Cardiac Diastolic Dysfunction Research Articles

Nonsteroidal Mineralocorticoid Receptor Antagonist Finerenone Improves Diastolic Dysfunction in Preclinical Nondiabetic Chronic Kidney Disease.

The mineralocorticoid receptor plays a significant role in the development of chronic kidney disease (CKD) and associated cardiovascular complications. Classic steroidal mineralocorticoid receptor antagonists are a therapeutic option, but their use in the clinic is limited due to the associated risk of hyperkalemia in patients with CKD. Finerenone is a nonsteroidal mineralocorticoid receptor antagonist that has been recently investigated in 2 large phase III clinical trials (FIDELIO-DKD [Finerenone in Reducing Kidney Failure and Disease Progression in Diabetic Kidney Disease] and FIGARO-DKD [Finerenone in Reducing Cardiovascular Mortality and Morbidity in Diabetic Kidney Disease]), showing reductions in kidney and cardiovascular outcomes. We tested whether finerenone improves renal and cardiac function in a preclinical nondiabetic CKD model. Twelve weeks after 5/6 nephrectomy, the rats showed classic signs of CKD characterized by a reduced glomerular filtration rate and increased kidney weight, associated with left ventricular (LV) diastolic dysfunction and decreased LV perfusion. These changes were associated with increased cardiac fibrosis and reduced endothelial nitric oxide synthase activating phosphorylation (ser 1177). Treatment with finerenone prevented LV diastolic dysfunction and increased LV tissue perfusion associated with a reduction in cardiac fibrosis and increased endothelial nitric oxide synthase phosphorylation. Curative treatment with finerenone improves nondiabetic CKD-related LV diastolic function associated with a reduction in cardiac fibrosis and increased cardiac phosphorylated endothelial nitric oxide synthase independently from changes in kidney function. Short-term finerenone treatment decreased LV end-diastolic pressure volume relationship and increased phosphorylated endothelial nitric oxide synthase and nitric oxide synthase activity. We showed that the nonsteroidal mineralocorticoid receptor antagonist finerenone reduces renal hypertrophy and albuminuria, attenuates cardiac diastolic dysfunction and cardiac fibrosis, and improves cardiac perfusion in a preclinical nondiabetic CKD model.

#1920 The impact of kidney function on cardiac diastolic dysfunction trajectories: insights from a longitudinal study

Abstract Background and Aims Although the association between kidney dysfunction and cardiac diastolic dysfunction has been investigated in cross-sectional studies, we currently lack a complete understanding of how the diastolic dysfunction changes over time in individuals with different kidney functions. Exploring the diastolic dysfunction trajectories is crucial as it can provide valuable insights into how kidney function influences cardiac health and which patients are at the highest cardiovascular risk. E/e’ is an echocardiography measure that estimates left ventricular filling pressure and diastolic dysfunction. This study evaluates how kidney function impacts changes in E/e′ over time. Method We identified patients from the Utrecht Patient Oriented Database (UPOD) who visited the outpatient clinic of Utrecht University Medical Center between January 2012 and April 2022. Patients who had received at least three echocardiography reports with a minimum of 12 months between them and had recorded serum creatinine measurements in their electronic health records were included. The estimated glomerular filtration rate (eGFR [mL/min/1.73 m2]) was calculated using the CKD-EPI 2021 creatinine formula without ethnicity and categorized as follows: eGFR ≥ 90, eGFR ≥ 60 - <90, eGFR < 60. Linear mixed-effect models were utilized to determine the impact of kidney function on changes in E/e′ over time. Results A total of 436 patients were included of whom 34.7% were women. The total number of echocardiography examination was 1308. Overall, the median eGFR for all patients was 78.2 mL/min/1.73 m2 [IQR: 61.9, 90.7]. Among them, 26.6%, 51.4%, and 22.0%, had an eGFR ≥ 90, eGFR ≥ 60 - < 90, and eGFR < 60, respectively. Patients with an eGFR < 60 had a higher prevalence of hypertension (64.6%) and cardiovascular disease (84.4%) compared to those with an eGFR ≥ 90, where the prevalence of hypertension and cardiovascular disease was 49.1% and 67.2%, respectively. Additionally, patients with an eGFR < 60 had the lowest mean ejection fraction of 44.9% ± 18.5% and the highest median E/e′ of 12.84 [10.10, 16.16]. The linear mixed model analysis showed that the estimated change in E/e′ per year depended on the level of kidney function. For patients with eGFR ≥ 60 - <90, E/e′ did not significantly change per year (p-value: 0.927). However, for patients with eGFR < 60, a statistically significant (p = 0.014) increase in the E/e′ of 0.45 (0.09, 0.81) was observed per year. Hypertension, diabetes mellitus, and cardiovascular disease were found to affect the change in E/e′, with estimates of 0.95 (0.41, 1.49), 1.82 (0.82, 2.89), and 1.25 (0.54, 1.97), respectively. Conclusion The trajectory of changes in E/e′ over time was significantly affected by varying levels of kidney function. Patients with impaired kidney function (eGFR < 60) have a higher E/e’ compared to those with normal kidney function (eGFR ≥ 90) and presented a significant increase of E/e’ per year.

