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Lipoprotein and hepatic lipase activity and high-density lipoprotein subclasses after cardiac transplantation
MISCELLANEOUS
Lipoprotein and Hepatic Lipase Activity and High-Density Lipoprotein Subclasses After Cardiac Transplantation I-!. Robert Superko, MD, William I-. Haskell, PhD, and Connie D. Di Ricco, RN
Atherosclerosis is the leading obstacle to long-term survival in cardiac transplant patients. Increases in plasma triglycerides and lipoprotein cholesterol levels occur after transplantation that may contribute to transplant atherosclerosis. The etiology of this increase is unclear. We investigated the interaction of immunosuppressive medications with plasma triglycerides, low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol, the HDL subclasses HDt.2 and HDLs cholesterol, and hepatic and lipoprotein lipase activity in 72 consecutive cardiac transplant patients compared to 51 healthy control subjects. In the transplantation group, greater concentrations of plasma triglyceride (SO%, p
From the Lipid Research Clinic and Laboratory Center for Research in Disease Prevention, Stanford University School of Medicine, Stanford, California, and The Lawrence Berkeley Laboratory, University of California, Berkeley, California. Manuscript received May 11, 1990; revised manuscript received June 22, 1990, and accepted June 24. Address for reprints: I-I. Robert Superko, MD, Center for Progressive Atherosclerosis Management, Alta Bates-Herrick Hospital, 3030 Telegraph Avenue, Berkeley, California 94705.
ransplant atherosclerosis is the major threat to long-term survival in cardiac transplant patients.’ The pathophysiologic processinvolves immunologic dysfunction, infectious aspects,and lipoprotein abnormalities.2-4 Although lipoprotein cholesterol concentrations tend to increase after transplantation, the mechanism and impact on graft atherosclerosis is unclear.5-7Transplant patients are treated with immunosuppressivemedications that may affect lipoprotein concentrations and consequently transplant atherosclerosis. Recently, cyclosporine was shown to increase lowdensity lipoprotein (LDL) cholesterol and apolipoprotein B significantly in patients with amyotrophic lateral sclerosis.* The lack of a strong association betweenlipoprotein cholesterol and transplant atherosclerosismay, in part, be explained by differences in lipoprotein subclass distribution that are not apparent on routine measuresof triglyceride and lipoprotein cholesterol concentration.9 High-density lipoprotein (HDL) cholesterol can be separated into a nascent cholesterol-poor form (HDLs cholesterol) and a cholesterol-enriched form (HDL2 cholesterol).‘* Low HDL2 cholesterol concentrations have been associatedwith myocardial infarction and the extent of coronary artery diseasedetermined on coronary arteriography in nontransplant coronary artery disease patients.” Treatment with cholestyramine has been reported to be associatedwith an increase in HDLZr, and with a reduced rate of arteriographically defined coronary atherosclerosis progression.’ 2 Mild elevations in plasma triglyceride levels, as often seenin cardiac transplant patients, have been associated with low HDL2 cholesterol and with hyperapobetalipoproteinemia and the small dense LDL syndrome.8,‘3J4Both conditions increase coronary artery diseaserisk. The enzymes lipoprotein lipase and hepatic lipase play central roles in lipoprotein metabolism. Lipoprotein lipase assistsin the metabolism of triglyceride-rich lipoprotein particles and in the modeling of LDL particles, whereas hepatic lipase also acts to model LDL and to remodel HDL2 into HDLs.tS,r6 Although a deficiency of lipoprotein lipase has not been associatedwith coronary artery disease,the effect of a partial deficiency is unclear. The heterozygote state for lipoprotein lipase deficiency may form one subset of familial combined hyperlipidemia. l7 This report describes differences in HDL subclass and lipase activity in cardiac transplant patients that may play a role in transplant atherosclerosis.
