Amel Taibi

Practical approaches to probiotics use

Probiotics are microorganisms exerting beneficial effects on the host. They can be ingested through foods or supplements and their inclusion in these products is regulated in Canada by the Health Canada Health Products and Food Branch. The aim of this article is to summarize current evidence from randomized controlled trials and guidelines from Health Canada, the World Health Organization, and internationally recognized expert committees in the hope that it will help practitioners and professionals recommending probiotics to healthy and diseased patients, with a focus on the Canadian setting. From a general perspective, probiotics can be recommended for prevention of diseases that are associated to altered intestinal ecology. Specifically, they can be recommended for prevention of upper respiratory tract infections and pouchitis, for prevention and management of necrotizing enterocolitis, bacterial vaginosis and antibiotic associated diarrhea, including Clostridium difficile infection, and for treatment of atopic eczema in cows milk allergy and of infectious diarrhea. Additional substantiated probiotic benefits include prevention of hypercholesterolemia, management of constipation, reduction of recurrent urinary tract infections, improvement of irritable bowel syndrome symptoms, and reduction of antibiotics side effects in Helicobacter pylori eradication. Because probiotics are generally recognized as safe and can be removed with antimicrobial agents, their use should be considered in patients of all ages.

Nonalcoholic fatty liver disease is associated with dysbiosis independent of body mass index and insulin resistance

This study aimed to determine if there is an association between dysbiosis and nonalcoholic fatty liver disease (NAFLD) independent of obesity and insulin resistance (IR). This is a prospective cross-sectional study assessing the intestinal microbiome (IM) of 39 adults with biopsy-proven NAFLD (15 simple steatosis [SS]; 24 nonalcoholic steatohepatitis [NASH]) and 28 healthy controls (HC). IM composition (llumina MiSeq Platform) in NAFLD patients compared to HC were identified by two statistical methods (Metastats, Wilcoxon). Selected taxa was validated using quantitative PCR (qPCR). Metabolites in feces and serum were also analyzed. In NAFLD, 8 operational taxonomic units, 6 genera, 6 families and 2 phyla (Bacteroidetes, Firmicutes) were less abundant and; 1 genus (Lactobacillus) and 1 family (Lactobacillaceae) were more abundant compared to HC. Lower abundance in both NASH and SS patients compared to HC were confirmed by qPCR for Ruminococcus, Faecalibacterium prausnitzii and Coprococcus. No difference was found between NASH and SS. This lower abundance in NAFLD (NASH+SS) was independent of BMI and IR. NAFLD patients had higher concentrations of fecal propionate and isobutyric acid and serum 2-hydroxybutyrate and L-lactic acid. These findings suggest a potential role for a specific IM community and functional profile in the pathogenesis of NAFLD.

Omega-3 Polyunsaturated Fatty Acids Time-Dependently Reduce Cell Viability and Oncogenic MicroRNA-21 Expression in Estrogen Receptor-Positive Breast Cancer Cells (MCF-7)

The omega-3 polyunsaturated fatty acid (n-3 PUFA), α-linolenic acid (ALA), and its metabolites, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), independently reduce the growth of breast cancer cells in vitro, but the mechanisms, which may involve microRNA (miRNA), are still unclear. The expression of the oncomiR, miR-21, is reduced by DHA treatment, but the effects of ALA on miR-21, alone or combined with EPA and DHA under physiologically relevant concentrations, have not been investigated. The effects of ALA alone and +/−EPA and DHA at the blood molar ratios seen in either humans (1.0:1.0:2.5, ALA:EPA:DHA) or mice (1.0:0.4:3.1, ALA:EPA:DHA) post flaxseed oil consumption (containing ALA) were assessed in vitro in MCF-7 breast cancer cells. Cell viability and the expression of miR-21 and its molecular target, phosphatase and tension homolog (PTEN, gene and protein), at different time points, were examined. At 1, 3, 48 and 96 h ALA alone and 24 h animal ratio treatments significantly reduced MCF-7 cell viability, while 1 and 3 h ALA alone and human and animal ratio treatments all significantly reduced miR-21 expression, and 24 h animal ratio treatment reduced miR-21 expression; these effects were not associated with changes in PTEN gene or protein expressions. We showed for the first time that ALA alone or combined with EPA and DHA at levels seen in human and animal blood post-ALA consumption can significantly reduce cell viability and modulate miR-21 expression in a time- and concentration-dependent manner, with the animal ratio containing higher DHA having a greater effect. The time dependency of miR-21 effects suggests the significance of considering time as a variable in miRNA studies, particularly of miR-21.

Citrobacter rodentium alters the mouse colonic miRNome

Citrobacter rodentium is a murine pathogen causing transmissible colonic hyperplasia and colitis with a pathogenic mechanism similar to foodborne enterohaemorrhagic Escherichia coli in humans. Mechanisms underlying intestinal responses to C. rodentium infection are incompletely understood. We identified 24 colonic microRNAs (miRNAs) as significantly deregulated in response to C. rodentium, including miR-7a, -17, -19a, -20a, -20b, -92a, -106a, -132, -200a, and -2137; most of these miRNAs belong to the oncogenic miR-17-92 clusters. Pathways involved in cell cycle, cancers, and immune responses were enriched among the predicted targets of these miRNAs. We further demonstrated that an apoptosis facilitator, Bim, is a candidate gene target of miRNA-mediated host response to the infection. These findings suggest that host miRNAs participate in C. rodentium pathogenesis and may represent novel treatment targets.

Time and strain-specific downregulation of intestinal EPAS1 via miR-148a by Bifidobacterium bifidum

Scope: Bifidobacteria play a role in intestinal homeostasis but molecular mechanisms remain underinvestigated. The aim of this study was to assess if probiotic Bifidobacterium strains alter expression of intestinal microRNA and downstream target gene response. Methods and results: The expression of miR‐148a and its validated target endothelial PAS domain protein 1 (EPAS1) was analyzed in Caco‐2 cells and mice cecum in response to Bifidobacterium bifidum MIMBb75, B. bifidum NCC390, or Bifidobacterium longum NCC2705. In vitro, exposure to B. bifidum MIMBb75, but not to B. bifidum NCC390 or B. longum NCC2705, increased the expression of miR‐148a after 1 and 4 h (p < 0.01), but not after 24 h. In vivo, B. bifidum MIMBb75 administration to C57BL/6J mice increased miR‐148a expression in the cecum after 2 but not 14 days (p < 0.05). The increase in miR‐148a was accompanied by a decrease in EPAS1 expression in Caco‐2 cells and cecum (p < 0.05). Silencing of miR‐148a reversed B. bifidum MIMBb75 dependent downregulation of EPAS1. Conclusion: This study shows an early response of intestinal cells to B. bifidum MIMBb75 through miR‐148a modulation. This brings a new concept of strain‐ and time‐dependent bifidobacteria–host crosstalk via microRNA. Probiotic B. bifidum MIMBb75 may help attenuating EPAS1 overexpression associated with intestinal inflammation.

Development of a real-time PCR assay for quantification of Citrobacter rodentium

Molecular tools to quantify Citrobacter rodentium are not available. We developed a quantitative PCR assay targeting the espB gene. This assay is specific, has a linearity range of about 6.7×10(1) to 6.7×10(6)cells/PCR reaction (92% efficiency) and a detection limit of about 10(4)cells/g wet feces.