OP0011 INVESTIGATING THE ROLE OF ENDOTHELIAL DYSFUNCTION IN ANTIPHOSPHOLIPID SYNDROME BY USING PATIENT-SPECIFIC ENDOTHELIAL COLONY-FORMING CELLS
Authors: F. Calcaterra, M. Gerosa, R. Ciceri, M. Bacci, A. Cancellara, F. Tumminello, A. Saresini, C. Iannone, L. M. Argolini, M. P. Donadini, S. Della Bella, C. Lodigiani, D. Mavilio, R. F. Caporali
Journal: Annals of the Rheumatic Diseases (2024)

<h3>Background:</h3> Antiphospholipid syndrome (APS) is an autoimmune disease that can occur either as a primary condition (Primary APS, PAPS) or co-morbidity of an underlying autoimmune disease. APS is characterized by venous thromboembolism, arterial thrombosis and/or pregnancy complications in the presence of medium/high titer antiphospholipid antibodies (aPL). The development of APS thrombotic manifestations is significantly associated with endothelial dysfunction (ED). However, whether ED is a direct consequence of the aPL binding to endothelial cells or represents a host susceptibility factor is not known. In this context, endothelial colony-forming cells (ECFCs) are a valuable tool to investigate alterations of the endothelial compartment in a patient-specific setting. <h3>Objectives:</h3> To investigate the pathophysiology of ED in APS patients. <h3>Methods:</h3> Nineteen patients diagnosed with Primary APS (PAPS), 11 aPL asymptomatic carriers and 27 healthy controls were enrolled. PAPS was diagnosed according to the 2006 Updated Classification Criteria[1] and patients had a history of thrombotic event(s) and/or obstetric complications; aPL carriers fulfilled the laboratory 2006 Updated Classification Criteria, but had no clinical sign(s) of disease. The isolation and expansion of ECFCs from peripheral blood was performed by using a protocol previously optimized in our laboratory[2]. To investigate ED, we assessed: a) ECFC isolation efficiency and cell senescence, b) ECFC phenotype by flow cytometry; c) ECFC ability to promote thrombin formation in an ECFC-based thrombin generation assay (TGA)[3]; d) plasmatic levels of soluble ED markers were measured by Legendplex. <h3>Results:</h3> Although we isolated ECFCs with similar efficiency from PAPS patients, aPL carriers and controls, the presence of constitutive ED was observed only in ECFCs obtained from PAPS patients. Specifically, ECFCs from PAPS patients promoted a faster thrombin generation when used as a substrate in TGA, and were characterized by higher expression levels of the adhesion molecule VCAM-1 and the pro-coagulant molecule tissue factor (TF). Finally, the presence of ED in PAPS patients was further confirmed by the increased plasmatic levels of the soluble form of the adhesion molecules VCAM-1, ICAM-1, PECAM-1, and E-selectin. <h3>Conclusion:</h3> Overall, our findings indicate the presence of constitutive ED in individuals with PAPS, suggesting its potential involvement in APS-related thrombosis. <h3>REFERENCES:</h3> [1] Miyakis S, Lockshin MD, Atsumi T, et al. International consensus statement on an update of the classification criteria for definite antiphospholipid syndrome (APS). <i>J Thromb Haemost.</i> 2006;4:295-306. [2] Colombo E, Calcaterra F, Cappelletti M, Mavilio D, Della Bella S. <i>Comparison of Fibronectin and Collagen in Supporting the Isolation and Expansion of Endothelial Progenitor Cells from Human Adult Peripheral Blood.</i> PLoS One. 2013 Jun 18;8(6):e66734. doi: 10.1371/journal.pone.0066734. [3] Bacci M, Cancellara A, Ciceri R, Romualdi E, Pessi V, Tumminello F, Fantuzzi M, Donadini MP, Lodigiani C, Della Bella S, Calcaterra F, Mavilio D. <i>Development of Personalized Thrombogenesis and Thrombin Generation Assays to Assess Endothelial Dysfunction in Cardiovascular Diseases.</i> Biomedicines. 2023. <h3>Acknowledgements:</h3> <b>NIL.</b> <h3>Disclosure of Interests:</h3> <b>None declared.</b>