THE AMERICAN JOURNAL OF CARDIOLOGY
NOVEMBER 1, 1990
TABLE
I Group Immunosuppressive
Values for Age, Weight Medications
No. Age (YES) Weight (kg) Cyclosporine (mg/kg/day) Azathioprine (mg/kg/day) Prednisone (mg/kg/day)
,
l p
f standard
TABLE
and
Transplant Patients
Control Subjects
72 35*11 83f15 3.2 f 2.3 1.3f 1.1 0.3 f 0.5
51 47 f 10’ 83fll 0 0 0
II Triglyceride
and Lipoprotein
Triglyceride (mg/dl) Total cholesterol (mg/dl) HDL cholesterol (mg/dl) HDL? cholesterol (mg/dl)* HDLs cholesterol (mg/dl): HDLp cholesterol (mg/dl) (%)* LDL cholesterol (mg/dl) Hepatic lipase bmol/FAA/ml/hr) Lipoprotein lipase (pmol/FAA/ml/hr)
devlatlon
Cholesterol
Values
Transplant Patients
Control Subjects
178f 137 243fb4 47.0* 17 8.0f 10 38.8f 11 14f 16 163 * 55 11.8f3.5 -0.4 * 2.0
99*41* 210 f 34* 49.6f 13 9.7 f 11 39.9 * 5 17f12 141 f28’ 5.9 f 1.9* 1.7fl.l’
* P
Consecutive cardiac transplant patients (n = 72,62 men, 10 women) were evaluated during their routine annual visit to the Stanford University cardiac transplantation service. Immunosuppressive drug dosageswere determined as the stable daily dose during the month before the annual visit. This drug dosewas chosen for analysis becauseit most accurately reflects the potential interaction of drug dose and lipoprotein concentrations. Baseline values on 51 healthy male volunteers in a coffee-drinking and lipoprotein metabolism trial were used as control values. TriBlycertdes and lipoprotein choksterd: Control subjects reported for blood sampling in the morning after 12 to 16 hours of abstention from food and vigorous physical activity. Plasma was separated from venous blood within 2 hours, and blood and plasma were kept at 4°C until processed.Plasma total cholesterol and triglyceride levels were measuredby enzymatic procedures (Abbott ABA 200 instrument)iXJ9; HDL cholesterol was determined by the dextran sulfate-magnesium precipitation procedure20;and LDL cholesterol was calculated from the following equation: total cholesterol [HDL cholesterol + (triglycerides/5)]. These measurements were consistently in control, as monitored by the Lipid Standardization Program of the Centers for DiseaseControl and the National Heart, Lung, and Blood Institute. HDL2 cholesterol and HDL3 cholesterol concentrations were determined by a double precipitation method.21 Lipoprotein lipase and hepattc lipase: Lipoprotein lipase activity was determined in the control subjects 15 minutes after injection of sodium heparin (75 U/kg body weight) as previously described by Krauss et al.22 Lipase activity was determined in the cardiac transplant patients immediately before their routine annual coronary arteriograms. Statistical analysis: A StatSoft data management system was used for data analysis.23Group differences were determined by a 2-tailed Student’s t test. Pearson product moment correlations were determined within the transplant group using statistical analysis system. Patient
group:
.I
significantly less (p
1132
THE AMERICAN
JOURNAL
OF CARDIOLOGY
VOLUME
66
DISCUSSION
This investigation revealed significant differences in triglycerides, LDL cholesterol, and lipase activity in cardiac transplant patients compared to healthy control subjects.The lower lipoprotein lipase activity and higher hepatic lipase activity in the transplant patients were correlated with triglyceride and LDL cholesterol. Although HDL and HDLs cholesterol activity was not significantly different between groups, lipoprotein lipase activity correlated with HDL and HDLs cholesterol activity within the transplant group (r = 0.23, r = 0.29). Of the 3 immunosuppressivemedications, only cyclosporine was correlated positively with hepatic lipase activity and inversely with lipoprotein lipase activity. This suggeststhat cyclosporine dose affects lipoprotein metabolism and contributes to a difference in lipase activity and consequentlythe lipoprotein profile. It is unlikely that cyclosporine interferes with the laboratory measurement of lipoprotein cholesterol. Sgoutas and Abbott24 have reported no effect of cyclosporine on total and HDL cholesterol measurement using enzymatic cholesterol assaysand 2 precipitation methods. Routine measuresof lipoprotein cholesterol content can obscure atherogenic lipoprotein differences. These hidden atherogenic patterns include lipase abnormalities, HDL