- Email: [email protected]
Thrombin-activatable fibrinolysis inhibitor and activated factor XII in patients with systemic lupus erythematosus
Thrombosis Research (2007) 119, 129 — 131
intl.elsevierhealth.com/journals/thre
Letter to the Editors-in-Chief Thrombin-activatable fibrinolysis inhibitor and activated factor XII in patients with systemic lupus erythematosus Dear Sirs, Systemic lupus erythematosus (SLE) is a vasculitis associated with a thromboembolic tendency. Accelerated atherosclerosis and early coronary artery disease are important causes of death and hospitalisation in SLE patients nowadays [1—3]. The increased risk of thromboembolic disease in these patients could be due to an excessive thrombin formation or a defective fibrinolysis. For the latter, a recently described enzyme, the thrombin-activatable fibrinolysis inhibitor (TAFI), is of importance. TAFI protects the fibrin clots from breakdown by removing C-terminal lysine residues from partially degraded fibrin which are necessary for tissue-type plasminogen activator (tPA)-mediated plasmin generation [4]. Elevated levels of TAFI antigen were found to be a mild risk factor for venous thrombosis due to the suppression of fibrinolysis [5—7]. Furthermore, it was recently shown that TAFI levels were significantly higher in patients with Behc¸et’s disease, a systemic vasculitis alike SLE, compared to healthy controls [8]. Therefore, we hypothesised that in SLE patients elevated TAFI antigen levels may be found indicating a suppressed fibrinolysis in these patients. For another hemostatic parameter, activated coagulation factor XII (FXIIa), it was demonstrated recently that patients with rheumatoid arthritis (RA) had significantly higher FXIIa levels compared to healthy control subjects [9]. It was concluded by these authors that the determination of FXIIa may be a useful marker of atherosclerotic disease and could possibly help to identify an bat riskQ group of RA patients, allowing early intervention therapy. Therefore, we hypothesised that for SLE patients which are known to have an increased risk for coronary disease, an increased FXIIa may be expected too.
Hence, we performed a case—control study comparing the levels of TAFI antigen and FXIIa between 67 SLE patients and healthy individuals with no history of thromboembolic events and negative test results for lupus anticoagulant. Control subjects were matched for age, sex, hormone therapy and smoking. Furthermore, we compared the TAFI antigen and FXIIa levels between SLE patients with or without a history of at least one thromboembolic event (arterial or venous), the presence of lupus anticoagulant or both. The 10 male and 57 female SLE patients belonged to the Erlangen cohort [10], followed up at the Department of Internal Medicine III, University Hospital of Erlangen. They were randomly selected irrespective of their disease severity or stage of the disease. None of the patients was clinically suffering from acute thromboembolism. All patients fulfilled the 1997 revised criteria of the American College of Rheumatology (ACR) for the diagnosis of SLE [11]. Mean age [FS.D.] was 40.1 F 14.3 years (range 17 to 69 years) and 40.7 F 14.1 years (range 19 to 68) for the patient and the control group, respectively. In the SLE patient group, 18 individuals (26.9%) had at least one thromboembolic event. Among those, 9 (50.0%), 5 (27.8%) and 4 (22.2%) patients experienced an arterial, venous thromboembolic event or both, respectively. Lupus anticoagulant was present in 23 SLE patients (34.3%). All patients and controls gave written informed consent for the study, which was approved by the local ethics committee. Venous blood samples was collected from antecubital fossa using a 20 G needle. Blood was allowed to flow freely with minimal venous stasis. In accordance with the manufacturer’s instruction, samples were kept at room temperature to avoid cold activation and centrifuged within 60 min of collection at 3.000 G. Plasma was separated and stored at 70 8C until the testing was performed. TAFI antigen concentration was measured using the enzyme-linked immunoassay (ELISA) kit ELISA TAFI Antigen (Haemochrom Diagnostica GmbH, Essen,
0049-3848/$ - see front matter D 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.thromres.2006.01.002
130
Letter to the Editors-in-Chief
Germany). For the determination of XIIa, we used the ELISA kit Activated Factor XII (FXIIa) (AxisShield Diagnostics Ltd., Leewood Business Park, Upton Huntingdon Cambs., United Kingdom). All statistical computations were performed using SAS version 8.02 or SPSS for Windows version 11.5 (SPSS Inc., Chicago, IL). For the comparison of the median TAFI antigen and FXIIa level between all patients and controls, box-plots were used to describe the distribution of the numeric response in each group. Additionally, a Wilcoxon rank sum test was performed. The distribution of the TAFI antigen and FXIIa levels between different SLE subgroups was compared using Kruskal—Wallis Test. We considered differences to be significant when p values were b 0.05. The levels of FXIIa and TAFI antigen were not statistically different between SLE patients and healthy controls (75.7 F 28.6% versus 66.9 F 24.3%, p = 0.07 for TAFI; 0.82 F 0.81 ng/ml versus 0.73 F 0.51 ng/ml, p = 0.36 for FXIIa) (Fig. 1). For TAFI antigen we found a trend towards higher levels for SLE patients. Furthermore, the distribution of TAFI antigen and FXIIa levels was similar for SLE patients with or without either a history of a thrombotic event or the presence of lupus anticoagulant or both. The results of the present study show that neither TAFI antigen nor FXIIa levels were elevated in our SLE patients. This might lead to the conclusion that a reduced fibrinolytic activity or an enhanced activation of the intrinsic coagulation system does not contribute to the known increased thrombotic risk among SLE patients. However, as we observed a trend towards higher TAFI antigen levels among our SLE patients further studies are needed to clarify this question.
