Plasma exosomes from patients with acute myocardial infarction alleviate myocardial injury by inhibiting ferroptosis through miR-26b-5p/SLC7A11 axis.

Ferroptosis promotes myocardial injury in acute myocardial infarction (AMI). Increasing evidence suggests the crucial role of exosomes in post-AMI pathophysiological regulation. We aimed to investigate the effects and underlying mechanisms of plasma exosomes derived from patients with AMI in inhibiting ferroptosis after AMI. Plasma exosomes were isolated from controls (Con-Exo) and patients with AMI (MI-Exo). These exosomes were incubated with hypoxic cardiomyocytes or intramyocardially injected into the AMI mice. Histopathological changes, cell viability, and cell death were measured to evaluate the myocardial injury. For the ferroptosis evaluation, iron particle deposition, Fe2+, ROS, MDA, GSH, and GPX4 levels were detected. Exosomal miR-26b-5p expression was detected by qRT-PCR, and the targeting relationship between miR-26b-5p and SLC7A11 was confirmed by dual luciferase reporter gene assay. The role of the miR-26b-5p/SLC7A11 axis in the regulation of ferroptosis was validated by rescue experiments in cardiomyocytes. Hypoxia-treatment induced ferroptosis and injury in H9C2 cells and primary cardiomyocytes. MI-Exo performed better than Con-Exo in inhibiting hypoxia-induced ferroptosis. miR-26b-5p expression was downregulated in MI-Exo, and miR-26b-5p overexpression significantly eliminated the inhibitory effect of MI-Exo on ferroptosis. Mechanistically, knockdown of miR-26b-5p upregulated SLC7A11/GSH/GPX4 expressions by directly targeting SLC7A11. Moreover, SLC7A11 silencing also reversed the inhibitory effect of MI-Exo on hypoxia-induced ferroptosis. In vivo, MI-Exo significantly inhibited ferroptosis, reduced myocardial injury, and improved the cardiac function of AMI mice. Our findings revealed a novel mechanism of myocardial protection that downregulation of miR-26b-5p in MI-Exo notably upregulated SLC7A11 expression, thereby inhibiting post-AMI ferroptosis and alleviating myocardial injury.

Li H ，Ding J ，Liu W ，Wang X ，Feng Y ，Guan H ，Chen Z ... -  《-》

EGCG attenuated acute myocardial infarction by inhibiting ferroptosis via miR-450b-5p/ACSL4 axis.

Epigallocatechin gallate (EGCG) has multiple biological effects such as anti-tumor multiple drug resistance, antioxidation and anti-inflammatory properties. Ferroptosis is the main driving factor of ischemic heart injury, thus inhibiting ferroptosis may prove to be an effective treatment strategy for cardiovascular diseases. However, the role of EGCG on ferroptosis in ischemic myocardium and underlying mechanisms remain uncertain. This study was aimed to investigate the effects and potential mechanisms of EGCG on myocardial ischemic-induced ferroptosis both in vitro and in vivo. Cardiomyocyte hypoxia model and mouse acute myocardial infarction (AMI) model were established in vitro and in vivo. MiR-450b-5p and ACSL4 silencing or overexpression plasmids were transfected, with or without EGCG pretreatment. Cell viability was determined by the CCK-8 assay. Hematoxylin and eosin (HE) staining and transmission electron microscopy (TEM) were used to evaluate the morphologic alterations. TTC staining was used to observe the infarction area, and echocardiography was adopted to appraise the heart function. Using flow cytometry, the presence of reactive oxygen species (ROS) was assessed. The content of cardiac troponin I (cTn I), glutathione (GSH), malondialdehyde (MDA), divalent iron ions (Fe2+) and superoxide dismutase (SOD) were detected using reagent kits. A luciferase activity assay was performed to assess the binding ability of miR-450b-5p to ACSL4. Expressions of related genes and proteins were measured by RT-qPCR and western blotting respectively. EGCG attenuated AMI-induced ferroptosis and improved myocardial ischemia injury, which was associated with reducing iron deposition and cTn I, inhibition of lipid peroxidation, decreasing TFR1 and ACSL4, and upregulating SLC7A11, FTH1 and GPX4. Meanwhile, EGCG pretreatment increased miR-450b-5p expression in ischemic myocardium. Further researches discovered that knockdown of miR-450b-5p partially compromised EGCG-generated protective effect in hypoxia HL-1 cells, while combination with miR-450b-5p mimic could strengthen the potency of EGCG on ischemic myocardium. The dual-luciferase test demonstrated that miR-450b-5p has binding to ACSL4. Furthermore, silencing of ACSL4 synergistically increased the cardioprotective effect of EGCG. More significantly, EGCG treatment regulated the ferroptosis-related proteins expression via miR-450b-5p/ACSL4 axis. In summary, the present study evidently demonstrated that EGCG attenuates myocardial ischemia injury by targeting ferroptosis. Our work revealed the role of miR-450b-5p/ACSL4 axis in AMI for the first time. Further, it also elucidated the molecular mechanisms of EGCG on inhibiting ferroptosis greatly depend on the miR-450b-5p/ACSL4 axis, suggesting that EGCG may act as a novel anti-ferroptosis agent and exert a therapeutic role in AMI.

