Protective effect of hyperoside on cardiac ischemia reperfusion injury through inhibition of ER stress and activation of Nrf2 signaling

Ferulic acid protects against stress-induced myocardial injury in mice

Excessive stress is a known contributor to cardiovascular diseases (CVD), and ferulic acid (FA), a natural phenolic compound, has demonstrated significant antioxidant and anti-inflammatory properties. This study investigates the protective effects of FA against stress-induced myocardial injury (SIMI) and elucidates the underlying mechanisms. An acute SIMI model was established in mice using low-temperature water immersion restraint. Cardiac function was assessed via cardiac index and histopathological analysis. Serum levels of corticosterone (CORT), lactate dehydrogenase (LDH), and brain natriuretic peptide (BNP) were quantified using enzyme-linked immunosorbent assay (ELISA), along with inflammatory markers TNF-α and IL-1β. The oxidative stress parameters, including malondialdehyde (MDA), glutathione (GSH), superoxide dismutase (SOD), and reactive oxygen species (ROS), were analyzed using colorimetric methods and fluorescent probes. Immunohistochemistry (IHC) and Western Blot were used to analyze the expression of proteins related to TNF, MAPK, PPAR-α/PGC-1α, and Nrf2 signaling pathways. Results indicated that FA pretreatment improved cardiac index, myocardial structural integrity, and reduced inflammatory cell infiltration. Serum levels of LDH, BNP, CORT, TNF-α, and IL-1β were significantly decreased in FA-treated SIMI mice. Elevated MDA and ROS levels, along with decreased GSH and SOD levels in the SIMI group, were reversed by FA pretreatment, likely through activation of the PPARα/PGC-1α and Nrf2 signaling pathways. Additionally, FA inhibited the TNF-α/TNFR1 and ERK/JNK MAPK pathways, contributing to its protective effects. In conclusion, FA mitigates SIMI by alleviating oxidative stress and inflammatory responses.

Endoplasmic reticulum stress in pancreatic β-cell dysfunction: The potential therapeutic role of dietary flavonoids

Diabetes mellitus (DM) is a global health burden that is characterized by the loss or dysfunction of pancreatic β-cells. In pancreatic β-cells, endoplasmic reticulum (ER) stress is a fact of life that contributes to β-cell loss or dysfunction. Despite recent advances in research, the existing treatment approaches such as lifestyle modification and use of conventional therapeutics could not prevent the loss or dysfunction of pancreatic β-cells to abrogate the disease progression. Therefore, targeting ER stress and the consequent unfolded protein response (UPR) in pancreatic β-cells may be a potential therapeutic strategy for diabetes treatment. Dietary phytochemicals have therapeutic applications in human health owing to their broad spectrum of biochemical and pharmacological activities. Flavonoids, which are commonly obtained from fruits and vegetables worldwide, have shown promising prospects in alleviating ER stress. Dietary flavonoids including quercetin, kaempferol, myricetin, isorhamnetin, fisetin, icariin, apigenin, apigetrin, vitexin, baicalein, baicalin, nobiletin hesperidin, naringenin, epigallocatechin 3-O-gallate hesperidin (EGCG), tectorigenin, liquiritigenin, and acacetin have shown inhibitory effects on ER stress in pancreatic β-cells. Dietary flavonoids modulate ER stress signaling components, chaperone proteins, transcription factors, oxidative stress, autophagy, apoptosis, and inflammatory responses to exert their pharmacological effects on pancreatic β-cells ER stress. This review focuses on the role of dietary flavonoids as potential therapeutic adjuvants in preserving pancreatic β-cells from ER stress. Highlights of the underlying mechanisms of action are also presented as well as possible strategies for clinical translation in the management of DM.

Butanol Extract of Acanthopanax senticosus (Rupr. et Maxim.) Harms Alleviates Atherosclerosis in Apolipoprotein E-Deficient Mice Fed a High-Fat Diet

This study investigated the effect of butanol extract of AS (ASBUE) on atherosclerosis in apolipoprotein E-deficient (ApoE^-/-) mice. The mice were administered ASBUE (390 or 130 mg/kg/day) or rosuvastatin (RSV) via oral gavage for eight weeks. In ApoE^-/- mice, ASBUE suppressed the abnormal body weight gain and improved serum and liver biochemical indicators. ASBUE remarkably reduced the aortic plaque area, improved liver pathological conditions, and lipid metabolism abnormalities, and altered the intestinal microbiota structure in ApoE^-/- mice. In the vascular tissue of ASBUE-treated mice, P-IKKβ, P-NFκB, and P-IκBα levels tended to decrease, while IκB-α increased in high fat-diet-fed atherosclerotic mice. These findings demonstrated the anti-atherosclerotic potential of ASBUE, which is mediated by the interaction between the gut microbiota and lipid metabolism and regulated via the Nuclear Factor-kappa B (NF-κB) pathway. This work paves the groundwork for subsequent studies to develop innovative drugs to treat atherosclerosis.

