Maturation of Gut Microbiota and Circulating Regulatory T Cells and Development of IgE Sensitization in Early Life.

Recent studies suggest that the cross-talk between the gut microbiota and human immune system during the first year of life is an important regulator of the later development of atopic diseases. We explored the changes in the gut microbiota, blood regulatory T cells, and atopic sensitization in a birth-cohort of Estonian and Finnish children followed from 3 to 36 months of age. We describe here an infant Treg phenotype characterized by high Treg frequency, the maturation of Treg population characterized by a decrease in their frequency accompanied with an increase in the highly activated Treg cells. These changes in Treg population associated first with the relative abundance of Bifidobacterium longum followed by increasing colonization with butyrate producing bacteria. High bifidobacterial abundance in the neonatal microbiota appeared to be protective, while colonization with Bacteroides and E. coli was associated with later risk of allergy. Estonian children with lower risk of IgE mediated allergic diseases than Finnish children showed an earlier maturation of the gut microbiota, detected as earlier switch to an increasing abundance of butyrate-producing bacteria, combined with an earlier maturation of Treg cell phenotype and total IgE production. The children with established allergic diseases by age 3 showed a decreased abundance of butyrate producing Faecalibacterium. These results suggest that as well as the maintenance of a bifidobacterial dominated gut microbiota is important during the first weeks of life, the overtake by butyrate producing bacteria seems to be a beneficial shift, which should not be postponed.

Aberrant gut microbiota composition at the onset of type 1 diabetes in young children.

AIMS/HYPOTHESIS: Recent studies indicate that an aberrant gut microbiota is associated with the development of type 1 diabetes, yet little is known about the microbiota in children who have diabetes at an early age. To this end, the microbiota of children aged 1-5 years with new-onset type 1 diabetes was compared with the microbiota of age-matched healthy controls. METHODS: A deep global analysis of the gut microbiota composition was established by phylogenetic microarray analysis using a Human Intestinal Tract Chip (HITChip). RESULTS: Principal component analyses highlighted the importance of age when comparing age-matched pairs. In pairs younger than 2.9 years, the combined abundance of the class Bacilli (notably streptococci) and the phylum Bacteroidetes was higher in diabetic children, whereas the combined abundance of members of Clostridium clusters IV and XIVa was higher in the healthy controls. Controls older than 2.9 years were characterised by a higher fraction of butyrate-producing species within Clostridium clusters IV and XIVa than was seen in the corresponding diabetic children or in children from the younger age groups, while the diabetic children older than 2.9 years could be differentiated by having an increased microbial diversity. CONCLUSIONS/INTERPRETATION: The results from both age groups suggest that non-diabetic children have a more balanced microbiota in which butyrate-producing species appear to hold a pivotal position.

Effects of wheat bran extract containing arabinoxylan oligosaccharides on gastrointestinal parameters in healthy preadolescent children.

OBJECTIVES: We assessed whether wheat bran extract (WBE) containing arabinoxylan-oligosaccharides (AXOS) elicited a prebiotic effect and modulated gastrointestinal (GI) parameters in healthy preadolescent children upon consumption in a beverage. METHODS: This double-blind randomized placebo-controlled crossover trial evaluated the effects of consuming WBE at 0 (control) or 5.0 g/day for 3 weeks in 29 healthy children (8-12 years). Fecal levels of microbiota, short-chain fatty acids, branched-chain fatty acids, ammonia, moisture, and fecal pH were assessed at the end of each treatment and at the end of a 1-week run-in (RI) period. In addition, the subjects completed questionnaires scoring distress severity of 3 surveyed GI symptoms. Finally, subjects recorded defecation frequency and stool consistency. RESULTS: Nominal fecal bifidobacteria levels tended to increase after 5 g/day WBE consumption (P = 0.069), whereas bifidobacteria expressed as percentage of total fecal microbiota was significantly higher upon 5 g/day WBE intake (P = 0.002). Additionally, 5 g/day WBE intake induced a significant decrease in fecal content of isobutyric acid and isovaleric acid (P < 0.01), markers of protein fermentation. WBE intake did not cause a change in distress severity of the 3 surveyed GI symptoms (flatulence, abdominal pain/cramps, and urge to vomit) (P > 0.1). CONCLUSIONS: WBE is well tolerated at doses up to 5 g/day in healthy preadolescent children. In addition, the intake of 5 g/day exerts beneficial effects on gut parameters, in particular an increase in fecal bifidobacteria levels relative to total fecal microbiota, and reduction of colonic protein fermentation.

