Short-term statin treatment reduces, and long-term statin treatment abolishes chronic vascular injury by radiation therapy.

Background: The incidental use of statins during radiation therapy has been associated with a reduced long-term risk of developing atherosclerotic cardiovascular disease. Objectives: Determine if irradiation causes chronic vascular injury and whether short-term administration of statins during and after irradiation is sufficient to prevent chronic injury compared to long-term administration. Methods: C57Bl/6 mice were pretreated with pravastatin for 72 hours and then exposed to 12 Gy x-ray head-and-neck irradiation. Subsequently, they received pravastatin either for one additional day or for one year. Carotid arteries were tested for vascular reactivity and altered gene expression one year after irradiation. Results: Treatment with pravastatin for 24 hours reduced the loss of endothelium-dependent vasorelaxation and protected against enhanced vasoconstriction after IR. It reduced the expression of some markers associated with inflammation and oxidative stress and modulated that of subunits of the voltage and Ca2+ activated K+ (BK) channel in the carotid artery one year after irradiation. Treatment with pravastatin for one year completely reversed the changes caused by irradiation. Conclusions: In mice, short-term administration of pravastatin is sufficient to reduce chronic vascular injury after irradiation. Long-term administration eliminates the effects of irradiation. These findings suggest that a prospective treatment strategy involving statins could be effective in patients undergoing radiation therapy. The optimal duration of treatment in humans has yet to be determined.

Regulation of Smooth Muscle Cell Proliferation by Mitochondrial Ca2+ in Type 2 Diabetes.

Type 2 diabetes (T2D) is associated with increased risk of atherosclerotic vascular disease due to excessive vascular smooth muscle cell (VSMC) proliferation. Here, we investigated the role of mitochondrial dysfunction and Ca2+ levels in VSMC proliferation in T2D. VSMCs were isolated from normoglycemic and T2D-like mice induced by diet. The effects of mitochondrial Ca2+ uptake were studied using mice with selectively inhibited mitochondrial Ca2+/calmodulin-dependent kinase II (mtCaMKII) in VSMCs. Mitochondrial transition pore (mPTP) was blocked using ER-000444793. VSMCs from T2D compared to normoglycemic mice exhibited increased proliferation and baseline cytosolic Ca2+ levels ([Ca2+]cyto). T2D cells displayed lower endoplasmic reticulum Ca2+ levels, reduced mitochondrial Ca2+ entry, and increased Ca2+ leakage through the mPTP. Mitochondrial and cytosolic Ca2+ transients were diminished in T2D cells upon platelet-derived growth factor (PDGF) administration. Inhibiting mitochondrial Ca2+ uptake or the mPTP reduced VSMC proliferation in T2D, but had contrasting effects on [Ca2+]cyto. In T2D VSMCs, enhanced activation of Erk1/2 and its upstream regulators was observed, driven by elevated [Ca2+]cyto. Inhibiting mtCaMKII worsened the Ca2+ imbalance by blocking mitochondrial Ca2+ entry, leading to further increases in [Ca2+]cyto and Erk1/2 hyperactivation. Under these conditions, PDGF had no effect on VSMC proliferation. Inhibiting Ca2+-dependent signaling in the cytosol reduced excessive Erk1/2 activation and VSMC proliferation. Our findings suggest that altered Ca2+ handling drives enhanced VSMC proliferation in T2D, with mitochondrial dysfunction contributing to this process.

Mechanisms by which statins protect endothelial cells from radiation-induced injury in the carotid artery.

