Imaging of receptors for advanced glycation end products in experimental myocardial ischemia and reperfusion injury

Abstract

Objectives: The aim of this study was to image expression of receptor for advanced glycation end products (RAGE) in a mouse model of myocardial reperfusion injury.

Background: RAGE and its ligands are implicated in the pathogenesis of ischemia/reperfusion injury and infarction. We hypothesized that RAGE-directed quantitative imaging of myocardial uptake of technetium-99m ((99m)Tc)-anti-RAGE F(ab')(2) in a mouse model of myocardial ischemic injury can detect RAGE expression and show quantitative differences between early (18 to 20 h) and later times (48 h) after reperfusion.

Methods: Twenty-five wild-type (WT) mice underwent left anterior descending coronary artery occlusion for 30 min. Mice were injected with 19.98 ± 1.78 MBq of (99m)Tc anti-RAGE F(ab')(2) at 2 time points after reperfusion (at 18 to 20 h [n = 8] and at 48 h [n = 12]) and 5 h later with 6.14 ± 2.0 MBq of thallium-201 ((201)Tl). Five WT mice were injected with nonspecific F(ab')(2) and (201)Tl 18 to 20 h after reperfusion. Six WT mice underwent sham operation without coronary intervention. After injection with (201)Tl, all mice immediately underwent dual isotope single-photon emission computed tomography/computed tomography. At completion of imaging, hearts were counted and sectioned.

Results: The uptake of (99m)Tc-anti-RAGE F(ab')(2) in the ischemic zone from the scans as mean percentage injected dose was significantly greater at 18 to 20 h (5.7 ± 2.1 × 10(-3)%) as compared with at 48 h (1.4 ± 1.1 × 10(-3)%; p < 0.001) after reperfusion. Disease and antibody controls showed no focal uptake in the infarct. Gamma well counting of the myocardium supported the quantitative scan data. By immunohistochemical staining there was greater caspase-3 and RAGE staining at 18 to 20 h versus at 48 h (p = 0.04 and p = 0.01, respectively). On dual immunofluorescence, RAGE colocalized mainly with injured cardiomyocytes undergoing apoptosis.

Conclusions: RAGE expression in myocardial ischemic injury can be imaged in vivo using a novel (99m)Tc-anti-RAGE F(ab')(2). RAGE plays a role in several cardiovascular diseases and is a potential target for clinical imaging.