Overexpression of Human Copper/Zinc Superoxide Dismutase (SOD1) Suppresses Ischemia–Reperfusion Injury and Subsequent Development of Graft Coronary Artery Disease in Murine Cardiac Grafts

BACKGROUND: Ischemia-reperfusion injury is an important risk factor for graft coronary artery disease (GCAD). We hypothesized that overexpression of SOD1 in donor hearts would suppress ischemia-reperfusion injury and thereby reduce GCAD. METHODS AND RESULTS: In one series, donor hearts of C57BL/6 (H-2b) transgenic mice overexpressing human SOD1 or C57BL/6 wild-type mice were heterotopically transplanted into C57BL/6 recipients and procured after 4 hours of reperfusion (n=6 each). Superoxide, TNF-alpha, and MCP-1/CCL2 production were significantly reduced in the SOD1 transgenic donor heart recipients, and graft injury determined by serum CPK-MB levels was significantly decreased. Cardiomyocyte apoptosis and caspase-3 and caspase-9 activities were significantly decreased in these recipients; caspase-8 activity was unchanged. Fas ligand but not Fas expression was also reduced. In a second series, transgenic and wild-type hearts were transplanted into C-H-2bm12KhEg (H-2bm12) recipients, and then procured on day 56 (n=7 each). Cardiac graft beating was significantly better in the SOD1 transgenic donor heart recipients on days 28, 42, and 56 (but not day 14). Significant reduction in luminal narrowing, the intima/media ratio, and the percentage of diseased vessels was seen in the SOD1 transgenic donor heart recipients, and MCP-1/CCL2, ICAM-1, and VCAM-1 production were significantly reduced. CONCLUSIONS: Overexpression of SOD1 attenuates both apoptosis and the inflammatory response during ischemia-reperfusion injury and therefore mitigates against the subsequent development of GCAD.