Fecal microbiota composition differs between children with ß-cell autoimmunity and those without.

The role of the intestinal microbiota as a regulator of autoimmune diabetes in animal models is well-established, but data on human type 1 diabetes are tentative and based on studies including only a few study subjects. To exclude secondary effects of diabetes and HLA risk genotype on gut microbiota, we compared the intestinal microbiota composition in children with at least two diabetes-associated autoantibodies (n = 18) with autoantibody-negative children matched for age, sex, early feeding history, and HLA risk genotype using pyrosequencing. Principal component analysis indicated that a low abundance of lactate-producing and butyrate-producing species was associated with ß-cell autoimmunity. In addition, a dearth of the two most dominant Bifidobacterium species, Bifidobacterium adolescentis and Bifidobacterium pseudocatenulatum, and an increased abundance of the Bacteroides genus were observed in the children with ß-cell autoimmunity. We did not find increased fecal calprotectin or IgA as marker of inflammation in children with ß-cell autoimmunity. Functional studies related to the observed alterations in the gut microbiome are warranted because the low abundance of bifidobacteria and butyrate-producing species could adversely affect the intestinal epithelial barrier function and inflammation, whereas the apparent importance of the Bacteroides genus in development of type 1 diabetes is insufficiently understood.

Effects of a wheat bran extract containing arabinoxylan oligosaccharides on gastrointestinal health parameters in healthy adult human volunteers: a double-blind, randomised, placebo-controlled, cross-over trial.

Wheat bran extract (WBE) is a food-grade soluble fibre preparation that is highly enriched in arabinoxylan oligosaccharides. In this placebo-controlled cross-over human intervention trial, tolerance and effects on colonic protein and carbohydrate fermentation were studied. After a 1-week run-in period, sixty-three healthy adult volunteers consumed 3, 10 and 0 g WBE/d for 3 weeks in a random order, with 2 weeks' washout between each treatment period. Fasting blood samples were collected at the end of the run-in period and at the end of each treatment period for analysis of haematological and clinical chemistry parameters. Additionally, subjects collected a stool sample for analysis of microbiota, SCFA and pH. A urine sample, collected over 48 h, was used for analysis of p-cresol and phenol content. Finally, the subjects completed questionnaires scoring occurrence frequency and distress severity of eighteen gastrointestinal symptoms. Urinary p-cresol excretion was significantly decreased after WBE consumption at 10 g/d. Faecal bifidobacteria levels were significantly increased after daily intake of 10 g WBE. Additionally, WBE intake at 10 g/d increased faecal SCFA concentrations and lowered faecal pH, indicating increased colonic fermentation of WBE into desired metabolites. At 10 g/d, WBE caused a mild increase in flatulence occurrence frequency and distress severity and a tendency for a mild decrease in constipation occurrence frequency. In conclusion, WBE is well tolerated at doses up to 10 g/d in healthy adults volunteers. Intake of 10 g WBE/d exerts beneficial effects on gut health parameters.

Consumption of breads containing in situ-produced arabinoxylan oligosaccharides alters gastrointestinal effects in healthy volunteers.

