A strain of Lactobacillus casei inhibits the effector phase of immune inflammation

Microbial Imbalance and Intestinal Permeability in the Pathogenesis of Rheumatoid Arthritis: A Mechanism Review with a Focus on Bacterial Translocation, Citrullination, and Probiotic Intervention

This review aims to investigate the role of intestinal permeability (IP) in rheumatoid arthritis (RA), following the hypotheses that leakage of intestinal microbes can influence increased citrullination of peptides leading to anti-citrullinated protein antibody (ACPA) production and inflammation in RA; and that leaked microbes can migrate to the peripheral joints, leading to immune responses and synovitis in peripheral joints. This review explored the evidence for the link between microbial dysbiosis and increased IP in the inflammatory state in RA, as well as the role of increased citrullination and bacterial translocation in the link between microbiota and immune responses in RA. Furthermore, this research aims to evaluate the potential effect of probiotics on RA symptoms and pathogenesis via proposed mechanisms, including the support of microbial balance and suppression of inflammatory factors in RA. A systematic literature search was conducted in three tranches (review, mechanism, intervention). 71 peer-reviewed papers met the inclusions criteria and are summarized in a narrative analysis. Primary studies were critically appraised, synthesized and their relevance to clinical practice evaluated. Evidence found in this mechanism review consistently supported intestinal dysbiosis and increased IP in arthritis. An altered intestinal microbiome was demonstrated in RA with specific microbes such as Collinsella and Eggerthella correlating with increased IP, mucosal inflammation, and immune responses. Hypercitrullination and ACPA production correlated with arthritic symptoms and intestinal microbes were shown to influence hypercitrullination. Some in vitro and animal studies demonstrated a link between leakage of microbes and bacterial translocation, but further research is needed to elucidate the link between IP and citrullination. Probiotic intervention studies evidenced reductions in inflammatory markers IL-6 and TNFα, associated with proliferation of synovial tissue and pain perception in RA joint inflammation. Despite some conflict in the literature, probiotics may present a promising nutritional intervention in the suppression of both, disease activity and inflammatory markers.Key teaching pointsThere is evidence for a dysbiotic profile of the RA gut with specific RA-associated microbes.Increased intestinal permeability and leakage of PAD enzyme facilitates citrullination of peptides.Hypercitrullination and ACPA production correlate to arthritic signs.Microbial leakage and translocation plays a role in the pathogenesis of RA.Probiotics (e.g. L. Casei 01) may reduce inflammation and ameliorate RA symptoms.

Emerging Role of the Mast Cell-Microbiota Crosstalk in Cutaneous Homeostasis and Immunity

The skin presents a multifaceted microbiome, a balanced coexistence of bacteria, fungi, and viruses. These resident microorganisms are fundamental in upholding skin health by both countering detrimental pathogens and working in tandem with the skin's immunity. Disruptions in this balance, known as dysbiosis, can lead to disorders like psoriasis and atopic dermatitis. Central to the skin's defense system are mast cells. These are strategically positioned within the skin layers, primed for rapid response to any potential foreign threats. Recent investigations have started to unravel the complex interplay between these mast cells and the diverse entities within the skin's microbiome. This relationship, especially during times of both balance and imbalance, is proving to be more integral to skin health than previously recognized. In this review, we illuminate the latest findings on the ties between mast cells and commensal skin microorganisms, shedding light on their combined effects on skin health and maladies.

Gut microbiota in SLE: from animal models to clinical evidence and pharmacological perspectives

Systemic lupus erythematosus (SLE) is a multifactorial autoimmune disease driven by complex interactions between genetics and environmental factors. SLE is characterised by breaking self-immune tolerance and autoantibody production that triggers inflammation and damage of multiple organs. Given the highly heterogeneous nature of SLE, the treatments currently used are still not satisfactory with considerable side effects, and the development of new therapies is a major health issue for better patient management. In this context, mouse models significantly contribute to our knowledge of the pathogenesis of SLE and are an invaluable tool for testing novel therapeutic targets. Here, we discuss the role of the most used SLE mouse models and their contribution to therapeutic improvement. Considering the complexity of developing targeted therapies for SLE, adjuvant therapies are also increasingly proposed. Indeed, murine and human studies have recently revealed that gut microbiota is a potential target and holds great promises for successful new SLE therapies. However, the mechanisms of gut microbiota dysbiosis in SLE remain unclear to date. In this review, we propose an inventory of existing studies investigating the relationship between gut microbiota dysbiosis and SLE to establish microbiome signature that may serve as a potential biomarker of the disease and its severity as well as a new potential therapy target. This approach may open new possibilities for early diagnosis, prevention and therapeutic perspectives of SLE based on gut microbiome.

