Stellate ganglion block ameliorates vascular calcification by inhibiting endoplasmic reticulum stress

Sympathetic hyperinnervation drives abdominal aortic aneurysm development by promoting vascular smooth muscle cell phenotypic switching

INTRODUCTION

Sympathetic hyperinnervation plays an important role in modulating the vascular smooth muscle cell (VSMC) phenotype and vascular diseases, but its role in abdominal aortic aneurysm (AAA) is still unknown.

OBJECTIVES

This study aimed to investigate the role of sympathetic hyperinnervation in promoting AAA development and the underlying mechanism involved.

METHODS

Western blotting and immunochemical staining were used to detect sympathetic hyperinnervation. We performed sympathetic denervation through coeliac ganglionectomy (CGX) and 6-OHDA administration to understand the role of sympathetic hyperinnervation in AAA and investigated the underlying mechanisms through transcriptome and functional studies. Sema4D knockout (Sema4D-/-) mice were utilized to determine the involvement of Sema4D in inducing sympathetic hyperinnervation and AAA development.

RESULTS

We observed sympathetic hyperinnervation, the most important form of sympathetic neural remodeling, in both mouse AAA models and AAA patients. Elimination of sympathetic hyperinnervation by CGX or 6-OHDA significantly inhibited AAA development and progression. We further revealed that sympathetic hyperinnervation promoted VSMC phenotypic switching in AAA by releasing extracellular ATP (eATP) and activating eATP-P2rx4-p38 signaling. Moreover, single-cell RNA sequencing revealed that Sema4D secreted by osteoclast-like cells induces sympathetic nerve diffusion and hyperinnervation through binding to Plxnb1. We consistently observed that AAA progression was significantly ameliorated in Sema4D-deficient mice.

CONCLUSIONS

Sympathetic hyperinnervation driven by osteoclast-like cell-derived Sema4D promotes VSMC phenotypic switching and accelerates pathological aneurysm progression by activating the eATP/P2rx4/p38 pathway. Inhibition of sympathetic hyperinnervation emerges as a potential novel therapeutic strategy for preventing and treating AAA.

Involvement of miRNA-204 carried by the exosomes of macrophages in the AT2 receptor-mediated improvement of vascular calcification

BACKGROUND

Vascular calcification (VC) always has poor cardiovascular outcomes, but it is still difficult to control. Exosomes secreted from activated macrophages can affect VC through microRNAs (miRNAs). Research has suggested that miRNA-204 inhibits VC. We previously demonstrated that angiotensin II type 2 receptor (AT2R) plays an important role in VC; however, its underlying mechanisms are not yet clear.

METHODS AND RESULTS

Rat aortic smooth muscle cells (RASMCs) and rat alveolar macrophages were cocultured with or without the phosphate and/or AT2R agonist compound 21 (C21). Calcium deposition was assessed by alizarin red staining. Protein expression was assessed by immunofluorescence staining and immunoblot analysis. The level of microRNA-204 was detected via qPCR, and its target mRNA was tested via a luciferase activity assay. C21 treatment improved the additional calcification of RASMCs cocultured with macrophages more than it did those cultured alone. The expression of miRNA-204-5p in exosomes secreted from macrophages markedly increased after C21 treatment. The decrease in the degree of calcification of RASMCs cocultured with macrophages and the expression of BMP-2, OCN, Wnt3a, β-catenin and RUNX2 induced by C21 treatment were significantly weakened after transfection with the miRNA-204-5p inhibitor. RUNX2 mRNA was the target of miRNA-204-5p in RASMCs cocultured with macrophages after C21 treatment.

CONCLUSIONS

Our results suggested that miRNA-204-5p in exosomes secreted from macrophages was at least partly involved in the AT2 receptor-mediated improvement in VC induced by phosphate through targeting RUNX2 mRNA, inhibiting the Wnt/β-catenin signalling pathway and decreasing the expression of calcification-related proteins.