Arabinoxylan oligosaccharides (AXOS) are studied as food compounds with prebiotic potential. Here, the impact of consumption of breads with in situ-produced AXOS on intestinal fermentation and overall gastrointestinal characteristics was evaluated in a completely randomized, double-blind, controlled, cross-over study. Twenty-seven healthy volunteers consumed 180 g of wheat/rye bread with or without in situ-produced AXOS (WR(+) and WR(-), respectively) daily for 3 wk. Consumption of WR(+) corresponded to an AXOS intake of ~2.14 g/d. Refined wheat flour bread without AXOS (W(-)) (180 g/d) was provided during the 3-wk run-in and wash-out periods. At the end of each treatment period, participants collected urine for 48 h as well as a feces sample. Additionally, all participants completed a questionnaire about stool characteristics and gastrointestinal symptoms during the last week of each period. Urinary phenol and p-cresol excretions were significantly lower after WR(+) intake compared to WR(-). Consumption of WR(+) significantly increased fecal total SCFA concentrations compared to intake of W(-). The effect of WR(+) intake was most pronounced on butyrate, with levels 70% higher than after consumption of W(-) in the run-in or wash-out period. Consumption of WR(+) tended to selectively increase the fecal levels of bifidobacteria (P = 0.06) relative to consumption of W(-). Stool frequency increased significantly after intake of WR(+) compared to WR(-). In conclusion, consumption of breads with in situ-produced AXOS may favorably modulate intestinal fermentation and overall gastrointestinal properties in healthy humans.

New prebiotic blend of polydextrose and galacto-oligosaccharides has a bifidogenic effect in young infants.

OBJECTIVE: The aim of the study was to evaluate the effect of infant formula with polydextrose (PDX) and galacto-oligosaccharides (GOS) on fecal microbiota and secretory IgA (sIgA). MATERIALS AND METHODS: In the present double-blind, randomized study, term infants received control (Enfamil Lipil) or the same formula with PDX/GOS (4 g/L, 1:1 ratio; PDX/GOS) for 60 days; a reference breast-fed group was included. Formula intake, tolerance, and stool characteristics were collected via electronic diary and analyzed by repeated measures analysis of variance. Anthropometric measurements and stool samples were obtained at baseline and after 30 and 60 days of feeding. Fecal sIgA was measured by enzyme-linked immunosorbent assay and fecal bacteria by fluorescent in situ hybridization and quantitative real-time polymerase chain reaction (qPCR); both were analyzed by Wilcoxon rank sum test. RESULTS: Two hundred thirty infants completed the study. Infants consuming PDX/GOS had softer stools than control at all times (P < 0.001). Using qPCR, counts in PDX/GOS were closer to the breast-fed group, tended to be higher than control for total bifidobacteria (P = 0.069) and Bifidobacterium longum (P = 0.057) at 30 days, and were significantly higher for total bifidobacteria and B longum at 60 days and B infantis at 30 days (P = 0.002). No significant differences were detected between PDX/GOS and control in changes from baseline to 30 or 60 days for sIgA or total bifidobacteria by fluorescent in situ hybridization or qPCR; however, significantly higher changes from baseline were detected between PDX/GOS and control for B infantis at 30 days and B longum at 60 days (P ≤ 0.035). CONCLUSIONS: Infant formula with PDX/GOS produces soft stools and a bifidogenic effect closer to breast milk than formula without PDX/GOS.

Design and application of group-specific oligonucleotide probes for detecting and monitoring mouse clostridia.

Clostridia dominate the rodent intestinal bacterial community and play an important role in physiological functions of the host. However, their ecology and diversity are still unclear. In our previous report, we showed that phylogenetically novel groups of clostridia inhabit the mouse intestine and contribute to the normalization of germfree mice. In this study, five new oligonucleotide probes were designed and applied to detect these clostridial groups that are essential for the normalization of germfree mice. Faecal microbiota of conventional mouse strains and specific pathogen-free mice from different breeding colonies were analysed by fluorescence in situ hybridization using these five probes. Our results showed that the composition of clostridia differed among mouse strains and also among mouse groups of the same inbred strain from different breeding colonies. These five new probes for mouse clostridia were able to detect the difference in clostridial diversity in each mouse group. In addition to Clostridium, we also analysed Bacteroides and Lactobacillus using previously described probes and the number or the frequency of occurrence of Bacteroides was shown to be different among mouse groups analysed. The oligonucleotide probe set including our newly developed and previously described probes used in this study can be applied to monitoring of significant groups of mouse intestinal microbiota.

