A Model of Cardiac Remodeling Through Constriction of the Abdominal Aorta in Rats

H2S treatment reverts cardiac hypertrophy and increases SERCA2a activity but does not fully restore cardiac Ca2+ handling in hypertensive rats

Hydrogen sulfide (H2S) has been proposed to play a cardioprotective role, particularly due to its ability to revert left ventricular hypertrophy (LVH) and mitigate cardiac dysfunction in various cardiomyopathies, including hypertensive heart disease. However, the extent to which cardioprotection by H2S involves improvement in Ca2+ handling remains unclear. Although H2S has been reported to influence the function of key Ca2+ handling proteins, most studies have focused on acute administration of H2S donors in isolated cardiomyocytes, rather than in a therapeutic context. In this study, we used a rat model of hypertension induced by abdominal aortic coarctation (AAC) to evaluate the therapeutic potential of NaHS, an H2S donor, on LVH and Ca2+ handling. After 8 weeks of AAC, hypertensive rats developed moderate LVH, which was accompanied by a reduction in both the amplitude and the rate of rise of systolic Ca2+ transients, as well as a decrease in sarcoplasmic reticulum (SR) Ca2+ load. Despite the reduced SR Ca2+ load, the frequency of diastolic Ca2+ sparks remained high, while the incidence and propagation rate of spontaneous Ca2+ waves significantly increased, suggesting enhanced diastolic SR Ca2+ leak, most likely due to hypersensitivity of ryanodine receptors (RyR2) to Ca2+. On the other hand, NaHS administration during the final 4 weeks of AAC reverted both LVH and hypertension, and increased SR Ca2+ reuptake mediated by the SR Ca2+ ATPase (SERCA2a). However, NaHS treatment failed to restore the amplitude and rate of rise of systolic Ca2+ transients or SR Ca2+ load. Furthermore, SR Ca2+ leak might have worsened, since spontaneous Ca2+ waves increased. In conclusion, NaHS treatment does not appear to normalize all Ca2+ handling properties during hypertensive LVH. On the contrary, NaHS may exert an arrhythmogenic effect, likely due to enhanced SERCA2a activity under conditions of unresolved RyR2 Ca2+ hypersensitivity.

Stellate Ganglionectomy Attenuates Pressure Overload-Induced Cardiac Hypertrophy and Dysfunction

BACKGROUND

Enhanced cardiac sympathetic activity contributes to chronic heart failure (CHF). Interventions targeting the stellate ganglion (SG) can reduce this activity, potentially slowing the progression of cardiovascular diseases. This study examined the effects and mechanisms of stellate ganglionectomy on myocardial hypertrophy and cardiac dysfunction caused by pressure overload.

METHODS

A rat model of pressure overload was created using abdominal aortic constriction. Four groups were studied: the sham surgery, abdominal aortic coarctation (AB), aortic constriction plus left stellate ganglionectomy (LSG), and aortic constriction plus right stellate ganglionectomy (RSG) groups. Cardiac function was assessed via echocardiography, and myocardial hypertrophy and fibrosis were evaluated using hematoxylin-eosin staining (H&E) and Masson staining. Serum atrial natriuretic peptides (ANP) and norepinephrine (NE) levels were measured using enzyme linked immunosorbent assay (ELISA), and the levels of the molecular markers tyrosine hydroxylase (TH) and growth-associated protein-43 (GAP43) were analyzed using Western blotting and PCR. Calcium calmodulin dependent protein kinase II (CaMKII) and phosphorylated Ryanodine Receptor 2 (p-RyR2) expression were also investigated.

RESULTS

Stellate ganglionectomy significantly reduced myocardial hypertrophy and improved cardiac function, as indicated by decreased left ventricular posterior wall thickness (LVPWD) (p < 0.01), left ventricular end-diastolic diameter (LVEDD) and volume (p < 0.001), left ventricular end-diastolic volume (LVEDV) (p < 0.001), increased left ventricular ejection fraction (LVEF) (p < 0.001) and left ventricular fractional shortening (LVFS) (p < 0.001). Histological analysis confirmed reduced myocardial dilation. Molecular analysis revealed decreased CaMKII/RyR2 signaling (p < 0.001) and lower NE levels (p < 0.01), suggesting reduced neurohormonal stress.

