THROMBOSIS RESEARCH 66; 391-395,1992 0049-3848/92 $5.00 + .OOPrinted in the USA. Copyright (c) 1992 Pergamon Press Ltd. All rights reserved.
PLASMA FIBRINOLYTIC ACTIVITY IN HEALTHY SUBJECTS WITH HIGH AND LOW LIPOPROTEIN(a) CONCENTRATIONS A. Szczeklik, J. Radwan, A. Kubicka, M. Libura, T. Sacha, J. Swadtba, Szczeklik, and J. Jodlowski
A. Undas, J.
Departments of Medicine and Occupational Diseases, Copernicus Academy of Medicine in Cracow, 8, Skawinska Street, 31-066 Cracow, Poland (Received 17.12.1991; accepted in revised form 6.4.1992 by Editor S. Lopaciuk)
(a), or Lp(a) is present in plasma of virtually everyone. Soon after its was shown to be associated with coronary heart disease; numerous this observation (for ref. see 2). Nevertheless, Lp(a) did not arouse much interest until 1987, when pronounced structural similarities between apo and plasminogen have been described (3). The identification of cDNA for revealed that ape(a) is a giant mutant of plasminogen, the gene for which lies near to that of ape(a) on chromosome 6. The high degree of homolo that ape(a) shares with plasminogen has led several roups to examine potential role o%?Lp(a) m the fibrinolytic system. Recent experiments a ave shown that Lp(a) binds to and displaces plasminogen from its binding sites on fibrin, fibrinogen and cell surfaces (4-7). Lp(a) also inhibits plasminogen activation b the bacterial activator stre tokinase (8), by tissue-type plasminogen activator (t-PA r bound to fibrin fragments P9,lO). These experiments with purified components of the fibrinolytic system suggest that in native plasma of healthy subjects the fibrinolytic activity might show relationship to the Lp(a) concentrations. The data here presented seem to support this view. SUBJECTS Fifty men (aged 22-55 ears; average, 35 years) were selected from a group of 461 healthy em loyees of a local fyoundry who had plasma Lp(a) levels determined by means of rocket e Pectrophoresis (Immuno AG, Austria) 11). These 50 men were divided into two groups: l/ those with Lp(a) levels >30 mg I dl (average, 55 mg/dl) and 2/ those with Lp(a) levels O.20) with res ect to any serum lipid components measured. Following venostasis there was no diFference in any index of fibrinolysis estimated (Table 2, values non-corected for changes in hematocrit). The euglobulin fractions obtained from 5 randomly selected participants were sublected to rocket electrophoresis for determination of Lp(a); all five showed presence of Lp(a) amounting from 90-100% of the concentration present in plasma. TABLE 1. Indices of fibrinolysis before venostasis in group I (Lp(a) > 30 mg/dl) and group II (Lp(a) < 5 mg/dl); means + standard deviations.
Euglobulin filytic activity (mm ) t-PA antigen Ma
PAI- activity
Group I
Group II
66.5219.5
78.6+25.0 -
0.07
4.7+2.7 -
6.0+5.6 -
0.27
1.821.0
1.3+0.4 -
0.30
15.4+11.4 -
0.44
12.4+10.8 -
P
Vol. 66, No. 4
FIBRINOLYSIS
AND LIPOPROTEIN
393
(a)
TABLE 2. Indices of fibrinolysis after venostasis in two groups studied. Group I
Group II
121.3240.8
133.2+43.6 -
0.40
11.6+6.2-
13.1+7.2-
0.40
t-PA activity (IUM)
10.4+7.6-
12.7+8.6-
0.46
PAI- 1 activity (arb U/ml)
13.5+13.0 -
11.7+12.1 -
0.65
Euglobulin fibrinolytic activity (mm ) t-PA antigen
P
(ndml)
140
t
. ”
: : 8 . -.EUGLO@UUN
8
FlBRlNOLYTlC ACTIVIN
”
(mm*)
. .
I > 30 mg/ml
< 5 mglml Serum
Fig. 1. Euglobulin
Lp(a)
fibrinolytic activity in individual subjects of the two groups studied.
