Calcium Sensing Receptor-Related Pathway Contributes to Cardiac Injury and the Mechanism of Astragaloside IV on Cardioprotection

Astragaloside IV mitigates hypoxia-induced cardiac hypertrophy through calpain-1-mediated mTOR activation

BACKGROUND

Astragaloside IV (AsIV), a key functioning element of Astragalus membranaceus, has been recognized for its potential cardiovascular protective properties. However, there is a need to elucidate the impacts of AsIV on myocardial hypertrophy under hypoxia conditions and its root mechanisms.

PURPOSE

This study scrutinized the influence of AsIV on cardiac injury under hypoxia, with particular emphasis on the role of calpain-1 (CAPN1) in mediating mTOR pathways.

METHODS

Hypoxia-triggered cardiac hypertrophy was examined in vivo with CAPN1 knockout and wild-type C57BL/6 mice and in vitro with H9C2 cells. The impacts of AsIV, 3-methyladenine, and CAPN1 inhibition on hypertrophy, autophagy, apoptosis, [Ca2+]i, and CAPN1 and mTOR levels in cardiac tissues and H9C2 cells were investigated.

RESULTS

Both AsIV treatment and CAPN1 knockout mitigated hypoxia-induced cardiac hypertrophy, autophagy, and apoptosis in mice and H9C2 cells. Moreover, AsIV, 3-methyladenine, and CAPN1 inhibition augmented p-mTOR level but reduced [Ca2+]i and CAPN1 level. Additionally, lentivirus-mediated CAPN1 overexpression in H9C2 cells exacerbated myocardial hypertrophy, apoptosis, and p-mTOR inhibition under hypoxia. Specifically, AsIV treatment reversed the impacts of increased CAPN1 expression on cardiac injury and the inhibition of p-mTOR.

CONCLUSION

These findings suggest that AsIV may alleviate cardiac hypertrophy under hypoxia by attenuating apoptosis and autophagy through CAPN1-mediated mTOR activation.

Solid-phase extraction with the functionalization of calcium-sensing receptors onto magnetic microspheres as an affinity probe can capture ligands selectively from herbal extract

Magnetic solid phase extraction with the functionalization of protein onto micro- or nano-particles as a probe is favorable for the discovery of new drugs from complicated natural products. Herein, we aimed to develop a rapid method by immobilizing halogenated alkane dehalogenase (Halo)-tagged calcium-sensing receptor (CaSR) directly out of crude cell lysates onto the surface of magnetic microspheres (MM) with no need to purify protein. Thereby we achieved CaSR-functionalized MM for revealing adsorption characteristics of agonist neomycin and screening ligands from herbal medicine Radix Astragali (RA). About 43.87 mg CaSR could be immobilized per 1 g MM within 30 min, and the acquired CaSR-functionalized MM showed good stability and activity for 4 weeks. The maximum adsorption capacity of neomycin on CaSR-functionalized MM was determined as 4.70 × 10-4 ~ 3.96 × 10-4 mol/g within 277 ~ 310 K, and its adsorption isotherm characteristics described best by the Temkin model were further validated using isothermal titration calorimetry. It was inferred that CaSR's affinity for neomycin was driven by electrostatic forces in a spontaneous process when the system reached an equilibrium state. Moreover, the ligands from the RA extract were screened, three of which were assigned as astragaloside IV, ononin, and calycosin based on HPLC-MS. Our findings demonstrated that the functionalization of a receptor onto magnetic materials designed as an affinity probe has the capability to recognize its agonist and capture the ligands selectively from complex matrices like herbs.

Recent pharmacological advances in the treatment of cardiovascular events with Astragaloside IV

Cardiovascular disease (CVD) remains the leading cause of death and disability globally. A wide range of CVDs have been reported, each of which diverges significantly, exhibiting sophisticated types of pathogenesis (e.g., inflammatory, oxidative stress, and disorders in cardiomyocyte metabolism). Compared with conventional treatments in modern medicine, traditional Chinese medicine (TCM) can exhibit comparative advantages in the treatment of CVDs. TCM can be utilized to develop effective strategies for addressing the challenges of CVD, with fewer side effects and higher therapeutic efficiency. Astragaloside IV (AS-IV) has been confirmed as one of the major active ingredients found in Astragalus membranaceus (a Chinese herbal medicine that has been extensively employed clinically for the treatments of CVDs). Since recent studies have shown that AS-IV in CVD treatments has achieved promising results, the substance has aroused great attention and further discussions in the field. The present review aims to summarize the recent pharmacological advances in employing AS-IV in the treatment of CVDs.

Review on the protective mechanism of astragaloside IV against cardiovascular diseases

Cardiovascular disease is a global health problem. Astragaloside IV (AS-IV) is a saponin compound extracted from the roots of the Chinese herb Astragalus. Over the past few decades, AS-IV has been shown to possess various pharmacological properties. It can protect the myocardium through antioxidative stress, anti-inflammatory effects, regulation of calcium homeostasis, improvement of myocardial energy metabolism, anti-apoptosis, anti-cardiomyocyte hypertrophy, anti-myocardial fibrosis, regulation of myocardial autophagy, and improvement of myocardial microcirculation. AS-IV exerts protective effects on blood vessels. For example, it can protect vascular endothelial cells through antioxidative stress and anti-inflammatory pathways, relax blood vessels, stabilize atherosclerotic plaques, and inhibit the proliferation and migration of vascular smooth muscle cells. Thus, the bioavailability of AS-IV is low. Toxicology indicates that AS-IV is safe, but should be used cautiously in pregnant women. In this paper, we review the mechanisms of AS-IV prevention and treatment of cardiovascular diseases in recent years to provide a reference for future research and drug development.

