Effect of bifidobacteria feeding on fecal flora and production of immunoglobulins in lactating mouse

Disruption of the early-life microbiota alters Peyer's patch development and germinal center formation in gastrointestinal-associated lymphoid tissue

During postnatal development, both the maturing microbiome and the host immune system are susceptible to environmental perturbations such as antibiotic use. The impact of timing in which antibiotic exposure occurs was investigated by treating mice from days 5-9 with amoxicillin or azithromycin, two of the most commonly prescribed medications in children. Both early-life antibiotic regimens disrupted Peyer's patch development and immune cell abundance, with a sustained decrease in germinal center formation and diminished intestinal immunoglobulin A (IgA) production. These effects were less pronounced in adult mice. Through comparative analysis of microbial taxa, Bifidobacterium longum abundance was found to be associated with germinal center frequency. When re-introduced to antibiotic-exposed mice, B. longum partially rescued the immunological deficits. These findings suggest that early-life antibiotic use affects the development of intestinal IgA-producing B cell functions and that probiotic strains could be used to restore normal development after antibiotic exposure.

Recent Development of Probiotic Bifidobacteria for Treating Human Diseases

Bifidobacterium is a non-spore-forming, Gram-positive, anaerobic probiotic actinobacterium and commonly found in the gut of infants and the uterine region of pregnant mothers. Like all probiotics, Bifidobacteria confer health benefits on the host when administered in adequate amounts, showing multifaceted probiotic effects. Examples include B. bifidum, B. breve, and B. longum, common Bifidobacterium strains employed to prevent and treat gastrointestinal disorders, including intestinal infections and cancers. Herein, we review the latest development in probiotic Bifidobacteria research, including studies on the therapeutic impact of Bifidobacterial species on human health and recent efforts in engineering Bifidobacterium. This review article would provide readers with a wholesome understanding of Bifidobacteria and its potentials to improve human health.

Health effects of probiotics on the skin

Skin is the largest organ of the body and is constantly exposed to physical, chemical, bacterial, and fungal challenges. It is well known that probiotics are helpful for specific disorders and different clinical studies have indicated that probiotics have special effects in cutaneous apparatus directly or indirectly that can be considerable from versatile aspects. Probiotic bacteriotherapy can have great potential in preventing and treating the skin diseases including eczema, atopic dermatitis, acne, and allergic inflammation or in skin hypersensitivity, UV-induced skin damage, wound protection, and as a cosmetic product. The current paper comprehensively reviews the different health effects of probiotics on the skin.

Oral administration of Lactobacillus plantarum 299v modulates gene expression in the ileum of pigs: prediction of crosstalk between intestinal immune cells and sub-mucosal adipocytes

To study host-probiotic interactions in parts of the intestine only accessible in humans by surgery (jejunum, ileum and colon), pigs were used as model for humans. Groups of eight 6-week-old pigs were repeatedly orally administered with 5 × 10(12) CFU Lactobacillus plantarum 299v (L. plantarum 299v) or PBS, starting with a single dose followed by three consecutive daily dosings 10 days later. Gene expression was assessed with pooled RNA samples isolated from jejunum, ileum and colon scrapings of the eight pigs per group using Affymetrix porcine microarrays. Comparison of gene expression profiles recorded from L. plantarum 299v-treated pigs with PBS-treated pigs indicated that L. plantarum 299v affected metabolic and immunological processes, particularly in the ileum. A higher expression level of several B cell-specific transcription factors/regulators was observed, suggesting that an influx of B cells from the periphery to the ileum and/or the proliferation of progenitor B cells to IgA-committed plasma cells in the Peyer's patches of the ileum was stimulated. Genes coding for enzymes that metabolize leukotriene B4, 1,25-dihydroxyvitamin D3 and steroids were regulated in the ileum. Bioinformatics analysis predicted that these metabolites may play a role in the crosstalk between intestinal immune cells and sub-mucosal adipocytes. Together with regulation of genes that repress NFKB- and PPARG-mediated transcription, this crosstalk may contribute to tempering of inflammatory reactions. Furthermore, the enzyme adenosine deaminase, responsible for the breakdown of the anti-inflammatory mediator adenosine, was strongly down-regulated in response to L. plantarum 299v. This suggested that L. plantarum 299v-regulated production of adenosine by immune cells like regulatory T cells may also be a mechanism that tempers inflammation in the ileum, and perhaps also in other parts of the pig's body.

