S100a8/9 (S100 Calcium Binding Protein a8/9) Promotes Cardiac Hypertrophy Via Upregulation of FGF23 (Fibroblast Growth Factor 23) in Mice.

BACKGROUND: S100a8/9 (S100 calcium binding protein a8/9) belongs to the S100 family and has gained a lot of interest as a critical regulator of inflammatory response. Our previous study found that S100a8/9 homolog promoted aortic valve sclerosis in mice with chronic kidney disease. However, the role of S100a8/9 in pressure overload-induced cardiac hypertrophy remains unclear. The present study was to explore the role of S100a8/9 in cardiac hypertrophy. METHODS AND RESULTS: Cardiomyocyte-specific S100a9 loss or gain of function was achieved using an adeno-associated virus system, and the model of cardiac hypertrophy was established by aortic banding-induced pressure overload. The results indicate that S100a8/9 expression was increased in response to pressure overload. S100a9 deficiency alleviated pressure overload-induced hypertrophic response, whereas S100a9 overexpression accelerated cardiac hypertrophy. S100a9-overexpressed mice showed increased FGF23 (fibroblast growth factor 23) expression in the hearts after exposure to pressure overload, which activated calcineurin/NFAT (nuclear factor of activated T cells) signaling in cardiac myocytes and thus promoted hypertrophic response. A specific antibody that blocks FGFR4 (FGF receptor 4) largely abolished the prohypertrophic response of S100a9 in mice. CONCLUSIONS: In conclusion, S100a8/9 promoted the development of cardiac hypertrophy in mice. Targeting S100a8/9 may be a promising therapeutic approach to treat cardiac hypertrophy.

USP28 Serves as a Key Suppressor of Mitochondrial Morphofunctional Defects and Cardiac Dysfunction in the Diabetic Heart.

BACKGROUND: The majority of people with diabetes are susceptible to cardiac dysfunction and heart failure, and conventional drug therapy cannot correct diabetic cardiomyopathy progression. Herein, we assessed the potential role and therapeutic value of USP28 (ubiquitin-specific protease 28) on the metabolic vulnerability of diabetic cardiomyopathy. METHODS: The type 2 diabetes mouse model was established using db/db leptin receptor-deficient mice and high-fat diet/streptozotocin-induced mice. Cardiac-specific knockout of USP28 in the db/db background mice was generated by crossbreeding db/m and Myh6-Cre+/USP28fl/fl mice. Recombinant adeno-associated virus serotype 9 carrying USP28 under cardiac troponin T promoter was injected into db/db mice. High glucose plus palmitic acid-incubated neonatal rat ventricular myocytes and human induced pluripotent stem cell-derived cardiomyocytes were used to imitate diabetic cardiomyopathy in vitro. The molecular mechanism was explored through RNA sequencing, immunoprecipitation and mass spectrometry analysis, protein pull-down, chromatin immunoprecipitation sequencing, and chromatin immunoprecipitation assay. RESULTS: Microarray profiling of the UPS (ubiquitin-proteasome system) on the basis of db/db mouse hearts and diabetic patients' hearts demonstrated that the diabetic ventricle presented a significant reduction in USP28 expression. Diabetic Myh6-Cre+/USP28fl/fl mice exhibited more severe progressive cardiac dysfunction, lipid accumulation, and mitochondrial disarrangement, compared with their controls. On the other hand, USP28 overexpression improved systolic and diastolic dysfunction and ameliorated cardiac hypertrophy and fibrosis in the diabetic heart. Adeno-associated virus serotype 9-USP28 diabetic mice also exhibited less lipid storage, reduced reactive oxygen species formation, and mitochondrial impairment in heart tissues than adeno-associated virus serotype 9-null diabetic mice. As a result, USP28 overexpression attenuated cardiac remodeling and dysfunction, lipid accumulation, and mitochondrial impairment in high-fat diet/streptozotocin-induced type 2 diabetes mice. These results were also confirmed in neonatal rat ventricular myocytes and human induced pluripotent stem cell-derived cardiomyocytes. RNA sequencing, immunoprecipitation and mass spectrometry analysis, chromatin immunoprecipitation assays, chromatin immunoprecipitation sequencing, and protein pull-down assay mechanistically revealed that USP28 directly interacted with PPARα (peroxisome proliferator-activated receptor α), deubiquitinating and stabilizing PPARα (Lys152) to promote Mfn2 (mitofusin 2) transcription, thereby impeding mitochondrial morphofunctional defects. However, such cardioprotective benefits of USP28 were largely abrogated in db/db mice with PPARα deletion and conditional loss-of-function of Mfn2. CONCLUSIONS: Our findings provide a USP28-modulated mitochondria homeostasis mechanism that involves the PPARα-Mfn2 axis in diabetic hearts, suggesting that USP28 activation or adeno-associated virus therapy targeting USP28 represents a potential therapeutic strategy for diabetic cardiomyopathy.

