Summary of probiotic activities of Bifidobacterium lactis HN019

Unlocking the power of postbiotics: A revolutionary approach to nutrition for humans and animals

Postbiotics, which comprise inanimate microorganisms or their constituents, have recently gained significant attention for their potential health benefits. Extensive research on postbiotics has uncovered many beneficial effects on hosts, including antioxidant activity, immunomodulatory effects, gut microbiota modulation, and enhancement of epithelial barrier function. Although these features resemble those of probiotics, the stability and safety of postbiotics make them an appealing alternative. In this review, we provide a comprehensive summary of the latest research on postbiotics, emphasizing their positive impacts on both human and animal health. As our understanding of the influence of postbiotics on living organisms continues to grow, their application in clinical and nutritional settings, as well as animal husbandry, is expected to expand. Moreover, by substituting postbiotics for antibiotics, we can promote health and productivity while minimizing adverse effects. This alternative approach holds immense potential for improving health outcomes and revolutionizing the food and animal products industries.

New Strategies for Enhancement of Infant Milk Formulas Composition

This article covers the issues of remodeling breast milk’s protective properties during creating infant milk formulas. First of all, this concerns the conditions for normal intestinal microbiota development in growing organism. Its quantitative and qualitative features are the trigger of either sanogenetic, or pathological immune and metabolic reactions, and also determine gut-brain axis functioning. The protective significance of prebiotic composition diversity of mammalian milk and the inductive role of breast milk oligosaccharides are shown. The modern concept of synbiotics role in gastrointestinal tract and other systems functioning, as well as the use of modern synbiotics in the creation of infant formulas (available Russian formula included) are presented.

Use of the Probiotic Bifidobacterium animalis subsp. lactis HN019 in Oral Diseases

The oral cavity is one of the environments on the human body with the highest concentrations of microorganisms that coexist harmoniously and maintain homeostasis related to oral health. Several local factors can shift the microbiome to a pathogenic state of dysbiosis. Existing treatments for infections caused by changes in the oral cavity aim to control biofilm dysbiosis and restore microbial balance. Studies have used probiotics as treatments for oral diseases, due to their ability to reduce the pathogenicity of the microbiota and immunoinflammatory changes. This review investigates the role of the probiotic Bifidobacterium animalis subsp. lactis (B. lactis) HN019 in oral health, and its mechanism of action in pre-clinical and clinical studies. This probiotic strain is a lactic acid bacterium that is safe for human consumption. It mediates bacterial co-aggregation with pathogens and modulates the immune response. Studies using B. lactis HN019 in periodontitis and peri-implant mucositis have shown it to be a potential adjuvant treatment with beneficial microbiological and immunological effects. Studies evaluating its oral effects and mechanism of action show that this probiotic strain has the potential to be used in several dental applications because of its benefit to the host.

Isolation and Characterization of a Cholesterol-Lowering Bacteria from Bubalus bubalis Raw Milk

Probiotics retrieved from animal sources have substantial health benefits for both humans and animals. The present study was designed to identify lactic acid bacteria (LAB) isolated from domestic water buffalo milk (Bubalus bubalis) and to evaluate their potential as target-based probiotics. Forty-six LAB strains were isolated and, among them, five strains (NMCC-M2, NMCC-M4, NMCC-M5, NMCC-M6, and NMCC-M7) were regarded as possible probiotics on the basis of their phenotypic and biochemical properties. These isolates were molecularly identified as Weissella confusa (NMCC-M2), Leuconostoc pseudo-mesenteroides (NMCC-M4), Lactococcus lactis Subsp. hordniae (NMCC-M5), Enterococcus faecium NMCC-M6, and Enterococcus lactis NMCC-M7. The tested bacterial strains showed significant antimicrobial activity, susceptibility to antibiotics, acid and bile tolerance, sugar fermentation, enzymatic potential, and nonhemolytic characteristics. Interestingly, NMCC-M2 displayed the best probiotic features including survival at pH 3 and 0.5% (w/v) bile salts, complete susceptibility to the tested antibiotics, high enzymatic potential, and in vitro cholesterol reduction (48.0 µg/mL for NMCC-M2) with 0.3% bile salt supplementation. Therefore, the isolated strain NMCC-M2 could be considered as a potential target-based probiotic in cholesterol-lowering fermented food products.

