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Fibrinolytic, platelet and monocyte variables in homozygous familial hypercholesterolemia. The effect of a regular plasma cholesterol removal by LDL-apheresis
Fibrinolysis
genotypes with respect to plasma insulin, VLDL-triglyceride and PAI- suggested that the regulation of PAIsynthesis by insulin and VLDL is partly genotype speCifQ The recent interesting developments in molecular biology and cell culture studies seem to support the clinical observation of a direct link between insulin resistance and plasma PAI- 1. An increased plasma PAI- level is one of the major disturbances of the hemostatic system in patients with CHD2 Recently emphasis has been put on the syndrome of insulin resistance and its consequences. Insulin resistance appears involved in the pathogenesis of atherothrombosis on epidemiological grounds. On the basis of what we have cited above it may be proposed that increased PAI- levels have to be added to the constellation of abnormalities observed in the syndrome of insulin resistance explaining further its role in the pathogenesis of atherothrombosis.
References 1.
2. 3.
4.
5.
6.
Hamsten A, De Faire Y, Walldius G, et al. Plasminogen activator inhibitor in plasma. Risk factor for rccurrent myocardial infarction. Lancet 1987; 2: 3-9. J&n-Vague I, Alessi MC. Plasminogcn activator inhibitor 1 and atherothrombosis. Thromb. Haemostas 1993 (In press). De Fronzo RA, Fenannini E. Insulin resistance : A multifaceted syndrome responsible for NIDD, obesity, hypertension, dyslipemia and atherosclerotic cardiovascular disease. Diabetes Care 1991; 14: 173-194. J&an-Vague I, Alessi MC, Vague P. Increased plasma plasminogen activator inhibitor 1 levels. A possible link between insulin resistance and atherothrombosis. Diabetologia 1991; 34: 457-462. Anfosso F, Chomiki N, Alessi MC, Vague P, Juhan-Vague I. Plasminogen activator inhibitor 1 synthesis in the human hepatoma cell line Hep G2. Metformin inhibits the stimulating effect of insulin. J Clin Invest 1993 (In press). Dawson S, Hamsten A, Wiman B, Henney A, Humphries S. Genetic variation at the plasminogen activator inhibitor-l locus is associated with altered levels of plasminogen activator inhibitor 1 activity. Atterioscler Thmmb 1991; 11: 183-190.
63
Fibrinolytic, Platelet and Monocyte Variables in Homozygous Familial Hypercholesterolemia. The Effect of a Regular Plasma Cholesterol Removal by LDL-apheresis Giovanni Di Minno, Anna Maria Cerbone, Alfred0 Tartarone, Anna Pagano, Lucia Soriente, Rosina Albisinni, Antonio Coppola, Umberto Piemontino, Alfred0 Postiglione, Mario Mancini, Angelo M. Scanu Institute of Internal Medicine and Metabolic Diseases, University of Naples; Molecular Medicine, I.R.C.C.S. ‘Casa Sollievo della Soffererua’, S. Giovanni Rotondo, Italy; and Department of Medicine, Biochemistry and Molecular Biology, University of Chicago, USA
Thrombotic complications of atherosclerosis are the major cause of morbidity and mortality in homozygous familial hypercholesterolemia (PII).’ Several hemostatic variables are often abnormal in patients prone to arterial thrombosis? With the exception of platelets? other hemostatic parameters have not been thoroughly investigated in FH patients. It is also known that a regular removal of cholesterol from plasma is an important strategy to control hypercholesterolemia in PH,4 and it is currently thought that LDL-cholesterol levels may affect a variety of hemostatic functions.3 In view of this, we evaluated some fibrinolytic, platelet and monocyte variables in 5 FH patients before and after a single and a regular 5-mo cholesterol removal by LDL-apheresis. We evaluated plasma levels of Lipoprotein (a) [Lp(a)] by an E&ISA method, antigenic and functional values of tissue plasminogen activator [t-PA], and plasminogen activator inhibitor (PAI); the in vitro ability of platelets to aggregate in response to threshold concentrations of Fibrinolytic parameters before and at different time Table intervals after the first LDL-apheresis (Mean f SEM)_F Parameter
