Effects of exercise training on insulin-like growth factor-I expression in the skeletal muscle of non-cachectic patients with chronic heart failure

Serum insulin-like growth factor-1 as a potential prognostic biomarker for heart failure with reduced ejection fraction: a meta-analysis

Background

Most studies have indicated that peripheral insulin-like growth levels factor-1 (IGF-1) is valuable in diagnosing heart failure, although the results have been inconsistent. To help solve the debate, we performed a meta-analysis to explore the relationship between IGF-1 and heart failure (HF).

Methods

We conducted an extensive search across various databases such as Embase, Cochrane Library, Pubmed, Medline, and Web of Science on May 30, 2023. From the extensive pool of studies, we selected 16 relevant articles, encompassing a total of 1,380 cases and 1,153 controls, to conduct a rigorous meta-analysis.

Results

The total results indicated that there is an association between lower IGF-1 level and HF. The random-effects model yielded a pooled standardized mean difference (SMD) of -0.598 (95% CI: -1.081 to -0.116, P = 0.015). Further subgroup analysis also showed that IGF-1 levels were associated with HF in the age difference ≥5 years subgroup and body mass index difference >1 subgroup. Additionally, significant association between IGF-1 levels and HF were detected in the "serum" samples and "Europe" subgroups. Importantly, we observed IGF-1 showed significant lower levels in patients with reduced ejection fraction (HFrEF) compared to the controls, not in patients with preserved ejection fraction (HFpEF). The Begg's and Egger's tests revealed no indication of publication bias.

Conclusions

Our meta-analysis has provided evidence suggesting a substantial correlation between reduced levels of IGF-1 and the occurrence of HF. Further prospective studies are necessary to ascertain the use of IGF-1 as a reliable biomarker for diagnosing HF, especially for HFrEF. But the diagnosis of HFpEF should be cautious.

Time-Dependent Changes in Muscle IGF1-IGFBP5-PAPP System after Sciatic Denervation

Denervation-induced muscle atrophy is a frequent cause of skeletal muscle diseases. However, the role of the most important muscle growth factor, insulin-like growth factor (IGF-1), in this process is poorly understood. IGF-1 activity is controlled by six IGF-1 binding proteins (IGFBPs). In skeletal muscle, IGFBP-5 seems to have an important role in atrophic processes. Furthermore, pappalysins (PAPP-A) modulate muscle growth by increasing IGF-1 bioavailability through IGFBP cleavage. We aimed to study the time-dependent changes in the IGF1-IGFBP5-PAPP system and its regulators in gastrocnemius muscle after sciatic denervation. Gastrocnemius atrophy and overexpression of IGF-1 was observed from day 3 post-denervation. The proteolytic factors measured were elevated from day 1 post-denervation onwards. Expression of both IGFBP-5 and pappalysins were increased on days 1 and 3. Subsequently, on days 7 to 14 pappalysins returned to control levels while IGFBP-5 remained elevated. The ratio IGFBP-5/PAPP-A was correlated with the main proteolytic markers. All data suggest that the initial increase of pappalysins could facilitate the IGF-1 action on muscle growth, whereas their subsequent decrease could lead to further muscle wasting.

Molecular mechanisms of post-burn muscle wasting and the therapeutic potential of physical exercise

After a severe burn injury, a systemic stress response activates metabolic and inflammatory derangements that, among other, leads to muscle mass loss (muscle wasting). These negative effects on skeletal muscle continue for several months or years and are aggravated by short-term and long-term disuse. The dynamic balance between muscle protein synthesis and muscle protein breakdown (proteolysis) is regulated by complex signalling pathways that leads to an overall negative protein balance in skeletal muscle after a burn injury. Research concerning these molecular mechanisms is still scarce and inconclusive, understanding of which, if any, molecular mechanisms contribute to muscle wasting is of fundamental importance in designing of therapeutic interventions for burn patients as well. This review not only summarizes our present knowledge of the molecular mechanisms that underpin muscle protein balance but also summarizes the effects of exercise on muscle wasting post-burn as promising strategy to counteract the detrimental effects on skeletal muscle. Future research focusing on the pathways causing post-burn muscle wasting and the different effects of exercise on them is needed to confirm this hypothesis and to lay the foundation of therapeutic strategies.

Effects of exercise-based cardiac rehabilitation delivery modes on exercise capacity and health-related quality of life in heart failure: a systematic review and network meta-analysis

Background

This review aimed to compare the relative effectiveness of different exercise-based cardiac rehabilitation (ExCR) delivery modes (centre-based, home-based, hybrid and technology-enabled ExCR) on key heart failure (HF) outcomes: exercise capacity, health-related quality of life (HRQoL), HF-related hospitalisation and HF-related mortality.

Methods and results

Randomised controlled trials (RCTs) published through 20 June 2021 were identified from six databases, and reference lists of included studies. Risk of bias and certainty of evidence were evaluated using the Cochrane tool and Grading of Recommendations Assessment, Development and Evaluation, respectively. Bayesian network meta-analysis was performed using R. Continuous and binary outcomes are reported as mean differences (MD) and ORs, respectively, with 95% credible intervals (95% CrI). One-hundred and thirty-nine RCTs (n=18 670) were included in the analysis. Network meta-analysis demonstrated improvements in VO₂peak following centre-based (MD (95% CrI)=3.10 (2.56 to 3.65) mL/kg/min), home-based (MD=2.69 (1.67 to 3.70) mL/kg/min) and technology-enabled ExCR (MD=1.76 (0.27 to 3.26) mL/kg/min). Similarly, 6 min walk distance was improved following hybrid (MD=84.78 (31.64 to 138.32) m), centre-based (MD=50.35 (30.15 to 70.56) m) and home-based ExCR (MD=36.77 (12.47 to 61.29) m). Incremental shuttle walk distance did not improve following any ExCR delivery modes. Minnesota living with HF questionnaire improved after centre-based (MD=−10.38 (−14.15 to –6.46)) and home-based ExCR (MD=−8.80 (−13.62 to –4.07)). Kansas City Cardiomyopathy Questionnaire was improved following home-based ExCR (MD=20.61 (4.61 to 36.47)), and Short Form Survey 36 mental component after centre-based ExCR (MD=3.64 (0.30 to 6.14)). HF-related hospitalisation and mortality risks reduced only after centre-based ExCR (OR=0.41 (0.17 to 0.76) and OR=0.42 (0.16 to 0.90), respectively). Mean age of study participants was only associated with changes in VO₂peak.

Conclusion

ExCR programmes have broader benefits for people with HF and since different delivery modes were comparably effective for improving exercise capacity and HRQoL, the selection of delivery modes should be tailored to individuals’ preferences.

Endocrine system dysfunction and chronic heart failure: a clinical perspective

Chronic heart failure (CHF) leads to an excess of urgent ambulatory visits, recurrent hospital admissions, morbidity, and mortality regardless of medical and non-medical management of the disease. This excess of risk may be attributable, at least in part, to comorbid conditions influencing the development and progression of CHF. In this perspective, the authors examined and described the most common endocrine disorders observed in patients with CHF, particularly in individuals with reduced ejection fraction, aiming to qualify the risks, quantify the epidemiological burden and discuss about the potential role of endocrine treatment. Thyroid dysfunction is commonly observed in patients with CHF, and sometimes it could be the consequence of certain medications (e.g., amiodarone). Male and female hypogonadism may also coexist in this clinical context, contributing to deteriorating the prognosis of these patients. Furthermore, growth hormone deficiency may affect the development of adult myocardium and predispose to CHF. Limited recommendation suggests to screen endocrine disorders in CHF patients, but it could be interesting to evaluate possible endocrine dysfunction in this setting, especially when a high suspicion coexists. Data referring to long-term safety and effectiveness of endocrine treatments in patients with CHF are limited, and their impact on several "hard" endpoints (such as hospital admission, all-cause, and cardiovascular mortality) are still poorly understood.

