Gut derived lactic acid bacteria induce strain specific CD4(+) T cell responses in human PBMC

The role of the gut microbiome in neuroinflammation and chemotherapy-induced peripheral neuropathy

Chemotherapy-induced peripheral neuropathy (CIPN) is one of the most debilitating adverse effects caused by chemotherapy drugs such as paclitaxel, oxaliplatin and vincristine. It is untreatable and often leads to the discontinuation of cancer therapy and a decrease in the quality of life of cancer patients. It is well-established that neuroinflammation and the activation of immune and glial cells are among the major drivers of CIPN. However, these processes are still poorly understood, and while many chemotherapy drugs alone can drive the activation of these cells and consequent neuroinflammation, it remains elusive to what extent the gut microbiome influences these processes. In this review, we focus on the peripheral mechanisms driving CIPN, and we address the bidirectional pathways by which the gut microbiome communicates with the immune and nervous systems. Additionally, we critically evaluate literature addressing how chemotherapy-induced dysbiosis and the consequent imbalance in bacterial products may contribute to the activation of immune and glial cells, both of which drive neuroinflammation and possibly CIPN development, and how we could use this knowledge for the development of effective treatment strategies.

The metabolites of lactic acid bacteria: classification, biosynthesis and modulation of gut microbiota

Lactic acid bacteria (LAB) are ubiquitous microorganisms that can colonize the intestine and participate in the physiological metabolism of the host. LAB can produce a variety of metabolites, including organic acids, bacteriocin, amino acids, exopolysaccharides and vitamins. These metabolites are the basis of LAB function and have a profound impact on host health. The intestine is colonized by a large number of gut microorganisms with high species diversity. Metabolites of LAB can keep the balance and stability of gut microbiota through aiding in the maintenance of the intestinal epithelial barrier, resisting to pathogens and regulating immune responses, which further influence the nutrition, metabolism and behavior of the host. In this review, we summarize the metabolites of LAB and their influence on the intestine. We also discuss the underlying regulatory mechanisms and emphasize the link between LAB and the human gut from the perspective of health promotion.

Immune-Enhancing Effects of Limosilactobacillus fermentum in BALB/c Mice Immunosuppressed by Cyclophosphamide

This study evaluates the immune-enhancing effects of Limosilactobacillus fermentum on cyclophosphamide (CP)-induced immunosuppression in BALB/c mice. In vitro, the expressions of pro-inflammatory cytokines and MAPK signaling molecules in Raw264.7 cells were analyzed by ELISA and Western blot analysis. Moreover, cell proliferation, surface receptor expression, and cytotoxicity of NK-92 cells were examined by Cell Counting Kit-8, CytoTox96 assay, and flow cytometry, respectively. To investigate the immune-enhancing effects of selected L. fermentum strains in vivo, these strains were orally administered to BALB/c mice for 2 weeks, and CP was intraperitoneally injected. Then, liver, spleen, and whole blood were isolated from each animal. Administration of single L. fermentum strains or their mixture sustained the spleen weight, the counts of white blood cells compared to non-fed group. Splenocyte proliferation and NK cytotoxicity were significantly increased in all L. fermentum-fed groups. The frequency of B220+ cells was also significantly enhanced in splenocytes isolated from L. fermentum groups. In addition, the production of cytokines (TNF-α, IFN-γ) and antibodies was recovered in splenocyte supernatants isolated from L. fermentum groups. In conclusion, L. fermentum could be a suitable functional food additive for immune-enhancing effect.

The role of Th17 cells in inflammatory bowel disease and the research progress

Th17 cells play an important role in the abnormal immune response in inflammatory bowel disease (IBD) and are involved in the development and progression of inflammation and fibrosis. An increasing amount of data has shown that gut microbes are important parts of intestinal immunity and regulators of Th17 cellular immunity. Th17 cell differentiation is regulated by intestinal bacteria and cytokines, and Th17 cells regulate the intestinal mucosal immune microenvironment by secreting cytokines, such as IL-17, IL-21, and IL-26. Solid evidence showed that, regarding the treatment of IBD by targeting Th17 cells, the therapeutic effect of different biological agents varies greatly. Fecal bacteria transplantation (FMT) in the treatment of IBD has been a popular research topic in recent years and is safe and effective with few side effects. To further understand the role of Th17 cells in the progression of IBD and associated therapeutic prospects, this review will discuss the progress of related research on Th17 cells in IBD by focusing on the interaction and immune regulation between Th17 cells and gut microbiota.

