Probiotics as modulators of the gut flora

Managing gut health through nutrition

1. To study gut health, a multi-pronged approach is necessary. It should be considered from the point of view of immunology, microbiology and nutrient supply. 2. The impact on gut health often comes from microbial imbalance in the gut, which will be exacerbated if antibiotics are withdrawn from feed. 3. Any gut damage caused by pathogens will lead to poor gut health, which will, in turn, affect nutrient utilisation efficiency. Subclinical forms of infection with no obvious signs of lesions are often financially more devastating than acute, short-term infections. Necrotic enteritis in poultry is one such example. 4. Dietary factors that modulate the immune system and gut microflora should be considered when formulating diets and managing feeding practices.

Effect of a low dose of dietary resveratrol on colon microbiota, inflammation and tissue damage in a DSS-induced colitis rat model

The naturally occurring polyphenol resveratrol has been acknowledged with health-beneficial properties. Most of the studies dealing with its in vivo effects assay huge doses, not representative from a dietary point of view. Our aim was to ascertain whether resveratrol can exert anti-inflammatory activity in vivo at an attainable dietary dose. Rats were fed with 1 mg of resveratrol/kg/day (a human equivalent dose) for 25 days, and in the last 5 days, 5% dextran sulfate sodium (DSS) was administered to induce colitis. Effects on colon tissue damage, gut microbiota, reactive oxygen species, inflammatory markers and nitric oxide production as well as gene expression profile with microarrays were evaluated. Resveratrol increased lactobacilli and bifidobacteria as well as diminished the increase of enterobacteria upon DSS treatment. Resveratrol significantly protected the colonic mucosa architecture, reduced body weight loss, diminished the induced anemia and reduced systemic inflammation markers, colonic mucosa prostaglandin E(2), cycloxygenase-2, prostaglandin E synthase and nitric oxide levels. In addition, the expression of 2,655 genes in distal colon mucosa related to important pathways was varied. These results reinforce the concept of resveratrol as a dietary beneficial compound in intestinal inflammation at doses possibly attainable with resveratrol-enriched nutraceuticals.

Role of gut microbiota in early infant development

Early colonization of the infant gastrointestinal tract is crucial for the overall health of the infant, and establishment and maintenance of non-pathogenic intestinal microbiota may reduce several neonatal inflammatory conditions. Much effort has therefore been devoted to manipulation of the composition of the microbiota through 1) the role of early infant nutrition, particularly breast milk, and supplementation of infant formula with prebiotics that positively influence the enteric microbiota by selectively promoting growth of beneficial bacteria and 2) oral administration of probiotic bacteria which when administered in adequate amounts confer a health benefit on the host. While the complex microbiota of the adult is difficult to change in the long-term, there is greater impact of the diet on infant microbiota as this is not as stable as in adults. Decreasing excessive use of antibiotics and increasing the use of pre- and probiotics have shown to be beneficial in the prevention of several important infant diseases such as necrotizing enterocolitis and atopic eczema as well as improvement of short and long-term health. This review addresses how the composition of the gut microbiota becomes established in early life, its relevance to infant health, and dietary means by which it can be manipulated.

The immunomodulatory effect of lactulose on Enterococcus faecium fed preruminant calves

Prebiotics and probiotics could represent an effective alternative to the use of synthetic antibiotics in nutrition. The mechanisms by which prebiotics affect the immune system have not yet been investigated in detail. Most effects have been attributed to increases in the innate and acquired immune responses. This study was conducted to elucidate the long-term effects of orally administered lactulose on the immune response in the intestinal tract of probiotic-fed calves. Preruminant calves were randomized to 3 feeding groups: milk replacer containing 1) no lactulose, 2) 1% lactulose, or 3) 3% lactulose. All 3 milk replacers contained 10(9) cfu Enterococcus faecium/kg. Messenger RNA expression of different cell activation markers, pro- and antiinflammatory cytokines, and IgA Fc receptor was investigated in the ileum, mesenterial lymph node, spleen, and white blood cells. A significantly greater number of blood lymphocytes were detected in the 3% lactulose group (P = 0.02) than in the control group. The expression results in male calves indicated that the transcription of IgA Fc receptor in the ileal mucosa of the 1% lactulose treatment group increased significantly (P = 0.04) and also tended to increase in the 3% lactulose group (P = 0.07). Furthermore, decreases in IL-10 and interferon-gamma mRNA expression were observed in the ileum (P = 0.04). The CD4-presenting lymphocytes were decreased significantly in the ileum (P = 0.04) and mesenteric lymph node (P = 0.01), whereas CD8-presenting lymphocytes were increased in the blood (P = 0.03) of females. Other proinflammatory cytokines (IL-1beta, IL-8, and tumor necrosis factor-alpha) and antiinflammatory cytokines (transforming growth factor-beta1) did not show significant differences in mRNA expression among treatment groups. The results indicate that additional lactulose feeding had an immunomodulatory effect on the composition of T-cell subsets in different immune compartments and had minor effects on pro- and antiinflammatory cytokine mRNA expression.

Update on irritable bowel syndrome and gender differences

Irritable bowel syndrome (IBS) is a chronic functional GI disorder characterized by abdominal pain associated with alterations in defecation or stool frequency and consistency. In Western industrialized countries, women seek health care services for their symptoms more frequently than men. The cause of IBS is likely multifactorial involving altered motility, visceral hypersensitivity, and dysregulation of the autonomic nervous system. Many patients note that their symptoms are exacerbated by diet and stress, and women frequently report menstrual cycle fluctuations in symptoms. Current approaches to IBS management include behavioral management therapies such as dietary intake changes and stress reduction cognitive restructuring. Drug therapies are targeted at altering pain sensitivity, motility, and secretion. This review provides an overview of the pathogenesis of IBS, factors that contribute to gender differences, and current therapeutic approaches for symptom management.

