Homeostasis of complement system and the severity of coronary artery disease

Objective To investigate if the relative ratio between C1q and C3a, C5a had a relationship with the extent of coronary artery disease (CAD) which had never been evaluated in humans. Methods Fifty-three patients scheduled for elective percutaneous coronary intervention (PCI) from February, 2016 to April, 2016 at Fuwai hospital were prospectively enrolled. According to the clinical and angiographic characters patients were divided into two groups: acute coronary syndrome (ACS) group (n=24), and control group (n=29, 19 patients with stable angina and 10 patients without CAD confirmed by angiography). In all individuals, fasting venous blood was collected by EDTA tubes after admission and strictly before PCI. The plasma level of C1q was measured by immune turbidimetric analysis, C3a and C5a were measured by ELISA tests. Differences between groups were assessed using t test, Mann-Whitney Utests, chi-squared test or Fisher exact test depending on the type of data respectively. Multivariate logistic regression analyses were conducted to evaluate the adjusted effect of C1q, C3a, C5a, C1q/C3a and C1q/C5a on ACS. Results Compared with control group, ACS group has an elevated circulation level of C3a (4 531.14 μg/L vs. 4 179.95 μg/L, t=1.381, P=0.173) and C5a (6.44 μg/L vs. 4.42 μg/L, t=0.133, P=0.108) but a decreased level of C1q (176.98 μg/ml vs. 200.60 μg/ml, t=-2.022, P=0.048). The relative ratio of C1q/ C3a was significantly decreased in ACS patients(4.05×10-2vs. 4.97×10-2,t=-2.484, P=0.016). According to the multiple logistic regression analysis, lower relative ratio of C1q/C3a level proved to be independently associated with ACS (OR=0.937, P=0.047, 95% CI: 0.879-0.998). Conclusions The decreased relative ratio of C1q/ C3a level proved to be independently associated with ACS. C1q/C3a ratio could be used as an important index reflecting the complement system homeostasis status which might have potential clinical value in evaluating the prognosis of patients with CAD.(Chin J Lab Med, 2016, 39: 685-689) Key words: Coronary artery disease; Severity of illness index; Complement C1q; Complement C3a; Complement C5a