Is serum angiotensin-converting enzyme a suitable biomarker for differentiating idiopathic and demyelinating optic neuritis?

Abstract

Background: To measure serum angiotensin-converting enzyme (ACE) in patients diagnosed with idiopathic and demyelinating optic neuritis (ON) as well as heathy individuals and assess its viability as a biomarker Methods: This case-control study involved patients with established acute ON as a study group and healthy controls aged between 18 and 50 years. After systemic and neurological evaluation, the study group was divided into two subgroups: idiopathic ON and demyelinating ON, including Multiple Sclerosis (MS), Neuromyelitis Optica (NMO) and clinically isolated syndrome (CIS). Using enzyme-linked immunosorbent assay, serum ACE levels were obtained and compared between groups. Results: Fifty-one patients with acute optic neuritis (78.4% female, mean age 29.8 ± 8.4 years) and 51 controls (78.4% female, mean age 29.9 ± 6.9 years) were recruited. In the study group, 29 patients were diagnosed with idiopathic ON (56.9%), and 22 patients with demyelinating ON (43.1%) (MS-ON, n=16; NMO-ON, n=3; and clinically isolated syndrome, n=3). The median serum ACE levels were 33.50 U/L (range: 29.40–46.20) and 34.25 U/L (range: 29.30–46.10) for patients diagnosed with idiopathic ON and demyelinating ON, respectively (P>0.99). Mean serum ACE level for healthy individuals was 26.2 U/L (range: 24.80–20.50) and compared to other groups it was significantly different (P<0.001). A high level of serum ACE (defined as a serum ACE >65 U/L) was present in 3 (10.3%) patients with idiopathic ON and 2 (9.1%) patients with the demyelinating ON (P>0.99). Conclusions: These results reveal that serum ACE levels are not significantly different in patients diagnosed with idiopathic ON and demyelinating ON. But serum ACE level in both groups is significantly higher compared to healthy subjects.