Contributions
Abstract: O03
Type: Oral presentation
Session Topic: Inherited and acquired coagulation disorders
Presentation during EHA Scientific Conference on Bleeding Disorders:
On Thursday, September 15, 2016 from 09:00 - 10:30
Location: Rubí + Zafir
Background
Microparticles (MPs) are small membrane vesicles constitutively released from the surface of cells after activation/apoptosis. The best established property of MPs is their ability to promote coagulation, which is largely linked to: i) the presence of phosphatidylserine (PS) on the outer membrane, and ii) the possible presence of tissue factor (TF) on it. Although the presence of MPs has been widely described in hypercoagulable states, their role in hemorrhagic disorders has been poorly evaluated.
Aim
To evaluate the presence and impact of prothrombotic MPs in several congenital bleeding disorders.
Methods
Fifty-three consecutive patients referred to our Unit between 2015 and 2016 who were identified as carriers of inherited bleeding disorders [M/F 30/23; median age 22 years, 12(22%) with hemophilia A, 2(4%) with Hemophilia B, 12(22%) with factor VII deficiency, 8(15%) with FXII deficiency, 6(11%) with FV deficiency, 8(15%) with hypo/dysfibrinogenemia, and 5(11%) with FXIII deficiency] were enrolled. Exclusion criteria were: acute infections, pregnancy/hormonal therapy, cardiovascular diseases, recent surgery, cancer, presence of inhibitor. All samples were performed prior to any administration of factor replacement therapy or plasma. Twenty-six healthy volunteers (M/F 31/25; median age 44 years), friend or companions unrelated to the cases were used as controls. MPs expressing PS, TF-bearing MPS (TF+MPs) and TF pathway inhibitor-bearing MPs (TFPI+MPs) were measured by flow-cytometry using anti-Annexin V-FITC, anti-CD142-PE and anti-TFPI-PE monoclonal antibody, respectively. The ratio of the TF/TFPI expression levels was then used as an index of the procoagulant potential of the MPs and compared between cases and controls.
Results
Overall considered, patients with congenital bleeding disorders showed significantly higher median levels of Annexin V-MPs (3608 [1666-5750] MPs/uL) than healthy controls (2042 [985-3853] MPs/uL, p=0.04). The levels of TF+MPs and TFPI+MPs did not differ significantly between cases and controls. However, the ratio TF/TFPI MPs was significantly higher in cases (1.17 [0.9-1.4]) than in controls (0.94 [0.85-1.13]). Carriers of FVII deficiency and hypo/dysfibrinogenemia showed significantly reduced levels of TFPI+MPs (p=0.002) and a significantly increased TF/TFPI MPs ratio (p=0.019) than healthy controls. Carriers of FXII deficiency showed significantly higher median levels of Annexin V-MPs (p=0.035) and a significantly increased TF/TFPI MPs ratio (p=0.015) compared to healthy subjects. Conversely, carriers of FV deficiency (two of them omozygotes) showed significantly reduced levels of all MPs considered and a significantly reduced ratio (p=0.04) compared to controls. FXIII deficiency carriers (one of them omozygote) presented higher Annexin V-MPs (p=0.0139) median levels and a significant reduction of TF/TFPI MPs ratio (p=0.02) compared to controls. Finally, patients with Hemophilia A and B showed significantly higher levels of Annexin V-MPs (p=0.002) and no difference in other MPs subtypes compared to healthy subjects.
Conclusion
Our study showed that patients with congenital bleeding disorders had an increase TF/TFPI MPs ratio due to reduced levels of TFPI+MPs. MPs may constitute a sort of procoagulant “rescue” mechanism that contribute to inhibit the TFPI pathway and protect carriers of bleeding diathesis. Our results need to be confirmed by larger studies.
