Exercise does not activate the β3 adrenergic receptor–eNOS pathway, but reduces inducible NOS expression to protect the heart of obese diabetic mice

Hyperglycemia triggers RyR2-dependent alterations of mitochondrial calcium homeostasis in response to cardiac ischemia-reperfusion: Key role of DRP1 activation

Hyperglycemia increases the heart sensitivity to ischemia-reperfusion (IR), but the underlying cellular mechanisms remain unclear. Mitochondrial dynamics (the processes that govern mitochondrial morphology and their interactions with other organelles, such as the reticulum), has emerged as a key factor in the heart vulnerability to IR. However, it is unknown whether mitochondrial dynamics contributes to hyperglycemia deleterious effect during IR. We hypothesized that (i) the higher heart vulnerability to IR in hyperglycemic conditions could be explained by hyperglycemia effect on the complex interplay between mitochondrial dynamics, Ca2+ homeostasis, and reactive oxygen species (ROS) production; and (ii) the activation of DRP1, a key regulator of mitochondrial dynamics, could play a central role. Using transmission electron microscopy and proteomic analysis, we showed that the interactions between sarcoplasmic reticulum and mitochondria and mitochondrial fission were increased during IR in isolated rat hearts perfused with a hyperglycemic buffer compared with hearts perfused with a normoglycemic buffer. In isolated mitochondria and cardiomyocytes, hyperglycemia increased mitochondrial ROS production and Ca2+ uptake. This was associated with higher RyR2 instability. These results could contribute to explain the early mPTP activation in mitochondria from isolated hearts perfused with a hyperglycemic buffer and in hearts from streptozotocin-treated rats (to increase the blood glucose). DRP1 inhibition by Mdivi-1 during the hyperglycemic phase and before IR induction, normalized Ca2+ homeostasis, ROS production, mPTP activation, and reduced the heart sensitivity to IR in streptozotocin-treated rats. In conclusion, hyperglycemia-dependent DRP1 activation results in higher reticulum-mitochondria calcium exchange that contribute to the higher heart vulnerability to IR.

Is Intrinsic Cardioprotection a Laboratory Phenomenon or a Clinically Relevant Tool to Salvage the Failing Heart?

Cardiovascular diseases, especially ischemic heart disease, as a leading cause of heart failure (HF) and mortality, will not reduce over the coming decades despite the progress in pharmacotherapy, interventional cardiology, and surgery. Although patients surviving acute myocardial infarction live longer, alteration of heart function will later lead to HF. Its rising incidence represents a danger, especially among the elderly, with data showing more unfavorable results among females than among males. Experiments revealed an infarct-sparing effect of ischemic "preconditioning" (IPC) as the most robust form of innate cardioprotection based on the heart's adaptation to moderate stress, increasing its resistance to severe insults. However, translation to clinical practice is limited by technical requirements and limited time. Novel forms of adaptive interventions, such as "remote" IPC, have already been applied in patients, albeit with different effectiveness. Cardiac ischemic tolerance can also be increased by other noninvasive approaches, such as adaptation to hypoxia- or exercise-induced preconditioning. Although their molecular mechanisms are not yet fully understood, some noninvasive modalities appear to be promising novel strategies for fighting HF through targeting its numerous mechanisms. In this review, we will discuss the molecular mechanisms of heart injury and repair, as well as interventions that have potential to be used in the treatment of patients.

Determination of progressive stages of type 2 diabetes in a 45% high-fat diet-fed C57BL/6J mouse model is achieved by utilizing both fasting blood glucose levels and a 2-hour oral glucose tolerance test

Type 2 diabetes is considered one of the top ten life-threatening diseases worldwide. Following economic growth, obesity and metabolic syndrome became the most common risk factor for type 2 diabetes. In this regard, high-fat diet-fed C57BL/6J mouse model is widely used for type 2 diabetes pathogenesis and novel therapeutics development. However, criteria for classifying type 2 diabetes progressive stages in this mouse model are yet to be determined, led to the difficulty in experimental end-point decision. In this study, we fed C57BL/6J male mice with 45% high-fat diet, which is physiologically close to human high-fat consumption, and evaluated the progression of type 2 diabetes. After consuming high-fat diet for 4 weeks, mice developed metabolic syndrome, including obesity, significant increase of fasting plasma cholesterol level, elevation of both C-peptide and fasting blood glucose levels. By combining both fasting blood glucose test and 2-hour-oral glucose tolerance test, our results illustrated clear progressive stages from metabolic syndrome into pre-diabetes before onset of type 2 diabetes in C57BL/6J mice given a 45% high-fat diet. Besides, among metabolic measurements, accumulating body weight gain > 16.23 g for 12 weeks could be utilized as a potential parameter to predict type 2 diabetes development in C57BL/6J mice. Thus, these results might support future investigations in term of selecting appropriate disease stage in high-fat diet-fed C57BL/6J mouse model for studying early prevention and treatment of type 2 diabetes.

Co-administration of exercise training and melatonin on the function of diabetic heart tissue: a systematic review and meta-analysis of rodent models

PURPOSE

Diabetes mellitus (DM), a hyperglycemic condition, occurs due to the failure of insulin secretion and resistance. This study investigated the combined effects of exercise training and melatonin (Mel) on the function of heart tissue in diabetic rodent models.

METHODS

A systematic search was conducted in Embase, ProQuest, Cochrane library, Clinicaltrial.gov, WHO, Google Scholar, PubMed, Ovid, Scopus, Web of Science, Ongoing Trials Registers, and Conference Proceedings in July 2022 with no limit of date or language. All trials associated with the effect of Mel and exercise in diabetic rodent models were included. Of the 962 relevant publications, 58 studies met our inclusion criteria as follows; Mel and type 1 DM (16 studies), Mel and type 2 DM (6 studies), exercise and type 1 DM (24 studies), and exercise and type 2 DM (12 studies). Meta-analysis of the data was done using the Mantel Haenszel method.