394
FIBRINOLYSIS AND LIPOPROTEIN (a)
Vol. 66, No. 4
We studied two groups, high1 contrasted with respect to serum Lp(a) levels. We observed a tendency for lower euglo i:ulin fibrinolytic activity in subjects with high serum Lp(a) as compared to those with barely detectable Lp(a) concentrations. These results cannot be explained by differences in the levels of actrvators or inhibitors of fibrinolysis. Similar1 to recent reports (13-15) we found no relationship between serum Lp(a) and levels o r t-PA antigen, t-PA activity and PAI-1 activity. Our observations could be accounted for by the presence of Lp(a) in euglobulins, which proved to be the case. One could imagine that during long, twenty four hours incubation of fibrin plates with plasma euglobulins, Lp(a) competes with plasmin for fibrin receptors and impedes its access to the natural substrate; this results m impaired fibrin01 sis. Such a conce t is consistent with the idea of local, regulatory functron of Lp(a). f t should be emp Kasized that our results are ertinent to a selected healthy population with sharply different Lp(a) levels. They mig Rt not apply to groups with more overlapin Lp(a) values or to patients in whom other factors might determine the efficacy o f fibrinolysis (14,15).
REFERENCES 1. BERG, K. A new serum type system in man - the LP-system. Acta Path01 Microbial Stand, 59,369-389, 1963. 2. SCANU, A.M., and FLESS, G.M. Li oprotein(a). relevance. J Clin Invest, 85, 1709-1715, 1g 90.
Heterogeneity
and biological
3. MCLEAN, J.W., TOMLINSON, J.E., and KUANG, W.J. cDNA sequence of human apolipoprotein(a) is homologous to plasminogen. Nature, 300, 132-137, 1978. 4. HARPEL, P.C., GORDON, B.R., and PARKER, T.S. Plasmin catalyses binding of lipoprotem(a) to immobilized fibrinogen and fibrin. Proc Nat1 Acad Sci, USA, 86, 3847- 3851,1989. 5. GONZALES-GRONOW, M., EDELBERG? J.M., and PIZZO, S.W. Further characterization of the cellular plasminogen bmding site: Evidence that plasminogen and lipoprotein(a) compete for the same site. Biochemistrv, 28,2375-2377, 1989. 6. MILES, L.A., FLESS, G.M., and LEVINE, E.G. A potential basis for the thrombotic risk associated with hpoprotein(a). Nature, 339,301-303, 1989. 7. HAJJAR, K.A., GAVISH, D., BRESLOW, J.L., and NACHMAN, R. Lipo rotein modulatron of endothelial cell surface fibrinolysis and its potentia P role in atherosclerosis. Nature, 339,303-305, 1989. 8. KARADI, L., KOSTNER, G.M., and GRIES, A. Lipoprotein(a) and plasminogen are immunochemically related. Biochim Bionhvs Acta, 960,91-97, 1988.
Vol. 66, No. 4
FIBRINOLYSIS AND LIPOPROTEIN (a)
395
9. EDELBERG,
J.M., GONZALEZ-GRONOW, M., and PIZZO, S.V. Lipoprotein(a) inhibition of plasminogen activation by tissue-type plasminogen activator. Thromb Res. 57, 155-162, 1990.
10. ROUY, D., GRAILHE, P., NIGON, F., CHAPMAN, J., and ANGLES-CANO, E. Lipoprotein(a) impairs generation of plasmin by fibrin-bound tissue-type plasminogen activator. Arterioscl Thromb, l&629-638, 1991. 11. WANDZILAK, M., JODLOWSKI, J., BOCHENEK, G., MILEWS M., RADWAN, J., KNISZNER, M., MUSIAL, J., SZCZEKLIK, J., and SZC zJE&K, hypertension, arteriosclerosis A. Lipoprotein(a) in obliterans, after myocardial infarction (in Polish). Kard Pol, 34, hypercholesterolemia and 11-16, 1991. 12. ASTRUP, T., and MULLERTZ, S. Fibrin plate method for estimating fibrinolytic activity. Arch Biochem Bioohvs, 40,346-351, 1952. 13. SUNDELL, I.B, NILSSON, T.K., HALLMANS, G., HELLSTEN, G., and DAHLEN, G.H. Interrelationships between plasma levels of plasminogen activator inhibitor, tissue plasminogen activator, lipoprotein(a), and established cardiovascular risk factors in a North Swedish population. Atherosclerosis, 80, 916. 1989. 14. ALESSI, M.C., PARRA, H.J., JOLY, P., VU-DAC, N., BARD, J.M., FRUCHART, J.C., and JUHAN-VAGUE, I. The increase plasma Lp(a): Lipoprotein particle concentration in angina pectoris is not associated with hipofibrinolysis. Clin Chim Acta. 188, 119-128, 1990. 15. GRACIA-FRADE, L.J., ALVAREZ, J.J., RAYO, I., TORRADO, M.C., LASUNCION, M.A., GARCIA-AVELLO, A., HERNANDEZ, A., and MARIN, E. Fibrinolytic parameters and lipoprotein(a) levels in plasma of patients with coronary artery disease. Thromb Res, 63,407-418, 1991.
