Endothelin Receptor Blocker Reverses Breast Cancer-Induced Cardiac Remodeling.

Background: Although some cancer therapies have overt and/or subclinical cardiotoxic effects that increase subsequent cardiovascular risk in breast cancer patients, we have recently shown that the breast tumor itself can also induce cardiac hypertrophy through the activation of the endothelin system to contribute to cardiovascular risk. However, the extent to which the suppression of the activation of the endothelin system could improve cardiac remodeling in breast cancer patients has yet to be investigated. Objectives: We aimed to retrospectively assess the cardiac morphology/function in patients with breast cancer before receiving cancer chemotherapy and to investigate if the suppression of the activation of the endothelin system improves cardiac remodeling in a mouse model of breast cancer. Methods: Our study involved 28 previously studied women with breast cancer (including 24 after tumor resection) before receiving adjuvant therapy and 17 control healthy women. In addition, we explored how the endothelin system contributed to breast cancer-induced cardiac remodeling using a mouse model of breast cancer. Results: Our results indicate that before chemotherapy, breast cancer patients already exhibit relative cardiac remodeling and subclinical cardiac dysfunction, which was associated with the activation of the endothelin system. Importantly, our mouse data also show that the endothelin receptor blocker atrasentan significantly lessened cardiac remodeling and improved cardiac function in a preclinical model of breast cancer. Conclusions: Although our findings should be further examined in other preclinical/clinical models, our data suggest that endothelin receptor blockers may play a role in cardiac health in individuals with breast cancer. (Understanding and Treating Heart Failure With Preserved Ejection Fraction: Novel Mechanisms, Diagnostics and Potential Therapeutics [Alberta HEART]; NCT02052804 and Multidisciplinary Team Intervention in Cardio-Oncology [TITAN]; NCT01621659).

TRIM35-mediated degradation of nuclear PKM2 destabilizes GATA4/6 and induces P53 in cardiomyocytes to promote heart failure.

Pyruvate kinase M2 (PKM2) is a glycolytic enzyme that translocates to the nucleus to regulate transcription factors in different tissues or pathologic states. Although studied extensively in cancer, its biological role in the heart remains unresolved. PKM1 is more abundant than the PKM2 isoform in cardiomyocytes, and thus, we speculated that PKM2 is not genetically redundant to PKM1 and may be critical in regulating cardiomyocyte-specific transcription factors important for cardiac survival. Here, we showed that nuclear PKM2 (S37P-PKM2) in cardiomyocytes interacts with prosurvival and proapoptotic transcription factors, including GATA4, GATA6, and P53. Cardiomyocyte-specific PKM2-deficient mice (Pkm2 Mut Cre+) developed age-dependent dilated cardiac dysfunction and had decreased amounts of GATA4 and GATA6 (GATA4/6) but increased amounts of P53 compared to Control Cre+ hearts. Nuclear PKM2 prevented caspase-1-dependent cleavage and degradation of GATA4/6 while also providing a molecular platform for MDM2-mediated reduction of P53. In a preclinical heart failure mouse model, nuclear PKM2 and GATA4/6 were decreased, whereas P53 was increased in cardiomyocytes. Loss of nuclear PKM2 was ubiquitination dependent and associated with the induction of the E3 ubiquitin ligase TRIM35. In mice, cardiomyocyte-specific TRIM35 overexpression resulted in decreased S37P-PKM2 and GATA4/6 along with increased P53 in cardiomyocytes compared to littermate controls and similar cardiac dysfunction to Pkm2 Mut Cre+ mice. In patients with dilated left ventricles, increase in TRIM35 was associated with decreased S37P-PKM2 and GATA4/6 and increased P53. This study supports a previously unrecognized role for PKM2 as a molecular platform that mediates cell signaling events essential for cardiac survival.

Muscle LIM Protein Force-Sensing Mediates Sarcomeric Biomechanical Signaling in Human Familial Hypertrophic Cardiomyopathy.