Metabolic landscape in cardiac aging: insights into molecular biology and therapeutic implications.

Cardiac aging is evident by a reduction in function which subsequently contributes to heart failure. The metabolic microenvironment has been identified as a hallmark of malignancy, but recent studies have shed light on its role in cardiovascular diseases (CVDs). Various metabolic pathways in cardiomyocytes and noncardiomyocytes determine cellular senescence in the aging heart. Metabolic alteration is a common process throughout cardiac degeneration. Importantly, the involvement of cellular senescence in cardiac injuries, including heart failure and myocardial ischemia and infarction, has been reported. However, metabolic complexity among human aging hearts hinders the development of strategies that targets metabolic susceptibility. Advances over the past decade have linked cellular senescence and function with their metabolic reprogramming pathway in cardiac aging, including autophagy, oxidative stress, epigenetic modifications, chronic inflammation, and myocyte systolic phenotype regulation. In addition, metabolic status is involved in crucial aspects of myocardial biology, from fibrosis to hypertrophy and chronic inflammation. However, further elucidation of the metabolism involvement in cardiac degeneration is still needed. Thus, deciphering the mechanisms underlying how metabolic reprogramming impacts cardiac aging is thought to contribute to the novel interventions to protect or even restore cardiac function in aging hearts. Here, we summarize emerging concepts about metabolic landscapes of cardiac aging, with specific focuses on why metabolic profile alters during cardiac degeneration and how we could utilize the current knowledge to improve the management of cardiac aging.

Cardiac Involvement in COVID-19: A Global Bibliometric and Visualized Analysis.

Objective: Coronavirus disease 2019 (COVID-19), which was caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), had already resulted in widespread epidemics worldwide and millions of people's deaths since its outbreak in 2019. COVID-19 had also been demonstrated to affect people's cardiac function. However, the specific mechanism and influence of this damage were not clear yet. The purpose of the present study was to provide a bibliometric analysis of the current studies related to cardiac involvement after SARS-CoV-2 infection. Methods: A bibliometric literature search was performed on the web of science. The number and type of publications, countries, institutional sources, journals, and citation patterns were analyzed. In addition, qualitative and quantitative evaluations were carried out to visualize the scientific achievements in this field by using the VOSviewer software. Results: Web of science had recorded 2,24,097 documents on COVID-19 at the time of data collection (May 12, 2022). A total of 2,025 documents related to cardiac involvement were recorded at last. The countries with the most published articles were the United States of America (USA) (n =747, 36.9%), Italy (n =324, 16%), and England (n =213, 10.5%). Although the countries and institutions that published the most articles were mainly from the USA, the top three authors were from Germany, England, and Poland. Frontiers in Cardiovascular Medicine was the journal with the most studies (65 3.2%), followed by ESC Heart Failure (59 2.9%) and Journal of Clinical Medicine (56 2.8%). We identified 13,739 authors, among which Karin Klingel and Amer Harky had the most articles, and Shaobo Shi was co-cited most often. There existed some cooperation between different authors, but the scope was limited. Myocarditis and heart failure (HF) were the main research hotspots of COVID-19 on cardiac dysfunction and may be crucial to the prognosis of patients. Conclusions: It was the first bibliometric analysis of publications related to COVID-19-associated cardiac disorder. This study provided academics and researchers with useful information on the most influential articles of COVID-19 and cardiac dysfunction. Cooperation between countries and institutions must be strengthened on myocarditis and HF during COVID-19 pandemic.

PD-1 inhibitor induces myocarditis by reducing regulatory T cells, activating inflammatory responses, promoting myocardial apoptosis and autophagy.