The potential application of probiotics for the prevention and treatment of COVID-19

Background

Given the severe infection, poor prognosis, and the low number of available effective drugs, potential prevention and treatment strategies for COVID-19 need to be urgently developed.

Main body

Herein, we present and discuss the possible protective and therapeutic mechanisms of human microbiota and probiotics based on the previous and recent findings. Microbiota and probiotics consist of mixed cultures of living microorganisms that can positively affect human health through their antiviral, antibacterial, anti-inflammatory, and immunomodulatory effect. In the current study, we address the promising advantages of microbiota and probiotics in decreasing the risk of COVID-19.

Conclusions

Thus, we recommend further studies be conducted for assessing and evaluating the capability of these microbes in the battle against COVID-19.

An autologous colonic organoid‐derived monolayer model to study immune: bacterial interactions in Crohn's disease patients

Objectives

Crohn's disease (CD) initiation and pathogenesis are believed to involve an environmental trigger in a genetically susceptible person that results in an immune response against commensal gut bacteria, leading to a compromised intestinal epithelial barrier and a cycle of inflammation. However, it has been difficult to study the contribution of all factors together in a physiologically relevant model and in a heterogenous patient population.

Methods

We developed an autologous colonic monolayer model that incorporated the immune response from the same donor and a commensal bacteria, Faecalibacterium prausnitzii. Two‐dimensional monolayers were grown from three‐dimensional organoids generated from intestinal biopsies, and the epithelial integrity of the epithelium was measured using transepithelial electrical resistance. We determined the effect of immune cells alone, bacteria alone and the co‐culture of immune cells and bacteria on integrity.

Results

Monolayers derived from CD donors had impaired epithelial integrity compared to those from non‐inflammatory bowel disease (IBD) donors. This integrity was further impaired by culture with bacteria, but not immune cells, despite a higher frequency of inflammatory phenotype peripheral T cells in CD donors. Variability in epithelial integrity was higher in CD donors than in non‐IBD donors.

Conclusion

We have developed a new autologous model to study the complexity of CD, which allows for the comparison of the barrier properties of the colonic epithelium and the ability to study how autologous immune cells directly affect the colonic barrier and whether this is modified by luminal bacteria. This new model allows for the study of individual patients and could inform treatment decisions.

Theoretical benefits of yogurt-derived bioactive peptides and probiotics in COVID-19 patients - A narrative review and hypotheses

The world is currently facing a frightening coronavirus disease-2019 (COVID-19) epidemic. Severity of COVID-19 presentation is highly variable among infected individuals with increasingly recognized risk factors. Although observational studies suggested lower COVID-19 severity in populations consuming fermented foods, no controlled study investigated the role of diet. Yogurt, a fermented dairy product, exhibits interesting properties related to the presence of bioactive peptides and probiotics that may play a beneficial role in COVID-19 presentation and outcome. Peptides contained in yogurt are responsible for angiotensin-converting enzyme-inhibitory, bradykinin potentiating, antiviral, anti-inflammatory, antithrombotic, and antioxidant effects. The types and activity of these peptides vary widely depending on their amino acid sequence, on the probiotics used in yogurt production and on intestinal digestion. Additionally, probiotics used in yogurt exhibit direct angiotensin-converting enzyme-inhibitory, antiviral and immune boosting activities. Since COVID-19 pathogenesis involves angiotensin II accumulation and bradykinin deficiency, yogurt bioactive peptides appear as potentially beneficial. Therefore, epidemiological investigations and randomized controlled clinical trials to evaluate the exact role of yogurt consumption on COVID-19 manifestations and outcome should be encouraged.

Examining the Gastrointestinal and Immunomodulatory Effects of the Novel Probiotic Bacillus subtilis DE111

Probiotics make up a large and growing segment of the commercial market of dietary supplements and are touted as offering a variety of human health benefits. Some of the purported positive impacts of probiotics include, but are not limited to, stabilization of the gut microbiota, prevention of gastrointestinal disorders and modulation of the host immune system. Current research suggests that the immunomodulatory effects of probiotics are strain-specific and vary in mode of action. Here, we examined the immunomodulatory properties of Bacillus subtilis strain DE111 in a healthy human population. In a pilot randomized, double blind, placebo-controlled four-week intervention, we examined peripheral blood mononuclear cells (PBMCs) at basal levels pre- and post-intervention, as well as in response to stimulation with bacterial lipopolysaccharide (LPS). We observed an increase in anti-inflammatory immune cell populations in response to ex vivo LPS stimulation of PBMCs in the DE111 intervention group. Overall perceived gastrointestinal health, microbiota, and circulating and fecal markers of inflammation (Il-6, sIgA) and gut barrier function (plasma zonulin) were largely unaffected by DE111 intervention, although the study may have been underpowered to detect these differences. These pilot data provide information and justification to conduct an appropriately powered clinical study to further examine the immunomodulatory potential of B. subtilis DE111 in human populations.

