| Objective To investigate the association between complement C3, C4, complement regulatory proteins CD55, CD59 and carotid artery intima-media thickness(IMT),ankle/brachial index in hyperlipidemia.Methods Serum C3, C4, properdin were tested with rate nephelometry and the expression of CD55, CD59 on leucocytes were evaluated with flowcytometry. High resolation B-ultrasould Doppler with vascular probe(lOMHz) was used in testing of IMTs,calibers and flow rate,brachial pressure,ankle pressure(ABI=ankle/brachial index). Four carotid artery segments of carotid artery on each side 0-15mm distal to the common carotid artery(CCA1), 15-30mm distal to the common carotid artery(CCA2), the bifurcation, the internal carotid artery(ICA) were examined by one same ultrasonographer. 20 age-, sex-, body weight-matched healthy volunteers were served as controls. The relationship between complement components, complement regulatory proteins and carotid artery IMT,ABI was analyzed.Results Compared with healthy controls, serum levels of C3, C4, properdin in hyperlipidemic patients were increased significantly [(1.47±0.40)g/L vs (1.21±0.26)g/L, (0.37±0.14)g/Lvs (0.29±0.09)g/L, (0.39±0.11)g/L vs (0.35±0.06)g/L, P=0.000, 0.000, 0.004], while the mean fluorescence intensity(MFI) of CD-positive lymphocytes was markedly decreased (2.05±0.31 vs 2.33±0.38, P=0.000). IMTs of CCA1, CCA2, bifurcation, ICA in patients with hyperlipidemia were all increased[(0.80±0.13)mm vs (0.71±0.08)mm, (0.85±0.14)mm vs (0.74±0.07)mm, (0.93±0.24)mm vs (0.78±0.15)mm, (0.66±0.11)mm vs (0.59±0.07)mm, P=0.007, 0.000, 0.019, 0.008, respectively].Flow rate of CCA1,CCA2 were increased [(68.45±16.60)cm/s vs (81.95±17.64)cm/s, (65.93±13.76)cm/s vs (74.14±13.63),P=0.004,0.029], while calibers of CCA1,CCA2 were decrease [(6.54±0.70)mm vs (5.96±0.66)mm, (6.39±0.73)mm vs (5.92±0.58)mm, P=0.002, 0.017]: Left,right average ABI were all decreased[(1.12±0.16) vs (1.21±0.11), (1.16±0.17) vs (1.27±0.07),(1.14±0.15) vs (0.24±0.05),P=0.034,0.001,0.000 ],IMTs of CCAl, CCA2, ICA were all positively correlated with age(P<0.05-P<0.01);IMT in each segment of carotid artery was positively correlated with systolic pressure;IMTs in CCAl, bifurcation, ICA were negatively correlated with MFI of CD55-positive lymphocytes(P<0.05);CCA2 IMT with waist-hip ratio and bifurcation IMT with hsCRP were positively correlated(both P<0.05). None of the four segment IMTs was correlated significantly with complement C3, C4, and properdin.Left,right,average ABI were all negatively correlated with HsCRP(P<0.05-0.01),and positively correlated with weight,body mass index(P<0.05-0.01);Left,average ABI were negatively correlated with age(P<0.05);Right,average ABI were positively correlated with height.Conclusion Serum C3, C4 and properdin are increased and the expression of complement regulatory protein CD55 on lymphocytes is decreased in hyperlipidemic patients. Down-regulation of complement regulatory protein CD55 expression might contribute to the development of atherosclerosis. Carotid IMT and caliber are all increased,flow rate is decreased, But complement C3, C4, properdin have no direct relation with atherosclerosis.
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