BACKGROUND: Familial hypertrophic cardiomyopathy (HCM) is the most common inherited cardiac disease and is typically caused by mutations in genes encoding sarcomeric proteins that regulate cardiac contractility. HCM manifestations include left ventricular hypertrophy and heart failure, arrythmias, and sudden cardiac death. How dysregulated sarcomeric force production is sensed and leads to pathological remodeling remains poorly understood in HCM, thereby inhibiting the efficient development of new therapeutics. METHODS: Our discovery was based on insights from a severe phenotype of an individual with HCM and a second genetic alteration in a sarcomeric mechanosensing protein. We derived cardiomyocytes from patient-specific induced pluripotent stem cells and developed robust engineered heart tissues by seeding induced pluripotent stem cell-derived cardiomyocytes into a laser-cut scaffold possessing native cardiac fiber alignment to study human cardiac mechanobiology at both the cellular and tissue levels. Coupled with computational modeling for muscle contraction and rescue of disease phenotype by gene editing and pharmacological interventions, we have identified a new mechanotransduction pathway in HCM, shown to be essential in modulating the phenotypic expression of HCM in 5 families bearing distinct sarcomeric mutations. RESULTS: Enhanced actomyosin crossbridge formation caused by sarcomeric mutations in cardiac myosin heavy chain (MYH7) led to increased force generation, which, when coupled with slower twitch relaxation, destabilized the MLP (muscle LIM protein) stretch-sensing complex at the Z-disc. Subsequent reduction in the sarcomeric muscle LIM protein level caused disinhibition of calcineurin-nuclear factor of activated T-cells signaling, which promoted cardiac hypertrophy. We demonstrate that the common muscle LIM protein-W4R variant is an important modifier, exacerbating the phenotypic expression of HCM, but alone may not be a disease-causing mutation. By mitigating enhanced actomyosin crossbridge formation through either genetic or pharmacological means, we alleviated stress at the Z-disc, preventing the development of hypertrophy associated with sarcomeric mutations. CONCLUSIONS: Our studies have uncovered a novel biomechanical mechanism through which dysregulated sarcomeric force production is sensed and leads to pathological signaling, remodeling, and hypertrophic responses. Together, these establish the foundation for developing innovative mechanism-based treatments for HCM that stabilize the Z-disc MLP-mechanosensory complex.

A reversible metabolic stress-sensitive regulation of CRMP2A orchestrates EMT/stemness and increases metastatic potential in cancer.

An epithelial-to-mesenchymal transition (EMT) phenotype with cancer stem cell-like properties is a critical feature of aggressive/metastatic tumors, but the mechanism(s) that promote it and its relation to metabolic stress remain unknown. Here we show that Collapsin Response Mediator Protein 2A (CRMP2A) is unexpectedly and reversibly induced in cancer cells in response to multiple metabolic stresses, including low glucose and hypoxia, and inhibits EMT/stemness. Loss of CRMP2A, when metabolic stress decreases (e.g., around blood vessels in vivo) or by gene deletion, induces extensive microtubule remodeling, increased glutamine utilization toward pyrimidine synthesis, and an EMT/stemness phenotype with increased migration, chemoresistance, tumor initiation capacity/growth, and metastatic potential. In a cohort of 27 prostate cancer patients with biopsies from primary tumors and distant metastases, CRMP2A expression decreases in the metastatic versus primary tumors. CRMP2A is an endogenous molecular brake on cancer EMT/stemness and its loss increases the aggressiveness and metastatic potential of tumors.

Modular design of a tissue engineered pulsatile conduit using human induced pluripotent stem cell-derived cardiomyocytes.

