Titration of sedentary behavior with varying physical activity levels reduces mortality in patients with type 2 diabetes.

CONTEXT: Both physical activity (PA) and sedentary behavior (SB) exert important impact on type 2 diabetes, but it remains unclear how maximum impact on improving the mortality and optimized proportion of the two lifestyles combination exists. OBJECTIVE: To explore the impacts of PA/SB combinations on mortality in patients with diabetes. METHODS: Patients with type 2 diabetes patients samplings were collected from the National Health and Nutrition Examination Survey (NHANES) dataset. Their lifestyles were categorized into eight groups based on combinations of the PA and SB levels. Cox proportional hazards models were used to calculate hazard ratios and 95% confidence intervals. RESULTS: During the follow-up period, 1,148 deaths (18.94%) were recorded. High SB (sedentary time ≥6 hours/day) was significantly associated with higher all-cause mortality (HR 1.65). In participants with low SB (<6 hours/day), low PA was associated with lower all-cause mortality (HR 0.43), while further increase of PA level did not show further reduction in either all-cause or cardiovascular mortality. In contrast, in participants with high SB，all levels of PA were associated with lower all-cause mortality (p<0.05), but only moderate PA was associated with lower cardiovascular mortality (HR 0.30). CONCLUSIONS: In patients with type 2 diabetes, different combinations of various levels of PA and SB are associated with different degree of risk for all-cause or cardiovascular mortality.

CircMap4k2 reactivated by aneurysm plication alleviates residual cardiac remodeling after SVR by enhancing cardiomyocyte proliferation in post-MI mice.

INTRODUCTION: Surgical ventricular reconstruction (SVR) is an alternative therapeutic approach in patients with refractory heart failure (HF), but residual remodeling after SVR limits the improvement of HF. Recently, we reported that SVR may act as an environmental cue to reactivate endogenous proliferation of cardiomyocytes; however, it is unclear whether enhancing endogenous cardiomyocyte regeneration further improves HF after SVR. OBJECTIVES: We aimed to explore whether circular RNAs (circRNAs) would involved in SVR and their mechanisms. METHODS: Male C57BL/6 mice were subjected to myocardial infarction (MI) or sham surgery. Four weeks later, MI mice with a large ventricular aneurysm underwent SVR or a second open-chest operation only. Echocardiography and histological analysis were used to evaluate heart function, cardiac remodeling, and myocardial regeneration. Sequencing of circular RNAs, RNA immunoprecipitation, RNA pulldown, and luciferase reporter assay were used to explore the underlying mechanisms. RESULTS: SVR markedly attenuated cardiac remodeling and induced cardiomyocyte regeneration, as evidenced by positive staining of Ki-67, phospho-histone H3 (pH3), and Aurora B in the plication zone, but significant residual remodeling still existed in comparison with the sham group. Sequencing results showed that SVR altered the expression profile of cardiac circRNAs, and circMap4k2 was identified as the most upregulated one. After characterizing circMap4k2, we noted that overexpression of circMap4k2 significantly promoted proliferation of cardiomyocytes in cultured neonatal rat cardiomyocytes and silencing of circMap4k2 significantly inhibited it; similar results were obtained in SVR-treated MI mice but not in MI mice without SVR treatment. Residual cardiac remodeling after SVR was further attenuated by circMap4k2 overexpression. CircMap4k2 bound with miR-106a-3p and inhibited cardiomyocyte proliferation by targeting a downstream effector of the antizyme inhibitor 1 (Azin1) gene. CONCLUSIONS: CircMap4k2 acts as an environmental cue and targets the miR-106a-3p/Azin1 pathway to increase cardiac regeneration in the plication zone and attenuate residual remodeling after SVR.

Pregnancy-induced physiological hypertrophic preconditioning attenuates pathological myocardial hypertrophy by activation of FoxO3a.

