Role of natural killer and dendritic cell crosstalk in immunomodulation by commensal bacteria probiotics. J Biomed Biotechnol. 2011;2011:473097. [PMID: 21660136 PMCID: PMC3110311 DOI: 10.1155/2011/473097]

The microbes we eat: abundance and taxonomy of microbes consumed in a day's worth of meals for three diet types

Far more attention has been paid to the microbes in our feces than the microbes in our food. Research efforts dedicated to the microbes that we eat have historically been focused on a fairly narrow range of species, namely those which cause disease and those which are thought to confer some “probiotic” health benefit. Little is known about the effects of ingested microbial communities that are present in typical American diets, and even the basic questions of which microbes, how many of them, and how much they vary from diet to diet and meal to meal, have not been answered.

We characterized the microbiota of three different dietary patterns in order to estimate: the average total amount of daily microbes ingested via food and beverages, and their composition in three daily meal plans representing three different dietary patterns. The three dietary patterns analyzed were: (1) the Average American (AMERICAN): focused on convenience foods, (2) USDA recommended (USDA): emphasizing fruits and vegetables, lean meat, dairy, and whole grains, and (3) Vegan (VEGAN): excluding all animal products. Meals were prepared in a home kitchen or purchased at restaurants and blended, followed by microbial analysis including aerobic, anaerobic, yeast and mold plate counts as well as 16S rRNA PCR survey analysis.

Based on plate counts, the USDA meal plan had the highest total amount of microbes at 1.3 × 10⁹ CFU per day, followed by the VEGAN meal plan and the AMERICAN meal plan at 6 × 10⁶ and 1.4 × 10⁶ CFU per day respectively. There was no significant difference in diversity among the three dietary patterns. Individual meals clustered based on taxonomic composition independent of dietary pattern. For example, meals that were abundant in Lactic Acid Bacteria were from all three dietary patterns. Some taxonomic groups were correlated with the nutritional content of the meals. Predictive metagenome analysis using PICRUSt indicated differences in some functional KEGG categories across the three dietary patterns and for meals clustered based on whether they were raw or cooked.

Further studies are needed to determine the impact of ingested microbes on the intestinal microbiota, the extent of variation across foods, meals and diets, and the extent to which dietary microbes may impact human health. The answers to these questions will reveal whether dietary microbes, beyond probiotics taken as supplements—i.e., ingested with food—are important contributors to the composition, inter-individual variation, and function of our gut microbiota.

Modulation of immunity and inflammatory gene expression in the gut, in inflammatory diseases of the gut and in the liver by probiotics

The potential for the positive manipulation of the gut microbiome through the introduction of beneficial microbes, as also known as probiotics, is currently an active area of investigation. The FAO/WHO define probiotics as live microorganisms that confer a health benefit to the host when administered in adequate amounts. However, dead bacteria and bacterial molecular components may also exhibit probiotic properties. The results of clinical studies have demonstrated the clinical potential of probiotics in many pathologies, such as allergic diseases, diarrhea, inflammatory bowel disease and viral infection. Several mechanisms have been proposed to explain the beneficial effects of probiotics, most of which involve gene expression regulation in specific tissues, particularly the intestine and liver. Therefore, the modulation of gene expression mediated by probiotics is an important issue that warrants further investigation. In the present paper, we performed a systematic review of the probiotic-mediated modulation of gene expression that is associated with the immune system and inflammation. Between January 1990 to February 2014, PubMed was searched for articles that were published in English using the MeSH terms “probiotics" and "gene expression" combined with “intestines", "liver", "enterocytes", "antigen-presenting cells", "dendritic cells", "immune system", and "inflammation". Two hundred and five original articles matching these criteria were initially selected, although only those articles that included specific gene expression results (77) were later considered for this review and separated into three major topics: the regulation of immunity and inflammatory gene expression in the gut, in inflammatory diseases of the gut and in the liver. Particular strains of Bifidobacteria, Lactobacilli, Escherichia coli, Propionibacterium, Bacillus and Saccharomyces influence the gene expression of mucins, Toll-like receptors, caspases, nuclear factor-κB, and interleukins and lead mainly to an anti-inflammatory response in cultured enterocytes. In addition, the interaction of commensal bacteria and probiotics with the surface of antigen-presenting cells in vitro results in the downregulation of pro-inflammatory genes that are linked to inflammatory signaling pathways, whereas other anti-inflammatory genes are upregulated. The effects of probiotics have been extensively investigated in animal models ranging from fish to mice, rats and piglets. These bacteria induce a tolerogenic and hyporesponsive immune response in which many genes that are related to the immune system, in particular those genes expressing anti-inflammatory cytokines, are upregulated. By contrast, information related to gene expression in human intestinal cells mediated by the action of probiotics is scarce. There is a need for further clinical studies that evaluate the mechanism of action of probiotics both in healthy humans and in patients with chronic diseases. These types of clinical studies are necessary for addressing the influence of these microorganisms in gene expression for different pathways, particularly those that are associated with the immune response, and to better understand the role that probiotics might have in the prevention and treatment of disease.

