Left Ventricular Anterior Wall Thickness Research Articles

Empagliflozin ameliorates ventricular arrhythmias by inhibiting sympathetic remodeling via nerve growth factor/tyrosine kinase receptor A pathway inhibition.

Sodium-glucose cotransporter 2 inhibitors (SGLT2is) can ameliorate arrhythmias; however, the mechanisms underlying their antiarrhythmic effect remain unclear. Therefore, we aimed to test the hypothesis that the SGLT2i empagliflozin (EMPA) ameliorates ventricular arrhythmias caused by myocardial infarction (MI) by inhibiting sympathetic remodeling. Male nondiabetic Sprague-Dawley rats were divided into Sham ( n = 10), MI ( n = 13), low-EMPA (10 mg/kg/day; n = 13), and high-EMPA (30 mg/kg/day; n = 13) groups. Except for the Sham group, MI models were established by ligation of the left anterior descending coronary artery. After 4 weeks, the hearts were removed. Echocardiography, electrical stimulation, hematoxylin-eosin staining and Masson's staining, Western blotting, immunohistochemistry (IHC), and ELISA were performed. Except for left ventricular posterior wall thickness (LVPWT), EMPA treatment significantly ameliorated the left ventricular anterior wall thickness (LVAWT), interventricular septum thickness (IVST), left ventricular end-diastolic diameter (LVEDD), left ventricular end-systolic diameter (LVESD), and left ventricular ejection fraction (LVEF) in MI rats; there was no statistical difference between the low-EMPA and high-EMPA groups. The threshold for ventricular fibrillation induction and myocardial fibrosis was significantly ameliorated in EMPA-treated rats, and there was no statistical difference between the high-EMPA and low-EMPA groups. EMPA decreased the expression of nerve growth factor (NGF), tyrosine kinase receptor A (TrkA), tyrosine hydroxylase, and growth-associated protein 43 (GAP43) in the left ventricular infarction margin myocardium of MI rats, especially in the high-EMPA group, with a statistically significant difference between the high-EMPA and low-EMPA groups. High-EMPA significantly decreased noradrenaline (NE) levels in the blood of MI rats; however, there was no statistical difference between the low-EMPA and MI groups. EMPA ameliorated the occurrence of ventricular arrhythmias in MI rats, which may be related to a reduction in sympathetic activity, inhibition of the NGF/TrkA pathway, inhibition of sympathetic remodeling, and improvement in cardiac function and cardiac structural remodeling.

Advanced maternal age alters cardiac functional and structural adaptations to pregnancy in rats.

A significant number of pregnancies occur at advanced maternal age (>35 yr), which is a risk factor for pregnancy complications. Healthy pregnancies require massive hemodynamic adaptations, including an increased blood volume and cardiac output. There is growing evidence that these cardiovascular adaptations are impaired with age, however, little is known about maternal cardiac function with advanced age. We hypothesized that cardiac adaptations to pregnancy are impaired with advanced maternal age. Younger (4 mo; ∼early reproductive maturity in humans) and aged (9 mo; ∼35 yr in humans) pregnant Sprague-Dawley rats were assessed and compared with age-matched nonpregnant controls. Two-dimensional echocardiographic images were obtained (ultrasound biomicroscopy; under anesthesia) on gestational day 19 (term = 22 days) and compared with age-matched nonpregnant rats (n = 7-9/group). Left ventricular structure and function were assessed using short-axis images and transmitral Doppler signals. During systole, left ventricular anterior wall thickness increased with age in the nonpregnant rats, but there was no age-related difference between the pregnant groups. There were no significant pregnancy-associated differences in left ventricular wall thickness. Calculated left ventricular mass increased with age in nonpregnant rats and increased with pregnancy only in young rats. Compared with young pregnant rats, the aortic ejection time of aged pregnant rats was greater and Tei index was lower. Overall, the greater aortic ejection time and lower Tei index with age in pregnant rats suggest mildly altered cardiac adaptations to pregnancy with advanced maternal age, which may contribute to adverse outcomes in advanced maternal age pregnancies.NEW & NOTEWORTHY We demonstrated that even before the age of reproductive senescence, rats show signs of age-related alterations in cardiac structure that suggests increased cardiac work. Our data also demonstrate, using an in vivo echocardiographic approach, that advanced maternal age in a rat model is associated with altered cardiac function and structure relative to younger pregnant controls.

Abstract 13816: Clearing P16+ Cells Prevents Cardiac Dysfunction and Death in Mice With Acute Myocardial Infarction