Previous studies show a woman's pregnancy is correlated with post-reproductive longevity, and nulliparity is associated with higher risk of incident heart failure, suggesting pregnancy likely exerts a cardioprotection. We previously reported a cardioprotective phenomenon termed myocardial hypertrophic preconditioning, but it is unknown whether pregnancy-induced physiological hypertrophic preconditioning (PHP) can also protect the heart against subsequent pathological hypertrophic stress. We aimed to clarify the phenomenon of PHP and its mechanisms. The pluripara mice whose pregnancy-induced physiological hypertrophy regressed and the nulliparous mice underwent angiotensin II (Ang II) infusion or transverse aortic constriction (TAC). Echocardiography, invasive left ventricular hemodynamic measurement and histological analysis were used to evaluate cardiac remodeling and function. Silencing or overexpression of Foxo3 by adeno-associated virus was used to investigate the role of FoxO3a involved in the antihypertrophic effect. Compared with nulliparous mice, pathological cardiac hypertrophy induced by Ang II infusion, or TAC was significantly attenuated and heart failure induced by TAC was markedly improved in mice with PHP. Activation of FoxO3a was significantly enhanced in the hearts of postpartum mice. FoxO3a inhibited myocardial hypertrophy by suppressing signaling pathway of phosphorylated glycogen synthase kinase-3ß (p-GSK3ß)/ß-catenin/Cyclin D1. Silencing or overexpression of Foxo3 attenuated or enhanced the anti-hypertrophic effect of PHP in mice with pathological stimulation. Our findings demonstrate that PHP confers resistance to subsequent hypertrophic stress and slows progression to heart failure through activation of FoxO3a/GSK3ß pathway.

LCZ696 (sacubitril/valsartan) inhibits pulmonary hypertension induced right ventricular remodeling by targeting pyruvate dehydrogenase kinase 4.

BACKGROUND: Right ventricular (RV) function is a major prognostic factor in patients with cardiopulmonary disease. Effective medical therapies are available for left heart failure, but they are usually less effective or even ineffective in right heart failure. Here, we tested the hypothesis that LCZ696 (sacubitril/valsartan) can attenuate pressure overload-induced RV remodeling by inhibiting pyruvate dehydrogenase kinase 4 (PDK4). METHODS: Adult male C57 mice were subjected to transverse aortic constriction (TAC), pulmonary artery constriction (PAC), or sham surgery. Bioinformatics analysis was used to screen for common differentially expressed genes (DEGs) between TAC and PAC. Chemical compounds targeting DEGs were predicted by molecular docking analysis. Effects of LCZ696 on PAC-induced RV remodeling and the associated PDK4-related mechanisms were investigated. RESULTS: We found 60 common DEGs between PAC and TAC, and Pdk4 was one of the downregulated DEGs. From 47 chemical compounds with potential cardiovascular activity and PDK4 protein binding ability, we selected LCZ696 to treat PAC-induced RV remodeling because of its high docking score for binding PDK4. Compared with vehicle-treated PAC mice, LCZ696-treated mice had significantly smaller RV wall thickness and RV diameters, less myocardial fibrosis, lower expression of PDK4 protein, and less phosphorylation of glycogen synthase kinase-3ß (p-GSK3ß). In PAC mice, overexpression of Pdk4 blocked the inhibitory effect of LCZ696 on RV remodeling, whereas conditional knockout of Pdk4 attenuated PAC-induced RV remodeling. CONCLUSIONS: Pdk4 is a common therapeutic target for pressure overload-induced left ventricular and RV remodeling, and LCZ696 attenuates RV remodeling by downregulating Pdk4 and inhibiting PDK4/p-GSK3ß signal.

Circ-Ddx60 contributes to the antihypertrophic memory of exercise hypertrophic preconditioning.

INTRODUCTION: We previously reported a phenomenon called exercise hypertrophic preconditioning (EHP), the underlying mechanisms of which need further clarification. OBJECTIVES: We aimed to investigate whether circular RNAs (circRNAs) are involved in EHP. METHODS: CircRNA sequencing of myocardial tissue was performed in male C57BL/6 mice with EHP and sedentary. Bioinformatics analysis and Sanger sequencing were used to screen hub circRNA expression and to detect full-length circRNAs, respectively. Loss-of-function analyses were conducted to assess the effects of circ-Ddx60 (c-Ddx) on EHP. After 21 days of swimming training or resting, mice underwent transverse aortic constriction (TAC) or sham surgery. Echocardiography, invasive hemodynamic measurement and histological analysis were used to evaluate cardiac remodeling and function. The presence of interaction between c-Ddx and proteins was investigated using comprehensive identification of RNA-binding proteins by mass spectrometry (ChIRP-MS). RESULTS: In this study, we identified a novel circRNA, named c-Ddx that was preferentially expressed in myocardial tissue and significantly up-regulated in EHP mice. Silencing of c-Ddx attenuated the antihypertrophic effect of EHP and worsened heart failure in mice that underwent TAC. ChIRP-MS and molecular docking analysis validated the combination of c-Ddx and eukaryotic elongation factor 2 (eEF2). Mechanistically, c-Ddx silencing inhibited the increase of phosphorylation of eEF2 and its upstream AMP-activated protein kinase (AMPK) induced by EHP. CONCLUSIONS: C-Ddx contributes to the antihypertrophic memory of EHP by binding and activating eEF2, which would provide opportunity to search new therapeutic targets for pathological hypertrophy of heart.