Therapeutic potential of dietary flavonoid hyperoside against non-communicable diseases: targeting underlying properties of diseases

Non-communicable diseases (NCDs) are a global epidemic with diverse pathogenesis. Among them, oxidative stress and inflammation are the most fundamental co-morbid features. Therefore, multi-targets and multi-pathways therapies with significant anti-oxidant and anti-inflammatory activities are potential effective measures for preventing and treating NCDs. The flavonol glycoside compound hyperoside (Hyp) is widely found in a variety of fruits, vegetables, beverages, and medicinal plants and has various health benefits, especially excellent anti-oxidant and anti-inflammatory properties targeting nuclear factor erythroid 2-related factor 2 (Nrf2) and nuclear factor-κB (NF-κB) signaling pathways. In this review, we summarize the pathogenesis associated with oxidative stress and inflammation in NCDs and the biological activity and therapeutic potential of Hyp. Our findings reveal that the anti-oxidant and anti-inflammatory activities regulated by Hyp are associated with numerous biological mechanisms, including positive regulation of mitochondrial function, apoptosis, autophagy, and higher-level biological damage activities. Hyp is thought to be beneficial against organ injuries, cancer, depression, diabetes, and osteoporosis, and is a potent anti-NCDs agent. Additionally, the sources, bioavailability, pharmacy, and safety of Hyp have been established, highlighting the potential to develop Hyp into dietary supplements and nutraceuticals.

Hyperoside ameliorates TNF‑α‑induced inflammation, ECM degradation and ER stress‑mediated apoptosis via the SIRT1/NF‑κB and Nrf2/ARE signaling pathways in vitro

Intervertebral disc degeneration (IDD) is the main pathogenesis of numerous cases of chronic neck and back pain, and has become the leading cause of spinal-related disability worldwide. Hyperoside is an active flavonoid glycoside that exhibits anti-inflammation, anti-oxidation and anti-apoptosis effects. The purpose of the present study was to investigate the effect of hyperoside on tumor necrosis factor (TNF)-α-induced IDD progression in human nucleus pulposus cells (NPCs) and its potential mechanism. The activity and apoptosis of NPCs were detected by Cell Counting Kit-8 and flow cytometry analyses, respectively. The expression of interleukin (IL)-6 and IL-1β was detected with ELISA kits. Western blotting was used to detect the expression levels of proteins. The results showed that hyperoside effectively alleviated TNF-α-induced NPC apoptosis, and hyperoside treatment inhibited the upregulation of inducible nitric oxide synthase, cyclooxygenase-2, IL-1β and IL-6 in TNF-α-stimulated NPCs. Compared with the findings in the TNF-α group, the intervention of hyperoside attenuated the upregulated expression of aggrecan and collagen II, and downregulated the expressions of matrix metalloproteinase (MMP) 3, MMP13 and a disintegrin and metalloproteinase with thrombospondin motifs 5. In addition, hyperoside upregulated sirtuin-1 (SIRT1) and nuclear factor E2-related factor 2 (Nrf2) protein expression, and inhibition of SIRT1 or Nrf2 signaling reversed the protective effect of hyperoside on TNF-α-induced NPCs. In summary, hyperoside ameliorated TNF-α-induced inflammation, extracellular matrix degradation, and endoplasmic reticulum stress-mediated apoptosis, which may be associated with the regulation of the SIRT1/NF-κB and Nrf2/antioxidant responsive element signaling pathways by hyperoside.

Protective Effects of Shen-Yuan-Dan Capsule against Ischemia/Reperfusion Injury in Cardiomyocytes by Alleviating Endoplasmic Reticulum Stress

Objective

Endoplasmic reticulum (ER) stress leads to the accumulation of misfolded proteins and an active unfolded protein response (UPR). If the ER stress is not resolved, the UPR triggers activation of the apoptotic cell death program. It has been shown that ischemia/reperfusion (I/R) injury can induce apoptosis via the ER stress pathway. We previously found that Shen-Yuan-Dan capsule (SYDC), a widely used traditional Chinese medicine, reduces I/R injury. Here, we investigated whether SYDC protects against cardiomyocyte apoptosis by reducing ER stress during I/R injury and. if so, explored its mechanism of action.

Methods

We use forty male Wistar rats to prepare the SYDC pharmacological serum. An I/R injury model was established using cultures of neonatal rat ventricular myocytes where cells were exposed to 2 h of reduced oxygenation followed by 4 h of normal oxygenation. After treatment of cultured cells with serum containing SYDC for 4 h, reverse transcription polymerase chain reaction and western blotting were performed to assess the expression levels of target molecules.

