Abstract 15278: Cell-free DNA Released From Ischemic Myocardium Contributes Importantly to Myocardial Reperfusion Injury
Introduction: Increasing evidence shows that damage associated molecular patterns (DAMPs) such as cell-free DNA (cfDNA) may play critical roles in mediating ischemia/reperfusion injury (IRI).
Hypothesis: cfDNA, released from ischemic myocardium during reperfusion, activates splenic leukocytes to exacerbate reperfusion injury.
Methods: C57BL6 mice underwent 10, 20 or 40 min occlusions of the left coronary artery followed by up to 60 min of reperfusion. Plasma cfDNA was measured using Sytox Green. Cardiac perfusate and ischemic heart homogenate (IHH) were acquired from 40 min (40-IHH) ischemic hearts without reperfusion. Plasma was acquired from mice undergoing 40 min of occlusion followed by 5 min of reperfusion. Mitochondrial DNA (mtDNA) was acquired from livers of normal C57BL6 mice. Myocardial infarct size (IS) is reported as % risk region (RR), as measured by TTC-Phthalo blue staining.
Results: Levels of plasma cfDNA were low and comparable among sham, 10’/30’ (I/R), and 40’/0’ mice. Plasma cfDNA significantly increased in 40’/30’ mice (>10 fold, p<0.05). In mice undergoing 40’/60’ IRI, IS in control mice was 56.9±3.5%. DNase I (30 mU/g bw) injected i.v. 5 min before reperfusion reduced IS by half (to 29.0±5.2%, p<0.05) vs. control. In mice undergoing 20’/60’ IRI (Figure), IS in control mice was 5.3±1.4%. Injection of 40-IHH protein (10 μg/g bw) i.v. 5 min before reperfusion increased IS by 4-fold (to 21.3±2.1%, p<0.05). Injection of perfusate from 40 min ischemic hearts similarly increased IS. Plasma obtained from mice undergoing 40’/5’ IRI (injected i.v. 5 min before reperfusion) increased IS by >3-fold (to 19.9±4.3, p<0.05). The increase in IS was abrogated by splenectomy (SPLX) or DNase I (1 mU). Exogenous mtDNA injected i.v. 5 min before reperfusion increased IS (to 16.1±5.1%), comparable to 40-IHH or plasma.
Conclusion: Cell-free DNA, likely mtDNA, released from the ischemic heart contributes importantly to reperfusion injury by activating the spleen.
Author Disclosures: Y. Tian: None. E.J. Charles: None. I.L. Kron: None. B.A. French: None. Z. Yang: None.
- © 2016 by American Heart Association, Inc.