Molecular Players Involved in the Interaction Between Beneficial Bacteria and the Immune System

Short-Chain Fatty Acids: Promising Therapeutic Targets for Respiratory Syncytial Virus Infection

The intestinal microbiota is a complex community of organisms present in the human gastrointestinal tract, some of which can produce short-chain fatty acids (SCFAs) through the fermentation of dietary fiber. SCFAs play a major role in mediating the intestinal microbiota's regulation of host immunity and intestinal homeostasis. Respiratory syncytial virus (RSV) can cause an imbalance between anti-inflammatory and proinflammatory responses in the host. In addition, changes in SCFA levels and the structure of the intestinal microbiota have been observed after RSV infection. Therefore, there may be a link between SCFAs and RSV infection, and SCFAs are expected to be therapeutic targets for RSV infection.

Effect of Lactic Acid Bacteria-Derived Postbiotic Supplementation on Tuberculosis in Wild Boar Populations

The Eurasian wild boar (Sus scrofa) is a key wildlife host for tuberculosis (TB) in central and southwestern Spain, posing a challenge to TB eradication in livestock. New strategies, including the use of beneficial microbes, are being explored to mitigate wildlife diseases. This study evaluated the effect of oral supplementation with postbiotic antimycobacterial metabolites produced using Ingulados' lactic acid bacteria (LAB) collection on TB development in wild boar. A total of 20 game estates in mid-western Spain were divided into two groups: one fed with standard feed containing the postbiotic product and a control group fed without postbiotics. Data were collected from wild boar during hunting events pre- and post-supplementation. The presence of TB-like lesions (TBLLs), lesion severity and seropositivity against Mycobacterium bovis were assessed. Postbiotic supplementation led to a 36.87% reduction in TBLLs and a 35.94% decrease in seropositivity. Notably, young wild boar showed a 64.72% reduction in TBLLs and an 81.80% drop in seropositivity, suggesting reduced transmission. These findings support the potential of postbiotics as a safe, feasible and sustainable tool to control TB in wild boar, offering a promising addition to broader TB eradication efforts.

Helicobacter pylori: Routes of Infection, Antimicrobial Resistance, and Alternative Therapies as a Means to Develop Infection Control

Helicobacter pylori (H. pylori) is a Gram-negative, spiral-shaped bacterium that colonizes the gastric epithelium and is associated with a range of gastrointestinal disorders, exhibiting a global prevalence of approximately 50%. Despite the availability of treatment options, H. pylori frequently reemerges and demonstrates increasing antibiotic resistance, which diminishes the efficacy of conventional therapies. Consequently, it is imperative to explore non-antibiotic treatment alternatives to mitigate the inappropriate use of antibiotics. This review examines H. pylori infection, encompassing transmission pathways, treatment modalities, antibiotic resistance, and eradication strategies. Additionally, it discusses alternative therapeutic approaches such as probiotics, anti-biofilm agents, phytotherapy, phototherapy, phage therapy, lactoferrin therapy, and vaccine development. These strategies aim to reduce antimicrobial resistance and enhance treatment outcomes for H. pylori infections. While alternative therapies can maintain low bacterial levels, they do not achieve complete eradication of H. pylori. These therapies are designed to bolster the immune response, minimize side effects, and provide gastroprotective benefits, rendering them suitable for adjunctive use alongside conventional treatments. Probiotics may serve as adjunctive therapy for H. pylori; however, their effectiveness as a monotherapy is limited. Photodynamic and phage therapies exhibit potential in targeting H. pylori infections, including those caused by drug-resistant strains, without the use of antibiotics. The development of a reliable vaccine is also critical for the eradication of H. pylori. This review identifies candidate antigens such as VacA, CagA, and HspA, along with various vaccine formulations, including vector-based and subunit vaccines. Some vaccines have demonstrated efficacy in clinical trials, while others have shown robust immune protection in preclinical studies. Nevertheless, each of the aforementioned alternative therapies requires thorough preclinical and clinical evaluation to ascertain their efficacy, side effects, cost-effectiveness, and patient compliance.

Role of immunomodulatory probiotics in alleviating bacterial diarrhea in piglets: a systematic review

Diarrhea is a common enteric disease in piglets that leads to high mortality and economic losses in swine production worldwide. Antibiotics are commonly used to prevent or treat diarrhea in piglets. However, irrational antibiotic use contributes to the development of resistance in bacteria and antibiotic residues in animal products, threatening public health, while causing gut microbiota dysbiosis and antibiotic-resistant bacterial infection in piglets. Therefore, the quest for alternative products (such as probiotics, prebiotics, organic acids, enzymes, essential oils, medium-chain fatty acids, zinc, and plant extracts) has recently been clearly emphasized through the increase in regulations regarding antibiotic use in livestock production. These antibiotic alternatives could lower the risk of antibiotic-resistant bacteria and meet consumer demand for antibiotic-free food. Several antibiotic alternatives have been proposed, including immunomodulatory probiotics, as candidates to reduce the need for antimicrobial therapy. Many studies have revealed that probiotics can avert and cure bacterial diarrhea by regulating the gut function and immune system of piglets. In this review, we focus on the major pathogenic bacteria causing piglet diarrhea, the research status of using probiotics to prevent and treat diarrhea, their possible mechanisms, and the safety issues related to the use of probiotics. Supplementation with probiotics is a possible alternative to antibiotics for the prevention or treatment of bacterial diarrhea in piglets. Furthermore, probiotics exert beneficial effects on feed efficiency and growth performance of piglets. Therefore, appropriate selection and strategies for the use of probiotics may have a positive effect on growth performance and also reduce diarrhea in piglets. This review provides useful information on probiotics for researchers, pig nutritionists, and the additive industry to support their use against bacterial diarrhea in piglets.

Microbial dysbiosis in systemic lupus erythematosus: a scientometric study

Introduction

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease. Mounting evidence suggests microbiota dysbiosis augment autoimmune response. This study aims to provide a systematic overview of this research field in SLE through a bibliometric analysis.

Methods

We conducted a comprehensive search and retrieval of literature related to microbial researches in SLE from the Web of Science Core Collection (WOSCC) database. The retrieved articles were subjected to bibliometric analysis using VOSviewer and Bibliometricx to explore annual publication output, collaborative patterns, research hotspots, current research status, and emerging trends.

Results

In this study, we conducted a comprehensive analysis of 218 research articles and 118 review articles. The quantity of publications rises annually, notably surging in 2015 and 2018. The United States and China emerged as the leading contributors in microbial research of SLE. Mashhad University of Medical Sciences had the highest publication outputs among the institutions. Frontiers in Immunology published the most papers. Luo XM and Margolles A were the most prolific and highly cited contributors among individual authors. Microbial research in SLE primarily focused on changes in microbial composition, particularly gut microbiota, as well as the mechanisms and practical applications in SLE. Recent trends emphasize "metabolites," "metabolomics," "fatty acids," "T cells," "lactobacillus," and "dietary supplementation," indicating a growing emphasis on microbial metabolism and interventions in SLE.

Conclusion

This study provides a thorough analysis of the research landscape concerning microbiota in SLE. The microbial research in SLE mainly focused on three aspects: microbial dysbiosis, mechanism studies and translational studies (microbiota-based therapeutics). It identifies current research trends and focal points, offering valuable guidance for scholars in the field.

Probiotics and their Beneficial Health Effects

Probiotics are living microorganisms that are present in cultured milk and fermented food. Fermented foods are a rich source for the isolation of probiotics. They are known as good bacteria. They have various beneficial effects on human health including antihypertensive effects, antihypercholesterolemic effects, prevention of bowel disease, and improving the immune system. Microorganisms including bacteria, yeast, and mold are used as probiotics but the major microorganisms that are used as probiotics are bacteria from the genus Lactobacillus, Lactococcus, Streptococcus, and Bifidobacterium. Probiotics are beneficial in the prevention of harmful effects. Recently, the use of probiotics for the treatment of various oral and skin diseases has also gained significant attention. Clinical studies indicate that the usage of probiotics can alter gut microbiota composition and provoke immune modulation in a host. Due to their various health benefits, probiotics are attaining more interest as a substitute for antibiotics or anti-inflammatory drugs leading to the growth of the probiotic market.

