Involvement of Apelin/APJ Axis in Thrombogenesis in Valve Heart Disease Patients with Atrial Fibrillation.

The mechanism underlying thrombosis in atrial fibrillation (AF) is not yet clearly understood. The apelin/APJ axis parallel and counter-regulate with the angiotensin system. The present study hypothesizes that apelin/APJ axis exert its anti-thrombus effect in normal left atrial tissue and is disrupted by up-regulated renin-angiotensin-aldosterone system (RAAS) signaling during AF. The specimens of left atrial appendages collected from patients with rheumatic mitral stenosis who underwent valve replacement were divided into 3 groups: sinus rhythm, AF+/thrombus-, and AF+/thrombus+. The amounts of angiotensin II receptor subtype 1 (AT1), apelin/APJ and its downstream plasminogen activator inhibitor-1 (PAI-1) were detected by western blot. The expression of apelin/APJ was significantly decreased in the AF+/thrombus+ group compared with the sinus rhythm and AF+/thrombus- groups. Meanwhile the expressions of AT1 and PAI-1 were highest in the AF+/thrombus+ group compared to the other two groups. Taken together, the present study reveals apelin/APJ axis might be correlated with thrombosis in patients with AF mediated by PAI-1.