Chronic circadian rhythm disorder induces heart failure with preserved ejection fraction-like phenotype through the Clock-sGC-cGMP-PKG1 signaling pathway

Emerging evidence has documented that circadian rhythm disorders could be related to cardiovascular diseases. However, there is limited knowledge on the direct adverse effects of circadian misalignment on the heart. This study aimed to investigate the effect of chronic circadian rhythm disorder on heart homeostasis in a mouse model of consistent jetlag. The jetlag model was induced in mice by a serial 8-h phase advance of the light cycle using a light-controlled isolation box every 4 days for up to 3 months. Herein, we demonstrated for the first time that chronic circadian rhythm disorder established in the mouse jetlag model could lead to HFpEF-like phenotype such as cardiac hypertrophy, cardiac fibrosis, and cardiac diastolic dysfunction, following the attenuation of the Clock-sGC-cGMP-PKG1 signaling. In addition, clock gene knock down in cardiomyocytes induced hypertrophy via decreased sGC-cGMP-PKG signaling pathway. Furthermore, treatment with an sGC-activator riociguat directly attenuated the adverse effects of jetlag model-induced cardiac hypertrophy, cardiac fibrosis, and cardiac diastolic dysfunction. Our data suggest that circadian rhythm disruption could induce HFpEF-like phenotype through downregulation of the clock-sGC-cGMP-PKG1 signaling pathway. sGC could be one of the molecular targets against circadian rhythm disorder-related heart disease.

Modulation of Cardiac Sarcomeric Function in Mouse Models of Hyperglycemia

Diabetes is a major risk factor for developing heart failure (HF) and patients with diabetes and HF have worse outcomes than patients with HF alone. Given that diabetes is associated with multiple metabolic impairments, it is critical to determine the mechanisms that exacerbate and worsen cardiac outcomes. Hyperglycemia has been associated with cardiac diastolic dysfunction, which is characterized by prolonged relaxation. The specific mechanisms underlying hyperglycemia-induced diastolic dysfunction are unclear. It is known that hyperglycemia induces profound perturbations in cardiac metabolism modifying acyl-based post-translational modifications (PTMs), which are a class of PTMs that have been gaining increasing focus as modulators of non-genomic protein function. We hypothesize that hyperglycemia contributes to cardiac dysfunction by modulating acyl-based modifications on sarcomeric proteins; thereby, leading to prolonged myofilament relaxation. We evaluated sarcomeric function and specific PTMs (acetylation, crotonylation, malonylation, propionylation, and hydoxy-butyrylation) on sarcomeric proteins in two mouse models that have elevated glucose without hyperinsulinemia: mice with inducible deletion of beta islet glucokinase and mice treated with streptozotocin (STZ) induced damage of the beta islet cells. In male and female mice of both models, myofibrils isolated from the hearts of animals with hyperglycemia demonstrated prolonged sarcomeric relaxation compared to myofibrils isolated from euglycemic mice. We found that sarcomeric proteins isolated from the hearts of hyperglycemic mice from both models have decreased protein acetylation. While crotonylation, malonylation, propionylation, and hydoxy-butyrylation are not different between hyperglycemic and euglycemic mice. To determine how decreased acetylation impacts sarcomeric mechanical function, myofibrils isolated from male and female euglycemic mice were treated with histone deacetylases decrease acetylation and mechanics were assessed. We found that decreased acetylation of myofibrils leads to prolonged relaxation similar to what was observed in hyperglycemic hearts. These findings indicate that specific modifications of acyl-PTMs on sarcomeric proteins modulate sarcomeric function and may contribute to overall diastolic dysfunction observed in hyperglycemia. This work was supported by the National Institutes of Health [K01AG066845 KCW] the American Heart Association [22CDA937598 KCW] and the University of Colorado Anschutz Medical Campus Ludeman Family Center for Women’s Health and Specialized Center for Research Excellence (SCORE) pilot award [KCW], Colorado Diabetes Research Center Pilot and Feasibility Award [P30DK11607 KCW)]. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Macrophage to Myofibroblast Transition Promotes Hypertension-Induced Cardiac Diastolic Dysfunction

