Circulating Endothelial Cells are Associated with Thromboembolic Events in Patients with Antiphospholipid Antibodies

Endothelial damage has been described in antiphospholipid antibody (aPL)-positive patients. However, it is uncertain whether circulating endothelial cells (CECs)-which are released when endothelial injury occurs-can be a marker of patients at high risk for thrombosis.

Ninety-seven patients with aPL and/or systemic lupus erythematosus (SLE) were included. CECs were determined by an automated CellSearch system. We also assayed plasma levels of tissue factor-bearing extracellular vesicles (TF⁺/EVs) and soluble triggering receptor expressed on myeloid cells 1 (sTREM-1) as markers of endothelial dysfunction/damage.

Patients' mean age was 46.1 ± 13.9 years, 77 were women. Thirty-seven had SLE and 75 patients were suffering from antiphospholipid syndrome. Thirty-seven percent of patients presented a medical history of arterial thrombosis and 46% a history of venous thromboembolism (VTE). Thirteen patients had increased levels of CECs (>20/mL), with a mean CEC level of 48.3 ± 21.3 per mL. In univariate analysis, patients with obesity or medical history of myocardial infarction (MI), VTE, or nephropathy had a significant increased CEC level. In multivariate analysis, obesity (odds ratio [OR] = 6.07, 95% confidence interval [CI]: 1.42-25.94), VTE (OR = 7.59 [95% CI: 1.38-41.66]), and MI (OR = 5.5 [95% CI: 1.1-26.6)] were independently and significantly associated with elevated CECs. We also identified significant correlations between CECs and other markers of endothelial dysfunction: sTREM-1 and TF⁺/EVs.

This study demonstrated that endothelial injury assessed by the levels of CECs was associated with thromboembolic events in patients with aPL and/or autoimmune diseases.