Interleukin-6 and tumor necrosis factor-alpha levels increase in response to maximal exercise in patients with chronic heart failure

Exercise Counters the Age-Related Accumulation of Senescent Cells

We propose the beneficial effects of exercise are in part mediated through the prevention and elimination of senescent cells. Exercise counters multiple forms of age-related molecular damage that initiate the senescence program and activates immune cells responsible for senescent cell clearance. Preclinical and clinical evidence for exercise as a senescence-targeting therapy and areas needing further investigation are discussed.

High Intensity Interval Training Leads to Similar Inflammatory Activation as Seen With Traditional Training in Chronic Heart Failure

BACKGROUND

Inflammatory activation has been associated with the severity and progression of chronic heart failure (CHF). Although cardiac rehabilitation is an important therapy, acute bouts of exercise may lead to increases in pro-inflammatory cytokines with exercise intensity mediating these changes.

OBJECTIVE

To evaluate the acute inflammatory response in patients living with CHF during a randomized trial following Steady State (SS) or High Intensity Interval (HIIT) training.

METHODS

Patients living with CHF (n = 14) were stratified (for body mass and aerobic power) and randomized into SS and HIIT cycle exercise. The HIIT exercise training involved 2 min work:recovery phases at 90:40% heart rate reserve. The SS exercise training involved continuous exercise at 65% of heart rate reserve (matched total work). Acute inflammatory markers were evaluated (via ELISA) at baseline, immediately following the bout, and at 6, 24, and 48 h post-exercise.

RESULTS

There was limited differences in the changes in inflammatory biomarkers across time between the HIIT and SS groups. Both groups experienced a significant (p < 0.05) change in Interleukin-6 immediately post-exercise.

CONCLUSIONS

A single bout of HIIT or SS does not result in excessive inflammatory activation in CHF patients. Acute HIIT and SS result in similar changes in inflammatory markers. These findings have important implications for exercise training and rehabilitation programs in persons living with CHF.

Molecular Choreography of Acute Exercise

Acute physical activity leads to several changes in metabolic, cardiovascular, and immune pathways. Although studies have examined selected changes in these pathways, the system-wide molecular response to an acute bout of exercise has not been fully characterized. We performed longitudinal multi-omic profiling of plasma and peripheral blood mononuclear cells including metabolome, lipidome, immunome, proteome, and transcriptome from 36 well-characterized volunteers, before and after a controlled bout of symptom-limited exercise. Time-series analysis revealed thousands of molecular changes and an orchestrated choreography of biological processes involving energy metabolism, oxidative stress, inflammation, tissue repair, and growth factor response, as well as regulatory pathways. Most of these processes were dampened and some were reversed in insulin-resistant participants. Finally, we discovered biological pathways involved in cardiopulmonary exercise response and developed prediction models revealing potential resting blood-based biomarkers of peak oxygen consumption.

Circulatory factors associated with function and prognosis in patients with severe heart failure

Background

Multiple circulatory factors are increased in heart failure (HF). Many have been linked to cardiac and/or skeletal muscle tissue processes, which in turn might influence physical activity and/or capacity during HF. This study aimed to provide a better understanding of the mechanisms linking HF with the loss of peripheral function.

Methods and results

Physical capacity measured by maximum oxygen uptake, myocardial function (measured by echocardiography), physical activity (measured by accelerometry), and mortality data was collected for patients with severe symptomatic heart failure an ejection fraction < 35% (n = 66) and controls (n = 28). Plasma circulatory factors were quantified using a multiplex immunoassay. Multivariate (orthogonal projections to latent structures discriminant analysis) and univariate analyses identified many factors that differed significantly between HF and control subjects, mainly involving biological functions related to cell growth and cell adhesion, extracellular matrix organization, angiogenesis, and inflammation. Then, using principal component analysis, links between circulatory factors and physical capacity, daily physical activity, and myocardial function were identified. A subset of ten biomarkers differentially expressed in patients with HF vs controls covaried with physical capacity, daily physical activity, and myocardial function; eight of these also carried prognostic value. These included established plasma biomarkers of HF, such as NT-proBNP and ST2 along with recently identified factors such as GDF15, IGFBP7, and TfR, as well as a new factor, galectin-4.

Conclusions

These findings reinforce the importance of systemic circulatory factors linked to hemodynamic stress responses and inflammation in the pathogenesis and progress of HF disease. They also support established biomarkers for HF and suggest new plausible markers.

Graphic abstract

Electronic supplementary material

The online version of this article (10.1007/s00392-019-01554-3) contains supplementary material, which is available to authorized users.

Acute Inflammatory Responses to Exercise in Patients with Abdominal Aortic Aneurysm

PURPOSE

Inflammation and extracellular matrix degeneration contribute to abdominal aortic aneurysm (AAA) development. We aimed to assess the effect of exercise intensity on circulating biomarkers of inflammation and extracellular matrix degeneration in patients with AAA and healthy older adults.

