To find high sensitivity and specificity biomarkers to better diagnose and monitor progression of inflammatory bowel disease (IBD). In this study, we try to find miRNAs that can used to diagnose or monitor progression of IBD by exploring differential expression of miRNAs in peripheral blood mononuclear cells (PBMCs) from Crohn's disease, ulcerative colitis and healthy controls. And we further validate these miRNAs in a larger population to assess their function as biomarkers.

Incidence of inflammatory bowel disease (IBD) has been rising in the past decades. However, diagnosis and differential diagnosis of IBD still lack gold standard. To diagnose IBD, physicians need to combine clinical manifestation, lab results, image examination, endoscopy examination and pathology. After diagnosis, patients still need to monitor their disease progression. The most accurate way is to do endoscopy examination, however, endoscopy examination is an invasive, expensive and uncomfortable procedure. At present, C-reactive protein (CRP), erythrocyte sedimentation rate (ESR) and fecal calprotectin are used as main noninvasive biomarkers to monitor progression routinely. But their specificities are still unsatisfactory. So, it's urgent to find high sensitivity and specificity biomarkers to better diagnose and monitor progression of IBD. In this study, we try to find miRNAs that can used to diagnose or monitor progression of IBD by exploring differential expression of miRNAs in peripheral blood mononuclear cells (PBMCs) from Crohn's disease, ulcerative colitis and healthy controls. And we further validate these miRNAs in a larger population to assess their function as biomarkers.

Inclusion Criteria:

• Diagnosed as Crohn's disease (CD) or ulcerative colitis (UC) according to World Health Organization (WHO) criteria
• Vital signs are stable

Exclusion Criteria:

• Refuse to sign consent
• Refuse to do examination to assess their disease progression
• CD patients only upper gastrointestinal tract (GI) is involved (L4)
• Had colectomy or in artificial opening status
• Have other autoimmune comorbidity
• Had severe infection within a week
• Had surgery within a month
• Have malignant tumor
• Pregnancy or lactation

Patients aged 14-75 years old, diagnosed as CD or UC according to WHO criteria, are recruited at specialist IBD clinic. They are excluded if upper GI is the only involved part, had colectomy or in artificial opening status or have other autoimmune comorbidity.