Soluble RAGE attenuates myocardial I/R injury by suppressing interleukin-6

Background Inflammatory responses play a central role in myocardial ischemia/reperfusion (I/R) injury. Previous studies have demonstrated that the receptor for advanced glycation end-products (RAGE) is involved in the pro-inflammatory process of myocardial I/R injury by binding to diverse ligands. Thus, the inhibitory effects of soluble receptor for advanced glycation end-products (sRAGE), a decoy receptor for RAGE, on myocardial I/R injury may be associated with a reduced inflammatory state. Methods In this study, plasma levels of several inflammatory mediators were measured in patients with acute myocardial infarction (AMI) and I/R-treated cardiomyocyte-specific sRAGE knock-in (sRAGE-CKI) mice. Cardiac function, infarct size, and macrophage phenotypes were examined and documented in mouse hearts. Results We enrolled 38 patients diagnosed with myocardial infarction (AMI) [mean age, 58.81 ± 10.40 years] and 26 control with negative coronary arteriographic findings [mean age, 61.84 ± 8.57 years]. The results showed that sRAGE levels were significantly elevated in the AMI patient group compared with the control group (1905.00 [1462.50, 2332.5] vs 1570.00 [1335.00, 1800.00] pg/mL, p < 0.05), which were negatively correlated with interleukin (IL)-1, IL-6, and IL-8 levels. Cardiac-specific overexpression of sRAGE dramatically improved cardiac function and reduced infarct size during myocardial I/R. Furthermore, sRAGE overexpression decreased the plasma IL-6 levels and pro-inflammatory iNOS+ M1-macrophages, and increased CD206+ M2-macrophages in the mouse hearts. Conclusions Our findings suggested that sRAGE protects the heart from myocardial I/R injury by inhibiting the infiltration of pro-inflammatory M1-macrophages, and subsequently decreasing IL-6 secretion.