Exercise Attenuates Myocardial Ischemia-Reperfusion Injury by Regulating Endoplasmic Reticulum Stress and Mitophagy Through M2 Acetylcholine Receptor

Inhibition of Th17 cell differentiation by aerobic exercise improves vasodilatation in diabetic mice

BACKGROUND

Aortic endothelial diastolic dysfunction is an early complication of diabetes and the abnormal differentiation of Th17 cells is involved in the development of diabetes. However, the exact role of exercise on regulating the Th17 cells differentiation and the underlying molecular mechanisms remain to be elucidated in diabetic mice.

METHODS

db/db and db/m+ mice were randomly divided into exercise and sedentary groups. Mice in exercise group were exercised daily, 6 days/week, for 6 weeks and mice in sedentary groups were placed on a nonmoving treadmill for 6 weeks. Vascular endothelial function was measured via wire myograph and the frequencies of Th17 from peripheral blood in mice were assessed via flow cytometry.

RESULTS

Our data showed that exercise improved insulin resistance and aortic endothelial diastolic function in db/db mice. In addition, the proportion of Th17 cells and IL-17A level in peripheral blood of db/db mice were significantly increased, and exercise could promote Th17 cell differentiation and reduce IL-17A level. More importantly, STAT3 or ROR-γt inhibitors could promote Th17 cell differentiation in db/db mice, while exercise significantly down-regulated p-STAT3/ROR-γt signaling in db/db mice, suggesting that exercise regulated Th17 differentiation through STAT3/ROR-γt signaling.

CONCLUSIONS

This study demonstrated that exercise improved vascular endothelial function in diabetic mice via reducing Th17 cell differentiation through p-STAT3/ROR-γt pathway, suggesting exercise may be an important non-pharmacological intervention strategy for the treatment of diabetes-related vascular complications.

Aerobic training attenuates cardiac remodeling in mice post-myocardial infarction by inhibiting the p300/CBP-associated factor

Aerobic training (AT), an effective form of cardiac rehabilitation, has been shown to be beneficial for cardiac repair and remodeling after myocardial infarction (MI). The p300/CBP-associated factor (PCAF) is one of the most important lysine acetyltransferases and is involved in various biological processes. However, the role of PCAF in AT and AT-mediated cardiac remodeling post-MI has not been determined. Here, we found that the PCAF protein level was significantly increased after MI, while AT blocked the increase in PCAF. AT markedly improved cardiac remodeling in mice after MI by reducing endoplasmic reticulum stress (ERS). In vivo, similar to AT, pharmacological inhibition of PCAF by Embelin improved cardiac recovery and attenuated ERS in MI mice. Furthermore, we observed that both IGF-1, a simulated exercise environment, and Embelin protected from H2O2-induced cardiomyocyte injury, while PCAF overexpression by viruses or the sirtuin inhibitor nicotinamide eliminated the protective effect of IGF-1 in H9C2 cells. Thus, our data indicate that maintaining low PCAF levels plays an essential role in AT-mediated cardiac protection, and PCAF inhibition represents a promising therapeutic target for attenuating cardiac remodeling after MI.

Mitochondrial Kinase Signaling for Cardioprotection

Myocardial ischemia/reperfusion injury is reduced by cardioprotective adaptations such as local or remote ischemic conditioning. The cardioprotective stimuli activate signaling cascades, which converge on mitochondria and maintain the function of the organelles, which is critical for cell survival. The signaling cascades include not only extracellular molecules that activate sarcolemmal receptor-dependent or -independent protein kinases that signal at the plasma membrane or in the cytosol, but also involve kinases, which are located to or within mitochondria, phosphorylate mitochondrial target proteins, and thereby modify, e.g., respiration, the generation of reactive oxygen species, calcium handling, mitochondrial dynamics, mitophagy, or apoptosis. In the present review, we give a personal and opinionated overview of selected protein kinases, localized to/within myocardial mitochondria, and summarize the available data on their role in myocardial ischemia/reperfusion injury and protection from it. We highlight the regulation of mitochondrial function by these mitochondrial protein kinases.

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.

Salvianolic acids and its potential for cardio-protection against myocardial ischemic reperfusion injury in diabetes

The incidence of diabetes and related mortality rate increase yearly in modern cities. Additionally, elevated glucose levels can result in an increase of reactive oxygen species (ROS), ferroptosis, and the disruption of protective pathways in the heart. These factors collectively heighten the vulnerability of diabetic individuals to myocardial ischemia. Reperfusion therapies have been effectively used in clinical practice. There are limitations to the current clinical methods used to treat myocardial ischemia-reperfusion injury. As a result, reducing post-treatment ischemia/reperfusion injury remains a challenge. Therefore, efforts are underway to provide more efficient therapy. Salvia miltiorrhiza Bunge (Danshen) has been used for centuries in ancient China to treat cardiovascular diseases (CVD) with rare side effects. Salvianolic acid is a water-soluble phenolic compound with potent antioxidant properties and has the greatest hydrophilic property in Danshen. It has recently been discovered that salvianolic acids A (SAA) and B (SAB) are capable of inhibiting apoptosis by targeting the JNK/Akt pathway and the NF-κB pathway, respectively. This review delves into the most recent discoveries regarding the therapeutic and cardioprotective benefits of salvianolic acid for individuals with diabetes. Salvianolic acid shows great potential in myocardial protection in diabetes mellitus. A thorough understanding of the protective mechanism of salvianolic acid could expand its potential uses in developing medicines for treating diabetes mellitus related myocardial ischemia-reperfusion.

Mitophagy for cardioprotection

Mitochondrial function is maintained by several strictly coordinated mechanisms, collectively termed mitochondrial quality control mechanisms, including fusion and fission, degradation, and biogenesis. As the primary source of energy in cardiomyocytes, mitochondria are the central organelle for maintaining cardiac function. Since adult cardiomyocytes in humans rarely divide, the number of dysfunctional mitochondria cannot easily be diluted through cell division. Thus, efficient degradation of dysfunctional mitochondria is crucial to maintaining cellular function. Mitophagy, a mitochondria specific form of autophagy, is a major mechanism by which damaged or unnecessary mitochondria are targeted and eliminated. Mitophagy is active in cardiomyocytes at baseline and in response to stress, and plays an essential role in maintaining the quality of mitochondria in cardiomyocytes. Mitophagy is mediated through multiple mechanisms in the heart, and each of these mechanisms can partially compensate for the loss of another mechanism. However, insufficient levels of mitophagy eventually lead to mitochondrial dysfunction and the development of heart failure. In this review, we discuss the molecular mechanisms of mitophagy in the heart and the role of mitophagy in cardiac pathophysiology, with the focus on recent findings in the field.