Introduction: Cellular senescence, a stress and age-related response, is often characterized by p16 expression in p16 positive (p16 + ) senescent cells. Senescent cells secrete profibrotic and proinflammatory factors as parts of a “senescence associated secretory phenotype”. The role of cellular senescence in myocardial infarction (MI) is unclear. Aims: To study the effect of p16 + cell clearance on survival, cardiac remodeling and function after MI. Methods: We used INK ATTAC transgenic mice, in which p16 + cells undergo targeted apoptosis upon exposure to a dimerizer, AP20187 (AP). MI mice were treated with AP or vehicle (V), twice a week for 1 month, beginning 3-4 hours post-MI. Cardiac function and structure were evaluated with echocardiography, hemodynamic parameters with a Millar catheter, infarct area with Masson’s Trichrome, gene expression with qPCR and single-nucleus RNA-sequencing (snRNAseq). Results: Survival post MI was dramatically increased in MI-AP vs MI-V mice (P<0.001, Fig A), primarily via prevention of cardiac rupture (CardRup). Left ventricular (LV) ejection fraction (EF%) and LV anterior wall thickness at end diastole (LVAWd) decreased in MI-V vs Sham and improved in MI-AP mice (Fig B), indicating preservation of cardiac function and structure with p16 + cell clearance. Hemodynamic indices of LV function (max and min dP/dt) improved with AP (Fig C). Fibrosis-related gene expression (Col1a1, Col3a1 and Lox; Fig D) increased with MI and improved with AP, paralleling changes in infarct size (Fig E). snRNAseq showed that genes were principally upregulated in MI-V macrophages and neutrophils; significant responses were seen in TNF-α, inflammatory response pathways and gene programs associated with CardRup (Fig F). Conclusion: These results suggest that p16 + cells play a significant role in the evolution of MI, apparently by modulating inflammatory signaling, pointing to an important pathophysiological role of cellular senescence.

Abstract 13336: Myocardial Protection of Chitosan Cardiac Muscle Patch in Myocardial Infarcted Mice

Background: Poor grafted rate of human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) via direct injection into the myocardium limits the efficacy of cardiac repair after myocardial infarction (MI). Chitosan-based scaffolds has regarded as functional biomaterial for designing delivery systems in cardiac therapies. This study aimed to enhancing the potency of cardiac repair with the hiPSC-CMs loaded chitosan cardiac patch (hCCMP). Methods: The patches were fabricated with chitosan. Characterization of the chitosan patches was evaluated through the detection of swelling rate and porosity. Biocompatibility of the hiPSC-CMs loaded patches was analysed by scanning electron microscope (SEM) and CCK8 assay. The mice were randomly divided into 4 groups (n=10 for each). Animals underwent MI-inductive surgery followed by epicardium implantation of hCCMP or Empty-patch (without hiPSC-CMs); Sham and MI mice without further intervention were set as control. 4 weeks after MI, heart function was measured via echocardiography. Engraftment was evaluated with human cardiac troponin T staining. Infarction size, left ventricular anterior wall thickness, cardiac remodeling, angiogenesis, arterialization and apoptosis was detected via immunofluorescence in infarcted boder area. Results: SEM showed that the chitosan patch had regular pore size and good 3D structure; porosity was about (96.7±0.37)%. On day3, the patch swelling rate was about (715±64.55)%. SEM, CCK8 assay showed a normal cells growth in the chitosan patch. The hiPSC-CMs grafted well with chitosan patch delivery systems and was associated with significantly improvement in LV heart function, infarction size, LV anterior wall thickness, cardiac remodeling, angiogenesis and cardiomyocyte apoptosis 4 weeks after MI. Conclusions: The 3D chitosan cardiac patch with hiPSC-CMs loaded can enhance the potency of cardiac repair after MI and present a novel and promising therapic strategy.

Dose additive maternal and offspring effects of oral maternal exposure to a mixture of three PFAS (HFPO-DA, NBP2, PFOS) during pregnancy in the Sprague-Dawley rat

Simultaneous exposure to multiple per- and polyfluoroalkyl substances (PFAS) is common in humans across the globe. Individual PFAS are associated with adverse health effects, yet the nature of mixture effects after exposure to two or more PFAS remains unclear. Previously we reported that oral administration of hexafluoropropylene oxide-dimer acid (HFPO-DA, or GenX), Nafion byproduct 2 (NBP2), or perfluorooctane sulfonate (PFOS) individually during pregnancy produced maternal and F1 effects. Here, we hypothesized that responses to the combined exposure to these three PFAS would be dose additive. Pregnant Sprague-Dawley rats were exposed to a fixed-ratio equipotent mixture where the top dose contained each PFAS at their ED50 for neonatal mortality (100 % dose = PFOS 3 mg/kg; NBP2 10 mg/kg; HFPO-DA 110 mg/kg), followed by a dilution series (33.3, 10, 3.3, and 1 %) and vehicle controls (0 % dose). Consistent with the single chemical studies, dams were exposed from gestation day (GD)14–18 or from GD8-postnatal day (PND2). Fetal and maternal livers on GD18 displayed multiple significantly upregulated genes associated with lipid and carbohydrate metabolism at all dose levels, while dams displayed significantly increased liver weight (≥3.3 % dose) and reduced serum thyroid hormones (≥33.3 % dose). Maternal exposure from GD8-PND2 significantly reduced pup bodyweights at birth (≥33.3 % dose) and PND2 (all doses), increased neonatal liver weights (≥3.3 % dose), increased pup mortality (≥3.3 % dose), and reduced maternal bodyweights and weight gain at the top dose. Echocardiography of adult F1 males and females identified significantly increased left ventricular anterior wall thickness (~10 % increase), whereas other cardiac morphological, functional, and transcriptomic measures were unaffected. Mixture effects in maternal and neonatal animals conformed to dose addition using a relative potency factor (RPF) analysis. Results support dose addition-based cumulative assessment approaches for estimating combined effects of PFAS co-exposure.

