The TIR/BB-loop mimetic AS-1 prevents cardiac hypertrophy by inhibiting IL-1R-mediated MyD88-dependent signaling

Lutein suppresses ferroptosis of cardiac microvascular endothelial cells via positive regulation of IRF in cardiac hypertrophy

Cardiac microvascular dysfunction contributes to cardiac hypertrophy (CH) and can progress to heart failure. Lutein is a carotenoid with various pharmacological properties, such as anti-apoptotic, anti-inflammatory, and antioxidant effects. Limited research has been conducted on the effects of lutein on pressure overload-induced CH. Studies have shown that CH is accompanied by ferroptosis in the cardiac microvascular endothelial cells (CMECs). This study aimed to investigate the effect of lutein on ferroptosis of CMECs in CH. The transcription factor interferon regulatory factor (IRF) is associated with immune system function, tumor suppression, and apoptosis. The results of this study suggested that pressure overload primarily inhibits IRF expression, resulting in endothelial ferroptosis. Administration of lutein increased the expression of IRF, providing protection to endothelial cells during pressure overload. IRF silencing downregulated solute carrier family 7 member 11 (SLC7A11) and glutathione peroxidase 4 (GPX4) expression, leading to the induction of ferroptosis in CMECs. Lutein supplementation suppressed endothelial ferroptosis by upregulating IRF. These data suggest that IRF may function as a transcription factor for SLC7A11 and that lutein represses ferroptosis in CMECs by upregulating IRF expression. Therefore, targeting IRF may be a promising therapeutic strategy for effective cardioprotection in patients with CH and heart failure.

Design, Synthesis, and Bioevaluation of Novel MyD88 Inhibitor c17 against Acute Lung Injury Derived from the Virtual Screen

Myeloid differentiation primary response protein 88 (MyD88) is crucial to immune cascades mediated by Toll-like receptors (TLRs) and interleukin-1 receptors (IL-1Rs). MyD88 dysregulation has been linked to a wide variety of inflammatory diseases, making it a promising new target for anti-inflammatory and cancer therapy development. In this study, 46 compounds were designed and synthesized inspired by virtual screen hit. The anti-inflammatory activity of designed compounds was evaluated biologically, and c17 was discovered to have a high binding affinity with MyD88. It inhibited the interaction of TLR4 and MyD88 and suppressed the NF-κB pathway. In addition, c17 treatment led to the accumulation in the lungs of rats and attenuated LPS-induced ALI mice model. Furthermore, c17 showed negligible toxicity in vivo. Together, these findings suggest that c17 may serve as a potential therapeutical method for the treatment of ALI and as a lead structure for the continued development of MyD88 inhibitors.

Cardiomyocyte-specific Peli1 contributes to the pressure overload-induced cardiac fibrosis through miR-494-3p-dependent exosomal communication

Cardiac fibrosis is an essential pathological process in pressure overload (PO)-induced heart failure. Recently, myocyte-fibroblast communication is proven to be critical in heart failure, in which, pathological growth of cardiomyocytes (CMs) may promote fibrosis via miRNAs-containing exosomes (Exos). Peli1 regulates the activation of NF-κB and AP-1, which has been demonstrated to engage in miRNA transcription in cardiomyocytes. Therefore, we hypothesized that Peli1 in CMs regulates the activation of cardiac fibroblasts (CFs) through an exosomal miRNA-mediated paracrine mechanism, thereby promoting cardiac fibrosis. We found that CM-conditional deletion of Peli1 improved PO-induced cardiac fibrosis. Moreover, Exos from mechanical stretch (MS)-induced WT CMs (WT MS-Exos) promote activation of CFs, Peli1^-/- MS-Exos reversed it. Furthermore, miRNA microarray and qPCR analysis showed that miR-494-3p was increased in WT MS-Exos while being down regulated in Peli1^-/- MS-Exos. Mechanistically, Peli1 promoted miR-494-3p expression via NF-κB/AP-1 in CMs, and then miR-494-3p induced CFs activation by inhibiting PTEN and amplifying the phosphorylation of AKT, SMAD2/3, and ERK. Collectively, our study suggests that CMs Peli1 contributes to myocardial fibrosis via CMs-derived miR-494-3p-enriched exosomes under PO, and provides a potential exosomal miRNA-based therapy for cardiac fibrosis.

