The American Heart Association at 100: A Century of Scientific Progress and the Future of Cardiovascular Science: A Presidential Advisory From the American Heart Association.

In 1924, the founders of the American Heart Association (AHA) envisioned an international society focused on the heart and aimed at facilitating research, disseminating information, increasing public awareness, and developing public health policy related to heart disease. This presidential advisory provides a comprehensive review of the past century of cardiovascular and stroke science, with a focus on the AHA's contributions, as well as informed speculation about the future of cardiovascular science into the next century of the organization's history. The AHA is a leader in fundamental, translational, clinical, and population science, and it promotes the concept of the "learning health system," in which a continuous cycle of evidence-based practice leads to practice-based evidence, permitting an iterative refinement in clinical evidence and care. This advisory presents the AHA's journey over the past century from instituting professional membership to establishing extraordinary research funding programs; translating evidence to practice through clinical practice guidelines; affecting systems of care through quality programs, certification, and implementation; leading important advocacy efforts at the federal, state and local levels; and building global coalitions around cardiovascular and stroke science and public health. Recognizing an exciting potential future for science and medicine, the advisory offers a vision for even greater impact for the AHA's second century in its continued mission to be a relentless force for longer, healthier lives.

Profibrotic COVID-19 subphenotype exhibits enhanced localized ER-dependent HSP47+ expression in cardiac myofibroblasts in situ.

We recently described a subgroup of autopsied COVID-19 subjects (∼40%), termed 'profibrotic phenotype,' who exhibited clusters of myofibroblasts (Mfbs), which were positive for the collagen-specific chaperone heat shock protein 47 (HSP47+) in situ. This report identifies increased, localized (hot spot restricted) expression of αSMA, COLα1, POSTN and FAP supporting the identity of HSP47+ cells as myofibroblasts and characterizing a profibrotic extracellular matrix (ECM) phenotype. Coupled with increased GRP78 in COVID-19 subjects, these data could reflect induction of the unfolded protein response for mitigation of proteostasis (i.e., protein homeostasis) dysfunction in discrete clusters of cells. ECM shifts in selected COVID-19 subjects occur without significant increases in either global trichrome positive staining or myocardial injury based quantitively on standard H&E scoring. Our findings also suggest distinct mechanism(s) for ECM remodeling in the setting of SARS-CoV-2 infection. The ratio of CD163+/CD68+ cells is increased in hot spots of profibrotic hearts compared with either controls or outside of hot spots in COVID-19 subjects. In sum, matrix remodeling of human COVID-19 hearts in situ is characterized by site-restricted profibrotic mediated (e.g., HSP47+ Mfbs, CD163+ Mφs) modifications in ECM (i.e., COLα1, POSTN, FAP), with a strong correlation between COLα1 and HSP47+cells within hot spots. Given the established associations of viral infection (e.g., human immunodeficiency virus; HIV), myocardial fibrosis and sudden cardiac death, early screening tools (e.g., plasma biomarkers, noninvasive cardiac magnetic resonance imaging) for diagnosis, monitoring and treatment of fibrotic ECM remodeling are warranted for COVID-19 high-risk populations.

Opioid Use and Its Relationship to Cardiovascular Disease and Brain Health: A Presidential Advisory From the American Heart Association.

The misuse of opioids continues to be epidemic, resulting in dependency and a recent upsurge in drug overdoses that have contributed to a significant decrease in life expectancy in the United States. Moreover, recent data suggest that commonly used opioids for the management of pain may produce undesirable pharmacological actions and interfere with critical medications commonly used in cardiovascular disease and stroke; however, the impact on outcomes remains controversial. The American Heart Association developed an advisory statement for health care professionals and researchers in the setting of cardiovascular and brain health to synthesize the current literature, to provide approaches for identifying patients with opioid use disorder, and to address pain management and overdose. A literature and internet search spanning from January 1, 2012, to February 15, 2021, and limited to epidemiology studies, reviews, consensus statements, and guidelines in human subjects was conducted. Suggestions and considerations listed in this document are based primarily on published evidence from this review whenever possible, as well as expert opinion. Several federal and institutional consensus documents and clinical resources are currently available to both patients and clinicians; however, none have specifically addressed cardiovascular disease and brain health. Although strategic tools and therapeutic approaches for recognition of opioid use disorder and safe opioid use are available for health care professionals who manage patients with cardiovascular disease and stroke, high-quality evidence does not currently exist. Therefore, there is an urgent need for more research to identify the most effective approaches to improve care for these patients.