Single ventricle heart defects (SVDs) are congenital disorders that result in a variety of complications, including increased ventricular mechanical strain and mixing of oxygenated and deoxygenated blood, leading to heart failure without surgical intervention. Corrective surgery for SVDs are traditionally handled by the Fontan procedure, requiring a vascular conduit for completion. Although effective, current conduits are limited by their inability to aid in pumping blood into the pulmonary circulation. In this report, we propose an innovative and versatile design strategy for a tissue engineered pulsatile conduit (TEPC) to aid circulation through the pulmonary system by producing contractile force. Several design strategies were tested for production of a functional TEPC. Ultimately, we found that porcine extracellular matrix (ECM)-based engineered heart tissue (EHT) composed of human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) and primary cardiac fibroblasts (HCF) wrapped around decellularized human umbilical artery (HUA) made an efficacious basal TEPC. Importantly, the TEPCs showed effective electrical and mechanical function. Initial pressure readings from our TEPC in vitro (0.68 mmHg) displayed efficient electrical conductivity enabling them to follow electrical pacing up to a 2 Hz frequency. This work represents a proof of principle study for our current TEPC design strategy. Refinement and optimization of this promising TEPC design will lay the groundwork for testing the construct's therapeutic potential in the future. Together this work represents a progressive step toward developing an improved treatment for SVD patients. STATEMENT OF SIGNIFICANCE: Single Ventricle Cardiac defects (SVD) are a form of congenital disorder with a morbid prognosis without surgical intervention. These patients are treated through the Fontan procedure which requires vascular conduits to complete. Fontan conduits have been traditionally made from stable or biodegradable materials with no pumping activity. Here, we propose a tissue engineered pulsatile conduit (TEPC) for use in Fontan circulation to alleviate excess strain in SVD patients. In contrast to previous strategies for making a pulsatile Fontan conduit, we employ a modular design strategy that allows for the optimization of each component individually to make a standalone tissue. This work sets the foundation for an in vitro, trainable human induced pluripotent stem cell based TEPC.

Recessive Mutations in KIF12 Cause High Gamma-Glutamyltransferase Cholestasis.

Undiagnosed liver disease remains an unmet medical need in pediatric hepatology, including children with high gamma-glutamyltransferase (GGT) cholestasis. Here, we report whole-exome sequencing of germline DNA from 2 unrelated children, both offspring of consanguineous union, with neonatal cholestasis and high GGT of unclear etiology. Both children had a rare homozygous damaging mutation (p.Arg219* and p.Val204Met) in kinesin family member 12 (KIF12). Furthermore, an older sibling of the child homozygous for p.Val204Met missense mutation, who was also found to have cholestasis, had the same homozygous mutation, thus identifying the cause of the underlying liver disease. Conclusion: Our findings implicate rare homozygous mutations in KIF12 in the pathogenesis of cholestatic liver disease with high GGT in 3 previously undiagnosed children.

TIMP3 deficiency exacerbates iron overload-mediated cardiomyopathy and liver disease.

Chronic iron overload results in heart and liver diseases and is a common cause of morbidity and mortality in patients with genetic hemochromatosis and secondary iron overload. We investigated the role of tissue inhibitor of metalloproteinase 3 (TIMP3) in iron overload-mediated tissue injury by subjecting male mice lacking Timp3 ( Timp3-/-) and wild-type (WT) mice to 12 wk of chronic iron overload. Whereas WT mice with iron overload developed diastolic dysfunction, iron-overloaded Timp3-/- mice showed worsened cardiac dysfunction coupled with systolic dysfunction. In the heart, loss of Timp3 was associated with increased myocardial fibrosis, greater Timp1, matrix metalloproteinase ( Mmp) 2, and Mmp9 expression, increased active MMP-2 levels, and gelatinase activity. Iron overload in Timp3-/- mice showed twofold higher iron accumulation in the liver compared with WT mice because of constituently lower levels of ferroportin. Loss of Timp3 enhanced the hepatic inflammatory response to iron overload, leading to greater neutrophil and macrophage infiltration and increased hepatic fibrosis. Expression of inflammation-related MMPs (MMP-12 and MMP-13) and inflammatory cytokines (IL-1ß and monocyte chemoattractant protein-1) was elevated to a greater extent in iron-overloaded Timp3-/- livers. Gelatin zymography demonstrated equivalent increases in MMP-2 and MMP-9 levels in WT and Timp3-/- iron-overloaded livers. Loss of Timp3 enhanced the susceptibility to iron overload-mediated heart and liver injury, suggesting that Timp3 is a key protective molecule against iron-mediated pathology. NEW & NOTEWORTHY In mice, loss of tissue inhibitor of metalloproteinase 3 ( Timp3) was associated with systolic and diastolic dysfunctions, twofold higher hepatic iron accumulation (attributable to constituently lower levels of ferroportin), and increased hepatic inflammation. Loss of Timp3 enhanced the susceptibility to iron overload-mediated injury, suggesting that Timp3 plays a key protective role against iron-mediated pathology.