CONCLUSIONS

Stellate ganglionectomy alleviates hypertrophy and cardiac dysfunction caused by pressure overload, likely through inhibition of the CaMKII/RyR2 pathway, underscoring its potential as a therapeutic approach.

Hydrogen therapy as a potential therapeutic intervention in heart disease: from the past evidence to future application

Cardiovascular disease is the leading cause of mortality worldwide. Excessive oxidative stress and inflammation play an important role in the development and progression of cardiovascular disease. Molecular hydrogen, a small colorless and odorless molecule, is considered harmless in daily life when its concentration is below 4% at room temperature. Owing to the small size of the hydrogen molecule, it can easily penetrate the cell membrane and can be metabolized without residue. Molecular hydrogen can be administered through inhalation, the drinking of hydrogen-rich water, injection with hydrogen-rich-saline, and bathing of an organ in a preservative solution. The utilization of molecular hydrogen has shown many benefits and can be effective for a wide range of purposes, from prevention to the treatment of diseases. It has been demonstrated that molecular hydrogen exerts antioxidant, anti-inflammatory, and antiapoptotic effects, leading to cardioprotective benefits. Nevertheless, the exact intracellular mechanisms of its action are still unclear. In this review, evidence of the potential benefits of hydrogen molecules obtained from in vitro, in vivo, and clinical investigations are comprehensively summarized and discussed with a focus on the cardiovascular aspects. The potential mechanisms involved in the protective effects of molecular hydrogen are also presented. These findings suggest that molecular hydrogen could be used as a novel treatment in various cardiovascular pathologies, including ischemic-reperfusion injury, cardiac injury from radiation, atherosclerosis, chemotherapy-induced cardiotoxicity, and cardiac hypertrophy.

Iron chelation alleviates multiple pathophysiological pathways in a rat model of cardiac pressure overload

Iron dysmetabolism affects a great proportion of heart failure patients, while chronic hypertension is one of the most common risk factors for heart failure and death in industrialized countries. Serum data from reduced ejection fraction heart failure patients show a relative or absolute iron deficiency, whereas cellular myocardial analyses field equivocal data. An observed increase in organellar iron deposits was incriminated to cause reactive oxygen species formation, lipid peroxidation, and cell death. Therefore, we studied the effects of iron chelation on a rat model of cardiac hypertrophy. Suprarenal abdominal aortic constriction was achieved surgically, with a period of nine weeks to accommodate the development of chronic pressure overload. Next, deferiprone (100 mg/kg/day), a lipid-permeable iron chelator, was administered for two weeks. Pressure overload resulted in increased inflammation, fibrotic remodeling, lipid peroxidation, left ventricular hypertrophy and mitochondrial iron derangements. Deferiprone reduced cardiac inflammation, lipid peroxidation, mitochondrial iron levels, and hypertrophy, without affecting circulating iron levels or ejection fraction. In conclusion, metallic molecules may pose ambivalent effects within the cardiovascular system, with beneficial effects of iron redistribution, chiefly in the mitochondria.

A machine learning approach for predicting descending thoracic aortic diameter

Background

To establish models for predicting descending thoracic aortic diameters and provide evidence for selecting the size of the stent graft for TBAD patients.

Methods

A total of 200 candidates without severe deformation of aorta were included. CTA information was collected and 3D reconstructed. In the reconstructed CTA, a total of 12 cross-sections of peripheral vessels were made perpendicular to the axis of flow of the aorta. Parameters of the cross sections and basic clinical characteristics were used for prediction. The data was randomly split into the training set and the test set in an 8:2 ratio. To fully describe diameters of descending thoracic aorta, three predicted points were set based quadrisection, and a total of 12 models at three predicted points were established using four algorithms included linear regression (LR), support vector machine (SVM), Extra-Tree regression (ETR) and random forest regression (RFR). The performance of models was evaluated by mean square error (MSE) of the prediction value, and the ranking of feature importance was given by Shapley value. After modeling, prognosis of five TEVAR cases and stent oversizing were compared.