Impact of the COVID-19 Pandemic on Cardiovascular Science: Anticipating Problems and Potential Solutions: A Presidential Advisory From the American Heart Association.

The coronavirus disease 2019 (COVID-19) pandemic has had worldwide repercussions for health care and research. In spring 2020, most non-COVID-19 research was halted, hindering research across the spectrum from laboratory-based experimental science to clinical research. Through the second half of 2020 and the first half of 2021, biomedical research, including cardiovascular science, only gradually restarted, with many restrictions on onsite activities, limited clinical research participation, and the challenges associated with working from home and caregiver responsibilities. Compounding these impediments, much of the global biomedical research infrastructure was redirected toward vaccine testing and deployment. This redirection of supply chains, personnel, and equipment has additionally hampered restoration of normal research activity. Transition to virtual interactions offset some of these limitations but did not adequately replace the need for scientific exchange and collaboration. Here, we outline key steps to reinvigorate biomedical research, including a call for increased support from the National Institutes of Health. We also call on academic institutions, publishers, reviewers, and supervisors to consider the impact of COVID-19 when assessing productivity, recognizing that the pandemic did not affect all equally. We identify trainees and junior investigators, especially those with caregiving roles, as most at risk of being lost from the biomedical workforce and identify steps to reduce the loss of these key investigators. Although the global pandemic highlighted the power of biomedical science to define, treat, and protect against threats to human health, significant investment in the biomedical workforce is required to maintain and promote well-being.

Advancing Healthcare Reform: The American Heart Association's 2020 Statement of Principles for Adequate, Accessible, and Affordable Health Care: A Presidential Advisory From the American Heart Association.

The mission of the American Heart Association is to be a relentless force for a world of longer, healthier lives. The American Heart Association has consistently prioritized the needs and perspective of the patient in taking positions on healthcare reform while recognizing the importance of biomedical research, providers, and healthcare delivery systems in advancing the care of patients and the prevention of disease. The American Heart Association's vision for healthcare reform describes the foundational changes needed for the health system to serve the best interests of patients and to achieve health care and coverage that are adequate, accessible, and affordable for everyone living in the United States. The American Heart Association is committed to advancing the dialogue around healthcare reform and has prepared this updated statement of our principles, placed in the context of the advances in coverage and care that have occurred after the passage of the Affordable Care Act, the rapidly changing landscape of healthcare delivery systems, and our evolving recognition that efforts to prevent cardiovascular disease can have synergistic benefit in preventing other diseases and improving overall well-being. These updated principles focus on expanding access to affordable health care and coverage; enhancing the availability of evidence-based preventive services; eliminating disparities that limit the availability and equitable delivery of health care; strengthening the public health infrastructure to respond to social determinants of health; prioritizing and accelerating investments in biomedical research; and growing a diverse, culturally competent health and healthcare workforce prepared to meet the challenges of delivering high-value health care.

Lurbinectedin versus pegylated liposomal doxorubicin or topotecan in patients with platinum-resistant ovarian cancer: A multicenter, randomized, controlled, open-label phase 3 study (CORAIL).