Bifidobacterium animalis subsp. lactis HN019 Effects on Gut Health: A Review

Optimal gut motility is central to bowel function and gut health. The link between the gut dysmotility related disorders and dysfunctional-intestinal barriers has led to a hypothesis that certain probiotics could help in normalizing gut motility and maintain gut health. This review investigates the roles of Bifidobacterium animalis subsp. lactis HN019 (B. lactis HN019™) on gut health, and its mechanisms of action in various pre-clinical and clinical studies. Research supports the hypothesis that B. lactis HN019™ has a beneficial role in maintaining intestinal barrier function during gastrointestinal infections by competing and excluding potential pathogens via different mechanisms; maintaining normal tight junction function in vitro; and regulating host immune defense toward pathogens in both in vitro and human studies. This has been observed to lead to reduced incidence of diarrhea. Interestingly, B. lactis HN019™ also supports normal physiological function in immunosenescent elderly and competes and excludes potential pathogens. Furthermore, B. lactis HN019™ reduced intestinal transit time and increased bowel movement frequency in functional constipation, potentially by modulating gut–brain–microbiota axis, mainly via serotonin signaling pathway, through short chain fatty acids derived from microbial fermentation. B. lactis HN019™ is thus a probiotic that can contribute to relieving gut dysmotility related disorders.

Probiotic Bifidobacterium animalis subsp. lactis consumption slows down orthodontic tooth movement in mice

INTRODUCTION

Probiotics are live microorganisms that, when consumed in appropriate amount, can provide health benefits. Although many studies have shown positive results with the use of probiotics in bone loss control, as in periodontal disease, the effect of probiotics on a mechanical force-induced alveolar bone resorption is still unknown. Therefore, this study aimed to investigate the impact of the specific probiotic Bifidobacterium animalis subsp. lactis on bone remodeling induced by orthodontic tooth movement.

METHODS

For this study, thirty C57BL6/J male mice were used and divided into two groups: 1- Mice were orally treated with the probiotic; 2- Mice were treated with vehicle. All mice were submitted to the experimental model of orthodontic tooth movement (OTM). Bone parameters and OTM was evaluated by MicroCT. OTM and TRAP positive cells were analyzed by histomorphometric analysis. Osteoclasts markers were evaluated by qPCR and short chain fatty acids were measured in feces.

RESULTS

Micro-CT analysis showed that probiotic treatment did not modify the alveolar bone parameters. However, supplementation with probiotics restrained the tooth movement, as demonstrated by the reduced distance of OTM. Probiotic-treated mice presented down-regulation of Trap expression and reduced osteoclast numbers compared to the control. Accordingly, probiotics supplemented mice exhibited a higher concentration of short-chain fatty acid in their feces.

CONCLUSIONS

The supplementation with Bifidobacterium animalis subsp. lactis impaired tooth movement without altering the alveolar bone microarchitecture. The effect on bone remodeling induced by Bifidobacterium animalis subsp. lactis may be associated with the short-chain fatty acids' production.

Synbiotic Effect of Bifidobacterium lactis CNCM I-3446 and Bovine Milk-Derived Oligosaccharides on Infant Gut Microbiota

BACKGROUND

This study evaluated the impact of Bifidobacterium animalis ssp. lactis CNCM I-3446, Bovine Milk-derived OligoSaccharides (BMOS) and their combination on infant gut microbiota in vitro. In addition, a novel strategy consisting of preculturing B. lactis with BMOS to further enhance their potential synbiotic effects was assessed.

METHOD

Short-term fecal batch fermentations (48 h) were used to assess the microbial composition and activity modulated by BMOS alone, B. lactis grown on BMOS or dextrose alone, or their combinations on different three-month-old infant microbiota.

RESULTS

BMOS alone significantly induced acetate and lactate production (leading to pH decrease) and stimulated bifidobacterial growth in 10 donors. A further in-depth study on two different donors proved B. lactis ability to colonize the infant microbiota, regardless of the competitiveness of the environment. BMOS further enhanced this engraftment, suggesting a strong synbiotic effect. This was also observed at the microbiota activity level, especially in a donor containing low initial levels of bifidobacteria. In this donor, preculturing B. lactis with BMOS strengthened further the early modulation of microbiota activity observed after 6 h.

