Effect of probiotic bacteria on induction and maintenance of oral tolerance to beta-lactoglobulin in gnotobiotic mice

Enhancement of Oral Tolerance Induction in DO11.10 Mice by Lactobacillus gasseri OLL2809 via Increase of Effector Regulatory T Cells

Food allergy is a serious problem for infants and young children. Induction of antigen-specific oral tolerance is one therapeutic strategy. Enhancement of oral tolerance induction by diet is a promising strategy to prevent food allergy in infants. Thus, in this study, we evaluate the effect of probiotic Lactobacillus gasseri OLL2809 (LG2809) on oral tolerance induction in a mouse model. The degree of oral tolerance induction was evaluated by measuring the proliferation and level of IL-2 production of splenic CD4⁺ T cells from DO11.10 mice fed ovalbumin (OVA) alone or OVA with LG2809. Oral administration of LG2809 significantly decreased the rate of proliferation and IL-2 production by CD4⁺ T cells from OVA-fed mice. LG2809 increased a ratio of CD4⁺ T-cell population, producing high levels of IL-10 and having strong suppressive activity. Moreover, LG2809 increased a ratio of plasmacytoid dendritic cells (pDCs) among the lamina propria (LP) in small intestine. When used as antigen presenting cells to naïve CD4⁺ T cells from DO11.10 mice, LP cells from BALB/c mice fed LG2809 induced higher IL-10 production and stronger suppressive activity than those from non-treated mice. These results suggest that oral administration of LG2809 increases the population of pDCs in the LP, resulting in the enhancement of oral tolerance induction by increasing the ratio of effector regulatory T cells. LG2809 could, therefore, act as a potent immunomodulator to prevent food allergies by promoting oral tolerance.

Induction of regulatory T cells: A role for probiotics and prebiotics to suppress autoimmunity

Regulatory T cells (Tregs) are comprised of a heterogeneous population of cells that play a vital role in suppressing inflammation and maintaining immune tolerance. Given the crucial role of Tregs in maintaining immune homeostasis, it is probably not surprising that many microbial species and their metabolites have the potential to induce Tregs. There is now great interest in the therapeutic potential of probiotics and prebiotics based strategies for a range of autoimmune disorders. This review will summarise recent findings concerning the role of probiotics and prebiotics in induction of Tregs to ameliorate the autoimmune conditions. In addition, the article is focused to explain the different mechanisms of Treg induction and function by these probiotics and prebiotics, based on the available studies till date. The article further proposes that induction of Tregs by probiotics and prebiotics could lead to the development of new therapeutic approach towards curbing the autoimmune response and as an alternative to detrimental immunosuppressive drugs.

A retrospective chart review to identify perinatal factors associated with food allergies

Background

Gut flora are important immunomodulators that may be disrupted in individuals with atopic conditions. Probiotic bacteria have been suggested as therapeutic modalities to mitigate or prevent food allergic manifestations. We wished to investigate whether perinatal factors known to disrupt gut flora increase the risk of IgE-mediated food allergies.

Methods

Birth records obtained from 192 healthy children and 99 children diagnosed with food allergies were reviewed retrospectively. Data pertaining to delivery method, perinatal antibiotic exposure, neonatal nursery environment, and maternal variables were recorded. Logistic regression analysis was used to assess the association between variables of interest and subsequent food allergy diagnosis.

Results

Retrospective investigation did not find perinatal antibiotics, NICU admission, or cesarean section to be associated with increased risk of food allergy diagnosis. However, associations between food allergy diagnosis and male gender (66 vs. 33; p=0.02) were apparent in this cohort. Additionally, increasing maternal age at delivery was significantly associated with food allergy diagnosis during childhood (OR, 1.05; 95% CI, 1.017 to 1.105; p=0.005).

Conclusions

Gut flora are potent immunomodulators, but their overall contribution to immune maturation remains to be elucidated. Additional understanding of the interplay between immunologic, genetic, and environmental factors underlying food allergy development need to be clarified before probiotic therapeutic interventions can routinely be recommended for prevention or mitigation of food allergies. Such interventions may be well-suited in male infants and in infants born to older mothers.

Gut microbiota, immune development and function

The microbiota of Westerners is significantly reduced in comparison to rural individuals living a similar lifestyle to our Paleolithic forefathers but also to that of other free-living primates such as the chimpanzee. The great majority of ingredients in the industrially produced foods consumed in the West are absorbed in the upper part of small intestine and thus of limited benefit to the microbiota. Lack of proper nutrition for microbiota is a major factor under-pinning dysfunctional microbiota, dysbiosis, chronically elevated inflammation, and the production and leakage of endotoxins through the various tissue barriers. Furthermore, the over-comsumption of insulinogenic foods and proteotoxins, such as advanced glycation and lipoxidation molecules, gluten and zein, and a reduced intake of fruit and vegetables, are key factors behind the commonly observed elevated inflammation and the endemic of obesity and chronic diseases, factors which are also likely to be detrimental to microbiota. As a consequence of this lifestyle and the associated eating habits, most barriers, including the gut, the airways, the skin, the oral cavity, the vagina, the placenta, the blood-brain barrier, etc., are increasingly permeable. Attempts to recondition these barriers through the use of so called 'probiotics', normally applied to the gut, are rarely successful, and sometimes fail, as they are usually applied as adjunctive treatments, e.g. in parallel with heavy pharmaceutical treatment, not rarely consisting in antibiotics and chemotherapy. It is increasingly observed that the majority of pharmaceutical drugs, even those believed to have minimal adverse effects, such as proton pump inhibitors and anti-hypertensives, in fact adversely affect immune development and functions and are most likely also deleterious to microbiota. Equally, it appears that probiotic treatment is not compatible with pharmacological treatments. Eco-biological treatments, with plant-derived substances, or phytochemicals, e.g. curcumin and resveratrol, and pre-, pro- and syn-biotics offers similar effects as use of biologicals, although milder but also free from adverse effects. Such treatments should be tried as alternative therapies; mainly, to begin with, for disease prevention but also in early cases of chronic diseases. Pharmaceutical treatment has, thus far, failed to inhibit the tsunami of endemic diseases spreading around the world, and no new tools are in sight. Dramatic alterations, in direction of a paleolithic-like lifestyle and food habits, seem to be the only alternatives with the potential to control the present escalating crisis. The present review focuses on human studies, especially those of clinical relevance.