In contrast to our data for SLE patients, a significantly elevated TAFI antigen level was found recently for patients with Behc¸et’s disease [8], a systemic vasculitis similar to SLE also known to be associated with an increased risk for arterial and venous thrombosis. Therefore, a reduced fibrinolytic activity might contribute to the thrombotic tendency in patients with Behc¸et’s disease to a higher extent than in patients with SLE. However, surprisingly Donmez et al. found similar TAFI antigen levels for Behc¸et subgroups with or without thrombosis as we did for SLE patients accordingly [8]. They discussed that their somehow discrepant results may have been due to the multifactorial pathogenesis of thrombosis in combination with the low statistical power of their study and the heterogeneity of the thrombotic events in their study. In 2002, McLaren et al. found significantly higher FXIIa levels in patients with rheumatoid arthritis compared to healthy age- and sex-matched controls [9]. Furthermore, 56% of their patients but only 6.7% of their controls showed FXIIa levels greater than or equal to 2 ng/ml, a level being associated with an increased risk for coronary heart disease [12]. Among our SLE patients, only 4 patients (6.0%) and 3 controls (4.5%) showed levels of FXIIa equal to or above 2.0 ng/ml. None of those SLE patients with elevated FXIIa levels experienced any thromboembolic event. Furthermore, the SLE patients with a history of an arterial thromboembolic event did not show higher FXIIa levels than SLE patients without a thromboembolic event or their matched controls. In conclusion, our data suggest that the determination of FXIIa as well as TAFI antigen levels seems not to be helpful to identify individuals with an increased thrombotic risk among SLE patients.
5,00
FXIIa concentration (ng/ml)
TAFI antigen level (%)
150,00
120,00
90,00
60,00
30,00
4,00
3,00
2,00
1,00
0,00
0,00 Patients
Controls
Patients
Controls
Figure 1 Box-plots of the distribution of the TAFI antigen and FXIIa levels in patients and controls (o: outlier, *: extreme outlier).
Letter to the Editors-in-Chief
Acknowledgements This study was supported by the ELAN-Fonds (AZ 02.12.02.1) of the University Hospital of Erlangen/Nuernberg.
References [1] Esdaile JM, Abrahamowicz M, Grodzicky T, Li Y, Panaritis C, du Berger R, et al. Traditional Framingham risk factors fail to fully account for accelerated atherosclerosis in systemic lupus erythematosus. Arthritis Rheum 2001;44:2331 – 7. [2] Manger K, Kusus M, Forster C, Ropers D, Daniel WG, Kalden JR, et al. Factors associated with coronary artery calcification in young female patients with SLE. Ann Rheum Dis 2003;62:846 – 50. [3] Sarzi-Puttini P, Atzeni F, Carrabbba M. Cardiovascular risk factors in systemic lupus erythematosus and in antiphospholipid syndrome. Minerva Med 2003;94:63 – 70. [4] Bajzar L, Manuel R, Nesheim ME. Purification and characterization of TAFI, a thrombin-activatable fibrinolysis inhibitor. J Biol Chem 1995;270:14477 – 84. [5] Van Tilburg NH, Rosendaal FR, Bertina RM. Thrombin activatable fibrinolysis inhibitor and the risk of deep vein thrombosis. Blood 2000;95:2855 – 9. [6] Libourel EJ, Bank I, Meinardi MR, Balje-Volkers CP, Hamulyak D, Middeldorp S, et al. Co-segregation of thrombophilic disorders in factor V Leiden carriers; the contributions of factor VIII, factor XI, thrombin activatable fibrinolysis inhibitor and lipoprotein(a) to the absolute risk of venous thromboembolism. Haematologica 2002;87: 1068 – 73. [7] Mosnier LO, Von dem Borne PA, Meijers JCM, Bouma BN. Plasma TAFI levels influence the clot lysis time in healthy individuals in the presence of an intact intrinsic pathway of coagulation. Thromb Haemost 1998;80:829 – 35. [8] Donmez A, Aksu K, Ak Celik H, Keser G, Cagirgan S, Omay SB, et al. Thrombin activatable fibrinolysis inhibitor in Behc¸et’s disease. Thromb Res 2005;115:287 – 92. [9] McLaren M, Alkaabi J, Connacher M. Activated factor XII in rheumatoid arthritis. Rheumatol Int 2002;22:182 – 4. [10] Manger K, Manger B, Repp R, Geisselbrecht M, Geiger A, Pfahlberg A, et al. Definition of risk factors for death, end stage renal disease, and thromboembolic events in a
