Novel mechanism of cardiac protection by valsartan: synergetic roles of TGF-β1 and HIF-1α in Ang II-mediated fibrosis after myocardial infarction

Preclinical Investigations on Anti-fibrotic Potential of Long-Term Oral Therapy of Sodium Astragalosidate in Animal Models of Cardiac and Renal Fibrosis

In traditional Chinese medicine, Radix Astragali has played a vital role in treating progressive fibrotic diseases. One of its main active components, astragaloside IV, is a promising anti-fibrotic treatment despite its extremely low bioavailability. Our study aimed to optimize sodium astragalosidate (SA) by salt formation to improve solubility and oral absorption for anti-fibrotic therapy in vivo. Isoproterenol-induced myocardial fibrosis rat models and obese BKS-db mice presenting diabetic kidney fibrosis were used in this study. Daily oral administration of SA (20 mg/kg) for 14 days ameliorated cardiac fibrosis by reducing collagen accumulation and fibrosis-related inflammatory signals, including TNF-α, IL-1β, and IL-6. In db/db mice, SA (5,10, and 20 mg/kg per day for 8 weeks) dose-dependently alleviated lipid metabolism impairment and renal dysfunction when administered orally. Furthermore, Western blot and immunohistochemistry analyses demonstrated that SA treatment inhibited renal fibrosis by suppressing TGF-β1/Smads signaling. Taken together, our findings provide the oral-route medication availability of SA, which thus might offer a novel lead compound in preclinical trial-enabling studies for developing a long-term therapy to treat and prevent fibrosis.

Hypoxia-inducible factor-1: Regulatory mechanisms and drug therapy in myocardial infarction

Myocardial infarction (MI), an acute cardiovascular disease characterized by coronary artery blockage, inadequate blood supply, and subsequent ischemic necrosis of the myocardium, is one of the leading causes of death. The cellular, physiological, and pathological responses following MI are complex, involving multiple intertwined pathological mechanisms. Hypoxia-inducible factor-1 (HIF-1), a crucial regulator of hypoxia, plays a significant role in of the development of MI by modulating the behavior of various cells such as cardiomyocytes, endothelial cells, macrophages, and fibroblasts under hypoxic conditions. HIF-1 regulates various post-MI adaptive reactions to acute ischemia and hypoxia through various mechanisms. These mechanisms include angiogenesis, energy metabolism, oxidative stress, inflammatory response, and ventricular remodeling. With its crucial role in MI, HIF-1 is expected to significantly influence the treatment of MI. However, the drugs available for the treatment of MI targeting HIF-1 are currently limited, and most contain natural compounds. The development of precision-targeted drugs modulating HIF-1 has therapeutic potential for advancing MI treatment research and development. This study aimed to summarize the regulatory role of HIF-1 in the pathological responses of various cells following MI, the diverse mechanisms of action of HIF-1 in MI, and the potential drugs targeting HIF-1 for treating MI, thus providing the theoretical foundations for potential clinical therapeutic targets.

HIF-2α Controls Expression and Intracellular Trafficking of the α2-Subunit of Na,K-ATPase in Hypoxic H9c2 Cardiomyocytes

The Na,K-ATPase (NKA) pump plays essential roles for optimal function of the heart. NKA activity decreases in necropsy materials from ischemic heart disease, heart failure and in experimental models. Cellular adaptation to hypoxia is regulated by hypoxia-induced transcription factors (HIF); we tested whether HIFs are involved in regulating the expression and intracellular dynamics of the α2-isoform of NKA (α2-NKA). HIF-1α and HIF-2α expression was suppressed in H9c2 cardiomyocytes by adenoviral infection, where cells were kept in 1% O2 for 24 h. The silencing efficiency of HIFs was tested on the mRNA and protein expression. We measured the mRNA expression of α2-NKA in HIF-silenced and hypoxia-exposed cells. The membrane and intracellular expression of α2-NKA was measured after labelling the cell surface with NHS-SS-biotin, immunoprecipitation and Western blotting. Hypoxia increased the mRNA expression of α2-NKA 5-fold compared to normoxic cells in an HIF-2α-sensitive manner. The plasma membrane expression of α2-NKA increased in hypoxia by 2-fold and was fully prevented by HIF-2α silencing. Intracellular expression of α2-NKA was not affected. These results showed for the first time that in hypoxic cardiomyocytes α2-NKA is transcriptionally and translationally regulated by HIF-2α. The molecular mechanism behind this regulation needs further investigation.

Hypoxia and HIF-1α Regulate the Activity and Expression of Na,K-ATPase Subunits in H9c2 Cardiomyoblasts

The optimal function of the Na,K-ATPase (NKA) pump is essential for the heart. In ischemic heart disease, NKA activity decreases due to the decreased expression of the pump subunits. Here, we tested whether the hypoxia-inducible transcription factor (HIF-1α), the key signaling molecule regulating the adaptation of cells to hypoxia, is involved in controlling the expression and cellular dynamics of α1- and β1-NKA isoforms and of NKA activity in in-vitro hypoxic H9c2 cardiomyoblasts. HIF-1α was silenced through adenoviral infection, and cells were kept in normoxia (19% O2) or hypoxia (1% O2) for 24 h. We investigated the mRNA and protein expression of α1-, β1-NKA using RT-qPCR and Western blot in whole-cell lysates, cell membranes, and cytoplasmic fractions after labeling the cell surface with NHS-SS-biotin and immunoprecipitation. NKA activity and intracellular ATP levels were also measured. We found that in hypoxia, silencing HIF-1α prevented the decreased mRNA expression of α1-NKA but not of β1-NKA. Hypoxia decreased the plasma membrane expression of α1-NKA and β1- NKA compared to normoxic cells. In hypoxic cells, HIF-1α silencing prevented this effect by inhibiting the internalization of α1-NKA. Total protein expression was not affected. The decreased activity of NKA in hypoxic cells was fully prevented by silencing HIF-1α independent of cellular ATP levels. This study is the first to show that in hypoxic H9c2 cardiomyoblasts, HIF-1α controls the internalization and membrane insertion of α1-NKA subunit and of NKA activity. The mechanism behind this regulation needs further investigation.

The beneficial effects of mesenchymal stem cells and their exosomes on myocardial infarction and critical considerations for enhancing their efficacy

Mesenchymal stem cells (MSCs) are multipotent stromal cells with regenerative, anti-inflammatory, and immunomodulatory properties. MSCs and their exosomes significantly improved structural and functional alterations after myocardial infarction (MI) in preclinical studies and clinical trials. By reprograming intracellular signaling pathways, MSCs attenuate inflammatory response, oxidative stress, apoptosis, pyroptosis, and endoplasmic reticulum (ER) stress and improve angiogenesis, mitochondrial biogenesis, and myocardial remodeling after MI. MSC-derived exosomes contain a mixture of non-coding RNAs, growth factors, anti-inflammatory mediators, and anti-fibrotic factors. Although primary results from clinical trials were promising, greater efficacies can be achieved by controlling several modifiable factors. The optimum timing of transplantation, route of administration, origin of MSCs, number of doses, and number of cells per dose need to be further investigated by future studies. Newly, highly effective MSC delivery systems have been developed to improve the efficacy of MSCs and their exosomes. Moreover, MSCs can be more efficacious after being pretreated with non-coding RNAs, growth factors, anti-inflammatory or inflammatory mediators, and hypoxia. Similarly, viral vector-mediated overexpression of particular genes can augment the protective effects of MSCs on MI. Therefore, future clinical trials must consider these advances in preclinical studies to properly reflect the efficacy of MSCs or their exosomes for MI.

Hypoxic Stress-Dependent Regulation of Na,K-ATPase in Ischemic Heart Disease

In cardiomyocytes, regular activity of the Na,K-ATPase (NKA) and its Na/K pump activity is essential for maintaining ion gradients, excitability, propagation of action potentials, electro-mechanical coupling, trans-membrane Na⁺ and Ca²⁺ gradients and, thus, contractility. The activity of NKA is impaired in ischemic heart disease and heart failure, which has been attributed to decreased expression of the NKA subunits. Decreased NKA activity leads to intracellular Na⁺ and Ca²⁺ overload, diastolic dysfunction and arrhythmias. One signal likely related to these events is hypoxia, where hypoxia-inducible factors (HIF) play a critical role in the adaptation of cells to low oxygen tension. HIF activity increases in ischemic heart, hypertension, heart failure and cardiac fibrosis; thus, it might contribute to the impaired function of NKA. This review will mainly focus on the regulation of NKA in ischemic heart disease in the context of stressed myocardium and the hypoxia-HIF axis and argue on possible consequences of treatment.

