Bifidobacterium longum 1714 improves sleep quality and aspects of well-being in healthy adults: a randomized, double-blind, placebo-controlled clinical trial.

Stress and sleep are linked with overall well-being. Bifidobacterium longum 1714 has been shown to influence stress responses and modulate neural responses during social stress, and influence sleep quality during examination stress in healthy adults. Here, we explored the ability of this strain to alter sleep quality in adults using subjective and objective measures. Eighty-nine adults (18-45y) with impaired sleep quality assessed with the Pittsburgh Sleep Quality Index (PSQI) and with a global score ≥ 5 were randomized to receive B. longum 1714 or placebo daily for eight weeks. Assessing the effect of the strain on PSQI global score was the primary objective. Secondary objectives assessed sleep quality and well-being subjectively and sleep parameters using actigraphy objectively. While PSQI global score improved in both groups, B. longum 1714 significantly improved the PSQI component of sleep quality (p < 0.05) and daytime dysfunction due to sleepiness (p < 0.05) after 4 weeks and social functioning (p < 0.05) and energy/vitality (p < 0.05) after 8 weeks, compared to placebo. No significant effect on actigraphy measures were observed. The 1714 strain had a mild effect on sleep, demonstrated by a faster improvement in sleep quality at week 4 compared to placebo, although overall improvements after 8 weeks were similar in both groups. B. longum 1714 improved social functioning and increased energy/vitality in line with previous work that showed the strain modulated neural activity which correlated with enhanced vitality/reduced mental fatigue (ClinicalTrials.gov: NCT04167475).

Impact of Bifidobacterium longum1714® on maternal cytokine response in peripheral blood mononuclear cells.

PURPOSE: The maternal immune system is implicated in adverse pregnancy outcomes. Manipulation of maternal immune response by probiotics holds potential to reduce pregnancy complications. The MicrobeMom2 study investigates the impact of probiotic supplementation on maternal immune responses to pathogen associated molecular patterns (PAMPs) in peripheral blood mononuclear cells (PBMCs) during pregnancy. METHODS: This double-blinded randomised-controlled trial involved oral supplementation of Bifidobacterium longum subsp. longum 1714® (B. longum 1714; daily ingestion of a minimum of 1x109 colony forming units) or placebo from 16 to 20-weeks' gestation until delivery in healthy pregnant women. The primary outcome was a change in IL-10 production, after stimulation with Lipopolysaccharide (LPS) or anti-CD3/28/2, in PBMCs isolated from blood samples taken at baseline (11-15 weeks' gestation) and late pregnancy (28-32 weeks' gestation) after 48 h incubation. 68 subjects were needed (34ineachgroup) for 80 % power at an alpha significance of 0.05 to detect differences in IL10. RESULTS: 72 women (mean ± SD age 33.17 ± 4.53 years and median (25th, 75th centile) body mass index 24.93 (21.93, 27.57 kg/m2)) were recruited with primary outcome data. Using LPS, late pregnancy fold change in IL-10 in PBMCs after 48 h incubation was median (25th, 75th centile) 88.45 (4.88, 488.78) in the intervention, 24.18 (6.36, 141.17) in the control group, p = 0.183. Using anti-CD3/28/2, values were 189.69 (425.96, 866.57),148.74 (31.67, 887.03) in intervention and control groups, respectively, p = 0.506. No significant differences were observed between the two groups. CONCLUSION: Maternal antenatal supplementation with B. longum 1714 did not alter cytokine production by maternal PBMCs in response to PAMPs or anti-CD3/28/2. TRIAL REGISTRATION NUMBER: ISRCTN registry ISRCTN43013285.

Detailed mapping of Bifidobacterium strain transmission from mother to infant via a dual culture-based and metagenomic approach.