RESULTS

In most of these studies, antioxidant status and oxidative stress, inflammatory response, apoptosis rate, lipid profiles, and glucose levels were monitored in diabetic heart tissue. According to our findings, both Mel and exercise can improve antioxidant capacity by activating antioxidant enzymes compared to the control diabetic groups (p < 0.05). The levels of pro-inflammatory cytokines, especially TNF-α were reduced in diabetic rodents after being treated with Mel and exercise. Apoptotic changes were diminished in diabetic rodents subjected to the Mel regime and exercise in which p53 levels and the activity of Caspases reached near normal levels (p < 0.05). Based on the data, both Mel and exercise can change the lipid profile in diabetic rodents, especially rats, and close it to near-to-control levels.

CONCLUSION

These data showed that exercise and Mel can reduce the harmful effects of diabetic conditions on the heart through the regulation of lipid profile, antioxidant capacity, apoptosis, and inflammation.

Moderate-Intensity Exercise Maintains Redox Homeostasis for Cardiovascular Health

It is well known that exercise is beneficial for cardiovascular health. Oxidative stress is the common pathological basis of many cardiovascular diseases. The overproduction of free radicals, both reactive oxygen species and reactive nitrogen species, can lead to redox imbalance and exacerbate oxidative damage to the cardiovascular system. Maintaining redox homeostasis and enhancing anti-oxidative capacity are critical mechanisms by which exercise protects against cardiovascular diseases. Moderate-intensity exercise is an effective means to maintain cardiovascular redox homeostasis. Moderate-intensity exercise reduces the risk of cardiovascular disease by improving mitochondrial function and anti-oxidative capacity. It also attenuates adverse cardiac remodeling and enhances cardiac function. This paper reviews the primary mechanisms of moderate-intensity exercise-mediated redox homeostasis in the cardiovascular system. Exploring the role of exercise-mediated redox homeostasis in the cardiovascular system is of great significance to the prevention and treatment of cardiovascular diseases.

Beyond cardiomyocytes: Cellular diversity in the heart's response to exercise

Cardiomyocytes comprise ∼70% to 85% of the total volume of the adult mammalian heart but only about 25% to 35% of its total number of cells. Advances in single cell and single nuclei RNA sequencing have greatly facilitated investigation into and increased appreciation of the potential functions of non-cardiomyocytes in the heart. While much of this work has focused on the relationship between non-cardiomyocytes, disease, and the heart's response to pathological stress, it will also be important to understand the roles that these cells play in the healthy heart, cardiac homeostasis, and the response to physiological stress such as exercise. The present review summarizes recent research highlighting dynamic changes in non-cardiomyocytes in response to the physiological stress of exercise. Of particular interest are changes in fibrotic pathways, the cardiac vasculature, and immune or inflammatory cells. In many instances, limited data are available about how specific lineages change in response to exercise or whether the changes observed are functionally important, underscoring the need for further research.

Exercise training after myocardial infarction increases survival but does not prevent adverse left ventricle remodeling and dysfunction in high-fat diet fed mice

AIMS

Aerobic exercise is an important component of rehabilitation after cardiovascular injuries including myocardial infarction (MI). In human studies, the beneficial effects of exercise after an MI are blunted in patients who are obese or glucose intolerant. Here, we investigated the effects of exercise on MI-induced cardiac dysfunction and remodeling in mice chronically fed a high-fat diet (HFD).

MAIN METHODS

C57Bl/6 male mice were fed either a standard (Chow; 21% kcal/fat) or HFD (60% kcal/fat) for 36 weeks. After 24 weeks of diet, the HFD mice were randomly subjected to an MI (MI) or a sham surgery (Sham). Following the MI or sham surgery, a subset of mice were subjected to treadmill exercise.

KEY FINDINGS

HFD resulted in obesity and glucose intolerance, and this was not altered by exercise or MI. MI resulted in decreased ejection fraction, increased left ventricle mass, increased end systolic and diastolic diameters, increased cardiac fibrosis, and increased expression of genes involved in cardiac hypertrophy and heart failure in the MI-Sed and MI-Exe mice. Exercise prevented HFD-induced cardiac fibrosis in Sham mice (Sham-Exe) but not in MI-Exe mice. Exercise did, however, reduce post-MI mortality.

SIGNIFICANCE

These data indicate that exercise significantly increased survival after MI in a model of diet-induced obesity independent of effects on cardiac function. These data have important translational ramifications because they demonstrate that environmental interventions, including diet, need to be carefully evaluated and taken into consideration to support the effects of exercise in the cardiac rehabilitation of patients who are obese.

Increased protein S-nitrosylation in mitochondria: a key mechanism of exercise-induced cardioprotection

Endothelial nitric oxide synthase (eNOS) activation in the heart plays a key role in exercise-induced cardioprotection during ischemia-reperfusion, but the underlying mechanisms remain unknown. We hypothesized that the cardioprotective effect of exercise training could be explained by the re-localization of eNOS-dependent nitric oxide (NO)/S-nitrosylation signaling to mitochondria. By comparing exercised (5 days/week for 5 weeks) and sedentary Wistar rats, we found that exercise training increased eNOS level and activation by phosphorylation (at serine 1177) in mitochondria, but not in the cytosolic subfraction of cardiomyocytes. Using confocal microscopy, we confirmed that NO production in mitochondria was increased in response to H₂O₂ exposure in cardiomyocytes from exercised but not sedentary rats. Moreover, by S-nitrosoproteomic analysis, we identified several key S-nitrosylated proteins involved in mitochondrial function and cardioprotection. In agreement, we also observed that the increase in Ca²⁺ retention capacity by mitochondria isolated from the heart of exercised rats was abolished by exposure to the NOS inhibitor L-NAME or to the reducing agent ascorbate, known to denitrosylate proteins. Pre-incubation with ascorbate or L-NAME also increased mitochondrial reactive oxygen species production in cardiomyocytes from exercised but not from sedentary animals. We confirmed these results using isolated hearts perfused with L-NAME before ischemia-reperfusion. Altogether, these results strongly support the hypothesis that exercise training increases eNOS/NO/S-nitrosylation signaling in mitochondria, which might represent a key mechanism of exercise-induced cardioprotection.