METHODS

Twenty patients with AAA (74 ± 6 yr) and 20 healthy males (72 ± 5 yr) completed moderate-intensity cycling at 40% peak power output, higher-intensity intervals at 70% peak power output, and control (rest) on separate days. Circulating matrix metalloproteinase-9 (MMP-9), transforming growth factor beta 1, interleukin-6 (IL-6), IL-10, and tumor necrosis factor alpha (TNF-α) were analyzed at rest and 0 to 90 min postexercise.

RESULTS

Biomarkers at baseline were similar between groups. IL-6 responses to exercise were similar between groups, with a greater increase in ΔIL-6 after moderate-intensity compared with higher-intensity exercise (P < 0.001). Delta MMP-9 showed a 118-ng·mL (95% confidence interval = 23 to 214, P = 0.02) greater increase immediately after higher-intensity exercise compared with changes in control in both groups. Delta MMP-9 then decreased by 114 ng·mL (18 to 211, P = 0.02) 90 min after higher-intensity exercise compared with the changes in control. Delta TNF-α was not different between protocols in healthy adults. In patients with AAA, delta TNF-α showed a greater decrease after higher-intensity compared with moderate-intensity exercise (-6.1 pg·mL, -8.5 to -3.6, P < 0.001) and control (-4.9 pg·mL, -7.4 to -2.4, P < 0.001). IL-10 and transforming growth factor beta 1 did not change in either group.

CONCLUSIONS

These findings suggest that a bout of higher-intensity exercise elicits a greater anti-inflammatory response compared with moderate-intensity exercise, which may be further augmented in patients with AAA. Exercise-induced reductions in biomarkers associated with AAA progression may represent a protective effect of exercise in patients with AAA.

Cytokine Responses to Acute Exercise in Healthy Older Adults: The Effect of Cardiorespiratory Fitness

Markers of chronic inflammation increase with aging, and are associated with cardiovascular disease prevalence and mortality. Increases in fitness with exercise training have been associated with lower circulating concentrations of cytokines known to have pro-inflammatory actions (such as interleukin-6 [IL-6]) and higher circulating concentrations of anti-inflammatory cytokines (interleukin-10 [IL-10]). However, the effect of cardiorespiratory fitness on acute cytokine responses to a single bout of exercise in healthy older individuals is unknown. We compared the response of plasma cytokines IL-6, tumor necrosis factor-alpha (TNF-α) and IL-10 to a bout of moderate-intensity continuous and higher-intensity interval exercise between older individuals with higher and lower levels of cardiorespiratory fitness. Sixteen lower-fit (VO_2peak: 22.6±2.8 mL.kg⁻¹.min⁻¹) and fourteen higher-fit participants (VO_2peak: 37.4±5.9 mL.kg⁻¹.min⁻¹) completed three 24 min experimental protocols in a randomized order: (1) moderate-intensity continuous exercise (40% of peak power output [PPO]); (2) higher-intensity interval exercise (12 × 1 min intervals at 70% PPO separated by 1 min periods at 10% PPO); or (3) non-exercise control. Plasma cytokines were measured at rest, immediately after, and during 90 min of recovery following exercise or control. Plasma IL-6 concentrations at baseline were greater in the higher-fit compared to the lower-fit group (P = 0.02), with no difference in plasma IL-10 or TNF-α concentrations at baseline between groups. Plasma IL-6 and IL-10 concentrations in both groups increased immediately after all protocols (IL-6: P = 0.02, IL-10: P < 0.01). However, there was no difference in the IL-6 and IL-10 response between the exercise and non-exercise (control) protocols. After all protocols, no changes in plasma TNF-α concentrations were observed in either the higher- or lower-fit groups. In this study, basal concentrations of circulating IL-6 were elevated in older individuals with higher levels of cardiorespiratory fitness. However, changes in plasma cytokine concentrations after exercise were not different to changes after non-exercise control in both the lower- and higher-fit groups.

Molecular and histological effects of MR-guided pulsed focused ultrasound to the rat heart

BACKGROUND

Image-guided high intensity focused ultrasound has been used as an extracorporeal cardiac pacing tool and to enhance homing of stem cells to targeted tissues. However, molecular changes in the myocardium after sonication have not been widely investigated. Magnetic-resonance (MR)-guided pulsed focused ultrasound (pFUS) was targeted to the rat myocardium over a range of pressures and the microenvironmental and histological effects were evaluated over time.

METHODS

Eight-to-ten-week-old Sprague-Dawley rats received T2-weighted MR images to target pFUS to the left ventricular and septum without cardiac or respiratory gating. Rats were sonicated through the thoracic wall at peak negative pressures (PNP) from 1 to 8 MPa at a center frequency of 1 MHz, 10 ms pulse duration and 1 Hz pulse repetition frequency for 100 pulses per focal target. Following pFUS, myocardium was harvested over 24 h and subjected to imaging, proteomic, and histological measurements.

