CTRP3 alleviates mitochondrial dysfunction and oxidative stress injury in pathological cardiac hypertrophy by activating UPRmt via the SIRT1/ATF5 axis.

Pathological cardiac hypertrophy is an independent risk factor for heart failure. Disruption of mitochondrial protein homeostasis plays a key role in pathological cardiac hypertrophy; however, the mechanism of maintaining mitochondrial homeostasis in pathological cardiac hypertrophy remains unclear. In this study, we investigated the regulatory mechanisms of mitochondrial protein homeostasis in pathological cardiac hypertrophy. Wildtype (WT) mice, knockout mice, and mice transfected with lentivirus overexpressing mouse C1q-tumor necrosis factor-related protein-3 (CTRP3) underwent transverse aortic constriction or sham surgery. After 4 weeks, cardiac function, mitochondrial function, and oxidative stress injury were examined. For mechanistic studies, neonatal rat cardiomyocytes were treated with small interfering RNA or overexpression plasmids for the relevant genes. CTRP3 overexpression attenuated transverse aortic constriction (TAC) induced pathological cardiac hypertrophy, mitochondrial dysfunction, and oxidative stress injury compared to that in WT mice. TAC or Ang II resulted in compensatory activation of UPRmt, but this was not sufficient to counteract pathologic cardiac hypertrophy. CTRP3 overexpression further induced activation of UPRmt during pathologic cardiac hypertrophy and thereby alleviated pathologic cardiac hypertrophy, whereas CTRP3 knockout or knockdown inhibited UPRmt. ATF5 was a key regulatory molecule of UPRmt, as ATF5 knockout prevented the cardioprotective effect of CTRP3 in TAC mice. In vitro, SIRT1 was identified as a possible downstream CTRP3 effector molecule, and SIRT1 knockout blocked the cardioprotective effects of CTRP3. Our results also suggest that ATF5 may be regulated by SIRT1. Our study demonstrates that CTRP3 activates UPRmt via the SIRT1/ATF5 axis under pathological myocardial hypertrophy, thus attenuating mitochondrial dysfunction and oxidative stress injury.

Low-dose exercise protects the heart against established myocardial infarction via IGF-1-upregulated CTRP9 in male mice.

Regular exercise is recommended as an important component of therapy for cardiovascular diseases in clinical practice. However, there are still major challenges in prescribing an optimized exercise regimen to individual patients with established cardiac disease. Here, we tested the effects of different exercise doses on cardiac function in mice with established myocardial infarction (MI). Exercise was introduced to mice with MI after 4 weeks of surgery. Low-dose exercise (15 min/day for 8 weeks) improved mortality and cardiac function by increasing 44.39% of ejection fractions while inhibiting fibrosis by decreasing 37.74% of distant region. Unlike higher doses of exercise, low-dose exercise consecutively upregulated cardiac expression of C1q complement/tumor necrosis factor-associated protein 9 (CTRP9) during exercise (>1.5-fold). Cardiac-specific knockdown of CTRP9 abolished the protective effects of low-dose exercise against established MI, while cardiac-specific overexpression of CTRP9 protected the heart against established MI. Mechanistically, low-dose exercise upregulated the transcription factor nuclear receptor subfamily 2 group F member 2 by increasing circulating insulin-like growth factor 1 (IGF-1), therefore, upregulating cardiac CTRP9 expression. These results suggest that low-dose exercise protects the heart against established MI via IGF-1-upregulated CTRP9 and may contribute to the development of optimized exercise prescriptions for patients with MI.

Epicardial adipose tissue, metabolic disorders, and cardiovascular diseases: recent advances classified by research methodologies.

Epicardial adipose tissue (EAT) is located between the myocardium and visceral pericardium. The unique anatomy and physiology of the EAT determines its great potential in locally influencing adjacent tissues such as the myocardium and coronary arteries. Classified by research methodologies, this study reviews the latest research progress on the role of EAT in cardiovascular diseases (CVDs), particularly in patients with metabolic disorders. Studies based on imaging techniques demonstrated that increased EAT amount in patients with metabolic disorders is associated with higher risk of CVDs and increased mortality. Then, in-depth profiling studies indicate that remodeled EAT may serve as a local mediator of the deleterious effects of cardiometabolic conditions and plays a crucial role in CVDs. Further, in vitro coculture studies provided preliminary evidence that the paracrine effect of remodeled EAT on adjacent cardiomyocytes can promote the occurrence and progression of CVDs. Considering the important role of EAT in CVDs, targeting EAT might be a potential strategy to reduce cardiovascular risks. Several interventions have been proved effective in reducing EAT amount. Our review provides valuable insights of the relationship between EAT, metabolic disorders, and CVDs, as well as an overview of the methodological constructs of EAT-related studies.