Erythromycin treatment hinders the induction of oral tolerance to fed ovalbumin

The mucosal immune system is constantly exposed to antigen, whether it be food antigen, commensal bacteria, or harmful antigen. It is essential that the mucosal immune system can distinguish between harmful and non-harmful antigens, and initiate an active immune response to clear the harmful antigens, while initiating a suppressive immune response (tolerance) to non-harmful antigens. Oral tolerance is an immunologic hyporesponsiveness to an orally administered antigen and is important in preventing unnecessary gastrointestinal tract inflammation, which can result in a number of autoimmune and hypersensitivity diseases. Probiotics (beneficial intestinal bacteria), T regulatory cells, and dendritic cells (DCs) are all essential for generating tolerance. Antibiotics are commonly prescribed to fight infections and often necessary for maintaining health, but they can disrupt the normal intestinal probiotic populations. There is increasing epidemiologic evidence that suggests that antibiotic usage correlates with the development of atopic or irritable bowel disorders, which often result due to a breakdown in immune tolerance. This study investigated the effect of the antibiotic erythromycin on oral tolerance induction to ovalbumin. The results demonstrated that antibiotic treatment prior to exposure to fed antigen prevents tolerance to that antigen, which may be associated with a reduction in intestinal Lactobacillus populations. Furthermore, antibiotic treatment resulted in a significant decrease in the tolerogenic CD11c⁺/CD11b⁺/CD8α^- mesenteric lymph node DCs independent of tolerizing treatment. These results provide evidence that antibiotic treatment, potentially through its effects on tolerogenic DCs and intestinal microflora, may contribute to autoimmune and atopic disorders via a breakdown in tolerance and support prior epidemiologic studies correlating increased antibiotic usage with the development of these disorders.

A defined intestinal colonization microbiota for gnotobiotic pigs

Maximising the ability of piglets to survive exposure to pathogens is essential to reduce early piglet mortality, an important factor in efficient commercial pig production. Mortality rates can be influenced by many factors, including early colonization by microbial commensals. Here we describe the development of an intestinal microbiota, the Bristol microbiota, for use in gnotobiotic pigs and its influence on synthesis of systemic immunoglobulins. Such a microbiota will be of value in studies of the consequences of early microbial colonization on development of the intestinal immune system and subsequent susceptibility to disease. Gnotobiotic pig studies lack a well-established intestinal microbiota. The use of the Altered Schaedler Flora (ASF), a murine intestinal microbiota, to colonize the intestines of Caesarean-derived, gnotobiotic pigs prior to gut closure, resulted in unreliable colonization with most (but not all) strains of the ASF. Subsequently, a novel, simpler porcine microbiota was developed. The novel microbiota reliably colonized the length of the intestinal tract when administered to gnotobiotic piglets. No health problems were observed, and the novel microbiota induced a systemic increase in serum immunoglobulins, in particular IgA and IgM. The Bristol microbiota will be of value for highly controlled, reproducible experiments of the consequences of early microbial colonization on susceptibility to disease in neonatal piglets, and as a biomedical model for the impact of microbial colonization on development of the intestinal mucosa and immune system in neonates.

Integrative medicine and human health - the role of pre-, pro- and synbiotics

Western lifestyle is associated with a sustained low grade increase in inflammation -increased levels of endotoxin in the body and increased activation of Toll-like receptors and neutrophils, which leads to impaired immunity and reduced resistance to disease, changes which might explain the epidemic of chronic diseases spreading around the globe. The immune system cannot function properly without access to bacteria and raw plants, rich not only in bacteria but also in plant fibre, antioxidants, healthy fats and numerous other nutrients. Modern food technology with plant breeding, separation, condensation of food ingredients, heating, freezing, drying, irradiation, microwaving, are effective tool to counteract optimal immune function, and suspected to be a leading cause of so called Western diseases. Supply of pre-, pro-, and synbiotics have sometimes proved to be effective tools to counteract, especially acute diseases, but have often failed, especially in chronic diseases. Thousands of factors contribute to unhealth and numerous alterations in life style and food habits are often needed, in order to prevent and cure “treatment-resistant” chronic diseases. Such alterations include avoiding processed foods rich in pro-inflammatory molecules, but also a focus on consuming substantial amounts of foods with documented anti-inflammatory effects, often raw and fresh green vegetables and tubers such as turmeric/curcumin.

Can early exposure to probiotics in children prevent dental caries? A current perspective

BACKGROUND

Probiotics are supplements or foods that contain viable microorganisms which cause alterations of the microflora of the host. Probiotics have already been established in the treatment and prevention of various gastrointestinal system. Recently, role of probiotics has become an important issue for research in dentistry in the era of increased antibiotic resistance.

MATERIALS AND METHODS

The basis of the paper is the clinical studies and research done in relation to probiotics on oral health using PUBMED search database.

RESULTS AND CONCLUSIONS

Although many clinical studies have demonstrated positive outcome in preventing caries and periodontal diseases, the data is still scarce in recommending probiotics for the oral health. Moreover, since initial colonization of oral cavity of the newborn is very important for developing immunity and prevention of future diseases. Hence, measures should be directed towards its preventive use in infants and children. The formulations produced for oral cavity should also be within reach of common man especially in underdeveloped and developing countries. This review endeavors to compile the research of probiotics on oral cavity and throws a light on its evolving status in developing countries. It also evaluates its use in children for a long-term benefit.

Pro- and synbiotics to prevent sepsis in major surgery and severe emergencies

Septic morbidity associated with advanced surgical and medical treatments is unacceptably high, and so is the incidence of complications occurring in connection with acute emergencies such as severe trauma and severe acute pancreatitis. Only considering the US, it will annually affect approximately (app) 300 million (mill) of a population of almost one million inhabitants and cause the death of more than 200,000 patients, making sepsis the tenth most common cause of death in the US. Two major factors affect this, the lifestyle-associated increased weakness of the immune defense systems, but more than this the artificial environment associated with modern treatments such as mechanical ventilation, use of tubes, drains, intravascular lines, artificial nutrition and extensive use of synthetic chemical drugs, methods all known to reduce or eliminate the human microbiota and impair immune functions and increase systemic inflammation. Attempts to recondition the gut by the supply of microorganisms have sometimes shown remarkably good results, but too often failed. Many factors contribute to the lack of success: unsuitable choice of probiotic species, too low dose, but most importantly, this bio-ecological treatment has never been given the opportunity to be tried as an alternative treatment. Instead it has most often been applied as complementary to all the other treatments mentioned above, including antibiotic treatment. The supplemented lactic acid bacteria have most often been killed already before they have reached their targeted organs.

