Outcomes of COVID-19 in Patients With a History of Cancer and Comorbid Cardiovascular Disease.

BACKGROUND: Cancer and cardiovascular disease (CVD) are independently associated with adverse outcomes in patients with COVID-19. However, outcomes in patients with COVID-19 with both cancer and comorbid CVD are unknown. METHODS: This retrospective study included 2,476 patients who tested positive for SARS-CoV-2 at 4 Massachusetts hospitals between March 11 and May 21, 2020. Patients were stratified by a history of either cancer (n=195) or CVD (n=414) and subsequently by the presence of both cancer and CVD (n=82). We compared outcomes between patients with and without cancer and patients with both cancer and CVD compared with patients with either condition alone. The primary endpoint was COVID-19-associated severe disease, defined as a composite of the need for mechanical ventilation, shock, or death. Secondary endpoints included death, shock, need for mechanical ventilation, need for supplemental oxygen, arrhythmia, venous thromboembolism, encephalopathy, abnormal troponin level, and length of stay. RESULTS: Multivariable analysis identified cancer as an independent predictor of COVID-19-associated severe disease among all infected patients. Patients with cancer were more likely to develop COVID-19-associated severe disease than were those without cancer (hazard ratio [HR], 2.02; 95% CI, 1.53-2.68; P<.001). Furthermore, patients with both cancer and CVD had a higher likelihood of COVID-19-associated severe disease compared with those with either cancer (HR, 1.86; 95% CI, 1.11-3.10; P=.02) or CVD (HR, 1.79; 95% CI, 1.21-2.66; P=.004) alone. Patients died more frequently if they had both cancer and CVD compared with either cancer (35% vs 17%; P=.004) or CVD (35% vs 21%; P=.009) alone. Arrhythmias and encephalopathy were also more frequent in patients with both cancer and CVD compared with those with cancer alone. CONCLUSIONS: Patients with a history of both cancer and CVD are at significantly higher risk of experiencing COVID-19-associated adverse outcomes. Aggressive public health measures are needed to mitigate the risks of COVID-19 infection in this vulnerable patient population.

Decreased metalloprotease 9 induction, cardiac fibrosis, and higher autophagy after pressure overload in mice lacking the transcriptional regulator p8.

Left ventricular remodeling, including the deposition of excess extracellular matrix, is key to the pathogenesis of heart failure. The stress-inducible transcriptional regulator p8 is increased in failing human hearts and is required both for agonist-stimulated cardiomyocyte hypertrophy and for cardiac fibroblasts matrix metalloprotease-9 (MMP9) induction. In the heart, upregulation of autophagy is an adaptive response to stress and plays a causative role in cardiomyopathies. We have recently shown that p8 ablation in cardiac cells upregulates autophagy and that, in vivo, loss of p8 results in a decrease of cardiac function. Here we investigated the effects of p8 genetic deletion in mediating adverse myocardial remodeling. Unstressed p8-/- mouse hearts manifested complex alterations in the expression of fibrosis markers. In addition, these mice displayed elevated autophagy and apoptosis compared with p8+/+ mice. Transverse aortic constriction (TAC) induced left ventricular p8 expression in p8+/+ mice. Pressure overload caused left ventricular remodeling in both genotypes, however, p8-/- mice showed less cardiac fibrosis induction. Consistent with this, although MMP9 induction was attenuated in the p8-/- mice, induction of MMP2 and MMP3 were strikingly upregulated while TIMP2 was downregulated. Left ventricular autophagy increased after TAC and was significantly higher in the p8-/- mice. Thus p8-deletion results in reduced collagen fibrosis after TAC, but in turn, is associated with a detrimental higher increase in autophagy. These findings suggest a role for p8 in regulating in vivo key signaling pathways involved in the pathogenesis of heart failure.

Parasympathetic response in chick myocytes and mouse heart is controlled by SREBP.