RESULTS

pFUS to the myocardium increased expression of cytokines, chemokines, and trophic factors characterized by an initial increase in tumor necrosis factor (TNF)-α followed by increases in pro- and anti-inflammatory factors that returned to baseline by 24 h. Immediately after pFUS, there was a transient (< 1 h) increase in N-terminal pro b-type natriuretic peptide (NT-proBNP) without elevation of other cardiac injury markers. A relationship between PNP and expression of TNF-α and NT-proBNP was observed with significant changes (p < 0.05 ANOVA) ≥ 4 MPa compared to untreated controls. Contrast-enhanced ex vivo T1-weighted MRI revealed vascular leakage in sonicated myocardium that was accompanied by the presence of albumin upon immunohistochemistry. Histology revealed infiltration of neutrophils and macrophages without morphological myofibril changes in sonicated tissue accompanied by pulmonary hemorrhage at PNP > 4 MPa.

CONCLUSIONS

MR-guided pFUS to myocardium induced transient proteomic and histological changes. The temporal proteomic changes in the myocardium indicate a short-lived sterile inflammatory response consistent with ischemia or contusion. Further study of myocardial function and strain is needed to determine if pFUS could be developed as an experimental model of cardiac injury and chest trauma.

Inflammation and oxidative stress in heart failure: effects of exercise intensity and duration

Although acute exercise is apparently pro-inflammatory and increases oxidative stress, it can promote the necessary stress stimulus to train chronic adaptations in patients with chronic heart failure (CHF). This study aimed to compare the effects of exercise intensity and duration on the inflammatory markers soluble tumor necrosis factor receptor (sTNFR1) and interleukin-6 (IL-6), and on oxidative stress [malondialdehyde (MDA) and antioxidant enzymes: catalase (CAT) and superoxide dismutase (SOD)] in individuals with CHF. Eighteen patients performed three exercise sessions: 30 min of moderate-intensity (M30) exercise, 30 min of low-intensity (L30) exercise, and 45 min of low-intensity (L45) exercise. Blood analysis was performed before exercise (baseline), immediately after each session (after), and 1 h after the end of each session (1h after). Thirty min of M30 exercise promoted a larger stressor stimulus, both pro-inflammatory and pro-oxidative, than that promoted by exercises L30 and L45. This was evidenced by increased sTNFR1 and MDA levels after exercise M30. In response to this stressor stimulus, 1 h after exercise, there was an increase in IL-6 and CAT levels, and a return of sTNFR1 to baseline levels. These findings suggest that compared with the duration of exercise, the exercise intensity was an important factor of physiologic adjustments.

Exercise promotes IL-6 release from legs in older men with minor response to unilateral immobilization

Physical inactivity is a major contributor to low-grade systemic inflammation. Most of the studies characterizing interleukin-6 (IL-6) and tumour necrosis factor-α (TNF-α) release from exercising legs have been done in young, healthy men, but studies on inactivity in older people are lacking. The impact of 14 days of one-leg immobilization (IM) on IL-6 and TNF-α release during exercise in comparison to the contralateral control (CON) leg was investigated. Fifteen healthy men (age 68.1 ± 1.1 year (mean ± SEM); BMI 27.0 ± 0.4 kg·m(2); VO2max 33.3 ± 1.6 ml·kg(‒1)·min(‒1)) performed 45 min of two-leg dynamic knee extensor exercise at 19.5 ± 0.9 W. Arterial and femoral venous blood samples from the CON and the IM legs were collected every 15 min during exercise, and thigh blood flow was measured with ultrasound Doppler. Arterial plasma IL-6 concentration increased with exercise (rest vs. 45 min, main effect p < .05). IL-6 release increased with exercise (rest vs. 30 min, main effect p < .05). Furthermore, IL-6 release was borderline (main effect, p = .085, effect size 0.28) higher in the IM leg compared to the CON leg (288 (95% CI: 213-373) vs. 220 (95% CI: 152-299) pg·min(‒1), respectively). There was no release of TNF-α in either leg and arterial concentrations remained unchanged during exercise (p > .05). In conclusion, exercise induces more pronounced IL-6 secretion in healthy older men. Two weeks of unilateral immobilization on the other hand had only a minor influence on IL-6 release. Neither immobilization nor exercise had an effect on TNF-α release across the working legs in older men.

The Impact of Exercising During Haemodialysis on Blood Pressure, Markers of Cardiac Injury and Systemic Inflammation--Preliminary Results of a Pilot Study

BACKGROUND/AIMS

Patients requiring haemodialysis have cardiovascular and immune dysfunction. Little is known about the acute effects of exercise during haemodialysis. Exercise has numerous health benefits but in other populations has a profound impact upon blood pressure, inflammation and immune function; therefore having the potential to exacerbate cardiovascular and immune dysfunction in this vulnerable population.

METHODS

Fifteen patients took part in a randomised-crossover study investigating the effect of a 30-min bout of exercise during haemodialysis compared to resting haemodialysis. We assessed blood pressure, plasma markers of cardiac injury and systemic inflammation and neutrophil degranulation.

RESULTS

Exercise increased blood pressure immediately post-exercise; however, 1 hour after exercise blood pressure was lower than resting levels (106±22 vs. 117±25 mm Hg). No differences in h-FABP, cTnI, myoglobin or CKMB were observed between trial arms. Exercise did not alter circulating concentrations of IL-6, TNF-α or IL-1ra nor clearly suppress neutrophil function.

