Reduction of virus shedding by B. bifidum in experimentally induced MRV infection. Statistical application for ELISA

Microbial colonization of the gastrointestinal tract of dairy calves - a review of its importance and relationship to health and performance

This review aims to explain how microbial colonization of the gastrointestinal tract (GIT) in young dairy calves is related to health and, consequently, to the performance of these animals. The review addresses everything from the fundamental aspects of microbial colonization to the current understanding about the microbiota manipulation to improve performance in adult animals. The ruminal microbiota is the most studied, mainly due to the high interest in the fermentative aspects, the production of short-chain fatty acids, and microbial proteins, and its effects on animal production. However, in recent years, the intestinal microbiota has gained space between studies, mainly due to the relationship to the host health and how it affects performance. Understanding how the GIT's microbiota looks like and how it is colonized may allow future studies to predict the best timing for dietary interventions as a way to manipulate it and, consequently, improve the health and performance of young ruminants.

The metabolic profile of Bifidobacterium dentium reflects its status as a human gut commensal

BACKGROUND

Bifidobacteria are commensal microbes of the mammalian gastrointestinal tract. In this study, we aimed to identify the intestinal colonization mechanisms and key metabolic pathways implemented by Bifidobacterium dentium.

RESULTS

B. dentium displayed acid resistance, with high viability over a pH range from 4 to 7; findings that correlated to the expression of Na+/H+ antiporters within the B. dentium genome. B. dentium was found to adhere to human MUC2+ mucus and harbor mucin-binding proteins. Using microbial phenotyping microarrays and fully-defined media, we demonstrated that in the absence of glucose, B. dentium could metabolize a variety of nutrient sources. Many of these nutrient sources were plant-based, suggesting that B. dentium can consume dietary substances. In contrast to other bifidobacteria, B. dentium was largely unable to grow on compounds found in human mucus; a finding that was supported by its glycosyl hydrolase (GH) profile. Of the proteins identified in B. dentium by proteomic analysis, a large cohort of proteins were associated with diverse metabolic pathways, indicating metabolic plasticity which supports colonization of the dynamic gastrointestinal environment.

CONCLUSIONS

Taken together, we conclude that B. dentium is well adapted for commensalism in the gastrointestinal tract.

In Vivo Evaluation of Immune-Enhancing Activity of Red Gamju Fermented by Probiotic Levilactobacillus brevis KU15154 in Mice

The purpose of this study was to evaluate the immune-enhancing effect of red gamju fermented with Levilactobacillus brevis KU15154, isolated from kimchi, as a biofunctional beverage using mice. Thirty-two mice were used, and after a 2-week feeding, the growth, cytokine and immunoglobulin production, and immune-related cell activation (phagocytes and natural killer [NK] cells) of the mice were evaluated. The red gamju- (SR) and fermented red gamju- (FSR) treated groups had 3.5-4.0-fold greater T-cell proliferation ability than the negative control group. IFN-γ production in the FSR group (15.5 ± 1.2 mg/mL) was significantly higher (p < 0.05) than that in the SR group (12.5 ± 1.8 mg/mL). The FSR group (502.6 ± 25.8 μg/mL) also showed higher IgG production levels than the SR group (412.2 ± 44.8 μg/mL). The activity of NK cells treated with FSR was also greater than that of cells treated with SR but it was not significant (p ≤ 0.05). Further, the phagocytic activity of peritoneal macrophages was higher in both SR and FSR groups than in the control group but was not significantly different (p < 0.05) between the SR and FSR groups. In conclusion, L. brevis KU15154 may be applied in the fermentation of bioactive food products, such as beverages or pharmaceutical industries, to potentially improve immunity.