The present study aimed to explore the pathogenesis of autoimmune myocarditis induced by PD-1 inhibitors and their potential therapeutic targets. Mouse models of autoimmune myocarditis induced by PD-1 inhibitor in mouse models of polymyositis were established. The expression level of PD-1 and regulatory T cells (Tregs), CD4, CD8 + T cells, inflammation, apoptosis and autophagy-related factors, including IL-6, TGF-ß, AMA-M2, Fas/FasL, LC3 and p62 were detected in peripheral blood, muscle or myocardium of mice in each group, using ELISA, RT-PCR, Western Blot and immunofluorescence. In addition, HE and TUNEL staining and ultrastructural scanning were performed on the myocardium of mice in each group. Results showed that the expression level of PD-1 in the two myositis groups was significantly lower than that in the control group, and the level of PD-1 was lower in the myocarditis group than that in the polymyositis group. In the myocardium, TGF-ß, p62, and Tregs proportion showed the same expression level trend as PD-1, while CD8, IL-6, IL-10 and LC3 showed the opposite trend. Levels of Fas/FasL were significantly higher in both myositis groups, but were slightly lower in the myocarditis group, as was AMA-M2. Inflammation, apoptosis, and autophagy were observed in both myositis groups, but were more severe in the myocarditis group. In summary, the decreased expression level of PD-1 leads to decreased Tregs level in the myocardium, aggravated inflammatory response, apoptosis and autophagy, which may be the pathological mechanism of myocarditis induced by PD-1 inhibitors.

Spatial region-resolved proteome map reveals mechanism of COVID-19-associated heart injury.

Direct myocardial and vascular injuries due to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection-driven inflammation is the leading cause of acute cardiac injury associated with coronavirus disease 2019 (COVID-19). However, in-depth knowledge of the injury characteristics of the heart affected by inflammation is lacking. In this study, using a quantitative spatial proteomics strategy that combines comparative anatomy, laser-capture microdissection, and histological examination, we establish a region-resolved proteome map of the myocardia and microvessels with obvious inflammatory cells from hearts of patients with COVID-19. A series of molecular dysfunctions of myocardia and microvessels is observed in different cardiac regions. The myocardia and microvessels of the left atrial are the most susceptible to virus infection and inflammatory storm, suggesting more attention should be paid to the lesion and treatment of these two parts. These results can guide in improving clinical treatments for cardiovascular diseases associated with COVID-19.

Manifestations and Mechanism of SARS-CoV2 Mediated Cardiac Injury.

Coronavirus disease 2019 (COVID-19), a global pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV2) had resulted in considerable morbidity and mortality. COVID-19 primarily posed a threat to the respiratory system and violated many different organs, including the heart, kidney, liver, and blood vessels with the development of the disease. Severe patients were often accompanied by cardiac injury, and once the heart gets damaged, the mortality of patients will significantly increase. The main clinical manifestations of cardiac injury range from myocarditis, heart failure (HF), arrhythmia, and Takotsubo cardiomyopathy (TCM). A high abundance of angiotensin-converting enzyme II (ACE2) on the membrane of cardiomyocytes makes it possible that the virus can directly attack cardiomyocytes as subsequently evidenced by the detection of spike protein and virus RNA in autopsy cardiac tissues. The secondary myocardial injury through systemic inflammatory and immune response also caused obvious cardiac damage. The pathological manifestations of heart tissue were diverse, varied from mild cardiomyocyte edema, myocardial hypertrophy, cardiomyocyte degeneration, and necrosis to severe myocarditis caused by lymphocyte and macrophage infiltration. However, the mechanism of heart injury was still unclear. Here, we summarized the clinical manifestations and mechanism of SARS-CoV2 mediated cardiac injury, providing a reference for cardiac treatment in critically ill patients.

Fibronectin type III domain-containing 5 improves aging-related cardiac dysfunction in mice.