A think tank of TINK/TANKs: tumor-infiltrating/tumor-associated natural killer cells in tumor progression and angiogenesis

Tumor-infiltrating leukocytes are often induced by the cancer microenvironment to display a protumor, proangiogenic phenotype. This “polarization” has been described for several myeloid cells, in particular macrophages. Natural killer (NK) cells represent another population of innate immune cells able to infiltrate tumors. The role of NK in tumor progression and angiogenesis has not yet been fully investigated. Several studies have shown that tumor-infiltrating NK (here referred to as “TINKs”) and tumor-associated NK (altered peripheral NK cells, which here we call “TANKs”) are compromised in their ability to lysew tumor cells. Recent data have suggested that they are potentially protumorigenic and can also acquire a proangiogenic phenotype. Here we review the properties of TINKs and TANKs and compare their activities to that of NK cells endowed with a physiological proangiogenic phenotype, in particular decidual NK cells. We speculate on the potential origins of TINKs and TANKs and on the immune signals involved in their differentiation and polarization. The TINK and TANK phenotype has broad implications in the immune response to tumors, ranging from a deficient control of cancer and cancer stem cells to an altered crosstalk with other relevant players of the immune response, such as dendritic cells, to induction of cancer angiogenesis. With this recently acquired knowledge that has not yet been put into perspective, we point out new potential avenues for therapeutic intervention involving NK cells as a target or an ally in oncology.

Modulating the microbiota in inflammatory bowel diseases: prebiotics, probiotics or faecal transplantation?

Crohn's disease (CD) and ulcerative colitis (UC) are the two major phenotypes of inflammatory bowel diseases (IBD) which constitute a spectrum of chronic, debilitating diseases characterised by a relapsing inflammation of the intestinal mucosal lining. Evidence from a variety of disciplines implicates the intestinal microbiota in the pathogenesis of idiopathic IBD and their complications, including pouchitis. Many studies have reported a dysbiosis in IBD, characterised by a decrease in diversity, a decreased abundance of some dominant commensal members (such as Clostridium IV and XIVa) and an increase in detrimental bacteria (such as sulphate reducing bacteria and Escherichia coli). Therapies such as prebiotics and probiotics aim to selectively manipulate the intestinal microbiota and have been evaluated as an attractive therapeutic option with few side effects. The multispecies product VSL#3 was found effective in preventing and maintaining remission in pouchitis, whereas both VSL#3 and E. coli Nissle were effective in maintaining remission in UC. A more drastic approach to restore the composition of the microbiota and correct the underlying imbalance is a faecal microbiota transplantation (FMT). FMT has been successfully applied to treat patients with even recalcitrant Clostridium difficile infection. Particularly in UC, the majority of studies suggest that FMT may be an effective treatment option although the evidence is still limited. It is anticipated that our increasing knowledge on the composition and function of the intestinal microbiota components will allow in the future for a better selection of highly performing bacteria with specific functions required for specific benefits.