Results

We identified a series of parameters which affect the diameter of descending thoracic aorta, including age, hypertension, the area of proximal edge of superior mesenteric artery, etc. Among four predictive models, all the MSEs of SVM models at three different predicted position were less than 2 mm², with approximately 90% predicted diameters error less than 2 mm in the test sets. In patients with dSINE, stent oversizing was about 3 mm, while only 1 mm in patients without complications.

Conclusion

The predictive models established by machine learning revealed the relationship between basic characteristics and diameters of different segment of descending aorta, which help to provide evidence for selecting the matching distal size of the stent for TBAD patients, thereby reducing the incidence of TEVAR complications.

Molecular imaging of fibroblast activity in pressure overload heart failure using [68 Ga]Ga-FAPI-04 PET/CT

PURPOSE

We aimed to evaluate whether [68 Ga]Ga-FAPI-04 PET/CT could characterize the early stages of cardiac fibrosis in pressure overload heart failure.

METHODS

Sprague-Dawley rats underwent abdominal aortic constriction (AAC) (n = 12) and sham surgery (n = 10). All rats were scanned with [68 Ga]Ga-FAPI-04 PET/CT at 2, 4, and 8 weeks after surgery. The expression of fibroblast activation protein (FAP) in the myocardium was detected by immunohistochemistry. [68 Ga]Ga-FAPI-04 PET signal and FAP expression were compared between two groups.

RESULTS

Compared with the sham group, the AAC group presented with decreased ejection fraction (EF) and fractional shortening (FS) and increased left ventricular internal dimensions in diastole (LVIDd) and systole (LVIDs) at 4 and 8 weeks (all p < 0.01). The AAC group showed higher [68 Ga]Ga-FAPI-04 accumulation in the heart than the sham group at 2, 4, and 8 weeks, and FAPI increased significantly from 2 to 8 weeks (all p < 0.001). Immunohistochemistry confirmed the higher density of the FAP+ area in the AAC group. The intensity of the [68 Ga]Ga-FAPI-04 correlated with the density of the FAP+ area (p < 0.001). The expression of the [68 Ga]Ga-FAPI-04 at 4 weeks correlated with the deterioration of cardiac function at 8 weeks (EF: R =  - 0.87; FS: R =  - 0.72; LVIDd: R = 0.77; LVIDs: R = 0.79; all p < 0.001). The AAC group also showed an increased [68 Ga]Ga-FAPI-04 signal in the liver, peaking at 4 weeks and then declining. Cardiac and liver PET signals correlated at 4 weeks in the AAC group (R = 0.69, p = 0.0010), suggesting an early fibrotic link between organs. A combination of the [68 Ga]Ga-FAPI-04 intensity in the heart and liver at 4 weeks better predicted the deterioration of cardiac function at 8 weeks.

CONCLUSIONS

The activated fibroblasts in the heart and liver after pressure overload can be monitored by [68 Ga]Ga-FAPI-04 PET/CT, which reveals an early fibrotic link in cardio-liver interactions and could better predict nonischemic heart failure prognosis.

NBP Relieves Cardiac Injury and Reduce Oxidative Stress and Cell Apoptosis in Heart Failure Mice by Activating Nrf2/HO-1/Ca2+-SERCA2a Axis