OBJECTIVE: The randomized phase 3 CORAIL trial evaluated whether lurbinectedin improved progression-free survival (PFS) compared to pegylated liposomal doxorubicin (PLD) or topotecan in patients with platinum-resistant ovarian cancer. METHODS: Patients were randomly assigned (1:1) to lurbinectedin 3.2 mg/m2 1-h i.v. infusion q3wk (experimental arm), versus PLD 50 mg/m2 1-h i.v. infusion q4wk or topotecan 1.50 mg/m2 30-min i.v. infusion Days 1-5 q3wk (control arm). Stratification factors were PS (0 vs. ≥1), prior PFI (1-3 months vs. >3 months), and prior chemotherapy lines (1-2 vs. 3). The primary endpoint was PFS by Independent Review Committee in all randomized patients. This study was registered with ClinicalTrials.gov, NCT02421588. RESULTS: 442 patients were randomized: 221 in lurbinectedin arm and 221 in control arm (127 PLD and 94 topotecan). With a median follow-up of 25.6 months, median PFS was 3.5 months (95% CI, 2.1-3.7) in the lurbinectedin arm and 3.6 months (95% CI, 2.7-3.8) in the control arm (stratified log-rank p = 0.6294; HR = 1.057). Grade ≥ 3 treatment-related adverse events (AEs) were most frequent in the control arm: 64.8% vs. 47.9% (p = 0.0005), mainly due to hematological toxicities. The most common grade ≥ 3 AEs were: fatigue (7.3% of patients) and nausea (5.9%) with lurbinectedin; mucosal inflammation (8.5%) and fatigue (8.0%) in the control arm. CONCLUSIONS: The primary endpoint of improvement in PFS was not met. Lurbinectedin showed similar antitumor efficacy and was better tolerated than current standard of care in patients with platinum-resistant ovarian cancer.

[Optimizing observer performance of clinic blood Pressure measurement: a position statement from the Lancet Commission on Hypertension GroupOtimização do desempenho do observador na medição clínica da pressão arterial: posicionamento do Grupo da Lancet Commission on Hypertension]. / Optimización del desempeño del observador al medir la presión arterial en el consultorio: declaración de posición de la Comisión Lancet de Hipertensión.

High blood pressure (BP) is a highly prevalent modifiable cause of cardiovascular disease, stroke, and death. Accurate BP measurement is critical, given that a 5-mmHg measurement error may lead to incorrect hypertension status classification in 84 million individuals worldwide. This position statement summarizes procedures for optimizing observer performance in clinic BP measurement, with special attention given to low-tomiddle- income settings, where resource limitations, heavy workloads, time constraints, and lack of electrical power make measurement more challenging. Many measurement errors can be minimized by appropriate patient preparation and standardized techniques. Validated semi-automated/automated upper arm cuff devices should be used instead of auscultation to simplify measurement and prevent observer error. Task sharing, creating a dedicated measurement workstation, and using semi-automated or solar-charged devices may help. Ensuring observer training, and periodic re-training, is critical. Low-cost, easily accessible certification programs should be considered to facilitate best BP measurement practice.

A hipertensão é uma causa altamente prevalente de doença cardiovascular, acidente vascular cerebral e morte. A medição precisa da pressão arterial (PA) é um aspecto crítico, uma vez que erros de mensuração da ordem de 5 mmHg podem levar a uma classificação incorreta do status de hipertensão em 84 milhões de pessoas em todo o mundo. O presente posicionamento resume os procedimentos para otimizar o desempenho do observador (o indivíduo responsável pela mensuração da PA) na mensuração clínica da PA, com atenção especial para contextos de baixa a média renda, onde recursos limitados, cargas de trabalho pesadas, restrições de tempo e falta de energia elétrica tornam mais desafiadora a tarefa de medir a PA. Muitos erros de mensuração podem ser minimizados pela preparação adequada do paciente e pelo uso de técnicas padronizadas. Para simplificar a mensuração e evitar erros do observador, devem-se utilizar dispositivos semiautomatizados ou automatizados validados, com manguito para braço, ao invés de auscultação. O compartilhamento de tarefas, a criação de uma estação de trabalho dedicada à mensuração e o uso de dispositivos semiautomatizados ou com carga solar podem ajudar. É essencial que seja assegurado o treinamento e retreinamento periódico do observador. Programas de certificação de baixo custo e de fácil acesso devem ser considerados para facilitar a adoção das melhores práticas na mensuração da PA.

