Functional role of endogenous Kv1.4 in experimental demyelination.

During neuroinflammation, the shaker type potassium channel Kv1.4 is re-expressed in oligodendrocytes (Ol), but not immune cells. Here, we analyze the role of endogenous Kv1.4 in two demyelinating animal models of multiple sclerosis. While Kv1.4 deficiency in primary murine Ol led to a decreased proliferation rate in vitro, it did not exert an effect on Ol proliferation or on the extent of de- or remyelination in the cuprizone model in vivo. However, in experimental autoimmune encephalomyelitis, Kv1.4-/- mice exhibited a milder disease course and reduced Th1 responses. These data argue for an indirect effect of Kv1.4 on immune cells, possibly via glial cells.

Fingolimod effects in neuroinflammation: Regulation of astroglial glutamate transporters?

Fingolimod is an oral sphingosine-1-phosphate-receptor modulator which reduces the recirculation of immune cells and may also directly target glial cells. Here we investigate effects of fingolimod on expression of astroglial glutamate transporters under pro-inflammatory conditions. In astrocyte cell culture, the addition of pro-inflammatory cytokines led to a significant downregulation of glutamate transporters glutamate transporter-1 (slc1a2/SLC1A2) and glutamate aspartate transporter (slc1a3/SLC1A3) expression on the mRNA or protein level. In this setting, the direct application of fingolimod-1 phosphate (F1P) on astrocytes did not change expression levels of slc1a2 and slc1a3 mRNA. The analysis of both transporters on the protein level by Western Blot and immunocytochemistry did also not reveal any effect of F1P. On a functional level, the addition of conditioned supernatants from F1P treated astrocytes to neuronal cell culture did not result in increased neurite growth. In experimental autoimmune encephalomyelitis as a model of multiple sclerosis, fingolimod treatment reduced T cell and macrophages/microglia mediated inflammation and also diminished astrocyte activation. At the same time, fingolimod restored the reduced expression of slc1a2 and slc1a3 in the inflamed spinal cord on the mRNA level and of SLC1A2 and SLC1A3 on the protein level, presumably via indirect, anti-inflammatory mechanisms. These findings provide further evidence for a predominantly peripheral effect of the compound in neuroinflammation.

Glutathione PEGylated liposomal methylprednisolone (2B3-201) attenuates CNS inflammation and degeneration in murine myelin oligodendrocyte glycoprotein induced experimental autoimmune encephalomyelitis.

Methylprednisolone (MP) pulses are the mainstay for relapse therapy in multiple sclerosis (MS). To improve the efficacy of treatment and reduce the side effects of MP, a long circulating brain-targeted formulation was developed; glutathione polyethylene glycol (PEG)ylated liposomal MP (2B3-201). Here we investigate the efficacy of 2B3-201 in murine myelin oligodendrocyte induced experimental autoimmune encephalomyelitis (MOG-EAE), an animal model mimicking inflammatory features and neurodegenerative aspects of MS. After disease onset, mice were randomized to receive either saline, three injections of free MP (high dose MP, 100mg/kg i.v.), two injections of free MP (low dose MP, 10mg/kg; i.v.), or two injections of 2B3-201 (10mg/kg i.v.). Treatment with a low dose of 2B3-201 significantly reduced the severity of EAE as compared to saline control, similar to treatment with high dose free MP, while a low dose of free MP was not effective. In a histological analysis of the spinal cord, treatment with 2B3-201 significantly decreased T cell as well as macrophage/microglia infiltration in the CNS by about 50%. Moreover, application of a low dose of 2B3-201 or a high dose of free MP reduced the amount of astrocyte activation as well as the extent of axonal loss and also demyelination in spinal cord lesions as compared to low dose MP or sham treatment. In summary, in the murine MOG-EAE model of MS, a glutathione PEGylated liposomal formulation of MP (2B3-201) is clinically and histologically as effective as free MP at one tenth of the dosage as well as at a lower application frequency and clearly more effective than the same dosage of free MP. These positive proof-of-concept efficacy studies warrant further development of 2B3-201 for the treatment of neuroinflammatory conditions such as MS.