Astragaloside IV improves pulmonary arterial hypertension by increasing the expression of CCN1 and activating the ERK1/2 pathway

The aim of the present study was to investigate the underlying mechanism of AS-IV and CCN1 in PAH and to evaluate whether the protective effect of AS-IV against PAH is associated with CCN1 and its related signalling pathway. In vivo, male SD rats were intraperitoneally injected with monocrotaline (MCT, 60 mg/kg) or exposed to hypoxia (10% oxygen) and gavaged with AS-IV (20, 40 and 80 mg/kg/day) to create a PAH model. In vitro, human pulmonary artery endothelial cells (hPAECs) were exposed to hypoxia (3% oxygen) or monocrotaline pyrrole (MCTP, 60 μg/mL) and treated with AS-IV (10, 20 and 40 μM), EGF (10 nM, ERK agonist), small interfering CCN1 (CCN1 siRNA) and recombinant CCN1 protein (rCCN1, 100 ng/mL). We identified the differences in the expression of genes in the lung tissues of PAH rats by proteomics. At the same time, we dynamically detected the expression of CCN1 by Western blot both in vivo and in vitro. The Western blot experimental results showed that the expression of CCN1 increased in the early stage of PAH and decreased in the advanced stage of PAH. The results showed that compared with the control group, MCT- and hypoxia-induced increased the hemodynamic parameters and apoptosis. AS-IV can improve PAH, as characterized by decreased hemodynamic parameters, vascular wall area ratio (WA%), vascular wall thickness ratio (WT%) and α-SMA expression and inhibition of cell apoptosis. Moreover, the improvement of PAH by AS-IV was accompanied by increased CCN1 expression, which activated the ERK1/2 signalling pathway. Meanwhile, CCN1 and p-ERK1/2 were inhibited by siCCN1 and promoted by rCCN1. EGF not only activated the ERK1/2 signalling pathway but also induced the expression of CCN1. In conclusion, AS-IV improves PAH by increasing the expression of CCN1 and activating the ERK1/2 signalling pathway. The results of our study provide a theoretical basis for additional study on the protective effect of AS-IV against PAH.

Calcium-Sensing Receptor (CaSR)-Mediated Intracellular Communication in Cardiovascular Diseases

The calcium-sensing receptor (CaSR), a G-protein-coupled receptor (GPCR), is a cell-surface-located receptor that can induce highly diffusible messengers (IP3, Ca²⁺, cAMP) in the cytoplasm to activate various cellular responses. Recently, it has also been suggested that the CaSR mediates the intracellular communications between the endoplasmic reticulum (ER), mitochondria, nucleus, protease/proteasome, and autophagy-lysosome, which are involved in related cardiovascular diseases. The complex intracellular signaling of this receptor challenges it as a valuable therapeutic target. It is, therefore, necessary to understand the mechanisms behind the signaling characteristics of this receptor in intracellular communication. This review provides an overview of the recent research progress on the various regulatory mechanisms of the CaSR in related cardiovascular diseases and the heart-kidney interaction; the associated common causes are also discussed.

Role of Calcimimetics in Treating Bone and Mineral Disorders Related to Chronic Kidney Disease

Renal osteodystrophy is common in patients with chronic kidney disease and end-stage renal disease and leads to the risks of fracture and extraosseous vascular calcification. Secondary hyperparathyroidism (SHPT) is characterized by a compensatory increase in parathyroid hormone (PTH) secretion in response to decreased renal phosphate excretion, resulting in potentiating bone resorption and decreased bone quantity and quality. Calcium-sensing receptors (CaSRs) are group C G-proteins and negatively regulate the parathyroid glands through (1) increasing CaSR insertion within the plasma membrane, (2) increasing 1,25-dihydroxy vitamin D3 within the kidney and parathyroid glands, (3) inhibiting fibroblast growth factor 23 (FGF23) in osteocytes, and (4) attenuating intestinal calcium absorption through Transient Receptor Potential Vanilloid subfamily member 6 (TRPV6). Calcimimetics (CaMs) decrease PTH concentrations without elevating the serum calcium levels or extraosseous calcification through direct interaction with cell membrane CaSRs. CaMs reduce osteoclast activity by reducing stress-induced oxidative autophagy and improving Wnt-10b release, which promotes the growth of osteoblasts and subsequent mineralization. CaMs also directly promote osteoblast proliferation and survival. Consequently, bone quality may improve due to decreased bone resorption and improved bone formation. CaMs modulate cardiovascular fibrosis, calcification, and renal fibrosis through different mechanisms. Therefore, CaMs assist in treating SHPT. This narrative review focuses on the role of CaMs in renal osteodystrophy, including their mechanisms and clinical efficacy.

Pathological role of the calcium-sensing receptor in sepsis-induced hypotensive shock: Therapeutic possibilities and unanswered questions

Sepsis is a life-threatening disease involving multiorgan dysfunction, prompted by an unregulated host response to infection. Shock is a complication of sepsis in which the circulatory and cellular metabolism anomalies are significant enough to raise the risk of death. Calcium dyshomeostasis occurs during sepsis condition due to imbalance between calcium uptake and excessive release induced by inflammatory cytokines. This calcium imbalance can cause activation of calcium-sensing receptors (CaSRs) located on the surface of T cells and thereby promote release of reactive oxygen species (ROS). The elevated ROS and inflammatory cytokines during sepsis condition have been reported to directly damage the endothelial cells, disrupt the barrier functions that might result in leakage of fluids, and inflammatory cells in tissues Moreover, several evidence have revealed that the calcium mediated activation of CaSR could produce systemic vasodilatory response by stimulating the nitric oxide production and opening of calcium-activated potassium channels, while infusion of its antagonist elevated the blood pressure. These evidence indicate that activation of CaSR during sepsis conditions results in release of ROS and inflammatory cytokines, which could produce an endothelial barrier damage, cardiomyocyte apoptosis. These pathological events could produce loss of fluid in tissues and cardiac dysfunction. Further the direct vasodilatory effects of CaSR activation might add to the shock-like condition. Thus, we hereby propose that inhibition of CaSR could suppress the release of ROS, inflammatory mediators, and thereby prevent the endothelial damage, cardiac dysfunction, and maintain systemic vascular tone.