[Lancet Commission on Hypertension Group position statement on the global improvement of accuracy standards for devices that measure blood pressurePosicionamento do Grupo da Lancet Commission on Hypertension sobre a melhoria global dos padrões de acurácia para aparelhos que medem a pressão arterial]. / Declaración de posición del Grupo de la Comisión Lancet de Hipertensión con respecto a la mejora mundial de las normas de exactitud para los dispositivos de medición de la presión arterial.

The Lancet Commission on Hypertension identified that a key action to address the worldwide burden of high blood pressure (BP) was to improve the quality of BP measurements by using BP devices that have been validated for accuracy. Currently, there are over 3 000 commercially available BP devices, but many do not have published data on accuracy testing according to established scientific standards. This problem is enabled through weak or absent regulations that allow clearance of devices for commercial use without formal validation. In addition, new BP technologies have emerged (e.g. cuffless sensors) for which there is no scientific consensus regarding BP measurement accuracy standards. Altogether, these issues contribute to the widespread availability of clinic and home BP devices with limited or uncertain accuracy, leading to inappropriate hypertension diagnosis, management and drug treatment on a global scale. The most significant problems relating to the accuracy of BP devices can be resolved by the regulatory requirement for mandatory independent validation of BP devices according to the universally-accepted International Organization for Standardization Standard. This is a primary recommendation for which there is an urgent international need. Other key recommendations are development of validation standards specifically for new BP technologies and online lists of accurate devices that are accessible to consumers and health professionals. Recommendations are aligned with WHO policies on medical devices and universal healthcare. Adherence to recommendations would increase the global availability of accurate BP devices and result in better diagnosis and treatment of hypertension, thus decreasing the worldwide burden from high BP.

A Comissão Lancet sobre Hipertensão Arterial identificou que uma iniciativa central para enfrentar a carga mundial da hipertensão arterial seria a melhoria na qualidade da mensuração da pressão arterial pelo uso aparelhos de pressão arterial validados quanto à acurácia. Atualmente, existem mais de 3 000 aparelhos de pressão arterial disponíveis comercialmente; entretanto, muitos não têm dados publicados sobre testes de acurácia realizados de acordo com padrões científicos estabelecidos. Este problema resulta de regulamentação fraca ou inexistente, o que permite a aprovação para uso comercial de dispositivos sem validação formal. Além disso, surgiram novas tecnologias de mensuração da pressão arterial (por exemplo, sensores sem algemas) sem consenso científico quanto aos padrões de acurácia. No conjunto, essas questões contribuem para a oferta generalizada de dispositivos de pressão arterial clínica e domiciliar com acurácia limitada ou incerta, levando a diagnóstico, gerenciamento e tratamento inadequados da hipertensão em escala global. Os problemas mais significativos relacionados com a acurácia dos dispositivos de pressão arterial podem ser resolvidos por regulamentação que imponha a obrigatoriedade de validação independente dos aparelhos de pressão arterial, de acordo com a norma universalmente aceita pela Organização Internacional de Normalização. Esta é uma recomendação fundamental para a qual existe uma necessidade internacional urgente. Outras recomendações essenciais incluem o desenvolvimento de padrões de validação especificamente para novas tecnologias de mensuração da pressão arterial e listas on-line de aparelhos com acurácia adequada que sejam acessíveis aos consumidores e profissionais de saúde. As recomendações estão alinhadas com as políticas da Organização Mundial da Saúde (OMS) sobre dispositivos médicos e atenção universal à saúde. A adesão às recomendações aumentaria a oferta global de dispositivos de pressão arterial com acurácia adequada e resultaria em melhor diagnóstico e tratamento da hipertensão arterial, diminuindo assim a carga mundial dessa doença.

The Human 343delT HSPB5 Chaperone Associated with Early-onset Skeletal Myopathy Causes Defects in Protein Solubility.