cholesterol subclass distribution, LDL subclass distribution, and hyperapobetalipoproteinemia.8J1,14,25 The latter 3 examples are often associated with modest elevations in plasma triglyceride levels, such.as observedin the cardiac transplant population.i3 Triglyceride, HDL and HDLs cholesterol concentrations are correlated (p <0.002, p <0.05, and p <0.05, respectively) with lipoprotein lipase activity in this transplant group. Lipoprotein lipase activity is inversely associated,and hepatic lipase positively associated,with cyclosporine dose. This suggeststhat cyclosporine may affect lipase activity and consequently triglyceride and LDL cholesterol concentrations and the composition of LDL and HDL particles. A prospective, double-blind, randomized, placebo-controlled trial of cyclosporine has demonstrated a significant increase in LDL cholesterol
16
and apolipoprotein B concentrations after cyclosporine treatment in patients with amyotrophic lateral sclerosis.* In this investigation, cyclosporine treatment also resulted in a significant elevation in blood urea nitrogen and creatinine. The mild elevation in plasma triglycerides may reflect alterations in lipoprotein composition that have been associatedwith atherosclerosis.26y27 This is of particular interest, becausecyclosporine is one of the few drugs transported on lipoprotein particles and, in rats, 80% of plasma cyclosporine is bound to lipoproteins.28,29 The effect of cyclosporine on lipase activity may be due to a direct effect on enzyme activity, an interaction with renal dysfunction, or by altering the function of apolipoprotein C-II. Lipoprotein lipase and hepatic lipase are central to lipoprotein metabolism and affect the production of dense LDL subclassparticles and of HDL2.i5 Hepatic lipase assistsin processing VLDL lipoprotein particles to LDL particles and helps to determine LDL characteristics.15 Lipoprotein lipase facilitates the uptake of unesterified cholesterol and the transfer of cholesterol ester from lipoproteins to ce11s.25,30-32 Rapid postprandial processing of triglyceride-rich particles is associated with lipoprotein lipase activity and decreasesendothelial LDL “dwell time”.33 Thus, the reduced lipoprotein lipase activity documented in this investigation may contribute to transplant atherosclerosisby increasing endothelial contact with small LDL particles, a potentially important aspect of transplant atherosclerosis. In this investigation, prednisone dose revealed no correlation with triglyceride concentrations, lipoprotein cholesterol concentrations, or lipase activity. Despite the widespread use of corticosteroids, their effect on lipoproteins is not well defined. Prednisone has-and has not-been associatedwith lipid changesin patients and healthy subjects.34-36A prospective study revealed no significant change in triglyceride or LDL cholesterol activity, but a significant increase (68%) in that of HDL cholesterol.37Reports of cardiac transplant patients suggest that corticosteroids used in combination with cyclo-
q
Hepatic Lipase
0
Lipoprotein
Lipase
P
14 P
12
FIGURE 1. Lipase activity (mean h standard deviation) in cardiac transplant patients and normal persons in mol FFA/mlhur. FFA = fres fatty acid.
10 umd FFA/ml/‘hr
8
6 4 2 0 -2 Transplant
THE AMERICAN JOURNAL OF CARDIOLOGY NOVEMBER 1, 1990
ga
sporine contribute to increased LDL and HDL cholesterol activity.38,39 Our report indicates that significant differences in lipoprotein values and lipase activity exist between cardiac transplant patients and healthy control subjects. Within the transplant group, cyclosporine dose correlates positively with hepatic lipase activity and inversely with lipoprotein lipase activity. The activity of lipoprotein lipase is, in turn, associatedwith HDL and HDL3 cholesterol concentrations and inversely with triglycerides. Immunosuppressive medications used in the transplant population may adversely impact lipoprotein metabolism and contribute to transplant atherosclerosis. This study suggeststhat cyclosporine doseis significantly associatedwith an adverselipid profile and lipase activity in cardiac transplant patients. Acknowledgment: We would like to acknowledge Ronald M. Krauss, MD, for help in reviewing the manuscript, and Paul Williams, PhD, and Karen Vranizan, MA, for statistical assistance.