Aging is an important risk factor for cardiovascular diseases, and aging-related cardiac dysfunction serves as a major determinant of morbidity and mortality in elderly populations. Our previous study has identified fibronectin type III domain-containing 5 (FNDC5) and its cleaved form, irisin, as the cardioprotectant against doxorubicin-induced cardiomyopathy. Herein, aging or matched young mice were overexpressed with FNDC5 by adeno-associated virus serotype 9 (AAV9) vectors, or subcutaneously infused with irisin to uncover the role of FNDC5 in aging-related cardiac dysfunction. To verify the involvement of nucleotide-binding oligomerization domain-like receptor with a pyrin domain 3 (NLRP3) and AMP-activated protein kinase α (AMPKα), Nlrp3 or Ampkα2 global knockout mice were used. Besides, young mice were injected with AAV9-FNDC5 and maintained for 12 months to determine the preventive effect of FNDC5. Moreover, neonatal rat cardiomyocytes were stimulated with tumor necrosis factor-α (TNF-α) to examine the role of FNDC5 in vitro. We found that FNDC5 was downregulated in aging hearts. Cardiac-specific overexpression of FNDC5 or irisin infusion significantly suppressed NLRP3 inflammasome and cardiac inflammation, thereby attenuating aging-related cardiac remodeling and dysfunction. In addition, irisin treatment also inhibited cellular senescence in TNF-α-stimulated cardiomyocytes in vitro. Mechanistically, FNDC5 activated AMPKα through blocking the lysosomal degradation of glucagon-like peptide-1 receptor. More importantly, FNDC5 gene transfer in early life could delay the onset of cardiac dysfunction during aging process. We prove that FNDC5 improves aging-related cardiac dysfunction by activating AMPKα, and it might be a promising therapeutic target to support cardiovascular health in elderly populations.

Osteocrin, a novel myokine, prevents diabetic cardiomyopathy via restoring proteasomal activity.

Proteasomal activity is compromised in diabetic hearts that contributes to proteotoxic stresses and cardiac dysfunction. Osteocrin (OSTN) acts as a novel exercise-responsive myokine and is implicated in various cardiac diseases. Herein, we aim to investigate the role and underlying molecular basis of OSTN in diabetic cardiomyopathy (DCM). Mice received a single intravenous injection of the cardiotrophic adeno-associated virus serotype 9 to overexpress OSTN in the heart and then were exposed to intraperitoneal injections of streptozotocin (STZ, 50 mg/kg) for consecutive 5 days to generate diabetic models. Neonatal rat cardiomyocytes were isolated and stimulated with high glucose to verify the role of OSTN in vitro. OSTN expression was reduced by protein kinase B/forkhead box O1 dephosphorylation in diabetic hearts, while its overexpression significantly attenuated cardiac injury and dysfunction in mice with STZ treatment. Besides, OSTN incubation prevented, whereas OSTN silence aggravated cardiomyocyte apoptosis and injury upon hyperglycemic stimulation in vitro. Mechanistically, OSTN treatment restored protein kinase G (PKG)-dependent proteasomal function, and PKG or proteasome inhibition abrogated the protective effects of OSTN in vivo and in vitro. Furthermore, OSTN replenishment was sufficient to prevent the progression of pre-established DCM and had synergistic cardioprotection with sildenafil. OSTN protects against DCM via restoring PKG-dependent proteasomal activity and it is a promising therapeutic target to treat DCM.

Endothelial ERG alleviates cardiac fibrosis via blocking endothelin-1-dependent paracrine mechanism.

Cardiac endothelium communicates closely with adjacent cardiac cells by multiple cytokines and plays critical roles in regulating fibroblasts proliferation, activation, and collagen synthesis during cardiac fibrosis. E26 transformation-specific (ETS)-related gene (ERG) belongs to the ETS transcriptional factor family and is required for endothelial cells (ECs) homeostasis and cardiac development. This study aims at investigating the potential role and molecular basis of ERG in fibrotic remodeling within the adult heart. We observed that ERG was abundant in murine hearts, especially in cardiac ECs, but decreased during cardiac fibrosis. ERG knockdown within murine hearts caused spontaneously cardiac fibrosis and dysfunction, accompanied by the activation of multiple Smad-dependent and independent pathways. However, the direct silence of ERG in cardiac fibroblasts did not affect the expression of fibrotic markers. Intriguingly, ERG knockdown in human umbilical vein endothelial cells (HUVECs) promoted the secretion of endothelin-1 (ET-1), which subsequently accelerated the proliferation, phenotypic transition, and collagen synthesis of cardiac fibroblasts in a paracrine manner. Suppressing ET-1 with either a neutralizing antibody or a receptor blocker abolished ERG knockdown-mediated deleterious effect in vivo and in vitro. This pro-fibrotic effect was also negated by RGD (Arg-Gly-Asp)-peptide magnetic nanoparticles target delivery of ET-1 small interfering RNA to ECs in mice. More importantly, we proved that endothelial ERG overexpression notably prevented pressure overload-induced cardiac fibrosis. Collectively, endothelial ERG alleviates cardiac fibrosis via blocking ET-1-dependent paracrine mechanism and it functions as a candidate for treating cardiac fibrosis. • ERG is abundant in murine hearts, especially in cardiac ECs, but decreased during fibrotic remodeling. • ERG knockdown causes spontaneously cardiac fibrosis and dysfunction. • ERG silence in HUVECs promotes the secretion of endothelin-1, which in turn activates cardiac fibroblasts in a paracrine manner. • Endothelial ERG overexpression prevents pressure overload-induced cardiac fibrosis.