Dapagliflozin attenuates residual cardiac remodeling after surgical ventricular reconstruction in mice with an enlarged heart after myocardial infarction.

BACKGROUND: Severe heart failure refractory to conventional therapy requires alternative treatment modalities. Surgical ventricular reconstruction (SVR) has been used to reverse cardiac remodeling in post-myocardial infarction (MI) patients with large left ventricular (LV) aneurysm, however, residual LV remodeling and dysfunction remain postoperatively. It is unclear whether SVR recovers response to drug treatment and whether the sodium-glucose co-transporter 2 inhibitor dapagliflozin (DAPA) reverses residual LV remodeling after SVR. METHODS: Adult male C57 mice were subjected to MI or sham surgery. Four-week later, MI mice with LV aneurysm underwent modified SVR or second open-chest sham operation and were randomized to DAPA or vehicle for four-week. Cardiac remodeling, LV function, and the underlying mechanisms were evaluated by echocardiography, invasive LV hemodynamic measurements, mRNA sequencing, and bioinformatics analysis. RESULTS: SVR significantly decreased LV volume; increased myocardial strain, LV pressure change rates and end-systolic elastance; and decreased heart-to-body weight ratio and myocardial fibrosis. However, significant residual cardiac remodeling remained. DAPA significantly attenuated residual cardiac remodeling and improved LV function in SVR mice but did not have curative effects in non-SVR mice. Of the 1532 genes differentially expressed in SVR and MI mice, 1037 were associated with cardiac metabolism; Src, Crebbp, Fn1, Grb2, and Mapk14 were the top 5 hub genes. Unlike sham surgery, MI upregulated those 5 genes, and treatment with SVR + DAPA normalized their expression. CONCLUSIONS: SVR restores therapeutic response in the post-MI heart with large LV aneurysm, and DAPA attenuates residual cardiac remodeling after SVR by normalizing some cardiac metabolism-related hub genes.

Growth differentiation factor 11 attenuates cardiac ischemia reperfusion injury via enhancing mitochondrial biogenesis and telomerase activity.

It has been reported that growth differentiation factor 11 (GDF11) protects against myocardial ischemia/reperfusion (IR) injury, but the underlying mechanisms have not been fully clarified. Considering that GDF11 plays a role in the aging/rejuvenation process and that aging is associated with telomere shortening and cardiac dysfunction, we hypothesized that GDF11 might protect against IR injury by activating telomerase. Human plasma GDF11 levels were significantly lower in acute coronary syndrome patients than in chronic coronary syndrome patients. IR mice with myocardial overexpression GDF11 (oe-GDF11) exhibited a significantly smaller myocardial infarct size, less cardiac remodeling and dysfunction, fewer apoptotic cardiomyocytes, higher telomerase activity, longer telomeres, and higher ATP generation than IR mice treated with an adenovirus carrying a negative control plasmid. Furthermore, mitochondrial biogenesis-related proteins and some antiapoptotic proteins were significantly upregulated by oe-GDF11. These cardioprotective effects of oe-GDF11 were significantly antagonized by BIBR1532, a specific telomerase inhibitor. Similar effects of oe-GDF11 on apoptosis and mitochondrial energy biogenesis were observed in cultured neonatal rat cardiomyocytes, whereas GDF11 silencing elicited the opposite effects to oe-GDF11 in mice. We concluded that telomerase activation by GDF11 contributes to the alleviation of myocardial IR injury through enhancing mitochondrial biogenesis and suppressing cardiomyocyte apoptosis.

Antihypertrophic Memory After Regression of Exercise-Induced Physiological Myocardial Hypertrophy Is Mediated by the Long Noncoding RNA Mhrt779.