131 monocentric cohort of 338 patients with systemic lupus erythematosus. Ann Rheum Dis 2002;61:1065 – 70. [11] Hochberg MC. Updating the American College of Rheumatology revised criteria for the classification of systemic lupus erythematosus. Arthritis Rheum 1997;40:1725. [12] Zito F, Drummond F, Bujac SR, Esnouf MP, Morrissey JH, Humphries SE, et al. Epidemiologic association of activated factor XIIa concentration with factor VII activity, fibriniopeptide A concentration, and risk of coronary heart disease in men. Circulation 2000;102:2058 – 62.
Juergen Ringwald* Stefanie Buettner Robert Zimmermann Volker Weisbach Erwin Strasser Reinhold Eckstein Department of Transfusion Medicine and Haemostaseology, University Hospital of Erlangen/ Nuernberg (Germany), Krankenhausstrasse 12, D-91054 Erlangen, Germany E-mail address: [email protected]. uni-erlangen.de. *Corresponding author. Tel.: +49 9131 85 36972; fax: +49 9131 85 36973. Karin Eckel Department of Medical Informatics, Biometry and Epidemiology, Friedrich-Alexander-University Erlangen/ Nuernberg (Germany), Krankenhausstrasse 12, D-91054 Erlangen, Germany Karin Manger Department of Internal Medicine III and Institute for Clinical Immunology, University Hospital of Erlangen/ Nuernberg (Germany), Krankenhausstrasse 12, D-91054 Erlangen, Germany 2 January 2006
intl.elsevierhealth.com/journals/thre
Letter to the Editors-in-Chief Thrombin-activatable fibrinolysis inhibitor and activated factor XII in patients with systemic lupus erythematosus Dear Sirs, Systemic lupus erythematosus (SLE) is a vasculitis associated with a thromboembolic tendency. Accelerated atherosclerosis and early coronary artery disease are important causes of death and hospitalisation in SLE patients nowadays [1—3]. The increased risk of thromboembolic disease in these patients could be due to an excessive thrombin formation or a defective fibrinolysis. For the latter, a recently described enzyme, the thrombin-activatable fibrinolysis inhibitor (TAFI), is of importance. TAFI protects the fibrin clots from breakdown by removing C-terminal lysine residues from partially degraded fibrin which are necessary for tissue-type plasminogen activator (tPA)-mediated plasmin generation [4]. Elevated levels of TAFI antigen were found to be a mild risk factor for venous thrombosis due to the suppression of fibrinolysis [5—7]. Furthermore, it was recently shown that TAFI levels were significantly higher in patients with Behc¸et’s disease, a systemic vasculitis alike SLE, compared to healthy controls [8]. Therefore, we hypothesised that in SLE patients elevated TAFI antigen levels may be found indicating a suppressed fibrinolysis in these patients. For another hemostatic parameter, activated coagulation factor XII (FXIIa), it was demonstrated recently that patients with rheumatoid arthritis (RA) had significantly higher FXIIa levels compared to healthy control subjects [9]. It was concluded by these authors that the determination of FXIIa may be a useful marker of atherosclerotic disease and could possibly help to identify an bat riskQ group of RA patients, allowing early intervention therapy. Therefore, we hypothesised that for SLE patients which are known to have an increased risk for coronary disease, an increased FXIIa may be expected too.
