Endothelial nitric oxide synthase tagging single nucleotide polymorphisms and recovery from aneurysmal subarachnoid hemorrhage

Aneurysmal subarachnoid hemorrhage (SAH) is a hemorrhagic stroke subtype with a poor recovery profile. Cerebral vasospasm (CV), a narrowing of the cerebral vasculature, significantly contributes to the poor recovery profile. Variation in the endothelial nitric oxide (NO) synthase (eNOS) gene has been implicated in CV and outcome after SAH. The purpose of this project was to explore the potential association between three eNOS tagging single nucleotide polymorphisms (SNPs) and recovery from SAH. We included 195 participants with a diagnosis of SAH and DNA and 6-month outcome data available but without preexisting neurologic disease/deficit. Genotyping was performed using an ABI Prism 7000 Sequence Detection System and TaqMan assays. CV was verified by cerebral angiogram independently read by a neurosurgeon on 118 participants. Modified Rankin Scores (MRS) and Glasgow Outcome Scale (GOS) scores were collected 6 months posthemorrhage. Data were analyzed using descriptive statistics, analysis of variance (ANOVA) and chi-square analysis as appropriate. The sample was primarily female (n=147; 75.4%) and White (n=178; 91.3%) with a mean age of 54.6 years. Of the participants with CV data, 56 (47.5%) developed CV within 14 days of SAH. None of the SNPs individually were associated with CV presence; however, a combination of the three variant SNPs was significantly associated with CV (p=.017). Only one SNP (rs1799983, variant allele) was associated with worse 6-month GOS scores (p<.001) and MRS (p<.001). These data indicate that the eNOS gene plays a role in the response to SAH, which may be explained by an influence on CV.

Cerebrospinal Fluid Apolipoprotein E, Calcium and Cerebral Vasospasm after Subarachnoid Hemorrhage

Intracellular calcium (Ca ++) regulation of cerebral vessels is impaired after subarachnoid hemorrhage (SAH), making secondary pathways, such as that involving apolipoprotein E, potentially more influential. To evaluate cerebrospinal fluid (CSF) apolipoprotein E and Ca++ levels as biomarkers of cerebral vasospasm, we examined changes in levels over time and apolipoprotein E (APOE) ε4 allele presence after SAH in individuals with and without vasospasm. We hypothesized that individuals with low apolipoprotein E levels, increased Ca++ levels and/or at least one copy of the APOE ε4 allele would have vasospasm. Daily samples from 50 participants, aged 18—75, with SAH were used to quantify apolipoprotein E and Ca++ levels. Vasospasm was verified using cerebral angiogram and/or elevated transcranial Dopplers in combination with clinical neurologic deterioration. Overall apolipoprotein E levels were higher in individuals with the APOE ε4 allele (p = .02) or angiographic vasospasm (p = .01), but there were no differences between individuals with and without symptomatic vasospasm. There were no significant changes in apolipoprotein E levels over time. Individuals with the ε4 allele had lower Ca ++ levels (p = .02) with trends suggesting a different pattern of change over time (p = .07). CSF Ca++ levels were lower in individuals with symptomatic vasospasm (p < .01). Change in apolipoprotein E and Ca ++ levels (p = .006) correlated over time regardless of genotype or vasospasm status. These findings suggest that apolipoprotein E and Ca ++ may be interacting after SAH, but this interaction does not appear to influence vasospasm.