A Multicenter Prospective Cohort Study on the Clinical Prognosis of Ulcerative Colitis

Inclusion Criteria: * sign informed consent before proceeding with any specific procedure. * ages:14-75 * subjects were diagnosed with ulcerative colitis in written form. (written diagnosis should include at least one histopathological change). * mucosal healing or histological remission has been achieved after medical treatment. 1. histological assessment is performed by 2 pathologists independently, and endoscopy have been independently evaluated by two endoscopic doctors. 2. prospective cohort study (3) definition of endoscopic mucosal healing: Baron score\<=1 and Mayo score\<=1 (4) definition of histological remission: Truelove/ Richards=1 and Geboes score\<3.0 (5) sampling methods: the terminal ileum, the ascending colon, the transverse colon, the descending colon, the sigmoid colon, and the rectum, the six parts were randomly taken specimen (at least 2 tissues each). * data integrity: the research data include: 1) enteroscopy; 2) laboratory examination indicators: blood routine, erythrocyte sedimentation rate, C reaction protein, liver function, renal function, fecal calprotectin, 3) serum concentration of infliximab, antibody to infliximab. * subjects were treated with the following treatment Mesalazine, glucocorticoid, immunosuppressive agent (azathioprine or thalidomide), biologics (infliximab) 7. subjects have the ability to answer the questionnaire Exclusion Criteria: * The diagnosis is unclear * Subjects with history of colectomy * Subjects with history of cancerogenesis * Subjects with severe liver disease, defined as child-pugh Grade B or Grade C * Subjects with severe renal disease, defined as Estimated glomerular filtration rate\<30 * major cardiovascular events, such as stroke, myocardial infarction, or unstable angina, occurred within 3 months before enrollment. * Subjects during pregnancy. * alcohol or drug abuse * poor compliance 10 Planners and investors