Targeting CaMKII-δ9 Ameliorates Cardiac Ischemia/Reperfusion Injury by Inhibiting Myocardial Inflammation. Circulation research BACKGROUND:CaMKII (Ca/calmodulin-dependent kinase II) plays a central role in cardiac ischemia/reperfusion (I/R) injury-an important therapeutic target for ischemic heart disease. In the heart, CaMKII-δ is the predominant isoform and further alternatively spliced into 11 variants. In humans, CaMKII-δ9 and CaMKII-δ3, the major cardiac splice variants, inversely regulate cardiomyocyte viability with the former pro-death and the latter pro-survival. However, it is unknown whether specific inhibition of the detrimental CaMKII-δ9 prevents cardiac I/R injury and, if so, what is the underlying mechanism. Here, we aim to investigate the cardioprotective effect of specific CaMKII-δ9 inhibition against myocardial I/R damage and determine the underlying mechanisms. METHODS:The role and mechanism of CaMKII-δ9 in cardiac I/R injury were investigated in mice in vivo, neonatal rat ventricular myocytes, and human embryonic stem cell-derived cardiomyocytes. RESULTS:We demonstrate that CaMKII-δ9 inhibition with knockdown or knockout of its feature exon, exon 16, protects the heart against I/R-elicited injury and subsequent heart failure. I/R-induced cardiac inflammation was also ameliorated by CaMKII-δ9 inhibition, and compared with the previously well-studied CaMKII-δ2, CaMKII-δ9 overexpression caused more profound cardiac inflammation. Mechanistically, in addition to IKKβ (inhibitor of NF-κB [nuclear factor-κB] kinase subunit β), CaMKII-δ9, but not δ2, directly interacted with IκBα (NF-κB inhibitor α) with its feature exon 13-16-17 combination and increased IκBα phosphorylation and consequently elicited more pronounced activation of NF-κB signaling and inflammatory response. Furthermore, the essential role of CaMKII-δ9 in myocardial inflammation and damage was confirmed in human cardiomyocytes. CONCLUSIONS:We not only identified CaMKII-δ9-IKK/IκB-NF-κB signaling as a new regulator of human cardiomyocyte inflammation but also demonstrated that specifically targeting CaMKII-δ9, the most abundant CaMKII-δ splice variant in human heart, markedly suppresses I/R-induced cardiac NF-κB activation, inflammation, and injury and subsequently ameliorates myocardial remodeling and heart failure, providing a novel therapeutic strategy for various ischemic heart diseases. 10.1161/CIRCRESAHA.121.319478

Hirsutine ameliorates myocardial ischemia-reperfusion injury through improving mitochondrial function via CaMKII pathway. Clinical and experimental hypertension (New York, N.Y. : 1993) Acute myocardial infarction (AMI) is the leading cause of death worldwide. Ischemia-reperfusion (I/R) injury is considered the most common contributor to AMI. Hirsutine has been shown to protect cardiomyocytes against hypoxic injury. The present study investigated whether hirsutine improved AMI induced by I/R injury and the underlying mechanisms. In our study, we used a rat model of myocardial I/R injury. The rats were given hirsutine daily (5, 10, 20 mg/kg) by gavage for 15 days before the myocardial I/R injury. Detectable changes were observed in myocardial infarct size, mitochondrial function, histological damage, and cardiac cell apoptosis. According to our findings, hirsutine pre-treatment reduced the myocardial infarct size, enhanced cardiac function, inhibited cell apoptosis, reduced the tissue lactate dehydrogenase (LDH) and reactive oxygen species (ROS) content, as well as enhanced myocardial ATP content and mitochondrial complex activity. In addition, hirsutine balanced mitochondrial dynamics by increasing Mitofusin2 (Mfn2) expression while decreasing dynamin-related protein 1 phosphorylation (p-Drp1), which was partially regulated by ROS and calmodulin-dependent protein kinase II phosphorylation (p-CaMKII). Mechanistically, hirsutine inhibited mitochondrial-mediated apoptosis during I/R injury by blocking the AKT/ASK-1/p38 MAPK pathway. This present study provides a promising therapeutic intervention for myocardial I/R injury. 10.1080/10641963.2023.2192444