Advanced iron-overload cardiomyopathy in a genetic murine model is rescued by resveratrol therapy.

Iron-overload cardiomyopathy is prevalent on a worldwide basis and is a major comorbidity in patients with genetic hemochromatosis and secondary iron overload. Therapies are limited in part due to lack of a valid preclinical model, which recapitulates advanced iron-overload cardiomyopathy. Male hemojuvelin (HJV) knockout (HJVKO) mice, which lack HJV, a bone morphogenetic co-receptor protein required for hepcidin expression and systemic iron homeostasis, were fed a high-iron diet starting at 4 weeks of age for a duration of 1 year. Aged HJVKO mice in response to iron overload showed increased myocardial iron deposition and mortality coupled with oxidative stress and myocardial fibrosis culminating in advanced iron-overload cardiomyopathy. In a parallel group, iron-overloaded HJVKO mice received resveratrol (240 mg/day) at 9 months of age until 1 year of age. Echocardiography and invasive pressure-volume (PV) loop analyses revealed a complete normalization of iron-overload mediated diastolic and systolic dysfunction in response to resveratrol therapy. In addition, myocardial sarcoplasmic reticulum Ca2+ ATPase (SERCa2a) levels were reduced in iron-overloaded hearts and resveratrol therapy restored SERCa2a levels and suppressed up-regulation of the sodium-calcium exchanger (NCX1). Further, iron-mediated oxidative stress and myocardial fibrosis were suppressed by resveratrol treatment with concomitant activation of the p-Akt and p-AMP-activated protein kinase (AMPK) signaling pathways. A combination of ageing and high-iron diet in male HJVKO mice results in a valid preclinical model that recapitulates iron-overload cardiomyopathy in humans. Resveratrol therapy resulted in normalization of cardiac function demonstrating that resveratrol represents a feasible therapeutic intervention to reduce the burden of iron-overload cardiomyopathy.

Females Are Protected From Iron-Overload Cardiomyopathy Independent of Iron Metabolism: Key Role of Oxidative Stress.

BACKGROUND: Sex-related differences in cardiac function and iron metabolism exist in humans and experimental animals. Male patients and preclinical animal models are more susceptible to cardiomyopathies and heart failure. However, whether similar differences are seen in iron-overload cardiomyopathy is poorly understood. METHODS AND RESULTS: Male and female wild-type and hemojuvelin-null mice were injected and fed with a high-iron diet, respectively, to develop secondary iron overload and genetic hemochromatosis. Female mice were completely protected from iron-overload cardiomyopathy, whereas iron overload resulted in marked diastolic dysfunction in male iron-overloaded mice based on echocardiographic and invasive pressure-volume analyses. Female mice demonstrated a marked suppression of iron-mediated oxidative stress and a lack of myocardial fibrosis despite an equivalent degree of myocardial iron deposition. Ovariectomized female mice with iron overload exhibited essential pathophysiological features of iron-overload cardiomyopathy showing distinct diastolic and systolic dysfunction, severe myocardial fibrosis, increased myocardial oxidative stress, and increased expression of cardiac disease markers. Ovariectomy prevented iron-induced upregulation of ferritin, decreased myocardial SERCA2a levels, and increased NCX1 levels. 17ß-Estradiol therapy rescued the iron-overload cardiomyopathy in male wild-type mice. The responses in wild-type and hemojuvelin-null female mice were remarkably similar, highlighting a conserved mechanism of sex-dependent protection from iron-overload-mediated cardiac injury. CONCLUSIONS: Male and female mice respond differently to iron-overload-mediated effects on heart structure and function, and females are markedly protected from iron-overload cardiomyopathy. Ovariectomy in female mice exacerbated iron-induced myocardial injury and precipitated severe cardiac dysfunction during iron-overload conditions, whereas 17ß-estradiol therapy was protective in male iron-overloaded mice.

