can produce metabolites with direct anticandidal function or enhance the host defense mechanisms against fungi. Most of the Lactobacillus spp. anticandidal mechanisms of action remain underexplored. This work aims to comprehensively review and provide an update on the current knowledge regarding these anticandidal mechanisms.

Modulation of Gut Microbiota for the Prevention and Treatment of COVID-19

The gut microbiota is well known to exert multiple benefits on human health including protection from disease causing pathobiont microbes. It has been recognized that healthy intestinal microbiota is of great importance in the pathogenesis of COVID-19. Gut dysbiosis caused by various reasons is associated with severe COVID-19. Therefore, the modulation of gut microbiota and supplementation of commensal bacterial metabolites could reduce the severity of COVID-19. Many approaches have been studied to improve gut microbiota in COVID-19 including probiotics, bacterial metabolites, and prebiotics, as well as nutraceuticals and trace elements. So far, 19 clinical trials for testing the efficacy of probiotics and synbiotics in COVID-19 prevention and treatment are ongoing. In this narrative review, we summarize the effects of various approaches on the prevention and treatment of COVID-19 and discuss associated mechanisms.

Ginsenoside Rk3 alleviates gut microbiota dysbiosis and colonic inflammation in antibiotic-treated mice

Ginsenoside Rk3 is a natural prebiotic found in ginseng, has excellent pharmacological efficacy, especially antitumor effects, and can greatly benefit human health. Here, we investigated the impact of Rk3 intake on modulation of the gut microbiota and their metabolites as well as its effect on low-grade inflammation in mice. C57BL/6JFandd mice were administered different doses of Rk3 for two weeks after establishment of an antibiotic-mediated gut microbiota disturbance model. Interestingly, Rk3 intake induced substantial changes in the gut microbiota composition, enriched the Bacteroides, Alloprevotella and Blautia genera, and effectively ameliorated gut microbiota dysbiosis, with significantly decreased Firmicutes/Bacteroidetes ratios. These changes were accompanied by beneficial alterations in gut microbiota diversity and improved short-chain fatty acid levels. In addition, we found that Rk3 intervention repaired intestinal barrier dysfunction by increasing the expression of tight junction proteins (ZO-1, Occludin and Claudin-1), reducing colonic inflammatory cytokine levels, and suppressing TNF-α, IL-1β, and IL-6 overproduction. In conclusion, Rk3 improves intestinal inflammation and induces potentially beneficial changes in the gut microbiota, and these findings help elucidate host-microbe interactions.