Systematic evaluation of genome-wide metabolic landscapes in lactic acid bacteria reveals diet- and strain-specific probiotic idiosyncrasies

Lactic acid bacteria (LAB) are well known to elicit health benefits in humans, but their functional metabolic landscapes remain unexplored. Here, we analyze differences in growth, intestinal persistence, and postbiotic biosynthesis of six representative LAB and their interactions with 15 gut bacteria under 11 dietary regimes by combining multi-omics and in silico modeling. We confirmed predictions on short-term persistence of LAB and their interactions with commensals using cecal microbiome abundance and spent-medium experiments. Our analyses indicate that probiotic attributes are both diet and species specific and cannot be solely explained using genomics. For example, although both Lacticaseibacillus casei and Lactiplantibacillus plantarum encode similarly sized genomes with diverse capabilities, L. casei exhibits a more desirable phenotype. In addition, "high-fat/low-carb" diets more likely lead to detrimental outcomes for most LAB. Collectively, our results highlight that probiotics are not "one size fits all" health supplements and lay the foundation for personalized probiotic design.

The Microbiota in Systemic Lupus Erythematosus: An Update on the Potential Function of Probiotics

Systemic lupus erythematosus (SLE) is a kind of chronic diffuse connective tissue illness characterized by multisystem and multiorgan involvement, repeated recurrence and remission, and the presence of a large pool of autoantibodies in the body. Although the exact cause of SLE is not thoroughly revealed, accumulating evidence has manifested that intake of probiotics alters the composition of the gut microbiome, regulating the immunomodulatory and inflammatory response, which may be linked to the disease pathogenesis. Particularly, documented experiments demonstrated that SLE patients have remarkable changes in gut microbiota compared to healthy controls, indicating that the alteration of microbiota may be implicated in different phases of SLE. In this review, the alteration of microbiota in the development of SLE is summarized, and the mechanism of intestinal microbiota on the progression of immune and inflammatory responses in SLE is also discussed. Due to limited reports on the effects of probiotics supplementation in SLE patients, we emphasize advancements made in the last few years on the function and mechanisms of probiotics in the development of SLE animal models. Besides, we follow through literature to survey whether probiotics supplements can be an adjuvant therapy for comprehensive treatment of SLE. Research has indicated that intake of probiotics alters the composition of the gut microbiome, contributing to prevent the progression of SLE. Adjustment of the gut microbiome through probiotics supplementation seems to alleviate SLE symptoms and their cardiovascular and renal complications in animal models, marking this treatment as a potentially novel approach.

Immunoregulatory Effects of Tolerogenic Probiotics in Multiple Sclerosis

Gut microbiota has essential roles in the prevention and progression of multiple sclerosis (MS). The association between the gut microbiota and the central nervous system (CNS) or immune system response of MS patients has been documented in many studies. The composition of the gut microbiota could lead to sensitization or resistance against promotion and development of MS disease. Probiotics are the major part of gut microflorapopulation and could be substituted with tolerogenic probiotics that protect the CNS against autoimmune responses. Tolerogenic probiotics with anti-inflammatory and immuno-modulatory properties have effects on intestinal flora and can reestablish regulatory mucosal and systemic immune responses. Probiotics are able to prevent and restore excessive activation of inflammatory responses, especially autoreactive T cells and inflammatory cytokines. Tolerogenic probiotics, through induction of regulatory T cells and increase of anti-inflammatory cytokines, play a crucial role in controlling inflammation and maintaining tolerance and hemostasis. Therefore, probiotics can be considered as a preventive or therapeutic tool in MS. In the present review, we focus on the immunoregulatory effects of tolerogenic probiotics on the severity of disease, as well as Th1, Th2, and Treg populations in different experimental and human studies of MS.