Hence, we performed a case—control study comparing the levels of TAFI antigen and FXIIa between 67 SLE patients and healthy individuals with no history of thromboembolic events and negative test results for lupus anticoagulant. Control subjects were matched for age, sex, hormone therapy and smoking. Furthermore, we compared the TAFI antigen and FXIIa levels between SLE patients with or without a history of at least one thromboembolic event (arterial or venous), the presence of lupus anticoagulant or both. The 10 male and 57 female SLE patients belonged to the Erlangen cohort [10], followed up at the Department of Internal Medicine III, University Hospital of Erlangen. They were randomly selected irrespective of their disease severity or stage of the disease. None of the patients was clinically suffering from acute thromboembolism. All patients fulfilled the 1997 revised criteria of the American College of Rheumatology (ACR) for the diagnosis of SLE [11]. Mean age [FS.D.] was 40.1 F 14.3 years (range 17 to 69 years) and 40.7 F 14.1 years (range 19 to 68) for the patient and the control group, respectively. In the SLE patient group, 18 individuals (26.9%) had at least one thromboembolic event. Among those, 9 (50.0%), 5 (27.8%) and 4 (22.2%) patients experienced an arterial, venous thromboembolic event or both, respectively. Lupus anticoagulant was present in 23 SLE patients (34.3%). All patients and controls gave written informed consent for the study, which was approved by the local ethics committee. Venous blood samples was collected from antecubital fossa using a 20 G needle. Blood was allowed to flow freely with minimal venous stasis. In accordance with the manufacturer’s instruction, samples were kept at room temperature to avoid cold activation and centrifuged within 60 min of collection at 3.000 G. Plasma was separated and stored at 70 8C until the testing was performed. TAFI antigen concentration was measured using the enzyme-linked immunoassay (ELISA) kit ELISA TAFI Antigen (Haemochrom Diagnostica GmbH, Essen,
0049-3848/$ - see front matter D 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.thromres.2006.01.002
130
Letter to the Editors-in-Chief
Germany). For the determination of XIIa, we used the ELISA kit Activated Factor XII (FXIIa) (AxisShield Diagnostics Ltd., Leewood Business Park, Upton Huntingdon Cambs., United Kingdom). All statistical computations were performed using SAS version 8.02 or SPSS for Windows version 11.5 (SPSS Inc., Chicago, IL). For the comparison of the median TAFI antigen and FXIIa level between all patients and controls, box-plots were used to describe the distribution of the numeric response in each group. Additionally, a Wilcoxon rank sum test was performed. The distribution of the TAFI antigen and FXIIa levels between different SLE subgroups was compared using Kruskal—Wallis Test. We considered differences to be significant when p values were b 0.05. The levels of FXIIa and TAFI antigen were not statistically different between SLE patients and healthy controls (75.7 F 28.6% versus 66.9 F 24.3%, p = 0.07 for TAFI; 0.82 F 0.81 ng/ml versus 0.73 F 0.51 ng/ml, p = 0.36 for FXIIa) (Fig. 1). For TAFI antigen we found a trend towards higher levels for SLE patients. Furthermore, the distribution of TAFI antigen and FXIIa levels was similar for SLE patients with or without either a history of a thrombotic event or the presence of lupus anticoagulant or both. The results of the present study show that neither TAFI antigen nor FXIIa levels were elevated in our SLE patients. This might lead to the conclusion that a reduced fibrinolytic activity or an enhanced activation of the intrinsic coagulation system does not contribute to the known increased thrombotic risk among SLE patients. However, as we observed a trend towards higher TAFI antigen levels among our SLE patients further studies are needed to clarify this question.
In contrast to our data for SLE patients, a significantly elevated TAFI antigen level was found recently for patients with Behc¸et’s disease [8], a systemic vasculitis similar to SLE also known to be associated with an increased risk for arterial and venous thrombosis. Therefore, a reduced fibrinolytic activity might contribute to the thrombotic tendency in patients with Behc¸et’s disease to a higher extent than in patients with SLE. However, surprisingly Donmez et al. found similar TAFI antigen levels for Behc¸et subgroups with or without thrombosis as we did for SLE patients accordingly [8]. They discussed that their somehow discrepant results may have been due to the multifactorial pathogenesis of thrombosis in combination with the low statistical power of their study and the heterogeneity of the thrombotic events in their study. In 2002, McLaren et al. found significantly higher FXIIa levels in patients with rheumatoid arthritis compared to healthy age- and sex-matched controls [9]. Furthermore, 56% of their patients but only 6.7% of their controls showed FXIIa levels greater than or equal to 2 ng/ml, a level being associated with an increased risk for coronary heart disease [12]. Among our SLE patients, only 4 patients (6.0%) and 3 controls (4.5%) showed levels of FXIIa equal to or above 2.0 ng/ml. None of those SLE patients with elevated FXIIa levels experienced any thromboembolic event. Furthermore, the SLE patients with a history of an arterial thromboembolic event did not show higher FXIIa levels than SLE patients without a thromboembolic event or their matched controls. In conclusion, our data suggest that the determination of FXIIa as well as TAFI antigen levels seems not to be helpful to identify individuals with an increased thrombotic risk among SLE patients.