The potential application of probiotics and prebiotics for the prevention and treatment of COVID-19

COVID-19 is a pandemic disease caused by the novel coronavirus severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). This new viral infection was first identified in China in December 2019, and it has subsequently spread globally. The lack of a vaccine or curative treatment for COVID-19 necessitates a focus on other strategies to prevent and treat the infection. Probiotics consist of single or mixed cultures of live microorganisms that can beneficially affect the host by maintaining the intestinal or lung microbiota that play a major role in human health. At present, good scientific evidence exists to support the ability of probiotics to boost human immunity, thereby preventing colonization by pathogens and reducing the incidence and severity of infections. Herein, we present clinical studies of the use of probiotic supplementation to prevent or treat respiratory tract infections. These data lead to promising benefits of probiotics in reducing the risk of COVID-19. Further studies should be conducted to assess the ability of probiotics to combat COVID-19.

Gut microbiota regulates neuropathic pain: potential mechanisms and therapeutic strategy

Neuropathic pain (NP) is a sustained and nonreversible condition characterized by long-term devastating physical and psychological damage. Therefore, it is urgent to identify an effective treatment for NP. Unfortunately, the precise pathogenesis of NP has not been elucidated. Currently, the microbiota-gut-brain axis has drawn increasing attention, and the emerging role of gut microbiota is investigated in numerous diseases including NP. Gut microbiota is considered as a pivotal regulator in immune, neural, endocrine, and metabolic signaling pathways, which participates in forming a complex network to affect the development of NP directly or indirectly. In this review, we conclude the current understanding of preclinical and clinical findings regarding the role of gut microbiota in NP and provide a novel therapeutic method for pain relief by medication and dietary interventions.

Lactobacillus fermentum species ameliorate dextran sulfate sodium-induced colitis by regulating the immune response and altering gut microbiota

We evaluated immunometabolic functions of novel Lactobacillus fermentum strains (KBL374 and KBL375) isolated from feces of healthy Koreans. The levels of inflammatory cytokines, such as interleukin (IL)-2, interferon-γ, IL-4, IL-13, and IL-17A, were decreased, and that of the anti-inflammatory cytokine IL-10 was increased, in human peripheral blood mononuclear cells (PBMCs) treated with the L. fermentum KBL374 or KBL375 strain. When these strains were orally administered to mice with dextran sulfate sodium (DSS)-induced colitis, both L. fermentum KBL374 and KBL375 showed beneficial effects on body weight, disease activity index score, colon length, cecal weight, and histological scores. Furthermore, both L. fermentum KBL374 and KBL375 modulated the innate immune response by improving gut barrier function and reducing leukocyte infiltration. Consistent with the PBMC data, both L. fermentum KBL374- and KBL375-treated DSS mice demonstrated decreased Th1-, Th2-, and Th17-related cytokine levels and increased IL-10 in the colon compared with the DSS control mice. Administration of L. fermentum KBL374 or KBL375 to mice increased the CD4+CD25+Foxp3+Treg cell population in mesenteric lymph nodes. Additionally, L. fermentum KBL374 or KBL375 administration reshaped and increased the diversity of the gut microbiota. In particular, L. fermentum KBL375 increased the abundance of beneficial microorganisms, such as Lactobacillus spp. and Akkermansia spp. Both L. fermentum KBL374 and KBL375 may alleviate inflammatory diseases, such as inflammatory bowel disease, in the gut by regulating immune responses and altering the composition of gut microbiota.

Immunomodulatory effects of probiotics: Can they be used to treat allergies and autoimmune diseases?