1-Kestose consumption during pregnancy and lactation increases the levels of IgA in the milk of lactating mice

To examine the effect of dietary supplementation with 1-kestose on the IgA levels in milk, BALB/c mice were fed diets with or without 5% 1-kestose during pregnancy and lactation. The total and specific IgA levels in the milk were measured at 7 and 14 days after delivery. A two-way ANOVA with repeated measures resulted in a significant effect of 1-kestose-supplementation on total IgA concentrations (p < 0.05) and the level of anti-Bacteroides IgA (p < 0.05). A significant positive correlation was found between the mean count of Bacteroides spp. in maternal feces and the total IgA concentration in maternal milk (r = 0.55, p < 0.05), suggesting a potential link between the gut and mammary gland immune system. In conclusion, this study demonstrated the effects of dietary prebiotics on milk IgA production.

Effect of Orally Administered Non-ViableLactobacillusCells on Murine Humoral Immune Responses

BALB/c mice were immunized intraperitoneally with the food antigen ovalbumin (OVA) while they were fed with Lactobacillus GG heated killed cell preparation. The oral administration of Lactobacillus GG did not appear to modify the antigen-augmented serum IgE in the tested mice but significantly augmented serum OVA specific IgG in the tested mice fed with a diet containing 0.1% Lactobacillus GG as the non-viable cell preparation (P< 0.05). The fecal OVA specific IgA of the tested mice fed with nonviable Lactobacillus GG cells was also significantly elevated (P< 0.05) compared to those from OVA immunized mice. The spleen cells of mice fed with non-viable Lactobacillus GG cells secreted more IL-6 (P< 0.01). These results suggest that the non-viable Lactobacillus GG can augment the systemic and mucosal immune responses in a host animal favoring secretory IgA but not IgE in an adjuvant-like manner.

Gut microbiota and diabetes: from pathogenesis to therapeutic perspective

More than several hundreds of millions of people will be diabetic and obese over the next decades in front of which the actual therapeutic approaches aim at treating the consequences rather than causes of the impaired metabolism. This strategy is not efficient and new paradigms should be found. The wide analysis of the genome cannot predict or explain more than 10-20% of the disease, whereas changes in feeding and social behavior have certainly a major impact. However, the molecular mechanisms linking environmental factors and genetic susceptibility were so far not envisioned until the recent discovery of a hidden source of genomic diversity, i.e., the metagenome. More than 3 million genes from several hundreds of species constitute our intestinal microbiome. First key experiments have demonstrated that this biome can by itself transfer metabolic disease. The mechanisms are unknown but could be involved in the modulation of energy harvesting capacity by the host as well as the low-grade inflammation and the corresponding immune response on adipose tissue plasticity, hepatic steatosis, insulin resistance and even the secondary cardiovascular events. Secreted bacterial factors reach the circulating blood, and even full bacteria from intestinal microbiota can reach tissues where inflammation is triggered. The last 5 years have demonstrated that intestinal microbiota, at its molecular level, is a causal factor early in the development of the diseases. Nonetheless, much more need to be uncovered in order to identify first, new predictive biomarkers so that preventive strategies based on pre- and probiotics, and second, new therapeutic strategies against the cause rather than the consequence of hyperglycemia and body weight gain.