Probiotics as an emerging therapeutic strategy to treat NAFLD: focus on molecular and biochemical mechanisms

Nonalcoholic fatty liver disease (NAFLD) is currently the most common liver disease worldwide, both in adults and in children. NAFLD is characterized by aberrant lipid storage in hepatocytes (hepatic steatosis) and inflammatory progression to nonalcoholic steatohepatitis. Evidences so far suggest that intrahepatic lipid accumulation does not always derive from obesity. Gut microbiota has been considered as a regulator of energy homeostasis and ectopic fat deposition, suggesting its implications in metabolic diseases. Probiotics are live microbial that alter the enteric microflora and have beneficial effects on human health. Although the molecular mechanisms of probiotics have not been completely elucidated yet, many of their effects have proved to be beneficial in NAFLD, including the modulation of the intestinal microbiota, an antibacterial substance production, an improved epithelial barrier function and a reduced intestinal inflammation. Given the close anatomical and functional correlation between the bowel and the liver, and the immunoregulatory effects elicited by probiotics, the aim of this review is to summarize today's knowledge about probiotics in NAFLD, focusing in particular on their molecular and biochemical mechanisms, as well as highlighting their efficacy as an emerging therapeutic strategy to treat this condition.

Germ-free status and altered caecal subdominant microbiota are associated with a high susceptibility to cow's milk allergy in mice

Studies suggesting that the development of atopy is linked to gut microbiota composition are inconclusive on whether dysbiosis precedes or arises from allergic symptoms. Using a mouse model of cow's milk allergy, we aimed at investigating the link between the intestinal microbiota, allergic sensitization, and the severity of symptoms. Germ-free and conventional mice were orally sensitized with whey proteins and cholera toxin, and then orally challenged with β-lactoglobulin (BLG). Allergic responses were monitored with clinical symptoms, plasma markers of sensitization, and the T-helper Th1/Th2/regulatory-T-cell balance. Microbiota compositions were analysed using denaturing gradient gel electrophoresis and culture methods. Germ-free mice were found to be more responsive than conventional mice to sensitization, displaying a greater reduction of rectal temperature upon challenge, higher levels of blood mouse mast cell protease-1 (mMCP-1) and BLG-specific immunoglobulin G1 (IgG1), and a systemic Th2-skewed response. This may be explained by a high susceptibility to release mMCP-1 even in the presence of low levels of IgE. Sensitization did not alter the microbiota composition. However, the absence of or low Staphylococcus colonization in the caecum was associated with high allergic manifestations. This work demonstrates that intestinal colonization protects against oral sensitization and allergic response. This is the first study to show a relationship between alterations within the subdominant microbiota and severity of food allergy.

The role of the gut mucosal immunity in the development of tolerance against allergy to food

PURPOSE OF REVIEW

To provide an overview on the role of gut mucosal immunity in the development of tolerance against allergy to food.

RECENT FINDINGS

The gastrointestinal tract, through innate and specific immunologic factors, acts as a defense against ingested antigens. In addition to the mucous membrane integrity and digestion, numerous specific immunologic cells and mediators orchestrate such defensive mechanisms. In case of food antigens, the outcome is usually in favor of tolerance. Defects in that barrier, however, can lead to the development of aberrant immunologic responses, including hypersensitivity reactions.

SUMMARY

The prevailing evidence is that healthy mucosal immunity plus appropriate feeding regimen during early infancy are in favor of food tolerance. However, in addition to genetic predisposition, development of allergy is facilitated by defects in the gut barrier (immune or nonimmune) and the food allergen load.

Probiotics and immunity: a fish perspective

Probiotics are usually live microorganisms which when administered in adequate amounts confer a health benefits on host. Nowadays, probiotics are also becoming an integral part of the aquaculture practices to obtain high production. The common probiotics that are used for aquaculture practices include Lactobacillus, Lactococcus, Leuconostoc, Enterococcus, Carnobacterium, Shewanella, Bacillus, Aeromonas, Vibrio, Enterobacter, Pseudomonas, Clostridium, and Saccharomyces species. The involvement of probiotics in nutrition, disease resistance and other beneficial activities in fish has proven beyond any doubt. Among the numerous health benefits attributed to probiotics, modulation of immune system is one of the most commonly purported benefits of the probiotics and their potency to stimulate the systemic and local immunity under in vitro and in vivo conditions is noteworthy. Different probiotics either monospecies or multispecies supplementation can eventually elevate phagocytic, lysozyme, complement, respiratory burst activity as well as expression of various cytokines in fish. Similarly, probiotics can stimulate the gut immune system of fish with marked increase in the number of Ig(+) cells and acidophilic granulocytes. Furthermore, mono-bacterial association studies (with non-probiotic bacterial strains) in gnotobiotic fish also indicate the up-regulation of various immune related genes. Though the exact mode of action of probiotics is yet to be established in any animal including fish, probiotics often exert host specific and strain specific differences in their activities. Various factors like source, type, dose and duration of supplementation of probiotics can significantly affect the immunomodulatory activity of probiotics. The review is therefore, aiming to highlight the immunomodulatory activity of probiotics and also to evaluate the factors that regulate for the optimum induction of immune responses in fish.

Pro- and synbiotics to control inflammation and infection in patients with multiple injuries

BACKGROUND

A recent randomized clinical trial of our group disclosed considerable reduction of the infective sequelae after administration of a synbiotic formula, namely Synbiotic 2000FORTE, in patients with multiple injuries, the latter being a preparation of four probiotics. The mechanism of action of synbiotics was studied.

METHODS

A total of 72 patients with severe multiple injuries were allocated to a 15-day administration of either placebo or the synbiotic formula. The association of bloodstream infections, ventilator-associated pneumonia (VAP), serum levels of C-reactive protein (CRP), and endotoxins (LPS) were studied.