As a person ages, physiological, immunological and gut microbiome changes collectively result in an array of chronic conditions. According to the 'hygiene hypothesis' the increasing prevalence of immune-mediated disorders may be related to intestinal dysbiosis, leading to immune dysfunction and associated conditions such as eczema, asthma, allergies and autoimmune diseases. Beneficial probiotic bacteria can be utilized by increasing their abundance within the gastrointestinal lumen, which in turn will modulate immune cells, such as, T helper (Th)-1, Th2, Th17, regulatory T (Treg) cells and B cells, which have direct relevance to human health and the pathogenesis of immune disorders. Here, we describe the cross-talk between probiotics and the gastrointestinal immune system, and their effects in relation to inflammatory bowel disease, multiple sclerosis, allergies and atopic dermatitis.

Postnatal Administration of Lactobacillus rhamnosus HN001 Ameliorates Perinatal Broad-Spectrum Antibiotic-Induced Reduction in Myelopoiesis and T Cell Activation in Mouse Pups

SCOPE

This study addresses whether administration of Lactobacillus rhamnosus HN001 could mitigate the effects of a compromised gut microbiota on the composition of mature leukocytes and granulocyte-macrophage progenitor cells (GMPs) in newborn mice.

METHODS AND RESULTS

Pregnant dams receive oral broad-spectrum antibiotics, which dramatically decrease the gut microbial composition analyzed by 16S rRNA sequencing. Perinatal antibiotic treatment decreases the proportions of bone marrow (BM) GMPs (postnatal day (PND2): 0.5% vs 0.8%, PND4: 0.2% to 0.6%) and mature granulocytes (33% vs 24% at PND2), and spleen granulocytes (7% vs 17% at PND2) and B cells (PND2:18% vs 28%, PND4:11% vs 22%). At PND35, T helper (Th) cells (20% vs 14%) and cytotoxic T (Tc) cells (10% vs 8%) decrease in the spleen. Oral administration of L. rhamnosus HN001 to neonatal pups (PND1-7) restores the antibiotic-induced changes of GMPs and granulocytes in BM and spleen, and further increases splenic granulocytes in control pups. At PND35, splenic proportions of B and Th but not Tc cells are restored.

CONCLUSION

Postnatal administration of a single bacterial strain efficiently restores granulopoiesis and most T cell activation in neonatal mice that suffer from a perinatal antibiotic-induced compromised gut microbiota at birth.

Anti-inflammaging effects of Lactobacillus brevis OW38 in aged mice

In the present study, lactic acid bacteria (LAB) strains were collected from kimchi and were screened to isolate strains that inhibit lipopolysaccharide (LPS) production by Escherichia coli and p16 expression and nuclear factor-kappa B (NF-κB) activation in LPS-stimulated macrophages. Oral administration of Lactobacillus brevis OW38 (1×109 cfu/mouse) to aged mice (male, 18 months old) for 8 weeks reduced the LPS level in colon fluid and blood. In addition, OW38 treatment also reduced the ratio of Firmicutes or Proteobacteria to Bacteroidetes, which was significantly higher in aged mice than in young mice. Treatment with OW38 in aged mice inhibited the expression of inflammatory markers, such as myeloperoxidase, tumour necrosis factor (TNF), and interleukin (IL)-1β, and inhibited NF-κB activation. Furthermore, it induced the expression of colonic tight junction proteins zonula occludens-1, occludin, and claudin-1. OW38 treatment also suppressed the expression of senescence markers p16, p53, and SAMHD1 in the colon and the hippocampus of aged mice. In addition, it significantly restored spontaneous alternation as well as the expression of brain-derived neurotrophic factor and doublecortin in aged mice compared to that in young mice (P<0.05). Based on these findings, we conclude that OW38 treatment may ameliorate aging-associated colitis and memory impairment by inhibiting gut microbiota LPS production, NF-κB activation, and p16 expression.

The effect of a probiotic Escherichia coli strain on regulatory T-cells in six year-old children