Effect of probiotics Lactobacillus acidophilus on Citrobacter rodentium colitis: the role of dendritic cells

Modulation of the intestinal immune response early in life by administration of probiotic bacteria may be an effective strategy for preventing or attenuating infectious diarrhea. We preinoculated the mice early in life with the probiotic bacteria Lactobacillus acidophilus NCFM (La) at age 2 wk. Dendritic cells (DCs) were collected and purified from mesenteric lymph nodes (MLN) and spleens of the BalbC/ByJ mice. DC isolation and adoptive transfer was used to examine the function of probiotics. We demonstrated that when mice were adoptively transferred with La-primed DCs (t-LaDC) instead of oral consumption with La, there was a similar effect on fecal bacteria counts, IgA levels, and colonic histopathology, as well as cytokine levels in MLN when there was intestinal bacterial infection. The above findings suggest that DCs play a key role in probiotics attenuating Citrobacter rodentium (Cr) colitis. Moreover, the location of La-primed DC hints that there is interaction of DCs and T cells in the digestive system of the host. Up-regulated expression of a surface marker on DCs indicated that inoculation with probiotics will stimulate the function of DCs, thereby further increasing immune response triggered by DC.

Inulin and oligofructose: review of experimental data on immune modulation

Diet modulates immune functions in different ways and affects host resistance to infections. In addition to the essential nutrients in food, nonessential food constituents such as nondigestible carbohydrates also affect the immune system. First results from human intervention studies suggest that the intake of inulin (IN) and oligofructose (OF) has beneficial effects on the gut-associated lymphoid tissue. At the level of the systemic immune system, however, only minor effects have been observed in healthy adult human subjects. In contrast, data from studies with infants suggest that supplementation with a prebiotic mixture positively affects postnatal immune development and increases fecal secretory IgA. Animal studies confirm the observations from human trials and give more insight into the immune tissue- specific effects of IN/OF. A clear outcome of the animal studies is that the intestinal immune system and especially the immune cells associated with the Peyer's patches are responsive to a dietary supplement of IN/OF and/or their metabolites. The mechanisms of IN/OF include indirect effects such as a shift in the composition of the intestinal flora and the enhanced production of immunoregulatory SCFA and perhaps other bacterial metabolites. Few data suggest direct effects of IN/OF via carbohydrate receptors on intestinal epithelial cells and immune cells. In conclusion, prebiotic IN/OF clearly modulate immunological processes at the level of the gut-associated lymphoid tissue, which may be associated with significant health benefits in infants and patients with intestinal inflammatory diseases.

The immune-enhancing effects of dietary fibres and prebiotics

The gastrointestinal tract is subjected to enormous and continual foreign antigenic stimuli from food and microbes. This organ must integrate complex interactions among diet, external pathogens, and local immunological and non-immunological processes. It is critical that protective immune responses are made to potential pathogens, while hypersensitivity reactions to dietary antigens are minimised. There is increasing evidence that fermentable dietary fibres and the newly described prebiotics can modulate various properties of the immune system, including those of the gut-associated lymphoid tissues (GALT). This paper reviews evidence for the immune-enhancing effects of dietary fibres. Changes in the intestinal microflora that occur with the consumption of prebiotic fibres may potentially mediate immune changes via: the direct contact of lactic acid bacteria or bacterial products (cell wall or cytoplasmic components) with immune cells in the intestine; the production of short-chain fatty acids from fibre fermentation; or by changes in mucin production. Although further work is needed to better define the changes, mechanisms for immunomodulation, and the ultimate impact on immune health, there is convincing preliminary data to suggest that the consumption of prebiotics can modulate immune parameters in GALT, secondary lymphoid tissues and peripheral circulation. Future protocols on the physiological impact of consuming prebiotics should be designed to include assessments of the gut microflora, gut physiology and the function and composition of the various regions of GALT.

Oral treatment with probiotic Lactobacillus johnsonii NCC533 (La1) for a specific part of the weaning period prevents the development of atopic dermatitis induced after maturation in model mice, NC/Nga

BACKGROUND

The inhibitory effect of probiotic bacteria on atopic dermatitis has been shown in human infants, but the mechanism is still unclear.