Protective Effects of Probiotic Consumption in Cardiovascular Disease in Systemic Lupus Erythematosus

The prevalence of renal and cardiovascular disease (CVD) in patients with systemic lupus erythematosus (SLE) is higher than in general populations. Recently, a causal role of gut microbiota on the development of immune responses in SLE has been described. Probiotic consumption changes the composition of gut microbiota, preventing SLE progression. The aim of this review is to explore the role of the gut microbiota in the development of renal and cardiovascular disease in SLE and how probiotics could be a therapeutic option. Despite strong evidence on the beneficial effects of probiotics in the development of autoimmunity and nephritis in SLE, only a few studies described the protective effects of Lactobacillus in important risk factors for CVD, such as endothelial dysfunction and hypertension in mice. The preventive effects of probiotics in renal and CVD in humans have not been established yet.

Adjunctive probiotic microorganisms to prevent rehospitalization in patients with acute mania: A randomized controlled trial

OBJECTIVE

Immunological abnormalities play a role in the pathophysiology of mania and have been associated with relapse. Probiotic organisms such as Lactobacilli and Bifidobacteria modulate inflammation in humans and animal models. The trial examined whether the administration of probiotic organisms prevents psychiatric rehospitalizations in patients recently discharged following hospitalization for mania.

METHODS

Patients hospitalized for mania (N = 66) were randomized after discharge to receive 24 weeks of adjunctive probiotics (Lactobacillus rhamnosus strain GG and Bifidobacterium animalis subsp. lactis strain Bb12) or adjunctive placebo in a parallel two-group design format. The effect of treatment group on the risk of rehospitalization was calculated using Cox regression models. The modulating effect of systemic inflammation was measured employing an inflammation score based on immunoglobulin levels directed at previously defined antigens.

RESULTS

During the 24-week observation period there were a total of 24 rehospitalizations in the 33 individuals who received placebo and eight rehospitalizations in the 33 individuals who received the probiotics (z = 2.63, P = .009). Hazard functions indicated that the administration of the probiotics was associated with a significant advantage in time to all psychiatric rehospitalizations (hazard ratio [HR] = 0.26, 95% confidence interval [CI] 0.10, .69; P = .007). Probiotic treatment also resulted in fewer days rehospitalized (mean 8.3 vs 2.8 days for placebo and probiotic treatment, respectively; χ²  = 5.17, P = .017). The effect of the probiotic treatment on the prevention of rehospitalization was increased in individuals with elevated levels of systemic inflammation at baseline.

CONCLUSION

Probiotic supplementation is associated with a lower rate of rehospitalization in patients who have been recently discharged following hospitalization for mania.

Basophils from allergic patients are neither hyperresponsive to activation signals nor hyporesponsive to inhibition signals

BACKGROUND

Basophil activation contributes to inflammatory reactions, especially in allergy. It is controlled, both positively and negatively, by several mechanisms. High-affinity IgE receptors (FcεRI) generate a mixture of activation and inhibition signals when aggregated, the ratio of which depends on the concentration of allergen recognized by receptor-bound IgE. Low-affinity IgG receptors (FcγRIIA/B) generate inhibition signals when coengaged with FcεRI by allergen-antibody immune complexes. Commensal and probiotic bacteria, such as Lactobacillus paracasei, generate inhibition signals through still unclear mechanisms.

OBJECTIVE

We sought to investigate whether mechanisms that control, both positively and negatively, basophil activation, which were unraveled and studied in basophils from healthy donors, are functional in allergic patients.

METHODS

FcεRI and FcγRIIA/B expression, FcεRI-dependent activation, FcεRI-dependent inhibition, and FcγRIIB-dependent inhibition were examined in blood basophils incubated overnight with or without L paracasei and challenged under 10 experimental conditions. Basophils from healthy donors were compared with basophils from patients who consulted an allergology outpatient clinic over a period of 3 months with respiratory allergy, anaphylaxis antecedents, chronic urticaria, and/or atopic dermatitis.