Nitrosative Stress and Human Disease: Therapeutic Potential of Denitrosylation

Proteins dynamically contribute towards maintaining cellular homeostasis. Posttranslational modification regulates the function of target proteins through their immediate activation, sudden inhibition, or permanent degradation. Among numerous protein modifications, protein nitrosation and its functional relevance have emerged. Nitrosation generally initiates nitric oxide (NO) production in association with NO synthase. NO is conjugated to free thiol in the cysteine side chain (S-nitrosylation) and is propagated via the transnitrosylation mechanism. S-nitrosylation is a signaling pathway frequently involved in physiologic regulation. NO forms peroxynitrite in excessive oxidation conditions and induces tyrosine nitration, which is quite stable and is considered irreversible. Two main reducing systems are attributed to denitrosylation: glutathione and thioredoxin (TRX). Glutathione captures NO from S-nitrosylated protein and forms S-nitrosoglutathione (GSNO). The intracellular reducing system catalyzes GSNO into GSH again. TRX can remove NO-like glutathione and break down the disulfide bridge. Although NO is usually beneficial in the basal context, cumulative stress from chronic inflammation or oxidative insult produces a large amount of NO, which induces atypical protein nitrosation. Herein, we (1) provide a brief introduction to the nitrosation and denitrosylation processes, (2) discuss nitrosation-associated human diseases, and (3) discuss a possible denitrosylation strategy and its therapeutic applications.

Digestive n-6 Lipid Oxidation, a Key Trigger of Vascular Dysfunction and Atherosclerosis in the Western Diet: Protective Effects of Apple Polyphenols

SCOPE

A main risk factor of atherosclerosis is a Western diet (WD) rich in n-6 polyunsaturated fatty acids (PUFAs) sensitive to oxidation. Their oxidation can be initiated by heme iron of red meat leading to the formation of 4-hydroxy-2-nonenal (4-HNE), a cytotoxic aldehyde. An increased 4-HNE production is implicated in endothelial dysfunction and atherosclerosis. By contrast, a diet rich in proanthocyanidins reduces oxidative stress and arterial diseases. This study evaluates the effects of a WD on vascular integrity in ApolipoproteinE (ApoE-/- ) mice and the protective capacity of apple extract and puree rich in antioxidant proanthocyanidins.

METHODS AND RESULTS

ApoE-/- mice are fed during 12 weeks with a WD with or without n-6 PUFAs. Moreover, two WD + n-6 PUFAs groups are supplemented with apple puree or phenolic extract. An increase in digestive 4-HNE production associated with a rise in plasmatic 4-HNE and oxidized LDL concentrations is reported. Oxidizable n-6 PUFAs consumption is associated with a worsened endothelial dysfunction and atherosclerosis. Interestingly, supplementations with apple polyphenol extract or puree prevented these impairments while reducing oxidative stress.

CONCLUSION

n-6 lipid oxidation during digestion may be a key factor of vascular impairments. Nevertheless, an antioxidant strategy can limit 4-HNE formation during digestion and thus durably protect vascular function.

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.

Diet-induced rodent models of obesity-related metabolic disorders-A guide to a translational perspective

Diet is a critical element determining human health and diseases, and unbalanced food habits are major risk factors for the development of obesity and related metabolic disorders. Despite technological and pharmacological advances, as well as intensification of awareness campaigns, the prevalence of metabolic disorders worldwide is still increasing. Thus, novel therapeutic approaches with increased efficacy are urgently required, which often depends on cellular and molecular investigations using robust animal models. In the absence of perfect rodent models, those induced by excessive consumption of fat and sugars better replicate the key aspects that are the root causes of human metabolic diseases. However, the results obtained using these models cannot be directly compared, particularly because of the use of different dietary protocols, and animal species and strains, among other confounding factors. This review article revisits diet-induced models of obesity and related metabolic disorders, namely, metabolic syndrome, prediabetes, diabetes and nonalcoholic fatty liver disease. A critical analysis focused on the main pathophysiological features of rodent models, as opposed to the criteria defined for humans, is provided as a practical guide with a translational perspective for the establishment of animal models of obesity-related metabolic diseases.

Expression and Signaling of β-Adrenoceptor Subtypes in the Diabetic Heart

Diabetes is a chronic, endocrine disorder that effects millions of people worldwide. Cardiovascular complications are the major cause of diabetes-related morbidity and mortality. Cardiac β₁- and β₂-adrenoceptor (AR) stimulation mediates positive inotropy and chronotropy, whereas β₃-AR mediates negative inotropic effect. Changes in β-AR responsiveness are thought to be an important factor that contributes to the diabetic cardiac dysfunction. Diabetes related changes in β-AR expression, signaling, and β-AR mediated cardiac function have been studied by several investigators for many years. In the present review, we have screened PubMed database to obtain relevant articles on this topic. Our search has ended up with wide range of different findings about the effect of diabetes on β-AR mediated changes both in molecular and functional level. Considering these inconsistent findings, the effect of diabetes on cardiac β-AR still remains to be clarified.

