Complement Complex C5b-9 Levels Are Associated with the Clinical Outcomes of Acute Ischemic Stroke and Carotid Plaque Stability.

The terminal complement complex C5b-9 plays an important role in acute ischemic stroke (AIS) and carotid atherosclerosis. However, the associations between serum C5b-9, the severity and outcome of AIS, and the stability of carotid plaques have not been well investigated. In this clinical study, 70 patients with AIS and 70 healthy controls were enrolled. Serum C5b-9 levels at 72 h after stroke onset were measured by enzyme-linked immunosorbent assay (ELISA). Infarct size, the National Institutes of Health Stroke Scale (NIHSS), the 90-day modified Rankin Scale (mRS), and carotid plaque and stenosis were evaluated. Serum C5b-9 levels were significantly higher in AIS patients than in healthy controls (p < 0.001) and were correlated with infarction sizes (p = 0.045) and the NIHSS (P = 0.035). Furthermore, 90-day mRS analysis demonstrated that the patients with poor outcomes had higher serum C5b-9 levels than those with good outcomes (P < 0.001). Moreover, serum C5b-9 levels in AIS patients with unstable carotid plaques were much higher than in those with stable carotid plaques (P = 0.009). Multivariate logistic regression indicated that C5b-9 could be an independent risk factor for AIS (P < 0.001) and unstable carotid plaques (P = 0.015). Therefore, complement complex C5b-9 may be a potential biomarker in predicting the severity and outcome, as well as the stability of carotid plaques, in AIS patients.