Background: The incidental use of statins during radiation therapy has been associated with a reduced long-term risk of developing atherosclerotic cardiovascular disease. However, the mechanisms by which statins protect the vasculature from irradiation injury remain poorly understood. Objectives: Identify the mechanisms by which the hydrophilic and lipophilic statins pravastatin and atorvastatin preserve endothelial function after irradiation. Methods: Cultured human coronary and umbilical vein endothelial cells irradiated with 4 Gy and mice subjected to 12 Gy head-and-neck irradiation were pretreated with statins and tested for endothelial dysfunction, nitric oxide production, oxidative stress, and various mitochondrial phenotypes at 24 and 240 h after irradiation. Results: Both pravastatin (hydrophilic) and atorvastatin (lipophilic) were sufficient to prevent the loss of endothelium-dependent relaxation of arteries after head-and-neck irradiation, preserve the production of nitric oxide by endothelial cells, and suppress the cytosolic reactive oxidative stress associated with irradiation. However, only pravastatin inhibited irradiation-induced production of mitochondrial superoxide; damage to the mitochondrial DNA; loss of electron transport chain activity; and expression of inflammatory markers. Conclusions: Our findings reveal some mechanistic underpinnings of the vasoprotective effects of statins after irradiation. Whereas both pravastatin and atorvastatin can shield from endothelial dysfunction after irradiation, pravastatin additionally suppresses mitochondrial injury and inflammatory responses involving mitochondria. Clinical follow-up studies will be necessary to determine whether hydrophilic statins are more effective than their lipophilic counterparts in reducing the risk of cardiovascular disease in patients undergoing radiation therapy.

The Beneficial Effect of Lomitapide on the Cardiovascular System in LDLr-/- Mice with Obesity.

OBJECTIVES: Homozygous familial hypercholesteremia (HoFH) is a rare, life-threatening metabolic disease, mainly caused by a mutation in the LDL receptor. If untreated, HoFH causes premature death from acute coronary syndrome. Lomitapide is approved by the FDA as a therapy to lower lipid levels in adult patients with HoFH. Nevertheless, the beneficial effect of lomitapide in HoFH models remains to be defined. In this study, we investigated the effect of lomitapide on cardiovascular function using LDL receptor-knockout mice (LDLr-/-). METHODS: Six-week-old LDLr-/- mice were fed a standard diet (SD) or a high-fat diet (HFD) for 12 weeks. Lomitapide (1 mg/Kg/Day) was given by oral gavage for the last 2 weeks in the HFD group. Body weight and composition, lipid profile, blood glucose, and atherosclerotic plaques were measured. Vascular reactivity and markers for endothelial function were determined in conductance arteries (thoracic aorta) and resistance arteries (mesenteric resistance arteries (MRA)). Cytokine levels were measured by using the Mesoscale discovery V-Plex assays. RESULTS: Body weight (47.5 ± 1.5 vs. 40.3 ± 1.8 g), % of fat mass (41.6 ± 1.9% vs. 31.8 ± 1.7%), blood glucose (215.5 ± 21.9 vs. 142.3 ± 7.7 mg/dL), and lipid levels (cholesterol: 600.9 ± 23.6 vs. 451.7 ± 33.4 mg/dL; LDL/VLDL: 250.6 ± 28.9 vs. 161.1 ± 12.24 mg/dL; TG: 299.5 ± 24.1 vs. 194.1 ± 28.1 mg/dL) were significantly decreased, and the % of lean mass (56.5 ± 1.8% vs. 65.2 ± 2.1%) was significantly increased in the HFD group after lomitapide treatment. The atherosclerotic plaque area also decreased in the thoracic aorta (7.9 ± 0.5% vs. 5.7 ± 0.1%). After treatment with lomitapide, the endothelium function of the thoracic aorta (47.7 ± 6.3% vs. 80.7 ± 3.1%) and mesenteric resistance artery (66.4 ± 4.3% vs. 79.5 ± 4.6%) was improved in the group of LDLr-/- mice on HFD. This was correlated with diminished vascular endoplasmic (ER) reticulum stress, oxidative stress, and inflammation. CONCLUSIONS: Treatment with lomitapide improves cardiovascular function and lipid profile and reduces body weight and inflammatory markers in LDLr-/- mice on HFD.

The mitochondrial regulation of smooth muscle cell proliferation in type 2 diabetes.