Aerobic exercise training regulates serum extracellular vesicle miRNAs linked to obesity to promote their beneficial effects in mice

There is a growing body of evidence that extracellular vesicles (EVs) and their cargo of RNA, DNA, and protein are released in the circulation with exercise and might mediate interorgan communication. C57BL6/J male mice were subjected to diet-induced obesity and aerobic training on a treadmill for 8 wk. The effect of aerobic training was evaluated in the liver, muscle, kidney, and white/brown adipose tissue. To provide new mechanistic insight, we profiled miRNA from serum EVs of obese and obese trained mice. We demonstrate that aerobic training changes the circulating EV miRNA profile of obese mice, including decreases in miR-122, miR-192, and miR-22 levels. Circulating miRNA levels were associated with miRNA levels in mouse liver white adipose tissue (WAT). In WAT, aerobically trained obese mice showed reduced adipocyte hypertrophy and increased the number of smaller adipocytes and the expression of Cebpa, Pparg, Fabp4 (adipogenesis markers), and ATP-citrate lyase enzyme activity. Importantly, miR-22 levels negatively correlated with the expression of adipogenesis and insulin sensitivity markers. In the liver, aerobic training reverted obesity-induced steatohepatitis, and steatosis score and Pparg expression were negatively correlated with miR-122 levels. The prometabolic effects of aerobic exercise in obesity possibly involve EV miRNAs, which might be involved in communication between liver and WAT. Our data provide significant evidence demonstrating that aerobic training exercise-induced EVs mediate the effect of exercise on adipose tissue metabolism.

Exercise training protects the heart against ischemia-reperfusion injury: A central role for mitochondria?

Ischemic heart disease is one of the main causes of morbidity and mortality worldwide. Physical exercise is an effective lifestyle intervention to reduce the risk factors for cardiovascular disease and also to improve cardiac function and survival in patients with ischemic heart disease. Among the strategies that contribute to reduce heart damages during ischemia and reperfusion, regular physical exercise is efficient both in rodent experimental models and in humans. However, the cellular and molecular mechanisms of the cardioprotective effects of exercise remain unclear. During ischemia and reperfusion, mitochondria are crucial players in cell death, but also in cell survival. Although exercise training can influence mitochondrial function, the consequences on heart sensitivity to ischemic insults remain elusive. In this review, we describe the effects of physical activity on cardiac mitochondria and their potential key role in exercise-induced cardioprotection against ischemia-reperfusion damage. Based on recent scientific data, we discuss the role of different pathways that might help to explain why mitochondria are a key target of exercise-induced cardioprotection.

β3-Adrenergic receptor blockade reduces mortality in endotoxin-induced heart failure by suppressing induced nitric oxide synthase and saving cardiac metabolism

The β₃-adrenergic receptor (β₃AR) is related to myocardial fatty acid metabolism and its expression has been implicated in heart failure. In this study, we investigated the role of β₃AR in sepsis-related myocardial dysfunction using lipopolysaccharide (LPS)-induced endotoxemia as a model of cardiac dysfunction. We placed mice into three treatment groups and treated each with intraperitoneal injections of the β₃AR agonist CL316243 (CL group), the β₃AR antagonist SR59230A (SR group), or normal saline (NS group). Survival rates were significantly improved in the SR group compared with the other treatment groups. Echocardiography analyses revealed cardiac dysfunction within 6-12 h of LPS injections, but the outcome was significantly better for the SR group. Myocardial ATP was preserved in the SR group but was decreased in the CL-treated mice. Additionally, quantitative PCR analysis revealed that expression levels of genes associated with fatty acid oxidation and glucose metabolism were significantly higher in the SR group. Furthermore, the expression levels of mitochondrial membrane protein complexes were preserved in the SR group. Electron microscope studies showed significant accumulation of lipid droplets in the CL group. Moreover, inducible nitric oxide synthase (iNOS) protein expression and nitric oxide were significantly reduced in the SR group. The in vitro study demonstrated that β₃AR has an independent iNOS pathway that does not go through the nuclear factor-κB pathway. These results suggest that blockading β₃AR improves impaired energy metabolism in myocardial tissues by suppressing iNOS expression and recovers cardiac function in animals with endotoxin-induced heart failure.NEW & NOTEWORTHY Nitric oxide production through stimulation of β₃-adrenergic receptor (β₃AR) may improve cardiac function in cases of chronic heart failure. We demonstrated that the blockade of β₃AR improved mortality and cardiac function in endotoxin-induced heart failure. We also determined that LPS-induced inducible nitric oxide synthase has a pathway that is independent of nuclear factor-κB, which worsened cardiac metabolism and mortality in the acute phase of sepsis. Treatment with the β₃AR antagonist had a favorable effect. Thus, the blockade of β₃AR could offer a novel treatment for sepsis-related heart failure.

Exercise training restores eNOS activation in the perivascular adipose tissue of obese rats: Impact on vascular function

OBJECTIVE

This study evaluated in obese rats the effect of exercise training on eNOS expressed in perivascular adipose tissue (PVAT) and its consequences on vascular function.

METHODS

Wistar rats were divided in 3 groups: control (standard diet), obese (high fat/high sucrose diet, HFS for 15 weeks), and exercised obese (HFS diet and exercise from week 6 to week 15, HFS-Ex) rats. The eNOS-adiponectin pathway and reactive oxygen species (ROS) were evaluated. Vascular reactivity was assessed on isolated aortic rings with or without PVAT and/or endothelium and exposed or not to the conditioned media of PVAT.

RESULTS

Obesity reduced eNOS level and phosphorylation on its activation site in the PVAT and had no impact on the vascular wall. Exercise training was able to increase eNOS and P-eNOS both in the vascular wall and in the PVAT. Interestingly, this was associated with increased level of adiponectin in the PVAT and to lower ROS in the vascular wall. Finally, PVAT of HFS-Ex aorta has eNOS-dependent anticontractile effects on endothelium denuded aortic rings and has beneficial effects on the endothelium-dependent vasorelaxation to ACh.

