Rhynchophylline ameliorates myocardial ischemia/reperfusion injury through the modulation of mitochondrial mechanisms to mediate myocardial apoptosis

Targeted Mitochondrial Drugs for Treatment of Ischemia-Reperfusion Injury

Ischemia-reperfusion injury is a complex hemodynamic pathology that is a leading cause of death worldwide and occurs in many body organs. Numerous studies have shown that mitochondria play an important role in the occurrence mechanism of ischemia-reperfusion injury and that mitochondrial structural abnormalities and dysfunction lead to the disruption of the homeostasis of the whole mitochondria. At this time, mitochondria are not just sub-organelles to produce ATP but also important targets for regulating ischemia-reperfusion injury; therefore, drugs targeting mitochondria can serve as a new strategy to treat ischemia-reperfusion injury. Based on this view, in this review, we discuss potential therapeutic agents for both mitochondrial structural abnormalities and mitochondrial dysfunction, highlighting the application and prospects of targeted mitochondrial drugs in the treatment of ischemia-reperfusion injury, and try to provide new ideas for the clinical treatment of the ischemia-reperfusion injury.

The Traditional Chinese Medicine Gedan Jiangya Decoction Alleviates Left Ventricular Hypertrophy via Suppressing the Ras/ERK1/2 Signaling Pathway

Gedan Jiangya Decoction (GJD), a Chinese herbal medicine composed of six botanical medicines, was designed to treat hypertension (patent published number (CN114246896A)). The overexpression of the ERK (extracellular signal-regulated kinase) signaling pathway is essential in developing left ventricular hypertrophy (LVH). This study aimed to evaluate GJD's effects on LVH in spontaneously hypertensive rats (SHRs) and examine its potential mechanisms on Ras/ERK1/2 pathway regulation. Thirty-five ten-week-old SHRs were randomly assigned to one of five groups: GJD low dosage, medium dose, high dose, model, and captopril. Wistar–Kyoto (WKY) rats served as the control group. All rats received a 6-week treatment. The following parameters were measured: systolic (SBP) and diastolic blood pressure (DBP), left ventricular mass index (LVMI), and serum TGF-beta1. The pathologic structure was determined by H & E staining and Masson. TGF-beta1, Ras, ERK1/2, and C-Fos levels were determined using western blotting and real-time qPCR. SBP, DBP, and LVMI were reduced significantly in the GJD group compared with the model group. GJD inhibited TGF-beta1, Ras, ERK1/2, and C-Fos expression in LVH. In conclusion, GJD reduced the Ras/ERK1/2 pathway expression, which decreased hypertension-induced heart hypertrophy. GJD may protect hypertension-induced myocardial hypertrophy by altering gene expression patterns in the heart.

Targeted mitochondrial drugs for treatment of Myocardial ischemia-reperfusion injury

Myocardial ischemia-reperfusion injury (MI/RI) refers to the further damage done to ischemic cardiomyocytes when restoring blood flow. A large body of evidence shows that MI/RI is closely associated with excessive production of mitochondrial reactive oxygen species, mitochondrial calcium overload, disordered mitochondrial energy metabolism, mitophagy, mitochondrial fission, and mitochondrial fusion. According to the way it affects mitochondria, it can be divided into mitochondrial quality abnormalities and mitochondrial quantity abnormalities. Abnormal mitochondrial quality refers to the dysfunction caused by the severe destruction of mitochondria, which then affects the balance of mitochondrial density and number, causing an abnormal mitochondrial quantity. In the past, most of the reports were limited to the study of the mechanism of myocardial ischemia-reperfusion injury, some of which involved mitochondria, but no specific countermeasures were proposed. In this review, we outline the mechanisms for treating myocardial ischemia-reperfusion injury from the direction of mitochondria and focus on targeted interventions and drugs to restore mitochondrial health during abnormal mitochondrial quality control and abnormal mitochondrial quantity control. This is an update in the field of myocardial ischemia-reperfusion injury.