Revisiting the concept of incretin and enteroendocrine L-cells as type 2 diabetes mellitus treatment

The significant growth in type 2 diabetes mellitus (T2DM) prevalence strikes a common threat to the healthcare and economic systems globally. Despite the availability of several anti-hyperglycaemic agents in the market, none can offer T2DM remission. These agents include the prominent incretin-based therapy such as glucagon-like peptide-1 receptor (GLP-1R) agonists and dipeptidyl peptidase-4 inhibitors that are designed primarily to promote GLP-1R activation. Recent interest in various therapeutically useful gastrointestinal hormones in T2DM and obesity has surged with the realisation that enteroendocrine L-cells modulate the different incretins secretion and glucose homeostasis, reflecting the original incretin definition. Targeting L-cells offers promising opportunities to mimic the benefits of bariatric surgery on glucose homeostasis, bodyweight management, and T2DM remission. Revising the fundamental incretin theory is an essential step for therapeutic development in this area. Therefore, the present review explores enteroendocrine L-cell hormone expression, the associated nutrient-sensing mechanisms, and other physiological characteristics. Subsequently, enteroendocrine L-cell line models and the latest L-cell targeted therapies are reviewed critically in this paper. Bariatric surgery, pharmacotherapy and new paradigm of L-cell targeted pharmaceutical formulation are discussed here, offering both clinician and scientist communities a new common interest to push the scientific boundary in T2DM therapy.

Astragaloside IV Ameliorates Isoprenaline-Induced Cardiac Fibrosis in Mice via Modulating Gut Microbiota and Fecal Metabolites

Aim

Gut microbiota is of crucial importance to cardiac health. Astragaloside IV (AS-IV) is a main active ingredient of Huangqi, a traditional edible and medicinal herb that has been shown to have beneficial effects on cardiac fibrosis (CF). However, it is still uncertain whether the consumption of AS-IV alleviates cardiac fibrosis through the gut microbiota and its metabolites. Therefore, we assessed whether the anti-fibrosis effect of AS-IV is associated with changes in intestinal microbiota and fecal metabolites and if so, whether some specific gut microbes are conducive to the benefits of AS-IV.

Methods

Male C57BL-6J mice were subcutaneously injected with isoprenaline (ISO) to induce cardiac fibrosis. AS-IV was administered to mice by gavage for 14 days. The effects of AS-IV on cardiac function, myocardial enzyme, cardiac weight index (CWI), and histopathology of ISO-induced CF mice were investigated. Moreover, 16S rRNA sequencing was used to establish gut-microbiota profiles. Fecal-metabolites profiles were established using the liquid chromatograph-mass spectrometry (LC-MS).

Results

AS-IV treatment prevented cardiac dysfunction, ameliorated myocardial damage, histopathological changes, and cardiac fibrosis induced by ISO. AS-IV consumption increased the richness of Akkermansia, Defluviitaleaceae_UCG-011, and Rikenella. AS-IV also modulated gut metabolites in their feces. Among 141 altered gut metabolites, amino acid production was sharply changed. Furthermore, noticeable correlations were found between several specific gut microbes and altered fecal metabolites.

Conclusions

An increase of Akkermansia, Defluviitaleaceae_UCG-011, and Rikenella abundance, and modulation of amino acid metabolism, may contribute to the anti-fibrosis and cardiac protective effects of Astragaloside IV.

Biological active ingredients of Astragali Radix and its mechanisms in treating cardiovascular and cerebrovascular diseases

BACKGROUND

With the rising age of the global population, the incidence rate of cardiovascular and cerebrovascular diseases (CCVDs) is increasing, which causes serious public health burden. The efforts for new therapeutic approaches are still being sought since the treatment effects of existing therapies are not quite satisfactory. Chinese traditional medicine proved to be very efficient in the treatment of CCVDs. Well described and established in Chinese medicine, Astragali Radix, has been commonly administered in the prophylaxis and cure of CCVDs for thousands of years.

PURPOSE

This review summarized the action mode and mechanisms of Astragali Radix phytochemicals on CCVDs, hoping to provide valuable information for the future application, development and improvement of Astragali Radix as well as CCVDs treatment.

METHODS

A plenty of literature on biological active ingredients of Astragali Radix used for CCVDs treatment were retrieved from online electronic PubMed and Web of Science databases.

RESULTS

This review highlighted the effects of five main active components in Astragali Radix including astragaloside Ⅳ, cycloastragenol, astragalus polysaccharide, calycosin-7-O-β-d-glucoside, and calycosin on CCVDs. The mechanisms mainly involved anti-oxidative damage, anti-inflammatory, and antiapoptotic through signaling pathways such as PI3K/Akt, Nrf2/HO-1, and TLR4/NF-κB pathway. In addition, the majority active constituents in AR have no obvious toxic side effects.

CONCLUSION

The main active components of Astragali Radix, especially AS-IV, have been extensively summarized. It has been proved that Astragali Radix has obvious therapeutic effects on various CCVDs, including myocardial and cerebral ischemia, hypertension, atherosclerosis, cardiac hypertrophy, chronic heart failure. CAG possesses anti-ischemia activity without toxicity, indicating a worthy of further development. However, high-quality clinical and pharmacokinetic studies are required to validate the current studies.