Probiotics and blueberry attenuate the severity of dextran sulfate sodium (DSS)-induced colitis

We studied the anti-inflammatory properties of probiotic strains and blueberry in a colitis model. The disease activity index (DAI) was significantly lower on days 9 and 10 in all groups compared to the colitis control. Myeloperoxidase (MPO) and bacterial translocation to the liver and to the mesenteric lymph nodes (MLN) decreased significantly in all groups compared to colitis control. Cecal Enterobacteriaceae count decreased significantly in blueberry with and without probiotics compared to the other groups. Lactobacillus plantarum reisolated from the cecal content in the presence of blueberry, contrary to Lactobacillus fermentum. Colonic MDA decreased significantly in all groups, except the L. fermentum group, compared to the colitis control. The cecal concentration of acetic, propionic, and butyricbutyric acid was significantly higher in the L. plantarum group, while the L. fermentum group yielded the highest concentration of lactic acid compared with all other groups. Lactobacillus plantarum DSM 15313, Lactobacillus fermentum 35D, and blueberry alone and in combination improve the DAI, reduce bacterial translocation, and reduce inflammation.

Interaction of probiotic Lactobacillus and Bifidobacterium strains with human intestinal epithelial cells: adhesion properties, competition against enteropathogens and modulation of IL-8 production

The human intestinal microbiota plays a pivotal role in human nutrition and health by promoting the supply of nutrients, preventing pathogen colonization and shaping and maintaining normal mucosal immunity. The depletion of the individual microbiota can result in a higher susceptibility to enteropathogenic bacteria infection. In order to reduce this risk, the use of food supplements containing probiotic bacteria has been recently addressed. In this paper, we investigate the protective role toward enteropathogen infection of probiotic strains belonging to Lactobacillus and Bifidobacterium. According to our experimental data, Lactobacillus acidophilus Bar13, L. plantarum Bar10, Bifidobacterium longum Bar33 and B. lactis Bar30 were effective in displacing the enteropathogens Salmonella typhimurium and Escherichia coli H10407 from a Caco-2 cell layer. Moreover, L. acidophilus Bar13 and B. longum Bar33 have been assessed for their immunomodulatory activity on IL-8 production by HT29 cells. Both strains showed the potential to protect enterocytes from an acute inflammatory response. These probiotic strains are potential candidates for the development of new functional foods helpful in counteracting enteropathogen infections.

Gut immune stimulation by non pathogenic Gram(+) and Gram(-) bacteria. Comparison with a probiotic strain

We analyzed the gut immune stimulation induced by Gram-positive bacteria: non probiotic Lactobacillus acidophilus CRL 1462 and Lactobacillus acidophilus A9; two potentially probiotic strains: L. acidophilus CRL 924 and Lactobacillusdelbrueckii subsp. bulgaricus CRL 423; comparatively with a probiotic strain: Lactobacillus casei CRL 431. We also studied Gram-negative bacteria: Escherichia coli 129 and E. coli 13-7 in BALB/c mice. All the strains increased the number of IgA+ cells. We analyzed the cytokines IFNgamma, TNFalpha, IL-17, IL-12, IL-6 and MIP-1alpha. The Gram(+) strains increased the number of IL-10+ cells. Gram(-) strains did not increase IL-10+ cells, but they increased the number of IL-12+ cells. The probiotic strain increased mainly IFNgamma and TNFalpha. In the study of the receptors TLR-2, TLR-4 and CD-206, we demonstrated that only the probiotic strain increased the number of CD-206+ cells. All the Gram(+) strains increased the number of TLR-2+ cells and the Gram(-) strains of the TLR-4+ cells. The probiotic strain induced the release of IL-6 by a preparation enriched in intestinal epithelial cells (IEC). Gram(+) and Gram(-) bacteria activated different immune receptors and induced a different cytokine profile. The probiotic strain showed a great activity on the immune cells and the enriched population in IEC, activating mainly cells of the innate immune system.

Probiotics and oral health effects in children

BACKGROUND

Probiotics are living micro-organisms added to food which beneficially affect the host by improving its intestinal microbial balance.

OBJECTIVE

This paper aims to present a general background on probiotics and its health effects in children, and to examine the evidence for oral colonization and the possible impact on oral health in children and young adults.

METHODS

For delivery and general health effects, recent systematic reviews, meta-analyses, and other relevant papers were used. Concerning oral installation and oral effects, a broad search for publications in English was conducted through February 2007 in PubMed. Studies describing an installation or intervention trial in humans with a controlled design and an oral endpoint measure were considered. Fourteen papers with dental focus were identified, of which two were narrative reviews.

RESULTS

Only one study of dental interest was conducted in children. Four papers dealt with oral installation of probiotic bacteria, and although detectable levels were found in saliva shortly after intake, the studies failed to demonstrate a long-term installation. Seven papers evaluated the effect of lactobacilli- or bifidobacteria-derived probiotics on the salivary levels of caries-associated bacteria in placebo-controlled designs. All but one reported a hampering effect on mutans streptococci and/or yeast. The single study carried out in early childhood reported a significant caries reduction in 3- to 4-year-old children after 7 months of daily consumption of probiotic milk.

CONCLUSION

Bacteriotheraphy in the form of probiotic bacteria with an inhibitory effect on oral pathogens is a promising concept, especially in childhood, but this may not necessarily lead to improved oral health. Further placebo controlled trials that assess carefully selected and defined probiotic strains using standardized outcomes are needed before any clinical recommendations can be made.