Phillyrin Inhibits Isoproterenol-Induced Cardiac Hypertrophy Via P38 and NF-κB Pathways

Cardiac hypertrophy (CH) is the main compensatory response to chronic heart stress and often progresses to a decompensation state potentially leading to heart failure. Phillyrin (PHI) is a novel compound derived from Forsythia, which has shown anti-inflammatory and anti-virus activities as well as renal protective effects on diabetic nephropathy. Therefore, we investigated the effects of PHI on CH induced by isoproterenol (ISO). Cardiac hypertrophy was induced by ISO in vivo, and the H9C2 cells were treated with ISO. PHI treatment alleviated CH in isoproterenol-induced mice in 7 and 14 days. Echocardiography showed that the PHI improved ISO-induced CH heart function and structure. PHI significantly decreased heart weight/body weight (HW/BW) and heart weight/tibia length (HW/TL) ratios and improved left ventricular (LV) function in ISO-treated mice. Hematoxylin and eosin staining revealed cardiomyocyte areas of the ISO group were significantly increased, and PHI was significantly reduced at 7 and 14 days, PHI-100 groups showed significantly better improvements than PHI-50. Sirius red staining indicated PHI significantly decreased collagen deposition in heart cross-sections induced by ISO, and PHI repressed ISO-induced cTn-I and NT-proBNP expression in mouse serum. In vitro data from H9C2 cells showed that PHI decreased cell areas and total cell protein levels in cells induced by ISO, whereas ANP, BNP, IL-6, and IL-1β expression was significantly inhibited by PHI. Also, PHI simultaneously inhibited P65 and P38 phosphorylation in vivo and in vitro. In conclusion, this study demonstrated the protective effect of PHI on CH in in vivo and in vitro, and this effect was related to the suppression of inflammation through the activation of the P38/NF-κB pathway.

MyD88: At the heart of inflammatory signaling and cardiovascular disease

Cardiovascular disease is a leading cause of death worldwide and is associated with systemic inflammation. In depth study of the cell-specific signaling mechanisms mediating the inflammatory response is vital to improving anti-inflammatory therapies that reduce mortality and morbidity. Cellular damage in the cardiovascular system results in the release of damage associated molecular patterns (DAMPs), also known as "alarmins," which activate myeloid cells through the adaptor protein myeloid differentiation primary response 88 (MyD88). MyD88 is broadly expressed in most cell types of the immune and cardiovascular systems, and its role often differs in a cardiovascular disease context and cell specific manner. Herein we review what is known about MyD88 in the setting of a variety of cardiovascular diseases, discussing cell specific functions and the relative contributions of MyD88-dependent vs. independent alarmin triggered inflammatory signaling. The widespread involvement of these pathways in cardiovascular disease, and their largely unexplored complexity, sets the stage for future in depth mechanistic studies that may place MyD88 in both immune and non-immune cell types as an attractive target for therapeutic intervention in cardiovascular disease.

Protective roles of the TIR/BB-loop mimetic AS-1 in alkali-induced corneal neovascularization by inhibiting ERK phosphorylation

Hydrocinnamoyl-L-valylpyrrolidine (AS-1), a synthetic low-molecule mimetic of myeloid differentiation primary response gene 88 (MyD88), inhibits inflammation by disrupting the interaction between the interleukin-1 receptor (IL-1R) and MyD88. Here, we describe the effects of AS-1 on injury-induced increases in inflammation and neovascularization in mouse corneas. Mice were administered a subconjunctival injection of 8 μL AS-1 diluent before or after corneal alkali burn, followed by evaluation of corneal resurfacing and corneal neovascularization (CNV) by slit-lamp biomicroscopy and clinical assessment. Corneal inflammation was assessed by whole-mount CD45⁺ immunofluorescence staining, and corneal hemangiogenesis and lymphangiogenesis following injury were evaluated by immunostaining for the vascular markers isolectin B4 (IB4) and the lymphatic vascularized marker lymphatic vessel endothelial hyaluronan receptor 1 (LYVE1), respectively. Additionally, corneal tissues were collected to determine the expression of 35 cytokines, and we detected activation of IL-1RI, MyD88, and mitogen-activated protein kinase (MAPK). The results showed that alkali conditions increased the number of CD45⁺ cells and expression of vascular endothelial growth factor (VEGF)-A, VEGF-C, and LYVE1 in corneas, with these levels decreased in the AS-1-treated group. Moreover, AS-1 effectively prevented alkali-induced cytokine production, blocked interactions between IL-1RI and MyD88, and inhibited MAPK activation post-alkali burn. These results indicated that AS-1 prevented alkali-induced corneal hemangiogenesis and lymphangiogenesis by blocking IL-1RI-MyD88 interaction, as well as extracellular signal-regulated kinase phosphorylation, and could be efficacious for the prevention and treatment of corneal alkali burn.

