Post-Translational Inhibition of IP-10 Secretion in IEC by Probiotic Bacteria: Impact on Chronic Inflammation

Peer reviewedPublisher PD

Safety assessment of probiotics for human use

The safety of probiotics is tied to their intended use, which includes consideration of potential vulnerability of the consumer or patient, dose and duration of consumption, and both the manner and frequency of administration. Unique to probiotics is that they are alive when administered, and unlike other food or drug ingredients, possess the potential for infectivity or in situ toxin production. Since numerous types of microbes are used as probiotics, safety is also intricately tied to the nature of the specific microbe being used. The presence of transferable antibiotic resistance genes, which comprises a theoretical risk of transfer to a less innocuous member of the gut microbial community, must also be considered. Genetic stability of the probiotic over time, deleterious metabolic activities, and the potential for pathogenicity or toxicogenicity must be assessed depending on the characteristics of the genus and species of the microbe being used. Immunological effects must be considered, especially in certain vulnerable populations, including infants with undeveloped immune function. A few reports about negative probiotic effects have surfaced, the significance of which would be better understood with more complete understanding of the mechanisms of probiotic interaction with the host and colonizing microbes. Use of readily available and low cost genomic sequencing technologies to assure the absence of genes of concern is advisable for candidate probiotic strains. The field of probiotic safety is characterized by the scarcity of studies specifically designed to assess safety contrasted with the long history of safe use of many of these microbes in foods

Butyrate Attenuates Lipopolysaccharide-Induced Inflammation in Intestinal Cells and Crohn's Mucosa through Modulation of Antioxidant Defense Machinery

Oxidative stress plays an important role in the pathogenesis of inflammatory bowel disease (IBD), including Crohn's disease (CrD). High levels of Reactive Oxygen Species (ROS) induce the activation of the redox-sensitive nuclear transcription factor kappa-B (NF-κB), which in turn triggers the inflammatory mediators. Butyrate decreases pro-inflammatory cytokine expression by the lamina propria mononuclear cells in CrD patients via inhibition of NF-κB activation, but how it reduces inflammation is still unclear. We suggest that butyrate controls ROS mediated NF-κB activation and thus mucosal inflammation in intestinal epithelial cells and in CrD colonic mucosa by triggering intracellular antioxidant defense systems. Intestinal epithelial Caco-2 cells and colonic mucosa from 14 patients with CrD and 12 controls were challenged with or without lipopolysaccaride from Escherichia Coli (EC-LPS) in presence or absence of butyrate for 4 and 24 h. The effects of butyrate on oxidative stress, p42/44 MAP kinase phosphorylation, p65-NF-κB activation and mucosal inflammation were investigated by real time PCR, western blot and confocal microscopy. Our results suggest that EC-LPS challenge induces a decrease in Gluthation-S-Transferase-alpha (GSTA1/A2) mRNA levels, protein expression and catalytic activity; enhanced levels of ROS induced by EC-LPS challenge mediates p65-NF-κB activation and inflammatory response in Caco-2 cells and in CrD colonic mucosa. Furthermore butyrate treatment was seen to restore GSTA1/A2 mRNA levels, protein expression and catalytic activity and to control NF-κB activation, COX-2, ICAM-1 and the release of pro-inflammatory cytokine. In conclusion, butyrate rescues the redox machinery and controls the intracellular ROS balance thus switching off EC-LPS induced inflammatory response in intestinal epithelial cells and in CrD colonic mucosa

Post-Translational Inhibition of IP-10 Secretion in IEC by Probiotic Bacteria: Impact on Chronic Inflammation

Peer reviewedPublisher PD

The microbiome of the human lower airways : a next generation sequencing perspective

Abstract For a long time, the human lower airways were considered a sterile environment where the presence of microorganisms, typically revealed by culturing, was interpreted as an abnormal health state. More recently, high-throughput sequencing-based studies have led to a shift in this perception towards the notion that even in healthy conditions the lower airways show either transient presence or even permanent colonization by microorganisms. However, challenges related to low biomass and contamination in samples still remain, and the composition, structure and dynamics of such putative microbial communities are unclear. Here, we review the evidence for the presence of microbial communities in the human lower airways, in healthy subjects and within the context of medical conditions of interest. We also provide an overview of the methodology pertinent to high-throughput sequencing studies, specifically those based on amplicon sequencing, including a discussion of good practices and common pitfalls

Top 10 up- and down-regulated overlapping genes between prenatal WT/iWT and WT/iARE gene expression patterns (effect of maternal inflammation) and between postnatal WT/ARE and WT/iARE gene expression patterns (effect of offspring genotype/disease).

<p>FC = log 2 based fold change, <i>p</i><0.05.</p

Top 5 up- and down-regulated genes in iWT, ARE and iARE mice pre- and postnatally.

<p>Fold changes refer to WT control mice according to MADMAX statistical analysis (n = 5 per group, <i>p</i><0.05; FC = log 2 based fold change).</p

Fetal Exposure to Maternal Inflammation Does Not Affect Postnatal Development of Genetically-Driven Ileitis and Colitis

<div><p><b><i>Background:</i></b> Chronic inflammatory disorders have been increasing in incidence over the past decades following geographical patterns of industrialization. Fetal exposure to maternal inflammation may alter organ functions and the offspring's disease risk. We studied the development of genetically-driven ileitis and colitis in response to maternal inflammation using mouse models.</p><p><b><i>Methods:</i></b> Disease susceptible (<i>Tnf</i>^ΔARE/+ and <i>IL</i>10^−/−) and disease-free (<i>Tnf</i>^+/+ and <i>IL</i>10^−/+) offspring were raised in inflamed and non-inflamed dams. Ileal, caecal and colonic pathology was evaluated in the offspring at 8 or 12 weeks of age. Ly6G-positive cells in inflamed sections from the distal ileum and distal colon were analysed by immunofluorescence microscopy. Gene expression of pro-inflammatory cytokines was measured in whole tissue specimens by quantitative PCR. Microarray analyses were performed on laser microdissected intestinal epithelium. Caecal bacterial communities were assessed by Illumina sequencing of 16S rRNA amplicons.</p><p><b><i>Results:</i></b> Disease severity, the number of infiltrated neutrophils as well as <i>Tnf</i> and <i>Il12p40</i> mRNA expression were independent of maternal inflammation in the offspring of mouse models for ileitis (<i>Tnf</i>^ΔARE/+) and colitis (<i>IL</i>10^−/−). Although TNF-driven maternal inflammation regulated 2,174 (wild type) and 3,345 (<i>Tnf</i>^ΔARE/+) genes in the fetal epithelium, prenatal gene expression patterns were completely overwritten after birth. In addition, co-housing experiments revealed no change in phylogenetic diversity of the offspring's caecal microbiota in response to maternal inflammation. This is independent of the offspring's genotype before and after the onset of tissue pathology.</p><p><b><i>Conclusions:</i></b> Disease risk and activity in mouse models of chronic ileitis and colitis was independent of the fetal exposure to maternal inflammation. Likewise, maternal inflammation did not alter the diversity and composition of offspring's caecal microbiota, clearly demonstrating that changes of the gene expression program in the fetal gut epithelium were not relevant for the development of chronic inflammatory disorders in the gut.</p></div