Pharmacologic Prevention of Myocardial Ischemia-Reperfusion Injury in Patients With Acute Coronary Syndrome Undergoing Percutaneous Coronary Intervention

Effect and mechanisms of dexmedetomidine combined with macrophage migration inhibitory factor inhibition on the expression of inflammatory factors and AMPK in mice

Reperfusion after acute myocardial infarction can cause ischemia/reperfusion (I/R) injury, which not only impedes restoration of the functions of tissues and organs but may also aggravate structural tissue and organ damage and dysfunction, worsening the patient's condition. Thus, the mechanisms that underpin myocardial I/R injury need to be better understood. We aimed to examine the effect of dexmedetomidine on macrophage migration inhibitory factor (MIF) in cardiomyocytes from mice with myocardial I/R injury and to explore the mechanistic role of adenosine 5'-monophosphate-activated protein kinase (AMPK) signaling in this process. Myocardial I/R injury was induced in mice. The expression of serum inflammatory factors, reactive oxygen species (ROS), adenosine triphosphate (ATP), and AMPK pathway-related proteins, as well as myocardial tissue structure and cell apoptosis rate, were compared between mice with I/R injury only; mice with I/R injury treated with dexmedetomidine, ISO-1 (MIF inhibitor), or both; and sham-operated mice. Dexmedetomidine reduced serum interleukin (IL)-6 and tumor necrosis factor-α concentrations and increased IL-10 concentration in mice with I/R injury. Moreover, dexmedetomidine reduced myocardial tissue ROS content and apoptosis rate and increased ATP content and MIF expression. MIF inhibition using ISO-1 reversed the protective effect of dexmedetomidine on myocardial I/R injury and reduced AMPK phosphorylation. Dexmedetomidine reduces the inflammatory response in mice with I/R injury and improves adverse symptoms, and its mechanism of action may be related to the MIF-AMPK pathway.

Evaluating the role of intravenous pentoxifylline administration on primary percutaneous coronary intervention success rate in patients with ST-elevation myocardial infarction (PENTOS-PCI)

Ischemia reperfusion injury can lead to further myocardiocyte damage in patients with ST-elevation myocardial infarction (STEMI). Pentoxifylline is a methylxanthine derivative with known anti-inflammatory, antioxidant, vasodilator, and rheological properties which can be a promising agent in preventing reperfusion injury. PENTOS-PCI is a single-center, randomized, double-blind, placebo-controlled trial which evaluated the efficacy and safety of preprocedural administration of intravenous pentoxifylline in patients undergoing primary percutaneous coronary intervention (PCI). Patients with acute STEMI who were eligible for PCI were randomized to receive either 100-mg intravenous infusion of pentoxifylline or placebo, prior to transferring to catheterization laboratory. Overall, 161 patients were included in our study of whom 80 patients were assigned to pentoxifylline and 81 to the control groups. Per-protocol analysis of primary endpoint indexing PCI's success rate as measured by thrombolysis in myocardial infarction (TIMI) flow grade 3 was not significantly different between pentoxifylline and placebo (71.3% and 66.3% respectively, P = 0.40). In addition, pentoxifylline could not improve secondary angiographic endpoints including myocardial blush grade 3 (87.5% and 85.2%, P = 0.79) and corrected TIMI frame count (22.8 [± 9.0] and 24.0 [± 5.1], P = 0.33) in the intervention and placebo groups respectively. The rates of major adverse cardiac and treatment emergent adverse effects were not significantly different between the two groups. Administration of intravenous pentoxifylline before primary PCI did not improve the success rate of the procedure in patients with STEMI. Intravenous administration of pentoxifylline was well tolerated, and there were no significant differences regarding adverse drug reactions in the two groups. Panel A, background: pentoxifylline is a methylxanthine derivative with known anti-inflammatory, antioxidant, vasodilator, and rheological properties which can be a promising agent in preventing reperfusion injury. Panel B: study design and main results of the PENTOS-PCI trial. cTFC corrected TIMI frame count, ED emergency department, IRI ischemia reperfusion injury, MBG myocardial blush grade, PCI percutaneous coronary intervention, PPCI primary PCI, PTX pentoxifylline, ROS reactive oxygen species, SD standard deviation, STEMI ST-elevation myocardial infarction, TIMI thrombolysis in myocardial infarction.

