Serum levels of renin-angiotensin system components in acute stroke patients

The renin-angiotensin system (RAS) is involved in the pathogenesis of ischemic brain damage, and is suggested to have therapeutic potential in stroke by large clinical trials. However, the changes of serum RAS components in patients with acute stroke are totally unknown. We assessed the serum levels of RAS components in acute stroke patients, and investigated the relationship between RAS and stroke subtype.

Levels of angiotensin-converting enzyme (ACE), ACE2 and angiotensin II in serum from patients with acute stroke (n=117; male 75, female 42, age 69 ± 13 years) were measured by an established enzyme-linked immunosorbent assay method. Diagnosis of subtypes of ischemic stroke was based on the Trial of Org10172 in Acute Stroke Treatment classification. The Kruskal-Wallis test with post-hoc Mann-Whitney U-test with Bonferroni correction was carried out for statistical analysis.

Classification of stroke was as follows: large-artery atherosclerosis (n=44), cardioembolism (n=33), small-vessel occlusion (n=31), stroke of other determined etiology (n=9). Levels of angiotensin II and ACE did not show significant differences among each group. However, serum ACE2 level was significantly higher in the cardioembolism group than in the small-vessel occlusion group (cardioembolism 13 ± 9.3 ng/mL, large-artery atherosclerosis 10.2 ± 6.8 ng/mL, small-vessel occlusion 7.2 ± 3.7 ng/mL, stroke of other determined etiology 10.2 ± 7.3 ng/mL). ACE2 level showed a positive correlation with serum brain natriuretic peptide level (P=0.031). In contrast, angiotensin II concentration showed a negative correlation with National Institute of Health Stroke Scale score on admission (P=0.023).

These findings suggest that changes of serum RAS components could reflect stroke subtypes and predict stroke severity.