CONCLUSION

Exercise training in obese rats is able to impact PVAT eNOS with subsequent beneficial impact on vascular function.

Acidic preconditioning of endothelial colony-forming cells (ECFC) promote vasculogenesis under proinflammatory and high glucose conditions in vitro and in vivo

Background

We have previously demonstrated that acidic preconditioning of human endothelial colony-forming cells (ECFC) increased proliferation, migration, and tubulogenesis in vitro, and increased their regenerative potential in a murine model of hind limb ischemia without baseline disease. We now analyze whether this strategy is also effective under adverse conditions for vasculogenesis, such as the presence of ischemia-related toxic molecules or diabetes, one of the main target diseases for cell therapy due to their well-known healing impairments.

Methods

Cord blood-derived CD34⁺ cells were seeded in endothelial growth culture medium (EGM2) and ECFC colonies were obtained after 14–21 days. ECFC were exposed at pH 6.6 (preconditioned) or pH 7.4 (nonpreconditioned) for 6 h, and then pH was restored at 7.4. A model of type 2 diabetes induced by a high-fat and high-sucrose diet was developed in nude mice and hind limb ischemia was induced in these animals by femoral artery ligation. A P value < 0.05 was considered statistically significant (by one-way analysis of variance).

Results

We found that acidic preconditioning increased ECFC adhesion and the release of pro-angiogenic molecules, and protected ECFC from the cytotoxic effects of monosodium urate crystals, histones, and tumor necrosis factor (TNF)α, which induced necrosis, pyroptosis, and apoptosis, respectively. Noncytotoxic concentrations of high glucose, TNFα, or their combination reduced ECFC proliferation, stromal cell-derived factor (SDF)1-driven migration, and tubule formation on a basement membrane matrix, whereas almost no inhibition was observed in preconditioned ECFC. In type 2 diabetic mice, intravenous administration of preconditioned ECFC significantly induced blood flow recovery at the ischemic limb as measured by Doppler, compared with the phosphate-buffered saline (PBS) and nonpreconditioned ECFC groups. Moreover, the histologic analysis of gastrocnemius muscles showed an increased vascular density and reduced signs of inflammation in the animals receiving preconditioned ECFC.

Conclusions

Acidic preconditioning improved ECFC survival and angiogenic activity in the presence of proinflammatory and damage signals present in the ischemic milieu, even under high glucose conditions, and increased their therapeutic potential for postischemia tissue regeneration in a murine model of type 2 diabetes. Collectively, our data suggest that acidic preconditioning of ECFC is a simple and inexpensive strategy to improve the effectiveness of cell transplantation in diabetes, where tissue repair is highly compromised.

Electronic supplementary material

The online version of this article (10.1186/s13287-018-0872-7) contains supplementary material, which is available to authorized users.

Energy restriction, exercise and atorvastatin treatment improve endothelial dysfunction and inhibit miRNA-155 in the erectile tissue of the aged rat

Background

Endothelial dysfunction underlies cardiovascular disease that frequently affects aged individuals. Characterized by local decrease in nitric oxide, it results from down-regulation of endothelial nitric oxide synthase (eNOS) expression/activity. Aiming to elucidate the molecular mechanisms involved in age-related endothelial dysfunction and to unveil potential therapeutic targets, we tested how diet pattern, exercise and atorvastatin modulate the expression of eNOS, inducible NOS (iNOS), endothelin-1, sirtuins (SIRT) and microRNA-155 in the erectile tissue of high-fat fed aged rats.

Methods

Sprague-Dawley male rats fed with high-fat diet until they completed 12 months were grouped and subjected to energy restriction (ER), ER and atorvastatin, or, ER, atorvastatin and physical exercise. Controls were fed with standard rodent chow. The blood pressure was measured using the tail-cuff method before sacrifice at 18 months. Glucose, total cholesterol, HDL, triglyceride and CRP were assessed in blood and eNOS, endothelin-1, iNOS and sirtuins were detected by immunofluorescence in the penis sections; eNOS, endothelin-1, iNOS, SIRT2-4 and SIRT6-7 were semi-quantified by western blotting in tissue homogenates. MicroRNA-155 was quantified using RT-PCR in formalin-fixed paraffin embedded sections. To compare the studied variables, two-tail student t test was used.

Results

Atorvastatin promotes eNOS expression and is more efficient than ER or exercise in the control of hyperlipidemia and inflammation. Among the studied sirtuins, detected for the first time in the erectile tissue of the aged rat, SIRT2 aligns with eNOS expression. Both proteins exhibit over-expression in animals with combined exercise, atorvastatin and ER. Analysis of microRNA-155 expression also suggests its intervention in the regulation of eNOS expression. ER, particularly when combined with atorvastatin, was able to reverse the increase of iNOS and endothelin-1 in high-fat fed rats.

Conclusions

The present results indicate that the association of ER, atorvastatin and exercise is more efficient than isolated interventions in the prevention of endothelial dysfunction.

Treadmill exercise alleviates diabetic cardiomyopathy by suppressing plasminogen activator inhibitor expression and enhancing eNOS in streptozotocin-induced male diabetic rats

OBJECTIVE

To investigate the biological mechanism of the effect of different intensity exercises on diabetic cardiomyopathy.