RESULTS

Patients' basophils expressed neither more FcεRI nor less FcγRIIB than basophils from healthy donors. They were neither hyperreactive to positive regulation nor hyporeactive to negative regulation, irrespective of the receptors or mechanisms involved and the allergic manifestations of the patients.

CONCLUSION

Regulatory mechanisms that control basophil activation are fully functional in allergic patients. Intrinsic defects in these mechanisms do not explain allergic manifestations. Based on these mechanisms, immune checkpoint modifiers can be developed as novel therapeutic tools for allergy.

Effects of oral Lactobacillus administration on antioxidant activities and CD4+CD25+forkhead box P3 (FoxP3)+ T cells in NZB/W F1 mice

Systemic lupus erythematosus (SLE) is an autoimmune disease that is characterised by a dysregulation of the immune system, which causes inflammation responses, excessive oxidative stress and a reduction in the number of cluster of differentiation (CD)4+CD25+forkhead box P3 (FoxP3)+ T cells. Supplementation with certain Lactobacillus strains has been suggested to be beneficial in the comprehensive treatment of SLE. However, little is known about the effect and mechanism of certain Lactobacillus strains on SLE. To investigate the effects of Lactobacillus on SLE, NZB/W F1 mice were orally gavaged with Lactobacillus paracasei GMNL-32 (GMNL-32), Lactobacillus reuteri GMNL-89 (GMNL-89) and L. reuteri GMNL-263 (GMNL-263). Supplementation with GMNL-32, GMNL-89 and GMNL-263 significantly increased antioxidant activity, reduced IL-6 and TNF-α levels and significantly decreased the toll-like receptors/myeloid differentiation primary response gene 88 signalling in NZB/W F1 mice. Notably, supplementation with GMNL-263, but not GMNL-32 and GMNL-89, in NZB/W F1 mice significantly increased the differentiation of CD4+CD25+FoxP3+ T cells. These findings reveal beneficial effects of GMNL-32, GMNL-89 and GMNL-263 on NZB/W F1 mice and suggest that these specific Lactobacillus strains can be used as part of a comprehensive treatment of SLE patients.

Individual strains of Lactobacillus paracasei differentially inhibit human basophil and mouse mast cell activation

INTRODUCTION

The microbiota controls a variety of biological functions, including immunity, and alterations of the microbiota in early life are associated with a higher risk of developing allergies later in life. Several probiotic bacteria, and particularly lactic acid bacteria, were described to reduce both the induction of allergic responses and allergic manifestations. Although specific probiotic strains were used in these studies, their protective effects on allergic responses also might be common for all lactobacilli.

METHODS

To determine whether allergic effector cells inhibition is a common feature of lactobacilli or whether it varies among lactobacilli strains, we compared the ability of 40 strains of the same Lactobacillus paracasei species to inhibit IgE-dependent mouse mast cell and human basophil activation.

RESULTS

We uncovered a marked heterogeneity in the inhibitory properties of the 40 Lactobacillus strains tested. These segregated into three to four clusters depending on the intensity of inhibition. Some strains inhibited both mouse mast cell and human basophil activation, others strains inhibited only one cell type and another group induced no inhibition of activation for either cell type.

CONCLUSIONS

Individual Lactobacillus strains of the same species differentially inhibit IgE-dependent activation of mouse mast cells and human basophils, two cell types that are critical in the onset of allergic manifestations. Although we failed to identify specific bacterial genes associated with inhibition by gene-trait matching analysis, our findings demonstrate the complexity of the interactions between the microbiota and the host. These results suggest that some L. paracasei strains might be more beneficial in allergies than others strains and provide the bases for a rational screening of lactic acid bacteria strains as next-generation probiotics in the field of allergy.