Xuesaitong promotes myocardial angiogenesis in myocardial infarction mice by inhibiting MiR-3158-3p targeting Nur77.

This study aims to investigate the regulatory effect of Xuesaitong (XST) and miR-3158-3p on angiogenesis. All mice were randomly assigned into Sham group, Model group, XST group, XST + miR-3158-3P-overexpression (miRNA-OE) group. XST was found to increase the left ventricular anterior wall thickness at end diastole and end systole (LVAWd and LVAWs), left ventricular internal dimension at end diastole and end systole (LVIDd and LVIDs), fractional shortening (FS), and ejection fraction (EF) and decrease the proportion of fibrotic areas in mice. In contrast to those in Sham group, the protein expressions of Nur77, p-PI3K, HIF-1α, VEGFs, COX-2 in the heart tissues of mice in Model group were elevated and further increased after XST treatment in comparison with those in Model group. Nur77-/- mice were utilized. It was found that XST enhanced cell viability through a methyl thiazolyl tetrazolium assay and facilitated angiogenesis in each group, as assessed by a catheter formation assay. Specifically, XST was shown to promote the formation of blood vessels. Moreover, the protein expression levels of Associated proteins in the heart tissues of Nur77-/- mice were dramatically reduced in mice in Model and XST group compared with those in WT mice. Additionally, the above-mentioned protein expressions in the heart tissues of Nur77-/- mice did not change significantly in mice in Model + miRNA-OE + XST group compared with those in WT mice, suggesting that miR-3158-3p can specifically inhibit the expression of Nur77. In conclusion, XST inhibits miR-3158-3p targeting Nur77 to facilitate myocardial angiogenesis in mice with myocardial infarction.

Abstract 11965: Cellular Senescence Produces Diastolic Dysfunction and Cardiac Hypertrophy With Aging in Mice

Background: Age is a major risk factor for heart failure with preserved ejection fraction (HFpEF); however, the underlying mechanisms are poorly understood. Cellular senescence is an aging and stress related response; senescent cells (SCs) secrete bioactive substances that produce a variety of pathological changes. The role of senescence in HFpEF is unknown. Objectives: To study the effect of targeted deletion of SCs on cardiac function, structure and left ventricular (LV) pressure in an aging mouse model of HFpEF. Methods: We studied INK ATTAC mice, in which SCs undergo targeted clearance following treatment with a dimerizing agent, AP20187 (AP). Mice were treated with blinded AP or vehicle from 12 months to 18 months of age. Cardiac function and structure were studied with echocardiography. Contractility parameters were measured with a Millar catheter. The percentage of SCs in different cardiac-cell populations was analyzed with the use of Fluorescence-Activated Cell Sorting (FACS). Results: From 12 to 18 months, LV mass/LV diameter at end diastole (LVDd) and the LV anterior wall thickness at end diastole (LVAWd) increased in the vehicle group while they decreased in the AP group (LV mass/LVDd: %Δvehicle=+7.9± 3%, %ΔAP=-2±1.2%, P=0.005; LVAWd: %Δvehicle=+5.3±2.5%, %ΔAP=-3.5±1.6%, P=0.007) (Fig1A, B). E/e’ (echo) and isovolumic relaxation time indicated diastolic dysfunction in vehicle mice, and improved with AP (Fig1C, D). GFP bicistronic with p16 indicated SCs; FACS-purified fibroblasts (FBs) showed reduced GFP fluorescence (P=0.056) in the AP group, whereas immune and endothelial cells were not affected, suggesting that the anti-HFpEF effects of SC-clearance might be mediated through the clearance of senescent FBs (Fig1E). Conclusions: Our study points to a significant role of SCs, likely senescent FBs, in the pathophysiology of HFpEF. Modulating senescence might provide the basis for novel therapeutic approaches to HFpEF prevention and/or therapy.

Assessment of the influence on left ventricle by potassium oxonate and hypoxanthine-induced chronic hyperuricemia.

Cellular cytoplasmic xanthine oxidase (XO)-mediated uric acid synthesis and extracellular excess uric acid exposure are both causes of cardiomyocytic injury under the condition of hyperuricemia (HUA). Potassium oxonate suppresses uric acid degradation to increase extracellular concentration, while hypoxanthine is the catalytic substrate of XO. We aimed to observe cardiac damage in a chronic HUA mouse model induced by potassium oxonate and hypoxanthine. The mouse model was established by the co-administration of potassium oxonate and hypoxanthine for eight weeks. Then, left ventricular parameters were examined by echocardiographic evaluation, and the heart tissues were harvested for further histopathological analysis. The results showed that plasma uric acid was persistently elevated in the model mice, which demonstrated the stable establishment of chronic HUA. The left ventricular anterior wall was significantly thickened in the model group compared with the blank control group. After the end of modeling, the left ventricular anterior wall thickness of the hyperuricemic mice increased compared with that of blank group. The histological analysis showed and myocardial structure disorganization in the model group compared with the blank control. The above cardiac impairment changes could be attenuated by allopurinol pretreatment. This study systematically assessed cardiac damage in a chronic HUA mouse model. In addition, it provides useful information for future HUA-associated heart injury mechanism investigation and therapeutic treatment evaluation.