A significant proportion of the infant gut microbiome is considered to be acquired from the mother during and after birth. Thus begins a lifelong and dynamic relationship with microbes that has an enduring impact on host health. Based on a cohort of 135 mother-infant (F = 72, M = 63) dyads (MicrobeMom: ISRCTN53023014), we investigated the phenomenon of microbial strain transfer, with a particular emphasis on the use of a combined metagenomic-culture-based approach to determine the frequency of strain transfer involving members of the genus Bifidobacterium, including species/strains present at low relative abundance. From the isolation and genome sequencing of over 449 bifidobacterial strains, we validate and augment metagenomics-based evidence to reveal strain transfer in almost 50% of dyads. Factors important in strain transfer include vaginal birth, spontaneous rupture of amniotic membranes, and avoidance of intrapartum antibiotics. Importantly, we reveal that several transfer events are uniquely detected employing either cultivation or metagenomic sequencing, highlighting the requirement for a dual approach to obtain an in-depth insight into this transfer process.

Interactions between symptoms and psychological status in irritable bowel syndrome: An exploratory study of the impact of a probiotic combination.

BACKGROUND: Stress is an exacerbator of irritable bowel syndrome (IBS) symptoms, and anxiety and depression are co-morbidities. Bifidobacterium longum strains 1714® and 35642® attenuate stress responses in healthy people and reduce symptoms in IBS, respectively. Here, we explore relationships between the psychological and visceral effects of the two strains (COMBO) in IBS subjects and biomarkers of stress and inflammation. METHODS: We recruited 40 patients with IBS (Rome III) and mild to moderate anxiety (HADS-A) and/or depression (HADS-D) and 57 asymptomatic female controls with low or moderate stress. IBS patients were fed COMBO (1 × 109 cfu/day) for 8 weeks with an 8-week washout. IBS symptoms, psychometric measures, salivary cortisol awakening response (CAR), and plasma inflammatory biomarkers were assessed every 4 weeks. KEY RESULTS: Compared to healthy controls, IBS subjects had a blunted CAR. Treatment with COMBO restored CAR and improved IBS symptoms compared to baseline during the treatment phase. The COMBO reduced HADS-D, HADS-A score, and TNF-α, while sleep quality improved significantly from baseline to the end of the intervention. Surprisingly, these parameters improved further once treatment ended and maintained this improvement by Week 16. CONCLUSIONS AND INFERENCES: These findings suggest that the stress response is a major driver of IBS symptoms. The time course of the beneficial effect of COMBO on IBS symptoms suggests that this is achieved through a restoration of the stress response. In contrast, the time course of the effects of COMBO on anxiety and depression in IBS paralleled an anti-inflammatory effect as indicated by a reduction in circulating levels of TNF-α.

Environment-dependent alterations of immune mediators in urban and rural South African children with atopic dermatitis.

BACKGROUND: In order to improve targeted therapeutic approaches for children with atopic dermatitis (AD), novel insights into the molecular mechanisms and environmental exposures that differentially contribute to disease phenotypes are required. We wished to identify AD immunological endotypes in South African children from rural and urban environments. METHODS: We measured immunological, socio-economic and environmental factors in healthy children (n = 74) and children with AD (n = 78), in rural and urban settings from the same ethno-linguistic AmaXhosa background in South Africa. RESULTS: Circulating eosinophils, monocytes, TARC, MCP-4, IL-16 and allergen-specific IgE levels were elevated, while IL-17A and IL-23 levels were reduced, in children with AD regardless of their location. Independent of AD, children living in a rural environment had the highest levels of TNFα, TNFß, IL-1α, IL-6, IL-8, IL-21, MCP-1, MIP-1α, MIP-1ß, MDC, sICAM1, sVCAM1, VEGFA, VEGFD and Tie2, suggesting a generalized microinflammation or a pattern of trained immunity without any specific TH polarization. In contrast, IL-15, IL-22, Flt1, PIGF and ßFGF were highest in urban children. Rural healthy children had the lowest levels of food allergen-specific IgG4. Early life nutritional factors, medications, animal exposures, indoor environment, sunlight exposure, household size, household income and parental education levels were associated with differences in circulating cytokine levels. CONCLUSIONS: This study highlights the immunological impact of environmental exposures and socio-economic status in the manifestation of immune endotypes in children with AD living in urban and rural areas, which are important in selecting appropriately matched immunological therapies for treatment of AD.