Establishment of a Mouse Anti-ovalbumin IgE Monoclonal Antibody That Induces FcɛRII (CD23)-dependent Activation Without FcɛRI-Dependent Activation

IgE mainly activates cells via two receptors, FcɛRI and FcɛRII. Blocking antibodies against and animals genetically targeted for these receptors have been successfully used to distinguish between these two activating pathways. In the present study, we investigated whether our newly established anti-ovalbumin (OVA) monoclonal IgE OE-2 induced FcɛRII-dependent activation, but not FcɛRI-dependent activation in vivo and in vitro, in contrast to the previously established anti-OVA IgE OE-1, which stimulated FcɛRI and FcɛRII. The FcɛRI-mediated degranulation of RBL2H3 cells and passive systemic anaphylaxis in mice were induced by OE-1 but not OE-2. On the other hand, the production of nitric oxide by rat peritoneal macrophages and the primary antibody response in mice against co-injected OVA, which were mediated through FcɛRII, were induced and enhanced by OE-1 and OE-2. Differences in the epitopes recognized by OE-1 and OE-2 may partially explain why OE-1, but not OE-2, triggered FcɛRI-dependent activation. OE-1 bridged FcɛRI through effective aggregation with OVA, whereas OE-2 crosslinked the receptor strongly and only moderately upon the addition of an anti-kappa antibody and polymerized OVA, namely, an OVA-conjugated resin, respectively, resulting in degranulation. Our results offer a novel approach for determining the relative importance of FcɛRI and FcɛRII in various IgE-dependent responses by using OE-1 and OE-2.

Attenuation of food allergy symptoms following treatment with human milk oligosaccharides in a mouse model

BACKGROUND

The prebiotic nature of human milk oligosaccharides (HMOs) and increasing evidence of direct immunomodulatory effects of these sugars suggest that they may have some therapeutic potential in allergy. Here, we assess the effect of two HMOs, 2'-fucosyllactose and 6'-sialyllactose, on symptomatology and immune responses in an ovalbumin-sensitized mouse model of food allergy.

METHODS

The effects of oral treatment with 2'-fucosyllactose and 6'-sialyllactose on anaphylactic symptoms induced by oral ovalbumin (OVA) challenge in sensitized mice were investigated. Mast cell functions in response to oral HMO treatment were also measured in the passive cutaneous anaphylaxis model, and direct effects on IgE-mediated degranulation of mast cells were assessed.

RESULTS

Daily oral treatment with 2'-fucosyllactose or 6'-sialyllactose attenuated food allergy symptoms including diarrhea and hypothermia. Treatment with HMOs also suppressed antigen-induced increases in mouse mast cell protease-1 in serum and mast cell numbers in the intestine. These effects were associated with increases in the CD4(+) CD25(+) IL-10(+) cell populations in the Peyer's patches and mesenteric lymph nodes, while 6'-sialyllactose also induced increased IL-10 and decreased TNF production in antigen-stimulated splenocytes. Both 2'-fucosyllactose and 6'-sialyllactose reduced the passive cutaneous anaphylaxis response, but only 6'-sialyllactose directly inhibited mast cell degranulation in vitro, at high concentrations.

CONCLUSIONS

Our results suggest that 2'-fucosyllactose and 6'-sialyllactose reduce the symptoms of food allergy through induction of IL-10(+) T regulatory cells and indirect stabilization of mast cells. Thus, human milk oligosaccharides may have therapeutic potential in allergic disease.

Attenuation of Colitis by Lactobacillus casei BL23 Is Dependent on the Dairy Delivery Matrix

The role of the food delivery matrix in probiotic performance in the intestine is not well understood. Because probiotics are often provided to consumers in dairy products, we investigated the contributions of milk to the health-benefiting performance of Lactobacillus casei BL23 in a dextran sulfate sodium (DSS)-induced murine model of ulcerative colitis. L. casei BL23 protected against the development of colitis when ingested in milk but not in a nutrient-free buffer simulating consumption as a nutritional supplement. Consumption of (acidified) milk alone also provided some protection against weight loss and intestinal inflammation but was not as effective as L. casei and milk in combination. In contrast, L. casei mutants deficient in DltD (lipoteichoic acid d-alanine transfer protein) or RecA (recombinase A) were unable to protect against DSS-induced colitis, even when consumed in the presence of milk. Mice fed either L. casei or milk contained reduced quantities of colonic proinflammatory cytokines, indicating that the L. casei DltD(-) and RecA(-) mutants as well as L. casei BL23 in nutrient-free buffer were effective at modulating immune responses. However, there was not a direct correlation between colitis and quantities of these cytokines at the time of sacrifice. Identification of the cecal microbiota by 16S rRNA gene sequencing showed that L. casei in milk enriched for Comamonadaceae and Bifidobacteriaceae; however, the consumption of neither L. casei nor milk resulted in the restoration of the microbiota to resemble that of healthy animals. These findings strongly indicate that probiotic strain efficacy can be influenced by the food/supplement delivery matrix.

