Assessment of the concomitant action of XBD173 and interferon β in a mouse model of multiple sclerosis using infrared marker bands

Disease modifying therapies including interferon-β (IFNβ) effectively counteract the inflammatory component in relapsing-remitting multiple sclerosis (RRMS) but this action, generally associated with severe side effects, does not prevent axonal/neuronal damages. Hence, axonal neuroprotection, which is pivotal for MS effective treatment, remains a difficult clinical challenge. Growing evidence suggested as promising candidate for neuroprotection, Emapunil (AC-5216) or XBD173, a ligand of the mitochondrial translocator protein highly expressed in glial cells and neurons. Indeed, elegant studies previously showed that low and well tolerated doses of XBD173 efficiently improved clinical symptoms and neuropathological markers in MS mice. Here we combined clinical scoring in vivo with Fourier transform infrared spectroscopy of sera samples to investigate the hypothesis that the concomitant treatment of RRMS mice with low doses of IFNβ and XBD173 may increase their beneficial effects against MS symptoms and additionally decrease IFNβ-induced side effects. Our results show a significant alteration of the composition of serum protein and lipids in the spectra of the sera of RRMS mice. While the signature of proteins remains altered upon treatment, the signature of lipids is recovered comparatively well with 20 kIU IFNβ and upon concomitant treatment with a low dose of XBD173 (10 mg/kg) and IFNβ (10 kIU), but not with 10 kIU of IFNβ alone. The concomitant therapy with XBD173 (10 mg/kg) and IFNβ (10 kIU), devoid of side effects, exhibited at least equal or even better efficacy than IFNβ (20 kIU) treatment against RRMS symptoms.