Spermidine and spermine exert protective effects within the lung.

Asthma is a heterologous disease that is influenced by complex interactions between multiple environmental exposures, metabolism, and host immunoregulatory processes. Specific metabolites are increasingly recognized to influence respiratory inflammation. However, the role of protein-derived metabolites in regulating inflammatory responses in the lung are poorly described. The aims of the present study were to quantify polyamine levels in bronchoalveolar lavages (BALs) from healthy volunteers and asthma patients, and to evaluate the impact of each polyamine on inflammatory responses using in vitro models and in a house dust mite (HDM)-induced respiratory allergy model. Spermidine levels were decreased, while cadaverine levels were increased in BALs from asthma patients compared to healthy controls, using Ultra Performance Liquid Chromatography (UPLC). Both spermine and spermidine inhibit lipopolysaccharide (LPS)-induced cytokine secretion from human peripheral blood mononuclear cells (PBMCs) and dendritic cells (DCs) in vitro. In addition, oral gavage with spermine or spermidine modulate HDM-induced cell infiltration, cytokine secretion, and epithelial cell tight junction expression in murine models. Spermidine also reduces airway hyper-responsiveness. These results suggest that modulation of polyamine metabolism, in particular spermidine, is associated with respiratory inflammation and these molecules and pathways should be further explored as biomarkers of disease and potential targets for novel therapies.

An Exopolysaccharide Produced by Bifidobacterium longum 35624® Inhibits Osteoclast Formation via a TLR2-Dependent Mechanism.

The probiotic Bifidobacterium longum subsp. longum 35624® (B. longum 35624®), with its surface exopolysaccharide (EPS624), has previously been demonstrated to induce immunoregulatory responses in the host and may, therefore, be a novel approach to prevent bone loss in inflammatory conditions such as post-menopausal osteoporosis (PMO). The aim of this study was to investigate the effect of EPS624 on osteoclast and osteoblast differentiation and to assess the potential of B. longum 35624® to prevent bone loss in vivo. In vitro cell assays were used to assess the impact of EPS624 on osteoclast and osteoblast differentiation. The potential of two probiotic B. longum 35624® strains, including an EPS-deficient strain, for preventing ovariectomy (Ovx)-induced bone loss was assessed in a murine model. EPS624 prevented osteoclast formation from murine bone marrow precursors under both normal and TNFα-induced inflammatory conditions and modestly increased mineralized matrix deposition in osteogenic cell cultures. However, in the presence of an anti-TLR2 blocking antibody, or in MyD88-/- osteoclast precursors, the inhibitory effect of EPS624 on osteoclast formation was diminished or completely prevented, respectively. Moreover, EPS624 induced IL-10 production in osteoclast precursors in a TLR2-dependent manner, although IL-10 was dispensable in the EPS624-mediated inhibition of osteoclast formation. In addition, EPS624-producing B. longum 35624® partially prevented bone loss in Ovx mice when administered by oral gavage. This study introduced EPS624 as a potential anti-resorptive therapy, although optimal in vivo delivery of the probiotic strain for treating low-grade inflammatory diseases such as PMO remains to be determined.

Intranasal Bifidobacterium longum protects against viral-induced lung inflammation and injury in a murine model of lethal influenza infection.