Probiotics are believed to prevent or reduce allergy development but the mechanism of their beneficial effect is still poorly understood. Immune characteristics of regulatory T cells (Tregs) in peripheral blood of perinatally probiotic-supplemented children of allergic mothers (51 children), non-supplemented children of allergic mothers (42 children), and non-supplemented children of healthy mothers (28 children) were compared at the age of 6-7 years. A first dose of a probiotic Escherichia coli strain (E. coli O83:K24:H31) was administered within 2 days after the birth and then 12 times during the first months of life and children were followed longitudinally. Proportion and functional properties of Tregs were estimated by flow cytometry in relation to the children's allergy status. Proportion of Tregs in the peripheral blood of children suffering from allergy tends to be higher whereas median of fluorescence intensity (MFI) of FoxP3 was significantly decreased in allergic group. Intracellular presence of regulatory cytokine interleukin (IL)-10 was also lower in allergic children. Immune functions of Tregs reflected by both MFI of FoxP3 and IL-10 in the group of probiotic-supplemented children of allergic mothers were nearly comparable with children of healthy mothers while probiotic non-supplemented children of allergic mothers have decreased immune function of Tregs. Supplementation by probiotic E. coli strain decreases allergy incidence in high-risk children. In contrast to our expectation, proportion of Tregs has not been increased in probiotic supplemented children. Beneficial effect of probiotics on newborn immature immune system could be, at least partially, explained by the modulating immune function of Tregs. In summary, we detected increased proportion of Tregs in peripheral blood of allergic children, their functional properties were decreased in comparison with the Tregs of healthy children. A unifying hypothesis for these findings is that Treg numbers in allergic children are increased in order to compensate for decreased function.

Pellet feed adsorbed with the recombinant Lactococcus lactis BFE920 expressing SiMA antigen induced strong recall vaccine effects against Streptococcus iniae infection in olive flounder (Paralichthys olivaceus)

The aim of this study was to develop a fish feed vaccine that provides effective disease prevention and convenient application. A lactic acid bacterium (LAB), Lactococcus lactis BFE920, was modified to express the SiMA antigen, a membrane protein of Streptococcus iniae. The antigen was engineered to be expressed under the nisin promoter, which is induced by nisin produced naturally by the host LAB. Various sizes (40 ± 3.5 g, 80 ± 2.1 g, and 221 ± 2.4 g) of olive flounder (Paralichthys olivaceus) were vaccinated by feeding the extruded pellet feed, onto which the SiMA-expressing L. lactis BFE920 (1.0 × 10(7) CFU/g) was adsorbed. Vaccine-treated feed was administered twice a day for 1 week, and priming and boosting were performed with a 1-week interval in between. The vaccinated fish had significantly elevated levels of antigen-specific serum antibodies and T cell marker mRNAs: CD4-1, CD4-2, and CD8a. In addition, the feed vaccine significantly induced T cell effector functions, such as the production of IFN-γ and activation of the transcription factor that induces its expression, T-bet. When the flounder were challenged by intraperitoneal infection and bath immersion with S. iniae, the vaccinated fish showed 84% and 82% relative percent survival (RPS), respectively. Furthermore, similar protective effects were confirmed even 3 months after vaccination in a field study (n = 4800), indicating that this feed vaccine elicited prolonged duration of immunopotency. In addition, the vaccinated flounder gained 21% more weight and required 16% less feed to gain a unit of body weight compared to the control group. The data clearly demonstrate that the L. lactis BFE920-SiMA feed vaccine has strong protective effects, induces prolonged vaccine efficacy, and has probiotic effects. In addition, this LAB-based fish feed vaccine can be easily used to target many different pathogens of diverse fish species.

In vitro evidence for efficacy in food intolerance for the multispecies probiotic formulation Ecologic® Tolerance (Syngut™)

The beneficial effects of probiotics are currently the subject of extensive studies in health and medical research. The aim of this research was to specifically design a new probiotic formulation for supplementation in people suffering from food intolerance. The selection of strains was focussed on the capacity to influence mechanisms of action that are important in development of food intolerance with the following parameters measure: in vitro capacity to produce β-galactosidase, in vitro strengthening of the epithelial barrier, in vitro stimulation of cytokines produced by regulatory T cells, in addition to assessing fundamental quality criteria (stability, gastrointestinal (GI)-survival, multispecies concept, allergen-free). Ecologic®Tolerance/Syngut™ was subsequently developed consisting of a multispecies concept using 4 different probiotic strains (Bifidobacterium lactis W51, Lactobacillus acidophilus W22, Lactobacillus plantarum W21 and Lactococcus lactis W19). Each of these strains demonstrated ability to survive the GI-tract and strain specific effects in producing β-galactosidase, strengthening the gut barrier function after immunological-induced stress and inhibiting Th2 cytokines (IL-4, IL-5 and IL-13 (≥50%), in addition to stimulating interleukin-10 levels; thus, providing in vitro evidence for the efficacy of the selected strains to provide beneficial effects in patients suffering from food intolerance.