METHODS

87 raise specific pathogen SPF healthy 6-week-old male Sprague-Dawley rats, fed 6 weeks with high-fat diet for rats were used, and a diabetic model was established by intraperitoneal injection of streptozotocin - randomly selected 43 rats were divided into Diabetic control group (DCG, n = 10), Diabetic exercise group 1 (DEG1, n = 11), Diabetic exercise group 2 (DEG2, n = 11) and Diabetic exercise group 3 (DEG3, n = 11). The rats in DEG1 were forced to run on a motorized treadmill, the exercise load consisted of running at a speed of 10 m/min, the exercise load of the rats in DEG2 were running at a speed of 15 m/min, the exercise load of the rats in DEG3 were running at a speed of 20 m/min, for one hour once a day for 6 weeks. After 6 weeks of exercise intervention, glucose metabolism-related indexes in rats such as blood glucose (FBG), glycosylated serum protein (GSP) and insulin (FINS); cardiac fibrinolytic system parameters such as PAI-1 (plasminogen activator inhibitor 1), Von Willebrand factor (vWF), protein kinase C (PKC) and diacylglycerol (DAG); and serum level of NO, eNOS and T-NOS were measured.

RESULT

Compared with DCG, fasting blood glucose and GSP were decreased, while insulin sensitivity index and insulin level were increased in all rats of the three exercise groups. FBG decrease was statistically significant (P < 0.01), only GSP decrease was statistically significant (P < 0.05) in DEG1 and DEG2, PAI-1 in three exercise groups were significantly reduced (P < 0.05), plasma vWF levels in the three exercise groups were significantly lower than those in the DCG group (P < 0.01); PKC levels decreased dramatically in the three exercise groups and DAG levels decrease slightly (P < 0.05), but with no significant difference. Compared with DCG, the serum level of NO was significantly higher (P < 0.05), and eNOS level was significantly elevated (P < 0.05). T-NOS elevation was statistically significant in DEG1 (P < 0.05).

CONCLUSIONS

Low- and moderate-intensity exercise can better control blood glucose level in diabetic rats; myocardial PAI-1 in DEG1, DEG2 and DEG3 rats decreased significantly (P < 0.05), serum NO increased (P < 0.05) and eNOS increased (P < 0.05) significantly. Therefore, it is inferred that exercise improves the biological mechanism of diabetic cardiomyopathy by affecting the levels of PAI-1 and eNOS, and there is a dependence on intensity.

AMPK-dependent nitric oxide release provides contractile support during hyperosmotic stress

In different pathological situations, cardiac cells undergo hyperosmotic stress (HS) and cell shrinkage. This change in cellular volume has been associated with contractile dysfunction and cell death. Given that nitric oxide (NO) is a well-recognized modulator of cardiac contractility and cell survival, we evaluated whether HS increases NO production and its impact on the negative inotropic effect observed during this type of stress. Superfusing cardiac myocytes with a hypertonic solution (HS: 440 mOsm) decreased cell volume and increased NO-sensitive DAF-FM fluorescence compared with myocytes superfused with an isotonic solution (IS: 309 mOsm). When cells were exposed to HS in addition to different inhibitors: L-NAME (NO synthase inhibitor), nitroguanidine (nNOS inhibitor), and Wortmannin (eNOS inhibitor) cell shrinkage occurred in the absence of NO release, suggesting that HS activates nNOS and eNOS. Consistently, western blot analysis demonstrated that maintaining cardiac myocytes in HS promotes phosphorylation and thus, activation of nNOS and eNOS compared to myocytes maintained in IS. HS-induced nNOS and eNOS activation and NO production were also prevented by AMPK inhibition with Dorsomorphin (DORSO). In addition, the HS-induced negative inotropic effect was exacerbated in the presence of either L-NAME, DORSO, ODQ (guanylate cyclase inhibitor), or KT5823 (PKG inhibitor), suggesting that NO provides contractile support via a cGMP/PKG-dependent mechanism. Our findings suggest a novel mechanism of AMPK-dependent NO release in cardiac myocytes with putative pathophysiological relevance determined, at least in part, by its capability to reduce the extent of contractile dysfunction associated with hyperosmotic stress.

Myocyte membrane and microdomain modifications in diabetes: determinants of ischemic tolerance and cardioprotection

Cardiovascular disease, predominantly ischemic heart disease (IHD), is the leading cause of death in diabetes mellitus (DM). In addition to eliciting cardiomyopathy, DM induces a ‘wicked triumvirate’: (i) increasing the risk and incidence of IHD and myocardial ischemia; (ii) decreasing myocardial tolerance to ischemia–reperfusion (I–R) injury; and (iii) inhibiting or eliminating responses to cardioprotective stimuli. Changes in ischemic tolerance and cardioprotective signaling may contribute to substantially higher mortality and morbidity following ischemic insult in DM patients. Among the diverse mechanisms implicated in diabetic impairment of ischemic tolerance and cardioprotection, changes in sarcolemmal makeup may play an overarching role and are considered in detail in the current review. Observations predominantly in animal models reveal DM-dependent changes in membrane lipid composition (cholesterol and triglyceride accumulation, fatty acid saturation vs. reduced desaturation, phospholipid remodeling) that contribute to modulation of caveolar domains, gap junctions and T-tubules. These modifications influence sarcolemmal biophysical properties, receptor and phospholipid signaling, ion channel and transporter functions, contributing to contractile and electrophysiological dysfunction, cardiomyopathy, ischemic intolerance and suppression of protective signaling. A better understanding of these sarcolemmal abnormalities in types I and II DM (T1DM, T2DM) can inform approaches to limiting cardiomyopathy, associated IHD and their consequences. Key knowledge gaps include details of sarcolemmal changes in models of T2DM, temporal patterns of lipid, microdomain and T-tubule changes during disease development, and the precise impacts of these diverse sarcolemmal modifications. Importantly, exercise, dietary, pharmacological and gene approaches have potential for improving sarcolemmal makeup, and thus myocyte function and stress-resistance in this ubiquitous metabolic disorder.

