Crohn’s disease (CD) is a chronic inflammatory condition of the gastrointestinal (GI) tract. It can affect any part of the GI tract, but is most commonly found at the end of the small bowel and the beginning of the colon. CD patients experience periods of remission where patients may not notice any symptoms, and periods of active inflammation (flare-ups), causing symptoms as persistent diarrhea, abdominal cramps and fever. Standard clinical testing to diagnose CD includes invasive procedures such as endoscopy and biopsy. Furthermore, to limit disease progression and complications, it is crucial to monitor mucosal inflammation, for which endoscopy is also the current standard.
The exact cause of CD is not well understood. Several hereditary, genetics and environmental factors have been proposed that may contribute to its development. Furthermore, research has shown clear associations between CD and alterations of the gut microbial composition (dysbiosis). In addition, the disease activity also seems to be associated with dysbiosis. Researchers from the University of Maastricht now investigated the potential of the gut microbiota as a non-invasive tool to monitor disease activity1. From 71 CD patients repeated fecal samples were collected, resulting in 97 active disease and 97 remission samples based on a combination of biochemical and clinical parameters. The fecal microbial profiles were determined with the use of 16s ribosomal RNA (rRNA) technology. Computational analysis were then used to find the bacterial species that were most discriminatory between active and remission samples. The 50 bacterial species with the highest variability between the samples were selected. This combination was then tested for its ability to correctly differentiate between active and remission samples in an independent sample group. It was found that the combination of 50 bacterial could correctly predict 73% of remission- and 79% of active samples.
In addition, a recent study has shown fecal microbiota profiles can also be used as a non-invasive diagnostic tool for CD2. They compared the fecal microbial profiles of CD patients with those of healthy individuals and also applied the 16S rRNA sequencing approach to determine the fecal microbial profiles. This resulted in the identification of 8 microbial groups, including Faecalibacterium and Collinsella, that were proposed as a specific microbial signature for CD. This signature was then tested against other studies with CD patients, achieving an overall sensitivity of 80%, meaning that it correctly diagnosed CD In 80% of the patients. Furthermore, the microbial signature of the microbial signature was tested against healthy cohorts, patients diagnosed with anorexia and ulcerative colotis, showing a specificity (i.e. the percentage of people who are correctly identified as not having CD) of 94,3%, 94,4% en 90,9%, respectively.
These studies underline the potential of the fecal microbiota as a non-invasive tool to diagnose and monitor CD.
Written by Tessa Hemrika, medical writer Winclove Probiotics
- 1. Tedjo, D. I., Smolinska, A., Savelkoul, P. H., Masclee, A. A., van Schooten, F. J., Pierik, M. J., and Jonkers, D. M. (2016). The fecal microbiota as a biomarker for disease activity in Crohn’s disease. Scientific Reports, 6, 35216
- 2. Pascal, V., Pozuelo, M., Borruel, N., Casellas, F., Campos, D., Santiago, A., & Vermeire, S. (2017). A microbial signature for Crohn's disease. Gut, 66 (5), pp. 813–822