The study is aim to detect common microbial profiles and metabolic pathways throughout IBD diagnosis and treatment with biological therapy.

The study is aim to detect common microbial profiles and metabolic pathways in patients belonging to the following groups:

1. Therapy naïve newly diagnosed Crohn's disease (CD), ulcerative colitis (UC) and pouchitis patients. Studying this group of patients will enable the detection of microbial profiles associated with disease onset.
2. Patients planned to commence biological therapy (with or without IBD). Studying this group of patients will enable the detection of microbial profiles associated with response to biological therapy.
3. IBD patients in complete remission (treated or untreated with biologics). Following this group of patients will enable the detection of microbial profiles associated with disease exacerbation.

Methods:

Study design: A prospective cohort study. Setting: The investigators will prospectively collect clinical, behavioral and environmental data of patients participating in the study. Data will be collected according to a uniform standardized protocol specifically adapted to the needs of the study and shared between the collaborators.

Study population: Eligible patients, who sign an informed consent form and answer to all the study inclusion criteria. Patients will be informed of the study by their treating physician, recruited and followed throughout the follow-up period by study coordinators.

sample size: sample size was estimated according to clinical capabilities of the researcher. We aim to collect data from a total of 1000 patients.

Schedule: Data will be collected between the years 2019-2024.

Study plan:

Patient and disease characteristics At baseline, demographic characteristics, medical history and specifically IBD phenotype, severity, extent and location, disease duration, previous medicinal treatment will be documented. Baseline and follow-up study visits which will include biological sample collection and questionnaires.

Patients will be asked to complete questionnaires to account for their lifestyle, sleep, quality of life and disease related symptoms and outcomes. Physician global assessment (PGA), disease severity using clinical scores (HBI and SCCAI scores for CD and UC patients) and biochemical data (CRP, fecal calprotectin) will be documented.

Inclusion Criteria:

Patients who belong to one of the following sub-groups:

1. Newly diagnosed (<1 years), therapy naïve IBD and pouchitis patients
2. IBD patients in complete remission (treated or untreated with biologics)
3. Patients (with and without IBD) scheduled to commence a biological therapy

Exclusion Criteria:

1. Age≤18 years
2. Inability to sign an informed consent
3. Abdominal surgery during the previous 3 months
4. Systemic antibiotic therapy in the previous 4 weeks
5. Severe systemic disease such as kidney, liver, neurologic, cardio-vascular disease
6. Primary sclerosing cholangitis
7. Pregnancy at recruitment
8. Cancer within the previous 5 years excluding local NMSC

The investigators aim to collect data from a total of 1000 patients.