Exercise training reverses age-induced diastolic dysfunction and restores coronary microvascular function

Coronary microvascular dysfunction in childhood: An emerging pathological entity and its clinical implications

Coronary microvascular dysfunction (CMD) encompasses a spectrum of structural and functional alterations in coronary microvasculature resulting in impaired coronary blood flow and consequent myocardial ischemia without obstruction in epicardial coronary artery. The pathogenesis of CMD is complex involving both functional and structural alteration in the coronary microcirculation. In adults, CMD is predominantly discussed in context with anginal chest pain or existing ischemic heart disease and its risk factors. The presence of CMD suggests increased risk of adverse cardiovascular events independent of coronary atherosclerosis. Coronary microvascular dysfunction is also known in children but is rarely recognized due to paucity of concommitent coronary artery disease. Thus, its clinical presentation, underlying mechanism of impaired microcirculation, and prognostic significance are poorly understood. In this review article, we will overview variable CMD reported in children and delineate its emerging clinical significance.

Impact of Coronary Microvascular Dysfunction on Functional Left Ventricular Remodeling and Diastolic Dysfunction

BACKGROUND

Coronary microvascular dysfunction (CMD) is a common complication of ST-segment-elevation myocardial infarction (STEMI) and can lead to adverse cardiovascular events. Whether CMD after STEMI is associated with functional left ventricular remodeling (FLVR) and diastolic dysfunction, has not been investigated.

METHODS AND RESULTS

This is a nonrandomized, observational, prospective study of patients with STEMI with multivessel disease. Coronary flow reserve and index of microcirculatory resistance of the culprit vessel were measured at 3 months post-STEMI. CMD was defined as index of microcirculatory resistance ≥25 or coronary flow reserve <2.0 with a normal fractional flow reserve. We examined the association between CMD, LV diastolic dysfunction, FLVR, and major adverse cardiac events at 12-month follow-up. A total of 210 patients were enrolled; 59.5% were men, with a median age of 65 (interquartile range, 58-76) years. At 3-month follow-up, 57 patients (27.14%) exhibited CMD. After 12 months, when compared with patients without CMD, patients with CMD had poorer LV systolic function recovery (-10.00% versus 8.00%; P<0.001), higher prevalence of grade 2 LV diastolic dysfunction (73.08% versus 1.32%; P<0.001), higher prevalence of group 3 or 4 FLVR (11.32% versus 7.28% and 22.64% versus 1.99%, respectively; P<0.001), and higher incidence of major adverse cardiac events (50.9% versus 9.8%; P<0.001). Index of microcirculatory resistance was independently associated with LV diastolic dysfunction and adverse FLVR.

CONCLUSIONS

CMD is present in ≈1 of 4 patients with STEMI during follow-up. Patients with CMD have a higher prevalence of LV diastolic dysfunction, adverse FLVR, and major adverse cardiac events at 12 months compared with those without CMD.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique Identifier: NCT05406297.

Intrinsic and Extrinsic Contributors to the Cardiac Benefits of Exercise

Among its many cardiovascular benefits, exercise training improves heart function and protects the heart against age-related decline, pathological stress, and injury. Here, we focus on cardiac benefits with an emphasis on more recent updates to our understanding. While the cardiomyocyte continues to play a central role as both a target and effector of exercise's benefits, there is a growing recognition of the important roles of other, noncardiomyocyte lineages and pathways, including some that lie outside the heart itself. We review what is known about mediators of exercise's benefits-both those intrinsic to the heart (at the level of cardiomyocytes, fibroblasts, or vascular cells) and those that are systemic (including metabolism, inflammation, the microbiome, and aging)-highlighting what is known about the molecular mechanisms responsible.

Endurance exercise upregulates mtp expression in aged Drosophila to ameliorate age-related diastolic dysfunction and extend lifespan

Diastolic dysfunction is a major cardiac dysfunction, and an important predisposing factor is age. Although exercise training is often used for the prevention and treatment of cardiovascular disease nowadays, little is currently known about whether exercise interventions associated with the slowing of cardiac aging are related to mtp-related pathways. In the present study, the UAS/Tub-Gal4 system was used to knockdown whole-body mtp expression levels in Drosophila, which underwent 2 weeks of endurance training. By conducting different assays and quantifying different indicators, we sought to investigate the relationship between mtp, exercise, and age-related diastolic dysfunction. We found that (1) Drosophila in the mtpRNAi youth group exhibited age-related diastolic dysfunction and had a significantly shorter mean lifespan. (2) Endurance exercise could improve diastolic dysfunction and prolong lifespan in aged Drosophila. (3) Endurance exercise could increase the expression levels of apolpp and Acox3, and decrease the levels of TC, LDL-C, and TG in the aged group. In summary, aging causes age-associated diastolic dysfunction in Drosophila, and systemic knockdown of mtp causes premature age-associated diastolic dysfunction in young Drosophila. Besides, endurance exercise improves age-related diastolic dysfunction and prolongs lifespan.

An observational study of microcirculation among healthy individuals by age and sex

OBJECTIVE

This study measured normal ranges of microcirculatory parameters in healthy individuals and investigated differences in parameters by age and sex.

METHODS

Participants were enrolled into three groups with equal numbers of male and female: young (20-39 years), middle-aged (40-59 years), and elderly (60-79 years). Sublingual microcirculation images were obtained using the incident dark field (IDF).