CONCLUSIONS

This study demonstrates fluctuations in blood pressure during haemodialysis in response to exercise. However, since the fall in blood pressure occurred without evidence of cardiac injury, we regard it as a normal response to exercise superimposed onto the haemodynamic response to haemodialysis. Importantly, exercise did not exacerbate systemic inflammation or immune dysfunction; intradialytic exercise was well tolerated.

Forearm blood flow response to acute exercise in obese and non-obese males

Chronic exercise is thought to improve endothelium-dependent vasodilation; however, few studies have evaluated the effects of acute exercise on microvascular vasodilatory capacity (MVC). Moreover, no studies have compared MVC responses in obese and non-obese individuals following acute exercise. To evaluate MVC, utilizing forearm blood flow (FBF) and excess blood flow (EBF) before and up to 48 h after a single exercise bout to elicit peak oxygen consumption (VO2 peak) in obese and non-obese males. Twelve obese (37.0 ± 1.1 kg/m(2)) and 12 non-obese (21.9 ± 0.3 kg/m(2)) males volunteered to participate. FBF measures, before and during reactive hyperemia (RH), were obtained prior to (PRE-E), immediately after (POST-E), and at 1 (POST-1), 2 (POST-2), 24 (POST-24), and 48 (POST-48) hours after exercise. EBF, was calculated as the difference between FBF, before and during RH. Blood samples were obtained to evaluate the response of interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-α), which are potential modifiers of MVC. FBF before and during RH were significantly (P < 0.05) increased in both groups POST-E. The EBF magnitude of change from PRE-E was significantly (P < 0.05) elevated in non-obese when compared with obese males. Although not related to MVC, concentrations of IL-6 significantly decreased between POST-2 and POST-24 in both groups. An acute bout of exercise designed to elicit VO2 peak significantly increased forearm MVC in non-obese and obese males, although the magnitude of change in EBF from PRE-E to POST-E was greater in non-obese males.

A consideration of biomarkers to be used for evaluation of inflammation in human nutritional studies

To monitor inflammation in a meaningful way, the markers used must be valid: they must reflect the inflammatory process under study and they must be predictive of future health status. In 2009, the Nutrition and Immunity Task Force of the International Life Sciences Institute, European Branch, organized an expert group to attempt to identify robust and predictive markers, or patterns or clusters of markers, which can be used to assess inflammation in human nutrition studies in the general population. Inflammation is a normal process and there are a number of cells and mediators involved. These markers are involved in, or are produced as a result of, the inflammatory process irrespective of its trigger and its location and are common to all inflammatory situations. Currently, there is no consensus as to which markers of inflammation best represent low-grade inflammation or differentiate between acute and chronic inflammation or between the various phases of inflammatory responses. There are a number of modifying factors that affect the concentration of an inflammatory marker at a given time, including age, diet and body fatness, among others. Measuring the concentration of inflammatory markers in the bloodstream under basal conditions is probably less informative compared with data related to the concentration change in response to a challenge. A number of inflammatory challenges have been described. However, many of these challenges are poorly standardised. Patterns and clusters may be important as robust biomarkers of inflammation. Therefore, it is likely that a combination of multiple inflammatory markers and integrated readouts based upon kinetic analysis following defined challenges will be the most informative biomarker of inflammation.

Metabolic responses of acute phase protein, antioxidant and cytokine in Arabian Endurance horses

Changes in serum amyloid A (SAA), glutathione reductase (GR) and interleukin-6 (IL-6) could be responsible for the metabolic disorders and poor performance in Arabian horses during gruelling endurance events. Therefore, this study aims to evaluate the metabolic responses in relation to SAA, GR and IL-6 in Arabian horses during endurance events. After physical examination, the successfully completed (SC) (n=16) and eliminated-from-race (ER) (n=16) endurance horses were identified. The data obtained were analysed using ANOVA and pairwise correlations and the analysis were considered significant at P<0.05. There were significant differences between the SC and ER Arabian horses in haemoglobin (Hb), packed cell volume (PCV), creatine kinase, plasma protein, lactate and monocytes (P<0.0001), IL-6, GR (P<0.0007), SAA (P<0.0068), glucose (P<0.00342), aspartate transaminase (P<0.0049) concentrations. There were significant negative correlations between GR and plasma protein (r=-0.2830; P<0.0299) and GR and SAA (r=-0.2554; P<0.0489). There were significant positive correlations between IL-6 and Hb (r=0.2977; P<0.0220) and positive and not significant correlation between IL-6 and PCV (r=0.2449; P<0.0615). In conclusion, SAA, GR and IL-6 were significantly associated with metabolic crises in Arabian endurance horses. Therefore, SAA, GR and IL-6 could be used to evaluate performance and health status of endurance horses during training and endurance events.

Evaluation of the inflammatory response to two different intensities of exercise in individuals with heart failure

The aim of this study is to compare the response of interleukin-6 (IL-6) and soluble tumor necrosis factor alpha receptor 1 (s-TNFr1) to two submaximal intensities of exercise in individuals with heart failure (HF). Thirty-two HF individuals aged 45.53 ± 9.41 years, classes II and III of the New York Heart Association (NYHA) classification underwent two sessions of exercise at low and moderate intensities with blood analysis at baseline, exercise and after exercise. The differences were evaluated by Friedman test and factorial ANOVA. Alpha = 5% was considered. No difference in IL-6 was detected for low intensity. At moderate intensity, there was a significant increase after exercise. The s-TNFr1 increased in moderate-intensity exercise and went back to baseline levels after it. A session of moderate-intensity exercise is better than low-intensity exercise at promoting positive immediate inflammatory responses in individuals with HF class II and III of the NYHA.

