Chimeric SOD2/3 inhibits at the endothelial-neutrophil interface to limit vascular dysfunction in ischemia-reperfusion

Abstract

After an ischemic episode, reperfusion causes profound oxidative stress in the vasculature of the afflicted tissue/organ. The dysregulated accumulation of reactive oxygen species (ROS), such as superoxide, has been closely linked to the production and release of proinflammatory mediators, a profound increase in adhesion molecule expression by the vascular endothelium, and infiltration of neutrophils during ischemia-reperfusion (I/R). Superoxide dismutase (SOD) has been shown to protect tissues and organs against I/R-induced injury; however, the drug had to be continuously perfused or kidneys had to be occluded to prevent clearance. We used intravital microscopy, a system that allowed us to visualize neutrophil-endothelial interactions within the mesenteric postcapillary venules of cats subjected to I/R and tested the hypothesis that I/R-induced neutrophil recruitment was inhibited by treatment with SOD2/3. SOD2/3 is a chimeric fusion gene product that contains the mature SOD2 as well as the COOH-terminal “tail” of SOD3 and, unlike the three naturally occurring SODs (SOD1, SOD2, and SOD3), which bear a net negative charge at pH 7.4, SOD2/3 is positively charged and physiologically stable. Our results suggest that not only does SOD2/3 have a much greater efficacy in vivo than the native human SOD2, but its administration prevents I/R-induced neutrophil-endothelial cell interactions and microvascular dysfunction. Moreover, our data support the hypothesis that reactive oxidants mediate I/R-induced injury and that the chimeric recombinant SOD2/3 has the potential to be a therapeutic agent against this debilitating illness.

Platelet-Endothelial Cell Adhesion Molecule-1-Directed Endothelial Targeting of Superoxide Dismutase Alleviates Oxidative Stress Caused by Either Extracellular or Intracellular Superoxide

“…For example, lecithinized SOD was shown to have increased affinity to endothelial cells (Igarashi et al, 1994;Koo et al, 2001). Chimeric SOD2/3 was synthesized as a fusion gene product of mitochondrial MnSOD (SOD2) and C-terminal heparin-binding tail of EC-SOD (SOD3) that delivered SOD activity to heparan sulfates of cellular surface (Gao et al, 2003;Bonder et al, 2004). Recently, a fusion protein that consists of bacterial Fe-SOD and single-chain variable fragment LC-1 anti-lung adenocarcinoma antibody was shown to keep the activities of both enzymatic and affinity moieties (Lu et al, 2006).…”

“…Xanthine oxidase released into the bloodstream due to tissue injury may lead to endothelial attack by extracellular superoxide, hence direct (patho)-physiological relevance of this model. Other scenarios in which endothelial cells are exposed to external superoxide attack include ROS generation by activated leukocytes via NADPH-oxidase pathway (Cai et al, 2003;Bonder et al, 2004). Anti-PECAM/SOD, but not unconjugated SOD, provided significant and marked protection against both apoptosis and necrosis caused by xanthine oxidase exposure (Figs.…”

Superoxide dismutases and their impact upon human health

“…The same chimera was also effective at decreasing the oxidative damage ensuing reperfusion in cats. In this recent study, Bonder et al (2004), showed that SOD2/3 decreased the amount of neutrophil-endothelial cell interaction that under controlled conditions typically led to microvascular dysfunction.…”

Improved Outcomes in Islet Isolation and Transplantation by the Use of a Novel Hemoglobin-based O2 Carrier

“…Ischemia renders cells more susceptible to oxidative stress by impairing mitochondrial antioxidant defenses (9). Providing O 2 to ischemic tissue has been shown to be a 'double-edged sword' due to reperfusion injury (10)(11)(12)(13). Reactive oxygen species (ROS) produced by mitochondria play a significant part in this type of injury.…”