RESULTS

Sepsis in the field of bacteremia occurred in 13 patients treated with placebo (36.1%) compared with 5 patients treated with Synbiotic 2000FORTE (13.9%, p = 0.028 between groups). The time to progression to primary bacteremia was longer among patients treated with Synbiotic 2000FORTE compared with placebo (p = 0.0237 between groups). Twelve (33.3%) and five (13.9%) placebo-treated and probiotic-treated patients, respectively, developed ventilator-associated pneumonia with Acinetobacter baumannii as a bacterial cause (p = 0.047 between groups). Treatment with synbiotics was accompanied by reduction of white blood cell counts and LPS and CRP levels in either patients who did or did not develop sepsis.

CONCLUSIONS

Synbiotics contained in the studied formula decrease significantly the risk for sepsis by bloodstream infections and the occurrence of VAP by A. baumannii. The mechanisms of action might involve direct immunomodulatory effect, prevention of bacterial translocation, or most likely a combination of both.

Bio-ecological control of chronic liver disease and encephalopathy

Minimal encephalopathy was originally associated with chronic liver disease but is increasingly associated with most other chronic diseases and particularly with diabetes and also chronic disorders in other organs: kidneys, lungs, thyroid and with obesity. It is increasingly with dramatically increased and more or less permanent increase in systemic inflammation, most likely a result of Western lifestyle. Frequent physical exercise and intake of foods rich in vitamins, antioxidants, fibres, lactic acid bacteria etc in combination with reduction in intake of refined and processed foods is known to reduce systemic inflammation and prevent chronic diseases. Some lactic acid bacteria, especially Lb paracasei, lb plantarum and pediococcus pentosaceus have proven effective to reduce inflammation and eliminate encephalopathy. Significant reduction in blood ammonia levels and endotoxin levels were reported in parallel to improvement of liver disease. Subsequent studies with other lactic acid bacteria seem to demonstrate suppression of inflammation and in one study also evidence of clinical improvement.

Lactobacillus casei potentiates induction of oral tolerance in experimental arthritis

Probiotics have been shown to exert beneficial effects on modulation of diverse diseases. However, no information is available for the effect of probiotics in the induction of oral tolerance in autoimmune diseases. The main purpose of this study was to elucidate whether Lactobacillus casei (L. casei) affect the induction of oral tolerance in experimental rheumatoid arthritis (RA). Type II collagen (CII) alone or together with L. casei was orally administered into collagen-induced arthritis (CIA) rats, and its effects on the clinical and histopathological aspects of RA were investigated. Co-administration of L. casei with CII more effectively suppressed clinical symptoms, paw swelling, lymphocyte infiltration and destruction of cartilage tissues of experimental arthritis than the rats treated with CII alone. The enhanced therapeutic efficacy was associated with an increase in anti-inflammatory cytokines (IL-10 and TGF-beta) while decreasing pro-inflammatory cytokines (IL-1beta, IL-2, IL-6, IL-12, IL-17, IFN-gamma and TNF-alpha). Co-administration of L. casei with CII more effectively suppressed CII-reactive T cell proliferation and the levels of Th1-type IgG isotypes (IgG2a and IgG2b), while up-regulating Foxp3 expression levels and the population of Foxp3(+) CD4(+) T cells. Our study provides evidence that L. casei could potentiate antigen-specific oral tolerance and suppress Th1-type immune responses of arthritic inflammation.

Which role for prebiotics at weaning?

It is now generally recognized that the intestinal microflora plays a key role for human health and well being. In fact, the gut ecosystem is involved in a number of biologic functions, such as direct and indirect antipathogen activity (nutritive competition, reduction of pH, production of short-chain fatty acids, maturation and protection of the mucosal barrier, etc), synthesis of vitamins, detoxification of potentially harmful substances, and maturation and regulation of the immune system. Weaning represents a crucial step in the development of the intestinal flora and, at the same time, corresponds to a very delicate phase of immunologic maturation. A safe and effective way to beneficially influence the intestinal microflora is the administration of prebiotics, which selectively promote the growth and/or activity of beneficial bacteria, such as bifidobacteria. Some of the studies, which investigated the microbiologic and clinical effectiveness of prebiotics have been conducted at weaning, reporting interesting results. Anyway, many of the promising beneficial effects evidenced still need to be confirmed by further large randomized trials.

Review article: future research on coeliac disease - a position report from the European multistakeholder platform on coeliac disease (CDEUSSA)

BACKGROUND

CDEUSSA is a Specific Support Action project from the Sixth Framework Programme Priority of the European Union (EU). Its aim is to bring together basic and applied research in the area of coeliac disease (CD). This paper reviews the main issues that are a result of the CDEUSSA initiative.

AIM

To identify the major issues in need of investigation in the areas of clinical aspects, treatment, prevention and public health.

METHODS

Key stakeholders, representing a wide range of knowledge with crucial importance for CD research and practice, have participated in two workshops aimed at identifying and proposing to the EU, as high priority research, topics in the areas of clinical aspects, treatment, prevention and public health.

RESULTS

In public health, the overall goal should be to improve quality of life of the European population by implementing primary prevention strategies, early diagnosis and improved treatments for CD. New treatment strategies need to be developed. The option of primary prevention should be fully explored, which requires combined epidemiological, clinical and basic scientific research efforts. Such studies should also consider the importance of gene-environment interactions in the development of CD. Increased knowledge is needed on the natural history of CD. Diagnostic criteria need to be revised.

CONCLUSIONS

To achieve these goals, a collaboration of the stakeholders is fundamental, including research and patient organizations, as well as industries within both diagnostics and food production.

Importance of the interferon-alpha system in murine large intestine indicated by microarray analysis of commensal bacteria-induced immunological changes

Background

Although microbiota play a critical role in the normal development and function of host immune systems, the underlying mechanisms, especially those involved in the large intestine (LI), remain unknown. In the present study, we performed transcriptome analysis of the LI of germ-free (GF) and specific pathogen-free (SPF) mice of the IQI strain, an inbred strain established from ICR mice.