Rhynchophylline Regulates Calcium Homeostasis by Antagonizing Ryanodine Receptor 2 Phosphorylation to Improve Diabetic Cardiomyopathy

Diabetic cardiomyopathy (DCM) is a serious complication of diabetes that can lead to heart failure and death, for which there is no effective treatment. Rhynchophylline (Rhy) is the main effective component of the Chinese herbal medicine Uncaria rhynchophylla, which mainly acts on the cardiovascular and nervous systems. However, its role in protecting against DCM remains unexplored. The present study sought to reveal the mechanism of Rhy in improving type 2 diabetes mellitus (T2DM) myocardial lesions from the perspective of regulating calcium homeostasis in cardiomyocytes. We prepared a mouse model of T2DM using a high-fat diet combined with low doses of streptozotocin. The T2DM mice were given 40 mg/kg of Rhy for 8 weeks. The results showed that Rhy can attenuate cardiac pathological changes, slow down the heart rate, decrease serum cardiac enzyme levels, reduce cardiomyocyte apoptosis, enhance cardiomyocyte contractility, and raise the calcium transient amplitude in T2DM mice. Further, Rhy downregulated the phosphorylation level of ryanodine receptor 2, upregulated the phosphorylation level of phospholamban, protected mitochondrial structure and function, and increased adenosine triphosphate levels in the cardiac tissue of T2DM mice. Our results demonstrated that Rhy may protect against myocardial damage in T2DM mice and promote cardiomyocyte contraction, and its mechanism of action seems to be related to the regulation of intracellular calcium homeostasis.

Extracellular Vesicle-Encapsulated miR-183-5p from Rhynchophylline-Treated H9c2 Cells Protect against Methamphetamine-Induced Dependence in Mouse Brain by Targeting NRG1

Methamphetamine (Meth) is a highly addictive substance and the largest drug threat across the globe. There is evidence to indicate that Meth use has serious damage on central nervous system (CNS) and heart in several animal and human studies. However, the connection in the process of Meth addiction between these two systems has not been determined. Emerging data suggest that extracellular vesicles (EVs) carrying behavior-altering microRNA (miRNAs) play a crucial role in cell communication between CNS and peripheral system. Rhynchophylline (Rhy), an antiaddictive alkaloid, was used to protect the brain and heart from Meth-induced damage, which has caught our attention. Here, we used Meth-dependent conditioned place preference (CPP) animal model and cell model to verify the protective effect of Rhy-treated EVs. Further, small RNA sequencing analysis, qPCR, dual-luciferase reporter assay, and transfection test were used to identify the key EVs-encapsulated miRNAs, isolated from cultured H9c2 cells with different treatments, involved in the therapeutic effect and the underlying mechanisms of Rhy. The results demonstrate that Rhy-treated EVs exert protective effects against Meth dependence through the pathway of miR-183-5p-neuregulin-1 (NRG1). Our collective findings provide novel insights into the roles of EVs miRNAs in Meth addiction and support their potential application in the development of novel therapeutic approaches.

Neuroprotective Effects of Rhynchophylline Against Aβ1-42-Induced Oxidative Stress, Neurodegeneration, and Memory Impairment Via Nrf2-ARE Activation

