Beta-endorphin concentrations in peripheral blood mononuclear cells of multiple sclerosis patients:effects of beta-interferon treatment

Context: It has been reported that the opioid peptide β-endorphin (BE) has immunosuppressive effects. Interferon beta (IFN-β) is a well-established therapy for multiple sclerosis (MS), but immunological mechanisms underlying its beneficial effects in MS are partially undefined. Objectives: To determine BE levels in peripheral blood mononuclear cells (PBMCs) of patients with relapsing-remitting MS during different phases of disease activity and the possible modulating effects of IFN-β treatment on PBMC BE synthesis in patients with MS. Design: We measured BE levels in blood samples collected from 6 patients with MS who had not experienced clinical changes during the previous 3 months (patients with stable MS) and from 7 patients with MS during a clinical relapse. We also surveyed BE levels in PBMC samples from 8 patients with MS before treatment and for 6 months after the beginning of IFN-β administration. The control group was 13 healthy subjects. Results: Low PBMC BE levels were detected in patients with stable MS and in those entering IFN-β treatment compared with control subjects. Increased BE concentrations were observed in MS patients experiencing a clinical relapse compared with patients with stable MS. During IFN-β treatment, the levels of BE in PBMC samples from patients with MS increased significantly (after 1 month, P = .02; after 3 months, P = .007; and after 6 months, P = .16). Conclusions: A reduction of BE levels was present in patients with clinically inactive MS. Treatment with IFN-β seems to induce an increase of this opioid in PBMCs of MS patients. The increase of BE concentration during a clinical relapse may represent a possible control mechanism aimed at counterbalancing the inflammatory phase of the disease.