Aucubin protects against pressure overload-induced cardiac remodelling via the β3 -adrenoceptor-neuronal NOS cascades

Medioresinol from Eucommiae cortex improves myocardial infarction-induced heart failure through activation of the PI3K/AKT/mTOR pathway: A network analysis and experimental study

OBJECTIVE

This study aims to systematically analyze the potential active components of Eucommiae cortex in the treatment of post- myocardial infarction heart failure through network analysis and molecular docking methods. In vitro experiments were conducted to verify that medioresinol, a component of Eucommiae cortex, improves oxygen-glucose deprivation-induced cell failure through its anti-inflammatory and antioxidant capacities.

METHODS

Potential active components of Eucommiae cortex were screened using specific data. The targets of these components were predicted using Swiss Institute of Bioinformatics database and TargetNet, and key targets were identified by intersecting with the disease targets of myocardial infarction and heart failure. Protein-Protein Interaction analysis was performed on the key targets to screen for core targets. Genomics Institute of the Novartis Research Foundation and Human Protein Atlas were used to identify myocardial highly expressed targets. Kyoto Encyclopedia of Genes and Genomes and Gene Ontology enrichment analyses were conducted using the Database for Annotation, Visualization, and Integrated Discovery. Molecular docking was performed for the final components and target proteins. In vitro experiments were carried out using H9c2 cells subjected to oxygen and glucose deprivation conditions to validate the effects of the screened potential active components.

RESULTS

Network analysis revealed that Eucommiae cortex might exert its effects through the phosphoinositide 3-kinase/protein kinase B/mammalian target of rapamycin (PI3K/AKT/mTOR), hypoxia-inducible factor 1, and Janus kinase/signal transducer and activator of transcription pathways, which are crucial for myocardial contraction, vascular tone regulation, inflammatory response, and oxidative stress. Molecular docking indicated stable binding of the selected compounds to PI3K, AKT, and mTOR. Medioresinol was selected for further study and shown to significantly improve oxidative stress and inflammatory response in myocardial ischemia-hypoxia model cells by activating the PI3K/AKT/mTOR pathway.

CONCLUSION

This study confirms the role of the PI3K/AKT/mTOR pathway in the cardiovascular protective effects of Eucommiae cortex and provides evidence at the cellular level. Medioresinol demonstrated potential therapeutic effects on myocardial infarction induced heart failure by reducing oxidative stress and inflammatory responses. These findings offer a theoretical basis for the application of Eucommiae cortex in the treatment of heart failure and support the development of new therapeutic drugs for cardiovascular diseases. Future research should further validate these effects in animal models and explore the overall efficacy of Eucommiae cortex.

Meteorin‑like/meteorin‑β protects against cardiac dysfunction after myocardial infarction in mice by inhibiting autophagy

Meteorin-β (Metrnβ) is a protein that is secreted by skeletal muscle and adipose tissue, and participates in cardiovascular diseases. However, its role in myocardial infarction (MI) has not been fully elucidated to date. The aim of the present study was to investigate the role and underlying mechanism of Metrnβ in MI. In the present study, mice were subjected to left coronary ligation to induce a MI model before being injected with adeno-associated virus 9 (AAV9)-Metrnβ to overexpress Metrnβ. Mice were subjected to echocardiography and pressure-volume measurements 2 weeks after ligation. Cardiac injury was measured from the levels of cardiac troponin T and pro-inflammatory factors, which were detected using ELISA kits. Cardiac remodelling was determined from the cross-sectional areas detected using H&E and wheat germ agglutinin staining as well as from the transcriptional levels of hypertrophic and fibrosis markers detected using reverse transcription-quantitative PCR. Cardiac function was detected using echocardiography and pressure-volume measurements. In addition, H9c2 cardiomyocytes were transfected with Ad-Metrnβ to overexpress Metrnβ, before being exposed to hypoxia to induce ischaemic injury. Apoptosis was determined using TUNEL staining and caspase 3 activity. Cell inflammation was detected using ELISA assays for pro-inflammatory factors. Autophagy was detected using LC3 staining and assessing the protein level of LC3II using western blotting. H9c2 cells were also treated with rapamycin to induce autophagy. It was revealed that Metrnβ expression was reduced in both mouse serum and heart tissue 2 weeks post-MI. Metrnβ overexpression using AAV9-Metrnβ delivery reduced the mortality rate, decreased the infarction size and reduced the extent of myocardial injury 2 weeks post-MI. Furthermore, Metrnβ overexpression inhibited cardiac hypertrophy, fibrosis and inflammation post-MI. In ischaemic H9c2 cells, Metrnβ overexpression using adenovirus also reduced cell injury, cell death and inflammatory response. Metrnβ overexpression suppressed MI-induced autophagy in vitro. Following autophagy activation using rapamycin in vitro, the protective effects induced by Metrnβ were reversed. Taken together, these results indicated that Metrnβ could protect against cardiac dysfunction post-MI in mice by inhibiting autophagy.

USP38 exacerbates pressure overload-induced left ventricular electrical remodeling

BACKGROUND

Ubiquitin-specific protease 38 (USP38), belonging to the USP family, is recognized for its role in controlling protein degradation and diverse biological processes. Ventricular arrhythmias (VAs) following heart failure (HF) are closely linked to ventricular electrical remodeling, yet the specific mechanisms underlying VAs in HF remain inadequately explored. In this study, we examined the impact of USP38 on VAs in pressure overload-induced HF.

METHODS

Cardiac-specific USP38 knockout mice, cardiac-specific USP38 transgenic mice and their matched control littermates developed HF induced by aortic banding (AB) surgery. After subjecting the mice to AB surgery for a duration of four weeks, comprehensive investigations were conducted, including pathological analysis and electrophysiological assessments, along with molecular analyses.

RESULTS

We observed increased USP38 expression in the left ventricle of mice with HF. Electrocardiogram showed that the USP38 knockout shortened the QRS interval and QTc, while USP38 overexpression prolonged these parameters. USP38 knockout decreased the susceptibility of VAs by shortening action potential duration (APD) and prolonging effective refractory period (ERP). In addition, USP38 knockout increased ion channel and Cx43 expression in ventricle. On the contrary, the increased susceptibility of VAs and the decreased expression of ventricular ion channels and Cx43 were observed with USP38 overexpression. In both in vivo and in vitro experiments, USP38 knockout inhibited TBK1/AKT/CAMKII signaling, whereas USP38 overexpression activated this pathway.

CONCLUSION

Our data indicates that USP38 increases susceptibility to VAs after HF through TBK1/AKT/CAMKII signaling pathway, Consequently, USP38 may emerge as a promising therapeutic target for managing VAs following HF.

Aucubin alleviates doxorubicin-induced cardiotoxicity through crosstalk between NRF2 and HIPK2 mediating autophagy and apoptosis

BACKGROUND

Doxorubicin (DOX) is widely used for the treatment of a variety of cancers. However, its clinical application is limited by dose-dependent cardiotoxicity. Recent findings demonstrated that autophagy inhibition and apoptosis of cardiomyocytes induced by oxidative stress dominate the pathophysiology of DOX-induced cardiotoxicity (DIC), however, there are no potential molecules targeting on these.

PURPOSE

This study aimed to explore whether aucubin (AU) acting on inimitable crosstalk between NRF2 and HIPK2 mediated the autophagy, oxidative stress, and apoptosis in DIC, and provide a new and alternative strategy for the treatment of DIC.