Background: Type 2 diabetes (T2D) is associated with a strongly increased risk for restenosis after angioplasty driven by proliferation of vascular smooth muscle cells (VSMCs). Here, we sought to determine whether and how mitochondrial dysfunction in T2D drives VSMC proliferation with a focus on ROS and intracellular [Ca 2+ ] that both drive cell proliferation, occur in T2D and are regulated by mitochondrial activity. Methods: Using a diet-induced mouse model of T2D, the inhibition of the mitochondrial Ca 2+ /calmodulin-dependent kinase II (mtCaMKII), a regulator of Ca 2+ entry via the mitochondrial Ca 2+ uniporter selectively in VSMCs, we performed in vivo phenotyping after mechanical injury and established the mechanisms of excessive proliferation in cultured VSMCs. Results: In T2D, the inhibition of mtCaMKII reduced both neointima formation after mechanical injury and the proliferation of cultured VSMCs. VSMCs from T2D mice displayed accelerated proliferation, reduced mitochondrial Ca 2+ entry and membrane potential with elevated baseline [Ca 2+ ] cyto compared to cells from normoglycemic mice. Accelerated proliferation after PDGF treatment was driven by activation of Erk1/2 and its upstream regulators. Hyperactivation of Erk1/2 was Ca 2+ -dependent rather than mitochondrial ROS-driven Ca 2+ -dependent and included the activation of CaMKII in the cytosol. The inhibition of mtCaMKII exaggerated the Ca 2+ imbalance by lowering mitochondrial Ca 2+ entry and increasing baseline [Ca 2+ ] cyto , further enhancing baseline Erk1/2 activation. With inhibition of mtCaMKII, PDGF treatment had no additional effect on cell proliferation. Inhibition of activated CaMKII in the cytosol decreased excessive Erk1/2 activation and reduced VSMC proliferation. Conclusions: Collectively, our results provide evidence for the molecular mechanisms of enhanced VSMC proliferation after mechanical injury by mitochondrial Ca 2+ entry in T2D.

Protective Role of Short-Chain Fatty Acids against Ang- II-Induced Mitochondrial Dysfunction in Brain Endothelial Cells: A Potential Role of Heme Oxygenase 2.

OBJECTIVES: Short-chain fatty acids (SCFAs), the main metabolites released from the gut microbiota, are altered during hypertension and obesity. SCFAs play a beneficial role in the cardiovascular system. However, the effect of SCFAs on cerebrovascular endothelial cells is yet to be uncovered. In this study, we use brain endothelial cells to investigate the in vitro effect of SCFAs on heme oxygenase 2 (HO-2) and mitochondrial function after angiotensin II (Ang-II) treatment. METHODS: Brain human microvascular endothelial cells were treated with Ang-II (500 nM for 24 h) in the presence and absence of an SCFAs cocktail (1 µM; acetate, propionate, and butyrate) and/or HO-2 inhibitor (SnPP 5 µM). At the end of the treatment, HO-2, endothelial markers (p-eNOS and NO production), inflammatory markers (TNFα, NFκB-p50, and -p65), calcium homeostasis, mitochondrial membrane potential, mitochondrial ROS and H2O2, and mitochondrial respiration were determined in all groups of treated cells. KEY RESULTS: Our data showed that SCFAs rescued HO-2 after Ang-II treatment. Additionally, SCFAs rescued Ang-II-induced eNOS reduction and mitochondrial membrane potential impairment and mitochondrial respiration damage. On the other hand, SCFAs reduced Ang-II-induced inflammation, calcium dysregulation, mitochondrial ROS, and H2O2. All of the beneficial effects of SCFAs on endothelial cells and mitochondrial function occurred through HO-2. CONCLUSIONS: SCFAs treatment restored endothelial cells and mitochondrial function following Ang-II-induced oxidative stress. SCFAs exert these beneficial effects by acting on HO-2. Our results are opening the door for more studies to investigate the effect the of SCFAs/HO-2 axis on hypertension and obesity-induced cerebrovascular diseases.

Mitochondrial Ca2+ Uptake Drives Endothelial Injury By Radiation Therapy.