Meteorin-like protein attenuates doxorubicin-induced cardiotoxicity via activating cAMP/PKA/SIRT1 pathway.

Meteorin-like (METRNL) protein is a newly identified myokine that functions to modulate energy expenditure and inflammation in adipose tissue. Herein, we aim to investigate the potential role and molecular basis of METRNL in doxorubicin (DOX)-induced cardiotoxicity. METRNL was found to be abundantly expressed in cardiac muscle under physiological conditions that was decreased upon DOX exposure. Cardiac-specific overexpression of METRNL by adeno-associated virus serotype 9 markedly improved oxidative stress, apoptosis, cardiac dysfunction and survival status in DOX-treated mice. Conversely, knocking down endogenous METRNL by an intramyocardial injection of adenovirus exacerbated DOX-induced cardiotoxicity and death. Meanwhile, METRNL overexpression attenuated, while METRNL silence promoted oxidative damage and apoptosis in DOX-treated H9C2 cells. Systemic METRNL depletion by a neutralizing antibody aggravated DOX-related cardiac injury and dysfunction in vivo, which were notably alleviated by METRNL overexpression within the cardiomyocytes. Besides, we detected robust METRNL secretion from isolated rodent hearts and cardiomyocytes, but to a less extent in those with DOX treatment. And the beneficial effects of METRNL in H9C2 cells disappeared after the incubation with a METRNL neutralizing antibody. Mechanistically, METRNL activated SIRT1 via the cAMP/PKA pathway, and its antioxidant and antiapoptotic capacities were blocked by SIRT1 deficiency. More importantly, METRNL did not affect the tumor-killing action of DOX in 4T1 breast cancer cells and tumor-bearing mice. Collectively, cardiac-derived METRNL activates SIRT1 via cAMP/PKA signaling axis in an autocrine manner, which ultimately improves DOX-elicited oxidative stress, apoptosis and cardiac dysfunction. Targeting METRNL may provide a novel therapeutic strategy for the prevention of DOX-associated cardiotoxicity.

FNDC5 alleviates oxidative stress and cardiomyocyte apoptosis in doxorubicin-induced cardiotoxicity via activating AKT.

Oxidative stress and cardiomyocyte apoptosis play critical roles in doxorubicin (DOX)-induced cardiotoxicity. Previous studies indicated that fibronectin type III domain-containing 5 (FNDC5) and its cleaved form, irisin, could preserve mitochondrial function and attenuate oxidative damage as well as cell apoptosis, however, its role in DOX-induced cardiotoxicity remains unknown. Our present study aimed to investigate the role and underlying mechanism of FNDC5 on oxidative stress and cardiomyocyte apoptosis in DOX-induced cardiotoxicity. Cardiomyocyte-specific FNDC5 overexpression was achieved using an adeno-associated virus system, and then the mice were exposed to a single intraperitoneal injection of DOX (15 mg/kg) to generate DOX-induced cardiotoxicity. Herein, we found that FNDC5 expression was downregulated in DOX-treated murine hearts and cardiomyocytes. Fndc5 deficiency resulted in increased oxidative damage and apoptosis in H9C2 cells under basal conditions, imitating the phenotype of DOX-induced cardiomyopathy in vitro, conversely, FNDC5 overexpression or irisin treatment alleviated DOX-induced oxidative stress and cardiomyocyte apoptosis in vivo and in vitro. Mechanistically, we identified that FNDC5/Irisin activated AKT/mTOR signaling and decreased DOX-induced cardiomyocyte apoptosis, and moreover, we provided direct evidence that the anti-oxidant effect of FNDC5/Irisin was mediated by the AKT/GSK3ß/FYN/Nrf2 axis in an mTOR-independent manner. And we also demonstrated that heat shock protein 20 was responsible for the activation of AKT caused by FNDC5/Irisin. In line with the data in acute model, we also found that FNDC5/Irisin exerted beneficial effects in chronic model of DOX-induced cardiotoxicity (5 mg/kg, i.p., once a week for three times, the total cumulative dose is 15 mg/kg) in mice. Based on these findings, we supposed that FNDC5/Irisin was a potential therapeutic agent against DOX-induced cardiotoxicity.

