- Email: [email protected]
Effect of aerobic exercise training on plasma levels of tumor necrosis factor alpha in patients with heart failure
5. Shionoiri H, Gotoh E, Takagi N, Takeda K, Yabana M, Kaneko Y. Antihypertensive effects and pharmacokinetics of single and consecutive doses of cilazapril in hypertensive patients with normal and impaired renal function. J Cardiovasc Pharmacol 1988;11:242–249. 6. Colan SD, Borow KM, Newmann A. Left ventricular end-systolic wall stressvelocity of fiber shortening relation: a load-independent index of myocardial contractility. J Am Coll Cardiol 1984;4:715–724. 7. Katayama H. Evaluation of left ventricular function in children with congenital heart disease, a study using end-systolic wall stress-velocity if fiber shortening relation. J Tokyo Women’s Med Coll 1990;60:69–81. 8. Massarella J, DeFeo T, Lin R, Limjuco R, Brown A. The pharmacokinetics and dose proportionality of cilazapril. Br J Clin Pharmacol 1989;27:199S–204S. 9. Dzau VJ. Vascular renin-angiotensin: a possible autocrine or paracrine system in control of vascular function. J Cardiovasc Pharmacol 1984;6(suppl 2):S377– S382. 10. Dzau VJ. Implications of local angiotensin production in cardiovascular physiology and pharmacology. Am J Cardiol 1987;59:59A–65A. 11. Dzau VJ. Circulating versus local renin-angiotensin system in cardiovascular homeostasis. Circulation 1988;77(suppl I):I-1–I-13. 12. Nakamura H, Ishii M, Sugimura T, Chiba K, Kato H, Ishizaki T. The kinetic profiles of enalapril and enalaprilat and their possible developmental changes in pediatric patients with congestive heart failure. Clin Pharmacol Ther 1994;56: 160–168.
13. Alehan D, Ozkutlu S. Beneficial effects of 1-year captopril therapy in children
with chronic aortic regurgitation who have no symptoms. Am Heart J 1998;135: 598–603. 14. Rosenthal E, Francis JR, Brown NA, Rajaguru S, Williams OEP. A pharmacokinetic study of cilazapril in patients with congestive heart failure. Br J Clin Pharmacol 1989;27:267S–273S. 15. Ritter SB, Cooper RS, Golinko RJ. Noninvasive assessment of pulmonary hypertension and pulmonary vascular reactivity in congenital heart disease: pulsed Doppler application. J Cardiovasc Ultrason 1986;5:213–221. 16. Bouthier JD, Safer ME, Benetos A, Simon A, Levenson JA, Hugues CM. Haemodynamic effects of vasodilating drugs on the common carotid and brachial circulations in patients with essential hypertension. Br J Pharmacol 1986;21: 137–142. 17. Simon AC, Levenson AJ, Bouthier JL, Safer ME. Captopril-induced changes in large arteries in essential hypertension. Am J Med 1984;75:71–75. 18. Safer ME, Laurent S, Bouthier JL, London GM. Comparative effects of captopril and isosorbide dinitrate on the arterial wall of hypertensive human brachial arteries. J Cardiovasc Pharmacol 1986;8:1257–1261. 19. Richer C, Thuillez C, Giudicelli JF. Perindopril, converting enzyme blockade, and peripheral arterial hemodynamics in the healthy volunteer. J Cardiovasc Pharmacol 1987;9:94–102. 20. Gray SD. Effect of angiotensin II on neonatal lamb carotid arteries. Experientia 1976;32:350–351.