Molecular basis and clinical implications of HIFs in cardiovascular diseases

Oxygen maintains the homeostasis of an organism in a delicate balance in different tissues and organs. Under hypoxic conditions, hypoxia-inducible factors (HIFs) are specific and dominant factors in the spatiotemporal regulation of oxygen homeostasis. As the most basic functional unit of the heart at the cellular level, the cardiomyocyte relies on oxygen and nutrients delivered by the microvasculature to keep the heart functioning properly. Under hypoxic stress, HIFs are involved in acute and chronic myocardial pathology because of their spatiotemporal specificity, thus granting them therapeutic potential. Most adult animals lack the ability to regenerate their myocardium entirely following injury, and complete regeneration has long been a goal of clinical treatment for heart failure. The precise manipulation of HIFs (considering their dynamic balance and transformation) and the development of HIF-targeted drugs is therefore an extremely attractive cardioprotective therapy for protecting against myocardial ischemic and hypoxic injury, avoiding myocardial remodeling and heart failure, and promoting recovery of cardiac function.

Downregulation of lncRNA Miat contributes to the protective effect of electroacupuncture against myocardial fibrosis

Background

Myocardial fibrosis changes the structure of myocardium, leads to cardiac dysfunction and induces arrhythmia and cardiac ischemia, threatening patients’ lives. Electroacupuncture at PC6 (Neiguan) was previously found to inhibit myocardial fibrosis. Long non-coding RNAs (lncRNAs) play a variety of regulatory functions in myocardial fibrosis, but whether electroacupuncture can inhibit myocardial fibrosis by regulating lncRNA has rarely been reported.

Methods

In this study, we constructed myocardial fibrosis rat models using isoproterenol (ISO) and treated rats with electroacupuncture at PC6 point and non-point as control. Hematoxylin–eosin, Masson and Sirius Red staining were performed to assess the pathological changes and collagen deposition. The expression of fibrosis-related markers in rat myocardial tissue were detected by RT-qPCR and Western blot. Miat, an important long non-coding RNA, was selected to study the regulation of myocardial fibrosis by electroacupuncture at the transcriptional and post-transcriptional levels. In post-transcriptional level, we explored the myocardial fibrosis regulation effect of Miat on the sponge effect of miR-133a-3p. At the transcriptional level, we studied the formation of heterodimer PPARG–RXRA complex and promotion of the TGF-β1 transcription.

Results

Miat was overexpressed by ISO injection in rats. We found that Miat can play a dual regulatory role in myocardial fibrosis. Miat can sponge miR-133a-3p in an Ago2-dependent manner, reduce the binding of miR-133a-3p target to the 3ʹUTR region of CTGF mRNA and improve the protein expression level of CTGF. In addition, it can also directly bind with PPARG protein, inhibit the formation of heterodimer PPARG–RXRA complex and then promote the transcription of TGF-β1. Electroacupuncture at PC6 point, but not at non-points, can reduce the expression of Miat, thus inhibiting the expression of CTGF and TGF-β1 and inhibiting myocardial fibrosis.

Conclusion

We revealed that electroacupuncture at PC6 point can inhibit the process of myocardial fibrosis by reducing the expression of lncRNA Miat, which is a potential therapeutic method for myocardial fibrosis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13020-022-00615-6.

At the Intersection of Cardiology and Oncology: TGFβ as a Clinically Translatable Therapy for TNBC Treatment and as a Major Regulator of Post-Chemotherapy Cardiomyopathy

Simple Summary

Specific/targeted therapies have been shown to be effective in the treatment of certain cancers. Unfortunately, there is currently no targeted therapy for the treatment of triple-negative breast cancer (TNBC), which is why this subtype of breast cancer is associated with poor patient prognosis. While there is an immense focus on the development of new therapies, the issue of cardiotoxicity following chemotherapeutic treatment is commonly overlooked, despite its role as a leading cause of mortality in cancer survivors. This review aims to discuss the connection of TGF-β signaling and its role in modulating cardiac fibrosis and remodeling, as well as its role in TNBC tumor progression, cancer stem cell enrichment, chemoresistance and relapse. Together, we highlight the modulation of TGF-β as a method to target two of the greatest causes of morbidity and mortality in breast cancer patients.

Abstract

Triple-negative breast cancer (TNBC) is a subtype of breast cancer that accounts for the majority of breast cancer-related deaths due to the lack of specific targets for effective treatments. While there is immense focus on the development of novel therapies for TNBC treatment, a persistent and critical issue is the rate of heart failure and cardiomyopathy, which is a leading cause of mortality and morbidity amongst cancer survivors. In this review, we highlight mechanisms of post-chemotherapeutic cardiotoxicity exposure, evaluate how this is assessed clinically and highlight the transforming growth factor-beta family (TGF-β) pathway and its significance as a mediator of cardiomyopathy. We also highlight recent findings demonstrating TGF-β inhibition as a potent method to prevent cardiac remodeling, fibrosis and cardiomyopathy. We describe how dysregulation of the TGF-β pathway is associated with negative patient outcomes across 32 types of cancer, including TNBC. We then highlight how TGF-β modulation may be a potent method to target mesenchymal (CD44⁺/CD24⁻) and epithelial (ALDH^high) cancer stem cell (CSC) populations in TNBC models. CSCs are associated with tumorigenesis, metastasis, relapse, resistance and diminished patient prognosis; however, due to plasticity and differential regulation, these populations remain difficult to target and continue to present a major barrier to successful therapy. TGF-β inhibition represents an intersection of two fields: cardiology and oncology. Through the inhibition of cardiomyopathy, cardiac damage and heart failure may be prevented, and through CSC targeting, patient prognoses may be improved. Together, both approaches, if successfully implemented, would target the two greatest causes of cancer-related morbidity in patients and potentially lead to a breakthrough therapy.

Signaling pathways and targeted therapy for myocardial infarction

Although the treatment of myocardial infarction (MI) has improved considerably, it is still a worldwide disease with high morbidity and high mortality. Whilst there is still a long way to go for discovering ideal treatments, therapeutic strategies committed to cardioprotection and cardiac repair following cardiac ischemia are emerging. Evidence of pathological characteristics in MI illustrates cell signaling pathways that participate in the survival, proliferation, apoptosis, autophagy of cardiomyocytes, endothelial cells, fibroblasts, monocytes, and stem cells. These signaling pathways include the key players in inflammation response, e.g., NLRP3/caspase-1 and TLR4/MyD88/NF-κB; the crucial mediators in oxidative stress and apoptosis, for instance, Notch, Hippo/YAP, RhoA/ROCK, Nrf2/HO-1, and Sonic hedgehog; the controller of myocardial fibrosis such as TGF-β/SMADs and Wnt/β-catenin; and the main regulator of angiogenesis, PI3K/Akt, MAPK, JAK/STAT, Sonic hedgehog, etc. Since signaling pathways play an important role in administering the process of MI, aiming at targeting these aberrant signaling pathways and improving the pathological manifestations in MI is indispensable and promising. Hence, drug therapy, gene therapy, protein therapy, cell therapy, and exosome therapy have been emerging and are known as novel therapies. In this review, we summarize the therapeutic strategies for MI by regulating these associated pathways, which contribute to inhibiting cardiomyocytes death, attenuating inflammation, enhancing angiogenesis, etc. so as to repair and re-functionalize damaged hearts.

LncRNA TDRG1 aggravates TGF-β1-induced fibrogenesis and inflammatory response of cardiac fibroblasts via miR-605-3p/TNFRSF21 axis

ABSTRACT

Heart failure is mainly caused by a decline in the systolic function of the heart. LncRNAs are related to cardiac diseases. This study aimed to explore the effects of lncRNA testis development related gene 1 (TDRG1) on the fibrogenesis and inflammatory response of transforming growth factor-beta1 (TGF-β1)-stimulated human cardiac fibroblasts (HCFs). Levels of proinflammatory cytokines were evaluated by ELISA. RT-qPCR was applied to reveal the expression levels of TDRG1, miR-605-3p and TNFRSF21. Western blot analysis was prepared to detect protein levels of TNFRSF21 and fibrosis related genes. Luciferase reporter assay was conducted for confirming the interaction between miR-605-3p and TDRG1/TNFRSF21. We found that TGF-β1-stimulated HCFs showed high concentrations of proinflammatory cytokines, and increased protein levels of fibrosis related genes, suggesting the dysfunctions of TGF-β1-stimulated HCFs. In addition, TDRG1 was upregulated in TGF-β1-stimulated HCFs. We found that interfering with TDRG1 alleviated dysfunctions of TGF-β1-stimulated HCFs. Moreover, TDRG1 bound with miR-605-3p. MiR-605-3p exerted the anti-fibrogenic and anti-inflammatory effects in TGF-β1-treated HCFs. As a target gene of miR-605-3p, TNFRSF21, reversed the anti-fibrogenic and anti-inflammatory effects of TDRG1 knockdown in TGF-β1-treated HCFs. Overall, our study confirmed that TDRG1 aggravates fibrogenesis and inflammatory response in TGF-β1-treated HCFs via the miR-605-3p/TNFRSF21 axis.

