The Relationship Between Plasma Osteopontin, Serum Aldosterone And Carotid Intima Media Thickness In Essential Hypertensive Subjects

Background and purposeEssential hypertension (EH) is one of the major risk factors of atherosclerosis. In patients with EH, hemodynamic changes and abnormal neurohumoral regulation lead to macrophages aggregation, smooth muscle cells immigration, collagen increase that may contribute to atherosclerosis. As a noninvasive indicator of atherosclerosis, carotid intima-media thickness (IMT) is currently and widely used and also closely related to cardio-cerebral vascular diseases.Osteopontin (OPN) was first discovered in bone tissue by Herring in1983,it was named because it mediated the connection of bone cells with bone matrix,involved in the mineralization of bone matrix and re-absorption process. Nearly all body cells can express OPN. Studies have shown that the OPN can participate in various physiological and pathological processes,such as bone metabolism, atherosclerosis, myocardial remodeling, immune regulation, tumor metastasis, post-traumatic tissue repair, scar formation and fibrosis.Aldosterone (ALD) is an important component of the rennin-angiotensin-aldos-terone system (RAAS).RAAS is activated in EH patients,causing ALD expression elevated, and then promoting AS through many pathways.ALD and OPN are closely linked:OPN is higher in patients with aldosteronism,and is lower when the patient was treated with spironolactone;ALD rasied OPN level in cultured vascular smooth muscle cells in a time-dependent manner.But there were little report about whether plasma OPN was related with serum ALD,and the mechanism of the interaction of plasma OPN with serum ALD in EH patients accompanied with atherosclerosis was unclear.The aim of this study was to know about OPN level in EH patients,and the interaction of OPN level with ALD level in EH patients with AS by measuring plasma OPN、 serum ALD、 carotid artery IMT.And finally research how OPN and ALD influence the course of AS in EH patients.Subjects and Methods91EH patients were selected for the study in the Second Affiliated Hosoital of Zhengzhou University from January to October2011,male47and female44,then they were divieded into EH without carotid atherosclerosis group(50cases) and EH with carotid atherosclerosis group(41cases) according to carotid ultrasound.All patients were up to guidelines of prevention and treatment with essential hypertension in China2010. Also39healthy cases served as normal controls,20males and19females.EH patients who were in antihypertensive treatment would withdrawal drugs2weeks before drawing blood. All selected were to exclude secondary hypertension, diabetes, metabolic syndrome, acute and chronic infectious diseases, autoimmune diseases, cancer, kidney disease and other serious chronic diseases.Blood pressure was measured by electronic sphygmomanometer by standard method.Conventional biochemical methods were used to measure fasting glucose (FG), total cholesterol (TC), triglyceride (TG), high density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), serum creatinine (Cr), blood urea nitrogen (BUN). Plasma OPN was tested through enzyme-linked immunosorbent assay (ELISA),serum ALD was tested by radioimmunoassay (RIA).Carotid IMT was measured by Doppler ultrasound. SPSS17.0statistical package was used for processing the measurement data, By comparing three groups, analysis of variance was taken place after the check of homogeneity of variance, Correlation was analyzed by the Pearson correlation analysis, P<0.05for the data differences had a statistical significence.Results1. Plasma osteopontin (31.6±4.1vs29.5±5.6) ug/1and serum aldosterone (134.6± 19.2vs125.0±21.8) ng/L levels were increased in50essential hypertensive patients with IMT<0.9as compared with39control (both P<0.05).2. Plasma osteopontin (34.2±4.4vs31.6±4.1) ug/l and serum aldosterone (143.9±24.1vs134.6±19.2) ng/L levels were increased in41essential hypertensive patients with IMT≥0.9as compared with50essential hypertensive patients with IMT<0.9(bothP<0.05).3.There was a positive relationship between plasma osteopontin and serum aldosterone level in essential hypertensive patients(r=0.594, P<0.05).4.There was a positive relationship between plasma osteopontin and IMT in essential hypertensive patients(r=0.424, P<0.01).ConclusionPlasma OPN level is higher in patients with EH, and has a positive correlation to carotid artery IMT and serum ALD. Plasma OPN may play a role in the progression of atherosclerosis in patients with EH.