Mitochondrial CaMKII causes adverse metabolic reprogramming and dilated cardiomyopathy. Nature communications Despite the clear association between myocardial injury, heart failure and depressed myocardial energetics, little is known about upstream signals responsible for remodeling myocardial metabolism after pathological stress. Here, we report increased mitochondrial calmodulin kinase II (CaMKII) activation and left ventricular dilation in mice one week after myocardial infarction (MI) surgery. By contrast, mice with genetic mitochondrial CaMKII inhibition are protected from left ventricular dilation and dysfunction after MI. Mice with myocardial and mitochondrial CaMKII overexpression (mtCaMKII) have severe dilated cardiomyopathy and decreased ATP that causes elevated cytoplasmic resting (diastolic) Ca concentration and reduced mechanical performance. We map a metabolic pathway that rescues disease phenotypes in mtCaMKII mice, providing insights into physiological and pathological metabolic consequences of CaMKII signaling in mitochondria. Our findings suggest myocardial dilation, a disease phenotype lacking specific therapies, can be prevented by targeted replacement of mitochondrial creatine kinase or mitochondrial-targeted CaMKII inhibition. 10.1038/s41467-020-18165-6

Macrophage-enriched Sectm1a promotes efficient efferocytosis to attenuate ischemia/reperfusion-induced cardiac injury. JCI insight Efficient clearance and degradation of apoptotic cardiomyocytes by macrophages (collectively termed efferocytosis) is critical for inflammation resolution and restoration of cardiac function after myocardial ischemia/reperfusion (I/R). Here, we define secreted and transmembrane protein 1a (Sectm1a), a cardiac macrophage-enriched gene, as a modulator of macrophage efferocytosis in I/R-injured hearts. Upon myocardial I/R, Sectm1a-KO mice exhibited impaired macrophage efferocytosis, leading to massive accumulation of apoptotic cardiomyocytes, cardiac inflammation, fibrosis, and consequently, exaggerated cardiac dysfunction. By contrast, therapeutic administration of recombinant SECTM1A protein significantly enhanced macrophage efferocytosis and improved cardiac function. Mechanistically, SECTM1A could elicit autocrine effects on the activation of glucocorticoid-induced TNF receptor (GITR) at the surface of macrophages, leading to the upregulation of liver X receptor α (LXRα) and its downstream efferocytosis-related genes and lysosomal enzyme genes. Our study suggests that Sectm1a-mediated activation of the Gitr/LXRα axis could be a promising approach to enhance macrophage efferocytosis for the treatment of myocardial I/R injury. 10.1172/jci.insight.173832

Cardiac-derived extracellular vesicles improve mitochondrial function to protect the heart against ischemia/reperfusion injury by delivering ATP5a1. Journal of nanobiotechnology BACKGROUND:Numerous studies have confirmed the involvement of extracellular vesicles (EVs) in various physiological processes, including cellular death and tissue damage. Recently, we reported that EVs derived from ischemia-reperfusion heart exacerbate cardiac injury. However, the role of EVs from healthy heart tissue (heart-derived EVs, or cEVs) on myocardial ischemia-reperfusion (MI/R) injury remains unclear. RESULTS:Here, we demonstrated that intramyocardial administration of cEVs significantly enhanced cardiac function and reduced cardiac damage in murine MI/R injury models. cEVs treatment effectively inhibited ferroptosis and maintained mitochondrial homeostasis in cardiomyocytes subjected to ischemia-reperfusion injury. Further results revealed that cEVs can transfer ATP5a1 into cardiomyocytes, thereby suppressing mitochondrial ROS production, alleviating mitochondrial damage, and inhibiting cardiomyocyte ferroptosis. Knockdown of ATP5a1 abolished the protective effects of cEVs. Furthermore, we found that the majority of cEVs are derived from cardiomyocytes, and ATP5a1 in cEVs primarily originates from cardiomyocytes of the healthy murine heart. Moreover, we demonstrated that adipose-derived stem cells (ADSC)-derived EVs with ATP5a1 overexpression showed much better efficacy on the therapy of MI/R injury compared to control ADSC-derived EVs. CONCLUSIONS:These findings emphasized the protective role of cEVs in cardiac injury and highlighted the therapeutic potential of targeting ATP5a1 as an important approach for managing myocardial damage induced by MI/R injury. 10.1186/s12951-024-02618-x