Before
Days afrer apheresis 7
Pre-stasis t-PA antigen (q/ml) Post-stasis
8.75 f 2.1
ll.Of1.6
14
10.2 f 2.2
21.5 * 5.7*
26.4 * 4.7+
3.7 f 0.8
4.3 f 1.2
3.9 Lto.7
7.8 f 1.9’
7.5 f 1.s*
7.0 f 1.0*
17.4zts.3 9.2 f 5.0
17.6 zt 5.4 11.3 f 5.2
14.1 f 3.3+ 9.4 f 3.6
Pre-stasis t-PA activity (U/ml) Post-stasis
20.3f4.1*
PAIAntigen (@ml) Activity (U/ml)
t Control values obtained in parallel in control subjects were
:
t-PA antigen pre - 9.6 f 4.3; t-PA antigen post - 23.6 f 10.3; t-PA activity pre - 2.9 f 1.2; t-PA activity post - 7.1 f 2.0; PAI-
antigen - 15.1 f 9.2; PAI activity 8.5 f 4.9
* p
(p always fl.05)
64
fibrinolysis
Tests in Clinical
Practice
ADP, collagen and arachidonic acid; and the expression of procoagulant (tissue factor) activity IpCA] by freshly isolated monocytes in the absence of any detectable stimulation and following incubation for 4 h at 37°C with E. Coli endotoxin (LPS) (10 pg/ml). Details of the methods employed have been reported elsewhere.’ The biweekly procedure determined a 25-30% reduction (about 150 mg/dl) in total and LDL-cholesterol (both >550 mg/dl at the beginning of the study). Lp(a) values, that were abnormally elevated in pre-apheresis samples (4.6 rt: 1.1, ~~0.01 vs controls), were markedly affected by the procedure, and their reduction paralleled that of LDL-cholesterol. Basal levels of t-PA antigen and fibrinolytic activity before and after 10 min of venous stasis, basal PAI activity and PAI- antigen were comparable to controls and were not affected by LDL-apheresis (Table), Likewise, regardless of the cholesterol removal, PCA of freshly isolated monocytes and that of monocytes incubated with LPS did not differ from control values. Finally, pm-aphemsis sensitivity of platelets to ADP, arachidonic acid and collagen was 1.5-2 times the normal value. This ratio was unchanged throughout the 5-mo procedure. We conclude that fibrinolytic parameters and monocyte PCA are normal in FH patients whereas platelet aggregation and plasma Lp(a) levels are abnormally high. At variance with platelet aggregation, Lp(a) levels are significantly affected by LDL-apheresis. Furthermore, our data suggest that removal of cholesterol from the plasma by LDL-apheresis is an important direction to be followed to understand the hemostatic mechanisms involved in the iscbemic complications of atherosclerosis in FH patients.
References 1.
2.
3.
4.
5.
Goldstein JL, Brown MS. Familial hypercholestemlemia : a genetic defect in the low density lipoprotein receptor. N Engl J Med 1976; 294 1386-1390. Davies FA. Detection of a prethmmbotic state. In : Bloom AL, Thomas DP eds. Haemostasis and Thrombosis Edinburgh: Churchill Livingstone, 1987; 721-738. Schick PK. Platelet lipids. In: Colman RW, Himh J. Ma&r VJ Salzman EW, eds. Hemostasis and Thrombosis. Basic principles and Clinical Practice. Philadelphia: Lippincott, 1987: 661-675 Thompson GR, Miller JP. Breslow JL. Improved survival of patients with homozygous familial hypercholesterolemia treated by plasma exchange. Br Med J 1985; 291: 1671-1673. Di MM0 G, G&one AM, Cirillo F, et al. Hemostatic variables in homozygous familial hypercholesterolemia. Effect of a regular plasma cholesterol removal by low density lipoprotein apheresis. Arteriosclerosis 1990; 10: 1119-l 126.
