Complement system and small HDL particles are associated with subclinical atherosclerosis in SLE patients

Abstract Background The complement system is involved in the pathogenic course of SLE. These patients exhibit metabolic disturbances in lipoprotein metabolism characterized by a pro-inflammatory status and an accelerated atherosclerosis. The aim of this study is to investigate whether levels of the complement are associated to the presence of subclinical atherosclerosis, lipid and glucose metabolism and inflammatory markers in SLE patients. Methods Sixty-nine consecutive patients with SLE were recruited for the study. Fasting venous blood samples were collected on the same day as the measurements of cIMT were performed. Total plasma lipids and the distribution of subclasses of lipoproteins were analyzed by nuclear magnetic resonance spectroscopy. Results We found direct correlations between cIMT values and the levels of C3, C4 and CH50. In multivariate analyses, the mean cIMT from the three territories were predicted by age ( β  = 0.005, 95% CI: 0.002–0.007, P β  = 0.003, 95% CI: 0.001–0.006, P β  = 0.024, 95% CI: 0.013–0.035, P β  = 0.005, 95% CI: 0.002–0.008, P  = 0.006. Conclusions Activation of the complement system measured by functional assay CH50 is related to subclinical atherosclerosis in quiescent lupus patients and is activated by the small dense HDL particles.