CONCLUSION

This study demonstrated the strong synbiotic effect of BMOS and B. lactis on the infant gut microbiota, and suggests a strategy to improve its effectiveness in an otherwise low-Bifidobacterium microbiota.

The Prospects for the Therapeutic Implications of Genetically Engineered Probiotics

The interest in the therapeutic use of probiotic microorganisms has been increased during the last decade although the doubts have ascended about the probiotics mainly because their beneficial effects are not fully understood, and, in many cases, their usefulness has not been validated in clinical trials. Consequently, the notion got a considerable interest in those strains having proven probiotic potential to be engineered for improvement in their beneficial features. The process of genetic engineering can also be used for probiotic strains for the reversion of antimicrobial resistance and other modifications for their safer and effective human applications. The lactic acid bacilli are predominantly opposite as they already have gained attention owing to their health-promoting benefits and their safety for human consumption; therefore, their use, especially as a delivery agent of vaccines and drugs, is gaining attention. The tailoring of probiotic strains will not only improve the data regarding the probiotic potential of these strains but also clinch the doubts concerning these probiotics. This article focuses on the approaches of bioengineered probiotics and discusses the potential prospects for their therapeutic applications including immunomodulation, cognitive health, and anticancer therapeutics.

Effects of 28-day Bifidobacterium animalis subsp. lactis HN019 supplementation on colonic transit time and gastrointestinal symptoms in adults with functional constipation: A double-blind, randomized, placebo-controlled, and dose-ranging trial

Bifidobacterium animalis subsp. lactis HN019 (HN019) ameliorates chronic idiopathic constipation. Our aim was to determine the efficacy and safety of 28-day supplementation with 1 × 109 or 1 × 1010 CFU of HN019/day for constipation. A total of 228 adults who were diagnosed with functional constipation according to the Rome III criteria were randomized in a double-blind and placebo-controlled trial. Colonic transit time (CTT), the primary outcome, and secondary outcomes that were measured using inventories-patient assessment of constipation symptoms (PAC-SYM) and quality of life (PAC-QoL), bowel function index (BFI), bowel movement frequency (BMF), stool consistency, degree of straining, bowel emptying, bloating, and pain severity-were assessed. Ancillary parameters and harms were also evaluated. There were no statistically significant differences in the primary or secondary outcomes between interventions. A post hoc analysis of 65 participants with fewer than 3 bowel movements per week (BMF ≤ 3/week) showed a physiologically relevant increase in weekly BMF in the high- (+2.0) and low-dose (+1.7) HN019 groups-by RMANOVA, the HN019 groups with BMF ≤ 3/week, pooled together, had a higher BMF versus placebo (P value = 0.01). Thus, improving low stool frequency could be a target of future interventions with HN019. High-dose HN019 also decreased the degree of straining at Day 28 versus placebo in those with BMF ≤ 3/week (P value = 0.02). Three unlikely related AEs-2 with low-dose HN019 and 1 with placebo-were followed until full recovery. In conclusion, although there were no differences in the primary analysis, HN019 is well tolerated and improves BMF in adults with low stool frequency.

Advanced glycation end products dietary restriction effects on bacterial gut microbiota in peritoneal dialysis patients; a randomized open label controlled trial

The modern Western diet is rich in advanced glycation end products (AGEs). We have previously shown an association between dietary AGEs and markers of inflammation and oxidative stress in a population of end stage renal disease (ESRD) patients undergoing peritoneal dialysis (PD). In the current pilot study we explored the effects of dietary AGEs on the gut bacterial microbiota composition in similar patients. AGEs play an important role in the development and progression of cardiovascular (CVD) disease. Plasma concentrations of different bacterial products have been shown to predict the risk of incident major adverse CVD events independently of traditional CVD risk factors, and experimental animal models indicates a possible role AGEs might have on the gut microbiota population. In this pilot randomized open label controlled trial, twenty PD patients habitually consuming a high AGE diet were recruited and randomized into either continuing the same diet (HAGE, n = 10) or a one-month dietary AGE restriction (LAGE, n = 10). Blood and stool samples were collected at baseline and after intervention. Variable regions V3-V4 of 16s rDNA were sequenced and taxa was identified on the phyla, genus, and species levels. Dietary AGE restriction resulted in a significant decrease in serum N^ε-(carboxymethyl) lysine (CML) and methylglyoxal-derivatives (MG). At baseline, our total cohort exhibited a lower relative abundance of Bacteroides and Alistipes genus and a higher abundance of Prevotella genus when compared to the published data of healthy population. Dietary AGE restriction altered the bacterial gut microbiota with a significant reduction in Prevotella copri and Bifidobacterium animalis relative abundance and increased Alistipes indistinctus, Clostridium citroniae, Clostridium hathewayi, and Ruminococcus gauvreauii relative abundance. We show in this pilot study significant microbiota differences in peritoneal dialysis patients’ population, as well as the effects of dietary AGEs on gut microbiota, which might play a role in the increased cardiovascular events in this population and warrants further studies.