RESULTS

A total of 75 female and 75 male healthy individuals were enrolled. The elderly group had a higher TVD (26.5 [2] vs. 25.2 [1.8]; p = 0.019) and a lower PPV (97 [2] vs. 98 [3]; p = 0.03) than did the young group. In the elderly group, systolic blood pressure (SBP) and mean arterial pressure (MAP) were moderately and positively correlated with MFI score (r = 0.407, p < 0.05, and r = 0.403, p < 0.05, respectively). The female participants had a lower MFI score than did the male participants (2.9 [2.8-3] vs. 3.0 [2.9-3]; p = 0.015).

CONCLUSIONS

This study revealed the range of microcirculatory parameters between different ages and sexes in healthy individuals. We found that blood pressure levels were correlated with microcirculatory parameters, especially in elders and female.

Upregulation of Orai Channels Contributes to Aging-Related Vascular Alterations in Rat Coronary Arteries

Vascular territories display heterogeneous sensitivity to the impacts of aging. The relevance of the STIM/Orai system to vascular function depends on the vascular bed. We aimed to evaluate the contribution of the STIM/Orai system to aging-related vascular dysfunction in rat coronary circulation. Vascular function was evaluated according to myography in coronary arteries from young (three-month-old) and older (twenty-month-old) rats. The effects of aging and STIM/Orai inhibition on the contraction and relaxation of the coronary arteries and on the protein expression of STIM-1, Orai1, and Orai3 in these vessels were determined. Aging-related hypercontractility to serotonin and endothelin-1 in arteries from male rats was reversed by STIM/Orai inhibition with YM-58483 or by specifically blocking the Orai1 channel with Synta66. The inhibitory effects of Synta66 on coronary vasoconstriction were also observed in older female rats. YM-58483 relaxed serotonin- but not KCl-contracted arteries from males. STIM/Orai inhibition improved defective endothelial vasodilations in aged arteries, even in the presence of NO synthase and cyclooxygenase inhibitors, but not in KCl-contracted segments. YM-58483 significantly enhanced relaxations to calcium-activated potassium channel stimulation in aged vessels. Increased protein expression of Orai1 and Orai3 was detected in arterial homogenates and sections from older rats. Upregulation of the Orai channel contributes to aging-related coronary dysfunction, revealing a potential target in reducing CVD risk.

Effects of high-intensity interval training on cardiac remodelling, function and coronary microcirculation in de novo heart transplant patients: a substudy of the HITTS randomised controlled trial

Objectives

High-intensity interval training (HIT) improves peak oxygen consumption (VO2peak) in de novo heart transplant (HTx) recipients. It remains unclear whether this improvement early after HTx is solely dependent on peripheral adaptations, or due to a linked chain of central and peripheral adaptations. The objective of this study was to determine whether HIT results in structural and functional adaptations in the cardiovascular system.

Methods

Eighty-one de novo HTx recipients were randomly assigned to participate in either 9 months of supervised HIT or standard care exercise-based rehabilitation. Cardiac function was assessed by echocardiogram and the coronary microcirculation with the index of microcirculatory resistance (IMR) at baseline and 12 months after HTx.

Results

Cardiac function as assessed by global longitudinal strain was significantly better in the HIT group than in the standard care group (16.3±1.2% vs 15.6±2.2%, respectively, treatment effect = -1.1% (95% CI -2.0% to -0.2%), p=0.02), as was the end-diastolic volume (128.5±20.8 mL vs 123.4±15.5 mL, respectively, treatment effect=4.9 mL (95% CI 0.5 to 9.2 mL), p=0.03). There was a non-significant tendency for IMR to indicate improved microcirculatory function (13.8±8.0 vs 16.8±12.0, respectively, treatment effect = -4.3 (95% CI -9.1 to 0.6), p=0.08).

Conclusion

When initiated early after HTx, HIT leads to both structural and functional cardiovascular adaptations.

Trial registration number

NCT01796379.

Accelerated ageing and coronary microvascular dysfunction in chronic heart failure in Tgαq*44 mice

Age represents a major risk factor in heart failure (HF). However, the mechanisms linking ageing and HF are not clear. We aimed to identify the functional, morphological and transcriptomic changes that could be attributed to cardiac ageing in a model of slowly progressing HF in Tgαq*44 mice in reference to the cardiac ageing process in FVB mice. In FVB mice, ageing resulted in the impairment of diastolic cardiac function and in basal coronary flow (CF), perivascular and interstitial fibrosis without changes in the cardiac activity of angiotensin-converting enzyme (ACE) or aldosterone plasma concentration. In Tgαq*44 mice, HF progression was featured by the impairment of systolic and diastolic cardiac function and in basal CF that was associated with a distinct rearrangement of the capillary architecture, pronounced perivascular and interstitial fibrosis, progressive activation of cardiac ACE and systemic angiotensin-aldosterone-dependent pathways. Interestingly, cardiac ageing genes and processes were represented in Tgαq*44 mice not only in late but also in early phases of HF, as evidenced by cardiac transcriptome analysis. Thirty-four genes and 8 biological processes, identified as being ageing related, occurred early and persisted along HF progression in Tgαq*44 mice and were mostly associated with extracellular matrix remodelling and fibrosis compatible with perivascular fibrosis resulting in coronary microvascular dysfunction (CMD) in Tgαq*44 mice. In conclusion, accelerated and persistent cardiac ageing contributes to the pathophysiology of chronic HF in Tgαq*44 mice. In particular, prominent perivascular fibrosis of microcirculation resulting in CMD represents an accelerated cardiac ageing phenotype that requires targeted treatment in chronic HF.