Cardiovascular Benefits of Moderate Exercise Training in Marfan Syndrome: Insights From an Animal Model

BACKGROUND

Marfan syndrome (MF) leads to aortic root dilatation and a predisposition to aortic dissection, mitral valve prolapse, and primary and secondary cardiomyopathy. Overall, regular physical exercise is recommended for a healthy lifestyle, but dynamic sports are strongly discouraged in MF patients. Nonetheless, evidence supporting this recommendation is lacking. Therefore, we studied the role of long-term dynamic exercise of moderate intensity on the MF cardiovascular phenotype.

METHODS AND RESULTS

In a transgenic mouse model of MF (Fbn1^C1039G/+), 4-month-old wild-type and MF mice were subjected to training on a treadmill for 5 months; sedentary littermates served as controls for each group. Aortic and cardiac remodeling was assessed by echocardiography and histology. The 4-month-old MF mice showed aortic root dilatation, elastic lamina rupture, and tunica media fibrosis, as well as cardiac hypertrophy, left ventricular fibrosis, and intramyocardial vessel remodeling. Over the 5-month experimental period, aortic root dilation rate was significantly greater in the sedentary MF group, compared with the wild-type group (∆mm, 0.27±0.07 versus 0.13±0.02, respectively). Exercise significantly blunted the aortic root dilation rate in MF mice compared with sedentary MF littermates (∆mm, 0.10±0.04 versus 0.27±0.07, respectively). However, these 2 groups were indistinguishable by aortic root stiffness, tunica media fibrosis, and elastic lamina ruptures. In MF mice, exercise also produced cardiac hypertrophy regression without changes in left ventricular fibrosis.

CONCLUSIONS

Our results in a transgenic mouse model of MF indicate that moderate dynamic exercise mitigates the progression of the MF cardiovascular phenotype.

Coronary angiogenic effect of long-term administration of Nigella sativa

Background

Coronary angiogenesis is one of the preferable adaptive responses of aerobic training. Previous studies found inotropic and hypertrophic cardiac effects for long-term administration of Nigella sativa (NS), but no studies have explored its coronary angiogenic effect. The present study compared the effect of long-term NS- administration and exercise training on the induction of coronary angiogenesis.

Method

Fifteen adult male Wistar rats were divided into three groups: control, NS-fed, and exercise-trained (Ex). The NS-fed rats were administered 800 mg/Kg NS orally for eight weeks. The (Ex) rats were trained on a five-lane treadmill at a speed of 18 m/min and a grade of 32° for two hour/day for eight weeks. After the experiment, the hearts were extracted and immunohistological slides were prepared using rat vascular endothelial growth factor (VEGF), platelet endothelial cell adhesion molecule-1 (PECAM-1), Von Willebrand factor (VWF) and nitric oxide synthase-2 (NOS-2) antibodies (Ab). Photomicrographs were analysed using ImageJ software, and the % of the immunostained-area of 10 fields per specimen was recorded.

Result

VEGF was significantly higher in the NS- (2.59±1.37%) and Ex rats (2.51±1.86%) compared to the control group (1.58±0.78%) with P<0.01. The VWF was significantly lower in the two experimental groups (1.57±0.83%, 1.07±0.72%) for NS and Ex groups respectively, compared to the controls (2.38±1.72) with p<0.01. Only Ex group had a higher PECAM-1 (1.79±0.78%) and lower NOS-2 (0.83±0.57%) than the control group (1.19±1.17%, 1.25±1.19%) for PECAM-1 and NOS-2 with P<0.01 and P<0.05 respectively.

Conclusions

The present study demonstrated an increase in VEGF and a decrease of the VWF in the hearts of Nigella-fed and exercise-trained rats. This might indicate the potentiality for induction of coronary angiogenesis via long-term administration of NS and exercise training. NS effect on coronary angiogenesis needs to be explored further as it might lead to a new promising preventive and therapeutic agent of the ischemic heart disease.

Exercise-induced circulating extracellular vesicles protect against cardiac ischemia-reperfusion injury

Extracellular vesicles (EVs) serve an important function as mediators of intercellular communication. Exercise is protective for the heart, although the signaling mechanisms that mediate this cardioprotection have not been fully elucidated. Here using nano-flow cytometry, we found a rapid increase in plasma EVs in human subjects undergoing exercise stress testing. We subsequently identified that serum EVs were increased by ~1.85-fold in mice after 3-week swimming. Intramyocardial injection of equivalent quantities of EVs from exercised mice and non-exercised controls provided similar protective effects against acute ischemia/reperfusion (I/R) injury in mice. However, injection of exercise-induced EVs in a quantity equivalent to the increase seen with exercise (1.85 swim group) significantly enhanced the protective effect. Similarly, treatment with exercise-induced increased EVs provided additional anti-apoptotic effect in H₂O₂-treated H9C2 cardiomyocytes mediated by the activation of ERK1/2 and HSP27 signaling. Finally, by treating H9C2 cells with insulin-like growth factor-1 to mimic exercise stimulus in vitro, we found an increased release of EVs from cardiomyocytes associated with ALIX and RAB35 activation. Collectively, our results show that exercise-induced increase in circulating EVs enhances the protective effects of endogenous EVs against cardiac I/R injury. Exercise-derived EVs might serve as a potent therapy for myocardial injury in the future.

Mitophagy and Mitochondrial Quality Control Mechanisms in the Heart

PURPOSE OF REVIEW

Mitochondrial homeostasis and quality control are essential to maintenance of cardiac function and a disruption of this pathway can lead to deleterious cardiac consequences.

