Dexpramipexole attenuates myocardial ischemia/reperfusion injury through upregulation of mitophagy

Programmed death of cardiomyocytes in cardiovascular disease and new therapeutic approaches

Cardiovascular diseases (CVDs) have a complex pathogenesis and pose a major threat to human health. Cardiomyocytes have a low regenerative capacity, and their death is a key factor in the morbidity and mortality of many CVDs. Cardiomyocyte death can be regulated by specific signaling pathways known as programmed cell death (PCD), including apoptosis, necroptosis, autophagy, pyroptosis, and ferroptosis, etc. Abnormalities in PCD can lead to the development of a variety of cardiovascular diseases, and there are also molecular-level interconnections between different PCD pathways under the same cardiovascular disease model. Currently, the link between programmed cell death in cardiomyocytes and cardiovascular disease is not fully understood. This review describes the molecular mechanisms of programmed death and the impact of cardiomyocyte death on cardiovascular disease development. Emphasis is placed on a summary of drugs and potential therapeutic approaches that can be used to treat cardiovascular disease by targeting and blocking programmed cell death in cardiomyocytes.

Mitochondrial quality control in human health and disease

Mitochondria, the most crucial energy-generating organelles in eukaryotic cells, play a pivotal role in regulating energy metabolism. However, their significance extends beyond this, as they are also indispensable in vital life processes such as cell proliferation, differentiation, immune responses, and redox balance. In response to various physiological signals or external stimuli, a sophisticated mitochondrial quality control (MQC) mechanism has evolved, encompassing key processes like mitochondrial biogenesis, mitochondrial dynamics, and mitophagy, which have garnered increasing attention from researchers to unveil their specific molecular mechanisms. In this review, we present a comprehensive summary of the primary mechanisms and functions of key regulators involved in major components of MQC. Furthermore, the critical physiological functions regulated by MQC and its diverse roles in the progression of various systemic diseases have been described in detail. We also discuss agonists or antagonists targeting MQC, aiming to explore potential therapeutic and research prospects by enhancing MQC to stabilize mitochondrial function.

The Janus face of mitophagy in myocardial ischemia/reperfusion injury and recovery

In myocardial ischemia/reperfusion injury (MIRI), moderate mitophagy is a protective or adaptive mechanism because of clearing defective mitochondria accumulates during MIRI. However, excessive mitophagy lead to an increase in defective mitochondria and ultimately exacerbate MIRI by causing overproduction or uncontrolled production of mitochondria. Phosphatase and tensin homolog (PTEN)-induced kinase 1 (Pink1), Parkin, FUN14 domain containing 1 (FUNDC1) and B-cell leukemia/lymphoma 2 (BCL-2)/adenovirus E1B19KD interaction protein 3 (BNIP3) are the main mechanistic regulators of mitophagy in MIRI. Pink1 and Parkin are mitochondrial surface proteins involved in the ubiquitin-dependent pathway, while BNIP3 and FUNDC1 are mitochondrial receptor proteins involved in the non-ubiquitin-dependent pathway, which play a crucial role in maintaining mitochondrial homeostasis and mitochondrial quality. These proteins can induce moderate mitophagy or inhibit excessive mitophagy to protect against MIRI but may also trigger excessive mitophagy or insufficient mitophagy, thereby worsening the condition. Understanding the actions of these mitophagy mechanistic proteins may provide valuable insights into the pathological mechanisms underlying MIRI development. Based on the above background, this article reviews the mechanism of mitophagy involved in MIRI through Pink1/Parkin pathway and the receptor mediated pathway led by FUNDC1 and BNIP3, as well as the related drug treatment, aim to provide effective strategies for the prevention and treatment of MIRI.

YAP Facilitates NEDD4L-Mediated Ubiquitination and Degradation of ACSL4 to Alleviate Ferroptosis in Myocardial Ischemia-Reperfusion Injury

BACKGROUND

Ferroptosis is a novel iron-dependent type of cell death that takes part in the progression of myocardial ischemia/reperfusion injury (MIRI). However, the detailed mechanism of ferroptosis underlying MIRI remains unclear. This study aimed to investigate the regulatory role of yes-associated protein (YAP) in ferroptosis during MIRI.