REFERENCES 1. Nitkin RS, Hunt SA, Schroeder JS. Accelerated atherosclerosis in a cardiac transplant patient. J Am CON Cardiol 1985;6:243-245. 2. Caplan M, Hastillo A, Mohanakumar T, Hess ML. Immunologic mechanisms in the atherosclerotic process. Cardiouasculor Reviews and Reports 1984;5:713721. 3. McDonald K, Rector TS, Braunlin EA, Kubo SH, Olivari MT. Association of coronary artery disease in cardiac transplant recipients with cytomegalovirus infection. Am J Cardiol 1989;64:359-362. 4. Alonso DR, Starek P, Minick CR. Studies on the pathogenesis of atheroarteriosclerosis induced in rabbit cardiac allografts by the synergy of graft rejection and hypercholesterolemia. Am J Pathol 1977;87:415-442. 5. Ballantyne CM, Jones PH, Payton-Ross C, Patsch W, Short HD, Noon GP, Gotto AM, DeBakey ME, Young JB. Hyperlipidemia following heart transplantation: natural history and intervention with mevinolin (lovastatin). Tram Proc 1987;XIX:60-62. 6. Becker DM, Markakis M, Sension M, Vitalis S, Baughman K, Swank R, Kwiterovich PO, Pearson TA, Achuff SC, Baumgartner WA, Borkon AM, Reitz BA, Trail1 TA. Prevalence of hyperlipidemia in heart transplant recipients. Transplantation 1987;44:323-325. 7. Keogh A, Simons L, Spratt P, Esmore D, Chang V, Hickie J, Baron D. Hyperlipidemia after heart transplantation. J Heart Transplant 1988;7:171-175. 8. Ballantyne CM, Podet EJ, Patsch WP, Harati Y, Appel V, Gotto AM, Young JB. Effects of cyclosporine therapy on plasma lipoprotein levels. JAMA 1989; 262:53-57. 9. Krauss RM. Relationship of intermediate and low-density lipoprotein subspecies to risk of coronary artery disease. Am Heart J 1987;113:578-582. 10. Patsch W, Schonfeld G, Gotto AM, Patsch JR. Characterization of human high density lipoproteins by zonal ultracentrifugation. J Biol Chem 1980; 255:3178-3185. 11. Miller NE. Associations of high-density lipoprotein subclasses and apolipoproteins with ischemic heart disease and coronary atherosclerosis. Am Heart J 1987;113(2 Pt 2):589-597. 12. Krauss RM, Lindgren IT, Williams PT, Kelsey SF, Brensike J, Vranizan K, Detre KM, Levy RI. In&medicate-density lipoproteins and progression of coronary artery disease in hypercholesterolaemic men. Lancet 1987;July 11:62-65. 13. Bieber CP, Hunt S, Schwinn DA, Jamieson SW, R&z BA, Oyer PE,
1134
THE AMERICAN JOURNAL OF CARDIOLOGY VOLUME 66
Shumway NE, Stinson EB. Complications in long-term survivors of cardiac transplantation. Tram Proc 1981:13:207-211. 14. Sniderman AD, Wolfson C, Teng B, Franklin FA, Bachorik PS, Kwiterovich PO. Association of hyperapobetalipoproteinemia with endogenous hypertriglyceridemia and atherosclerosis. Ann Intern Med 1982;97:833-839. 15. Kinnunen PK, Virtanen JA, Vainio P. Lipoprotein lipase and hepatic endothelial lipase: their roles in plasma lipoprotein metabolism. Gotto AM, Paoletti R, eds. Atherosclerosis Reviews, New York: Raven Press, 1983;11:65-105. 16. Auwerx JH, Marzetta CA, Hokanson JE, Brunzell JD. Large buoyant LDLlike particles in hepatic lipase deficiency. Arteriosclerosis 1989;9:319-325. 17. Babirak SP, Iverius PH. Fuiimoto WY. Brunzell JD. Detection and characterization of the heterozygote state for lipoprotein lipase deficiency. Arterioscferosis 1989:9:326-334. 18. Allain CC, Peon LS, Chan CS, Richmond W, Fu PC. Enzymatic determination of total serum cholesterol. Chin Chem 1974;20:470-475. 19. Sampson EJ, Demers LM, K&g AF. Faster enzymatic procedure for serum triglycerides. Clin Chem 1975;21:1983-1985. 20. Warnick GR, Benderson J, Albers JJ. D&ran sulfate-Mg2+ precipitation procedure for quantitation of high-density lipoprotein cholesterol. Clin Chem 1982;28:1379-1388. 21. Warnick GR, Benderson JM, Albers JJ. Quantification of high-density subclasses after separation by d&ran sulfate and Mg2+ precipitation (abstr) Clin Chem 1982;28:1574. 22. Krauss RM, Levv RI. Fredrickson DS. Selective measurement of two lioase activities in post-heparin plasma from normal subjects and patients with hyp’erlioooroteinemia. J Clin Invest 197454: I 107- 1 124. ii. StatSoft statistical system. SiatSoft, Inc. 2325 East 13th Street, Tulsa, Oklahoma 74104. 