Uric acid-lowering treatment with benzbromarone in patients with heart failure: a double-blind placebo-controlled crossover preliminary study

BACKGROUND

Hyperuricemia is common in chronic heart failure (CHF), and it is a strong independent marker of prognosis. Upregulated xanthine oxidase (XO) activity and impaired renal excretion have been shown to account for increased serum uric acid (UA) levels in CHF. Therapeutic interventions with allopurinol to reduce UA levels by XO inhibition have been shown to be beneficial. Discussions are ongoing whether UA itself is actively involved or it is a mere marker of upregulated XO activity within CHF pathophysiology. Therefore, the aim of this study was to test the effect of lowering UA by uricosuric treatment without XO inhibition on hemodynamic and metabolic characteristics of CHF. Impaired renal excretion of UA was taken into account.

METHODS AND RESULTS

Serum UA (SUA), urinary UA (uUA) excretion, and renal clearance test for UA (Cl(UA)) were measured in 82 patients with CHF. SUA was significantly increased compared with controls of similar age (control, 5.45+/-0.70 mg/dL; New York Heart Association I, 6.48+/-1.70 mg/dL; New York Heart Association II, 7.34+/-1.94 mg/dL; New York Heart Association III, 7.61+/-2.11 mg/dL; P<0.01). Patients with CHF showed lower uUA excretion and Cl(UA). On multivariate analysis, insulin, brain natriuretic peptide (P<0.01), and creatinine levels (P=0.05) showed independent correlation with SUA. The treatment effect of the uricosuric agent benzbromarone was tested in 14 patients with CHF with hyperuricemia in a double-blind, placebo-controlled, randomized crossover study design. Benzbromarone significantly decreased SUA (P<0.01). Brain natriuretic peptide, left ventricular ejection fraction, and dimensions in echocardiographic assessment did not change after benzbromarone therapy. In contrast, fasting insulin (placebo, 18.8+/-8.9 microU/mL; benzbromarone, 11.0+/-6.2 microU/mL; P<0.05), homeostasis model assessment of insulin resistance index (placebo, 5.4+/-2.6; benzbromarone, 3.0+/-1.7; P<0.05), and tumor necrosis factor-alpha (placebo, 2.59+/-0.63 pg/mL; benzbromarone, 2.14+/-0.51 pg/mL; P<0.05) improved after benzbromarone, and the changes in tumor necrosis factor-alpha levels were correlated with reduction of SUA (P<0.05).

CONCLUSIONS

These results show that UA lowering without XO inhibition may not have an effect on hemodynamic impairment in CHF pathophysiology. To the extent that these data are correct, this finding suggests that upregulated XO activity rather than UA itself is actively involved in hemodynamic impairment in CHF. Clinical Trial Registration- clinical trials.gov. Identifier: NCT00422318.

Usefulness of N-terminal pro-B-type natriuretic peptide increase with exercise for predicting cardiovascular mortality in patients with heart failure

N-terminal pro-B-type natriuretic peptide (NT-pro-BNP) level at rest is related to left ventricular (LV) function and cardiovascular mortality in patients with heart failure (HF). There are limited and controversial data regarding changes in NT-pro-BNP level during exercise in patients with HF. The aim of this study was to investigate the effects of exercise on NT-pro-BNP levels and the relation between increases in NT-pro-BNP and the LV ejection fraction and cardiovascular mortality in patients with HF. Seventy-five patients with HF (New York Heart Association classes I to III) and 20 healthy subjects were enrolled in the study. Echocardiographic examination was performed. The modified Bruce protocol was used for symptom-limited exercise testing. Levels of NT-pro-BNP were measured at rest and after peak exercise. The patients were followed up for 690 to 840 days for cardiovascular mortality. Exercise induced significant increases in NT-pro-BNP in patients and controls. Except for a relative increase in NT-pro-BNP during exercise (relative DeltaNT-pro-BNP), NT-pro-BNP concentrations at rest and during peak exercise and absolute increases in NT-pro-BNP during exercise (absolute DeltaNT-pro-BNP) were significantly higher in patients with HF (p <0.001). Absolute DeltaNT-pro-BNP was positively correlated with NT-pro-BNP at rest (p <0.001). The level of absolute DeltaNT-pro-BNP was the most important parameter in predicting a LV ejection fraction <30% (p <0.001). Absolute DeltaNT-pro-BNP and LV end-systolic volume were found to be independent predictors of mortality (p = 0.012 and p = 0.015, respectively). In conclusion, exercise induced increases in NT-pro-BNP in patients and healthy subjects. Absolute increase in NT-pro-BNP is a reliable parameter in predicting a low LV ejection fraction and may help in the identification of patients at high risk for mortality.