Results

GeneChip analysis, quantitative real-time RT-PCR, and reconfirmation using bacteria-inoculated GF mice revealed differences in the expression levels of several immune-related genes, such as cryptdin-related sequences (CRS), certain subsets of type 1 interferon (IFN)-related genes, class Ib MHC molecules, and certain complements. LI expressed no authentic cryptdins but predominantly expressed CRS2, 4, and 7. The mRNA levels of IFN-related genes, including Irf7, Isgf3g, Ifit1 and Stat1, were lower in SPF- and flora-reconstituted mice. When an oral IFN-α inducer tilorone analog, R11567DA, was administered to SPF mice, IFN-α was induced rapidly in the LI at 4 h, whereas no IFN-α protein was detected in the small intestine (SI) or blood. In situ hybridization and immunohistochemistry suggested that the IFN-α production originated from Paneth cells in the SI, and portions of lamina proprial CD11b- or mPDCA1-positive cells in the LI.

Conclusion

The present study suggests that microbial colonization, while inducing the expression of anti-microbial peptides, results in the down-regulation of certain genes responsible for immune responses, especially for type I IFN synthesis. This may reflect the adaptation process of the immune system in the LI to prevent excessive inflammation with respect to continuous microbial exposure. Further, the repertoire of anti-microbial peptides and the extraordinary role of interferon producing cells in the LI have been found to be distinct from those in the SI.

A review of the functionality of probiotics in the larviculture food chain

During the past two decades, the use of probiotics as an alternative to the use of antibiotics has shown to be promising in aquaculture, particularly in fish and shellfish larviculture. This article reviews the studies on probiotics in larviculture, focusing on the current knowledge of their in vivo mechanisms of action. The article highlights that the in vivo mechanisms of action largely remain to be unravelled. Several methodologies are suggested for further in vivo research, including studies on gut microbiota composition, the use of gnotobiotic animals as test models, and the application of molecular techniques to study host-microbe and microbe-microbe interactions.

Susceptibility to nasal and oral tolerance induction to the major birch pollen allergen Bet v 1 is not dependent on the presence of the microflora

The indigenous microflora plays an integrative role in the maintenance of immunological homeostasis. Several studies reported that immunological tolerance is dependent on microbial colonization of the gut. In the present study, we investigated whether the absence of the microflora influences the sensitization process to an allergen as well as the ability to develop mucosal tolerance in a mouse model of birch pollen allergy. Germ-free or conventional BALB/c mice were intranasally or intragastrically pre-treated with the major birch pollen allergen Bet v 1 prior to sensitization with this allergen. Both germ-free and conventional mice displayed comparable Th2 biased immune responses after allergic sensitization. Oral as well as intranasal tolerization led to suppression of allergen-specific serum antibodies (IgG1, IgE, IgA) as well as cytokine production by splenocytes (IL-5, IFN-gamma) in both germ-free and conventional animals. Peyer's patches of germ-free animals were approximately 20 times smaller than in conventional animals, but the relative distribution of lymphocyte subpopulations was equal. We conclude that the absence of the microflora does not influence the ability to mount Th2 responses nor to establish tolerance towards the aeroallergen Bet v 1. Our findings may challenge the view that the commensal microflora is a key factor for breakdown of physiological tolerance and allergy development.

Presence of two Lactobacillus and Bifidobacterium probiotic strains in the neonatal ileum

The overall purpose of this study was to examine the lactobacilli and bifidobacteria microbiota in the human ileum at a very early stage of life. Ileostomy effluents from two infants, taken at different time points, were plated on Lactobacillus selective agar and cys-MRS containing mupirocin to select for bifidobacteria. In one case, a stool sample following ileostomy reversal was subsequently analyzed microbiologically. Pulse-field gel electrophoresis and 16S rRNA sequencing was used to investigate the cultivable population of bifidobacteria and lactobacilli and denaturing gradient gel electrophoresis (DGGE) to examine the non-cultivable population. The probiotic strain, Lactobacillus paracasei NFBC 338, was recovered at both time points from one of the infants and dominated in the small intestine for a period of over 3 weeks. Moreover, the probiotic strain, B. animalis subsp. lactis Bb12, was obtained from the other infant. This study shows the presence of two known probiotic strains in the upper intestinal tract at an early stage of human life and thus provides some evidence for their ability to colonize the infant small intestine.

Development of mucosal immune function in the intrauterine and early postnatal environment

PURPOSE OF REVIEW

There is recent evidence that immunological priming can start prenatally or in the very early life phase. This review summarizes recent progress in the field of early gut immunology with special attention to factors contributing to the intrauterine and early postnatal development of mucosal immune responses in the gut.

RECENT FINDINGS

Development and maturation of the fetal gut immune system occurs under close control of the maternal environment. Examples include maternal antibodies, cytokines, sCD14 molecules and bacterial antigens. Mouse experiments reveal that activated T cells can be detected already at birth in the fetal gut, which are supposed to be activated by signals from the maternal microbial gut flora. Human milk sCD14 is involved in the immunological priming of the developing gut immune system to Gram-negative bacteria and modulates the microbial recognition system of the gut. The development of food allergies is associated with consumption of food components like polyunsaturated fatty acids acting prenatally or in the early postnatal life span as immunomodulators.

SUMMARY

The new findings highlight the importance of very early life factors for the development of the mucosal immune functions of the gut. Therefore, the gut might be a new target to establish preventive strategies with regard to different immunologic disorders.

Effect of herbal medicine Juzentaihoto on hepatic and intestinal heat shock gene expression requires intestinal microflora in mouse

AIM: To evaluate the role of intestinal microflora in the effects of multi-herbal medicine on gene expression in the gut and liver.

METHODS: The multi-herbal medicine Juzentaihoto (JTX) was administered to five germ-free mice and regular mice for 2 wk. Among the results of the comprehensive gene chip analysis of the intestine and liver, we featured heat shock proteins (HSPs) 70 and 105 because their gene expression changed only in the presence of microflora. Real-time RT-PCR was performed to confirm the expression levels of these HSP genes. To determine whether JTX acts directly on the HSP genes, sodium arsenite (SA) was used to induce the heat shock proteins directly. To examine the change of the intestinal microflora with administration of JTX, the terminal restriction fragment polymorphism (T-RFLP) method was used. To identify the changed bacteria, DNA sequencing was performed.