Although heart failure (HF) has become one of the most fatal diseases in the whole world, there are fewer drugs for its treatment. Therefore, we focused on the protective effect of Dl-3-n-butylphthalide (NBP) on myocardial injury and oxidative stress in heart failure mice and further investigated the relationship with the Nrf2/HO-1/Ca2+-SERCA2a axis. Methods. C57BL/6J mice were divided into the sham group (Sham), heart Failure model group (HF), HF + NBP group (HN), HN + Nrf2 inhibitor (HNM), HN + Calmodulin-dependent protein kinase II (CaMKII) antagonist, KN93 (HNK). The HF mice model was prepared using abdominal aorta ligation. Mice’s heart function was accessed by echocardiography. Hematoxylin-eosin staining and MASSON staining were used to identify myocardial injury; the cell apoptosis was determined by the TUNEL staining assay. The expression of oxidative stress-related proteins was detected by the ELISA assay. The reactive oxygen species and Nrf2 expression in heart tissue were observed with the immunofluorescence assay. SERCA2a, calmodulin, endoplasmic reticulum stress regulatory proteins, and Nrf2/HO-1 in mice’ heart tissues were measured using Western blotting. Results. Moreover, NBP could significantly promote heart failure mice’s heart function, relieve the injury and inhibit cell apoptosis. Meanwhile, it could reduce ERS injury of heart failure mice through increasing SERCA2a level and reducing Ca2+ influx. NBP was demonstrated to minimize CaMKII phosphorylation level and decrease cAMP-response element-binding protein phosphorylation level, suggesting NBP could also activate the Nrf2/HO-1 signaling pathway. Conclusions. We demonstrated that NPBs treatment promotes the cardiomyocyte’s ERS and alleviates myocardial injury in heart failure mice, related to stimulating the Nrf2/HO-1 signaling pathway, regulating Ca2+-SERCA2a, and reducing Ca2+ influx.

Slowing Heart Rate Protects Against Pathological Cardiac Hypertrophy

We aimed to determine the pathophysiological impact of heart rate (HR) slowing on cardiac function. We have recently developed a murine model in which it is possible to conditionally delete the stimulatory heterotrimeric G-protein (Gα_s) in the sinoatrial (SA) node after the addition of tamoxifen using cre-loxP technology. The addition of tamoxifen leads to bradycardia. We used this approach to examine the physiological and pathophysiological effects of HR slowing. We first looked at the impact on exercise performance by running the mice on a treadmill. After the addition of tamoxifen, mice with conditional deletion of Gα_s in the SA node ran a shorter distance at a slower speed. Littermate controls preserved their exercise capacity after tamoxifen. Results consistent with impaired cardiac capacity in the mutants were also obtained with a dobutamine echocardiographic stress test. We then examined if HR reduction influenced pathological cardiac hypertrophy using two models: ligation of the left anterior descending coronary artery for myocardial infarction and abdominal aortic banding for hypertensive heart disease. In littermate controls, both procedures resulted in cardiac hypertrophy. However, induction of HR reduction prior to surgical intervention significantly ameliorated the hypertrophy. In order to assess potential protein kinase pathways that may be activated in the left ventricle by relative bradycardia, we used a phospho-antibody array and this revealed selective activation of phosphoinositide-3 kinase. In conclusion, HR reduction protects against pathological cardiac hypertrophy but limits physiological exercise capacity.

A Heart Failure Model Established by Pressure Overload Caused by Abdominal Aortic Contraction in Rat

Heart failure is a complex clinical syndrome in which ventricular filling or ejection capacity is impaired due to structural or functional diseases of the heart. In order to establish a stable heart failure model, we investigated cardiac parameters in rats with abdominal aortic contraction and normal rats, including the left ventricular posterior wall diameter (LVPWd), the interventricular septum thickness of end-diastolic (IVSd), the left ventricular end-diastolic diameter (LVEDd), the left ventricular ejection fraction (LVEF), and left ventricular fractional shortening (LVFS). Rats were randomly divided into experimental group (n = 20) and control group (n = 20). The experimental group underwent modified abdominal aortic constriction, while the control group only isolated the abdominal aorta without constriction. The results showed that the survival rate of rats in the experimental group was 85% after one week of operation, while the survival rate of rats in the control group was 100%. Five weeks after operation, the left ventricular posterior wall diameter (LVPWd) and the interventricular septum thickness of end-diastolic (IVSd) in the experimental group were all increased compared with those in the control group, and the differences were statistically significant (p < 0.05); the left ventricular end-diastolic diameter (LVEDd) in the experimental group showed an increasing trend compared with the control group, but p > 0.05; compared with the control group, the left ventricular ejection fraction (LVEF) and left ventricular fractional shortening (LVFS) in the experimental group showed downward trend, but p > 0.05. 10 weeks after operation, the LVPWd, IVSd, and LVEDd of the experimental group were increased compared with the control group, p < 0.05, and the LVEF and LVFS of the experimental group were decreased compared with the control group, p < 0.05. Compared with the control group, the BNP of the experimental group increased significantly, p < 0.05. The heart weight index and left ventricular weight index of rats in the experimental group were significantly higher than those in the control group, p < 0.05. HE staining showed that the myocardial cells in the experimental group increased in volume, disordered cell arrangement, widened gaps, increased nuclear hyperchromia, and uneven staining. This paper provides a theoretical basis for the study of heart failure.