BACKGROUND: Prophylactic strategies are urgently needed for prevention of severe inflammatory responses to respiratory viral infections. Bacterial-host interactions may modify the immune response to viral infections. METHODS: We examined the contribution of Intranasal administration of two different Bifidobacterium longum strains or its isolated cell wall in controlling viral induced inflammation using a murine model of influenza infection. We monitored mortality and morbidity over a 10-day period and viral load, differential broncho alveolar lavage (BAL) fluid inflammatory cell counts, Lung tissue histology, BAL and serum cytokines, markers of vascular damage and cell death were quantified. FINDINGS: Intranasal administration of Bifidobacterium longum35624® or its isolated cell wall prior to virus inoculation significantly reduced viral load within the lungs and significantly improved survival. Reduced viral load was associated with reduced lung injury as suggested by cell death and vascular leakage markers, a shift from neutrophil to macrophage recruitment, reduced inflammatory cytokine levels (including IL-6), reduced type 1 and 2 interferon levels, but increased levels of interferon-λ and surfactant protein D. These protective effects were maintained when the bifidobacterial cell wall preparation was administered 24 h after viral inoculation. The protective effects were also observed for the Bifidobacterium longumPB-VIR™ strain. INTERPRETATION: Exposure to these bifidobacterial strains protect against the inflammatory sequelae and damage associated with uncontrolled viral replication within the lung. FUNDING: This work has been funded, in part, by a research grant from GlaxoSmithKline, PrecisionBiotics Group Ltd., Swiss National Science Foundation grants (project numbers CRSII3_154488, 310030_144219, 310030_127356 and 310030_144219) and Christine Kühne - Center for Allergy Research and Education (CK-CARE).

Bacterial secretion of histamine within the gut influences immune responses within the lung.

BACKGROUND: Histamine is an important immunomodulator influencing both the innate and adaptive immune system. Certain host cells express the histidine decarboxylase enzyme (HDC), which is responsible for catalysing the decarboxylation of histidine to histamine. We and others have shown that bacterial strains can also express HDC and secrete histamine; however, the influence of bacterial-derived histamine on the host immune responses distant to the gut is unclear. METHODS: The Escherichia coli BL21 (E coli BL21) strain was genetically modified to express the Morganella morganii (M morganii)-derived HDC gene (E coli BL21_HTW). E coli BL21 and E coli BL21_HTW were gavaged to ovalbumin (OVA) sensitized and challenged mice to investigate the effect of bacterial-derived histamine on lung inflammatory responses. RESULTS: Oral administration of E coli BL21_HTW, which is able to secrete histamine, to wild-type mice reduced lung eosinophilia and suppressed ex vivo OVA-stimulated cytokine secretion from lung cells in the OVA respiratory inflammation mouse model. In histamine receptor 2 (H2R)-deficient mice, administration of histamine-secreting bacteria also reduced inflammatory cell numbers in bronchoalveolar lavage (BAL). However, the suppressive effect of bacterial-derived histamine on BAL inflammation was lost in HDC-deficient mice. This loss of activity was associated with increased expression of histamine degrading enzymes and reduced histamine receptor expression. CONCLUSION: Histamine secretion from bacteria within the gut can have immunological consequences at distant mucosal sites, such as within the lung. These effects are influenced by host histamine receptor expression and the expression of histamine degrading enzymes.

Biology of the Microbiome 1: Interactions with the Host Immune Response.

The intestinal immune system is intimately connected with the vast diversity of microbes present within the gut and the diversity of food components that are consumed daily. The discovery of novel molecular mechanisms, which mediate host-microbe-nutrient communication, have highlighted the important roles played by microbes and dietary factors in influencing mucosal immune responses. Dendritic cells, epithelial cells, innate lymphoid cells, T regulatory cells, effector lymphocytes, natural killer T cells, and B cells can all be influenced by the microbiome. Many of the mechanisms being described are bacterial strain or metabolite specific.

The Surface-Associated Exopolysaccharide of Bifidobacterium longum 35624 Plays an Essential Role in Dampening Host Proinflammatory Responses and Repressing Local TH17 Responses.