Parasympathetic stimulation of the heart, which provides protection from arrhythmias and sudden death, involves activation of the G protein-coupled inward rectifying K+ channel GIRK1/4 and results in an acetylcholine-sensitive K+ current, I KACh. We describe a unique relationship between lipid homeostasis, the lipid-sensitive transcription factor SREBP-1, regulation of the cardiac parasympathetic response, and the development of ventricular arrhythmia. In embryonic chick atrial myocytes, lipid lowering by culture in lipoprotein-depleted serum increased SREBP-1 levels, GIRK1 expression, and I KACh activation. Regulation of the GIRK1 promoter by SREBP-1 and lipid lowering was dependent on interaction with 2 tandem sterol response elements and an upstream E-box motif. Expression of dominant negative SREBP-1 (DN-SREBP-1) reversed the effect of lipid lowering on I KACh and GIRK1. In SREBP-1 knockout mice, both the response of the heart to parasympathetic stimulation and the expression of GIRK1 were reduced compared with WT. I KACh, attenuated in atrial myocytes from SREBP-1 knockout mice, was stimulated by SREBP-1 expression. Following myocardial infarction, SREBP-1 knockout mice were twice as likely as WT mice to develop ventricular tachycardia in response to programmed ventricular stimulation. These results demonstrate a relationship between lipid metabolism and parasympathetic response that may play a role in arrhythmogenesis.

Estrogen attenuates left ventricular and cardiomyocyte hypertrophy by an estrogen receptor-dependent pathway that increases calcineurin degradation.

Left ventricular (LV) hypertrophy commonly develops in response to chronic hypertension and is a significant risk factor for heart failure and death. The serine-threonine phosphatase calcineurin (Cn)A plays a critical role in the development of pathological hypertrophy. Previous experimental studies in murine models show that estrogen limits pressure overload-induced hypertrophy; our purpose was to explore further the mechanisms underlying this estrogen effect. Wild-type, ovariectomized female mice were treated with placebo or 17beta-estradiol (E2), followed by transverse aortic constriction (TAC), to induce pressure overload. At 2 weeks, mice underwent physiological evaluation, immediate tissue harvest, or dispersion of cardiomyocytes. E2 replacement limited TAC-induced LV and cardiomyocyte hypertrophy while attenuating deterioration in LV systolic function and contractility. These E2 effects were associated with reduced abundance of CnA. The primary downstream targets of CnA are the nuclear factor of activated T-cell (NFAT) family of transcription factors. In transgenic mice expressing a NFAT-activated promoter/luciferase reporter gene, E2 limited TAC-induced activation of NFAT. Moreover, the inhibitory effects of E2 on LV hypertrophy were absent in CnA knockout mice, supporting the notion that CnA is an important target of E2-mediated inhibition. In cultured rat cardiac myocytes, E2 inhibited agonist-induced hypertrophy while also decreasing CnA abundance and NFAT activation. Agonist stimulation also reduced CnA ubiquitination and degradation that was prevented by E2; all in vitro effects of estrogen were reversed by an estrogen receptor (ER) antagonist. These data support that E2 reduces pressure overload induced hypertrophy by an ER-dependent mechanism that increases CnA degradation, unveiling a novel mechanism by which E2 and ERs regulate pathological LV and cardiomyocyte growth.

Increased FOG-2 in failing myocardium disrupts thyroid hormone-dependent SERCA2 gene transcription.

Reduced expression of sarcoplasmic reticulum calcium ATPase (SERCA)2 and other genes in the adult cardiac gene program has raised consideration of an impaired responsiveness to thyroid hormone (T3) that develops in the advanced failing heart. Here, we show that human and murine cardiomyopathy hearts have increased expression of friend of GATA (FOG)-2, a cardiac nuclear hormone receptor corepressor protein. Cardiac-specific overexpression of FOG-2 in transgenic mice led to depressed cardiac function, activation of the fetal gene program, congestive heart failure, and early death. SERCA2 transcript and protein levels were reduced in FOG-2 transgenic hearts, and FOG-2 overexpression impaired T3-mediated SERCA2 expression in cultured cardiomyocytes. FOG-2 physically interacts with thyroid hormone receptor-alpha1 and abrogated even high levels of T3-mediated SERCA2 promoter activity. These results demonstrate that SERCA2 is an important target of FOG-2 and that increased FOG-2 expression may contribute to a decline in cardiac function in end-stage heart failure by impaired T3 signaling.