METHODS AND RESULTS

We first demonstrated the protection of AU on cardiac structure and function in DIC mice manifested by increased EF and FS values, decreased serum CK-MB and LDH contents and well-aligned cardiac tissue in HE staining. Furthermore, AU alleviated DOX-induced myocardial oxidative stress, mitochondrial damage, apoptosis, and autophagy flux dysregulation in mice, as measured by decreased ROS, 8-OHdG, and TUNEL-positive cells in myocardial tissue, increased SOD and decreased MDA in serum, aligned mitochondria with reduced vacuoles, and increased autophagosomes. In vitro, AU alleviated DOX-induced oxidative stress, autophagy inhibition, and apoptosis by promoting NRF2 and HIPK2 expression. We also identified crosstalk between NRF2 and HIPK2 in DIC as documented by overexpression of NRF2 or HIPK2 reversed cellular oxidative stress, autophagy blocking, and apoptosis aggravated by HIPK2 or NRF2 siRNA, respectively. Simultaneously, AU promoted the expression and nuclear localization of NRF2 protein, which was reversed by HIPK2 siRNA, and AU raised the expression of HIPK2 protein as well, which was reversed by NRF2 siRNA. Crucially, AU did not affect the antitumor activity of DOX against MCF-7 and HepG2 cells, which made up for the shortcomings of previous anti-DIC drugs.

CONCLUSION

These collective results innovatively documented that AU regulated the unique crosstalk between NRF2 and HIPK2 to coordinate oxidative stress, autophagy, and apoptosis against DIC without compromising the anti-tumor effect of DOX in vitro.

Reduced expression of transmembrane protein 43 during cardiac hypertrophy leads to worsening heart failure in mice

Transmembrane protein 43 (TMEM43), a member of the transmembrane protein subfamily, was found to be associated with arrhythmogenic right ventricular cardiomyopathy. However, its role in cardiac hypertrophy has not been elucidated. Here, we used a pressure overload-induced cardiac hypertrophy model to explore the role of TMEM43 in heart failure. Mice were subjected to aortic banding (AB) to induce cardiac hypertrophy. The mice were also randomly selected to receive injection of adeno-associated virus 9 (AAV9)-shTMEM43 to knockdown TMEM43 in cardiomyocytes or control AAV9 (ScRNA). Four weeks after AB, the mice were subjected to echocardiography to evaluate cardiac function. Neonatal rat cardiomyocytes (NRCMs) were stimulated with angiotensin II (AngII, 1 μM) and transfected with an adenovirus to over-express TMEM43. We found that TMEM43 was downregulated in mouse hearts and cardiomyocytes poststimulation. Mice with TMEM43 knockdown showed worsening heart failure accompanied by deteriorating cardiac function and exacerbated cardiac hypertrophy and fibrosis at 4 weeks post-AB. NRCMs over-expressing TMEM43 exhibited an ameliorated hypertrophic response. Moreover, we found that TMEM43 deficiency increased nuclear factor kappa B (NF-κB) activation in mouse hearts post-AB, while TMEM43 over-expression reduced NF-κB activation in cardiomyocytes upon AngII stimulation. Thus, we conclude that reduced expression of TMEM43 during cardiac hypertrophy leads to worsening heart failure in mice.

Characteristics, Isolation Methods, and Biological Properties of Aucubin

Aucubin is an iridoid glycoside widely spread in the families Cornaceae, Garryaceae, Orobanchaceae, Globulariaceae, Eucommiaceae, Scrophulariaceae, Plantaginaceae, and Rubiaceae. This review is intended to provide data on the physicochemical characteristics, isolation methods, and biological activities of aucubin and its producing plants. Aucubin is unstable and can be deglycosylated into its aglycone, aucubigenin. Various chromatographic methods (column chromatography, vacuum liquid chromatography, medium pressure liquid chromatography, and high-performance liquid chromatography) have been used together to isolate aucubin, mainly with the stationary phase C-18 and the mobile phase water-methanol solution made in gradients. In vitro and in vivo studies reveal that aucubin has a wide range of activities, including anti-inflammatory, antioxidant, anxiolytic and antidepressant, antidiabetic, antifibrotic, antimicrobial, anticancer, antihyperlipidemic, gastroprotective, cardioprotective, hepatoprotective, retinoprotective, neuroprotective, osteoprotective, and renoprotective. Even though aucubin has been extensively investigated, further research in humans is urgently needed primarily to substantiate the clinical evidence. Moreover, extensive studies on its drug delivery systems will help maximize efficacy and minimize side effects.

Research progress on the protective effects of aucubin in neurological diseases

CONTEXT

Aucubin (AU), an iridoid glycoside that is one of the active constituents of Eucommia ulmoides Oliv. (EUO) (Eucommiaceae), a traditional Chinese medicine, has been extensively studied in the management of neurological diseases (NDs). However, a comprehensive review of its effects and mechanisms in this regard is currently not available.

OBJECTIVE

To compile the protective effects and mechanisms of AU in NDs and provide a basis for further research.

METHODS

We used 'aucubin' as the 'All Fields' or 'MeSH' in PubMed, Web of Science and China National Knowledge Infrastructure without any limitation to search all relevant articles as comprehensively as possible; we selected the articles on AU treatment of NDs for summary.

RESULTS

Studies reviewed herein reported that AU improved the symptoms or prognosis of Parkinson's disease, Alzheimer's disease, intracerebral haemorrhage, diabetic encephalopathy, epilepsy, anxiety and depression, and traumatic brain injury. The pharmacological mechanisms involved in repairing neuronal loss were postulated to include increasing γ-aminobutyric acid (GABA) content in the synapse, promoting differentiation of neural precursor cells into GABAergic neurons, providing antioxidant and anti-neuroinflammation activities, as well as enhancing autophagy and anti-apoptotic actions.

DISCUSSION AND CONCLUSIONS

The protective effects of AU on some NDs have been confirmed. According to the pharmacological effects, AU is also highly likely to have protective effects on other NDs, which can be realized by further in vivo and in vitro basic research, and clinical trials. In the future, AU may be used for clinical prevention or treatment of patients with neurological diseases.

Tax1 banding protein 1 exacerbates heart failure in mice by activating ITCH-P73-BNIP3-mediated cardiomyocyte apoptosis