The immune-modulating properties of certain bifidobacterial strains, such as Bifidobacterium longum subsp. longum 35624 (B. longum 35624), have been well described, although the strain-specific molecular characteristics associated with such immune-regulatory activity are not well defined. It has previously been demonstrated that B. longum 35624 produces a cell surface exopolysaccharide (sEPS), and in this study, we investigated the role played by this exopolysaccharide in influencing the host immune response. B. longum 35624 induced relatively low levels of cytokine secretion from human dendritic cells, whereas an isogenic exopolysaccharide-negative mutant derivative (termed sEPSneg) induced vastly more cytokines, including interleukin-17 (IL-17), and this response was reversed when exopolysaccharide production was restored in sEPSneg by genetic complementation. Administration of B. longum 35624 to mice of the T cell transfer colitis model prevented disease symptoms, whereas sEPSneg did not protect against the development of colitis, with associated enhanced recruitment of IL-17+ lymphocytes to the gut. Moreover, intranasal administration of sEPSneg also resulted in enhanced recruitment of IL-17+ lymphocytes to the murine lung. These data demonstrate that the particular exopolysaccharide produced by B. longum 35624 plays an essential role in dampening proinflammatory host responses to the strain and that loss of exopolysaccharide production results in the induction of local TH17 responses. IMPORTANCE: Particular gut commensals, such as B. longum 35624, are known to contribute positively to the development of mucosal immune cells, resulting in protection from inflammatory diseases. However, the molecular basis and mechanisms for these commensal-host interactions are poorly described. In this report, an exopolysaccharide was shown to be decisive in influencing the immune response to the bacterium. We generated an isogenic mutant unable to produce exopolysaccharide and observed that this mutation caused a dramatic change in the response of human immune cells in vitro In addition, the use of mouse models confirmed that lack of exopolysaccharide production induces inflammatory responses to the bacterium. These results implicate the surface-associated exopolysaccharide of the B. longum 35624 cell envelope in the prevention of aberrant inflammatory responses.

Genome Analysis and Characterisation of the Exopolysaccharide Produced by Bifidobacterium longum subsp. longum 35624™.

The Bifibobacterium longum subsp. longum 35624™ strain (formerly named Bifidobacterium longum subsp. infantis) is a well described probiotic with clinical efficacy in Irritable Bowel Syndrome clinical trials and induces immunoregulatory effects in mice and in humans. This paper presents (a) the genome sequence of the organism allowing the assignment to its correct subspeciation longum; (b) a comparative genome assessment with other B. longum strains and (c) the molecular structure of the 35624 exopolysaccharide (EPS624). Comparative genome analysis of the 35624 strain with other B. longum strains determined that the sub-speciation of the strain is longum and revealed the presence of a 35624-specific gene cluster, predicted to encode the biosynthetic machinery for EPS624. Following isolation and acid treatment of the EPS, its chemical structure was determined using gas and liquid chromatography for sugar constituent and linkage analysis, electrospray and matrix assisted laser desorption ionization mass spectrometry for sequencing and NMR. The EPS consists of a branched hexasaccharide repeating unit containing two galactose and two glucose moieties, galacturonic acid and the unusual sugar 6-deoxy-L-talose. These data demonstrate that the B. longum 35624 strain has specific genetic features, one of which leads to the generation of a characteristic exopolysaccharide.

Histamine Receptor 2 is Required to Suppress Innate Immune Responses to Bacterial Ligands in Patients with Inflammatory Bowel Disease.