Impacts of gut microbiota alteration on age-related chronic liver diseases

The gut microbiome and its metabolites are involved in developing and progressing liver disease. Various liver illnesses, such as non-alcoholic fatty liver disease, alcoholic liver disease, hepatitis C, and hepatocellular carcinoma, are made worse and have worse prognoses with aging. Dysbiosis, which occurs when the symbiosis between the microbiota and the host is disrupted, can significantly negatively impact health. Liver disease is linked to qualitative changes, such as an increase in hazardous bacteria and a decrease in good bacteria, as well as quantitative changes in the overall amount of bacteria (overgrowth). Intestinal gut microbiota and their metabolites may lead to chronic liver disease development through various mechanisms, such as increasing gut permeability, persistent systemic inflammation, production of SCFA, bile acids, and alteration in metabolism. Age-related gut dysbiosis can disrupt the communication between gut microbiota and the host, impacting the host's health and lifespan. With aging, a gradual loss of the ability to maintain homeostasis because of structural alteration and gut dysbiosis leads to the disease progression in end-stage liver disease. Recently chronic liver disease has been identified as a global problem. A large number of patients are receiving liver transplants yearly. Thereby gut microbiome ecology is changing in the patients of the gut due to the changes in pathophysiology during the preoperative stage. The present review summarises the age-associated dysbiosis of gut microbial composition and its contribution to chronic liver disease. This review also provides information about the impact of liver transplant on the gut microbiome and possible disadvantageous effects of alteration in gut microbiota.

Iron overload induces colitis by modulating ferroptosis and interfering gut microbiota in mice

BACKGROUND

Iron plays a pivotal role in various physiological processes, including intestinal inflammation, ferroptosis, and the modulation of the gut microbiome. However, the way these factors interact with each other is unclear.

METHODS

Mice models were fed with low, normal and high iron diets to assess their impacts on colitis, ferroptosis and gut microbiota. Untargeted fecal metabolomics analysis, 16S rRNA sequencing, histopathology analysis, real-time quantitative PCR and western blot were performed to analyze the differences in the intestinal inflammatory response and understanding its regulatory mechanisms between low, normal and high iron groups.

RESULTS

The iron overload changed the serum iron, colon iron and fecal iron. In addition, the iron overload induced the colitis, induced the ferroptosis and altered the microbiome composition in the fecal of mice. By using untargeted fecal metabolomics analysis to screen of metabolites in the fecal, we found that different metabolomics profiles in the fecal samples between iron deficiency, normal iron and iron overload groups. The correlation analysis showed that both of iron deficiency and overload were closely related to Dubosiella. The relationship between microbial communities (e.g., Akkermansia, Alistipes, and Dubosiella) and colitis-related parameters was highly significant. Additionally, Alistipes and Bacteroides microbial communities displayed a close association with ferroptosis-related parameters. Iron overload reduced the concentration of metabolites, which exert the anti-inflammatory effects (e.g., (+)-.alpha.-tocopherol) in mice. The nucleotide metabolism, enzyme metabolism and metabolic diseases were decreased and the lipid metabolism was increased in iron deficiency and iron overload groups compared with normal iron group.

CONCLUSION

Iron overload exacerbated colitis in mice by modulating ferroptosis and perturbing the gut microbiota. Iron overload-induced ferroptosis was associated with NRF2/GPX-4 signaling pathway. Specific microbial taxa and their associated metabolites were closely intertwined with both colitis and ferroptosis markers.

Evaluation of isolated probiotics on the efficacy of immune system in male and female Wistar rats

Probiotics were isolated from fruits and vegetables. Microscopic, biochemical, and molecular tests were carried out for the characterization of strains of probiotics. To assess the effects of isolated probiotics on immunity, male and female (15 + 15) Wistar rats (n = 3) were randomly distributed into 5 groups: 0-day, negative control, positive control (commercially available Lactobacillus acidophilus-14), laboratory isolated probiotics with accession numbers; Lactobacillus plantarum (MZ707748) and Lactobacillus plantarum (MZ729681), respectively. After hematological investigations, the amounts of IgA and IgG in male and female groups were significantly different (p < 0.05). At the same time, the values of Alanine-transaminase (ALT) and Aspartate-aminotransferase (AST) in both genders were average, and there were no differences (p > 0.05). Male probiotic-treated groups had decreased levels of interleukin-6, bilirubin, and creatinine, but female probiotic-treated groups had a slight rise in bilirubin and creatinine values (p = 0.05). Cellular blood count levels of Hematocrit (HCT) and white blood cells (WBC) in male groups showed considerable differences (p < 0.05), while there were no differences (p > 0.05) in female groups. Levels of Red blood cells (RBC) and mean corpuscular hemoglobin concentration (MCHC) showed distinct changes (p < 0.05) in female groups, while these values were insignificant changes (p > 0.05) among male groups. There were considerable differences between the control and groups that were given probiotics. Histopathological results showed no damage to the liver and thymus. A fecal examination of rats was used to examine the viability and survival of Lactobacilli. Based on blood tests, it was observed that the immune system was boosted and improved in probiotic-treated groups compared to control groups.

Phenotypic Traits and Probiotic Functions of Lactiplantibacillus plantarum Y42 in Planktonic and Biofilm Forms

Bacteria in planktonic and biofilm forms exhibit different phenotypic properties. In this study, the phenotypic traits and probiotic functions of Lactiplantibacillus plantarum Y42 in planktonic and biofilm forms were assessed. After 36 h of static culture, scanning electron microscopy and confocal laser scanning microscopy showed that the L. plantarum Y42 bacterial cells contained interconnected adhesive matter on the surface, forming a ~18 μm layer of dense biofilms. The surface properties of L. plantarum Y42 in biofilm form, including autoaggregation ability, hydrophobicity, acid-base charge, and adhesiveness, were all higher than those in the planktonic form. Biofilm L. plantarum Y42 showed a higher tolerance to adverse environmental conditions and a higher survival rate, enzymatic activity, and integrity after vacuum lyophilization. And biofilm L. plantarum Y42 had higher adhesion to human enterocyte HT-29 cell monolayers, inhibited the expressions of proinflammatory factors IL-6 and TNF-α, and promoted the expressions of the anti-inflammatory factor IL-10 and barrier proteins Claudin-1 and Occludin. In addition, L. plantarum Y42 in biofilm form can inhibit the adhesion and invasion of Listeria monocytogenes ATCC 19115 to HT-29 cell monolayers and is more effective in relieving the inflammatory reactions and injuries of HT-29 cells caused by L. monocytogenes ATCC 19115. In conclusion, L. plantarum Y42 in biofilm form exhibited better probiotic functions compared to that in planktonic form. This indicated that L. plantarum Y42 can form biofilms to enhance its probiotic functions, which provided a theoretical basis for better development and utilization of L. plantarum Y42.

Dietary glutamate enhances intestinal immunity by modulating microbiota and Th17/Treg balance-related immune signaling in piglets after lipopolysaccharide challenge

The purpose of this study was to explore the effects of glutamate on piglet growth performance and intestinal immunity function, and to further elucidate its mechanism. In a 2 × 2 factorial design involving immunological challenge (lipopolysaccharide (LPS) or saline) and diet (with or without glutamate), twenty-four piglets were randomly assigned to four groups, each with 6 replicates. Piglets were fed with a basal or glutamate diet for 21 d before being injected intraperitoneally with LPS or saline. Piglet's intestinal samples were collected 4 h after injection. Results showed that glutamate increased daily feed intake, average daily gain, villus length, villus area, and villus length to crypt depth ratio (V/C), and decreased the crypt depth (P < 0.05). Furthermore, glutamate increased the mRNA expression of forkhead box P3 (FOXP3), a signal transducer and activator of transcription 5 (STAT5) and transforming growth factor beta, while decreasing the mRNA expression of RAR-related orphan receptor c and STAT3. Glutamate increased interleukin-10 (IL-10) mRNA expression while decreasing the mRNA expression of IL-1β, IL-6, IL-8, IL-17, IL-21, and tumor necrosis factor-α. At the phylum level, glutamate increased the Actinobacteriota abundance and Firmicutes-to-Bacteroidetes ratio while decreasing Firmicutes abundance. At the genus level, glutamate improved the abundance of beneficial bacteria (e.g., Lactobacillus, Prevotellaceae-NK3B31-group, and UCG-005). Furthermore, glutamate increased the concentrations of short-chain fatty acids (SCFAs). Correlation analysis revealed that the intestinal microbiota is closely related to Th17/Treg balance-related index and SCFAs. Collectively, glutamate can improve piglet growth performance and intestinal immunity by modulating gut microbiota and Th17/Treg balance-related signaling pathways.