BACKGROUND: Radiation therapy strongly increases the risk of atherosclerotic vascular disease, such as carotid stenosis. Radiation induces DNA damage, in particular in mitochondria, but the upstream and downstream signaling events are poorly understood. The objective of this study was to define such mechanisms. METHODS: Endothelial-specific MCU (mitochondrial Ca2+ uniporter) knockout and C57Bl6/J mice with or without a preinfusion of a mitoTEMPO (mitochondrial reactive oxygen species [ROS] scavenger) were exposed to a single dose of cranial irradiation. 24, and 240 hours postirradiation, vascular reactivity, endothelial function, and mitochondrial integrity were assessed ex vivo and in vitro. RESULTS: In cultured human endothelial cells, irradiation with 4 Gy increased cytosolic Ca2+ transients and the mitochondrial Ca2+ concentration ([Ca2+]mt) and activated MCU. These outcomes correlated with increases in mitochondrial ROS (mtROS), loss of NO production, and sustained damage to mitochondrial but not nuclear DNA. Moreover, irradiation impaired activity of the ETC (electron transport chain) and the transcription of ETC subunits encoded by mitochondrial DNA (mtDNA). Knockdown or pharmacological inhibition of MCU blocked irradiation-induced mtROS production, mtDNA damage, loss of NO production, and impairment of ETC activity. Similarly, the pretreatment with mitoTEMPO, a scavenger of mtROS, reduced irradiation-induced Ca2+ entry, and preserved both the integrity of the mtDNA and the production of NO, suggesting a feed-forward loop involving [Ca2+]m and mtROS. Enhancement of DNA repair in mitochondria, but not in the nucleus, was sufficient to block prolonged mtROS elevations and maintain NO production. Consistent with the findings from cultured cells, in C57BL/6J mice, head and neck irradiation decreased endothelium-dependent vasodilation, and mtDNA integrity in the carotid artery after irradiation. These effects were prevented by endothelial knockout of MCU or infusion with mitoTEMPO. CONCLUSIONS: Irradiation-induced damage to mtDNA is driven by MCU-dependent Ca2+ influx and the generation of mtROS. Such damage leads to reduced transcription of mitochondrial genes and activity of the ETC, promoting sustained mtROS production that induces endothelial dysfunction. Our findings suggest that targeting MCU and mtROS might be sufficient to mitigate irradiation-induced vascular disease.

Retraction notice to "Inhibition of CaMKII in mitochondria preserves endothelial barrier function after irradiation" [Free Radic. Biol. Med. 146C (2020) 287-298].

This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the Authors and Editor-in-Chief. Some of the data presented in Figure 6C, F and G of the above-titled paper were reported incorrectly in the published article. After being contacted by the Journal, the authors discovered an unintentional error in how the original data were analyzed that could affect the accuracy of the subsequent analysis. The raw data were incorrectly grouped in the analysis software, thereby altering the comparisons. Therefore the authors wish to retract the paper and will recollect and reanalyze the data appropriately. The authors apologize for any inconvenience.

Retraction notice to Corrigendum to "Inhibition of CaMKII in mitochondria preserves endothelial barrier function after irradiation" [Free Radical Biol. Med. 146, January (2020) 287-298].

This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the Authors and Editor-in-Chief. Some of the data presented in Figure 6C, F and G of the paper to which this corrigendum relates were reported incorrectly in the published article. After being contacted by the Journal, the authors discovered an unintentional error in how the original data were analyzed that could affect the accuracy of the subsequent analysis. The raw data were incorrectly grouped in the analysis software, thereby altering the comparisons. Therefore the authors wish to retract the paper and corrigendum and will recollect and reanalyze the data appropriately. The authors apologize for any inconvenience.

The microsomal triglyceride transfer protein inhibitor lomitapide improves vascular function in mice with obesity.

OBJECTIVE: In this study, the effect of lomitapide, a microsomal triglyceride transfer protein inhibitor, on the cardiovascular function in obesity was investigated. METHODS: Eight-week-old C57BL/6 mice were fed with high-fat diet for 12 weeks in the presence and absence of lomitapide. Lomitapide was administered by gavage (1 mg/kg/d) during the last 2 weeks of high-fat feeding. Body weight, blood glucose, body composition, and lipid profile were determined. Vascular function and endothelial function markers were studied in the aorta and mesenteric resistance arteries. RESULTS: Lomitapide treatment reduced body weight in mice with obesity. Blood glucose, percentage of fat mass, total cholesterol, and low-density lipoprotein levels were significantly reduced, and the percentage of lean mass was significantly increased after lomitapide treatment. The vascular response to sodium nitroprusside in the aorta and mesenteric arteries was similar among groups. However, the vascular response to acetylcholine was improved in the treated group. This was associated with decreased levels of vascular endoplasmic reticulum stress, inflammation, and oxidative stress. CONCLUSIONS: Treatment with lomitapide attenuated the increase in body weight in mice with obesity and restored the lipid profile and vascular function. These effects were accompanied by a decrease in inflammation and oxidative stress.