Inhibition of miRNA-1-Mediated Inflammation and Autophagy by Astragaloside IV Improves Lipopolysaccharide-Induced Cardiac Dysfunction in Rats

Introduction

Astragaloside IV (AS-IV) is one of the main active components isolated from the traditional Chinese medicinal herb, Astragalus membranaceus. The present study was designed to investigate whether the regulation of microRNA-1 (miR-1)-mediated inflammation and autophagy contributes to the protective effect of AS-IV against cardiac dysfunction in rats treated with lipopolysaccharides (LPS).

Methods

Animal model of cardiac dysfunction in rats or cellular model of injured H9c2 heart cell line was established by using LPS. Echocardiography, electron microscopy, enzyme-linked immunosorbent assay, immunofluorescence, quantitative RT-PCR, and Western blotting were used to determine the cardiac function and expression of inflammation- and autophagy-related proteins at both the mRNA and protein levels.

Results

LPS caused cardiac dysfunction in rats or injury in H9c2 cells and induced inflammation and autophagy. Compared with LPS treatment, AS-IV treatment attenuated cardiac dysfunction or cell injury, accompanied by inhibition of inflammation and autophagy. However, the miR-1 mimics partly abolished the effects of AS-IV. In addition, the effect of the miR-1 inhibitor was similar to that of AS-IV in the LPS model. Further analyses showed that AS-IV treatment decreased the mRNA expression of miR-1 in the heart tissue of rats and H9c2 cells treated with LPS.

Conclusion

These results suggest that AS-IV attenuated cardiac dysfunction caused by LPS by inhibiting miR-1-mediated inflammation and autophagy, thereby providing a novel mechanism for the protection against cardiac diseases.

Leu27 IGF-II-induced hypertrophy in H9c2 cardiomyoblasts is ameliorated by saffron by regulation of calcineurin/NFAT and CaMKIIδ signaling

The insulin-like growth factor II receptor (IGF-IIR) induces myocardial hypertrophy under various pathological conditions like diabetes and hypertension via G protein receptors like Gαq or Gαs. Increased expression of the ligand IGF II and IGF-IIR induces pathological hypertrophy through downstream signaling mediators such as calcineurin, nuclear factor of activated T cells 3 and calcium-calmodulin (CaM)-dependent kinase II (CaMKII)-histone deacetylase 4 (HDAC4). The dried stigma of Crocus sativus L. (saffron) has a long repute as a traditional medicine against various disorders. In the present study, we have investigated whether C. sativus extract (CSE) canameliorate Leu²⁷ IGF-II triggered hypertrophy and have elucidated the underlying mechanism of protection. Additionally, the effects of oleic acid (OA), an activator of calcineurin and CaMKII was investigated thereof. The results demonstrate that CSE can ameliorate Leu²⁷ IGF-II-induced hypertrophy seemingly through regulation of calcineurin-NFAT3 and CaMKII-HDAC4 signaling cascade.

Ginsenoside Rg1 attenuates mechanical stress-induced cardiac injury via calcium sensing receptor-related pathway

Background

Ginsenoside Rg1 (Rg1) has been well documented to be effective against various cardiovascular disease. The aim of this study is to evaluate the effect of Rg1 on mechanical stress-induced cardiac injury and its possible mechanism with a focus on the calcium sensing receptor (CaSR) signaling pathway.

Methods

Mechanical stress was implemented on rats through abdominal aortic constriction (AAC) procedure and on cardiomyocytes and cardiac fibroblasts by mechanical stretching with Bioflex Collagen I plates. The effects of Rg1 on cell hypertrophy, fibrosis, cardiac function, [Ca²⁺]_i, and the expression of CaSR and calcineurin (CaN) were assayed both on rat and cellular level.

Results

Rg1 alleviated cardiac hypertrophy and fibrosis, and improved cardiac decompensation induced by AAC in rat myocardial tissue and cultured cardiomyocytes and cardiac fibroblasts. Importantly, Rg1 treatment inhibited CaSR expression and increase of [Ca²⁺]_i, which similar to the CaSR inhibitor NPS2143. In addition, Rg1 treatment inhibited CaN and TGF-β1 pathways activation. Mechanistic analysis showed that the CaSR agonist GdCl₃ could not further increase the [Ca²⁺]_i and CaN pathway related protein expression induced by mechanical stretching in cultured cardiomyocytes. CsA, an inhibitor of CaN, inhibited cardiac hypertrophy, cardiac fibrosis, [Ca²⁺]_i and CaN signaling but had no effect on CaSR expression.

Conclusion

The activation of CaN pathway and the increase of [Ca²⁺]_i mediated by CaSR are involved in cardiac hypertrophy and fibrosis, that may be the target of cardioprotection of Rg1 against myocardial injury.

Astragaloside IV Inhibits Bleomycin-Induced Ferroptosis in Human Umbilical Vein Endothelial Cells by Mediating LPC

Ferroptosis, as an iron-dependent programmed cell death pathway, can induce a variety of cardiovascular diseases. Astragaloside IV (AS-IV), which is purified from Astragalus membranaceus, can protect endothelial function and promote vascular regeneration. However, the role played by AS-IV in ferroptosis remains unknown. In this study, the lipid metabolomics in HUVECs treated with/without bleomycin and/or AS-IV were explored using LC/MS. The most differential metabolite between groups was further identified via GO and pathway enrichment analyses. The effects of lysophosphatidylcholine (LPC), AS-IV, and FIN56 on cell viability were explored using the CCK-8 assay, their effects on cell senescence were examined by β-galactosidase staining, and their effects on ferroptosis were detected by a flow cytometric analysis of lipid ROS levels, transmission electron microscopy, and an assay for cellular iron levels. The related mechanisms were investigated by real-time PCR and Western blot assays. Our results showed that LPC, as the most differential metabolite, inhibited cell viability but promoted cell apoptosis and senescence as its concentration increased. Also, the decreased cell activity, increased iron ion and lipid ROS levels, and the enhanced cell senescence induced by LPC treatment were all significantly reversed by AS-IV but further enhanced by FIN56 treatment. The changes in mitochondrial morphology caused by the LPC treatment were significantly alleviated by the AS-IV treatment, while treatment with FIN56 reversed those phenomena. Moreover, AS-IV partially upregulated the levels of SLC7A11 and GPX4 expression which were reduced by LPC. However, those changes were prevented by FIN56 treatment. In conclusion, our data suggested that AS-IV could serve as a novel drug for treating ferroptosis-related diseases.