The Complex Interactions Between Rotavirus and the Gut Microbiota

Human rotavirus (HRV) is the leading worldwide cause of acute diarrhea-related death in children under the age of five. RV infects the small intestine, an important site of colonization by the microbiota, and studies over the past decade have begun to reveal a complex set of interactions between RV and the gut microbiota. RV infection can temporarily alter the composition of the gut microbiota and probiotic administration alleviates some symptoms of infection in vivo, suggesting reciprocal effects between the virus and the gut microbiota. While development of effective RV vaccines has offered significant protection against RV-associated mortality, vaccine effectiveness in low-income countries has been limited, potentially due to regional differences in the gut microbiota. In this mini review, we briefly detail research findings to date related to HRV vaccine cohorts, studies of natural infection, explorations of RV-microbiota interactions in gnotobiotic pig models, and highlight various in vivo and in vitro models that could be used in future studies to better define how the microbiota may regulate RV infection and host antiviral immune responses.

Bifidobacterium dentium Fortifies the Intestinal Mucus Layer via Autophagy and Calcium Signaling Pathways

Much remains unknown about how the intestinal microbiome interfaces with the protective intestinal mucus layer. Bifidobacterium species colonize the intestinal mucus layer and can modulate mucus production by goblet cells. However, select Bifidobacterium strains can also degrade protective glycans on mucin proteins. We hypothesized that the human-derived species Bifidobacterium dentium would increase intestinal mucus synthesis and expulsion, without extensive degradation of mucin glycans. In silico data revealed that B. dentium lacked the enzymes necessary to extensively degrade mucin glycans. This finding was confirmed by demonstrating that B. dentium could not use naive mucin glycans as primary carbon sources in vitro To examine B. dentium mucus modulation in vivo, Swiss Webster germfree mice were monoassociated with live or heat-killed B. dentium Live B. dentium-monoassociated mice exhibited increased colonic expression of goblet cell markers Krüppel-like factor 4 (Klf4), Trefoil factor 3 (Tff3), Relm-β, Muc2, and several glycosyltransferases compared to both heat-killed B. dentium and germfree counterparts. Likewise, live B. dentium-monoassociated colon had increased acidic mucin-filled goblet cells, as denoted by Periodic Acid-Schiff-Alcian Blue (PAS-AB) staining and MUC2 immunostaining. In vitro, B. dentium-secreted products, including acetate, were able to increase MUC2 levels in T84 cells. We also identified that B. dentium-secreted products, such as γ-aminobutyric acid (GABA), stimulated autophagy-mediated calcium signaling and MUC2 release. This work illustrates that B. dentium is capable of enhancing the intestinal mucus layer and goblet cell function via upregulation of gene expression and autophagy signaling pathways, with a net increase in mucin production.IMPORTANCE Microbe-host interactions in the intestine occur along the mucus-covered epithelium. In the gastrointestinal tract, mucus is composed of glycan-covered proteins, or mucins, which are secreted by goblet cells to form a protective gel-like structure above the epithelium. Low levels of mucin or alterations in mucin glycans are associated with inflammation and colitis in mice and humans. Although current literature links microbes to the modulation of goblet cells and mucins, the molecular pathways involved are not yet fully understood. Using a combination of gnotobiotic mice and mucus-secreting cell lines, we have identified a human-derived microbe, Bifidobacterium dentium, which adheres to intestinal mucus and secretes metabolites that upregulate the major mucin MUC2 and modulate goblet cell function. Unlike other Bifidobacterium species, B. dentium does not extensively degrade mucin glycans and cannot grow on mucin alone. This work points to the potential of using B. dentium and similar mucin-friendly microbes as therapeutic agents for intestinal disorders with disruptions in the mucus barrier.

Probiotics in Newborns and Children

Microbes and humans have been closely associated throughout evolution; this symbiotic and/or commensal relationship is crucial for normal development and health. The use of probiotics has been the topic of intense investigation in the past couple of decades because they have the capability to promote health. Based on these studies, it can be debated whether they are being used to promote overall health or to treat and prevent diseases. This review provides an overview and analysis of evidence about what is currently known about the health benefits of these agents that are marketed for use in children and neonates.