Triad3A attenuates pathological cardiac hypertrophy involving the augmentation of ubiquitination-mediated degradation of TLR4 and TLR9

Activation of TLRs mediated the NF-κB signaling pathway plays an important pathophysiological role in cardiac hypertrophy. Triad3A, a ubiquitin E3 ligase, has been reported to negatively regulate NF-κB activation pathway via promoting ubiquitination and degradation of TLR4 and TLR9 in innate immune cells. The role of Triad3A in cardiac hypertrophic development remains unknown. The present study investigated whether there is a link between Triad3A and TLR4 and TLR9 in pressure overload induced cardiac hypertrophy. We observed that Triad3A levels were markedly reduced following transverse aortic constriction (TAC) induced cardiac hypertrophy. Similarly, stimulation of neonatal rat cardiac myocytes (NRCMs) with angiotensin-II (Ang II) significantly decreased Triad3A expression. To determine the role of Triad3A in TAC-induced cardiac hypertrophy, we transduced the myocardium with adenovirus expressing Triad3A followed by induction of TAC. We observed that increased expression of Triad3A significantly attenuated cardiac hypertrophy and improved cardiac function. To investigate the mechanisms by which Triad3A attenuated cardiac hypertrophy, we examined the Triad3A E3 ubiquitination on TLR4 and TLR9. We found that Triad3A promoted TLR4 and TLR9 degradation through ubiquitination. Triad3A mediated TLR4 and TLR9 degradation resulted in suppression of NF-κB activation. Our data suggest that Triad3A plays a protective role in the development of cardiac hypertrophy, at least through catalyzing ubiquitination-mediated degradation of TLR4 and TLR9, thus negatively regulating NF-κB activation.

The TIR/BB-loop mimetic AS-1 prevents Ang II-induced hypertensive cardiac hypertrophy via NF-κB dependent downregulation of miRNA-143

Untreated pathological cardiac hypertrophy, which can be caused by sustained systemic hypertension, may lead to heart failure. In the present study, we investigated whether AS-1 had attenuating effects on hypertension-induced cardiac hypertrophy, and whether this process was mediated by the regulation of miRNA-143. To induce the hypertrophic response in vitro, cardiomyocytes were stimulated with Ang II for 24hs. AS-1 administration strongly attenuated Ang II-induced hypertrophic response of cardiomyocytes. Chronical infusion of Ang II via implanted osmotic mini-pump induced increased blood pressure and cardiac hypertrophy in vivo. AS-1 administration attenuated hypertension-induced cardiac hypertrophy by, at least in part, inhibin of MAPK signaling. We observed, for the first time, upregulated expression of miRNA-143 in Ang II-induced cardiomyocytes, and inhibition of miRNA-143 significantly reduced the Ang II-induced hypertrophic responses. Importantly, AS-1 administration diminished the Ang II-induced upregulation of miRNA-143. Overexpression of miRNA-143 abolished the attenuating effects of AS-1 on Ang II-induced hypertrophic response of cardiomyocytes. Additionally, AS-1 administration abrogates Ang II-induced nuclear translocation of p50 NF-κB subunit in hypertrophic cardiomyocytes. Application of NF-κB inhibitor significantly suppressed Ang II-induced upregulation of miRNA-143. Our data suggest a novel mechanism by which AS-1 attenuates Ang II-induced hypertrophic response through downregulation miRNA-143 expression in a NF-κB-dependent manner.