24. Sgoutas DS, Abbott KL. Cyclosporine does not interfere in total and highdensity lipoprotein cholesterol measurement with use of enzymatic cholesterol assays. Clin Chem 1989;35:2251&2252. 25. Eckel RH. Lipoprotein lipase. A multifunctional enzyme relevant to common metabolic diseases. New Engl J Med 1989;320:1060-1068. 26. Eisenberg S. Lipoprotein abnormalities in hypertriglyceridemia: significance in atherosclerosis. Am Heart J 1987;113:555-561. 27. Austin MA, Breslow JL, Hennekens CH, Buring JE, Will&t WC, Krauss RM. Low density lipoprotein subclass patterns and risk of myocardial infarction. JAMA 1988;260:1917-1921. 28. Gurecki J, Warty V, Sanghvi A. The transport of cyclosporine in association with plasma in heart and liver transplant patients. Trans Proc 1985;17:19972002. 29. Niederberger W, Lemaire M, Maurer G, Nussbaumer K, Wagner 0. Distribution and binding of cyclosporine in blood and tissues. Trans Proc 1983;15:24192421. 30. Zinder 0, Mendelson CR, Blanchette-Mackie EJ, Scow RO. Lipoprotein lipase and uptake of chylomicron triacylglycerol and cholesterol by perfused rat mammary tissue. Biochim Biophys Acta 1976;431:526&537. 31. Fielding CJ. Metabolism of cholesterol rich chyiomicrons. J C/in Invest 1978;62:141-151. 32. Stein 0, Halperin G, Leitersdorf E, Olivecrona T, Stein Y. Lipoprotein lipase mediated uptake of non-degradable ether analogues of phosphatidylcholine and cholesterol ester by cultured cells. Biochim Biophys Acta 1984;795:47-59. 33. Staprans I, Felts JM. A possible mechanism for accelerated atherogenesis in male versus female rats. Arteriosclerosis 1989;9:224-229. 34. Brindly DN. Regulation of hepatic triacylglycerol synthesis and lipoprotein metabolism by glucocorticoids. Chin Sci 1981;61:129-133. 35. Ettinger WH, Goldberg AP, Applebaum-Bowden D, Hazard WR. Dyslipoproteinemia in systemic lupus erythematosus. Effect of corticosteroids. Am J Med 1987;83:503-508. 36. Chan MK, Varghese Z, Persaud JW, Fernando ON, Moorhead JF. The role of multiple pharmaco-therapy in the pathogenesis of hyperlipidemia after renal transplantation. Clin Nephrol 1981;15:309-313. 37. Zimmerman J, Fainaru M, Eisenberg S. The effects of prednisone therapy on plasma lipoproteins and apolipoproteins: a prospective study. Metabolism 1984; 33:521-526. 38. Taylor DO, Thompson JA, Hastillo A, Barnhart G, Rider S, Lower RR, Hess ML. Hyperlipidemia after clinical heart transplantation. J Heart Transplant 1989;8:209-213. 38. Renlund DG, Bristow MR, Crandall BG, Burton NA, Doty DB, Karwande SV, Gay WA, Jones KW, Hegewald MG, Hagan ME, Lee HR, O’Connell JB. Hypercholesterolemia after heart transplantation: amelioration by corticosteroidfree maintenance immunosuppression. J Heart Transplant 1989;8:214-220.
Lipoprotein and Hepatic Lipase Activity and High-Density Lipoprotein Subclasses After Cardiac Transplantation I-!. Robert Superko, MD, William I-. Haskell, PhD, and Connie D. Di Ricco, RN
Atherosclerosis is the leading obstacle to long-term survival in cardiac transplant patients. Increases in plasma triglycerides and lipoprotein cholesterol levels occur after transplantation that may contribute to transplant atherosclerosis. The etiology of this increase is unclear. We investigated the interaction of immunosuppressive medications with plasma triglycerides, low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol, the HDL subclasses HDt.2 and HDLs cholesterol, and hepatic and lipoprotein lipase activity in 72 consecutive cardiac transplant patients compared to 51 healthy control subjects. In the transplantation group, greater concentrations of plasma triglyceride (SO%, p
From the Lipid Research Clinic and Laboratory Center for Research in Disease Prevention, Stanford University School of Medicine, Stanford, California, and The Lawrence Berkeley Laboratory, University of California, Berkeley, California. Manuscript received May 11, 1990; revised manuscript received June 22, 1990, and accepted June 24. Address for reprints: I-I. Robert Superko, MD, Center for Progressive Atherosclerosis Management, Alta Bates-Herrick Hospital, 3030 Telegraph Avenue, Berkeley, California 94705.