Respiratory and Peripheral Muscle Weakness and Body Composition Abnormalities in Non-Cystic Fibrosis Bronchiectasis Patients: Gender Differences

As demonstrated in COPD, bronchiectasis patients may experience respiratory and peripheral muscle dysfunction. We hypothesized that respiratory and peripheral (upper and lower limbs) muscle function and nutritional status may be more significantly altered in female than in males for identical age and disease severity. In mild-to-moderate bronchiectasis patients (n = 150, 114 females) and 37 controls (n = 37, 21 females), radiological extension, maximal inspiratory and expiratory pressures (MIP and MEP), sniff nasal inspiratory pressure (SNIP), hand grip and quadriceps muscle strengths, body composition, and blood analytical biomarkers were explored. Compared to the controls, in all bronchiectasis patients (males and females), BMI, fat-free mass index (FFMI), fat tissue, upper and lower limb muscle strength, and respiratory muscle strength significantly declined, and FFMI, fat tissue, and quadriceps muscle function were significantly lower in female than male patients. In patients with mild-to-moderate bronchiectasis, respiratory and peripheral muscle function is significantly impaired and only partly related to lung disease status. Quadriceps muscle strength was particularly weakened in the female patients and was negatively associated with their exercise tolerance. Muscle weakness should be therapeutically targeted in bronchiectasis patients. Body composition and peripheral muscle function determination should be part of the comprehensive clinical assessment of these patients.

Lean Mass Abnormalities in Heart Failure: The Role of Sarcopenia, Sarcopenic Obesity, and Cachexia

The role of body composition in patients with heart failure (HF) has been receiving much attention in the last few years. Particularly, reduced lean mass (LM), the best surrogate for skeletal muscle mass, is independently associated with abnormal cardiorespiratory fitness (CRF) and muscle strength, ultimately leading to reduced quality of life and worse prognosis. While in the past, reduced CRF in patients with HF was thought to result exclusively from cardiac dysfunction leading to reduced cardiac output at peak exercise, current evidence supports the concept that abnormalities in LM may also play a critical role. Abnormalities in the LM body composition compartment are associated with the development of sarcopenia, sarcopenic obesity, and cachexia. Such conditions have been implicated in the pathophysiology and progression of HF. However, identification of such conditions remains challenging, as universal definitions for sarcopenia, sarcopenic obesity, and cachexia are lacking. In this review article, we describe the most common body composition abnormalities related to the LM compartment, including skeletal and respiratory muscle mass abnormalities, and the consequences of such anomalies on CRF and muscle strength in patients with HF. Finally, we discuss the potential nonpharmacologic therapeutic strategies such as exercise training (ie, aerobic exercise and resistance exercise) and dietary interventions (ie, dietary supplementation and dietary patterns) that have been implemented to target body composition, with a focus on HF.

Effects of different types of exercise on skeletal muscle atrophy, antioxidant capacity and growth factors expression following myocardial infarction

AIMS

Myocardial infarction (MI) is accompanied with skeletal muscle abnormalities. The aims are to explore an optimal exercise mode to improve cardiac function and prevent skeletal muscle atrophy, and detect the possible mechanisms of exercise-induced inhibition of muscle atrophy.

MAIN METHODS

Rats were subjected to four weeks of different types of exercise after MI surgery (resistance training, RT; moderated-intensity continuous aerobic exercise, MCE and high-intensity intermittent aerobic exercise, HIA). Cardiac function, histological changes of heart and skeletal muscle, oxidative stress, antioxidant capacity and the expression of muscle atrophy-related factors were detected in skeletal muscle.

KEY FINDINGS

The three types of exercise improved heart function, reduced cardiac fibrosis and increased muscle weight and cross-section area (CSA) of muscle fibers in different degrees. The survival rates of MI rats intervened by RT and MCE were higher than HIA. Exercise down-regulated the mRNA levels of murf1 and atrogin-1, decreased reactive oxygen species level, increased antioxidant capacity, regulated the expression of insulin-like growth factor 1 (IGF1), mechano growth factor (MGF), Neuregulin1 (NRG1) and Myostatin (MSTN), and activated Akt and Erk1/2 signalings in soleus muscle. Furthermore, CSA of muscle fibers and the expression of IGF1, MGF, NRG1 in skeletal muscle had correlations with cardiac function.

SIGNIFICANCE

RT and MCE are the first two choices for the early exercise rehabilitation following MI. All types of exercise can effectively inhibit skeletal muscle atrophy through increasing the antioxidant capacity, reducing oxidative stress and protein degradation, and regulating the growth factors expression in skeletal muscle.

Effects of exercise training on anabolic and catabolic markers in patients with chronic heart failure: a systematic review

Decreased anabolism because of alterations in the insulin-like growth factor 1 (IGF-1)/growth hormone (GH) axis and increased catabolism induced by proinflammatory cytokines like tumor necrosis factor α (TNF-α) and interleukin 6 (IL-6) have been reported to contribute to muscle wasting in chronic heart failure (CHF). However, it is unclear whether exercise training could modulate anabolic and catabolic markers in CHF patients. The purpose of this study was to investigate the effects of exercise intervention on anabolic and catabolic markers for patients with CHF. Literatures were systematically searched in electronic databases and relevant references. Only published randomized controlled trials (RCTs) focusing on exercise training for CHF were eligible for inclusion. Outcome measurements included serum level and muscle biopsy of TNF-α, IL-6, GH, and IGF-I. Of the six included studies, four showed no significant difference between exercise group and control group in the serum levels of TNF-α, IL-6, GH, and IGF-I. However, two studies showed significant reduction in TNF-α and IL-6 and increase in IGF-I by local skeletal muscle biopsy. We conclude that the decreases in catabolic markers and increases in anabolic after exercise training were evident only by local skeletal muscle biopsy. More RCTs on dose-response relation of exercise programs are needed to further optimize anabolic and anti-inflammatory benefits of exercise training in patients with CHF.

A Systematic Review of Exercise Systematic Reviews in the Cancer Literature (2005-2017)

BACKGROUND

Evidence supports the benefits of exercise for patients with cancer; however, specific guidance for clinical decision making regarding exercise timing, frequency, duration, and intensity is lacking. Efforts are needed to optimize clinical recommendations for exercise in the cancer population.

OBJECTIVES

To aggregate information regarding the benefit of exercise through a systematic review of existing systematic reviews in the cancer exercise literature.

DATA SOURCES

PubMed, CINAHL Plus, Scopus, Web of Science, and EMBASE.

STUDY ELIGIBILITY CRITERIA

Systematic reviews and meta-analyses of the impact of movement-based exercise on the adult cancer population.