Role of Dietary Defatted Rice Bran in the Modulation of Gut Microbiota in AOM/DSS-Induced Colitis-Associated Colorectal Cancer Rat Model

Defatted rice bran (DRB) is a by-product of rice bran derived after the oil extraction. DRB contains several bioactive compounds, including dietary fiber and phytochemicals. The supplementation with DRB manifests chemopreventive effects in terms of anti-chronic inflammation, anti-cell proliferation, and anti-tumorigenesis in the azoxymethane (AOM) and dextran sodium sulfate (DSS)-induced colitis-associated colorectal cancer (CRC) model in rats. However, little is known about its effect on gut microbiota. Herein, we investigated the effect of DRB on gut microbiota and short chain fatty acid (SCFA) production, colonic goblet cell loss, and mucus layer thickness in the AOM/DSS-induced colitis-associated CRC rat model. The results suggested that DRB enhanced the production of beneficial bacteria (Alloprevotella, Prevotellaceae UCG-001, Ruminococcus, Roseburia, Butyricicoccus) and lessened the production of harmful bacteria (Turicibacter, Clostridium sensu stricto 1, Escherichia-Shigella, Citrobacter) present in colonic feces, mucosa, and tumors. In addition, DRB also assisted the cecal SCFAs (acetate, propionate, butyrate) production. Furthermore, DRB restored goblet cell loss and improved the thickness of the mucus layer in colonic tissue. These findings suggested that DRB could be used as a prebiotic supplement to modulate gut microbiota dysbiosis, which decreases the risks of CRC, therefore encouraging further research on the utilization of DRB in various nutritional health products to promote the health-beneficial bacteria in the colon.

The Effect of the Gut Microbiota on Transplanted Kidney Function

The intestinal microflora is extremely important, not only in the processes of absorption, digestion and biosynthesis of vitamins, but also in shaping the immune and cognitive functions of the human body. Several studies demonstrate a correlation between microbiota composition and such events as graft rejection, kidney interstitial fibrosis, urinary tract infections, and diarrhoea or graft tolerance. Some of those changes might be directly linked with pathologies such as colonization with pathogenic bacterial strains. Gut microbiota composition also plays an important role in metabolic complications and viral infections after transplantation. From the other side, gut microbiota might induce graft tolerance by promotion of T and B regulatory cells. Graft tolerance induction is still an extremely important issue regarding transplantology and might allow the reduction or even avoidance of immunosuppressive treatment. Although there is a rising evidence of the pivotal role of gut microbiota in aspects of kidney transplantation there is still a lack of knowledge on the direct mechanisms of microbiota action. Furthermore, some of those negative effects could be reversed by probiotics of faecal microbiota trapoinsplantation. While diabetes and hypertension as well as BKV and CMV viremia are common and important complications of transplantation, both worsening the graft function and causing systemic injuries, it opens up potential clinical treatment options. As has been also suggested in the current review, some bacterial subsets exhibit protective properties. However, currently, there is a lack of evidence on pro- and prebiotic supplementation in kidney transplant patients. In the current review, we describe the effect of the microbiota on the transplanted kidney in renal transplant recipients.

Chinese patent medicine shouhui tongbian capsule attenuated loperamide-induced constipation through modulating the gut microbiota in rat

ETHNOPHARMACOLOGICAL RELEVANCE

Shouhui tongbian capsule (SHTC) is a commercial Chinese patent medicine used in the treatment of constipation. However, its mechanism of action remains unclear.

AIM OF THE STUDY

The present study was undertaken to assess SHTC relieved effects on the clinical symptoms of loperamide (LOP) induced constipation in Sprague Dawley (SD) rat model and to clarify the relationship between the protective effect of SHTC on constipation and the gut microbiota.

MATERIALS AND METHODS

Constipation male SD rats models were induced with solution of LOP (1.5 mg/kg bw), and rats were treated with an oral dose of SHTC (35, 70 mg/kg bw) three times a day after successful modeling. All rats were assessed weekly by change in body weight, gastric emptying rate, fecal moisture content and wet/dry weight. Hematoxylin and eosin (H&E) were used to observe parts of the rats small intestine. The gut microbiota in colonic contents was analyzed using 16SrRNA gene sequencing. Contents of short-chain fatty acids (SCFAs) were analyzed by gas chromatography-mass spectrometer (GCMS).

RESULTS

The results confirmed the therapeutic effects of SHTC on constipation. Specifically, SHTC could alleviate the decrease in body weight, gastric emptying rate and fecal moisture content caused by LOP-induced constipation. The pathological damage of small intestine was significantly improved by H&E staining. Notably, SHTC increased the relative abundances of Lactobacillus and the ratio of Firmicutes to Bacteroides (F/B). In addition, the content of acetic acid and propionic acid was significantly increased in constipated rats fed with SHTC.

CONCLUSION

SHTC could ameliorate the development of LOP-induced constipation in rats by remodeling the structure of gut microbial community and regulating production of intestinal metabolites.

The gut microbiota of silkworm are altered by antibiotic exposure

In recent years, antibiotics have frequently been detected in soil, lakes, and rivers. Antibiotic residues in the environment may alter microbial structure and cause bacterial resistance, but their effect on interactions among host microbiota is still poorly understood. To investigate this issue, here we used silkworm (Bombyx mori) fed on antibiotic-treated mulberry leaf as a model to explore the effects of antibiotic exposure on gut bacteria and fungi. We observed that elimination of fungi significantly reduced bacterial richness and diversity in silkworm intestine after exposure to the antifungal amphotericin B, while the elimination of bacteria dramatically increased the richness and diversity of fungi after exposure to the antibacterial ampicillin-streptomycin. Thus, antibiotic-treated mulberry leaf significantly altered the community structure of microbiota in the gut of silkworm. Clearance of gut bacteria enhanced the correlation between gut fungi and leaf-derived fungi, while clearance of gut fungi promoted abnormal proliferation of gut bacteria. These data provide a simple model to explore the comprehensive effect of diet-derived bacteria, fungi, and antibiotics on gut microbiota.

Probiotics as multifaceted oral vaccines against colon cancer: A review

Probiotics are known as the live microorganisms that, upon adequate administration, elicit a health beneficial response inside the host. The probiotics are known as immunomodulators and exhibit anti-tumor properties. Advanced research has explored the potential use of probiotics as the oral vaccines without the latent risks of pathogenicity. Probiotic-based oral vaccines are known to induce mucosal immunity that prevents the host from several enteric infections. Probiotic bacteria have the ability to produce metabolites in the form of anti-inflammatory cytokines, which play an important role in the prevention of carcinogenesis and in the activation of the phagocytes that eliminate the preliminary stage cancer cells. This review discusses the advantages and disadvantages of using the oral probiotic vaccines as well as the mechanism of action of probiotics in colon cancer therapy. This review also employs the use of “PROBIO” database for selecting certain probiotics with immunomodulatory properties. Furthermore, the use of several probiotic bacteria as anti-colon cancer adjuvants has also been discussed in detail. Because the current studies and trials are more focused on using the attenuated pathogens instead of using the probiotic-based vaccines, future studies must involve the advanced research in exploiting the potential of several probiotic strains as adjuvants in cancer therapies.

Effects of dietary supplement with a Chinese herbal mixture on growth performance, antioxidant capacity, and gut microbiota in weaned pigs

Weaning stress decreases the growth performance of piglets and is one of the main concerns of pig industries. Traditional Chinese herbal medicines have been used to reduce the adverse effects of weaning stress as both nutritional supplements and antibiotic substitutes. This study aimed to evaluate the effects of a Chinese herbal mixture (Kangtaile, which contained Paeonia lactiflora, licorice, dandelion, and tea polyphenols) on the growth performances, immune response, antioxidant capacity, and intestinal microbiota of weaned pigs. A total of 400 weaned pigs [Duroc × (Landrace × Yorkshire)] were randomly allocated into one of four treatments: the CON group, fed with basic diet; the HM1 group, fed with basal diet supplemented with 0.5 g herbal mixture/kg diet; the HM2 group, fed with basal diet supplemented with 1.0 g herbal mixture/kg diet; or the HM3 group, fed with basal diet supplemented with 1.5 g herbal mixture/kg diet. The results revealed that dietary supplementation with the herbal mixture for 28 days improved average daily gain and feed conversion ratio, while decreased the diarrhea rate of weaned pigs. Moreover, dietary supple-mentation with the herbal mixture improved the antioxidant capacity through increasing the activity of catalase (CAT) and the total antioxidant capacity (T-AOC) level, while decreasing the concentration of malondialdehyde (MDA) in the serum. Pigs supplemented with herbal mixture presented an increased serum immunoglobulin (Ig)M level on day 14 compared with control pigs. The herbal mixture altered the composition of intestinal microbiota by influencing the relative abundances of Firmicutes and Bacteroidetes at the phylum level. The relative abundances of the Firmicutes and Bacteroidetes were significantly related to the body weight gain of pigs. In conclusion, supplementation of herbal mixture to the diet improved growth performance, immunity, and antioxidant capacity and modified the composition of intestinal microbiota in weaning pigs. This study provided new insights into the nutritional regulation effects of the herbal mixtures on weaned pigs.