Aerobic high-intensity interval exercise training in patients with angina and no obstructive coronary artery disease: feasibility and physiological effects

Aims

Patients with chest pain and normal coronary angiogram [angina with normal coronary arteries (ANOCA)] constitute a therapeutic problem with considerable functional limitation and reduced quality of life. The aims of the current pilot study were to (i) explore if a structured aerobic high-intensity interval training (HIT) program for 12 weeks was feasible in patients with ANOCA, and (ii) to assess mechanisms related to symptoms in this population.

Methods and results

Sixteen patients with ANOCA underwent a 3-month aerobic HIT program with one-to-one monitored exercise sessions on treadmill in a 4 min × 4 manner, three times a week. Four patients served as controls. Coronary flow velocity reserve (CFVR) transthoracic Doppler, flow-mediated vasodilation (FMD) and VO_2max was measured at baseline and after 12 weeks. The average attendance to training sessions was 82.3% ± 10.1 (56-94). CFVR in the training group increased from 2.50 ± 0.48 to 3.04 ± 0.71 (P < 0.001) whereas FMD increased from 4.19 ± 2.42% to 8.28 ± 2.85% (P < 0.001). Improvement in CFVR correlated with the relative improvement in FMD (R = 0.45, P = 0.047). This was associated with an increase in VO_2max from 28.75 ± 6.51 mL/kg/min to 31.93 ± 6.46 mL/kg/min (P < 0.001).

Conclusion

A 3-month program of monitored HIT was feasible, with high adherence resulting in improved functional capacity in patients with ANOCA. CFVR improved and this improvement was associated with improved FMD.

ClinicalTrialsgov Identifier

NCT02905630.

Vascular compliance and left ventricular compliance cross talk: Implications for using long-term heat acclimation in cardiac care

1) The first evidence of the beneficial impact of Long-Term-Heat-Acclimation (LTHA) on cardio-vascular compliance was the positive inotropic response and improved left ventricular (LV) compliance noted when isolated hearts from LTHA rats were studied. Human echo study demonstrates that passive HA affects the right ventricle and the atria as well. 2) There is a cross-talk between vascular and cardiac compliance. Vascular compliance per se is defined by central venous pressure-Blood volume relationship-Global Vascular Compliance (GVC). It is determined by the sum of the vascular compliance of the vessels in every organ in any physiological state, varies with LTHA and thus influences cardiac performance. LTHA improves endothelial function, increases NO (nitric oxide) production, in-turn stimulating alterations in ECM (extracellular matrix) via the TGF β1-SMAD pathway. 3) LTHA is associated with transformation from fast to slow myosin, heat acclimation ischemic/hypoxic cross-tolerance and alterations in the extracellular matrix. 4) A human translational study demonstrated improved LV compliance following bypass surgery in LTHA subjects compared to controls. 5) Diastolic dysfunction and the impact of comorbidities with vascular and non- vascular origins are major contributors to the syndrome of heart failure with preserved ejection function (HFPEF). Unfortunately, there is a paucity of treatment modalities that improve diastolic dysfunction. 6) In the current mini-review we suggest that LTHA may be beneficial to HFPEF patients by remodeling cardiac compliance and vascular response.

Effects of two different exercise paradigms on cardiac function, BDNF-TrkB expression, and myocardial protection in the presence and absence of Western diet

Background

Brain-derived neurotrophic factor (BDNF) -tropomyosin-related kinase receptor B (TrkB) signaling is a vital regulator of myocardial performance. Here, we tested the impact of high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT) on heart function, metabolic parameters, and serum/cardiac BDNF (with its TrkB receptor) in animals fed a Western (WD) or regular diet (ND). Further, myocardial expression of pro-inflammatory cytokine interleukin-18 (IL-18) and cardioprotective molecule heme oxygens-1 (HO-1) were monitored.

Methods

Wistar rats were divided into HIIT, MICT, and sedentary (SED), all fed a WD or ND, for 12 weeks. Heart function, protein expression, and serum factors were assessed via echocardiography, western blotting, and ELISA, respectively.

Results

WD plus SED caused insulin resistance, dyslipidemia, visceral fat deposition, serum BDNF depletion as well as cardiac upregulation of IL-18 and downregulation of HO-1, without affecting, heart function and BDNF-TrkB expression. The cardiometabolic risk factors, serum BDNF losses, and IL-18 overexpression were similarly obviated by HIIT and MICT, although HO-1 expression was boosted by HIIT exclusively (even in ND). HIIT enhanced heart function, regardless of the diet. HIIT augmented cardiac BDNF expression, with a significant difference between ND and WD. Likewise, HIIT instigated TrkB expression only in ND.

Conclusions

HIIT and MICT can cope with myocardial inflammation and cardiometabolic risk factors in WD consumers and, exclusively, HIIT may grant further protection by increasing heart function, BDNF-TrkB expression, and HO-1 expression. Thus, the HIIT paradigm should be considered as a preference for subjects who require heart function to be preserved or enhanced.