Liaison between natural killer cells and dendritic cells in human gestation

A successful pregnancy relies on immunological adaptations that allow the fetus to grow and develop in the uterus, despite being recognized by maternal immune cells. Among several immunocompetent cell types present within the human maternal/fetal interface, DC-SIGN(+) dendritic cells (DCs) and CD56(+) natural killer (NK) cells are of major importance for early pregnancy maintenance, not only generating maternal immunological tolerance but also regulating stromal cell differentiation. Previous reports show the presence of NK-DC cell conjugates in first trimester human decidua, suggesting that these cells may play a role in the modulation of the local immune response within the uterus. While effective immunity is necessary to protect the mother from harmful pathogens, some form of tolerance must be activated to avoid an immune response against fetal antigens. This review article discusses current evidence concerning the functions of DC and NK cells in pregnancy and their liaison in human decidua.

Cross-talk between probiotic lactobacilli and host immune system

The mechanism by which probiotic lactobacilli affect the immune system is strain specific. As the immune system is a multicompartmental system, each strain has its way to interact with it and induce a visible and quantifiable effect. This review summarizes the interplay existing between the host immune system and probiotic lactobacilli, that is, with emphasis on lactobacilli as a prototype probiotic genus. Several aspects including the bacterial-host cross-talk with the mucosal and systemic immune system are presented, as well as short sections on the competing effect towards pathogenic bacteria and their uses as delivery vehicle for antigens.

Development of Streptococcus pneumoniae Vaccines Using Live Vectors

Streptococcus pneumoniae still causes severe morbidity and mortality worldwide, especially in young children and the elderly. Much effort has been dedicated to developing protein-based universal vaccines to conquer the current shortcomings of capsular vaccines and capsular conjugate vaccines, such as serotype replacement, limited coverage and high costs. A recombinant live vector vaccine delivering protective antigens is a promising way to achieve this goal. In this review, we discuss the researches using live recombinant vaccines, mainly live attenuated Salmonella and lactic acid bacteria, to deliver pneumococcal antigens. We also discuss both the limitations and the future of these vaccines.

An increased number of CD4+CD25+ cells induced by an oral administration of Lactobacillus plantarum NRIC0380 are involved in antiallergic activity

BACKGROUND

Our previous study showed that an oral administration of Lactobacillus plantarum NRIC0380 inhibited immunoglobulin E (IgE) production in a murine model, and that orally administered NRIC0380 induced CD4+CD25+ Foxp3+ T, i.e. regulatory T (Treg), cells in the spleen and Peyer's patch of mice. Although it has been reported that Treg cells might suppress the allergic symptoms, the involvement of the cells in the antiallergic activity of lactic acid bacteria has not been clearly demonstrated. We therefore examined in detail the antiallergic activity of Treg cells obtained from mice that had been fed NRIC0380.

METHODS

Treg cells were obtained from mice that had been fed NRIC0380. The T cell-suppressive effect of the cells was analyzed by coculturing the cells with splenocytes of β-lactoglobulin-immunized mice and β-lactoglobulin. The effects of the Treg cells on the IgE production and cutaneous anaphylaxis reaction were then analyzed by transferring the cells into another mouse.

RESULTS

The Treg cells obtained from the mice that had been fed NRIC0380 showed similar T cell-suppressive activity to those cells obtained from the control mice. The Treg cells obtained from the mice fed NRIC0380 significantly inhibited the IgE production and active cutaneous anaphylaxis reaction when transferred into another mouse that was subsequently immunized with the antigen. Furthermore, the Treg cells also significantly suppressed the passive cutaneous anaphylaxis reaction when cotransferred with the IgE antibody into another mouse.

CONCLUSIONS

The induction of Treg cells by the oral administration of NRIC0380 would be involved in the antiallergic activity of NRIC0380.