Integrated Role of Bifidobacterium animalis subsp. lactis Supplementation in Gut Microbiota, Immunity, and Metabolism of Infant Rhesus Monkeys

To investigate the impact of probiotic supplementation of infant formula on immune parameters, intestinal microbiota, and metabolism, five individually housed infant rhesus monkeys exclusively fed standard infant formula supplemented with probiotics (Bifidobacterium animalis subsp. lactis HN019) from birth until 3 months of age were compared with five standard formula-fed and five breast-fed monkeys. Anthropometric measurements, serum insulin, immune parameters, fecal microbiota, and metabolic profiles of serum, urine, and feces were evaluated. Consumption of B. lactis-supplemented formula reduced microbial diversity, restructured the fecal microbial community, and altered the fecal metabolome at the last two time points, in addition to increasing short-chain fatty acids in serum and urine. Circulating CCL22 was lower and threonine, branched-chain amino acids, urea, and allantoin, as well as dimethylglycine in serum and urine, were increased in the group supplemented with B. lactis compared with the standard formula-fed group. These results support a role of probiotics as effectors of gut microbial activity regulating amino acid utilization and nitrogen cycling. Future risk-benefit analyses are still needed to consolidate the existing knowledge on the long-term consequences of probiotic administration during infancy. IMPORTANCE Probiotics are becoming increasingly popular due to their perceived effects on health, despite a lack of mechanistic information on how they impart these benefits. Infant formula and complementary foods are common targets for supplementation with probiotics. However, different probiotic strains have different properties, and there is a lack of data on long-term health effects on the consumer. Given the increasing interest in supplementation with probiotics and the fact that the gastrointestinal tracts of infants are still immature, we sought to determine whether consumption of infant formula containing the probiotic Bifidobacterium animalis subsp. lactis HN019 for 3 months starting at birth would impact gut microbial colonization, as well as infant immunity and metabolism, when compared with consumption of formula alone.

Benefits of Bifidobacterium animalis subsp. lactis Probiotic in Experimental Periodontitis

BACKGROUND

This study evaluates effects of topical administration of probiotic bacteria of the genus Bifidobacterium on experimental periodontitis (EP) in rats.

METHODS

Thirty-two rats were divided into groups C (control; without EP), EP (EP only), C-HN019 (control+probiotic), and EP-HN019 (EP+probiotic). On day 0 of the experiment, animals of groups EP and EP-HN019 received cotton ligatures around mandibular first molars (MFMs). In groups C-HN019 and EP-HN019, 1 mL of suspensions containing Bifidobacterium animalis subsp. lactis (B. lactis) HN019 was topically administered in the subgingival region of MFMs on days 0, 3, and 7. In groups C and EP, topical administrations were performed using a sham suspension (without probiotic). All animals were euthanized at day 14. Gingival tissue, hemimandibles, and oral biofilm were collected. Data were statistically analyzed (P <0.05).

RESULTS

Group EP presented greater bone porosity, trabecular separation, and connective tissue attachment loss (CTAL) as well as reduced bone volume than all other groups (P <0.05). In group EP-HN019, there were greater proportions of Actinomyces and Streptococcus-like species and lower proportions of Veillonella parvula, Capnocytophaga sputigena, Eikenella corrodens, and Prevotella intermedia-like species than group EP. Group EP-HN019 presented greater expressions of osteoprotegerin and β-defensins than group EP (P <0.05). Group EP presented greater levels of interleukin-1β and receptor activator of nuclear factor-kappa B ligand than group EP-HN019 (P <0.05).