Microbes taming mast cells: Implications for allergic inflammation and beyond

There is increasing awareness of a relationship between our microbiota and the pathogenesis of allergy and other inflammatory diseases. In investigating the mechanisms underlying microbiota modulation of allergy the focus has been on the induction phase; alterations in the phenotype and function of antigen presenting cells, induction of regulatory T cells and shifts in Th1/Th2 balance. However there is evidence that microbes can influence the effector phase of disease, specifically that certain potentially beneficial bacteria can attenuate mast cell activation and degranulation. Furthermore, it appears that different non-pathogenic bacteria can utilize distinct mechanisms to stabilize mast cells, acting locally though direct interaction with the mast cell at mucosal sites or attenuating systemic mast cell dependent responses, likely through indirect signaling mechanisms. The position of mast cells on the frontline of defense against pathogens also suggests they may play an important role in fostering the host-microbiota relationship. Mast cells are also conduits of neuro-immuo-endocrine communication, suggesting the ability of microbes to modulate cell responses may have implications for host physiology beyond immunology. Further investigation of mast cell regulation by non-pathogenic or symbiotic bacteria will likely lead to a greater understanding of host microbiota interaction and the role of the microbiome in health and disease.

Study on reducing antigenic response and IgE-binding inhibitions of four milk proteins of Lactobacillus casei 1134

BACKGROUND

Cow's milk allergy has aroused public concern. The aim of this study was to investigate the effects of fermentation by Lactobacillus casei 1134 on the antigenicity and allergenicity (IgE-binding inhibitions) of milk proteins. The effects of pH value on the antigenicity and allergenicity of four milk proteins (α-lactalbumin, β-lactoglobulin, α-casein and β-casein) were examined by indirect competitive enzyme-linked immunosorbent assay. The free amino acids which were produced in the fermentation process were analysed and the proteolysis of milk proteins was detected.

RESULTS

Fermentation by L. casei 1134 could significantly reduce the antigenicity and allergenicity of the four proteins in reconstituted milk. The allergenicity of milk proteins was further reduced in the process of simulated gastrointestinal digestion. Moreover, we could deduce that one of the potential factors of antigenicity was lactic acid with the comparison of the antigenicity of the four proteins between L. casei 1134 fermented milk and lactic acid milk at different pH values.

CONCLUSION

There are many factors which can affect the milk proteins allergen, including lactic acid and proteolytic enzymes.

Mast Cells in Lung Homeostasis: Beyond Type I Hypersensitivity

Lungs are indispensable organs for the respiratory process, and maintaining their homeostasis is essential for human health and survival. However, during the lifetime of an individual, the lungs suffer countless insults that put at risk their delicate organization and function. Many cells of the immune system participate to maintain this equilibrium and to keep functional lungs. Among these cells, mast cells have recently attracted attention because of their ability to rapidly secrete many chemical and biological mediators that modulate different processes like inflammation, angiogenesis, cell proliferation, etc. In this review, we focus on recent advances in the understanding of the role that mast cells play in lung protection during infections, and of the relation of mast cell responses to type I hypersensitivity-associated pathologies. Furthermore, we discuss the potential role of mast cells during wound healing in the lung and its association with lung cancer, and how mast cells could be exploited as therapeutic targets in some diseases

Escherichia coli exposure inhibits exocytic SNARE-mediated membrane fusion in mast cells