Novel perspectives on dendritic cell-based immunotherapy of cancer

Advances in immunobiology knowledge as well as in cell culture processes that generate large numbers of purified and functionally mature dendritic cells (DCs) have raised the possibility that DCs might represent promising clinical agents to generate effective immune responses against cancer. Here, we discuss the present pitfalls of dendritic cell vaccines for the treatment of human cancer with regard to the most recent knowledge in the biology of DCs. In particular, we highlight the relevance of improving our current understanding of DC trafficking, functions and interactions with other cells of innate immunity for the development of more effective cancer vaccines.

Probiotics and food allergy

The exact prevalence of food allergy in the general population is unknown, but almost 12% of pediatric population refers a suspicion of food allergy. IgE mediated reactions to food are actually the best-characterized types of allergy, and they might be particularly harmful especially in children. According to the "hygiene hypothesis" low or no exposure to exogenous antigens in early life may increase the risk of allergic diseases by both delaying the development of the immune tolerance and limiting the Th2/Th1 switch. The critical role of intestinal microbiota in the development of immune tolerance improved recently the interest on probiotics, prebiotics, antioxidants, polyunsaturated fatty acid, folate and vitamins, which seem to have positive effects on the immune functions.Probiotics consist in bacteria or yeast, able to re-colonize and restore microflora symbiosis in intestinal tract. One of the most important characteristics of probiotics is their safety for human health. Thanks to their ability to adhere to intestinal epithelial cells and to modulate and stabilize the composition of gut microflora, probiotics bacteria may play an important role in the regulation of intestinal and systemic immunity. They actually seem capable of restoring the intestinal microbic equilibrium and modulating the activation of immune cells.Several studies have been recently conducted on the role of probiotics in preventing and/or treating allergic disorders, but the results are often quite contradictory, probably because of the heterogeneity of strains, the duration of therapy and the doses administered to patients. Therefore, new studies are needed in order to clarify the functions and the utility of probiotics in food allergies and ion other types of allergic disorders.

Probiotics, prebiotics and immunomodulation of gut mucosal defences: homeostasis and immunopathology

Probiotics are beneficial microbes that confer a realistic health benefit on the host, which in combination with prebiotics, (indigestible dietary fibre/carbohydrate), also confer a health benefit on the host via products resulting from anaerobic fermentation. There is a growing body of evidence documenting the immune-modulatory ability of probiotic bacteria, it is therefore reasonable to suggest that this is potentiated via a combination of prebiotics and probiotics as a symbiotic mix. The need for probiotic formulations has been appreciated for the health benefits in "topping up your good bacteria" or indeed in an attempt to normalise the dysbiotic microbiota associated with immunopathology. This review will focus on the immunomodulatory role of probiotics and prebiotics on the cells, molecules and immune responses in the gut mucosae, from epithelial barrier to priming of adaptive responses by antigen presenting cells: immune fate decision-tolerance or activation? Modulation of normal homeostatic mechanisms, coupled with findings from probiotic and prebiotic delivery in pathological studies, will highlight the role for these xenobiotics in dysbiosis associated with immunopathology in the context of inflammatory bowel disease, colorectal cancer and hypersensitivity.

NK cells are necessary for recovery of corneal CD11c+ dendritic cells after epithelial abrasion injury

Mechanisms controlling CD11c(+) MHCII(+) DCs during corneal epithelial wound healing were investigated in a murine model of corneal abrasion. Selective depletion of NKp46(+) CD3- NK cells that normally migrate into the cornea after epithelial abrasion resulted in >85% reduction of the epithelial CD11c(+) MHCII(+) DCs, normally present during and after epithelial wound closure. Transfer (i.v.) of spleen NK cells into NK cell-depleted mice significantly restored levels of corneal epithelial DCs (P<0.01). Immigrated NK cells were predominately positive for IFN-γ, and topical corneal anti-IFN-γ reduced epithelial DCs by 79% (P<0.01). IFN-γ(-/-) mice had 69% fewer DCs than WT controls (P<0.01), and topical rIFN-γ applied to NK cell-depleted corneas increased epithelial DCs significantly (P<0.01). The contribution of ICAM-1, an adhesion molecule involved in leukocyte migration, expressed on healing corneal epithelium, was evaluated. ICAM-1(-/-) mice exhibited >70% reduction in epithelial DC recovery in the first 48 h after epithelial abrasion (P<0.01). These interventions reveal an early turnover of DCs in the epithelium after injury, and ICAM-1, NK cells, and IFN-γ are necessary for the immigration phase of this turnover.