Genetic mouse models of autism spectrum disorder present subtle heterogenous cardiac abnormalities.

Autism spectrum disorder (ASD) and congenital heart disease (CHD) are linked on a functional and genetic level. Most work has investigated CHD‐related neurodevelopmental abnormalities. Cardiac abnormalities in ASD have been less studied. We investigated the prevalence of cardiac comorbidities relative to ASD genetic contributors. Using high frequency ultrasound imaging, we screened 9 ASD‐related genetic mouse models (Arid1b (+/−), Chd8 (+/−), 16p11.2 (deletion), Sgsh (+/−), Sgsh (−/−), Shank3 Δexon 4–9 (+/−), Shank3 Δexon 4–9 (−/−), Fmr1 (−/−), Vps13b (+/−)), and pooled wild‐type littermates (WTs). We measured heart rate (HR), aorta diameter (AoD), thickness and thickening of the left‐ventricular (LV) anterior and posterior walls, LV chamber diameter, fractional shortening, stroke volume and cardiac output, mitral inflow Peak E and A velocity ratio, ascending aorta velocity time integral (VTI). Mutant groups presented small‐scale alterations in cardiac structure and function compared to WTs (LV anterior wall thickness and thickening, chamber diameter and fractional shortening, HR). A greater number of significant differences was observed among mutant groups than between mutant groups and WTs. Mutant groups differed primarily in structural measures (LV chamber diameter and anterior wall thickness, HR, AoD). The mutant groups with most differences to WTs were 16p11.2 (deletion), Fmr1 (−/−), Arid1b (+/−). The mutant groups with most differences from other mutant groups were 16p11.2 (deletion), Sgsh (+/−), Fmr1 (−/−). Our results recapitulate the associated clinical findings. The characteristic ASD heterogeneity was recapitulated in the cardiac phenotype. The type of abnormal measures (morphological, functional) can highlight common underlying mechanisms. Clinically, knowledge of cardiac abnormalities in ASD can be essential as even non‐lethal abnormalities impact normal development.Lay SummaryAutism spectrum disorder (ASD) and congenital heart disease (CHD) are linked functionally and genetically. ASD cardiac phenotyping is limited. We assessed the cardiac phenotype of 9 ASD‐related mouse models. We found subtle heterogenous cardiac abnormalities compared to controls, with more differences within ASD than between ASD and controls, mirroring clinical findings. Clinically, knowing the cardiac abnormalities in ASD is vital as even non‐lethal cardiac abnormalities can impact development.

Periplocymarin Alleviates Doxorubicin-Induced Heart Failure and Excessive Accumulation of Ceramides.

Doxorubicin-driven cardiotoxicity could result in dilated cardiomyopathy and heart failure (HF). Previously, we showed that periplocymarin exerted a cardiotonic role by promoting calcium influx and attenuating myocardial fibrosis induced by isoproterenol (ISO) by improving the metabolism of cardiomyocytes. However, the impact of periplocymarin on doxorubicin (DOX)-triggered cardiomyopathy has not been investigated. In the current study, C57BL/6 mice were randomly divided into three groups, namely, the control, DOX, and DOX+periplocymarin groups. The cardiac function and apoptosis were measured. Our results revealed that periplocymarin administration greatly improved the DOX-induced cardiac dysfunction manifested by the ejection fraction (EF%), fractional shortening (FS%), left ventricular posterior wall thickness (LVPW), left ventricular anterior wall thickness (LVAW), left ventricular (LV) mass, and attenuated DOX-induced cardiomyocyte apoptosis assessed by hematoxylin and eosin (H&E) staining, terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining, and western blotting. Further study using H9c2 cells revealed that the pretreatment of periplocymarin suppressed DOX-induced apoptosis evidenced by annexin V staining. Moreover, liquid chromatography with tandem mass spectrometry (LC-MS/MS) analysis demonstrated that DOX lead to an accumulation in serum ceramide, and the pre-treatment of periplocymarin could reverse this phenomenon. Network pharmacology also demonstrated that ceramide metabolism was involved in the process. Consistently, real-time PCR showed that periplocymarin significantly abolished the induction of the genes involved in the de novo synthesis of ceramide, i.e., CerS2, CerS4, CerS5, and CerS6, and the induction was attributed to the treatment of DOX. Collectively, these results suggested that periplocymarin reduced cardiomyocyte apoptosis to protect hearts from DOX-induced cardiotoxicity and the de novo synthesis of ceramides was involved in this process.