Rosmarinic acid alleviates cardiomyocyte apoptosis via cardiac fibroblast in doxorubicin-induced cardiotoxicity.

Cardiomyocyte apoptosis is a key event in the process of doxorubicin (DOX)-induced cardiotoxicity. Our previous study found that rosmarinic acid (RA) could attenuate pressure overload-induced cardiac dysfunction via cardiac fibroblasts (CFs), however its effect in DOX-induced cardiotoxicity remains unknown. In the present study, mice were subjected to a single intraperitoneal injection of DOX (15mg/kg) to generate DOX-induced cardiotoxicity. Histological examination, echocardiography, and molecular markers were used to evaluate the effects of RA. Neonatal rat cardiomyocytes (CMs) and CFs were used to verify the protective effect of RA in vitro. Conditioned medium derived from RA-treated CFs were prepared to illustrate the effect of RA on paracrine interplay between CFs and CMs. We found that RA significantly alleviated DOX-induced cardiomyocyte apoptosis and cardiac dysfunction in vivo, which, however, had almost negligible beneficial effect on DOX directly induced cardiomyocyte apoptosis in vitro. Mechanistically, CFs-derived Fas L was responsible for DOX-induced cardiomyocyte apoptosis, and RA treatment could decrease Fas L expression in CFs and its release to the conditioned medium by suppressing nuclear factor of activated T cells (NFAT) activation and metalloproteinase 7 (MMP7) expression, and exerted the anti-apoptotic effect on CMs via CFs. Ionomycin, and activator of NFAT, abrogated RA-mediated protective effect on cardiomyocyte apoptosis and cardiac dysfunction. In summary, RA alleviated cardiomyocyte apoptosis by inhibiting the expression and release of Fas L in CFs via a paracrine manner, moreover, NFAT as well as MMP7 inhibition were responsible for the suppression of Fas L. RA could be a powerful new therapeutic agent to mitigate cardiomyocyte apoptosis, thereby improving DOX-induced cardiotoxicity.

Piperine Alleviates Doxorubicin-Induced Cardiotoxicity via Activating PPAR-γ in Mice.

BACKGROUND: Oxidative stress, inflammation and cardiac apoptosis were closely involved in doxorubicin (DOX)-induced cardiac injury. Piperine has been reported to suppress inflammatory response and pyroptosis in macrophages. However, whether piperine could protect the mice against DOX-related cardiac injury remain unclear. This study aimed to investigate whether piperine inhibited DOX-related cardiac injury in mice. METHODS: To induce DOX-related acute cardiac injury, mice in DOX group were intraperitoneally injected with a single dose of DOX (15 mg/kg). To investigate the protective effects of piperine, mice were orally treated for 3 weeks with piperine (50 mg/kg, 18:00 every day) beginning two weeks before DOX injection. RESULTS: Piperine treatment significantly alleviated DOX-induced cardiac injury, and improved cardiac function. Piperine also reduced myocardial oxidative stress, inflammation and apoptosis in mice with DOX injection. Piperine also improved cell viability, and reduced oxidative damage and inflammatory factors in cardiomyocytes. We also found that piperine activated peroxisome proliferator-activated receptor-γ (PPAR-γ), and the protective effects of piperine were abolished by the treatment of the PPAR-γ antagonist in vivo and in vitro. CONCLUSIONS: Piperine could suppress DOX-related cardiac injury via activation of PPAR-γ in mice.

C1q-tumour necrosis factor-related protein-3 exacerbates cardiac hypertrophy in mice.