CONCLUSION

Topical use of B. lactis HN019 promotes a protective effect against alveolar bone loss and CTALs attributable to EP in rats, modifying immunoinflammatory and microbiologic parameters.

Encapsulation of lactic acid bacteria in colloidosomes

Polymeric colloidosomes encapsulating viable lactic acid bacteria were prepared. An aqueous suspension of 153 nm poly(methyl methacrylate-co-butyl acrylate) latex particles plus Lactobacillus crispatus was emulsified in a continuous phase of sunflower oil. By adding a small amount of ethanol and salt to the oil phase, the latex particles at the surface of the emulsion droplets aggregate to form the colloidosome shells. The colloidosomes have been examined using optical, confocal, and scanning electron microscopies. The viability of the bacteria was tested using fluorescent molecular probes. The encapsulated lactic acid bacteria were able to metabolize glucose from solution and produce acid albeit at a slower rate compared to unencapsulated microbes. This demonstrates transport limitation through the colloidosome shell and restriction of the cellular metabolism due to encapsulation. Protection of the bacteria by encapsulation in colloidosomes was also demonstrated; a significantly larger number of encapsulated bacteria maintained viability in simulated stomach conditions compared to unencapsulated microbes.

The potential of bifidobacteria as a source of natural folate

AIMS

To screen 19 strains of bifidobacteria for main folate forms composition in synthetic folate-free and complex folate-containing media.

METHODS AND RESULTS

HPLC was used to analyse deconjugated folates extracted from bacterial biomass. Most strains had a total folate content above 4000 μg per 100 g dry matter (DM). The highest value of 9295 μg per 100 g DM was found in Bifidobacterium catenulatum ATCC 27539 and the lowest in Bifidobacterium animalis ssp. animalis ATCC 25527 containing 220 μg per 100 g DM. Ten strains grew in a synthetic folate-free medium (FFM), showing folate autotrophy and suggesting folate auxotrophy of the remaining nine. In the autotrophic strains, a consistently higher folate level was found in FFM as compared to a more complex folate-containing medium, suggesting reduced requirements for folates in the presence of growth factors otherwise requiring folates for synthesis. The contents of total folate, 5-CH(3) -H(4) folate and H(4) folate were strain dependent. 5-CH(3) -H(4) folate dominated in most strains.

CONCLUSIONS

Our results show that bifidobacteria folate content and composition is dynamic, is strain specific and depends on the medium. Suitable selection of the growth conditions can result in high levels of folate per cell unit biomass.

SIGNIFICANCE AND IMPACT OF THE STUDY

This suggests that certain bifidobacteria may contribute to the folate intake, either directly in foods, such as fermented dairy products, or in the intestine as folate-trophic probiotics or part of the natural microbiota.

Xylo-oligosaccharides and lactitol promote the growth of Bifidobacterium lactis and Lactobacillus species in pure cultures

The current screening study aimed at identifying promising prebiotic and synbiotic candidates. The fermentation of xylo-oligosaccharides, xylan, galacto-oligosaccharide, fructo-oligosaccharide, polydextrose, lactitol, gentiobiose and pullulan was investigated in vitro. The ability of these established and potential prebiotic candidates to function as a sole carbon source for probiotic (Bifidobacterium and Lactobacillus), intestinal and potential pathogenic microbes (Eubacterium, Bacteroides, Clostridium, Escherichia coli, Salmonella, and Staphylococcus) was assessed in pure cultures. Xylo-oligosaccharides were fermented with high specificity by the tested Bifidobacterium lactis strains and lactitol by lactobacilli, whereas galacto-oligosaccharides, fructo-oligosaccharides and gentiobiose were utilised by a larger group of microbes. Xylan, polydextrose and pullulan were utilised to a limited extent by only a few of the tested microbes. The results of this screening study indicate that xylo-oligosaccharides and lactitol support the growth of a limited number of beneficial microbes in pure cultures. Such a high degree of specificity has not been previously reported for established prebiotics. Based on these results, the most promising prebiotics and synbiotic combinations can be selected for further testing.