Small nucleolar RNAs and SNHGs in the intestinal mucosal barrier: Emerging insights and current roles

BACKGROUND

Previous studies have focused on the involvement of small nucleolar RNAs (snoRNAs) and SNHGs in tumor cell proliferation, apoptosis, invasion, and metastasis via multiple pathways, including phosphatidylinositol-3-kinase/protein kinase B (PI3K/AKT), Wnt/β catenin, and mitogen-activated protein kinase (MAPK). These molecular mechanisms affect the integrity of the intestinal mucosal barrier.

AIM OF REVIEW

Current evidence regarding snoRNAs and SNHGs in the context of the mucosal barrier and modulation of homeostasis is fragmented. In this review, we collate the established information on snoRNAs and SNHGs as well as discuss the major pathways affecting the mucosal barrier.

KEY SCIENTIFIC CONCEPTS OF REVIEW

Intestinal mucosal immunity, microflora, and the physical barrier are altered in non-neoplastic diseases such as inflammatory bowel diseases. Dysregulated snoRNAs and SNHGs may impact the intestinal mucosal barrier to promote the pathogenesis and progression of multiple diseases. SnoRNAs or SNHGs has been shown to be associated with poor disease behaviors, indicating that they may be exploited as prognostic biomarkers. Additionally, clarifying the complicated interactions between snoRNAs or SNHGs and the mucosal barrier may provide novel insights for the therapeutic treatment targeting strengthen the intestinal mucosal barrier.

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.

The toxic effects of endocrine disrupting chemicals (EDCs) on gut microbiota: Bisphenol A (BPA). A review

BACKGROUND

Bisphenol A (BPA), an important industrial material widely applied in daily products, is considered an endocrine-disrupting chemical that may adversely affect humans. Growing evidence have shown that intestinal bacterial alterations caused by BPA exposure play an important role in several local and systemic diseases.

AIM OF THE STUDY

finding evidence that BPA-induced alterations in gut microbiota composition and activity may perturb its role on human health.

RESULTS

evidence from several experimental settings show that both low and high doses of BPA, interfere with the hormonal, homeostatic and reproductive systems in both animals and human systems. Moreover, it has recently been classified as an environmental obesogenic, with metabolic-disrupting effects on lipid metabolism and pancreatic b-cell functions. Several evidence characterize PBA as an environmental contributor to type II diabetes, metabolic syndrome, and obesity. However, the highest estimates of the exposure derived from foods alone or in combination with other sources are 3 to 5 times below the new tolerable daily intake (TDI) value, today reduced by the European Food Safety Authority (EFSA) experts from 50 micrograms per kilogramme of bodyweight per day (µg/kg bw/day) to 4 µg/kg bw/day.

CONCLUSIONS

Considering estimates for the total amount of BPA that can be ingested daily over a lifetime, many International Health Authorities conclude that dietary exposure of adult humans to BPA does not represent a risk to consumers' health, declaring its safety due to very-low established levels in food and water and declare any appreciable health risk.

Modulation of lymphocyte subpopulations in the small intestine of mice treated with probiotic bacterial strains and infected with Trichinella spiralis

AIMS

To study the local intestinal lymphocyte immunity in mice with trichinellosis affected by probiotic bacteria.

METHODS AND RESULTS

Enterococcus faecium CCM8558, E. durans ED26E/7, Limosilactobacillus fermentum CCM7421 and Lactiplantibacillus plantarum 17L/1 were administered daily (10⁹ CFU.ml^-1 ) and mice were infected with Trichinella spiralis (400 larvae) on 7^th day of treatment. T. spiralis infection significantly inhibited lymphocyte subpopulations from 5 to 25 days post infection (dpi). L. fermentum CCM7421 and L. plantarum 17L/1 restored the CD4+T cell numbers in the epithelium and lamina propria at control level from 11 dpi. All strains stimulated the CD8+T cells numbers in infected mice, which were restored in the lamina propria on 11 dpi and in the epithelium only on 32 dpi. B cells (CD19+) inhibition after T. spiralis infection was not affected by treatment till 25dpi.

CONCLUSIONS

The strain-specific immunomodulatory effect of tested bacteria was confirmed. L. fermentum CCM7421 and L. plantarum 17L/1 showed the greatest immunomodulatory potential on CD4+ and CD8+T lymphocytes in trichinellosis. E. faecium CCM8558 and E. durans ED26E/7 activated only CD8+T cells in the lamina propria.

SIGNIFICANCE AND IMPACT OF STUDY

Positive modulation of the gut lymphocyte immunity in T. spiralis infection with bacterial strains showed their beneficial effect in the host's antiparasitic defense.

Natural compounds as safe therapeutic options for ulcerative colitis

Ulcerative colitis (UC) is a chronic inflammatory bowel disease of unknown etiology. Several conventional treatments for UC such as corticosteroids, immunosuppressive agents, tumor necrosis factor antagonist, integrin blockers, and interleukin antagonist, and salicylates are available but are associated with the various limitations and side-effects. None of the above treatments helps to achieve the ultimate goal of the therapy, i.e., maintenance of remission in the long-term. Natural remedies for the treatment of UC show comparatively less side effects as compared to conventional approaches, and affordable. The current review presents details on the role of herbal drugs in the treatment and cure of UC. Google, PubMed, Web of Science, and Scopus portals have been searched for potentially relevant literature to get the latest developments and updated information related to use of natural drugs in the treatment of UC. Natural products have been used over centuries to treat UC. Some of the essential herbal constituents exhibiting antiulcerogenic activity include gymnemic acid (Gymnema sylvestre), shagoal (Zingiber officinale), catechin (Camellia sinensis), curcumin (Curcuma longa), arctigenin (Arctium lappa), and boswellic acid (Boswellia serrata). Although many plant-derived products have been recommended for UC, further research to understand the exact molecular mechanism is still warranted to establish their usefulness clinically.

Effects of Loigolactobacillus coryniformis K8 CECT 5711 on the Immune Response of Elderly Subjects to COVID-19 Vaccination: A Randomized Controlled Trial

Elderly people are particularly vulnerable to COVID-19, with a high risk of developing severe disease and a reduced immune response to the COVID-19 vaccine. A randomized, placebo-controlled, double-blind trial to assess the effect of the consumption of the probiotic Loigolactobacillus coryniformis K8 CECT 5711 on the immune response generated by the COVID-19 vaccine in an elderly population was performed. Two hundred nursing home residents >60 yrs that had not COVID-19 were randomized to receive L. coryniformis K8 or a placebo daily for 3 months. All volunteers received a complete vaccination schedule of a mRNA vaccine, starting the intervention ten days after the first dose. Specific IgG and IgA antibody levels were analyzed 56 days after the end of the immunization process. No differences between the groups were observed in the antibody levels. During the intervention, 19 subjects had COVID-19 (11 receiving K8 vs. 8 receiving placebo, p = 0.457). Subgroup analysis in these patients showed that levels of IgG were significantly higher in those receiving K8 compared to placebo (p = 0.038). Among subjects >85 yrs that did not get COVID-19, administration of K8 tended to increase the IgA levels (p = 0.082). The administration of K8 may enhance the specific immune response against COVID-19 and may improve the COVID-19 vaccine-specific responses in elderly populations.

Evaluation of tolerance to artificial gastroenteric juice and fermentation characteristics of Lactobacillus strains isolated from human

Fifty-seven strains of Lactobacillus were isolated from fecal samples of healthy young people in Tibet, Xinjiang, and Inner Mongolia using pure culture methods. Lactobacillus ruminis and Lactobacillus gasseri were the dominant Lactobacillus species isolated from the intestinal microflora, accounting for 54.4% and 14.0% of the total isolates, respectively. Isolated strains were identified by 16S rRNA sequencing, and their tolerance to gastric acid and bile salt, and fermentation characteristics were evaluated. The results of experiments in vitro showed that nine of the isolated strains of Lactobacillus grew well at pH 3.0. After 11 h of incubation in artificial digestive juices, the isolated L. plantarum and the control strain L. plantarum P8 still had high survival rates. Most of the isolates and control isolates have strong tolerance to bile salts. The evaluation of fermentation characteristics indicated that the ability of the intestinal Lactobacillus to ferment skimmed milk was lower than that of the reference L. plantarum P8. In the process of storage, the viable count of screened isolates of human origin in fermented milk decreased to some extent, but remained above 7.01 ± 0.22 log CFU/ml, showing good storage characteristics.