Effect of Aerobic Exercise Training on Plasma Levels of Tumor Necrosis Factor Alpha in Patients With Heart Failure Alf Inge Larsen,
MD,
Pa˚ l Aukrust, MD, PhD, Torbjørn Aarsland, Kenneth Dickstein, MD, PhD
xercise training has been shown to have beneficial effects on exercise performance and peripheral E pathology, with improvement in the neurohumoral profile in stable patients with congestive heart failure (CHF).1 However, the mechanisms by which exercise training improve cardiovascular function have not been fully clarified. Whether training may influence cytokine levels in such patients is unknown. In the present study we therefore evaluated the effect of a 3-month exercise training program on immunlogic mediators in patients with CHF by examining plasma cytokine levels. We also studied the relation of these changes to improvement in functional status. Recently, immunologic and inflammatory processes have been suggested to play a pathogenic role in CHF. Thus, elevated plasma levels and enhanced myocardial expression have been reported for several proinflammatory cytokines, such as tumor necrosis factor (TNF)-␣ and interleukin 6 in patients with CHF.2– 4 •••
During a period from 1994 to 1996, male outpatients with symptomatic CHF were screened. Left ventricular ejection fraction was determined by radionuclide ventriculography; functional capacity was asFrom the Cardiology Division, Central Hospital in Rogaland, Stavanger; Section of Clinical Immunology and Infectious Disease, Rikshospitalet, Oslo; Research Institute for Internal Medicine, Medical Department, Rikshospitalet, Oslo; and Hjertelaget Research Foundation, Stavanger, Norway. Dr. Larsen’s address is: Cardiology Division, Central Hospital in Rogaland, PO Box 8100 Postterminalen, N-4068 Stavanger, Norway. E-mail: [email protected]. Manuscript received April 4, 2001; revised manuscript received and accepted May 14, 2001. ©2001 by Excerpta Medica, Inc. All rights reserved. The American Journal of Cardiology Vol. 88 October 1, 2001
RN,
and
sessed by the 6-minute walk test and by the cycle ergometer exercise test with peak VO2 determination. Only patients with exercise intolerance, confirmed by a 6-minute walk test ⬍550 m and a peak ergometer cycle exercise test with a peak VO2 consumption ⬍20 ml/kg/min, were eligible. Patients with unstable angina pectoris, serious rhythm disturbance, significant valvular stenosis, symptomatic peripheral vascular disease, obstructive airways disease, or other serious concurrent illness that would reduce exercise capacity (e.g., malignancy and autoimmune disorders) were excluded. Twenty-eight men (mean age 67 ⫾ 8 years) with stable, ischemic CHF for at least 3 months, in New York Heart Association class II to III (mean ejection fraction 32 ⫾ 5%), and on a stable regimen of medical therapy were recruited. The dosages of medicine were kept constant during the training period, and there were no episodes of myocardial infarction and acute coronary syndromes, and there was no need for revascularization during this period. No patient was pacemaker dependent, but 2 patients did have backup VVI pacemakers before entry into the study. The patients were on stable, conventional medical therapy including diuretics (n ⫽ 24), angiotensin-converting enzyme inhibitors or angiotensin II antagonists (n ⫽ 25), and digitalis (n ⫽ 19). No patient was treated with  blockers. There were no clinical signs of infection at the time of the blood withdrawal. To compare cytokine levels, 16 healthy male blood donors were included as a control group (mean age 62 ⫾ 5 years). The protocol was approved by the regional ethical committee, and written informed consent was ob0002-9149/01/$–see front matter PII S0002-9149(01)01859-8
805
TABLE 1 Cytokine Levels in Plasma Before and After Exercise Training in 28 Patients With CHF*
Controls Baseline patients with CHF After 12 wks
TNF-␣ (pg/ml)
IL-6 (pg/ml)
Il-8 (pg/ml)
7.3 ⫾ 3 28.7 ⫾ 18.5†
1.1 ⫾ 0.8 4.6 ⫾ 3.9†
Not detectable 12.7 ⫾ 9.2†
25.1 ⫾ 14.4‡
4.8 ⫾ 5.1
11.2 ⫾ 4.7
*Baseline levels are compared with plasma levels in 16 healthy subjects. † p ⬍0.001 versus controls; ‡p ⫽ 0.013 versus before training. IL ⫽ interleukin.
TABLE 2 TNF-␣ Levels (pg/ml) in Survivors (n ⫽ 16) and Nonsurvivors (n ⫽ 12) Before and After Exercise Training*
Pretraining Post-training Difference After versus before
Survivors
Nonsurvivors
32.3 ⫾ 23.4 24.7 ⫾ 17.5 4.9 ⫾ 7.7 p ⫽ 0.023
24.0 ⫾ 9.4 22.1 ⫾ 6.4 1.9 ⫾ 6.3 NS
*The patient group was followed for 4 years after exercise training.
