Fumaric acid and its esters: an emerging treatment for multiple sclerosis with antioxidative mechanism of action

Fumaric acid was originally therapeutically used in psoriasis. Several lines of evidence have demonstrated immunomodulatory but also neuroprotective effects for FAE. Clinical studies in psoriasis showed a reduction of peripheral CD4+ and CD8+ T-lymphocytes due to the ability of FAE to induce apoptosis. In vitro studies with the ester dimethylfumarate (DMF) described an inhibitory effect on nuclear factor kappa B (NF-κB)-dependent transcription of tumor necrosis factor-alpha (TNF-α) induced genes in human endothelial cells. Animal experiments in the mouse model of central nervous system demyelination, MOG-induced experimental autoimmune encephalomyelitis, revealed a clear preservation of myelin and axonal density in the plaque. Molecular studies showed that this is based on the antioxidative mechanism of action via induction of the transcription factor Nrf-2. A phase II clinical trial in relapsing-remitting multiple sclerosis (RRMS) patients with dimethylfumarate showed a significant reduction in the number of gadolinium enhancing lesions after 24weeks.

Remyelination after cuprizone induced demyelination is accelerated in mice deficient in the polysialic acid synthesizing enzyme St8siaIV

Polysialic acid (PSA) is a carbohydrate polymer added post-translationally on the neural cell adhesion molecule (NCAM) affecting its adhesion properties. It has been suggested that the presence of PSA in demyelinated lesions in multiple sclerosis could prevent axon-glia interactions inhibiting spontaneous remyelination. The enzyme St8siaIV is one of the two polysialyltransferases responsible for PSA synthesis, and it is predominantly active during adult life. Here we treated 8-10-weeks old St8siaIV deficient and wild-type mice for 5 weeks with cuprizone, which is a reliable model for de- and remyelination in the corpus callosum and cortex. Developmental myelination of the St8siaIV knock-out mice was not disturbed and adult mice showed normal myelin protein expression. Demyelination did not differ between transgenic and wild-type mice but early myelin protein re-expression and thus remyelination were accelerated in St8siaIV knock-out mice during the first week after withdrawal of the toxin. This was mainly due to enhanced oligodendrocyte precursor cells (OPC) differentiation and to a lesser extent to OPC recruitment. These data are proof of principle that PSA expression interferes at least to some extent with remyelination in vivo.

[The significance of intravenous immunoglobulin in treatment of immune-mediated polyneuropathies]

Long-term treatment of immune-mediated polyneuropathies remains difficult. For acute polyneuritis, or Guillain-Barré syndrome, the established standard therapy utilizes high doses of polyvalent intravenous immunoglobulins (IVIG). A recently published randomized placebo-controlled study of patients with chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) showed IVIG to be clinically effective also for this disorder in both short and long term. This survey presents data of this so-called ICE study ("Intravenous immune globulin for the treatment of chronic inflammatory demyelinating polyradiculoneuropathy"). It also discusses the value of IVIG in the treatment of immune-mediated polyneuropathies.

Analysis of neuroprotective effects of valproic acid on primary motor neurons in monoculture or co-cultures with astrocytes or Schwann cells

Chronic dysregulation of the intracellular Ca(2+) homeostasis (excitotoxicity) is thought to contribute to the development of motor neuron diseases. Valproic acid (VPA) is widely used as an antiepileptic drug and acts mainly by inhibition of sodium channels and by enhancing the level of the inhibitory neurotransmitter gamma-aminobutyric acid. Neuroprotective capacities of VPA are supposed to arise also from the inhibition of histone deacetylases. We investigated the viability of highly purified rat embryonic motor neurons cultured on glial feeder layers, composed of either astrocytes or Schwann cells, or in the absence of glia, monoculture in presence of VPA and/or kainate (KA) using immunocytochemistry and calcium imaging. A significant effect of the culture and co-culture conditions on the viability of motor neurons in our in vitro model of excitotoxicity was detected. The neuroprotective effect of VPA on primary embryonic motor neuron cultures was not proven. A functional interaction between VPA and KA occurred during the first 10 days in culture.

Fumaric Acid and its esters: an emerging treatment for multiple sclerosis

Fumaric acid is an intermediate product of the citric acid cycle that is a source of intracellular energy in the form of adenosine triphosphate (ATP). It is generated by oxidation of adenylsuccinate by the enzyme succinate dehydrogenase and is then converted to maleate by the enzyme fumarase. At present, fumaric acid esters (FAE) are licensed for the treatment of psoriasis. Several lines of evidence have demonstrated immunomodulatory effects for FAE. Clinical studies in psoriasis showed a reduction of peripheral CD4(+)- and CD8(+)-T-lymphocytes due to the ability of FAE to induce apoptosis. In vitro studies with the ester dimethyl fumarate (DMF) described an inhibitory effect on nuclear factor kappa B (NF-kappaB)-dependent transcription of tumor necrosis factor-alpha (TNF-alpha) induced genes in human endothelial cells. Animal studies using a model of central nervous system demyelination, MOG-induced experimental autoimmune encephalomyelitis (EAE), revealed a reduction of microglia and macrophages in inflamed lesions. A phase II clinical study in relapsing-remitting multiple sclerosis (RRMS) patients with a modified fumaric acid ester, BG-12, showed as "proof of principle" a significant reduction in the number of gadolinium enhancing lesions after 24 weeks of treatment as compared to placebo. Further phase III studies have now started to explore the long-term efficacy of FAE.