Crucial role of RAGE in inappropriate increase of smooth muscle cells from patients with pulmonary arterial hypertension

Background

Pulmonary vascular remodeling of pulmonary arterial hypertension (PAH) is characterized by an inappropriate increase of vascular cells. The receptor for advanced glycation end products (RAGE) is a type I single-pass transmembrane protein belonging to the immunoglobulin superfamily and is involved in a broad range of hyperproliferative diseases. RAGE is also implicated in the etiology of PAH and is overexpressed in pulmonary artery smooth muscle cells (PASMCs) in patients with PAH. We examined the role of RAGE in the inappropriate increase of PASMCs in patients with PAH.

Methods and results

PASMCs were obtained from 12 patients with PAH including 9 patients with idiopathic PAH (IPAH) and 3 patients with heritable PAH (HPAH) (2 patients with BMPR2 mutation and one patient with SMAD9 mutation) who underwent lung transplantation. Western blot analysis and immunofluorescence staining revealed that RAGE and S100A8 and A9, ligands of RAGE, were overexpressed in IPAH and HPAH-PASMCs in the absence of any external growth stimulus. PDGF-BB (10 ng/mL) up-regulated the expression of RAGE in IPAH and HPAH-PASMCs. PAH-PASMCs are hyperplastic in the absence of any external growth stimulus as assessed by 3H-thymidine incorporation. This result indicates overgrowth characterized by continued growth under a condition of no growth stimulation in PAH-PASMCs. PDGF-BB stimulation caused a higher growth rate of PAH-PASMCs than that of non-PAH-PASMCs. AS-1, an inhibitor of TIR domain-mediated RAGE signaling, significantly inhibited overgrowth characterized by continued growth under a condition of no growth stimulation in IPAH and HPAH-PASMCs (P<0.0001). Furthermore, AS-1 significantly inhibited PDGF-stimulated proliferation of IPAH and HPAH-PASMCs (P<0.0001).

Conclusions

RAGE plays a crucial role in the inappropriate increase of PAH-PASMCs. Inhibition of RAGE signaling may be a new therapeutic strategy for PAH.

MyD88 as a therapeutic target for inflammatory lung diseases

INTRODUCTION

Myeloid differentiation primary response protein 88 (MyD88) is a critical adaptor protein involved in Toll-like and IL-1 receptor family signaling controlling innate immune responses and inflammation. Genetic deletion of MyD88 function results in profound suppression of inflammation and reduced resistance of the host to pathogens indicating non-redundant roles of MyD88. The TIR domain is critical for MyD88 dimerization and signaling for TLR and IL-1R family receptor. Areas covered: Emerging evidence suggests that chemical disruption of the TIR domain attenuates cell activation and inhibits in vivo MyD88-dependent inflammation. We review the development of MyD88 dimerization disruptors as a novel therapeutic approach of respiratory diseases with a focus on COPD. Expert opinion: There is a proof of concept that therapeutic targeting of MyD88 is feasible and first preclinical data are highly promising. This opens a great opportunity to treat exacerbations of COPD and other chronic respiratory diseases. However, extensive preclinical investigations and risk analyses are required with carefully evaluation of reduced host resistance and opportunistic infections.

Recent advances of adapter proteins in the regulation of heart diseases

Heart diseases are major causes of mortality. Cardiac hypertrophy, myocardial infarction (MI), viral cardiomyopathy, ischemic and reperfusion (I/R) heart injury finally lead to heart failure and death. Insulin and IGF1 signal pathways play key roles in normal cardiomyocyte growth and physiological cardiac hypertrophy while inflammatory signal pathway is associated with pathological cardiac hypertrophy, MI, viral cardiomyopathy, I/R heart injury, and heart failure. Adapter proteins are the major family proteins, which transduce signals from insulin, IGF1, or cytokine receptors to the downstream pathways and have been shown to regulate variety of heart diseases. Here, we summarized the recent advances in understanding the physiological and pathological roles of adapter proteins in heart failure.

