Upregulation of Ecto-5′-Nucleotidase by Rosuvastatin Increases the Vasodilator Response to Ischemia

Abstract

Abstract-3-Hydroxy-3-methyl-glutaryl-coenzyme A reductase inhibitors (statins) are effective in the primary and secondary prevention of cardiovascular events. Although originally developed to improve lipid profile, statins have demonstrated a surplus of beneficial pleiotropic effects, including improved endothelial function, reduced inflammation, and increased tolerance to ischemia-reperfusion injury. In preclinical studies, increased ecto-5Ј-nucleotidase activity, the key enzyme in extracellular adenosine formation, plays an important role in these effects. Because human data are absent, we explored the effects of rosuvastatin on ecto-5Ј-nucleotidase activity and the clinical relevance of increased extracellular adenosine during ischemia in humans in vivo. The forearm vasodilator responses to 3 increasing periods of forearm ischemia (2, 5, and 13 minutes) were determined during placebo and caffeine (an adenosine receptor antagonist) infusion into the brachial artery. At the end of an 8-day treatment period with rosuvastatin (20 mg per day), this whole procedure was repeated. During both experiments, ecto-5Ј-nucleotidase activity was determined. Vasodilator responses are expressed as the percentage increase in forearm blood flow ratio from baseline. Rosuvastatin increased ecto-5Ј-nucleotidase activity by 49Ϯ17% and enhanced the vasodilator response after 2, 5, and 13 minutes of ischemia in the absence (146Ϯ19, 330Ϯ26, and 987Ϯ133 to 312Ϯ77, 566Ϯ107, and 1533Ϯ267) but not in the presence of caffeine ( Key Words: adenosine Ⅲ ecto-5Ј-nucleotidase Ⅲ caffeine Ⅲ ischemia Ⅲ reactive hyperemia 3 -Hydroxy-3-methyl-glutaryl-coenzyme A reductase inhibitors (statins) are effective in the primary and secondary prevention of cardiovascular events. 1,2 Although originally developed to improve lipid profile, statins have demonstrated a surplus of beneficial pleiotropic effects, including improved endothelial function, reduced inflammation, and increased tolerance to ischemia-reperfusion injury. [3][4][5][6][7] These effects are independent of plasma cholesterol lowering and improve outcome after cardiovascular events. 8,9 Increased extracellular adenosine formation has been implicated as one of the underlying mechanisms. This is supported by several preclinical studies demonstrating the activation of ecto-5Ј-nucleotidase (CD73) activity, increased stimulation of adenosine receptors, and adenosine-mediated protection against ischemia-reperfusion injury by statins. 10 -12 The enzyme CD73 dephosphorylates extracellular AMP, which forms the rate-limiting step in the formation of extracellular adenosine. 13 We recently demonstrated increased extracellular adenosine formation in healthy human volunteers after a 1-week treatment with rosuvastatin using a pharmacological approach. In addition, we demonstrated rosuvastatin-induced augmentation of postocclusive reactive hyperemia (PORH). 5 However, we did not assess CD73 activity as a potential source of extracellular adenosine, nor did we investigate the role of adenosine in rosuvasta...

How systemic inflammation modulates adenosine metabolism and adenosine receptor expression in humans in vivo

“…Only recently, Haskó and co-workers (21) demonstrated that ecto-5NT decreases mortality and organ injury during murine sepsis. Interestingly, recent studies in animals and in humans in vivo have shown that statins cause an activation of ecto-5NT activity (14,22,23). Furthermore, it was recently demonstrated that the use of statins during intensive care unit stay reduces hospital mortality (24), but whether an increase in extracellular adenosine accounts for the survival benefit needs to be further explored.…”

“…Enzyme activity assays for ADA, AK, and ecto-5NT were performed as previously described (13,14). In summary, PBMCs were washed three times in sterile PBS.…”

5'-Nucleotidases, Nucleosides and their Distribution in the Brain: Pathological and Therapeutic Implications

“…Focal ischemia also increased the activ-ity of cerebroprotective e5'NT, which may increase the levels of neuroprotective Ado [63,118,126,344,345]. Rosuvastatin increased the extracellular levels of Ado via an enhancement of e5'NT activity and, as a consequence, increased the vasodilatator response to ischemia [346]. Upregulation of e5'NT activity was also demonstrated in models of brain damage, such as the cortical stub injury [347,348].…”

Short-term Statin Treatment Does Not Prevent Ischemia and Reperfusion-induced Endothelial Dysfunction in Humans

“…Previous studies demonstrated that statins (3-hydroxy-3-methylglutarylcoenzyme A reductase inhibitors) reduce serum low-density lipoprotein (LDL) cholesterol, which is associated with a significant reduction in cardiovascular events. [1][2][3][4] Statins also have cholesterol-independent pleiotropic effects, such as upregulation of ecto-59-nucleotidase, [5][6][7][8] activation of the phosphatidylinositol 3-kinase-Akt pathway, 9 activation of the ERK 1/2 pathway 10 and upregulation of nitric oxide (NO) synthase. 11,12 These pleiotropic actions may contribute to the cardioprotective effects of statins, such as an improved tolerance against ischemia and reperfusion injury (IR injury).…”