ransplant atherosclerosis is the major threat to long-term survival in cardiac transplant patients.’ The pathophysiologic processinvolves immunologic dysfunction, infectious aspects,and lipoprotein abnormalities.2-4 Although lipoprotein cholesterol concentrations tend to increase after transplantation, the mechanism and impact on graft atherosclerosis is unclear.5-7Transplant patients are treated with immunosuppressivemedications that may affect lipoprotein concentrations and consequently transplant atherosclerosis. Recently, cyclosporine was shown to increase lowdensity lipoprotein (LDL) cholesterol and apolipoprotein B significantly in patients with amyotrophic lateral sclerosis.* The lack of a strong association betweenlipoprotein cholesterol and transplant atherosclerosismay, in part, be explained by differences in lipoprotein subclass distribution that are not apparent on routine measuresof triglyceride and lipoprotein cholesterol concentration.9 High-density lipoprotein (HDL) cholesterol can be separated into a nascent cholesterol-poor form (HDLs cholesterol) and a cholesterol-enriched form (HDL2 cholesterol).‘* Low HDL2 cholesterol concentrations have been associatedwith myocardial infarction and the extent of coronary artery diseasedetermined on coronary arteriography in nontransplant coronary artery disease patients.” Treatment with cholestyramine has been reported to be associatedwith an increase in HDLZr, and with a reduced rate of arteriographically defined coronary atherosclerosis progression.’ 2 Mild elevations in plasma triglyceride levels, as often seenin cardiac transplant patients, have been associated with low HDL2 cholesterol and with hyperapobetalipoproteinemia and the small dense LDL syndrome.8,‘3J4Both conditions increase coronary artery diseaserisk. The enzymes lipoprotein lipase and hepatic lipase play central roles in lipoprotein metabolism. Lipoprotein lipase assistsin the metabolism of triglyceride-rich lipoprotein particles and in the modeling of LDL particles, whereas hepatic lipase also acts to model LDL and to remodel HDL2 into HDLs.tS,r6 Although a deficiency of lipoprotein lipase has not been associatedwith coronary artery disease,the effect of a partial deficiency is unclear. The heterozygote state for lipoprotein lipase deficiency may form one subset of familial combined hyperlipidemia. l7 This report describes differences in HDL subclass and lipase activity in cardiac transplant patients that may play a role in transplant atherosclerosis.
THE AMERICAN JOURNAL OF CARDIOLOGY
NOVEMBER 1, 1990
TABLE
I Group Immunosuppressive
Values for Age, Weight Medications
No. Age (YES) Weight (kg) Cyclosporine (mg/kg/day) Azathioprine (mg/kg/day) Prednisone (mg/kg/day)
,
l p
f standard
TABLE
and
Transplant Patients
Control Subjects
72 35*11 83f15 3.2 f 2.3 1.3f 1.1 0.3 f 0.5
51 47 f 10’ 83fll 0 0 0
II Triglyceride
and Lipoprotein
Triglyceride (mg/dl) Total cholesterol (mg/dl) HDL cholesterol (mg/dl) HDL? cholesterol (mg/dl)* HDLs cholesterol (mg/dl): HDLp cholesterol (mg/dl) (%)* LDL cholesterol (mg/dl) Hepatic lipase bmol/FAA/ml/hr) Lipoprotein lipase (pmol/FAA/ml/hr)
devlatlon
Cholesterol
Values
Transplant Patients
Control Subjects
178f 137 243fb4 47.0* 17 8.0f 10 38.8f 11 14f 16 163 * 55 11.8f3.5 -0.4 * 2.0
99*41* 210 f 34* 49.6f 13 9.7 f 11 39.9 * 5 17f12 141 f28’ 5.9 f 1.9* 1.7fl.l’
* P
Consecutive cardiac transplant patients (n = 72,62 men, 10 women) were evaluated during their routine annual visit to the Stanford University cardiac transplantation service. Immunosuppressive drug dosageswere determined as the stable daily dose during the month before the annual visit. This drug dosewas chosen for analysis becauseit most accurately reflects the potential interaction of drug dose and lipoprotein concentrations. Baseline values on 51 healthy male volunteers in a coffee-drinking and lipoprotein metabolism trial were used as control values. TriBlycertdes and lipoprotein choksterd: Control subjects reported for blood sampling in the morning after 12 to 16 hours of abstention from food and vigorous physical activity. Plasma was separated from venous blood within 2 hours, and blood and plasma were kept at 4°C until processed.Plasma total cholesterol and triglyceride levels were measuredby enzymatic procedures (Abbott ABA 200 instrument)iXJ9; HDL cholesterol was determined by the dextran sulfate-magnesium precipitation procedure20;and LDL cholesterol was calculated from the following equation: total cholesterol [HDL cholesterol + (triglycerides/5)]. These measurements were consistently in control, as monitored by the Lipid Standardization Program of the Centers for DiseaseControl and the National Heart, Lung, and Blood Institute. HDL2 cholesterol and HDL3 cholesterol concentrations were determined by a double precipitation method.21 Lipoprotein lipase and hepattc lipase: Lipoprotein lipase activity was determined in the control subjects 15 minutes after injection of sodium heparin (75 U/kg body weight) as previously described by Krauss et al.22 Lipase activity was determined in the cardiac transplant patients immediately before their routine annual coronary arteriograms. Statistical analysis: A StatSoft data management system was used for data analysis.23Group differences were determined by a 2-tailed Student’s t test. Pearson product moment correlations were determined within the transplant group using statistical analysis system. Patient