Helix-loop-helix protein p8, a transcriptional regulator required for cardiomyocyte hypertrophy and cardiac fibroblast matrix metalloprotease induction.

Cardiomyocyte hypertrophy and extracellular matrix remodeling, primarily mediated by inflammatory cytokine-stimulated cardiac fibroblasts, are critical cellular events in cardiac pathology. The molecular components governing these processes remain nebulous, and few genes have been linked to both hypertrophy and matrix remodeling. Here we show that p8, a small stress-inducible basic helix-loop-helix protein, is required for endothelin- and alpha-adrenergic agonist-induced cardiomyocyte hypertrophy and for tumor necrosis factor-stimulated induction, in cardiac fibroblasts, of matrix metalloproteases (MMPs) 9 and 13-MMPs linked to general inflammation and to adverse ventricular remodeling in heart failure. In a stimulus-dependent manner, p8 associates with chromatin containing c-Jun and with the cardiomyocyte atrial natriuretic factor (anf) promoter and the cardiac fibroblast mmp9 and mmp13 promoters, established activator protein 1 effectors. p8 is also induced strongly in the failing human heart by a process reversed upon therapeutic intervention. Our results identify an unexpectedly broad involvement for p8 in key cellular events linked to cardiomyocyte hypertrophy and cardiac fibroblast MMP production, both of which occur in heart failure.

Risk and predictors of dyssynchrony cardiomyopathy in left bundle branch block with preserved left ventricular ejection fraction.

BACKGROUND: Left bundle branch block (LBBB) and left ventricular (LV) dyssynchrony likely contribute to progressive systolic dysfunction. The evaluation of newly recognized LBBB includes screening for structural heart abnormalities and coronary artery disease (CAD). In patients whose LV ejection fraction (EF) is preserved during initial testing, the incidence of subsequent cardiomyopathy is not firmly established. HYPOTHESIS: The risk of developing LV systolic dysfunction among LBBB patients with preserved LVEF is high enough to warrant serial imaging. METHODS: We screened records of 1000 consecutive patients with LBBB from our ECG database and identified subjects with an initially preserved LVEF (≥45%) without clinically relevant CAD or other cause for cardiomyopathy. Baseline imaging, clinical data, and follow-up imaging were recorded to determine the risk of subsequent LV systolic dysfunction (LVEF ≤40%). RESULTS: (Data are mean + SD) 784 subjects were excluded, the majority for CAD or depressed LVEF upon initial imaging. Of the remaining 216, 37 (17%) developed a decline in LVEF(≤40%) over a mean follow-up of 55 ± 31 months; 94% of these patients had a baseline LVEF≤60% and LV end systolic diameter (ESD) ≥ 2.9 cm indicating that these measures may be useful to define which patients warrant longitudinal follow-up. The negative predictive value of a LVEF>60% and LVESD <2.9 cm was 98%. CONCLUSIONS: Seventeen percent of patients with LBBB and initial preserved LVEF develop dyssynchrony cardiomyopathy. We believe the risk of developing dyssynchrony cardiomyopathy is high enough to warrant serial assessment of LV systolic function in this high-risk population.

Outcomes of Impella CP insertion during cardiac arrest: A single center experience.