METHODS

The in vivo and in vitro MIRI models were established in the Sprague-Dawley (SD) rats and H9C2 cardiomyocytes. The infarct volume, pathologic changes, cardiac function, serum levels of lactate dehydrogenase (LDH) and creatine kinase (CK)-MB were detected. Western blotting and immunohistochemistry were performed to measure the expression of YAP, neural precursor cell expressed developmentally downregulated 4-like (NEDD4L) and ferroptosis-related proteins. Ferroptosis was evaluated by Fe2+, malondialdehyde (MDA), LDH, glutathione (GSH), and lipid reactive oxygen species (ROS) levels. Molecular mechanism was analyzed by co-immunoprecipitation (Co-IP), chromatin immunoprecipitation (ChIP), and dual-luciferase reporter assay.

RESULTS

YAP and NEDD4L were remarkably low expressed in MIRI models. YAP overexpression reduced myocardial infarct volume and improved cardiac function. In addition, YAP inhibited MIRI-induced ferroptosis as confirmed by reducing levels of Fe2+, MDA, LDH, lipid ROS, and ferroptosis-related protein ACSL4, and enhancing GSH level and cell viability. Mechanistically, YAP facilitated NEDD4L transcription that consequently caused ubiquitination and degradation of ACSL4, thereby restraining ferroptosis in MIRI. YAP knockdown aggravated MIRI-induced ferroptosis, which was counteracted by NEDD4L overexpression.

CONCLUSIONS

YAP represses MIRI-induced cardiomyocyte ferroptosis via promoting NEDD4L transcription and subsequent ubiquitination and degradation of ACSL4. YAP-mediated ferroptosis inhibition might be a novel therapeutic strategy for MIRI.

Contribution and therapeutic value of mitophagy in cerebral ischemia-reperfusion injury after cardiac arrest

Cardiopulmonary resuscitation and related life support technologies have improved substantially in recent years; however, mortality and disability rates from cardiac arrest (CA) remain high and are closely associated with the high incidence of cerebral ischemia-reperfusion injury (CIRI), which is explained by a "double-hit" model (i.e., resulting from both ischemia and reperfusion). Mitochondria are important power plants in the cell and participate in various biochemical processes, such as cell differentiation and signaling in eukaryotes. Various mitochondrial processes, including energy metabolism, calcium homeostasis, free radical production, and apoptosis, are involved in several important stages of the progression and development of CIRI. Mitophagy is a key mechanism of the endogenous removal of damaged mitochondria to maintain organelle function and is a critical target for CIRI treatment after CA. Mitophagy also plays an essential role in attenuating ischemia-reperfusion in other organs, particularly during post-cardiac arrest myocardial dysfunction. Regulation of mitophagy may influence necroptosis (a programmed cell death pathway), which is the main endpoint of organ ischemia-reperfusion injury. In this review, we summarize the main signaling pathways related to mitophagy and their associated regulatory proteins. New therapeutic methods and drugs targeting mitophagy in ischemia-reperfusion animal models are also discussed. In-depth studies of the mechanisms underlying the regulation of mitophagy will enhance our understanding of the damage and repair processes in CIRI after CA, thereby contributing to the development of new therapeutic strategies.

Therapeutic potentials of terbium hydroxide nanorods for amelioration of hypoxia-reperfusion injury in cardiomyocytes

Myocardial hypoxia reperfusion (H/R) injury is the paradoxical exacerbation of myocardial damage, caused by the sudden restoration of blood flow to hypoxia affected myocardium. It is a critical contributor of acute myocardial infarction, which can lead to cardiac failure. Despite the current pharmacological advancements, clinical translation of cardioprotective therapies have proven challenging. As a result, researchers are looking for alternative approaches to counter the disease. In this regard, nanotechnology, with its versatile applications in biology and medicine, can confer broad prospects for treatment of myocardial H/R injury. Herein, we attempted to explore whether a well-established pro-angiogenic nanoparticle, terbium hydroxide nanorods (THNR) can ameliorate myocardial H/R injury. For this study, in vitro H/R-injury model was established in rat cardiomyocytes (H9c2 cells). Our investigations demonstrated that THNR enhance cardiomyocyte survival against H/R-induced cell death. This pro-survival effect of THNR is associated with reduction of oxidative stress, lipid peroxidation, calcium overload, restoration of cytoskeletal integrity and mitochondrial membrane potential as well as augmentation of cellular anti-oxidant enzymes such as glutathione-s-transferase (GST) and superoxide dismutase (SOD) to counter H/R injury. Molecular analysis revealed that the above observations are traceable to the predominant activation of PI3K-AKT-mTOR and ERK-MEK signalling pathways by THNR. Concurrently, THNR also exhibit apoptosis inhibitory effects mainly by suppression of pro-apoptotic proteins like Cytochrome C, Caspase 3, Bax and p53 with simultaneous restoration of anti-apoptotic protein, Bcl-2 and Survivin. Thus, considering the above attributes, we firmly believe that THNR have the potential to be developed as an alternative approach for amelioration of H/R injury in cardiomyocytes.