Mutations of HSPB5 (also known as CRYAB or αB-crystallin), a bona fide heat shock protein and molecular chaperone encoded by the HSPB5 (crystallin, alpha B) gene, are linked to multisystem disorders featuring variable combinations of cataracts, cardiomyopathy, and skeletal myopathy. This study aimed to investigate the pathological mechanisms involved in an early-onset myofibrillar myopathy manifesting in a child harboring a homozygous recessive mutation in HSPB5, 343delT. To study HSPB5 343delT protein dynamics, we utilize model cell culture systems including induced pluripotent stem cells derived from the 343delT patient (343delT/343delT) along with isogenic, heterozygous, gene-corrected control cells (WT KI/343delT) and BHK21 cells, a cell line lacking endogenous HSPB5 expression. 343delT/343delT and WT KI/343delT-induced pluripotent stem cell-derived skeletal myotubes and cardiomyocytes did not express detectable levels of 343delT protein, contributable to the extreme insolubility of the mutant protein. Overexpression of HSPB5 343delT resulted in insoluble mutant protein aggregates and induction of a cellular stress response. Co-expression of 343delT with WT prevented visible aggregation of 343delT and improved its solubility. Additionally, in vitro refolding of 343delT in the presence of WT rescued its solubility. We demonstrate an interaction between WT and 343delT both in vitro and within cells. These data support a loss-of-function model for the myopathy observed in the patient because the insoluble mutant would be unavailable to perform normal functions of HSPB5, although additional gain-of-function effects of the mutant protein cannot be excluded. Additionally, our data highlight the solubilization of 343delT by WT, concordant with the recessive inheritance of the disease and absence of symptoms in carrier individuals.

The NADPH metabolic network regulates human αB-crystallin cardiomyopathy and reductive stress in Drosophila melanogaster.

Dominant mutations in the alpha-B crystallin (CryAB) gene are responsible for a number of inherited human disorders, including cardiomyopathy, skeletal muscle myopathy, and cataracts. The cellular mechanisms of disease pathology for these disorders are not well understood. Among recent advances is that the disease state can be linked to a disturbance in the oxidation/reduction environment of the cell. In a mouse model, cardiomyopathy caused by the dominant CryAB(R120G) missense mutation was suppressed by mutation of the gene that encodes glucose 6-phosphate dehydrogenase (G6PD), one of the cell's primary sources of reducing equivalents in the form of NADPH. Here, we report the development of a Drosophila model for cellular dysfunction caused by this CryAB mutation. With this model, we confirmed the link between G6PD and mutant CryAB pathology by finding that reduction of G6PD expression suppressed the phenotype while overexpression enhanced it. Moreover, we find that expression of mutant CryAB in the Drosophila heart impaired cardiac function and increased heart tube dimensions, similar to the effects produced in mice and humans, and that reduction of G6PD ameliorated these effects. Finally, to determine whether CryAB pathology responds generally to NADPH levels we tested mutants or RNAi-mediated knockdowns of phosphogluconate dehydrogenase (PGD), isocitrate dehydrogenase (IDH), and malic enzyme (MEN), the other major enzymatic sources of NADPH, and we found that all are capable of suppressing CryAB(R120G) pathology, confirming the link between NADP/H metabolism and CryAB.

Molecular stress-inducing compounds increase osteoclast formation in a heat shock factor 1 protein-dependent manner.

Many anticancer therapeutic agents cause bone loss, which increases the risk of fractures that severely reduce quality of life. Thus, in drug development, it is critical to identify and understand such effects. Anticancer therapeutic and HSP90 inhibitor 17-(allylamino)-17-demethoxygeldanamycin (17-AAG) causes bone loss by increasing osteoclast formation, but the mechanism underlying this is not understood. 17-AAG activates heat shock factor 1 (Hsf1), the master transcriptional regulator of heat shock/cell stress responses, which may be involved in this negative action of 17-AAG upon bone. Using mouse bone marrow and RAW264.7 osteoclast differentiation models we found that HSP90 inhibitors that induced a heat shock response also enhanced osteoclast formation, whereas HSP90 inhibitors that did not (including coumermycin A1 and novobiocin) did not affect osteoclast formation. Pharmacological inhibition or shRNAmir knockdown of Hsf1 in RAW264.7 cells as well as the use of Hsf1 null mouse bone marrow cells demonstrated that 17-AAG-enhanced osteoclast formation was Hsf1-dependent. Moreover, ectopic overexpression of Hsf1 enhanced 17-AAG effects upon osteoclast formation. Consistent with these findings, protein levels of the essential osteoclast transcription factor microphthalmia-associated transcription factor were increased by 17-AAG in an Hsf1-dependent manner. In addition to HSP90 inhibitors, we also identified that other agents that induced cellular stress, such as ethanol, doxorubicin, and methotrexate, also directly increased osteoclast formation, potentially in an Hsf1-dependent manner. These results, therefore, indicate that cellular stress can enhance osteoclast differentiation via Hsf1-dependent mechanisms and may significantly contribute to pathological and therapeutic related bone loss.

