Living drugs for gastrointestinal diseases: the case for probiotics

The Inflammatory Response to Enterotoxigenic E. coli and Probiotic E. faecium in a Coculture Model of Porcine Intestinal Epithelial and Dendritic Cells

The gut epithelium constitutes an interface between the intestinal contents and the underlying gut-associated lymphoid tissue (GALT) including dendritic cells (DC). Interactions of intestinal epithelial cells (IEC) and resident DC are characterized by bidirectional crosstalk mediated by various factors, such as transforming growth factor-β (TGF-β) and thymic stromal lymphopoietin (TSLP). In the present study, we aimed (1) to model the interplay of both cell types in a porcine in vitro coculture consisting of IEC (cell line IPEC-J2) and monocyte-derived DC (MoDC) and (2) to assess whether immune responses to bacteria are altered because of the interplay between IPEC-J2 cells and MoDC. With regard to the latter, we focused on the inflammasome pathway. Here, we propose caspase-13 as a promising candidate for the noncanonical inflammasome activation in pigs. We conducted challenge experiments with enterotoxigenic Escherichia coli (ETEC) and probiotic Enterococcus faecium (E. faecium) NCIMB 10415. As potential mediators of IEC/DC interactions, TGF-β and TSLP were selected for analyses. Cocultured MoDC showed attenuated ETEC-induced inflammasome-related and proinflammatory interleukin (IL)-8 reactions compared with MoDC monocultures. Caspase-13 was more strongly expressed in IPEC-J2 cells cocultured with MoDC and upon ETEC incubation. We found that IPEC-J2 cells and MoDC were capable of releasing TSLP. The latter cells secreted greater amounts of TSLP when cocultured with IPEC-J2 cells. TGF-β was not modulated under the present experimental conditions in either cell types. We conclude that, in the presence of IPEC-J2 cells, porcine MoDC exhibited a more tolerogenic phenotype, which might be partially regulated by autocrine TSLP production. Noncanonical inflammasome signaling appeared to be modulated in IPEC-J2 cells. Our results indicate that the reciprocal interplay of the intestinal epithelium and GALT is essential for promoting balanced immune responses.

Review of the role of probiotics in gastrointestinal diseases in adults

BACKGROUND

Probiotics may act as biological agents that modify the intestinal microbiota and certain cytokine profiles, which can lead to an improvement in certain gastrointestinal diseases.

OBJECTIVES

To conduct a review of the evidence of the role of probiotics in certain gastrointestinal diseases in adults.

SEARCH METHODS

Review conducted using appropriate descriptors, filters and limits in the PubMed database (MEDLINE).

SELECTION CRITERIA

The MeSH terms used were Probiotics [in the title] AND Gastrointestinal Diseases, with the following limits or filters: Types of study: Systematic Reviews, Meta-Analysis, Guideline, Practice Guideline, Consensus Development Conference (and Consensus Development Conference NIH), Randomized Controlled Trial, Controlled Clinical Trial and Clinical Trial; age: adults (19 or older); language: English and Spanish; in humans, and with at least one abstract.

DATA COLLECTION AND ANALYSIS

Full texts of all the Systematic Reviews and meta-analyses directly related to the review's objective were obtained, as well as the Randomised Controlled Trials of the studies that were considered relevant and of sufficient quality for this review.

MAIN RESULTS

Certain probiotics, different for each process, have proven to be effective and beneficial in cases of acute infectious diarrhoea, antibiotic-associated diarrhoea, Clostridium difficile-associated diarrhoea, pouchitis and Helicobacter pylori infection eradication.

AUTHORS' CONCLUSIONS

Although some probiotics have not demonstrated any benefit, there are certain gastrointestinal diseases in which the use of probiotics, true biological agents, can be recommended.

Role of commensal and probiotic bacteria in human health: a focus on inflammatory bowel disease

The human gut is one of the most complex ecosystems, composed of 1013-1014 microorganisms which play an important role in human health. In addition, some food products contain live bacteria which transit through our gastrointestinal tract and could exert beneficial effects on our health (known as probiotic effect). Among the numerous proposed health benefits attributed to commensal and probiotic bacteria, their capacity to interact with the host immune system is now well demonstrated. Currently, the use of recombinant lactic acid bacteria to deliver compounds of health interest is gaining importance as an extension of the probiotic concept. This review summarizes some of the recent findings and perspectives in the study of the crosstalk of both commensal and probiotic bacteria with the human host as well as the latest studies in recombinant commensal and probiotic bacteria. Our aim is to highlight the potential roles of recombinant bacteria in this ecosystem.

An overview of the mosaic bacteriocin pln loci from Lactobacillus plantarum

The pln locus responsible for bacteriocin biosynthesis in Lactobacillus plantarum C11 was first unraveled about 15 years ago and since then different strains of L. plantarum (NC8, WCFS1, J23 and J51) have been found to harbor mosaic pln loci in their genomes. Each locus is of 18-19kb and contains 22-25 genes organized into 5-6 operons. Together these strains produce four different class IIb two-peptide bacteriocins, plantaricins EF, JK, NC8 and J51 and a pheromone peptide plantaricin A with antimicrobial activity. Their production has been found to be regulated through a quorum-sensing based network consisting of a secreted peptide pheromone, a membrane-located sensor and one or two transcription regulators. The individual loci each contain a set of semi-conserved regulated promoters with subtle differences necessary for the regulators to regulate their promoter activity individually with respect to timing and strength. These subtle differences in the promoters are highly conserved across the different pln loci, in a functionally related manner. In this review we will discuss various aspects of these bacteriocin loci with special focus on their mosaic genetic composition, gene regulation and mode of action. We also present a novel pln locus containing a transposon of the MULE superfamily, a mobile element which has not been described in L. plantarum before.