MiR-135a Protects against Myocardial Injury by Targeting TLR4

Emerging evidence highlights the importance of microRNAs (miRNAs) as functional regulators in cardiovascular disease. This study aimed to investigate the functional significance of miR-135a in the regulation of cardiac injury after isoprenaline (ISO) stimulation and the underlying mechanisms of its effects. Murine models with cardiac-specific overexpression of miR-135a were constructed with an adeno-associated virus expression system. The cardiac injury model was induced by ISO injection (60 mg/kg per day for 14 d). In vitro, we used H9c2 cells to establish a cell injury model by ISO stimulation (10 µM). The results indicated that miR-135a was increased during days 0-6 of ISO injection and was then downregulated during days 8-14 of ISO injection. The expression of miR-135a was consistent with the in vivo findings. Moreover, mice with cardiac overexpression of miR-135a exhibited reduced cardiac fibrosis, lactate dehydrogenase levels, Troponin I, inflammatory response and apoptosis. Overexpression of miR-135a also ameliorated cardiac dysfunction induced by ISO. MiR-135 overexpression in H9c2 cells increased cell viability and decreased cell apoptosis and inflammation in response to ISO. Conversely, miR-135 silencing in H9c2 cells decreased cell viability and increased cell apoptosis and inflammation in response to ISO. Mechanistically, we found that miR-135a negatively regulated toll-like receptor 4 (TLR4), which was confirmed by luciferase assay. Furthermore, the TLR4 inhibitor eritoran abolished the adverse effect of miR-135 silencing. Overall, miR-135a promotes ISO-induced cardiac injury by inhibiting the TLR4 pathway. MiR-135a may be a therapeutic agent for cardiac injury.

Astragaloside IV prevents acute myocardial infarction by inhibiting the TLR4/MyD88/NF-κB signaling pathway

Although astragaloside IV protects from acute myocardial infarction (AMI)-induced chronic heart failure (CHF), the underlying mechanism of action is unclear. We determined the potential therapeutic effect of astragaloside IV using molecular docking approaches and validated the findings by the ligation of the left anterior descending (LAD) coronary artery-induced AMI rat model. The interaction between astragaloside IV and myeloid differentiation factor 88 (MyD88) was evaluated by SwissDock. To explore the mechanisms underlying the beneficial effects of astragaloside IV in the LAD coronary artery ligation-induced AMI model, we administered the rats with astragaloside IV for 4 weeks. Hemodynamic indexes were used to evaluate the degree of myocardial injury in model rats. The histopathological changes in myocardium were detected by hematoxylin & eosin (H&E) staining and Masson's staining. Myocardium homogenate contents of collagen I and collagen III were evaluated by ELISA. The level of myocardial hydroxyproline (HYP) was determined by alkaline hydrolysis. Immunohistochemistry was used to examine collagen I. Western blotting was used to examine relevant proteins. As per the molecular docking study results, astragaloside IV may act on MyD88. Furthermore, astragaloside IV improved hemodynamic disorders, alleviated pathological changes, and reduced abnormal collagen deposition and myocardial HYP in vivo. Astragaloside IV significantly reduced the overexpression of TLR4, MyD88, NF-Κb, and TGF-β, which further validated the molecular docking findings. Hence, astragaloside IV ameliorates AMI by reducing inflammation and blocking TLR4/MyD88/NF-κB signaling. These results indicate that astragaloside IV may alleviate AMI. PRACTICAL APPLICATIONS: Astragaloside IV, a small active substance extracted from Astragalus membranaceus, has demonstrated potent protective effects against cardiovascular ischemia/reperfusion, diabetic nephropathy, and other diseases. Molecular docking experiments showed that astragaloside IV might act on the myeloid differentiation factor 88 (MyD88). Astragaloside IV can effectively reduce the overexpression of TLR4, MyD88, and NF-κB p65, indicating that astragaloside IV inhibits inflammation via TLR4/MyD88/NF-κB signaling pathway. These results indicate that astragaloside IV may alleviate acute myocardial infarction.

Calcium-Sensing Receptor (CaSR), Its Impact on Inflammation and the Consequences on Cardiovascular Health

The calcium Sensing Receptor (CaSR) is a cell surface receptor belonging to the family of G-protein coupled receptors. CaSR is mainly expressed by parathyroid glands, kidneys, bone, skin, adipose tissue, the gut, the nervous system, and the cardiovascular system. The receptor, as its name implies is involved in sensing calcium fluctuations in the extracellular matrix of cells, thereby having a major impact on the mineral homeostasis in humans. Besides calcium ions, the receptor is also activated by other di- and tri-valent cations, polypeptides, polyamines, antibiotics, calcilytics and calcimimetics, which upon binding induce intracellular signaling pathways. Recent studies have demonstrated that CaSR influences a wide variety of cells and processes that are involved in inflammation, the cardiovascular system, such as vascular calcification, atherosclerosis, myocardial infarction, hypertension, and obesity. Therefore, in this review, the current understanding of the role that CaSR plays in inflammation and its consequences on the cardiovascular system will be highlighted.