Cardiac diastolic dysfunction is a pathological continuum of hypertension eventually leading to heart failure—which is responsible for ~13% of all deaths in the United States. A hallmark of this disease is cardiac fibrotic remodeling, in which excessive extracellular matrix components are deposited into the myocardium. Recent studies have shown the novel ability of macrophages to differentiate into a fibrotic myofibroblast-like phenotype—termed macrophage to myofibroblast transition (MMT). This phenomenon has been implicated in renal fibrosis but, has not been investigated in the heart during hypertension or diastolic dysfunction. Therefore, we hypothesize that MMT plays a causal role in cardiac fibrotic remodeling in hypertension, promoting diastolic dysfunction. As such, we seek to investigate the prevalence of myofibroblast-transitioned macrophages in the heart, as well as determine the gravity of MMT-mediated fibrotic cardiac remodeling. To understand the pathological progression of hypertension to diastolic dysfunction, we utilized the classic DOCA + NaCl model of hypertension in C57BL/6 mice. This investigation is multi-pronged, in that, we seek to gauge diastolic function in vivo, as well as investigate the microenvironment of the heart in primary in vitro experiments. To achieve this, we employ echocardiography and direct left ventricular pressure and volume measurements to determine the progression of hypertension to diastolic dysfunction in the adult mouse heart. For primary in vitro analyses, mouse hearts were isolated and digested, and leukocytes were isolated by Percoll gradient. Cells were stained with α-SMA (myofibroblast) and CD68 (monocyte/macrophage). Finally, the deposition of fibrotic collagen was assessed by both Masson’s trichrome and picrosirius red tissue stains. Mice were subjected to DOCA + salt to induce hypertension. Ten days after this treatment, the left ventricular pressure change as a function of time was measured in the left ventricle. This analysis revealed degraded heart function, realized by a significant decrease in -dp/dt as soon as ten days following the onset of hypertension. Following, another cohort of hypertensive WT mouse hearts was isolated for staining. The results of these assays revealed increased cardiac fibrosis in the hearts of hypertensive mice—likely contributing to the deficit in cardiac function. Finally, in addition to this, flow cytometric analyses of isolated cardiac leukocytes revealed that hypertensive mice had a significant increase in the α-SMA+/CD68+ population of cells in the hypertensive mouse heart, implicating MMT in the rapid pathological progression of hypertension to diastolic dysfunction. These results characterize the presence of MMT cells in the hypertensive mouse heart. Furthermore, the increase of myofibroblast transition is accompanied by decreased cardiac diastolic function and enhanced fibrotic remodeling in the heart—alluding to the role of MMT in the pathological progression of hypertension to diastolic dysfunction. Future efforts into this phenomenon involve the real-time progression of hypertension to diastolic dysfunction via echocardiography, as well as a final, definitive measurement of diastolic function by PV loop. Finally, we will employ an angiotensin II model of hypertension to ensure that this phenomenon is encapsulated in other forms of hypertension, rather than just the DOCA + Salt model. We thank our sources of funding:NIG R01-HL146713, AHA 23TPA1076467. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Relationship of interleukin-16 with different phenogroups in acute heart failure with preserved ejection fraction.

Interleukin-16 (IL-16) has been reported to mediate left ventricular myocardial fibrosis and stiffening in patients with heart failure with preserved ejection fraction (HFpEF). We sought to elucidate whether IL-16 has a distinct impact on pathophysiology and prognosis across different subphenotypes of acute HFpEF. We analysed 211 patients enrolled in a prospective multicentre registry of acute decompensated HFpEF for whom serum IL-16 levels after stabilization were available (53% female, median age 81 [interquartile range 75-85] years). We divided this sub-cohort into four phenogroups using our established clustering algorithm. The study endpoint was all-cause death. Patients were subclassified into phenogroup 1 ('rhythm trouble' [n=69]), phenogroup 2 ('ventricular-arterial uncoupling' [n=49]), phenogroup 3 ('low output and systemic congestion' [n=41]), and phenogroup 4 ('systemic failure' [n=52]). After a median follow-up of 640days, 38 patients had died. Among the four phenogroups, phenogroup 2 had the highest IL-16 level. The IL-16 level showed significant associations with indices of cardiac hypertrophy, diastolic dysfunction, and congestion only in phenogroup 2. Furthermore, the IL-16 level had a significant predictive value for all-cause death only in phenogroup 2 (C-statistic 0.750, 95% confidence interval 0.606-0.863, P=0.017), while there was no association between the IL-16 level and the endpoint in the other phenogroups. Our results indicated that the serum IL-16 level had a significant association with indices that reflect the pathophysiology and prognosis of HFpEF in a specific phenogroup in acute HFpEF.

Lipid Toxicity in the Cardiovascular-Kidney-Metabolic Syndrome (CKMS).

Recent studies of Cardiovascular-Kidney-Metabolic Syndrome (CKMS) indicate that elevated concentrations of derivatives of phospholipids (ceramide, sphingosine), oxidized LDL, and lipoproteins (a, b) are toxic to kidney and heart function. Energy production for renal proximal tubule resorption of critical fuels and electrolytes is required for homeostasis. Cardiac energy for ventricular contraction/relaxation is preferentially supplied by long chain fatty acids. Metabolism of long chain fatty acids is accomplished within the cardiomyocyte cytoplasm and mitochondria by means of the glycolytic, tricarboxylic acid, and electron transport cycles. Toxic lipids and excessive lipid concentrations may inhibit cardiac function. Cardiac contraction requires calcium movement from the sarcoplasmic reticulum from a high to a low concentration at relatively low energy cost. Cardiac relaxation involves calcium return to the sarcoplasmic reticulum from a lower to a higher concentration and requires more energy consumption. Diastolic cardiac dysfunction occurs when cardiomyocyte energy conversion is inadequate. Diastolic dysfunction from diminished ATP availability occurs in the presence of inadequate blood pressure, glycemia, or lipid control and may lead to heart failure. Similar disruption of renal proximal tubular resorption of fuels/electrolytes has been found to be associated with phospholipid (sphingolipid) accumulation. Elevated concentrations of tissue oxidized low-density lipoprotein cholesterols are associated with loss of filtration efficiency at the level of the renal glomerular podocyte. Macroscopically excessive deposits of epicardial and intra-nephric adipose are associated with vascular pathology, fibrosis, and inhibition of essential functions in both heart and kidney. Chronic triglyceride accumulation is associated with fibrosis of the liver, cardiac and renal structures. Successful liver, kidney, or cardiac allograft of these vital organs does not eliminate the risk of lipid toxicity. Lipid lowering therapy may assist in protecting vital organ function before and after allograft transplantation.

