Immunological Characteristics of Preclinical IBD

Inclusion criteria Patients from cohort A will be included if they fulfill all the following inclusion criteria: * Male or female ≥18 years of age at baseline. * New diagnosis of IBD during a CRC screening colonoscopy, based on the criteria from the European Crohn's and Colitis Organization (33, 34). * Presence of a chronic inflammatory infiltrate and histological diagnosis compatible with IBD. * The patient must be asymptomatic at diagnosis and without previous symptoms suggestive of IBD. * Time interval between the index colonoscopy and the baseline visit up to 3 months. Patients from cohort B will be included if they fulfill all the following inclusion criteria: * Male or female ≥18 years of age at baseline. * Recent diagnosis of IBD, with \<3 months from symptoms onset. * Time interval between the index colonoscopy and the baseline visit up to 3 months. Patients from cohort C will be included if they fulfill all the following inclusion criteria: * Male or female ≥18 years of age at baseline. * No endoscopic signs of IBD after a complete ileo-colonoscopy within the CRC screening program. * Time interval between the index colonoscopy and the baseline visit up to 3 months. Exclusion criteria Patients from cohort A will be excluded if they fulfill any the following exclusion criteria: * Identification of any enteropathogen in the stool culture. * Isolated findings of acute inflammatory infiltrate without signs of chronicity. * Previous or current diagnosis of microscopic colitis. * Alteration in biomarkers in blood or stool will not constitute an exclusion criterion. Patients from cohort B will be excluded if they fulfill any the following exclusion criteria: \- Previous use of immunomodulators or biologics for any condition. Patients from cohort C will be excluded if they fulfill any the following exclusion criteria: * Any gastrointestinal symptoms at baseline. * Previous use of immunomodulators or biologics for any condition.