PLASMA FIBRINOLYTIC ACTIVITY IN HEALTHY SUBJECTS WITH HIGH AND LOW LIPOPROTEIN(a) CONCENTRATIONS A. Szczeklik, J. Radwan, A. Kubicka, M. Libura, T. Sacha, J. Swadtba, Szczeklik, and J. Jodlowski
A. Undas, J.
Departments of Medicine and Occupational Diseases, Copernicus Academy of Medicine in Cracow, 8, Skawinska Street, 31-066 Cracow, Poland (Received 17.12.1991; accepted in revised form 6.4.1992 by Editor S. Lopaciuk)
(a), or Lp(a) is present in plasma of virtually everyone. Soon after its was shown to be associated with coronary heart disease; numerous this observation (for ref. see 2). Nevertheless, Lp(a) did not arouse much interest until 1987, when pronounced structural similarities between apo and plasminogen have been described (3). The identification of cDNA for revealed that ape(a) is a giant mutant of plasminogen, the gene for which lies near to that of ape(a) on chromosome 6. The high degree of homolo that ape(a) shares with plasminogen has led several roups to examine potential role o%?Lp(a) m the fibrinolytic system. Recent experiments a ave shown that Lp(a) binds to and displaces plasminogen from its binding sites on fibrin, fibrinogen and cell surfaces (4-7). Lp(a) also inhibits plasminogen activation b the bacterial activator stre tokinase (8), by tissue-type plasminogen activator (t-PA r bound to fibrin fragments P9,lO). These experiments with purified components of the fibrinolytic system suggest that in native plasma of healthy subjects the fibrinolytic activity might show relationship to the Lp(a) concentrations. The data here presented seem to support this view. SUBJECTS Fifty men (aged 22-55 ears; average, 35 years) were selected from a group of 461 healthy em loyees of a local fyoundry who had plasma Lp(a) levels determined by means of rocket e Pectrophoresis (Immuno AG, Austria) 11). These 50 men were divided into two groups: l/ those with Lp(a) levels >30 mg I dl (average, 55 mg/dl) and 2/ those with Lp(a) levels O.20) with res ect to any serum lipid components measured. Following venostasis there was no diFference in any index of fibrinolysis estimated (Table 2, values non-corected for changes in hematocrit). The euglobulin fractions obtained from 5 randomly selected participants were sublected to rocket electrophoresis for determination of Lp(a); all five showed presence of Lp(a) amounting from 90-100% of the concentration present in plasma. TABLE 1. Indices of fibrinolysis before venostasis in group I (Lp(a) > 30 mg/dl) and group II (Lp(a) < 5 mg/dl); means + standard deviations.
Euglobulin filytic activity (mm ) t-PA antigen Ma
PAI- activity
Group I
Group II
66.5219.5
78.6+25.0 -
0.07
4.7+2.7 -
6.0+5.6 -
0.27
1.821.0
1.3+0.4 -
0.30
15.4+11.4 -
0.44
12.4+10.8 -
P
Vol. 66, No. 4
FIBRINOLYSIS
AND LIPOPROTEIN
393
(a)
TABLE 2. Indices of fibrinolysis after venostasis in two groups studied. Group I
Group II
121.3240.8
133.2+43.6 -
0.40
11.6+6.2-
13.1+7.2-
0.40
t-PA activity (IUM)
10.4+7.6-
12.7+8.6-
0.46
PAI- 1 activity (arb U/ml)
13.5+13.0 -
11.7+12.1 -
0.65
Euglobulin fibrinolytic activity (mm ) t-PA antigen
P
(ndml)
140
t
. ”
: : 8 . -.EUGLO@UUN
8
FlBRlNOLYTlC ACTIVIN
”
(mm*)
. .
I > 30 mg/ml
< 5 mglml Serum
Fig. 1. Euglobulin
Lp(a)
fibrinolytic activity in individual subjects of the two groups studied.