Potential of probiotics, prebiotics and synbiotics for management of colorectal cancer

Colorectal Cancer (CRC) is the second leading cause of cancer-related mortality and is the fourth most common malignant neoplasm in USA. Escaping apoptosis and cell mutation are the prime hallmarks of cancer. It is apparent that balancing the network between DNA damage and DNA repair is critical in preventing carcinogenesis. One-third of cancers might be prevented by nutritious healthy diet, maintaining healthy weight and physical activity. In this review, an attempt is made to abridge the role of carcinogen in colorectal cancer establishment and prognosis, where special attention has been paid to food-borne mutagens and functional role of beneficial human gut microbiome in evading cancer. Further the significance of tailor-made prebiotics, probiotics and synbiotics in cancer management by bio-antimutagenic and desmutagenic activity has been elaborated. Probiotic bacteria are live microorganisms that, when administered in adequate amounts, confer a healthy benefit on the host. Prebiotics are a selectively fermentable non-digestible oligosaccharide or ingredient that brings specific changes, both in the composition and/or activity of the gastrointestinal microflora, conferring health benefits. Synbiotics are a combination of probiotic bacteria and the growth promoting prebiotic ingredients that purport "synergism."

Mucosal immunology and probiotics

The cross-talk between the mucosa-associated immune system and microbiota is critical in mucosal tissue homeostasis as well as in protection against infectious and inflammatory diseases occurring at mucosal sites. This recent evidence has paved the way to therapeutic approaches aimed at modulating the mucosa-associated immune system using probiotics. Different strains of probiotics possess the ability to finely regulate dendritic cell (DC) activation, polarizing the subsequent T cell activity toward Th1 (e.g. Lactobacillus (Lb) acidophilus), Th2 (Lb.reuteri and Bifidobacterium bifidum) or, as more recently demonstrated, Th17 responses induced by specific strains such as Lb.rhamnosus GG and Lac23a, the latter isolated in our laboratory. Here, we review some recent advances in our understanding of probiotics effects on mucosal immunology, particularly on cells of the innate immunity such as DCs. We also highlight our own experiences in modulating DC functions by commensal bacteria and discuss the relevance of probiotics administration in the treatment of human immunopathologies.

Effect of Lactobacillus brevis KB290 on the cell-mediated cytotoxic activity of mouse splenocytes: a DNA microarray analysis

Lactic acid bacteria confer a variety of health benefits. Here, we investigate the mechanisms by which Lactobacillus brevis KB290 (KB290) enhances cell-mediated cytotoxic activity. Female BALB/c mice aged 9 weeks were fed a diet containing KB290 (3 × 10(9) colony-forming units/g) or starch for 1 d. The resulting cytotoxic activity of splenocytes against YAC-1 cells was measured using flow cytometry and analysed for gene expression using DNA microarray technology. KB290 enhanced the cell-mediated cytotoxic activity of splenocytes. DNA microarray analysis identified 327 up-regulated and 347 down-regulated genes that characterised the KB290 diet group. The up-regulated genes were significantly enriched in Gene Ontology terms related to immunity, and, especially, a positive regulation of T-cell-mediated cytotoxicity existed among these terms. Almost all the genes included in the term encoded major histocompatibility complex (MHC) class I molecules involved in the presentation of antigen to CD8(+) cytotoxic T cells. Marco and Signr1 specific to marginal zone macrophages (MZM), antigen-presenting cells, were also up-regulated. Flow cytometric analysis confirmed that the proportion of MZM was significantly increased by KB290 ingestion. Additionally, the over-represented Kyoto Encyclopedia of Genes and Genomes pathways among the up-regulated genes were those for natural killer (NK) cell-mediated cytotoxicity and antigen processing and presentation. The results for the selected genes associated with NK cells and CD8(+) cytotoxic T cells were confirmed by quantitative RT-PCR. These results suggest that enhanced cytotoxic activity could be caused by the activation of NK cells and/or of CD8(+) cytotoxic T cells stimulated via MHC class I presentation.