BACKGROUND: Exercise can induce physiological myocardial hypertrophy (PMH), and former athletes can live 5 to 6 years longer than nonathletic controls, suggesting a benefit after regression of PMH. We previously reported that regression of pathological myocardial hypertrophy has antihypertrophic effects. Accordingly, we hypothesized that antihypertrophic memory exists even after PMH has regressed, increasing myocardial resistance to subsequent pathological hypertrophic stress. METHODS: C57BL/6 mice were submitted to 21 days of swimming training to develop PMH. After termination of exercise, PMH regressed within 1 week. PMH regression mice (exercise hypertrophic preconditioning [EHP] group) and sedentary mice (control group) then underwent transverse aortic constriction or a sham operation for 4 weeks. Cardiac remodeling and function were evaluated with echocardiography, invasive left ventricular hemodynamic measurement, and histological analysis. LncRNA sequencing, chromatin immunoprecipitation assay, and comprehensive identification of RNA-binding proteins by mass spectrometry and Western blot were used to investigate the role of Mhrt779 involved in the antihypertrophic effect induced by EHP. RESULTS: At 1 and 4 weeks after transverse aortic constriction, the EHP group showed less increase in myocardial hypertrophy and lower expression of the Nppa and Myh7 genes than the sedentary group. At 4 weeks after transverse aortic constriction, EHP mice had less pulmonary congestion, smaller left ventricular dimensions and end-diastolic pressure, and a larger left ventricular ejection fraction and maximum pressure change rate than sedentary mice. Quantitative polymerase chain reaction revealed that the long noncoding myosin heavy chain-associated RNA transcript Mhrt779 was one of the markedly upregulated lncRNAs in the EHP group. Silencing of Mhrt779 attenuated the antihypertrophic effect of EHP in mice with transverse aortic constriction and in cultured cardiomyocytes treated with angiotensin II, and overexpression enhanced the antihypertrophic effect. Using chromatin immunoprecipitation assay and quantitative polymerase chain reaction, we found that EHP increased histone 3 trimethylation (H3K4me3 and H3K36me3) at the a4 promoter of Mhrt779. Comprehensive identification of RNA-binding proteins by mass spectrometry and Western blot showed that Mhrt779 can bind SWI/SNF related, matrix associated, actin dependent regulator of chromatin, subfamily a, member 4 (Brg1) to inhibit the activation of the histone deacetylase 2 (Hdac2)/phosphorylated serine/threonine kinase (Akt)/phosphorylated glycogen synthase kinase 3ß(p-GSK3ß) pathway induced by pressure overload. CONCLUSIONS: Myocardial hypertrophy preconditioning evoked by exercise increases resistance to pathological stress via an antihypertrophic effect mediated by a signal pathway of Mhrt779/Brg1/Hdac2/p-Akt/p-GSK3ß.

Operating Transverse Aortic Constriction with Absorbable Suture to Obtain Transient Myocardial Hypertrophy.

Based on twice transverse aortic constrictions (TACs) in mice, it is proved that myocardial hypertrophic preconditioning (MHP) could attenuate cardiomyocyte hypertrophy and slow down progression to heart failure. For novices, however, the MHP model is usually quite difficult to establish because of the technical obstacles in ventilator operation, opening the chest repeatedly, and bleeding caused by debanding. To facilitate this model, to increase the surgical success rate and to reduce the incidence of bleeding, we switched to absorbable sutures for the first TAC combing with a ventilator-free technique. Using a 2-week absorbable suture, we demonstrated that this procedure could cause significant myocardial hypertrophy in 2 weeks; and 4 weeks after surgery, myocardial hypertrophy was almost completely regressed to the baseline. Using this protocol, the operators could master the MHP model easily with a lower operation mortality.

Lansoprazole alleviates pressure overload-induced cardiac hypertrophy and heart failure in mice by blocking the activation of ß-catenin.

AIMS: Proton pump inhibitors (PPIs) are widely used in patients receiving percutaneous coronary intervention to prevent gastric bleeding, but whether PPIs are beneficial for the heart is controversial. Here, we investigated the effects of lansoprazole on cardiac hypertrophy and heart failure, as well as the underlying mechanisms. METHODS AND RESULTS: Adult male C57 mice were subjected to transverse aortic constriction (TAC) or sham surgery and then were treated with lansoprazole or vehicle for 5 weeks. In addition, cultured neonatal rat ventricular cardiomyocytes and fibroblasts were exposed to angiotensin II in the presence or absence of lansoprazole. At 5 weeks after TAC, the heart weight/body weight ratio was lower in lansoprazole-treated mice than in untreated mice, as was the lung weight/body weight ratio, while left ventricular (LV) fractional shortening and the maximum and minimum rates of change of the LV pressure were higher in lansoprazole-treated mice, along with less cardiac fibrosis. In cultured cardiomyocytes, lansoprazole inhibited angiotensin II-induced protein synthesis and hypertrophy, as well as inhibiting proliferation of fibroblasts. Lansoprazole decreased myocardial levels of phosphorylated Akt, phosphorylated glycogen synthase kinase 3ß, and active ß-catenin in TAC mice and in angiotensin II-stimulated cardiomyocytes. After overexpression of active ß-catenin or knockdown of H+/K+-ATPase α-subunit, lansoprazole still significantly attenuated myocyte hypertrophy. CONCLUSION: Lansoprazole inhibits cardiac remodelling by suppressing activation of the Akt/GSK3ß/ß-catenin pathway independent of H+/K+-ATPase inhibition, and these findings may provide a novel insight into the pharmacological effects of PPIs with regard to alleviation of cardiac remodelling.