RESULTS: Heat shock protein gene expression, documented by gene chip and real-time RT-PCR, changed with the administration of JTX in the regular mice but not in the germ-free mice. JTX did not suppress the direct induction of the HSPs by SA. T-RFLP suggested that JTX decreased unculturable bacteria and increased Lactobacillus johnsoni. These data suggested that JTX changed the intestinal microflora which, in turn, changed HSP gene expression.

CONCLUSION: Intestinal microflora affects multi-herbal product JTX on the gene expression in the gut and liver.

Retinol concentrations after birth are inversely associated with atopic manifestations in children and young adults

BACKGROUND

Vitamin A has anti-inflammatory and immunomodulatory effects, and its deficiency results in impaired specific and innate immunity. Vitamin A is essential for inducing the gut-homing specificity on T cells.

OBJECTIVE

As an impaired gut immune response in early infancy may contribute to the development of atopic sensitization, we looked for an association of plasma retinol concentrations and the subsequent development of allergic symptoms in healthy infants.

METHODS

A cohort of 200 unselected, full-term newborns were followed up from birth to age 20 years. The plasma retinol concentration was determined in cord blood (n=97), at ages of 2, 4 and 12 months (n=95), and at ages 5 years (n=155) and 11 years (n=151). The subjects were re-examined at the ages of 5, 11 and 20 years with assessment of the occurrence of allergic symptoms during the preceding year, skin prick testing and measurement of serum total IgE.

RESULTS

subjects with allergic symptoms or a positive skin prick test (SPT) in childhood or adolescence had lower retinol concentrations in infancy and childhood than symptom-free subjects. The difference was most pronounced at age 2 months. Retinol concentration at 2 months correlated inversely with positive SPT at ages of 5 and 20 years, and with allergic symptoms at age 20 years.

CONCLUSION

Retinol concentration in young infants is inversely associated with the subsequent development of allergic symptoms. We propose that an inborn regulation of retinol may play a role in atopic sensitization, possibly through regulating the intestinal T cell responses.

Antibiotic administration early in life impairs specific humoral responses to an oral antigen and increases intestinal mast cell numbers and mediator concentrations

In this study, we assessed the effect of administering the antibiotic amoxicillin to rat pups on the immune response to orally fed ovalbumin (OVA). We first established that amoxicillin administration durably altered the gut microbiota of these animals. In parallel, we observed that the induction of the specific humoral response to ovalbumin was impaired when it occurred during antibiotic administration to the rat pups. We also examined the consequences of those observations on further allergic reactions. Amoxicillin administration had no significant impact on subsequent sensitization to OVA, as nonexacerbated systemic allergic responses were induced in antibiotic-treated animals. However, increased rat mast cell protease II levels and higher mast cell numbers were detected in their small intestines, independently of the antigen administration. Globally, our data suggest that antibiotic administration early in life negatively affects the specific immune response to a luminal antigen when it is first introduced during antibiotic administration. The increased mast cell numbers and mediator concentrations in the intestinal mucosae of the antibiotic-treated animals may testify to the early stages of an altered immune system homeostasis.

Constitutive delivery of bovine beta-lactoglobulin to the digestive tracts of gnotobiotic mice by engineered Lactobacillus casei

The gut microbiota is critical for maturation of the immune system. Recent evidence suggests that early establishment of lactobacilli in the intestinal microbiota, during neonatal colonization or by probiotic supplementation, could prevent the development of allergic disorders. Postnatal maturation of the gut immune system with allergen-producing lactobacilli colonizing the digestive tract could then affect the development of further allergic sensitization. In this paper, we describe construction of a recombinant Lactobacillus casei strain that can constitutively deliver bovine beta-lactoglobulin (BLG), a major cow's milk allergen, to the guts of gnotobiotic mice. The blg gene was inserted into the L. casei chromosome downstream of an endogenous promoter. BLG production was improved by fusing the propeptide LEISSTCDA (LEISS) to the BLG mature moiety. This led to a 10-fold increase in LEISS-BLG production compared to the production obtained without the propeptide and also led to enhanced secretion corresponding to 5% of the total production. After inoculation into germfree C3H/HeN mice, the genetic stability of the recombinant strain and in vivo BLG production were confirmed for at least 10 weeks. BLG stimulation of spleen cells from mice monoassociated with the BLG-producing lactobacilli induced secretion of the Th1 cytokine gamma interferon and, to a lesser extent, the Th2 cytokine interleukin-5. No BLG-specific immunoglobulin G1 (IgG1), IgG2a, or IgA was detected in sera or in fecal samples. These results suggest that gut colonization with allergen-producing lactobacilli could provide a useful model for studying the modulation of allergic disorders.

Live bacterial vaccines--a review and identification of potential hazards

The use of live bacteria to induce an immune response to itself or to a carried vaccine component is an attractive vaccine strategy. Advantages of live bacterial vaccines include their mimicry of a natural infection, intrinsic adjuvant properties and their possibility to be administered orally. Derivatives of pathogenic and non-pathogenic food related bacteria are currently being evaluated as live vaccines. However, pathogenic bacteria demands for attenuation to weaken its virulence. The use of bacteria as vaccine delivery vehicles implies construction of recombinant strains that contain the gene cassette encoding the antigen. With the increased knowledge of mucosal immunity and the availability of genetic tools for heterologous gene expression the concept of live vaccine vehicles gains renewed interest. However, administration of live bacterial vaccines poses some risks. In addition, vaccination using recombinant bacteria results in the release of live recombinant organisms into nature. This places these vaccines in the debate on application of genetically modified organisms. In this review we give an overview of live bacterial vaccines on the market and describe the development of new live vaccines with a focus on attenuated bacteria and food-related lactic acid bacteria. Furthermore, we outline the safety concerns and identify the hazards associated with live bacterial vaccines and try to give some suggestions of what to consider during their development.