OBJECTIVE

This study aimed to show the effects of the administration of a probiotic during the weaning period in mouse models on production of the intestinal secretory IgA (sIgA) and on the development of atopic dermatitis (AD) in later life.

METHODS

The effects of the administration of Lactobacillus johnsonii NCC533 (La1) during weaning were evaluated using a mouse model (Balb/c). The weaning period of mice was divided into three phases according to the evolution of faecal IgA. La1 was administered in each phase and the evolution of the faecal IgA was estimated. In the next experiment, the effect of the administration of La1 in phase 2 on host immunity after maturation was further assessed by using the model NC/Nga mouse for human AD.

RESULTS

Administration of La1 in each phase showed a distinct effect on the production of sIgA. But sIgA production was only positively stimulated when La1 was administrated in phase 2. The development of AD induced by mite antigen from 6 weeks old was significantly prevented by the primary administration of La1 in phase 2. AD-like lesions were significantly milder than those of the control mice, and histological observations showed an almost normal appearance of the epidermis and upper dermis of the mice treated with La1.

CONCLUSION

This study suggested that the primary administration of La1 in a specific part of the weaning period is effective in preventing or inhibiting the development of AD after maturation by modulating or accelerating the gut immune response.

Do probiotics have a therapeutic role in gastroenterology?

Several hundred species of bacteria inhabit the gut, and affect its cell biology, morphology and homeostasis. Many bacteria are however potential pathogens, especially if the integrity of the epithelial barrier is physically or functionally breached. Conversely, the interaction between host and commensal microbes can confer important health benefits. This has led to commercial and public interest in 'probiotics', live microbes principally taken as food supplements. Might probiotics also be used in disease therapy Experimental evidence that probiotics modulate gut physiology, particularly barrier integrity and immunological function, underpins exciting new gastroenterological research. We discuss below the scientific basis for probiotic effects and present a critical perspective for their use in relation to gastrointestinal disease.

Immunomodulating potential of supplementation with probiotics: a dose–response study in healthy young adults

Certain probiotic microorganisms have been found beneficial in the treatment of immune-related diseases and may also affect immune function in healthy people. Intervention studies of probiotics in healthy humans are urgently required. Here, the immunomodulating potential of Bifidobacterium animalis ssp. lactis (BB-12) and Lactobacillus paracasei ssp. paracasei (CRL-431) was studied in a double-blind placebo-controlled parallel dose-response trial (n=71) based on five randomly assigned groups of young healthy adults supplemented for 3 weeks with 0, 10(8), 10(9), 10(10) and 10(11) CFU day(-1), respectively, of a mixture of BB-12 and CRL-431. No statistically significant dose-dependent effect was found for phagocytic activity in blood leukocytes, fecal immunoglobulin A (IgA) concentrations or production of interferon-gamma and interleukin-10 in blood cells. When evaluating data according to the amount of viable BB-12 recovered from faeces, the interferon-gamma production in blood cells was significantly reduced. In conclusion, no solid effect on the immune function of young healthy adults supplemented with even high doses of B. animalis ssp. lactis BB-12 and L. paracasei ssp. paracasei CRL-431 was demonstrated in this study.

Protective role of supplement with foreign Bifidobacterium and Lactobacillus in experimental hepatic ischemia-reperfusion injury

BACKGROUND AND AIM

Intestinal microflora play a crucial role in some severe liver diseases. The purpose of this study was to evaluate the effects of a Lactobacillus strain and a Bifidobacterium strain on ischemia-reperfusion (I/R) liver injury.

METHODS

Rats were divided into six groups. Each group received either Bifidobacterium Catenulatum ZYB0401; Lactobacillus Fermentum ZYL0401; a mixture of these two bacterial strains; gentamicin; or saline by daily gavage for 7 days. On the sixth day, all rats, except those in the control group, were subjected to 20 min of liver ischemia. After 22 h of hepatic reperfusion, liver enzymes and histology, malondialdehyde (MDA), superoxide dismutase (SOD), endotoxemia, serum tumor necrosis factor-alpha (TNF-alpha), intestinal bacteria, intestinal mucosal ultrastructure, and bacterial translocation were studied.