Splenda alters gut microflora and increases intestinal p-glycoprotein and cytochrome p-450 in male rats

Splenda is comprised of the high-potency artificial sweetener sucralose (1.1%) and the fillers maltodextrin and glucose. Splenda was administered by oral gavage at 100, 300, 500, or 1000 mg/kg to male Sprague-Dawley rats for 12-wk, during which fecal samples were collected weekly for bacterial analysis and measurement of fecal pH. After 12-wk, half of the animals from each treatment group were sacrificed to determine the intestinal expression of the membrane efflux transporter P-glycoprotein (P-gp) and the cytochrome P-450 (CYP) metabolism system by Western blot. The remaining animals were allowed to recover for an additional 12-wk, and further assessments of fecal microflora, fecal pH, and expression of P-gp and CYP were determined. At the end of the 12-wk treatment period, the numbers of total anaerobes, bifidobacteria, lactobacilli, Bacteroides, clostridia, and total aerobic bacteria were significantly decreased; however, there was no significant treatment effect on enterobacteria. Splenda also increased fecal pH and enhanced the expression of P-gp by 2.43-fold, CYP3A4 by 2.51-fold, and CYP2D1 by 3.49-fold. Following the 12-wk recovery period, only the total anaerobes and bifidobacteria remained significantly depressed, whereas pH values, P-gp, and CYP3A4 and CYP2D1 remained elevated. These changes occurred at Splenda dosages that contained sucralose at 1.1-11 mg/kg (the US FDA Acceptable Daily Intake for sucralose is 5 mg/kg). Evidence indicates that a 12-wk administration of Splenda exerted numerous adverse effects, including (1) reduction in beneficial fecal microflora, (2) increased fecal pH, and (3) enhanced expression levels of P-gp, CYP3A4, and CYP2D1, which are known to limit the bioavailability of orally administered drugs.

The effect of probiotics on gut flora, level of endotoxin and Child-Pugh score in cirrhotic patients: results of a double-blind randomized study

OBJECTIVE

To determine the effect of Escherichia coli Nissle (Mutaflor, Ardeypharm GmbH, Herdecke, Germany) on the intestinal colonization, level of endotoxin and liver functions in patients with liver cirrhosis.

METHODS

Thirty-nine patients with liver cirrhosis diagnosed by means of biopsy and clinical examinations were randomly allocated to treatment with E. coli Nissle or placebo for 42 days. Standard clinical examination, biochemical and hematological examinations, level of endotoxin and microbiological examination of the stool were performed before and after the treatment.

RESULTS

In comparing the treatment of E. coli Nissle and placebo, significant improvement of the intestinal colonization (P<0.001) in the E. coli Nissle group was described. We found a trend of significant lowering of the endotoxemia (P=0.07) and improvement of liver functions evaluated by Child-Pugh score (P=0.06).

CONCLUSION

E. coli Nissle seems to be effective in the restoration of normal colonic colonization and can probably lower endotoxemia in cirrhotic patients.

Probiotics and prebiotics in infant nutrition

The human colonic microflora has a central role in health and disease, being unique in its complexity and range of functions. As such, dietary modulation is important for improved gut health, especially during the highly-sensitive stage of infancy. Diet can affect the composition of the gut microflora through the availability of different substrates for bacterial fermentation. Differences in gut microflora composition and incidence of infection exist between breast-fed and formula-fed infants, with the former thought to have improved protection. Historically, this improvement has been believed to be a result of the higher presence of reportedly-beneficial genera such as the bifidobacteria. As such, functional food ingredients such as prebiotics and probiotics could effect a beneficial modification in the composition and activities of gut microflora of infants by increasing positive flora components. The prebiotic approach aims to increase resident bacteria that are considered to be beneficial for human health, e.g. bifidobacteria and lactobacilli, while probiotics advocates the use of the live micro-organisms themselves in the diet. Both approaches have found their way into infant formula feeds and aim to more closely simulate the gut microbiota composition seen during breast-feeding.

Effect of prebiotic supplementation on a probiotic bacteria mixture: comparison between a rat model and clinical trials

The effects of a probiotic mixture (PRO), supplemented with either galacto-oligosaccharide (GOS) or polydextrose (PDX), on cell numbers of lactic acid bacteria (LAB) and bifidobacteria (BIF) were studied in conventional rats and healthy human subjects. In rats the baseline BIF cell numbers were below the detection limit and were increased by the 2-week GOSPRO intervention. In contrast baseline LAB numbers in rats were high and not affected by the treatments. The human study consisted of two independent but concurrent trials; both started with PRO followed by GOSPRO or PDXPRO periods. In the human subjects variation in numbers of BIF and LAB were high. The GOSPRO group exhibited high counts of faecal LAB and BIF at the start and showed little or no effects of the interventions. In contrast, the PDX group had low faecal LAB and BIF numbers at the start and clearly increased cell numbers of BIF after the PDXPRO period, and LAB after the PRO and PDXPRO period, compared with the run-in period. We propose here that responses to pro- and prebiotics are dependent on baseline numbers of LAB and/or BIF, and that the conventional rat model does not predict well the treatment responses in humans. The survival of PRO was presumably enhanced by the use of prebiotic supplementation and advocates the use of particular combinations of pro- and prebiotics.

Maintenance therapy for ulcerative colitis has no impact on changes in the extent of ulcerative colitis

BACKGROUND AND AIM

Although the efficacy of maintenance remission therapy in ulcerative colitis (UC) has been proved in many studies, little is known about its possible effect on the extent of the disease. The aim of the present multicenter Belgian study was to evaluate the potential role of UC maintenance therapy on the colonic extension of the disease.

MATERIALS AND METHODS

A total of 98 patients, 56 males, 42 females, mean age 52 years, range 22-82 years, from 12 medical centers in Belgium, with an acute exacerbation of well-established, endoscopically and histologically proven left-sided UC, were included. The colonic extension was endoscopically determined at the time of the initial diagnosis and at the actual flare-up. The mean duration of UC was 93+72 months, median was 84 months, and range was 3-372 months. Active smoking was reported in only 7% of patients, while the majority were no-smokers (63%) or ex-smokers (30%). The median colonic extension at the time of initial diagnosis was 25 cm, range 2-70 cm from the anal merge. Sixty-six percent of the patients had quiescent disease without flare-ups during last year. The χ(2)-test was used for statistical analysis.