OBJECTIVES: We sought to determine the outcomes of patients with an Impella CP percutaneous mechanical circulatory support (MCS) device deployed during a cardiac arrest. BACKGROUND: The Impella CP device is indicated for left ventricular support in patients with cardiogenic shock. The utility of percutaneous MCS in the setting of cardiac arrest during cardiopulmonary resuscitation (CPR) remains unclear. METHODS: We retrospectively examined data from patients supported with an Impella CP device for cardiogenic shock complicated by cardiac arrest between April 2015 and April 2017 at a single academic medical center. Patients with cardiac arrest who underwent Impella CP placement during CPR were compared to those who had return of spontaneous circulation (ROSC) prior to Impella CP placement. RESULTS: We identified 22 patients with cardiogenic shock complicated by cardiac arrest (average age 64 years, 23% female) who underwent placement of an Impella CP device. The majority of patients (68%) underwent support for cardiogenic shock secondary to an acute myocardial infarction. Seven of the 22 patients (32%) underwent Impella CP placement during CPR and 15 (68%) underwent Impella CP insertion following ROSC. The in-hospital mortality was 86% in the group of patients who had the Impella CP placed during CPR and 56% in the group with ROSC prior to Impella CP insertion, (p = 0.19). CONCLUSIONS: Based on our single center retrospective analysis, the mortality rate of patients undergoing placement of an Impella CP during CPR is 86%. Further study is necessary to better understand the utility of the Impella CP mechanical circulatory support device during a cardiac arrest.

Management of Cardiovascular Disease During Coronavirus Disease (COVID-19) Pandemic.

Patients with pre-existing cardiovascular disease and risk factors are more likely to experience adverse outcomes associated with the novel coronavirus disease-2019 (COVID-19). Additionally, consistent reports of cardiac injury and de novo cardiac complications, including possible myocarditis, arrhythmia, and heart failure in patients without prior cardiovascular disease or significant risk factors, are emerging, possibly due to an accentuated host immune response and cytokine release syndrome. As the spread of the virus increases exponentially, many patients will require medical care either for COVID-19 related or traditional cardiovascular issues. While the COVID-19 pandemic is dominating the attention of the healthcare system, there is an unmet need for a standardized approach to deal with COVID-19 associated and other traditional cardiovascular issues during this period. We provide consensus guidance for the management of various cardiovascular conditions during the ongoing COVID-19 pandemic with the goal of providing the best care to all patients and minimizing the risk of exposure to frontline healthcare workers.

Gene 33/RALT is induced by hypoxia in cardiomyocytes, where it promotes cell death by suppressing phosphatidylinositol 3-kinase and extracellular signal-regulated kinase survival signaling.

Ischemia in the heart deprives cardiomyocytes of oxygen, triggering cell death (myocardial infarction). Ischemia and its cell culture model, hypoxia, elicit a stress response program that contributes to cardiomyocyte death; however, the molecular components required to promote this process remain nebulous. Gene 33 is a 50-kDa cytosolic adapter protein that suppresses signaling from receptor Tyr kinases of the epidermal growth factor receptor/ErbB family. Here we show that adenoviral expression of Gene 33 swiftly stimulates cardiomyocyte death coincident with reduced Akt and extracellular signal-regulated kinase (ERK) signaling. Subjecting cardiomyocytes to hypoxia and then reoxygenation induces gene 33 mRNA and Gene 33 protein. RNA interference experiments indicate that endogenous Gene 33 reduces Akt and ERK signaling and is required for maximal hypoxia-induced cardiomyocyte death. Gene 33 levels are also strikingly increased in myocardial ischemic injury and infarction. Our results identify a new role for Gene 33 as a component in the molecular pathophysiology of ischemic injury.

17 Beta-estradiol differentially affects left ventricular and cardiomyocyte hypertrophy following myocardial infarction and pressure overload.