Effects of Acute Interval Exercise on Arterial Stiffness and Cardiovascular Autonomic Regulatory Responses: A Narrative Review of Potential Impacts of Aging

The physiological changes associated with aging deleteriously impact cardiovascular function and regulation and therefore increase the risk of developing cardiovascular disease. There is substantial evidence that changes in the autonomic nervous system and arterial stiffness play an important role in the development of cardiovascular disease during the aging process. Exercise is known to be effective in improving autonomic regulation and arterial vascular compliance, but differences in the type and intensity of exercise can have varying degrees of impact on vascular regulatory responses and autonomic function. There is still little evidence on whether there are differences in the response of exercise interventions to cardiovascular modulatory effects across the lifespan. In addition, acute interval exercise challenges can improve autonomic modulation, although the results of interval exercise on autonomic physiological parameters vary. Therefore, this narrative review focuses on evaluating the effects of acute interval exercise on blood pressure regulation and autonomic responses and also incorporates studies investigating different age groups to evaluate the effects of acute interval exercise on the autonomic nervous system. Herein we also summarize existing literature examining the acute cardiovascular responses to varied modes of interval exercise, as well as to further compare the benefits of interval exercise with other types of exercise on autonomic regulation and arterial stiffness. After reviewing the existing literature, it has been shown that with advancing age, changes in the autonomic nervous activity of interval exercise result in significant impacts on the cardiovascular system. We document that with advancing age, changes in the autonomic nerves lead to aging of the nervous system, thereby affecting the regulation of blood pressure. According to the limited literature, interval exercise is more effective in attenuating arterial stiffness than continuous exercise, but the difference in exercise benefits may depend on the training mode, intensity, duration of exercise, and the age of participants. Therefore, the benefits of interval exercise on autonomic and arterial stiffness improvement still warrant investigation, particularly the impact of age, in future research.

Cardiac remodeling in ambitious endurance-trained amateur athletes older than 50 years–an observational study

Background

Data on cardiac remodeling in veteran athletes are conflicting but of clinical importance.

Methods

Sixty-nine clinically stable and healthy individuals >50 years were identified (median 55 (IQR 52–64), 26% female). Echocardiographic features were identified in individuals, who have performed endurance sports at 70% of their maximum heart rate for at least 1 hour 3 times/ week over the previous 5 years.

Results

Median training time in all participants was 6 hours per week. Therefore, based on these 6 hours of weekly training, participants were grouped into 45 ambitious endurance-trained amateur athletes (EAA) and 24 recreationally active endurance-trained athletes (RAP) training ≥6 hours (6–10) and <6 hours (3.5–5), respectively. Left ventricular (LV) diameters were slightly larger in EAA than in RAP (27 mm/m² (25–28) vs. 25 mm/m² (24–27), p = 0.023) and EAA showed preserved diastolic function (p = 0.028) with lower E/E’ ratio (7 (6–9) vs. 9 (7–10), p = 0.039). Interventricular septal thickness and relative wall thickness ratio were similar. Global right ventricular and LV strain were similar, but left atrial (LA) reservoir strain was higher in EAA than in RAP (27% (22–34) vs. 20% (15–29), p = 0.002).

Conclusions

Endurance training in healthy athletes >50 years is not associated with chamber dilatation or LV hypertrophy. A weekly training duration of ≥6 hours seems beneficial to preserve diastolic function associated with an increased LA reservoir function.

The Feline Cardiomyopathies: 2. Hypertrophic cardiomyopathy

Practical relevance:

Hypertrophic cardiomyopathy (HCM) is the most common form of feline cardiomyopathy observed clinically and may affect up to approximately 15% of the domestic cat population, primarily as a subclinical disease. Fortunately, severe HCM, leading to heart failure or arterial thromboembolism (ATE), only occurs in a small proportion of these cats.

Patient group:

Domestic cats of any age from 3 months upward, of either sex and of any breed, can be affected. A higher prevalence in male and domestic shorthair cats has been reported.

Diagnostics:

Subclinical feline HCM may or may not produce a heart murmur or gallop sound. Substantial left atrial enlargement can often be identified radiographically in cats with severe HCM. Biomarkers should not be relied on solely to diagnose the disease. While severe feline HCM can usually be diagnosed via echocardiography alone, feline HCM with mild to moderate left ventricular (LV) wall thickening is a diagnosis of exclusion, which means there is no definitive test for HCM in these cats and so other disorders that can cause mild to moderate LV wall thickening (eg, hyperthyroidism, systemic hypertension, acromegaly, dehydration) need to be ruled out.

Key findings:

While a genetic cause of HCM has been identified in two breeds and is suspected in another, for most cats the cause is unknown. Systolic anterior motion of the mitral valve (SAM) is the most common cause of dynamic left ventricular outflow tract obstruction (DLVOTO) and, in turn, the most common cause of a heart murmur with feline HCM. While severe DLVOTO is probably clinically significant and so should be treated, lesser degrees probably are not. Furthermore, since SAM can likely be induced in most cats with HCM, the distinction between HCM without obstruction and HCM with obstruction (HOCM) is of limited importance in cats. Diastolic dysfunction, and its consequences of abnormally increased atrial pressure leading to signs of heart failure, and sluggish atrial blood flow leading to ATE, is the primary abnormality that causes clinical signs and death in affected cats. Treatment (eg, loop diuretics) is aimed at controlling heart failure. Preventive treatment (eg, antithrombotic drugs) is aimed at reducing the risk of complications (eg, ATE).

Conclusions:

Most cats with HCM show no overt clinical signs and live a normal or near-normal life despite this disease. However, a substantial minority of cats develop overt clinical signs referable to heart failure or ATE that require treatment. For most cats with clinical signs caused by HCM, the long-term prognosis is poor to grave despite therapy.