tained from all patients. This study was an open, unblinded trial designed for evaluating the effect of a 3-month exercise training program. The design, training protocol, and exercise testing protocols have previously been reported.5 Briefly, patients participated in exercise training groups 3 days/week in the rehabilitation center with an instructor specialized in cardiac rehabilitation. The group-training model consisted of 10 minutes of warmup, 25 minutes of endurance training, and 10 minutes of cooling down and stretching. The endurance training was based on callisthenics: low- impact aerobic walking and jogging using the large muscle groups in both the upper and lower extremities at approximately 80% of maximum capacity. The exercises were repeated at least 3 times a week. After 2 weeks of physical training in groups with the instructor at the cardiac rehabilitation center, patients were encouraged to exercise at home on a cycle ergometer for 30 minutes, 3 days/week, with a target heart rate of 80% of the peak in addition to the group training. Patients were evaluated on an upright, electrically braked ergometer bicycle (model KEM III, Mijnhardt, S.V. Bunnik, The Netherlands) using a 15-W/min ramp protocol. Patients were instructed to exercise maximally until symptomatic end points. Gas exchange data were collected continuously with an automated breath-by-breath system (System 2001, Medical Graphics Corporation, St. Paul, Minnesota). Before the maximal exercise test, an arterial cannula (Viggo Spectramed, Helsingborg, Sweden) was placed in the radial artery and fixed to the arm, with a continuous flush device (Abbott intraflo II, Chicago, Illinois, 30 ml/hour) with heparinized saline solution connected. Submaximal exercise test (6-minute walk test). The test was performed according to conventional criteria, and all tests were monitored by the same 806 THE AMERICAN JOURNAL OF CARDIOLOGY姞
VOL. 88
investigator to ensure uniform instruction in a quiet exercise facility.6 Patients were instructed to walk on a Star Track 3028 treadmill (Unisen, Inc, Tustin, California) at an initial speed of 1.0 km/hour and an angle of 0%. The speed and angle was increased according to 1 of 2 alternative protocols based on the patients estimated exercise capacity until a stable heart rate equal to 85% of the peak heart rate, as assessed by the baseline bicycle test, was reached. Patients were then instructed to continue at a constant rate and angle until symptomatic end points or until a total test time of 30 minutes was reached. The 12-week test used an identical protocol to ensure matched work intensities at baseline and after completion of the training. At baseline and at the end of the study, blood was collected from the arterial cannula into pyrogen-free vacuum blood-collection ethylenediaminetetraacetic acid tubes (Becton Dickinson, San Jose, California) after 5 minutes at supine rest before any exercise. The tubes were immediately immersed in melting ice, centrifuged within 15 minutes at 1,000 g and 4°C for 10 minutes, and stored at ⫺80°C. Plasma levels of TNF-␣ were measured by enzyme immunoassays (BioSource Europe, Nivelles, Belgium) as described.7 Plasma levels of interleukin 8 and interleukin 6 were measured by enzyme immunoassays obtained from R&D Systems (Minneapolis, Minnesota). The intraand interassay coefficient of variation was ⬍10% for all assays. All data were entered into a dBase version 5 database and prepared for analysis using SYSTAT version 5 (Evanston, Illinois) and SPSS version 9.0 (SPSS Inc, Chicago, Illinois) software packages. To evaluate the training effect in this open, unblinded trial, we used the paired t test. The values are reported as mean ⫾ 1 SD. The t test was used to calculate a p value for the comparisons of means. We used the Pearsons bivariate correlation test for evaluating the relation between change in cytokine levels and change in exercise performance. The value of significance was set at p ⬍0.05. All patients completed the study, and there were no serious adverse events or requirement for therapy adjustment during the training period. The results of the training program on exercise performance have previously been reported.5 Significant improvement was seen in exercise capacity during the 6-minute walk test (from 511 ⫾ 68 to 550 ⫾ 55 m, 8.1% increase, p ⬍0.001), in maximal workload during the cycle ergometer test (from 27.2 ⫾ 11.36 to 36.4 ⫾ 13.7 kJ, 44.7% increase, p ⬍0.001), and lactic acid production measured as area under the curve (16.7% decrease, p ⬍0.005). At baseline, both TNF-␣ and interleukin 6 and 8 levels were markedly raised in patients with CHF compared with age- and sex-matched healthy controls (Table 1). After 12 weeks of exercise training, there was a significant decrease in TNF-␣ levels from 28.7 ⫾ 19.0 to 25.1 ⫾ 14.4 pg/ml (p ⫽ 0.013) (Table 1), and this decrease was seen in all but 8 patients. The mean reduction was 3.6 ⫾ 7.2 pg/ml. The median OCTOBER 1, 2001
FIGURE 1. Correlation between changes in plasma levels TNF-␣ and changes in peak VO2 during exercise training in survivors (n ⴝ 14).