Bifidobacteria and Their Role as Members of the Human Gut Microbiota

Members of the genus Bifidobacterium are among the first microbes to colonize the human gastrointestinal tract and are believed to exert positive health benefits on their host. Due to their purported health-promoting properties, bifidobacteria have been incorporated into many functional foods as active ingredients. Bifidobacteria naturally occur in a range of ecological niches that are either directly or indirectly connected to the animal gastrointestinal tract, such as the human oral cavity, the insect gut and sewage. To be able to survive in these particular ecological niches, bifidobacteria must possess specific adaptations to be competitive. Determination of genome sequences has revealed genetic attributes that may explain bifidobacterial ecological fitness, such as metabolic abilities, evasion of the host adaptive immune system and colonization of the host through specific appendages. However, genetic modification is crucial toward fully elucidating the mechanisms by which bifidobacteria exert their adaptive abilities and beneficial properties. In this review we provide an up to date summary of the general features of bifidobacteria, whilst paying particular attention to the metabolic abilities of this species. We also describe methods that have allowed successful genetic manipulation of bifidobacteria.

Randomized double blinded controlled trial to evaluate the efficacy and safety of Bifilac in patients with acute viral diarrhea

OBJECTIVE

To evaluate the efficacy and safety of Bifilac on reducing the episodes (frequency) and duration of diarrhea induced by rotaviral infection and to evaluate the efficacy of Bifilac to ameliorate the associated symptoms like dehydration and duration of rotaviral shedding in faeces.

METHODS

80 children aged between 3 months and 3 years were enrolled and divided into 2 groups, one group received standard therapy + placebo, the other group received standard therapy + probiotic (Bifilac) randomly. Children assessed for frequency and duration of diarrhea. Degree of dehydration, duration and volume of oral rehydration salt [ORS] therapy, duration and volume of Intra venous fluids and duration of rotaviral shedding.

RESULTS

When compared to the placebo, Bifilac showed clinical as well as statistically significant reduction in Number of episodes (frequency) of diarrhea in a day, mean duration of diarrhea (in days) degree of dehydration, duration and volume of oral rehydration salt [ORS] therapy, duration and volume of intravenous fluid [IVF] therapy, duration of rotaviral shedding (P<0.01).

CONCLUSION

The synbiotic, bifilac, appears to be a safe and very effective adjuvant in the management of acute rotaviral diarrhea.

Effects of probiotics on enteric flora and feeding tolerance in preterm infants

BACKGROUND

Probiotics are live microbes that colonize the gastrointestinal tract and benefit the host. Preterm infants develop abnormal patterns of bowel colonization, and only a few clinical trials have reported the outcomes of preterm infants treated with probiotics.

PURPOSE

We investigated the rate of colonization of Lactobacillus and the clinical variables affecting the colonization in preterm infants.

METHODS

Infants with gestational age less than 37 weeks treated at Ewha Womans University Hospital between March 2003 and July 2004 were eligible. Lactobacillus acidophilus (containing 10(8) CFU) was supplemented orally, mixed with breast milk or formula divided into three doses a day. Stool samples were collected before and 14 days after supplementation of the probiotic. Stool samples were anaerobically cultured on Rogosa agar and identified by Gram stain, catalase test and glucose fermentation test. Clinical characteristics were analyzed.

RESULTS

Seventy-three patients with an average gestational age of 33.0 +/- 2.5 weeks were studied. Meconium was cultured in 46 patients and Lactobacillus was not detected. Probiotic supplementation began on 3.4 +/- 6.8 days, and after 14 days of supplementation, Lactobacillus was cultured in an average of 3.01 x 10(8) CFU in the stool of 37.0% (27/73) of the patients. There was a tendency towards an increased incidence of sepsis in the Lactobacillus- group (p = 0.082). In the Lactobacillus+ group, a striking increase in feeding tolerance was detected.

CONCLUSION

In preterm infants, with the administration of probiotics, 37% of the preterm infants had Lactobacillus colonized in the gastrointestinal tract and improved feeding tolerance. A double-blind study is in progress for further investigation into the effect on other systemic diseases in premature infants.