Forkhead box O6 (FoxO6) promotes cardiac pathological remodeling and dysfunction by activating Kif15-TGF-ß1 under aggravated afterload.

Pathological cardiac hypertrophy exhibits complex and abnormal gene expression patterns and progresses to heart failure. Forkhead box protein O6 (FoxO6) is a key transcription factor involved in many biological processes. This study aimed to explore the role of FoxO6 in cardiac hypertrophy. Three groups of mice were established: wild-type, FoxO6 knockout, and FoxO6-overexpressing. The mice received daily administration of angiotensin-II (Ang-II) or saline for 4 weeks, after which they were examined for cardiac hypertrophy, fibrosis, and function. Elevated cardiac expression of FoxO6 was observed in Ang-II-treated mice. FoxO6 deficiency attenuated contractile dysfunction and cardiac remodeling, including cardiomyocyte hypertrophy and fibroblast proliferation and differentiation. Conversely, FoxO6 overexpression aggravated the cardiomyopathy and heart dysfunction. Further studies identified kinesin family member 15 (Kif15) as downstream molecule of FoxO6. Kif15 inhibition attenuated the aggravating effect of FoxO6 overexpression. In vitro, FoxO6 overexpression increased Kif15 expression in cardiomyocytes and elevated the concentration of transforming growth factor-ß1 (TGF-ß1) in the medium where fibroblasts were grown, exhibiting increased proliferation and differentiation, while FoxO6 knockdown attenuated this effect. Cardiac-derived FoxO6 promoted pathological cardiac remodeling induced by aggravated afterload largely by activating the Kif15/TGF-ß1 axis. This result further complements the mechanisms of communication among different cells in the heart, providing novel therapeutic targets for heart failure.

ZIF-90-Derived Porous ZnO Coated Optical Microfiber Interferometer Sensor for Enhanced Humidity Sensing and Breath Monitoring.

Humidity plays an important role in many fields, and the realization of high sensitivity and fast response simultaneously for humidity detection is a great challenge in practical application. In this work, we demonstrated a high-performance relative humidity (RH) sensor made by supporting zeolitic imidazolate framework-90 (ZIF-90)-derived porous zinc oxide (ZnO) onto an optical microfiber Sagnac interferometer (OMSI). The ZIF-90-modified OMSI (ZIF-90-OMSI) sensor was in situ heated at different temperatures to obtain porous ZnO, and their humidity-sensing properties were investigated ranging from 25 to 80% RH. The experimental results showed that the porous ZnO fiber sensor prepared at 500 °C (Z500-OMSI) exhibited best humidity-sensing performance with a high sensitivity of 96.2 pm/% RH (25-45% RH) and 521 pm/% RH (50-80% RH) and ultrafast response/recovery time (62.37/206.67 ms) at 22.3% RH. These performances were attributed to the complete transformation of ZIF-90 to ZnO at 500 °C. The obtained Z500 not only retained the high porosity and specific surface area of ZIF-90 but also exhibited the exceptional hydrophilicity of ZnO. In addition, the signals of the proposed Z500-OMSI sensor changed with different breathing patterns, indicating the possibility for human respiration monitoring. This work provided a reliable candidate for an effective RH monitoring system with potential application in medical diagnoses, industrial production, environmental detection, and human health monitoring.

GLUT4 mediates the protective function of gastrodin against pressure overload-induced cardiac hypertrophy.

Gastrodia elata exhibits extensive pharmacological activity; its extract gastrodin (GAS) has been used clinically to treat cardiovascular diseases. In the present study, we examined the effect of GAS in a mice model of pathological cardiac hypertrophy, which was induced using transverse aortic constriction (TAC). Male C57BL/6 J mice underwent either TAC or sham surgery. GAS was administered post-surgically for 6 weeks and significantly improved the deterioration of cardiac contractile function caused by pressure overload, cardiac hypertrophy, and fibrosis in mice. Treatment with GAS for 6 weeks upregulated myosin heavy chain α and down-regulated myosin heavy chain ß and atrial natriuretic peptide, while insulin increased the effects of GAS against cardiac hypertrophy. In vitro studies showed that GAS could also protect phenylephrine-induced cardiomyocyte hypertrophy, and these effects were attenuated by BAY-876, and increased by insulin. Taken together, our results suggest that the anti-hypertrophic effect of gastrodin depends on its entry into cardiomyocytes through GLUT4.