Results

Ischemia/reperfusion (I/R) clearly decreased cell viability. Treatment of cells with SYDC in serum (5% and 10%) increased cell viability compared with control serum-treated I/R cardiomyocytes. The mRNA levels of glucose-regulated protein 78 (Grp78), C/EBP homologous protein (CHOP), and caspase-12 were significantly upregulated in the I/R group. The mRNA levels of Grp78, CHOP, and caspase-12 were significantly decreased in the 5% and 10% SYDC groups compared to the I/R group. The protein expression levels of Grp78, CHOP, and caspase-12 were significantly upregulated in the I/R group. Treatment of I/R cardiomyocytes with 5% or 10% SYDC reduced the expression levels of CHOP and caspase-12, while the control serum did not show this effect.

Conclusions

These findings demonstrate that SYDC alleviates ER stress and prevents ER stress-induced apoptosis via the CHOP-dependent pathway.

Hyperoside: A review on its sources, biological activities, and molecular mechanisms

Hyperoside is a natural flavonol glycoside in various plants, such as Crataegus pinnatifida Bge, Forsythia suspensa, and Cuscuta chinensis Lam. Medical research has found that hyperoside possesses a broad spectrum of biological activities, including anticancer, anti-inflammatory, antibacterial, antiviral, antidepressant, and organ protective effects. These pharmacological properties lay the foundation for its use in treating multiple diseases, such as sepsis, arthritis, colitis, diabetic nephropathy, myocardial ischemia-reperfusion, pulmonary fibrosis, and cancers. Hyperoside is obtained from the plants and chemical synthesis. This study aims to provide a comprehensive overview of hyperoside on its sources and biological activities to provide insights into its therapeutic potential, and to provide a basis for high-quality studies to determine the clinical efficacy of this compound.

ER Stress in Cardiometabolic Diseases: From Molecular Mechanisms to Therapeutics

The endoplasmic reticulum (ER) hosts linear polypeptides and fosters natural folding of proteins through ER-residing chaperones and enzymes. Failure of the ER to align and compose proper protein architecture leads to accumulation of misfolded/unfolded proteins in the ER lumen, which disturbs ER homeostasis to provoke ER stress. Presence of ER stress initiates the cytoprotective unfolded protein response (UPR) to restore ER homeostasis or instigates a rather maladaptive UPR to promote cell death. Although a wide array of cellular processes such as persistent autophagy, dysregulated mitophagy, and secretion of proinflammatory cytokines may contribute to the onset and progression of cardiometabolic diseases, it is well perceived that ER stress also evokes the onset and development of cardiometabolic diseases, particularly cardiovascular diseases (CVDs), diabetes mellitus, obesity, and chronic kidney disease (CKD). Meanwhile, these pathological conditions further aggravate ER stress, creating a rather vicious cycle. Here in this review, we aimed at summarizing and updating the available information on ER stress in CVDs, diabetes mellitus, obesity, and CKD, hoping to offer novel insights for the management of these cardiometabolic comorbidities through regulation of ER stress.

The role and mechanism of hyperoside against myocardial infarction in mice by regulating autophagy via NLRP1 inflammation pathway

ETHNOPHARMACOLOGICAL RELEVANCE

The genus Hypericum are widely distributed in China. Hypericum perforatum L. (genus Hypericum, family Hypericaceae) has a long history as a traditional Chinese medicine, which was traditionally used for the treatment of emotional distress, cardiothoracic depression, and acute mastitis. Hyperoside (Hyp) extracted from Hypericum perforatum L. has been affirmed to exert therapeutic effects on cardiovascular diseases, with widespread existence in plants of genus Hypericum. Hyp could also be extracted from Crataegus pinnatifida Bunge (genus Crataegus pinnatifida Bunge, family Rosaceae), another traditional Chinese medicine that traditionally prevented and treated heart disease in China. The cardioprotection and mechanism of Hyp comprise anti-inflammation, anti-fibrosis, activation of autophagy, and reversal of cardiac remodeling.

AIM OF THE STUDY

This study aimed to explore the Hyp effect against MI and its underlying mechanism.

MATERIALS AND METHODS

The MI model was constructed in the KM mice via a ligating surgery of the left anterior descending (LAD) coronary artery. Subsequently, the mice were divided into following seven groups: Sham group, MI group, MI + Hyp 9 mg/kg group, MI + Hyp18 mg/kg group, MI + Hyp36 mg/kg group, MI + Fosinopril group, and MI + Hyp-36 mg/kg+3-MA group. Each group was treated with Hyp in different concentrations or positive medicine for two weeks except for the sham group. After two weeks, we examined the cardiac function, electrocardiogram (ECG), myocardial hypertrophy in the non-infarct area, collagen volume fraction (CVF), perivascular collagen area (PVCA) in the infarct area, and several serum cytokines. Autophagy and inflammation in cardiomyocytes were assessed via measuring autophagy-associated proteins and NLRP1 inflammasome pathway related proteins.