Yap1 modulates cardiomyocyte hypertrophy via impaired mitochondrial biogenesis in response to chronic mechanical stress overload

Rationale: Chronic pressure overload is a major trigger of cardiac pathological hypertrophy that eventually leads to heart disease and heart failure. Understanding the mechanisms governing hypertrophy is the key to develop therapeutic strategies for heart diseases.

Methods: We built chronic pressure overload mice model by abdominal aortic constriction (AAC) to explore the features of Yes-associated protein 1 (YAP1). Then AAV-cTNT-Cre was applied to Yap1^F/F mice to induce mosaic depletion of YAP1. Myh6^CreERT2; H11^CAG-LSL-YAP1 mice were involved to establish YAP1 overexpression model by Tomaxifen injection. ATAC-seq and bioChIP-seq were used to explore the potential targets of YAP1, which were verified by a series of luciferase reporter assays. Dnm1l and Mfn1 were re-expressed in AAC mice by AAV-cTNT-Dnm1l and AAV-cTNT-Mfn1. Finally, Verteprofin was used to inhibit YAP1 to rescue cardiac hypertrophy.

Results: We found that pathological hypertrophy was accompanied with the activation of YAP1. Cardiomyocyte-specific deletion of Yap1 attenuated AAC-induced hypertrophy. Overexpression of YAP1 was sufficient to phenocopy AAC-induced hypertrophy. YAP1 activation resulted in the perturbation of mitochondria ultrastructure and function, which was associated with the repression of mitochondria dynamics regulators Dnm1l and Mfn1. Mitochondrial-related genes Dnm1l and Mfn1, are significantly targeted by TEAD1/YAP complex. Overexpression of Dnm1l and Mfn1 synergistically rescued YAP1-induced mitochondrial damages and cardiac hypertrophy. Pharmacological repression of YAP1 by verteporfin attenuated mitochondrial damages and pathological hypertrophy in AAC-treated mice. Interestingly, YAP1-induced mitochondria damages also led to increased reactive oxidative species, DNA damages, and the suppression of cardiomyocyte proliferation.

Conclusion: Together, these data uncovered YAP signaling as a therapeutic target for pressure overload-induced heart diseases and cautioned the efforts to induce cardiomyocyte regeneration by activating YAP.

Calpains as Potential Therapeutic Targets for Myocardial Hypertrophy

Despite advances in its treatment, heart failure remains a major cause of morbidity and mortality, evidencing an urgent need for novel mechanism-based targets and strategies. Myocardial hypertrophy, caused by a wide variety of chronic stress stimuli, represents an independent risk factor for the development of heart failure, and its prevention constitutes a clinical objective. Recent studies performed in preclinical animal models support the contribution of the Ca²⁺-dependent cysteine proteases calpains in regulating the hypertrophic process and highlight the feasibility of their long-term inhibition as a pharmacological strategy. In this review, we discuss the existing evidence implicating calpains in the development of cardiac hypertrophy, as well as the latest advances in unraveling the underlying mechanisms. Finally, we provide an updated overview of calpain inhibitors that have been explored in preclinical models of cardiac hypertrophy and the progress made in developing new compounds that may serve for testing the efficacy of calpain inhibition in the treatment of pathological cardiac hypertrophy.