Bergenin alleviates myocardial ischemia-reperfusion injury via SIRT1 signaling.

Myocardial ischemia-reperfusion (MI/R) is a major risk factor for cardiovascular disease. At present, reducing oxidative stress and apoptosis is a crucial therapeutic strategy for ameliorating MI/R injury. However, there is a lack of drugs targeting oxidative stress and apoptosis for the clinical therapy of MI/R. Bergenin is a reportedly effective agent with antioxidative and antiapoptotic activity against acute injury. Nevertheless, the roles and potential mechanisms of bergenin against MI/R injury remain unknown. Here, we hypothesized that bergenin attenuated MI/R-induced apoptosis and reactive oxygen species (ROS) production via SIRT1. Mice were subjected to MI/R and treated with bergenin, after which the cardiac function, cardiomyocyte apoptosis, LDH release, and MDA content were evaluated. In vitro, myocardial injury model of H9c2 cells was induced by simulated ischemia/reperfusion (SI/R), apoptosis and oxidative stress was decreased after treated with bergenin. Bergenin significantly reduced myocardial apoptosis and ROS generation in vitro and improved cardiac function in vivo. Intriguingly, bergenin remarkably decreased apoptosis in cardiac tissue accompanied by SIRT1 upregulation following MI/R injury. Further studies showed that inhibiting SIRT1 blocked bergenin's beneficial impact against apoptosis following SI/R injury through excessive oxidative stress and depression of the Bcl2 to Bax ratio. Collectively, these findings indicate that bergenin alleviates MI/R injury by ameliorating myocardial apoptosis and oxidative damage via the SIRT1 signaling pathway.

Alternate-Day Ketogenic Diet Feeding Protects against Heart Failure through Preservation of Ketogenesis in the Liver.

As heart failure develops, the heart utilizes ketone bodies at increased rates, indicating an adaptive stress response. Thus, increasing ketone body availability exerts protective effects against heart failure. However, although it is the widely used approach for increasing ketone body availability, the ketogenic diet shows limited cardioprotective effects against heart failure. This study was aimed at examining the effects of the ketogenic diet on heart failure and the underlying mechanisms. Pressure overload-induced heart failure was established by transverse aortic constriction (TAC) in mice. Continuous ketogenic diet feeding for 8 weeks failed to protect the heart against heart failure. It showed no significant effects on cardiac systolic function and fibrosis but aggravated cardiac diastolic function in TAC mice. Specifically, it induced systemic lipid metabolic disorder and hepatic dysfunction in TAC mice. It decreased the content of 3-hydroxy-3-methylglutaryl-CoA lyase (HMGCL), a key enzyme in ketogenesis, and impaired the capacity of hepatic ketogenesis in TAC mice. It preserved the capacity of hepatic ketogenesis and exerted cardioprotective effects against heart failure, increasing cardiac function and decreasing cardiac fibrosis, in liver-specific HMGCL-overexpressed TAC mice. Importantly, we found that alternate-day ketogenic diet feeding did not impair the capacity of hepatic ketogenesis and exerted potent cardioprotective effects against heart failure. These results suggested that alternate-day but not continuous ketogenic diet protects against heart failure through preservation of ketogenesis in the liver.

Exercise Enhances Branched-Chain Amino Acid Catabolism and Decreases Cardiac Vulnerability to Myocardial Ischemic Injury.