Ces3/TGH Deficiency Attenuates Steatohepatitis.

Nonalcoholic fatty liver disease (NAFLD) is the most common form of chronic liver disease in developed countries. NAFLD describes a wide range of liver pathologies from simple steatosis to nonalcoholic steatohepatitis (NASH) and cirrhosis. NASH is distinguished from simple steatosis by inflammation, cell death and fibrosis. In this study we found that mice lacking triacylglycerol hydrolase (TGH, also known as carboxylesterase 3 or carboxylesterase 1d) are protected from high-fat diet (HFD) - induced hepatic steatosis via decreased lipogenesis, increased fatty acid oxidation and improved hepatic insulin sensitivity. To examine the effect of the loss of TGH function on the more severe NAFLD form NASH, we ablated Tgh expression in two independent NASH mouse models, Pemt(-/-) mice fed HFD and Ldlr(-/-) mice fed high-fat, high-cholesterol Western-type diet (WTD). TGH deficiency reduced liver inflammation, oxidative stress and fibrosis in Pemt(-/-) mice. TGH deficiency also decreased NASH in Ldlr(-/-) mice. Collectively, these findings indicate that TGH deficiency attenuated both simple hepatic steatosis and irreversible NASH.

Resveratrol mediates therapeutic hepatic effects in acquired and genetic murine models of iron-overload.

BACKGROUND & AIMS: Abnormal iron metabolism and hepatic iron-overload is a major cause of liver injury and in the development of chronic liver diseases. Iron-overload-mediated liver disease leads to end-stage cirrhosis and/or hepatocellular carcinoma. METHODS: Using a genetic hemochromatosis (hemojuvelin knockout mice) and non-genetic (secondary iron-overload) murine models of hepatic iron-overload, we elucidated the mechanism of hepatic iron injury and the therapeutic effects of resveratrol. RESULTS: Hepatic iron-overload was associated with hepatosplenomegaly, increased oxidative stress, hepatic fibrosis, and inflammation, and a pro-apoptotic state which was markedly corrected by resveratrol therapy. Importantly our aging studies with the hemojuvelin knockout mice showed advanced liver disease in association with steatosis in the absence of a diabetic state which recapitulates the essential pathological features seen in clinical iron-overload. Chronic hepatic iron-overload showed increased nuclear localization of acetylated Forkhead fox-O-1 (FoxO1) transcription factor whereas resveratrol dietary intervention reversed the acetylation of FoxO1 in association with increased SIRT1 levels which together with its pleotropic antioxidant properties are likely key mechanisms of its therapeutic action. Importantly, resveratrol treatment did not affect the degree of hepatic iron-overload but rather direct protects the liver from iron-mediated injury. CONCLUSIONS: Our findings illustrate a novel and definitive therapeutic action of resveratrol and represent an economically feasible therapeutic intervention to treat hepatic iron-overload and liver disease.

ACE2 Deficiency Worsens Epicardial Adipose Tissue Inflammation and Cardiac Dysfunction in Response to Diet-Induced Obesity.

