Background: We reported a reduction in the levels of angiotensin II in cerebrospinal fluid (CSF) from patients with multiple sclerosis (MS).

Objective: To clarify the mechanism underlying this reduction, we assayed angiotensin-converting enzyme (ACE) and ACE2 concentrations along with angiotensin II concentrations in CSF samples from 20 patients with MS and 17 controls with non-neurological diseases.

Results: ACE levels were significantly elevated in patients with MS compared with controls (48.42 +/- 4.84 vs 44.71 +/- 3.9 pg/mL), whereas ACE2 levels were significantly reduced (2.56 +/- 0.26 vs 2.78 +/- 0.24 pg/mL), acting toward a normalization of angiotensin II levels.

Conclusions: These results further indicate an alteration of the intrathecal renin-angiotensin system in patients with MS.