Long-term exercise-induced metabolic adaptations occupy a central position in exercise-afforded cardiac benefits. Emerging evidence suggests that branched-chain amino acid (BCAA) catabolic defect contributes to cardiac dysfunction in multiple cardiometabolic diseases. However, the role of BCAA catabolism in exercise-afforded cardiac benefits remains unknown. Here, we show that exercise improves BCAA catabolism and thus reduce cardiac vulnerability to myocardial ischemic injury. Exercise increased circulating BCAA levels in both humans (male adolescent athletes) and mice (following an 8-week swimming intervention). It increased the expression of mitochondrial localized 2C-type serine-threonine protein phosphatase (PP2Cm), a key enzyme in regulating BCAA catabolism, and decreased BCAA accumulation in mouse hearts, indicating an increase in BCAA catabolism. Pharmacological promotion of BCAA catabolism protected the mouse heart against myocardial infarction (MI) induced by permanent ligation of the left descending coronary artery. Although cardiac-specific PP2Cm knockout showed no significant effects on cardiac structural and functional adaptations to exercise, it blunted the cardioprotective effects of exercise against MI. Mechanistically, exercise alleviated BCAA accumulation and subsequently inactivated the mammalian target of rapamycin in MI hearts. These results showed that exercise elevated BCAA catabolism and protected the heart against myocardial ischemic injury, reinforcing the role of exercise in the promotion of cardiac health.

C1q/TNF-related protein-9 ameliorates hypoxia-induced pulmonary hypertension by regulating secretion of endothelin-1 and nitric oxide mediated by AMPK in rats.

Injury/dysfunction of the endothelium of pulmonary arteries contributes to hypoxia-induced pulmonary hypertension (HPH). We investigated whether C1q/tumor necrosis factor-related protein-9 (CTRP9), a newly identified cardiovascular agent, has protective roles in the development of HPH. HPH was induced in adult male rats by chronic hypobaric hypoxia. CTRP9 overexpression by adeno-associated virus (AAV)-CTRP9 transfection attenuated the increases in right ventricular systolic pressure, right ventricular hypertrophy index, and pulmonary arterial remodeling of rats under hypoxia. Importantly, CTRP9 overexpression improved endothelium-dependent vasodilation in pulmonary arterioles in HPH rats. CTRP9 overexpression enhanced expression of phosphorylated 5'-adenosine monophosphate-activated protein kinase (p-AMPK) and phosphorylated endothelial nitric oxide synthase (p-eNOS), and reduced phosphorylated extracellular signal-regulated protein kinase (p-ERK1/2) expression in pulmonary microvascular endothelial cells (PMVECs) of HPH rats. In cultured PMVECs, CTRP9 not only preserved the decrease of AMPK and eNOS phosphorylation level and nitric oxide (NO) production induced by hypoxia, but also blocked the increase in hypoxia-induced ERK1/2 phosphorylation level and endothelin (ET)-1 production. Furthermore, the effects of CTRP9 were interrupted by inhibitors or knockdown of AMPK. CTRP9 enhances NO production and reduces ET-1 production by regulating AMPK activation. CTRP9 could be a target for HPH.

Short-term but not long-term high fat diet feeding protects against pressure overload-induced heart failure through activation of mitophagy.

AIMS: Recent studies have shown that enhancement of fatty acid utilization through feeding animals a high fat diet (HFD) attenuated cardiac dysfunction in heart failure (HF). Here, we aimed to examine the temporal effects of HFD feeding on cardiac function in mice with heart failure and its underlying mechanism. MAIN METHODS: Pressure overload-induced HF was established via transverse aortic constriction (TAC) surgery. After surgery, the mice were fed on either normal diet or HFD for 8 or 16 weeks. KEY FINDINGS: HFD feeding exerted opposite effects on cardiac function at different time points post-surgery. Short-term HFD feeding (8 wk) protected the heart against pressure overload, inhibiting cardiac hypertrophy and improving cardiac function, while long-term HFD feeding (16 wk) aggravated cardiac dysfunction in TAC mice. Short-term HFD feeding elevated cardiac fatty acid utilization, while long-term HFD feeding showed no significant effects on cardiac fatty acid utilization in TAC mice. Specifically, an increase in cardiac fatty acid utilization was accompanied with activated mitophagy and improved mitochondrial function. Palmitic acid treatment (400 µM, 2 h) stimulated fatty acid oxidation and mitophagy in neonatal myocytes. Mechanistically, fatty acid utilization stimulated mitophagy through upregulation of Parkin. Cardiac-specific knockdown of Parkin abolished the protective effects of short-term HFD feeding on cardiac function in TAC mice. SIGNIFICANCES: These results suggested that short-term but not long-term HFD feeding protects against pressure overload-induced heart failure through activation of mitophagy, and dietary fat intake should be used with caution in treatment of heart failure.

Upregulated hepatokine fetuin B aggravates myocardial ischemia/reperfusion injury through inhibiting insulin signaling in diabetic mice.