Review article: bifidobacteria as probiotic agents -- physiological effects and clinical benefits

Bifidobacteria, naturally present in the dominant colonic microbiota, represent up to 25% of the cultivable faecal bacteria in adults and 80% in infants. As probiotic agents, bifidobacteria have been studied for their efficacy in the prevention and treatment of a broad spectrum of animal and/or human gastrointestinal disorders, such as colonic transit disorders, intestinal infections, and colonic adenomas and cancer. The aim of this review is to focus on the gastrointestinal effects of bifidobacteria as probiotic agents in animal models and man. The traditional use of bifidobacteria in fermented dairy products and the GRAS ('Generally Recognised As Safe') status of certain strains attest to their safety. Some strains, especially Bifidobacterium animalis strain DN-173 010 which has long been used in fermented dairy products, show high gastrointestinal survival capacity and exhibit probiotic properties in the colon. Bifidobacteria are able to prevent or alleviate infectious diarrhoea through their effects on the immune system and resistance to colonization by pathogens. There is some experimental evidence that certain bifidobacteria may actually protect the host from carcinogenic activity of intestinal flora. Bifidobacteria may exert protective intestinal actions through various mechanisms, and represent promising advances in the fields of prophylaxis and therapy.

Functional Foods: A Survey of Health Claims, Pros and Cons, and Current Legislation

Functional foods stand for a new category of remarkably promising foods bearing properties (i.e., low cholesterol, antioxidant, anti-aging, anticancer, etc.) that have already rendered them quite appealing. There are many classes offunctionalfoods (pro- and pre-biotics, dietary fiber, low fat, etc.), and their definition is occasionally confused with that of nutraceuticals and novel foods. Consumers' main skepticism regarding functional foods resides in the veracity of health claims and in the low and often inadequate control of their claimed properties. Legislation concerning this matter is progressing at an extremely low pace and currently only Japan, the U.K., U.S.A., and Scandinavian countries have managed to make notable progress. Moreover, the labeling of functional foods is far from informative, providing scanty information about nutritional value, storage, and cooking recipes. It is anticipated that technological advances in the food industry, in conjunction with extensive clinical trials and governmental control, will eventually guarantee the credibility of health claims and ensure consumers' confidence in functional foods.

Nutritional impact of pre- and probiotics as protective gastrointestinal organisms

The health benefits of pre- and probiotics have been the subject of increased research interests. These food supplements have been demonstrated to alter the pre-existing intestinal flora so as to provide an advantage to the host. This review focuses on the scientific evidence both for and against their role in promoting health and treating disease. Specific attention is turned to their effects on immunomodulation, lipid metabolism, cancer prevention, diarrhea, Helicobacter pylori, necrotizing enterocolitis, allergy, and inflammatory bowel disease.

Immune protection mediated by the probiotic Lactobacillus rhamnosus HN001 (DR20) against Escherichia coli O157:H7 infection in mice

This study investigated the protective effects of feeding the immunoenhancing probiotic Lactobacillus rhamnosus HN001 against Escherichia coli O157:H7 infection in murine (BALB/c and C57BL/6 mice) challenge infection models. Mice were fed milk-based diets supplemented with L. rhamnosus HN001 (3 x 10(8) cfu g(-1)) for 7 days prior to and following oral challenge with E. coli O157:H7. Morbidity and feed intake were measured for 1 week following challenge; pathogen translocation to spleen, liver and blood, and humoral and cellular immunological responses (specific antibody and phagocytosis) were measured in a sub-sample of ostensibly healthy animals 1 week post-challenge. Results showed that, after challenge, L. rhamnosus HN001-fed mice exhibited lower cumulative morbidity and bacterial translocation rates, compared to non-probiotic-fed control mice. Significantly higher intestinal anti-E. coli IgA responses and blood leucocyte phagocytic activity were recorded among probiotic-fed mice compared to controls. These results demonstrate that feeding the probiotic L. rhamnosus HN001 to mice can reduce the severity of E. coli O157:H7 infection, and suggest that this reduction may be associated with enhanced humoral and cellular immune responses.

