Statins as potential therapeutic agents in multiple sclerosis

Simvastatin improves final visual outcome in acute optic neuritis: a randomized study

Background: In recent years, small-scale clinical trials have indicated that statins or 3-hydroxy-3-methylglutaryl coenzyme A (HMGCoA) reductase inhibitors exert pleiotropic immunomodulatory effects, with potential therapeutic implications in multiple sclerosis (MS).

Objective: To investigate whether simvastatin treatment (80 mg daily for 6 months) in patients with optic neuritis (ON) had a beneficial effect on visual outcome and on brain MRI.

Methods: Sixty-four patients with acute ON were randomized to simvastatin treatment ( n = 32) or placebo ( n = 32) for 6 months. None of the patients had been on immunosuppressive therapy for 6 months prior to inclusion or treated with steroids from symptom onset. Contrast sensitivity (Arden plates), visual acuity, colour perception, visual evoked potentials (VEP) – latency and amplitude, Visual Analogue Scale (VAS) score, and gadolinium enhancing and T2 lesions on brain MRI were evaluated at screening visit, day 14 (except brain MRI), day 90 and day 180.

Results: Simvastatin had a beneficial effect on VEP in both latency ( p = 0.01) and amplitude ( p = 0.01), a borderline effect on the Arden score ( p = 0.06) and VAS ( p = 0.04), and no effect on brain MRI or on relapse rate between the groups.

Conclusion: This study provides Class I evidence that simvastatin 80 mg daily is well tolerated and possibly effective in patients with acute ON.

Neurotherapeutics in multiple sclerosis: novel agents and emerging treatment strategies

New insights into the complex immunopathogenesis of multiple sclerosis have led to a proliferation of promising new therapeutic strategies. While the current armamentarium of immunomodulatory medications has demonstrated beneficial effects on the disease, more effective and tolerable therapies are needed. Several novel therapeutic strategies under investigation include oral therapies, monoclonal antibodies, symptomatic treatments, insights into neuroprotection and repair as well as combination regimens. New therapies may prove more efficacious and tolerable than the available arsenal of treatments; however, decisions regarding first-line therapies will expectedly become more complicated, with greater influence if risk-to-benefit ratios in light of premature safety data. Biomarker profiles may help elucidate disease subtypes as well as therapeutic response in an effort to individualize treatment choice. This review will highlight recent promising therapeutic strategies under investigation in the field of MS.

Multiple sclerosis: new treatment trials and emerging therapeutic targets

PURPOSE OF REVIEW

This review focuses on new therapeutic strategies in multiple sclerosis.

RECENT FINDINGS

The past decade has marked the advent of various new therapeutic strategies in multiple sclerosis. Whereas the current armamentarium of immunomodulatory medications has demonstrated beneficial effects on the disease, more effective and tolerable therapies are needed. Several novel therapeutic strategies in testing include oral therapies, monoclonal antibodies, symptomatic treatments as well as insights into neuroprotection and repair. Ways to build upon existing therapies are also under investigation, including early initiation of treatment and various combination regimens.

SUMMARY

New therapies, along with variations of currently available treatments, may prove more efficacious and tolerable than the available arsenal of treatments. Nevertheless, as the treatment horizon broadens, choosing first-line therapies will become more complicated, with greater influence of risk-to-benefit ratios in light of premature safety data. Patient's clinical, paraclinical and biomarker fingerprint profiles may help elucidate disease subtypes as well as response to therapy in an effort to individualize treatment choice. A complete discussion of all studies currently underway is beyond the scope of this review, which will highlight recent promising therapeutic strategies under investigation in the field of multiple sclerosis.

Differential effects of Th1, monocyte/macrophage and Th2 cytokine mixtures on early gene expression for immune-related molecules by central nervous system mixed glial cell cultures

Cytokines secreted within the central nervous system (CNS) are important in the development of multiple sclerosis (MS) lesions. The balance between Th1, monocyte/macrophage (M/M) and Th2 cytokines in the CNS may be pivotal in determining the outcome of lesion development. We examined the effects of mixtures of cytokines on gene expression by CNS glial cells, as mixtures of cytokines are present in MS lesions, which in turn contain mixtures of glial cells. In this initial analysis by gene array, we examined changes at 6 hours to identify early changes in gene expression that represent primary responses to the cytokines. Rat glial cells were incubated with mixtures of Th1, M/M and Th2 cytokines for 6 hours and examined for changes in early gene expression employing microarray gene chip technology. A minimum of 814 genes were differentially regulated by one or more of the cytokine mixtures in comparison to controls, including changes in expression in a large number of genes for immune system-related proteins. Expression of the proteins for these genes likely influences development and inhibition of MS lesions as well as protective and regenerative processes. Analysing gene expression for the effects of various combinations of exogenous cytokines on glial cells in the absence of the confounding effects of inflammatory cells themselves should increase our understanding of cytokine-induced pathways in the CNS.