Stellate ganglion, inflammation, and arrhythmias: a new perspective on neuroimmune regulation

Current research on the stellate ganglion (SG) has shifted from merely understanding its role as a collection of neurons to recognizing its importance in immune regulation. As part of the autonomic nervous system (ANS), the SG plays a crucial role in regulating cardiovascular function, particularly cardiac sympathetic nerve activity. Abnormal SG function can lead to disordered cardiac electrical activity, which in turn affects heart rhythm stability. Studies have shown that excessive activity of the SG is closely related to the occurrence of arrhythmias, especially in the context of inflammation. Abnormal activity of the SG may trigger excessive excitation of the sympathetic nervous system (SNS) through neuroimmune mechanisms, thereby increasing the risk of arrhythmias. Simultaneously, the inflammatory response of the SG further aggravates this process, forming a vicious cycle. However, the causal relationship between SG, inflammation, and arrhythmias has not yet been fully clarified. Therefore, this article deeply explores the key role of the SG in arrhythmias and its complex relationship with inflammation, providing relevant clinical evidence. It indicates that interventions targeting SG function and inflammatory responses have potential in preventing and treating inflammation-related arrhythmias, offering a new perspective for cardiovascular disease treatment strategies.

Recent Advances in Therapeutic Modalities Against Breast Cancer-Related Lymphedema: Future Epigenetic Landscape

Background: Lymphedema is a significant postsurgical complication observed in the majority of breast cancer patients. These multifactorial etiopathogenesis have a significant role in the development of novel diagnostic/prognostic biomarkers and the development of novel therapies. This review aims to ascertain the epigenetic alterations that lead to breast cancer-related lymphedema (BCRL), multiple pathobiological events, and the underlying genetic predisposing factors, signaling cascades pertinent to the lapses in effective prognosis/diagnosis, and finally to develop a suitable therapeutic regimen. Methods and Results: We have performed a literature search in public databases such as PubMed, Medline, Google Scholar, National Library of Medicine and screened several published reports. Search words such as epigenetics to induce BCRL, prognosis/diagnosis, primary lymphedema, secondary lymphedema, genetic predisposing factors for BRCL, conventional therapies, and surgery were used in these databases. This review described several epigenetic-based predisposing factors and the pathophysiological consequences of BCRL, which affect the overall quality of life, and the interplay of these events could foster the progression of lymphedema in breast cancer survivors. Prognosis/diagnostic and therapy lapses for treating BCRL are highly challenging due to genetic and anatomical variations, alteration in the lymphatic vessel contractions, and variable expression of several factors such as vascular endothelial growth factor (VEGF)-E and vascular endothelial growth factor receptor (VEGFR) in breast cancer survivors. Conclusion: We compared the efficacy of various conventional therapies for treating BCRL as a multidisciplinary approach. Further substantial research is required to decipher underlying signaling epigenetic pathways to develop chromatin-modifying therapies pertinent to the multiple etiopathogenesis to explore the correlation between the disease pathophysiology and novel therapeutic modalities to treat BCRL.

Stellate ganglion block suppresses hippocampal ferroptosis to attenuate cerebral ischemia-reperfusion injury via the Hippo pathway

Ischemic stroke is a disabling and fatal disease caused by the insufficient blood supply to the brain. Stellate ganglion block (SGB) is a type of anesthesia commonly used to relieve pain. Here, we sought to identify the effects of SGB on cerebral ischemia-reperfusion (I/R) injury. The middle cerebral artery occlusion (MCAO) model was established in rats. The brain injury was assessed using the 2,3,5-triphenyl-tetrazolium-chloride (TTC) staining assay and neurological score. Ferroptosis was analyzed by detecting cell death, Fe²⁺ content, glutathione (GSH), malonic dialdehyde (MDA), superoxide dismutase (SOD), and ferroptosis-related factors. The mechanisms of SGB were assessed using the western blot. The results showed that I/R increased brain infarction and damaged neurological function. SGB decreased I/R-induced infarction and improved neurological function. Meantime, SGB inhibited ferroptosis of the hippocampus induced by I/R via the Hippo pathway. and the Yes1 associated transcriptional regulator (YAP) of this pathway was positively correlated with the ferroptosis-related solute carrier family 7 member 11 (SLC7A11). Inhibition of the Hippo pathway reversed the effects of SGB on brain injury and ferroptosis. In conclusion, SGB inhibited ferroptosis of hippocampal neurons via activating the Hippo pathway and thereby alleviated I/R injury. The data provide a novel insight into the treatment of ischemic stroke and even other ischemic encephalopathies.