RECENT FINDINGS

Mitochondrial quality control has been described as a major homeostatic mechanism in cell. Recent studies highlighted that an impairment of mitochondrial quality control in different cell or mouse models is linked to cardiac dysfunction. Moreover, some conditions as aging, genetic mutations or obesity have been associated with mitochondrial quality control alteration leading to an accumulation of damaged mitochondria responsible for increased production of reactive oxygen species, metabolic inflexibility, and inflammation, all of which can have sustained effects on cardiac cell function and even cell death.

SUMMARY

In this review, we describe the major mechanisms of mitochondrial quality control, factors that can impair mitochondrial quality control, and the consequences of disrupted mitochondrial quality control.

Macro- and microvascular endothelial dysfunction in diabetes

Endothelial cells, as well as their major products nitric oxide (NO) and prostacyclin, play a key role in the regulation of vascular homeostasis. Diabetes mellitus is an important risk factor for cardiovascular disease. Diabetes-induced endothelial dysfunction is a critical and initiating factor in the genesis of diabetic vascular complications. The present review focuses on both large blood vessels and the microvasculature. The endothelial dysfunction in diabetic macrovascular complications is characterized by reduced NO bioavailability, poorly compensated for by increased production of prostacyclin and/or endothelium-dependent hyperpolarizations, and increased production or action of endothelium-derived vasoconstrictors. The endothelial dysfunction of microvascular complications is primarily characterized by decreased release of NO, enhanced oxidative stress, increased production of inflammatory factors, abnormal angiogenesis, and impaired endothelial repair. In addition, non-coding RNAs (microRNAs) have emerged as participating in numerous cellular processes. Thus, this reviews pays special attention to microRNAs and their modulatory role in diabetes-induced vascular dysfunction. Some therapeutic strategies for preventing and restoring diabetic endothelial dysfunction are also highlighted.

Targeting Obesity and Diabetes to Treat Heart Failure with Preserved Ejection Fraction

Heart failure with preserved ejection fraction (HFpEF) is a major unmet medical need that is characterized by the presence of multiple cardiovascular and non-cardiovascular comorbidities. Foremost among these comorbidities are obesity and diabetes, which are not only risk factors for the development of HFpEF, but worsen symptoms and outcome. Coronary microvascular inflammation with endothelial dysfunction is a common denominator among HFpEF, obesity, and diabetes that likely explains at least in part the etiology of HFpEF and its synergistic relationship with obesity and diabetes. Thus, pharmacological strategies to supplement nitric oxide and subsequent cyclic guanosine monophosphate (cGMP)-protein kinase G (PKG) signaling may have therapeutic promise. Other potential approaches include exercise and lifestyle modifications, as well as targeting endothelial cell mineralocorticoid receptors, non-coding RNAs, sodium glucose transporter 2 inhibitors, and enhancers of natriuretic peptide protective NO-independent cGMP-initiated and alternative signaling, such as LCZ696 and phosphodiesterase-9 inhibitors. Additionally, understanding the role of adipokines in HFpEF may lead to new treatments. Identifying novel drug targets based on the shared underlying microvascular disease process may improve the quality of life and lifespan of those afflicted with both HFpEF and obesity or diabetes, or even prevent its occurrence.

Nitric oxide: what's new to NO?

Nitric oxide (NO) is one of the critical components of the vasculature, regulating key signaling pathways in health. In macrovessels, NO functions to suppress cell inflammation as well as adhesion. In this way, it inhibits thrombosis and promotes blood flow. It also functions to limit vessel constriction and vessel wall remodeling. In microvessels and particularly capillaries, NO, along with growth factors, is important in promoting new vessel formation, a process termed angiogenesis. With age and cardiovascular disease, animal and human studies confirm that NO is dysregulated at multiple levels including decreased production, decreased tissue half-life, and decreased potency. NO has also been implicated in diseases that are related to neurotransmission and cancer although it is likely that these processes involve NO at higher concentrations and from nonvascular cell sources. Conversely, NO and drugs that directly or indirectly increase NO signaling have found clinical applications in both age-related diseases and in younger individuals. This focused review considers recently reported advances being made in the field of NO signaling regulation at several levels including enzymatic production, receptor function, interacting partners, localization of signaling, matrix-cellular and cell-to-cell cross talk, as well as the possible impact these newly described mechanisms have on health and disease.

Pterostilbene protects against myocardial ischemia/reperfusion injury via suppressing oxidative/nitrative stress and inflammatory response

Recent studies have shown that pterostilbene (Pte) confers protection against myocardial ischemia/reperfusion injury. The oxidative/nitrative stress and inflammation induce injury after myocardial ischemia/reperfusion. The present study was designed to evaluate whether treatment with Pte attenuates oxidative/nitrative stress and inflammation in myocardial ischemia/reperfusion (MI/R). Rats were subjected to 30min of myocardial ischemia and 3h of reperfusion, and the rats were administered with vehicle or Pte. The results showed that Pte (10mg/kg) dramatically improved cardiac function and reduced myocardial infarction and myocardial apoptosis following MI/R. As an indicator of oxidative/nitrative stress, myocardial ONOO^- content was markedly reduced after Pte treatment. And, Pte led to a dramatic decrease in superoxide generation and malondialdehyde (MDA) content and a dramatic increase in superoxide dismutase (SOD) activity. In addition, Pte treatment significantly reduced p38 MAPK activation and the expression of iNOS and gp91^phox and increased phosphorylated eNOS expression. Pte treatment dramatically decreased myocardial TNF-α, and IL-1β levels and myeloperoxidase (MPO) activity. Furthermore, ONOO^- suppression by either Pte or uric acid (UA), an ONOO^- scavenger, reduced myocardial injury. In conclusion, Pte exerts a protective effect against MI/R injury by suppressing oxidative/nitrative stress. These results provide evidence that Pte might be a therapeutic approach for the treatment of MI/R injury.