the median TNF-␣ reduction, we found 5 nonsurvivors in the group above the median and 7 nonsurvivors in the group of patients below the median. However, when dividing the patients by the mean reduction of 3.6 pg/ml, 4 of 12 patients (33%) above the mean died during the 4-year follow-up. In the other group with the smallest reduction of TNF-␣, there were 8 nonsurvivors after 4 years of follow up. Moreover, among survivors, we found a significant correlation between the increase in peak VO2, which was significant in survivors, and the reduction in TNF-␣ levels (r ⫽ ⫺0.643, p ⫽ 0.013, n ⫽ 14) (Figure 1). Two patients were excluded from this analysis of correlation because of the inability to increase heart rate during training. For the whole group, there was a significant correlation between the decrease in TNF-␣ and the increase in distance walked in the 6-minute walk test (r ⫽ ⫺0.427, p ⫽ 0.023) (Figure 2, Table 3). •••
Moderate endurance activity in active, healthy persons has previously been reported not to influence circulating cytokine levels.8,9 In contrast, overtraining and short-term extreme physical activity have been associated with enhanced levels of proinflammatory cytokines (e.g., interleukin 6)10,11 However, the present study is the first to report a downregulation of TNF-␣ levels after a moderate physical training program in patients with CHF, a population with enhanced immune activation at baseline. The mechanisms for such a reduction in TNF-␣ levels are unclear, but may involve a decrease in exercise-induced hypoxia. Hypoxia is a potent stimulus of several proinflammatory cytokines such as TNF-␣.12 Thus, the FIGURE 2. Correlation between changes in 6-minute walk test and in plasma levsignificant correlation between the inels of TNF-␣ during 12 weeks of exercise training in 28 patients with CHF. crease in peak VO2 and the decrease in TNF-␣ found in the present study may reduction was ⫺1 pg/ml. In contrast, exercise training suggest that reduced hypoxia during moderate daily did not induce any significant changes in interleukin 6 activity may be involved in the reduction of TNF-␣ or 8 levels (Table 1). levels after physical training in patients with CHF. During a follow-up period of 4 years, 12 patients However, there was no reduction in interleukin 8 died of progressive heart failure. When dividing the levels after exercise training, another cytokine that study group into survivors and nonsurvivors, we may be induced by hypoxia,13 suggesting that other found that although there there was no significant mechanisms may be involved in the reduction of reduction in TNF-␣ levels after exercise training in TNF-␣ levels during such activity (e.g., altered neunonsurvivors, TNF-␣ decreased from 32.3 ⫾ 23.5 to rohormonal status). Preliminary results suggest that inhibition of 24.7 ⫾ 17.5 pg/ml (p ⫽ 0.023) in survivors (n ⫽ 16) (Table 2). In contrast, there was no significant reduc- TNF-␣ activity may also have beneficial effects in tion in serum levels of interleukin 6 or 8 in either patients with CHF.14 Thus, it is possible that even the survivors or nonsurvivors. When dividing patients by modest decrease in TNF-␣ levels after exercise trainBRIEF REPORTS
807
TABLE 3 Correlations Between Cytokines and Clinical Parameters TNF-␣ Before Training TNF-␣ before training TNF-␣ after training IL 6 before training IL 6 after training IL 8 before training IL 8 after training VO2 baseline VO2 after training Delta VO2 Workload baseline Workload after training Delta workload 6-min walk baseline 6-min walk after training Delta 6-min walk test
TNF-␣ After Training
0.148 0.258 0.286 0.273 ⫺0.139 0.076 0.230 ⫺0.199 ⫺0.259 0.298 ⫺0.194 ⫺0.156
⫺0.794† ⫺0.566* ⫺0.317* ⫺0.131 ⫺0.490† ⫺0.359 0.264 ⫺0.007 ⫺0.318 0.033 ⫺0.135 ⫺0.199 0.113 ⫺0.201
0.105
⫺0.427*
0.951† 0.951† 0.228 0.240 0.395* 0.336 ⫺0.202 0.059 0.290 ⫺0.159 0.109 0.295 ⫺0.186 ⫺0.039 0.238
TNF-␣ Difference
*p ⫽ 0.05 (2-tailed). † p ⫽ 0.01 (2-tailed). R values obtained by Pearson’s correlation test. Abbreviation as in Table 1.
ing observed in the present study is associated with clinical improvement. After exercise training, we found a significant correlation between the decrease in TNF-␣ and the increase in peak VO2 in survivors, and with the increase in the 6-minute walk test for the entire group. Enhanced activity of the TNF systems appears to have prognostic significance.15 In the present study a decrease in TNF-␣ during exercise training was associated with improved long-time survival, suggesting that the decrease in TNF-␣ levels may be of clinical relevance. We recently reported that either angiotensin-converting enzyme inhibitors or  blockers may downregulate elevated levels of cytokines in patients with CHF.16,17 Therefore, exercise training may be beneficial in patients with CHF on optimal medical therapy, at least partly by downregulating TNF-␣ levels. In summary, the present study demonstrates that aerobic exercise training reduces pathologically increased TNF ␣ levels in patients with CHF. This modest reduction was associated with improved exercise performance.
808 THE AMERICAN JOURNAL OF CARDIOLOGY姞
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Acknowledgment: The expert assistance of Marit Kristiansen, PT, and Anne Haugland, PT, in designing and performing the training program is highly appreciated.