Relation of B-type natriuretic peptide levels before and after exercise and functional capacity in patients with idiopathic dilated cardiomyopathy

Although much is known about the value of B-type natriuretic peptide (BNP) at rest, the significance of the responsiveness of BNP during exercise in patients with chronic heart failure (HF) without coronary artery disease remains to be established. A role of BNP release during exercise in the functional disability of patients with chronic HF and idiopathic dilated cardiomyopathy (IDC) was hypothesized. One hundred five consecutive patients with an established diagnosis of HF and IDC who underwent symptom-limited cardiopulmonary exercise testing were studied. BNP was measured immediately before exercise and within 1 minute of the end of exercise. BNP at rest increased significantly at peak exercise (median from 66.5 (first, third quartiles 18, 168) to 72.0 pg/ml (26, 208), p <0.001), but BNP response was not uniform. BNP response increased in 63% of patients, did not change in 22%, and decreased in 15%. BNP at rest and BNP response showed an inverse correlation (p <0.001, r = -0.523). Aging and low left ventricular ejection fraction were independent predictors of higher BNP levels at rest, but lower BNP response. Beta-blocker therapy did not influence BNP response. BNP at rest correlated negatively with functional capacity (p <0.001, r = -0.516), whereas BNP response correlated positively (p = 0.002, r = 0.326). Patients with BNP release (vs patients without) had higher maximum oxygen consumption (19.2 +/- 5.1 vs 15.9 +/- 3.6, p <0.001), better functional capacity (59 +/- 13% vs 50 +/- 15%, p = 0.002), and lower minute ventilation/carbon dioxide production slope (33.6 +/- 4.8 vs 36.5 +/- 7.7, p = 0.026) independent of other clinical parameters. In conclusion, BNP release during exercise could be a determinant of functional capacity in patients with chronic HF and IDC.

Effect of orange peel and black tea extracts on markers of performance and cytokine markers of inflammation in horses

This study tested the hypothesis that orange peel (O) and decaffeinated black tea (T) extracts would alter markers of exercise performance as well as exercise-induced mRNA expression for the inflammatory cytokines IL-6, TNF-alpha and IFN-gamma. Nine healthy, unfit Standardbred mares (age: 10±4years, ∼450kg) were assigned to three treatment groups in a randomized crossover design where each horse was administered one of the following; placebo (O; 21 water), black tea extract in water (T; 21) or orange peel extract in water (W; 21), via a nasogastric tube. One hour later the horses completed an incremental graded exercise test (GXT) on a treadmill at a fixed 6% grade with measurements and blood samples obtained at rest, at the end of each 1min step of the GXT and at 2 and 5min post-GXT. An additional set of blood samples for Polymerase Chain Reaction (PCR) measurements of mRNA was obtained before exercise and at 5 and 30min and 1, 2, 4 and 24h post-GXT. The GXTs were conducted between 0700 and 1200h not less than 7days apart. There were no differences (P>0.05) in VO2max, respiratory exchange ratio, run time, velocity at VO2max, core body temperature, haematocrit, creatine kinase (CK), plasma lactate concentrations, HR, right ventricular pressure (RVP) or pulmonary artery pressure (PAP) across treatments. A major finding was that orange peel extract significantly reduced post-exercise VO2 recovery time (W = 112±7, O = 86±6, and T = 120±11s). There was a significant difference in plasma total protein concentration (TP) in the O runs compared with water and T. TNF-alpha mRNA expression was lower in the T runs compared with water and O trials. IFN-gamma mRNA expression levels appeared to be lower in both the T and O extract runs compared with the water trials. The mRNA expression of IL-6 was unaltered across treatment groups. These data suggest that orange peel and black tea extracts may modulate the cytokine responses to intense exercise. Orange peel extract reduced post-exercise recovery time and may potentially enhance the ability of horses to perform subsequent bouts of high-intensity exercise.

Natriuretic peptide response to dynamic exercise in patients with atrial fibrillation

BACKGROUND

In patients with atrial fibrillation (AF) information regarding exercise release of atrial natriuretic peptide (ANP) is sparse and data on plasma brain natriuretic peptide (BNP) response to exercise is lacking. The aim of this study was to investigate plasma ANP and BNP response to exercise in patients with permanent AF and to assess if the response was different from the response in healthy age- and sex-matched control subjects.

METHODS

Plasma venous concentrations of ANP and BNP were determined at rest, at peak exercise and 30 min from the end of exercise in 38 patients with permanent AF and in 43 age- and sex-matched healthy control subjects.

RESULTS

Plasma concentrations of ANP and BNP were significantly higher in AF patients compared with the healthy control group at rest, peak exercise and after 30 min of recovery (p<0.0001). ANP and BNP increased significantly during exercise in both patients with AF and in the healthy control subjects (p<0.05). The increase in plasma concentration of ANP and BNP during exercise was significantly higher in AF patients compared with healthy controls (p=0.0002 for ANP; p<0.0001 for BNP). In the recovery period plasma BNP decreased significantly (p<0.0001) where as the decrease in plasma ANP was insignificant (p=0.4).

