Proteomic Profiling of Extracellular Vesicles in Inflammatory Bowel Diseases

Background: The proteomic analysis of serum extracellular vesicles (EVs) could be a useful tool for studying the pathophysiology of Crohn’s disease (CD) and ulcerative colitis (UC), as well as for biomarker discovery. Aims: To characterize the proteomic composition of serum EVs in patients with CD and UC to identify biomarkers and molecular pathways associated with pathogenesis and activity. Methods: Serum EVs were enriched and analyzed in patients with quiescent CD, active CD (aCD), quiescent UC, active UC (aUC), and healthy controls (HCs) (n = 30 per group). All groups were matched for age and sex. Disease activity was assessed by ileocolonoscopy and categorized based on the SES-CD (CD) and the endoscopic sub-score of the Mayo Score (UC). EVs were enriched by ultracentrifugation, and their size and concentration were determined by nanoparticle tracking analysis. The expression of CD63, CD81, and CD9 was determined using Western blotting. Proteomic analysis was performed by label-free nano-LC MS/MS. Results: A total of 324 proteins were identified; 60 showed differential abundance in CD-HC, 34 in UC-HC, and 21 in CD-UC. Regarding disease activity, the abundance of 58 and 32 proteins was altered in aCD-HC and aUC-HC, respectively. Functional analyses revealed that proteins associated with aCD were involved in immune regulation, whereas those linked to aUC were enriched in oxidative stress. Conclusions: We have identified expressed proteins between EVs from patients with CD and UC, depending on the presence of disease, the disease type, and the disease activity. These proteins are potential candidates as disease biomarkers and open new research avenues to better understand these conditions.