Obesity is increasing in prevalence and is strongly associated with metabolic and cardiovascular disorders. The renin-angiotensin system (RAS) has emerged as a key pathogenic mechanism for these disorders; angiotensin (Ang)-converting enzyme 2 (ACE2) negatively regulates RAS by metabolizing Ang II into Ang 1-7. We studied the role of ACE2 in obesity-mediated cardiac dysfunction. ACE2 null (ACE2KO) and wild-type (WT) mice were fed a high-fat diet (HFD) or a control diet and studied at 6 months of age. Loss of ACE2 resulted in decreased weight gain but increased glucose intolerance, epicardial adipose tissue (EAT) inflammation, and polarization of macrophages into a proinflammatory phenotype in response to HFD. Similarly, human EAT in patients with obesity and heart failure displayed a proinflammatory macrophage phenotype. Exacerbated EAT inflammation in ACE2KO-HFD mice was associated with decreased myocardial adiponectin, decreased phosphorylation of AMPK, increased cardiac steatosis and lipotoxicity, and myocardial insulin resistance, which worsened heart function. Ang 1-7 (24 µg/kg/h) administered to ACE2KO-HFD mice resulted in ameliorated EAT inflammation and reduced cardiac steatosis and lipotoxicity, resulting in normalization of heart failure. In conclusion, ACE2 plays a novel role in heart disease associated with obesity wherein ACE2 negatively regulates obesity-induced EAT inflammation and cardiac insulin resistance.

Iron-overload injury and cardiomyopathy in acquired and genetic models is attenuated by resveratrol therapy.

Iron-overload cardiomyopathy is a prevalent cause of heart failure on a world-wide basis and is a major cause of mortality and morbidity in patients with secondary iron-overload and genetic hemochromatosis. We investigated the therapeutic effects of resveratrol in acquired and genetic models of iron-overload cardiomyopathy. Murine iron-overload models showed cardiac iron-overload, increased oxidative stress, altered Ca(2+) homeostasis and myocardial fibrosis resulting in heart disease. Iron-overload increased nuclear and acetylated levels of FOXO1 with corresponding inverse changes in SIRT1 levels in the heart corrected by resveratrol therapy. Resveratrol, reduced the pathological remodeling and improved cardiac function in murine models of acquired and genetic iron-overload at varying stages of iron-overload. Echocardiography and hemodynamic analysis revealed a complete normalization of iron-overload mediated diastolic and systolic dysfunction in response to resveratrol therapy. Myocardial SERCA2a levels were reduced in iron-overloaded hearts and resveratrol therapy restored SERCA2a levels and corrected altered Ca(2+) homeostasis. Iron-mediated pro-oxidant and pro-fibrotic effects in human and murine cardiomyocytes and cardiofibroblasts were suppressed by resveratrol which correlated with reduction in iron-induced myocardial oxidative stress and myocardial fibrosis. Resveratrol represents a clinically and economically feasible therapeutic intervention to reduce the global burden from iron-overload cardiomyopathy at early and chronic stages of iron-overload.

Antagonism of angiotensin 1-7 prevents the therapeutic effects of recombinant human ACE2.

UNLABELLED: Activation of the angiotensin 1-7/Mas receptor (MasR) axis counteracts angiotensin II (Ang II)-mediated cardiovascular disease. Recombinant human angiotensin-converting enzyme 2 (rhACE2) generates Ang 1-7 from Ang II. We hypothesized that the therapeutic effects of rhACE2 are dependent on Ang 1-7 action. Wild type male C57BL/6 mice (10-12 weeks old) were infused with Ang II (1.5 mg/kg/d) and treated with rhACE2 (2 mg/kg/d). The Ang 1-7 antagonist, A779 (200 ng/kg/min), was administered to a parallel group of mice. rhACE2 prevented Ang II-induced hypertrophy and diastolic dysfunction while A779 prevented these beneficial effects and precipitated systolic dysfunction. rhACE2 effectively antagonized Ang II-mediated myocardial fibrosis which was dependent on the action of Ang 1-7. Myocardial oxidative stress and matrix metalloproteinase 2 activity was further increased by Ang 1-7 inhibition even in the presence of rhACE2. Activation of Akt and endothelial nitric oxide synthase (eNOS) by rhACE2 were suppressed by the antagonism of Ang 1-7 while the activation of pathological signaling pathways was maintained. Blocking Ang 1-7 action prevents the therapeutic effects of rhACE2 in the setting of elevated Ang II culminating in systolic dysfunction. These results highlight a key cardioprotective role of Ang 1-7, and increased Ang 1-7 action represents a potential therapeutic strategy for cardiovascular diseases. KEY MESSAGES: Activation of the renin-angiotensin system (RAS) plays a key pathogenic role in cardiovascular disease. ACE2, a monocarboxypeptidase, negatively regulates pathological effects of Ang II. Antagonizing Ang 1-7 prevents the therapeutic effects of recombinant human ACE2. Our results highlight a key protective role of Ang 1-7 in cardiovascular disease.