Hippo pathway activated by circulating reactive oxygen species mediates cardiac diastolic dysfunction after acute kidney injury

Acute kidney injury (AKI) can cause distal cardiac dysfunction; however, the underlying mechanism is unknown. Oxidative stress is proved prominent in AKI-induced cardiac dysfunction, and a possible bridge role of oxidative-stress products in cardio-renal interaction has been reported. Therefore, this study aimed to investigate the critical role of circulating reactive oxygen species (ROS) in mediating cardiac dysfunction after bilateral renal ischemia-reperfusion injury (IRI). We observed the diastolic dysfunction in the mice following renal IRI, accompanied by reduced ATP levels, oxidative stress, and branched-chain amino acids (BCAA) accumulation in the heart. Notably, ROS levels showed a sequential increase in the kidneys, circulation, and heart. Treatment with tempol, an ROS scavenger, significantly restored cardiac diastolic function in the renal IRI mice, corroborating the bridge role of circulating ROS. Accumulating evidence has identified oxidative stress as upstream of Mst1/Hippo in cardiac injury, which could regulate the expression of downstream genes related to mitochondrial quality control, leading to lower ATP, higher ROS and metabolic disorder. To verify this, we examined the activation of the Mst1/Hippo pathway in the heart of renal IRI mice, which was alleviated by tempol treatment as well. In vitro, analysis revealed that Mst1-knockdown cardiomyocytes could be activated by hydrogen peroxide (H2O2). Analysis of Mst1-overexpression cardiomyocytes confirmed the critical role of the Mst1/Hippo pathway in oxidative stress and BCAA dysmetabolism. Therefore, our results indicated that circulating ROS following renal IRI activates the Mst1/Hippo pathway of myocardium, leading to cardiac oxidative stress and diastolic dysfunction. This finding provides new insights for the clinical exploration of improved treatment options for cardiorenal syndrome.

Exenatide reduces atrial fibrillation susceptibility by inhibiting hKv1.5 and hNav1.5 channels

Exenatide, a promising cardioprotective agent, protects against cardiac structural remodeling and diastolic dysfunction. Combined blockade of sodium and potassium channels is valuable for managing atrial fibrillation (AF). Here, we explored whether exenatide displayed anti-AF effects by inhibiting human Kv1.5 and Nav1.5 channels. We used the whole-cell patch-clamp technique to investigate the effects of exenatide on hKv1.5 and hNav1.5 channels expressed in human embryonic kidney 293 cells and studied the effects of exenatide on action potential (AP) and other cardiac ionic currents in rat atrial myocytes. Additionally, an electrical mapping system was used to explore the effects of exenatide on electrical properties and AF activity in isolated rat hearts. Finally, a rat AF model, established using acetylcholine and calcium chloride, was employed to evaluate the anti-AF potential of exenatide in rats. Exenatide reversibly suppressed IKv1.5 with IC50 of 3.08 μM, preferentially blocked hKv1.5 channel in its closed state, and positively shifted the voltage-dependent activation curve. Exenatide also reversibly inhibited INav1.5 with IC50 of 3.30 μM, negatively shifted the voltage-dependent inactivation curve, and slowed its recovery from inactivation with significant use-dependency at 5 and 10 Hz. Furthermore, exenatide prolonged AP duration and suppressed the sustained K+ current (Iss) and transient outward K+ current (Ito), but without inhibition of L-type Ca2+ current (ICa,L) in rat atrial myocytes. Exenatide prevented AF incidence and duration in rat hearts and rats. These findings demonstrate that exenatide inhibits IKv1.5 and INav1.5in vitro and reduces AF susceptibility in isolated rat hearts and rats.