Tax1 banding protein 1 (Tax1bp1) was originally identified as an NF-κB regulatory protein that participated in inflammatory, antiviral and innate immune processes. Tax1bp1 also functions as an autophagy receptor that plays a role in autophagy. Our previous study shows that Tax1bp1 protects against cardiomyopathy in STZ-induced diabetic mice. In this study we investigated the role of Tax1bp1 in heart failure. Pressure overload-induced heart failure model was established in mice by aortic banding (AB) surgery, and angiotensin II (Ang II)-induced heart failure model was established by infusion of Ang II through osmotic minipump for 4 weeks. We showed that the expression levels of Tax1bp1 in the heart were markedly increased 2 and 4 weeks after AB surgery. Knockdown of Tax1bp1 in mouse hearts significantly ameliorated both AB- and Ang II infusion-induced heart failure parameters. On the contrary, AB-induced heart failure was aggravated in cardiac-specific Tax1bp1 transgenic mice. Similar results were observed in neonatal rat cardiomyocytes (NRCMs) under Ang II insult. We demonstrated that the pro-heart failure effect of Tax1bp1 resulted from its interaction with the E3 ligase ITCH to promote the transcription factor P73 ubiquitination and degradation, causing enhanced BCL2 interacting protein 3 (BNIP3)-mediated cardiomyocyte apoptosis. Knockdown ITCH or BNIP3 in NRCMs significantly reduced Ang II-induced apoptosis in vitro. Similarly, BNIP3 knockdown attenuated heart failure in cardiac-specific Tax1bp1 transgenic mice. In the left ventricles of heart failure patients, Tax1bp1 expression level was significantly increased; Tax1bp1 gene expression was negatively correlated with left ventricular ejection fraction in heart failure patients. Collectively, the Tax1bp1 increase in heart failure enhances ITCH-P73-BNIP3-mediated cardiomyocyte apoptosis and induced cardiac injury. Tax1bp1 may serve as a potent therapeutic target for the treatment of heart failure.• Cardiac Tax1bp1 transgene mice were more vulnerable to cardiac dysfunction under stress.• Cardiac Tax1bp1 transgene mice were more vulnerable to cardiac dysfunction under stress.• Knockout of Tax1bp1 in mouse hearts ameliorated heart failure induced by pressure overload.• Tax1bp1 interacts with the E3 ligase Itch to promote P73 ubiquitination and degradation, causing enhanced BNIP3-mediated apoptosis.• Tax1bp1 may become a target of new therapeutic methods for treating heart failure.

Mechanism of tonifying-kidney Chinese herbal medicine in the treatment of chronic heart failure

According to traditional Chinese medicine (TCM), chronic heart failure has the basic pathological characteristics of “heart-kidney yang deficiency.” Chronic heart failure with heart- and kidney-Yang deficiency has good overlap with New York Heart Association (NYHA) classes III and IV. Traditional Chinese medicine classical prescriptions for the treatment of chronic heart failure often take “warming and tonifying kidney-Yang” as the core, supplemented by herbal compositions with functions of “promoting blood circulation and dispersing blood stasis.” Nowadays, there are still many classical and folk prescriptions for chronic heart failure treatment, such as Zhenwu decoction, Bushen Huoxue decoction, Shenfu decoction, Sini decoction, as well as Qili Qiangxin capsule. This review focuses on classical formulations and their active constituents that play a key role in preventing chronic heart failure by suppressing inflammation and modulating immune and neurohumoral factors. In addition, given that mitochondrial metabolic reprogramming has intimate relation with inflammation, cardiac hypertrophy, and fibrosis, the regulatory role of classical prescriptions and their active components in metabolic reprogramming, including glycolysis and lipid β-oxidation, is also presented. Although the exact mechanism is unknown, the classical TCM prescriptions still have good clinical effects in treating chronic heart failure. This review will provide a modern pharmacological explanation for its mechanism and offer evidence for clinical medication by combining TCM syndrome differentiation with chronic heart failure clinical stages.

Iridoid glycoside Aucubin protects against nonylphenol-induced testicular damage in male rats via modulation of steroidogenic and apoptotic signaling

Aucubin (AU) is one of the widespread compounds belonging to the group of iridoid glycosides, which possesses numerous beneficial properties. Nonylphenol (NP), is a synthetic environmental toxicant that has the potential to cause male infertility through excessive production of reactive oxygen species. In the current study, the remedial potential of Aucubin was assessed against NP-generated testicular damage in male rats. Animals were distributed into four groups and treated for 56 days in this study. Control-group (0.1% DMSO + food), NP group (100 µg/kg), NP + AU group (100 µg/kg + 5 mg/kg) and AU group (5 mg/kg). NP exposure significantly (p < 0.05) reduced the activity of antioxidant enzymes i.e., glutathione reductase, catalase (CAT), superoxide dismutase, glutathione peroxidase (GPx), and total protein content (TPC), whereas the level of reactive oxygen species (ROS) and thiobarbituric acid reactive substances (TBARS) was enhanced substantially (p < 0.05). Treatment with AU substantially (p < 0.05) recovered activities of antioxidant enzymes, TPC, ROS, and TBARS levels. Moreover, decrease in the levels of follicle-stimulating hormone (FSH), luteinizing hormone (LH), plasma testosterone, sperm count, motility, sperm membrane integrity, and the number of spermatocytes of different stages along with the level of steroidogenic enzymes i.e., 17β-hydroxysteroid dehydrogenase (17β-HSD), 3β-hydroxysteroid dehydrogenase (3β-HSD), and B-cell lymphoma 2 (Bcl-2) by NP administration were recovered to control values by AU treatment. However, AU mitigated the sperm abnormalities (head/midpiece/tail), the number of dead sperms, and proapoptotic proteins i.e., Bcl-2 associated X protein (Bax), caspase-9, and caspase-3 that were increased by NP. Besides, AU treatment recovered the NP-induced potential histopathological alterations in the testicular tissues such as the height of epithelium, seminiferous tubules diameter as well as the height of tunica propria. Overall, NP-induced toxicity was effectively recuperated by the AU administration. These results indicate that AU might be considered as a potential protective agent against testicular damage. The observed protection may be due to its antioxidant, anti-apoptotic, anti-inflammatory and androgenic potential.

Aucubin Exerts Anticancer Activity in Breast Cancer and Regulates Intestinal Microbiota

Aucubin, a natural compound isolated from herbal medicine, has been reported to possess multiple beneficial properties. In this study, we aimed to verify the anticancer effect of aucubin on breast cancer and investigate the effect of cancer on the intestinal flora and whether aucubin has a therapeutic effect on intestinal problems caused by cancer. We established the breast cancer model with mouse 4T1 cell line and BALB/c mice. Aucubin was given once a day by gavage for 14 days. The results showed that aucubin suppress the growth of tumor in vivo by inducing tumor cell apoptosis. The tumor suppression rate of aucubin could reach 51.31 ± 4.07%. Organ histopathology was evaluated by tissue staining, which demonstrated that aucubin could alleviate the organ inflammatory damage caused by breast cancer without visible side effects. Moreover, aucubin could increase the expression of colonic tight junction protein occluding and adjust the gut microbiome to normal level according to 16S rDNA high-throughput sequencing. Herein, our results provide evidence for developing aucubin as an alternative and safe therapeutic for breast cancer treatment.

New Progress in the Molecular Regulations and Therapeutic Applications in Cardiac Oxidative Damage Caused by Pressure Overload

Chronic pressure overload is a key risk factor for mortality due to its subsequent development of heart failure, in which the underlying molecular mechanisms remain vastly undetermined. In this review, we updated the latest advancements for investigating the role and relevant mechanisms of oxidative stress involved in the pathogenesis of pressure-overload-induced cardiomyopathy and cardiac dysfunction, focusing on significant biological sources of reactive oxygen species (free radical) production, antioxidant defenses, and their association with the cardiac metabolic remodeling in the stressed heart. We also summarize the newly developed preclinical therapeutic approaches in animal models for pressure-overload-induced myocardial damage. This review aims to enhance the current understanding of the mechanisms of chronic hypertensive heart failure and potentially improve the development of better therapeutic strategies for the associated diseases.

