The study aims to:

1. To determine the relationship between inflammatory activities and epithelial gaps in IBD by CLE and evaluate epithelial gaps healing via dexamethasone treatment.
2. To demonstrated the alteration of local barrier function in IBD using CLE.

The primary end-point of this study was the cohort comparison of epithelial gap density and local barrier function as determined by CLE of subjects with IBD versus controls. Despite discontinuities in the cellular layer, the intestinal barrier function is maintained during this high cell turnover rate at the apical pole of the epithelial layer. Gaps first identified in vivo through acriflavine have pivotal definitions (lacked nuclei or cytosol, appeared to be filled with an impermeable substance). However, Current endoscopic technology does not identify whether there is material present in human gaps, so investigators could not formally resolve whether human epithelial gaps compromise or defend the epithelial barrier.

Inclusion Criteria:

• Male or Female aged 18-80
• IBD： Patients previously diagnosed as having IBD
• Health control: Asymptomatic individuals admitted for health surveillance or patients for follow up after polypectomy.
• Subjects who experienced successful intubation of the terminal ileum.

Exclusion Criteria:

• Subjects age < 18 or >80 years
• Subjects under conditions unsuitable for performing CLE including coagulopathy (prothrombin time <50% of control, partial thromboplastin time >50 s), cirrhosis, renal dysfunction (creatinine level >1.2 mg/dL), pregnancy or breastfeeding, acute gastrointestinal bleeding, jaundice and known allergy to fluorescein sodium.

Patients with indications for colonoscopy in Qilu Hospital outpatient and inpatient department.