Xylo-oligosaccharides enhance the growth of bifidobacteria and Bifidobacterium lactis in a simulated colon model

A semi-continuous, anaerobic colon simulator, with four vessels mimicking the conditions of the human large intestine, was used to study the fermentation of xylo-oligosaccharides (XOS). Three XOS compounds and a xylan preparation were fermented for 48 hours by human colonic microbes. Fructo-oligosaccharides (FOS) were used as a prebiotic reference. As a result of the fermentation, the numbers of Bifidobacterium increased in all XOS and xylan simulations when compared to the growth observed in the baseline simulations, and increased levels of Bifidobacterium lactis were measured with the two XOS compounds that had larger distribution of the degree of polymerisation. Fermentation of XOS and xylan increased the microbial production of short chain fatty acids in the simulator vessels; especially the amounts of butyrate and acetate were increased. XOS was more efficient than FOS in increasing the numbers of B. lactis in the colonic model, whereas FOS increased the Bifidobacterium longum numbers more. The selective fermentation of XOS by B. lactis has been demonstrated in pure culture studies, and these results further indicate that the combination of B. lactis and XOS would form a successful, selective synbiotic combination.

Dose-response effect of Bifidobacterium lactis HN019 on whole gut transit time and functional gastrointestinal symptoms in adults

OBJECTIVE

To assess the impact of Bifidobacterium lactis HN019 supplementation on whole gut transit time (WGTT) and frequency of functional gastrointestinal (GI) symptoms in adults.

MATERIAL AND METHODS

We randomized 100 subjects (mean age: 44 years; 64% female) with functional GI symptoms to consume a proprietary probiotic strain, B. lactis HN019 (Fonterra Research Centre, Palmerston North, New Zealand), at daily doses of 17.2 billion colony forming units (CFU) (high dose; n = 33), 1.8 billion CFU (low dose; n = 33), or placebo (n = 34) for 14 days. The primary endpoint of WGTT was assessed by X-ray on days 0 and 14 and was preceded by consumption of radiopaque markers once a day for 6 days. The secondary endpoint of functional GI symptom frequency was recorded with a subject-reported numeric (1-100) scale before and after supplementation.

RESULTS

Decreases in mean WGTT over the 14-day study period were statistically significant in the high dose group (49 ± 30 to 21 ± 32 h, p < 0.001) and the low dose group (60 ± 33 to 41 ± 39 h, p = 0.01), but not in the placebo group (43 ± 31 to 44 ± 33 h). Time to excretion of all ingested markers was significantly shorter in the treatment groups versus placebo. Of the nine functional GI symptoms investigated, eight significantly decreased in frequency in the high dose group and seven decreased with low dose, while two decreased in the placebo group. No adverse events were reported in any group.

CONCLUSIONS

Daily B. lactis HN019 supplementation is well tolerated, decreases WGTT in a dose-dependent manner, and reduces the frequency of functional GI symptoms in adults.

Effects of Bifidobacterium lactis HN019 and prebiotic oligosaccharide added to milk on iron status, anemia, and growth among children 1 to 4 years old

OBJECTIVE

To evaluate the effect of Bifidobacterium lactis HN019 and prebiotic-fortified milk on iron status, anemia, and growth among 1- to 4-year-old children.

PATIENTS AND METHODS

In a community-based double-masked, controlled trial in a periurban population, 624 children were enrolled and randomly allocated to receive either milk fortified with additional probiotic and prebiotic (n = 312) or control milk (n = 312) for 1 year. Probiotic and prebiotic milk contained an additional 1.9 x 10 colony-forming units per day of probiotic B lactis HN019 and 2.4 g/day of prebiotic oligosaccharides milk. Hematological parameters were estimated at baseline and at the end of the study. Height and weight measurements were recorded at baseline, mid study, and the end of the study. Difference of means and multivariate regression models was used to examine the effect of intervention.

RESULTS

Both study groups were similar at baseline. Compliance was high (>85%) and did not vary by intervention groups. As compared with non-fortified milk, consumption of probiotic- and prebiotic-fortified milk for a period of 1 year reduced the risk of being anemic and iron deficient by 45% (95% CI 11%, 66%; P = 0.01) and increased weight gain by 0.13 kg/year (95% CI 0.03, 0.23; P = 0.02).

CONCLUSIONS

Preschoolers are usually fed milk, which has good acceptance and can be easily fortified for delivery of probiotics. Consumption of B lactis HN019 and prebiotic-fortified milk resulted in a smaller number of iron-deficient preschoolers and increased weight gain.