1. Coats AJ, Adamopoulos S, Radaelli A, McCance A, Meyer TE, Bernardi L,
Solda PL, Davey P, Ormerod O, Forfar C. Controlled trial of physical training in chronic heart failure. Exercise performance, hemodynamics, ventilation and autonomic function. Circulation 1992;85:2119–2131. 2. Seta Y, Shan K, Bozkurt B, Oral H, Mann DL. Basic mechanisms in heart failure: the cytokine hypothesis. J Cardiac Failure 1996;2:243–249. 3. Aukrust P, Ueland T, Lien E, Bendtzen K, Muller F, Andreassen AK, Nordoy I, Aass H, Espevik T, Simonsen S, Froland SS, Gullestad L. Cytokine network in congestive heart failure secondary to ischemic or idiopathic cardiomyopathy. Am J Cardiol 1999;83:376–382. 4. Torre-Amione G, Kapadia S, Lee J, Durand JB, Bies RD, Young JB, Mann DL. Tumor necrosis factor receptors in the failing human heart. Circulation 1996;15: 704–711. 5. Larsen AI, Aarsland T, Kristiansen M, Haugland A, Dickstein K. Assessing the effect of exercise training in men with heart failure. Comparison of maximal, submaximal and endurance exercise protocols. Eur Heart J 2001;22:684 – 692. 6. Riley M, McParland J, Stanford CF, Nicholls DP. Oxygen consumption during corridor walk testing in chronic cardiac failure. Eur Heart J 1992;13:789–793. 7. Aukrust P, Lien E, Kristoffersen AK, Muller F, Haug CJ, Espevik T, Froland SS. Persistent activation of the tumor necrosis factor system in a subgroup of patients with common variable immunodeficiency-possible immunologic and clinical consequences. Blood 1996;87:674–681. 8. Shepard RJ, Shek P. Impact of physical activity and sport on the immune system. Rev Environ Health 1996;11:133–147. 9. Smith JA, Telford RD, Baker MS, Hapel AJ, Weidemann MJ. Cytokine immunoreactivity in plasma does not change after moderate endurance exercise. J Appl Physiol 1992;73:1396–1401. 10. Moldoveanu AI, Shephard R, Shek PN. Exercise elevates plasma levels but not gene expression of IL-1beta, IL-6, and TNF-alpha in blood mononuclear cells. J Appl Physiol 2000;89:1499–1504. 11. Smith LL. Cytokine hypothesis of overtraining; a physiological adaptation to excessive stress. Med Sci Sports Exerc 2000;32:317–331. 12. Chandel NS, Trzyna WC, McClintock DS, Schumacker PT. Role of oxidants in NF-kappa B activation and TNF-alpha gene transcription induced by hypoxia and endotoxin. J Immunol 2000;165:1013–1021. 13. Karakurum M, Shreeniwas R, Chen J, Pinsky D, Yan SD, Anderson M, Sunouchi K, Major J, Hamilton T, Kuwabara K. Hypoxic induction of interleukin-8 gene expression in human endothelial cells. J Clin Invest 1994;93:1564– 1570. 14. Deswal A, Bozkurt B, Seta Y, Parilti-Eiswirth S, Hayes FA, Blosch C, Mann DL. Safety and efficacy of a soluble P75 tumor necrosis factor receptor (Enbrel, etanercept) in patients with advanced heart failure. Circulation 1999;99:3224– 3226. 15. Rauchhaus M, Doehner W, Francis DP, Davos C, Kemp M, Liebenthal C, Niebauer J, Hooper J, Volk HD, Coats AJ, Anker SD. Plasma cytokine parameters and mortality in patients with chronic heart failure. Circulation 2000;102: 3060–3067. 16. Gullestad L, Aukrust P, Ueland T, Espevik T, Yee G, Vagelos R, Froland SS, Fowler M. Effect of high-versus low-dose angiotensin converting enzyme inhibiton on cytokine levels in chronic heart failure. J Am Coll Cardiol 1999;34:2061– 2067. 17. Gullestad L, Ueland T, Brunsvig A, Kjekshus J, Simonsen S, Froland SS, Aukrust P. Effect of metoprolol on cytokine levels in chronic heart failure—a sub study in the MERIT-HF trial. Am Heart J 2001;141:418 – 421.
OCTOBER 1, 2001
13. Alehan D, Ozkutlu S. Beneficial effects of 1-year captopril therapy in children
with chronic aortic regurgitation who have no symptoms. Am Heart J 1998;135: 598–603. 14. Rosenthal E, Francis JR, Brown NA, Rajaguru S, Williams OEP. A pharmacokinetic study of cilazapril in patients with congestive heart failure. Br J Clin Pharmacol 1989;27:267S–273S. 15. Ritter SB, Cooper RS, Golinko RJ. Noninvasive assessment of pulmonary hypertension and pulmonary vascular reactivity in congenital heart disease: pulsed Doppler application. J Cardiovasc Ultrason 1986;5:213–221. 16. Bouthier JD, Safer ME, Benetos A, Simon A, Levenson JA, Hugues CM. Haemodynamic effects of vasodilating drugs on the common carotid and brachial circulations in patients with essential hypertension. Br J Pharmacol 1986;21: 137–142. 17. Simon AC, Levenson AJ, Bouthier JL, Safer ME. Captopril-induced changes in large arteries in essential hypertension. Am J Med 1984;75:71–75. 18. Safer ME, Laurent S, Bouthier JL, London GM. Comparative effects of captopril and isosorbide dinitrate on the arterial wall of hypertensive human brachial arteries. J Cardiovasc Pharmacol 1986;8:1257–1261. 19. Richer C, Thuillez C, Giudicelli JF. Perindopril, converting enzyme blockade, and peripheral arterial hemodynamics in the healthy volunteer. J Cardiovasc Pharmacol 1987;9:94–102. 20. Gray SD. Effect of angiotensin II on neonatal lamb carotid arteries. Experientia 1976;32:350–351.