CONCLUSIONS

Patients with permanent AF have elevated levels of ANP and BNP at rest and exhibit much higher exercise release compared to healthy control subjects. This enhanced secretion of potent vasodilating and natriuretic agents may represent an important compensatory mechanism to improve exercise capacity in patients with AF.

Cardiac endocrine function is an essential component of the homeostatic regulation network: physiological and clinical implications

The discovery of cardiac natriuretic hormones required a profound revision of the concept of heart function. The heart should no longer be considered only as a pump but rather as a multifunctional and interactive organ that is part of a complex network and active component of the integrated systems of the body. In this review, we first consider the cross-talk between endocrine and contractile function of the heart. Then, based on the existing literature, we propose the hypothesis that cardiac endocrine function is an essential component of the integrated systems of the body and thus plays a pivotal role in fluid, electrolyte, and hemodynamic homeostasis. We highlight those studies indicating how alterations in cardiac endocrine function can better explain the pathophysiology of cardiovascular diseases and, in particular of heart failure, in which several target organs develop a resistance to the biological action of cardiac natriuretic peptides. Finally, we emphasize the concept that a complete knowledge of the cardiac endocrine function and of its relation with other neurohormonal regulatory systems of the body is crucial to correctly interpret changes in circulating natriuretic hormones, especially the brain natriuretic peptide.

Clinical relevance of biological variation: the lesson of brain natriuretic peptide (BNP) and NT-proBNP assay

The clinical relevance of brain natriuretic peptide (BNP) and N-terminal (NT)-proBNP assays as a diagnostic tool and prognostic marker in patients with cardiovascular diseases has recently been confirmed. However, several studies demonstrated variation of intra-individual BNP concentrations of >30% (ranging from 30% to 50%) with reference change values at the 95% confidence interval (i.e., the estimated critical difference) ranging from 99% to 130% in healthy subjects and heart failure patients. According to this estimated confidence interval, only a great variation in plasma BNP levels should be considered significant in an individual patient (for example, a decrease of >50% or an increase of more than two-fold). Many recent clinical studies have demonstrated that BNP variations below this estimated critical difference could also have clinical relevance. Like the concentration of other neuro-hormones, levels of plasma BNP fluctuate widely and rapidly along with heart rhythm and blood pressure variations in response to physiological stimuli. However, biological variation of BNP should not be interpreted strictly as random fluctuation around a homeostatic set point, as assumed by the common model used in all studies on biological variation of BNP reported in the literature. These results cannot be directly transferred to clinical practice. While awaiting more accurate studies, we suggest that variations of plasma BNP three-fold greater than the analytical imprecision should be considered as potentially relevant from a physiological and clinical point of view.

Myocardial Ischemia Induces Interleukin-6 and Tissue Factor Production in Patients With Coronary Artery Disease

BACKGROUND

Interleukin-6 (IL-6) and macrophage colony stimulating factor plasma levels are elevated in acute coronary syndromes. IL-6 has an inherent negative inotropic action and, with tissue factor (TF), mediates the ischemia-reperfusion myocardial injury. We hypothesized that inducible ischemia leads to cytokine production, TF expression, and consequently persistent left ventricular dysfunction after dobutamine stress echocardiography (DSE) in coronary artery disease patients.

METHODS AND RESULTS

DSE was performed in 103 patients with angiographically documented coronary artery disease. Blood samples were obtained at rest, at peak stress, and 30 minutes after cessation of dobutamine infusion for measurement of macrophage colony stimulating factor, IL-6, and TF. New or worsening wall motion abnormalities at peak stress and their duration into recovery were noted. Median IL-6 and TF levels were increased at peak stress and at 30 minutes into recovery compared with rest (2.7 and 2.4 versus 2.1 pg/mL for IL-6, 310 and 385 versus 266 pg/mL for TF [P<0.01] in patients with an ischemic response; n=55). Compared with rest, a greater release of IL-6 at peak stress and recovery was observed in patients with increasing number of ischemic segments at peak DSE (2 versus 3 to 4 versus 5 to 6 versus 7 to 8 segments; P=0.03). The time to recovery of wall motion abnormalities was also associated with IL-6 levels at peak stress and recovery (r=0.51 and r=0.39, P<0.05). Macrophage colony stimulating factor levels remained unchanged throughout DSE.

CONCLUSIONS

Reversible ischemia induced during DSE increases IL-6 and TF plasma levels. IL-6 is related to the extent of left ventricular dysfunction at peak stress and to persistent LV dysfunction during recovery.