RESULTS

All administered bacteria increased intestinal Bifidobacterium and Lactobacillus, decreased endotoxemia (P < 0.01), alanine aminotransferase (ALT) (P < 0.01), and markedly ameliorated liver histology and intestinal mucosal ultrastructure. Only rats treated with Bifidobacterium Catenulatum ZYB0401 and Lactobacillus Fermentum ZYL0401 showed reduced incidence of bacterial translocation to the kidney (P < 0.05), associated with decreased serum TNF-alpha and liver MDA (P < 0.05) and increased liver SOD (P < 0.05) compared to the I/R group. Gentamicin decreased almost all kinds of intestinal bacteria (P < 0.01) and decreased ALT (P < 0.01) and serum TNF-alpha, but failed to reduce both endotoxemia and the incidence of bacterial translocation and had no effects on liver MDA and SOD.

CONCLUSION

Bifidobacterium Catenulatum ZYB0401 in combination with Lactobacillus Fermentum ZYL0401 could be useful in restoring intestinal microflora and in preventing liver injury in hepatic I/R of rats.

Preinoculation with the probiotic Lactobacillus acidophilus early in life effectively inhibits murine Citrobacter rodentium colitis

Enteropathogenic Escherichia coli (EPEC) is a common pathogen in infantile diarrhea, causing a characteristic histopathologic attaching and effacing (A/E) lesion in the intestinal mucosa. The mouse pathogen Citrobacter rodentium causes a similar A/E lesion in the murine intestine. Like EPEC, C. rodentium infection results in colonic crypt hyperplasia, goblet cell depletion, epithelial proliferation, and mucosal disruption. Using this murine model, we tested the hypothesis that preinoculation of murine gut with Lactobacillus acidophilus early in life can enhance host defense against enteric bacterial infection and attenuate bacteria-mediated colitis. Two-week old BALB/c mice were inoculated with L. acidophilus twice per week for 4 weeks before C. rodentium infection or concomitantly with the exposure to C. rodentium at 6-8 weeks of age. The probiotics were administered twice weekly thereafter. We observed that L. acidophilus inoculation in mice inhibits C. rodentium-induced colitis, which is associated with a decrease in C. rodentium colonization and translocation, an increase in its clearance, and a suppression of colonic myeloperoxidase (MPO) activity. Probiotic treatment also stimulates regulatory cytokine expression in the colon [transforming growth factor beta (TGF-beta), interleukin (IL)-10]. Preinoculation with L. acidophilus is more effective than concomitant use of probiotics in the induction of intestinal IgA secretion and in the downregulation of proinflammatory cytokine expression [tumor necrosis factor alpha (TNF-alpha), IL-6, and IL-12]. These observations suggest that inoculation with probiotics can effectively prevent bacteria-induced colitis by limiting enteric bacteria infection and promoting mucosal protective regulatory immune responses. This study may have ramifications for prevention of infectious diarrhea in human infants and children, particularly in developing countries.

Separation of growth-stimulating peptides for Bifidobacterium from soybean conglycinin

AIM

To isolate and identify the soybean conglycinin peptides that selectively stimulates the growth of bifidobacteria in vitro, and to investigate the effect of soybean conglycinin peptides on intestinal ecosystem in vivo.

METHODS

Soybean conglycinin was purified from soybean seeds by gel filtration (Sepharose-CL-6B). These proteins were submitted to hydrolysis by pepsin. Several growth-stimulating peptides for bifidobacteria were isolated chromatographically from pepsin hydrolysis of soybean conglycinin and identified by means of matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF-MS). Parallel to in vitro study, in vivo experiments with soybean conglycinin peptides were performed in mice. Ninety male KM mice were randomly assigned into five groups of 16 mice each, and each group was administered for 21d intragastrically with physiological saline (control), conglycinin, pepsin-treated conglycinin (PTC), the most active fraction which isolated from pepsin-treated conglycinin (P2-PTC) and HCl-full hydrolysis of conglycinin (HCl-FHC), respectively. Intestinal microflora were evaluated by standard microbiologic methods and biochemical assays of cecal content samples after treatment.