Phytochemistry and cardiovascular protective effects of Huang-Qi (Astragali Radix)

Huang-Qi (Astragali Radix) is an herbal tonic widely used in China and many other countries. It is derived from the roots of Astragalus membranaceus and A. membranaceus var. mongholicus and shows potent cardiovascular protective effects. In this article, we comprehensively reviewed 189 small molecules isolated from the two Astragalus species and discussed the interspecies chemical differences. Moreover, we summarized the pharmacological activities and mechanisms of action of Huang-Qi and its major bioactive compounds for the treatment of cardiovascular diseases. This review covers 171 references published between February 1983 and March 2020.

Silencing of circHIPK3 Inhibits Pressure Overload-Induced Cardiac Hypertrophy and Dysfunction by Sponging miR-185-3p

Background

Cardiac hypertrophy is induced by diverse patho-physiological stimuli and indicates an increase in cardiomyocyte size. Circular RNAs (circRNAs) and microRNAs (miRNAs), members of noncoding RNAs, are involved in several biological processes and cardiovascular diseases (CVD). Here, we investigated the potential role of circHIPK3, which is produced by the third exon of the HIPK3 gene in cardiac hypertrophy.

Methods

qRT-PCR and Sanger sequencing were conducted to identify the expression and characteristics (head-to-tail structure, stability, and location) of circHIPK3 in cardiac hypertrophy; Immunostaining of α-SMA was performed to evaluate the size of the cardiomyocytes; Transverse aortic constriction (TAC) induced hypertrophy models of mice were established to investigate the effect of circHIPK3 in vivo. Bioinformatics analysis and luciferase reporter assays, RNA immunoprecipitation, and fluorescence in situ hybridization (FISH) experiments were conducted to investigate the mechanism of circHIPK3-mediated cardiac hypertrophy.

Results

circHIPK3 is circular, more stable, and mainly located in the cytoplasm. Silencing of circHIPK3 inhibited the TAC induced cardiac hypertrophy, and reversed the effect of TAC on the echocardiograph parameters, such as left ventricular end-diastolic pressure (LVEDPS), left ventricular fraction shortening (LVFS), left ventricular ejection fraction (LVEF), and left ventricular systolic dysfunction (LVSD), and also the heart weight to tibial length (HW/TL). Angiotensin II (Ang II) Ang II-treated cardiomyocytes showed larger size of cardiomyocyte and upregulation of fetal genes, biomarkers of cardiac hypertrophy, peptide hormones, atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP), and myofilament protein, β-myosin heavy chain (β-MHC). These effects were reversed by circHIPK3 knockdown. Mechanically, circHIPK3 sponges miR-185-3p. In addition, miR-185-3p targets CASR. The rescue experiments confirmed the interaction between circHIPK3 and miR-185-3p as well as miR-185-3p and CASR.

Discussion

Our data suggested that circHIPK3 serve as a miR-185-3p sponge to regulate cardiac hypertrophy revealing a potential new target for the prevention of TAC- and Ang-II induced cardiac hypertrophy.

The Protective of Baicalin on Myocardial Ischemia-Reperfusion Injury

BACKGROUND

The aim of this study was to explore the inhibitory effect of baicalin on myocardial apoptosis induced by Ischemia-Reperfusion (I/R).

METHODS

Sprague Dawley rats' heart and myocardial cells I/R model were established in vivo and vitro, then 100 mg/kg and 10 μmol/l baicalin were administrated, respectively. The experiment was randomly divided into 4 groups (n=10): Control; I/R; IR+DMEM; and I/R+baicalin groups. Postoperation, the Left Ventricular (LV) End-Diastolic Pressure (LVEDP), the maximum velocity of LV contraction (dP/dtmax) and the maximum velocity of LV diastole (dP/dtmin) were recorded by the transthoracic echocardiography; the myocardial apoptosis percentage was analyzed by Annexin VFITC/ PI and TUNEL staining, and the apoptosis gene and protein were detected by RT-PCR and western blot. Furthermore, the protein expression of the calcium-sensing receptor (CaSR) and ERK1/2 phosphorylation were observed by western blot and Fura-2-acetoxymethyl ester. Moreover, primary rats' cardiomyocytes were cultured and ERK1/2 specific inhibitor PD98059 was added to the culture medium. The cell survival rate, vitality and apoptosis were detected by MTT, lactate dehydrogenase (LDH) and TUNEL staining assay Kit, respectively.

RESULTS

Our present study showed that baicalin significantly improved LV hemodynamic parameters and myocardial apoptosis in myocardial I/R injury rats. Furthermore, we found that baicalin could down-regulate the protein expression of CaSR, but up-regulate the protein expression of ERK1/2. Furthermore, when the cells were pretreated with ERK1/2 inhibitor PD98059, the cells survival rate significantly decreased, but LDH activity and apoptosis significantly increased. The results indicated that the effect of baicalin on myocardial I/R injury could be inhibited by ERK1/2 inhibitor.

CONCLUSION

In conclusion, our data suggests that baicalin attenuates I/R-induced myocardial injury maybe through the suppression of the CaSR/ERK1/2 signaling pathway.

Astragaloside IV prevents myocardial hypertrophy induced by mechanical stress by activating autophagy and reducing inflammation

AIMS

The aim of the present study was to investigate the effects of astragaloside IV (As-IV) on mechanical stress-induced myocardial hypertrophy, with a focus on autophagy and inflammation.