Resveratrol treatment of mice with pressure-overload-induced heart failure improves diastolic function and cardiac energy metabolism.

BACKGROUND: Although resveratrol has multiple beneficial cardiovascular effects, whether resveratrol can be used for the treatment and management of heart failure (HF) remains unclear. In the current study, we determined whether resveratrol treatment of mice with established HF could lessen the detrimental phenotype associated with pressure-overload-induced HF and identified physiological and molecular mechanisms contributing to this. METHODS AND RESULTS: C57Bl/6 mice were subjected to either sham or transverse aortic constriction surgery to induce HF. Three weeks post surgery, a cohort of mice with established HF (% ejection fraction <45) was administered resveratrol (≈320 mg/kg per day). Despite a lack of improvement in ejection fraction, resveratrol treatment significantly increased median survival of mice with HF, lessened cardiac fibrosis, reduced gene expression of several disease markers for hypertrophy and extracellular matrix remodeling that were upregulated in HF, promoted beneficial remodeling, and improved diastolic function. Resveratrol treatment of mice with established HF also restored the levels of mitochondrial oxidative phosphorylation complexes, restored cardiac AMP-activated protein kinase activation, and improved myocardial insulin sensitivity to promote glucose metabolism and significantly improved myocardial energetic status. Finally, noncardiac symptoms of HF, such as peripheral insulin sensitivity, vascular function, and physical activity, were improved with resveratrol treatment. CONCLUSIONS: Resveratrol treatment of mice with established HF lessens the severity of the HF phenotype by lessening cardiac fibrosis, improving molecular and structural remodeling of the heart, and enhancing diastolic function, vascular function, and energy metabolism.

TIMP2 and TIMP3 have divergent roles in early renal tubulointerstitial injury.

Tissue inhibitors of metalloproteinases (TIMPs) are endogenous inhibitors of matrix metalloproteinases (MMPs). While TIMP2 and TIMP3 inhibit MMPs, TIMP3 also inhibits activation of pro-MMP2, whereas TIMP2 promotes it. Here we assessed the differential role of TIMP2 and TIMP3 in renal injury using the unilateral ureteral obstruction model. Gene microarray assay showed that post obstruction, the lack of TIMP3 had a greater impact on gene expression of intermediate, late injury- and repair-induced transcripts, kidney selective transcripts, and solute carriers. Renal injury in TIMP3(-/-), but not in TIMP2(-/-), mice increased the expression of collagen type I/III, connective tissue growth factor, transforming growth factor-ß, and the downstream Smad2/3 pathway. Interestingly, ureteral obstruction markedly increased MMP2 activation in the kidneys of TIMP3(-/-) mice, which was completely blocked in the kidneys of TIMP2(-/-) mice. These changes are consistent with enhanced renal tubulointerstitial fibrosis in TIMP3(-/-) and its reduction in TIMP2(-/-) mice. The activities of tumor necrosis factor-α-converting enzyme, caspase-3, and mitogen-activated kinases were elevated in the kidneys of TIMP3(-/-) mice but not TIMP2(-/-) mice, suggesting enhanced activation of apoptotic and pathological signaling pathways only in the obstructed kidney of TIMP3(-/-) mice. Thus, TIMP2 and TIMP3 play differential and contrasting roles in renal injury: TIMP3 protects from damage, whereas TIMP2 promotes injury through MMP2 activation.