RESULTS

The results showed that the peptides which were isolated from soybean conglycinin could stimulate the growth of bifidobacteria in vitro, and the molecular mass of purified peptides with MALDI-TOF-MS ranged from 693.32 to 1829.55. Compared with control group, in vivo experiments showed that P2-PTC group decreased cecal pH (7.08+/-0.08 vs 7.21+/-0.09, P<0.05) and enterococci counts (5.38+/-0.26 log10CFU/g vs 5.78+/-0.19 log10CFU/g, P<0.05), significantly increased sIgA level (172.08+/-35.40 ng/g vs 118.27+/-33.93 ng/g, P<0.01) and beta-galactosidase activity (1.28+/-0.23 U/g vs 1.82+/-0.58 U/g, P<0.05).

CONCLUSION

The results have shown that conglycinin is good source for enzyme-mediated production of peptides which stimulate the growth of bifidobacteria. These peptides are inactive within the sequence of the parent protein but can be released during enzymatic hydrolysis, and in vivo experiments demonstrate that conglycinin peptides may be beneficial for improving gastrointestinal health.

Effect of Probiotic Supplementation on Bacterial Translocation in Thermal Injury

PURPOSE

To examine the effects of probiotic supplementation and enteral solutions containing glutamine and arginine on bacterial translocation (BT) and intestinal villous atrophy in thermal injury.

METHODS

Forty male Sprague-Dawley rats weighing 200-250 g were divided into four groups of ten. Group 1 served as control group without thermal injury and was fed standard chow. Thermal injury was inflicted as a 30% scald burn in the other three groups. Group 2 was fed standard chow and group 3 was fed standard chow supplemented with a probiotic (Acidophilus plus) containing Bifidobacterium bifidum, Lactobacillus acidophilus, and Lactobacillus bulgaricus (2 x 10(9) CFU/day) via an orogastric tube. Group 4 was fed only an enteral diet (Stresson multifiber) containing glutamine, arginine, and medium chain triglyceride, at 1 g/kg per day amino acid and 230 kcal/kg, for 7 days before thermal injury. All the animals were killed 24 h after thermal injury, and ileal segments were resected and examined histopathologically. To evaluate BT, samples from blood, mesenteric lymph nodes, and cecal content were cultured under aerobic and anaerobic conditions. Terminal ileum specimens were histologically examined to evaluate mucosal integrity.

RESULTS

Significantly less BT was seen in groups 3 and 4 than in group 2 (P < 0.001). No significant difference was found between groups 3 and 4. Histological evaluation showed significant reduction in villous atrophy in groups 3 and 4.

CONCLUSION

Probiotic supplementation seems to reduce bacterial translocation and decrease intestinal mucosal atrophy in rats with thermal injury, as do enteral solutions with arginine and glutamine.

Inulin, oligofructose and immunomodulation

Diet is known to modulate immune functions in multiple ways and to affect host resistance to infections. Besides the essential nutrients, non-essential food constituents such as non-digestible carbohydrates may also have an impact on the immune system, especially in the area of the gut-associated lymphoid tissue (GALT). Recent data now provide first evidence that prebiotics such as inulin/oligofructose (IN/OF) modulate functions of the immune system. In animal studies IN/OF primarily activated immune cells in Peyer's patches including IL-10 production and natural killer (NK) cell cytotoxicity. Other immune functions modulated by IN/OF included the concentration of secretory IgA in ileum and caecum, splenic NK cell cytotoxicity as well as splenocyte cytokine production. In different tumour models, a lower incidence of tumours was observed, which in the case of colonic tumours was associated with enhanced NK cell cytotoxicity in the GALT. Few human studies so far have investigated the effects of IN/OF alone or in combination with other dietary supplements on immunocompetence. Supplementation of IN/OF resulted in minor changes of systemic immune functions such as decrease in phagocytic activity. No data are available on the effects of IN/OF on the GALT in man. The mechanisms of the reported effects of IN/OF on the immune system are currently investigated and include: (i) direct effects of lactic acid-producing bacteria or bacterial constituents on immune cells; (ii) the production of SCFA and binding to SCFA receptors on leucocytes. In conclusion, the current data suggest that IN/OF primarily modulate immune parameters in the GALT, but splenocytes are also activated by IN/OF. Human studies are needed to find out whether IN/OF have the potential to modulate systemic immunity in well-nourished individuals and to lower the risk of diseases such as colon cancer.

