Abstract 19706: CD39/CD73 Pathway in End-stage Human Ischemic Cardiomyopathy

Abstract

Introduction: CD39 (ectonucleoside triphosphate diphosphohydrolase) is a nucleotidase expressed on endothelial cells, vascular smooth muscles cells, and leukocytes. CD39 plays a key role in vascular homeostasis, hydrolyzing extracellular ATP or ADP to AMP. CD73 (ecto-5’-nculeotidase) hydrolyzes AMP to adenosine. Both CD39 and CD73 are key modulators of purinergic signaling and have been shown to be important in ischemic preconditioning and ischemia reperfusion in animal models. Hypothesis: We hypothesized that the expression of the purine nucleotide-metabolizing pathway consisting of CD39 and CD73 in human hearts with ischemic cardiomyopathy is unregulated in response to ischemia. Methods: We compared the expression of CD39 and CD73 in left ventricular samples from patients with end-stage ischemic cardiomyopathy and normal hearts. Left ventricular tissue obtained from 7 end-stage ischemic cardiomyopathy hearts and 7 normal hearts not used for transplantation were homogenized and the levels of CD39 and CD73 mRNA were measured by qRT-PCR. Using the same tissue, immunoblot analysis for the protein level of CD39 and CD73 was conducted. Furthermore, immunohistochemical analysis of CD39 and CD73 expression was conducted on left ventricular tissue from the same subjects. Results: The total mRNA levels of CD39 and CD73 were increased in patients with end-stage ischemic cardiomyopathy. However, while there was a reduction in the total CD73 protein levels that did not reach significance, there was a marked reduction in the the total protein level of CD39 in ICM hearts (Figure). Immunohistochemical analysis demonstrated that the expression pattern of CD39 was significantly different in ICM hearts compared to normal hearts. Conclusions: These data provide important evidence that the extracellular nucleotide metabolizing pathway is altered in ICM. CD39 protein levels are significantly reduced in human end-stage ischemic cardiomyopathy.