Microbiota profile in feces of breast- and formula-fed newborns by using fluorescence in situ hybridization (FISH).

The development of the gut is controlled and modulated by different interacting mechanisms such as, genetic endowment, intrinsic biological regulatory functions, environment influences and last but no least, the diet influence. Considered together with other endogenous and exogenous factors the type of feeding may interfere greatly in the regulation of the intestinal microbiota. During the last years molecular methods offer a complementarity to the classic culture-based knowledge. FISH has been applied for molecular evaluation of the microbiota in newborns delivered by vaginal delivery. Eleven probes/probe combinations for specific groups of faecal bacteria were used to determine the bacterial composition in faecal samples of newborns infants under different types of feeding. Breast-fed infants harbor a fecal microbiota by more than two times increased in numbers of Bifidobacterium cells when compared to formula-fed infants. After formula-feeding, Atopobium was found in significant counts and the numbers of Bifidobacterium dropped followed by increasing numbers in Bacteroides population. Moreover, under formula feeding the infants microbiota was more diverse.

Impact of digestive and oropharyngeal decontamination on the intestinal microbiota in ICU patients.

PURPOSE: Selective digestive microbial decontamination (SDD) is hypothesized to benefit patients in intensive care (ICU) by suppressing Gram-negative potential pathogens from the colon without affecting the anaerobic intestinal microbiota. The purpose of this study was to provide more insight to the effects of digestive tract and oropharyngeal decontamination on the intestinal microbiota by means of a prospective clinical trial in which faecal samples were collected from ICU patients for intestinal microbiota analysis. METHODS: The faecal samples were collected from ICU patients enrolled in a multicentre trial to study the outcome of SDD and selective oral decontamination (SOD) in comparison with standard care (SC). Fluorescent in situ hybridization (FISH) was used to analyze the faecal microbiota. The numbers of bacteria from different bacterial groups were compared between the three regimens. RESULTS: The total counts of bacteria per gram faeces did not differ between regimens. The F. prausnitzii group of bacteria, representing an important group among intestinal microbiota, was significantly reduced in the SDD regimen compared to the SC and SOD. The Enterobacteriaceae were significantly suppressed during SDD compared to both SOD and SC; enterococci increased in SDD compared to both other regimens. CONCLUSIONS: The composition of the intestinal microbiota is importantly affected by SDD. The F. prausnitzii group was significantly suppressed during SDD. This group of microbiota is a predominant producer of butyrate, the main energy source for colonocytes. Reduction of this microbiota is an important trade-off while reducing gram-negative bacteria by SDD.

Association between Faecalibacterium prausnitzii and dietary fibre in colonic fermentation in healthy human subjects.

The intestinal microbiota are a complex ecosystem influencing the immunoregulation of the human host, providing protection from colonising pathogens and producing SCFA as the main energy source of colonocytes. Our objective was to investigate the effect of dietary fibre exclusion and supplementation on the intestinal microbiota and SCFA concentrations. Faecal samples were obtained from healthy volunteers before and after two 14 d periods of consuming formulated diets devoid or supplemented with fibre (14 g/l). The faecal microbiota were analysed using fluorescent in situ hybridisation and SCFA were measured using GLC. There were large and statistically significant reductions in the numbers of the Faecalibacterium prausnitzii (P < or = 0.01) and Roseburia spp. (P < or = 0.01) groups during both the fibre-free and fibre-supplemented diets. Significant and strong positive correlations between the proportion of F. prausnitzii and the proportion of butyrate during both baseline normal diets were found (pre-fibre free r 0.881, P = 0.001; pre-fibre supplemented r 0.844, P = 0.002). A significant correlation was also found between the proportional reduction in F. prausnitzii and the proportional reduction in faecal butyrate during both the fibre-free (r 0.806; P = 0.005) and the fibre-supplemented diet (r 0.749; P = 0.013). These findings may contribute to the understanding of the association between fibre, microbiota and fermentation in health, during enteral nutrition and in disease states such as Crohn's disease.