Patients with type 2 diabetes mellitus (T2DM) are more susceptible to acute myocardial ischemia/reperfusion (MI/R) injury. However, the mechanism remains largely elusive. Clinical observation showed that high levels of hepatokine fetuin-B (FetB) in plasma are significantly associated with both diabetes and coronary artery diseases. This study was aimed to determine whether FetB mostly derived from liver exacerbates MI/R-induced injury and the underlying mechanisms in T2DM. Mice were given high-fat diet and streptozotocin to induce T2DM model and subjected to 30 min MI followed by reperfusion. Diabetes caused increased hepatic FetB expression and greater myocardial injury as evidenced by increased apoptosis and myocardial enzymes release following MI/R. In T2DM hearts, insulin-induced phosphorylations of insulin receptor substrate 1 at Tyr608 site and Akt at Ser473 site and glucose transporter 4 membrane translocation were markedly reduced. Interaction between FetB and insulin receptor-ß subunit (IRß) was enhanced assessed by immunoprecipitation analysis. More importantly, FetB knockdown via AAV9 alleviated MI/R injury and improved cardiac insulin-induced signaling in T2DM mice. Conversely, upregulation of FetB in normal mice caused exacerbated MI/R injury and impairment of insulin-mediated signaling. In cultured neonatal mouse cardiomyocytes, incubation of FetB significantly reduced tyrosine kinase activity of IR and insulin-induced glucose uptake, and increased hypoxia/reoxygenation-induced apoptosis. Furthermore, FoxO1 knockdown by siRNA suppressed FetB expressions in hepatocytes treated with palmitic acid. In conclusion, upregulated FetB in diabetic liver contributes to increased MI/R injury and cardiac dysfunction via directly interacting with IRß and consequently impairing cardiac insulin signaling.

Novel PGC-1α/ATF5 Axis Partly Activates UPRmt and Mediates Cardioprotective Role of Tetrahydrocurcumin in Pathological Cardiac Hypertrophy.

Mitochondrial unfolding protein response (UPRmt) effectively resists the pathological cardiac hypertrophy and improves the mitochondrial function. However, the specific activation mechanism and drugs that can effectively activate UPRmt in the cardiac muscle are yet to be elucidated. The aim of this study was to determine the regulation role of UPRmt on preventing pathological cardiac hypertrophy by tetrahydrocurcumin (THC) and explore its underlying molecular mechanism. Male C57BL/6J wild-type (WT) mice were divided into a control group and subjected to sham treatment for 4 weeks, and a test group which was subjected to transverse aortic constriction (TAC) surgery. Animals in the control and test group were orally administered THC (50 mg/kg) for 4 weeks after TAC procedure; an equivalent amount of saline was orally administered in the control sham-treated group and the TAC group. Subsequently, oxidative stress and UPRmt markers were assessed in these mice, and cardiac hypertrophy, fibrosis, and cardiac function were tested. Small interfering RNA (siRNA) targeting proliferator-activated receptor-gamma coactivator (PGC)-1α and activating transcription factor 5 (ATF5) were used to determine the UPRmt activation mechanism. THC supplement partly upregulated UPRmt effectors and inhibited TAC-induced oxidative stress compared with TAC-operated WT mice, thereby substantially attenuating contractile dysfunction, cardiac hypertrophy, and fibrosis. Furthermore, PGC-1α knockdown blunted the UPRmt activation and the cardioprotective role of THC. The interaction between PGC-1α and ATF5 was tested in neonatal rat cardiac myocytes under normal conditions. The results showed that PGC-1α was an upstream effector of ATF5 and partly activated UPRmt. In vitro, phenylephrine- (PE-) induced cardiomyocyte hypertrophy caused ATF5 upregulating rather than downregulating corresponding to the downregulation of PGC-1α. The PGC-1α/ATF5 axis mediated the UPRmt activation and stress-resistance role of THC in vitro. Collectively, the present study provides the first evidence that PGC-1 and ATF5 can form a signaling axis to partly activate UPRmt that mediates the cardioprotective role of THC in pathological cardiac hypertrophy.

C1q-TNF-related protein-3 attenuates pressure overload-induced cardiac hypertrophy by suppressing the p38/CREB pathway and p38-induced ER stress.