Bifidobacterium animalis causes extensive duodenitis and mild colonic inflammation in monoassociated interleukin-10-deficient mice

BACKGROUND

We recently showed that Bifidobacterium animalis is more prevalent within the colons of interleukin (IL)-10-deficient (-/-) mice than in wildtype (WT) animals colonized with the same specific pathogen-free (SPF) fecal contents. Here we tested the ability of this organism to cause T-cell-mediated intestinal inflammation by introducing it into germ-free (GF) IL-10-/- mice.

METHODS

GF IL-10-/- or WT mice were monoassociated with Bifidobacterium animalis subsp. animalis ATCC (American Type Culture Collection, Manassas, VA) 25527(T) or with B. infantis ATCC 15697(T). Inflammation was measured by blinded histologic scores of the duodenum, cecum, and colon and by spontaneous secretion of IL-12/IL-23 p40 from colonic explants. Bacterial antigen-specific CD4(+) mesenteric lymph node (MLN) T-cell recall responses were measured in response to antigen-presenting cells (APC) pulsed with bacterial lysates.

RESULTS

B. animalis caused marked duodenal inflammation and mild colitis in monoassociated IL-10-/- mice, whereas the intestinal tracts of WT animals remained free of inflammation. B. infantis colonization resulted in mild inflammation in the duodena of IL-10-/- mice. CD4(+) MLN T cells from B. animalis monoassociated IL-10-/- mice secreted high levels of IFN-gamma and IL-17 in response to B. animalis lysate. B. animalis equally colonized the different intestinal regions of WT and IL-10-/- mice.

CONCLUSIONS

B. animalis, a traditional probiotic species that is expanded in experimental colitis in this model, induces marked duodenal and mild colonic inflammation and TH1/TH17 immune responses when introduced alone into GF IL-10-/- mice. This suggests a potential pathogenic role for this commensal bacterial species in a susceptible host.

Exploring the diversity of the bifidobacterial population in the human intestinal tract

Although the health-promoting roles of bifidobacteria are widely accepted, the diversity of bifidobacteria among the human intestinal microbiota is still poorly understood. We performed a census of bifidobacterial populations from human intestinal mucosal and fecal samples by plating them on selective medium, coupled with molecular analysis of selected rRNA gene sequences (16S rRNA gene and internally transcribed spacer [ITS] 16S-23S spacer sequences) of isolated colonies. A total of 900 isolates were collected, of which 704 were shown to belong to bifidobacteria. Analyses showed that the culturable bifidobacterial population from intestinal and fecal samples include six main phylogenetic taxa, i.e., Bifidobacterium longum, Bifidobacterium pseudocatenulatum, Bifidobacterium adolescentis, Bifidobacterium pseudolongum, Bifidobacterium breve, and Bifidobacterium bifidum, and two species mostly detected in fecal samples, i.e., Bifidobacterium dentium and Bifidobacterium animalis subp. lactis. Analysis of bifidobacterial distribution based on age of the subject revealed that certain identified bifidobacterial species were exclusively present in the adult human gut microbiota whereas others were found to be widely distributed. We encountered significant intersubject variability and composition differences between fecal and mucosa-adherent bifidobacterial communities. In contrast, a modest diversification of bifidobacterial populations was noticed between different intestinal regions within the same individual (intrasubject variability). Notably, a small number of bifidobacterial isolates were shown to display a wide ecological distribution, thus suggesting that they possess a broad colonization capacity.

Probiotics: definition, sources, selection, and uses

Interest in probiotics is at an all-time high in the United States, driven in part by new products emerging in the market, by US researchers eager to evaluate efficacy claims rigorously, and by consumers interested in potential therapeutic and preventive health benefits. The US marketplace is a mixed bag of products, some well-defined and properly evaluated in controlled clinical studies and others with unsubstantiated claims of efficacy. Validation of probiotic contents in commercial products is needed to ensure consumer confidence. The term "probiotic" should be used only for products that meet the scientific criteria for this term-namely, products that contain an adequate dose of live microbes that have been documented in target-host studies to confer a health benefit. Probiotics must be identified to the level of strain, must be characterized for the specific health target, and must be formulated into products using strains and doses shown to be efficacious. Several characteristics commonly presumed to be essential to probiotics, such as human origin and the ability to improve the balance of the intestinal microbiota, are discussed.