Malfolded protein structure and proteostasis in lung diseases.

Recent discoveries indicate that disorders of protein folding and degradation play a particularly important role in the development of lung diseases and their associated complications. The overarching purpose of the National Heart, Lung, and Blood Institute workshop on "Malformed Protein Structure and Proteostasis in Lung Diseases" was to identify mechanistic and clinical research opportunities indicated by these recent discoveries in proteostasis science that will advance our molecular understanding of lung pathobiology and facilitate the development of new diagnostic and therapeutic strategies for the prevention and treatment of lung disease. The workshop's discussion focused on identifying gaps in scientific knowledge with respect to proteostasis and lung disease, discussing new research advances and opportunities in protein folding science, and highlighting novel technologies with potential therapeutic applications for diagnosis and treatment.

A near-infrared fluorescent voltage-sensitive dye allows for moderate-throughput electrophysiological analyses of human induced pluripotent stem cell-derived cardiomyocytes.

Human induced pluripotent stem cell-derived cardiomyocyte (iPSC-CM)-based assays are emerging as a promising tool for the in vitro preclinical screening of QT interval-prolonging side effects of drugs in development. A major impediment to the widespread use of human iPSC-CM assays is the low throughput of the currently available electrophysiological tools. To test the precision and applicability of the near-infrared fluorescent voltage-sensitive dye 1-(4-sulfanatobutyl)-4-{ß[2-(di-n-butylamino)-6-naphthyl]butadienyl}quinolinium betaine (di-4-ANBDQBS) for moderate-throughput electrophysiological analyses, we compared simultaneous transmembrane voltage and optical action potential (AP) recordings in human iPSC-CM loaded with di-4-ANBDQBS. Optical AP recordings tracked transmembrane voltage with high precision, generating nearly identical values for AP duration (AP durations at 10%, 50%, and 90% repolarization). Human iPSC-CMs tolerated repeated laser exposure, with stable optical AP parameters recorded over a 30-min study period. Optical AP recordings appropriately tracked changes in repolarization induced by pharmacological manipulation. Finally, di-4-ANBDQBS allowed for moderate-throughput analyses, increasing throughput >10-fold over the traditional patch-clamp technique. We conclude that the voltage-sensitive dye di-4-ANBDQBS allows for high-precision optical AP measurements that markedly increase the throughput for electrophysiological characterization of human iPSC-CMs.

Myocardial Strain for the Differentiation of Myocardial Involvement in the Post-Acute Sequelae of COVID-19-A Multiparametric Cardiac MRI Study.

Myocardial involvement was shown to be associated with an unfavorable prognosis in patients with COVID-19, which could lead to fatal outcomes as in myocardial injury-induced arrhythmias and sudden cardiac death. We hypothesized that magnetic resonance imaging (MRI) myocardial strain parameters are sensitive markers for identifying subclinical cardiac dysfunction associated with myocardial involvement in the post-acute sequelae of COVID-19 (PASC). This study evaluated 115 subjects, including 65 consecutive COVID-19 patients, using MRI for the assessment of either post-COVID-19 myocarditis or other cardiomyopathies. Subjects were categorized, based on the results of the MRI exams, as having either 'suspected' or 'excluded' myocarditis. A control group of 50 matched individuals was studied. Along with parameters of global cardiac function, the MRI images were analyzed for measurements of the myocardial T1, T2, extracellular volume (ECV), strain, and strain rate. Based on the MRI late gadolinium enhancement and T1/T2/ECV mappings, myocarditis was suspected in 7 out of 22 patients referred due to concern of myocarditis and in 9 out of 43 patients referred due to concern of cardiomyopathies. The myocardial global longitudinal, circumferential, and radial strains and strain rates in the suspected myocarditis group were significantly smaller than those in the excluded myocarditis group, which in turn were significantly smaller than those in the control group. The results showed significant correlations between the strain, strain rate, and global cardiac function parameters. In conclusion, this study emphasizes the value of multiparametric MRI for differentiating patients with myocardial involvement in the PASC based on changes in the myocardial contractility pattern and tissue structure.