C1q-tumor necrosis factor-related protein-3 (CTRP3) is an adipokine, which exerts protective function in ischemic or diabetic heart injury. However, the role of CTRP3 in cardiac hypertrophy remains unclear. The aim of this study was to investigate the pharmacological effects of CTRP3 on pathological cardiac hypertrophy induced by hypertension. Male C57BL/6 J wild-type (WT) mice, Ctrp3 knockout mice, and mice infected with lentivirus overexpressing mouse Ctrp3 underwent sham surgery or transverse aortic constriction (TAC) surgery. After 4 weeks, cardiac hypertrophy, fibrosis, and cardiac function were examined. Compared with WT mice, Ctrp3 deficiency substantially impaired contractile dysfunction, exacerbated the enlargement of cardiomyocytes and myocardial fibrosis, and reprogramed the expression of pathological genes after TAC. Conversely, CTRP3 overexpression played a role in restoring the left ventricular cardiac contractile function, alleviating cardiac hypertrophy and fibrosis, and inhibiting the expression of hypertrophic and fibrotic signaling in mice after TAC. Furthermore, CTRP3 regulated the expression of the p38/CREB pathway and of the primary modulating factors of the endoplasmic reticulum stress, i.e., GRP78 and the downstream molecules eukaryotic translation inhibition factor 2 submit α, C/EBP homologous protein, and inositol-requiring enzyme-1. Further, inhibition of p38 MAPK by SB203580 blunted the ER stress intensified by Ctrp3 deficiency. In vitro, CTRP3 protected neonatal rat cardiac myocytes against phenylephrine-induced cardiomyocyte hypertrophy. We conclude that CTRP3 protects the host against pathological cardiac remodeling and left ventricular dysfunction induced by pressure overload largely by inhibiting the p38/CREB pathway and alleviating p38-induced ER stress.

C1q/tumor necrosis factor-related protein-3-engineered mesenchymal stromal cells attenuate cardiac impairment in mice with myocardial infarction.

Mesenchymal stromal cells (MSCs) transplantation offers an attractive alternative in myocardial infarctive therapy. However, poor cell engraftment and survival limit their restorative capacity. C1q/tumor necrosis factor-related protein-3 (CTRP3) inhibits reverse remodeling after myocardial infarction (MI) and was found to be secreted by MSCs in our preliminary experiments. We examined whether the overexpression of CTRP3 improved the survival of transplanted MSCs and augmented their efficacy on MI and whether silencing CTRP3 attenuated these effects. For gain-of-function analysis, MSCs overexpressing CTRP3 (LvC3-MSCs), control virus-transfected MSCs (LvNull-MSCs), MSCs alone, or phosphate-buffered saline (PBS) were injected into the peripheral areas of the infarction immediately after coronary artery ligation. For loss-of-function analysis, mice subjected to MI were randomized into groups and administered CTRP3-knockdown MSCs (LvshC3-MSCs), Lvshctrl-MSCs, MSCs, or PBS. Survival rates, cardiac function, and myocardial remodeling in mice were evaluated after 4 weeks. Injection of MSCs or LvNull-MSCs improved the left ventricular ejection fraction, inhibited cardiac fibrosis, and regulated cellular profiles of the infarction border zone 4 weeks after MI compared with those in the PBS group. Furthermore, overexpression of hCTRP3 promoted the efficacy of MSCs in the treatment of MI. However, knocking down CTRP3 impaired that. Coculture experiments confirmed that hCTRP3-enriched conditioned medium (CM) promoted MSCs migration and protected against H2O2-induced cell damage. Conversely, CM from C3-/- MSCs (CTRP3 knock out) significantly reduced the migration and antioxidative effects of MSCs. CTRP3 protein alone promoted MSCs proliferation and migration by upregulating matrix metalloproteinase 9 (MMP9) and protecting against oxidation by increasing superoxide dismutase 2 (SOD2) and metallothionein 1/2 (MT1/2) expression; and these effects were blocked by pretreatment with the extracellular signal-regulated kinase (ERK1/2) inhibitor U0126. Overexpression of CTRP3 significantly improved the MSCs-based efficacy on MI by increasing cell survival and retention via a mechanism involving ERK1/2-MMP9 and ERK1/2-SOD2/MT1/2 signaling.

Asprosin improves the survival of mesenchymal stromal cells in myocardial infarction by inhibiting apoptosis via the activated ERK1/2-SOD2 pathway.