Gut Microbiota Regulates the Sympathetic Nerve Activity and Peripheral Serotonin Through Hypothalamic MicroRNA-204 in Order to Increase the Browning of White Adipose Tissue in Obesity.

The prevalence of obesity is increasing worldwide, and novel therapeutic strategies such as enhancement of thermogenic pathways in white adipose tissue (WAT) are gaining more attention. The gut/brain axis plays an essential role in promoting the browning of WAT. However, the mechanism by which this axis regulates WAT function is not fully understood. On the other hand, the role of microRNAs (miRNAs) in the control of WAT browning has already been established. Therefore, understanding the communication pathways linking the gut/brain axis and miRNAs might establish a promising intervention for obesity. Our published data showed that microRNA-204 (miR-204), a microRNA that plays an important role in the control of the central nervous system (CNS) and the pathogenesis of obesity, is affected by gut dysbiosis. Therefore, miR-204 could be a key element that controls the browning of WAT by acting as a potential link between the gut microbiota and the brain. In this review, we summarized the current knowledge about communication pathways between the brain, gut, and miR-204 and examined the literature to discuss potential research directions that might lead to a better understanding of the mechanisms underlying the browning of WAT in obesity.

Hypothalamic miR-204 Induces Alteration of Heart Electrophysiology and Neurogenic Hypertension by Regulating the Sympathetic Nerve Activity: Potential Role of Microbiota.

There is abundant evidence demonstrating the association between gut dysbiosis and neurogenic diseases such as hypertension. A common characteristic of resistant hypertension is the chronic elevation in sympathetic nervous system (SNS) activity accompanied by increased release of norepinephrine (NE), indicating a neurogenic component that contributes to the development of hypertension. Factors that modulate the sympathetic tone to the cardiovascular system in hypertensive patients are still poorly understood. Research has identified an interaction between the brain and the gut, and this interaction plays a possible role in the mechanism of heart damage-induced hypertension. Data, however, remain scarce, and further study is required to define the role of microbiota in sympathetic neural function and its relationship with heart damage and blood pressure (BP) control. Experimental evidence has pointed toward a bidirectional relationship between alterations in the types of bacteria present in the gut and neurogenic diseases, such as hypertension. Our published data showed that miR-204, a microRNA that plays an important role in the CNS function, is affected by gut dysbiosis. Therefore, miR-204 could be a key element that regulates normal sinus rhythm and neuronal hypertension. In this review, we will shed light on the potential mechanism by which microbiota affects hypothalamic miR-204, which in turn, could hinder the sympathetic nerve drive to the cardiovascular system leading to arrhythmia and hypertension.

Association of Cardiotoxicity With Doxorubicin and Trastuzumab: A Double-Edged Sword in Chemotherapy.

Anticancer drugs play an important role in reducing mortality rates and increasing life expectancy in cancer patients. Treatments include monotherapy and/or a combination of radiation therapy, chemotherapy, hormone therapy, or immunotherapy. Despite great advances in drug development, some of these treatments have been shown to induce cardiotoxicity directly affecting heart function and structure, as well as accelerating the development of cardiovascular disease. Such side effects restrict treatment options and can negatively affect disease management. Consequently, when managing cancer patients, it is vital to understand the mechanisms causing cardiotoxicity to better monitor heart function, develop preventative measures against cardiotoxicity, and treat heart failure when it occurs in this patient population. This review discusses the role and mechanism of major chemotherapy agents with principal cardiovascular complications in cancer patients.

Critical Interaction Between Telomerase and Autophagy in Mediating Flow-Induced Human Arteriolar Vasodilation.

