Abstract 39: Decreased Ferroxidase Activity in Cerebrospinal Fluid Following Subarachnoid Hemorrhage

Abstract

Introduction: We previously reported on the relationship between unbound CSF iron and brain injury following SAH. The ferroxidase ceruloplasmin (Cp) regulates iron levels in the CNS and prevents free radical injury. Paradoxically, oxidative stress is known to cause structural modifications that result in decreased enzymatic activity of Cp. We sought to determine if CSF of patients with SAH exhibits impaired ferroxidase activity (FA). Methods: Samples of CSF were obtained on day 5 following aneurysm rupture and levels of malondialdehyde (MDA; a marker of lipid peroxidation) and ferroxidase activity (defined as the amount of enzyme that converts 1 μM of substrate into product per minute) were determined by means of absorbance and colorimetric assays. Ceruloplasmin concentration in CSF was measured with ELISA. Demographic and clinical data were recorded. Values are expressed as mean ± SEM. Comparisons were made using Wilcoxon rank sum test. Simple linear regression analysis was performed for comparison of continuous variables. Results: A total of 5 patients and 4 control subjects were included in this pilot study. Median Hunt-Hess and modified Fisher scores were 4 (IQR 1.5) and 4 (IQR 1), respectively. Levels of MDA in CSF (9.2 ± 0.9 vs. 0.09 ± 0.01 μM, p =0.02) were significantly higher in SAH patients, while FA was significantly reduced (64.8 ± 17.1 vs. 284.1 ± 64.9 U/L, p =0.01). Ceruloplasmin concentration was higher in SAH samples (49.4 ± 12 vs. 1.72 ± 0.7 mg/L, p =0.04), and patients who developed delayed cerebral ischemia had lower CSF FA (43.2 ± 6.3 vs. 97.2 ± 32.4 U/L, p =0.07), compared to those who did not. Conclusions: The ferroxidase activity of CSF following SAH is significantly impaired, in spite of higher ceruloplasmin concentrations. Evidence of increased CNS oxidative damage was also demonstrated in our cohort. We postulate that structural modifications in Cp mediated by an oxidative milieu occur in SAH and are associated with decreased enzymatic function. There is a possible inverse relationship between ferroxidase activity and risk of development of delayed cerebral ischemia. Further studies are needed to explore the significance of these findings.