RESULTS

29/98 (29.6%) patients had not used any maintenance therapy in the last 3 months before the actual exacerbation. The most commonly used maintenance therapy was 5-ASA (43%), while combined therapy with 5-ASA, corticosteroids or immunosuppresives (mainly azathioprine) in all possible combinations was reported by 29.6% of patients. The extent of UC had not changed in 50.7% and 51.7% of patients, respectively, with and without maintaining therapy (NS, p=0.99). Some degree of regression was observed in, respectively, 21.7% and 20.7% (NS, p=0.99), and some degree of extension in, respectively, 27.5% and 27.6% (NS, p=0.99). Furthermore, no relationship was found between changes in colonic extent and type of maintaining therapy, smoking habits or disease activity during the last year before the acute exacerbation. A tendency of beneficial effect of maintenance therapy on disease extent was observed in patients with continuous active disease of short duration.

CONCLUSIONS

According to this multicenter study, maintenance remission therapy for left-sided UC was not found to have a statistically significant effect on colonic extension. Further long-term studies are necessary to confirm these results.

Effect of chewing gums containing xylitol or probiotic bacteria on salivary mutans streptococci and lactobacilli

The aim was to evaluate the effect of xylitol and probiotic chewing gums on salivary mutans streptococci (MS) and lactobacilli (LB). The material consisted of 80 healthy young adults (21-24 years) who volunteered after informed consent. They were assigned by random into one of four parallel study groups: A, probiotic gum group; B, xylitol gum group; C, probiotic + xylitol gum group; and D, placebo gum group. The gums were taken three times daily after meals, and the intervention period was 3 weeks. The probiotic gums contained two strains of Lactobacilli reuteri (ATCC 55730 at a dose of 1 x 10(8) CFU/gum and ATCC PTA 5289 at a dose of 1 x 10(8) CFU/gum), and each pellet of the xylitol gum contained approximately 1.0 g xylitol as single sweetener. Pretreatment and posttreatment samples of stimulated whole saliva were collected and quantified for MS and LB with chair-side kits. A statistically significant reduction (p < 0.05) of salivary MS was displayed in group A and B after the intervention when compared with baseline. A similar but nonsignificant tendency was seen in group C. No alterations of salivary LB was demonstrated in any group. In conclusion, daily chewing on gums containing probiotic bacteria or xylitol reduced the levels of salivary MS in a significant way. However, a combination of probiotic and xylitol gums did not seem to enhance this effect.

Microarchitecture and Spatial Relationship Between Bacteria and Ileal, Cecal, and Colonic Epithelium in Chicks Fed a Direct-Fed Microbial, PrimaLac, and Salinomycin

Direct-fed microbials (DFM) could serve as a potential alternative to the feeding of antibiotics in poultry production. In this study, the effects of providing a DFM were compared with the feeding of salinomycin on intestinal histomorphometrics, and microarchitecture was examined. Broiler chicks (n=18 per treatment; trials 1 and 2) were fed a standard starter diet (control), control+PrimaLac (DFM; 0.3% wt/wt), and control+salinomycin (SAL; 50 ppm) from hatch to 21d. The birds were euthanized on d 21, and the ileal, jejunal, cecal, and colon tissues were dissected. Samples were examined by light microscopy (jejunum and ileum; trial 1) and scanning electron microscopy (ileum, cecum, and colon; trial 2). Feeding of the DFM increased intestinal muscle thickness (P<0.05) up to 33% compared with the control treatment. The DFM group also had increased villus height and perimeter (P=0.009 and 0.003, respectively) in jejunum. Segmented filamentous-like bacteria were less numerous in DFM-treated chicks than in the control chicks. Very few segmented filamentous-like bacteria were found near other microbes in the ileum. The DFM chicks had a larger number of bacteria positioned over or near goblet cells and in intervilli spaces. Bacteria in the colon were observed to be attached primarily around and within the crypts. Mucous thickness was less, and the density of bacteria embedded in the mucous blanket appeared to be lower in DFM-treated animals than in the control in all intestinal segments. The birds fed SAL had fewer bacteria and enterocytes in the ileum than in the control-and DFM-treated birds, and they had thicker and fewer microvilli. Because gastrointestinal track colonization by the DFM organisms can prevent the attachment of pathogens to the epithelium, spatial relationships, in this study, demonstrate the functionality of DFM and probiotics in preventing disease. It also supports previous observations that the feeding of salinomycin may alter intestinal function.

Molecular characterisation of the gut microflora of healthy and inflammatory bowel disease cats using fluorescence in situ hybridisation with special reference to Desulfovibrio spp

Inflammatory bowel disease (IBD) is a common cause of chronic large bowel diarrhoea in cats. Although the aetiology of IBD is unknown, an immune-mediated response to a luminal antigen is thought to be involved. As knowledge concerning the colonic microflora of cats is limited and requires further investigation, the purpose of this study was to determine the presence of specific bacterial groups in normal and IBD cats, and the potential role they play in the health of the host. Total bacterial populations, Bacteroides spp., Bifidobacterium spp., Clostridium histolyticum subgp., Lactobacillus-Enterococcus subgp. and Desulfovibrio spp. were enumerated in 34 healthy cats and 11 IBD cats using fluorescence in situ hybridisation. The study is one of the first to show the presence of Desulfovibrio in cats. Total bacteria, Bifidobacterium spp. and Bacteroides spp. counts were all significantly higher in healthy cats when compared with IBD cats, whereas Desulfovibrio spp. (producers of toxic sulphides) numbers were found to be significantly higher in colitic cats. The information obtained from this study suggests that modulation of bacterial flora by increasing bifidobacteria and decreasing Desulfovibrio spp. may be beneficial to cats with IBD. Dietary intervention may be an important aspect of their treatment.