Dexmedetomidine Preconditioning Attenuates Myocardial Ischemia/Reperfusion Injury in Rats by Suppressing Mitophagy Via Activating Α2-Adrenergic Receptor

BACKGROUND

Dexmedetomidine (DEX), a specific α2-adrenergic receptor agonist, is protective against myocardial ischemia/reperfusion injury (MIRI). However, the association between DEX preconditioning-induced cardioprotection and mitophagy suppression remains unclear.

OBJECTIVE

Hence, we aimed to investigate whether DEX preconditioning alleviates MIRI by suppressing mitophagy via α2-adrenergic receptor activation.

METHOD

Sixty isolated rat hearts were treated with or without DEX before inducing ischemia and reperfusion; an α2-adrenergic receptor antagonist, yohimbine (YOH), was also administered before ischemia, alone or with DEX. The heart rate (HR), left ventricular diastolic pressure (LVDP), left ventricular end-diastolic pressure (LVEDP), maximal and minimal rate of left ventricular pressure development (±dp/dtmax), and myocardial infarction size were measured. The mitochondrial ultrastructure and autophagosomes were assessed using transmission electron microscopy. Mitochondrial membrane potential and reactive oxygen species (ROS) levels were measured using JC-1 and dichloride hydrofluorescein diacetate assays, respectively. The expression levels of the mitophagy-associated proteins Beclin1, LC3II/I ratio, p62, PINK1, and Parkin were detected by western blotting.

RESULTS

Compared with the control group, in the ischemia/reperfusion group, the HR, LVDP, and ±dp/dtmax were remarkably decreased (p< 0.05), whereas LVEDP and infarct sizes were significantly increased (p< 0.05). DEX preconditioning significantly improved cardiac dysfunction reduced myocardial infarction size, maintained mitochondrial structural integrity, increased mitochondrial membrane potential, inhibited autophagosomes formation, and decreased ROS production and Beclin1, LC3II/I ratio, PINK1, Parkin, and p62 expression(p< 0.05). When DEX and YOH were combined, YOH canceled the effect of DEX, whereas the use of YOH alone had no effect.

CONCLUSION

Therefore, DEX preconditioning was cardioprotective against MIRI in rats by suppressing mitophagy via α2-adrenergic receptor activation.

Reducing myocardial infarction by combination of irisin and Dendrobium nobile Lindl through inhibiting nod-like receptor protein-3-related pyroptosis and activating PINK1/Parkin-mitophagy during aging

