TY - JOUR
T1 - Activation of Autophagic Flux Blunts Cardiac Ischemia/Reperfusion Injury
AU - Xie, Min
AU - Cho, Geoffrey W.
AU - Kong, Yongli
AU - Li, Dan L.
AU - Altamirano, Francisco
AU - Luo, Xiang
AU - Morales, Cyndi R.
AU - Jiang, Nan
AU - Schiattarella, Gabriele G.
AU - May, Herman I.
AU - Medina, Jessica
AU - Shelton, John M.
AU - Ferdous, Anwarul
AU - Gillette, Thomas G.
AU - Hill, Joseph A.
N1 - Funding Information:
This work was supported by grants from the National Institutes of Health (NIH), HL-120732 (J.A. Hill), HL-128215 (J.A. Hill), HL-126012 (J.A. Hill), HL-147933 (J.A. Hill), HL-155765 (J.A. Hill), American Heart Association (AHA), 14SFRN20510023 (J.A. Hill), 14SFRN20670003 (J.A. Hill), AHA 15POST22670003 (G.W. Cho), NIH T32-98040-4/5 (G.W. Cho), NIH K08-HL127305 (M. Xie), R03-HL141620 (M. Xie), HL153501 (M. Xie), AHA and the Theodore and Beulah Beasley Foundation 18POST34060230 (G.G. Schiat-tarella), AHA Postdoctoral fellowship 16POST30680016 (F. Altamirano), University Federico II of Naples, and the Compagnia di San Paolo STAR program (G.G. Schiattarella).
Publisher Copyright:
© 2021 Lippincott Williams and Wilkins. All rights reserved.
PY - 2021/7/23
Y1 - 2021/7/23
N2 - Rationale: Reperfusion injury accounts for up to half of myocardial infarct size, and meaningful clinical therapies targeting it do not exist. We have reported previously that autophagy is reduced during reperfusion and that HDAC (histone deacetylase) inhibition enhances cardiomyocyte autophagy and blunts ischemia/reperfusion (I/R) injury when administered at the time of reperfusion. However, whether inducing autophagy per se, as opposed to other effects triggered by HDAC inhibition, is sufficient to protect against reperfusion injury is not clear. Objective: We set out to test whether augmentation of autophagy using a specific autophagy-inducing peptide, TB (Tat-Beclin), protects the myocardium through reduction of reactive oxygen species (ROS) during reperfusion injury. Methods and Results: Eight- to 12-week-old, WT (wild type) C57BL6 mice and tamoxifen-inducible cardiomyocyte-specific ATG7 KO (ATG7 knockout) mice (to test the dependency on autophagy) were randomized into 2 groups: exposed to a control TS (Tat-scrambled) peptide or a TB peptide. Each group was subjected to I/R surgery (45-minute coronary ligation, 24-hour reperfusion). Infarct size, systolic function, autophagic flux, and ROS were assayed. Cultured neonatal rat ventricular myocytes were exposed to TB during simulated I/R injury. ATG7 knockdown by small interfering RNA in neonatal rat ventricular myocytes was used to evaluate the role of autophagy. TB treatment at reperfusion reduced infarct size by 20% (absolute reduction; 50% relative reduction) and improved contractile function. Improvement correlated with increased autophagic flux in the border zone with less oxidative stress. ATG7 KO mice did not manifest TB-promoted cardioprotection during I/R. In neonatal rat ventricular myocytes subjected to I/R, TB reduced cell death by 41% and reduced I/R-induced ROS generation. Conversely, ATG7 knockdown in neonatal rat ventricular myocytes abolished these beneficial effects of TB on cell death and ROS reduction. Conclusions: Induction of autophagy at the time of reperfusion is sufficient to mitigate myocardial reperfusion injury by reducing ROS and cell death. Maintenance of appropriate autophagic flux may emerge as a viable clinical therapy to reduce reperfusion injury in acute myocardial infarction. Graphic Abstract: A graphic abstract is available for this article.
AB - Rationale: Reperfusion injury accounts for up to half of myocardial infarct size, and meaningful clinical therapies targeting it do not exist. We have reported previously that autophagy is reduced during reperfusion and that HDAC (histone deacetylase) inhibition enhances cardiomyocyte autophagy and blunts ischemia/reperfusion (I/R) injury when administered at the time of reperfusion. However, whether inducing autophagy per se, as opposed to other effects triggered by HDAC inhibition, is sufficient to protect against reperfusion injury is not clear. Objective: We set out to test whether augmentation of autophagy using a specific autophagy-inducing peptide, TB (Tat-Beclin), protects the myocardium through reduction of reactive oxygen species (ROS) during reperfusion injury. Methods and Results: Eight- to 12-week-old, WT (wild type) C57BL6 mice and tamoxifen-inducible cardiomyocyte-specific ATG7 KO (ATG7 knockout) mice (to test the dependency on autophagy) were randomized into 2 groups: exposed to a control TS (Tat-scrambled) peptide or a TB peptide. Each group was subjected to I/R surgery (45-minute coronary ligation, 24-hour reperfusion). Infarct size, systolic function, autophagic flux, and ROS were assayed. Cultured neonatal rat ventricular myocytes were exposed to TB during simulated I/R injury. ATG7 knockdown by small interfering RNA in neonatal rat ventricular myocytes was used to evaluate the role of autophagy. TB treatment at reperfusion reduced infarct size by 20% (absolute reduction; 50% relative reduction) and improved contractile function. Improvement correlated with increased autophagic flux in the border zone with less oxidative stress. ATG7 KO mice did not manifest TB-promoted cardioprotection during I/R. In neonatal rat ventricular myocytes subjected to I/R, TB reduced cell death by 41% and reduced I/R-induced ROS generation. Conversely, ATG7 knockdown in neonatal rat ventricular myocytes abolished these beneficial effects of TB on cell death and ROS reduction. Conclusions: Induction of autophagy at the time of reperfusion is sufficient to mitigate myocardial reperfusion injury by reducing ROS and cell death. Maintenance of appropriate autophagic flux may emerge as a viable clinical therapy to reduce reperfusion injury in acute myocardial infarction. Graphic Abstract: A graphic abstract is available for this article.
KW - autophagy
KW - cardiomyopathies
KW - histone deacetylases
KW - ischemia
KW - reperfusion
KW - Myocardial Contraction
KW - Reactive Oxygen Species/metabolism
KW - Mice, Inbred C57BL
KW - Recombinant Proteins/pharmacology
KW - Cells, Cultured
KW - Myocytes, Cardiac/drug effects
KW - Rats
KW - Myocardial Reperfusion Injury/drug therapy
KW - Autophagy
KW - Rats, Sprague-Dawley
KW - Animals
KW - Beclin-1/pharmacology
KW - Autophagy-Related Protein 7/genetics
KW - Mice
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U2 - 10.1161/CIRCRESAHA.120.318601
DO - 10.1161/CIRCRESAHA.120.318601
M3 - Article
C2 - 34111934
SN - 0009-7330
VL - 129
SP - 435
EP - 450
JO - Circulation Research
JF - Circulation Research
IS - 3
ER -