RIP3 Contributes to Cardiac Hypertrophy by Influencing MLKL-Mediated Calcium Influx

Receptor-interacting protein 3(RIP3), a RIP family member, has been reported as a critical regulator of necroptosis and involves in the pathogenesis of various heart diseases. However, its role in the development of myocardial hypertrophy after pressure overload is unclear. We aimed to investigate the roles of RIP3 in pathological cardiac hypertrophy. A rat model of myocardial hypertrophy induced by the aortic banding method was used in this study. Neonatal rat cardiomyocytes (NRCMs) were stimulated with angiotensin II (Ang-II) or phenylephrine (PE) to induce neurohumoral stress. Our results showed that RIP3 level was significantly elevated in the hypertrophic myocardium tissues from patients, rats subjected to AB surgery, and NRCMs treated with Ang-II or PE. After downregulation of RIP3 expression in NRCMs, the phenotypes of myocardial hypertrophy were obviously alleviated. In mechanism, we demonstrated that RIP3 interacts with mixed lineage kinase domain-like protein (MLKL) and promotes its cell membrane localization to increase the influx of calcium within cells, thereby mediating the development of myocardial hypertrophy. More interestingly, we found the blockage of calcium influx by 2-aminoethoxydiphenyl borate, and lanthanum chloride efficiently reverses RIP3-induced cardiac remodeling in NRCMs. Taken together, our findings indicate a key role of the RIP3-MLKL signaling pathway in myocardial hypertrophy, which may be a novel promising treatment strategy for myocardial hypertrophy.

Activation of Nrf2 by Lithospermic Acid Ameliorates Myocardial Ischemia and Reperfusion Injury by Promoting Phosphorylation of AMP-Activated Protein Kinase α (AMPKα)

Background: As a plant-derived polycyclic phenolic carboxylic acid isolated from Salvia miltiorrhiza, lithospermic acid (LA) has been identified as the pharmacological management for neuroprotection and hepatoprotection. However, the role and mechanism of lithospermic acid in the pathological process of myocardial ischemia-reperfusion injury are not fully revealed. Methods: C57BL/6 mice were subjected to myocardial ischemia and reperfusion (MI/R) surgery and pretreated by LA (50 mg/kg, oral gavage) for six consecutive days before operation. The in vitro model of hypoxia reoxygenation (HR) was induced by hypoxia for 24 h and reoxygenation for 6 h in H9C2 cells, which were subsequently administrated with lithospermic acid (100 μM). Nrf2 siRNA and dorsomorphin (DM), an inhibitor of AMPKα, were used to explore the function of AMPKα/Nrf2 in LA-mediated effects. Results: LA pretreatment attenuates infarct area and decreases levels of TnT and CK-MB in plasm following MI/R surgery in mice. Echocardiography and hemodynamics indicate that LA suppresses MI/R-induced cardiac dysfunction. Moreover, LA ameliorates oxidative stress and cardiomyocytes apoptosis following MI/R operation or HR in vivo and in vitro. In terms of mechanism, LA selectively activates eNOS, simultaneously increases nuclear translocation and phosphorylation of Nrf2 and promotes Nrf2/HO-1 pathway in vivo and in vitro, while cardioprotection of LA is abolished by pharmacological inhibitor of AMPK or Nrf2 siRNA in H9C2 cells. Conclusion: LA protects against MI/R-induced cardiac injury by promoting eNOS and Nrf2/HO-1 signaling via phosphorylation of AMPKα.

6-Gingerol protects against cardiac remodeling by inhibiting the p38 mitogen-activated protein kinase pathway

6-Gingerol, a pungent ingredient of ginger, has been reported to possess anti-inflammatory and antioxidant activities, but the effect of 6-gingerol on pressure overload-induced cardiac remodeling remains inconclusive. In this study, we investigated the effect of 6-gingerol on cardiac remodeling in in vivo and in vitro models, and to clarify the underlying mechanisms. C57BL/6 mice were subjected to transverse aortic constriction (TAC), and treated with 6-gingerol (20 mg/kg, ig) three times a week (1 week in advance and continued until the end of the experiment). Four weeks after TAC surgery, the mice were subjected to echocardiography, and then sacrificed to harvest the hearts for analysis. For in vitro study, neonatal rat cardiomyocytes and cardiac fibroblasts were used to validate the protective effects of 6-gingerol in response to phenylephrine (PE) and transforming growth factor-β (TGF-β) challenge. We showed that 6-gingerol administration protected against pressure overload-induced cardiac hypertrophy, fibrosis, inflammation, and dysfunction in TAC mice. In the in vitro study, we showed that treatment with 6-gingerol (20 μM) blocked PE-induced-cardiomyocyte hypertrophy and TGF-β-induced cardiac fibroblast activation. Furthermore, 6-gingerol treatment significantly decreased mitogen-activated protein kinase p38 (p38) phosphorylation in response to pressure overload in vivo and extracellular stimuli in vitro, which was upregulated in the absence of 6-gingerol treatment. Moreover, transfection with mitogen-activated protein kinase kinase 6 expressing adenoviruses (Ad-MKK6), which specifically activated p38, abolished the protective effects of 6-gingerol in both in vitro and in vivo models. In conclusion, 6-gingerol improves cardiac function and alleviates cardiac remodeling induced by pressure overload in a p38-dependent manner. The present study demonstrates that 6-gingerol is a promising agent for the intervention of pathological cardiac remodeling.

Neutrophil Gelatinase-Associated Lipocalin 2 Accelerates Hypoxia-Induced Endothelial Cell Injury via eNOS/NRF2 Signalling

Objective

Neutrophil gelatinase-associated lipocalin (NGAL), a lipocalin, is implicated in many cardiovascular diseases (CVD). The effect of NGAL on endothelial cells (ECs), particularly on ECs injured because of hypoxia, is unclear. In this study, we aim to explore the effect of NGAL in an EC injury in response to hypoxia.

Materials and Methods

In this experimental study, we isolated and cultured mouse heart ECs (MHECs). The EC injury model was established by exposure of the ECs to hypoxia for 24 hours. The ECs were treated with NGAL (30, 60, 120, 250 and 500 ng/ml). Cell inflammation and oxidative stress were detected by corresponding assays. Apoptotic cells were stained by the terminal deoxynucleotidyl transferase dUTP nick end labelling (TUNEL) assay.

Results

NGAL increased the inflammatory response at the baseline level and further augmented the hypoxia-induced inflammation response. Reactive oxygen species (ROS) levels increased upon NGAL treatment, which caused antioxidase/oxidase imbalance. NGAL also exaggerated hypoxia-induced oxidative stress. The cell apoptosis rate also increased in both the NGAL-treated normoxic and hypoxic conditions. NGAL also reduced endothelial nitric oxide synthase (eNOS)-nitric oxide (NO) signalling, thus decreasing the expression and nuclear translocation of nuclear factor erythroid-2-related factor 2 (NRF2), which was confirmed by overexpression of NRF2.

Conclusion

NGAL exaggerates EC injury in both normoxic and hypoxic conditions by inhibiting the eNOS-NRF2 pathway.

