Lay Summary

Proposal No. IBD-0030
Principal Investigator:  Alexander Swidsinski, M.D., Ph.D.
Applicant Organization:  The University Hospital Charité of the Humboldt University at Berlin (Germany)
Project Title: In situ characterization of the mucosal bacterial biofilm in patients with inflammatory bowel disease using universal and group/species specific FISH probes
Period of Award:  January 1, 2003 – March 31, 2005

The non-inflamed mucosa of patients with inflammatory bowel disease (IBD) is covered by a thick bacterial biofilm that is absent in control subjects.  There is a significant relationship between bacterial concentrations and severity of disease, patient’s age at onset of disease, disease activity, treatment regimen and medical therapy.

Mucosal bacteria form complex structured multicellular communities (biofilms).  The coordinated response of this mixed bacterial biofilms to environmental hazards allows them to grow in a hostile environment and to colonize inert or living surfaces.  The same species of bacteria, in their sessile form, are different from the free-floating planktonic ones.  They cause a very low-grade inflammatory response of the surrounding mucosa.  They are highly resistant to antibiotics and it is almost impossible to eliminate the bacterial biofilm.

Until now, all attempts to identify a specific pathogen triggering IBD have possibly failed because of methods neglecting the organization of the bacterial biofilm.  The spatial structure of the biofilm is the key to understanding of its properties and function.  Presently, very little is known about the composition and nothing about the structure of human gut biofilms either in health or disease.  We will describe the location of bacterial groups within the biofilm in relation to the surface of the mucosa, to overall thickness of the biofilm and to other mucosal and intraepithelial bacterial components and will correlate the results with the clinical course of the patients.  The spatial structure of the adherent biofilm in patients with IBD may revise enteric microbiology and give rise to fresh ideas concerning IBD pathogenesis and treatment.