Probiotic bacteria and intestinal epithelial barrier function

Department of Physiology and Pharmacology, Univ. of Calgary, 3330 Hospital Dr. NW, Calgary, AB, Canada T2N 4N1.
AJP Gastrointestinal and Liver Physiology (Impact Factor: 3.8). 03/2010; 298(6):G807-19. DOI: 10.1152/ajpgi.00243.2009
Source: PubMed


The intestinal tract is a diverse microenvironment where more than 500 species of bacteria thrive. A single layer of epithelium is all that separates these commensal microorganisms and pathogens from the underlying immune cells, and thus epithelial barrier function is a key component in the arsenal of defense mechanisms required to prevent infection and inflammation. The epithelial barrier consists of a dense mucous layer containing secretory IgA and antimicrobial peptides as well as dynamic junctional complexes that regulate permeability between cells. Probiotics are live microorganisms that confer benefit to the host and that have been suggested to ameliorate or prevent diseases including antibiotic-associated diarrhea, irritable bowel syndrome, and inflammatory bowel disease. Probiotics likely function through enhancement of barrier function, immunomodulation, and competitive adherence to the mucus and epithelium. This review summarizes the evidence about effects of the many available probiotics with an emphasis on intestinal barrier function and the mechanisms affected by probiotics.

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Available from: Wallace MacNaughton, Jun 11, 2014
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    • "In addition, the production of secretory IgA (SIgA) at the mucosal surfaces decreases with age and can lead to an increased risk of infection [10, 11]. SIgA, the predominant immunoglobulin class in human external secretions, is a key element in the maintenance of gut microbiota homeostasis and in the protection of gastrointestinal and respiratory tracts against pathogens [12] . Moreover, it has been also shown that the agedependent modifications of the composition of the gut microbiota also contribute to the defective local and systemic immune defenses in the elderly population [13, 14]. "
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    ABSTRACT: Bacillus probiotics health benefits have been until now quite poorly studied in the elderly population. This study aimed to assess the effects of Bacillus subtilis CU1 consumption on immune stimulation and resistance to common infectious disease (CID) episodes in healthy free-living seniors. One hundred subjects aged 60–74 were included in this randomized, double-blind, placebo-controlled, parallel-arms study. Subjects consumed either the placebo or the probiotic (2.10 9 B. subtilis CU1 spores daily) by short periodical courses of 10 days intermittently, alternating 18-day course of break. This scheme was repeated 4 times during the study. Symptoms of gastrointestinal and upper/lower respiratory tract infections were recorded daily by the subjects throughout the study (4 months). Blood, saliva and stool samples were collected in a predefined subset of the first forty-four subjects enrolled in the study. B. subtilis CU1 supplementation did not statistically significantly decrease the mean number of days of reported CID symptoms over the 4-month of study (probiotic group: 5.1 (7.0) d, placebo group: 6.6 (7.3) d, P = 0.2015). However, in the subset of forty-four randomized subjects providing biological samples, we showed that consumption of B. subtilis CU1 significantly increased fecal and salivary secretory IgA concentrations compared to the placebo. A post-hoc analysis on this subset showed a decreased frequency of respiratory infections in the probiotc group compared to the placebo group. Taken together, our study provides evidence that B. subtilis CU1 supplementation during the winter period may be a safe effective way to stimulate immune responses in elderly subjects.
    Full-text · Article · Dec 2015 · Immunity & Ageing
    • "A balanced composition of the gut microbiota plays an important role for health and prevention of disease, a topic that has been extensively reviewed by several authors (Sekirov et al. 2010; Wallace et al. 2011; Clemente et al. 2012). To obtain this balance, health promoting bacteria , probiotics, are important for modulating microbial composition to protect against infections and stimulate immune function (Ohland and MacNaughton 2010). Most bacterial strains classified as probiotics thus far belong to either bifidobacteria or lactobacilli (Kleerebezem and Vaughan 2009), but other genera of lactic acid bacteria (LAB) commonly found in fermented-foods and in the gastrointestinal tract of humans also contain probiotic candidates. "
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    ABSTRACT: In this work, we present the first XOS degrading glycoside hydrolase from Weissella, WXyn43, a two-domain enzyme from GH43. The gene was amplified from genomic DNA of the XOS utilizing Weissella strain 92, classified under the species-pair Weissella cibaria/W.confusa, and expressed in Escherichia coli. The enzyme is lacking a putative signal peptide and is, from a homology model, shown to be composed of an N-terminal 5-fold β-propeller catalytic domain and a C-terminal β-sandwich domain of unknown function. WXyn43 hydrolyzed short (1–4)-β-d-xylooligosaccharides, with similar kcat/KM for xylobiose (X2) and xylotriose (X3) and clearly lower efficiency in xylotetraose (X4) conversion. WXyn43 displays the highest reported kcat for conversion of X3 (900 s−1 at 37°C) and X4 (770 s−1), and kcat for hydrolysis of X2 (907 s−1) is comparable with or greater than the highest previously reported. The purified enzyme adopted a homotetrameric state in solution, while a truncated form with isolated N-terminal catalytic domain adopted a mixture of oligomeric states and lacked detectable activity. The homology model shows that residues from both domains are involved in monomer–monomer hydrogen bonds, while the bonds creating dimer–dimer interactions only involved residues from the N-terminal domain. Docking of X2 and X3 in the active site shows interactions corresponding to subsites −1 and +1, while presence of a third subsite is unclear, but interactions between a loop and the reducing-end xylose of X3 may be present.
    No preview · Article · Oct 2015 · Glycobiology
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    • "Furthermore, they are able to improve the epithelial barrier in several ways, depending on the used bacterial strain (Anderson et al., 2010; Miyauchi et al., 2012). They can increase the mucus production of the goblet cells, they are able to stabilise the tight junctions between the epithelial cells and they can enhance IgA production (Ohland and Macnaughton, 2010). Probiotics can also have an indirect effect on the resident microbiota. "
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    ABSTRACT: Migraine prevalence is associated with gastrointestinal disorders. Possible underlying mechanisms could be increased gut permeability and inflammation. Probiotics may decrease intestinal permeability as well as inflammation, and therefore may reduce the frequency and/or intensity of migraine attacks. Therefore we assessed feasibility, possible clinical efficacy, and adverse reactions of probiotic treatment in migraine patients. 29 migraine patients took 2 g/d of a probiotic food supplement (Ecologic®Barrier, 2.5×109 cfu/g) during 12 weeks. Participants recorded frequency and intensity of migraine in a headache diary and completed the Migraine Disability Assessment Scale (MIDAS) and Henry Ford Hospital Headache Disability Inventory (HDI) at baseline and after 12 weeks of treatment. Compliance was measured every 4 weeks by counting the remaining sachets with probiotics. The study was completed by 27/29 (93%) patients who took 95% of the supplements. Obstipation was reported by 4 patients during the first 2 weeks of treatment only. The mean±standard deviation (SD) number of migraine days/month decreased significantly from 6.7±2.4 at baseline to 5.1±2.2 (P=0.008) in week 5-8 and 5.2±2.4 in week 9-12 (P=0.001). The mean±SD intensity of migraine decreased significantly from 6.3±1.5 at baseline to 5.5±1.9 after treatment (P=0.005). The MIDAS score improved from 24.8±25.5 to 16.6±13.5 (P=0.031). However, the mean HDI did not change significantly. In conclusion, probiotics may decrease migraine supporting a possible role for the intestine in migraine management. Feasibility and lack of adverse reactions justify further placebo-controlled studies.
    Full-text · Article · Apr 2015 · Beneficial Microbes
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