BACKGROUND: Histamine is a key immunoregulatory mediator in immediate-type hypersensitivity reactions and chronic inflammatory responses, in particular histamine suppresses proinflammatory responses to bacterial ligands, through histamine receptor 2 (H2R). The aim of this study was to investigate the effects of histamine and H2R on bacteria-induced inflammatory responses in patients with IBD. METHODS: Peripheral blood mononuclear cells (PBMCs) were obtained from patients with Crohn's disease, patients with ulcerative colitis, and healthy controls. PBMC histamine receptor expression was evaluated by flow cytometry. Cytokine secretion following Toll-like receptor (TLR)-2, TLR-4, TLR-5, or TLR-9 stimulation in the presence or absence of histamine or famotidine (H2R antagonist) was quantified. Biopsy histamine receptor gene expression was evaluated using reverse transcription-polymerase chain reaction. The in vivo role of H2R was evaluated in the T-cell transfer murine colitis model. RESULTS: The percentage of circulating H2R monocytes was significantly reduced in patients with IBD. Histamine effectively suppressed TLR-induced cytokine secretion from healthy volunteer PBMCs but not for PBMCs from patients with IBD. Famotidine reversed this suppressive effect. H1R, H2R, and H4R gene expression was increased in inflamed gastrointestinal mucosa compared with noninflamed mucosa from the same patient and expression levels correlated with proinflammatory cytokine gene expression. Mice receiving lymphocytes from H2R donors, or treated with famotidine, displayed more severe weight loss, higher disease scores and increased numbers of mucosal IFN-γ and IL-17 T cells. CONCLUSION: Patients with IBD display dysregulated expression of histamine receptors, with diminished anti-inflammatory effects associated with H2R signaling. Deliberate manipulation of H2R signaling may suppress excessive TLR responses to bacteria within the gut.

Human dendritic cell DC-SIGN and TLR-2 mediate complementary immune regulatory activities in response to Lactobacillus rhamnosus JB-1.

The microbiota is required for optimal host development and ongoing immune homeostasis. Lactobacilli are common inhabitants of the mammalian large intestine and immunoregulatory effects have been described for certain, but not all, strains. The mechanisms underpinning these protective effects are beginning to be elucidated. One such protective organism is Lactobacillus rhamnosus JB-1 (Lb. rhamnosus JB-1). Lb. murinus has no such anti-inflammatory protective effects and was used as a comparator organism. Human monocyte-derived dendritic cells (MDDCs) were co-incubated with bacteria and analysed over time for bacterial adhesion and intracellular processing, costimulatory molecule expression, cytokine secretion and induction of lymphocyte polarization. Neutralising antibodies were utilized to identify the responsible MDDC receptors. Lb. rhamnosus JB-1 adhered to MDDCs, but internalization and intracellular processing was significantly delayed, compared to Lb. murinus which was rapidly internalized and processed. Lb. murinus induced CD80 and CD86 expression, accompanied by high levels of cytokine secretion, while Lb. rhamnosus JB-1 was a poor inducer of costimulatory molecule expression and cytokine secretion. Lb. rhamnosus JB-1 primed MDDCs induced Foxp3 expression in autologous lymphocytes, while Lb. murinus primed MDDCs induced Foxp3, T-bet and Ror-γt expression. DC-SIGN was required for Lb. rhamnosus JB-1 adhesion and influenced IL-12 secretion, while TLR-2 influenced IL-10 and IL-12 secretion. Here we demonstrate that the delayed kinetics of bacterial processing by MDDCs correlates with MDDC activation and stimulation of lymphocytes. Thus, inhibition or delay of intracellular processing may be a novel strategy by which certain commensals may avoid the induction of proinflammatory responses.

Bifidobacterium infantis 35624 modulates host inflammatory processes beyond the gut.

Certain therapeutic microbes, including Bifidobacteria infantis (B. infantis) 35624 exert beneficial immunoregulatory effects by mimicking commensal-immune interactions; however, the value of these effects in patients with non-gastrointestinal inflammatory conditions remains unclear. In this study, we assessed the impact of oral administration of B. infantis 35624, for 6‒8 weeks on inflammatory biomarker and plasma cytokine levels in patients with ulcerative colitis (UC) (n = 22), chronic fatigue syndrome (CFS) (n = 48) and psoriasis (n = 26) in three separate randomized, double-blind, placebo-controlled interventions. Additionally, the effect of B. infantis 35624 on immunological biomarkers in healthy subjects (n = 22) was assessed. At baseline, both gastrointestinal (UC) and non-gastrointestinal (CFS and psoriasis) patients had significantly increased plasma levels of C-reactive protein (CRP) and the pro-inflammatory cytokines tumor necrosis factor α (TNF-α) and interleukin-6 (IL-6) compared with healthy volunteers. B. infantis 35624 feeding resulted in reduced plasma CRP levels in all three inflammatory disorders compared with placebo. Interestingly, plasma TNF-α was reduced in CFS and psoriasis while IL-6 was reduced in UC and CFS. Furthermore, in healthy subjects, LPS-stimulated TNF-α and IL-6 secretion by peripheral blood mononuclear cells (PBMCs) was significantly reduced in the B. infantis 35624-treated groups compared with placebo following eight weeks of feeding. These results demonstrate the ability of this microbe to reduce systemic pro-inflammatory biomarkers in both gastrointestinal and non-gastrointestinal conditions. In conclusion, these data show that the immunomodulatory effects of the microbiota in humans are not limited to the mucosal immune system but extend to the systemic immune system.