METHODS

Two author teams reviewed 302 abstracts for inclusion with 93 selected for full-text review. A total of 53 studies were analyzed. A Measurement Tool to Assess Systematic Reviews (AMSTAR) was used as a quality measure of the reviews. Information was extracted using the PICO format (ie, participants, intervention, comparison, outcomes). Descriptive findings are reported.

RESULTS

Mean AMSTAR score = 7.66/11 (±2.04) suggests moderate quality of the systematic reviews. Exercise is beneficial before, during, and after cancer treatment, across all cancer types, and for a variety of cancer-related impairments. Moderate-to-vigorous exercise is the best level of exercise intensity to improve physical function and mitigate cancer-related impairments. Therapeutic exercises are beneficial to manage treatment side effects, may enhance tolerance to cancer treatments, and improve functional outcomes. Supervised exercise yielded superior benefits versus unsupervised. Serious adverse events were not common.

LIMITATIONS

Movement-based exercise intervention outcomes are reported. No analysis of pooled effects was calculated across reviews due to significant heterogeneity within the systematic reviews. Findings do not consider exercise in advanced cancers or pediatric populations.

CONCLUSIONS

Exercise promotes significant improvements in clinical, functional, and in some populations, survival outcomes and can be recommended regardless of the type of cancer. Although generally safe, patients should be screened and appropriate precautions taken. Efforts to strengthen uniformity in clinical trial reporting, develop clinical practice guidelines, and integrate exercise and rehabilitation services into the cancer delivery system are needed.

Low salinity affects cellularity, DNA methylation, and mRNA expression of igf1 in the liver of half smooth tongue sole (Cynoglossus semilaevis)

Animal growth depends on feedback regulation of hormone levels and environmental conditions. Insulin-like growth factor-1 (Igf1) promotes cell growth and differentiation and represses apoptosis and is highly regulated by the environment. Moreover, animals modify physiological homeostasis under stressful conditions through epigenetics and genetic regulatory mechanisms. Therefore, a comprehensive understanding of the effects of salt on fish growth is needed. In this study, half smooth tongue sole (Cynoglossus semilaevis) were subjected to 15‰ salinity for 0, 7, and 60 days (D) to assess the effects of low salinity on liver cellularity and growth. The results show that low salinity changed liver morphology, suggesting an increase in energy expenditure to recover from the osmotic disruption. igf1 was upregulated in female fish under 15‰ salinity after 7D and may participate in molecular repair. igf1 was downregulated after 60D of salt stress, resulting in retarded growth. Methylation levels were opposite to those of gene expression, suggesting inhibited regulation. Furthermore, three exons in the igf1 gene had significantly different methylation levels in fish under salt stress. Notably, more putative transcription factor binding sites were located in CpG sites at higher methylation levels. igf1 is not a sex-related gene, as no difference in methylation level was detected between males and females in the control group. These results clarify liver damage and changes in DNA methylation and mRNA expression of igf1, providing insight into the adverse effects of low salt on growth of C. semilaevis and the epigenetics and regulatory mechanisms involved in stressful conditions.

Sarcopenia, cachexia, and muscle performance in heart failure: Review update 2016

Cachexia in the context of heart failure (HF) has been termed cardiac cachexia, and represents a progressive involuntary weight loss. Cachexia is mainly the result of an imbalance in the homeostasis of muscle protein synthesis and degradation due to a lower activity of protein synthesis pathways and an over-activation of protein degradation. In addition, muscle wasting leads to of impaired functional capacity, even after adjusting for clinical relevant variables in patients with HF. However, there is no sufficient therapeutic strategy in muscle wasting in HF patients and very few studies in animal models. Exercise training represents a promising intervention that can prevent or even reverse the process of muscle wasting, and worsening the muscle function and performance in HF with muscle wasting and cachexia. The pathological mechanisms and effective therapeutic approach of cardiac cachexia remain uncertain, because of the difficulty to establish animal cardiac cachexia models, thus novel animal models are warranted. Furthermore, the use of improved animal models will lead to a better understanding of the pathways that modulate muscle wasting and therapeutics of muscle wasting of cardiac cachexia.

Effects of High-Intensity Interval Exercise Training on Skeletal Myopathy of Chronic Heart Failure

BACKGROUND

It remains controversial which type of exercise elicits optimum adaptations on skeletal myopathy of heart failure (HF). Our aim was to evaluate the effect of high-intensity interval training (HIIT), with or without the addition of strength training, on skeletal muscle of HF patients.

METHODS AND RESULTS

Thirteen male HF patients (age 51 ± 13 years, body mass index 27 ± 4 kg/m²) participated in either an HIIT (AER) or an HIIT combined with strength training (COM) 3-month program. Biopsy samples were obtained from the vastus lateralis. Analyses were performed on muscle fiber type, cross-section area (CSA), capillary density, and mRNA expression of insulin-like growth factor (IGF) 1 isoforms (ie, IGF-1Ea, IGF-1Eb, IGF-1Ec), type-1 receptor (IGF-1R), and binding protein 3 (IGFBP-3). Increased expression of IGF-1Ea, IGF-1Eb, IGF-1Ec, and IGFBP-3 transcripts was found (1.7 ± 0.8, 1.5 ± 0.8, 2.0 ± 1.32.4 ± 1.4 fold changes, respectively; P < .05). Type I fibers increased by 21% (42 ± 10% to 51 ± 7%; P < .001) and capillary/fiber ratio increased by 24% (1.27 ± 0.22 to 1.57 ± 0.41; P = .005) in both groups as a whole. Fibers' mean CSA increased by 10% in total, but the increase in type I fibers' CSA was greater after AER than COM (15% vs 6%; P < .05). The increased CSA correlated with the increased expression of IGF-1Ea and IGF-1Εb.

CONCLUSIONS

HIIT reverses skeletal myopathy of HF patients, with the adaptive responses of the IGF-1 bioregulation system possibly contributing to these effects. AER program seemed to be superior to COM to induce muscle hypertrophy.

Experimental Evidences Supporting the Benefits of Exercise Training in Heart Failure

Heart Failure (HF), a common end point for many cardiovascular diseases, is a syndrome with a very poor prognosis. Although clinical trials in HF have achieved important outcomes in reducing mortality, little is known about functional mechanisms conditioning health improvement in HF patients. In parallel with clinical studies, basic science has been providing important discoveries to understand the mechanisms underlying the pathophysiology of HF, as well as to identify potential targets for the treatment of this syndrome. In spite of being the end-point of cardiovascular derangements caused by different etiologies, autonomic dysfunction, sympathetic hyperactivity, oxidative stress, inflammation and hormonal activation are common factors involved in the progression of this syndrome. Together these causal factors create a closed link between three important organs: brain, heart and the skeletal muscle. In the past few years, we and other groups have studied the beneficial effects of aerobic exercise training as a safe therapy to avoid the progression of HF. As summarized in this chapter, exercise training, a non-pharmacological tool without side effects, corrects most of the HF-induced neurohormonal and local dysfunctions within the brain, heart and skeletal muscles. These adaptive responses reverse oxidative stress, reduce inflammation, ameliorate neurohormonal control and improve both cardiovascular and skeletal muscle function, thus increasing the quality of life and reducing patients' morbimortality.