Therapeutic Advances in Gut Microbiome Modulation in Patients with Inflammatory Bowel Disease from Pediatrics to Adulthood

There is mounting evidence that the gut microbiota plays an important role in the pathogenesis of inflammatory bowel disease (IBD). For the past decade, high throughput sequencing-based gut microbiome research has identified characteristic shifts in the composition of the intestinal microbiota in patients with IBD, suggesting that IBD results from alterations in the interactions between intestinal microbes and the host’s mucosal immune system. These studies have been the impetus for the development of new therapeutic approaches targeting the gut microbiome, such as nutritional therapies, probiotics, fecal microbiota transplant and beneficial metabolic derivatives. Innovative technologies can further our understanding of the role the microbiome plays as well as help to evaluate how the different approaches in microbiome modulation impact clinical responses in adult and pediatric patients. In this review, we highlight important microbiome studies in patients with IBD and their response to different microbiome modulation therapies, and describe the differences in therapeutic response between pediatric and adult patient cohorts.

Yin and Yang of Biofilm Formation and Cyclic di-GMP Signaling of the Gastrointestinal Pathogen Salmonella enterica Serovar Typhimurium

Within the last 60 years, microbiological research has challenged many dogmas such as bacteria being unicellular microorganisms directed by nutrient sources; these investigations produced new dogmas such as cyclic diguanylate monophosphate (cyclic di-GMP) second messenger signaling as a ubiquitous regulator of the fundamental sessility/motility lifestyle switch on the single-cell level. Successive investigations have not yet challenged this view; however, the complexity of cyclic di-GMP as an intracellular bacterial signal, and, less explored, as an extracellular signaling molecule in combination with the conformational flexibility of the molecule, provides endless opportunities for cross-kingdom interactions. Cyclic di-GMP-directed microbial biofilms commonly stimulate the immune system on a lower level, whereas host-sensed cyclic di-GMP broadly stimulates the innate and adaptive immune responses. Furthermore, while the intracellular second messenger cyclic di-GMP signaling promotes bacterial biofilm formation and chronic infections, oppositely, Salmonella Typhimurium cellulose biofilm inside immune cells is not endorsed. These observations only touch on the complexity of the interaction of biofilm microbial cells with its host. In this review, we describe the Yin and Yang interactive concepts of biofilm formation and cyclic di-GMP signaling using S. Typhimurium as an example.

Wildlife symbiotic bacteria are indicators of the health status of the host and its ecosystem

Lactic acid bacteria (LAB) are gut symbionts that can be used as a model to understand the host-microbiota crosstalk under unpredictable environmental conditions such as wildlife ecosystems. The aim of this study was to determine whether viable LAB can be informative of the health status of wild boar populations. We monitored the genotype and phenotype of LAB based on markers that included safety and phylogenetic origin, antibacterial activity and immunomodulatory properties. A LAB profile dominated by lactobacilli appears to stimulate protective immune responses and relates to strains widely used as probiotics, resulting in a potentially healthy wildlife population whereas microbiota overpopulated by enterococci was observed in a hostile environment. These enterococci were closely related to pathogenic strains that have developed mechanisms to evade innate immune system, posing a potential risk for the host health. Furthermore, our LAB isolates displayed antibacterial properties in a species-dependent manner. Nearly all of them were able to inhibit bacterial pathogens, raising the possibility of using them as a la carte antibiotic alternative in the unexplored field of wildlife disease mitigation. Our study highlights that microbiological characterization of LAB is a useful indicator of wildlife health status and the ecological origin from which they derive. Significance Statement The wildlife symbiotic microbiota is an important component to the greater for greater diversity and functionality of their bacterial populations, influencing the host health and adaptability to its ecosystem. Although many microbes are partly responsible for the development of multiple physiological processes, only certain bacterial groups such as lactic acid bacteria (LAB) have the capacity to overpopulate the gut, promoting health (or disease) when specific genetic and environmental conditions are present. LAB have been exploited in many ways due to their probiotic properties, in particular lactobacilli, however their relationship with wildlife gut-associated microbiota hosts remains to be elucidated. On the other hand, it is unclear whether LAB such as enterococci, which have been associated with detrimental health effects, could lead to disease. These important questions have not been properly addressed in the field of wildlife, and therefore, should be clearly attained.

A Janus-Faced Bacterium: Host-Beneficial and -Detrimental Roles of Cutibacterium acnes

The bacterial species Cutibacterium acnes (formerly known as Propionibacterium acnes) is tightly associated with humans. It is the dominant bacterium in sebaceous regions of the human skin, where it preferentially colonizes the pilosebaceous unit. Multiple strains of C. acnes that belong to phylogenetically distinct types can co-exist. In this review we summarize and discuss the current knowledge of C. acnes regarding bacterial properties and traits that allow host colonization and play major roles in host-bacterium interactions and also regarding the host responses that C. acnes can trigger. These responses can have beneficial or detrimental consequences for the host. In the first part of the review, we highlight and critically review disease associations of C. acnes, in particular acne vulgaris, implant-associated infections and native infections. Here, we also analyse the current evidence for a direct or indirect role of a C. acnes-related dysbiosis in disease development or progression, i.e., reduced C. acnes strain diversity and/or the predominance of a certain phylotype. In the second part of the review, we highlight historical and recent findings demonstrating beneficial aspects of colonization by C. acnes such as colonization resistance, immune system interactions, and oxidant protection, and discuss the molecular mechanisms behind these effects. This new insight led to efforts in skin microbiota manipulation, such as the use of C. acnes strains as probiotic options to treat skin disorders.

Probiotic Bacteria and Their Cell Walls Induce Th1-Type Immunity Against Salmonella Typhimurium Challenge

Probiotics have been associated with a variety of health benefits. They can act as adjuvant to enhance specific immune response. Bacterial cell wall (CW) molecules are key structures that interact with host receptors promoting probiotic effects. The adjuvant capacity underlying this sub-cellular fraction purified from Lactobacillus casei CRL431 and L. paracasei CNCMI-1518 remains to be characterized. We interrogated the molecular and cellular events after oral feeding with probiotic-derived CW in addition to heat-inactivated Salmonella Typhimurium and their subsequent protective capacity against S. Typhimurium challenge. Intact probiotic bacteria were orally administered for comparison. We find that previous oral feeding with probiotics or their sub-cellular fraction reduce bacterial burden in spleen and liver after Salmonella challenge. Antibody responses after pathogen challenge were negligible, characterized by not major changes in the antibody-mediated phagocytic activity, and in the levels of total and Salmonella-specific intestinal sIgA and serum IgG, respectively. Conversely, the beneficial effect of probiotic-derived CW after S. Typhimurium challenge were ascribed to a Th1-type cell-mediated immunity which was characterized by augmentation of the delayed-type hypersensitivity response. The cell-mediated immunity associated with the oral feeding with probiotic-derived CW was accompanied with a Th1-cell polarizing cytokines, distinguished by increase IFN-γ/IL-4 ratio. Similar results were observed with the intact probiotics. Our study identified molecular events associated with the oral administration of sub-cellular structures derived from probiotics and their adjuvant capacity to exert immune modulatory function.

Immunomodulatory streptococci that inhibit CXCL8 secretion and NFκB activation are common members of the oral microbiota

Introduction

Oral tissues are generally homeostatic despite exposure to many potential inflammatory agents including the resident microbiota. This requires the balancing of inflammation by regulatory mechanisms and/or anti-inflammatory commensal bacteria. Thus, the levels of anti-inflammatory commensal bacteria in resident populations may be critical in maintaining this homeostatic balance.

Hypothesis/Gap Statement

The incidence of immunosuppressive streptococci in the oral cavity is not well established. Determining the proportion of these organisms and the mechanisms involved may help to understand host-microbe homeostasis and inform development of probiotics or prebiotics in the maintenance of oral health.

Aim

To determine the incidence and potential modes of action of immunosuppressive capacity in resident oral streptococci.

Methodology

Supragingival plaque was collected from five healthy participants and supragingival and subgingival plaque from five with gingivitis. Twenty streptococci from each sample were co-cultured with epithelial cells±flagellin or LL-37. CXCL8 secretion was detected by ELISA, induction of cytotoxicity in human epithelial cells by lactate dehydrogenase release and NFκB-activation using a reporter cell line. Bacterial identification was achieved through partial 16S rRNA gene sequencing and next-generation sequencing.

Results

CXCL8 secretion was inhibited by 94/300 isolates. Immunosuppressive isolates were detected in supragingival plaque from healthy (4/5) and gingivitis (4/5) samples, and in 2/5 subgingival (gingivitis) plaque samples. Most were Streptococcus mitis/oralis. Seventeen representative immunosuppressive isolates all inhibited NFκB activation. The immunosuppressive mechanism was strain specific, often mediated by ultra-violet light-labile factors, whilst bacterial viability was essential in certain species.