OBJECTIVE: Coronary artery disease (CAD) is associated with a compensatory switch in mechanism of flow-mediated dilation (FMD) from nitric oxide (NO) to H2O2. The underlying mechanism responsible for the pathological shift is not well understood, and recent reports directly implicate telomerase and indirectly support a role for autophagy. We hypothesize that autophagy is critical for shear stress-induced release of NO and is a crucial component of for the pathway by which telomerase regulates FMD. Approach and Results: Human left ventricular, atrial, and adipose resistance arterioles were collected for videomicroscopy and immunoblotting. FMD and autophagic flux were measured in arterioles treated with autophagy modulators alone, and in tandem with telomerase-activity modulators. LC3B II/I was higher in left ventricular tissue from patients with CAD compared with non-CAD (2.8±0.2 versus 1.0±0.2-fold change; P<0.05), although p62 was similar between groups. Shear stress increased Lysotracker fluorescence in non-CAD arterioles, with no effect in CAD arterioles. Inhibition of autophagy in non-CAD arterioles induced a switch from NO to H2O2, while activation of autophagy restored NO-mediated vasodilation in CAD arterioles. In the presence of an autophagy activator, telomerase inhibitor prevented the expected switch (Control: 82±4%; NG-Nitro-l-arginine methyl ester: 36±5%; polyethylene glycol catalase: 80±3). Telomerase activation was unable to restore NO-mediated FMD in the presence of autophagy inhibition in CAD arterioles (control: 72±7%; NG-Nitro-l-arginine methyl ester: 79±7%; polyethylene glycol catalase: 38±9%). CONCLUSIONS: We provide novel evidence that autophagy is responsible for the pathological switch in dilator mechanism in CAD arterioles, demonstrating that autophagy acts downstream of telomerase as a common denominator in determining the mechanism of FMD.

MicroRNAs and obesity-induced endothelial dysfunction: key paradigms in molecular therapy.

The endothelium plays a pivotal role in maintaining vascular health. Obesity is a global epidemic that has seen dramatic increases in both adult and pediatric populations. Obesity perturbs the integrity of normal endothelium, leading to endothelial dysfunction which predisposes the patient to cardiovascular diseases. MicroRNAs (miRNAs) are short, single-stranded, non-coding RNA molecules that play important roles in a variety of cellular processes such as differentiation, proliferation, apoptosis, and stress response; their alteration contributes to the development of many pathologies including obesity. Mediators of obesity-induced endothelial dysfunction include altered endothelial nitric oxide synthase (eNOS), Sirtuin 1 (SIRT1), oxidative stress, autophagy machinery and endoplasmic reticulum (ER) stress. All of these factors have been shown to be either directly or indirectly caused by gene regulatory mechanisms of miRNAs. In this review, we aim to provide a comprehensive description of the therapeutic potential of miRNAs to treat obesity-induced endothelial dysfunction. This may lead to the identification of new targets for interventions that may prevent or delay the development of obesity-related cardiovascular disease.

Inhibition of CaMKII in mitochondria preserves endothelial barrier function after irradiation.

Damage to the microvascular endothelium is an important part of normal tissue injury after radiation exposure and driven by the production of pro-oxidants. The Ca2+/calmodulin-dependent protein kinase II is present in the mitochondrial matrix (mitoCaMKII) where it regulates Ca2+ uptake via the mitochondrial Ca2+ uniporter (MCU) and pro-oxidant production. Here, we demonstrate that radiation exposure disrupts endothelial cell barrier integrity in vitro, but can be abrogated by inhibition of mitoCaMKII, MCU, or opening of the mitochondrial transition pore. Scavenging of mitochondrial pro-oxidants with mitoTEMPO before, but not after irradiation, protected barrier function. Furthermore, markers of apoptosis and mitochondrial pro-oxidant production were elevated at 24 h following irradiation and abolished by mitoCaMKII inhibition. Endothelial barrier dysfunction was detected as early as 2 h after irradiation. Despite only mildly impaired mitochondrial respiration, the intracellular ATP levels were significantly reduced 4 h after irradiation and correlated with barrier function. MitoCaMKII inhibition improved intracellular ATP concentrations by increasing glycolysis. Finally, DNA double strand break repair and non-homologous end joining, two major drivers of ATP consumption after irradiation, were greatly increased but not significantly affected by mitoCaMKII inhibition. These findings support the hypothesis that mitoCaMKII activity is linked to mitochondrial pro-oxidant production, reduced ATP production, and loss of endothelial barrier function following irradiation. The inhibition of mitoCaMKII is a promising approach to limiting radiation-induced endothelial injury.

Mitochondrial Oxidative Phosphorylation defect in the Heart of Subjects with Coronary Artery Disease.

