Inflammation, complement activation and endothelial function in stable and unstable coronary artery disease

Abstract

Background Endothelial dysfunction plays an important role in the pathogenesis of coronary artery disease (CAD). Apart from traditional risk factors complement activation and inflammation may trigger and sustain endothelial dysfunction. We sought to assess the association between endothelial function, high sensitivity C-reactive protein (hs-CRP) and markers of complement activation in patients with either stable or unstable coronary artery disease. Methods We prospectively recruited 78 patients, 35 patients with stable angina pectoris (SAP) and 43 patients with unstable angina pectoris (UAP). Endothelial function was assessed as brachial artery reactivity (BAR). Hs-CRP, C3a, C5a and C1-Inhibitor (C1 inh.) were measured enzymatically. Results Patients with UAP showed higher median levels of hs-CRP and C3a compared to patients with SAP, while BAR was not significantly different between patient groups. In UAP patients, hs-CRP was significantly correlated with cholesterol ( r = 0.27, p < 0.02), C3a ( r = 0.32, p < 0.001) and C1 INH.( r = 0.41, p < 0.003), but not with flow mediated dilatation ( r = 0.09, P = 0.41). Hs-CRP and C1 INH.were found to be independant predictors of UAP in a backward stepwise logistic regression model. Conclusions We conclude that both hs-CRP, a marker of inflammation and C3a, a marker of complement activation are elevated in patients with UAP, but not in patients with SAP.