Traditional application and modern pharmacological research of Eucommia ulmoides Oliv

As a Traditional Chinese Medicine, Eucommia ulmoides Oliv. has been used for the treatment of various diseases since ancient times, involving lumbar pain, knee pain, osteoporosis, hepatoprotection, paralysis, intestinal haemorrhoids, vaginal bleeding, abortion, spermatorrhoea, foot fungus, anti-aging etc. With the developing discovery of E. ulmoides extracts and its active components in various pharmacological activities, E. ulmoides has gained more and more attention. Up to now, E. ulmoides has been revealed to show remarkable therapeutic effects on hypertension, hyperglycemia, diabetes, obesity, osteoporosis, Parkinson's disease, Alzheimer's disease, sexual dysfunction. E. ulmoides has also been reported to possess antioxidant, anti-inflammatory, neuroprotective, anti-fatigue, anti-aging, anti-cancer and immunoregulation activities etc. Along these lines, this review summarizes the traditional application and modern pharmacological research of E. ulmoides, providing novel insights of E. ulmoides in the treatment of various diseases.

Traditional Chinese medicine as a therapeutic option for cardiac fibrosis: Pharmacology and mechanisms

Cardiovascular diseases are one of the leading causes of death worldwide and cardiac fibrosis is a common pathological process for cardiac remodeling in cardiovascular diseases. Cardiac fibrosis not only accelerates the deterioration progress of diseases but also becomes a pivotal contributor for futile treatment in clinical cardiovascular trials. Although cardiac fibrosis is common and prevalent, effective medicines to provide sufficient clinical intervention for cardiac fibrosis are still unavailable. Traditional Chinese medicine (TCM) is the natural essence experienced boiling, fry, and other processing methods, including active ingredients, extracts, and herbal formulas, which have been applied to treat human diseases for a long history. Recently, research has increasingly focused on the great potential of TCM for the prevention and treatment of cardiac fibrosis. Here, we aim to clarify the identified pro-fibrotic mechanisms and intensively summarize the application of TCM in improving cardiac fibrosis by working on these mechanisms. Through comprehensively analyzing, TCM mainly regulates the following pathways during ameliorating cardiac fibrosis: attenuation of inflammation and oxidative stress, inhibition of cardiac fibroblasts activation, reduction of extracellular matrix accumulation, modulation of the renin-angiotensin-aldosterone system, modulation of autophagy, regulation of metabolic-dependent mechanisms, and targeting microRNAs. We also discussed the deficiencies and the development direction of anti-fibrotic therapies on cardiac fibrosis. The data reviewed here demonstrates that TCM shows a robust effect on alleviating cardiac fibrosis, which provides us a rich source of new drugs or drug candidates. Besides, we also hope this review may give some enlightenment for treating cardiac fibrosis in clinical practice.

Mirabegron Ameliorated Atherosclerosis of ApoE-/- Mice in Chronic Intermittent Hypoxia but Not in Normoxia

PURPOSE

It has been established that obstructive sleep apnea (OSA) is an independent risk factor for atherosclerosis. Chronic intermittent hypoxia (CIH) activates sympathoadrenal system and upregulates β3 adrenergic receptor (β3 AR). However, the effect of selective β3 AR agonist mirabegron in CIH-induced atherosclerosis remains unknown.

METHODS

We generated a CIH-induced atherosclerosis model through exposing ApoE^-/- mice to CIH (8 h per day, cyclic inspiratory oxygen fraction 5-21%, 60-s cycle) for 6 weeks after 4-week high-fat dieting and investigated the effects of mirabegron, a selective β3 AR agonist, on CIH-induced atherosclerosis. The coronary endarterectomy (CE) specimens from coronary artery disease patients with OSA and without OSA were collected.

RESULTS

The expression of β3 AR was significantly elevated in CIH-induced atherosclerosis model. Furthermore, treatment with mirabegron (10mg/kg per day by oral administration for 6 weeks) ameliorated atherosclerosis in ApoE^-/- mice in CIH but not in normoxia. Mechanistically, mirabegron activated β3 AR and ameliorated intraplaque oxidative stress by suppressing p22phox expression and reactive oxygen species (ROS) level. In addition, in human CE specimens, β3 AR was also upregulated associated with increased p22phox expression and ROS level both in the lumen and in the plaque of coronary artery in OSA subjects.

CONCLUSION

This study first demonstrated that mirabegron impeded the progression of CIH-induced atherosclerosis, at least in part, via β3 AR-mediated oxidative stress, suggesting a promising therapeutic strategy for protecting against atherosclerosis induced by CIH.

Pinoresinol diglucoside (PDG) attenuates cardiac hypertrophy via AKT/mTOR/NF-κB signaling in pressure overload-induced rats

ETHNOPHARMACOLOGICAL RELEVANCE

Pinoresinol diglucoside (PDG), the active compound extracted from Eucommia ulmoides, Styrax sp. and Forsythia suspensa, plays the roles in regulating hypertension, inflammation and oxidative stress.

AIMS

Considering that hypertension and inflammation has been proved to contribute to cardiac remodeling, we tested the effects of PDG on cardiac hypertrophy (CM).

METHODS

Male Sprague Dawley (SD) rats were used to construct hypertrophic rats by partial abdominal aortic constriction (AAC)-surgery. PDG solution (2 mg/ml) was used to treat AAC-induced rats by intraperitoneal injection at low dose (L-PDG, 2.5 mg/kg per day), medium dose (M-PDG, 5 mg/kg per day), and high dose (H-PDG, 7.5 mg/kg per day) for 3 weeks post AAC-surgery. CM was evaluated by the ratio of left ventricular weight to body weight ratio (LVW/BW), left ventricular wall thickness by H&E staining, and collagen content deposit by Masson's staining. Further, isoproterenol (ISO) and phenylephrine (PE) were used to produce cellular models of CM in neonatal rat ventricular cardiomyocytes (NRVMs). PDG pre-treated NRVMs 2 h at low dose (L-PDG, 2.5 μg/ml), medium dose (M-PDG, 5 μg/ml), and high dose (H-PDG, 7.5 μg/ml) for 24 h with or without PE- and ISO-stimulation. CM was evaluated by the expressions of hypertrophic biomarkers. Next, the hypertrophic biomarkers and pro-inflammatory cytokines were measured using quantitative real-time PCR (qRT-PCR), the expressions of protein kinase B (AKT)/mammalian target of rapamycin (mTOR)/transcription factor nuclear factor-kappa B (NF-kB) signaling pathway were determined by Western blotting.

RESULTS

PDG treatment prevented cardiac histomorphology damages, decreased upregulations of hypertrophic biomarkers, and prevented fibrosis and inflammation after pressure overload resulting from AAC-surgery. Consistently, PDG remarkably inhibited the changes of cardiomyocyte hypertrophic biomarkers and inflammatory responses in cellular models of CM. Interestingly, PDG administration inhibited the activation of AKT/mTOR/NF-kB signaling pathway both in vivo and in vitro.

CONCLUSIONS

PDG prevents AAC-induced CM in vivo, PE- and ISO-induced CM in vitro. The AKT/mTOR/NF-kB signaling pathway could be the potential therapeutic target involved in the protection of PDG. These findings provide novel evidence that PDG might be a promising therapeutic strategy for CM.