Vascular calcification: Molecular mechanisms and therapeutic interventions

Vascular calcification (VC) is recognized as a pathological vascular disorder associated with various diseases, such as atherosclerosis, hypertension, aortic valve stenosis, coronary artery disease, diabetes mellitus, as well as chronic kidney disease. Therefore, it is a life-threatening state for human health. There were several studies targeting mechanisms of VC that revealed the importance of vascular smooth muscle cells transdifferentiating, phosphorous and calcium milieu, as well as matrix vesicles on the progress of VC. However, the underlying molecular mechanisms of VC need to be elucidated. Though there is no acknowledged effective therapeutic strategy to reverse or cure VC clinically, recent evidence has proved that VC is not a passive irreversible comorbidity but an active process regulated by many factors. Some available approaches targeting the underlying molecular mechanism provide promising prospects for the therapy of VC. This review aims to summarize the novel findings on molecular mechanisms and therapeutic interventions of VC, including the role of inflammatory responses, endoplasmic reticulum stress, mitochondrial dysfunction, iron homeostasis, metabolic imbalance, and some related signaling pathways on VC progression. We also conclude some recent studies on controversial interventions in the clinical practice of VC, such as calcium channel blockers, renin-angiotensin system inhibitions, statins, bisphosphonates, denosumab, vitamins, and ion conditioning agents.

Pharmacological inhibition of eIF2alpha phosphorylation by integrated stress response inhibitor (ISRIB) ameliorates vascular calcification in rats

Vascular calcification (VC) is an independent risk factor for cardiovascular events and all-cause mortality with the absence of current treatment. This study aimed to investigate whether eIF2alpha phosphorylation inhibition could ameliorate VC. VC in rats was induced by administration of vitamin D3 (3×10(5) IU/kg, intramuscularly) plus nicotine (25 mg/kg, intragastrically). ISRIB (0.25 mg/kg·week), an inhibitor of eIF2alpha phosphorylation, ameliorated the elevation of calcium deposition and ALP activity in calcified rat aortas, accompanied by amelioration of increased SBP, PP, and PWV. The decreased protein levels of calponin and SM22alpha, and the increased levels of RUNX2 and BMP2 in calcified aorta were all rescued by ISRIB, while the increased levels of the GRP78, GRP94, and C/EBP homologous proteins in rats with VC were also attenuated. Moreover, ISRIB could prevent the elevation of eIF2alpha phosphorylation and ATF4, and partially inhibit PERK phosphorylation in the calcified aorta. These results suggested that an eIF2alpha phosphorylation inhibitor could ameliorate VC pathogenesis by blocking eIF2alpha/ATF4 signaling, which may provide a new target for VC prevention and treatment.

Role of endothelial cells in vascular calcification

Vascular calcification (VC) is active and regulates extraosseous ossification progress, which is an independent predictor of cardiovascular disease (CVD) morbidity and mortality. Endothelial cells (ECs) line the innermost layer of blood vessels and directly respond to changes in flow shear stress and blood composition. Together with vascular smooth muscle cells, ECs maintain vascular homeostasis. Increased evidence shows that ECs have irreplaceable roles in VC due to their high plasticity. Endothelial progenitor cells, oxidative stress, inflammation, autocrine and paracrine functions, mechanotransduction, endothelial-to-mesenchymal transition (EndMT), and other factors prompt ECs to participate in VC. EndMT is a dedifferentiation process by which ECs lose their cell lineage and acquire other cell lineages; this progress coexists in both embryonic development and CVD. EndMT is regulated by several signaling molecules and transcription factors and ultimately mediates VC via osteogenic differentiation. The specific molecular mechanism of EndMT remains unclear. Can EndMT be reversed to treat VC? To address this and other questions, this study reviews the pathogenesis and research progress of VC, expounds the role of ECs in VC, and focuses on the regulatory factors underlying EndMT, with a view to providing new concepts for VC prevention and treatment.

Extracellular vesicle miR-32 derived from macrophage promotes arterial calcification in mice with type 2 diabetes via inhibiting VSMC autophagy

Background

The development of diabetes vascular calcification (VC) is tightly associated with the inhibition of vascular smooth muscle cell (VSMC) autophagy. Previously, our team found that miR-32-5p (miR-32) promotes macrophage activation, and miR-32 is expressed at higher level in the plasma of patients with coronary calcification. However, whether miR-32 mediates the function of macrophages in type 2 diabetes (T2D) VC is still unclear.