Fibrinolytic
Tests and Venous Thrombophilia
Cristina Legnani Dept. Angiology and Blood Coagulation, University Hospital SOrsola, Bologna, Italy
The term thrombophilia describes the congenital or acquired disorders of the haemostatic mechanism which are likely to predispose to thrombosis. The causal relationship between thrombosis and congenital deficiencies of the main components of the anticoagulant system (antithrombin III, protein C and S) is now well established. A relationship between impaired fibrinolysis and thromboembolism is biologically plausible and alterations of the fibrinolytic system have been suggested as predisposing factors for thrombosis.1-3 Theoretically, the fibrinolytic system can be impaired by deficiencies and/or abnormalities of some of its components (e.g. plasminogen, fibrinogen, factor XII), defective release from the vessel wall of plasminogen activators (t-PA and u-PA), and high inhibitor plasma levels (PAI, histidinerich glycoprotein, a2-antiplasmin).
Plasminogen deficiency Inherited plasminogen deficiency was first described in 1978 since when a number of other plasminogen defect kindreds have been reported (about l-3 8 in juvenile thrombophilic patients). Inherited plasminogen defect can present as hypoplasminogenemia with concomitant decrease in activity and antigen levels (type I deficiency) or as dysplasminogenemia with low activity in presence of normal antigen concentration (type II deficiency). Plasminogen deficiency is inherited as an autosomal dominant trait, but penetrance is very low. Despite the identification of other heterozygotes in propositus families, only a few family members suffered from thrombosis and in many cases only the proband was symptomatic. Thus, the causal relationship between plasminogen deficiency and thrombosis appears weak and it is not possible at present to conclude that plasminogen deficiency is by itself a risk factor for thromboemholism.’
Dysfibrinogenemia Although inherited dysfibrinogenemia is usually asymptomatic or associated with bleeding diathesis, an increased risk of venous or less common arterial thrombosis has been reported in some cases (approximately 10-U%). Congenital dysfibrinogenemia accounts for 1% of unexplained venous thrombosis occurring in young individuals. The mechanisms for the occurrence of thrombosis in patients with dysfibrino-
genotypes with respect to plasma insulin, VLDL-triglyceride and PAI- suggested that the regulation of PAIsynthesis by insulin and VLDL is partly genotype speCifQ The recent interesting developments in molecular biology and cell culture studies seem to support the clinical observation of a direct link between insulin resistance and plasma PAI- 1. An increased plasma PAI- level is one of the major disturbances of the hemostatic system in patients with CHD2 Recently emphasis has been put on the syndrome of insulin resistance and its consequences. Insulin resistance appears involved in the pathogenesis of atherothrombosis on epidemiological grounds. On the basis of what we have cited above it may be proposed that increased PAI- levels have to be added to the constellation of abnormalities observed in the syndrome of insulin resistance explaining further its role in the pathogenesis of atherothrombosis.
References 1.
2. 3.
4.
5.
6.
Hamsten A, De Faire Y, Walldius G, et al. Plasminogen activator inhibitor in plasma. Risk factor for rccurrent myocardial infarction. Lancet 1987; 2: 3-9. J&n-Vague I, Alessi MC. Plasminogcn activator inhibitor 1 and atherothrombosis. Thromb. Haemostas 1993 (In press). De Fronzo RA, Fenannini E. Insulin resistance : A multifaceted syndrome responsible for NIDD, obesity, hypertension, dyslipemia and atherosclerotic cardiovascular disease. Diabetes Care 1991; 14: 173-194. J&an-Vague I, Alessi MC, Vague P. Increased plasma plasminogen activator inhibitor 1 levels. A possible link between insulin resistance and atherothrombosis. Diabetologia 1991; 34: 457-462. Anfosso F, Chomiki N, Alessi MC, Vague P, Juhan-Vague I. Plasminogen activator inhibitor 1 synthesis in the human hepatoma cell line Hep G2. Metformin inhibits the stimulating effect of insulin. J Clin Invest 1993 (In press). Dawson S, Hamsten A, Wiman B, Henney A, Humphries S. Genetic variation at the plasminogen activator inhibitor-l locus is associated with altered levels of plasminogen activator inhibitor 1 activity. Atterioscler Thmmb 1991; 11: 183-190.