group:
.I
significantly less (p
1132
THE AMERICAN
JOURNAL
OF CARDIOLOGY
VOLUME
66
DISCUSSION
This investigation revealed significant differences in triglycerides, LDL cholesterol, and lipase activity in cardiac transplant patients compared to healthy control subjects.The lower lipoprotein lipase activity and higher hepatic lipase activity in the transplant patients were correlated with triglyceride and LDL cholesterol. Although HDL and HDLs cholesterol activity was not significantly different between groups, lipoprotein lipase activity correlated with HDL and HDLs cholesterol activity within the transplant group (r = 0.23, r = 0.29). Of the 3 immunosuppressivemedications, only cyclosporine was correlated positively with hepatic lipase activity and inversely with lipoprotein lipase activity. This suggeststhat cyclosporine dose affects lipoprotein metabolism and contributes to a difference in lipase activity and consequentlythe lipoprotein profile. It is unlikely that cyclosporine interferes with the laboratory measurement of lipoprotein cholesterol. Sgoutas and Abbott24 have reported no effect of cyclosporine on total and HDL cholesterol measurement using enzymatic cholesterol assaysand 2 precipitation methods. Routine measuresof lipoprotein cholesterol content can obscure atherogenic lipoprotein differences. These hidden atherogenic patterns include lipase abnormalities, HDL cholesterol subclass distribution, LDL subclass distribution, and hyperapobetalipoproteinemia.8J1,14,25 The latter 3 examples are often associated with modest elevations in plasma triglyceride levels, such.as observedin the cardiac transplant population.i3 Triglyceride, HDL and HDLs cholesterol concentrations are correlated (p <0.002, p <0.05, and p <0.05, respectively) with lipoprotein lipase activity in this transplant group. Lipoprotein lipase activity is inversely associated,and hepatic lipase positively associated,with cyclosporine dose. This suggeststhat cyclosporine may affect lipase activity and consequently triglyceride and LDL cholesterol concentrations and the composition of LDL and HDL particles. A prospective, double-blind, randomized, placebo-controlled trial of cyclosporine has demonstrated a significant increase in LDL cholesterol
16
and apolipoprotein B concentrations after cyclosporine treatment in patients with amyotrophic lateral sclerosis.* In this investigation, cyclosporine treatment also resulted in a significant elevation in blood urea nitrogen and creatinine. The mild elevation in plasma triglycerides may reflect alterations in lipoprotein composition that have been associatedwith atherosclerosis.26y27 This is of particular interest, becausecyclosporine is one of the few drugs transported on lipoprotein particles and, in rats, 80% of plasma cyclosporine is bound to lipoproteins.28,29 The effect of cyclosporine on lipase activity may be due to a direct effect on enzyme activity, an interaction with renal dysfunction, or by altering the function of apolipoprotein C-II. Lipoprotein lipase and hepatic lipase are central to lipoprotein metabolism and affect the production of dense LDL subclassparticles and of HDL2.i5 Hepatic lipase assistsin processing VLDL lipoprotein particles to LDL particles and helps to determine LDL characteristics.15 Lipoprotein lipase facilitates the uptake of unesterified cholesterol and the transfer of cholesterol ester from lipoproteins to ce11s.25,30-32 Rapid postprandial processing of triglyceride-rich particles is associated with lipoprotein lipase activity and decreasesendothelial LDL “dwell time”.33 Thus, the reduced lipoprotein lipase activity documented in this investigation may contribute to transplant atherosclerosisby increasing endothelial contact with small LDL particles, a potentially important aspect of transplant atherosclerosis. In this investigation, prednisone dose revealed no correlation with triglyceride concentrations, lipoprotein cholesterol concentrations, or lipase activity. Despite the widespread use of corticosteroids, their effect on lipoproteins is not well defined. Prednisone has-and has not-been associatedwith lipid changesin patients and healthy subjects.34-36A prospective study revealed no significant change in triglyceride or LDL cholesterol activity, but a significant increase (68%) in that of HDL cholesterol.37Reports of cardiac transplant patients suggest that corticosteroids used in combination with cyclo-
q
Hepatic Lipase
0
Lipoprotein
Lipase
P
14 P
12
FIGURE 1. Lipase activity (mean h standard deviation) in cardiac transplant patients and normal persons in mol FFA/mlhur. FFA = fres fatty acid.