BACKGROUND: We have shown previously that 17beta-estradiol (E2) increases left ventricular (LV) and cardiomyocyte hypertrophy after myocardial infarction (MI). However, E2 decreases hypertrophy in pressure overload models. We hypothesized that the effect of estrogen on cardiac hypertrophy was dependent on the type of hypertrophic stimulus. METHODS AND RESULTS: Ovariectomized wild-type female mice (n = 192) were given vehicle or E2 treatment followed by coronary ligation (MI), transverse aortic constriction (TAC), or sham operation. Signaling pathway activation was studied at 3, 24, and 48 hours, whereas echocardiography and hemodynamic studies were performed at 14 days. MI induced early but transient activation of p38 and p42/44 MAPK pathways, whereas TAC induced sustained activation of both pathways. E2 had no effect on these pathways, but increased Stat3 activation after MI while decreasing Stat3 activation after TAC. MI caused LV dilation and decreased fractional shortening (FS) that were unaltered by E2. TAC caused LV dilation, reduced FS, and increased LV mass, but in this model, E2 improved these parameters. After MI, E2 led to increases in myocyte cross-sectional area, atrial natriuretic peptide (ANP) and beta-myosin heavy chain (MHC) gene expression, but E2 diminished TAC-induced increases ANP and beta-MHC gene expression. CONCLUSIONS: These data demonstrate that the effects of E2 on LV and myocyte remodeling depend on the nature of the hypertrophic stimulus. The opposing influence of E2 on hypertrophy in these models may, in part, result from differential effects of E2 on Stat3 activation. Further work will be necessary to explore this and other potential mechanisms by which estrogen affects hypertrophy in these models.

Estrogen replacement and cardiomyocyte protection.

The effects of estrogen on vascular function have been studied extensively; however, much less is known regarding the effect of estrogen on myocardial function and cardiomyocyte biology. We recently examined the effects of estrogen on infarct size and left ventricular remodeling after induction of myocardial infarction by permanent coronary ligation in ovariectomized female mice. These studies demonstrated that physiologic replacement with 17beta-estradiol (E(2)) reduced infarct size and reduced cardiomyocyte apoptosis at 24 and 72 hours post-myocardial infarction. In vivo, physiologic E(2) replacement rapidly activated the Akt signaling pathway within the myocardium. In vitro, physiologic concentrations of E(2) rapidly activated Akt via estrogen receptor alpha (ERalpha) and phosphoinositide-3 (PI3)-kinase-dependent mechanisms. Moreover, estrogen mitigated anthracycline-induced apoptosis in vitro via ER- and PI3-kinase-Akt-dependent mechanisms. Our data therefore support that estrogen favorably influences cardiomyocyte survival both in a coronary occlusion model in vivo and in cultured cardiomyocytes in vitro. Further work is necessary to more completely understand the complex effects of sex hormones on cardiomyocyte biology.

Models of Gender Differences in Cardiovascular Disease.

Clinical observations made over several decades support the existence of gender differences in cardiovascular disease prevalence and severity. For example, women exhibit a delay in the onset of vascular disease compared to men and the temporal link between menopause and the rise in vascular events in women suggests that ovarian hormones may be important in reducing the risk of vascular disease in women. Gender differences have also been observed in the severity and outcome of myocardial diseases such that women with heart failure have a better prognosis than men coupled with gender-specific patterns of ventricular remodeling. These clinical observations have fostered great interest in understanding the mechanisms of gender differences in cardiovascular diseases with the goal being to identify novel therapeutic targets. The purpose of this review is to describe animal models of cardiovascular disease that have demonstrated clear gender differences in the pathophysiologic responses to a given stimulus. Animal models from two broad areas of cardiovascular investigation will be highlighted: vascular disease and heart failure.

Ventricular assist device therapy normalizes inducible nitric oxide synthase expression and reduces cardiomyocyte apoptosis in the failing human heart.