AIMS: Several adipokines have been proven to improve the therapeutic efficacy of mesenchymal stromal cells (MSCs) when used to treat ischemic heart disease. Asprosin (ASP) is a newly-discovered adipokine. ASP might also predict the severity of coronary pathology. We investigated the role of ASP on MSCs and the effects of ASP-pretreated MSCs on myocardial infarction (MI). MAIN METHODS: MSCs were labelled with a lentivirus carrying green fluorescent protein (GFP). For in vivo study, after pretreatment with vehicle or ASP, MSCs were injected into infarcted hearts. Cardiac function and fibrosis were then evaluated 4 weeks after the induction of MI and survival of MSCs evaluated after 1 week. MSCs proliferation and migration were investigated after ASP treatment in vitro. MSCs apoptosis induced by hydrogen peroxide (H2O2) was assessed using flow cytometry. KEY FINDINGS: Compared to vehicle-pretreated MSCs, ASP-pretreated MSCs significantly improved the left ventricular ejection fraction (LVEF), and inhibited myocardial fibrosis 4 weeks after MI. ASP pretreatment may have promoted homing of transplanted MSCs. In vitro results showed that ASP had no significant effect on MSC proliferation and migration, but protected these cells from H2O2-induced apoptosis. Among 21 molecules associated with antioxidation and cell death, the antioxidant enzyme SOD2 was significantly upregulated by ASP. Furthermore, ASP treatment inhibited H2O2-induced ROS generation and apoptosis via the activated ERK1/2-SOD2 pathway. SIGNIFICANCE: This is the first evidence that ASP can regulate MSCs function and enhance MSCs therapy for ischemic heart disease. Furthermore, we demonstrate that ASP protects MSCs from oxidative stress-induced apoptosis via the ERK1/2-SOD2 pathway.

GPR 30 reduces myocardial infarct area and fibrosis in female ovariectomized mice by activating the PI3K/AKT pathway.

AIMS: Estrogen plays an important role in cardioprotection. Animal experiments showed that the G-protein coupled estrogen receptor 30 (GPR30) specific agonist G1 could reduce post-ischemic dysfunction and inhibit cardiac fibroblast proliferation. However, the underlying mechanism of action is not clear. The current study tests the hypothesis that GPR30 reduces myocardial infarct area and fibrosis in female ovariectomized (OVX) mice by activating the PI3K/AKT pathway. MAIN METHODS: In this study, we established a myocardial infarction (MI) animal model derived from OVX C57BL/6 female mice, and investigated the effect of G1 on cardiac function by echocardiography and Hemodynamics, morphology and expression of fibrosis-related and apoptosis-related proteins by Masson's trichrome and H&E, Immunofluorescence, Western blotting and TUNEL. KEY FINDINGS: Combination with OVX significantly increased myocardial fibrosis and MI area compared to MI treatment alone, as determined by echocardiography and hemodynamics. Further addition of G1 changed the expression of apoptosis-related proteins, decreased the levels of tumor necrosis factor-α and interleukin-10, and reduced the degree of myocardial fibrosis and myocardial infarct area. Primary cultured cardiac fibroblasts (CFs) were subjected to hypoxia/serum deprivation (H/SD) simulating the in vivo ischemia model. When the PI3K/AKT pathway was inhibited by wortmanin in H/SD CFs, G1 failed to induce significant changes in the expression of apoptosis-related proteins. SIGNIFICANCE: It suggested that GPR30 may improve cardiac function in female OVX mice by activating the PI3K/AKT pathway and reducing myocardial infarct size and fibrosis.

GPR30 Attenuates Myocardial Fibrosis in Diabetic Ovariectomized Female Rats: Role of iNOS Signaling.

Premenopausal women have a reduced risk for cardiovascular disease. Estrogen deficiency augments cardiac inflammation and oxidative stress and, thereby, aggravates myocardial fibrosis (MF) and diastolic dysfunction in hypertensive female rats. However, estrogen replacement therapy has no effect on myocardial infarction and cardiac fibrosis in postmenopausal women. Further clinical studies showed that high blood glucose levels in patients with diabetes is an important cause of MF, but the underlying mechanism is unclear. To experimentally address this issue, diabetes mellitus (DM) was induced by injecting streptozotocin and administering a high-fat diet in ovariectomized (OVX) rats. High degrees of fibrosis and apoptosis were detected in the cardiac tissue of these rats, together with increased expression of iNOS. Further treatment with the G protein-coupled estrogen receptor 30 (GPR30) agonist G1 decreased iNOS expression and the apoptosis rate in cardiac tissue significantly and inhibited cardiac fibroblast (CF) proliferation. Similar trends were observed in cultured CFs treated with high concentrations of fat and glucose. In addition, treatment with the iNOS-specific inhibitor W1400 attenuated iNOS and vimentin expression, which is associated with a marked reduction in MF. These results suggest that GPR30 activation inhibits MF in diabetic OVX female rats by suppressing cardiac iNOS activity and consequently NO levels. Thus, GPR30 activation may provide novel cardioprotection strategies for postmenopausal women, especially those with DM.