Bifidobacterium infantis 35624 administration induces Foxp3 T regulatory cells in human peripheral blood: potential role for myeloid and plasmacytoid dendritic cells.

BACKGROUND: Intestinal homoeostasis is dependent on immunological tolerance to the microbiota. OBJECTIVE: To (1) determine if a probiotic could induce Foxp3 T cells in humans; (2) to elucidate the molecular mechanisms, which are involved in the induction of Foxp3 T cells by human dendritic cells. DESIGN: Cytokine secretion and Foxp3 expression were assessed in human volunteers following Bifidobacterium infantis feeding. Monocyte-derived dendritic cells (MDDCs), myeloid dendritic cells (mDCs) and plasmacytoid dendritic cells (pDCs) were incubated in vitro with B. infantis and autologous lymphocytes. Transcription factor expression, costimulatory molecule expression, cytokine secretion, retinoic acid and tryptophan metabolism were analysed. RESULTS: Volunteers fed B. infantis displayed a selective increase in secretion of interleukin (IL)-10 and enhanced Foxp3 expression in peripheral blood. In vitro, MDDCs, mDCs and pDCs expressed indoleamine 2,3-dioxygenase and secreted IL-10, but not IL-12p70, in response to B. infantis. MDDC and mDC IL-10 secretion was Toll-like receptor (TLR)-2/6 dependent, while pDC IL-10 secretion was TLR-9 dependent. In addition, MDDCs and mDCs expressed RALDH2, which was TLR-2 and DC-SIGN dependent. B. infantis-stimulated MDDCs, mDCs and pDCs induced T cell Foxp3 expression. TLR-2, DC-SIGN and retinoic acid were required for MDDC and mDC induction of Foxp3 T cells, while pDCs required indoleamine 2,3-dioxygenase. CONCLUSIONS: B. infantis administration to humans selectively promotes immunoregulatory responses, suggesting that this microbe may have therapeutic utility in patients with inflammatory disease. Cross-talk between multiple pattern-recognition receptors and metabolic pathways determines the innate and subsequent T regulatory cell response to B. infantis. These findings link nutrition, microbiota and the induction of tolerance within the gastrointestinal mucosa.

Bifidobacterium animalis AHC7 protects against pathogen-induced NF-κB activation in vivo.