T cell-mediated oral tolerance is intact in germ-free mice

Commensal enteric bacteria stimulate innate immune cells and increase numbers of lamina propria and mesenteric lymph node (MLN) T and B lymphocytes. However, the influence of luminal bacteria on acquired immune function is not understood fully. We investigated the effects of intestinal bacterial colonization on T cell tolerogenic responses to oral antigen compared to systemic immunization. Lymphocytes specific for ovalbumin-T cell receptor (OVA-TCR Tg(+)) were transplanted into germ-free (GF) or specific pathogen-free (SPF) BALB/c mice. Recipient mice were fed OVA or immunized subcutaneously with OVA peptide (323-339) in complete Freund's adjuvant (CFA). Although the efficiency of transfer was less in GF recipients, similar proportions of cells from draining peripheral lymph node (LN) or MLN were proliferating 3-4 days later in vivo in GF and SPF mice. In separate experiments, mice were fed tolerogenic doses of OVA and then challenged with an immunogenic dose of OVA 4 days later. Ten days after immunization, lymphocytes were restimulated with OVA in vitro to assess antigen-specific proliferative responses. At both high and low doses of OVA, cells from both SPF and GF mice fed OVA prior to immunization had decreased proliferation compared to cells from control SPF or GF mice. In addition, secretion of interferon (IFN)-gamma and interleukin (IL)-10 by OVA-TCR Tg(+) lymphocytes was reduced in both SPF and GF mice fed OVA compared to control SPF or GF mice. Unlike previous reports indicating defective humoral responses to oral antigen in GF mice, our results indicate that commensal enteric bacteria do not enhance the induction of acquired, antigen-specific T cell tolerance to oral OVA.

The development of the mucosal immune system pre- and post-weaning: balancing regulatory and effector function

The mucosal immune system fulfils the primary function of defence against potential pathogens that may enter across vulnerable surface epithelia. However, a secondary function of the intestinal immune system is to discriminate between pathogen-associated and 'harmless' antigens, expressing active responses against the former and tolerance to the latter. Control of immune responses appears to be an active process, involving local generation of IgA and of regulatory and/or regulated T lymphocytes. Two important periods of maximum exposure to novel antigens occur in the young animal, immediately after birth and at weaning. In both cases the antigenic composition of the intestinal contents can shift suddenly, as a result of a novel diet and of colonisation by novel strains and species of bacteria. Changes in lifestyles of man, and husbandry of animals, have resulted in weaning becoming much more abrupt than previously in evolution, increasing the number of antigens that must be simultaneously evaluated by neonates. Thus, birth and weaning are likely to represent hazard and critical control points in the development of appropriate responses to pathogens and harmless dietary and commensal antigens. Neonates are born with relatively undeveloped mucosal immune systems. At birth this factor may prevent both expression of active immune responses and development of tolerance. However, colonisation by intestinal flora expands the mucosal immune system in antigen-specific and non-specific ways. At weaning antibody to fed proteins can be detected, indicating active immune responses to fed proteins. It is proposed that under normal conditions the ability of the mucosal immune system to mount active responses to foreign antigens develops simultaneously with the ability to control and regulate such responses. Problems arise when one or other arm of the immune system develops inappropriately, resulting in inappropriate effector responses to harmless food proteins (allergy) or inadequate responses to pathogens (disease susceptibility).

The influence of environment on development of the mucosal immune system

The mucosal immune system expresses active responses against pathogens and also tolerance against harmless food and commensal bacterial antigens. The mechanisms that determine which of these outcomes occur after recognition of antigens by T-cells are not clear. One possibility is that it is determined by the initial interaction between a dendritic and a naïve T-cell in organised lymphoid tissue. However, such organised structures are, evolutionarily, quite recent and the original immune system must have made appropriate responses in more diffuse immunological architecture; a second possibility is that the critical interaction is between primed T-cells and their environment, in the lamina propria of the intestine. The mucosal immune system of neonates is poorly developed and inefficient at expressing appropriate immune responses. Development is influenced by a range of environmental factors including maternally derived antigen or antibody and commensal flora and pathogens. The intestine is a complex immunological structure in which the immune system and the macro- and microenvironment interact.

Innate mechanisms for Bifidobacterium lactis to activate transient pro-inflammatory host responses in intestinal epithelial cells after the colonization of germ-free rats

Bifidobacteria comprise a dominant microbial population group in the human intestinal tract with purported beneficial health effects on the host. In this study, we characterized the molecular mechanisms for the initial interaction of probiotic Bifidobacterium lactis strain BB12 with native and intestinal epithelial cell (IEC) lines. We showed that B. lactis-monoassociated Fisher F344 rats transiently induce phosphorylation/activation of the NF-kappaB transcriptionally active subunit RelA and the mitogen-activated protein kinase (MAPK) p38 in native IEC at day 5 after initial bacterial colonization. In addition, Interleukin 6 (IL-6) gene expression was significantly increased at day 5, demonstrating the physiological relevance of transient transcription factor activation in IEC. In contrast, Bacteroides vulgatus-monoassociated Fisher rats revealed RelA but not p38 MAPK phosphorylation and failed to trigger significant IL-6 gene expression in native IEC. Moreover, we demonstrated that B. lactis triggers NF-kappaB RelA and p38 MAPK phosphorylation in IEC lines. Adenoviral delivery of mutant IKK-beta (Ad5dnIKKbeta) and inhibition of the p38 MAPK pathway through the pharmacological inhibitor SB203580 significantly blocked B. lactis-induced IL-6 gene expression in IEC, suggesting that B. lactis triggers NF-kappaB and MAPK signaling to induce gene expression in the intestinal epithelium. Regarding the mechanisms of bacteria epithelial cell cross-talk, B. lactis-induced IL-6 gene expression was completely inhibited in TLR2 deficient mouse embryogenic fibroblasts (MEF TLR2-/-) as well as TLR2DeltaTIR transfected Mode-K cells. In conclusion, we demonstrated that probiotic bacteria transiently trigger innate signal transduction and pro-inflammatory gene expression in the intestinal epithelium at early stages of bacterial colonization.

Mucosal immunity and allergic responses: lack of regulation and/or lack of microbial stimulation?