Communication Between Cardiomyocytes and Fibroblasts During Cardiac Ischemia/Reperfusion and Remodeling: Roles of TGF-β, CTGF, the Renin Angiotensin Axis, and Non-coding RNA Molecules

Communication between cells is a foundational concept for understanding the physiology and pathology of biological systems. Paracrine/autocrine signaling, direct cell-to-cell interplay, and extracellular matrix interactions are three types of cell communication that regulate responses to different stimuli. In the heart, cardiomyocytes, fibroblasts, and endothelial cells interact to form the cardiac tissue. Under pathological conditions, such as myocardial infarction, humoral factors released by these cells may induce tissue damage or protection, depending on the type and concentration of molecules secreted. Cardiac remodeling is also mediated by the factors secreted by cardiomyocytes and fibroblasts that are involved in the extensive reciprocal interactions between these cells. Identifying the molecules and cellular signal pathways implicated in these processes will be crucial for creating effective tissue-preserving treatments during or after reperfusion. Numerous therapies to protect cardiac tissue from reperfusion-induced injury have been explored, and ample pre-clinical research has attempted to identify drugs or techniques to mitigate cardiac damage. However, despite great success in animal models, it has not been possible to completely translate these cardioprotective effects to human applications. This review provides a current summary of the principal molecules, pathways, and mechanisms underlying cardiomyocyte and cardiac fibroblast crosstalk during ischemia/reperfusion injury. We also discuss pre-clinical molecules proposed as treatments for myocardial infarction and provide a clinical perspective on these potential therapeutic agents.

Protective effect of valsartan against doxorubicin-induced cardiotoxicity: Histopathology and metabolomics in vivo study

Doxorubicin (DOX) treatment has been associated with cardiotoxicity. Therefore, it is crucial to search for a therapeutic that can effectively mitigate DOX-induced cardiotoxicity. This study was conducted to investigate the protective effects of valsartan (VAL) against DOX-induced cardiotoxicity. Sprague-Dawley rats were divided into four treatment groups: Group I: Control, Group II: VAL (30 mg/kg, ip), Group III: DOX (15 mg/kg, ip), and Group IV: VAL + DOX (30 + 15 mg/kg, ip). All groups were treated every other day for 14 days. Blood was isolated for biochemical and metabolomics studies, and sections of the heart were also analyzed for histopathological and immunohistochemical alterations to detect changes in P53, BAX, BCL-2, and P62 expression. The combination of VAL + DOX resulted in a marked decrease in cardiac biomarker enzymes (aminotransferase and creatine phosphokinase) compared to DOX monotherapy. In addition, the histopathological examination of the VAL + DOX combination revealed a low percentage of fibrosis and inflammation. Immunohistochemical expression of p53 and BAX was significantly reduced, whereas BCL-2 expression was significantly increased in the VAL + DOX treatment group compared to DOX monotherapy. Also, the combination of VAL + DOX reverses the negative effect of DOX on nuclear p62 expression. Analysis of serum metabolites showed that DOX monotherapy reduced the number of several amino acids, whereas the combination of VAL + DOX restored these metabolic pathways. This study revealed the potential cardioprotective effect of VAL, which may provide novel and promising approaches for managing cardiotoxicity induced by DOX.

Resveratrol improves cardiac function and left ventricular fibrosis after myocardial infarction in rats by inhibiting NLRP3 inflammasome activity and the TGF-β1/SMAD2 signaling pathway

Background

Several studies have shown that resveratrol (RES), a naturally occurring polyphenol found in many plants, is beneficial for preventing cardiovascular diseases. However, the mechanism underlying the RES-mediated protection against myocardial infarction has not yet been revealed entirely. In this study, we investigated the protective effects of RES on cardiac function in a rat model of acute myocardial infarction (AMI) and the related underlying mechanisms.

Methods

Male Sprague-Dawley rats were randomly divided into four groups: Sham (sham operation), Sham-RES, AMI (AMI induction), and AMI-RES. The rat AMI model was established by the permanent ligation of left anterior descending coronary artery method. The rats in the RES-treated groups were gavaged with RES (50 mg/kg/day) daily for 45 days after the Sham operation or AMI induction; rats in the Sham and AMI groups were gavaged with deionized water. Cardiac function was evaluated by echocardiography. Atrial interstitial fibrosis was assessed by hematoxylin-eosin or Masson’s trichrome staining. Real-time PCR and western blotting analyses were performed to examine the levels of signaling pathway components.

Results

RES supplementation decreased the inflammatory cytokine levels, improved the cardiac function, and ameliorated atrial interstitial fibrosis in the rats with AMI. Furthermore, RES supplementation inhibited NLRP3 inflammasome activity, decreased the TGF-β1 production, and downregulated the p-SMAD2/SMAD2 expression in the heart.

Conclusion

RES shows notable cardioprotective effects in a rat model of AMI; the possible mechanisms underlying these effects may involve the improvement of cardiac function and atrial interstitial fibrosis via the RES-mediated suppression of NLRP3 inflammasome activity and inhibition of the TGF-β1/SMAD2 signaling pathway in the heart.

Curcumin relieves the arecoline-induced fibrosis of oral mucosal fibroblasts via inhibiting HIF-1α/TGF-β/CTGF signaling pathway: an in vitro study

Oral submacosal fibrosis (OSF) has been recognized as one of the oral potentially malignant disorders. Areca nut chewing is implicated in this pathological fibrosis. The current treatments for OSF have failed to achieve the desired curative effect. Here, we propose that curcumin has excellent therapeutic effect on OSF and explore its specific mechanism. Transwell assay was performed to detected cell migration. Flow cytometry was used to measured apoptosis. And MTT assay was performed to test cell viability. Gene and protein levels were detected by quantitative real-time polymerase chain reaction (qPCR) and western blotting. Our results displayed that curcumin treatment reduced fibrosis-related molecules (collagen type I alpha 1, collagen type III alpha 1, tissue inhibitor of metalloprotease 2) in arecoline-treated oral mucosal fibroblasts and elevated matrix metalloproteinase 2 expression. Additionally, curcumin could suppress cell proliferation and migration, and enhance the apoptosis of arecoline-treated normal oral mucosal fibroblasts. Most importantly, the hypoxia-inducible factor-1α (HIF-1α), transforming growth factor-β (TGF-β) and connective tissue growth factor (CTGF) expressions in arecoline-treated normal oral mucosal fibroblasts were reduced after exposure to curcumin, whereas the activation of HIF-1α/TGF-β/CTGF axis reversed curcumin's effect on improving fibrosis of arecoline-treated normal oral mucosal fibroblasts. Therefore, curcumin alleviated oral submucosal fibrosis via inhibiting HIF-1α/TGF-β/CTGF axis. In summary, curcumin effectively inhibited the migration and proliferation and promoted apoptosis in arecoline-induced normal oral mucosal fibroblasts by inactivating HIF-1α/TGF-β/CTGF pathway. And curcumin might be a potential therapeutic drug for OSF treatment.

Optimal vacuum erectile device therapy regimen for penile rehabilitation in a bilateral cavernous nerve crush rat model

BACKGROUND

Vacuum erectile device (VED) therapy has been widely used in penile rehabilitation after radical prostatectomy; however, there is no consensus on the best regimen.

OBJECTIVES

To explore an optimal VED therapy regimen in bilateral cavernous nerve crush (BCNC) rat model.

MATERIALS AND METHODS

Adult male rats were used to measure the effects of different durations (1-30 min) of VED treatment on penile length, penile blood gas analysis, and adverse effects. Forty-eight adult male rats were randomly divided into Sham, BCNC, and VED treatment groups (2-3-2-3 min, 4-3-3 min, 5-5 min, and 10 min). Penile length, erectile function, and side effects were detected after VED treatment. Histopathological staining and Western blotting were performed to explore the cellular and molecular changes.

RESULTS

Prolongation of the duration of VED treatment significantly decreased the penile oxygen saturation, partial oxygen pressure, and arterial blood ratio (P < 0.05). Compared with the BCNC group, all VED treatment regimens partially reversed BCNC-induced penile shortening and erectile dysfunction (P < 0.0001), with the 4-3-3-min and 5-5-min treatment groups exhibiting more significant improvement than the 10-min and 2-3-2-3-min treatment groups (P < 0.0001). The mechanism may be related to the up-regulation of the smooth muscle cell/collagen ratio, endothelial nitric oxide synthase, and α-smooth muscle actin (all P < 0.0001); and the down-regulation of hypoxia-inducible factor-1α, transforming growth factor-β1, and apoptosis (all P < 0.0001). The incidence of adverse effects in the 2-3-2-3-min treatment group was the highest.

DISCUSSION

The commonly used VED therapy regimens maintained erectile function and penile length of BCNC rat by relieving hypoxia and fibrosis, and no further benefits were observed with increased treatment frequency or prolonged treatment duration.

CONCLUSION

Two consecutive 5-min treatments with a short interval is the optimal VED therapy regimen for penile rehabilitation in BCNC rat model.