Effects of enhanced external counterpulsation on skeletal muscle gene expression in patients with severe heart failure

Enhanced external counterpulsation (EECP) is a non-invasive treatment in which leg cuff compressions increase diastolic aortic pressure and coronary perfusion. EECP is offered to patients with refractory angina pectoris and increases physical capacity. Benefits in heart failure patients have been noted, but EECP is still considered to be experimental and its effects must be confirmed. The mechanism of action is still unclear. The aim of this study was to evaluate the effect of EECP on skeletal muscle gene expression and physical performance in patients with severe heart failure. Patients (n = 9) in NYHA III-IV despite pharmacological therapy were subjected to 35 h of EECP during 7 weeks. Before and after, lateral vastus muscle biopsies were obtained, and functional capacity was evaluated with a 6-min walk test. Skeletal muscle gene expression was evaluated using Affymetrix Hugene 1.0 arrays. Maximum walking distance increased by 15%, which is in parity to that achieved after aerobic exercise training in similar patients. Skeletal muscle gene expression analysis using Ingenuity Pathway Analysis showed an increased expression of two networks of genes with FGF-2 and IGF-1 as central regulators. The increase in gene expression was quantitatively small and no overlap with gene expression profiles after exercise training could be detected despite adequate statistical power. EECP treatment leads to a robust improvement in walking distance in patients with severe heart failure and does induce a skeletal muscle transcriptional response, but this response is small and with no significant overlap with the transcriptional signature seen after exercise training.

The effect of endurance training on exercise capacity following cardiac resynchronization therapy in chronic heart failure patients: a pilot trial

BACKGROUND

Both endurance training (ET) and cardiac resynchronization therapy (CRT) improve quality of life (QOL) and exercise tolerance in patients with advanced chronic heart failure (CHF).

DESIGN

A randomized intervention trial to study the effect on exercise capacity of ET in addition to CRT in patients with CHF and dyssynchrony.

METHODS

Seventeen patients (eight men, aged 59+/-9 years) with CHF and dyssynchrony were randomized to CRT with (n=8) or without (n=9) ET and compared with two matched control CHF groups (standard care with ET: n=9, standard care only: n=10). At baseline and after 5 months, exercise tolerance, left ventricular (LV) remodelling, QOL and NT-pro brain natriuretic peptide (NT-proBNP) levels were assessed.

RESULTS

Peak oxygen consumption (VO2peak), maximal workload (Wattmax), circulatory power, LV ejection fraction, dyssynchrony and QOL improved in both CRT groups. However, the increase in VO2peak (+40% versus +16%, P=0.005), Wattmax (+43% versus +13%, P=0.0005), and circulatory power (+74% versus +32%, P=0.01), was significantly greater in the trained versus the untrained CRT patients. Comparison of the four patient groups confirmed the cumulative effects of CRT plus ET.

CONCLUSIONS

ET in resynchronized CHF patients is feasible and further enhances exercise tolerance. Patients with severe CHF should be prescribed an exercise training programme after implantation in order to maximize the expected benefit.

Training improves the oxidative phenotype of muscle during the transition from cardiac hypertrophy to heart failure without altering MyoD and myogenin

NEW FINDINGS

What is the central question of this study? We investigated the effects of physical training on phenotypic (fibre-type content) and myogenic features (MyoD and myogenin expression) in skeletal muscle during the transition from cardiac hypertrophy to heart failure. What is the main finding and its importance? We provide new insight into skeletal muscle adaptations by showing that physical training increases the type I fibre content during the transition from cardiac hypertrophy to heart failure, without altering MyoD and myogenin expression. These results have important clinical implications for patients with heart failure, because this population has reduced muscle oxidative capacity. The purpose of this study was to investigate the effects of physical training (PT) on phenotypic features (fibre-type content) and myogenic regulatory factors (MyoD and myogenin) in rat skeletal muscle during the transition from cardiac hypertrophy to heart failure. We used the model of ascending aortic stenosis (AS) to induce heart failure in male Wistar rats. Sham-operated animals were used as age-matched controls. At 18 weeks after surgery, rats with ventricular dysfunction were randomized into the following four groups: sham-operated, untrained (Sham-U; n = 8); sham-operated, trained (Sham-T; n = 6); aortic stenosis, untrained (AS-U; n = 6); and aortic stenosis, trained (AS-T; n = 8). The AS-T and Sham-T groups were submitted to a 10 week aerobic PT programme, while the AS-U and Sham-U groups remained untrained for the same period of time. After the PT programme, the animals were killed and the soleus muscles collected for phenotypic and molecular analyses. Physical training promoted type IIa-to-I fibre conversion in the trained groups (Sham-T and AS-T) compared with the untrained groups (Sham-U and AS-U). No significant (P > 0.05) differences were found in type I or IIa fibre content in the AS-U group compared with the Sham-U group. Additionally, there were no significant (P > 0.05) differences in the myogenic regulatory factors MyoD and myogenin (gene and protein) expression between the groups. Therefore, our results indicate that PT may be a suitable strategy to improve the oxidative phenotype in skeletal muscle during the transition from cardiac hypertrophy to heart failure, without altering MyoD and myogenin.

Akt/mTOR pathway contributes to skeletal muscle anti-atrophic effect of aerobic exercise training in heart failure mice

BACKGROUND

Exercise intolerance is one of the main clinical symptoms of heart failure (HF) and is associated with skeletal muscle wasting due to an imbalance between proteolysis and protein synthesis. In this study, we tested whether aerobic exercise training (AET) would counteract skeletal muscle atrophy by activating IGF-I/Akt/mTOR pathway in HF mice.

METHODS

Sympathetic hyperactivity induced HF mice were assigned into 8-week moderate intensity AET. Untrained wild type and HF mice were used as control. Soleus cross sectional area was evaluated by histochemistry and motor performance by rotarod. 26S proteasome activity was assessed by fluorimetric assay, and components of IGF-I/Akt/mTOR pathway or myostatin pathway by qRT-PCR or immunoblotting. A different subset of mice was used to evaluate the relative contribution of mTOR inhibition (rapamycin) or activation (leucine) on AET-induced changes in muscle mass regulation.

RESULTS

AET prevented exercise intolerance and impaired motor performance in HF mice. These effects were associated with attenuation of soleus atrophy. Rapamycin treatment precluded AET effects on soleus mass in HF mice suggesting the involvement of IGF signaling pathway in this response. In fact, AET increased IGF-I Ea and IGF-I Pan mRNA levels, while it reduced myostatin and Smad2 mRNA levels in HF mice. At protein levels, AET prevented reduced expression levels of IGF-I, pAkt (at basal state), as well as, p4E-BP1 and pP70(S6K) (leucine-stimulated state) in HF mice. Additionally, AET prevented 26S proteasome hyperactivity in HF mice.

CONCLUSIONS

Taken together, our data provide evidence for AET-induced activation of IGF-I/Akt/mTOR signaling pathway counteracting HF-induced muscle wasting.

Sarcopenic obesity and the pathogenesis of exercise intolerance in heart failure with preserved ejection fraction

Heart failure with preserved ejection fraction (HFpEF) is the most common form of heart failure (HF) in older adults. The primary chronic symptom in patients with HFpEF, even when well compensated, is severe exercise intolerance. Cardiac and peripheral functions contribute equally to exercise intolerance in HFpEF, though the latter has been the focus of fewer studies. Of note, multiple studies with exercise training have shown that exercise intolerance can improve significantly in the absence of improvements in exercise cardiac output, indicating a role of peripheral, noncardiac adaptations. In addition, clinical drug trials performed to date in HFpEF, all of which have focused on influencing cardiovascular function, have not been positive on primary clinical outcomes and most have not improved exercise capacity. Mounting evidence indicates that sarcopenic obesity, characterized by the coexistence of excess fat mass and decreased muscle mass, could contribute to the pathophysiology of exercise intolerance in older HFpEF patients and may provide avenues for novel treatments.