The Combination of Dietary Conjugated Linoleic Acid and Treadmill Exercise Lowers Gain in Body Fat Mass and Enhances Lean Body Mass in High Fat–Fed Male Balb/C Mice

Nearly half of the U.S. adult population is overweight or obese, which may be related to increased energy intake combined with lack of physical activity. Obesity increases the risk of several chronic diseases including diabetes, coronary heart disease, hypertension, and stroke. Conjugated linoleic acids (CLA) were shown to decrease fat and increase lean mass in several animal studies. However, the effects of CLA in combination with exercise (Ex) on body composition have not been studied in an animal model. We examined the effect of a low concentration of either safflower oil as control (0.5%) or mixed isomers of CLA (0.4%) along with treadmill exercise on body composition in male Balb/C mice fed a high-fat diet (20% corn oil) in a 2 x 2 factorial design. CLA consumption lowered change in fat mass (P < 0.001) confirming the results of other studies, and change in fat mass decreased further (P < 0.001) with CLA and exercise. Change in lean mass did not increase with exercise alone; it increased, although not significantly, with CLA alone and increased significantly (P < 0.05) due to the combination of CLA and exercise. This effect was accompanied by decreased serum leptin levels and lower leptin mRNA expression in peritoneal fat (P < 0.001). Serum insulin, glucose, tumor necrosis factor (TNF)-alpha, and interleukin-6 were lower in CLA-fed mice than in controls (P < 0.05), whereas serum TNF-alpha was increased by exercise (P < 0.05). Exercise increased oxygen consumption and energy expenditure when measured under resting conditions (P < 0.05). In summary, the combination of dietary CLA and exercise decreased fat mass and increased lean mass in mice fed a high-fat diet, and these effects may be related in part to decreased serum leptin and exercise-induced increases in oxygen consumption and energy expenditure.

Epinephrine stimulates IL-6 expression in skeletal muscle and C2C12 myoblasts: role of c-Jun NH2-terminal kinase and histone deacetylase activity

Although an individual's genetic makeup is a major determinant of muscle mass, other influences, such as hormones, cytokines, nutrition, and exercise can also modulate muscle size. IL-6 is an important inflammatory cytokine. Mice that overexpress IL-6 fail to thrive and/or have reduced skeletal muscle mass. The purpose of the present study was to determine whether the stress hormone epinephrine increases inflammatory cytokine expression in skeletal muscle and muscle cells. Infusion of epinephrine in vivo for 2 h increased IL-6 protein (15-fold) and mRNA (40-fold) in skeletal muscle but not in liver. Epinephrine had a similar effect in C2C12 muscle cells, where the hormone increased IL-6 protein and mRNA in a dose- and time-dependent manner. Epinephrine-stimulated IL-6 expression was attenuated by the alpha-adrenergic receptor antagonist phentolamine and completely blocked by either the beta1/2-adrenergic receptor antagonist propranalol or the beta2-antagonist ICI-118551. The transcriptional inhibitor DRB and the synthetic glucocorticoid dexamethasone also blocked epinephrine-induced IL-6. SP-600125 (a JNK inhibitor) and SB-202190 (a p38 MAP kinase inhibitor) completely blocked epinephrine-induced IL-6 synthesis. Endotoxin and epinephrine given together had a synergistic affect on IL-6 mRNA and protein expression. Trichostatin A (a histone deacetylase inhibitor) blocked both endotoxin- and epinephrine-induced IL-6 expression. These data suggest that epinephrine induces IL-6 synthesis in skeletal muscle in vivo and myocytes in vitro. Epinephrine utilizes predominantly the beta1/2-adrenergic receptors to stimulate IL-6 synthesis. Endotoxin and epinephrine synergize to increase IL-6 mRNA expression. Optimal IL-6 synthesis may require both stress kinase and histone deacetylase activity.

Neurohormonal Determinants of Peak Oxygen Uptake in Patients with Chronic Heart Failure

Chronic heart failure (CHF) is characterized by the activation of neurohormones and cytokines. This study determined whether peak oxygen uptake (VO2) can be predicted by the degree of neurohormonal and cytokine activations in CHF. Plasma norepinephrine. epinephrine, renin-angiotensin system activity, ANP, BNP, and serum interleukin-6 (IL-6) and tumor necrosis factor (TNF)-alpha were measured in 84 CHF patients (age, 59 +/- 1 years, LVEF, 36 +/- 1%) and 34 controls. Maximal cardiopulmonary exercise testing was performed. Peak VO2 (Controls vs CHF: 27.8 +/- 1.3 vs 18.2 +/- 0.5 mL/min/kg, P < 0.0001) was lower in CHF. Patients with CHF had increased plasma norepinephrine (211 +/- 11 vs 315 +/- 24 pg/mL), renin activity (1.2 +/- 0.2 vs 6.2 +/- 1.1 ng/mL/hr), ANP (22 +/- 3 vs 72 +/- 7 pg/mL), and BNP levels (18 +/- 3 vs 200 +/- 25 pg/mL) (all P < 0.01). Serum IL-6 (1.1 0.1 vs 2.4 +/- 0.3 pg/mL) and TNF-alpha (2.7 +/- 0.2 vs 4.0 +/- 0.3 pg/mL) levels were higher in CHF (both P < 0.001). Univariate analysis revealed that age (P < 0.001), cardiothoracic ratio (P < 0.001), norepinephrine (P < 0.0001), ANP (P < 0.001), BNP (P < 0.01), and log IL-6 (P < 0.05) were significantly related with peak VO2. Stepwise regression analysis indicated that plasma norepinephrine and ANP emerged as significant determinants of peak VO2, independent of patient age (overall R = 0.61, P < 0.0001). In summary, patients with CHF exhibited activation of neurohormones and proinflammatory cytokines. Among the elevated hormonal and cytokine markers, plasma norepinephrine and ANP levels were independent predictors of exercise capacity.