Areas of uncertainty:

Genetic mutations (variants) that cause HCM have been identified in a few breeds, but, despite valiant efforts, the cause of HCM in the vast majority of cats remains unknown. No treatment currently exists that reverses or even slows the cardiomyopathic process in HCM, again despite valiant efforts. The search goes on.

Aging-Induced Impairment of Vascular Function: Mitochondrial Redox Contributions and Physiological/Clinical Implications

Significance: The vasculature responds to the respiratory needs of tissue by modulating luminal diameter through smooth muscle constriction or relaxation. Coronary perfusion, diastolic function, and coronary flow reserve are drastically reduced with aging. This loss of blood flow contributes to and exacerbates pathological processes such as angina pectoris, atherosclerosis, and coronary artery and microvascular disease. Recent Advances: Increased attention has recently been given to defining mechanisms behind aging-mediated loss of vascular function and development of therapeutic strategies to restore youthful vascular responsiveness. The ultimate goal aims at providing new avenues for symptom management, reversal of tissue damage, and preventing or delaying of aging-induced vascular damage and dysfunction in the first place. Critical Issues: Our major objective is to describe how aging-associated mitochondrial dysfunction contributes to endothelial and smooth muscle dysfunction via dysregulated reactive oxygen species production, the clinical impact of this phenomenon, and to discuss emerging therapeutic strategies. Pathological changes in regulation of mitochondrial oxidative and nitrosative balance (Section 1) and mitochondrial dynamics of fission/fusion (Section 2) have widespread effects on the mechanisms underlying the ability of the vasculature to relax, leading to hyperconstriction with aging. We will focus on flow-mediated dilation, endothelial hyperpolarizing factors (Sections 3 and 4), and adrenergic receptors (Section 5), as outlined in Figure 1. The clinical implications of these changes on major adverse cardiac events and mortality are described (Section 6). Future Directions: We discuss antioxidative therapeutic strategies currently in development to restore mitochondrial redox homeostasis and subsequently vascular function and evaluate their potential clinical impact (Section 7). Antioxid. Redox Signal. 35, 974-1015.

Aerobic exercise training reduces cardiac function and coronary flow-induced vasodilation in mice lacking adiponectin

We tested the hypothesis that adiponectin deficiency attenuates cardiac and coronary microvascular function and prevents exercise training-induced adaptations of the myocardium and the coronary microvasculature in adult mice. Adult wild-type (WT) or adiponectin knockout (adiponectin KO) mice underwent treadmill exercise training or remained sedentary for 8-10 wk. Systolic and diastolic functions were assessed before and after exercise training or cage confinement. Vasoreactivity of coronary resistance arteries was assessed at the end of exercise training or cage confinement. Before exercise training, ejection fraction and fractional shortening were similar in adiponectin KO and WT mice, but isovolumic contraction time was significantly lengthened in adiponectin KO mice. Exercise training increased ejection fraction (12%) and fractional shortening (20%) with no change in isovolumic contraction time in WT mice. In adiponectin KO mice, both ejection fraction (-9%) and fractional shortening (-12%) were reduced after exercise training and these decreases were coupled to a further increase in isovolumic contraction time (20%). In sedentary mice, endothelium-dependent dilation to flow was higher in arterioles from adiponectin KO mice as compared with WT mice. Exercise training enhanced dilation to flow in WT mice but decreased flow-induced dilation in adiponectin KO mice. These data suggest that compensatory mechanisms contribute to the maintenance of cardiac and coronary microvascular function in sedentary mice lacking adiponectin; however, in the absence of adiponectin, cardiac and coronary microvascular adaptations to exercise training are compromised.NEW & NOTEWORTHY We report that compensatory mechanisms contribute to the maintenance of cardiac and coronary microvascular function in sedentary mice in which adiponectin has been deleted; however, when mice lacking adiponectin are subjected to the physiological stress of exercise training, beneficial coronary microvascular and cardiac adaptations are compromised or absent.

The Molecular Mechanisms of Cardiotoxicity Induced by HER2, VEGF, and Tyrosine Kinase Inhibitors: an Updated Review

AIM

In recent decades, there has been a revolutionary decrease in cancer-related mortality and an increase in survival due to the introduction of novel targeted drugs. Nevertheless, drugs targeting human epidermal growth factor receptor 2 (HER-2), angiogenesis, and other tyrosine kinases also come with unexpected cardiac side effects, including heart failure, hypertension, arterial thrombosis, and arrhythmias, and have mechanisms that are unlike those of classic chemotherapeutic agents. In addition, it is challenging to address some problems, as the existing guidelines need to be more specific, and further large-scale clinical trials and experimental studies are required to confirm the benefit of administering cardioprotective agents to patients treated with targeted therapies. Therefore, an improved understanding of cardiotoxicity becomes increasingly important to minimize the pernicious effects and maximize the beneficial effects of targeted agents.

METHODS

"Cardiotoxicity", "targeted drugs", "HER2", "trastuzumab", "angiogenesis inhibitor", "VEGF inhibitor" and "tyrosine kinase inhibitors" are used as keywords for article searches.

RESULTS

In this article, we report several targeted therapies that induce cardiotoxicity and update knowledge of the clinical evidence, molecular mechanisms, and management measures.

Skeletal Muscle in ALS: An Unappreciated Therapeutic Opportunity?