Aerobic Exercise and Pharmacological Therapies for Skeletal Myopathy in Heart Failure: Similarities and Differences

Skeletal myopathy has been identified as a major comorbidity of heart failure (HF) affecting up to 20% of ambulatory patients leading to shortness of breath, early fatigue, and exercise intolerance. Neurohumoral blockade, through the inhibition of renin angiotensin aldosterone system (RAS) and β-adrenergic receptor blockade (β-blockers), is a mandatory pharmacological therapy of HF since it reduces symptoms, mortality, and sudden death. However, the effect of these drugs on skeletal myopathy needs to be clarified, since exercise intolerance remains in HF patients optimized with β-blockers and inhibitors of RAS. Aerobic exercise training (AET) is efficient in counteracting skeletal myopathy and in improving functional capacity and quality of life. Indeed, AET has beneficial effects on failing heart itself despite being of less magnitude compared with neurohumoral blockade. In this way, AET should be implemented in the care standards, together with pharmacological therapies. Since both neurohumoral inhibition and AET have a direct and/or indirect impact on skeletal muscle, this review aims to provide an overview of the isolated effects of these therapeutic approaches in counteracting skeletal myopathy in HF. The similarities and dissimilarities of neurohumoral inhibition and AET therapies are also discussed to identify potential advantageous effects of these combined therapies for treating HF.

The Influence of Exercise on the Insulin-like Growth Factor Axis in Oncology: Physiological Basis, Current, and Future Perspectives

Exercise and physical activity have been shown to reduce the risk of many common cancers and strongly influence tumor biology. A cause-effect mechanism explaining this relationship is dependent on cellular pathways that can influence tumor growth and are exercise responsive. The insulin-like growth factor (IGF) axis is reported to promote the development and progression of carcinomas through cellular signaling in cancerous tissues. This review summarizes the physiologic basis of the role of the IGF axis in oncology and the influence of exercise on this process. We examined the effects of exercise prescription on the IGF axis in cancer survivors by evaluating the current scope of the literature. The current research demonstrates a remarkable heterogeneity and inconsistency in the responses of the IGF axis to exercise in breast, prostate, and colorectal cancer survivors. Finally, this review presents an in-depth exploration of the physiologic basis and mechanistic underpinnings of the seemingly disparate relationship between exercise and the IGF axis in oncology. Although there is currently insufficient evidence to categorize the effects of exercise prescription on the IGF axis in cancer survivors, the inconsistency of results suggests a multifaceted relationship, the complexities of which are considered in this review.

Skeletal muscle wasting in cachexia and sarcopenia: molecular pathophysiology and impact of exercise training

Skeletal muscle provides a fundamental basis for human function, enabling locomotion and respiration. Transmission of external stimuli to intracellular effector proteins via signalling pathways is a highly regulated and controlled process that determines muscle mass by balancing protein synthesis and protein degradation. An impaired balance between protein synthesis and breakdown leads to the development of specific myopathies. Sarcopenia and cachexia represent two distinct muscle wasting diseases characterized by inflammation and oxidative stress, where specific regulating molecules associated with wasting are either activated (e.g. members of the ubiquitin-proteasome system and myostatin) or repressed (e.g. insulin-like growth factor 1 and PGC-1α). At present, no therapeutic interventions are established to successfully treat muscle wasting in sarcopenia and cachexia. Exercise training, however, represents an intervention that can attenuate or even reverse the process of muscle wasting, by exerting anti-inflammatory and anti-oxidative effects that are able to attenuate signalling pathways associated with protein degradation and activate molecules associated with protein synthesis. This review will therefore discuss the molecular mechanisms associated with the pathology of muscle wasting in both sarcopenia and cachexia, as well as highlighting the intracellular effects of exercise training in attenuating the debilitating loss of muscle mass in these specific conditions.

Exercise training in chronic heart failure: improving skeletal muscle O2 transport and utilization

Chronic heart failure (CHF) impairs critical structural and functional components of the O2 transport pathway resulting in exercise intolerance and, consequently, reduced quality of life. In contrast, exercise training is capable of combating many of the CHF-induced impairments and enhancing the matching between skeletal muscle O2 delivery and utilization (Q̇mO2 and V̇mO2 , respectively). The Q̇mO2 /V̇mO2 ratio determines the microvascular O2 partial pressure (PmvO2 ), which represents the ultimate force driving blood-myocyte O2 flux (see Fig. 1). Improvements in perfusive and diffusive O2 conductances are essential to support faster rates of oxidative phosphorylation (reflected as faster V̇mO2 kinetics during transitions in metabolic demand) and reduce the reliance on anaerobic glycolysis and utilization of finite energy sources (thus lowering the magnitude of the O2 deficit) in trained CHF muscle. These adaptations contribute to attenuated muscle metabolic perturbations (e.g., changes in [PCr], [Cr], [ADP], and pH) and improved physical capacity (i.e., elevated critical power and maximal V̇mO2 ). Preservation of such plasticity in response to exercise training is crucial considering the dominant role of skeletal muscle dysfunction in the pathophysiology and increased morbidity/mortality of the CHF patient. This brief review focuses on the mechanistic bases for improved Q̇mO2 /V̇mO2 matching (and enhanced PmvO2 ) with exercise training in CHF with both preserved and reduced ejection fraction (HFpEF and HFrEF, respectively). Specifically, O2 convection within the skeletal muscle microcirculation, O2 diffusion from the red blood cell to the mitochondria, and muscle metabolic control are particularly susceptive to exercise training adaptations in CHF. Alternatives to traditional whole body endurance exercise training programs such as small muscle mass and inspiratory muscle training, pharmacological treatment (e.g., sildenafil and pentoxifylline), and dietary nitrate supplementation are also presented in light of their therapeutic potential. Adaptations within the skeletal muscle O2 transport and utilization system underlie improvements in physical capacity and quality of life in CHF and thus take center stage in the therapeutic management of these patients.

Hormonal Profile in Patients With Dilated Cardiomyopathy

BACKGROUND

There is increasing evidence that endocrine system may be dysfunctional in patients with heart failure.

OBJECTIVES

In the present study, we investigated hormonal abnormalities in heart failure and the effect of disturbed hormonal balance on prognostic outcomes of patients with systolic heart failure.

PATIENTS AND METHODS

Among patients followed in Heart Failure and Transplantation Clinic, 33 men with a diagnosis of idiopathic dilated cardiomyopathy receiving guidelines-directed medical therapies and with New York Heart Association Class II-III were enrolled. Serum concentrations of growth hormone (GH), insulin-like growth factor 1 (IGF-1), thyroid hormones, free testosterone, high-sensitive C-reactive protein (hs-CRP), and N-terminal pro-brain natriuretic peptide (NT Pro-BNP) were measured in all the patients. The physical performance of patients was assessed by six-minute walk test (6MWT). The patients were subsequently followed for a year and the data regarding their death, transplantation, or hospitalizations due to acute heart failure were recorded.

