Secreted bacterial effectors produced by the intestinal microbiota are in part responsible for the proinflammatory effect of the fecal content in inflammatory bowel disease (IBD) patients.

Fecal colonic content will be collected by suction during routine colonoscopy. From the fecal content different fractions (containing soluble bacterial fractions and membrane bound bacterial fractions) will be processed. These bacterial fractions (also termed as bacterial secretome) will be tested for proinflammatory potential in tissue culture assays including epithelial colonic cell lines and dendritic/monocytic cell lines. The main outcome parameter will be the secretion of proinflammatory cytokines from the tissue culture.

For this purpose the investigators will test different groups of patients including patients with active/inactive Crohn's disease or ulcerative colitis, patients with other inflammatory conditions of the colon, patients with colorectal carcinoma and healthy controls undergoing colonoscopy.

Group 1 (healthy controls): n=20

Inclusion criteria:

• Colonoscopy performed for the following indications: anemia, blood in stool, constipation, change in bowel habits, screening for colon cancer, follow up after polyps, weight loss
• Macroscopic normal colonoscopy except for diverticulosis (without any signs of inflammation), ≤ 3 polyps (except hyperplastic polyps of the colon and rectum), angiodysplasia

Exclusion criteria:

• Diagnosis of IBD or any other inflammatory condition of the small and large intestine
• Diagnosis of IBS
• Autoimmune disorders
• Obesity (BMI> 30)
• Regular intake of NSAIDs (> 2 tablets/ week), immunosuppressants
• Intake of antibiotics within the last 3 months
• Intestinal infection by enteric pathogens
• Probiotic therapy

Group 2 (Crohn´s disease; CD): n= 20 (10 active CD; 10 inactive CD)

Inclusion criteria:

• Colonoscopy indicated by routine clinical care
• Established diagnosis of Crohn´s disease (also if established by the study colonoscopy)

Exclusion criteria:

• Intestinal infection by enteric pathogens

Definition of active CD Harvey-Bradshaw Index - HBI ≥ 5 and / or Simple Endoscopic Score for Crohn Disease (SES-CD) ≥ 3

Except SES-CD scores resulting from isolated lesions only located at the ileocolonic anastomosis consistent with a modified Rutgeerts score i2a (these patients are considered as endoscopically non active)

Definition of inactive CD

Harvey-Bradshaw Index (HBI) < 5 and Simple Endoscopic Score for Crohn Disease (SES-CD) < 3

Except SES-CD scores resulting from isolated lesions only located at the ileocolonic anastomosis consistent with a modified Rutgeerts score i2a (these patients are considered as endoscopically non active)

Group 3 (Ulcerative colitis, UC): n= 20 (10 active UC; 10 inactive UC)

Inclusion criteria:

• Colonoscopy indicated by routine clinical care
• Established diagnosis of ulcerative colitis (also if established by the study colonoscopy)

Exclusion criteria:

• Intestinal infection by enteric pathogens

Definition of active UC Total Mayo score ≥ 3 and Endoscopic Mayo subscore ≥ 2

Definition of inactive UC Total Mayo score < 3 and Endoscopic Mayo subscore 0 or 1.

Group 4 (Colorectal cancer): n= 10

Inclusion criteria:

• Diagnosis of a lesion with suspicion for colorectal cancer during endoscopy which is confirmed later by histology

Exclusion criteria:

• None

Group 5 (Colitis/Enteritis of different origin): n= 20

Inclusion criteria:

• Diagnosis of intestinal inflammation at endoscopy or histology
• E.g.: Infectious colitis /enteritis; ischemic Colitis; microscopic colitis; GVHD; NSAID colitis; Colitis of unknown cause

Exclusion criteria:

• None

Healthy controls and active and inactive UC patients