The pathogenesis of multiple sclerosis: is it really a primary inflammatory process?

Imaging Surrogates of Disease Activity in Neuromyelitis Optica Allow Distinction from Multiple Sclerosis

Inflammatory demyelinating lesions of the central nervous system are a common feature of both neuromyelitis optica and multiple sclerosis. Despite this similarity, it is evident clinically that the accumulation of disability in patients with neuromyelitis optica is relapse related and that a progressive phase is very uncommon. This poses the question whether there is any pathological evidence of disease activity or neurodegeneration in neuromyelitis optica between relapses. To investigate this we conducted a longitudinal advanced MRI study of the brain and spinal cord in neuromyelitis optica patients, comparing to patients with multiple sclerosis and controls. We found both cross-sectional and longitudinal evidence of diffusely distributed neurodegenerative surrogates in the multiple sclerosis group (including thalamic atrophy, cervical cord atrophy and progressive widespread diffusion and myelin water imaging abnormalities in the normal appearing white matter) but not in those with neuromyelitis optica, where localised abnormalities in the optic radiations of those with severe visual impairment were noted. In addition, between relapses, there were no new silent brain lesions in the neuromyelitis optica group. These findings indicate that global central nervous system neurodegeneration is not a feature of neuromyelitis optica. The work also questions the theory that neurodegeneration in multiple sclerosis is a chronic sequela to prior inflammatory and demyelinating pathology, as this has not been found to be the case in neuromyelitis optica where the lesions are often more destructive.

Percutaneous transluminal angioplasty for treatment of chronic cerebrospinal venous insufficiency (CCSVI) in multiple sclerosis patients

BACKGROUND

Multiple sclerosis (MS) is a leading cause of neurological disability in young adults. The most widely accepted hypothesis regarding its pathogenesis is that it is an immune-mediated disease. It has been hypothesised more recently that chronic venous congestion may be an important factor in the pathogenesis of MS. This concept has been named 'chronic cerebrospinal venous insufficiency' (CCSVI) and is characterised by stenoses of either the internal jugular or azygos veins, or both. It is suggested that these stenoses restrict the normal blood flow from the brain, causing the deposition of iron in the brain and the eventual triggering of an auto-immune response. The proposed treatment for CCSVI is percutaneous transluminal angioplasty, also known as the 'liberation procedure', which is claimed to improve the blood flow in the brain thereby alleviating some of the symptoms of MS.

OBJECTIVES

To assess the effects of percutaneous transluminal angioplasty for the treatment of CCSVI in people with MS.

SEARCH METHODS

We searched the following databases up to June 2012: The Cochrane Multiple Sclerosis and Rare Diseases of the Central Nervous System Group Specialised Register, CENTRAL in The Cochrane Library 2012, Issue 5, MEDLINE (from 1946), EMBASE (from 1974), and reference lists of articles. We also searched several online trials registries for ongoing trials.

SELECTION CRITERIA

Randomised controlled trials assessing the effects of percutaneous transluminal angioplasty in adults with multiple sclerosis, that have been diagnosed to have CCSVI.

DATA COLLECTION AND ANALYSIS

Our searches retrieved 159 references, six of which were to ongoing trials. Based on assessment of the title or abstract, or both, we excluded all of the studies, with the exception of one which was evaluated following examination of the full text report. However, this study also did not meet our inclusion criteria and was subsequently excluded.

MAIN RESULTS

No randomised controlled trials met our inclusion criteria.

AUTHORS' CONCLUSIONS

There is currently no high level evidence to support or refute the efficacy or safety of percutaneous transluminal angioplasty for treatment of CCSVI in people with MS. Clinical practice should be guided by evidence supported by well-designed randomised controlled trials: closure of some of the gaps in the evidence may be feasible at the time of completion of the six ongoing clinical trials.

Natalizumab for relapsing remitting multiple sclerosis

BACKGROUND

Natalizumab (NTZ) (Tysabri(®)) is a monoclonal antibody that inhibits leukocyte migration across the blood-brain barrier, thus reducing inflammation in central nervous system, and has been approved worldwide for the treatment of relapsing-remitting multiple sclerosis (RRMS).

OBJECTIVES

To evaluate the efficacy, tolerability and safety of NTZ in the treatment of patients with RRMS.

SEARCH STRATEGY

We searched the Cochrane Multiple Sclerosis Group Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, 2010, Issue 1), MEDLINE (PubMed) and EMBASE, all up to 19 February 2010, and bibliographies of papers. Handsearching was carried out. Trialists and pharmaceutical companies were contacted. Furthermore, the websites of US Food and Drug Administration (FDA), the European Medicines Evaluation Agency (EMA) and the National Institute for health and Clinical Excellence (NICE) were also checked.

SELECTION CRITERIA

All double-blind, randomised, controlled trials analysing more than a single infusion of NTZ (dosage > 3 mg/kg intravenous infusion every 4 weeks), also including its use as add-on treatment, versus placebo or other drugs in patients with RRMS. No restrictions on the basis of duration of treatment or length of follow up.