In vitro study of the effect of a probiotic bacterium Lactobacillus rhamnosus against herpes simplex virus type 1

Background

Due to the emergence of drug resistance in herpes simplex virus type 1 (HSV-1), researchers are trying to find other methods for treating herpes simplex virus type 1 infections. Probiotic bacteria are effective in macrophage activation and may have antiviral activities.

Objective

This study aimed at verifying the direct effect of Lactobacillus rhamnosus, a probiotic bacterium, in comparison with Escherichia coli, a non-probiotic one, on HSV-1 infection, and determining its effect on macrophage activation for in vitro elimination of HSV-1 infection.

Methods

The above bacteria were introduced into HSV-1 infected Vero cells, and their effects were examined using both MTT and plaque assay. To determine macrophage activation against in vitro HSV-1 infection, J774 cells were exposed to these bacteria; then, macrophage viability was examined with the MTT method, and tumor necrosis factor alpha (TNF-α), Interferon-gamma (IFN-γ), and nitric oxide (NO) assessments were performed using the ELISA method.

Results

A significant increased viability of macrophages was observed (p < 0.05) in the presence of Lactobacillus rhamnosus before and after HSV-1 infection when compared with Escherichia coli as a non-probiotic bacterium. However, tumor necrosis factor α concentration produced by Escherichia coli-treated J774 cells was significantly higher than Lactobacillus rhamnosus-treated J774 cells (p < 0.05). Interferon-gamma and NO production were not different in the groups treated with Escherichia coli or with Lactobacillus rhamnosus.

Conclusion

The results of this study indicate that Lactobacillus rhamnosus enhances macrophage viability for HSV-1 elimination and activation against HSV-1 more effectively, when compared with non-probiotic Escherichia coli. It also seems that receptor occupation of macrophage sites decreases HSV-1 infectivity by both of the studied bacteria.

Cell-free culture supernatant of Bifidobacterium breve CNCM I-4035 decreases pro-inflammatory cytokines in human dendritic cells challenged with Salmonella typhi through TLR activation

Dendritic cells (DCs) constitute the first point of contact between gut commensals and our immune system. Despite growing evidence of the immunomodulatory effects of probiotics, the interactions between the cells of the intestinal immune system and bacteria remain largely unknown. Indeed,, the aim of this work was to determine whether the probiotic Bifidobacterium breve CNCM I-4035 and its cell-free culture supernatant (CFS) have immunomodulatory effects in human intestinal-like dendritic cells (DCs) and how they respond to the pathogenic bacterium Salmonella enterica serovar Typhi, and also to elucidate the molecular mechanisms involved in these interactions. Human DCs were directly challenged with B. breve/CFS, S. typhi or a combination of these stimuli for 4 h. The expression pattern of genes involved in Toll-like receptor (TLR) signaling pathway and cytokine secretion was analyzed. CFS decreased pro-inflammatory cytokines and chemokines in human intestinal DCs challenged with S. typhi. In contrast, the B. breve CNCM I-4035 probiotic strain was a potent inducer of the pro-inflammatory cytokines and chemokines tested, i.e., TNF-α, IL-8 and RANTES, as well as anti-inflammatory cytokines including IL-10. CFS restored TGF-β levels in the presence of Salmonella. Live B.breve and its supernatant enhanced innate immune responses by the activation of TLR signaling pathway. These treatments upregulated TLR9 gene transcription. In addition, CFS was a more potent inducer of TLR9 expression than the probiotic bacteria in the presence of S. typhi. Expression levels of CASP8 and IRAK4 were also increased by CFS, and both treatments induced TOLLIP gene expression. Our results indicate that the probiotic strain B. breve CNCM I-4035 affects the intestinal immune response, whereas its supernatant exerts anti-inflammatory effects mediated by DCs. This supernatant may protect immune system from highly infectious agents such as Salmonella typhi and can down-regulate pro-inflammatory pathways.