394
FIBRINOLYSIS AND LIPOPROTEIN (a)
Vol. 66, No. 4
We studied two groups, high1 contrasted with respect to serum Lp(a) levels. We observed a tendency for lower euglo i:ulin fibrinolytic activity in subjects with high serum Lp(a) as compared to those with barely detectable Lp(a) concentrations. These results cannot be explained by differences in the levels of actrvators or inhibitors of fibrinolysis. Similar1 to recent reports (13-15) we found no relationship between serum Lp(a) and levels o r t-PA antigen, t-PA activity and PAI-1 activity. Our observations could be accounted for by the presence of Lp(a) in euglobulins, which proved to be the case. One could imagine that during long, twenty four hours incubation of fibrin plates with plasma euglobulins, Lp(a) competes with plasmin for fibrin receptors and impedes its access to the natural substrate; this results m impaired fibrin01 sis. Such a conce t is consistent with the idea of local, regulatory functron of Lp(a). f t should be emp Kasized that our results are ertinent to a selected healthy population with sharply different Lp(a) levels. They mig Rt not apply to groups with more overlapin Lp(a) values or to patients in whom other factors might determine the efficacy o f fibrinolysis (14,15).
REFERENCES 1. BERG, K. A new serum type system in man - the LP-system. Acta Path01 Microbial Stand, 59,369-389, 1963. 2. SCANU, A.M., and FLESS, G.M. Li oprotein(a). relevance. J Clin Invest, 85, 1709-1715, 1g 90.
Heterogeneity
and biological
3. MCLEAN, J.W., TOMLINSON, J.E., and KUANG, W.J. cDNA sequence of human apolipoprotein(a) is homologous to plasminogen. Nature, 300, 132-137, 1978. 4. HARPEL, P.C., GORDON, B.R., and PARKER, T.S. Plasmin catalyses binding of lipoprotem(a) to immobilized fibrinogen and fibrin. Proc Nat1 Acad Sci, USA, 86, 3847- 3851,1989. 5. GONZALES-GRONOW, M., EDELBERG? J.M., and PIZZO, S.W. Further characterization of the cellular plasminogen bmding site: Evidence that plasminogen and lipoprotein(a) compete for the same site. Biochemistrv, 28,2375-2377, 1989. 6. MILES, L.A., FLESS, G.M., and LEVINE, E.G. A potential basis for the thrombotic risk associated with hpoprotein(a). Nature, 339,301-303, 1989. 7. HAJJAR, K.A., GAVISH, D., BRESLOW, J.L., and NACHMAN, R. Lipo rotein modulatron of endothelial cell surface fibrinolysis and its potentia P role in atherosclerosis. Nature, 339,303-305, 1989. 8. KARADI, L., KOSTNER, G.M., and GRIES, A. Lipoprotein(a) and plasminogen are immunochemically related. Biochim Bionhvs Acta, 960,91-97, 1988.
Vol. 66, No. 4
FIBRINOLYSIS AND LIPOPROTEIN (a)
395
9. EDELBERG,
J.M., GONZALEZ-GRONOW, M., and PIZZO, S.V. Lipoprotein(a) inhibition of plasminogen activation by tissue-type plasminogen activator. Thromb Res. 57, 155-162, 1990.
10. ROUY, D., GRAILHE, P., NIGON, F., CHAPMAN, J., and ANGLES-CANO, E. Lipoprotein(a) impairs generation of plasmin by fibrin-bound tissue-type plasminogen activator. Arterioscl Thromb, l&629-638, 1991. 11. WANDZILAK, M., JODLOWSKI, J., BOCHENEK, G., MILEWS M., RADWAN, J., KNISZNER, M., MUSIAL, J., SZCZEKLIK, J., and SZC zJE&K, hypertension, arteriosclerosis A. Lipoprotein(a) in obliterans, after myocardial infarction (in Polish). Kard Pol, 34, hypercholesterolemia and 11-16, 1991. 12. ASTRUP, T., and MULLERTZ, S. Fibrin plate method for estimating fibrinolytic activity. Arch Biochem Bioohvs, 40,346-351, 1952. 13. SUNDELL, I.B, NILSSON, T.K., HALLMANS, G., HELLSTEN, G., and DAHLEN, G.H. Interrelationships between plasma levels of plasminogen activator inhibitor, tissue plasminogen activator, lipoprotein(a), and established cardiovascular risk factors in a North Swedish population. Atherosclerosis, 80, 916. 1989. 14. ALESSI, M.C., PARRA, H.J., JOLY, P., VU-DAC, N., BARD, J.M., FRUCHART, J.C., and JUHAN-VAGUE, I. The increase plasma Lp(a): Lipoprotein particle concentration in angina pectoris is not associated with hipofibrinolysis. Clin Chim Acta. 188, 119-128, 1990. 15. GRACIA-FRADE, L.J., ALVAREZ, J.J., RAYO, I., TORRADO, M.C., LASUNCION, M.A., GARCIA-AVELLO, A., HERNANDEZ, A., and MARIN, E. Fibrinolytic parameters and lipoprotein(a) levels in plasma of patients with coronary artery disease. Thromb Res, 63,407-418, 1991.