DATA COLLECTION AND ANALYSIS

Three reviewers independently selected articles which met the inclusion criteria. Disagreements were solved by discussion. Two reviewers independently extracted the data and assessed the methodological quality of each trial. Missing data was sought by contacting principal authors and Biogen Idec, through Biogen-Dompé Italia.

MAIN RESULTS

Three studies met the inclusion criteria. These included one placebo-controlled trial (942 patients) and two add-on placebo-controlled trials, i.e. one plus glatiramer acetate (110 patients) and the second plus interferon beta-1a (1171 patients).This review assessed the efficacy, tolerability and safety of NTZ in patients with RRMS. Data was conclusive with respect to efficacy and tolerability, but not safety. As far as efficacy is concerned, the results showed statistically significant evidence in favour of NTZ for all the primary outcomes and for the secondary ones where data was available. NTZ reduced the risk of experiencing at least one new exacerbation at 2 years by about 40% and of experiencing progression at 2 years by about 25% as compared to a control group. MRI parameters showed statistical evidence in favour of participants receiving NTZ. Infusion reactions, anxiety, sinus congestion, lower limb swelling, rigors, vaginitis and menstrual disorders were reported as adverse events (AEs) more frequently after NTZ treatment. In this review NTZ was found to be well tolerated over a follow-up period of two years: the number of patients experiencing at least one AE (including severe and serious AEs) during this period did not differ between NTZ-treated patients and controls. Safety concerns have been raised about Progressive Multifocal Leukoencephalopathy (PML). In the trials included in this review, two cases of PML were encountered: one in a patient who had received 29 doses of NTZ and a second fatal case of PML in another patient after 37 doses of NTZ. Our protocol was insufficient to evaluate PML risk as well as other rare and long-term adverse events such as cancers and other opportunistic infections, which are very important issues in considering the risk/benefit ratio of NTZ.

AUTHORS' CONCLUSIONS

Although one trial did not contribute to efficacy results due to its duration, we found robust evidence in favour of a reduction in relapses and disability at 2 years in RRMS patients treated with NTZ. The drug was well tolerated. There are current significant safety concerns due to reporting of an increasing number of PML cases in patients treated with NTZ. This review was unable to provide an up-to-date systematic assessment of the risk due to the maximum 2 year-duration of the trials included. An independent systematic review of the safety profile of NTZ is warranted. NTZ should be used only by skilled neurologists in MS centres under surveillance programs.All the data in this review came from trials supported by the Pharmaceutical Industry. In agreement with the Cochrane Collaboration policy, this may be considered a potential source of bias.

The effect of smoking on the symptoms and progression of multiple sclerosis: a review

Multiple sclerosis (MS) is a chronic inflammatory neurodegenerative disorder of the central nervous system with characteristic demyelinating lesions and axonal loss. MS accounts for the most common cause of neurological disability in young adults in the Western world. The clinical manifestations and the course of MS are highly variable. The early stage of the disease is usually characterized by attacks of neurological dysfunction with complete or incomplete recovery, however, with time disability accumulates in many patients. MS is believed to result from an interplay between susceptibility genes and environmental factors, one of which is smoking. Smoking, a worldwide epidemic, can be regarded as an important risk factor for MS particularly because of its modifiable nature in the quest to prevent or temper the disease course in MS as well as providing possible insights into MS pathogenesis. There are also reports that smoking may influence the symptoms and disease progression in patients with MS. The purpose of this article is to review the effects of smoking on MS symptoms and progression. We conclude that (1) although there are some early reports on worsening of MS symptoms by smoking, the existing evidence is insufficient to thoroughly assess the effects of smoking on the myriad of MS symptoms and (2) smoking seems to adversely influence disease progression in MS patients. We also discuss the potential biological mechanisms linking smoking and MS.

Multiple sclerosis: a practical overview for clinicians

Multiple sclerosis (MS) is the commonest disabling neurological condition to afflict young adults and therefore has a high social burden. Over several decades, there has been a considerable progress in the understanding of the disease pathogenesis as well as in the clinical management of MS patients. The emphasis in managing MS patients has shifted to multidisciplinary teams working in specialist groups. A review of the literature was conducted using MedLine to identify recent advances in MS. The current consensus is that MS is an autoimmune disease triggered by environmental agents acting in genetically susceptible people. Based on that concept, new methods of immune intervention procedures have been introduced into clinical practice. Licensed first-line disease-modifying therapies reduce the MS attack or relapse rate by a third and delaying short-term disease progression. More effective therapies have emerged; however, these are associated with increased risks. New clinical and pathological insights are making us question the aetiology and pathogenesis of MS. The recognition of pathological heterogeneity has raised the question of whether MS is a single disease entity or a syndrome. Recent evidence suggests that the pathological subtype may predict therapeutic response to specific therapies. A new novel auto-antibody has defined a subset of neuromyelitis optica or Devic's disease as being distinct from MS. This is an attractive concept that is not widely accepted. The observation that MS progresses despite immunosuppressive therapy suggests that MS may be a neurodegenerative disease with overlapping immune activation possibly in response to the release of central nervous system auto-antigens. The development of neuroprotective therapies for MS is required to prevent the devastating effects of long-term disability as a result of progressive disease.

