Intestinal Microbiota and Colorectal Cancer in Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) are chronic and relapsing disabling disease. Crohn's disease (CD) and Ulcerative colitis (UC) are the two main types of IBD.

Patients with IBD are at greater risk of intestinal infection including viral infections (including cytomegalovirus) and bacterial (especially Clostridium difficile). In the long term, patients with colonic involvement are at an increased risk of colorectal cancer (CRC). Moreover, it has been reported in several cohort studies that patients with primary sclerosing cholangitis (PSC) associated with IBD (PSC-IBD), have an even increased risk of CRC (about 10 to 20% at 10 years). Other studies also suggest that the microbiota has an impact on liver diseases. Conversely, cholestatic liver diseases (such as PSC) can influence the microbiota, notably through modification of the production of bile acids. Finally, the role of the gut microbiota in the development of the CRC in IBD has been well established in animal models. The pathophysiological mechanisms are not well understood but may involve an alteration of the balance between protective bacteria against harmful microbiota.

This study aims to investigate the link between gut microbiota, intestinal inflammation, colorectal cancer, bile acid and liver diseases and this, through the creation of a biological collection of fecal microbiota from fecal samples from 8 groups of subjects: (i) IBD without CCR (ii) IBD with CCR, (iii) IBD with dysplasia, (iv) non IBD without CCR, (v) non IBD with CCR, (vi) IBD-CSP without CCR, (vii ) IBD-CSP with CCR, (viii) IBD-CSP with dysplasia. In these patients, microbiota composition will be assessed by sequencing technology.

Inclusion criteria

• Patient with the capacity to give informed consent.
• Age ≥ 18 years.
• A patient with IBD (Crohn's disease or ulcerative colitis) or healthy subject having a screening colonoscopy scheduled.
• Diagnosis of pathologies in question established or confirmed in any of the services involved in the study and according to international diagnostic criteria (Consensus ECCO).
• Patient follow-up in one of the services involved in the study

Exclusion criteria

• trusteeship, guardianship or safeguard justice.
• Subject does not speak French.
• Subject unable to answer questions or to speak.
• Previous history of colonic resection
• Taking antibiotics within 8 weeks preceding the stool sample Temporary exclusion criterium)
• Taking a bowel preparation for colonoscopy within 6 weeks before the stool sample (temporary exclusion criterium). Sampling is possible before bowel preparation or on the first stool after starting the bowel preparation.
• Ostomy at the time of sampling
• Current treatment by radiotherapy, chemotherapy