Methods

Wild-type (WT) and miR-32−/− mice were used in this study. qRT-PCR and western blotting were used to analyze gene expression. Flow cytometry was used to analyze the influence of glucose concentration on macrophage polarization. Nanoparticle tracking analysis (NTA), transmission electron microscopy, and confocal microscopy were used to identify macrophage extracellular vehicles (EVs). Immunofluorescence, in situ hybridization (ISH), immunohistochemistry, and alizarin red staining were used to analyze the influence of macrophage EVs on autophagy and calcification of the aorta of miR-32−/− mice. A luciferase assay was used to analyze the effect of miR-32 on myocyte enhancer factor 2D (Mef2d) expression. Co-IP combined with mass spectrometry (MS) and transcriptome sequencing was used to analyze the signalling pathway by which Mef2d acts in VSMC autophagy.

Results

We found that high glucose conditions upregulate miR-32 expression in macrophages and their EVs. Importantly, macrophages and their EVs promote VSMC osteogenic differentiation and upregulate miR-32 expression in VSMCs. Moreover, miR-32 mimics transfection promoted osteogenic differentiation and inhibited autophagy in VSMCs. In vitro and in vivo experiments showed that Mef2d is the key target gene of miR-32 that inhibits VSMC autophagy. Furthermore, MS and transcriptome sequencing found that cGMP-PKG is an important signalling pathway by which Mef2d regulates VSMC autophagy. In addition, after T2D miR-32−/− mice were injected with macrophage EVs via the caudal vein, miR-32 was detected in aortic VSMCs of miR-32−/− mice. Moreover, autophagy was significantly inhibited, and calcification was significantly enhanced in aorta cells.

Conclusions

These results reveal that EVs are the key pathway by which macrophages promote T2D VC, and that EVs miR-32 is a key cause of autophagy inhibition in VSMCs.

Endoplasmic Reticulum Stress and Pathogenesis of Vascular Calcification

Vascular calcification (VC) is characterized by calcium phosphate deposition in blood vessel walls and is associated with many diseases, as well as increased cardiovascular morbidity and mortality. However, the molecular mechanisms underlying of VC development and pathogenesis are not fully understood, thus impeding the design of molecular-targeted therapy for VC. Recently, several studies have shown that endoplasmic reticulum (ER) stress can exacerbate VC. The ER is an intracellular membranous organelle involved in the synthesis, folding, maturation, and post-translational modification of secretory and transmembrane proteins. ER stress (ERS) occurs when unfolded/misfolded proteins accumulate after a disturbance in the ER environment. Therefore, downregulation of pathological ERS may attenuate VC. This review summarizes the relationship between ERS and VC, focusing on how ERS regulates the development of VC by promoting osteogenic transformation, inflammation, autophagy, and apoptosis, with particular interest in the molecular mechanisms occurring in various vascular cells. We also discuss, the therapeutic effects of ERS inhibition on the progress of diseases associated with VC are detailed.

Increased β-adrenergic stimulation augments vascular smooth muscle cell calcification via PKA/CREB signalling

In chronic kidney disease (CKD), hyperphosphatemia promotes medial vascular calcification, a process augmented by osteogenic transdifferentiation of vascular smooth muscle cells (VSMCs). VSMC function is regulated by sympathetic innervation, and these cells express α- and β-adrenergic receptors. The present study explored the effects of β2-adrenergic stimulation by isoproterenol on VSMC calcification. Experiments were performed in primary human aortic VSMCs treated with isoproterenol during control or high phosphate conditions. As a result, isoproterenol dose dependently up-regulated the expression of osteogenic markers core-binding factor α-1 (CBFA1) and tissue-nonspecific alkaline phosphatase (ALPL) in VSMCs. Furthermore, prolonged isoproterenol exposure augmented phosphate-induced calcification of VSMCs. Isoproterenol increased the activation of PKA and CREB, while knockdown of the PKA catalytic subunit α (PRKACA) or of CREB1 genes was able to suppress the pro-calcific effects of isoproterenol in VSMCs. β2-adrenergic receptor silencing or inhibition with the selective antagonist ICI 118,551 blocked isoproterenol-induced osteogenic signalling in VSMCs. The present observations imply a pro-calcific effect of β2-adrenergic overstimulation in VSMCs, which is mediated, at least partly, by PKA/CREB signalling. These observations may support a link between sympathetic overactivity in CKD and vascular calcification.