The TIR/BB-loop mimetic AS-1 prevents non-alcoholic steatohepatitis and hepatic insulin resistance by inhibiting NLRP3-ASC inflammasome activation

BACKGROUND AND PURPOSE

Non-alcoholic steatohepatitis (NASH) is characterized by excessive intracellular lipid accumulation, inflammation and hepatic insulin resistance. As the incidence of NASH is increasing worldwide, there is an urgent need to find novel interventional approaches. The pro-inflammatory cytokine IL-1β, generated and released from Kupffer cells, is considered to initiate the development of NASH. AS-1, a synthetic low-molecule mimetic of myeloid differentiation primary response gene 88 (MyD88), disrupts the interaction between the IL-1 receptor and MyD88. Here, we investigated whether AS-1 could attenuate the pathogenesis of NASH with an emphasis on hepatic insulin resistance.

EXPERIMENTAL APPROACH

Eight-week-old db/db mice were fed a control diet or a methionine- and choline-deficient (MCD) diet. AS-1 (50 mg·kg^-1 ) or vehicle was administered i.p.

KEY RESULTS

AS-1 administration significantly ameliorated NASH as evidenced by alanine aminotransferase levels and CD68 levels in livers of MCD-fed mice. AS-1 inhibited the MCD diet-induced activation of caspase 1 and the NLRP3-ASC inflammasome, and also reduced the enhanced levels of ROS, malondialdehyde, 3-nitrotyrosine, NADPH oxidase complex and CYP reductase-associated cytochrome p450 2E1 (CYP2E1) expression in the liver. In addition, AS-1 decreased ROS, inflammasome activation and IL-1β production in free fatty acid-LPS-treated Kupffer cells. Finally, pretreatment with AS-1 significantly ameliorated gluconeogenesis and insulin desensitization induced by IL-1β, probably by blocking the interaction between MyD88 and the IL-1 receptor.

CONCLUSIONS AND IMPLICATIONS

Our results indicate that AS-1 can ameliorate NASH and hepatic insulin resistance and could be considered as a potential strategy for the prevention and treatment of NASH.

TIR/BB-loop mimetic AS-1 attenuates cardiac ischemia/reperfusion injury via a caveolae and caveolin-3-dependent mechanism

AS-1, the TIR/BB loop mimetic, plays a protective role in cardiac ischemia/reperfusion (I/R) but the molecular mechanism remains unclear. The muscle specific caveolin3 (Cav-3) and the caveolae have been found to be critical for cardioprotection. This study aimed to evaluate our hypothesis that caveolae and Cav-3 are essential for AS-1-induced cardioprotection against myocardial I/R injury. To address these issues, we analyzed the involvement of Cav-3 in AS-1 mediated cardioprotection both in vivo and in vitro. We demonstrate that AS-1 administration significantly decreased infarct size, improved cardiac function after myocardial I/R and modulated membrane caveolae and Cav-3 expression in the myocardium. For in vitro studies, AS-1 treatment prevented Cav-3 re-distribution induced by H/R injury. In contrast, disruption of caveolae by MCD treatment or Cav-3 knockdown abolished the protection against H/R-induced myocytes injury by AS-1. Our findings reveal that AS-1 attenuates myocardial I/R injury through caveolae and Cav-3 dependent mechanism.

Asiatic acid inhibits cardiac hypertrophy by blocking interleukin-1β-activated nuclear factor-κB signaling in vitro and in vivo

BACKGROUND

Activated interleukin (IL)-1β signaling pathway is closely associated with pathological cardiac hypertrophy. This study investigated whether asiatic acid (AA) could inhibit IL-1β-related hypertrophic signaling, and thus suppressing the development of cardiac hypertrophy.

METHODS

Transverse aortic constriction (TAC) induced cardiac hypertrophy in C57BL/6 mice and cultured neonatal cardiac myocytes stimulated with IL-1β were used to evaluate the role of AA in cardiac hypertrophy. The expression of atrial natriuretic peptide (ANP) was evaluated by quantitative polymerase chain reaction (qPCR) and the nuclear factor (NF)-κB binding activity was measured by electrophoretic mobility shift assays (EMSA).