METHODS

A rat cardiac hypertrophy model was established by narrowing the abdominal aorta, and a cell hypertrophy model was established by mechanically stretching primary cardiomyocytes. Cardiac function index and cardiac hypertrophy were measured by echocardiography, heart weight index (HWI) and left ventriculus weight index (LVWI) in vivo. Cell size was measured by phalloidin-tetramethyl treatment in vitro, while hematoxylin and eosin (HE) staining was used to observe the arrangement and morphology of myocardial cells. The expression of ANP, BNP, LC3II, p62, NLRP3, and IL-1β in both myocardial tissue and cardiomyocytes was assessed by Western blot, while TNF-α and IL-18 levels in serum and cell supernatants were measured by ELISA.

RESULTS

In the aortic banding model, the cardiac function index LVEF was decreased; the hypertrophy indexes LVPWd, LVPWs, IVSd and IVSs were significantly increased; cardiomyocytes were enlarged and disordered; the expression levels of ANP, BNP, NLRP3, IL-1β and p62 were increased; and LC3II expression was decreased in both myocardial tissue and cardiomyocytes. As-IV could significantly improve cardiac function and cardiomyocyte morphology and limit hypertrophy, thereby protecting damaged hearts, while rapamycin had a similar effect as As-IV. In addition, As-IV decreased the expression of NLRP3 and IL-1β and activated autophagy, as evidenced by increased LC3II expression and decreased p62 levels.

CONCLUSION

As-IV prevents myocardial hypertrophy induced by mechanical stress by activating autophagy and reducing inflammation.

Astragaloside IV: An Effective Drug for the Treatment of Cardiovascular Diseases

Cardiovascular disease (CVD), the number one cause of death worldwide, has always been the focus of clinical and scientific research. Due to the high number of deaths each year, it is essential to find alternative therapies that are safe and effective with minimal side effects. Traditional Chinese medicine (TCM) has a long history of significant impact on the treatment of CVDs. The mode of action of natural active ingredients of drugs and the development of new drugs are currently hot topics in research on TCM. Astragalus membranaceus is a commonly used Chinese medicinal herb. Previous studies have shown that Astragalus membranaceus has anti-tumor properties and can regulate metabolism, enhance immunity, and strengthen the heart. Astragaloside IV (AS-IV) is the active ingredient of Astragalus membranaceus, which has a prominent role in cardiovascular diseases. AS-IV can protect against ischemic and hypoxic myocardial cell injury, inhibit myocardial hypertrophy and myocardial fibrosis, enhance myocardial contractility, improve diastolic dysfunction, alleviate vascular endothelial dysfunction, and promote angiogenesis. It can also regulate blood glucose and blood lipid levels and reduce the risk of cardiovascular diseases. In this paper, the mechanism of AS-IV intervention in cardiovascular diseases in recent years is reviewed in order to provide a reference for future research and new drug development.

Astragaloside IV attenuates chronic intermittent hypoxia-induced myocardial injury by modulating Ca2+ homeostasis

Obstructive sleep apnea syndrome (OSAS) is an important consequence of chronic intermittent hypoxia (CIH). Astragaloside IV (AS-IV) exerts multiple protective effects in diverse diseases. However, whether AS-IV can attenuate CIH-induced myocardial injury is unclear. In this study, rats exposed to CIH were established and treated with AS-IV for 4 weeks. In vitro, H9C2 cardiomyocytes subjected to CIH exposure were treated with AS-IV for 48 hours. Then the cardiac function, morphology, fibrosis, apoptosis and Ca²⁺ homeostasis were determined to assess cardiac damage. Results showed that AS-IV attenuated cardiac dysfunction and histological lesions in CIH rats. The increased TUNEL-positive cells and activated apoptotic proteins in CIH rats were reduced by AS-IV. We also noticed that AS-IV reversed the accumulation of Ca²⁺ and altered expressions of Ca²⁺ handling proteins (decreases of SERCA2a and RYR2, and increases of p-CaMKII and NCX1) under CIH exposure. Furthermore, CIH-induced reduction of SERCA2a activity was increased by AS-IV in rats. Similar results were also observed in H9C2 cells. Altogether, these findings indicate that AS-IV modulates Ca²⁺ homeostasis to inhibit apoptosis, protecting against CIH-induced myocardial injury eventually, suggesting it may be a potential agent for cardiac damage of OSAS patients. SIGNIFICANCE OF THE STUDY: Chronic intermittent hypoxia (CIH) is a great contributor of OSAS, which is closely associated with cardiovascular diseases. It is necessary for developing a promising drug to attenuate CIH-induced myocardial injury. This work suggests that AS-IV can attenuate myocardial apoptosis and calcium disruption, thus protecting against CIH-induced myocardial injury. It may represent a novel therapeutic for cardiac damage of OSAS.

Astragaloside IV alleviates myocardial damage induced by type 2 diabetes via improving energy metabolism

The aim of the present study was to evaluate the protective effect and mechanism of Astragaloside IV (ASIV) on myocardial injury induced by type 2 diabetes, with a focus on energy metabolism. Blood glucose, the hemodynamic index, left ventricular weight/heart weight (LVW/HW), the left ventricular systolic pressure (LVSP), the left ventricular end diastolic pressure (LVEDP) and cell survival rate were measured in streptozotocin‑induced diabetes model rats. Western blot analysis, PCR, hematoxylin‑eosin and TUNEL staining, flow cytometry and ELISA were used to detect: i) Cardiomyocyte damage indicators such as atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), cytochrome c (Cyt C), caspase‑3, cleaved caspase‑3 and the apoptotic rate; ii) energy metabolism indicators such as ATP/AMP and ADP/AMP; and iii) energy metabolism associated pathway proteins such as peroxisome proliferator‑activated receptor γ coactivator 1‑α (PGC‑1α) and nuclear respiratory factor 1 (NRF1). The present demonstrated increased blood glucose, LVW/HW, LVSP, LVEDP and the cardiomyocyte damage indicators (ANP, BNP, Cyt C and caspase‑3), in the diabetic and high glucose‑treated groups, which were decreased by ASIV. The expression of NRF‑1 and PGC‑1α significantly changed in the model group and was markedly improved following ASIV treatment. Furthermore, the abnormal energy metabolism in the model group was reversed by ASIV. According to the results, ASIV can regulate energy metabolism by regulating the release of PGC‑1α and NRF1 to rescue the abnormal energy metabolism caused by diabetes mellitus, thus decreasing the myocardial damage caused by diabetic cardiomyopathy.