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder characterized by the selective degeneration of upper and lower motor neurons and by the progressive weakness and paralysis of voluntary muscles. Despite intense research efforts and numerous clinical trials, it is still an incurable disease. ALS had long been considered a pure motor neuron disease; however, recent studies have shown that motor neuron protection is not sufficient to prevent the course of the disease since the dismantlement of neuromuscular junctions occurs before motor neuron degeneration. Skeletal muscle alterations have been described in the early stages of the disease, and they seem to be mainly involved in the “dying back” phenomenon of motor neurons and metabolic dysfunctions. In recent years, skeletal muscles have been considered crucial not only for the etiology of ALS but also for its treatment. Here, we review clinical and preclinical studies that targeted skeletal muscles and discuss the different approaches, including pharmacological interventions, supplements or diets, genetic modifications, and training programs.

Targeting the Endothelium to Achieve Cardioprotection

Despite considerable improvements in the treatment of myocardial infarction, it is still a highly prevalent disease worldwide. Novel therapeutic strategies to limit infarct size are required to protect myocardial function and thus, avoid heart failure progression. Cardioprotection is a research topic with significant achievements in the context of basic science. However, translation of the beneficial effects of protective approaches from bench to bedside has proven difficult. Therefore, there is still an unmet need to study new avenues leading to protecting the myocardium against infarction. In line with this, the endothelium is an essential component of the cardiovascular system with multiple therapeutic targets with cardioprotective potential. Endothelial cells are the most abundant non-myocyte cell type in the heart and are key players in cardiovascular physiology and pathophysiology. These cells can regulate vascular tone, angiogenesis, hemostasis, and inflammation. Accordingly, endothelial dysfunction plays a fundamental role in cardiovascular diseases, which may ultimately lead to myocardial infarction. The endothelium is of paramount importance to protect the myocardium from ischemia/reperfusion injury via conditioning strategies or cardioprotective drugs. This review will provide updated information on the most promising therapeutic agents and protective approaches targeting endothelial cells in the context of myocardial infarction.

Exercise Regulates MicroRNAs to Preserve Coronary and Cardiac Function in the Diabetic Heart

RATIONALE

Diabetic heart disease (DHD) is a debilitating manifestation of type 2 diabetes mellitus. Exercise has been proposed as a potential therapy for DHD, although the effectiveness of exercise in preventing or reversing the progression of DHD remains controversial. Cardiac function is critically dependent on the preservation of coronary vascular function.

OBJECTIVE

We aimed to elucidate the effectiveness and mechanisms by which exercise facilitates coronary and cardiac-protection during the onset and progression of DHD.

METHODS AND RESULTS

Diabetic db/db and nondiabetic mice, with or without underlying cardiac dysfunction (16 and 8 weeks old, respectively) were subjected to either moderate-intensity exercise or high-intensity exercise for 8 weeks. Subsequently, synchrotron microangiography, immunohistochemistry, Western blot, and real-time polymerase chain reaction were used to assess time-dependent changes in cardiac and coronary structure and function associated with diabetes mellitus and exercise and determine whether these changes reflect the observed changes in cardiac-enriched and vascular-enriched microRNAs (miRNAs). We show that, if exercise is initiated from 8 weeks of age, both moderate-intensity exercise and high-intensity exercise prevented the onset of coronary and cardiac dysfunction, apoptosis, fibrosis, microvascular rarefaction, and disruption of miRNA signaling, as seen in the nonexercised diabetic mice. Conversely, the cardiovascular benefits of moderate-intensity exercise were absent if the exercise was initiated after the diabetic mice had already established cardiac dysfunction (ie, from 16 weeks of age). The experimental silencing or upregulation of miRNA-126 activity suggests the mechanism underpinning the cardiovascular benefits of exercise were mediated, at least in part, through tissue-specific miRNAs.

CONCLUSIONS

Our findings provide the first experimental evidence for the critical importance of early exercise intervention in ameliorating the onset and progression of DHD. Our results also suggest that the beneficial effects of exercise are mediated through the normalization of cardiovascular-enriched miRNAs, which are dysregulated in DHD.

Effects of aging on coronary flow reserve in patients with no evidence of myocardial perfusion abnormality

Coronary flow reserve (CFR) reflects the functional capacity of microcirculation to adapt to blood demand during increased cardiac work. We tested the hypothesis that aging had impacts on coronary flow velocities and CFR in patients with no evidence of myocardial perfusion abnormality on single photon emission computed tomography (SPECT). Seventy-six patients undergoing transthoracic Doppler echocardiography with no evidence of myocardial perfusion abnormality on SPECT were enrolled in this study. CFR was defined as the ratio of hyperemic to resting peak diastolic coronary flow velocity. Patients were divided into the three groups based on age: 17 patients aged less than 70 years (Group I), 38 patients aged 70-79 years (Group II), and 21 patients aged 80 years or more (Group III). Compared with Group I, CFR was significantly lower in Group II (p < 0.01) and Group III (p < 0.01). Multivariate linear regression analysis showed that female (β = - 0.26, p = 0.03), cigarette smoking (β = - 0.32, p = 0.004), hemoglobin level (β = - 0.40, p = 0.001) and LV mass index (β = 0.24, p = 0.03) were determinants for resting coronary flow velocity. On the other hand, age (β = -0.30, p = 0.008), hemoglobin level (β = -0.47, p < 0.001) and LV mass index (β = 0.24, p = 0.04) were determinants for hyperemic coronary flow velocity. Age was only determinant for CFR (β = -0.48, p < 0.001). Our data suggested that that aging had a decreased effect on hyperemic coronary flow velocity rather than resting coronary flow velocity, and was further associated with impaired CFR in patients with no evidence of myocardial perfusion abnormality.