OBJECTIVES: We examined the effect of mechanical unloading with ventricular assist device (VAD) therapy on myocardial inducible nitric oxide synthase (iNOS) expression and cardiomyocyte apoptosis in patients with end-stage heart failure (HF). BACKGROUND: Despite advances in medical therapy, HF continues to be a progressive and ultimately fatal disorder. High levels of iNOS expression are present in the myocardium of failing hearts, suggesting a potential role for iNOS in HF progression. METHODS: Inducible NOS protein expression was analyzed by Western blotting and cardiomyocyte apoptosis by terminal deoxynucleotidyltransferase dUTP nick end-labeling (TUNEL) in myocardial samples from failing hearts. Included in these analyses were tissues from 9 patients at the time of transplantation (HF-transplant group), 10 patients at the time of VAD insertion (pre-VAD group), and 11 patients undergoing transplant after VAD support (post-VAD group). Seven control samples were obtained at autopsy. RESULTS: Low or undetectable levels of iNOS were present in controls (0.005 +/- 0.002). The HF-transplant and pre-VAD myocardial specimens exhibited a marked increase in iNOS expression (1.48 +/- 0.34 and 1.29 +/- 0.26, respectively; p < 0.01 for both vs. controls). The increase in iNOS expression was reversed in the post-VAD group (0.36 +/- 0.16; p < 0.01 vs. HF-transplant and pre-VAD groups). The rate of TUNEL-positive cardiomyocytes was high in the pre-VAD group and significantly lower in the post-VAD group (0.64 +/- 0.15% in pre-VAD group and 0.16 +/- 0.07% in post-VAD group; p < 0.01). The iNOS levels correlated significantly with cardiomyocyte apoptosis (r = 0.66, p < 0.01). CONCLUSIONS: Therapy with VAD normalizes iNOS expression in association with diminished cardiomyocyte apoptosis in the failing heart. Further work is required to define whether a causal relationship exists between iNOS and cardiomyocyte apoptosis.

17beta-estradiol reduces cardiomyocyte apoptosis in vivo and in vitro via activation of phospho-inositide-3 kinase/Akt signaling.

Female gender and estrogen-replacement therapy in postmenopausal women are associated with improved heart failure survival, and physiological replacement of 17beta-estradiol (E2) reduces infarct size and cardiomyocyte apoptosis in animal models of myocardial infarction (MI). Here, we characterize the molecular mechanisms of E2 effects on cardiomyocyte survival in vivo and in vitro. Ovariectomized female mice were treated with placebo or physiological E2 replacement, followed by coronary artery ligation (placebo-MI or E2-MI) or sham operation (sham) and hearts were harvested 6, 24, and 72 hours later. After MI, E2 replacement significantly increased activation of the prosurvival kinase, Akt, and decreased cardiomyocyte apoptosis assessed by terminal deoxynucleotidyltransferase dUTP nick-end labeling (TUNEL) staining and caspase 3 activation. In vitro, E2 at 1 or 10 nmol/L caused a rapid 2.7-fold increase in Akt phosphorylation and a decrease in apoptosis as measured by TUNEL staining, caspase 3 activation, and DNA laddering in cultured neonatal rat cardiomyocytes. The E2-mediated reduction in apoptosis was reversed by an estrogen receptor (ER) antagonist, ICI 182,780, and by phospho-inositide-3 kinase inhibitors, LY294002 and Wortmannin. Overexpression of a dominant negative-Akt construct also blocked E2-mediated reduction in cardiomyocyte apoptosis. These data show that E2 reduces cardiomyocyte apoptosis in vivo and in vitro by ER- and phospho-inositide-3 kinase-Akt-dependent pathways and support the relevance of these pathways in the observed estrogen-mediated reduction in myocardial injury.

17-beta-estradiol increases cardiac remodeling and mortality in mice with myocardial infarction.

OBJECTIVES: This study was designed to examine the effects of estrogen replacement on infarct size, ventricular remodeling, and mortality after myocardial infarction (MI) in mice. BACKGROUND: Observational and clinical studies suggest that the cardiovascular effects of hormone replacement therapy can differ depending on the patient population studied. No prospective studies have examined the effect of estrogen on outcomes following MI. We now examine the effects of estrogen replacement on infarct size, ventricular remodeling, and mortality after MI in mice. METHODS: Myocardial infarction was induced by left coronary artery ligation in ovariectomized female mice treated with 17-beta-estradiol (E2) or placebo. At either one day or six weeks after MI, hemodynamic function was assessed, animals were euthanized, and infarct size was determined. RESULTS: 17-beta-estradiol-treated mice had smaller infarcts than placebo-treated animals both one day (18% decrease; p < 0.01), and six weeks (14% decrease; p < 0.05) following MI. E2 reduced cardiomyocyte apoptosis as assessed by the terminal deoxynucleotidyl transferase uridine nucleotide end-labeling method (50% reduction, p < 0.05) and caspase 3 activation (33% reduction, p < 0.05). Despite having smaller infarcts, however, left ventricular mass increased more in the E2-treated animals (16% greater; p < 0.01). Left ventricular weight was positively correlated with infarct size in the estrogen-treated animals (R2 = 0.79, p = 0.0001). 17-beta-estradiol treatment also significantly increased mortality in the infarcted animals (relative risk of death = 2.4; 95% confidence interval 1.2 to 5.3). CONCLUSIONS: Estrogen replacement therapy reduces infarct size and cardiomyocyte apoptosis in mice. However, estrogen increased post-MI ventricular remodeling and mortality. Further studies will be necessary to elucidate the mechanisms underlying the complex effects of estrogen observed in the present study.

