Abstract 506: The Effect of Human Recombinant DNase-1 Treatment on Skeletal Muscle Ischemia Reperfusion Injury

Abstract

Objective Nucleosomes are known to exacerbate tissue injury, thus exogenous DNase-1 has been suggested as a novel therapeutic strategy to limit tissue injury in a stroke model. Our aim was to assess the effect of recombinant DNase-1 treatment on skeletal muscle fiber injury, tissue inflammation and levels of circulating nucleosomes in a mouse model of hind limb ischemia-reperfusion-injury (IR). Methods C57BL6 mice were subjected to IR (1.5hr Ischemia/24hr Reperfusion) or sham conditions. Mice were treated with either 50μg DNase-1 IP every 6 hours (DNase-1) or buffer (Control) at the same time intervals. Sham mice were anesthetized for 1.5 hours and allowed to recover for 24 hours. Muscles were harvested to quantify muscle fiber injury, DNAse-1 protein and calcium dependent endonuclease activity. Muscle markers of inflammation Myeloperoxidase (MPO), Keratinocyte chemoattractant (KC) and Plasma nucleosomes were quantified. Results Skeletal muscle fiber injury (numbers p<0.05) and endonuclease activity (numbers p<0.001) were greater in the DNase-1 group compared to control and sham. DNase-I localized predominantly to the extracellular matrix and severely injured muscle fibers. There was no significant difference in the plasma levels of nucleosomes or markers of inflammation (MPO or KC). Conclusions These novel findings suggest that in contrast to brain IR, hind limb IR increases DNAse-1 activity, and that exogenous treatment with DNase-1 exacerbates muscle injury independent of markers of inflammation. DNase-1 may be a therapeutic target that warrants further investigation. Table to Be Inserted