RESULTS

Hyp reversed LV remodeling and adverse ECG changes through reducing CVF and myocardial hypertrophy. Additionally, Hyp treatment could reduce inflammation levels in cardiomyocytes, compared with those in MI group. Moreover, NLRP1inflammation pathway was activated after MI. Up-regulation of autophagic flux suppressed NLRP1 inflammation pathway after Hyp treatment. However, co-treatment with 3-MA abrogated above effects of Hyp.

CONCLUSIONS

Hyp had obvious protective effect on heart injury in MI mice. Echocanrdiographic and histological measurements demonstrated that Hyp treatment improved cardiac function, and ameliorated myocardial hypertrophy and fibrinogen deposition after MI. The partial mechanism is that Hyp could up-regulate autophagy after MI. Furthermore, the promotion of autophagic flux would suppress NLRP1 inflammation pathway induced by MI.

Hyperoside prevents sepsis-associated cardiac dysfunction through regulating cardiomyocyte viability and inflammation via inhibiting miR-21

BACKGROUND

Sepsis-associated cardiac dysfunction results in increased mortality. Hyperoside (Hyp) is a flavonoid, showing significant anti-inflammatory effects. However, its pharmacological effects on sepsis-induced cardiac dysfunction remain unknown. In this study, we attempted to explore whether Hyp could prevent cardiac dysfunction and its underlying mechanisms.

METHODS

We established a mice mode of sepsis by cecal ligation and puncture (CLP) treatment, and constructed a cell model of myocardial injury by lipopolysaccharide (LPS) stimulation. The cardiac function indicators and the inflammatory cytokine levels were measured. Effect of Hyp on cardiomyocyte viability was evaluated using MTT assay. The expression and functional role of microRNA-21 (miR-21), a documented molecule that regulated by Hyp, was evaluated in the constructed models, and the potential targets of miR-21 were predicted.

RESULTS

Hyp alleviated the impaired cardiac function and stimulated inflammation caused by CLP in the in vivo sepsis model, and alleviated the LPS-induced decrease in cell viability and increase in inflammation of cardiomyocytes. Additionally, Hyp significantly inhibited the expression of miR-21 in LPS-induced cardiomyocytes, and the increased cell viability and decreased inflammation caused by Hyp in the in vitro model could be reversed by miR-21 overexpression. In animal model of sepsis, the protective influence of Hyp against sepsis-induced cardiac dysfunction was attenuated by miR-21 upregulation.

CONCLUSION

Our findings demonstrated that Hyp may serve as a promising natural drug for the treatment of sepsis-associated cardiac dysfunction, and its protective role may exerted through regulating cardiomyocyte viability and inflammation by suppressing miR-21.

Pharmacological Protection against Ischemia-Reperfusion Injury by Regulating the Nrf2-Keap1-ARE Signaling Pathway

Ischemia/reperfusion (I/R) injury is associated with substantial clinical implications, including a wide range of organs such as the brain, kidneys, lungs, heart, and many others. I/R injury (IRI) occurs due to the tissue injury following the reestablishment of blood supply to ischemic tissues, leading to enhanced aseptic inflammation and stimulation of oxidative stress via reactive oxygen and nitrogen species (ROS/RNS). Since ROS causes membrane lipids’ peroxidation, triggers loss of membrane integrity, denaturation of proteins, DNA damage, and cell death, oxidative stress plays a critical part in I/R pathogenesis. Therefore, ROS regulation could be a promising therapeutic strategy for IRI. In this context, Nrf2 (NF-E2-related factor 2) is a transcription factor that regulates the expression of several factors involved in the cellular defense against oxidative stress and inflammation, including heme oxygenase-1 (HO-1). Numerous studies have shown the potential role of the Nrf2/HO-1 pathway in IRI; thus, we will review the molecular aspects of Nrf2/Kelch-like ECH-associated protein 1 (Keap1)/antioxidant response element (ARE) signaling pathway in I/R, and we will also highlight the recent insights into targeting this pathway as a promising therapeutic strategy for preventing IRI.