RESULTS

Except for testosterone level, the levels of GH, IGF-1, T3, and T4 concentrations in the patients were significantly lower than the normal values (P < 0.05). Among different hormone, only GH had correlation with NT Pro-BNP, hs-CRP, and 6MWT. There was no association between the occurrence of the combined events and different hormonal levels in multivariate analysis.

CONCLUSIONS

The hormonal levels were low in patients with idiopathic dilated cardiomyopathy. However, the prognostic significance of different hormonal deficiencies was not clear in our study populations who were receiving standard therapies for heart failure and had a relatively stable clinical condition.

Ventricular assist device implantation improves skeletal muscle function, oxidative capacity, and growth hormone/insulin-like growth factor-1 axis signaling in patients with advanced heart failure

BACKGROUND

Skeletal muscle dysfunction in patients with heart failure (HF) has been linked to impaired growth hormone (GH)/insulin-like growth factor (IGF)-1 signaling. We hypothesized that ventricular assist device (VAD) implantation reverses GH/IGF-1 axis dysfunction and improves muscle metabolism in HF.

METHODS

Blood and rectus abdominis muscle samples were collected during VAD implantation and explantation from patients with HF and controls. Clinical data were obtained from medical records, biomarkers measured by enzyme-linked immunosorbent assay (ELISA), and gene expression analyzed by reverse transcription and real-time polymerase chain reaction (RT-PCR). Grip strength was assessed by dynamometry. Oxidative capacity was measured using oleate oxidation rates. Muscle fiber type and size were assessed by histology.

RESULTS

Elevated GH (0.27 ± 0.27 versus 3.6 ± 7.7 ng/ml in HF; p = 0.0002) and lower IGF-1 and insulin-like growth factor binding protein (IGFBP)-3 were found in HF (IGF-1, 144 ± 41 versus 74 ± 45 ng/ml in HF, p < 0.05; and IGFBP-3, 3,880 ± 934 versus 1,935 ± 862 ng/ml in HF, p = 0.05). The GH/IGF-1 ratio, a marker of GH resistance, was elevated in HF (0.002 ± 0.002 versus 0.048 ± 0.1 pre-VAD; p < 0.0039). After VAD support, skeletal muscle expression of IGF-1 and IGFBP-3 increased (10-fold and 5-fold, respectively; p < 0.05) accompanied by enhanced oxidative gene expression (CD36, CPT1, and PGC1α) and increased oxidation rates (+1.37-fold; p < 0.05). Further, VAD implantation increased the oxidative muscle fiber proportion (38 versus 54 %, p = 0.031), fiber cross-sectional area (CSA) (1,005 ± 668 versus 1,240 ± 670 μm(2), p < 0.001), and Akt phosphorylation state in skeletal muscle. Finally, hand grip strength increased 26.5 ± 27.5 % at 180 days on-VAD (p < 0.05 versus baseline).

CONCLUSION

Our data demonstrate that VAD implantation corrects GH/IGF-1 signaling, improves muscle structure and function, and enhances oxidative muscle metabolism in patients with advanced HF.

Personalized preventive medicine: genetics and the response to regular exercise in preventive interventions

Regular exercise and a physically active lifestyle have favorable effects on health. Several issues related to this theme are addressed in this report. A comment on the requirements of personalized exercise medicine and in-depth biological profiling along with the opportunities that they offer is presented. This is followed by a brief overview of the evidence for the contributions of genetic differences to the ability to benefit from regular exercise. Subsequently, studies showing that mutations in TP53 influence exercise capacity in mice and humans are succinctly described. The evidence for effects of exercise on endothelial function in health and disease also is covered. Finally, changes in cardiac and skeletal muscle in response to exercise and their implications for patients with cardiac disease are summarized. Innovative research strategies are needed to define the molecular mechanisms involved in adaptation to exercise and to translate them into useful clinical and public health applications.

Salinity and temperature variations reflecting on cellular PCNA, IGF-I and II expressions, body growth and muscle cellularity of a freshwater fish larvae

The present study assessed the influence of salinity and temperature on body growth and on muscle cellularity of Lophiosilurus alexaxdri vitelinic larvae. Slightly salted environments negatively influenced body growth of freshwater fish larvae and we observed that those conditions notably act as an environmental influencer on muscle growth and on local expression of hypertrophia and hypeplasia markers (IGFs and PCNA). Furthermore, we could see that salinity tolerance for NaCl 4gl(-)(1) diminishes with increasing temperature, evidenced by variation in body and muscle growth, and by irregular morphology of the lateral skeletal muscle of larvae. We saw that an increase of both PCNA and autocrine IGF-II are correlated to an increase in fibre numbers and fibre diameter as the temperature increases and salinity diminishes. On the other hand, autocrine IGF-I follows the opposite way to the other biological parameters assessed, increasing as salinity increases and temperature diminishes, showing that this protein did not participate in muscle cellularity, but participating in molecular/cellular repair. Therefore, slightly salted environments may provide adverse conditions that cause some obstacles to somatic growth of this species, suggesting some osmotic expenditure with a salinity increment.

Adiponectin: key role and potential target to reverse energy wasting in chronic heart failure

The concept of skeletal muscle myopathy as a main determinant of exercise intolerance in chronic heart failure (HF) is gaining acceptance. Symptoms that typify HF patients, including shortness of breath and fatigue, are often directly related to the abnormalities of the skeletal muscle in HF. Besides muscular wasting, alterations in skeletal muscle energy metabolism, including insulin resistance, have been implicated in HF. Adiponectin, an adipocytokine with insulin-sensitizing properties, receives increasing interest in HF. Circulating adiponectin levels are elevated in HF patients, but high levels are paradoxically associated with poor outcome. Previous analysis of m. vastus lateralis biopsies in HF patients highlighted a striking functional adiponectin resistance. Together with increased circulating adiponectin levels, adiponectin expression within the skeletal muscle is elevated in HF patients, whereas the expression of the main adiponectin receptor and genes involved in the downstream pathway of lipid and glucose metabolism is downregulated. In addition, the adiponectin-related metabolic disturbances strongly correlate with aerobic capacity (VO2 peak), sub-maximal exercise performance and muscle strength. These observations strengthen our hypothesis that adiponectin and its receptors play a key role in the development and progression of the "heart failure myopathy". The question whether adiponectin exerts beneficial rather than detrimental effects in HF is still left unanswered. This current research overview will elucidate the emerging role of adiponectin in HF and suggests potential therapeutic targets to tackle energy wasting in these patients.

Metabolic and structural impairment of skeletal muscle in heart failure

Physiologic endurance exercise performance is primarily limited by cardiac function. In patients with heart failure, there is dissociation between cardiac performance and exercise capacity, suggesting a distinct role of abnormal peripheral organ function, including skeletal muscle function. The impact of heart failure upon skeletal muscle and exercise performance will be discussed with a focus on molecular, structural, and functional derangements in skeletal muscle of patients with heart failure.

Analysis of skeletal muscle gene expression patterns and the impact of functional capacity in patients with systolic heart failure

BACKGROUND

Declining physical function is common among systolic heart failure (HF) patients and heralds poor clinical outcomes. We hypothesized that coordinated shifts in expression of ubiquitin-mediated atrophy-promoting genes are associated with muscle atrophy and contribute to decreased physical function.