63
Fibrinolytic, Platelet and Monocyte Variables in Homozygous Familial Hypercholesterolemia. The Effect of a Regular Plasma Cholesterol Removal by LDL-apheresis Giovanni Di Minno, Anna Maria Cerbone, Alfred0 Tartarone, Anna Pagano, Lucia Soriente, Rosina Albisinni, Antonio Coppola, Umberto Piemontino, Alfred0 Postiglione, Mario Mancini, Angelo M. Scanu Institute of Internal Medicine and Metabolic Diseases, University of Naples; Molecular Medicine, I.R.C.C.S. ‘Casa Sollievo della Soffererua’, S. Giovanni Rotondo, Italy; and Department of Medicine, Biochemistry and Molecular Biology, University of Chicago, USA
Thrombotic complications of atherosclerosis are the major cause of morbidity and mortality in homozygous familial hypercholesterolemia (PII).’ Several hemostatic variables are often abnormal in patients prone to arterial thrombosis? With the exception of platelets? other hemostatic parameters have not been thoroughly investigated in FH patients. It is also known that a regular removal of cholesterol from plasma is an important strategy to control hypercholesterolemia in PH,4 and it is currently thought that LDL-cholesterol levels may affect a variety of hemostatic functions.3 In view of this, we evaluated some fibrinolytic, platelet and monocyte variables in 5 FH patients before and after a single and a regular 5-mo cholesterol removal by LDL-apheresis. We evaluated plasma levels of Lipoprotein (a) [Lp(a)] by an E&ISA method, antigenic and functional values of tissue plasminogen activator [t-PA], and plasminogen activator inhibitor (PAI); the in vitro ability of platelets to aggregate in response to threshold concentrations of Fibrinolytic parameters before and at different time Table intervals after the first LDL-apheresis (Mean f SEM)_F Parameter
Before
Days afrer apheresis 7
Pre-stasis t-PA antigen (q/ml) Post-stasis
8.75 f 2.1
ll.Of1.6
14
10.2 f 2.2
21.5 * 5.7*
26.4 * 4.7+
3.7 f 0.8
4.3 f 1.2
3.9 Lto.7
7.8 f 1.9’
7.5 f 1.s*
7.0 f 1.0*
17.4zts.3 9.2 f 5.0
17.6 zt 5.4 11.3 f 5.2
14.1 f 3.3+ 9.4 f 3.6
Pre-stasis t-PA activity (U/ml) Post-stasis
20.3f4.1*
PAIAntigen (@ml) Activity (U/ml)
t Control values obtained in parallel in control subjects were
:
t-PA antigen pre - 9.6 f 4.3; t-PA antigen post - 23.6 f 10.3; t-PA activity pre - 2.9 f 1.2; t-PA activity post - 7.1 f 2.0; PAI-
antigen - 15.1 f 9.2; PAI activity 8.5 f 4.9
* p
(p always fl.05)
64
fibrinolysis
Tests in Clinical
Practice
ADP, collagen and arachidonic acid; and the expression of procoagulant (tissue factor) activity IpCA] by freshly isolated monocytes in the absence of any detectable stimulation and following incubation for 4 h at 37°C with E. Coli endotoxin (LPS) (10 pg/ml). Details of the methods employed have been reported elsewhere.’ The biweekly procedure determined a 25-30% reduction (about 150 mg/dl) in total and LDL-cholesterol (both >550 mg/dl at the beginning of the study). Lp(a) values, that were abnormally elevated in pre-apheresis samples (4.6 rt: 1.1, ~~0.01 vs controls), were markedly affected by the procedure, and their reduction paralleled that of LDL-cholesterol. Basal levels of t-PA antigen and fibrinolytic activity before and after 10 min of venous stasis, basal PAI activity and PAI- antigen were comparable to controls and were not affected by LDL-apheresis (Table), Likewise, regardless of the cholesterol removal, PCA of freshly isolated monocytes and that of monocytes incubated with LPS did not differ from control values. Finally, pm-aphemsis sensitivity of platelets to ADP, arachidonic acid and collagen was 1.5-2 times the normal value. This ratio was unchanged throughout the 5-mo procedure. We conclude that fibrinolytic parameters and monocyte PCA are normal in FH patients whereas platelet aggregation and plasma Lp(a) levels are abnormally high. At variance with platelet aggregation, Lp(a) levels are significantly affected by LDL-apheresis. Furthermore, our data suggest that removal of cholesterol from the plasma by LDL-apheresis is an important direction to be followed to understand the hemostatic mechanisms involved in the iscbemic complications of atherosclerosis in FH patients.