Using Spectrum-Effect Relationships Coupled with LC-TOF-MS to Screen Anti-arrhythmic Components of the Total Flavonoids in Hypericum attenuatum Extracts

This research explored the HPLC fingerprints of Hypericum attenuatum Choisy, which has anti-arrhythmic activity. HPLC was adopted to perform a determination of chemical fingerprints of H. attenuatum specimens acquired through seven distinct sources. The anti-arrhythmic activity of each H. attenuatum sample was obtained through pharmacodynamics experiments in animals. A regression analysis and correlation analysis were utilized to calculate the relationship of the peak and pharmacological effectiveness with the identified peak. Peaks numbered 5, 7, 13 and 14 in the fingerprint were regarded as the likely anti-arrhythmic agents. The fingerprint was compared with reference standards for identification of the correlative peaks. Liquid chromatography-time-of-flight-mass spectrometry was applied to identify its structure. As a consequence, a universal model was established for the utilization of HPLC to investigate anti-arrhythmic activity and the spectrum-effect relationship among H. attenuatum. This model is available for the discovery of the major bioactive constituents of Hypericum.

A review on herbal Nrf2 activators with preclinical evidence in cardiovascular diseases

Cardiovascular diseases (CVDs) are an ever-growing problem and are the most common cause of death worldwide. The uncontrolled production of reactive oxygen species (ROS) and the activation of ROS associated with various cell signaling pathways with oxidative cellular damage are the most common pathological conditions connected with CVDs including endothelial dysfunction, hypercontractility of vascular smooth muscle, cardiac hypertrophy and heart failure. The nuclear factor E2-related factor 2 (Nrf2) is a basic leucine zipper redox transcription factor, together with its negative regulator, kelch-like ECH-associated protein 1 (Keap1), which serves as a key regulator of cellular defense mechanisms to combat oxidative stress and associated diseases. Multiple lines of evidence described here support the cardiac protective property of Nrf2 in various experimental models of cardiac related disease conditions. In this review, we emphasized the molecular mechanisms of Nrf2 and described the detailed outline of current findings on the therapeutic possibilities of the Nrf2 activators specifically from herbal origin in various CVDs. Based on evidence from various preclinical experimental models, we have highlighted the activation of Nrf2 pathway as a budding therapeutic option for the prevention and treatment of CVDs, which needs further investigation and validation in the clinical settings.

Hyperoside protects cardiomyocytes against hypoxia‑induced injury via upregulation of microRNA‑138

Following hypoxia, cardiomyocytes are susceptible to damage, against which microRNA (miR)‑138 may act protectively. Hyperoside (Hyp) is a Chinese herbal medicine with multiple biological functions that serve an important role in cardiovascular disease. The aim of the present study was to investigate the role of Hyp in hypoxic cardiomyocytes and its effect on miR‑138. A hypoxia model was established in both H9C2 cells and C57BL/6 mice, which were stimulated by Hyp. The expression levels of miR‑138 were increased in the hypoxic myocardium in the presence of Hyp at concentrations of >50 µmol/l in vivo and >50 mg/kg in vitro. Using Cell Counting Kit‑8 and 5‑ethynyl‑2'‑deoxyuridine assays, it was observed that Hyp improved hypoxia‑induced impairment of cell proliferation. Cell apoptosis was evaluated by flow cytometry and a TUNEL assay. The number of apoptotic cells in the Hyp group was lower than that in the control group. As markers of myocardial injury, the levels of lactate dehydrogenase, creatine kinase‑myocardial band isoenzyme and malondialdehyde were decreased in the Hyp group compared with the control group, whereas the levels of superoxide dismutase were increased. A marked decrease in the levels of cleaved caspase‑3 and cleaved poly(ADP) ribose polymerase and a marked increase in expression levels of Bcl‑2 were observed in the presence of Hyp. However, miR‑138 inhibition by antagomir attenuated the protective effects of Hyp. Furthermore, Hyp treatment was associated with marked downregulation of mixed lineage kinase 3 and lipocalin‑2, but not pyruvate dehydrogenase kinase 1, in hypoxic H9C2 cells. These findings demonstrated that Hyp may be beneficial for myocardial cell survival and may alleviate hypoxic injury via upregulation of miR‑138, thereby representing a promising potential strategy for clinical cardioprotection.

Hyperoside ameliorates the progression of osteoarthritis: An in vitro and in vivo study

BACKGROUND

Osteoarthritis (OA) is a common degenerative joint disease. The pathogenesis of OA is closely related to inflammatory responses and apoptosis of chondrocytes. Hyperoside (Hyp), a natural flavonoid compound, exerts multiple bioactivities in various diseases.

PURPOSE

Our study aims to investigate the anti-arthritic effects of Hyp and delineate the potential mechanism at the cellular level.

METHODS

Murine chondrocytes were stimulated with interleukin-1β (IL-1β) with or without Hyp treatment. CCK-8 assay was used to evaluate the cytotoxic effect of Hyp. DCFH-DA was used to detect intracellular ROS. Annexin V-FITC/PI method was applied to examine apoptosis of chondrocytes. The anti-arthritic effects of Hyp and related mechanisms were investigated by examining and analyzing relative markers through quantitative PCR, western blot analysis and immunofluorescent staining. C57BL/6 mice were performed the destabilized medial meniscus (DMM) surgery to establish OA model and then injected intraperitoneally with Hyp (20 mg/kg)) for 4 or 8 weeks. Finally, mice were sacrificed and knee joints were collected for histological observation and analysis.