The species composition of the human intestinal microbiota differs between particle-associated and liquid phase communities.

Many of the substrates available as energy sources for microorganisms in the human colon, including dietary plant fibre and secreted mucin, are insoluble. It seems likely that such insoluble substrates support a specialized microbiota, and in order to test this hypothesis, faecal samples from four healthy subjects were fractionated into insoluble (washed particulate) and liquid fractions. Analysis of 1252 PCR-amplified 16S rRNA sequences revealed a significantly lower percentage of Bacteroidetes (P = 0.021) and a significantly higher percentage of Firmicutes (P = 0.029) among bacterial sequences amplified from particle-associated (mean 76.8% Firmicutes, 18.5% Bacteroidetes) compared with liquid phase (mean 65.8% Firmicutes, 28.5% Bacteroidetes). Within the Firmicutes, the most significant association with solid particles was found for relatives of Ruminococcus-related clostridial cluster IV species that include Ruminococcus flavefaciens and R. bromii, which together accounted for 12.2% of particle-associated, but only 3.3% of liquid phase, sequences. These findings were strongly supported by microscopy, using group-specific FISH probes able to detect these species. This work suggests that the primary colonizers of insoluble substrates found in the gut are restricted to certain specialized groups of bacteria. The abundance of such primary degraders may often be underestimated because of the difficulty in recovering these bacteria and their nucleic acids from the insoluble substrate.

Differential analysis of protein expression of Bifidobacterium grown on different carbohydrates.

We observed recently that colonic fermentation of lactose might be a major factor in the pathophysiology of lactose intolerance. Proteomic techniques could be helpful in interpreting the metabolic pathways of lactose fermentation. The objective of this study was to explore proteomic methodologies for studying bacterial lactose metabolism that can be used to detect and identify proteins associated with the onset of intolerance symptoms. Differential expression of cytoplasmic proteins of Bifidobacterium animalis, Bifidobacterium breve and Bifidobacterium longum grown on different carbohydrates (lactose, glucose, galactose) was analyzed with surface-enhanced laser desorption ionization-time of flight (SELDI-TOF) MS and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). After fractionation by SDS-PAGE, differentially-expressed proteins were identified with LC-MS/MS. The three strains grown on the same carbohydrate or the same strain grown on glucose or lactose showed differences in SELDI-TOF MS protein profiles. Differences in protein expression were observed in B. breve grown on glucose, galactose or lactose as analyzed with SDS-PAGE. With LC-MS/MS, proteins from Bifidobacterium were identified, which included enzymes for metabolism of lactose, glucose and galactose. In conclusion, the applied techniques can discern differences in protein expression of bacteria metabolizing different carbohydrates. These techniques are promising in studying metabolism of lactose and other substrates in a complex bacterial ecosystem such as the colonic microbiota.

Denaturing gradient gel electrophoresis as a diagnostic tool in periodontal microbiology.

Bacteria play an important role in the initiation and progression of periodontal diseases and are part of a biofilm, which can contain over 100 different species. The aim of the present study was to show the potential of denaturing gradient gel electrophoresis (DGGE) as a tool for the detection of clinically relevant species and to compare the results of detection by DGGE with those by PCR and culturing. Hybridization of the bands from the DGGE profiles with species-specific probes was developed to confirm the band positions in the marker obtained with reference strains. The sensitivities of DGGE compared to those of cultivation for the detection of Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, and Tannerella forsythensis were 100, 100, 88, and 100%, respectively; and the sensitivities of DGGE compared to those of PCR were 100, 90, 88, and 96%, respectively. DGGE as a diagnostic tool could easily be extended to other species, as shown for Treponema denticola, which could be detected in 48% of the samples. Three different groups of A. actinomycetemcomitans serotypes could be distinguished by DGGE (i.e., a group comprising serotypes a, d, e, and f; a group comprising serotype b; and a group comprising serotype c). Amplicons from P. gingivalis and T. denticola migrated to the same position in the gel, and P. intermedia produced multiple bands. In the present study we show that the DGGE profiles represent clinically relevant species which can be detected by hybridization with species-specific probes. With DGGE, large numbers of samples can be analyzed for different species simultaneously, and DGGE may be a good alternative in periodontal microbial diagnostics.