Changes in intestinal microbiota and humoral immune response following probiotic administration in brown trout (Salmo trutta)

We studied the effect of several lactic acid bacteria (LAB) on the humoral response of brown trout (Salmo trutta). LAB groups (Lactococcus(Lc.)lactisssp.lactis,Lactobacillus(Lb.)sakeiandLeuconostoc(Leu.)mesenteroides) were administered orally at 106colony-forming units/g feed to brown trout for 2 weeks, after which fish were switched to an unsupplemented feed. Blood and intestinal samples were taken from the onset of feeding supplemented diets at 1, 2, 3 and 4 weeks. During the LAB-feeding period,Lc. lactisssp.lactis,Lb. sakeiandLeu. mesenteroidespersisted in the fish intestines, but the number of LAB slowly decreased in the intestines after changing to the unsupplemented diet. OnlyLb. lactisssp.lactisandLeu. mesenteroideswere detected at levels above 1 × 102colony-forming units/g at the end of the fourth week. In comparison to untreated control fish, the alternative complement activity in the serum was found to be significantly greater in all LAB groups at the end of the second week. Groups supplemented withLc. lactisssp.lactisandLeu. mesenteroidesexhibited an elevated level of lysozyme activity at the end of the third week, but the group supplemented withLb. sakeidid not exhibit any significant change in lysozyme activity. Serum immunoglobulin levels were higher compared with the control group, but there was no significant difference between the LAB and control groups.

[Intake of fermented milk containing Lactobacillus casei DN-114 001 and its effect on gut flora]

OBJECTIVE

To study the gut flora in infants who received fermented milk containing Lactobacillus casei and Streptococcus termophilus and its effect on secretory immunoglobulin levels.

MATERIAL AND METHODS

An experimental, randomized, prospective, parallel group study was carried out. Thirty-five infants were included (18 in the treatment group and 17 in the control group) with a mean age of 2 years (SD: 0.6 years; range: 1-3 years). The experimental group received both fermented milk (0.5 l/day) containing L. casei and S. termophilus for 6 weeks and standard cow's milk for the following 6 weeks. The control group received standard cow's milk (0.5 l/day) for 12 weeks. Secretory IgA levels in saliva were evaluated in the experimental group at the start of the study (baseline levels) and 6 weeks later. In both groups, stools were collected to study gut flora at 0, 6 and 12 week.

RESULTS

Secretory IgA levels significantly increased (p =0.0063) from a mean baseline value of 2.5 mg/dl to a mean of 3.4 mg/dl at 6 weeks. Gram-negative aerobic flora were decreased in the experimental group after 6 weeks compared with the control group (p =0.0203). The number of infants with Lactobacillus spp in their gut flora was greater in the experimental group than in the control group at week 6 and this difference was statistically significant (p =0.028) at week 12. Conclusion The present study provides evidence of L. casei survival in the gastrointestinal tract and of its effect of increasing secretory IgA.

Genotypic and physiological characterization of Saccharomyces boulardii, the probiotic strain of Saccharomyces cerevisiae

Saccharomyces boulardii, a yeast that was isolated from fruit in Indochina, has been used as a remedy for diarrhea since 1950 and is now a commercially available treatment throughout Europe, Africa, and South America. Though initially classified as a separate species of Saccharomyces, recent publications have shown that the genome of S. boulardii is so similar to Saccharomyces cerevisiae that the two should be classified as conspecific. This raises the question of the distinguishing molecular and phenotypic characteristics present in S. boulardii that make it perform more effectively as a probiotic organism compared to other strains of S. cerevisiae. This investigation reports some of these distinguishing characteristics including enhanced ability for pseudohyphal switching upon nitrogen limitation and increased resistance to acidic pH. However, these differences did not correlate with increased adherence to epithelial cells or transit through mouse gut. Pertinent characteristics of the S. boulardii genome such as trisomy of chromosome IX, altered copy number of a number of individual genes, and sporulation deficiency have been revealed by comparative genome hybridization using oligonucleotide-based microarrays coupled with a rigorous statistical analysis. The contributions of the different genomic and phenotypic features of S. boulardii to its probiotic nature are discussed.

Probiotics and inflammatory bowel diseases

Enteric microflora profiles vary considerably between active inflammatory bowel diseases (IBD) and healthy conditions. Intestinal microflora may partake in the pathogenesis of IBD by one or some ways: specific pathogenic infection induces abnormal intestinal mucosal inflammation; aberrant microflora components trigger the onset of IBD; abnormal host immune response loses normal immune tolerance to luminal components; luminal antigens permeate through the defective mucosal barrier into mucosal lamina propria and induce abnormal inflammatory response. Preliminary studies suggest that administration of probiotics may be benefit for experimental colitis and clinical trials for IBD. Researches have been studying the function of probiotics. Introduction of probiotics can balance the aberrant enteric microflora in IBD patients, and reinforce the various lines of intestinal defence by inhibiting microbial pathogens growth, increasing intestinal epithelial tight junction and permeability, modulating immune response of intestinal epithelia and mucosal immune cells, secreting antimicrobial products, decomposing luminal pathogenic antigens.

Probiotics for maintenance of remission in Crohn's disease

BACKGROUND

Crohn's disease (CD) is characterised by episodes of disease activity and symptom-free remission. Probiotics are microorganisms that can potentially benefit health, and have been evaluated as an alternate means of preventing relapse in patients with CD.

OBJECTIVES

To assess the effectiveness of probiotics for the maintenance of remission in CD.

SEARCH STRATEGY

The following databases were searched: the Cochrane Database of Systematic Reviews (2005, Issue 3); the Cochrane Central Register of Controlled Trials (2005, Issue 3); the Cochrane IBD/FBD Group Trials Register (2005), MEDLINE (1966-2005); EMBASE (1980-2005); ISI Web of Knowledge (BIDS) 1981-2005; On-line clinical trials databases (2005); and review articles. Experts in the field were contacted for unpublished data.

SELECTION CRITERIA

Randomised controlled trials of probiotic therapy.

DATA COLLECTION AND ANALYSIS

Two independent reviewers performed data extraction and assessment of methodological quality. The primary outcome was the relative risk (RR) of relapse after maintenance treatment (and 95% confidence intervals [CI]).