Loss of Apelin exacerbates myocardial infarction adverse remodeling and ischemia-reperfusion injury: therapeutic potential of synthetic Apelin analogues.

BACKGROUND: Coronary artery disease leading to myocardial ischemia is the most common cause of heart failure. Apelin (APLN), the endogenous peptide ligand of the APJ receptor, has emerged as a novel regulator of the cardiovascular system. METHODS AND RESULTS: Here we show a critical role of APLN in myocardial infarction (MI) and ischemia-reperfusion (IR) injury in patients and animal models. Myocardial APLN levels were reduced in patients with ischemic heart failure. Loss of APLN increased MI-related mortality, infarct size, and inflammation with drastic reductions in prosurvival pathways resulting in greater systolic dysfunction and heart failure. APLN deficiency decreased vascular sprouting, impaired sprouting of human endothelial progenitor cells, and compromised in vivo myocardial angiogenesis. Lack of APLN enhanced susceptibility to ischemic injury and compromised functional recovery following ex vivo and in vivo IR injury. We designed and synthesized two novel APLN analogues resistant to angiotensin converting enzyme 2 cleavage and identified one analogue, which mimicked the function of APLN, to be markedly protective against ex vivo and in vivo myocardial IR injury linked to greater activation of survival pathways and promotion of angiogenesis. CONCLUSIONS: APLN is a critical regulator of the myocardial response to infarction and ischemia and pharmacologically targeting this pathway is feasible and represents a new class of potential therapeutic agents.

Loss of p47phox subunit enhances susceptibility to biomechanical stress and heart failure because of dysregulation of cortactin and actin filaments.

RATIONALE: The classic phagocyte nicotinamide adenine dinucleotide phosphate oxidase (gp91(phox) or Nox2) is expressed in the heart. Nox2 activation requires membrane translocation of the p47(phox) subunit and is linked to heart failure. We hypothesized that loss of p47(phox) subunit will result in decreased reactive oxygen species production and resistance to heart failure. OBJECTIVE: To define the role of p47(phox) in pressure overload-induced biomechanical stress. METHODS AND RESULTS: Eight-week-old male p47(phox) null (p47(phox) knockout [KO]), Nox2 null (Nox2KO), and wild-type mice were subjected to transverse aortic constriction-induced pressure overload. Contrary to our hypothesis, p47(phox)KO mice showed markedly worsened systolic dysfunction in response to pressure overload at 5 and 9 weeks after transverse aortic constriction compared with wild-type-transverse aortic constriction mice. We found that biomechanical stress upregulated N-cadherin and ß-catenin in p47(phox)KO hearts but disrupted the actin filament cytoskeleton and reduced phosphorylation of focal adhesion kinase. p47(phox) interacts with cytosolic cortactin by coimmunoprecipitation and double immunofluorescence staining in murine and human hearts and translocated to the membrane on biomechanical stress where cortactin interacted with N-cadherin, resulting in adaptive cytoskeletal remodeling. However, p47(phox)KO hearts showed impaired interaction of cortactin with N-cadherin, resulting in loss of biomechanical stress-induced actin polymerization and cytoskeletal remodeling. In contrast, Nox2 does not interact with cortactin, and Nox2-deficient hearts were protected from pressure overload-induced adverse myocardial and intracellular cytoskeletal remodeling. CONCLUSIONS: We showed a novel role of p47(phox) subunit beyond and independent of nicotinamide adenine dinucleotide phosphate oxidase activity as a regulator of cortactin and adaptive cytoskeletal remodeling, leading to a paradoxically enhanced susceptibility to biomechanical stress and heart failure.