Molecular diversity, cultivation, and improved detection by fluorescent in situ hybridization of a dominant group of human gut bacteria related to Roseburia spp. or Eubacterium rectale.

Phylogenetic analysis was used to compare 16S rRNA sequences from 19 cultured human gut strains of Roseburia and Eubacterium rectale with 356 related sequences derived from clone libraries. The cultured strains were found to represent five of the six phylotypes identified. A new oligonucleotide probe, Rrec584, and the previous group probe Rint623, when used in conjunction with a new helper oligonucleotide, each recognized an average of 7% of bacteria detected by the eubacterial probe Eub338 in feces from 10 healthy volunteers. Most of the diversity within this important group of butyrate-producing gut bacteria can apparently be retrieved through cultivation.

Lupin kernel fiber consumption modifies fecal microbiota in healthy men as determined by rRNA gene fluorescent in situ hybridization.

BACKGROUND: Changes in the composition of gastrointestinal microbiota by dietary interventions using pro- and prebiotics provide opportunity for improving health and preventing disease. However, the capacity of lupin kernel fiber (LKFibre), a novel legume-derived food ingredient, to act as a prebiotic and modulate the colonic microbiota in humans needed investigation. AIM OF THE STUDY: The present study aimed to determine the effect of LKFibre on human intestinal microbiota by quantitative fluorescent in situ hybridization (FISH) analysis. DESIGN: A total of 18 free-living healthy males between the ages of 24 and 64 years consumed a control diet and a LKFibre diet (containing an additional 17-30 g/day fiber beyond that of the control-incorporated into daily food items) for 28 days with a 28-day washout period in a single-blind, randomized, crossover dietary intervention design. METHODS: Fecal samples were collected for 3 days towards the end of each diet and microbial populations analyzed by FISH analysis using 16S rRNA gene-based oligonucleotide probes targeting total and predominant microbial populations. RESULTS: Significantly higher levels of Bifidobacterium spp. (P = 0.001) and significantly lower levels of the clostridia group of C. ramosum, C. spiroforme and C. cocleatum (P = 0.039) were observed on the LKFibre diet compared with the control. No significant differences between the LKFibre and the control diet were observed for total bacteria, Lactobacillus spp., the Eubacterium spp., the C. histolyticum/C. lituseburense group and the Bacteroides-Prevotella group. CONCLUSIONS: Ingestion of LKFibre stimulated colonic bifidobacteria growth, which suggests that this dietary fiber may be considered as a prebiotic and may beneficially contribute to colon health.

Colonic fermentation may play a role in lactose intolerance in humans.

The results of our previous study suggested that in addition to the small intestinal lactase activity and transit time, colonic processing of lactose may play a role in lactose intolerance. We investigated whether colonic fermentation of lactose is correlated with lactose intolerance. After 28 Chinese subjects had undergone 1 glucose (placebo) and 2 lactose challenges, consistent lactose tolerant (n = 7) and intolerant (n = 5) subjects with no complaints after glucose administration were classified on the basis of the 6-h symptom scores. Before the challenges, fecal samples were collected for in vitro incubation with lactose. The incubation was carried out in a static system under anaerobic conditions for 5 h during which samples were taken for measurement of short-chain fatty acids, lactate, lactose, glucose, and galactose. Fecal bacterial composition was determined by fluorescent in situ hybridization. The tolerant and intolerant groups did not differ in the rate or degree of hydrolysis of lactose or production of glucose and galactose. The intolerant group produced d- and l-lactate, acetate, propionate, and butyrate significantly faster than the tolerant group. In the intolerant group, the amounts of acetate, propionate, butyrate, and l-lactate produced were higher than those in the tolerant group. Fecal bacterial composition did not differ between the 2 groups. The results indicate that the degree and rate of lactose hydrolysis in the colon do not play a role in lactose intolerance. However, after lactose is hydrolyzed, a faster and higher production of microbial intermediate and end metabolites may be related to the occurrence of symptoms.