Effect of Aerobic Exercise Training on Plasma Levels of Tumor Necrosis Factor Alpha in Patients With Heart Failure Alf Inge Larsen,
MD,
Pa˚ l Aukrust, MD, PhD, Torbjørn Aarsland, Kenneth Dickstein, MD, PhD
xercise training has been shown to have beneficial effects on exercise performance and peripheral E pathology, with improvement in the neurohumoral profile in stable patients with congestive heart failure (CHF).1 However, the mechanisms by which exercise training improve cardiovascular function have not been fully clarified. Whether training may influence cytokine levels in such patients is unknown. In the present study we therefore evaluated the effect of a 3-month exercise training program on immunlogic mediators in patients with CHF by examining plasma cytokine levels. We also studied the relation of these changes to improvement in functional status. Recently, immunologic and inflammatory processes have been suggested to play a pathogenic role in CHF. Thus, elevated plasma levels and enhanced myocardial expression have been reported for several proinflammatory cytokines, such as tumor necrosis factor (TNF)-␣ and interleukin 6 in patients with CHF.2– 4 •••
During a period from 1994 to 1996, male outpatients with symptomatic CHF were screened. Left ventricular ejection fraction was determined by radionuclide ventriculography; functional capacity was asFrom the Cardiology Division, Central Hospital in Rogaland, Stavanger; Section of Clinical Immunology and Infectious Disease, Rikshospitalet, Oslo; Research Institute for Internal Medicine, Medical Department, Rikshospitalet, Oslo; and Hjertelaget Research Foundation, Stavanger, Norway. Dr. Larsen’s address is: Cardiology Division, Central Hospital in Rogaland, PO Box 8100 Postterminalen, N-4068 Stavanger, Norway. E-mail: [email protected]. Manuscript received April 4, 2001; revised manuscript received and accepted May 14, 2001. ©2001 by Excerpta Medica, Inc. All rights reserved. The American Journal of Cardiology Vol. 88 October 1, 2001
RN,
and
sessed by the 6-minute walk test and by the cycle ergometer exercise test with peak VO2 determination. Only patients with exercise intolerance, confirmed by a 6-minute walk test ⬍550 m and a peak ergometer cycle exercise test with a peak VO2 consumption ⬍20 ml/kg/min, were eligible. Patients with unstable angina pectoris, serious rhythm disturbance, significant valvular stenosis, symptomatic peripheral vascular disease, obstructive airways disease, or other serious concurrent illness that would reduce exercise capacity (e.g., malignancy and autoimmune disorders) were excluded. Twenty-eight men (mean age 67 ⫾ 8 years) with stable, ischemic CHF for at least 3 months, in New York Heart Association class II to III (mean ejection fraction 32 ⫾ 5%), and on a stable regimen of medical therapy were recruited. The dosages of medicine were kept constant during the training period, and there were no episodes of myocardial infarction and acute coronary syndromes, and there was no need for revascularization during this period. No patient was pacemaker dependent, but 2 patients did have backup VVI pacemakers before entry into the study. The patients were on stable, conventional medical therapy including diuretics (n ⫽ 24), angiotensin-converting enzyme inhibitors or angiotensin II antagonists (n ⫽ 25), and digitalis (n ⫽ 19). No patient was treated with  blockers. There were no clinical signs of infection at the time of the blood withdrawal. To compare cytokine levels, 16 healthy male blood donors were included as a control group (mean age 62 ⫾ 5 years). The protocol was approved by the regional ethical committee, and written informed consent was ob0002-9149/01/$–see front matter PII S0002-9149(01)01859-8
805
TABLE 1 Cytokine Levels in Plasma Before and After Exercise Training in 28 Patients With CHF*
Controls Baseline patients with CHF After 12 wks
TNF-␣ (pg/ml)
IL-6 (pg/ml)
Il-8 (pg/ml)
7.3 ⫾ 3 28.7 ⫾ 18.5†
1.1 ⫾ 0.8 4.6 ⫾ 3.9†
Not detectable 12.7 ⫾ 9.2†
25.1 ⫾ 14.4‡
4.8 ⫾ 5.1
11.2 ⫾ 4.7
*Baseline levels are compared with plasma levels in 16 healthy subjects. † p ⬍0.001 versus controls; ‡p ⫽ 0.013 versus before training. IL ⫽ interleukin.
TABLE 2 TNF-␣ Levels (pg/ml) in Survivors (n ⫽ 16) and Nonsurvivors (n ⫽ 12) Before and After Exercise Training*
Pretraining Post-training Difference After versus before
Survivors
Nonsurvivors
32.3 ⫾ 23.4 24.7 ⫾ 17.5 4.9 ⫾ 7.7 p ⫽ 0.023
24.0 ⫾ 9.4 22.1 ⫾ 6.4 1.9 ⫾ 6.3 NS
*The patient group was followed for 4 years after exercise training.