Aging, a crucial risk factor for ischemic heart disease, has negative impacts on cardioprotective mechanisms. As such, there is still an unmet requirement to explore potential therapies for improving the outcomes of myocardial ischemia/reperfusion (IR) injury in elderly subjects. Here, we aimed to confirm the cardioprotective function of irisin/Dendrobium nobile Lindl (DNL) combination therapy against myocardial IR injury in aged rats, with a focus on the involvement of pyroptosis and mitophagy. Male aged Wistar rats (22-24 months old, 400-450 g; n = 54) underwent myocardial IR or sham surgery. Before IR operation, rats were pretreated with irisin (0.5 mg/kg, intraperitoneally) and/or DNL (80 mg/kg, orally) for 1 or 4 weeks, respectively, at corresponding groups. Cardiac function, lactate dehydrogenase (LDH) and cardiac-specific isoform of troponin-I (cTn-I) levels, the expression of proteins involved in pyroptosis (nod-like receptor protein-3 (NLRP3), apoptosis-associated speck-like protein, c-caspase-1, and GSDMD-N) and mitophagy (PINK1 and Parkin), and pro-inflammatory cytokines levels were evaluated after 24 h of reperfusion. Irisin/DNL combined therapy significantly restored cardiac function and decreased LDH and cTn-I levels. It also downregulated pyroptosis-related proteins, upregulated PINK1 and Parkin, and decreased pro-inflammatory cytokines secretion. Pretreatment with Mdivi-1, as mitophagy inhibitor, abolished the cardioprotective action of dual therapy. This study revealed the cardioprotective effects of irisin/DNL combination therapy against IR-induced myocardial injury in aged rats, and also showed that the mechanism might be associated with suppression of NLRP3-related pyroptosis through enhancing the activity of the PINK1/Parkin mitophagy. This combination therapy is worthy of further detailed studies due to its potential to alleviate myocardial IR injury upon aging.

The immunoproteasome subunit β2i ameliorates myocardial ischemia/reperfusion injury by regulating Parkin-Mfn1/2-mediated mitochondrial fusion

Mitochondrial dynamics are critical for maintaining mitochondrial morphology and function during cardiac ischemia and reperfusion (I/R). The immunoproteasome complex is an inducible isoform of the proteasome that plays a key role in modulating inflammation and some cardiovascular diseases, but the importance of immunoproteasome catalytic subunit β2i (also known as LMP10 or MECL1) in regulating mitochondrial dynamics and cardiac I/R injury is largely unknown. Here, using β2i-knockout (KO) mice and rAAV9-β2i-injected mice, we discovered that β2i expression and its trypsin-like activity were significantly attenuated in the mouse I/R myocardium and in patients with myocardial infarction (MI). Moreover, β2i-KO mice exhibited greatly enhanced I/R-mediated cardiac dysfunction, infarct size, myocyte apoptosis and oxidative stress accompanied by excessive mitochondrial fission due to Mfn1/2 and Drp1 imbalance. Conversely, cardiac overexpression of β2i in mice injected with recombinant adeno-associated virus 9 (rAAV9)-β2i ameliorated cardiac I/R injury. Mechanistically, I/R injury reduced β2i expression and activity, which increased the expression of the E3 ligase Parkin protein and promoted the degradation of mitofusin 1/2 (Mfn1/2), leading to excessive mitochondrial fission. In conclusion, our data suggest for the first time that β2i exerts a protective role against cardiac I/R injury and that increasing β2i expression may be a new therapeutic option for cardiac ischemic disease in clinical practice. Graphical abstract showing how the immunoproteasome subunit β2i ameliorates myocardial I/R injury by regulating Parkin-Mfn1/2-mediated mitochondrial fusion.

Mitophagy in cardiovascular diseases: molecular mechanisms, pathogenesis, and treatment

With the growing prevalence of cardiovascular disease (CVD), there is an urgent need to explore non-conventional therapeutic measures to alleviate the burden of CVD on global healthcare. Mitochondrial injury plays a cardinal role in the pathogenesis of CVD. Mitochondrial dynamics and mitophagy are essential machineries that govern mitochondrial health in cardiomyocytes in physiological and pathophysiological settings. However, with the onset and progression of CVD, homeostasis of mitophagy is disturbed through largely unknown pathological mechanisms, causing mitochondrial damage and ultimately cardiomyocyte death. In this review we decipher the dual regulatory role of mitophagy in CVD pathogenesis, summarize controversies in mitophagy, and highlight recently identified compounds capable of modulating mitophagy. We share our perspectives on future mitophagy research directions in the context of CVD.