Adiponectin Modified BMSCs Alleviate Heart Fibrosis via Inhibition TGF-beta1/Smad in Diabetic Rats

Background: Accumulating evidence suggested that bone marrow mesenchymal stem cells (BMSCs) have therapeutic potential for diabetes and heart diseases. However, the effects of BMSC on reducing myocardial fibrosis need to be optimized. This study aimed to investigate the mechanism of adiponectin (APN) modified BMSCs on myocardial fibrosis in diabetic model in vivo and in vitro.

Methods: The high-fat diet combined with streptozotocin (STZ) injection were used to induced diabetic rat model. H9c2 cells were cultured under a high glucose medium as in vitro model. The BMSCs were modified by APN plasmid or APN small interfering RNA (siRNA), then transplanted to the diabetic rats by a single tail-vein injection, or co-cultured with H9c2 cells.

Results: We demonstrated that diabetic rats showed typical diabetic symptoms, such as decreased cardiac function, accumulation of pathological lesions and collagen expression. However, these impairments were significantly prevented by the APN modified BMSCs treatment while no effects on APN siRNA modified BMSCs treated diabetic rats. Moreover, we confirmed that APN modified BMSCs could attenuate the expression of TGF-beta1/smad to suppress the myocardial fibrosis in the diabetic rats and high glucose induced H9c2 cells.

Conclusion: The present results for the first time showed that APN modified BMSCs exerted protection on cardiac fibrosis via inhibiting TGF-beta1/smad signal pathway in diabetic rats. Our findings suggested that APN modified BMSCs might be a novel and optimal therapy for the diabetic cardiomyopathy in future.

Apigenin suppresses TGF-β1-induced cardiac fibroblast differentiation and collagen synthesis through the downregulation of HIF-1α expression by miR-122-5p

BACKGROUND

Apigenin can reduce cardiomyocyte hypertrophy by downregulating hypoxia inducible factor-1 alpha (HIF-1α) expression. However, its effects on cardiac fibroblasts (CFs) and its exact inhibitory molecular mechanisms on HIF-1α remain unclear.

PURPOSE

This study aims to examine the effects of apigenin on cell proliferation and differentiation, microRNA-122-5p (miR-122-5p) expression, and HIF-1α-mediated Smad signaling pathway in transforming growth factor beta 1 (TGF-β1)-stimulated CFs and cardiac fibrosis and to investigate the relationship between miR-122-5p and HIF-1α.

METHODS

The TGF-β1-stimulated CFs, the combination of TGF-β1-stimulated and miR-122-5p mimic-transfected CFs, the combination of TGF-β1-stimulated and miR-122-5p inhibitor-transfected CFs, and the isoproterenol-induced cardiac fibrotic mice were used and treated with or without apigenin. The recombinant lentiviruses overexpressing HIF-1α vector and miR-122-5p mimic were co-transfected to observe their interaction. Related mRNA and protein expressions and myocardial collagen were determined. The luciferase reporter gene that contains HIF-1α wild type or mutant type 3'-UTR was used, and the luciferase activity was determined to verify the direct link between miR-122-5p and HIF-1α.

RESULTS

In the TGF-β1-stimulated CFs, apigenin treatment increased the miR-122-5p and Smad7 expressions and decreased the HIF-1α, α-smooth muscle actin, collagen Ⅰ/Ⅲ, Smad2/3, and p-Smad2/3 expressions. Similar and inverse results were observed in the miR-122-5p mimic- and inhibitor-transfected CFs, respectively. Moreover, the miR-122-5p mimic could antagonize the effects of TGF-β1 in the TGF-β1 and miR-122-5p mimic-combined CFs, and the miR-122-5p inhibitor could enhance the effects of TGF-β1 in the TGF-β1 and miR-122-5p inhibitor-combined CFs. In the two aforementioned cell models, the addition of apigenin could further enhance the effects of miR-122-5p mimic and partially reverse the effects of miR-122-5p inhibitor. After treatment of HIF-1α-transfected CFs with miR-122-5p mimic, the HIF-1α expression decreased. Further study confirmed that HIF-1α was a direct target of miR-122-5p. Apigenin also decreased the myocardial collagen accumulation in cardiac fibrotic mice.

CONCLUSION

Apigenin could suppress the differentiation and collagen synthesis of TGF-β1-stimulated CFs and mouse cardiac fibrosis, and its mechanisms were related to the increment of miR-122-5p expression and subsequent downregulation of HIF-1α expression via direct interaction, which might finally result in the decrements of Smad2/3 and p-Smad2/3 expressions and increment of Smad7 expression.

SIRT6 promotes angiogenesis and hemorrhage of carotid plaque via regulating HIF-1α and reactive oxygen species

As a member of Sirtuins family, SIRT6 participates in the physiological and pathological progress of DNA repair, anti-aging, metabolism, and so on. Several studies have demonstrated that knockdown of SIRT6 inhibited the development of atherosclerosis (AS), indicated SIRT6 as a protective factor for AS. However, we confirmed SIRT6 was significantly overexpressed in human unstable carotid plaques compared with stable carotid plaques. This result indicated a more complex role of SIRT6 in AS. Furthermore, we constructed mice model with unstable carotid plaque and injected them with SIRT6 overexpressed adeno-associated virus (AAV-SIRT6). AAV-SIRT6 significantly promoted angiogenesis as well as hemorrhage in plaques. In vitro, we demonstrated overexpression of SIRT6 prevented HIF-1α from degradation by deubiquitination at K37 and K532 of HIF-1α, thus promoted the expression of HIF-1α under both normoxia and hypoxia in human umbilical vein endothelial cells (HUVECs). Through regulating HIF-1α, overexpression of SIRT6 promoted invasion, migration, proliferation, as well as tube formation ability of HUVECs. Interestingly, under different conditions, SIRT6 played different roles in the function of HUVECs. Under oxidative stress, another important pathological environment for AS, SIRT6 bound to the promoter of Catalase, a main reactive oxygen species scavenger, and depleted H3K56 acetylation, thus inhibited expression and activity of Catalase at the transcriptional level. Subsequently, inhibited Catalase promoted reactive oxygen species (ROS) under oxidative stress. Accumulated ROS further aggravated oxidative stress injury of HUVECs. On one hand, SIRT6 promoted angiogenesis in plaque via HIF-1α under hypoxia. On the other hand, SIRT6 promoted injury of neovascular via ROS under oxidative stress. It is this process of continuous growth and damage that leads to hemorrhage in carotid plaque. In conclusion, we innovatively confirmed SIRT6 promoted the angiogenesis and IPH via promoting HIF-1α and ROS in different environments, thus disclosed the unknowing danger of SIRT6.

Health-promoting role of dietary bioactive compounds through epigenetic modulations: a novel prophylactic and therapeutic approach

The epigenome is an overall epigenetic state of an organism, which is as important as that of the genome for normal development and functioning of an individual. Epigenetics involves heritable but reversible changes in gene expression through alterations in DNA methylation, histone modifications and regulation of non-coding RNAs in cells, without any change in the DNA sequence. Epigenetic changes are owned by various environmental factors including pollution, microbiota and diet, which have profound effects on epigenetic modifiers. The bioactive compounds present in the diet mainly include curcumin, resveratrol, catechins, quercetin, genistein, sulforaphane, epigallocatechin-3-gallate, alkaloids, vitamins, and peptides. Bioactive compounds released during fermentation by the action of microbes also have a significant effect on the host epigenome. Besides, recent studies have explored the new insights in vitamin's functions through epigenetic regulation. These bioactive compounds exert synergistic, preventive and therapeutic effects when combined as well as when used with chemotherapeutic agents. Therefore, these compounds have potential of therapeutic agents that could be used as "Epidrug" to treat many inflammatory diseases and various cancers where chemotherapy results have many side effects. In this review, the effect of diet derived bioactive compounds through epigenetic modulations on in vitro and in vivo models is discussed.

Investigating the potential effects of selective histone deacetylase 6 inhibitor ACY1215 on infarct size in rats with cardiac ischemia-reperfusion injury

BACKGROUND

Despite the fact that histone deacetylase (HDAC) inhibitors have been tested to treat various cardiovascular diseases, the effects of selective HDAC6 inhibitor ACY1215 on infarct size during cardiac ischemia-reperfusion (IR) injury still remain unknown. In the present study we aimed to investigate the effects of ACY1215 on infarct size in rats with cardiac IR injury, as well as to examine the association between HDAC6 inhibitors and the gene expression of hypoxia inducible factor-1α (HIF-1α), a key regulator of cellular responses to hypoxia.

METHODS

By using computational analysis of high-throughput expression profiling dataset, the association between HDAC inhibitors (pan-HDAC inhibitors panobinostat and vorinostat, and HDAC6 inhibitor ISOX) and their effects on HIF-1α gene-expression were evaluated. The male Wistar rats treated with ligation of left coronary artery followed by reperfusion were used as a cardiac IR model. ACY1215 (50 mg/kg), pan-HDAC inhibitor MPT0E028 (25 mg/kg), and vehicle were intraperitoneally injected within 5 min before reperfusion. The infarct size in rat myocardium was determined by 2,3,5-triphenyltetrazolium chloride staining. The serum levels of transforming growth factor-β (TGF-β) and C-reactive protein (CRP) were also determined.

