Abnormalities in the cerebrospinal fluid levels of endocannabinoids in multiple sclerosis

Endocannabinoids (eCBs) play a role in the modulation of neuroinflammation, and experimental findings suggest that they may be directly involved in the pathogenesis of multiple sclerosis (MS). The objective of our study was to measure eCB levels in the cerebrospinal fluid (CSF) of patients with MS.

Arachidonoylethanolamine (anandamide, AEA), palmotylethanolamide (PEA), 2-arachidonoylglycerol (2-AG) and oleoylethanolamide (OEA) levels were measured in the CSF of 50 patients with MS and 20 control subjects by isotope dilution gas-chromatography/mass-spectrometry. Patients included 35 patients with MS in the relapsing-remitting (RR) form of the disease, 20 in a stable clinical phase and 15 during a relapse, and 15 patients with MS in the secondary progressive (SP) form.

Significantly reduced levels of all the tested eCBs were found in the CSF of patients with MS compared to control subjects, with lower values detected in the SP MS group. Higher levels of AEA and PEA, although below those of controls, were found in the CSF of RR MS patients during a relapse. Higher levels of AEA, 2-AG and OEA were found in patients with MRI gadolinium-enhancing (Gd+) lesions.

The present findings suggest the presence of an impaired eCB system in MS. Increased CSF levels of AEA during relapses or in RR patients with Gd+ lesions suggest its potential role in limiting the ongoing inflammatory process with potential neuroprotective implications. These findings provide further support for the development of drugs targeting eCBs as a potential pharmacological strategy to reduce the symptoms and slow disease progression in MS.