References 1.
2.
3.
4.
5.
Goldstein JL, Brown MS. Familial hypercholestemlemia : a genetic defect in the low density lipoprotein receptor. N Engl J Med 1976; 294 1386-1390. Davies FA. Detection of a prethmmbotic state. In : Bloom AL, Thomas DP eds. Haemostasis and Thrombosis Edinburgh: Churchill Livingstone, 1987; 721-738. Schick PK. Platelet lipids. In: Colman RW, Himh J. Ma&r VJ Salzman EW, eds. Hemostasis and Thrombosis. Basic principles and Clinical Practice. Philadelphia: Lippincott, 1987: 661-675 Thompson GR, Miller JP. Breslow JL. Improved survival of patients with homozygous familial hypercholesterolemia treated by plasma exchange. Br Med J 1985; 291: 1671-1673. Di MM0 G, G&one AM, Cirillo F, et al. Hemostatic variables in homozygous familial hypercholesterolemia. Effect of a regular plasma cholesterol removal by low density lipoprotein apheresis. Arteriosclerosis 1990; 10: 1119-l 126.
Fibrinolytic
Tests and Venous Thrombophilia
Cristina Legnani Dept. Angiology and Blood Coagulation, University Hospital SOrsola, Bologna, Italy
The term thrombophilia describes the congenital or acquired disorders of the haemostatic mechanism which are likely to predispose to thrombosis. The causal relationship between thrombosis and congenital deficiencies of the main components of the anticoagulant system (antithrombin III, protein C and S) is now well established. A relationship between impaired fibrinolysis and thromboembolism is biologically plausible and alterations of the fibrinolytic system have been suggested as predisposing factors for thrombosis.1-3 Theoretically, the fibrinolytic system can be impaired by deficiencies and/or abnormalities of some of its components (e.g. plasminogen, fibrinogen, factor XII), defective release from the vessel wall of plasminogen activators (t-PA and u-PA), and high inhibitor plasma levels (PAI, histidinerich glycoprotein, a2-antiplasmin).
Plasminogen deficiency Inherited plasminogen deficiency was first described in 1978 since when a number of other plasminogen defect kindreds have been reported (about l-3 8 in juvenile thrombophilic patients). Inherited plasminogen defect can present as hypoplasminogenemia with concomitant decrease in activity and antigen levels (type I deficiency) or as dysplasminogenemia with low activity in presence of normal antigen concentration (type II deficiency). Plasminogen deficiency is inherited as an autosomal dominant trait, but penetrance is very low. Despite the identification of other heterozygotes in propositus families, only a few family members suffered from thrombosis and in many cases only the proband was symptomatic. Thus, the causal relationship between plasminogen deficiency and thrombosis appears weak and it is not possible at present to conclude that plasminogen deficiency is by itself a risk factor for thromboemholism.’
Dysfibrinogenemia Although inherited dysfibrinogenemia is usually asymptomatic or associated with bleeding diathesis, an increased risk of venous or less common arterial thrombosis has been reported in some cases (approximately 10-U%). Congenital dysfibrinogenemia accounts for 1% of unexplained venous thrombosis occurring in young individuals. The mechanisms for the occurrence of thrombosis in patients with dysfibrino-