RESULTS

The high-throughput gene expression assay showed that treatment of ISOX was associated with a more decreased gene expression of HIF-1α than that of panobinostat and vorinostat. Compared to control rats, ACY1215-treated rats had a smaller infarct size (49.75 ± 9.36% vs. 19.22 ± 1.70%, p < 0.05), while MPT0E028-treated rats had a similar infarct size to control rats. ACY-1215- and MPT0E028-treated rats had a trend in decreased serum TGF-β levels, but not statistically significant. ACY1215-treated rats also had higher serum CRP levels compared to control rats (641.6 μg/mL vs. 961.37 ± 64.94 μg/mL, p < 0.05).

CONCLUSIONS

Our research indicated that HDAC6 inhibition by ACY1215 might reduce infarct size in rats with cardiac IR injury possibly through modulating HIF-1α expression. TGF-β and CRP should be useful biomarkers to monitor the use of ACY1215 in cardiac IR injury.

Interaction Between Sacubitril and Valsartan in Preventing Heart Failure Induced by Aortic Valve Insufficiency in Rats

BACKGROUND

Synergistic interactions between neprilysin inhibition (NEPi) with sacubitril and angiotensin receptor type1 blockade (ARB) with valsartan have been implicated in improvement of left ventricular (LV) contractility, relaxation, exercise tolerance, and fibrosis in preexisting heart failure (HF) induced by aortic valve insufficiency (AVI). It is not known whether this pharmacologic synergy can prevent cardiovascular pathology in a similar AVI model. Our aim was to investigate the pharmacology of sacubitril/valsartan in an experimental setting with therapy beginning immediately after creation of AVI.

METHODS

HF was induced through partial disruption of the aortic valve in rats. Therapy began 3 hours after valve disruption and lasted 8 weeks. Sacubitril/valsartan (68 mg/kg), valsartan (31 mg/kg), sacubitril (31 mg/kg), or vehicle were administered daily via oral gavage (N=8 in each group). Hemodynamic assessments were conducted using Millar technology, and an exercise tolerance test was conducted using a rodent treadmill.

RESULTS

Only sacubitril/valsartan increased total arterial compliance and ejection fraction (EF). Therapies with sacubitril/valsartan and valsartan similarly improved load-dependent (dP/dt_max) and load independent indices (Ees) of LV contractility, and exercise tolerance, whereas sacubitril did not. None of the therapies improved LV relaxation (dP/dt_min), whereas all reduced myocardial fibrosis.

CONCLUSIONS

1) The synergistic interaction between NEPi and ARB in early therapy with sacubitril/valsartan leads to increased total arterial compliance and EF. 2) Improvement in indices of LV contractility, and exercise tolerance with sacubitril/valsartan is likely because of ARB effect of valsartan. 3) All three therapies provided antifibrotic effects, suggesting both ARB and NEPi are capable of reducing myocardial fibrosis.

Hypoxia inducible factor 1α in vascular smooth muscle cells promotes angiotensin II-induced vascular remodeling via activation of CCL7-mediated macrophage recruitment

The process of vascular remodeling is associated with increased hypoxia. However, the contribution of hypoxia-inducible factor 1α (HIF1α), the key transcription factor mediating cellular hypoxic responses, to vascular remodeling is established, but not completely understood. In the angiotensin II (Ang II)-induced vascular remodeling model, HIF1α was increased and activated in vascular smooth muscle cells (VSMCs). Selective genetic disruption of Hif1a in VSMCs markedly ameliorated Ang II-induced vascular remodeling, as revealed by decreased blood pressure, aortic thickness, collagen deposition, inflammation, and aortic stiffness. VSMC Hif1a deficiency also specifically suppressed Ang II-induced infiltration of CD45⁺CD11b⁺F4/80⁺CD206⁻ M1 macrophages into the vessel. Mechanistically, HIF1α deficiency in VSMCs dramatically suppressed the expression of CCL7, a chemokine critical for macrophage recruitment. Bioinformatic analysis and chromatin immunoprecipitation assays revealed three functional hypoxia-response elements in the Ccl7 promoter, indicating that Ccl7 is a direct HIF1α target gene. Blocking CCL7 with antibody in vivo alleviated Ang II-induced hypertension and vascular remodeling, coincident with decreased macrophage infiltration. This study provides direct evidence that HIF1α activation in VSMCs exacerbates Ang II-induced macrophage infiltration and resultant vascular remodeling via its target gene Ccl7, and thus may serve as a potential therapeutic target for remodeling-related vascular disease.

Ellagic acid inhibits proliferation and migration of cardiac fibroblasts by down-regulating expression of HDAC1

Cardiac fibroblasts (CFs) could be activated after myocardial infarction (MI). Thus, it is necessary to explore effective drugs to suppress the activation of CFs following MI. This study was designed to investigate the impacts of ellagic acid on CFs and the underlying mechanisms. The expression of histone deacetylases (HDACs) and fibrosis-related genes was detected by qRT-PCR and western blot. The Masson's Trichrome Staining assay was used to evaluate the area of cardiac fibrosis. The proliferation and migration of CFs were measured by CCK8 Kit and Transwell assay, respectively. Our results showed that ellagic acid significantly reduced protein expression of HDAC1, mRNA expression of collagen I, collagen III, MMP-2 and MMP-9 and the area of cardiac fibrosis in MI rats. In Ang II-stimulated CFs, ellagic acid (60 μmol/L) decreased the protein expression of HDAC1, collagen I, collagen III, MMP-2 and MMP-9, and inhibited cell proliferation and migration. Further, HDAC1 over-expression reversed the inhibitor effects of ellagic acid on proteins expression (collagen I, collagen III, MMP-2 and MMP-9) and proliferation and migration of CFs. The present results suggested that ellagic acid suppressed proliferation and migration of CFs by down-regulating expression of HDAC1.

Hypoxia-inducible factor 1-alpha (HIF-1α) as a factor mediating the relationship between obesity and heart failure with preserved ejection fraction

Heart failure with preserved ejection fraction (HFpEF), a common condition with an increased mortality, is strongly associated with obesity and the metabolic syndrome. The latter two conditions are associated with increased epicardial fat that can extend into the heart. This review advances the proposition that hypoxia-inhibitory factor-1α (HIF-1α) maybe a key factor producing HFpEF. HIF-1α, a highly conserved transcription factor that plays a key role in tissue response to hypoxia, is increased in adipose tissue in obesity. Increased HIF-1α expression leads to expression of a potent profibrotic transcriptional programme involving collagen I, III, IV, TIMP, and lysyl oxidase. The net effect is the formation of collagen fibres leading to fibrosis. HIF-1α is also responsible for recruiting M1 macrophages that mediate obesity-associated inflammation, releasing IL-6, MCP-1, TNF-α, and IL-1β with increased expression of thrombospondin, pro α2 (I) collagen, transforming growth factor β, NADPH oxidase, and connective tissue growth factor. These factors can accelerate cardiac fibrosis and impair cardiac diastolic function. Inhibition of HIF-1α expression in adipose tissue of mice fed a high-fat diet suppressed fibrosis and reduces inflammation in adipose tissue. Delineation of the role played by HIF-1α in obesity-associated HFpEF may lead to new potential therapies.

The ATRQβ-001 vaccine improves cardiac function and prevents postinfarction cardiac remodeling in mice

We invented the ATRQβ-001 hypertension vaccine, which targeted angiotensin II type 1 receptor (AT₁R) and showed a desirable blocking effect for AT₁R. The purpose of this study was to investigate whether the ATRQβ-001 vaccine could improve cardiac function and prevent cardiac remodeling after acute myocardial infarction (AMI). C57BL/6 male mice were randomly assigned into four groups: sham + VLP, MI + VLP, MI + ATRQβ-001, and MI + valsartan. Mice were administered Qβ virus-like particle (Qβ-VLP, 100 μg/time), ATRQβ-001 vaccine (100 μg/time), and valsartan (6 mg/kg/day) before AMI, which was induced by permanently ligating the left anterior descending coronary artery. The effect of the ATRQβ-001 vaccine on cardiac function and cardiac remodeling was observed by following up for 1 week, 4 weeks, and 12 weeks post MI. The ATRQβ-001 vaccine significantly reduced sudden cardiac death and increased survival rates (compared with MI + VLP, 80% versus 55% and mean estimate (days) 68.4 ± 7.0 versus 47.8 ± 8.9, respectively; p = 0.046) post MI. Echocardiography showed that the ATRQβ-001 vaccine remarkably improved cardiac function (left ventricular ejection fraction, 24.8 ± 7.0% versus 13.2 ± 3.8%, p = 0.005) post MI. Histological analysis revealed that the ATRQβ-001 vaccine obviously mitigated myocardial inflammation, apoptosis, and fibrosis after AMI. Further, the ATRQβ-001 vaccine significantly inhibited the TGF-β1/Smad2/3 signaling pathway. Assessment of the renin-angiotensin system (RAS) demonstrated that the ATRQβ-001 vaccine did not cause obvious feedback of circulating RAS, but prominently attenuated the expression of AT₁R, compared with the other groups at 4 and 12 weeks after AMI. In conclusion, the ATRQβ-001 vaccine decreased mortality and improved cardiac function and remodeling after AMI.

