Increased plasma levels of osteopontin are associated with activation of the renin-aldosterone system and with myocardial and coronary microvascular damage in dilated cardiomyopathy

In patients with dilated cardiomyopathy (DCM) abnormal myocardial blood flow (MBF) has been associated with coronary microvascular dysfunction. The aim of this study was to test the hypothesis that osteopontin (OPN) plasma levels could be associated with the activation of the renin-aldosterone system (RAS) in these patients and be involved in mediating myocardial and coronary damage. In 66 patients with idiopathic left ventricular dysfunction of variable severity the plasma levels of OPN were correlated with biomarkers of systemic metabolism, RAS activation, myocardial dysfunction and with clinical indexes of left ventricle (LV) function and perfusion obtained by 2D-echocardiography and PET. As compared to controls, patients showed a significant increase of inflammatory markers (OPN: 508+/-30.8ng/ml vs. 426.9+/-16.4, p<0.05 and interleukin (IL)-6: 1.71+/-0.29pg/ml vs. 0.38+/-0.03pg/ml, p<0.001) and of indexes of cardiac damage. OPN levels were significantly correlated with the extent of microvascular dysfunction (MBF at rest: p=0.01; during dipyridamole: p=0.0003) and with plasma renin activity (PRA) (r=0.26, p=0.04). Both in patients with milder or more severe LV dysfunction lower MBF values were associated with higher OPN levels and PRA. These results suggest a interdependent role of RAS and vascular inflammation in cardiomyopathy.