Late-life voluntary wheel running reverses age-related aortic stiffness in mice: a translational model for studying mechanisms of exercise-mediated arterial de-stiffening

Aortic stiffening, assessed as pulse-wave velocity (PWV), increases with age and is an important antecedent to, and independent predictor of, cardiovascular diseases (CVD) and other clinical disorders of aging. Aerobic exercise promotes lower levels of aortic stiffness in older adults, but the underlying mechanisms are incompletely understood, largely due to inherent challenges of mechanistic studies of large elastic arteries in humans. Voluntary wheel running (VWR) is distinct among experimental animal exercise paradigms in that it allows investigation of the physiologic effects of aerobic training without potential confounding influences of aversive molecular signaling related to forced exercise. In this study, we investigated whether VWR in mice may be a suitable model for mechanistic studies (i.e., "reverse translation") of the beneficial effects of exercise on arterial stiffness in humans. We found that 10 weeks of VWR in old mice (~ 28 months) reversed age-related elevations in aortic PWV assessed in vivo (Old VWR: 369 ± 19 vs. old sedentary: 439 ± 20 cm/s, P < 0.05). The de-stiffening effects of VWR were accompanied by normalization of age-related increases in ex vivo mechanical stiffness of aortic segments and aortic accumulation of collagen-I and advanced glycation end products, as well as lower levels of aortic superoxide and nitrotyrosine. Our results suggest that late-life VWR in mice recapitulates the aortic de-stiffening effects of exercise in humans and indicates important mechanistic roles for decreased oxidative stress and extracellular matrix remodeling. Therefore, VWR is a suitable model for further study of the mechanisms underlying beneficial effects of exercise on arterial stiffness.

Potential Preventive Strategies for Amyotrophic Lateral Sclerosis

It may seem useless to propose preventive measures for a disease without established pathogenesis and successful therapy, such as amyotrophic lateral sclerosis (ALS). However, we will show that ALS shares essential molecular mechanisms with aging and that established anti-aging strategies, such as healthy diet or individually adjusted exercise, may be successfully applied to ameliorate the condition of ALS patients. These strategies might be applied for prevention if persons at ALS risk could be identified early enough. Recent research advances indicate that this may happen soon.

Vasodilatory function in human skeletal muscle feed arteries with advancing age: the role of adropin

KEY POINTS

The present study aimed to determine the impact of ageing on endogenous adropin levels in human skeletal muscle feed arteries (SMFAs) and the role of adropin in age-related vascular dysfunction. Adropin protein expression falls progressively with advancing age in the human peripheral vasculature. Endothelial-dependent vasodilatation, typically attenuated with age, was strongly correlated with SMFA adropin protein levels. Adropin incubation restored age-related endothelial-dependent vasodilatory dysfunction and increased the phosphorylated endothelial nitric oxide synthase (eNOS)/eNOS ratio in an age-dependent manner in the SMFAs. The role of nitric oxide bioavailability was additionally indicated by NOS blockade ablating both the positive vascular effects of adropin incubation and the relationship between endothelial function and adropin protein expression. Additional evidence of a mechanistic link between declining adropin and age-related endothelial dysfunction was documented by a progressively increasing magnitude of effect of adropin-induced eNOS-mediated vasodilatation with ageing. Adropin appears to be a novel therapeutic target for facilitating the restoration of endothelial function with ageing.

ABSTRACT

The present study aimed to determine the impact of advancing age on endogenous adropin levels in human skeletal muscle feed arteries (SMFAs) and the role of adropin in age-related vascular dysfunction. Adropin protein expression and vasodilatory capacity was assesed in SMFAs from Young (27 ± 2 years, n = 10), Middle Aged (54 ± 2 years, n = 10) and Old (75 ± 2 years, n = 16) subjects. Endothelial-dependent vasodilatation, with and without adropin incubation, was assessed in response to flow-induced shear stress and ACh. Both SMFA adropin protein expression and endothelial-dependent vasodilatory function exhibited a progressive, age-related, reduction (Flow: Y: 65 ± 3%; Middle Aged: 36 ± 3%; Old: 15 ± 2%; ACh: Young: 63 ± 2%, Middle Aged: 34 ± 3%; Old: 23 ± 3%, P < 0.05). There was a strong positive correlation between SMFA adropin protein expression and both flow (r = 0.81, P < 0.05) and ACh (r = 0.78, P < 0.05). Adropin incubation in the Middle Aged and Old SMFAs restored the vasodilatory response to flow (Middle Aged + Adropin: 59 ± 3%; Old + Adropin: 47 ± 3%, P < 0.05) and ACh (Middle Aged + Adropin: 59 ± 3%; Old + Adropin: 49 ± 2%, P < 0.05). A mechanistic link between adropin and nitric oxide (NO) biovavailabilty was supported by (i) increased phosphorylated endothelial NO synthase (eNOS)/eNOS protein expression with adropin incubation only in the Middle Aged and Old SMFAs; (ii) eNOS blockade ablating both the positive vascular effects of adropin incubation and the relationship between endothelial function and adropin protein expression and (iii) a progressive increase in the magnitude of effect of adropin-induced eNOS-mediated vasodilatation with advancing age. Adropin could be a novel therapeutic target for facilitating the restoration of endothelial function via increased NO bioavailability, with advancing age.