Piperlongumine inhibits angiotensin II-induced extracellular matrix expression in cardiac fibroblasts

Piperlongumine (PL), a single component isolated from Piper longum, has been reported to possess anti-inflammatory, antibacterial, antiangiogenic, antioxidant, antitumor, and antidiabetic activities. However, its role in cardiac fibrosis remains to be clarified. Therefore, we determined the effects of PL on cardiac fibroblasts (CFs) proliferation, and extracellular matrix (ECM) production under angiotensin II (Ang II) conditions, and further investigated the underlying molecular mechanism. Our data revealed that PL inhibited the proliferation and migration of CFs induced by Ang II. In addition, PL blocked the transformation of CFs to myofibroblasts induced by Ang II, as well as decreased cellular reactive oxygen species (ROS) production and malondialdehyde level in Ang II-stimulated CFs. Furthermore, PL significantly suppressed the Ang II-increased phosphorylation of extracellular regulated protein kinase 1/2 (ERK1/2) in CFs. Taken together, the results of the current study demonstrated that PL inhibits Ang II-induced cell proliferation, migration, and ECM expression in CFs through the inactivation of the ERR1/2 signaling pathway. These data strongly suggest that PL may be a promising therapeutic candidate for the treatment of cardiac fibrosis.

Synergy between sacubitril and valsartan leads to hemodynamic, antifibrotic, and exercise tolerance benefits in rats with preexisting heart failure

Simultaneous neprilysin inhibition (NEPi) and angiotensin receptor blockade (ARB) with sacubitril/valsartan improves cardiac function and exercise tolerance in patients with heart failure. However, it is not known whether these therapeutic benefits are primarily due to NEPi with sacubitril or ARB with valsartan or their combination. Therefore, the aim of the present study was to investigate the potential contribution of sacubitril and valsartan to the benefits of the combination therapy on left ventricular (LV) function and exercise tolerance. Heart failure was induced by volume overload via partial disruption of the aortic valve in rats. Therapy began 4 wk after valve disruption and lasted through 8 wk. Drugs were administered daily via oral gavage [sacubitril/valsartan (68 mg/kg), valsartan (31 mg/kg), and sacubitril (31 mg/kg)]. Hemodynamic assessments were conducted using Millar technology, and an exercise tolerance test was conducted using a rodent treadmill. Therapy with sacubitril/valsartan improved load-dependent indexes of LV contractility (dP/d t_max) and relaxation (dP/d t_min), exercise tolerance, and mitigated myocardial fibrosis, whereas monotherapies with valsartan, or sacubitril did not. Both sacubitril/valsartan and valsartan similarly improved a load-independent index of contractility [slope of the end-systolic pressure-volume relationship ( E_es)]. Sacubitril did not improve E_es. First, synergy of NEPi with sacubitril and ARB with valsartan leads to the improvement of load-dependent LV contractility and relaxation, exercise tolerance, and reduction of myocardial collagen content. Second, the improvement in load-independent LV contractility with sacubitril/valsartan appears to be solely due to ARB with valsartan constituent. NEW & NOTEWORTHY Our data suggest the following explanation for the effects of sacubitril/valsartan: 1) synergy of sacubitril and valsartan leads to the improvement of load-dependent left ventricular contractility and relaxation, exercise tolerance, and reduction of myocardial fibrosis and 2) improvement in load-independent left ventricular contractility is solely due to the valsartan constituent. The findings offer a better understanding of the outcomes observed in clinical studies and might facilitate the continuing development of the next generations of angiotensin receptor neprilysin inhibitors.

Single-Stranded DNA-Binding Protein 1 Abrogates Cardiac Fibroblast Proliferation and Collagen Expression Induced by Angiotensin II

Angiotensin II (Ang II), an effective component of renin-angiotensin system, plays a pivotal role in cardiac fibrosis, which may further contribute to heart failure. Single-stranded DNA-binding protein 1 (SSBP1), a DNA damage response protein, regulates both mitochondrial function and extracellular matrix remodeling. In this study, we aim to investigate the role of SSBP1 in cardiac fibrosis that is induced by Ang II. We infused C57BL/6J mice with vehicle or Ang II and valsartan using implanted osmotic mini-pumps. Moreover, heart function was examined by echocardiography and cardiac fibrosis was analyzed via picrosirus red staining. The expression of COL1A1, COL3A1, SSBP1, p53, Nox1, and Nox4 was analyzed via qRT-PCR and/or immunoblots. The SSBP1 expression was manipulated via SSBP1 shRNA and pcDNA3.1/SSBP1 plasmids, while the p53 expression was enhanced via AdCMV-p53 infection. The exposure to Ang II increased the mouse heart weight, systolic blood pressure, interventricular septal thickness diastolic (IVSTD) and left ventricular end posterior wall dimension diastolic (LVPWD), which were counteracted by valsartan. While cardiac fibrosis was induced with Ang II treatment, it was relieved using valsartan. Furthermore, Ang II treatment caused mitochondrial dysfunction, oxidative stress, and down-regulated SSBP1 expression. The knockdown of SSBP1 increased cardiac fibroblast proliferation, collagen expression, and decreased p53 expression, which was impeded via SSBP1 overexpression. Moreover, the forced expression of p53 abated the fibroblast proliferation and collagen expression that was induced by Ang II. To summarize, SSBP1 was down-regulated by Ang II and implicated in cardiac fibroblast proliferation and collagen expression partly via the p53 protein.

Toll-like receptor 4 contributes to a myofibroblast phenotype in cardiac fibroblasts and is associated with autophagy after myocardial infarction in a mouse model

BACKGROUND AND AIMS

Cardiac fibrosis after myocardial infarction (MI) is involved in fibroblast transforming and differentiating into myofibroblast phenoconversion, however, the underlying mechanisms are poorly understood. Toll-like receptor 4 (TLR4)-mediated pathogen-associated molecular patterns are key factors that deteriorate cardiac remodelling after MI. Moreover, autophagy has dual roles in cell survival in myocardial tissues after MI. We evaluated the relationship between TLR4 signalling and cardiac myofibroblast transformation-differentiation after MI in vivo and in vitro and analysed the role of autophagy.

METHODS

We reproduced a model of MI by the permanent ligation of the left anterior descending coronary artery of Tlr4-knockout (Tlr4^-/-) and wild-type (WT) male mice. We evaluated scar formation, myofibroblast phenoconversion, LC3 dot formation, autophagy related proteins and α-smooth muscle actin (SMA) in cardiac tissues, 7, 14, and 28 days after myocardial infarction. Cardiac fibroblasts were cultured from Tlr4^-/- or WT mice. Vimentin, α-SMA, bilayer membrane vesicle structures of autophagosomes, and autophagy related proteins were observed after treatment with lipopolysaccharide (LPS) or 3-methyladenine (3-MA) at 24 h.

RESULTS

After MI on 7, 14, and 28 days, Tlr4^-/- mice showed that heart tissue fibrosis and expression of α-SMA, a marker of myofibroblasts, were decreased compared to WT mice. Additionally, levels of LC3II, Atg5, Atg7, and Beclin-1, which are involved in autophagy, were lower than those in WT mice. Further, p62 expression, which is negatively correlated with autophagy levels, was higher in Tlr4^-/- mice. Moreover, LC3-labelled autophagosomes in cardiac tissues were reduced in these animals. In vitro, LPS, a ligand of TLR4, stimulated α-SMA expression in cardiac fibroblasts, enhanced autophagic flux, and increased autophagosome numbers. In contrast, these effects were not obvious in Tlr4^-/- cardiac fibroblasts. LC3II, Atg5, Atg7, and Beclin-1 were upregulated, and p62 was downregulated in cardiac fibroblasts of WT mice stimulated with LPS. However, these effects were blocked by 3-methyladenine, an inhibitor of autophagy.

CONCLUSIONS

These results suggest that TLR4 signalling executes the development of a myofibroblast phenotype after MI via autophagy and could be therapeutically exploited to improve outcome after myocardial injury.