Probiotics in the treatment of atopic eczema/dermatitis syndrome in infants: a double-blind placebo-controlled trial

BACKGROUND

Probiotic bacteria are suggested to reduce symptoms of the atopic eczema/dermatitis syndrome (AEDS) in food-allergic infants. We aimed to investigate whether probiotic bacteria have any beneficial effect on AEDS.

METHODS

Follow-up of severity of AEDS by the Severity Scoring of Atopic Dermatitis (SCORAD) index in 230 infants with suspected cow's milk allergy (CMA) receiving, in a randomized double-blinded manner, concomitant with elimination diet and skin treatment, Lactobacillus GG (LGG), a mixture of four probiotic strains, or placebo for 4 weeks. Four weeks after the treatment, CMA was diagnosed with a double-blind placebo-controlled (DBPC) milk challenge in 120 infants.

RESULTS

In the whole group, mean SCORAD (at baseline 32.5) decreased by 65%, but with no differences between treatment groups immediately or 4 weeks after the treatment. No treatment differences were observed in infants with CMA either. In IgE-sensitized infants, however, the LGG group showed a greater reduction in SCORAD than did the placebo group, -26.1 vs-19.8 (P=0.036), from baseline to 4 weeks after the treatment. Exclusion of infants who had received antibiotics during the study reinforced the findings in the IgE-sensitized subgroup.

CONCLUSION

Treatment with LGG may alleviate AEDS symptoms in IgE-sensitized infants but not in non-IgE-sensitized infants.

Probiotics: what are they? What are their effects on gut physiology?

Probiotics can be defined as microbial cells that have a beneficial effect on the health and well-being of the host. Since the gastrointestinal mucosa is the surface of contact with probiotics, it seems evident that the first effects of probiotics relate to digestive function. A brief review of the literature indicates that probiotics have very few effects on the main physiological functions of the gastrointestinal tract, which are digestion, absorption and propulsion. The main action of probiotics can be summarised as a reinforcement of the intestinal mucosal barrier against deleterious agents. Experimental data indicate that some probiotics reduce pathological alterations in paracellular permeability to large molecules or bacteria, stimulate mucosal immunity, display a trophic action on the mucosa, reduce mucus degradation and interact with mediators of inflammation. Yoghurt may help lactose digestion, and some data needing confirmation indicate a stimulation of water absorption and an acceleration of intestinal transit by some bacteria.

Screening of Bifidobacterium strains isolated from human faeces for antagonistic activities against potentially bacterial pathogens

As probiotic bacteria, strains belonging to the genus Bifidobacterium colonise the gastro-intestinal tract of humans and animals at the time of birth, and they are found in young as well as in adult individuals in great numbers. Moreover, they can interact with the development of enteric infections by the production of antimicrobial metabolites. In this work 281 strains of bifidobacteria were anaerobically isolated from human faecal samples, supplied by volunteers of different ages (youngs, adults, elders), and preliminarly described by microscopic observation. All strains were screened by the fructose 6-phosphate phosphoketolase (F6PPK) test in order to confirm their classification within the genus Bifidobacterium. Selected strains were used to evaluate their antagonistic activities against Escherichia coli, Salmonella thyphimurium, Staphylococcus lentus, Enterococcus faecalis, Acinetobacter calcoaceticus, Sphingomonas paucimobilis, Listeria monocytogenes, Yersinia enterocolitica, Bacillus cereus, Clostridium sporogenes. Experiments were performed in vitro by different methods based on the observation of growth inhibition in Petri dishes. The strains that showed the highest inhibiting activities were compared by SDS-PAGE for total cell proteins, using type strains of human origin as references. Representative isolates were metabolically characterised by the BIOLOG system; a specific database was created with strains obtained from our collection and a statistical evaluation for metabolic patterns was carried out.