Conclusion

Many streptococci isolated from plaque suppressed epithelial cell CXCL8 secretion, via inhibition of NFκB. This phenomenon may play an important role in oral host-microbe homeostasis.

Impact of Dietary Flavanols on Microbiota, Immunity and Inflammation in Metabolic Diseases

Flavanols are natural occurring polyphenols abundant in fruits and vegetables to which have been attributed to beneficial effects on health, and also against metabolic diseases, such as diabetes, obesity and metabolic syndrome. These positive properties have been associated to the modulation of different molecular pathways, and importantly, to the regulation of immunological reactions (pro-inflammatory cytokines, chemokines, adhesion molecules, nuclear factor-κB [NF-κB], inducible enzymes), and the activity of cells of the immune system. In addition, flavanols can modulate the composition and function of gut microbiome in a prebiotic-like manner, resulting in the positive regulation of metabolic pathways and immune responses, and reduction of low-grade chronic inflammation. Moreover, the biotransformation of flavanols by gut bacteria increases their bioavailability generating a number of metabolites with potential to affect human metabolism, including during metabolic diseases. However, the exact mechanisms by which flavanols act on the microbiota and immune system to influence health and disease remain unclear, especially in humans where these connections have been scarcely explored. This review seeks to summarize recent advances on the complex interaction of flavanols with gut microbiota, immunity and inflammation focus on metabolic diseases.

The impact of probiotics on gut health via alternation of immune status of monogastric animals

The intestinal immune system is affected by various factors during its development, such as maternal antibodies, host genes, intestinal microbial composition and activity, and various stresses (such as weaning stress). Intestinal microbes may have an important impact on the development of the host immune system. Appropriate interventions such as probiotics may have a positive effect on intestinal immunity by regulating the composition and activity of intestinal microbes. Moreover, probiotics participate in the regulation of host health in many ways; for instance, by improving digestion and the absorption of nutrients, immune response, increasing the content of intestinal-beneficial microorganisms, and inhibiting intestinal-pathogenic bacteria, and they participate in regulating intestinal diseases in various ways. Probiotics are widely used as additives in livestock and the poultry industry and bring health benefits to hosts by improving intestinal microbes and growth performance, which provides more choices for promoting strong and efficient productivity.

Preventive oral supplementation with Bifidobacterium longum 51A alleviates oxazolone-induced allergic contact dermatitis-like skin inflammation in mice

Allergic contact dermatitis (ACD) is a common allergic skin disease that affects individuals subjected to different antigen exposure conditions and significantly impacts the quality of life of those affected. Numerous studies have demonstrated that probiotics suppress inflammation through immunomodulatory effects. In this study, we aimed to evaluate the effect of the probiotic Bifidobacterium longum 5^1A as a preventive treatment for ACD using an oxazolone-induced murine model. We demonstrated that B. longum 5^1A exerted a prophylactic effect on oxazolone-induced ACD-like skin inflammation via reductions in ear and dermal thickness and leucocyte infiltration. The administration of inactivated B. longum 5^1A did not affect oxazolone-induced ACD-like skin inflammation, suggesting that the bacteria must be alive to be effective. Given that B. longum 5^1A is an acetate producer, we treated mice with acetate intraperitoneally, which also prevented ear and dermal thickening. Moreover, the tissue levels of the inflammatory cytokines and chemokines interleukin (IL)-10, IL-33, tumour necrosis factor-α, chemokine (C-C motif) ligand 2/monocyte chemoattractant protein-1 and chemokine (C-C motif) ligand 5/RANTES were significantly reduced after probiotic treatment, but only IL-33 and IL-10 were reduced when the mice were treated with acetate. These results show that B. longum 5^1A exerted a potential prophylactic effect on skin inflammation and that acetate represents one potential mechanism. However, other factors are likely involved since these two treatments do not yield the same results.

Dysbiosis, Small Intestinal Bacterial Overgrowth, and Chronic Diseases

Dysbiosis is characterized by an alteration in quantity and quality of intestinal microbiota composition. In the presence of dysbiosis, enterocytes will have difficulty in maintaining the integrity of the mucosal barrier, leading to increased intestinal permeability. These events are recognised to be linked to several chronic diseases. One of the consequences of dysbiosis is the manifestation of small intestinal bacterial overgrowth (SIBO), which is associated to a variety of chronic diseases. Single food nutrients and bioactive molecules, food additives, pre- and probiotics, and different dietary patterns may change the composition of the intestinal microbiota. Low FODMAPs diet has been a reference in SIBO treatment. This chapter intends to describe how the intestinal microbiota, dysbiosis, and SIBO can be related; to define dysbiosis food and nutrients influence; and to offer some nutritional therapy strategies for applying the low FODMAPs protocol, enabling better adherence by patients in order to increase their wellbeing.

The Russian Doll Model: How Bacteria Shape Successful and Sustainable Inter-Kingdom Relationships

Successful inter-kingdom relationships are based upon a dynamic balance between defense and cooperation. A certain degree of competition is necessary to guarantee life spread and development. On the other hand, cooperation is a powerful tool to ensure a long lasting adaptation to changing environmental conditions and to support evolution to a higher level of complexity. Bacteria can interact with their (true or potential) parasites (i.e., phages) and with their multicellular hosts. In these model interactions, bacteria learnt how to cope with their inner and outer host, transforming dangerous signals into opportunities and modulating responses in order to achieve an agreement that is beneficial for the overall participants, thus giving rise to a more complex "organism" or ecosystem. In this review, particular attention will be addressed to underline the minimal energy expenditure required for these successful interactions [e.g., moonlighting proteins, post-translational modifications (PTMs), and multitasking signals] and the systemic vision of these processes and ways of life in which the system proves to be more than the sum of the single components. Using an inside-out perspective, I will examine the possibility of multilevel interactions, in which viruses help bacteria to cope with the animal host and bacteria support the human immune system to counteract viral infection in a circular vision. In this sophisticated network, bacteria represent the precious link that insures system stability with relative low energy expenditure.

Beneficial bacteria activate type-I interferon production via the intracellular cytosolic sensors STING and MAVS

Type-I interferon (IFN-I) cytokines are produced by immune cells in response to microbial infections, cancer and autoimmune diseases, and subsequently, trigger cytoprotective and antiviral responses through the activation of IFN-I stimulated genes (ISGs). The ability of intestinal microbiota to modulate innate immune responses is well known, but the mechanisms underlying such responses remain elusive. Here we report that the intracellular sensors stimulator of IFN genes (STING) and mitochondrial antiviral signaling (MAVS) are essential for the production of IFN-I in response to lactic acid bacteria (LAB), common gut commensal bacteria with beneficial properties. Using human macrophage cells we show that LAB strains that potently activate the inflammatory transcription factor NF-κB are poor inducers of IFN-I and conversely, those triggering significant amounts of IFN-I fail to activate NF-κB. This IFN-I response is also observed in human primary macrophages, which modulate CD64 and CD40 upon challenge with IFN-I-inducing LAB. Mechanistically, IFN-I inducers interact more intimately with phagocytes as compared to NF-κB-inducers, and fail to activate IFN-I in the presence of phagocytosis inhibitors. These bacteria are then sensed intracellularly by the cytoplasmic sensors STING and, to a lesser extent, MAVS. Accordingly, macrophages deficient for STING showed dramatically reduced phosphorylation of TANK-binding kinase (TBK)-1 and IFN-I activation, which resulted in lower expression of ISGs. Our findings demonstrate a major role for intracellular sensing and STING in the production of IFN-I by beneficial bacteria and the existence of bacteria-specific immune signatures, which can be exploited to promote cytoprotective responses and prevent overreactive NF-κB-dependent inflammation in the gut.

Intestinal effect of the probiotic Escherichia coli strain Nissle 1917 and its OMV

Several investigations have been conducted during the past years to examine the correlation between dysbiosis and both intestinal and extra-intestinal diseases such as inflammatory bowel disease (IBD) and ulcerative colitis (UC). E. coli Nissle 1917 (EcN) is a nonpathogenic gram-negative strain utilized in numerous gastrointestinal issues, consisting of diarrhea, uncomplicated diverticular malady, IBD and specifically UC. Many investigations have been done to examine the capability of assertive bacteria, inclusive of commensal and probiotic strains to enhance IBD in clinical testing. Bacterial secreted factors have been investigated to detect the EcN agents that facilitate the regulation of tight junction. These agents candiffuse smoothly through the mucin layer before reaching intestinal epithelial cells. Outer membrane vesicles (OMVs) are known as intercellular communicasomes as they facilitate the distal transfer of active compounds between cells. A few investigations have detailed immune-modulatory attributes for EcN through various systems that could be liable for its clinical viability in IBD. Today, the function of gut microbiota extracellular vesicles in health and disease has become a focus of attention as they serve as vehicles for the transmission of microorganisms to distal tissues of many bacterial effectors.