Yu Q ，Zhang N ，Gan X ，Chen L ，Wang R ，Liang R ，Jian J ... -  《-》

Hypoxia-elicited cardiac microvascular endothelial cell-derived exosomal miR-210-3p alleviate hypoxia/reoxygenation-induced myocardial cell injury through inhibiting transferrin receptor 1-mediated ferroptosis.

Ferroptosis is a novel mode of non-apoptotic cell death induced by build-up of toxic lipid peroxides (lipid-ROS) in an iron dependent manner, which is a key event in ischemia/reperfusion (I/R)-induced cardiomyocytes damages. Studies indicated that ischemic preconditioning with cardiac microvascular endothelial cells (CMECs) protected against I/R-induced cardiomyocytes damages. However, the role of hypoxia-conditioned CMECs-derived Exo (H-exo) in I/R cardiomyocytes damages remains largely unclear. Therefore, the objective of this study was to explore the role and underlying mechanisms of H-exo in hypoxia/reoxygenation(H/R)-induced H9C2 cells damages. The rat CMECs were subjected to hypoxia or normoxia culture and Exo was subsequently collected and identified. H-exo or normoxia-conditioned CMECs-derived Exo (N-exo) were administered to H9C2 cells with H/R. To evaluate the therapeutic effect of H-exo and H-exo on H/R-induced H9C2 cells damages, cell proliferation was detected by CCK-8 assay and Edu staining, and ferroptosis process were evaluated by iron ion concentration, lipid reactive oxygen species (ROS) level, malondialdehyde (MDA) level, glutathione peroxidase (GSH-Px) level, and the protein expression of ferroptosis markers. Mechanically, we utilized the RT-qPCR to identify the expression of candidate miR-210-3p in N-exo and H-exo. Bioinformatics combined with dual luciferase reporter assay disclosed the downstream molecular mechanism of miR-210-3p. The results indicated that both H-exo and N-exo significantly facilitated cell proliferation, increased GSH-Px levels and ferroptosis marker (GPX4) protein levels, and reduced iron ion concentration, lipid ROS level, MDA levels and ferroptosis markers (ACSL4 and PTGS2) protein levels in H/R-treated H9C2 cells. More importantly, the therapeutic effect of H-exo was significantly better than that of N-exo. Mechanistically, the results of RT-qPCR revealed significant enrichment of miR-210-3p in H-exo compared with N-exo. The miR-210-3p delivered by H-exo inhibited TFR expression by directly interacting with TFR mRNA, resulting in the promotion of cell proliferation and the attenuation of cell ferroptosis in H/R-treated H9C2 cells. All these data demonstrated that H-exo derived miR-210-3p facilitated the proliferation of myocardial cells in H/R-treated H9C2 cells by suppressing TFR-mediated ferroptosis, which provided new methods to treat H/R-induced myocardial injury.

Lei D ，Li B ，Isa Z ，Ma X ，Zhang B ... -  《-》

Human umbilical cord mesenchymal stem cells-derived exosomes transfers microRNA-19a to protect cardiomyocytes from acute myocardial infarction by targeting SOX6.

Huang L ，Yang L ，Ding Y ，Jiang X ，Xia Z ，You Z ... -  《-》

Long noncoding RNA UCA1 from hypoxia-conditioned hMSC-derived exosomes: a novel molecular target for cardioprotection through miR-873-5p/XIAP axis.

Sun L ，Zhu W ，Zhao P ，Wang Q ，Fan B ，Zhu Y ，Lu Y ，Chen Q ，Zhang J ，Zhang F ... -  《Cell Death & Disease》