Dexpramipexole Attenuates White Matter Injury to Facilitate Locomotion and Motor Coordination Recovery via Reducing Ferroptosis after Intracerebral Hemorrhage

Deciphering the factors causing damage to white matter fiber bundles and exploring new strategies to alleviate white matter injury (WMI) is a promising treatment to improve neurological impairments after intracerebral hemorrhage (ICH). Ferroptosis usually occurs at perihematomal region and contributes to neuronal death due to reactive oxygen species (ROS) production. Dexpramipexole (DPX) easily crosses the blood brain barrier (BBB) and exerts antioxidative properties by reducing ROS production, while the role of DPX in ferroptosis after ICH remains elusive. Here, our results indicated that ferroptosis played a significant role in WMI resulting from iron and ROS accumulation around hematoma. Further evidence demonstrated that the administration of DPX decreased iron and ROS deposition to inhibit ferroptosis at perihematomal site. With the inhibition of ferroptosis, WMI was alleviated at perihematomal site, thereafter promoting locomotion and motor coordination recovery in mice after ICH. Subsequently, the results showcased that the expression of glutathione peroxidase 4 (GPX4) and ferroptosis suppressing protein 1 (FSP1) was upregulated with the administration of DPX. Collectively, the present study uncovers the underlying mechanism and elucidates the therapeutic effect of DPX on ICH, and even in other central nervous system (CNS) diseases with the presence of ferroptosis.

PINK1/Parkin-mediated mitophagy in cardiovascular disease: From pathogenesis to novel therapy

Cardiovascular disease(CVD)is one of the predominant causes of death and morbidity. Mitochondria play a key role in maintaining cardiac energy metabolism. However, mitochondrial dysfunction leads to excessive production of ROS, resulting in oxidative damage to cardiomyocytes and contributing to a variety of cardiovascular diseases. In such a case, the clearance of impaired mitochondria is necessary. Currently, most studies have indicated an essential role for mitophagy in maintaining cardiac homeostasis and regulating CVD-related metabolic transition. Recent studies have implicated that PTEN-induced putative kinase 1 (PINK1)/Parkin-mediated mitophagy has been implicated in maintaining cardiomyocyte homeostasis. Here, we discuss the physiological and pathological roles of PINK1/Parkin-mediated mitophagy in the cardiovascular system, as well as potential therapeutic strategies based on PINK1/Parkin-mediated mitophagy modulation, which are of great significance for the prevention and treatment of cardiovascular diseases.

L-Borneol 7-O-[β-D-Apiofuranosyl-(1 → 6)]-β-D-Glucopyranoside Alleviates Myocardial Ischemia-Reperfusion Injury in Rats and Hypoxic/Reoxygenated Injured Myocardial Cells via Regulating the PI3K/AKT/mTOR Signaling Pathway

Ischemia/reperfusion (I/R) is a primary cause of morbidity and mortality in acute myocardial infarction (AMI). L-Borneol 7-O-[β-D-apiofuranosyl-(1→6)]-β-D-glucopyranoside (LBAG), extracted from the Radix Ophiopogonis, is the main bioactive component that may be exerting cardiovascular protection in AMI. The purpose was to examine the effects of LBAG on myocardial I/R injury (MIRI) in rats and H9c2 cells treated with hypoxia/reoxygenation (H/R). MIRI was induced through the combination of ischemia with reperfusion for 30 min and 24 h, respectively. LBAG was administered 7 days before vascular ligation. Myocardial function was detected by an electrocardiograph, histological, TTC, and TUNEL staining analyses. The influences of LBAG on the content concentration of cardiac enzymes in the serum were measured by ELISA. Moreover, H9c2 cells were exposed to LBAG or combined with AKT inhibitor (perifosine) and then exposed to H/R for simulating the cardiac injury process. Afterward, cell viability, LDH, CD-KM release, apoptosis, and autophagy were evaluated by CCK-8 and ELISA assays, flow cytometry, TUNEL, and immunofluorescence staining, respectively. Additionally, the proteins of apoptosis, autophagy, and PI3K/mTOR pathway were determined by western blotting. In I/R rats, LBAG pretreatment significantly ameliorated cardiac function, as illustrated by reducing the infarct size, myocardial autophagy, and apoptosis levels. In H/R-induced H9c2 cells, LBAG pretreatment significantly decreased cell apoptosis, LC3 II/I, and Beclin 1 levels, elevated the Bcl-2 levels, attenuated LDH, and CD-KM production. Moreover, LBAG pretreatment markedly increased the PI3K/mTOR pathway activation, and the protective influences of LBAG were partly abolished with the AKT inhibitor perifosine treatment. These findings demonstrated the protective functions of LBAG on I/R by regulating apoptosis and autophagy in vitro and in vivo by activating the PI3K/mTOR pathway.

