Procoagulant Activity of Blood and Endothelial Cells via Phosphatidylserine Exposure and Microparticle Delivery in Patients with Diabetic Retinopathy

Abstract

Background/Aims: The mechanisms for thrombosis in diabetic retinopathy (DR) are complex and need to be further elucidated. The purpose of this study was to test phosphatidylserine (PS) exposure on microparticles (MPs) and MP-origin cells from the circulation and to analyze cell-/MP-associated procoagulant activity (PCA) in DR patients. Methods: PS-positive MPs and cells from healthy controls (n = 20) and diabetic patients (n = 60) were analyzed by flow cytometry and confocal microscopy. Clotting time and purified coagulation complex assays were used to measure PCA. Results: PS exposure on platelets and monocytes was higher in proliferative DR (PDR) patients than in non-PDR patients or controls. The highest levels of MPs (derived from platelets [30%], erythrocytes [13%], leukocytes [28%], and endothelial cells [10%]) were found in patients with PDR. In addition, PS exposure on blood cells and shed MPs in DR patients led to significantly increased FXa and FIIa generation, fibrin formation, and markedly shortened coagulation time. Moreover, lactadherin reduced 70% of PCA by blocking PS, while an anti-tissue factor antibody had a smaller effect. Conclusion: Our results confirmed that PCA in DR patients may be partly ascribed to PS exposure and MP release from blood and endothelial cells. Lactadherin may act as an efficient anticoagulant factor in this process.

Extracellular Vesicles Derived From Platelets, Red Blood Cells, and Monocyte-Like Cells Differ Regarding Their Ability to Induce Factor XII-Dependent Thrombin Generation

“…The different ability of pEVs and monocytic EVs to support FXII-mediated thrombin generation might therefore rather be due to differences in their membrane composition. Based on the primary role of phosphatidylserine in supporting coagulation (Lentz, 2003;Ansari et al, 2016;Su et al, 2018), our data provide evidence that EVs from different sources or settings might differ regarding their exposure of phosphatidylserine. This is further supported by the data obtained with flow cytometric characterization of pEVs, rbcEVs, and mlEVs in the present work, showing higher density of phosphatidylserine on pEVs and rbcEVs as compared to mlEVs.…”

Platelet distribution width, platelet count, and plateletcrit in diabetic retinopathy

“…[36] Studies considered that the most notable reactome pathway of DR was “platelet degranulation.” [37] In addition, procoagulant activity in DR patients may be partly ascribed to phosphatidylserine exposure and microparticles release from blood and endothelial cells. [38] Thus, platelets contribute cooperatively to the hypercoagulable state of DR patients and play an important role in formation of DR.…”

Role of Circulating Microparticles in Type 2 Diabetes Mellitus: Implications for Pathological Clotting

“…71,72 Increased levels of PMPs and MMPs have been reported in patients with DR. 70,76 However, the presence of RMPs, EMPs, LMPs (specifically derived from polynuclear cells), and lymphocyte-derived MPs has also been observed in these patients. 77 Interestingly, it was also found that patients with proliferative DR, the more advanced form of DR, displayed the highest levels of RMPs, EMPs, and polynuclear cell-derived MPs compared with patients without DR. These findings suggest that patients with proliferative DR have more endothelial damage and greater risk of coagulation aberration.…”

“…These findings suggest that patients with proliferative DR have more endothelial damage and greater risk of coagulation aberration. 77 In addition, the authors also observed that the exposure of phosphatidylserine (PS) in MPs is significantly elevated in patients with DR. This increased PS exposure is believed to promote the procoagulant activity of MP in DR patients by facilitating the assembly of prothrombinase complexes and providing a binding site for factor Xa, thus contributing to increased thrombin generation.…”