Liposomal glucocorticosteroids in treatment of chronic autoimmune demyelination: long-term protective effects and enhanced efficacy of methylprednisolone formulations.

Liposomal encapsulation leads to enhanced efficacy of glucocorticosteroids (GS) in treatment of autoimmune diseases. Here we compare liposomal prednisolone (PL) to liposomal methylprednisolone (MPL) in chronic-relapsing myelin oligodendrocyte glycoprotein-induced experimental autoimmune encephalomyelitis (EAE), a model closely reflecting aspects of multiple sclerosis (MS). At the maximum of the first relapse, a single dose of PL or MPL was applied at 10 mg/kg or at 4 mg/kg and compared to classical methylprednisolone (MP) pulse therapy. PL at 10 mg/kg was superior to free MP with long-term efficacy and a sustained protection even during the second and third relapse. At the same time, in vivo magnetic resonance imaging of rat brains revealed a significant reduction of T2-lesions after PL application. Comparison of PL and MPL at 10 mg/kg disclosed superior effects for MPL with an enhanced reduction of inflammatory infiltration as well as preservation of myelin and axons. Dose titration experiments underscored a dose-dependent efficacy of liposomal GS with a sustained efficacy especially of the higher dosage. In histological analyses, PL10 was superior in reducing macrophage and T cell infiltration as well as demyelination and axonal loss while the lower dosages were still at least as effective as free MP. FACS analyses revealed an effect of liposome formulations on T cell numbers, the CD4/CD8 ratio, frequencies of regulatory T cells and adhesion molecule expression. In summary, liposomal GS and especially methylprednisolone formulations display an enhanced efficacy not only in acute inflammatory, but also in chronic demyelinating models of MS and confer long-term protection from relapses. These findings lay the groundwork for applying liposomal GS in clinical MS trials in the near future.