The effect of long-term administration of green tea catechins on aging-related cardiac diastolic dysfunction and decline of troponin I

Aging is an independent risk factor for cardiovascular diseases. Cardiac diastolic dysfunction (CDD), ultimately leading to heart failure with preserved ejection fraction, is prevalent among older individuals. Although therapeutics have made great progress, preventive strategies remain unmet medical needs. Green tea catechins have been shown to be effective in improving aging-related cardiovascular and cerebral disorders in animal models and patients. However, little attention has been paid to whether long-term administration of epigallocatechin gallate (EGCG), the major bioactive ingredient of green tea catechins, could prevent the onset and progression of CDD. In this study, 12-month-old female mice were orally administered 50, 100, and 200 mg EGCG mixed with drinking water for 6 months. Aged mice (18 months old) exhibited the major features of heart failure with preserved ejection fraction, including CDD with preserved ejection fraction, cardiac fibrosis, increased cardiomyocyte apoptosis, and mitochondrial damages, as well as elevated A/B-type natriuretic peptide. Cardiac troponin I (cTnI) expression was also reduced. Long-term administration of 100 or 200 mg EGCG prevented aging-related CDD and exercise capacity decline, along with alleviating myocardial apoptosis and mitochondria damage. The transcription and protein expression of cTnI were increased, which might be achieved by inhibiting the expression and activity of histone deacetylase 1 and reducing its binding level near cTnI's promoter, thereby elevating acetylated histone 3 and acetylated lysine 9 on histone H3 in the aged mice. We provide a novel insight that long-term administration of EGCG is a potentially effective strategy in preventing aging-related CDD and cTnI expression decline.

Roles of heat shock protein A12A in the development of diabetic cardiomyopathy.

Long-term hyperglycemia can lead to diabetic cardiomyopathy (DCM), a main lethal complication of diabetes. However, the mechanisms underlying DCM development have not been fully elucidated. Heat shock protein A12A (HSPA12A) is the atypic member of the Heat shock 70kDa protein family. In the present study, we found that the expression of HSPA12A was upregulated in the hearts of mice with streptozotocin-induced diabetes, while ablation of HSPA12A improved cardiac systolic and diastolic dysfunction and increased cumulative survival of diabetic mice. An increased expression of HSPA12A was also found in H9c2 cardiac cells following treatment with high glucose (HG), while overexpression of HSPA12A-enhanced the HG-induced cardiac cell death, as reflected by higher levels of propidium iodide cells, lactate dehydrogenase leakage, and caspase 3 cleavage. Moreover, the HG-induced increase of oxidative stress, as indicated by dihydroethidium staining, was exaggerated by HSPA12A overexpression. Further studies demonstrated that the HG-induced increases of protein kinase B and forkhead box transcription factors 1 phosphorylation were diminished by HSPA12A overexpression, while pharmacologically inhibition of protein kinase B further enhanced the HG-induced lactate dehydrogenase leakage in HSPA12A overexpressed cardiac cells. Together, the results suggest that hyperglycemia upregulated HSPA12A expression in cardiac cells, by which induced cell death to promote DCM development. Targeting HSPA12A may serve as a potential approach for DCM management.

Retinal Vascular Changes in Heart Failure with Preserved Ejection Fraction Using Optical Coherence Tomography Angiography.

Background: Systemic microvascular regression and dysfunction are considered important underlying mechanisms in heart failure with preserved ejection fraction (HFpEF), but retinal changes are unknown. Methods: This prospective study aimed to investigate whether retinal microvascular and structural parameters assessed using optical coherence tomography angiography (OCT-A) differ between patients with HFpEF and control individuals (i.e., capillary vessel density, thickness of retina layers). We also aimed to assess the associations of retinal parameters with clinical and echocardiographic parameters in HFpEF. HFpEF patients, but not controls, underwent echocardiography. Macula-centered 6 × 6 mm volume scans were computed of both eyes. Results: Twenty-two HFpEF patients and 24 controls without known HFpEF were evaluated, with an age of 74 [68-80] vs. 68 [58-77] years (p = 0.027), and 73% vs. 42% females (p = 0.034), respectively. HFpEF patients showed vascular degeneration compared to controls, depicted by lower macular vessel density (p < 0.001) and macular ganglion cell-inner plexiform layer thickness (p = 0.025), and a trend towards lower total retinal volume (p = 0.050) on OCT-A. In HFpEF, a lower total retinal volume was associated with markers of diastolic dysfunction (septal e', septal and average E/e': R2 = 0.38, 0.36, 0.25, respectively; all p < 0.05), even after adjustment for age, sex, diabetes mellitus, or atrial fibrillation. Conclusions: Patients with HFpEF showed clear levels of retinal vascular changes compared to control individuals, and retinal alterations appeared to be associated with markers of more severe diastolic dysfunction in HFpEF. OCT-A may therefore be a promising technique for monitoring systemic microvascular regression and cardiac diastolic dysfunction.

Cardiomyocyte-specific deletion of GCN5L1 reduces lysine acetylation and attenuates diastolic dysfunction in aged mice by improving cardiac fatty acid oxidation.