BACKGROUND: Bifidobacteria and lactobacilli are among the early and important colonizers of the gastrointestinal tract and are generally considered to be part of a normal, healthy microbiota. It is believed that specific strains within the microbiota can influence host immune-reactivity and may play a role in protection from infection and aberrant inflammatory activity. One such strain, Bifidobacterium animalis AHC7, has been previously shown to protect against Salmonella typhimurium infection in mice and helps resolve acute idiopathic diarrhea in dogs. The aim of this study was to investigate the potential molecular and cellular mechanisms underpinning the Bifidobacterium animalis AHC7 protective effect. RESULTS: Following 4 hours of infection with Salmonella typhimurium, NF-κB activation was significantly elevated in vivo in placebo and Enterococcus faecium-fed animals while Bifidobacterium animalis AHC7 consumption significantly attenuated the NF-κB response. In vitro anti-CD3/CD28 stimulated Peyer's patch cells secreted significantly less TNF-α and IFN-γ following Bifidobacterium animalis AHC7 consumption. Stimulated cells released more IL-12p70 but this difference did not reach statistical significance. No alteration in mucosal IL-6, IL-10 or MCP-1 levels were observed. No statistically significant change in the cytokine profile of mesenteric lymph node cells was noted. In vitro, Bifidobacterium animalis AHC7 was bound by dendritic cells and induced secretion of both IL-10 and IL-12p70. In addition, co-culture of CD4+ T cells with Bifidobacterium animalis AHC7-stimulated dendritic cells resulted in a significant increase in CD25+Foxp3+ T cell numbers. CONCLUSION: Bifidobacterium animalis AHC7 exerts an anti-inflammatory effect via the attenuation of pro-inflammatory transcription factor activation in response to an infectious insult associated with modulation of pro-inflammatory cytokine production within the mucosa. The cellular mechanism underpinning Bifidobacterium animalis AHC7 mediated attenuation of NF-κB activation may include recognition of the bacterium by dendritic cells and induction of CD25+Foxp3+ T cells.

Plasma cytokine profiles in females with irritable bowel syndrome and extra-intestinal co-morbidity.

OBJECTIVES: Irritable bowel syndrome (IBS) is a functional disorder that is associated with a number of extra-intestinal co-morbidities and a pro-inflammatory profile. This study was designed to examine the cytokine profile among a group of IBS patients with the extra-intestinal co-morbidities fibromyalgia, premenstrual dysmorphic disorder, and chronic fatigue syndrome. METHODS: In all, 100 female IBS patients with these co-morbidities, 21 IBS subjects without co-morbidity ("pure" IBS; Rome II), and 54 age-matched female controls took part in the study. Blood was drawn for measurement of the plasma cytokines interleukin (IL)-1ß, IL-6, IL-8, IL-10, IL-12p70, IL-13, tumor necrosis factor (TNF)α, and interferon γ. The presence of the selected extra-intestinal manifestations was assessed using standard international criteria. RESULTS: Patients with IBS have increased plasma levels of IL-6 and IL-8; those with these extra-intestinal co-morbidities were found to have, in addition, increased levels of IL-1ß and TNFα. No associations were evident between cytokine profiles and the nature of the co-morbidity or number of extra-intestinal co-morbidities present. CONCLUSIONS: Although IBS is characterized by a pro-inflammatory profile featuring the pro-inflammatory cytokines IL-6 and IL-8, IBS patients with certain extra-intestinal co-morbid conditions are distinguished by additional elevations in IL-1ß and TNFα.

Listeriolysin S, a novel peptide haemolysin associated with a subset of lineage I Listeria monocytogenes.

Streptolysin S (SLS) is a bacteriocin-like haemolytic and cytotoxic virulence factor that plays a key role in the virulence of Group A Streptococcus (GAS), the causative agent of pharyngitis, impetigo, necrotizing fasciitis and streptococcal toxic shock syndrome. Although it has long been thought that SLS and related peptides are produced by GAS and related streptococci only, there is evidence to suggest that a number of the most notorious Gram-positive pathogenic bacteria, including Listeria monocytogenes, Clostridium botulinum and Staphylococcus aureus, produce related peptides. The distribution of the L. monocytogenes cluster is particularly noteworthy in that it is found exclusively among a subset of lineage I strains; i.e., those responsible for the majority of outbreaks of listeriosis. Expression of these genes results in the production of a haemolytic and cytotoxic factor, designated Listeriolysin S, which contributes to virulence of the pathogen as assessed by murine- and human polymorphonuclear neutrophil-based studies. Thus, in the process of establishing the existence of an extended family of SLS-like modified virulence peptides (MVPs), the genetic basis for the enhanced virulence of a proportion of lineage I L. monocytogenes may have been revealed.