Differential Metabolism of Exopolysaccharides from Probiotic Lactobacilli by the Human Gut Symbiont Bacteroides thetaiotaomicron

Probiotic microorganisms are ingested as food or supplements and impart positive health benefits to consumers. Previous studies have indicated that probiotics transiently reside in the gastrointestinal tract and, in addition to modulating commensal species diversity, increase the expression of genes for carbohydrate metabolism in resident commensal bacterial species. In this study, it is demonstrated that the human gut commensal species Bacteroides thetaiotaomicron efficiently metabolizes fructan exopolysaccharide (EPS) synthesized by probiotic Lactobacillus reuteri strain 121 while only partially degrading reuteran and isomalto/malto-polysaccharide (IMMP) α-glucan EPS polymers. B. thetaiotaomicron metabolized these EPS molecules via the activation of enzymes and transport systems encoded by dedicated polysaccharide utilization loci specific for β-fructans and α-glucans. Reduced metabolism of reuteran and IMMP α-glucan EPS molecules may be due to reduced substrate binding by components of the starch utilization system (sus). This study reveals that microbial EPS substrates activate genes for carbohydrate metabolism in B. thetaiotaomicron and suggests that microbially derived carbohydrates provide a carbohydrate-rich reservoir for B. thetaiotaomicron nutrient acquisition in the gastrointestinal tract.

Impact of kefir derived Lactobacillus kefiri on the mucosal immune response and gut microbiota

The evaluation of the impact of probiotics on host health could help to understand how they can be used in the prevention of diseases. On the basis of our previous studies and in vitro assays on PBMC and Caco-2 ccl20:luc reporter system presented in this work, the strain Lactobacillus kefiri CIDCA 8348 was selected and administrated to healthy Swiss mice daily for 21 days. The probiotic treatment increased IgA in feces and reduced expression of proinflammatory mediators in Peyer Patches and mesenteric lymph nodes, where it also increased IL-10. In ileum IL-10, CXCL-1 and mucin 6 genes were upregulated; meanwhile in colon mucin 4 was induced whereas IFN-γ, GM-CSF, and IL-1β genes were downregulated. Moreover, ileum and colon explants showed the anti-inflammatory effect of L. kefiri since the LPS-induced increment of IL-6 and GM-CSF levels in control mice was significantly attenuated in L. kefiri treated mice. Regarding fecal microbiota, DGGE profiles allowed differentiation of experimental groups in two separated clusters. Quantitative PCR analysis of different bacterial groups revealed only significant changes in Lactobacillus population. In conclusion, L. kefiri is a good candidate to be used in gut inflammatory disorders.

The effects of combined dietary probiotics Lactococcus lactis BFE920 and Lactobacillus plantarum FGL0001 on innate immunity and disease resistance in olive flounder (Paralichthys olivaceus)

The effects of a dietary probiotic mixture containing Lactococcus (Lc.) lactis BFE920 isolated from bean sprout and autochthonous Lactobacillus (Lb.) plantarum FGL0001 originally isolated from the hindgut of olive flounder (Paralichthys olivaceus) were investigated for the purpose of improving the probiotic effects of Lc. lactis BFE920 on the olive flounder. The immunostimulatory, disease protective, and weight gain effects of Lc. lactis BFE920 were significantly improved when olive flounder (average weight 37.5±1.26 g) were fed the probiotic mixture (log10 7.0 CFU each/g feed pellet) for 30 days. Flounder fed the mixture showed improved skin mucus lysozyme activity and phagocytic activity of innate immune cells compared to flounder fed a single probiotic agent or a control diet. While the levels of neutrophil activity in flounder fed the single probiotic agent or the mixture were similar, they were significantly higher than levels in a control group. Additionally, probiotic-fed flounder showed significantly increased expressions of IL-6, IL-8, and TNF-α in the intestine compared to the control group. Following a 30-day period of being fed probiotics or a control diet, the olive flounder were challenged with an i.p. injection of Streptococcus iniae (log10 6.0 CFU/fish). The groups fed the mixed probiotics, Lc. lactis BFE920, Lb. plantarum FGL0001, and the control diet had survival rates of 55%, 45%, 35%, and 20%, respectively. Flounder fed the probiotic mixture gained 38.1±2.8% more body weight compared to flounder fed the control diet during the 30-day study period. These data strongly suggest that a mixture of Lc. lactis BFE920 and Lb. plantarum FGL0001 may serve as an immunostimulating feed additive useful for disease protection in the fish farming industry.

