Intestinal Surface (intestinal + surface)

Distribution by Scientific Domains

Selected Abstracts

Mechanisms and modulation of intestinal epithelial repair

Dr. Axel U. Dignass
Abstract The mucosal epithelium of the alimentary tract represents a crucial barrier to a broad spectrum of noxious and immunogenic substances within the intestinal lumen. An impairment of the integrity of the mucosal epithelial barrier is observed in the course of various intestinal disorders including inflammatory bowel diseases (IBD), celiac disease, intestinal infections, and various other diseases. Furthermore, even under physiologic conditions temporary damage of the epithelial surface mucosa may be caused by proteases, residential flora, dietary compounds, or other factors. Generally, the integrity of the intestinal mucosal surface barrier is rapidly reestablished even after extensive destruction because of an enormous regenerative capability of the mucosal surface epithelium. Rapid resealing of the surface epithelium is accomplished by epithelial cell migration, also termed epithelial restitution, epithelial cell proliferation, and differentiation. Healing of the intestinal surface epithelium is regulated by a complex network of highly divergent factors, among them a broad spectrum of structurally distinct regulatory peptides that have been identified within the mucosa of the intestinal tract. These regulatory peptides, conventionally designated as growth factors and cytokines, play an essential role in regulating differential epithelial cell functions to preserve normal homeostasis and integrity of the intestinal mucosa. In addition, a number of other peptide molecules such as extracellular matrix factors and blood clotting factors, and also nonpeptide molecules including phospholipids, short-chain fatty acids, adenine nucleotides, trace elements, and pharmacological agents, have been demonstrated to modulate intestinal epithelial repair mechanisms. Some of these molecules may be released by platelets, adjacent stromal cells, inflammatory cells, or injured epithelial and nonepithelial cells and may play an important role in the modulation of intestinal injury. Repeated damage and injury of the intestinal surface are key features of various intestinal disorders including IBD and require constant repair of the epithelium. Enhancement of intestinal repair mechanisms by regulatory peptides or other modulatory factors may provide future approaches for the treatment of diseases that are characterized by injuries of the epithelial surface. [source]

OmpA is an adhesion factor of Aeromonas veronii, an optimistic pathogen that habituates in carp intestinal tract

A. Namba
Abstract Aims:, In the present study, we focused on one of the Aeromonas veronii isolates that exhibited marked adhesion onto carp intestine and studied its membrane-associated proteins for their possible involvement in mucosal adhesion. Methods and Results:, We isolated a strain of Aer. veronii (CWP11) that exhibited a high degree of temperature-dependent adhesion activity onto carp intestinal tract and studied its adhesion factor. A proteomic analysis of the membrane-associated fraction showed the presence of multiple proteins that were specifically expressed in CWP11 cells cultured at 25°C. Of these, a 30 kDa protein was identified to be OmpA by a mass fingerprint analysis. Cloning and nucleotide sequencing of the ompA region of CWP11 revealed the presence of two tandem ompA homologues (ompAI - ompAII). Escherichia coli that expressed either OmpAI or OmpAII exhibited marked adhesion onto carp intestinal surface. Disruption of ompAI by a homologous recombination technique resulted in marked reduction of the adhesion activity in CWP11. Conclusion:, The OmpA homologue plays an important role in the adhesion of the Aer. veronii strain onto the surface of intestinal tract. Significance and Impact of the Study:, We successfully identified an OmpA homologue to be an adhesion factor of Aer. veronii, an optimistic pathogen that habituates in carp intestinal tract. [source]

Health-beneficial effects of probiotics: Its mode of action

ABSTRACT It is now widely recognized that probiotics have health-beneficial effects on humans and animals. Probiotics should survive in the intestinal tract to exert beneficial effects on the host's health. To keep a sufficient level of probiotic bacteria in the gastrointestinal tract, a shorter interval between doses may be required. Although adherence to the intestinal epithelial cell and mucus is not a universal property of probiotics, high ability to adhere to the intestinal surface might strongly interfere with infection of pathogenic bacteria and regulate the immune system. The administration of probiotic Lactobacillus stimulated indigenous Lactobacilli and the production of short-chain fatty acids. This alteration of the intestinal environment should contribute to maintain the host's health. The immunomodulatory effects of probiotics are related to important parts of their beneficial effects. Probiotics may modulate the intestinal immune response through the stimulation of certain cytokine and IgA secretion in intestinal mucosa. The health-beneficial effects, in particular the immunomodulation effect, of probiotics depend on the strain used. Differences in indigenous intestinal microflora significantly alter the magnitude of the effects of a probiotic. Specific probiotic strains suitable for each animal species and their life stage as well as each individual should be found. [source]

Exported proteins in probiotic bacteria: adhesion to intestinal surfaces, host immunomodulation and molecular cross-talking with the host

Borja Sánchez
Abstract The group of exported proteins of a bacterium are those proteins that are sorted from the cytoplasm to the bacterial surface or to the surroundings of the microorganism. In probiotic bacteria, these proteins are of special relevance because they might determine important traits such as adhesion to intestinal surfaces and molecular cross-talking with the host. Current knowledge about the presence and biological relevance of exported proteins produced by the main genera of probiotic bacteria in the gastrointestinal environment is reviewed in this minireview. As will be seen, some of these proteins are involved in host adhesion or are able to modify certain signalization pathways within host cells, whereas others are important for the physiology of probiotic bacteria in the gastrointestinal tract. [source]