Astragaloside IV protects against hyperglycemia-induced vascular endothelial dysfunction by inhibiting oxidative stress and Calpain-1 activation

AIMS

Vascular endothelial cells act as a selective barrier between circulating blood and vessel wall and play an important role in the occurrence and development of cardiovascular diseases. Astragaloside IV (As-IV) has a protective effect on vascular endothelial cells, but its underlying mechanism remains unclear. This study is aimed at investigating the effect of As-IV on endothelial dysfunction (ED).

METHODS

Male Sprague-Dawley (SD) were injected intraperitoneally with 65 mg/kg streptozotocin (STZ) to induce diabetes and then administered orally with As-IV (40, 80 mg/kg) for 8 weeks. Vascular function was evaluated by vascular reactivity in vivo and in vitro. The expression of calpain-1 and eNOS in the aorta of diabetic rats was examined by western blot. NO production was measured using nitrate reductase method. Oxidative stress was determined by measuring SOD, GSH-px and ROS.

RESULTS

Our results showed that As-IV administration significantly improved diabetes associated ED in vivo, and both NAC (an antioxidant) and MDL-28170 (calpain-1 inhibitor) significantly attenuated hyperglycemia-induced ED in vitro. Meanwhile, pretreatment with the inhibitor l-NAME nearly abolished vasodilation to ACh in all groups of rats. Furthermore, As-IV increased NO production and the expression of eNOS in the thoracic aorta of diabetic rats. In addition, the levels of ROS were significantly increased, and the activity of SOD and GSH-px were decreased in diabetic rats, while As-IV administration reversed this change in a concentration-dependent manner.

CONCLUSION

These results suggest that As-IV improves endothelial dysfunction in thoracic aortas from diabetic rats by reducing oxidative stress and calpain-1.

Nutritional preconditioning induced by astragaloside Ⅳ on isolated hearts and cardiomyocytes against myocardial ischemia injury via improving Bcl-2-mediated mitochondrial function

Ischemic preconditioning and pharmacological preconditioning are common strategies to prevent lethal myocardial injury, especially nutritional preconditioning (NPC). In this study, we investigated the effects of astragaloside IV (Ast), as an NPC agent, on myocardium suffered anoxia/reoxygenation (A/R) injury. Rats received 5 mg/kg Ast daily for 3 weeks by intragastric administration. Then, hearts were harvested and underwent A/R treatment using a Langendorff apparatus. Ast- pretreatment significantly promoted functional recovery of the myocardium, reduced infarct size, and oxidative stress, and decreased the apoptotic index. Similar findings were demonstrated in H9c2 cardiomyocytes that were pretreated with Ast for 24 h. Moreover, Ast-pretreatment significantly upregulated Bcl-2 expression, especially in mitochondria. The effects of Ast treatment against A/R injury were also reflected by increased antioxidant potential, inhibited reactive oxygen species (ROS) burst, increased oxygen consumption rate, maintained mitochondrial membrane potential (MMP), inhibited mitochondrial permeability transition pore (mPTP) opening, and prevented apoptosis. Selective inhibition of Bcl-2 by ABT-737 decreased myocardial injury protection of Ast. Ast-pretreatment resulted in NPC- related effects against A/R, and mitochondria may be the target of a cascade of events elicited by upregulating Bcl-2 expression, promoting translocation of Bcl-2 into mitochondria, maintaining MMP, inhibiting ROS bursts, thereby leading to recovery of mitochondrial respiration, preventing mPTP opening, decreasing cytochrome C release, preventing apoptosis, and ultimately alleviating myocardial injury.

G-Protein Coupled Receptor Targeting on Myeloid Cells in Atherosclerosis

Atherosclerosis, the underlying cause of the majority of cardiovascular diseases (CVDs), is a lipid-driven, inflammatory disease of the large arteries. Gold standard therapy with statins and the more recently developed proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors have improved health conditions among CVD patients by lowering low density lipoprotein (LDL) cholesterol. Nevertheless, a substantial part of these patients is still suffering and it seems that 'just' lipid lowering is insufficient. The results of the Canakinumab Anti-inflammatory Thrombosis Outcome Study (CANTOS) have now proven that inflammation is a key driver of atherosclerosis and that targeting inflammation improves CVD outcomes. Therefore, the identification of novel drug targets and development of novel therapeutics that block atherosclerosis-specific inflammatory pathways have to be promoted. The inflammatory processes in atherosclerosis are facilitated by a network of immune cells and their subsequent responses. Cell networking is orchestrated by various (inflammatory) mediators which interact, bind and induce signaling. Over the last years, G-protein coupled receptors (GPCRs) emerged as important players in recognizing these mediators, because of their diverse functions in steady state but also and specifically during chronic inflammatory processes - such as atherosclerosis. In this review, we will therefore highlight a selection of these receptors or receptor sub-families mainly expressed on myeloid cells and their role in atherosclerosis. More specifically, we will focus on chemokine receptors, both classical and atypical, formyl-peptide receptors, the chemerin receptor 23 and the calcium-sensing receptor. When information is available, we will also describe the consequences of their targeting which may hold promising options for future treatment of CVD.