Flavonoid Extract from Propolis Inhibits Cardiac Fibrosis Triggered by Myocardial Infarction through Upregulation of SIRT1

The flavonoid extract from propolis (FP) has been shown to protect against heart injury induced by isoproterenol. However, the effect of FP on cardiac fibrosis after myocardial infarction (MI) as well as the underlying mechanisms is not known. In the present study, we used biochemical and histological approaches to examine the effects of FP on MI-induced cardiac fibrosis and the related mechanisms in a rat MI model and in angiotensin II- (Ang II-) treated rat cardiac fibroblasts (CFs). In vivo, MI was generated by ligation of the left anterior descending coronary artery of rats, which remained for 4 weeks. Rats were randomly divided into the sham, MI, FP (12.5 mg/kg/d), and MI+FP groups. We found that FP treatment improved heart function, reduced cardiac fibrosis, and downregulated the expression of fibrosis-related factors including collagen I, collagen III, matrix metalloproteinase-2 (MMP-2), MMP-9, transforming growth factor-β1 (TGF-β1), and p-Smad2/3, which coincided with the upregulated expression of silent information regulator 1 (SIRT1) in the hearts of MI rats. Our in vitro experiments showed that FP inhibited the proliferation and migration of primary cultured rat CFs and downregulated the expression of the above-mentioned fibrosis-related factors in Ang II-stimulated CFs. In addition, FP can decrease ROS production induced by MI and Ang II in vivo and vitro. Notably, silencing SIRT1 counteracted the FP-induced effects on CFs treated with Ang II. We conclude that FP inhibits MI-induced cardiac fibrosis through SIRT1 activation and that FP represents a potential promising drug for the treatment of MI patients in the clinic.

Oral vitamin-A-coupled valsartan nanomedicine: High hepatic stellate cell receptors accessibility and prolonged enterohepatic residence

So far, liver fibrosis still has no clinically-approved treatment. The loss of stored vitamin-A (V_A) in hepatic stellate cells (HSCs), the main regulators to hepatic fibrosis, can be applied as a mechanism for their targeting. Valsartan is a good candidate for this approach; it is a marketed oral-therapy with inverse- and partial-agonistic activity to the over-expressed angiotensin-II type1 receptor (AT1R) and depleted nuclear peroxisome proliferator-activated receptor-gamma (PPAR-γ), respectively, in activated HSCs. However, efficacy on AT1R and PPAR-γ necessitates high drug permeability which is lacking in valsartan. In the current study, liposomes were used as nanocarriers for valsartan to improve its permeability and hence efficacy. They were coupled to V_A and characterized for HSCs-targeting. Tracing of orally-administered fluorescently-labeled V_A-coupled liposomes in normal rats and their fluorescence intensity quantification in different organs convincingly demonstrated their intestinal entrapment. On the other hands, their administration to rats with induced fibrosis revealed preferential hepatic, and less intestinal, accumulation which lasted up to six days. This indicated their uptake by intestinal stellate cells that acted as a depot for their release over time. Confocal microscopical examination of immunofluorescently-stained HSCs in liver sections, with considerable formula accumulation, confirmed HSCs-targeting and nuclear uptake. Consequently, V_A-coupled valsartan-loaded liposomes (VLC)-therapy resulted in profound re-expression of hepatic Mas-receptor and PPAR-γ, potent reduction of fibrogenic mediators' level and nearly normal liver function tests. Therefore, VLC epitomizes a promising antifibrotic therapy with exceptional extended action and additional PPAR-γ agonistic activity.

MiR-33 promotes myocardial fibrosis by inhibiting MMP16 and stimulating p38 MAPK signaling

Myocardial fibrosis occurs in the late stages of many cardiovascular diseases, and appears to be stimulated by various microRNAs (miRNAs). We previously found that miR-33 may stimulate cardiac remodeling. Here, we examined the involvement of miR-33 in myocardial fibrosis. Proximal left coronary descending artery occlusion was performed in rat, and antagomiR-33a was injected. Primary cardiac fibroblasts were cultured and transfected with miR-33a mimics and inhibitors. miR-33a levels were increased in the rat after surgery, and collagen deposition and heart fibrosis were observed in vivo. Inhibition of miR-33a suppressed fibroblast proliferation, reduced the mRNA and protein levels of collagen-related markers in vitro and in vivo, and rescued the histological damage in vivo. A dual-luciferase reporter system showed that matrix metalloproteinase 16 (MMP16) gene was the direct target of MiR-33a. These results suggest that miR-33 promoted myocardial fibrosis by inhibiting MMP16 and stimulating p38 mitogen-activated protein kinase (p38 MAPK) signaling pathway. MiR-33 may act as a novel therapeutic target for treating myocardial fibrosis.

Abnormal expression of fibrosis markers, estrogen receptor α and stromal derived factor‑1/chemokine (C‑X‑C motif) receptor‑4 axis in intrauterine adhesions

Intrauterine adhesions (IUAs) are mainly derived from fibrous tissue formation following endometrial damage. The aim of the present study was to assess whether fibrosis markers, estrogen receptor (ER)α and the stromal derived factor (SDF)-1/C-X-C chemokine receptor type 4 (CXCR-4) axis are abnormally expressed in IUA endometrium. A total of 76 human endometrial biopsy samples (normal, n=20; mild-to-moderate IUAs, n=40; and severe IUAs, n=16) were employed, and Sprague-Dawley rat IUA models at different time points were constructed. Subsequently, the expression of transforming growth factor (TGF)-β1, matrix metalloproteinase (MMP)-9, ERα and the SDF-1/CXCR-4 axis was evaluated in human and rat IUAs using histology, immunohistochemistry, reverse transcription quantitative polymerase chain reaction and western blotting. In patients and rats with IUA formation, the expression of TGF-β1, MMP-9 and ERα was significantly higher compared with the control group at the mRNA and protein levels (P<0.05); in addition, in patients, the TGF-β1, MMP-9 and ERα levels were significantly higher in severe IUAs compared with those in mild-to-moderate IUA endometrium (P<0.05). Although the chemokine SDF-1 level in rats increased significantly during the early postoperative phase (reaching a peak at the second estrus phase) in rat endometrium (P<0.05), its special receptor CXCR-4 expression did not differ significantly compared with the control group in rats or patients (P>0.05). Our findings indicated that aberrant activation of fibrosis and expression of ERα may be involved in the pathology of IUA formation. The role of the SDF-1/CXCR-4 axis in IUAs as inflammatory medium in the short-term or special homing factors for bone marrow mesenchymal stem cells requires further verification in in vivo animal models.

Recruitment of macrophages from the spleen contributes to myocardial fibrosis and hypertension induced by angiotensin II

INTRODUCTION

The purpose of this study was to determine whether macrophages migrated from the spleen are associated with angiotensin II-induced cardiac fibrosis and hypertension.

METHODS

Sprague-Dawley rats were subjected to angiotensin II infusion in vehicle (500 ng/kg/min) for up to four weeks. In splenectomy, the spleen was removed before angiotensin II infusion. In the angiotensin II AT1 receptor blockade, telmisartan was administered by gastric gavage (10 mg/kg/day) during angiotensin II infusion. The heart and aorta were isolated for Western blot analysis and immunohistochemistry.

RESULTS

Angiotensin II infusion caused a significant reduction in the number of monocytes in the spleen through the AT1 receptor-activated monocyte chemoattractant protein-1. Comparison of angiotensin II infusion, splenectomy and telmisartan comparatively reduced the recruitment of macrophages into the heart. Associated with this change, transforming growth factor β1 expression and myofibroblast proliferation were inhibited, and Smad2/3 and collagen I/III were downregulated. Furthermore, interstitial/perivascular fibrosis was attenuated. These modifications occurred in coincidence with reduced blood pressure. At week 4, invasion of macrophages and myofibroblasts in the thoracic aorta was attenuated and expression of endothelial nitric oxide synthase was upregulated, along with a reduction in aortic fibrosis.

CONCLUSIONS

These results suggest that macrophages when recruited into the heart and aorta from the spleen potentially contribute to angiotensin II-induced cardiac fibrosis and hypertension.

Danshen injection prevents heart failure by attenuating post-infarct remodeling

ETHNOPHARMACOLOGICAL RELEVANCE

Danshen Injection (DSI) is a traditional Chinese medicine extracted from Danshen, prepared from the dried root and rhizome of Salvia miltiorrhiza Bunge. Danshen is an ancient antipyretic traditional Chinese medicine which is mostly used to improve blood circulation and dispel blood stasis. Danshen decoction or liquor-fried Danshen (with grain-based liquor) which is cool in nature is traditionally used to 'cool the blood' and reduce the swelling of sores and abscesses.

AIM OF STUDY

The present study aimed to examine the effect and mechanism of DSI in LAD induced heart injury.

MATERIALS AND METHODS

One day after LAD surgery, adult male Sprague-Dawley rats were randomized to 3 groups: MI group; DSI group (1.5ml/kg/d, intramuscular); and Valsartan group (10mg/kg/d, intragastric). Echocardiography and hemodynamic measurements (Pressure-Volume loop) were performed to evaluate cardiac function. Pathological methods (Masson, and Sirus red staining) were used to check myocardial fibrosis. Western blotting assay was used to detect the protein expression of MMP-2. RT-PCR was used to detect the gene expression of MMP-9, MPO, iNOS, Bcl-2 and Bax.

RESULTS

DSI administration to LAD rats resulted in improved cardiac functions, hemodynamic parameters and normalized ventricular mass. Furthermore, DSI-treated group demonstrated potential regulation of myocardial collagen I and III deposition associated with MMP-2 expression. Also, DSI administration decreased gene expression of iNOS, MPO and MMP-9, and increased Bcl-2/Bax ratio.