Clinical Study of Stellate Ganglion Block Combined with General Anesthesia on Hemodynamics, Cognitive Function, and Gastrointestinal Function in Elderly Patients Undergoing Partial Hepatectomy

Partial hepatectomy under general anesthesia is prone to hemodynamic alterations, and stress reactions are the main contributing factors to postoperative cognitive function in elderly partial hepatectomy patients. Postoperative cognitive dysfunction increases the incidence of postoperative complications and long-term morbidity and mortality in elderly patients. With the increasing trend of aging population and the gradual increase of elderly people undergoing surgical treatment, it is especially important to study the corresponding prevention and treatment measures. In this study, a total of 90 patients with primary liver cancer who received hepatectomy in our hospital from July 2020 to July 2021 were included as the research subject. The changes in hemorheology, stress-related indexes, cognitive function, postoperative pain, and gastrointestinal function were compared between the two groups The results showed that SGB combined with general anesthesia can effectively reduce hemodynamic fluctuations in elderly partial hepatectomy patients, alleviate surgical stress, promote postoperative recovery of cognitive function and gastrointestinal function with high safety, and is worthy of clinical promotion.

Ameliorative effect of allicin on vascular calcification via inhibiting endoplasmic reticulum stress

OBJECTIVES

Vascular calcification (VC) is an independent predictor for cardiovascular events and mortality. However, there are currently no effective methods to reverse or prevent it. The present study aimed to determine the ameliorative effect of allicin on VC.

METHODS

VC model of rats was induced by high-dose vitamin D₃, which was valued by Alizarin Red staining, calcium contents, and alkaline phosphatase in the aorta. Systolic blood pressure, pulse pressure, and pulse wave velocity were measured to determine aortic stiffness. Protein levels were detected by Western blot.

RESULTS

Allicin treatment rescued aortic VC and stiffness. The increased protein levels of RUNX2 and BMP2, two markers of osteoblastic phenotype of vascular smooth muscle cells, in the calcified aorta were attenuated by allicin, whereas the decreased levels of calponin and SM22α induced by calcification were improved. Allicin treatment significantly attenuated the increased protein levels of GRP78, GRP94, and CHOP, which are key markers of endoplasmic reticulum stress, in the calcified aorta. The activation of PERK/eIF2α/ATF4 cascades was also prevented by allicin.

CONCLUSIONS

Allicin could ameliorate aortic VC and stiffness. The ameliorative effect of allicin on VC might be mediated by inhibiting PERK/eIF2α/ATF4 cascades. Our results might provide a new proof for VC treatment.

Effect of Stellate Ganglion Block on Intraoperative Propofol and Fentanyl Consumption in Patients with Complex Regional Pain Syndrome Undergoing Surgical Repair of Brachial Plexus Injury: A Randomized, Double-blind, Placebo-controlled Trial

Introduction

Stellate ganglion block (SGB) is commonly performed to treat chronic painful conditions, such as complex regional pain syndrome (CRPS) and postherpetic neuralgia. However, whether it is effective in reducing anesthesia and analgesia requirement during surgery (acute pain) is not known.

Materials and Methods

Sixty American Society of Anesthesiologists (ASA) physical status I and II patients with CRPS type II undergoing surgery for repair of brachial plexus injury were randomized (1:1) to receive SGB with either 10 mL of 0.5% bupivacaine (Group B) or a matching placebo (Group S) before induction of anesthesia.

Results

There was a significant reduction in the requirement of total intraoperative propofol (1659.7 ± 787.5 vs. 2500.7 ± 740.9 mg, P = 0.0003) and fentanyl (190.0 ± 82.5 vs. 327.3 ± 139.3, P = 0.0001) in Group B compared with Group S. Similarly, in Group B, the time to first analgesic was much longer (328 ± 219 vs. 64 ± 116 min, P = 0.000) and postoperative fentanyl requirement for 24 h was lesser compared to Group S (0.6 ± 1.1 vs. 2.1 ± 1.3 μg/kg, P = 0.000).

Conclusion

SGB is effective in reducing the requirement of intraoperative propofol and fentanyl as well as decreasing opioid requirement in the postoperative period in patients with CRPS type II undergoing surgery.