RESULTS

Hyp inhibited IL-1β-induced expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). Additionally, Hyp attenuated IL-1β-induced destruction of the extracellular matrix (ECM) by downregulating the expression of MMPs and ADAMTS5, and meanwhile upregulating the expression of collagen II, aggrecan, and SOX9. Also, Hyp pretreatment reduced IL-1β-induced overproduction of ROS and apoptosis of chondrocytes. Mechanistically, Hypexerted anti-inflammatory effects by partly suppressing the PI3K/AKT/NF-κB and the MAPK signaling pathways, enhancing the Nrf2/HO-1 to limit the activation of NF-κB. Moreover, Hyp played an anti-apoptotic effect via the Nrf2/ROS/BAX/Bcl-xlaxis. In vivo, cartilage degradation was attenuated with a lower OARSI score in Hyp-treated group compared to the DMM group.

CONCLUSION

Our study demonstrated that anti-arthritic effects of Hyp in vitro and in vivo, indicating Hyp might serve as a potential agent for the treatment of OA.

Modulatory properties of cardiac and quercetin glycosides from Dacryodes edulis seeds during L-NAME-induced vascular perturbation

Background Numerous food wastes have been identified to possess potent bioactive compounds used for the treatment of several diseases. Therefore this study evaluated the potentials of cardiac and quercetin glycosides extracted from Dacryodes edulis seeds to reverse vascular and endothelial damage (VAED). Methods The glycoside composition of the seeds was extracted using standard methods and characterized by gas chromatography. We then recruited rats with L-NAME-induced VAED based on confirmatory biomarkers cardiac troponin (CnT), cellular adhesion molecule (VCAM-1), lipoprotein associated phospholipase A2 (Lp-PLA2), RAAS, VWF, endothelin, eNOx, and homocysteine. Only rats that showed total alterations of all biomarkers were recruited into the respective experimental groups and treated with either metaprolol succinate (met.su) + losartan or glycoside extracts of D. edulis seeds (NPSG). Results Chromatographic isolation of glycosides in the seed showed predominance of artemetin (1.59 mg/100 g), amygdalin (3.68 mg/100 g), digitoxin (19.21 mg/100 g), digoxin (27.23 mg/100 g), avicularin (133.59 mg/100 g), and hyperoside (481.76 mg/100 g). We observed decreased water intake and higher heart beats under vascular damage as the experiment progressed up to the fourth week. The met.su + losartan and H.D NPSG proved effective in restoring troponin, but both doses of NPSG normalized the VCAM-1 and RAAS activities excluding aldosterone and Lp-PLA2. Among the endothelial dysfunction biomarkers, H.D NPSG produced equivalent effects to met.su + losartan towards restoring the eNOx and VWF activities, but showed higher potency in normalizing the endothelin and Hcy levels. Conclusions We thus propose that the synergistic effect of the isolated glycosides from D. edulis shown in our study proved potent enough at high doses in treatment of vascular and endothelial dysfunction.

CBX7 suppression prevents ischemia-reperfusion injury-induced endoplasmic reticulum stress through the Nrf-2/HO-1 pathway

Renal ischemia-reperfusion injury (I/R) usually occurs in renal transplantation and partial nephrectomy, which could lead to acute kidney injury. However, the effective treatment for renal I/R still remains limited. In the present study, we investigated whether inhibition of chromobox 7 (CBX7) could attenuate renal I/R injury in vivo and in vitro as well as the potential mechanisms. Adult male mice were subjected to right renal ischemia and reperfusion for different periods, both with and without the CBX7 inhibitor UNC3866. In addition, human kidney cells (HK-2) were subjected to a hypoxia/reoxygenation (H/R) process for different periods, both with or without the CBX7 inhibitor or siRNA for CBX7. The results showed that expression of CBX7, glucose regulator protein-78 (GRP78), phosphorylated eukaryotic translation initiation factor-2α (p-eIF2α), and C/EBP homologous protein (CHOP) were increased after extension of I/R and H/R periods. Moreover, overexpression of CBX7 could elevate the expression of CBX7, GRP78, p-eIF2α, and CHOP. However, CBX7 inhibition with either UNC3866 or genetic knockdown led to reduced expression of GRP78, p-eIF2α, and CHOP through nuclear factor-erythroid 2-related factor 2 (Nrf2)/heme oxygenase-1 activation in I/R and H/R injury. Furthermore, ML385, the Nrf2 inhibitor, could elevate endoplasmic reticulum stress levels, abrogating the protective effects of UNC3866 against renal I/R injury. In conclusion, our results demonstrated that CBX7 inhibition alleviated acute kidney injury by preventing endoplasmic reticulum stress via the Nrf2/HO-1 pathway, indicating that CBX7 inhibitor could be a potential therapeutic target for renal I/R injury.