Down-regulation of autoreactive T-cells by HMG CoA reductase inhibitors

The inhibitors of HMG CoA reductase (statins) are widely used as cholesterol-lowering drugs with excellent safety records in hypercholesterolemic patients. Statins exert pleiotropic effects on a variety of cells, and they were recently described as a new class of immune modulators. Depending on their structure, dose, and route of administration, statins regulate the function of both the antigen-presenting cells and T-cells by HMG CoA reductase-dependent and independent mechanisms. Herein, we describe these mechanisms leading to prevention, amelioration, and reversal of autoimmune diseases. We also present data from our laboratories showing for the first time that in a double transgenic mouse model for autoimmune diabetes, atorvastatin (lipitor) prevented the onset of disease when administered in the neonatal period, and stabilized the glucose levels when administered in mice developing a mild form of diabetes.

Multiple sclerosis – novel insights and new therapeutic strategies

PURPOSE OF REVIEW

This review focuses on novel aspects of the pathogenesis and advances in the therapy of multiple sclerosis (MS).

RECENT FINDINGS

Recent observations suggest that early lesion development in MS may start in some forms with oligodendrocyte death and that inflammation appears as a secondary phenomenon only. The lack of sufficient remyelination in MS may be the result of a disturbed function of basic helix-loop-helix transcription factors. Clinically the identification of patients with a clinically isolated syndrome at high risk to develop clinically definite MS remains difficult; the predictive value of serum antibodies against myelin proteins remains controversial. The role of neutralizing antibodies in interferon therapy is discussed. New therapeutic approaches in MS are emerging.

SUMMARY

The existing view on the pathogenesis of MS is still changing. The original assumption that cell-mediated demyelination is the key event in lesion development dictating clinical disability is critically reviewed and alternative pathways have been suggested. Oligodendrocyte death, axonal loss, the role of CD8 T lymphocytes, T regulatory cells, and B lymphocytes have come into the focus of newly evolving concepts in MS pathogenesis. A deepened understanding of the immunopathogenesis of this disease translates into innovative therapeutic approaches, such as blockade of alpha4 integrins by a humanized monoclonal antibody. In various animal models cell-replacement strategies yield promising results; however, turning these findings into an effective therapy in MS patients has a long way to go.

Modular Transcriptional Activity Characterizes the Initiation and Progression of Autoimmune Encephalomyelitis

Murine experimental autoimmune encephalomyelitis is a well-established model that recapitulates many clinical and physiopathological aspects of multiple sclerosis (MS). An important conceptual development in the understanding of both experimental autoimmune encephalomyelitis and MS pathogenesis has been the compartmentalization of the mechanistic process into two distinct but overlapping and connected phases, inflammatory and neurodegenerative. However, the dynamics of CNS transcriptional changes that underlie the development and regression of the phenotype are not well understood. Our report presents the first high frequency longitudinal study looking at the earliest transcriptional changes in the CNS of NOD mice immunized with myelin oligodendrocyte glycoprotein 35-55 in CFA. Microarray-based gene expression profiling and histopathological analysis were performed from spinal cord samples obtained at 13 time points around the first clinical symptom (every other day until day 11 and every day onward until day 19 postimmunization). Advanced statistics and data-mining algorithms were used to identify expression signatures that correlated with disease stage and histological profiles. Discrete phases of neuroinflammation were accompanied by distinctive expression signatures, in which altered immune to neural gene expression ratios were observed. By using high frequency gene expression analysis we captured expression profiles that were characteristic of the transition from innate to adaptive immune response in this experimental paradigm between days 11 and 12 postimmunization. Our study demonstrates the utility of large-scale transcriptional studies and advanced data mining to decipher complex biological processes such as those involved in MS and other neurodegenerative disorders.

Analysis of microglial gene expression: identifying targets for CNS neurodegenerative and autoimmune disease

Microglia are the tissue macrophage of the central nervous system (CNS) and their activation is among the earliest signs of CNS dysfunction and disease. Because microglia express many macrophage markers, they are presumed to act primarily as effectors of CNS inflammation and destruction. While such responses are beneficial to the extent that they destroy CNS pathogens, these responses do have the potential to have neurotoxic outcomes. Consequently, therapies for many CNS neurodegenerative and inflammatory diseases have been directed at suppressing microglial function. There is evidence to suggest that microglia play an important role during CNS development and maintenance of CNS function that may go beyond simple defense against pathogens. Molecular analysis of microglial phenotypes and function has revealed three striking findings: (i) that microglia are a unique CNS-specific type of tissue macrophage; (ii) that they are highly heterogeneous within the healthy CNS; and (iii) that microglial responses are exquisitely tailored to specific regions of the CNS and specific pathological insults. We suggest that ubiquitous suppression (rather than targeted manipulation) of microglial function may fail to fully ameliorate CNS pathology and may even ultimately promote maladaptive outcomes.