Ginsenoside Rh2 attenuates myocardial ischaemia‑reperfusion injury by regulating the Nrf2/HO‑1/NLRP3 signalling pathway

Ginsenoside Rh2 (GRh2) is a monomer isolated from red ginseng that has extensive pharmacological effects. However, whether GRh2 has a protective effect on ischaemia/reperfusion (I/R) in the myocardium has yet to be elucidated. The present study aimed to identify the anti-inflammatory and antioxidant effects of GRh2 on I/R in the myocardium and its underlying mechanism. A rat model of myocardial I/R injury was constructed by ligating the left anterior descending coronary artery, which was subsequently treated with GRh2. A total of 40 male Sprague-Dawley rats were divided into the following four groups: The sham group, the I/R group, the I/R+GRh2 (10 mg/kg) group and the I/R+GRh2 (20 mg/kg) group. Neonatal rat cardiomyocytes were also used to evaluate the protective effect of GRh2 on hypoxia/reoxygenation (H/R)-induced myocardial injury in vitro. The GRh2 pre-treatment reduced the I/R- or H/R-induced release of myocardial enzymes and the production of IL-1β, IL-18 and TNF-α. GRh2 reduced the area of myocardial infarction and the histological changes in the myocardium and improved cardiac functions. In addition, GRh2 reduced the expression levels of NOD-like receptor family pyrin domain-containing 3 (NLRP3), apoptosis-associated speck-like protein, caspase-1, malondialdehyde and reactive oxygen species and increased the expression levels of nuclear factor E2-related factor 2 (Nrf2), heme oxygenase-1 (HO-1), glutathione peroxidase and superoxide dismutase. In conclusion, the present study confirmed that GRh2 could reduce oxidative stress and inflammation in cardiomyocytes after reperfusion, and its mechanism of action may be related to its regulation of the Nrf2/HO-1/NLRP3 signalling pathway.

Cathepsin B/HSP70 complex induced by Ilexsaponin I suppresses NLRP3 inflammasome activation in myocardial ischemia/reperfusion injury

BACKGROUND

Myocardial ischemia/reperfusion injury (MI/RI) is a clinical issue in MI therapy that requires effective intervention. Cathepsin B (CTSB) plays an essential role in regulating cell death, inflammatory response and angiogenesis. Ilexsaponin I (ISI), a triterpenoid saponin obtained from Ilex pubescens Hook. et Arn, has anti-inflammatory and cardioprotective effects. However, the effect of ISI on MI/RI is unclear.

PURPOSE

The study aims to disclose the mechanism of ISI as a potent therapeutic agent for MI/RI.

METHODS

Left anterior descending (LAD) coronary artery ligation and oxygen-glucose deprivation and reperfusion (OGD/R) were used to establish MI/RI model in vivo and in vitro. ELISA, western blot and immunofluorescence were carried out to detect CTSB activity and NLRP3 inflammasome activation. Coimmunoprecipitation (Co-IP), molecular docking and surface plasmon resonance (SPR) analysis were used to detect the interaction of CTSB/HSP70 complex. Infarct area determination, echocardiography and hematoxylin and eosin (HE) staining were performed to assess the cardioprotection of ISI in vivo.

RESULTS

Plasma CTSB was elevated in patients after percutaneous coronary intervention (PCI), and was positively correlated with the level of cTnI in plasma, which was also found in MI/RI rat model. ISI significantly suppressed the overexpression and activity of CTSB after MI/RI or OGD/R. ISI remarkably suppressed CTSB triggered-NLRP3 inflammasome activation and reduced the maturation of IL-1β and IL-18. Importantly, we firstly found that ISI promoted CTSB/HSP70 complex formation to disrupt CTSB/NLRP3 complex, leading to NLRP3 inflammasome inactivation. ISI could also limit infarct size, improve cardiac function and reduce inflammatory infiltrates in vivo and protected H9c2 cells against OGD/R insult in vitro. Interrupting the HSP70 and CTSB interaction with HSP70 siRNA blocked the effect of ISI on CTSB, NLRP3 inflammasome activation and the cardioprotective effect.

CONCLUSION

ISI probably exerts cardioprotective effect against MI/RI by modulating HSP70 competitively bind to CTSB to suppress the activation of the NLRP3 inflammasome.

Polyphyllin I improves myocardial damage in coronary artery disease via modulating lipid metabolism and myocardial apoptosis

Polyphyllin I (PPI) is a famous traditional medicine ingredient, which has been explored in wide range of areas. Nevertheless, whether PPI exerts any functions in coronary artery disease (CAD) is still uncertified. Herein, we probed the effect and mechanism of PPI on lipid metabolism and myocardial dysfunction in myocardial cells and CAD rat model. Hypoxia/reoxygenation (H/R)-treated H9c2 cells model was constructed for the in vitro experiments, and CAD model in vivo was established by high-fat feeding. After management with PPI, the correlated factors of lipid metabolism and myocardial function were investigated. The apoptosis of myocardial cells was assessed by Annexin V-FITC/PI kit and TUNEL staining. The apoptosis-associated factors (caspase 3, cleaved caspase 3, Bax, and Bcl-2) were tested by Western blot analysis. The MEK/ERK inhibitor was applied and the functions of MEK/ERK pathway in myocardial damage were investigated. H/R-treated H9c2 cells model was constructed for the in vitro experiments, and CAD model in vivo was established by high-fat feeding. After management with PPI, the correlated factors of lipid metabolism and myocardial function were investigated. The apoptosis of myocardial cells was assessed by Annexin V-FITC/PI kit and TUNEL staining. The apoptosis-associated factors (caspase 3, cleaved caspase 3, Bax, and Bcl-2) were tested by Western blot analysis. The MEK/ERK inhibitor was applied and the functions of MEK/ERK pathway in myocardial damage were investigated. PPI improved lipid metabolism disorder in H/R-induced H9c2 cells or in CAD rat model. Additionally, PPI attenuated myocardial dysfunction in CAD rats via enhancing left ventricular systolic pressure, maximum rate of change of left ventricular pressure (±dp/dt_max ), and arterial blood flow (CF). The apoptosis of myocardial cells was lessened by PPI management, which was further verified by reducing Bax and cleaved caspase 3 expression. Furthermore, PD0325901 (MEK/ERK inhibitor) weakened the effect of PPI on myocardial dysfunction, lipid metabolism, and myocardial cell apoptosis in CAD rats. The research confirmed the protective effect of PPI on myocardial damage in CAD, which was regulated by MEK/ERK pathway.