Extensive studies have shown that oxidative stress is a crucial pathogenic factor in Alzheimer's disease (AD). Nuclear factor E2-related factor 2 (Nrf2) is a master cytoprotective regulator against oxidative stress, and thus represents an attractive therapeutic target in AD. The goal of our study is to investigate the contribution of Nrf2 in Rhynchophylline (Rhy)-induced neuroprotection in AD. The data showed that intraperitoneal administration of Rhy (10 or 20 mg/kg) could ameliorate Aβ1-42-induced cognitive impairment, evidenced by performance improvement in memory tests. The result of Antioxidant response element (ARE)-luciferase activity assay indicated that Rhy treatment improved ARE promoter activity. The results of reactive oxygen species (ROS), malondialdehyde (MDA) and glutathione (GSH) assessment in the frontal cortex and hippocampus showed that Rhy treatment could attenuate Aβ1-42-induced oxidative stress to some extent, evidenced by reversion of these cytokines compared to Aβ1-42 + Veh group. Rhy treatment also restored expression of Nrf2 and its downstream protein heme oxygenase-1 (HO-1), NAD(P)H/quinone oxidoreductase 1 (NOQ1), and recombinant glutamate cysteine ligase, modifier subunit (GCLM) in the frontal cortex and hippocampus of Aβ1-42-treated mice. In addition, to investigate whether activation of Nrf2-mediated pathway is responsible for the neuroprotection of Rhy, Nrf2 siRNA was used in human neuroblastoma cells (SH-SY5Y). Interestingly, the results showed that the protective effects of Rhy, including anti-oxidative, anti-apoptosis and elevation of Nrf2 and its downstream proteins, were abolished in Nrf2 siRNA-transfected cells. These findings indicate that Rhynchophylline is protective against Aβ1-42-induced neurotoxicity via Nrf2-ARE activation, and suggest that Rhy may serve as a potential candidate and promising Nrf2 activator for management of AD.

Dexmedetomidine Protects Human Renal Tubular Epithelial HK-2 Cells against Hypoxia/Reoxygenation Injury by Inactivating Endoplasmic Reticulum Stress Pathway

Objective

The study was aimed to investigate the effects and potential mechanisms of Dexmedetomidine (Dex) on hypoxia/reoxygenation (H/R) injury in human renal tubular epithelial HK-2 cells.

Materials and Methods

In this experimental study, HK-2 cells were divided into four groups: control group, Dex group, H/R group, and Dex+H/R group. The cells in control group received no treatment, and cells in Dex group were only treated with 0.1 nmol/L Dex. The cells in H/R group and Dex+H/R group were all treated with H/R (hypoxia for 24 hours and normoxia for 4 hours), and only the cells in Dex+H/R group were pre-administrated with 0.1 nmol/L Dex. Following treatments at 37˚C for 28 hours, cell viability and apoptosis were measured by MTT assay and flow cytometry, respectively. Also, the expressions of hypoxia-inducible factor 1 (HIF-1α), glucose-regulated protein 78 (GRP78), C/EBP homologous protein (CHOP), caspase-12 and cleaved caspase-3 were determined by western blot.

Results

The cell viability was significant decreased in H/R group compared with control group (P<0.05), while was significantly increased in Dex+H/R group compared with that in H/R group (P<0.05). However, the change tendency of the cell apoptosis was opposite to that of cell viability. Compared with H/R group, the expression of HIF-1α was evidently up-regulated, while GRP78, CHOP, capase-12 and cleaved caspase-3 expressions were all obviously down- regulated in Dex+H/R group (P<0.05). In addition, the concentrations of malondialdehyde (MDA) in H/R group and Dex+H/R group were 1.68 ± 0.22 nmol/mgprot and 0.85 ± 0.16 nmol/mgprot, respectively. The superoxide dismutase (SOD) activity was higher in Dex+H/R group (121 ± 11 U/L), which which was more than twice larger than that in H/R group (57 ± 10 U/L).

Conclusion

Dex could promote cell viability and inhibit apoptosis through up-regulating HIF-1α, reducing endoplasmic reticulum (ER) stress and mediating oxidative stress, thus ameliorating the H/R injury.