Allergic hyperreactivity is defined as an exaggerated immune response [typically immunoglobulin E (IgE) but also non-IgE mediated] toward harmless antigenic stimuli. The prevalence of allergic disease has increased dramatically during the last 20 years, especially in developed countries. Both genetic and environmental factors contribute to susceptibility to allergy. Evidence has emerged supporting the hypothesis that a reduction in antigenic stimulation brought about by widespread vaccination, improvements in standards of hygiene, and extensive use of antibiotics has contributed to the dysregulation of T-helper 2 cell (Th2) type responsiveness that typifies allergy. Regulation of the inherently Th2-biased mucosal immune response is crucial both to the maintenance of homeostasis at this strategic defensive barrier and to the prevention of allergic disease. The ability of Th1 responses to counter-regulate Th2 reactivity is well characterized. More recently, interest has centered on regulatory T cells, which can suppress both Th1 and Th2 cells through the secretion of immunosuppressive cytokines such as interleukin-10 and transforming growth factor-beta. In this review, we discuss the basic cellular mechanisms of allergic diseases at mucosal surfaces, focusing on allergic responses to food, before examining newer work that suggests the induction of allergic hyperreactivity is due to a deficient immunoregulatory network, a lack of microbial stimulation, or both.

A Full Flora, but not Monocolonization by Escherichia coli or Lactobacilli, Supports Tolerogenic Processing of a Fed Antigen

Fed protein undergoes processing and coupling to major histocompatibility complex (MHC) II molecules during passage through the intestinal epithelium, generating a tolerogenic form of the antigen in serum. Transfer of this factor to naïve animals induces tolerance in the recipient. In this study, we investigate what impact colonization with Gram-positive (Lactobacillus plantarum) or Gram-negative (Escherichia coli) bacteria has on tolerogenic processing in the gut. Germ-free (GF), monocolonized or conventional mice were fed ovalbumin (OVA), and their serum was collected and transferred to naïve conventional recipients that were tested for delayed-type hypersensitivity against OVA after parenteral immunization. A transferable tolerogenic factor was produced by conventional mice, but not by mice that were germ free or monocolonized with either E. coli or L. plantarum. Conventional, but neither GF nor monocolonized mice showed upregulation of MHCII expression in the epithelium of small intestine. The results suggest that a complex intestinal microflora is needed to support oral tolerance development.

Bacteriotherapy and probiotics’ role on oral health

Oral infections constitute some of the most common and costly forms of infections in humans. The concept of microbial ecological change as a mechanism for preventing dental disease is an important one while altered microbial ecology may lead to dental disease. New methods such as probiotic approaches (i.e. whole bacteria replacement therapy) to eliminate pathogenic members of the microbiota can be investigated. Bacteriotherapy is an alternative and promising way to combat infections by using harmless bacteria to displace pathogenic microorganisms. Probiotics are one of these new agents which are widely used for their therapeutic action. Limited research is available showing that some probiotic cultures may help dental improvement. Present paper focuses on possible oral benefits of probiotics.

Oral administration of recombinant Lactococcus lactis expressing bovine beta-lactoglobulin partially prevents mice from sensitization

BACKGROUND

The use of probiotics such as Lactococcus lactis and other lactic acid bacteria (LAB) has been proposed for the management of food allergy. However, no experimental study has clearly demonstrated any preventive or therapeutic inhibition of an allergen-specific IgE response.

OBJECTIVE

We aimed to study the immunomodulatory effect of recombinant L. lactis expressing bovine beta-lactoglobulin (BLG), a major cow's milk allergen, in a validated mouse model of allergy.

METHODS

Six-week-old female Balb/c mice received five repeated doses of BLG, of L. lactis plus BLG, or of recombinant L. lactis by gavage. Different recombinant strains were inoculated, which corresponded to BLG doses ranging from 4 to 70 microg/mice. Mice were then sensitized by intra-peritoneal injection of BLG emulsified in incomplete Freund's adjuvant to induce high IgE concentrations.

RESULTS

Pre-treatment with natural L. lactis plus BLG allowed induction of BLG-specific T-helper type 1 (Th1) response, and abrogated the oral tolerance induced by BLG alone, demonstrating the adjuvant effect of this non-colonizing LAB. Moreover, pre-treatment with some of the recombinant strains favoured the development of a Th1 response inhibiting the Th2 one: it induced a significant decrease of specific IgE response, and an intense increase of specific IgG2a and IFN-gamma productions. The most efficient strains that inhibited the IgE response were those producing the highest amounts of the BLG protein.

CONCLUSION

Oral administration of some recombinant L. lactis was demonstrated to induce a specific Th1 response down-regulating a further Th2 one. Prophylaxis protocols will thus be evaluated using the most efficient strains.

Probiotics and down-regulation of the allergic response

The first clinical trials with probiotics, especially in the treatment of atopic eczema, have yielded encouraging results. Experimental studies have found that probiotics exert strain-specific effects in the intestinal lumen and on epithelial cells and immune cells with anti-allergic potential. These effects include enhancement in antigen degradation and gut barrier function and induction of regulatory and proinflammatory immune responses, the latter of which occurs more likely beyond the intestinal epithelium. Future studies should address more accurately how these and other possible mechanisms operate in the complex gastrointestinal macroenvironment in vivo and how these mechanisms are related to the clinical effects in a dose-dependent manner.

Stimulation of interleukin-10 production by acidic beta-lactoglobulin-derived peptides hydrolyzed with Lactobacillus paracasei NCC2461 peptidases

We have previously demonstrated that Lactobacillus paracasei NCC2461 may help to prevent cow's milk allergy in mice by inducing oral tolerance to beta-lactoglobulin (BLG). To investigate the mechanisms involved in this beneficial effect, we examined the possibility that L. paracasei induces tolerance by hydrolyzing BLG-derived peptides and liberating peptides that stimulate interleukin-10 (IL-10) production. L. paracasei peptidases have been shown to hydrolyze tryptic-chymotryptic peptides from BLG, releasing numerous small peptides with immunomodulating properties. We have now shown that acidic tryptic-chymotryptic peptides stimulate splenocyte proliferation and gamma interferon (IFN-gamma) production in vitro. Hydrolysis of these peptides with L. paracasei peptidases repressed the lymphocyte stimulation, up-regulated IL-10 production, and down-regulated IFN-gamma and IL-4 secretion. L. paracasei NCC2461 may therefore induce oral tolerance to BLG in vivo by degrading acidic peptides and releasing immunomodulatory peptides stimulating regulatory T cells, which function as major immunosuppressive agents by secreting IL-10.