Empagliflozin attenuates cardiac microvascular ischemia/reperfusion through activating the AMPKα1/ULK1/FUNDC1/mitophagy pathway

Mitophagy preserves microvascular structure and function during myocardial ischemia/reperfusion (I/R) injury. Empagliflozin, an anti-diabetes drug, may also protect mitochondria. We explored whether empagliflozin could reduce cardiac microvascular I/R injury by enhancing mitophagy. In mice, I/R injury induced luminal stenosis, microvessel wall damage, erythrocyte accumulation and perfusion defects in the myocardial microcirculation. Additionally, I/R triggered endothelial hyperpermeability and myocardial neutrophil infiltration, which upregulated adhesive factors and endothelin-1 but downregulated vascular endothelial cadherin and endothelial nitric oxide synthase in heart tissue. In vitro, I/R impaired the endothelial barrier function and integrity of cardiac microvascular endothelial cells (CMECs), while empagliflozin preserved CMEC homeostasis and thus maintained cardiac microvascular structure and function. I/R activated mitochondrial fission, oxidative stress and apoptotic signaling in CMECs, whereas empagliflozin normalized mitochondrial fission and fusion, neutralized supraphysiologic reactive oxygen species concentrations and suppressed mitochondrial apoptosis. Empagliflozin exerted these protective effects by activating FUNDC1-dependent mitophagy through the AMPKα1/ULK1 pathway. Both in vitro and in vivo, genetic ablation of AMPKα1 or FUNDC1 abolished the beneficial effects of empagliflozin on the myocardial microvasculature and CMECs. Taken together, the preservation of mitochondrial function through an activation of the AMPKα1/ULK1/FUNDC1/mitophagy pathway is the working mechanism of empagliflozin in attenuating cardiac microvascular I/R injury.

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Empagliflozin reduces I/R-induced microvascular damage.

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Empagliflozin suppresses I/R-induced endothelial cell damage.

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Empagliflozin activates FUNDC1-dependent mitophagy through the AMPKα1/ULK1 pathway.

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Ablation of FUNDC1 or AMPKα1 abolishes the protective effects of empagliflozin against I/R-induced microvascular damage.

Leucine induces cardioprotection in vitro by promoting mitochondrial function via mTOR and Opa-1 signaling

BACKGROUND AND AIMS

Coronary heart disease is a major global health concern. Further, severity of this condition is greatly influenced by myocardial ischemia/reperfusion (I/R) injury. Branched-chain amino acids (BCAAs) have cardioprotective effects against I/R via mammalian target of rapamycin (mTOR) activity, wherein Leu is considered to particularly regulate mTOR activation. However, the mechanism underlying cardioprotective effects of Leu via mTOR activity is not fully elucidated. Here, we aimed to study the signaling pathway of cardioprotection and mitochondrial function induced by Leu treatment.

METHODS AND RESULTS

Cardiac myocytes isolated from adult male Wistar rats were incubated and exposed to simulated I/R (SI/R) injury by replacing the air content. Cardiac myocytes were treated with Leu and subsequently, their survival rate was calculated. To elucidate the signaling pathway and mitochondrial function, immunoblots and mitochondrial permeability transition pore were examined. Cell survival rate was decreased with SI/R but improved by 160 μM Leu (38.5 ± 3.6% vs. 64.5 ± 4.2%, respectively, p < 0.001). Although rapamycin (mTOR inhibitor) prevented this cardioprotective effect induced by Leu, wortmannin (PI3K inhibitor) did not interfere with this effect. In addition, we indicated that overexpression of Opa-1 and mitochondrial function are ameliorated via Leu-induced mitochondrial biogenesis. In contrast, knockdown of Opa-1 suppressed Leu-induced cardioprotection.

CONCLUSION

Leu treatment is critical in rendering a cardioprotective effect exhibited by BCAAs via mTOR signaling. Furthermore, Leu improved mitochondrial function.