Human intestinal dendritic cells decrease cytokine release against Salmonella infection in the presence of Lactobacillus paracasei upon TLR activation

Probiotic bacteria have been shown to modulate immune responses and could have therapeutic effects in allergic and inflammatory disorders. However, little is known about the signalling pathways that are engaged by probiotics. Dendritic cells (DCs) are antigen-presenting cells that are involved in immunity and tolerance. Monocyte-derived dendritic cells (MoDCs) and murine DCs are different from human gut DCs; therefore, in this study, we used human DCs generated from CD34+ progenitor cells (hematopoietic stem cells) harvested from umbilical cord blood; those DCs exhibited surface antigens of dendritic Langerhans cells, similar to the lamina propria DCs in the gut. We report that both a novel probiotic strain isolated from faeces of exclusively breast-fed newborn infants, Lactobacillus paracasei CNCM I-4034, and its cell-free culture supernatant (CFS) decreased pro-inflammatory cytokines and chemokines in human intestinal DCs challenged with Salmonella. Interestingly, the supernatant was as effective as the bacteria in reducing pro-inflammatory cytokine expression. In contrast, the bacterium was a potent inducer of TGF-β2 secretion, whereas the supernatant increased the secretion of TGF-β1 in response to Salmonella. We also showed that both the bacteria and its supernatant enhanced innate immunity through the activation of Toll-like receptor (TLR) signalling. These treatments strongly induced the transcription of the TLR9 gene. In addition, upregulation of the CASP8 and TOLLIP genes was observed. This work demonstrates that L. paracasei CNCM I-4034 enhanced innate immune responses, as evidenced by the activation of TLR signalling and the downregulation of a broad array of pro-inflammatory cytokines. The use of supernatants like the one described in this paper could be an effective and safe alternative to using live bacteria in functional foods.

Probiotic metabolites from Bacillus coagulans GanedenBC30TM support maturation of antigen-presenting cells in vitro

AIM: To study the effects of probiotic metabolites on maturation stage of antigen-presenting immune cells.

METHODS: Ganeden Bacillus coagulans 30 (GBC30) bacterial cultures in log phase were used to isolate the secreted metabolite (MET) fraction. A second fraction was made to generate a crude cell-wall-enriched fraction, by centrifugation and lysis, followed by washing. A preparation of MET was subjected to size exclusion centrifugation, generating three fractions: < 3 kDa, 3-30 kDa, and 30-200 kDa and activities were tested in comparison to crude MET and cell wall in primary cultures of human peripheral blood mononuclear cell (PBMC) as a source of antigen-presenting mononuclear phagocytes. The maturation status of mononuclear phagocytes was evaluated by staining with monoclonal antibodies towards CD14, CD16, CD80 and CD86 and analyzed by flow cytometry.

RESULTS: Treatment of PBMC with MET supported maturation of mononuclear phagocytes toward both macrophage and dendritic cell phenotypes. The biological activity unique to the metabolites included a reduction of CD14+ CD16+ pro-inflammatory cells, and this property was associated with the high molecular weight metabolite fraction. Changes were also seen for the dendritic cell maturation markers CD80 and CD86. On CD14^dim cells, an increase in both CD80 and CD86 expression was seen, in contrast to a selective increase in CD86 expression on CD14^bright cells. The co-expression of CD80 and CD86 indicates effective antigen presentation to T cells and support of T helper cell differentiation. The selective expression of CD86 in the absence of CD80 points to a role in generating T regulatory cells.

CONCLUSION: The data show that a primary mechanism of action of GBC30 metabolites involves support of more mature phenotypes of antigen-presenting cells, important for immunological decision-making.