FBXW5 acts as a negative regulator of pathological cardiac hypertrophy by decreasing the TAK1 signaling to pro-hypertrophic members of the MAPK signaling pathway

Pathological cardiac hypertrophy is a crucial cause of cardiac morbidity and mortality worldwide. However, the molecular mechanisms of this disease remain incompletely understood. As a member of E3 ubiquitin ligases, F-box/WD repeat-containing protein 5 (FBXW5) has been implicated in various pathophysiological processes. However, the role of FBXW5 in pathological cardiac hypertrophy remains largely unknown. In this study, decreased expression of FBXW5 was observed in both neonatal rat cardiomyocytes and mouse hearts with hypertrophic remodeling. Gain- and loss-of-function experiments were performed to study the potential function of FBXW5 in pathological cardiac hypertrophy. The in vitro results showed that FBXW5 had a protective effect against cardiac hypertrophy induced by phenylephrine (PE). FBXW5 knockout mice and mice with AAV9-mediated FBXW5 overexpression were generated. Consistent with the in vitro results, FBXW5 deficiency aggravated cardiac hypertrophy induced by pressure overload. FBXW5 overexpression protected mice from hypertrophic stimuli. Remarkably, FBXW5 ameliorated pathological cardiac hypertrophy by directly interacting with the protein transforming growth factor-beta-activated kinase 1 (TAK1) and blocking the mitogen-activated protein kinase (MAPK) signaling pathway. Furthermore, inhibition of TAK1 prevented the effects of FBXW5 on agonist- or pressure overload-induced cardiac hypertrophy. These findings imply that FBXW5 is an essential negative regulator and may be a potential therapeutic target for pathological cardiac hypertrophy.

The pro-migration and anti-apoptosis effects of HMGA2 in HUVECs stimulated by hypoxia

High-mobility group AT-hook2 (HMGA2), serving as an architectural transcription factor, participates in plenty of biological processes. Our study is aimed at illustrating the effect of HMGA2 on hypoxia-induced HUVEC injury and the underlying mechanism. To induce hypoxia-related cell injury, HUVECs were exposed to hypoxic condition for 12-24 h. Molecular expression was determined by Western blot analysis, real-time PCR and immunofluorescence staining. Cell migration was monitored by wound healing assay and Transwell chamber assay. Cell proliferation and apoptosis were measured by MTT assay kits and TUNEL staining. In this study, we discovered that HMGA2 was upregulated in hypoxia-induced HUVECs. Overexpression of HMGA2 promoted cell migration, decreased the apoptosis ratio in response to hypoxia stimulation, while HMGA2 knockdown inhibited cell migration and accelerated apoptosis in HUVECs under hypoxic condition. Mechanistically, we found that HMGA2 induced increased expression of HIF-1α,VEGF, eNOS and AKT. eNOS knockdown significantly reduced HMGA2-mediated pro-migration effects, and AKT knockdown strikingly counteracted HMGA2-mediated anti-apoptotic effect. Hence, our data indicated that HMGA2 promoted cell migration by regulating HIF-1α/VGEF/eNOS signaling and prevented cell apoptosis by activating HIF-1α/VGEF/AKT signaling in HUVECs.

Nucleotide-Binding Oligomerization Domain-Like Receptor 3 Deficiency Attenuated Isoproterenol-Induced Cardiac Fibrosis via Reactive Oxygen Species/High Mobility Group Box 1 Protein Axis

Nucleotide-binding oligomerization domain-like receptor 3 (NLRP3) is involved in fibrosis of multiple organs, such as kidney, liver, lung, and the like. However, the role of NLRP3 in cardiac fibrosis is still controversial and remains unclear. The study aims to investigate the role of NLRP3 on cardiac fibrosis induced by isoproterenol (ISO). In vivo, NLRP3 knockout and wild-type mice were subcutaneously injected with ISO to induce the cardiac fibrosis model. The results showed that NLRP3 deficiency alleviated the cardiac fibrosis and inflammation induced by ISO. In vitro, neonatal rat ventricular myocytes (NRVMs) and primary adult mouse cardiac fibroblasts of NLRP3 knockout and wild-type mice were isolated and challenged with ISO. Adenovirus (Ad-) NLRP3 and small interfering RNAs targeting NLRP3 were used to transfect NRVMs to overexpress or knockdown NLRP3. We found that NLRP3 could regulate high-mobility group box 1 protein (HMGB1) secretion via reactive oxygen species production in NRVMs and the HMGB1 secreted by NRVMs promoted the activation and proliferation of cardiac fibroblasts. Thus, we concluded that the NLRP3/reactive oxygen species/HMGB1 pathway could be the underlying mechanism of ISO-induced cardiac fibrosis.

The 5-Lipoxygenase Inhibitor Zileuton Protects Pressure Overload-Induced Cardiac Remodeling via Activating PPARα

Zileuton has been demonstrated to be an anti-inflammatory agent due to its well-known ability to inhibit 5-lipoxygenase (5-LOX). However, the effects of zileuton on cardiac remodeling are unclear. In this study, the effects of zileuton on pressure overload-induced cardiac remodeling were investigated and the possible mechanisms were examined. Aortic banding was performed on mice to induce a cardiac remodeling model, and the mice were then treated with zileuton 1 week after surgery. We also stimulated neonatal rat cardiomyocytes with phenylephrine (PE) and then treated them with zileuton. Our data indicated that zileuton protected mice from pressure overload-induced cardiac hypertrophy, fibrosis, and oxidative stress. Zileuton also attenuated PE-induced cardiomyocyte hypertrophy in a time- and dose-dependent manner. Mechanistically, we found that zileuton activated PPARα, but not PPARγ or PPARθ, thus inducing Keap and NRF2 activation. This was confirmed with the PPARα inhibitor GW7647 and NRF2 siRNA, which abolished the protective effects of zileuton on cardiomyocytes. Moreover, PPARα knockdown abolished the anticardiac remodeling effects of zileuton in vivo. Taken together, our data indicate that zileuton protects against pressure overload-induced cardiac remodeling by activating PPARα/NRF2 signaling.

Galangin ameliorates cardiac remodeling via the MEK1/2-ERK1/2 and PI3K-AKT pathways

Cardiac remodeling is associated with inflammation and apoptosis. Galangin, as a natural flavonol, has the potent function of regulating inflammation and apoptosis, which are factors related to cardiac remodeling. Beginning 3 days after aortic banding (AB) or Sham surgery, mice were treated with galangin for 4 weeks. Cardiac remodeling was assessed according to echocardiographic parameters, histological analyses, and hypertrophy and fibrosis markers. Our results showed that galangin administration attenuated cardiac hypertrophy, dysfunction, and fibrosis response in AB mice and angiotensin II-treated H9c2 cells. The inhibitory action of galangin in cardiac remodeling was mediated by MEK1/2-extracellular-regulated protein kinases 1/2 (ERK1/2)-GATA4 and phosphoinositide 3-kinase (PI3K)-protein kinase B (AKT)-glycogen synthase kinase 3β (GSK3β) activation. Furthermore, we found that galangin inhibited inflammatory response and apoptosis. Our findings suggest that galangin protects against cardiac remodeling through decreasing inflammatory responses and apoptosis, which are associated with inhibition of the MEK1/2-ERK1/2-GATA4 and PI3K-AKT-GSK3β signals.