High-mobility group box-1 promotes vascular calcification in diabetic mice via endoplasmic reticulum stress

Several studies reported the role of endoplasmic reticulum stress (ERS) in vascular calcification. High-mobility group box-1 (HMGB-1) plays a substantial role in diabetes and its complications. However, relatively little information is available regarding the association between HMGB-1 and calcification, and the underlying mechanism has still remained elusive. Therefore, in the present study, we attempted to indicate whether HMGB-1 could promote vascular calcification via ERS in diabetes. After induction of diabetes by Streptozotocin (STZ), mice were treated with glycyrrhizin (Gly) or 4-phenylbutyrate (4-PBA). Mineral deposition was confirmed by reverse transcription-polymerase chain reaction (RT-PCR) and calcium assay. In cell experiments, calcification of vascular smooth muscle cells (VSMCs) was performed with Alizarin Red staining, alkaline phosphatase (ALP) activity and RT-PCR. Expression and location of HMGB-1 in aortic tissue were detected by Western blotting, immunocytochemistry (ICC) and immunohistochemistry (IHC). Diabetic mice demonstrated increased HMGB-1 expression, ERS and vascular calcification. However, inhibition of HMGB-1 with Gly or inhibition of ERS with 4-PBA ameliorated the enhanced vascular calcification and ERS in diabetic mice. In vitro experiments unveiled that inhibition of HMGB-1 attenuated advanced glycation end products (AGEs)-induced ERS in VSMCs. In addition, AGEs promoted translocation and secretion of HMGB-1 in VSMCs, which was reversed by 4-PBA. Moreover, VSMCs exhibited increased mineralization and osteogenic gene expressions in response to HMGB-1 and AGEs. However, inhibition of ERS with 4-PBA partially, although noticeably, attenuated VSMC calcification induced by HMGB-1. Thus, diabetes induced translocation and secretion of HMGB-1 via ERS, which resulted in calcification in diabetic mice and in AGEs-treated VSMCs.

Shuxuetong injection simultaneously ameliorates dexamethasone-driven vascular calcification and osteoporosis

Osteoporosis (OP) and vascular calcification (VC) share a number of common risk factors, pathophysiological mechanisms and etiology, which are known as bone-vascular axis. The present study aimed to investigate the effects of Shuxuetong (SXT) injection on VC and osteoporosis. A rat model of VC and osteoporosis was induced by dexamethasone (DEX; 1 mg/kg/day for 4 weeks, intramuscularly). Simultaneously, 0.6 ml/kg/day SXT was intraperitoneally injected. Compared with control rats, DEX induced significantly more VC and OP, as determined by increased calcium deposition and alkaline phosphatase activity in the aorta, disturbed structure, decreased levels of cortical bone thickness and trabecular bone area, and increased apoptosis in the bone. SXT injection ameliorated DEX-induced VC and osteoporosis; furthermore, the osteoblastic differentiation of vascular smooth muscle cells and the activation of endoplasmic reticulum stress in the DEX group was also prevented by SXT injection. Compared with control rats, protein expression levels of sclerostin, a crucial crosslink of the bone-vascular axis, were significantly increased in the aorta and bone of rats with DEX, which was also attenuated by SXT injection. Thus, the present study suggested that SXT injection could ameliorate both VC and OP, and may be mediated by the regulation of sclerostin. The present study may provide the basis a novel strategy for the prevention and treatment of VC and OP, which emerge as side-effects of glucocorticoids.

Inhibition of endoplasmic reticulum stress mediates the ameliorative effect of apelin on vascular calcification

AIMS

Apelin is the endogenous ligand of G protein-coupled receptor APJ and play an important role in the regulation of cardiovascular homeostasis. We aimed to investigate whether apelin ameliorates vascular calcification (VC) by inhibition of endoplasmic reticulum stress (ERS).

METHODS AND RESULTS

VC model in rats was induced by nicotine plus vitamin D, while calcification of vascular smooth muscle cell (VSMC) was induced by beta-glycerophosphate. Alizarin Red S staining showed dramatic calcium deposition in the aorta of rats with VC, while calcium contents and ALP activity also increased in calcified aorta. Protein levels of apelin and APJ were decreased in the calcified aorta. In rats with VC, apelin treatment significantly ameliorated aortic calcification, compliance and stimulation of ERS. The ameliorative effect of apelin on VC and ERS was also observed in calcified VSMCs. ERS stimulator (tunicamycin or DTT) blocked the beneficial effect of apelin. Apelin treatment activated the PI3K/Akt signaling, blockage of which by wortmannin or inhibitor IV prevented the ameliorative effect of apelin, while ERS inhibitor 4-PBA rescued the blockade effect of wortmannin. Akt-induced GSK inhibition prevented the phosphorylation of PERK and IRE1, and the activation of these two major ERS branches. F13A blocked the ameliorative effect of apelin on VC and ERS, which was reversed by treatment with 4-PBA or Akt activator SC79 CONCLUSIONS: Apelin ameliorated VC by binding to APJ and then prevented ERS activation by stimulating Akt signaling. These results might provide new target for therapy and prevention of VC.