Abstract P391: Inhalation Of Airborne Particulate Matter Alters Cardiovascular Function Of Alzheimer-prone Mice

Air pollution has detrimental effects on cardiovascular and lung function, and the extent of its pathological consequences continues to be uncovered. Recently, air pollution has been implicated in the development of Alzheimer Disease (AD) progression. AD and heart failure are common co-morbidities, giving reason to believe that cardiovascular dysfunction may contribute to AD. A known contributor to cardiovascular dysfunction-particulate matter (PM 2.5 , < 2.5 μm diameter)—is a critical component of air pollution and is considered a risk factor for heart failure and AD development. This co-morbidity pattern and shared environmental risk factor prompted the hypothesis that PM 2.5 contributes to cardiovascular dysfunction in a transgenic mouse model of AD. We tested our hypothesis by subjecting 6-month-old transgenic (APP) and non-carrier wildtype (WT) male mice to filtered air (FA) or PM 2.5 for 5 days/week, 6 hours/day for 3 months (n = 34). Following exposure, echocardiography, pressure-volume (PV) loops, and respiratory mechanics were performed to detect cardiac and pulmonary changes associated with genotype and exposure conditions among the 3-month group. Echocardiography revealed left ventricular anterior wall thickness in systole was significantly elevated among PM-exposed APP mice compared to FA-exposed APP controls. PV data demonstrated significant reduced end-systolic elastance in PM-exposed mice compared to FA-exposed mice in both WT and APP mouse models, demonstrating impaired contractility. PV loops also showed that the time constant of isovolumetric relaxation was increased in PM-exposed compared to FA-exposed WT mice. APP mice experienced higher lung resistance and central airway resistance with an increasing dose of methacholine. Taken together, these findings indicate airborne particulate matter exposure causes cardiac and pulmonary dysfunction in a transgenic mouse model of AD.

Circular RNA POSTN Promotes Myocardial Infarction-Induced Myocardial Injury and Cardiac Remodeling by Regulating miR-96-5p/BNIP3 Axis

Myocardial infarction (MI) is the most prevalent cardiac disease with high mortality, leading to severe heart injury. Circular RNAs (circRNAs) are a new type of regulatory RNAs and participate in multiple pathological cardiac progressions. However, the role of circRNAs Postn (circPostn) in MI modulation remains unclear. Here, we aimed to explore the effect of circPostn on MI-induced myocardial injury and cardiac remodeling. We identified that the expression of circPostn was elevated in the plasma of MI patients, MI mouse model, and hypoxia and reoxygenation (H/R)-treated human cardiomyocytes. The depletion of circPostn significantly attenuated MI-related myocardium injury and reduced the infarct size in MI mouse model. The circPostn knockdown obviously enhanced left ventricular ejection fraction (LVEF) and left ventricular fraction shortening (LVFS) and inhibited left ventricular anterior wall thickness at diastole (LVAWd) and left ventricular posterior wall thickness at diastole (LVPWd). The depletion of circPostn was able to decrease MI-induced expression of collagen 1α1 and collagen 3α1 in the ventricular tissues of mice. The protein expression of collagen and α-smooth muscle actin (SMA) was up-regulated in MI mice and was inhibited by circPostn knockdown. Meanwhile, the expression of atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) was repressed by circPostn depletion in the ventricular tissues of MI mice. Besides, the circPostn depletion attenuated cardiomyocyte apoptosis in mice. Mechanically, circPostn served as a miR-96-5p sponge and miR-96-5p-targeted BNIP3 in human cardiomyocytes, in which circPostn up-regulated BNIP3 expression by targeting miR-96-5p. circPostn promoted H/R-induced cardiomyocyte injury by modulating miR-96-5p/BNIP3 axis. Thus, we conclude that circPostn contributes to MI-induced myocardial injury and cardiac remodeling by regulating miR-96-5p/BNIP3 axis. Our finding provides new insight into the mechanism by which circPostn regulates MI-related cardiac dysfunction. circPostn, miR-96-5p, and BNIP3 are potential targets for the treatment of MI-caused heart injury.

Helium Protects Against Lipopolysaccharide-Induced Cardiac Dysfunction in Mice via Suppressing Toll-Like Receptor 4-Nuclear Factor κB-Tumor Necrosis Factor-Alpha/ Interleukin-18 Signaling.

The nonanesthetic noble gas helium (He) can protect many organs against ischemia and reperfusion injury, such as liver and heart. However, the role of He on cardiac dysfunction during sepsis is not clear. In this study, we established a lipopolysaccharide (LPS)-induced cardiac dysfunction mouse model to examine the influence of He on the impaired cardiac function, and further investigated the possible innate immune mechanisms that may be involved. LPS induced left ventricular dysfunction and cavity enlargement, as indicated by decreased percent ejection fraction, percent fractional shortening, left ventricular anterior wall thickness in systole, and left ventricular posterior wall thickness in systole, while increased left ventricular end-systolic diameter and left ventricular end-systolic volume. He improved the impaired left ventricular function and cavity enlargement in a dose-dependent manner, and it was beneficial at 1.0 mL/100 g. Mechanistically, He inhibited toll-like receptor 4 (TLR4) expression, reduced the phosphorylation of nuclear factor κB (NF-κB), and subsequently alleviated tumor necrosis factor-alpha (TNF-α) and interleukin-18 (IL-18) expression in heart. Therefore, He protects against LPS-induced cardiac dysfunction in mice partially via inhibiting myocardial TLR4-NF-κB-TNF-α/IL-18 signaling.