RESULTS

AA pretreatment significantly attenuated the IL-1β-induced hypertrophic response of cardiomyocytes as reflected by reduction in the cardiomyocyte surface area and the inhibition of ANP mRNA expression. The protective effect of AA on IL-1β-stimulated cardiomyocytes was associated with the reduction of NF-κB binding activity. In addition, AA prevented TAC-induced cardiac hypertrophy in vivo. It was found that AA markedly reduced the excessive expression of IL-1β and ANP, and inhibited the activation of NF-κB in the hypertrophic myocardium.

CONCLUSIONS

Our data suggest that AA may be a novel therapeutic agent for cardiac hypertrophy. The inhibition of IL-1β-activated NF-κB signaling may be the mechanism through which AA prevents cardiac hypertrophy.

Pellino1-mediated TGF-β1 synthesis contributes to mechanical stress induced cardiac fibroblast activation

Activation of cardiac fibroblasts is a key event in the progression of cardiac fibrosis that leads to heart failure. However, the molecular mechanisms underlying mechanical stress-induced cardiac fibroblast activation are complex and poorly understood. This study demonstrates that Pellino1, an E3 ubiquitin ligase, was activated in vivo in pressure overloaded rat hearts and in cultured neonatal rat cardiac fibroblasts (NRCFs) exposed to mechanical stretch in vitro. Suppression of the expression and activity of Pellino1 by adenovirus-mediated delivery of shPellino1 (adv-shpeli1) attenuated pressure overload-induced cardiac dysfunction and cardiac hypertrophy and decreased cardiac fibrosis in rat hearts. Transfection of adv-shpeli1 also significantly attenuated mechanical stress-induced proliferation, differentiation and collagen synthesis in NRCFs. Pellino1 silencing also abrogated mechanical stretch-induced polyubiquitination of tumor necrosis factor-alpha receptor association factor-6 (TRAF6) and receptor-interacting protein 1 (RIP1) and consequently decreased the DNA binding activity of nuclear factor-kappa B (NF-κB) in NRCFs. In addition, Pellino1 silencing prevented stretch-induced activation of p38 and activator protein 1 (AP-1) binding activity in NRCFs. Chromatin Immunoprecipitation (ChIP) and luciferase reporter assays showed that Pellino1 silencing prevented the binding of NF-κB and AP-1 to the promoter region of transforming growth factor-β1 (TGF-β1) thus dampening TGF-β1 transactivation. Our data reveal a previously unrecognized role of Pellino1 in extracellular matrix deposition and cardiac fibroblast activation in response to mechanical stress and provides a novel target for treatment of cardiac fibrosis and heart failure.

Bortezomib prevents oncogenesis and bone metastasis of prostate cancer by inhibiting WWP1, Smurf1 and Smurf2

Prostate cancer is the most common malignancy diagnosed in males, and bone metastases remain a significant source of morbidity and mortality in this population. Ubiquitin ligase E3s and proteasomes were thought to play essential roles in the development of cancers, therefore, they were proposed as therapy targets for the treatment of solid and hematological malignancies. Bortezomib, well-known as a proteasome inhibitor, has been observed with exact anticancer effect both in cell and animal models for several solid tumor types, including prostate cancer. To explore activities of the ubiquitin ligase E3s WWP1, Smurf1 and Smurf2 in oncogenesis and bone metastasis of prostate cancer, as well as in the functional mechanism of bortezomib in preventing prostate cancer, transcription and expression levels of WWP1, Smurf1 and Smurf2 genes in cell lines or tissues of benign prostate hyperplasia and human prostate cancer with and without bone metastasis were tested. Moreover, human prostate cancer PC3 cell lines were treated with bortezomib at different concentration gradients and then their proliferation at different time points, mRNA and protein levels were investigated. The results indicated that transcription and expression levels of WWP1, Smurf1 and Smurf2 genes in prostate cancer without bone metastasis were significantly higher compared to those in benign prostate hyperplasia (P<0.05), whereas significantly lower than prostate cancer metastatic to bone (P<0.05). Furthermore, bortezomib reduced the transcription and expression levels of WWP1, Smurf1 and Smurf2 genes in prostate cancer cell lines in a dose-dependent manner, thus, inhibiting the proliferation of prostate cancer cells. Elevated transcription and expression levels of ubiquitin ligase E3s WWP1, Smurf1 and Smurf2 genes may be the mechanisms of occurrence, development and metastasis of prostate cancer. In addition, bortezomib can prevent prostate cancer and its bone metastasis by downregulating WWP1, Smurf1 and Smurf2.