Coronary artery disease (CAD) is a leading cause of death worldwide and frequently associated with mitochondrial dysfunction. Detailed understanding of abnormalities in mitochondrial function that occur in patients with CAD is lacking. We evaluated mitochondrial damage, energy production, and mitochondrial complex activity in human non-CAD and CAD hearts. Fresh and frozen human heart tissue was used. Cell lysate or mitochondria were isolated using standard techniques. Mitochondrial DNA (mtDNA), NAD + and ATP levels, and mitochondrial oxidative phosphorylation capacity were evaluated. Proteins critical to the regulation of mitochondrial metabolism and function were also evaluated in tissue lysates. PCR analysis revealed an increase in mtDNA lesions and the frequency of mitochondrial common deletion, both established markers for impaired mitochondrial integrity in CAD compared to non-CAD patient samples. NAD+ and ATP levels were significantly decreased in CAD subjects compared to Non-CAD (NAD+ fold change: non-CAD 1.00 ± 0.17 vs. CAD 0.32 ± 0.12* and ATP fold change: non-CAD 1.00 ± 0.294 vs. CAD 0.01 ± 0.001*; N = 15, P < 0.005). We observed decreased respiration control index in CAD tissue and decreased activity of complexes I, II, and III. Expression of ETC complex subunits and respirasome formation were increased; however, elevations in the de-active form of complex I were observed in CAD. We observed a corresponding increase in glycolytic flux, indicated by a rise in pyruvate kinase and lactate dehydrogenase activity, indicating a compensatory increase in glycolysis for cellular energetics. Together, these results indicate a shift in mitochondrial metabolism from oxidative phosphorylation to glycolysis in human hearts subjects with CAD.

Targeting Autophagy in Obesity-Associated Heart Disease.

Over the past three decades, the increasing rates of obesity have led to an alarming obesity epidemic worldwide. Obesity is associated with an increased risk of cardiovascular diseases; thus, it is essential to define the molecular mechanisms by which obesity affects heart function. Individuals with obesity and overweight have shown changes in cardiac structure and function, leading to cardiomyopathy, hypertrophy, atrial fibrillation, and arrhythmia. Autophagy is a highly conserved recycling mechanism that delivers proteins and damaged organelles to lysosomes for degradation. In the hearts of patients and mouse models with obesity, this process is impaired. Furthermore, it has been shown that autophagy flux restoration in obesity models improves cardiac function. Therefore, autophagy may play an important role in mitigating the adverse effects of obesity on the heart. Throughout this review, we will discuss the benefits of autophagy on the heart in obesity and how regulating autophagy might be a therapeutic tool to reduce the risk of obesity-associated cardiovascular diseases.

Telomerase Deficiency Predisposes to Heart Failure and Ischemia-Reperfusion Injury.

Introduction: Elevated levels of mitochondrial reactive oxygen species (ROS) contribute to the development of numerous cardiovascular diseases. TERT, the catalytic subunit of telomerase, has been shown to translocate to mitochondria to suppress ROS while promoting ATP production. Acute overexpression of TERT increases survival and decreases infarct size in a mouse model of myocardial infarct, while decreased telomerase activity predisposes to mitochondrial defects and heart failure. In the present study, we examined the role of TERT on cardiac structure and function under basal conditions and conditions of acute or prolonged stress in a novel rat model of TERT deficiency. Methods: Cardiac structure and function were evaluated via transthoracic echocardiogram. Langendorff preparations were used to test the effects of acute global ischemia reperfusion injury on cardiac function and infarction. Coronary flow and left ventricular pressure were measured during and after ischemia/reperfusion (I/R). Mitochondrial DNA integrity was measured by PCR and mitochondrial respiration was assessed in isolated mitochondria using an Oxygraph. Angiotensin II infusion was used as an established model of systemic stress. Results: No structural changes (echocardiogram) or coronary flow/left ventricle pressure (isolated hearts) were observed in TERT-/- rats at baseline; however, after I/R, coronary flow was significantly reduced in TERT-/- compared to wild type (WT) rats, while diastolic Left Ventricle Pressure was significantly elevated (n = 6 in each group; p < 0.05) in the TERT-/-. Interestingly, infarct size was less in TERT-/- rats compared to WT rats, while mitochondrial respiratory control index decreased and mitochondrial DNA lesions increased in TERT-/- compared to WT. Angiotensin II treatment did not alter cardiac structure or function; however, it augmented the infarct size significantly more in TERT-/- compared to the WT. Conclusion: Absence of TERT activity increases susceptibility to stress like cardiac injury. These results suggest a critical role of telomerase in chronic heart disease.