METHODS

Systolic HF patients (left ventricular ejection fraction [LVEF] ≤40%) underwent skeletal muscle biopsies (nondominant vastus lateralis) and comprehensive physical assessments. Skeletal muscle gene expression was assessed with the use of real-time polymerase chain reaction. Aerobic function was assessed with the use of cardiopulmonary exercise and 6-minute walk tests. Strength capacity was assessed with the use of pneumatic leg press (maximum strength and power). Serologic inflammatory markers also were assessed.

RESULTS

54 male patients (66.6 ± 10.0 years) were studied: 24 systolic HF patients (mean LVEF 28.9 ± 7.8%) and 30 age-matched control subjects. Aerobic and strength parameters were diminished in HF versus control. FoxO1 and FoxO3 were increased in HF versus control (7.9 ± 6.2 vs 5.0 ± 3.5, 6.5 ± 4.3 vs 4.3 ± 2.8 relative units, respectively; P ≤ .05 in both). However, atrogin-1 and MuRF-1 were similar in both groups. PGC-1α was also increased in HF (7.9 ± 5.4 vs. 5.3 ± 3.6 relative units; P < .05). Muscle levels of insulin-like growth factor (IGF) 1 as well as serum levels of tumor necrosis factor α, C-reactive protein, interleukin (IL) 1β, and IL-6 were similar in HF and control.

CONCLUSION

Expression of the atrophy-promoting genes FoxO1 and FoxO3 were increased in skeletal muscle in systolic HF compared with control, but other atrophy gene expression patterns (atrogin-1 and MuRF-1), as well as growth promoting patterns (IGF-1), were similar. PGC-1α, a gene critical in enhancing mitochondrial function and moderating FoxO activity, may play an important counterregulatory role to offset ubiquitin pathway-mediated functional decrements.

Exercise intolerance in chronic heart failure: the role of cortisol and the catabolic state

Chronic heart failure (CHF) is a complex clinical syndrome leading to exercise intolerance due to muscular fatigue and dyspnea. Hemodynamics fail to explain the reduced exercise capacity, while a significant skeletal muscular pathology seems to constitute the main underlying mechanism for exercise intolerance in CHF patients. There have been proposed several metabolic, neurohormonal and immune system abnormalities leading to an anabolic/catabolic imbalance that plays a central role in the pathogenesis of the wasting process of skeletal muscle myopathy. The impairment of the anabolic axes is associated with the severity of symptoms and the poor outcome in CHF, whereas increased cortisol levels are predictive of exercise intolerance, ventilatory inefficiency and chronotropic incompetence, suggesting a significant contributing mechanism to the limited functional status. Exercise training and device therapy could have beneficial effects in preventing and treating muscle wasting in CHF. However, specific anabolic treatment needs more investigation to prove possible beneficial effects.

IGF-1 gene-modified muscle-derived stem cells are resistant to oxidative stress via enhanced activation of IGF-1R/PI3K/AKT signaling and secretion of VEGF

Reactive oxygen species (ROS)-induced oxidative stress increases in skeletal muscle with aging and decreases the viability of implanted cells. Type 1 insulin-like growth factor (IGF-1) promotes the survival of skeletal muscle cells under oxidative stress. It is unknown whether IGF-1 protects muscle-derived stem cells (MDSCs) from oxidative stress. In this study, we genetically engineered rat MDSCs to overexpress IGF-1 and determined cell viability, apoptosis, and VEGF secretion under oxidative stress. Overexpression of IGF-1 prevented MDSCs from H2O2-induced caspase-dependent apoptotic cell death by upregulating the PI3K/AKT pathway, accompanied with an increase of NF-κB, p-NF-κB, Bcl-2, and VEGF, as well as a decrease of Bax. In contrast, pre-administration of picropodophyllinb, wortmannin, 1L-6-hydroxymethyl-chiro-inositol-2-((R)-2-O-methyl-3-O-octadecylcarbonate), or pyrrolidine-dithiocarbamate, specific inhibitors of IGF-1R, PI3K, AKT, and NF-κB, respectively, followed by treatment with H2O2, resulted in cell death of MDSCs. Our data indicated that IGF-1 suppresses apoptosis and enhances the paracrine function of MDSCs under oxidative stress via enhancing IGF-1R/PI3K/AKT signaling. Thus, IGF-1 gene-modified MDSCs present a potential application in the treatment of muscle wasting, such as urethra intrinsic sphincter deficiency.

Unraveling new mechanisms of exercise intolerance in chronic heart failure: role of exercise training

Despite remarkable progress in the therapeutic approach of patients with chronic heart failure (CHF), exercise intolerance remains one of the hallmarks of the disease. During the past two decades, evidence has accumulated to underscore the key role of both endothelial dysfunction and skeletal muscle wasting in the process that gradually leads to physical incapacity. Whereas reverse ventricular remodeling has been attributed to aerobic exercise training, the vast majority of studies conducted in this specific patient population emphasize the reversal of peripheral abnormalities. In this review, we provide a general overview on underlying pathophysiological mechanisms. In addition, emphasis is put on recently identified pathways, which contribute to a deeper understanding of the main causes of exercise tolerance and the potential for reversal through exercise training. Recently, deficient bone marrow-related endothelial repair mechanisms have received considerable attention. Both acute exercise bouts, as well as exercise training, affect the mobilization of endothelial progenitor cells and their function. The observed changes following exercise training are believed to significantly contribute to improvement of peripheral endothelial function, as well as exercise capacity. With regard to skeletal muscle dysfunction and energy deprivation, adiponectin has been suggested to play a significant role. The demonstration of local skeletal muscle adiponectin resistance may provide an interesting and new link between the insulin resistant state and skeletal muscle wasting in CHF patients.

Intrinsic skeletal muscle alterations in chronic heart failure patients: a disease-specific myopathy or a result of deconditioning?

Chronic heart failure (CHF) patients frequently experience impaired exercise tolerance due to skeletal muscle fatigue. Studies suggest that this in part is due to intrinsic alterations in skeletal muscle of CHF patients, often interpreted as a disease-specific myopathy. Knowledge about the mechanisms underlying these skeletal muscle alterations is of importance for the pathophysiological understanding of CHF, therapeutic approach and rehabilitation strategies. We here critically review the evidence for skeletal muscle alterations in CHF, the underlying mechanisms of such alterations and how skeletal muscle responds to training in this patient group. Skeletal muscle characteristics in CHF patients are very similar to what is reported in response to chronic obstructive pulmonary disease (COPD), detraining and deconditioning. Furthermore, skeletal muscle alterations observed in CHF patients are reversible by training, and skeletal muscle of CHF patients seems to be at least as trainable as that of matched controls. We argue that deconditioning is a major contributor to the skeletal muscle dysfunction in CHF patients and that further research is needed to determine whether, and to what extent, the intrinsic skeletal muscle alterations in CHF represent an integral part of the pathophysiology in this disease.

Cachexia in chronic heart failure: endocrine determinants and treatment perspectives

It is well documented in the current literature that chronic heart failure is often associated with cachexia, defined as involuntary weight loss of 5 % in 12 month or less. Clinical studies unraveled that the presence of cachexia decreases significantly mean survival of the patient. At the molecular level mainly myofibrillar proteins are degraded, although a reduced protein synthesis may also contribute to the loss of muscle mass. Endocrine factors clearly regulate muscle mass and function by influencing the normally precisely controlled balance between protein breakdown and protein synthesis The aim of the present article is to review the knowledge in the field with respect to the role of endocrine factors for the regulation of cachexia in patients with CHF and deduce treatment perspectives.