Indigo Fruits Ingredient, Aucubin, Protects against LPS-Induced Cardiac Dysfunction in Mice

Aucubin (AUB), which is extracted from Eucommia ulmoides Oliver seeds, has been found to possess anti-inflammatory and antiapoptotic properties. Recent studies have indicated that inflammation, oxidative stress, and apoptosis are involved in the pathophysiology of lipopolysaccharide (LPS)-induced cardiac dysfunction. Our study aimed to investigate the effect of AUB on LPS-induced acute cardiac injury. Male C57BL/6 mice were injected with LPS (one 6 mg/kg injection) to induce cardiac dysfunction without or with AUB pretreatment (20 or 80 mg/kg per day) for 1 week. We found that AUB ameliorated cardiac dysfunction, inflammation, oxidative stress, and apoptosis induced by LPS stimulation. Mechanistically, AUB inhibited LPS-induced oxidative stress by decreasing reactive oxygen species and thioredoxin interaction protein (TXNIP) levels. Moreover, AUB suppressed LPS-induced inflammation and apoptosis by reducing nucleotide-binding oligomerization domain-like receptor family pyrin domain-containing 3 (NLRP3)/apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC)/caspase-1 inflammasome formation. Overexpression of NLRP3 in cardiomyocytes attenuated the protective effects of AUB. Interestingly, NLRP3 deficiency ameliorated cardiac function and reduced the inflammatory response and oxidative stress after LPS insult in mice, whereas AUB could not further prevent LPS-induced cardiac dysfunction in NLRP3-deficient mice. In summary, AUB exerts a protective effect against LPS-induced inflammation, oxidative stress, and apoptosis in vivo and in vitro by regulating the TXNIP pathway and inactivating the NLRP3/ASC/caspase-1 inflammasome. Hence, AUB may be a promising agent against LPS-induced cardiac dysfunction. SIGNIFICANCE STATEMENT: Aucubin exerts a protective effect against lipopolysaccharide-induced cardiac dysfunction by regulating nucleotide-binding oligomerization domain-like receptor family pyrin domain-containing 3 inflammasome.

Regulatory Mechanisms of the NLRP3 Inflammasome, a Novel Immune-Inflammatory Marker in Cardiovascular Diseases

The nod-like receptor family pyrin domain containing 3 (NLRP3) is currently the most widely studied inflammasome and has become a hot topic of recent research. As a macromolecular complex, the NLRP3 inflammasome is activated to produce downstream factors, including caspase-1, IL-1β, and IL-18, which then promote local inflammatory responses and induce pyroptosis, leading to unfavorable effects. A growing number of studies have examined the relationship between the NLRP3 inflammasome and cardiovascular diseases (CVDs). However, some studies have shown that the NLRP3 inflammasome is not involved in the occurrence of certain diseases. Therefore, identifying the mechanism of action of the NLRP3 inflammasome and its potential involvement in the pathological process of disease progression is of utmost importance. This review discusses the mechanisms of NLRP3 inflammasome activation and the relationship between the inflammasome and CVDs, including coronary atherosclerosis, myocardial ischemia/reperfusion, cardiomyopathies, and arrhythmia, as well as CVD-related treatments.

Cordycepin ameliorates cardiac hypertrophy via activating the AMPKα pathway

Increase of myocardial oxidative stress is closely related to the occurrence and development of cardiac hypertrophy. Cordycepin, also known as 3'-deoxyadenosine, is a natural bioactive substance extracted from Cordyceps militaris (which is widely cultivated for commercial use in functional foods and medicine). Since cordycepin suppresses oxidative stress both in vitro and in vivo, we hypothesized that cordycepin would inhibit cardiac hypertrophy by blocking oxidative stress-dependent related signalling. In our study, a mouse model of cardiac hypertrophy was induced by aortic banding (AB) surgery. Mice were intraperitoneally injected with cordycepin (20 mg/kg/d) or the same volume of vehicle 3 days after-surgery for 4 weeks. Our data demonstrated that cordycepin prevented cardiac hypertrophy induced by AB, as assessed by haemodynamic parameters analysis and echocardiographic, histological and molecular analyses. Oxidative stress was estimated by detecting superoxide generation, superoxide dismutase (SOD) activity and malondialdehyde levels, and by detecting the protein levels of gp91^phox and SOD. Mechanistically, we found that cordycepin activated activated protein kinase α (AMPKα) signalling and attenuated oxidative stress both in vivo in cordycepin-treated mice and in vitro in cordycepin treated cardiomyocytes. Taken together, the results suggest that cordycepin protects against post-AB cardiac hypertrophy through activation of the AMPKα pathway, which subsequently attenuates oxidative stress.

STING-IRF3 contributes to lipopolysaccharide-induced cardiac dysfunction, inflammation, apoptosis and pyroptosis by activating NLRP3

Mountainous evidence suggests that inflammation, cardiomyocyte apoptosis and pyroptosis are involved in the development of sepsis and sepsis-induced cardiomyopathy (SIC). Stimulator of interferon genes (STING) is an indispensable molecule that could regulate inflammation and immune response in multiple diseases. However, the role of STING in cardiovascular disease, especially SIC remains unclear. This study was designed to investigate the potential molecular mechanisms of STING in lipopolysaccharide (LPS)-induced cardiac injury using STING global knockout mice. In wild type mice and cardiomyocytes, LPS stimulation triggered the perinuclear translocation of STING, which further bound to Type-I interferons (IFN) regulatory factor 3 (IRF3) and phosphorylated IRF3. Phosphorylated (P-) IRF3 subsequently translocated into nucleus and increased the expression of NOD-like receptor protein 3 (NLRP3). Knockout of STING in mice significantly improved survival rate and cardiac function, apart from suppressing myocardial and serum inflammatory cytokines, apoptosis, as well as cardiomyocyte pyroptosis. In vitro experiments revealed that NLRP3 overexpression by adenovirus could offset protective effects of STING knockdown in LPS-induced cardiomyocytes. Additionally, LPS stimulation also promoted the production of intracellular reactive oxygen (ROS), which further induced the NLRP3 translocation to the cytoplasm from the nucleus. Dissociative TXNIP could directly interact with cytoplasmic NLRP3 and form inflammasome, eventually triggering cardiomyocyte injury. Collectively, our findings disclose that STING deficiency could alleviate LPS-induced SIC in mice. Hence, targeting STING in cardiomyocytes may be a promising therapeutic strategy for preventing SIC.

Oridonin protects against cardiac hypertrophy by promoting P21-related autophagy

Autophagy is an endogenous protective process; the loss of autophagy could destabilize proteostasis and elevate intracellular oxidative stress, which is critically involved in the development of cardiac hypertrophy and heart failure. Oridonin, a natural tetracycline diterpenoid from the Chinese herb Rabdosia, has autophagy activation properties. In this study, we tested whether oridonin protects against cardiac hypertrophy in mice and cardiomyocytes. We implemented aortic banding to induce a cardiac hypertrophy mouse model, and oridonin was given by gavage for 4 weeks. Neonatal rat cardiomyocytes were stimulated with angiotensin II to simulate neurohumoural stress. Both in vivo and in vitro studies suggested that oridonin treatment mitigated pressure overload-induced cardiac hypertrophy and fibrosis, and also preserved heart function. Mice that received oridonin exhibited increased antioxidase activities and suppressed oxidative injury compared with the aortic banding group. Moreover, oridonin enhanced myocardial autophagy in pressure-overloaded hearts and angiotensin II-stimulated cardiomyocytes. Mechanistically, we discovered that oridonin administration regulated myocardial P21, and cytoplasmic P21 activated autophagy via regulating Akt and AMPK phosphorylation. These findings were further corroborated in a P21 knockout mouse model. Collectively, pressure overload-induced autophagy dysfunction causes intracellular protein accumulation, resulting in ROS injury while aggravating cardiac hypertrophy. Thus, our data show that oridonin promoted P21-related autophagic lysosomal degradation, hence attenuating oxidative injury and cardiac hypertrophy.