Cardiac mitochondrial dysfunction is a critical contributor to the pathogenesis of aging and many age-related conditions. As such, complete control of mitochondrial function is critical to maintain cardiac efficiency in the aged heart. Lysine acetylation is a reversible post-translational modification shown to regulate several mitochondrial metabolic and biochemical processes. In the present study, we investigated how mitochondrial lysine acetylation regulates fatty acid oxidation (FAO) and cardiac function in the aged heart. We found a significant increase in mitochondrial protein acetylation in the aged heart which correlated with increased level of mitochondrial acetyltransferase-related protein GCN5L1. We showed that acetylation status of several fatty acid and glucose oxidation enzymes (long-chain acyl-coenzyme A dehydrogenase, hydroxyacyl-coA dehydrogenase, and pyruvate dehydrogenase) were significantly up-regulated in aged heart which correlated with decreased enzymatic activities. Using a cardiac-specific GCN5L1 knockout (KO) animal model, we showed that overall acetylation of mitochondrial proteins was decreased in aged KO animals, including FAO proteins which led to improved FAO activity and attenuated cardiac diastolic dysfunction observed in the aged heart. Together, these findings indicate that lysine acetylation regulates FAO in the aged heart which results in improved cardiac diastolic function and this is in part regulated by GCN5L1.

Mkk7 Protects Against Cardiac Dysfunction in Heart Failure with Preserved Ejection Fraction

Article Mkk7 Protects Against Cardiac Dysfunction in Heart Failure with Preserved Ejection Fraction Tayyiba Azam 1, * , Hongyuan Zhang 1, Susanne S. Hille 2, Elizabeth J. Cartwright 1, Oliver J. Müller 2, and Xin Wang 1, * 1 Faculty of Biology, Medicine, and Health, University of Manchester, Oxford Road, M13 9PT, Manchester, UK 2 Department of Internal Medicine III, University of Kiel, Germany; German Centre for Cardiovascular Research (DZHK), 24105 Partner Site Hamburg/Kiel/Lübeck, Germany * Correspondence: xin.wang@manchester.ac.uk (Xin Wang); tayyiba.azam@manchester.ac.uk (Tayyiba Azam) Received: 12 June 2023 Accepted: 25 September 2023 Published: 6 March 2024 Abstract: Shifts in epidemiological patterns foretell a rapid increase in the number of patients with heart failure (HF) globally, representing a significant health and economic burden. Heart failure with preserved ejection (HFpEF) is now considered the prevailing subtype of HF, with no effective treatment available to combat this syndrome. Previous studies have highlighted the cardioprotective role of MKK7 during cardiac pathology, however, no extensive research has been performed to examine MKK7 in the context of HFpEF. This study aimed to address this shortcoming by using adeno-associated virus (AAV) 9 to overexpress MKK7 in the two-hit clinically relevant HFpEF mouse model. We report that cardiomyocyte-specific overexpression of MKK7 improved the HFpEF phenotype in mice, by impeding cardiac diastolic dysfunction and myocardial fibrosis. Mechanistically, it was found that MKK7 ameliorated ER stress by maintaining IRE1-XBP1 signalling and blunted CHOP increase in the myocardium. To summarise, MKK7 overexpression holds the ability to protect the myocardium from HFpEF associated pathologies.

New Insights into Endothelial Dysfunction in Cardiometabolic Diseases: Potential Mechanisms and Clinical Implications.

The endothelium is a monocellular layer covering the inner surface of blood vessels. It maintains vascular homeostasis regulating vascular tone and permeability and exerts anti-inflammatory, antioxidant, anti-proliferative, and anti-thrombotic functions. When the endothelium is exposed to detrimental stimuli including hyperglycemia, hyperlipidemia, and neurohormonal imbalance, different biological pathways are activated leading to oxidative stress, endothelial dysfunction, increased secretion of adipokines, cytokines, endothelin-1, and fibroblast growth factor, and reduced nitric oxide production, leading eventually to a loss of integrity. Endothelial dysfunction has emerged as a hallmark of dysmetabolic vascular impairment and contributes to detrimental effects on cardiac metabolism and diastolic dysfunction, and to the development of cardiovascular diseases including heart failure. Different biomarkers of endothelial dysfunction have been proposed to predict cardiovascular diseases in order to identify microvascular and macrovascular damage and the development of atherosclerosis, particularly in metabolic disorders. Endothelial dysfunction also plays an important role in the development of severe COVID-19 and cardiovascular complications in dysmetabolic patients after SARS-CoV-2 infection. In this review, we will discuss the biological mechanisms involved in endothelial dysregulation in the context of cardiometabolic diseases as well as the available and promising biomarkers of endothelial dysfunction in clinical practice.

Organosulfur Compounds in Aged Garlic Extract Ameliorate Glucose Induced Diabetic Cardiomyopathy by Attenuating Oxidative Stress, Cardiac Fibrosis, and Cardiac Apoptosis.