Influence of fructooligosaccharides on Peyer's patch lymphocyte numbers in healthy and endotoxemic mice

OBJECTIVE

The purpose of this study was to determine whether fructooligosaccharides (FOS) exert an immunomodulating effect on Peyer's patches (PP), the main inductive site of the intestinal immune system. We investigated the effects of FOS in healthy and endotoxemic animals.

METHODS

Six-week-old female Balb/c mice were fed a control diet or a diet supplemented with 10% FOS over a period of 16 d. To induce endotoxemia, mice were challenged intraperitoneally with lipopolysaccharide (LPS) on day 15. PP were excised from mice, and lymphocyte subpopulations (B lymphocytes, T lymphocytes, CD4(+) cells, and CD8(+) cells) were determined by flow cytometry.

RESULTS

The FOS-enriched diet increased the total cell yield in healthy and endotoxemic mice (P < 0.001). Similarly, B lymphocytes were increased in both groups (P < 0.001). In contrast, T lymphocytes were unaltered in healthy mice but increased in LPS-challenged mice after FOS enrichment (P < 0.001). In endotoxemic mice but not in control animals, the increase of CD4(+) cells (P < 0.001) was more pronounced than that of CD8(+) cells (P < 0.001), thus increasing the CD4:CD8 ratio (P < 0.01).

CONCLUSION

FOS showed an immunostimulating effect on PP lymphocytes under healthy and endotoxemic conditions. Thus it can be concluded that FOS administration affects not only the large intestine but also the main inductive part of the mucosal immune system in the small intestine.

Probiotics: potential pharmaceutical applications

Realisation of the importance of human gut microbiota in health restoration and maintenance has kindled an interest in probiotics. Probiotics are defined as the microbial food supplements, which beneficially affect the host by improving its intestinal microbial balance. Probiotics are the health enhancing functional food ingredients used therapeutically to prevent diarrhea, improve lactose tolerance and modulate immunity. They may also have potential to prevent cancer and lower serum cholesterol levels. Lactobacillus, Bifidobacterium and several other microbial species are perceived to exert such effects by changing the composition of the gut microbiota. However, it is important that exogenously administered bacteria reach and establish themselves in the large intestine in an intact form. The use of non-digestible oligosaccharides ('prebiotics') can fortify intestinal microflora and stimulate their growth. The present review encompasses information regarding the probiotics and their proposed uses. It addresses the concepts of prebiotics and synbiotics, the application of genetic engineering to produce newer probiotics. Finally, the list of commercially available products are reviewed with discussion of questions regarding the reliability, utility and the safety of these products.

Antitumor activity of milk kefir and soy milk kefir in tumor-bearing mice

The effects of oral administration of milk and soy milk kefirs on tumor growth in tumor-bearing mice and the mucosal immunoglobulin A response in mice were studied. Oral administration of milk and soy milk kefirs to mice inoculated with sarcoma 180 tumor cells resulted in 64.8% and 70.9% inhibition of tumor growth, respectively, compared with controls. In addition, oral administration of the two kefir types induced apoptotic tumor cell lysis. Total immunoglobulin A levels for tissue extracts from the wall of the small intestine were also significantly higher for mice fed a milk kefir or a soy milk kefir regimen for 30 days. These results suggest that milk and soy milk kefirs may be considered among the more promising food components in terms of cancer prevention and enhancement of mucosal resistance to gastrointestinal infection.