AIMS: C1q-tumour necrosis factor-related protein-3 (CTRP3) is an adipokine and a paralog of adiponectin. Our previous study showed that CTRP3 attenuated diabetes-related cardiomyopathy. However, the precise role of CTRP3 in cardiac hypertrophy remains unclear. This study was aimed to clarify the role of CTRP3 involved in cardiac hypertrophy. METHODS AND RESULTS: Cardiomyocyte-specific CTRP3 overexpression was achieved using an adeno-associated virus system, and cardiac CTRP3 expression was knocked down using gene delivery of specific short hairpin RNAs in vivo. CTRP3 expression was upregulated in murine hypertrophic hearts and failing human hearts. Increased CTRP3 was mainly derived from cardiomyocytes and induced by the production of reactive oxygen species (ROS) during the hypertrophic response. CTRP3-overexpressing mice exhibited exacerbated cardiac hypertrophy and cardiac dysfunction in response to pressure overload. Conversely, Ctrp3 deficiency in the heart resulted in an alleviated hypertrophic phenotype. CTRP3 induced hypertrophy in cardiomyocytes, which could be blocked by the addition of CTRP3 antibody in the media. Detection of signalling pathways showed that pressure overload-induced activation of the transforming growth factor ß-activated kinase 1 (TAK1)-c-Jun N-terminal kinase (JNK) pathway was enhanced by CTRP3 overexpression and inhibited by CTRP3 disruption. Furthermore, we found that CTRP3 lost its pro-hypertrophic effects in cardiomyocyte-specific Tak1 knockout mice. Protein kinase A (PKA) was involved in the activation of TAK1 by CTRP3. CONCLUSION: In conclusion, our results suggest that CTRP3 promotes pressure overload-induced cardiac hypertrophy via activation of the TAK1-JNK axis.

Overexpression of CTRP3 protects against sepsis-induced myocardial dysfunction in mice.

C1q/tumor necrosis factor-related protein-3 (CTRP3) shows striking homologies of genomic structure to the adiponectin. In this study, we aimed to investigate the protective role of CTRP3 against sepsis-induced cardiomyopathy. Here, we overexpressed CTRP3 in myocardium by direct intramyocardial injection and constructed a model of lipopolysaccharide (LPS)-induced sepsis in mice. Our results demonstrated that cardiac-specific overexpression of CTRP3 remarkably attenuated myocardial dysfunction and increased the phosphorylation level of AMPKα during LPS-induced sepsis. The anti-inflammatory effects of CTRP3, as determined by decreased mRNA levels of TNF-α, IL-6 and a lower protein expression of phosphorylated NF-κB p65 and IκBα, was detected in mice following LPS treatment. Additionally, CTRP3 suppressed cardiac apoptosis induced by LPS in mice as indicated by terminal deoxynucleotidyl transferase nick-end labeling (TUNEL) staining and western blot for Cleaved-caspase3, Bax and Bcl-2. In conclusion, CTRP3 could protect against sepsis-induced myocardial dysfunction in mice. The cardioprotective effects of CTRP3 might be mediated by activating AMPKα signaling pathway and blunting inflammatory response and apoptosis.

T-bet deficiency attenuates cardiac remodelling in rats.

Previous studies have suggested the involvement of CD4 + T lymphocytes in cardiac remodelling. T-bet can direct Th1 lineage commitment. This study aimed to investigate the functional significance of T-bet in cardiac remodelling induced by pressure overload using T-bet global knockout rats. Increased T-bet levels were observed in rodent and human hypertrophied hearts. T-bet deficiency resulted in a less severe hypertrophic phenotype in rats. CD4 + T-lymphocyte reconstitution in T-bet-/- rats resulted in aggravated cardiac remodelling. T-cell homing molecule expression and cytokine secretion were altered in T-bet-deficient rat hearts. Administration of exogenous interferon-γ (IFN-γ) offset T-bet deficiency-mediated cardioprotection. Cardiomyocytes cultured in T-bet-/- CD4 + T-cell-conditioned media showed a reduced hypertrophic response after hypertrophic stimuli, which was abolished by an IFN-γ-neutralizing antibody. Taken together, our findings show that T-bet deficiency attenuates pressure overload-induced cardiac remodelling in rats. Specifically, targeting T-bet in T cells may be of great importance for the treatment of pathological cardiac remodelling and heart failure.

Rosmarinic acid attenuates cardiac fibrosis following long-term pressure overload via AMPKα/Smad3 signaling.