Experimental study of cardiac function by high-resolution ultrasound in sepsis rats with cecal ligation and puncture

To evaluate the cardiac function of cecal ligation and puncture (CLP) induced sepsis rats with high-resolution ultrasound. According to the method of random number table, 48 adult male Sprague-Dawley (SD) rats were randomly divided into normal control group and sepsis 6, 12, 24, 30, 48 hours groups, with 8 rats in each group. The sepsis model was produced by CLP, and the rats in the normal control group were only anesthetized and resuscitated. The general situation after modeling in each group was observed, and the left ventricular function was assessed by high-resolution echocardiography at all the time points. The abdominal aorta blood of rats was collected, and the serum levels of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and MB isoenzyme of creatine kinase (CK-MB) were determined by enzyme-linked immunosorbent assay (ELISA). The myocardial tissue was harvested, and the pathological changes in myocardial tissue were observed by hematoxylin-eosin (HE) staining. The rats challenged to CLP displayed symptoms of sepsis, such as depression, ruffled fur, decreased diet and activity, and the symptoms became more obvious with the extension of time. High-resolution echocardiography could clearly show the structure of left ventricle in each group and obtain satisfactory M-mode echocardiography of left ventricle. The heart rate (HR) of rats in all sepsis groups was elevated with the increase in model time as measured by high-resolution ultrasound, and it was significantly higher than that in the normal control group at 12, 24, 30 hours (bpm: 359.66±23.33, 361.35±12.85, 392.67±11.33 vs. 306.24±29.79, all P < 0.05). Stroke volume (SV) and cardiac output (CO) in sepsis rats were decreased with the increase in model time, while left ventricular ejection fraction (LVEF) and left ventricular fractional shortening (LVFS) were increased first and then decreased, and SV and LVEF in sepsis 48 hours group were significantly lower than those in the normal control group [SV (μL): 78.43±17.52 vs. 122.61±15.88, LVEF: 0.763±0.018 vs. 0.902±0.011, both P < 0.05]. Left ventricular weight (LVW) in all sepsis groups was increased to different degrees as compared with that in the normal control group, as well as the left ventricular anterior and posterior wall thickness increased in diastole and systole. Compared with the normal control group, the left ventricular posterior wall thickness was increased significantly at the end of diastolic and systolic period in the sepsis 12 hours group, and the left ventricular anterior wall thickness was also increased significantly at the end of diastolic period in the sepsis 48 hours group. The serum levels of TNF-α, IL-1β and CK-MB in sepsis rats were increased first and then decreased with the extension of model making time. The above parameters in the sepsis 48 hours group were still significantly higher than those in the normal control group [TNF-α (ng/L): 61.59±3.99 vs. 16.87±4.89, IL-1β (ng/L): 255.03±13.23 vs. 119.59±10.43, CK-MB (μg/L): 1.27±0.15 vs. 0.52±0.15, all P < 0.05]. HE staining showed that the myocardial striations of the rats in the normal control group were clear and complete, with normal morphology and orderly arrangement of cardiac cells. However in the sepsis groups, myocardial cells were swollen, ruptured and necrotic, and inflammatory cells were infiltrated, with myocardial fibers ruptured and necrosis dissolved, and the above pathological manifestations gradually increased with the extension of the model making time. High-resolution ultrasound can evaluate the cardiac function of CLP induced sepsis rat model more comprehensive, and the consequence of evaluation index is consistent with the expression level of myocardial enzyme and histopathologic manifestations.

Effects of Wheel Running on Health-Related Outcomes in Growth Restricted Mice.

Growth restriction caused by early life undernutrition leads to an increased risk of cardiovascular disease, hypertension, type II diabetes and sarcopenia. However, limited information exists on the beneficial effects of physical activity engagement in growth restricted individuals. PURPOSE: To determine the effects of wheel running access on health-related outcomes in growth restricted mice. METHODS: Mice were undernourished in gestation (GUN, N=15) or lactation (PUN, N=17) by feeding FVB mothers a low protein diet (8% protein). The control group (CON, N=14) was fed a normal protein diet (20% protein) throughout gestation and lactation. At postnatal day 21 (PN21), all pups were weaned and refed with the control diet. At PN45, mice were singly housed and either given access to a free moving running wheel (VOL-wheel access) or used as a non-active control (SED-sedentary). At PN70 a maximal treadmill test was performed to determine exercise capacity, and at PN72 echocardiography was performed to evaluate cardiovascular function. RESULTS: Final body weight showed SED PUN (M: 21.22±2.07 g, F: 17.42±1.7 g) weighed significantly (P=0.0002) less than SED CON (M: 26.83±2.2 g, F: 20.65±1.65 g) and SED GUN (M: 26.9±1.5 g, F: 19.98±1.6 g) mice, while the VOL CON mice (M: 24.9±1.62 g, F: 23.0±1.42 g) were significantly larger (P=0.0441) than VOL PUN mice (M: 22.6±2.7 g, F: 20.0±2.26 g). Wheel access improved treadmill running time to exhaustion in CON (P=0.045, VOL: 1078±47s, SED: 936±40s), and GUN mice (P=0.042; VOL 1021±39s SED 890±44s), but not PUN mice (P=0.59; VOL 933±31s and SED 908±32s). Echoes showed heart rate was significantly lowered (P=0.002) in GUN mice (VOL:366±11 bpm; SED: 421±10 bpm) with running wheel access. Stroke volume was also significantly higher (P=0.02) in GUN mice (VOL: 27±1.2 uL; SED: 23±1.1 uL). VOL CON (1.64±0.08mm) mice had a significantly greater (P=0.05) left ventricular anterior wall thickness at systole than SED CON (1.38±0.08mm). CONCLUSION: Voluntary wheel access does not attenuate growth-restriction in PUN mice nor does it improve maximal treadmill tests. This is due to a lack of improvements in cardiac function for PUN mice, despite access to voluntary wheel running, while GUN mice did improve.