PEX5 prevents cardiomyocyte hypertrophy via suppressing the redox-sensitive signaling pathways MAPKs and STAT3

Peroxisomal biogenesis factor 5 (PEX5) is a member of peroxisome biogenesis protein family which serves as a shuttle receptor for the import of peroxisome matrix protein. The function of PEX5 on cardiomyocyte hypertrophy remained to be elucidated. Our study demonstrated that the protein expression level of PEX5 was declined in primary neonatal rat cardiomyocytes treated with phenylephrine (PE) and hearts from cardiac hypertrophic rats induced by abdominal aortic constriction (AAC). Overexpression of PEX5 alleviated cardiomyocyte hypertrophy induced by PE, while silencing of PEX5 exacerbated cardiomyocyte hypertrophy. PEX5 improved redox imbalance by decreasing cellular reactive oxygen species level and preserving peroxisomal catalase. Moreover, PEX5 knockdown aggravated PE-induced activation of redox-sensitive signaling pathways, including mitogen-activated protein kinase (MAPK) pathway and signal transducer and activator of transcription 3 (STAT3); whereas PEX5 overexpression suppressed activation of MAPK and STAT3. But PEX5 did not affect PE-induced phosphorylation of mammalian target of rapamycin (mTOR). In conclusion, the present study suggests that PEX5 protects cardiomyocyte against hypertrophy via regulating redox homeostasis and inhibiting redox-sensitive signaling pathways MAPK and STAT3.

Hydrogen-rich saline mitigates pressure overload-induced cardiac hypertrophy and atrial fibrillation in rats via the JAK-STAT signalling pathway

Objective

To investigate if hydrogen-rich saline (HRS), which has been shown to have antioxidant and anti-inflammatory properties, could mitigate cardiac remodelling and reduce the incidence of atrial fibrillation (AF) in the rat model of cardiac hypertrophy.

Methods

Pressure overload was induced in rats by abdominal aortic constriction (AAC). The animals were separated into four groups: sham; AAC group; AAC plus low dose HRS (LHRS); AAC plus high dose HRS (HHRS). The sham and AAC groups received normal saline intraperitoneally and the LHRS and HHRS groups received 3 or 6 ml/kg HRS daily for six weeks, respectively. In vitro research was also performed using cardiotrophin-1 (CT-1)-induced hypertrophy of cultured neonatal rat cardiomyocytes.

Results

Cardiac hypertrophy was successfully induced by AAC and low and high dose HRS mitigated the pressure overload as shown by lower heart and atrial weights in these treatment groups. AF incidence and duration of the HRS groups were also significantly lower in the HRS groups compared with the AAC group. Atrial fibrosis was also reduced in the HRS groups and the JAK-STAT signalling pathway was down-regulated. In vitro experiments showed that hydrogen-rich medium mitigated the CT-1-induced cardiomyocyte hypertrophy with a similar effect as the JAK specific antagonists AG490.

Conclusions

HRS was found to mitigate cardiac hypertrophy induced by pressure overload in rats and reduce atrial fibrosis and AF which was possibly achieved via inhibition of the JAK-STAT signalling pathway.

Protective effect of hydrogen-rich saline on pressure overload-induced cardiac hypertrophyin rats: possible role of JAK-STAT signaling

Background

Molecular hydrogen has been shown to have antioxidant effect and have been used to prevent oxidative stress-related diseases. The goal of this study was to explore if hydrogen-rich saline (HRS) plays a cardioprotective effect on abdominal aortic constriction (AAC) induced cardiac hypertrophy in rats. 60adult Sprague–Dawley rats received surgically the AAC for 6-week. After the surgery, the rats were randomly divided into 4 groups (15 for each):1: sham-operated (sham); 2: AAC-model; 3: AAC + Low HRS (LHRS); and 4: AAC + High HRS (HHRS). The rats in sham and AAC-model groups were treated with normal saline intraperitoneally, while rats in LHRS and HHRS groups were intraperitoneally treated with 3 or 6 mL/kg HRS daily, respectively, for 6-week.

Results

The ratios of HW/BW and LVW/BW were shown in an order of Model > LHRS > HHRS > SHAM groups. The cardiac hypertrophy was also manifested with increased expressions of atrial natriuretic peptide (ANP), brain natriuretic peptides (BNP) and fibrosis of cardiac tissues in AAC-model group, which could likewise be restrained in LHRS and HHRS groups. Moreover, the JAK-STAT (Janus Kinase-Signal transducers and activators of transcription) signaling molecule expressions were decreased with HRS treatment.

Conclusions

Our results showed a protective effect of HRS on pressure overload-induced cardiac hypertrophy in rats, which may be associated to a decreasing in JAK-STAT signaling pathway.