Effect of ghrelin and its analogues, BIM-28131 and BIM-28125, on the expression of myostatin in a rat heart failure model

BACKGROUND

In chronic heart failure (CHF), cachexia is a hallmark of the terminal stage of this disease and is associated with a severely reduced quality of life and poor prognosis. Therapeutic options are currently not available. Ghrelin and its analogues BIM-28125 and BIM-28131 (now known as RM-131) have been shown to increase weight in a rat model of CHF. It has been further demonstrated that the expression of myostatin, a negative regulator of skeletal muscle mass, is increased in CHF. The aim of the study was to investigate the influence of ghrelin or its analogues on myostatin in CHF.

METHODS

In an animal model of CHF, Sprague-Dawley rats received either ghrelin or two ghrelin analogues BIM-28125 and BIM-28131 in two different concentrations (50 and 500 nmol/kg/day) compared to placebo. The compounds were delivered using osmotic mini pumps. The expression of myostatin was analyzed in skeletal muscle by RT-PCR and Western blot, and muscle mass of gastrocnemius muscle was measured. The plasma levels of tumor necrosis factor alpha (TNF-α) were measured.

RESULTS

The relative weight of the gastrocnemius muscle of the sham-operated group was significantly increased compared to placebo-treated CHF rats. The application of ghrelin analogue BIM-28125 and BIM-28131 in their higher concentrations led to a significant reduction in myostatin mRNA expression in comparison to placebo. Myostatin protein expression was significantly reduced in both concentrations of ghrelin and BIM-28131 and in the lower concentration of BIM-28125. The increase of TNF-α plasma concentration in the CHF-animals could be abolished by all used substances.

CONCLUSIONS

In an animal model of CHF, the expression of myostatin is significantly reduced in the skeletal muscle after application of ghrelin and most concentrations of its analogues BIM-28125 and BIM-28131 possibly due to anti-inflammatory effects.

Skeletal muscle abnormalities in chronic heart failure

Skeletal muscle abnormalities are well-established in patients with heart failure from an early stage in the progression of the disease and contribute to their symptoms and the limitation of physical activity. Heart failure-induced skeletal muscle pathology includes morphologic, histologic, and enzymatic changes along with derangements in skeletal muscle metabolism and autonomic function. These alterations influence both peripheral and ventilatory muscles, are present at rest, and deteriorate during exercise and their occurrence depends upon the severity and the duration of CHF syndrome. Future studies will be needed to elucidate the origin of skeletal "myopathy" and its reversibility, which is associated with improvement in exercise capacity, observed after physical training programs.

Exercise training attenuates MuRF-1 expression in the skeletal muscle of patients with chronic heart failure independent of age: the randomized Leipzig Exercise Intervention in Chronic Heart Failure and Aging catabolism study

BACKGROUND

Muscle wasting occurs in both chronic heart failure (CHF) and normal aging and contributes to exercise intolerance and increased morbidity/mortality. However, the molecular mechanisms of muscle atrophy in CHF and their interaction with aging are still largely unknown. We therefore measured the activation of the ubiquitin-proteasome system and the lysosomal pathway of intracellular proteolysis in muscle biopsies of CHF patients and healthy controls in two age strata and assessed the age-dependent effects of a 4-week endurance training program on the catabolic-anabolic balance.

METHODS AND RESULTS

Sixty CHF patients (30 patients aged ≤55 years, mean age 46±5 years; 30 patients aged ≥65 years, mean age 72±5 years) and 60 healthy controls (30 subjects aged ≤55 years, mean age 50±5 years; 30 subjects aged ≥65 years, mean age 72±4 years) were randomized to 4 weeks of supervised endurance training or to a control group. Before and after the intervention, vastus lateralis muscle biopsies were obtained. The expressions of cathepsin-L and the muscle-specific E3 ligases MuRF-1 and MAFbx were measured by real-time polymerase chain reaction and confirmed by Western blot. At baseline, MuRF-1 expression was significantly higher in CHF patients versus healthy controls (mRNA: 624±59 versus 401±25 relative units; P=0.007). After 4 weeks of exercise training, MuRF-1 mRNA expression was reduced by -32.8% (P=0.02) in CHF patients aged ≤55 years and by -37.0% (P<0.05) in CHF patients aged ≥65 years.

CONCLUSIONS

MuRF-1, a component of the ubiquitin-proteasome system involved in muscle proteolysis, is increased in the skeletal muscle of patients with heart failure. Exercise training results in reduced MuRF-1 levels, suggesting that it blocks ubiquitin-proteasome system activation and does so in both younger and older CHF patients.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT00176319.

Influence of prediagnostic recreational physical activity on survival from breast cancer

Recreational physical activity (RPA) is associated with a reduced risk of developing breast cancer, but there is limited research on whether prediagnostic RPA influences survival after breast cancer diagnosis or not. We evaluated the association between prediagnostic RPA and risk of death in 1508 women with a first breast cancer diagnosis during 1996 and 1997 in the population-based Long Island Breast Cancer Study Project. A 5-year mortality, through the end of 2002, was assessed using the National Death Index (N=196). An in-person interview was completed shortly after diagnosis to obtain information on lifetime RPA, which was expressed as metabolic equivalent task hours per week (MET-h/week). A lower risk of all-cause death was observed for women who engaged in an average of 9 or more MET-h/week of RPA from menarche to diagnosis compared with women who did not exercise [age-adjusted and BMI adjusted hazard ratio (HR)=0.57; 95% confidence interval (CI)=0.39-0.83], an association that was similar when evaluated according to menopausal status. Compared with women who did not engage in moderate RPA, those who engaged in any moderate intensity lifetime RPA (>0 MET-h/week) were found to have lower all-cause mortality (HR=0.62; 95% CI=0.46-0.84) and breast cancer-specific mortality (HR=0.64; 95% CI=0.43-0.93). Among postmenopausal women, RPA that took place after menopause resulted in a decrease in overall mortality, whereas no association was observed for RPA which took place prior to menopause (for >0 MET-h/week of RPA vs. no RPA, the HR=0.61; 95% CI=0.39-0.94 and HR=1.00; 95% CI=0.65-1.54, respectively). This study provides support that RPA prior to breast cancer diagnosis improves survival.

Growth hormone, insulin-like growth factor 1, and insulin signaling-a pharmacological target in body wasting and cachexia

Cachexia is an irreversible process that can develop in the course of chronic disease. It is characterized by the remodeling of the metabolic, inflammatory, and endocrine pathways. Insulin, growth hormone (GH), and insulin-like growth factor 1 (IGF-1) are involved in glucose, protein, and fat metabolism, which regulates body composition. In body wasting and cachexia, their signaling is impaired and causes anabolic/catabolic imbalance. Important mechanisms include inflammatory cytokines and neurohormonal activation. Remodeled post-receptor insulin, GH, and IGF-1 pathways constitute a potential target for pharmacological treatment in the setting of body wasting and cachexia. Peroxisome proliferator-activated receptor gamma agonists, drugs inhibiting angiotensin II action (angiotensin II antagonists and inhibitors of angiotensin-converting enzyme), and testosterone, which interfere with post-receptor pathways of insulin, GH, and IGF-1, were investigated as pharmacological intervention targets and various clinically important implications were reported. There are several other potential targets, but their treatment feasibility and applicability is yet to be established.