New concepts in post-infarction ventricular remodeling.

An understanding of the process of left ventricular (LV) remodeling has led to greater knowledge of the pathophysiology of heart failure syndrome. This article examines the relationship between LV remodeling and clinical outcomes of heart failure syndrome from several different perspectives. The studies cited suggest that the post-myocardial infarction process is related to and associated with long-term progression of LV dysfunction, heart failure symptoms, and mortality. It is also demonstrated that drug therapies that slow or reverse the remodeling process appear to have favorable natural history effects in the short term as well as during long-term therapy.

Use of pulse wave and color flow Doppler echocardiography in mouse models of human disease.

The noninvasive assessment of cardiovascular physiology in mice is challenging because of their small size and extremely rapid heart rates. In this study, we sought to determine the feasibility and utility of pulse wave (PW) and color flow Doppler imaging techniques when applied to mouse models of cardiac remodeling. We performed transverse aortic banding, induced aortic insufficiency (AI), or sham procedures in wild-type mice. Animals were anesthetized and transthoracic echocardiography was performed, including PW and color flow Doppler imaging. In aortic banded mice, color flow Doppler imaging was used to identify flow around the aortic arch, and PW measurements were performed distal to the constriction. A high-velocity jet across the aortic constriction was detected in all 4 banded animals. Both modalities were applied to AI mice in which AI was detected in all 5 mice but in none of the 5 shams. Pulse wave and color flow Doppler imaging were also used to screen senescent mice for valve abnormalities; AI was detected in 3 of 20 and mitral regurgitation in 2 of 20. We demonstrate here that PW and color flow Doppler imaging techniques are useful in the evaluation of mouse models of cardiac remodeling. In addition, this study indicates that these modalities may be potentially useful to screen transgenic mice for valve abnormalities.

Deficiency of the transcriptional regulator p8 results in increased autophagy and apoptosis, and causes impaired heart function.

Autophagy is a cytoprotective pathway used to degrade and recycle cytoplasmic content. Dysfunctional autophagy has been linked to both cancer and cardiomyopathies. Here, we show a role for the transcriptional regulator p8 in autophagy. p8 RNA interference (RNAi) increases basal autophagy markers in primary cardiomyocytes, in H9C2 and U2OS cells, and decreases cellular viability after autophagy induction. This autophagy is associated with caspase activation and is blocked by atg5 silencing and by pharmacological inhibitors. FoxO3 transcription factor was reported to activate autophagy by enhancing the expression of autophagy-related genes. P8 expression represses FoxO3 transcriptional activity, and p8 knockdown affects FoxO3 nuclear localization. Thus, p8 RNAi increases FoxO3 association with bnip3 promoter, a known proautophagic FoxO3 target, resulting in higher bnip3 RNA and protein levels. Accordingly, bnip3 knockdown restores cell viability and blocks apoptosis of p8-deficient cells. In vivo, p8 -/- mice have higher autophagy and express higher cardiac bnip3 levels. These mice develop left ventricular wall thinning and chamber dilation, with consequent impaired cardiac function. Our studies provide evidence of a p8-dependent mechanism regulating autophagy by acting as FoxO3 corepressor, which may be relevant for diseases associated with dysregulated autophagy, as cardiovascular pathologies and cancer.