5,00
FXIIa concentration (ng/ml)
TAFI antigen level (%)
150,00
120,00
90,00
60,00
30,00
4,00
3,00
2,00
1,00
0,00
0,00 Patients
Controls
Patients
Controls
Figure 1 Box-plots of the distribution of the TAFI antigen and FXIIa levels in patients and controls (o: outlier, *: extreme outlier).
Letter to the Editors-in-Chief
Acknowledgements This study was supported by the ELAN-Fonds (AZ 02.12.02.1) of the University Hospital of Erlangen/Nuernberg.
References [1] Esdaile JM, Abrahamowicz M, Grodzicky T, Li Y, Panaritis C, du Berger R, et al. Traditional Framingham risk factors fail to fully account for accelerated atherosclerosis in systemic lupus erythematosus. Arthritis Rheum 2001;44:2331 – 7. [2] Manger K, Kusus M, Forster C, Ropers D, Daniel WG, Kalden JR, et al. Factors associated with coronary artery calcification in young female patients with SLE. Ann Rheum Dis 2003;62:846 – 50. [3] Sarzi-Puttini P, Atzeni F, Carrabbba M. Cardiovascular risk factors in systemic lupus erythematosus and in antiphospholipid syndrome. Minerva Med 2003;94:63 – 70. [4] Bajzar L, Manuel R, Nesheim ME. Purification and characterization of TAFI, a thrombin-activatable fibrinolysis inhibitor. J Biol Chem 1995;270:14477 – 84. [5] Van Tilburg NH, Rosendaal FR, Bertina RM. Thrombin activatable fibrinolysis inhibitor and the risk of deep vein thrombosis. Blood 2000;95:2855 – 9. [6] Libourel EJ, Bank I, Meinardi MR, Balje-Volkers CP, Hamulyak D, Middeldorp S, et al. Co-segregation of thrombophilic disorders in factor V Leiden carriers; the contributions of factor VIII, factor XI, thrombin activatable fibrinolysis inhibitor and lipoprotein(a) to the absolute risk of venous thromboembolism. Haematologica 2002;87: 1068 – 73. [7] Mosnier LO, Von dem Borne PA, Meijers JCM, Bouma BN. Plasma TAFI levels influence the clot lysis time in healthy individuals in the presence of an intact intrinsic pathway of coagulation. Thromb Haemost 1998;80:829 – 35. [8] Donmez A, Aksu K, Ak Celik H, Keser G, Cagirgan S, Omay SB, et al. Thrombin activatable fibrinolysis inhibitor in Behc¸et’s disease. Thromb Res 2005;115:287 – 92. [9] McLaren M, Alkaabi J, Connacher M. Activated factor XII in rheumatoid arthritis. Rheumatol Int 2002;22:182 – 4. [10] Manger K, Manger B, Repp R, Geisselbrecht M, Geiger A, Pfahlberg A, et al. Definition of risk factors for death, end stage renal disease, and thromboembolic events in a
131 monocentric cohort of 338 patients with systemic lupus erythematosus. Ann Rheum Dis 2002;61:1065 – 70. [11] Hochberg MC. Updating the American College of Rheumatology revised criteria for the classification of systemic lupus erythematosus. Arthritis Rheum 1997;40:1725. [12] Zito F, Drummond F, Bujac SR, Esnouf MP, Morrissey JH, Humphries SE, et al. Epidemiologic association of activated factor XIIa concentration with factor VII activity, fibriniopeptide A concentration, and risk of coronary heart disease in men. Circulation 2000;102:2058 – 62.
Juergen Ringwald* Stefanie Buettner Robert Zimmermann Volker Weisbach Erwin Strasser Reinhold Eckstein Department of Transfusion Medicine and Haemostaseology, University Hospital of Erlangen/ Nuernberg (Germany), Krankenhausstrasse 12, D-91054 Erlangen, Germany E-mail address: [email protected]. uni-erlangen.de. *Corresponding author. Tel.: +49 9131 85 36972; fax: +49 9131 85 36973. Karin Eckel Department of Medical Informatics, Biometry and Epidemiology, Friedrich-Alexander-University Erlangen/ Nuernberg (Germany), Krankenhausstrasse 12, D-91054 Erlangen, Germany Karin Manger Department of Internal Medicine III and Institute for Clinical Immunology, University Hospital of Erlangen/ Nuernberg (Germany), Krankenhausstrasse 12, D-91054 Erlangen, Germany 2 January 2006