MIcroorganisms as Triggers in Acute Severe Ulcerative Colitis and Their Influence on Medical Therapy Efficacy: a Multi-omics Pilot Approach.

Ulcerative Colitis (UC) is one of the two entities of Inflammatory Bowel Disease (IBD), along with Crohn's disease. One in 4 patients experiences an Acute Severe Ulcerative Colitis (ASUC) during the disease course, defined as a severe flare with systemic inflammation. ASUC is a medical and surgical emergency as complications and death may occur when patients do not respond to medical therapy and require salvage colectomy. Little is known about the pathophysiology and specifically the triggers of ASUC. At baseline, investigators will investigate the presence of a microbiome signature in patients with an ASUC compared with patients with a non-severe UC flare (NSUC). To identify the role of microorganisms, investigators will look specifically for known enteropathogens, i.e. Clostridium difficile and Cytomegalovirus. Investigators will investigate the impact of microbiota disruptors, such as antibiotics, NSAIDs and diet on microbiota and patients' outcomes. To evaluate the role of the host inflammatory pathways, investigators will study the colonic mucosa transcriptome and the host metabolome, focusing on anti-microbial defence pathways, regarding the suggested role of defective immune defence pathways in IBD pathogenesis. Investigators will focus on the IL23 and Jak pathways, since new drugs targeting these molecules are now available for IBD patients but still not recommended in the ASUC setting. Our last approach will be to evaluate the predictability of the response to therapy according to baseline and early changes of stool microbiome and host metabolome.