tained from all patients. This study was an open, unblinded trial designed for evaluating the effect of a 3-month exercise training program. The design, training protocol, and exercise testing protocols have previously been reported.5 Briefly, patients participated in exercise training groups 3 days/week in the rehabilitation center with an instructor specialized in cardiac rehabilitation. The group-training model consisted of 10 minutes of warmup, 25 minutes of endurance training, and 10 minutes of cooling down and stretching. The endurance training was based on callisthenics: low- impact aerobic walking and jogging using the large muscle groups in both the upper and lower extremities at approximately 80% of maximum capacity. The exercises were repeated at least 3 times a week. After 2 weeks of physical training in groups with the instructor at the cardiac rehabilitation center, patients were encouraged to exercise at home on a cycle ergometer for 30 minutes, 3 days/week, with a target heart rate of 80% of the peak in addition to the group training. Patients were evaluated on an upright, electrically braked ergometer bicycle (model KEM III, Mijnhardt, S.V. Bunnik, The Netherlands) using a 15-W/min ramp protocol. Patients were instructed to exercise maximally until symptomatic end points. Gas exchange data were collected continuously with an automated breath-by-breath system (System 2001, Medical Graphics Corporation, St. Paul, Minnesota). Before the maximal exercise test, an arterial cannula (Viggo Spectramed, Helsingborg, Sweden) was placed in the radial artery and fixed to the arm, with a continuous flush device (Abbott intraflo II, Chicago, Illinois, 30 ml/hour) with heparinized saline solution connected. Submaximal exercise test (6-minute walk test). The test was performed according to conventional criteria, and all tests were monitored by the same 806 THE AMERICAN JOURNAL OF CARDIOLOGY姞
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investigator to ensure uniform instruction in a quiet exercise facility.6 Patients were instructed to walk on a Star Track 3028 treadmill (Unisen, Inc, Tustin, California) at an initial speed of 1.0 km/hour and an angle of 0%. The speed and angle was increased according to 1 of 2 alternative protocols based on the patients estimated exercise capacity until a stable heart rate equal to 85% of the peak heart rate, as assessed by the baseline bicycle test, was reached. Patients were then instructed to continue at a constant rate and angle until symptomatic end points or until a total test time of 30 minutes was reached. The 12-week test used an identical protocol to ensure matched work intensities at baseline and after completion of the training. At baseline and at the end of the study, blood was collected from the arterial cannula into pyrogen-free vacuum blood-collection ethylenediaminetetraacetic acid tubes (Becton Dickinson, San Jose, California) after 5 minutes at supine rest before any exercise. The tubes were immediately immersed in melting ice, centrifuged within 15 minutes at 1,000 g and 4°C for 10 minutes, and stored at ⫺80°C. Plasma levels of TNF-␣ were measured by enzyme immunoassays (BioSource Europe, Nivelles, Belgium) as described.7 Plasma levels of interleukin 8 and interleukin 6 were measured by enzyme immunoassays obtained from R&D Systems (Minneapolis, Minnesota). The intraand interassay coefficient of variation was ⬍10% for all assays. All data were entered into a dBase version 5 database and prepared for analysis using SYSTAT version 5 (Evanston, Illinois) and SPSS version 9.0 (SPSS Inc, Chicago, Illinois) software packages. To evaluate the training effect in this open, unblinded trial, we used the paired t test. The values are reported as mean ⫾ 1 SD. The t test was used to calculate a p value for the comparisons of means. We used the Pearsons bivariate correlation test for evaluating the relation between change in cytokine levels and change in exercise performance. The value of significance was set at p ⬍0.05. All patients completed the study, and there were no serious adverse events or requirement for therapy adjustment during the training period. The results of the training program on exercise performance have previously been reported.5 Significant improvement was seen in exercise capacity during the 6-minute walk test (from 511 ⫾ 68 to 550 ⫾ 55 m, 8.1% increase, p ⬍0.001), in maximal workload during the cycle ergometer test (from 27.2 ⫾ 11.36 to 36.4 ⫾ 13.7 kJ, 44.7% increase, p ⬍0.001), and lactic acid production measured as area under the curve (16.7% decrease, p ⬍0.005). At baseline, both TNF-␣ and interleukin 6 and 8 levels were markedly raised in patients with CHF compared with age- and sex-matched healthy controls (Table 1). After 12 weeks of exercise training, there was a significant decrease in TNF-␣ levels from 28.7 ⫾ 19.0 to 25.1 ⫾ 14.4 pg/ml (p ⫽ 0.013) (Table 1), and this decrease was seen in all but 8 patients. The mean reduction was 3.6 ⫾ 7.2 pg/ml. The median OCTOBER 1, 2001
FIGURE 1. Correlation between changes in plasma levels TNF-␣ and changes in peak VO2 during exercise training in survivors (n ⴝ 14).