Bifidobacterium breve attenuates murine dextran sodium sulfate-induced colitis and increases regulatory T cell responses

While some probiotics have shown beneficial effects on preventing or treating colitis development, others have shown no effects. In this study, we have assessed the immunomodulating effects of two probiotic strains, Lactobacillus rhamnosus (L. rhamnosus) and Bifidobacterium breve (B. breve) on T cell polarization in vitro, using human peripheral blood mononuclear cells (PBMC), and in vivo, using murine dextran sodium sulfate (DSS) colitis model. With respect to the latter, the mRNA expression of T cell subset-associated transcription factors and cytokines in the colon was measured and the T helper type (Th) 17 and regulatory T cell (Treg) subsets were determined in the Peyer's patches. Both L. rhamnosus and B. breve incubations in vitro reduced Th17 and increased Th2 cell subsets in human PBMCs. In addition, B. breve incubation was also able to reduce Th1 and increase Treg cell subsets in contrast to L. rhamnosus. In vivo intervention with B. breve, but not L. rhamnosus, significantly attenuated the severity of DSS-induced colitis. In DSS-treated C57BL/6 mice, intervention with B. breve increased the expression of mRNA encoding for Th2- and Treg-associated cytokines in the distal colon. In addition, intervention with B. breve led to increases of Treg and decreases of Th17 cell subsets in Peyer's patches of DSS-treated mice. B. breve modulates T cell polarization towards Th2 and Treg cell-associated responses in vitro and in vivo. In vivo B. breve intervention ameliorates DSS-induced colitis symptoms and this protective effect may mediated by its effects on the T-cell composition.

Probiotics and prebiotics in neonatal necrotizing enterocolitis: New opportunities for translational research

Neonatal necrotizing enterocolitis (NEC) in premature infants has been recognized as a defined disease entity for at least four decades. Although survival has increased due to the advent of more sophisticated intensive care, incidence and long term health impacts due to NEC remain unchanged and no preventive therapy is currently available. Different probiotic strains of bacteria have been examined in their ability to prevent NEC with varied but encouraging results. Undigestable prebiotic sugars known to promote the growth of probiotic bacteria in the colon have been used in neonates with no clear benefit. The literature on NEC and probiotics is now cluttered with more reviews and meta-analyses than number of clinical trials. On the other hand, significant new information is available on microbiota and their impact on gut immunity. This review attempts to reiterate the risk factors of NEC and the pathogenesis of NEC with special reference to gut permeability. The reader is then introduced to gut microbiota, uniqueness and differences among probiotic strains, and how multiple resident flora talk to each other in the community setting in the human gut. After presenting a concise review of available clinical research results, the reader is challenged to question as to why no precise answer is available at present. Some modalities to examine the complex microflora and changes in the neonatal gut are then proposed including non-invasive methods and mathematical modeling. The review concludes by attracting the reader's attention to known immunomodulators of inflammation and injury. Justice to this review will be done only if the readers, clinical, and basic science investigators from multiple fields gather courage for a paradigm shift and embark on understanding the pathophysiology of the disease and attempt to discern the difference from equally preterm, equally vulnerable neonates that do not develop NEC. Learning about the developing microbiota in neonatal gut and its immunological impacts on the host in the face of many variables will provide a leap in our pursuit to select better, if not the best candidate probiotics, and put them to work against this stubborn disease that continues to take a toll on our precious neonates and the society.

Effects of Lactobacillus rhamnosus LA68 on the immune system of C57BL/6 mice upon oral administration

Probiotic bacteria have been used in human nutrition for centuries and are now attracting more attention. In order to examine the immunological aspects of probiotic consumption, Lactobacillus rhamnosus LA68 was orally administrated using gavage to healthy C57BL/6 mice. After one month splenocytes were isolated, and analysed by flow cytometry. The magnitude of splenocyte proliferation upon stimulation with lipopolysaccharide and peptidoglycan and cytokine levels (IFN-γ, IL-6, IL-10 and IL-17) was assessed. Cytokine levels in the serum were also analysed. Oral application of strain LA68 leads to a significant decrease of CD3+, CD25+ and CD19+ cells, and an increase of CD11b+ and CD16/CD32+ positive cell populations in the mouse spleen. Increased sensitivity to stimulation through proliferation and IL-6 secretion was detected. Increased serum IFN-γ and decreased IL-10 levels were found. Our results show increased responsiveness of splenocytes, activation of the Th1 type of immune response, and a shift of leucocyte populations towards monocyte/granulocyte populations.