Modulation of the Gut Microbiota during High-Dose Glycerol Monolaurate-Mediated Amelioration of Obesity in Mice Fed a High-Fat Diet

Obesity and associated metabolic disorders are worldwide public health issues. The gut microbiota plays a key role in the pathophysiology of diet-induced obesity. Glycerol monolaurate (GML) is a widely consumed food emulsifier with antibacterial properties. Here, we explore the anti-obesity effect of GML (1,600 mg/kg of body weight) in high-fat diet (HFD)-fed mice. HFD-fed mice were treated with 1,600 mg/kg GML. Integrated microbiome, metabolome, and transcriptome analyses were used to systematically investigate the metabolic effects of GML, and antibiotic treatment was used to assess the effects of GML on the gut microbiota.

Obesity and associated metabolic disorders are worldwide public health issues. The gut microbiota plays a key role in the pathophysiology of diet-induced obesity. Glycerol monolaurate (GML) is a widely consumed food emulsifier with antibacterial properties. Here, we explore the anti-obesity effect of GML (1,600 mg/kg of body weight) in high-fat diet (HFD)-fed mice. HFD-fed mice were treated with 1,600 mg/kg GML. Integrated microbiome, metabolome, and transcriptome analyses were used to systematically investigate the metabolic effects of GML, and antibiotic treatment was used to assess the effects of GML on the gut microbiota. Our data indicated that GML significantly reduced body weight and visceral fat deposition, improved hyperlipidemia and hepatic lipid metabolism, and ameliorated glucose homeostasis and inflammation in HFD-fed mice. Importantly, GML modulated HFD-induced gut microbiota dysbiosis and selectively increased the abundance of Bifidobacterium pseudolongum. Antibiotic treatment abolished all the GML-mediated metabolic improvements. A multiomics (microbiome, metabolome, and transcriptome) association study showed that GML significantly modulated glycerophospholipid metabolism, and the abundance of Bifidobacterium pseudolongum strongly correlated with the metabolites and genes that participated in glycerophospholipid metabolism. Our results indicated that GML may be provided for obesity prevention by targeting the gut microbiota and regulating glycerophospholipid metabolism.

Gut Microbiota, Its Role in Induction of Alzheimer's Disease Pathology, and Possible Therapeutic Interventions: Special Focus on Anthocyanins

The human gut is a safe environment for several microbes that are symbiotic and important for the wellbeing of human health. However, studies on gut microbiota in different animals have suggested that changes in the composition and structure of these microbes may promote gut inflammation by releasing inflammatory cytokines and lipopolysaccharides, gut-wall leakage, and may affect systemic inflammatory and immune mechanisms that are important for the normal functioning of the body. There are many factors that aid in the gut’s dysbiosis and neuroinflammation, including high stress levels, lack of sleep, fatty and processed foods, and the prolonged use of antibiotics. These neurotoxic mechanisms of dysbiosis may increase susceptibility to Alzheimer’s disease (AD) and other neurodegenerative conditions. Therefore, studies have recently been conducted to tackle AD-like conditions by specifically targeting gut microbes that need further elucidation. It was suggested that gut dyshomeostasis may be regulated by using available options, including the use of flavonoids such as anthocyanins, and restriction of the use of high-fatty-acid-containing food. In this review, we summarize the gut microbiota, factors promoting it, and possible therapeutic interventions especially focused on the therapeutic potential of natural dietary polyflavonoid anthocyanins. Our study strongly suggests that gut dysbiosis and systemic inflammation are critically involved in the development of neurodegenerative disorders, and the natural intake of these flavonoids may provide new therapeutic opportunities for preclinical or clinical studies.

Gut commensal bacteria show beneficial properties as wildlife probiotics

Probiotics are noninvasive, environmentally friendly alternatives for reducing infectious diseases in wildlife species. Our aim in the present study was to evaluate the potential of gut commensals such as lactic acid bacteria (LAB) as wildlife probiotics. The LAB selected for our analyses were isolated from European badgers (Meles meles), a wildlife reservoir of bovine tuberculosis, and comprised four different genera: Enterococcus, Weissella, Pediococcus, and Lactobacillus. The enterococci displayed a phenotype and genotype that included the production of antibacterial peptides and stimulation of antiviral responses, as well as the presence of virulence and antibiotic resistance genes; Weissella showed antimycobacterial activity owing to their ability to produce lactate and ethanol; and lactobacilli and pediococci modulated proinflammatory phagocytic responses that associate with protection against pathogens, responses that coincide with the presence of immunomodulatory markers in their genomes. Although both lactobacilli and pediococci showed resistance to antibiotics, this was naturally acquired, and almost all isolates demonstrated a phylogenetic relationship with isolates from food and healthy animals. Our results show that LAB display probiotic benefits that depend on the genus, and that lactobacilli and pediococci are probably the most obvious candidates as probiotics against infectious diseases in wildlife because of their food-grade status and ability to modulate protective innate immune responses.

Glycerol-Monolaurate-Mediated Attenuation of Metabolic Syndrome is Associated with the Modulation of Gut Microbiota in High-Fat-Diet-Fed Mice

SCOPE

The gut microbiota plays an important role in the development of diet-induced obesity and metabolic syndrome. Glycerol monolaurate (GML), a widely consumed food emulsifier, is reported to promote metabolic disorder and gut microbiota dysbiosis in low-dose supplementation upon low-fat-diet feeding. However, little is known about whether GML produce the same effects in mice fed a high-fat diet (HFD).

METHODS AND RESULTS

C57BL/6 mice are fed a HFD with or without GML supplementation (150, 300, and 450 mg kg^-1 ) for 10 weeks. The results demonstrated that higher GML treatment (450 mg kg^-1 ) ameliorates HFD-induced metabolic disorders, supported by prevented visceral fat deposition, improved hyperlipidemia, modulated hepatic lipid metabolism, and reduced serum proinflammatory cytokine, TNF-α. Additionally, all doses of GML attenuated circulating lipopolysaccharide load and insulin resistance. Notably, GML ameliorates HFD-induced gut microbiota dysbiosis, with increases in Bacteroides uniformis, Akkermansia, Bifidobacterium, and Lactobacillus and decreases in Escherichia coli, Lactococcus, and Flexispira. Spearman's correlation analysis indicates that these enriched specific genera are significantly associated with the metabolic improvements of GML.

CONCLUSION

The findings identify the links between gut microbiota and GML-induced metabolic improvements, suggesting that the attenuation of HFD-induced metabolic disorders by higher GML supplementation may occur through targeting gut microbiota.

Lactobacilli Isolated From Wild Boar (Sus scrofa) Antagonize Mycobacterium bovis Bacille Calmette-Guerin (BCG) in a Species-Dependent Manner

Background: Wildlife poses a significant burden for the complete eradication of bovine tuberculosis (bTB). In particular, wild boar (Sus scrofa) is one of the most important reservoirs of Mycobacterium bovis, the causal agent of bTB. Wild boar can display from mild TB lesions, usually found in head lymph nodes, to generalized TB lesions distributed in different anatomical regions; but rarely clinical signs, which complicates the diagnosis of Mycobacterium bovis infection and bTB control. Among the possibilities for this variability in lesion distribution is the influence of the host-beneficial commensal-primed immune barrier. In this respect, beneficial microbes may delay bTB dissemination as a consequence of an antagonistic competition for nutrients and phagocytes. In order to explore this possibility, we have tested whether typical commensals such as lactobacilli have the capacity to reduce the survival rate of the surrogate M. bovis strain Bacillus Calmette-Guerin (BCG); and to modulate its phagocyte intake.

Results: Three Lactobacillus species, L. casei, L. plantarum, and L. salivarius, isolated from wild boar feces displayed a pH-dependent inhibitory activity against BCG and influenced its intake by porcine blood phagocytes in a species-dependent manner. All lactobacilli showed a very significant bactericidal effect against BCG at low pH, but only isolates of L. plantarum and L. casei displayed such antimycobacterial activity at neutral pH. The genomes of these isolates revealed the presence of two-peptide bacteriocins whose precursor genes up-regulate in the presence of BCG cells. Furthermore, L. plantarum reduced significantly the BCG phagocytic intake, whereas L. casei had the opposite effect. L. salivarius had no significant influence on the phagocytic response to BCG.