Physiological Consequences of Coronary Arteriolar Dysfunction and Its Influence on Cardiovascular Disease

To date, the major focus of diagnostic modalities and interventions to treat coronary artery disease has been the large epicardial vessels. Despite substantial data showing that microcirculatory dysfunction is a strong predictor of future adverse cardiovascular events, very little research has gone into developing techniques for in vivo diagnosis and therapeutic interventions to improve microcirculatory function. In this review, we will discuss the pathophysiology of coronary arteriolar dysfunction, define its prognostic implications, evaluate the diagnostic modalities available, and provide speculation on current and potential therapeutic opportunities.

Physical Activity, Immune System, and the Microbiome in Cardiovascular Disease

Cardiovascular health is a primary research focus, as it is a leading contributor to mortality and morbidity worldwide, and is prohibitively costly for healthcare. Atherosclerosis, the main driver of cardiovascular disease, is now recognized as an inflammatory disorder. Physical activity (PA) may have a more important role in cardiovascular health than previously expected. This review overviews the contribution of PA to cardiovascular health, the inflammatory role of atherosclerosis, and the emerging evidence of the microbiome as a regulator of inflammation.

Voluntary exercise training restores anticontractile effect of NO in coronary arteries of adult rats with antenatal/early postnatal hypothyroidism

INTRODUCTION

Our recent study showed that NO-mediated anticontractile effect of endothelium is absent in coronary arteries of adult rats, which suffered from antenatal/early postnatal hypothyroidism. This study tested the hypothesis that exercise training would improve such detrimental consequences of early thyroid deficiency.

DESIGN AND METHODS

Wistar dams received propylthiouracil (PTU, 7 ppm) in drinking water during gestation and two weeks postpartum; control dams received tap water. Six-week-old male offspring of control (CON) and PTU dams was divided into sedentary (CON-Sed, n = 12; PTU-Sed, n = 10) and trained (CON-Tr, n = 12; PTU-Tr, n = 10) groups; the latter had 24-h access to running wheels. Eight weeks later coronary arteries were studied by wire myography. Anticontractile effect of NO was assessed by the effects of NOS inhibitor L-NNA on the basal tone and contractile response to U46619. Oxidative phosphorylation complexes and eNOS were estimated by Western blotting.

RESULTS

T₃/T₄ and TSH levels (ELISA) were normalized in the progeny of PTU-treated dams at the age of 6 weeks and were not affected by training. Total running distance did not differ between CON-Tr and PTU-Tr. The contents of oxidative phosphorylation complexes were increased post-training in triceps brachii muscle from CON-Tr and PTU-Tr and in heart from PTU-Tr. Coronary arteries of PTU-Sed compared to CON-Sed demonstrated higher basal tone and contractile response to U46619, which were not further increased by L-NNA. The effects of L-NNA on the basal tone and contractile response to U46619 did not differ in CON-Tr and PTU-Tr groups, but were elevated in PTU-Tr compared to PTU-Sed group. PTU-Tr rats in comparison to PTU-Sed group had higher eNOS content in heart. Responses of coronary arteries to DEA/NO did not differ among all experimental groups.

CONCLUSIONS

Long-lasting coronary endothelial dysfunction resulted from transient thyroid deficiency during the antenatal/early postnatal period can be corrected by voluntary exercise training.

Effects of age and exercise training on coronary microvascular smooth muscle phenotype and function

Coronary microvascular function and blood flow responses during acute exercise are impaired in the aged heart but can be restored by exercise training. Coronary microvascular resistance is directly dependent on vascular smooth muscle function in coronary resistance arterioles; therefore, we hypothesized that age impairs contractile function and alters the phenotype of vascular smooth muscle in coronary arterioles. We further hypothesized that exercise training restores contractile function and reverses age-induced phenotypic alterations of arteriolar smooth muscle. Young and old Fischer 344 rats underwent 10 wk of treadmill exercise training or remained sedentary. At the end of training or cage confinement, contractile responses, vascular smooth muscle proliferation, and expression of contractile proteins were assessed in isolated coronary arterioles. Both receptor- and non-receptor-mediated contractile function were impaired in coronary arterioles from aged rats. Vascular smooth muscle shifted from a differentiated, contractile phenotype to a secretory phenotype with associated proliferation of smooth muscle in the arteriolar wall. Expression of smooth muscle myosin heavy chain 1 (SM1) was decreased in arterioles from aged rats, whereas expression of phospho-histone H3 and of the synthetic protein ribosomal protein S6 (rpS6) were increased. Exercise training improved contractile responses, reduced smooth muscle proliferation and expression of rpS6, and increased expression of SM1 in arterioles from old rats. Thus age-induced contractile dysfunction of coronary arterioles and emergence of a secretory smooth muscle phenotype may contribute to impaired coronary blood flow responses, but arteriolar contractile responsiveness and a younger smooth muscle phenotype can be restored with late-life exercise training. NEW & NOTEWORTHY Aging impairs contractile function of coronary arterioles and induces a shift of the vascular smooth muscle toward a proliferative, noncontractile phenotype. Late-life exercise training reverses contractile dysfunction of coronary arterioles and restores a young phenotype to the vascular smooth muscle.