MAIN RESULTS

Seven small studies were identified and varied according to probiotics tested, methodological quality and medication regimen. No studies were pooled for statistical analysis. There was no statistically significant benefit of E. coli Nissle for reducing the risk of relapse compared to placebo (RR 0.43, 95% CI 0.15 to 1.20), or Lactobacillus GG after surgically-induced remission (RR 1.58, 95% CI 0.30 to 8.40) or medically-induced remission (RR 0.83, 95% CI 0.25 to 2.80). There was no statistically significant benefit of probiotics for reducing the risk of relapse compared to maintenance therapy employing aminosalicylates or azathioprine (RR 0.67, 95% CI 0.13 to 3.30), and in this study the probiotic Lactobacillus GG was associated with adverse events. In children, there was there was no statistically significant difference between Lactobacillus GG and placebo for reducing the risk of relapse (RR 1.85, 95% CI 0.77 to 4.40). A small study using the yeast Saccharomyces boulardii demonstrated a difference that was not statistically significant in favour of probiotic combined with a reduced level of maintenance therapy over standard maintenance treatment alone (RR 0.17, 95% CI 0.02 to 1.23).

AUTHORS' CONCLUSIONS

There is no evidence to suggest that probiotics are beneficial for the maintenance of remission in CD. All of the included studies enrolled small numbers of patients and may have lacked statistical power to show differences should they exist. Larger trials are required to determine if probiotics are of benefit in Crohn's disease.

Probiotics for maintenance of remission in Crohn's disease

BACKGROUND

Crohn's disease (CD) is characterised by episodes of disease activity and symptom-free remission. Probiotics are microorganisms that can potentially benefit health, and have been evaluated as an alternate means of preventing relapse in patients with CD.

OBJECTIVES

To assess the effectiveness of probiotics for the maintenance of remission in CD.

SEARCH STRATEGY

The following databases were searched: the Cochrane Database of Systematic Reviews (2005, Issue 3); the Cochrane Central Register of Controlled Trials (2005, Issue 3); the Cochrane IBD/FBD Group Trials Register (2005), MEDLINE (1966-2005); EMBASE (1980-2005); ISI Web of Knowledge (BIDS) 1981-2005; On-line clinical trials databases (2005); and review articles. Experts in the field were contacted for unpublished data.

SELECTION CRITERIA

Randomised controlled trials of probiotic therapy.

DATA COLLECTION AND ANALYSIS

Two independent reviewers performed data extraction and assessment of methodological quality. The primary outcome was the relative risk (RR) of relapse after maintenance treatment (and 95% confidence intervals [CI]).

MAIN RESULTS

Seven small studies were identified and varied according to probiotics tested, methodological quality and medication regimen. No studies were pooled for statistical analysis. There was no statistically significant benefit of E. coli Nissle for reducing the risk of relapse compared to placebo (RR 0.43, 95% CI 0.15 to 1.20), or Lactobacillus GG after surgically-induced remission (RR 1.58, 95% CI 0.30 to 8.40) or medically-induced remission (RR 0.83, 95% CI 0.25 to 2.80). There was no statistically significant benefit of probiotics for reducing the risk of relapse compared to maintenance therapy employing aminosalicylates or azathioprine (RR 0.67, 95% CI 0.13 to 3.30), and in this study the probiotic Lactobacillus GG was associated with adverse events. In children, there was there was no statistically significant difference between Lactobacillus GG and placebo for reducing the risk of relapse (RR 1.85, 95% CI 0.77 to 4.40). A small study using the yeast Saccharomyces boulardii demonstrated a difference that was not statistically significant in favour of probiotic combined with a reduced level of maintenance therapy over standard maintenance treatment alone (RR 0.17, 95% CI 0.02 to 1.23).

AUTHORS' CONCLUSIONS

There is no evidence to suggest that probiotics are beneficial for the maintenance of remission in CD. All of the included studies enrolled small numbers of patients and may have lacked statistical power to show differences should they exist. Larger trials are required to determine if probiotics are of benefit in Crohn's disease.

Prebiotic galactooligosaccharides reduce adherence of enteropathogenic Escherichia coli to tissue culture cells

Prebiotic oligosaccharides are thought to provide beneficial effects in the gastrointestinal tract of humans and animals by stimulating growth of selected members of the intestinal microflora. Another means by which prebiotic oligosaccharides may confer health benefits is via their antiadhesive activity. Specifically, these oligosaccharides may directly inhibit infections by enteric pathogens due to their ability to act as structural mimics of the pathogen binding sites that coat the surface of gastrointestinal epithelial cells. In this study, the ability of commercial prebiotics to inhibit attachment of microcolony-forming enteropathogenic Escherichia coli (EPEC) was investigated. The adherence of EPEC strain E2348/69 on HEp-2 and Caco-2 cells, in the presence of fructooligosaccharides, inulin, galactooligosaccharides (GOS), lactulose, and raffinose was determined by cultural enumeration and microscopy. Purified GOS exhibited the greatest adherence inhibition on both HEp-2 and Caco-2 cells, reducing the adherence of EPEC by 65 and 70%, respectively. In addition, the average number of bacteria per microcolony was significantly reduced from 14 to 4 when GOS was present. Adherence inhibition by GOS was dose dependent, reaching a maximum at 16 mg/ml. When GOS was added to adhered EPEC cells, no displacement was observed. The expression of BfpA, a bundle-forming-pilus protein involved in localized adherence, was not affected by GOS, indicating that adherence inhibition was not due to the absence of this adherence factor. In addition, GOS did not affect autoaggregation. These observations suggest that some prebiotic oligosaccharides may have antiadhesive activity and directly inhibit the adherence of pathogens to the host epithelial cell surface.

Probiotics as flourishing benefactors for the human body

This article provides a comprehensive review of the beneficial effects of various strains of probiotics in preventing and treating certain diseases. Currently, changed lifestyles as well as the increased use of antibiotics are significant factors challenging the preservation of a healthy intestinal microflora. The concept of probiotics is to restore and uphold a microflora advantageous for the human body. Probiotics are found in a number of fermented dairy products, infant formula, and dietary supplements. In the presence of prebiotics, which are nondigestible food ingredients favorable for probiotic growth, their survival in the intestine is ameliorated.