Conclusions: Our in vitro results show that lactobacilli isolated from wild boar antagonize BCG as a consequence of their antimycobacterial activity and a competitive phagocytic response. These findings suggest that commensal bacteria could play a beneficial role in influencing the outcome of bTB dissemination. Further work with lactobacilli as a potential competitive pressure to control bTB will need to take into account the complex nature of the commensal microbiome, the specific immunity of the wild boar and the in vivo infection context with pathogenic strains of M. bovis.

Extracellular vesicles and soluble factors secreted by Escherichia coli Nissle 1917 and ECOR63 protect against enteropathogenic E. coli-induced intestinal epithelial barrier dysfunction

Background

Enteric pathogens have developed mechanisms to disrupt tight junctions and increase gut permeability. Many studies have analysed the ability of live probiotics to protect intestinal epithelial cells against tight junction damage caused by bacterial pathogens. Escherichia coli Nissle 1917 (EcN) is among the probiotics that positively modulates the intestinal epithelial barrier by regulating expression and distribution of tight junction proteins. We previously reported that regulation of ZO-1, claudin-14 and claudin-2 is mediated by EcN secreted factors, either free-released or associated with outer membrane vesicles (OMVs). Factors secreted by commensal ECOR63 elicited comparable effects in intact epithelial T-84 and Caco-2 cell monolayers.

Results

Here we analyse the ability of OMVs and soluble secreted factors to protect epithelial barrier function in polarized T-84 and Caco-2 cells infected with enteropathogenic Escherichia coli (EPEC). Transepithelial electrical resistance, paracellular permeability, mRNA levels and subcellular distribution of tight junction proteins were monitored in the absence or presence of EcN and ECOR63 extracellular fractions. EPEC downregulated expression of ZO-1 ZO-2, occludin and claudin-14 and altered the subcellular localization of ZO-1, occludin and F-actin cytoskeleton. OMVs and soluble factors secreted by EcN and ECOR63 counteracted EPEC-altered transepithelial resistance and paracellular permeability, preserved occludin and claudin-14 mRNA levels, retained ZO-1 and occludin at tight junctions in the cell boundaries and ameliorated F-actin disorganization. Redistribution of ZO-1 was not accompanied by changes at mRNA level.

Conclusion

This study provides new insights on the role of microbiota secreted factors on the modulation of intestinal tight junctions, expanding their barrier-protective effects against pathogen-induced disruption.

Evaluation of the Immunomodulatory Activities of the Probiotic Strain Lactobacillus fermentum UCO-979C

Lactobacillus fermentum UCO-979C, a strain isolated from a human stomach, was previously characterized by its potential probiotic properties. The UCO-979C strain displayed the ability to beneficially regulate the innate immune response triggered by Helicobacter pylori infection in human gastric epithelial cells. In this work, we conducted further in vitro studies in intestinal epithelial cells (IECs) and in vivo experiments in mice in order to characterize the potential immunomodulatory effects of L. fermentum UCO-979C on the intestinal mucosa. Results demonstrated that the UCO-979C strain is capable to differentially modulate the immune response of IECs triggered by Toll-like receptor 4 (TLR4) activation through the modulation of TLR negative regulators' expression. In addition, we demonstrated for the first time that L. fermentum UCO-979C is able to exert its immunomodulatory effect in the intestinal mucosa in vivo. The feeding of mice with L. fermentum UCO-979C significantly increased the production of intestinal IFN-γ, stimulated intestinal and peritoneal macrophages and increased the number of Peyer's patches CD4⁺ T cells. In addition, L. fermentum UCO-979C augmented intestinal IL-6, reduced the number of immature B220⁺CD24^high B cells from Peyer's patches, enhanced the number of mature B B220⁺CD24^low cells, and significantly increased intestinal IgA content. The results of this work revealed that L. fermentum UCO-979C has several characteristics making it an excellent candidate for the development of immunobiotic functional foods aimed to differentially regulate immune responses against gastric and intestinal pathogens.

Proteomics for the Investigation of Surface-Exposed Proteins in Probiotics

Probiotics are commensal microorganisms that are present in the intestinal tract and in many fermented foods and positively affect human health, promoting digestion and uptake of dietary nutrients, strengthening intestinal barrier function, modulating immune response, and enhancing antagonism toward pathogens. The proteosurfaceome, i.e., the complex set of proteins present on the bacterial surface, is directly involved as leading actor in the dynamic communication between bacteria and host. In the last decade, the biological relevance of surface-exposed proteins prompted research activities exploiting the potentiality of proteomics to define the complex network of proteins that are involved in the molecular mechanisms at the basis of the adaptation to gastrointestinal environment and the probiotic effects. These studies also took advantages of the recent technological improvements in proteomics, mass spectrometry and bioinformatics that triggered the development of ad hoc designed innovative strategies to characterize the bacterial proteosurfaceome. This mini-review is aimed at describing the key role of proteomics in depicting the cell wall protein architecture and the involvement of surface-exposed proteins in the intimate and dynamic molecular dialogue between probiotics and intestinal epithelial and immune cells.

Mechanisms of Action of Probiotics

Probiotics are living microorganisms that confer health benefits to the host when administered in adequate amounts; however, dead bacteria and their components can also exhibit probiotic properties. Bifidobacterium and strains of lactic acid bacteria are the most widely used bacteria that exhibit probiotic properties and are included in many functional foods and dietary supplements. Probiotics have been shown to prevent and ameliorate the course of digestive disorders such as acute, nosocomial, and antibiotic-associated diarrhea; allergic disorders such as atopic dermatitis (eczema) and allergic rhinitis in infants; and Clostridium difficile-associated diarrhea and some inflammatory bowel disorders in adults. In addition, probiotics may be of interest as coadjuvants in the treatment of metabolic disorders, including obesity, metabolic syndrome, nonalcoholic fatty liver disease, and type 2 diabetes. However, the mechanisms of action of probiotics, which are diverse, heterogeneous, and strain specific, have received little attention. Thus, the aim of the present work was to review the main mechanisms of action of probiotics, including colonization and normalization of perturbed intestinal microbial communities in children and adults; competitive exclusion of pathogens and bacteriocin production; modulation of fecal enzymatic activities associated with the metabolization of biliary salts and inactivation of carcinogens and other xenobiotics; production of short-chain and branched-chain fatty acids, which, in turn, have wide effects not only in the intestine but also in peripheral tissues via interactions with short-chain fatty acid receptors, modulating mainly tissue insulin sensitivity; cell adhesion and mucin production; modulation of the immune system, which results mainly in the differentiation of T-regulatory cells and upregulation of anti-inflammatory cytokines and growth factors, i.e., interleukin-10 and transforming growth factor; and interaction with the brain-gut axis by regulation of endocrine and neurologic functions. Further research to elucidate the precise molecular mechanisms of action of probiotics is warranted.

Occurrence and Dynamism of Lactic Acid Bacteria in Distinct Ecological Niches: A Multifaceted Functional Health Perspective

Lactic acid bacteria (LAB) are representative members of multiple ecosystems on earth, displaying dynamic interactions within animal and plant kingdoms in respect with other microbes. This highly heterogeneous phylogenetic group has coevolved with plants, invertebrates, and vertebrates, establishing either mutualism, symbiosis, commensalism, or even parasitism-like behavior with their hosts. Depending on their location and environment conditions, LAB can be dominant or sometimes in minority within ecosystems. Whatever their origins and relative abundance in specific anatomic sites, LAB exhibit multifaceted ecological and functional properties. While some resident LAB permanently inhabit distinct animal mucosal cavities, others are provided by food and may transiently occupy the gastrointestinal tract. It is admitted that the overall gut microbiome has a deep impact on health and diseases. Here, we examined the presence and the physiological role of LAB in the healthy human and several animal microbiome. Moreover, we also highlighted some dysbiotic states and related consequences for health, considering both the resident and the so-called "transionts" microorganisms. Whether LAB-related health effects act collectively or follow a strain-specificity dogma is also addressed. Besides the highly suggested contribution of LAB to interplay with immune, metabolic, and even brain-axis regulation, the possible involvement of LAB in xenobiotic detoxification processes and metal equilibrium is also tackled. Recent technological developments such as functional metagenomics, metabolomics, high-content screening and design in vitro and in vivo experimental models now open new horizons for LAB as markers applied for disease diagnosis, susceptibility, and follow-up. Moreover, identification of general and more specific molecular mechanisms based on antioxidant, antimicrobial, anti-inflammatory, and detoxifying properties of LAB currently extends their selection and promising use, either as probiotics, in traditional and functional foods, for dedicated treatments and mostly for maintenance of normobiosis and homeostasis.