A Reduction in ADAM17 Expression Is Involved in the Protective Effect of the PPAR-α Activator Fenofibrate on Pressure Overload-Induced Cardiac Hypertrophy.

The peroxisome proliferator-activated receptor-α (PPAR-α) agonist fenofibrate ameliorates cardiac hypertrophy; however, its mechanism of action has not been completely determined. Our previous study indicated that a disintegrin and metalloproteinase-17 (ADAM17) is required for angiotensin II-induced cardiac hypertrophy. This study aimed to determine whether ADAM17 is involved in the protective action of fenofibrate against cardiac hypertrophy. Abdominal artery constriction- (AAC-) induced hypertensive rats were used to observe the effects of fenofibrate on cardiac hypertrophy and ADAM17 expression. Primary cardiomyocytes were pretreated with fenofibrate (10 μM) for 1 hour before being stimulated with angiotensin II (100 nM) for another 24 hours. Fenofibrate reduced the ratios of left ventricular weight to body weight (LVW/BW) and heart weight to body weight (HW/BW), left ventricular anterior wall thickness (LVAW), left ventricular posterior wall thickness (LVPW), and ADAM17 mRNA and protein levels in left ventricle in AAC-induced hypertensive rats. Similarly, in vitro experiments showed that fenofibrate significantly attenuated angiotensin II-induced cardiac hypertrophy and diminished ADAM17 mRNA and protein levels in primary cardiomyocytes stimulated with angiotensin II. In summary, a reduction in ADAM17 expression is associated with the protective action of PPAR-α agonists against pressure overload-induced cardiac hypertrophy.

Doxorubicin upregulates CXCR4 via miR-200c/ZEB1-dependent mechanism in human cardiac mesenchymal progenitor cells

Doxorubicin (DOXO) treatment is limited by its cardiotoxicity, since it causes cardiac-progenitor-cell depletion. Although the cardioprotective role of the stromal cell-derived factor-1/C-X-C chemokine receptor type 4 (SDF1/CXCR4) axis is well established, its involvement during DOXO-induced cardiotoxicity has never been investigated. We showed that in a mouse model of DOXO-induced cardiomyopathy, CXCR4+ cells were increased in response to DOXO, mainly in human cardiac mesenchymal progenitor cells (CmPC), a subpopulation with regenerative potential. Our in vitro results showed a CXCR4 induction after 24 h of DOXO exposure in CmPC. SDF1 administration protected from DOXO-induced cell death and promoted CmPC migration. CXCR4 promoter analysis revealed zinc finger E-box binding homeobox 1 (ZEB1) binding sites. Upon DOXO treatment, ZEB1 binding decreased and RNA-polymerase-II increased, suggesting a DOXO-mediated transcriptional increase in CXCR4. Indeed, DOXO induced the upregulation of miR-200c, that directly targets ZEB1. SDF1 administration in DOXO-treated mice partially reverted the adverse remodeling, decreasing left ventricular (LV) end diastolic volume, LV ejection fraction and LV anterior wall thickness in diastole, recovering LV end systolic pressure and reducing±dP/dt. Moreover, in vivo administration of SDF1 partially reverted DOXO-induced miR-200c and p53 protein upregulation in mouse hearts. In addition, downmodulation of ZEB1 mRNA and protein by DOXO was significantly increased by SDF1. In keeping, p21 mRNA, that is induced by p53 and inhibited by ZEB1, is induced by DOXO treatment and is decreased by SDF1 administration. This study showed new players of the DOXO-induced cardiotoxicity, that can be exploited to ameliorate DOXO-associated cardiomyopathy.

Transgenic overexpression of GTP cyclohydrolase 1 in cardiomyocytes ameliorates post-infarction cardiac remodeling

GTP cyclohydrolase 1 (GCH1) and its product tetrahydrobiopterin play crucial roles in cardiovascular health and disease, yet the exact regulation and role of GCH1 in adverse cardiac remodeling after myocardial infarction are still enigmatic. Here we report that cardiac GCH1 is degraded in remodeled hearts after myocardial infarction, concomitant with increases in the thickness of interventricular septum, interstitial fibrosis, and phosphorylated p38 mitogen-activated protein kinase and decreases in left ventricular anterior wall thickness, cardiac contractility, tetrahydrobiopterin, the dimers of nitric oxide synthase, sarcoplasmic reticulum Ca2+ release, and the expression of sarcoplasmic reticulum Ca2+ handling proteins. Intriguingly, transgenic overexpression of GCH1 in cardiomyocytes reduces the thickness of interventricular septum and interstitial fibrosis and increases anterior wall thickness and cardiac contractility after infarction. Moreover, we show that GCH1 overexpression decreases phosphorylated p38 mitogen-activated protein kinase and elevates tetrahydrobiopterin levels, the dimerization and phosphorylation of neuronal nitric oxide synthase, sarcoplasmic reticulum Ca2+ release, and sarcoplasmic reticulum Ca2+ handling proteins in post-infarction remodeled hearts. Our results indicate that the pivotal role of GCH1 overexpression in post-infarction cardiac remodeling is attributable to preservation of neuronal nitric oxide synthase and sarcoplasmic reticulum Ca2+ handling proteins, and identify a new therapeutic target for cardiac remodeling after infarction.