Protective effect of hyperoside on heart failure rats via attenuating myocardial apoptosis and inducing autophagy

Heart failure (HF) is one of the most severe heart conditions, which lacks effective therapies. Therefore, it is necessary to develop more efficient drugs for HF. In this study, we investigated the cardioprotective effects of hyperoside against the pathological progression of HF. Thoracic aortic constriction (TAC) was performed to induce HF in rats. Hyperoside treatment improved cardiac function, decreased cardiomyocyte cross-sectional area and heart weight to body weight (HW/BW) ratio in HF rats. Moreover, hyperoside administration repressed apoptosis as evidenced by changing apoptosis-related protein levels, and promoted autophagy in TAC rats and angiotensin II (AngII)-induced H9C2 cells. Inhibition of autophagy by 3-methyladenine (3-MA) attenuated the beneficial effect of hyperoside against apoptosis in H9C2 cells. In summary, these data confirm that hyperoside effectively alleviates HF via suppressing apoptosis and inducing autophagy, which provides evidence that hyperoside may serve as a promising natural drug for treating HF.

Galanthamine improves myocardial ischemia-reperfusion-induced cardiac dysfunction, endoplasmic reticulum stress-related apoptosis, and myocardial fibrosis by suppressing AMPK/Nrf2 pathway in rats

Background

Myocardial ischemia/reperfusion (I/R) injury is an important cause of myocardial infarction and heart failure after cardiovascular surgery. Galanthamine (Gal) is an important Amaryllidaceae alkaloid with anti-acetylcholinesterase and anti-inflammatory activity. The purpose of this study was to investigate the role of Gal in myocardial I/R injury.

Methods

In this study, an animal model of myocardial I/R injury was constructed, and the rats were divided into five groups (n=10): the sham, I/R model, I/R + Gal (1 mg/kg), I/R + Gal (3 mg/kg), and I/R + Aspirin (20 mg/kg) groups. The expression of related proteins was detected by Western blotting and Immunohistochemistry, and Histological lesion was detected by HE staining.

Results

Results showed that Gal improves I/R-induced cardiac dysfunction in rats. Moreover, Gal inhibits I/R-induced endoplasmic reticulum stress (ERS)-related apoptosis by suppressing the expression of CHOP, Cleaved caspase 12, and caspase 3, and promoting the expression of CADD34 and BiP in rats. Furthermore, Gal mitigates I/R-induced myocardial fibrosis through restraining the expression of α-SMA and Collagen I in rats. Mechanically, Gal promoted the expression of AMPKα1, Nrf2 and HO-1. However, AMPK inhibitor Compound C exhibited the opposite effects. Collectively, this finding suggests that Gal improves I/R-induced cardiac dysfunction, ERS-related apoptosis, and myocardial fibrosis by activating AMPK/Nrf2 pathway in myocardial I/R rats.

Conclusions

Given this evidence, Gal may be a potential therapeutic drug for the treatment of I/R injury.

The role of the unfolded protein response in arrhythmias

Human heart failure is characterized by arrhythmogenic electrical remodeling consisting mostly of ion channel downregulations. Reversing these downregulations is a logical approach to antiarrhythmic therapy, but understanding the pathophysiological mechanisms of the reduced currents is crucial for finding the proper treatments. The unfolded protein response (UPR) is activated by endoplasmic reticulum (ER) stress and has been found to play pivotal roles in different diseases including neurodegenerative diseases, diabetes mellitus, and heart disease. Recently, the UPR is reported to regulate multiple cardiac ion channels, contributing to arrhythmias in heart disease. In this review, we will discuss which UPR modulators and effectors could be involved in regulation of cardiac ion channels in heart disease, and how the understanding of these regulating mechanisms may lead to new antiarrhythmic therapeutics that lack the proarrhythmic risk of current ion channel blocking therapies.

PPARα activation alleviates damage to the cytoskeleton during acute myocardial ischemia/reperfusion in rats

The cytoskeleton serves an important role in maintaining cellular morphology and function, and it is a substrate of calpain during myocardial ischemia/reperfusion (I/R) injury (MIRI). Calpain may be activated by endoplasmic reticulum (ER) stress during MIRI. The activation of peroxisome proliferator-activated receptor α (PPARα) may inhibit ischemia/reperfusion damage by regulating stress reactions. The present study aimed to determine whether the activation of PPARα protects against MIRI-induced cytoskeletal degradation, and investigated the underlying mechanism involved. Wistar rats were pretreated with or without fenofibrate and subjected to left anterior descending coronary artery ligation for 45 min, followed by 120 min of reperfusion. Calpain activity and the expression of PPARα, desmin and ER stress parameters were evaluated. Electrocardiography was performed and cardiac function was evaluated. The ultrastructure was observed under transmission electron microscopy. I/R significantly induced damage to the cytoskeleton in cardiomyocytes and cardiac dysfunction, all of which were improved by PPARα activation. In addition, I/R increased ER stress and calpain activity, which were significantly decreased in fenofibrate-pretreated rat heart tissue. The results suggested that PPARα activation may exert a protective effect against I/R in the myocardium, at least in part via ER stress inhibition. Suppression of ER stress may be an effective therapeutic target for protecting the I/R myocardium.