Agonists of peroxisome proliferator-activated receptor gamma (PPAR-γ) can activate 5' AMP-activated protein kinase alpha (AMPKα) and exert cardioprotective effects. A previous study has demonstrated that rosmarinic acid (RA) can activate PPAR-γ, but its effect on cardiac remodeling remains largely unknown. Our study aimed to investigate the effect of RA on cardiac remodeling and to clarify the underlying mechanism. Mice were subjected to aortic banding to generate pressure overload induced cardiac remodeling and then were orally administered RA (100 mg/kg/day) for 7 weeks beginning 1 week after surgery. The morphological examination, echocardiography, and molecular markers were used to evaluate the effects of RA. To ascertain whether the beneficial effect of RA on cardiac fibrosis was mediated by AMPKα, AMPKα2 knockout mice were used. Neonatal rat cardiomyocytes and fibroblasts were separated and cultured to validate the protective effect of RA in vitro. RA-treated mice exhibited a similar hypertrophic response as mice without RA treatment, but had an attenuated fibrotic response and improved cardiac function after pressure overload. Activated AMPKα was essential for the anti-fibrotic effect of RA via inhibiting the phosphorylation and nuclear translocation of Smad3 in vivo and in vitro, and AMPKα deficiency abolished RA-mediated protective effects. Small interfering RNA against Ppar-γ (siPpar-γ) and GW9662, a specific antagonist of PPAR-γ, abolished RA-mediated AMPKα phosphorylation and alleviation of fibrotic response in vitro. RA attenuated cardiac fibrosis following long-term pressure overload via AMPKα/Smad3 signaling and PPAR-γ was required for the activation of AMPKα. RA might be a promising therapeutic agent against cardiac fibrosis.

CTRP3 protected against doxorubicin-induced cardiac dysfunction, inflammation and cell death via activation of Sirt1.

BACKGROUND: Inflammation and myocytes apoptosis play critical roles in the development of doxorubicin (DOX)-induced cardiotoxicity. Our previous study found that C1q/tumour necrosis factor-related protein-3 (CTRP3) could inhibit cardiac inflammation and apoptosis of myocytes but its role in DOX-induced heart injury remains largely unknown. Our study aimed to investigate whether CTRP3 protected against DOX-induced heart injury and the underlying mechanism. METHODS: We overexpressed CTRP3 in the hearts using an adeno-associated virus system. The mice were subjected to a single intraperitoneal injection of DOX (15mg/kg) to induce short-term model for cardiomyopathy. The morphological examination and biochemical analysis were used to evaluate the effects of CTRP3. H9C2 cells were used to verify the protective role of CTRP3 in vitro. RESULTS: Myocardial CTRP3 protein levels were reduced in DOX-treated mice. Cardiac specific-overexpression of CTRP3 preserved heart dysfunction, and attenuated cardiac inflammation and cell loss induced by DOX in vivo and in vitro. CTRP3 could activate silent information regulator 1 (Sirt1) in vivo and in vitro. Moreover, specific inhibitor of Sirt1 and the silence of Sirt1 could abolish the protective effects of CTRP3 against DOX-induced inflammation and apoptosis. CONCLUSION: CTRP3 protected against DOX-induced heart injury via activation of Sirt1. CTRP3 has therapeutic potential for the treatment of DOX cardiotoxicity.

Arctiin protects against cardiac hypertrophy through inhibiting MAPKs and AKT signaling pathways.

PURPOSE: The mitogen-activated protein kinases (MAPKs) and protein kinase B (AKT) pathways have emerged as essential intracellular signaling pathways in eukaryotic cells, particularly as regulators of cardiac hypertrophy. Previous studies indicated that arctiin, an active ingredient of biennial dried ripe burdock, could exhibit potent anti-inflammatory and anti-allergic activities via down-regulating the activation of MAPKs and AKT pathways. However, little is known about its effects on cardiac hypertrophy. Therefore, the present study aimed to explore whether arctiin could attenuate cardiac hypertrophy. GENERAL METHODS: Arctiin (80 mg/kg) was administered by oral gavage once daily for 3 weeks from 1 week after surgery. Then, the mice were subjected to either chronic pressure overload generated by aortic banding (AB) or sham surgery (control group). Cardiac function was assessed by echocardiography. FINDINGS: The results indicated that arctiin attenuated cardiac hypertrophy induced by AB, and suppressed cardiac fibrosis and accumulation of collagen in vivo. Arctiin also inhibit the activation of MAPKs and AKT occurs in response to hypertrophic stimuli. Arctiin attenuated phenylephrine-induced hypertrophy of myocytes in vitro. CONCLUSIONS: In conclusion, arctiin can improve cardiac function and prevent the development of cardiac hypertrophy by blocking the MAPKs and AKT signaling pathways.