10 umd FFA/ml/‘hr
8
6 4 2 0 -2 Transplant
THE AMERICAN JOURNAL OF CARDIOLOGY NOVEMBER 1, 1990
ga
sporine contribute to increased LDL and HDL cholesterol activity.38,39 Our report indicates that significant differences in lipoprotein values and lipase activity exist between cardiac transplant patients and healthy control subjects. Within the transplant group, cyclosporine dose correlates positively with hepatic lipase activity and inversely with lipoprotein lipase activity. The activity of lipoprotein lipase is, in turn, associatedwith HDL and HDL3 cholesterol concentrations and inversely with triglycerides. Immunosuppressive medications used in the transplant population may adversely impact lipoprotein metabolism and contribute to transplant atherosclerosis. This study suggeststhat cyclosporine doseis significantly associatedwith an adverselipid profile and lipase activity in cardiac transplant patients. Acknowledgment: We would like to acknowledge Ronald M. Krauss, MD, for help in reviewing the manuscript, and Paul Williams, PhD, and Karen Vranizan, MA, for statistical assistance.
REFERENCES 1. Nitkin RS, Hunt SA, Schroeder JS. Accelerated atherosclerosis in a cardiac transplant patient. J Am CON Cardiol 1985;6:243-245. 2. Caplan M, Hastillo A, Mohanakumar T, Hess ML. Immunologic mechanisms in the atherosclerotic process. Cardiouasculor Reviews and Reports 1984;5:713721. 3. McDonald K, Rector TS, Braunlin EA, Kubo SH, Olivari MT. Association of coronary artery disease in cardiac transplant recipients with cytomegalovirus infection. Am J Cardiol 1989;64:359-362. 4. Alonso DR, Starek P, Minick CR. Studies on the pathogenesis of atheroarteriosclerosis induced in rabbit cardiac allografts by the synergy of graft rejection and hypercholesterolemia. Am J Pathol 1977;87:415-442. 5. Ballantyne CM, Jones PH, Payton-Ross C, Patsch W, Short HD, Noon GP, Gotto AM, DeBakey ME, Young JB. Hyperlipidemia following heart transplantation: natural history and intervention with mevinolin (lovastatin). Tram Proc 1987;XIX:60-62. 6. Becker DM, Markakis M, Sension M, Vitalis S, Baughman K, Swank R, Kwiterovich PO, Pearson TA, Achuff SC, Baumgartner WA, Borkon AM, Reitz BA, Trail1 TA. Prevalence of hyperlipidemia in heart transplant recipients. Transplantation 1987;44:323-325. 7. Keogh A, Simons L, Spratt P, Esmore D, Chang V, Hickie J, Baron D. Hyperlipidemia after heart transplantation. J Heart Transplant 1988;7:171-175. 8. Ballantyne CM, Podet EJ, Patsch WP, Harati Y, Appel V, Gotto AM, Young JB. Effects of cyclosporine therapy on plasma lipoprotein levels. JAMA 1989; 262:53-57. 9. Krauss RM. Relationship of intermediate and low-density lipoprotein subspecies to risk of coronary artery disease. Am Heart J 1987;113:578-582. 10. Patsch W, Schonfeld G, Gotto AM, Patsch JR. Characterization of human high density lipoproteins by zonal ultracentrifugation. J Biol Chem 1980; 255:3178-3185. 11. Miller NE. Associations of high-density lipoprotein subclasses and apolipoproteins with ischemic heart disease and coronary atherosclerosis. Am Heart J 1987;113(2 Pt 2):589-597. 12. Krauss RM, Lindgren IT, Williams PT, Kelsey SF, Brensike J, Vranizan K, Detre KM, Levy RI. In&medicate-density lipoproteins and progression of coronary artery disease in hypercholesterolaemic men. Lancet 1987;July 11:62-65. 13. Bieber CP, Hunt S, Schwinn DA, Jamieson SW, R&z BA, Oyer PE,
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