Short-Duration Swimming Exercise after Myocardial Infarction Attenuates Cardiac Dysfunction and Regulates Mitochondrial Quality Control in Aged Mice.

BACKGROUND: Exercise benefits to cardiac rehabilitation (CR) following stable myocardial infarction (MI). The suitable exercise duration for aged patients with coronary heart disease (CHD) remains controversial, and the underlying molecular mechanism is still unclear. METHODS AND RESULTS: 18-Month-old mice after stable MI were randomly submitted to different durations of exercise, including 15 and 60 min swimming training (ST) once per day, five times a week for 8 weeks. Compared to sedentary mice, 15 min ST, rather than 60 min ST, significantly augmented left ventricular function, increased survival rate, and suppressed myocardial fibrosis and apoptosis. 15 min ST improved mitochondrial morphology via regulating mitochondrial fission-fusion signaling. 15 min ST regulated mitophagy signaling via inhibiting LC3-II and P62 levels and increasing PINK/Parkin expression. 15 min ST also inhibited ROS production and enhanced antioxidant SOD2 activity. Notably, 15 min ST significantly increased sirtuin (SIRT) 3 level (2.7-fold) in vivo while the inhibition of SIRT3 exacerbated senescent H9c2 cellular LDH release and ROS production under hypoxia. In addition, SIRT3 silencing impairs mitochondrial dynamics and mitophagy in senescent cardiomyocytes against simulated ischemia (SI) injury. CONCLUSION: Collectively, our study demonstrated for the first time that sustained short-duration exercise, rather than long-duration exercise, attenuates cardiac dysfunction after MI in aged mice. It is likely that the positive regulation induced by a short-duration ST regimen on the elevated SIRT3 protein level improved mitochondrial quality control and decreased apoptosis and fibrosis contributed to the observed more resistant phenotype.

Cardiac-derived CTRP9 protects against myocardial ischemia/reperfusion injury via calreticulin-dependent inhibition of apoptosis.

Cardiokines play an essential role in maintaining normal cardiac functions and responding to acute myocardial injury. Studies have demonstrated the heart itself is a significant source of C1q/TNF-related protein 9 (CTRP9). However, the biological role of cardiac-derived CTRP9 remains unclear. We hypothesize cardiac-derived CTRP9 responds to acute myocardial ischemia/reperfusion (MI/R) injury as a cardiokine. We explored the role of cardiac-derived CTRP9 in MI/R injury via genetic manipulation and a CTRP9-knockout (CTRP9-KO) animal model. Inhibition of cardiac CTRP9 exacerbated, whereas its overexpression ameliorated, left ventricular dysfunction and myocardial apoptosis. Endothelial CTRP9 expression was unchanged while cardiomyocyte CTRP9 levels decreased after simulated ischemia/`reperfusion (SI/R) in vitro. Cardiomyocyte CTRP9 overexpression inhibited SI/R-induced apoptosis, an effect abrogated by CTRP9 antibody. Mechanistically, cardiac-derived CTRP9 activated anti-apoptotic signaling pathways and inhibited endoplasmic reticulum (ER) stress-related apoptosis in MI/R injury. Notably, CTRP9 interacted with the ER molecular chaperone calreticulin (CRT) located on the cell surface and in the cytoplasm of cardiomyocytes. The CTRP9-CRT interaction activated the protein kinase A-cAMP response element binding protein (PKA-CREB) signaling pathway, blocked by functional neutralization of the autocrine CTRP9. Inhibition of either CRT or PKA blunted cardiac-derived CTRP9's anti-apoptotic actions against MI/R injury. We further confirmed these findings in CTRP9-KO rats. Together, these results demonstrate that autocrine CTRP9 of cardiomyocyte origin protects against MI/R injury via CRT association, activation of the PKA-CREB pathway, ultimately inhibiting cardiomyocyte apoptosis.