Background:Psoriatic arthritis (PsA) is a chronic inflammatory joint disease which develops in patients with psoriasis. Mortality among patients with PsA is 1.28 times higher than population levels and in most cases it is caused by cardio-vascular diseases (CVD). Those patients have increased risk of clinical and subclinical CVD, mostly due to endothelial dysfunction (ED) and accelerated atherosclerosis. Elevated levels of circulating endothelial cells (CEC) have been described in different cardiovascular pathologies, suggesting their potential use as diagnostic biomarkers for dysfunction of endothelium.Objectives:To identify the potential role of circulating endothelial cells as a marker of cardiovascular diseases in patients with psoriatic arthritis.Methods:In total, ninety-four patients with PsA, who fulfilled the disease criteria (CASPAR) were examined using standard diagnostic methods (including C-reactive protein (CRP), lipid profile) and evaluation endothelium-dependent vasodilation in response to reactive hyperemia (EDVD). Circulating endothelial cells were determined in the peripheral venous blood samples by flow cytometry and counted according to a standardized protocol using a fluorescence microscope after acridine orange labeling. The control group, which were consisted from thirty healthy adults were also examined.Results:CEC were quantified in patients with PsA (7,15 ± 0,19 cells mL−1) and in the control group (4,05 ± 0,11 cells mL−1). Comparing two groups of patients, endothelial circulating cell level was significantly different (p = 0.0001). Finally, we analyzed the relationship between CEC count, comorbidities, cardiovascular risk factors and EDVD in patients with PsA. Increased CEC levels were associated with obesity (r=0,62), duration of disease (r=0,65), age (r=0,67), increased CRP (r=0,76), high blood pressure (r=0,87) and decreased EDVD (r=–0,91).Conclusion:CEC counts were significantly higher in patients with PsA, positively correlated with the main factors of CVD, and another specific marker of ED - EDVD. Elevated CEC levels were also associated with high concentrations of CRP, which plays a direct role in promoting vascular inflammation, vessel damage and clinical CVD events. In conclusion, increased CEC counts provide a direct proof of endothelial damage in patient with PsA and a clinically informative diagnostic tool for endothelial damage in pre-symptomatic CVD. As CEC are one of the most sensitive biomarker for ED, further efforts should concentrate on improving the sensitivity of its detection in order to increase diagnostic sensitivity.References:[1]Maura Farinacci, Thomas Krahn, Wilfried Dinh, et al. Circulating endothelial cells as biomarker for cardiovascular diseases. Res Pract Thromb Haemost, Vol. 3, Issue, 2019, P.49-58;[2]C. Horreau, C. Pouplard, E. Brenautet, et al. Cardiovascular morbidity and mortality in psoriasis and psoriatic arthritis: a systematic literature review. J Eur Acad Dermatol Venereol, Vol. 27, Issue 3, 2013, P.12-19;[3]Frank Verhoeven, Clément Prati, Céline Demougeot, Daniel Wendling. Cardiovascular risk in psoriatic arthritis, a narrative review. Joint Bone Spine, Vol. 87, Issue 5, 2020, P.413-418;Disclosure of Interests:None declared.