Avaluation of circulating platelet-derived microparticles in deep venous thrombosis, antibody antiphospholipid syndrome or Leiden factor V

Author(s)

Mariane Cristina Flores Nascimento

• Document type: Master's Dissertation
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Faculdade de Ciências Médicas
• Defense date: 2007-06-22

Examining board members

Joyce Maria Annichino Bizzacchi; Dayse Maria Lourenço; Vagner de Castro

• Advisor: Joyce Maria Annichino Bizzacchi

Abstract

Deep Venous Thrombosis (DVT) is a multicausal disease, but many risk factors are not well defined. Microparticles (MPs) are small blebs released from cellular surfaces during activation and apoptosis. MPs may be the consequence of the dynamics between rest, activation and cellular death and can contribute to the seriousness of the illness and are therefore procoagulant and pro-inflammatory. There seems to be an association between high numbers of MPs and risk of thromboembolic complications and these may have a role in pathogenesis of these illnesses. In this study, we evaluated and characterized the MPs in patients with DVT of inferior limbs, [at diagnosis (5M/4H, medium age= 41.1 years), after 6 months of treatment (7M/3H, medium age= 32.9 years), and associated to Antibody Antiphospholipid Syndrome (7M/3H, medium age= 33.8 years)], and asymptomatic carriers of Factor V Leiden (FVL) (7M, medium age 34= years), matched to health controls by sex, age and ethnic origin. The MPs were isolated from citrated peripheral blood, by differential centrifugation. The quantification and characterization were performed by flow cytometry using the antibodies: CD235, CD61, CD45, CD31, CD14, CD45, anti-TF and Annexin V. The plasmatic procoagulantic activity was investigated by prothrombin fragment 1+2 (F1+2) dosage. The MPs procoagulant activities were analyzed by F1+2 dosage, D-dímer (DD2) and Thrombin Generation Test (TGT) in a pool of healthy individuals in the presence of MPs, corrected or not for number in the sample (10.000 MPs). Statistical analysiswas performed by Wilcoxon or the Mann-Whitney tests, a=0.05. The MPs number were not lower in any of the studied groups. The MPs percentage was statistically increased in the SAF/DVT patients compared to their matched controls (P=0.007). A significant increase in the platelet-derived MPs in SAF/DVT patients (P=0.01) and a reduction in the endothelial-derived MPs at diagnosis were observed (P=.03), when compared to their matched controls. The SAF/TVP patients show a significant reduction in plasmatic F1+2, when compared to their matched controls (P=0.008) and to the total CTR (P=0.002). The F1+2 generated by MPs were significantly lower in FVL carriers compared to the total CTR (0.009), and in SAF/DVT patients compared to their controls (P=0.001), and to the total CTR (P=0.008). The DD2 in the pool of plasma, independently of the number MPs, was significantly higher in DVT at diagnosis when compared to their matched controls (P=0.008) and the total CTR (P=0.0001). The DD2 in the pool with corrected MPs number was significantly higher in DVT at diagnosis patients when compared to their matched controls (P=0,008). The values of TGT in corrected MPs number were statistically lower in patients with DVT after 6 months (P=0.01), in comparison to the total CTR. Our results demonstrated that the number of MPs is modified in patients with DVT, and may play a role, particularly after the thrombotic event or in association with antiphospholipid antibodies. The MPs demonstrated procoagulant activity, especially at DVT diagnosis, and were able to contribute or to aggravate the patient¿s clinical situation (AU)