References
1. Mooberry, Key, Cytometry 2016; 89: 111-22
2. Lacroix et al, J Thromb Haemost 2013; 11(Suppl1): 24-35
3. Tsimerman et al, Thromb Haemost 2011; 106: 310–321
Abstract: O03
Type: Oral presentation
Session Topic: Inherited and acquired coagulation disorders
Presentation during EHA Scientific Conference on Bleeding Disorders:
On Thursday, September 15, 2016 from 09:00 - 10:30
Location: Rubí + Zafir
Background
Microparticles (MPs) are small membrane vesicles constitutively released from the surface of cells after activation/apoptosis. The best established property of MPs is their ability to promote coagulation, which is largely linked to: i) the presence of phosphatidylserine (PS) on the outer membrane, and ii) the possible presence of tissue factor (TF) on it. Although the presence of MPs has been widely described in hypercoagulable states, their role in hemorrhagic disorders has been poorly evaluated.
Aim
To evaluate the presence and impact of prothrombotic MPs in several congenital bleeding disorders.
Methods
Fifty-three consecutive patients referred to our Unit between 2015 and 2016 who were identified as carriers of inherited bleeding disorders [M/F 30/23; median age 22 years, 12(22%) with hemophilia A, 2(4%) with Hemophilia B, 12(22%) with factor VII deficiency, 8(15%) with FXII deficiency, 6(11%) with FV deficiency, 8(15%) with hypo/dysfibrinogenemia, and 5(11%) with FXIII deficiency] were enrolled. Exclusion criteria were: acute infections, pregnancy/hormonal therapy, cardiovascular diseases, recent surgery, cancer, presence of inhibitor. All samples were performed prior to any administration of factor replacement therapy or plasma. Twenty-six healthy volunteers (M/F 31/25; median age 44 years), friend or companions unrelated to the cases were used as controls. MPs expressing PS, TF-bearing MPS (TF+MPs) and TF pathway inhibitor-bearing MPs (TFPI+MPs) were measured by flow-cytometry using anti-Annexin V-FITC, anti-CD142-PE and anti-TFPI-PE monoclonal antibody, respectively. The ratio of the TF/TFPI expression levels was then used as an index of the procoagulant potential of the MPs and compared between cases and controls.
Results
Overall considered, patients with congenital bleeding disorders showed significantly higher median levels of Annexin V-MPs (3608 [1666-5750] MPs/uL) than healthy controls (2042 [985-3853] MPs/uL, p=0.04). The levels of TF+MPs and TFPI+MPs did not differ significantly between cases and controls. However, the ratio TF/TFPI MPs was significantly higher in cases (1.17 [0.9-1.4]) than in controls (0.94 [0.85-1.13]). Carriers of FVII deficiency and hypo/dysfibrinogenemia showed significantly reduced levels of TFPI+MPs (p=0.002) and a significantly increased TF/TFPI MPs ratio (p=0.019) than healthy controls. Carriers of FXII deficiency showed significantly higher median levels of Annexin V-MPs (p=0.035) and a significantly increased TF/TFPI MPs ratio (p=0.015) compared to healthy subjects. Conversely, carriers of FV deficiency (two of them omozygotes) showed significantly reduced levels of all MPs considered and a significantly reduced ratio (p=0.04) compared to controls. FXIII deficiency carriers (one of them omozygote) presented higher Annexin V-MPs (p=0.0139) median levels and a significant reduction of TF/TFPI MPs ratio (p=0.02) compared to controls. Finally, patients with Hemophilia A and B showed significantly higher levels of Annexin V-MPs (p=0.002) and no difference in other MPs subtypes compared to healthy subjects.
Conclusion
Our study showed that patients with congenital bleeding disorders had an increase TF/TFPI MPs ratio due to reduced levels of TFPI+MPs. MPs may constitute a sort of procoagulant “rescue” mechanism that contribute to inhibit the TFPI pathway and protect carriers of bleeding diathesis. Our results need to be confirmed by larger studies.
References
1. Mooberry, Key, Cytometry 2016; 89: 111-22
2. Lacroix et al, J Thromb Haemost 2013; 11(Suppl1): 24-35
3. Tsimerman et al, Thromb Haemost 2011; 106: 310–321