Saikosaponin A Protects From Pressure Overload-Induced Cardiac Fibrosis via Inhibiting Fibroblast Activation or Endothelial Cell EndMT

Saikosaponin A (SSA) is a triterpenoid saponin with many pharmacological activities, including anti-inflammatory and antioxidant effects. The effect of SSA on cardiac remodeling and fibrosis, however, remains unclear. Aortic banding surgery was used to establish a mouse cardiac remodeling and fibrosis model. Mice were subjected to an intraperitoneal (i.p.) injection of SSA (5 mg/kg/d or 40 mg/kg/d) 2 weeks after surgery for 28 days. As a result, SSA had limited effect on cardiac hypertrophy but decreased cardiac fibrosis remarkably. Neonatal rat cardiomyocytes were isolated and cultured with SSA (1 and 30 μM). Both 1 and 30 μM SSA reduced atrial natriuretic peptide transcription induced by angiotensin II. Adult mouse cardiac fibroblasts were isolated and cultured with SSA (1, 3, 10 and 30 μM). Only 10 and 30 μM SSA ameliorated transforming growth factor β (TGFβ)-induced fibroblast activation and function. Mouse heart endothelial cells were isolated and stimulated with TGFβ and cocultured with SSA (1, 3, 10 and 30 μM). Only 1 and 3 μM SSA ameliorated TGFβ-induced endothelium-mesenchymal transition (EndMT). Consistently, only the 5 mg/kg/d treatment relieved pressure overload-induced EndMT in vivo. Furthermore, we found that high dosages of SSA (10 and 30 μM) inhibited the TGFβ/smad pathway in fibroblasts, while low dosages of SSA (1 and 3 μM) inhibited the Wnt/β-catenin pathway in endothelial cells. The Smad pathway activator SRI-011381 eliminated SSA (30 μM)-induced protective effects on fibroblasts. The Wnt pathway activator WAY-262611 eliminated SSA (1 μM)-induced protective effects on endothelial cells. In summary, this study indicates the potential application of SSA in the treatment of myocardial fibrosis in cardiac fibrosis, with different target effects associated with different dosages.

Enrichment and Purification of Aucubin from Eucommia ulmoides Ionic Liquid Extract Using Macroporous Resins

Aiming to address the shortcomings of high-concentration ethanol or methanol extraction solutions that need to be diluted and concentrated prior to use in conventional macroporous resin adsorption approaches, an efficient approach for enrichment and purification of aucubin from the ionic liquid extraction solution of samaras of Eucommia ulmoides was proposed. Among the nine kinds of macroporous resins investigated, the HPD850 resin was found to be the most suitable. Equilibrium adsorption tests were investigated and found to be better fitted by the Langmuir isotherm model. After the dynamic tests on a column packed with HPD850, the optimum operational conditions were as follows: for the absorption process, an initial aucubin concentration of 9.87 mg/L, a sample volume of 13 bed volumes (BV), and a flow rate of 2 BV/h; for the water washing process, 5 BV of deionized water and a flow rate of 3 BV/h; for the ethanol desorption process, a 10–80% ethanol volume fraction as the eluent, 2 BV for each ethanol volume fraction, and a flow rate of 3 BV/h. The 40–80% ethanol volume fraction eluent was collected and concentrated to produce the final products, resulting in an aucubin purity and recovery of 79.41% and 72.92%, respectively.

NLRP3 deficiency accelerates pressure overload-induced cardiac remodeling via increased TLR4 expression

NLRP3, a member of the nucleotide-binding oligomerization domain (NOD)-like receptor family, is involved in cardiac inflammation. However, the functional role of NLRP3 in cardiac remodeling is not clear. To investigate the roles of NLRP3 in pressure overload-induced cardiac remodeling, NLRP3 knockout and wild-type mice were subjected to aortic banding to induce cardiac remodeling. The data showed that NLRP3 expression was downregulated in the remodeling process. NLRP3 deficiency accelerated cardiac hypertrophy, fibrosis, and inflammation responses with deteriorating cardiac dysfunction in the pressure overload-induced cardiac remodeling mouse model. Neonatal rat cardiomyocytes were isolated and stimulated with phenylephrine (PE). We identified NLRP3 as a negative regulator of cardiomyocyte remodeling in PE-stimulated cardiomyocyte remodeling using adenovirus-NLRP3 and NLRP3 siRNA. Mechanistically, we found that the expression of Toll-like receptor (TLR) 4 was upregulated in NLRP3-deficient mouse hearts and PE-stimulated cardiomyocytes. NLRP3 knockout mice subjected to a TLR4 inhibitor revealed a relieved cardiac remodeling response with improved cardiac dysfunction. Our data suggested that NLRP3 could be a therapeutic target for cardiac remodeling and heart failure. KEY MESSAGES: NLRP3 expression was downregulated in the remodeling process. NLRP3 deficiency accelerated pressure overload-induced cardiac remodeling. NLRP3 acted as a negative regulator of cardiomyocyte remodeling via downregulating TLR4.

Aucubin protects against pressure overload-induced cardiac remodelling via the β3 -adrenoceptor-neuronal NOS cascades

BACKGROUND AND PURPOSE

Aucubin, the predominant component of Eucommia ulmoides Oliv., has been shown to have profound effects on oxidative stress. As oxidative stress has previously been demonstrated to contribute to acute and chronic myocardial injury, we tested the effects of aucubin on cardiac remodelling and heart failure.

EXPERIMENTAL APPROACH

Initially, H9c2 cardiomyocytes and neonatal rat cardiomyocytes pretreated with aucubin (1, 3, 10, 25 and 50 μM) were challenged with phenylephrine. Secondly, the transverse aorta was constricted in C57/B6 and neuronal NOS (nNOS)-knockout mice, then aucubin (1 or 5 mg·kg^-1 body weight day^-1 ) was injected i.p. for 25 days. Hypertrophy was evaluated by assessing morphological changes, echocardiographic parameters, histological analyses and hypertrophic markers. Oxidative stress was evaluated by examining ROS generation, oxidase activity and NO generation. NOS expression was determined by Western blotting.

KEY RESULTS

Aucubin effectively suppressed cardiac remodelling; in mice, aucubin substantially inhibited pressure overload-induced cardiac hypertrophy, fibrosis and inflammation, whereas knocking out nNOS abolished these cardioprotective effects of aucubin. Blocking or knocking down the β₃ -adrenoceptor abolished the protective effects of aucubin in vitro. Furthermore, aucubin enhanced the protective effects of a β₃ -adrenoceptor agonist in vitro by increasing cellular cAMP levels, whereas treatment with an adenylate cyclase (AC) inhibitor abolished the cardioprotective effects of aucubin.

CONCLUSIONS AND IMPLICATIONS

Aucubin suppresses oxidative stress during cardiac remodelling by increasing the expression of nNOS in a process that requires activation of the β₃ -adrenoceptor/AC/cAMP pathway. These findings suggest that aucubin could have potential as a treatment for cardiac remodelling and heart failure.