Asiatic acid attenuates cardiac hypertrophy by blocking transforming growth factor-β1-mediated hypertrophic signaling in vitro and in vivo

Cardiac hypertrophy is a major cause of morbidity and mortality worldwide. Transforming growth factor-β1 (TGF-β1) signaling has been considered as a trigger causally contributing to pathological cardiac hypertrophy. Asiatic acid (AA) is a triterpenoid compound extracted from Centella asiatica and exhibits a variety of pharmacological effects. In this study, we investigated the anti-hypertrophic effects and mechanisms of action of AA in a TGF-β1-stimulated hypertrophic response using cultured neonatal cardiomyocytes in vitro and in a mouse model of cardiac hypertrophy induced by pressure overload in vivo. Treatment with AA markedly attenuated the TGF-β1-induced hypertrophic responses of cardiomyocytes as reflected by reduction in the cardiomyocyte surface area and the inhibition of atrial natriuretic peptide (ANP) mRNA expression. The protective effects of AA on hypertrophic cardiomyocytes were associated with the blocking of p38 and extracellular signal‑regulated kinase (ERK)1/2 phosphorylation and the reduction of nuclear factor-κB (NF-κB) binding activity. In vivo experiments indicated that the administration of AA prevented cardiac hypertrophy and dysfunction induced by pressure overload. It was found that AA markedly reduced the excessive production of TGF-β1 in the hypertrophic myocardium, blocked the phosphorylation of p38 and ERK1/2 and inhibited the activation of NF-κB. Our data suggest that AA may be a novel therapeutic agent for cardiac hypertrophy. The inhibition of TGF-β1‑mediated hypertrophic signaling may be the mechanism through which AA prevents cardiac hypertrophy.

The ginsenoside Rg1 prevents transverse aortic constriction-induced left ventricular hypertrophy and cardiac dysfunction by inhibiting fibrosis and enhancing angiogenesis

BACKGROUND

Ginsenoside Rg1, an important and active ingredient of Panax ginseng, has been shown to exert cardioprotective effects in vivo. The present study aimed to test the hypothesis that ginsenoside Rg1 attenuates cardiac dysfunction in a transverse aortic constriction (TAC)-induced left ventricular hypertrophy in vivo via proangiogenic and antifibrotic effects.

METHODS

This study investigated the effects of ginsenoside Rg1 in a rat model of TAC-induced left ventricular hypertrophy. Cardiac function was assessed by echocardiography. The antifibrotic and proangiogenic effects were assessed by histopathology and mRNA expression of procollagen I, III, and vascular endothelial growth factor (VEGF) through quantitative real-time PCR. The expression of phosphorylation of Akt, p38 mitogen-activated protein kinase (MAPK), hypoxia inducible factor-1 (HIF-1), and VEGF proteins were examined by Western blotting.

RESULTS

Ginsenoside Rg1 treatment significantly decreased TAC-induced myocardial fibrosis and left ventricular hypertrophy, and preserved cardiac function. Ginsenoside Rg1 administration enhanced angiogenesis by increasing the expression of HIF-1 and VEGF. These cardioprotective effects of ginsenoside Rg1 are partially related to the activation of phospho-Akt and inhibition of p38 MAPK.

CONCLUSIONS

Ginsenoside Rg1 exhibited protective effect against TAC-induced left ventricular hypertrophy and cardiac dysfunction, which is potentially associated with phospho-Akt activation and p38 MAPK inhibition.