Immune responses in rhesus rotavirus-challenged BALB/c mice treated with bifidobacteria and prebiotic supplements

Bifidobacterium species (B. bifidum and B. infantis), with or without prebiotic compounds (arabino-galactan, short-chain fructo-oligosaccharide, iso-malto-dextrins), were orally fed to Balb/c pups (n = 192) to evaluate their potential synergistic effects on modulating the course of rhesus rotavirus (RRV) infection, as well as their ability to mediate the associated mucosal and humoral immune responses. Rotavirus-specific IgA and IgG in serum, rotavirus antigen, and specific IgA in feces were measured by ELISA. Mucosal total IgA and IgG levels were determined in Peyer's patches by flow cytometry. Significantly delayed onset (p = 0.001) and early resolution (p < 0.001) of diarrhea were observed in bifidobacteria-treated, RRV-infected mice compared with RRV-infected control mice. Supplementation with prebiotic compounds did not shorten the clinical diarrhea course more than that observed with bifidobacteria treatment alone. Rotavirus-specific IgA in feces was 16-fold elevated on d 5 postinfection in bifidobacteria-treated, RRV-infected mice compared with the RRV-infected alone group. In addition, the level of rotavirus-specific IgA in serum was four-fold higher in bifidobacteria-treated, RRV-infected litters versus mice challenged with RRV alone on 28 and 42 d postinfection. No enhancement of the immune response was found in RRV-infected mice that were treated with both bifidobacteria and prebiotic compounds over those treated with bifidobacteria only. The findings suggest that bifidobacteria may act as an adjuvant by modulating early mucosal and strong humoral rotavirus-specific immune responses, and mitigate severity of rotavirus-induced diarrhea.

Probiotic treatment using Bifidobacterium lactis HN019 reduces weanling diarrhea associated with rotavirus and Escherichia coli infection in a piglet model

BACKGROUND

Diarrhea associated with rotavirus and Escherichia coli is one of the major gastrointestinal problems faced by human infants. Using a piglet model, the authors investigated the protective effectiveness of probiotic feeding against naturally acquired diarrhea in weanlings.

METHODS

Seventeen piglets were allocated into two groups balanced for live weight and litter of origin. The test group was administered Bifidobacterium lactis HN019 (109 colony-forming units (cfu)/piglet/d) orally until the end of the experiment; the control group did not receive probiotic treatment. After 1 week, animals were penned individually and weaned onto a diet for a weaner. The degree of subsequent diarrheal disease was monitored in both groups of animals, feed intake and live weight gain of the piglets were assessed, and blood and fecal samples were collected to measure concurrent systemic and gastrointestinal tract immunologic activity.

RESULTS

Compared with the controls, piglets that received B. lactis HN019 had a lower severity of weanling diarrhea and maintained a greater feed conversion efficiency during weaning. The protective effect of probiotic feeding was associated with lower concentrations of fecal rotavirus and E. coli, higher blood leukocyte phagocytic and T-lymphocyte proliferative responses, and higher gastrointestinal tract pathogen-specific antibody titers.

CONCLUSIONS

These results show that dietary treatment using B. lactis HN019 can reduce the severity of weanling diarrhea associated with rotavirus and E. coli, possibly via a mechanism of enhanced immune-mediated protection. This study suggests that probiotic treatment may be an effective dietary means of preventing or limiting diarrhea in human infants.