Diabetic cardiomyopathy has emerged as a major cause of cardiac fibrosis, hypertrophy, diastolic dysfunction, and heart failure due to uncontrolled glucose metabolism in patients with diabetes mellitus. However, there is still no consensus on the optimal treatment to prevent or treat the cardiac burden associated with diabetes, which urges the development of dual antidiabetic and cardioprotective cardiac therapy based on natural products. This study investigates the cardiotoxic profile of glucose and the efficacy of AGE against glucose-induced cardiotoxicity in H9c2 cardiomyocytes. The cellular metabolic activity of H9c2 cardiomyocytes under increasing glucose concentration and the therapeutic efficacy of AGE were investigated using the MTT cell cytotoxicity assay. The in vitro model was established in six groups known as 1. control, 2. cells treated with 25 µM glucose, 3. 100 µM glucose, 4. 25 µM glucose +35 µM AGE, 5. 100 µM glucose + 35 µM AGE, and 6. 35 µM AGE. Morphological and nuclear analyses were performed using Giemsa, HE, DAPI, and PI, respectively, whereas cell death was simultaneously assessed using the trypan blue assay. The antioxidant potential of AGE was evaluated by DCFH-DA assay, NO, and H202 scavenging assay. The activities of the antioxidant enzymes catalase and superoxide dismutase were also investigated. The antiglycative potential of AGE was examined by antiglycation assays, amylase zymography, and SDS PAGE. These results were then validated by in silico molecular docking and qRTPCR. Hyperglycemia significantly reduced cellular metabolic activity of H9c2 cardiomyocytes, and AGE was found to preserve cell viability approximately 2-fold by attenuating oxidative, fibrosis, and apoptotic signaling molecules. In silico and qRTPCR studies confirmed that organosulfur compounds target TNF-α, MAPK, TGF-β, MMP-7, and caspase-9 signaling molecules to ameliorate glucose-induced cardiotoxicity. AGE was found to be an antidiabetic and cardioprotective natural product with exceptional therapeutic potential for use as a novel herb-drug therapy in the treatment of diabetic cardiomyopathy in future therapies.

Prognostic Implications of Microvascular Resistance Reserve in Symptomatic Patients With Intermediate Coronary Stenosis

BackgroundMicrovascular resistance reserve (MRR) is a novel index reflecting coronary microcirculatory function, irrespective of epicardial coronary artery stenosis. There is limited evidence regarding whether MRR can be an independent prognostic tool in patients with stable ischemic heart disease (IHD). ObjectivesThe aim of this study was to evaluate clinical outcomes according to MRR in patients with stable IHD accompanied with or without significant epicardial coronary artery stenosis. MethodsThe present study included 547 consecutive patients undergoing systematic echocardiographic and invasive physiological assessment for suspected stable IHD. Significant epicardial coronary artery stenosis was defined as fractional flow reserve (FFR) ≤0.80. Coronary microvascular dysfunction (CMD) was defined as MRR ≤3.0. The primary outcome was major adverse cardiovascular events (MACE), a composite of cardiovascular death, myocardial infarction, repeat revascularization, and admission for heart failure. ResultsAmong the study group, 172 patients (31.4%) had FFR ≤0.80, and 200 patients (36.6%) had CMD defined by MRR ≤3.0. MRR showed no significant correlation with FFR (R = −0.031; P = 0.469), but it was significantly correlated with the index of microcirculatory resistance (R = −0.353; P < 0.001), N-terminal pro–B-type natriuretic peptide (R = −0.296; P < 0.001), left ventricular filling pressure (E/e′ ratio) (R = −0.224; P < 0.001), and diastolic dysfunction grade (P < 0.001). During a median follow-up period of 3.3 years (Q1-Q3: 2.0-4.5 years), MRR was significantly associated with MACE risk (HR: 1.23 per 1-U decrease; 95% CI: 1.12-1.36; P < 0.001). CMD defined by MRR ≤3.0 was associated with an increased MACE risk for both FFR >0.80 (41.0% vs 26.0%; adjusted HR: 1.59; 95% CI: 1.07-2.35; P = 0.021) and FFR ≤0.80 (34.7% vs 14.8%; adjusted HR: 2.32; 95% CI: 1.12-4.82; P = 0.024). ConclusionsDecreased MRR was associated with the presence of cardiac diastolic dysfunction as well as increased left ventricular filling pressure. The presence of CMD defined by MRR was independently associated with the risk for a composite of cardiovascular death, myocardial infarction, repeat revascularization, and admission for heart failure in patients with stable IHD, irrespective of significant epicardial coronary artery stenosis. (Prognostic Impact of Cardiac Diastolic Function and Coronary Microvascular Function [DIAST-CMD]; NCT05058833)

Semiquantitative 18F-FDG PET/CT in monitoring glucocorticoid response of immunoglobulin G4-related effusive constrictive pericarditis: a case report