Exopolysaccharide-producing Bifidobacterium animalis subsp. lactis strains and their polymers elicit different responses on immune cells from blood and gut associated lymphoid tissue

The effect of exopolysaccharide (EPS) producing bifidobacteria, and the EPS derived thereof, on the modulation of immune response was evaluated. Cells isolated from gut associated lymphoid tissue (GALT) and from peripheral blood mononuclear cells (PBMC) of naïve rats were used. The proliferation and cytokine production of these immune cells in the presence of the three isogenic Bifidobacterium animalis subsp. lactis strains (A1, A1dOx and A1dOxR), as well as their purified polymers, were in vitro analysed. The cytokine pattern produced by immune cells isolated from GALT showed that most levels remained stable in the presence of the three strains or their corresponding polymers. However, in PBMC the UV-inactivated bacteria induced higher levels of the ratios IFNγ/IL-17, TNFα/IL-10 and TNFα/TGFβ, and no variation in the ratio IFNγ/IL-4. Thus, B. animalis subsp. lactis strains were able to activate blood monocytes as well as T lymphocytes towards a mild inflammatory Th1 response. Furthermore, only the EPS-A1dOxR was able to stimulate a response in a similar way than its EPS-producing bacterium. Our work supports the notion that some bifidobacterial EPS could play a role in mediating the dialog of these microorganisms with the immune system. In addition, this study emphasizes the effect that the origin of the immune cells has in results obtained; this could explain the great amount of contradiction found in literature about the immunomodulation capability of EPS from probiotic bacteria.

Interaction with intestinal epithelial cells promotes an immunosuppressive phenotype in Lactobacillus casei

Maintenance of the immunological tolerance and homeostasis in the gut is associated with the composition of the intestinal microbiota. We here report that cultivation of Lactobacillus casei ATCC 334 in the presence of human intestinal epithelial cells promotes functional changes in bacteria. In particular, the interaction enhanced the immunosuppressive phenotype of L. casei as demonstrated by the ability of L. casei to generate functional regulatory T cells (CD4+CD25+FoxP3+) and production of the anti-inflammatory cytokine interleukin-10 by human peripheral blood mononuclear cells. The results indicate microbe-host cross-talk that changes features of microbes, and suggest that in vitro simulation of epithelial cell interaction can reveal functional properties of gut microbes more accurately than conventional cultivation.

Gut microbiota, host health, and polysaccharides

The intestinal microbiota is a complicated ecosystem that influences many aspects of host physiology (i.e. diet, disease development, drug metabolism, and regulation of the immune system). It also exhibits spatial patterning and temporal dynamics. In this review, the effects of internal and external (environmental) factors on intestinal microbiota are discussed. We describe the roles of the gut microbiota in maintaining intestinal and immune system homeostasis and the relationship between gut microbiota and diseases. In particular, the contributions of polysaccharides, as the most abundant diet components in intestinal microbiota and host health are presented. Finally, perspectives for research avenues relating to gut microbiota are also discussed.

β-Glucans are involved in immune-modulation of THP-1 macrophages

SCOPE

We aimed to examine different immunological aspects of β-glucans derived from different food sources (oat, barley and shiitake) on phorbol myristate acetate (PMA)-differentiated THP-1 macrophages. Commercially purified barley β-glucan (commercial BG) and lentinan were included to compare β-glucans from the same origin but different degree of purity and processing.

METHODS AND RESULTS

Chemical composition and molecular weight distribution of β-glucan samples were determined. Inflammation-related gene expression kinetics (IL-1β, IL-8, nuclear factor kappa B [NF-κB] and IL-10) after 3, 6 and 24 h of stimulation with 100 μg/mL β-glucan were investigated. All tested β-glucans mildly upregulated the observed inflammation-related genes with differential gene expression patterns. Similar gene expression kinetics, but different fold induction values, was found for the crude β-glucan extracts and their corresponding commercial forms. Pre-incubation of THP-1 macrophages with β-glucans prior to lipopolysaccharide (LPS) exposure decreased the induction of inflammation-related genes compared to LPS treatment. No production of nitric oxide (NO) and hydrogen peroxide (H₂O₂) was detected in β-glucan stimulated THP-1 macrophages. Phagocytic activity was not different after stimulation by β-glucan samples.

CONCLUSION

Based on these in vitro analyses, it can be concluded that the analysed β-glucans have varying levels of immunomodulating properties, which are likely related to structure, molecular weight and compositional characteristic of β-glucan.