Immunoregulatory Mechanisms Underlying Prevention of Colitis-Associated Colorectal Cancer by Probiotic Bacteria

Background: Inflammatory bowel disease (IBD) increases the risk of colorectal cancer. Probiotic bacteria produce immunoregulatory metabolites in vitro such as conjugated linoleic acid (CLA), a polyunsaturated fatty acid with potent anticarcinogenic effects. This study aimed to investigate the cellular and molecular mechanisms underlying the efficacy of probiotic bacteria in mouse models of cancer. Methodology/Principal Findings: The immune modulatory mechanisms of VSL#3 probiotic bacteria and CLA were investigated in mouse models of inflammation-driven colorectal cancer. Colonic specimens were collected for histopathology, gene expression and flow cytometry analyses. Immune cell subsets in the mesenteric lymph nodes (MLN), spleen and colonic lamina propria lymphocytes (LPL) were phenotypically and functionally characterized. Mice treated with CLA or VSL#3 recovered faster from the acute inflammatory phase of disease and had lower disease severity in the chronic, tumor-bearing phase of disease. Adenoma and adenocarcinoma formation was also diminished by both treatments. VSL#3 increased the mRNA expression of TNF-a, angiostatin and PPAR c whereas CLA decreased COX-2 levels. Moreover, VSL#3-treated mice had increased IL-17 expression in MLN CD4+ T cells and accumulation of Treg LPL and memory CD4+ T cells. Conclusions/Significance: Both CLA and VSL#3 suppressed colon carcinogenesis, although VSL#3 showed greater anticarcinogeni

Prebiotic potential of a maize-based soluble fibre and impact of dose on the human gut microbiota

Dietary management of the human gut microbiota towards a more beneficial composition is one approach that may improve host health. To date, a large number of human intervention studies have demonstrated that dietary consumption of certain food products can result in significant changes in the composition of the gut microbiota i.e. the prebiotic concept. Thus the prebiotic effect is now established as a dietary approach to increase beneficial gut bacteria and it has been associated with modulation of health biomarkers and modulation of the immune system. Promitor™ Soluble Corn Fibre (SCF) is a well-known maize-derived source of dietary fibre with potential selective fermentation properties. Our aim was to determine the optimum prebiotic dose of tolerance, desired changes to microbiota and fermentation of SCF in healthy adult subjects. A double-blind, randomised, parallel study was completed where volunteers (n = 8/treatment group) consumed 8, 14 or 21 g from SCF (6, 12 and 18 g/fibre delivered respectively) over 14-d. Over the range of doses studied, SCF was well tolerated Numbers of bifidobacteria were significantly higher for the 6 g/fibre/day compared to 12g and 18g/fibre delivered/day (mean 9.25 and 9.73 Log10 cells/g fresh faeces in the pre-treatment and treatment periods respectively). Such a numerical change of 0.5 Log10 bifidobacteria/g fresh faeces is consistent with those changes observed for inulin-type fructans, which are recognised prebiotics. A possible prebiotic effect of SCF was therefore demonstrated by its stimulation of bifidobacteria numbers in the overall gut microbiota during a short-term intervention

The type and quantity of dietary fat and carbohydrate alter faecal microbiome and short-chain fatty acid excretion in a metabolic syndrome ‘at-risk’ population syndrome.

An obese-type human microbiota with an increased Firmicutes:Bacteroidetes ratio has been described that may link the gut microbiome with obesity and metabolic syndrome (MetS) development. Dietary fat and carbohydrate are modifiable risk factors that may impact on MetS by altering the human microbiome composition. We determined the effect of the amount and type of dietary fat and carbohydrate on faecal bacteria and short chain fatty acid (SCFA) concentrations in people ‘at risk’ of MetS

Prognosis following upper gastrointestinal bleeding: Record linkage study

Upper gastrointestinal (GI) bleeding is one of the most common, high risk emergency disorders in the western world. Almost nothing has been reported on longer term prognosis following upper GI bleeding. The aim of this study was to establish mortality up to three years following hospital admission with upper GI bleeding and its relationship with aetiology, co-morbidities and socio-demographic factors.Systematic record linkage of hospital inpatient and mortality data for 14 212 people in Wales, UK, hospitalised with upper GI bleeding between 1999 and 2004 with three year follow-up to 2007. The main outcome measures were mortality rates, standardised mortality ratios (SMRs) and relative survival.Mortality at three years was 36.7% overall, based on 5215 fatalities. It was highest for upper GI malignancy (95% died within three years) and varices (52%). Compared with the general population, mortality was increased 27-fold during the first month after admission. It fell to 4.3 by month four, but remained significantly elevated during every month throughout the three years following admission. The most important independent prognostic predictors of mortality at three years were older age (mortality increased 53 fold for people aged 85 years and over compared with those under 40 years); oesophageal and gastric/duodenal malignancy (48 and 32 respectively) and gastric varices aetiologies (2.8) when compared with other bleeds; non-upper GI malignancy, liver disease and renal failure co-morbidities (15, 7.9 and 3.9); social deprivation (29% increase for quintile V vs I); incident bleeds as an inpatient (31% vs admitted with bleeding) and male patients (25% vs female).Our study shows a high late as well as early mortality for upper GI bleeding, with very poor longer term prognosis following bleeding due to malignancies and varices. Aetiologies with the worst prognosis were often associated with high levels of social deprivation