CONCLUSION

Myocardial fibrosis, cardiac hypertrophy, hemodynamic deterioration as well as systolic and diastolic dysfunctions which characterize a failing hearts were significantly prevented by DSI. Our study may provide future directions to focus on the anti-hypertrophic mechanisms of DSI and pathological roles played by MMP-2 in myocardial hypertrophy. Meanwhile, DSI also performed the effect of anti-inflammation by the way of decreasing iNOS and MPO. The way Danshen Injection increasing Bcl-2/Bax presented the possibility that it may has the effect of inhibiting cell death.

Amelioration of cardiac dysfunction and ventricular remodeling after myocardial infarction by danhong injection are critically contributed by anti-TGF-β-mediated fibrosis and angiogenesis mechanisms

ETHNOPHARMACOLOGICAL RELEVANCE

Danhong injection (DHI) is a standardized product extracted from Radix et Rhizoma Salviae Miltiorrhizae and Flos Carthami , which has been long applied mainly used to treat ischemic encephalopathy and cardiac diseases including myocardial infarction and angina in clinical practice.

AIM OF THE STUDY

Aim of this study was to investigate the salutary effects of DHI by slowing ventricular remodeling and improving cardiac function after myocardial infarction (MI) in rats.

MATERIALS AND METHODS

In this study, Male Sprague-Dawley rats were subjected to ligation on left anterior descending coronary artery to establish MI models and valsartan was selected as positive control. Cardiac function examination was conducted at the 1st, 3rd, 7th, 14th and the 28th days after LAD. Haematoxylin and Eosin (HE) staining and Masson staining were conducted to observe cardiac pathology and morphological changes levels of VEGF, TGF-β, MMP-2, and MMP-9 in the myocardial tissue were determined in gene and protein expressions.

RESULTS

After 3 days post-treatment and thereafter, EF and FS in DHI group were greater than that of model group (p<0.05). Compared with the MI group, ratio of infarct was markedly decreased in treated-DHI group(p<0.05). TGF-β1 protein and fibrosis-related proteins MMP-2 and MMP-9 were up-regulated after MI, and they were significantly suppressed by the administration of DHI(p<0.05 and p<0.01, respectively). Moreover, DHI improved the mRNA expression of VEGF and increased the blood vessel density of myocardial infarct border zone. DHI decreased the expression of cell apoptosis protein of caspase-3 and increased the anti-apoptotic protein, bcl-2.

CONCLUSIONS

We provided direct evidences that DHI improves cardiac remodeling and preserves ventricular function post-MI in rats. DHI conferred cardio-protection in rats with MI via anti-myocardial apoptosis, angiogenesis, reduction of myocardial fibrosis and many other aspects of joint actions.

Autophagy inhibition of hsa-miR-19a-3p/19b-3p by targeting TGF-β R II during TGF-β1-induced fibrogenesis in human cardiac fibroblasts

Transforming growth factor-β1 (TGF-β1) plays an important role on fibrogenesis in heart disease. MicroRNAs have exhibited as crucial regulators of cardiac homeostasis and remodeling in various heart diseases. MiR-19a-3p/19b-3p expresses with low levels in the plasma of heart failure patients. The purpose of our study is to determine the role of MiR-19a-3p/19b-3p in regulating autophagy-mediated fibrosis of human cardiac fibroblasts. We elucidate our hypothesis in clinical samples and human cardiac fibroblasts (HCF) to provide valuable basic information. TGF-β1 promotes collagen I α2 and fibronectin synthesis in HCF and that is paralleled by autophagic activation in these cells. Pharmacological inhibition of autophagy by 3-methyladenine decreases the fibrotic response, while autophagy induction of rapamycin increases the response. BECN1 knockdown and Atg5 over-expression either inhibits or enhances the fibrotic effect of TGF-β1 in experimental HCF. Furthermore, miR-19a-3p/19b-3p mimics inhibit epithelial mesenchymal transition (EMT) and extracellular matrix (ECM) prodution and invasion of HCF. Functional studies suggest that miR-19a-3p/19b-3p inhibits autophagy of HCF through targeting TGF-β R II mRNA. Moreover, enhancement of autophagy rescues inhibition effect of miR-19a-3p/19b-3p on Smad 2 and Akt phosphorylation through TGF-β R II signaling. Our study uncovers a novel mechanism that miR-19a-3p/19b-3p inhibits autophagy-mediated fibrogenesis by targeting TGF-β R II.

Curcumin protects against myocardial infarction-induced cardiac fibrosis via SIRT1 activation in vivo and in vitro

Curcumin, a polyphenolic compound derived from turmeric, protects against myocardial injury by alleviating oxidative stress, inflammation, apoptosis, and fibrosis. However, the role of curcumin and its mechanism of action on interstitial fibrosis after myocardial infarction (MI) are poorly understood. To clarify, MI was induced by a permanent ligation of the left anterior descending coronary artery in adult mice, and the effects of curcumin were evaluated 4 weeks after the MI event. In vitro, we treated cardiac fibroblasts (CFs) with Ang II, and investigated the anti-fibrotic mechanism of curcumin. Our results showed that curcumin significantly attenuated collagen deposition in vivo and inhibited CF proliferation and migration, and MMP expression. In addition, we found that the down-regulation of SIRT1 after MI was attenuated by curcumin pretreatment, which indicated that the activation of SIRT1 might be involved in the protective action of curcumin. This hypothesis was confirmed by genetic inhibition of SIRT1 (siRNA-SIRT1) in Ang II-treated CFs. Our results provide new insights into the mechanism underlying the anti-fibrotic effects of curcumin in the heart.

MiR-30a regulates the atrial fibrillation-induced myocardial fibrosis by targeting snail 1

OBJECTIVE

Our study aims at assessing the association between miR-30a along with its target gene snail 1 and atrial fibrillation (AF)-induced myocardial fibrosis.

METHODS

Ang II was used to up-regulate cardiac fibroblasts fibrosis in vitro, and then the cardiac fibroblasts were divided into the mimics group (mimics miR-30a), inhibitors group (inhibitors miR-30a), NC group (transfected miR-30a, negative control) and blank control group (non-transfected cells). Two-group (sham operated group and rapid pacing group) AF rabbit models were constructed according to whether rapid pacing was presented in the subject. Then the establishment of rabbit models was examined using histopathology after Masson staining. The mRNA and protein expression levels of snail 1 and periostin in cardiac fibroblasts and myocardial tissues were detected using the method of RT-PCR and Western blot, respectively.

RESULTS

In vitro, our experiment showed that overexpression of miR-30a in cardiac fibroblasts contribute to a significant decrease in the average expression level of snail 1 and periostin (P < 0.05) whereas inhibition of miR-30a significantly increased the average expression level of snail 1 and periostin (P < 0.05). In vivo, the average expression level of miR-30a significantly decreased in myocardial tissues with an increased degree of myocardial fibrosis, while the snail 1 and periostin expression level significantly increased during a certain period of time (P < 0.05).

CONCLUSION

Our results suggest that miR-30a target snail 1 protein may be related to AF-induced myocardial fibrosis. The average expression levels of snail 1 increased significantly in both myocardial cells and tissues, while miR-30a could inhibit the expression of snail 1. Thus, we speculate that miR-30a and snail 1 may be potential therapeutic targets for curing AF-induced myocardial fibrosis.

Influence of interleukin-1 beta gene polymorphisms on the risk of myocardial infarction and ischemic stroke at young age in vivo and in vitro

In this study, by using vivo and vitro model, we assessed whether interleukin (IL)-1beta gene polymorphisms influence on the risk of myocardial infarction and ischemic stroke at young age. 147 patients (age < 45 years) with a first episode of MI and 56 patients (age < 45 years) with first-ever cerebral ischemia consecutively were admitted to this study from the Department of Chinese PLA General Hospital. Meanwhile, 91 normal volunteers without MI or stroke were deeded as control group and greed to give blood samples for DNA analysis and biochemical measurements by written informed consent. IL-1β-511 wild type (WT, CC) and SNP (TT) were established and transfected into Rat myocardial H9c2 cell and Mouse brain endothelial bEND.3 cells. In Young Age MI or stroke patients, the IL-1β levels of patients with 511CC are higher than that of patients with 511TT. In our study, NF-κB miRNA, iNOS activity, NF-κB, iNOS and Bax protein expressions of MI-induced H9c2 cell or stroke-induced bEND.3 cells in IL-1β-511TT group were lower than those of IL-1β-511CC. Additionally, the protein expression of MMP-2 of MI-induced H9c2 cell or stroke-induced bEND.3 cells in IL-1β-511TT group were higher than that of IL-1β 511CC group. In conclusion, our data indicate that IL-1β-511TT/CC influence on the risk of myocardial infarction and ischemic stroke at young age through NF-κB, iNOS, MMP-2 and Bax.