Glutathione-dependent reductive stress triggers mitochondrial oxidation and cytotoxicity.

To investigate the effects of the predominant nonprotein thiol, glutathione (GSH), on redox homeostasis, we employed complementary pharmacological and genetic strategies to determine the consequences of both loss- and gain-of-function GSH content in vitro. We monitored the redox events in the cytosol and mitochondria using reduction-oxidation sensitive green fluorescent protein (roGFP) probes and the level of reduced/oxidized thioredoxins (Trxs). Either H(2)O(2) or the Trx reductase inhibitor 1-chloro-2,4-dinitrobenzene (DNCB), in embryonic rat heart (H9c2) cells, evoked 8 or 50 mV more oxidizing glutathione redox potential, E(hc) (GSSG/2GSH), respectively. In contrast, N-acetyl-L-cysteine (NAC) treatment in H9c2 cells, or overexpression of either the glutamate cysteine ligase (GCL) catalytic subunit (GCLC) or GCL modifier subunit (GCLM) in human embryonic kidney 293 T (HEK293T) cells, led to 3- to 4-fold increase of GSH and caused 7 or 12 mV more reducing E(hc), respectively. This condition paradoxically increased the level of mitochondrial oxidation, as demonstrated by redox shifts in mitochondrial roGFP and Trx2. Lastly, either NAC treatment (EC(50) 4 mM) or either GCLC or GCLM overexpression exhibited increased cytotoxicity and the susceptibility to the more reducing milieu was achieved at decreased levels of ROS. Taken together, our findings reveal a novel mechanism by which GSH-dependent reductive stress triggers mitochondrial oxidation and cytotoxicity.

Carvedilol Phenocopies PGC-1α Overexpression to Alleviate Oxidative Stress, Mitochondrial Dysfunction and Prevent Doxorubicin-Induced Toxicity in Human iPSC-Derived Cardiomyocytes.

Doxorubicin (DOX), one of the most effective and widely used anticancer drugs, has the major limitation of cancer treatment-related cardiotoxicity (CTRTOX) in the clinic. Reactive oxygen species (ROS) generation and mitochondrial dysfunction are well-known consequences of DOX-induced injury to cardiomyocytes. This study aimed to explore the mitochondrial functional consequences and associated mechanisms of pretreatment with carvedilol, a ß-blocking agent known to exert protection against DOX toxicity. When disease modeling was performed using cultured rat cardiac muscle cells (H9c2 cells) and human iPSC-derived cardiomyocytes (iPSC-CMs), we found that prophylactic carvedilol mitigated not only the DOX-induced suppression of mitochondrial function but that the mitochondrial functional readout of carvedilol-pretreated cells mimicked the readout of cells overexpressing the major regulator of mitochondrial biogenesis, PGC-1α. Carvedilol pretreatment reduces mitochondrial oxidants, decreases cell death in both H9c2 cells and human iPSC-CM and maintains the cellular 'redox poise' as determined by sustained expression of the redox sensor Keap1 and prevention of DOX-induced Nrf2 nuclear translocation. These results indicate that, in addition to the already known ROS-scavenging effects, carvedilol has a hitherto unrecognized pro-reducing property against the oxidizing conditions induced by DOX treatment, the sequalae of DOX-induced mitochondrial dysfunction and compromised cell viability. The novel findings of our preclinical studies suggest future trial design of carvedilol prophylaxis, such as prescreening for redox state, might be an alternative strategy for preventing oxidative stress writ large in lieu of the current lack of clinical evidence for ROS-scavenging agents.