Preconditioning with cobalt chloride or desferrioxamine protects oligodendrocyte cell line (MO3.13) from tumor necrosis factor-alpha-mediated cell death

Hypoxia-inducible factor-1alpha (HIF-1alpha) is a transcription factor induced under hypoxic conditions. HIF-1alpha promotes the expression of genes encoding proteins that increase the cellular supply of oxygen and promote survival in periods of cellular stress and availability of cellular energy. We examined the effect of desferrioxamine (DFO) and cobalt chloride (CoCl(2)), two agents known to increase the stability of HIF-1alpha, and its effect on the survivability of an oligodendroglial cell line, MO3.13, when cultured with tumor necrosis factor-alpha (TNFalpha). Our studies showed that, unlike a murine microglial cell line (BV-2), MO3.13 cells do not induce HIF-1alpha in the presence of TNFalpha. MO3.13 cells do stabilize HIF-1alpha in the presence of DFO or CoCl(2). When MO3.13 cell were preconditioned with either DFO or CoCl(2), addition of TNFalpha further increased protein levels of HIF-1alpha. The mechanisms that underlie the increase in protein levels of HIF -1alpha seen, following addition of TNFalpha in preconditioned cells is due to an increase in transcription of the HIF-1alpha gene. Increased cellular levels of HIF-1alpha is associated with improved survival of MO3.13 cells, when cultured with TNFalpha after a period of preconditioning by DFO or CoCl(2). These studies suggest that compoundsthat increase HIF-1alpha can function as neuroprotective agents in inflammatory disorders of the CNS.

Transient 5-(4-phenylbutoxy)psoralen (PAP-1) treatment dissociates developing pathologies in autoimmune optic neuritis into two distinct pathology profiles

Discovery of treatments to protect axonal function of neurons and prevent permanent disability associated with progressive multiple sclerosis (MS) has faced the uphill challenge of assessing relatively small changes in accumulated axon damage within a background environment that is disorganized by CNS inflammation. We hypothesized that transient immunosuppression after initiation of MS-like autoimmune mechanisms would disassociate development of MS-like myelinated axon pathology from development of CNS inflammation in a rat model of autoimmune optic neuritis (AON). A rat model of myelin oligodendrocyte glycoprotein peptide-induced AON was transiently treated (on days 3-7 after antigen exposure) with 5-(4-phenylbutoxy)psoralen (PAP-1), an immunomodulatory drug previously shown specifically to suppress proliferation of effector memory T-cells and immunoglobulin class-switched B-cells. Thirteen days after antigen exposure, optic nerves were harvested for quantitative assessment of 12 MS-associated pathologies using microfluorimetry. With one exception, the immunoreactivities (-ir) for eight markers of MS-like neuroinflammation and immune infiltration were significantly reduced (P < 0.05) by transient PAP-1 treatment, often to levels significantly below those detected in normal control rat optic nerves. With one exception, four immunoreactive markers of MS-like myelinated axon pathology were detected at levels indicating increased axon/myelin pathology compared with vehicle-treated rats with AON (P < 0.05). These data suggest the conclusion that early causative mechanisms in CNS autoimmunity initiate signaling mechanisms that diverge into two separate pathways, one that is strongly associated with inflammatory responses and one that is associated predominantly with disturbed axon-myelin interactions and impaired fast axonal transport.

Contrasting roles for axonal degeneration in an autoimmune versus viral model of multiple sclerosis: When can axonal injury be beneficial?

Although demyelination is a cardinal feature in multiple sclerosis, axonal injury also occurs. We tested whether a delay in axonal degeneration could affect the disease severity in two models for multiple sclerosis: experimental autoimmune encephalomyelitis (EAE) and Theiler's murine encephalomyelitis virus (TMEV) infection. We compared wild-type C57BL/6 (B6) mice with C57BL/Wld(s) (Wld) mice, which carry a mutation that delays axonal degeneration. In EAE, both mouse strains were sensitized with myelin oligodendrocyte glycoprotein (MOG)(35-55) peptide and showed a similar disease onset, MOG-specific lymphoproliferative responses, and inflammation during the acute stage of EAE. However, during the chronic stage, B6 mice continued to show paralysis with a greater extent of axonal damage, demyelination, and MOG-specific lymphoproliferative responses compared with Wld mice, which showed complete recovery. In TMEV infection, only Wld mice were paralyzed and had increased inflammation, virus antigen-positive cells, and TMEV-specific lymphoproliferative responses versus infected B6 mice. Because TMEV can use axons to disseminate in the brain, axonal degeneration in B6 mice might be a beneficial mechanism that limits the virus spread, whereas slow axonal degeneration in Wld mice could favor virus spread. Therefore, axonal degeneration plays contrasting roles (beneficial versus detrimental) depending on the initiator driving the disease.