Recent Advances in the Anti-Inflammatory Activity of Plant-Derived Alkaloid Rhynchophylline in Neurological and Cardiovascular Diseases

Rhynchophylline (Rhy) is a plant-derived indole alkaloid isolated from Uncaria species. Both the plant and the alkaloid possess numerous protective properties such as anti-inflammatory, neuroprotective, anti-hypertensive, anti-rhythmic, and sedative effects. Several studies support the significance of the anti-inflammatory activity of the plant as an underlying mechanism for most of the pharmacological activities of the alkaloid. Rhy is effective in protecting both the central nervous system and cardiovascular system. Cerebro-cardiovascular disease primarily occurs due to changes in lifestyle habits. Many previous studies have highlighted the significance of Rhy in modulating calcium channels and potassium channels, thereby protecting the brain from neurodegenerative diseases and related effects. Rhy also has anticoagulation and anti-platelet aggregation activity. Although Rhy has displayed its role in protecting the cardiovascular system, very little is explored about its intervention in early atherosclerosis. Extensive studies are required to understand the cardioprotective effects of Rhye. This review summarized and discussed the various pharmacological effects of Rhy in neuro- and cardioprotection and in particular the relevance of Rhy in preventing early atherosclerosis using Rhy-loaded nanoparticles.

Cellular Effects of Rhynchophylline and Relevance to Sleep Regulation

Uncaria rhynchophylla is a plant highly used in the traditional Chinese and Japanese medicines. It has numerous health benefits, which are often attributed to its alkaloid components. Recent studies in humans show that drugs containing Uncaria ameliorate sleep quality and increase sleep time, both in physiological and pathological conditions. Rhynchophylline (Rhy) is one of the principal alkaloids in Uncaria species. Although treatment with Rhy alone has not been tested in humans, observations in rodents show that Rhy increases sleep time. However, the mechanisms by which Rhy could modulate sleep have not been comprehensively described. In this review, we are highlighting cellular pathways that are shown to be targeted by Rhy and which are also known for their implications in the regulation of wakefulness and sleep. We conclude that Rhy can impact sleep through mechanisms involving ion channels, N-methyl-d-aspartate (NMDA) receptors, tyrosine kinase receptors, extracellular signal-regulated kinases (ERK)/mitogen-activated protein kinases (MAPK), phosphoinositide 3-kinase (PI3K)/RAC serine/threonine-protein kinase (AKT), and nuclear factor-kappa B (NF-κB) pathways. In modulating multiple cellular responses, Rhy impacts neuronal communication in a way that could have substantial effects on sleep phenotypes. Thus, understanding the mechanisms of action of Rhy will have implications for sleep pharmacology.

Suppression of autophagy through JAK2/STAT3 contributes to the therapeutic action of rhynchophylline on asthma

Background

Asthma is a chronic inflammatory disease characterized by airway remodeling and inflammation. Rhynchophylline is a kind of indole alkaloid isolated from Uncaria rhynchophylla. Here we investigated the effect of rhynchophylline on autophagy in asthma.

Methods

A mice model of asthma was established by ovalbumin challenge. Histopathological changes were assessed by hematoxylin-eosin staining, periodic acid-schiff staining and Masson staining. The levels of IgE in serum, interleukin-6 and interleukin-13 in bronchoalveolar lavage fluid, as well as the activities of superoxide dismutase and catalase in lung tissues were detected. The expression of autophagy-related genes and Janus kinase (JAK) 2/ signal transducer and activator of transcription (STAT) 3 signal was detected by western blot and immunofluorescence. Airway smooth muscle cells (ASMCs) were isolated, and the effect rhynchophylline on autophagy in ASMCs was explored.

Results

Our data showed that rhynchophylline treatment alleviated inflammation, airway remodeling, and oxidative stress in asthma. In addition, autophagy, which was implicated in asthma, was suppressed by rhynchophylline with decreased level of autophagy-related proteins. Furthermore, rhynchophylline suppressed the JAK2/STAT3 signaling pathway, which was activated in asthma. In vitro study showed that rhynchophylline suppressed ASMC autophagy through suppressing the activation of JAK2/STAT3 signal.

Conclusions

Our study demonstrated that rhynchophylline can alleviate asthma through suppressing autophagy in asthma, and that JAK2/STAT3 signal was involved in this effect of rhynchophylline. This study indicates that rhynchophylline may become a promising drug for the treatment of asthma.