Effects of probiotic bacteria on diarrhea, lipid metabolism, and carcinogenesis: a review of papers published between 1988 and 1998

We reviewed the evidence from human intervention studies for the health effects of probiotic bacteria, ie, live bacteria that survive passage through the gastrointestinal tract and have beneficial effects on the host. Of the 49 studies reviewed, 26 dealt with the prevention or treatment of diarrheal disease, 9 with the prevention of cancer or of the formation of carcinogens, 7 with the lowering of serum cholesterol, and 7 with the stimulation of the immune system. The most widely studied probiotic bacteria were Lactobacillus GG (22 studies), Lactobacillus acidophilus (16 studies), Bifidobacterium bifidum (6 studies), and Enterococcus faecium (7 studies). Intake of Lactobacillus GG consistently shortened the diarrheal phase of rotavirus infection by 1 d. However, evidence for the prevention by Lactobacillus GG and other probiotics of diarrhea due to viral or bacterial infections was less strong. Effects of probiotics on the immune system are inconclusive because of the variety of outcome variables reported. Cholesterol lowering by L. acidophilus was shown in some but not all studies; cholesterol lowering by E. faecium seems to be transient. Two studies of one research group showed a smaller recurrence of bladder tumors in patients after treatment with Lactobacillus casei; these results await confirmation. The production of mutagens after a meal might be reduced by the concomitant intake of probiotics, but the relevance of this finding is unclear. In conclusion, consumption of foods containing Lactobacillus GG may shorten the course of rotavirus infection. Other health effects of probiotic bacteria have not been well established. Well-designed placebo-controlled studies with validated outcome variables are needed to determine the health effects of probiotics.

Interactions mediating bacterial translocation in the immature intestine

Systemic disease caused by transmucosal passage of enterovirulent bacteria and toxins from the gut lumen into the mesenteric lymph nodes (MLN) is reviewed, with particular concern for bacterial interactions in the developing gut of premature newborns. Anaerobic bacteria are rarely observed to translocate to the MLN. Bifidobacterial strains have been tested for their abilities to adhere to enterocyte-like Caco-2 cells in culture. We have investigated the inhibitory effect of adherent human bifidobacterial strains against colonization by a number of diarrheagenic bacteria (Escherichia coli O157; Salmonella typhimurium) and viruses (murine and rhesus rotavirus), in various in vitro and in vivo models. The phagocytic cell (macrophage) may be a key factor in bacterial translocation (BT). Human breast milk contains abundant bioactive substances (immunologic, nutritional) that provide protective effects through inhibition of bacterial overgrowth and BT. New biotherapeutic therapies that stimulate beneficial anaerobic microflora (Lactobacillus, Bifidobacterium) are promising avenues of research to combat BT in disease treatment.

The current status of the rotavirus vaccine

The US just licensed of an oral tetravalent rhesus reassortant vaccine for routine immunization of infants against rotavirus. The virus was first identified 25 years ago and is now recognized to be the most common single cause of severe diarrhea throughout the world. Most children suffer at least one infection and reinfection is common. Studies of natural immunity show that breastfeeding may merely delay onset of primary infection and that maternal immunity has little effect-especially in developing countries where onset in early infancy is common. Immunity, furthermore, appears to be serotype-specific. Early attempts to develop a vaccine focused on animal forms of rotavirus. More recent efforts have created human-animal reassortants that have been far more successful.

Effect of faecal consistency on virological diagnosis

A study was set up to investigate the effect of consistency of routine faecal specimens on the diagnostic yield by electron microscopy (EM) and virus isolation. A total of 3078 specimens were characterized as solid, semisolid, or liquid. Of 2568 specimens processed by EM a virus was demonstrated in 8.6% of liquid, 19.9% of semisolid and 25.2% of solid specimens (Chi-squared for linear trend, P value <0.0001). This observation was valid for both adenovirus (2.4%, 5.0% and 6.6%) and rotavirus (5.2%, 13.6% and 16.6%). Virus isolation was positive in 3.6% of liquid, 17.4% of semisolid and 18.1% of solid specimens. (Chi-squared for linear trend, P value <0.0001). We suggest that solid faecal specimens at the end of an episode of diarrhoea will have a higher diagnostic yield than liquid specimens at the peak of symptoms. Our findings repudiate the commonly held dogma that viruses of gastroenteritis are more likely to be found in liquid than in solid faecal specimens. This finding has important implications for those establishing diagnostic algorithms for the investigation of viral gastroenteritis.