the median TNF-␣ reduction, we found 5 nonsurvivors in the group above the median and 7 nonsurvivors in the group of patients below the median. However, when dividing the patients by the mean reduction of 3.6 pg/ml, 4 of 12 patients (33%) above the mean died during the 4-year follow-up. In the other group with the smallest reduction of TNF-␣, there were 8 nonsurvivors after 4 years of follow up. Moreover, among survivors, we found a significant correlation between the increase in peak VO2, which was significant in survivors, and the reduction in TNF-␣ levels (r ⫽ ⫺0.643, p ⫽ 0.013, n ⫽ 14) (Figure 1). Two patients were excluded from this analysis of correlation because of the inability to increase heart rate during training. For the whole group, there was a significant correlation between the decrease in TNF-␣ and the increase in distance walked in the 6-minute walk test (r ⫽ ⫺0.427, p ⫽ 0.023) (Figure 2, Table 3). •••
Moderate endurance activity in active, healthy persons has previously been reported not to influence circulating cytokine levels.8,9 In contrast, overtraining and short-term extreme physical activity have been associated with enhanced levels of proinflammatory cytokines (e.g., interleukin 6)10,11 However, the present study is the first to report a downregulation of TNF-␣ levels after a moderate physical training program in patients with CHF, a population with enhanced immune activation at baseline. The mechanisms for such a reduction in TNF-␣ levels are unclear, but may involve a decrease in exercise-induced hypoxia. Hypoxia is a potent stimulus of several proinflammatory cytokines such as TNF-␣.12 Thus, the FIGURE 2. Correlation between changes in 6-minute walk test and in plasma levsignificant correlation between the inels of TNF-␣ during 12 weeks of exercise training in 28 patients with CHF. crease in peak VO2 and the decrease in TNF-␣ found in the present study may reduction was ⫺1 pg/ml. In contrast, exercise training suggest that reduced hypoxia during moderate daily did not induce any significant changes in interleukin 6 activity may be involved in the reduction of TNF-␣ or 8 levels (Table 1). levels after physical training in patients with CHF. During a follow-up period of 4 years, 12 patients However, there was no reduction in interleukin 8 died of progressive heart failure. When dividing the levels after exercise training, another cytokine that study group into survivors and nonsurvivors, we may be induced by hypoxia,13 suggesting that other found that although there there was no significant mechanisms may be involved in the reduction of reduction in TNF-␣ levels after exercise training in TNF-␣ levels during such activity (e.g., altered neunonsurvivors, TNF-␣ decreased from 32.3 ⫾ 23.5 to rohormonal status). Preliminary results suggest that inhibition of 24.7 ⫾ 17.5 pg/ml (p ⫽ 0.023) in survivors (n ⫽ 16) (Table 2). In contrast, there was no significant reduc- TNF-␣ activity may also have beneficial effects in tion in serum levels of interleukin 6 or 8 in either patients with CHF.14 Thus, it is possible that even the survivors or nonsurvivors. When dividing patients by modest decrease in TNF-␣ levels after exercise trainBRIEF REPORTS
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TABLE 3 Correlations Between Cytokines and Clinical Parameters TNF-␣ Before Training TNF-␣ before training TNF-␣ after training IL 6 before training IL 6 after training IL 8 before training IL 8 after training VO2 baseline VO2 after training Delta VO2 Workload baseline Workload after training Delta workload 6-min walk baseline 6-min walk after training Delta 6-min walk test
TNF-␣ After Training
0.148 0.258 0.286 0.273 ⫺0.139 0.076 0.230 ⫺0.199 ⫺0.259 0.298 ⫺0.194 ⫺0.156
⫺0.794† ⫺0.566* ⫺0.317* ⫺0.131 ⫺0.490† ⫺0.359 0.264 ⫺0.007 ⫺0.318 0.033 ⫺0.135 ⫺0.199 0.113 ⫺0.201
0.105
⫺0.427*
0.951† 0.951† 0.228 0.240 0.395* 0.336 ⫺0.202 0.059 0.290 ⫺0.159 0.109 0.295 ⫺0.186 ⫺0.039 0.238
TNF-␣ Difference
*p ⫽ 0.05 (2-tailed). † p ⫽ 0.01 (2-tailed). R values obtained by Pearson’s correlation test. Abbreviation as in Table 1.
ing observed in the present study is associated with clinical improvement. After exercise training, we found a significant correlation between the decrease in TNF-␣ and the increase in peak VO2 in survivors, and with the increase in the 6-minute walk test for the entire group. Enhanced activity of the TNF systems appears to have prognostic significance.15 In the present study a decrease in TNF-␣ during exercise training was associated with improved long-time survival, suggesting that the decrease in TNF-␣ levels may be of clinical relevance. We recently reported that either angiotensin-converting enzyme inhibitors or  blockers may downregulate elevated levels of cytokines in patients with CHF.16,17 Therefore, exercise training may be beneficial in patients with CHF on optimal medical therapy, at least partly by downregulating TNF-␣ levels. In summary, the present study demonstrates that aerobic exercise training reduces pathologically increased TNF ␣ levels in patients with CHF. This modest reduction was associated with improved exercise performance.
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Acknowledgment: The expert assistance of Marit Kristiansen, PT, and Anne Haugland, PT, in designing and performing the training program is highly appreciated.
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