BackgroundImmunoglobulin G4 (IgG4)-related effusive constrictive pericarditis (ECP) is a rare manifestation of IgG4-related disease (IgG4-RD). It can lead to persistent pericardial fibrosis, resulting in cardiac tamponade, diastolic dysfunction, and heart failure. Glucocorticoids are the primary treatment for effectively reducing inflammation and preventing fibrosis. However, guidelines for monitoring treatment response are lacking and tapering glucocorticoid therapy for specific target organs remains a challenge. Recent studies on IgG4-RD have demonstrated that semiquantitative measurements of fluorine-18 fluorodeoxyglucose (18F-FDG) uptake in the main involved organs in positron emission tomography/computed tomography (PET/CT) scanning are correlated to disease activity. We present a case of IgG4-related ECP to demonstrate the usefulness of 18F-FDG PET/CT for diagnosing and treatment follow-up of IgG4-related ECP.Case presentationHerein, a 66-year-old woman diagnosed with IgG4-related ECP presented with breathlessness, leg swelling, rales, and fever. Laboratory tests revealed markedly elevated levels of C-reactive protein, and transthoracic echocardiography revealed constrictive physiology with effusion. High IgG4 levels suggested an immune-related pathogenesis, while viral and malignant causes were excluded. Subsequent pericardial biopsy revealed lymphocyte and plasma cell infiltration in the pericardium, confirming the diagnosis of IgG4-related ECP. 18F-FDG PET/CT revealed increased uptake of 18F-FDG in the pericardium, indicating isolated cardiac involvement of IgG4-RD. Treatment with prednisolone and colchicine led to a rapid improvement in the patient’s condition within a few weeks. Follow-up imaging with 18F-FDG PET/CT after 3 months revealed reduced inflammation and improved constrictive physiology on echocardiography, leading to successful tapering of the prednisolone dose and discontinuation of colchicine.ConclusionThe rarity of IgG4-related ECP and possibility of multiorgan involvement in IgG4-RD necessitates a comprehensive diagnostic approach and personalized management. This case report highlights the usefulness of 18F-FDG PET/CT in the diagnosis and treatment follow-up of isolated pericardial involvement in IgG4-RD.

Cardiac Magnetic Resonance Studies in a Large Animal Model that Simulates the Cardiac Abnormalities of Human Septic Shock.

Septic shock, in humans and in our well-established animal model, is associated with increases in biventricular end diastolic volume (EDV) and decreases in ejection fraction (EF). These abnormalities occur over 2 days and reverse within 10 days. Septic non-survivors do not develop an increase in EDV. The mechanism for this cardiac dysfunction and EDV differences is unknown. Purpose-bred beagles randomized to receive intrabronchial Staphylococcus aureus (n=27) or saline (n=6) were provided standard ICU care including sedation, mechanical ventilation, and fluid resuscitation to a pulmonary arterial occlusion pressure of over 10mmHg. No catecholamines were administered. Over 96h, cardiac magnetic resonance imaging, echocardiograms, and invasive hemodynamics were serially performed, and laboratory data was collected. Tissue was obtained at 66h from six septic animals. From 0-96h after bacterial challenge, septic animals vs. controls had significantly increased left ventricular wall edema (6%) and wall thinning with loss of mass (15%) which was more pronounced at 48h in non-survivors than survivors. On histology, edema was located predominantly in myocytes, the interstitium, and endothelial cells. Edema was associated with significantly worse biventricular function (lower EFs), ventricular-arterial coupling, and circumferential strain. In septic animals, from 0-24h, the EDV decreased from baseline and, despite cardiac filling pressures being similar, decreased significantly more in non-survivors. From 24-48h, all septic animals had increases in biventricular chamber sizes. Survivors biventricular EDVs were significantly greater than baseline and in non-survivors, where biventricular EDVs were not different from baseline. Preload, afterload, or HR differences did not explain these differential serial changes in chamber size. Systolic and diastolic cardiac dysfunction during sepsis is associated with ventricular wall edema. Rather than differences in preload, afterload, or heart rate, structural alterations to the ventricular wall best account for the volume changes associated with outcome during sepsis. In non-survivors, from 0-24h, sepsis induces a more severe diastolic dysfunction, further decreasing chamber size. The loss of left ventricular mass with wall thinning in septic survivors may, in part explain, the EDV increases from 24-48h. However, these changes continued and even accelerated into the recovery phase consistent with a reparative process rather than ongoing injury. What is new?: Utilizing multimodal imaging and hemodynamics, we demonstrate the cardiac changes of sepsis have injury and reparative phases.The injury phase (0-24h) has EDV decreases more profound in non-survivors and is associated with worse ventricular compliance, myocardial edema, and diastolic dysfunction.The recovery phase has left ventricular mass loss with wall thinning in survivors that explains the EDV increases (24-96h). These progressed into the EF recovery phase consistent with a reparative process removing damaged tissue.This is the first controlled CMR sepsis study supporting ventricular wall edema is a fundamental aspect of sepsis pathophysiology and dry mass loss a reparative mechanism.What are the clinical implications?: Despite optimizing filling pressures, the cardiac changes in ventricular wall structure and function associated with survival and non-survival in sepsis still occurred, thereby discounting fluid resuscitation as the major factor of therapeutic importance for cardiac function and survival.The changes reported here have potential implications for sepsis treatment especially in the field of fluid resuscitation. These findings yield new understanding into the pathophysiology of sepsis cardiac dysfunction and allow for novel phenotyping and prognosticating of the syndrome with ventricular compliance and EDVs. This also offers potentially high yielding targets for research for new therapeutic approaches for sepsis and heart failure.

TRPM7 kinase is key to hypomagnesemia-induced mitochondrial dysfunction and cardiac diastolic dysfunction

TRPM7 kinase is key to hypomagnesemia-induced mitochondrial dysfunction and cardiac diastolic dysfunction