Identification of bacteria with beta-galactosidase activity in faeces from lactase non-persistent subjects.

Previous studies suggest that, besides the maldigestion of lactose in the small intestine, the colonic processing of lactose might play a role in lactose intolerance. beta-Galactosidase is the bacterial enzyme which catalyzes the first step of lactose fermentation in the colon. We propose a practical method to differentiate and identify bacteria with beta-galactosidase activity in faeces which combines a colony-lift filter assay with X-gal (5-bromo-4-chloro-3-indolyl-beta-d-galactopyranoside) as substrate for differentiation and the fluorescent in situ hybridization technique for identification. The method was applied to faeces from lactase non-persistent subjects. After 28 subjects had undergone one glucose and two lactose challenges, consistent intolerant (n=5) and tolerant (n=7) groups were defined according to their symptom scores. Of the 28 faecal samples, 80.6% (mean, SD: 12.1, range: 47.8-100%) of the total cultured bacteria were found to possess beta-galactosidase activity, which indicates that the bacterial beta-galactosidase is abundant in the colon. The tolerant and intolerant groups did not differ in the percentage or composition of the bacteria with beta-galactosidase activity or beta-galactosidase activity in faeces. Results suggest that the percentage or composition of the bacteria with beta-galactosidase activity in faeces do not play a role in lactose intolerance.

Fecal microbiota composition and frailty.

The relationship between fecal microbiota composition and frailty in the elderly was studied. Fecal samples from volunteers with high frailty scores showed a significant reduction in the number of lactobacilli (26-fold). At much higher population levels, both the Bacteroides/Prevotella (threefold) and the Faecalibacterium prausnitzii (fourfold) groups showed a significant reduction in percentage of total number of hybridizable bacteria in the elderly with high frailty scores. In contrast to this, the number of Enterobacteriaceae was significantly higher (sevenfold) in samples from very frail volunteers.

Reduction of colitis by prebiotics in HLA-B27 transgenic rats is associated with microflora changes and immunomodulation.

HLA-B27 transgenic rats develop spontaneous colitis under specific pathogen-free conditions (SPF) but germ-free rats remain disease-free, emphasizing a role for intestinal bacteria in the pathogenesis of chronic intestinal inflammation. Prebiotics are dietary substances that affect the host by stimulating growth and/or activity of potentially health promoting bacteria. The aims of this study were to investigate whether prebiotics can prevent colitis in SPF HLA-B27 rats, and secondly, to explore mechanisms of protection. SPF HLA-B27 transgenic rats received orally the prebiotic combination long-chain inulin and oligofructose (Synergy 1), or not, prior to the development of clinically detectable colitis. After seven weeks, cecal and colonic tissues were collected for gross cecal scores (GCS), histologic inflammatory scores (scale 0-4), and mucosal cytokine measurement. Cecal and colonic contents were collected for analysis of the gut microbiota by PCR-denaturing gradient gel electrophoresis (PCR-DGGE) and fluorescent in-situ hybridization (FISH), and analysis of short-chain fatty acid composition. Prebiotic treatment significantly decreased GCS and inflammatory histologic scores in the cecum and colon. Prebiotic treatment also decreased cecal IL-1beta, but increased cecal TGF-beta concentrations. Inulin/oligofructose altered the cecal and colonic PCR-DGGE profiles, and FISH analysis showed significant increases in cecal Lactobacillus and Bifidobacterium populations after prebiotic treatment compared with water-treated rats. In conclusion, the prebiotic combination Synergy 1 reduced colitis in HLA-B27 transgenic rats, which effect was associated with alterations to the gut microbiota, decreased tissue proinflammatory cytokines and increased immunomodulatory molecules. These results show promise for prebiotics as primary or adjuvant maintenance therapy for chronic inflammatory bowel diseases.