A study, led by Dr. Chaysavanh Manichanh, responsible for research of Intestinal Microbiota of the Physiology and Digestive Physiopathology of the Vall d'Hebron Research Institute (VHIR) has identified 8 biomarkers that could improve the diagnosis of Crohn's disease and the design of treatment for this disease and ulcerative colitis.

The study, published in Gut, has analyzed the microbiota -the set of microorganisms of the intestine- of patients and healthy people from stool samples. They have analyzed a total of 415 stool samples from 178 participantsto identify 8 biomarkers that could rule out the diagnosis of Crohn's disease and, therefore, avoid invasive colonoscopy and endoscopy tests.

The 8 biomarkers correspond to the following eight groups of microorganisms: Faecalibacterium Peptostreptococcaceae, Anaerostipes, Methanobrevibacter, Christensenellaceae, Collinsella, Fusobacterium and Escherichia, being the last two the most detected in Crohn's patients. In addition, it is the first study in which we have collected samples from patients throughout a year, a design that has helped researchers detect biomarkers in the 80% of the samples, despite changes in microbiota characteristic of this pathology.

First geographic analysis in Europe

The study has handled a large number of samples, 2.045, for an analysis of cohorts, i.e. compare a sample of population affected by the disease with a sample of healthy people. To this end, they have worked with a cohort with samples of patients with inflammatory bowel disease from the Digestive System Service of the University Hospital Vall d'Hebron - which main forms are Crohn's disease and ulcerative colitis - that has allowed to identify biomarkers of Crohn's disease and other cohorts to validate the results. This validation has been done with samples of patients with Crohn's disease of Belgium, of patients with irritable bowel syndrome of Vall d'Hebron, of healthy people from United Kingdom and of patients with anorexia from Germany.

Thus, a part of the samples analyzed and sequenced from patients with Crohn's disease has been compared with the results of another already published study of healthy individuals of United Kingdom. The biomarkers that the authors of the study propose should not be detected in the sequences of healthy individuals. In this case, the results have been of only a 7% of false positive, i.e., a result that confirms the existence of the pathology when there is not. In addition, Dr. Manichanh, clarifies that it is possible that the percentage was lower because it is unknown if any of the samples corresponded to a patient that had not been diagnosed. On the other hand, the results for the samples of irritable colon and anorexia were similar, with a 5% of false positive in both cases. The principal investigator of the study explains that "it is an indicative percentage of the precision of using these biomarkers to diagnose the Crohn's disease and the ulcerative colitis. We have designed an algorithm that any laboratory could use to diagnose the Crohn's disease".

The researchers stand out that the results of the study confirm that the Crohn's disease and the ulcerative colitis are diseases clinically similar, but with a very different microbiota. In this regard, they noted that patients with Crohn's disease have a more destabilizing microbiota than patients with ulcerative colitis. Dr. Manichanh highlights that "it is something that has to be taken into account when designing the treatment of those patients".

After the publication of this research, the interest of the authors is to have samples of patients of Crohn's and ulcerative colitis from all over the world to validate the method and to use it as test diagnostic in any laboratory.

Crohn's disease and ulcerative colitis

Crohn's disease and ulcerative colitis are chronic digestive diseases of unknown cause. The main symptoms include abdominal pain, diarrhea, fever, weight loss and rectal bleeding.

Crohn's disease is an inflammatory autoimmune disease of the gastrointestinal tract that evolves in a recurrent manner with outbreaks. This pathology can affect from the mouth to the anus.

Ulcerative colitis affects exclusively the colon, the most frequent location being the rectum. 

Reference: Pascal V, Pozuelo M, Borruel N, et al A microbial signature for Crohn's disease. Gut Published Online First: 07 February 2017. doi: 10.1136/gutjnl-2016-313235