Abstract 10036: Olmesartan Improves Not Only Vascular Endothelial Dysfunction but Cardiac Diastolic Dysfunction in Hypertensive Heart Failure With Preserved Ejection Fraction - ORION Study

Introduction: The optimal treatment for heart failure (HF) with preserved left ventricular (LV) ejection fraction (EF) (HFpEF) has not been established. Using an experimental model of HFpEF, we previously reported a novel mechanism underlying reversal of endothelial dysfunction and HFpEF by AT1 receptor blocker (ARB). By performing this study (ORION: OlmesaRtan Improvement endothelial functiON with hypertension study), we examined the effects of ARB on hypertensive HFpEF patients, focusing on reactive oxygen species (ROS). Methods and Results: We examined prospectively 20 hypertensive HFpEF patients, taking any renin-angiotensin system inhibitors, switched to appreciable amounts of highly-selective ARB; olmesartan (average dosage amounts: 22.9 mg/day) for 3 months. Despite no additive hypotensive effects of olmesartan, endothelial dysfunction assessed by fingertrip digital reactive hyperemia (RH) peripheral arterial tonometry using Endo-PAT2000 was significantly reversed (RH-index; 1.57±0.34 to 1.87±0.50, P=0.034), accompanied by significant reduction of serum derivatives of reactive oxidative metabolites levels, novel biomarker of ROS (362.8±13.7 to 302.1±9.4 unit called the Carratelli unit [U.CARR], P=0.001). Olmesartan treatments significantly improved cardiac diastolic function evaluated by the ratio of early transmitral flow velocity to tissue doppler early diastolic mitral annular velocity (15.4 to 11.0, P&lt;0.001) but not LVEF and LV anterior wall thickness in echocardiography, and decreased plasma B-type natriuretic peptide levels (214.9 to 191.4, P&lt;0.05) in HFpEF patients. Additionaly, olmesartan significantly increased plasma superoxide dismutase activity (2.39±0.73 to 3.06±0.78 U/mL, P=0.02) and adiponectin levels (2.66±1.55 to 4.12±1.99 μg/mL, P&lt;0.05), but not affect plasma nitrates and nitrites (NO3-/NO2-) levels (53.2±28.1 to 62.9±28.4 μmol/L). Conclusions: These data suggested that strong AT1 receptor blockade by olmesartan restored not only endothelial dysfunction but cardiac diastolic dysfunction in HFpEF beyond hypotensive effects. Increased in SOD activities and adiponectin levels, but not nitric oxide levels, might contribute to these beneficial effects of olmesartan.

Abstract 16: Enhancing Myocardial Repair With CardioChimeras

Dual cell transplantation of cardiac progenitor cells (CPCs) and mesenchymal stem cells (MSCs) after infarction enhances myocardial repair and performance in large animal models relative to delivery of either cell population individually. However, a single stem cell to support both direct and indirect mechanisms of myocardial repair has yet to be identified. CardioChimeras (CCs), a progenitor cell formed by fusion between CPCs and MSCs were analysed for reparative potential after myocardial infarction (MI) relative to individual parents cell or combined parent cell delivery. Two representative CCs, CardioChimera 1 (CC1) and CardioChimera 2 (CC2) were used for this study. CC1 and CC2 improved left ventricular anterior wall thickness (AWT) at 4 weeks, but only CC1 treatment preserved AWT at 18 weeks relative to no cell treatment (PBS). Ejection fraction was enhanced at 6 weeks post injury in CC1 and CC2 groups, which was maintained in CC1, CC2 and CPC + MSC combined groups up to 18 weeks. Infarct size was decreased by 5% in CC1 and CC2 hearts, whereas CPC + MSC and CPC parent groups remained unchanged when comparing 4 to 12 week change in scar size. MSC and PBS groups displayed marked increases in infarct size (10-15%). CC1 and CC2 showed enhanced engraftment potential by 3-fold relative to CPC + MSC and CPC hearts. In contrast, MSCs were detected at low levels (0.04%). CC1 and CC2 discovered within the myocardium expressed early commitment marker cardiac troponin T relative to controls. CC1 and CC2 treatment increased capillary density within the infarct, indicating that cell persistence facilitates paracrine mediated vasculature stabilization and/or formation. CCs merge the application of distinct cells into a single entity for cellular therapeutic intervention in the progression of heart failure. CCs represent a tractable cellular system that improves upon combinatorial cell therapy approaches and supports myocardial regeneration.