Mast cells orchestrate the allergic response through the release of proinflammatory mediators, which is driven by the fusion of cytoplasmic secretory granules with the plasma membrane. During this process, SNARE proteins including Syntaxin4, SNAP23 and VAMP8 play a key role. Following stimulation, the kinase IKKβ interacts with and phosphorylates the t-SNARE SNAP23. Phosphorylated SNAP23 then associates with Syntaxin4 and the v-SNARE VAMP8 to form a ternary SNARE complex, which drives membrane fusion and mediator release. Interestingly, mast cell degranulation is impaired following exposure to bacteria such as Escherichia coli. However, the molecular mechanism(s) by which this occurs is unknown. Here, we show that E. coli exposure rapidly and additively inhibits degranulation in the RBL-2H3 rat mast cell line. Following co-culture with E. coli, the interaction between IKKβ and SNAP23 is disrupted, resulting in the hypophosphorylation of SNAP23. Subsequent formation of the ternary SNARE complex between SNAP23, Syntaxin4 and VAMP8 is strongly reduced. Collectively, these results demonstrate that E. coli exposure inhibits the formation of VAMP8-containing exocytic SNARE complexes and thus the release of VAMP8-dependent granules by interfering with SNAP23 phosphorylation.

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.

Anaphylactic reaction to probiotics. Cow's milk and hen's egg allergens in probiotic compounds

BACKGROUND

Probiotics are used in the treatment of allergic diseases. We investigated the safety of probiotics for subjects with food allergy.

MATERIAL AND METHODS

Labels of probiotics commercially available in Spain were examined to assess their content of cow's milk or hen's egg. Skin prick tests with these compounds (20 mg/ml) were performed in five children allergic to cow's milk, five children allergic to hen's white egg, and five control subjects non-allergic to food. Three serum pools: I (positive-specific IgE to cow's milk and hen's egg white proteins), II (positive-specific IgE to cow's milk and negative to hen's egg white proteins), and III (negative-specific IgE to cow's milk and positive to hen's egg white proteins) were used to detect cow's milk and hen's egg white allergens in probiotics. ImmunoCAP(®) (Phadia), in-house ELISA, SDS-PAGE immunoblotting, and inhibition studies of these assays were performed. Proteins were quantified by enzyme-immunoassay.

RESULTS

Eleven probiotics were studied. No label advertised about egg content, eight labels warned about lactose, lactic acid or cow's milk, one label claimed to be milk-free, and two gave no information. Cow's milk proteins were detected, by at least one lab technique, in 10/11 probiotics, three over 2.5 mg/kg (21, 52, 112 mg/kg). Hen's egg white proteins were detected in 3/11 probiotics, only one had more than 2.5 mg/kg (47 mg/kg).

CONCLUSION

Probiotic compounds may contain hidden allergens of food and may not be safe for subjects with allergy to cow's milk or hen's egg.

Systemic effects of ingested Lactobacillus rhamnosus: inhibition of mast cell membrane potassium (IKCa) current and degranulation

Exposure of the intestine to certain strains lactobacillus can have systemic immune effects that include the attenuation of allergic responses. Despite the central role of mast cells in allergic disease little is known about the effect of lactobacilli on the function of these cells. To address this we assessed changes in rat mast cell activation following oral treatment with a strain of Lactobacillus known to attenuate allergic responses in animal models. Sprague Dawley rats were fed with L. rhamnosus JB-1 (1×10(9)) or vehicle control for 9 days. Mediator release from peritoneal mast cells (RPMC) was determined in response to a range of stimuli. Passive cutaneous anaphylaxis (PCA) was used to assess mast cell responses in vivo. The Ca(2+) activated K(+) channel (KCa3.1) current, identified as critical to mast cell degranulation, was monitored by whole cell patch-clamp. L. rhamnosus JB-1 treatment lead to significant inhibition of mast cell mediator release in response to a range of stimuli including IgE mediated activation. Furthermore, the PCA response was significantly reduced in treated rats. Patch-clamp studies revealed that RPMC from treated animals were much less responsive to the KCa3.1 opener, DCEBIO. These studies demonstrate that Ingestion of L. rhamnosus JB-1 leads to mast cell stabilization in rats and identify KCa3.1 as an immunomodulatory target for certain lactobacilli. Thus the systemic effects of certain candidate probiotics may include mast cell stabilization and such actions could contribute to the beneficial effect of these organisms in allergic and other inflammatory disorders.