Probiotics and chronic disease

In today's climate, changed lifestyles and the increased use of antibiotics are significant factors that affect the preservation of a healthy intestinal microflora. The concept of probiotics is to restore and maintain a microflora advantageous to the human body. Probiotics are found in a number of fermented dairy products, infant formula, and dietary supplements. Basic research on probiotics has suggested several modes of action beneficial for the human body and clinical research has proven its preventive and curative features in different intestinal and extraintestinal diseases. Chronic diseases cause considerable disablement in patients and represent a substantial economic burden on healthcare resources. Research has demonstrated a crucial role of nutrition in the prevention of chronic disease. Thus, positive, strain-specific effects of probiotics have been shown in diarrheal diseases, inflammatory bowel diseases, irritable bowel syndrome, and Helicobacter pylori-induced gastritis, and in atopic diseases and in the prevention of cancer. As the majority of probiotics naturally inhabit the human intestinal microflora, their use has been regarded as very safe. However, in view of the range of potential benefits on health that might be achieved by the use of some probiotic bacteria, major and thorough evaluation is still necessary. In conclusion, probiotics act as an adjuvant in the prevention and treatment of a wide variety of chronic diseases.

Effect of special Hungarian probiotic kefir on faecal microflora

AIM: To investigate the effect of a four-week consumption of a special Hungarian probiotic agent (Biofir^®) on the faecal microflora in human healthy subjects.

METHODS: The effect of Biofir^® with 10⁶/cm³ initial germs on the faecal microflora was studied in 120 healthy volunteers (71 females, 49 males). The traditional Russian type kefir was used as control. The various germ groups and pH values were determined in wk 2, 4 and 6.

RESULTS: The number of all microbes increased during the 4-week probiotic treatment. The number of microbes increased 4.3-fold in the control group and 6.8-fold in Biofir-treated group. The probiotic kefir caused multiplication of the probiotic flora, meanwhile the undesired bacteria multiplied in the control group. No significant change of pH values of the faeces was found in both groups.

CONCLUSION: The Hungarian probiotic kefir (Biofir^®) is capable of promoting multiplication of probiotic bacterial flora in the large bowel.

Living drugs for gastrointestinal diseases: the case for probiotics

Nonpathogenic micro-organisms may contain or produce molecules of potential therapeutic interest. This led to the concept of using ingested living micro-organisms to produce and transport these molecules to targets in the proximal or distal intestine. Several characteristics of this pharmacological approach are very original: potential for in vivo production of active molecules, for targeting immune cells, for presenting immunogenic molecules in a microbial context, for duodenal delivery using bile sensitivity. Probiotics have been studied for some decades and more recently worm eggs have also received some interest. This paper summarizes facts (especially results of randomized controlled trials and pharmacokinetic studies), and ideas about the use of probiotics to treat or prevent gastrointestinal diseases. The safety of this approach (exceptional cases of infections have been observed), and the potential for using new agents or genetically modified micro-organisms (ongoing trials in humans with Crohn's disease) are also discussed.

Precaecal and faecal digestibility of inulin (DP 10-12) or an inulin/Enterococcus faecium mix and effects on nutrient digestibility and microbial gut flora

The aim of the present study was to investigate the precaecal and faecal digestibility of inulin (DP 10-12) and inulin/Enterococcus faecium mix, and the effects of these substances on nutrient digestibility and microbial gut flora. For the experiment four of eight male pigs were fitted with an end-to-end ileo-rectal anastomosis (IRA) with preserved ileo-caeco-colic valve. The residual pigs were used as intact partner (IN). The animals received 1.5 kg/day of a diet based on corn, wheat, barley and soybean meal, supplemented with either 8 x 10(9) CFU E. faecium/kg, 2% inulin or a mixture of both substances. The digestibility trial was carried out from weeks 4 to 8 after surgery. Precaecal digestibility of inulin was assessed to be 57%. The addition of E. faecium to the diet resulted in a similar precaecal digestibility of inulin of 55%. Supplementation of E. faecium, inulin, and a mixture of E. faecium and inulin did not affect precaecal and faecal nutrient digestibility with the exception of the precaecal digestibility of CF which increased when inulin alone was supplemented. Bacterial population in the digesta of IRA and IN pigs were not affected by the experimental diets except the concentration of bifidobacteria and lactobacilli. The supplementation of E. faecium to the diet significantly decreased the concentration of bifidobacteria and the population of lactobacilli inclined to decrease when IN pigs received the probiotic diet. The combination of E. faecium and inulin prevented a reduction of enterococci in faeces of IN pigs. The daily digesta excretion (DM) tended to decrease in IRA and IN pigs when inulin was supplemented. The results indicate that inulin (DP 10-12) in pig nutrition did partly react as a prebiotic as has been confirmed for humans. A combination of E. faecium and inulin improves the survival of the probiotic strain through the upper intestinal tract and allocates the synbiotic effect. Furthermore inulin might be able to show positive effects on precaecal and faecal microbial characteristics.

Fat From Different Foods Show Diverging Relations With Breast Cancer Risk in Postmenopausal Women

The aim was to explore previous findings within the Malmö Diet and Cancer cohort (Sweden) that omega6-fatty acid intakes are positively associated with breast cancer risk among women 50 yr of age and older and specifically examine relations between breast cancer risk and fat from different food groups. Incident breast cancer cases (n = 237) were matched to controls (n = 673) on age and screening date. A modified diet history method, a structured questionnaire, and anthropometric measurements provided data. Fat-food variables from 24 food groups were computed. Conditional logistic regression examined breast cancer risk associated with energy-adjusted exposure categories of fat-food variables. Fat from fermented milk products was negatively associated with breast cancer risk (trend, P = 0.003). The highest quartiles of vegetable oil-based dietary fats (odds ratio, OR = 1.74; confidence interval, CI = 1.12-2.72) and dried soup powders (OR = 1.59; CI = 1.04-2.43) showed positive associations. Dietary fiber did not influence associations.

