Evaluation of Circulating Endothelial and Platelet Microparticles in Men with Ankylosing Spondylitis

Abstract

To evaluate the profiles of endothelial microparticles (EMP) and platelet microparticles (PMP) in men with ankylosing spondylitis (AS) and healthy subjects. We also aimed to determine whether microparticles (MP) correlate with disease activity, function, and spinal mobility indices. There were 82 men with AS and 53 healthy controls. Subjects with a history of chronic diseases including coronary artery disease, hypertension, diabetes mellitus, and dyslipidemia were excluded. MP were stained with monoclonal antibodies against platelets and endothelial cells and quantified using flow cytometry. MP that were positive for both CD42a+/CD31+ and total CD42a+ were identified as PMP; and MP consisting of CD42a-/CD31+ and total CD144+ were considered EMP. EMP and PMP were similar between the patient and control groups (p > 0.05). Comparison of patients with AS in the active disease state (BASDAI ≥ 4) and in the inactive state showed that EMP and PMP were not different between the groups (p > 0.05). Correlation analysis revealed no correlation with Bath Ankylosing Spondylitis Disease Activity Index, Bath Ankylosing Spondylitis Functional Index, or Bath Ankylosing Spondylitis Metrology Index. C-reactive protein was significantly correlated with PMP and CD42a-/CD31+ EMP (p < 0.05). Comparison of patients with AS treated with anti-tumor necrosis factor (anti-TNF) drugs, subjects treated conventionally, and healthy controls revealed that PMP and CD42a-/CD31+ EMP were significantly downregulated in patients receiving biological agents. Circulating EMP and PMP, known to be indicators and mediators of vascular injury, were not significantly altered in men with AS who did not have classical cardiovascular risk factors. Significantly downregulated MP in patients receiving biological agents suggested that anti-TNF treatment may have a beneficial effect on vascular function in AS.