Uremic Toxins and Vascular Calcification-Missing the Forest for All the Trees

The cardiorenal syndrome relates to the detrimental interplay between the vascular system and the kidney. The uremic milieu induced by reduced kidney function alters the phenotype of vascular smooth muscle cells (VSMC) and promotes vascular calcification, a condition which is strongly linked to cardiovascular morbidity and mortality. Biological mechanisms involved include generation of reactive oxygen species, inflammation and accelerated senescence. A better understanding of the vasotoxic effects of uremic retention molecules may reveal novel avenues to reduce vascular calcification in CKD. The present review aims to present a state of the art on the role of uremic toxins in pathogenesis of vascular calcification. Evidence, so far, is fragmentary and limited with only a few uremic toxins being investigated, often by a single group of investigators. Experimental heterogeneity furthermore hampers comparison. There is a clear need for a concerted action harmonizing and standardizing experimental protocols and combining efforts of basic and clinical researchers to solve the complex puzzle of uremic vascular calcification.

25-Hydroxycholesterol promotes vascular calcification via activation of endoplasmic reticulum stress

Vascular calcification is a highly regulated process similar to osteogenesis involving phenotypic change of vascular smooth muscle cells (VSMCs). 25-Hydroxycholesterol (25-HC), one of oxysterols synthesized by the enzyme cholesterol 25-hydroxylase, has been shown to promote bovine calcifying vascular cells (CVC) calcification. However, whether and how 25-HC regulates vascular calcification are not completely understood. In this study, in vitro and ex vivo models of vascular calcification were used to determine whether 25-HC regulates vascular calcification. Alizarin red staining and calcium content assay showed that 25-HC treatment promoted calcification of rat and human VSMCs in a dose-dependent manner. Similarly, ex vivo study further confirmed that 25-HC accelerated calcification of rat aortic rings. In addition, western blot analysis showed that 25-HC significantly up-regulated the expression of endoplasmic reticulum stress (ERS) signaling molecules including ATF4 and CHOP in VSMCs and flow cytometry analysis revealed that 25-HC increased apoptosis of VSMCs. Moreover, knockdown of CHOP by siRNA blocked 25-HC-induced mineral deposition in VSMCs. Collectively, this study for the first time demonstrates that 25-HC promotes vascular calcification via ATF4/CHOP signaling using in vitro and ex vivo models, suggesting that ERS is involved in the regulation of 25-HC-induced vascular calcification.

Icariside II prevents hypertensive heart disease by alleviating endoplasmic reticulum stress via the PERK/ATF-4/CHOP signalling pathway in spontaneously hypertensive rats

OBJECTIVES

Reducing endoplasmic reticulum stress (ERS)-induced cardiomyocyte apoptosis is a key strategy for preventing hypertensive heart disease. In our previous study, Icariside II can improve left ventricular remodelling in spontaneously hypertensive rats (SHRs). This study aims to determine whether Icariside II can exert its effect by inhibiting ERS-induced cardiomyocyte apoptosis via the PERK/ATF-4/CHOP signalling pathway.

METHODS

Spontaneously hypertensive rats were randomly divided into model group and Icariside II groups. The rats in the Icariside II groups were intragastrically administrated with Icariside II 4, 8 and 16 mg/kg from 14 to 26 week-age, respectively. The left ventricular function was measured at the 18, 22 and 26 week-age by small animal ultrasound. At the end of the 26th week, cardiomyocyte apoptosis was analysed and the levels of GRP78, PERK, ATF-4 and CHOP gene and protein were detected.

KEY FINDINGS

The function of left ventricular became declined with age in SHRs, but improved in Icariside II groups. Myocardial apoptosis was aggravated in SHRs, but alleviated in Icariside II groups. Icariside II could reduce the levels of GRP78, PERK, ATF-4, CHOP gene and protein that increased in SHRs.

CONCLUSIONS

Icariside II prevents hypertensive heart disease by alleviating ERS-induced cardiomyocyte apoptosis, and its mechanism is related to the impediment of the PERK/ATF-4/CHOP signalling pathway.