Vinexin-β protects against cardiac hypertrophy by blocking the Akt-dependent signalling pathway

Cardiac hypertrophy is the heart's response to hypertrophic stimuli and is associated with increased mortality. Vinexin-β is a vinculin-binding protein that belongs to a family of adaptor proteins and mediates signal transduction and actin cytoskeleton organisation. A previous study has shown that Vinexin-β is ubiquitously expressed and that it is highly expressed in the heart. However, a critical role for Vinexin-β in cardiac hypertrophy has not been investigated. Therefore, to examine the role of Vinexin-β in pathological cardiac hypertrophy, we used Vinexin-β knockout mice and transgenic mice that overexpress human Vinexin-β in the heart. Cardiac hypertrophy was induced by aortic banding (AB). The extent of cardiac hypertrophy was quantitated by echocardiography and pathological and molecular analyses of heart samples. Our results demonstrated that Vinexin-β overexpression in the heart markedly attenuated cardiac hypertrophy, fibrosis, and cardiac dysfunction, whereas loss of Vinexin-β exaggerated the pathological cardiac remodelling and fibrosis response to pressure overload. Further analysis of the in vitro and in vivo signalling events indicated that beneficial Vinexin-β effects were associated with AKT signalling abrogation. Our findings demonstrate for the first time that Vinexin-β is a novel mediator that protects against cardiac hypertrophy by blocking the AKT signalling pathway.

Deletion of Fn14 receptor protects from right heart fibrosis and dysfunction

Pulmonary arterial hypertension (PAH) is a fatal disease for which no cure is yet available. The leading cause of death in PAH is right ventricular (RV) failure. Previously, the TNF receptor superfamily member fibroblast growth factor-inducible molecule 14 (Fn14) has been associated with different fibrotic diseases. However, so far there is no study demonstrating a causal role for endogenous Fn14 signaling in RV or LV heart disease. The purpose of this study was to determine whether global ablation of Fn14 prevents RV fibrosis and remodeling improving heart function. Here, we provide evidence for a causative role of Fn14 in pulmonary artery banding (PAB)-induced RV fibrosis and dysfunction in mice. Fn14 expression was increased in the RV after PAB. Mice lacking Fn14 (Fn14^−/−) displayed substantially reduced RV fibrosis and dysfunction following PAB compared to wild-type littermates. Cell culture experiments demonstrated that activation of Fn14 induces collagen expression via RhoA-dependent nuclear translocation of myocardin-related transcription factor-A (MRTF-A)/MAL. Furthermore, activation of Fn14 in vitro caused fibroblast proliferation and myofibroblast differentiation, which corresponds to suppression of PAB-induced RV fibrosis in Fn14^−/− mice. Moreover, our findings suggest that Fn14 expression is regulated by endothelin-1 (ET-1) in cardiac fibroblasts. We conclude that Fn14 is an endogenous key regulator in cardiac fibrosis and suggest this receptor as potential new target for therapeutic interventions in heart failure.

Interferon regulatory factor 3 is a negative regulator of pathological cardiac hypertrophy

Interferon regulatory factor (IRF) 3, a member of the highly conserved IRF family transcription factors, plays a pivotal role in innate immune response, apoptosis, and oncogenesis. Recent studies have implicated IRF3 in a wide range of host defense. However, whether IRF3 induces defensive responses to hypertrophic stresses such as biomechanical stress and neurohumoral factors remains unclear. Herein, we employed an IRF3-deficient mouse model, cardiac-specific IRF3-overexpression mouse model and isolated cardiomyocytes to investigate the role of IRF3 in cardiac hypertrophy induced by aortic banding (AB) or isoproterenol (ISO). The extent of cardiac hypertrophy was quantitated by echocardiography as well as by pathological and molecular analysis. Our results demonstrate that IRF3 deficiency profoundly exacerbated cardiac hypertrophy, whereas overexpression of IRF3 in the heart significantly blunted pathological cardiac remodeling induced by pressure overload. Similar results were also observed in cultured cardiomyocytes upon the treatment with ISO. Mechanistically, we discovered that IRF3 interacted with ERK2 and thereby inhibited the ERK1/2 signaling. Furthermore, inactivation of ERK1/2 by U0126 offset the IRF3-deficient-mediated hypertrophic response induced by aortic banding. Altogether, these data demonstrate that IRF3 plays a protective role in AB-induced hypertrophic response by inactivating ERK1/2 in the heart. Therefore, IRF3 could be a new target for the prevention and therapy of cardiac hypertrophy and failure.