Activation of the unfolded protein response downregulates cardiac ion channels in human induced pluripotent stem cell-derived cardiomyocytes

RATIONALE

Heart failure is characterized by electrical remodeling that contributes to arrhythmic risk. The unfolded protein response (UPR) is active in heart failure and can decrease protein levels by increasing mRNA decay, accelerating protein degradation, and inhibiting protein translation.

OBJECTIVE

Therefore, we investigated whether the UPR downregulated cardiac ion channels that may contribute to arrhythmogenic electrical remodeling.

METHODS

Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) were used to study cardiac ion channels. Action potentials (APs) and ion channel currents were measured by patch clamp recording. The mRNA and protein levels of channels and the UPR effectors were determined by quantitative RT-PCR and Western blotting. Tunicamycin (TM, 50 ng/mL and 5 μg/mL), GSK2606414 (GSK, 300 nmol/L), and 4μ8C (5 μmol/L) were utilized to activate the UPR, inhibit protein kinase-like ER kinase (PERK) and inositol-requiring protein-1 (IRE1), respectively.

RESULTS

TM-induced activation of the UPR caused significant prolongation of the AP duration (APD) and a reduction of the maximum upstroke velocity (dV/dt_max) of the AP phase 0 in both acute (20-24 h) and chronic treatment (6 days). These changes were explained by reductions in the sodium, L-type calcium, the transient outward and rapidly/slowly activating delayed rectifier potassium currents. Na_v1.5, Ca_v1.2, K_v4.3, and K_vLQT1 channels showed concomitant reductions in mRNA and protein levels under activated UPR. Inhibition of PERK or IRE1 shortened the APD and reinstated dV/dt_max. The PERK branch regulated Na_v1.5, K_v4.3, hERG, and K_vLQT1. The IRE1 branch regulated Na_v1.5, hERG, K_vLQT1, and Ca_v1.2.

CONCLUSIONS

Activated UPR downregulates all major cardiac ion currents and results in electrical remodeling in hiPSC-CMs. Both PERK and IRE1 branches downregulate Na_v1.5, hERG, and K_vLQT1. The PERK branch specifically downregulates K_v4.3, while the IRE1 branch downregulates Ca_v1.2. Therefore, the UPR contributed to electrical remodeling, and targeting the UPR might be anti-arrhythmic.

Hyperglycemia-induced oxidative stress and heart disease-cardioprotective effects of rooibos flavonoids and phenylpyruvic acid-2-O-β-D-glucoside

Diabetic patients are at an increased risk of developing heart failure when compared to their non-diabetic counter parts. Accumulative evidence suggests chronic hyperglycemia to be central in the development of myocardial infarction in these patients. At present, there are limited therapies aimed at specifically protecting the diabetic heart at risk from hyperglycemia-induced injury. Oxidative stress, through over production of free radical species, has been hypothesized to alter mitochondrial function and abnormally augment the activity of the NADPH oxidase enzyme system resulting in accelerated myocardial injury within a diabetic state. This has led to a dramatic increase in the exploration of plant-derived materials known to possess antioxidative properties. Several edible plants contain various natural constituents, including polyphenols that may counteract oxidative-induced tissue damage through their modulatory effects of intracellular signaling pathways. Rooibos, an indigenous South African plant, well-known for its use as herbal tea, is increasingly studied for its metabolic benefits. Prospective studies linking diet rich in polyphenols from rooibos to reduced diabetes associated cardiovascular complications have not been extensively assessed. Aspalathin, a flavonoid, and phenylpyruvic acid-2-O-β-D-glucoside, a phenolic precursor, are some of the major compounds found in rooibos that can ameliorate hyperglycemia-induced cardiomyocyte damage in vitro. While the latter has demonstrated potential to protect against cell apoptosis, the proposed mechanism of action of aspalathin is linked to its capacity to enhance the expression of nuclear factor (erythroid-derived 2)-like 2 (Nrf2) expression, an intracellular antioxidant response element. Thus, here we review literature on the potential cardioprotective properties of flavonoids and a phenylpropenoic acid found in rooibos against diabetes-induced oxidative injury.