Anshen-Buxin-Liuwei pill, a Mongolian medicinal formula could alleviate cardiomyocyte hypoxia/reoxygenation injury via mitochondrion pathway

BACKGROUND

Anshen Buxin Liuwei pill (ABLP) is a Mongolian medicinal formula that is composed of six medicinal materials: the Mongolian medicine Bos taurus domesticus Gmelin, Choerospondias axillaris (Roxb.) Burtt et Hill, Myristica fragrans Houtt., Eugenia caryophμllata Thunb., Aucklandia lappa Decne., and Liqui dambar formosana Hance. ABLP is considered to have a therapeutic effect on symptoms such as coronary heart disease, angina pectoris, arrhythmia, depression and irritability, palpitation, and shortness of breath.

METHODS

H9c2 cardiomyocytes were used to construct a hypoxia/reoxygenation (HR) injury model. CCK-8 assay and Annexin V-FITC cell apoptosis assays were used for cell viability and cell apoptosis determination. The LDH, SOD, MDA, CAT, CK, GSH-Px, Na⁺-K⁺-ATPase, and Ca²⁺-ATPase activities in cells were determined to assess the protective effects of ABLP. The mRNA levels of Sirtuin3 (Sirt3) and Cytochrome C (Cytc) in H9c2 cells were determined by quantitative real-time PCR.

RESULTS

The results indicate that HR-treated cells began to shrink from the spindle in an irregular shape with some floated in the medium. By increasing the therapeutic dose of ABLP (5, 25, and 50 μg/mL), the cells gradually reconverted in a concentration-dependent manner. The release of CK in HR-treated cells was significantly increased, indicating that ABLP exerts a protective effect in H9c2 cells against HR injury and can improve mitochondrial energy metabolism and mitochondrial function integrity. The present study scrutinized the cardioprotective effects of ABLP against HR-induced H9c2 cell injury through antioxidant and mitochondrial pathways.

CONCLUSIONS

ABLP could be a promising therapeutic drug for the treatment of myocardial ischemic cardiovascular disease. The results will provide reasonable information for the clinical use of ABLP.

Mitophagy Regulation Following Myocardial Infarction

Mitophagy, which mediates the selective elimination of dysfunctional mitochondria, is essential for cardiac homeostasis. Mitophagy is regulated mainly by PTEN-induced putative kinase protein-1 (PINK1)/parkin pathway but also by FUN14 domain-containing 1 (FUNDC1) or Bcl2 interacting protein 3 (BNIP3) and BNIP3-like (BNIP3L/NIX) pathways. Several studies have shown that dysregulated mitophagy is involved in cardiac dysfunction induced by aging, aortic stenosis, myocardial infarction or diabetes. The cardioprotective role of mitophagy is well described, whereas excessive mitophagy could contribute to cell death and cardiac dysfunction. In this review, we summarize the mechanisms involved in the regulation of cardiac mitophagy and its role in physiological condition. We focused on cardiac mitophagy during and following myocardial infarction by highlighting the role and the regulation of PI NK1/parkin-; FUNDC1-; BNIP3- and BNIP3L/NIX-induced mitophagy during ischemia and reperfusion.

Advances in Cardiotoxicity Induced by Altered Mitochondrial Dynamics and Mitophagy

Mitochondria are the most abundant organelles in cardiac cells, and are essential to maintain the normal cardiac function, which requires mitochondrial dynamics and mitophagy to ensure the stability of mitochondrial quantity and quality. When mitochondria are affected by continuous injury factors, the balance between mitochondrial dynamics and mitophagy is broken. Aging and damaged mitochondria cannot be completely removed in cardiac cells, resulting in energy supply disorder and accumulation of toxic substances in cardiac cells, resulting in cardiac damage and cardiotoxicity. This paper summarizes the specific underlying mechanisms by which various adverse factors interfere with mitochondrial dynamics and mitophagy to produce cardiotoxicity and emphasizes the crucial role of oxidative stress in mitophagy. This review aims to provide fresh ideas for the prevention and treatment of cardiotoxicity induced by altered mitochondrial dynamics and mitophagy.