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.

Real-time PCR quantification of bacterial adhesion to Caco-2 cells: competition between bifidobacteria and enteropathogens

Probiotic bacteria play an important role in protecting the host from intestinal colonization of pathogenic bacteria. We have developed a new analytical approach based on a real-time PCR technique for quantifying Bifidobacterium adhesion to intestinal epithelial cells. Real-time PCR analysis showed that adhesion to enterocyte-like Caco-2 cells represented a variable phenotype in the genus Bifidobacterium, enabling classification of three adhesion behaviors: high adhesiveness (>40 bifidobacterial cells/Caco-2 cell); adhesiveness (5-40 bifidobacterial cells/Caco-2 cell); no adhesiveness (<5 bifidobacterial cells/Caco-2 cell). This molecular methodology was successfully used in competition studies in enteropathogens. All bifidobacterial strains examined evidenced displacement activity towards important enteropathogens (S. typhimurium, Y. enterocolitica and E. coli EPEC). Real-time PCR is a rapid, accurate and sensitive method for detecting and quantifying different bacterial genera and species simultaneously adhering to a epithelial cell monolayer.

A proteomic view ofBifidobacterium infantis generated by multi-dimensional chromatography coupled with tandem mass spectrometry

Bifidobacteria are Gram-positive prokaryotes that naturally colonize the human gut where they exert several health-promoting effects. The present paper reports the use of a strong cation exchange-reversed-phase-tandem mass spectrometry strategy to catalogue the most abundantly expressed proteins of a probiotic Bifidobacterium infantis strain. A global view of the B. infantis proteome was obtained. The bimodal representation of the proteins identified by mass spectrometry provides the first theoretical two-dimensional map of protein distribution for this organism. Among the 136 proteins identified by multidimensional protein identification technology (MudPIT) analysis, 118 showed the highest similarity with the translated sequences of B. longum genome, two proteins were similar to other Bifidobacterium species and the remaining 16 were similar to different genera. Specific biological activities have been assigned to 115 identified proteins, whereas 21 have been referred to the group of hypothetical proteins. The MudPIT approach allowed us to identify high mass and basic isoelectric point proteins that are generally challenging to visualize using the traditional two-dimensional electrophoresis technique. Redundancy in peptide and protein identification using the double chromatography technique was also evaluated.

Lactobacillus and bifidobacterium in irritable bowel syndrome: symptom responses and relationship to cytokine profiles

BACKGROUND & AIMS

The aim of this study was to compare the response of symptoms and cytokine ratios in irritable bowel syndrome (IBS) with ingestion of probiotic preparations containing a lactobacillus or bifidobacterium strain.

METHODS

Seventy-seven subjects with IBS were randomized to receive either Lactobacillus salivarius UCC4331 or Bifidobacterium infantis 35624, each in a dose of 1 x 10 10 live bacterial cells in a malted milk drink, or the malted milk drink alone as placebo for 8 weeks. The cardinal symptoms of IBS were recorded on a daily basis and assessed each week. Quality of life assessment, stool microbiologic studies, and blood sampling for estimation of peripheral blood mononuclear cell release of the cytokines interleukin (IL)-10 and IL-12 were performed at the beginning and at the end of the treatment phase.

RESULTS

For all symptoms, with the exception of bowel movement frequency and consistency, those randomized to B infantis 35624 experienced a greater reduction in symptom scores; composite and individual scores for abdominal pain/discomfort, bloating/distention, and bowel movement difficulty were significantly lower than for placebo for those randomized to B infantis 35624 for most weeks of the treatment phase. At baseline, patients with IBS demonstrated an abnormal IL-10/IL-12 ratio, indicative of a proinflammatory, Th-1 state. This ratio was normalized by B infantis 35624 feeding alone.

CONCLUSIONS

B infantis 35624 alleviates symptoms in IBS; this symptomatic response was associated with normalization of the ratio of an anti-inflammatory to a proinflammatory cytokine, suggesting an immune-modulating role for this organism, in this disorder.

Does the microbiota regulate immune responses outside the gut?

Perturbations in the gastrointestinal (GI) microbiota composition that occur as a result of antibiotics and diet in "westernized" countries are strongly associated with allergies and asthma ("hygiene hypothesis"). The microbiota ("microflora") plays a crucial role in the development of mucosal tolerance, including the airways. Significant attention has been focused on the role of the microbiota in GI development, immune adaptation and initiation of GI inflammatory diseases. This review covers the post-developmental functions that the microbiota plays in regulating immunological tolerance to allergen exposure outside the GI tract and proposes the question: is the microbiota a major regulator of the immune system?

Probiotics and the management of inflammatory bowel disease

The demonstration that immune and epithelial cells can discriminate between different microbial species has extended our understanding of the actions of probiotics beyond simple barrier and antimicrobial concepts. Several probiotic mechanisms of action, relative to inflammatory bowel disease, have been elucidated: (1) competitive exclusion, whereby probiotics compete with microbial pathogens for a limited number of receptors present on the surface epithelium; (2) immunomodulation and/or stimulation of an immune response of gut-associated lymphoid and epithelial cells; (3) antimicrobial activity and suppression of pathogen growth; (4) enhancement of barrier function; and (5) induction of T cell apoptosis in the mucosal immune compartment. The unraveling of these mechanisms of action has led to new support for the use of probiotics in the management of clinical inflammatory bowel disease. Though level 1 evidence now supports the therapeutic use of probiotics in the treatment of postoperative pouchitis, only levels 2 and 3 evidence is currently available in support of the use of probiotics in the treatment of ulcerative colitis and Crohn's disease. Nevertheless, one significant and consistent finding has emerged during the course of research in the past year: not all probiotic bacteria have similar therapeutic effects. Rigorously designed, controlled clinical trials are vital to investigate the unresolved issues related to efficacy, dose, duration of use, single or multi-strain formulation, and the concomitant use of probiotics, synbiotics, or antibiotics.