Alpha lipoic acid inhibits T cell migration into the spinal cord and suppresses and treats experimental autoimmune encephalomyelitis

Alternatives to current disease-modifying treatment in MS: what do we need and what can we expect in the future?

Disease-modifying treatments (DMTs) for multiple sclerosis (MS) are now widely available, and their beneficial effects on relapse rates, magnetic resonance imaging outcomes and, in some cases, relapse-related disability have been shown in numerous clinical studies. However, as these treatments are only partially effective in halting the MS disease process, the search for improved treatment regimens and novel therapies must continue. Strategies to improve our therapeutic armamentarium have to take into account the different phases or parts of the pathogenesis of the disease. Available treatments address systemic immune dysfunction, blood-brain barrier permeability and the inflammatory process in the central nervous system. Currently, patients who fail to respond adequately to first-line DMTs are often considered as candidates for intensive immunosuppression with cytostatic agents or even autologous stem cell transplantation. However, new approaches are being developed. Combination therapies offer an alternative approach that may have considerable potential to improve therapeutic yield and, although likely to present considerable challenges in terms of trial design, this certainly seems to be a logical step forward in view of the complex pathology of MS. Several new drugs are also being developed with the aim of providing more effective, convenient and/or specific modulation of the inflammatory component of the disease. These treatments include humanised monoclonal antibodies such as the anti-VLA-4 antibody natalizumab, inhibitors of intracellular activation, signalling pathways and T-cell proliferation, and oral immunomodulators such as sirolimus, teriflunomide or statins. There remains, however, an urgent need for treatments that protect against demyelination and axonal loss, or promote remyelination/regeneration. Due to the chronicity of MS, the therapeutic window for neuroprotective agents is wider than that following stroke or acute spinal cord injury, and may therefore allow the use of some drugs that have proven disappointing in other situations. Novel potential neuroprotective agents such as alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid antagonists and ion-channel blockers will be entering Phase II trials in MS in the near future, and it is hoped that these agents will mark the start of a new era for DMTs for MS.

Sphingosine 1-phosphate receptor agonists attenuate relapsing–remitting experimental autoimmune encephalitis in SJL mice

FTY720 is a prodrug for FTY-phosphate, an agonist at four of the five known receptors for sphingosine-1-phosphate (S1P). We show that administration of either FTY720 or FTY-P to SJL mice with established relapsing-remitting experimental autoimmune encephalitis (EAE) results in a rapid and sustained improvement in their clinical status, and a reversal of changes in expression of mRNAs encoding some myelin proteins and inflammatory mediators. EAE produced by adoptively transferring lymph node cells from immunized mice to naïve hosts is similarly ameliorated by FTY-P. Treatment with FTY-P is accompanied by a dose-responsive peripheral lymphopoenia.

The Role of Iron in the Pathogenesis of Experimental Allergic Encephalomyelitis and Multiple Sclerosis

Multiple sclerosis (MS) and its animal model, experimental allergic encephalomyelitis (EAE), are autoimmune disorders resulting in demyelination in the central nervous system (CNS). Pathologically, the blood-brain barrier becomes damaged, macrophages and T cells enter into the CNS, oligodendrocytes and myelin are destroyed, astrocytes and microglia undergo gliosis, and axons become transected. Data from several biochemical and pharmacological studies indicate that free radicals participate in the pathogenesis of EAE, and iron has been implicated as the catalyst leading to their formation. The primary focus of this article is the examination of the role of iron in the pathogenesis of MS and EAE. Particular attention will be paid to the role and distribution of iron and proteins involved with iron metabolism (e.g., transferrin, ferritin, heme oxygenase-1, etc.) in normal and disease states of myelin. Furthermore, therapeutic interventions aimed at iron, iron-binding proteins, and substrates or products of iron-catalyzed reactions leading to free radical production will be discussed.

α-Lipoic acid is effective in prevention and treatment of experimental autoimmune encephalomyelitis

Alpha-lipoic acid (alpha-LA) is a neuroprotective metabolic antioxidant that has been shown to cross the blood brain barrier. We tested whether alpha-LA is capable to prevent MOG35-55-induced experimental autoimmune encephalomyelitis (EAE), an established model of multiple sclerosis (MS). Daily oral administration of alpha-LA, starting at the time of immunization, significantly prevented EAE progression as compared to control mice. This was associated with a reduction of CNS infiltrating T cells and macrophages as well as decreased demyelination. We then tested alpha-LA in a therapeutic protocol aimed at suppressing EAE after its onset. Intraperitoneal (i.p.), but not oral, administration of alpha-LA significantly prevented disease progression when compared to vehicle-treated controls. Similarly, we observed significant reduction of demyelination and inflammatory infiltration. This clinical effect was not due to an impairment of MOG35-55 recognition by encephalitogenic T cells. In contrast, MOG-specific T cells showed a decreased production of IFNgamma and IL-4, suggesting an immunosuppressive activity on both Th1 and Th2 cytokines. In addition, alpha-LA inhibited the proteolytic activity of MMP2 and MMP9 only at very high doses. Our data indicate that alpha-LA can effectively interfere with the autoimmune reaction associated with EAE through mechanisms other than its antioxidant activity and supports further studies on the use of alpha-LA as a potential therapy for MS.

Emerging disease modifying therapies for multiple sclerosis

Multiple sclerosis (MS), the most common central nervous system (CNS) demyelinating disease, is thought to be mediated in part by CNS autoantigen-specific T cells. The aetiology of the disease is unclear, but includes genetic and environmental factors. The disease onset often occurs in young adults and is characterised by bouts of neurological symptoms such as numbness, weakness, imbalance or visual difficulties that may not be recovered from. Sometimes the course is more progressive. Since the disease can be disabling, several treatments have been developed that reduce the risk of relapse and progression of sustained disability. Although earlier treatment is encouraged, currently approved disease modifying therapies for MS are only partially effective, administered parenterally and associated with significant side effects and potential toxicities. Therefore, many promising new therapies are under development that target various goals, including immunosuppression, immunomodulation, cell traffic through the blood-brain barrier (BBB), neuroprotection and enhancement of CNS repair.

Functional roles and therapeutic targeting of gelatinase B and chemokines in multiple sclerosis

Multiple sclerosis (MS) is a demyelinating disease of the CNS of unknown cause. Pathogenetic mechanisms, such as chemotaxis, subsequent activation of autoreactive lymphocytes, and skewing of the extracellular proteinase balance, are targets for new therapies. Matrix metalloproteinase gelatinase B (MMP-9) is upregulated in MS and was recently shown to degrade interferon beta, one of the drugs used to treat MS. Consequently, the effect of endogenously produced interferon beta or parenterally given interferon beta may be increased by gelatinase B inhibitors. Blockage of chemotaxis or cell adhesion molecule engagement, and inhibition of hydroxymethyl-glutaryl-coenzyme-A reductase to lower expression of gelatinase B, may become effective treatments of MS, alone or in combination with interferon beta. This may allow interferon beta to be used at lower doses and prevent side-effects.