Effects of probiotics on the prevention of atopic dermatitis

Atopic dermatitis (AD) is an immune disorder that is becoming increasingly prevalent throughout the world. The exact etiology of AD remains unknown, and a cure for AD is not currently available. The hypothesis that appropriate early microbial stimulation contributes to the establishment of a balanced immune system in terms of T helper type Th1, Th2, and regulatory T cell (Treg) responses has led to the use of probiotics for the prevention and treatment of AD in light of various human clinical studies and animal experiments. Meta-analysis data suggests that probiotics can alleviate the symptoms of AD in infants. The effects of balancing Th1/Th2 immunity and enhancing Treg activity via the interaction of probiotics with dendritic cells have been described in vitro and in animal models, although such an effect has not been demonstrated in human studies. In this review, we present some highlights of the immunomodulatory effects of probiotics in humans and animal studies with regard to their effects on the prevention of AD.

Unbalance of intestinal microbiota in atopic children

Background

Playing a strategic role in the host immune function, the intestinal microbiota has been recently hypothesized to be involved in the etiology of atopy. In order to investigate the gastrointestinal microbial ecology of atopic disease, here we performed a pilot comparative molecular analysis of the faecal microbiota in atopic children and healthy controls.

Results

Nineteen atopic children and 12 healthy controls aged 4–14 years were enrolled. Stools were collected and the faecal microbiota was characterized by means of the already developed phylogenetic microarray platform, HTF-Microbi.Array, and quantitative PCR. The intestinal microbiota of atopic children showed a significant depletion in members of the Clostridium cluster IV, Faecalibacterium prausnitzii, Akkermansia muciniphila and a corresponding increase of the relative abundance of Enterobacteriaceae.

Conclusion

Depleted in key immunomodulatory symbionts, the atopy-associated microbiota can represent an inflammogenic microbial consortium which can contribute to the severity of the disease. Our data open the way to the therapeutic manipulation of the intestinal microbiota in the treatment of atopy by means of pharmaceutical probiotics.

The impact of bacterial infection on mast cell degranulation

In developed countries, the prevalence of allergy is on the rise. Although the causes are unknown, it seems that (1) the disappearance of microbiota may play a role in the increase of allergies and (2) exposure to bacterial infections during childhood decreases the incidence of allergies. Although several cell types are involved in the development of allergy, mast cells play a major role in orchestrating inflammation. Upon activation, mast cell secretory granules fuse with the plasma membrane, resulting in the release of a number of inflammatory mediators. In addition to allergy, mast cells contribute to the innate immune response against a variety of bacteria. This is accomplished through the secretion of cytokines and other soluble mediators. Interestingly, there is growing evidence that mast cells exposed to bacteria down-regulate degranulation in response to IgE/Allergen stimulation. This inhibitory effect seems to require direct contact between bacteria and mast cells, but the intracellular mechanism by which bacterial contact suppresses allergic responses is unknown. Here, we review different aspects of mast cell physiology and discuss hypotheses as to how bacteria may influence mast cell degranulation.

Recent insights into microbial triggers of interleukin-10 production in the host and the impact on infectious disease pathogenesis

Since its initial description as a Th2-cytokine antagonistic to interferon-alpha and granulocyte-macrophage colony-stimulating factor, many studies have shown various anti-inflammatory actions of interleukin-10 (IL-10), and its role in infection as a key regulator of innate immunity. Studies have shown that IL-10 induced in response to microorganisms and their products plays a central role in shaping pathogenesis. IL-10 appears to function as both sword and shield in the response to varied groups of microorganisms in its capacity to mediate protective immunity against some organisms but increase susceptibility to other infections. The nature of IL-10 as a pleiotropic modulator of host responses to microorganisms is explained, in part, by its potent and varied effects on different immune effector cells which influence antimicrobial activity. A new understanding of how microorganisms trigger IL-10 responses is emerging, along with recent discoveries of how IL-10 produced during disease might be harnessed for better protective or therapeutic strategies. In this review, we summarize studies from the past 5 years that have reported the induction of IL-10 by different classes of pathogenic microorganisms, including protozoa, nematodes, fungi, viruses and bacteria and discuss the impact of this induction on the persistence and/or clearance of microorganisms in the host.