Assessment Of Circulating Endothelial Cells And Their Progenitors As Potential Biomarkers Of Disease Activity And Damage Accrual In Behçet's Syndrome

PURPOSE: To explore the potential role of circulating endothelial cells (CECs) and their progenitors (EPCs) as biomarkers of disease activity and damage accrual in patients with Behçet's syndrome (BS), by using a standardised and reliable flow cytometry protocol. PATIENTS AND METHODS: CECs and EPCs were assessed in 32 BS patients and 11 gender/age/smoking habits matched healthy controls (HC). They were identified by flow cytometry as alive/nucleated/CD45-negative/CD34-bright/CD146-positive and alive/nucleated/CD45-negative/CD34-bright/CD309-positive events, respectively. In BS patients, demographic and clinical features, including disease activity (assessed by Behçet's disease current disease activity form, BDCAF) and irreversible damage accrual (by the vasculitis damage index, VDI) were recorded. Uni- and multivariate analysis were performed to compare the CECs and EPCs concentrations in BS vs HC and to identify potential associations with demographic or clinical features. RESULTS: The CECs concentration was significantly higher in the BS patients than HCs [median (IQR) 15.0 (7.5-23.0) vs 6.0 (2.0-13.0) CECs/mL, p=0.024]. In BS patients, no significant associations were found between CECs and demographic features, present and past clinical manifestations, BDCAF score and ongoing treatment. A significant association was observed between CECs and organ damage, as assessed by the VDI (rho 0.356, p=0.045). Higher levels of CECs were especially associated with vascular damage [median (IQR) 23.0 (14.0-47.0) vs 13.0 (6.0-19.0) CECs/mL, p=0.011], including arterial aneurysm and stenosis, complicated venous thrombosis, cerebrovascular accident. The concentration of EPCs did not significantly differ between the BS and HC [median 26.5 (13.0-46.0) vs 19.0 (4.0-42.0) EPCs/mL, p=0.316] and no significant associations were observed between their levels and any clinical characteristic. CONCLUSION: Our study suggests that the CECs concentration is significantly higher in BS than healthy subjects, and it mainly correlates with vascular damage. A longitudinal extension of the present study on a wider cohort would be useful to validate the potential role of CECs as a marker or, hopefully, predictor of vascular damage in BS.