Polyclonal immunoglobulins for intravenous use do not influence the behaviour of cultured oligodendrocytes

Immunoglobulins Treatment in Multiple Sclerosis and Experimental Autoimmune Encephalomyelitis

Intravenously administered immunoglobulins (IgG) treatment has several modes of action that can regulate the immune response during different steps of the inflammatory process in experimental autoimmune encephalomyelitis (EAE) and Multiple Sclerosis (MS). The immunomodulatory effects IgG are largely dependent on their ability to interact with membrane molecules of lymphocytes and monocytes. Better understanding of these mechanisms of action in relation to the pathogenesis of MS, is important in order to decide the time of initiation and the duration of treatment in MS patients. In order to have the best beneficial effect on disease course, future research should focus on the initial events that activate the disease and on the early treatment modalities of IgG in MS.

Investigation of Cuprizone Inactivation by Temperature

Animal models, such as cuprizone (bis-cyclohexanone oxaldihydrazone) feeding, are helpful to study experimental demyelination and remyelination in the context of diseases like multiple sclerosis. Cuprizone is a copper chelator, which when supplemented to the normal food of C57BL/6J mice in a concentration of 0.2% leads to oligodendroglial loss, subsequent microglia and astrocyte activation, resulting in demyelination. Termination of the cuprizone diet results in remyelination, promoted by newly formed mature oligodendrocytes. The exact mode of cuprizone's action is not well understood, and information about its inactivation and cleavage are still not available. The knowledge of these processes could lead to a better understanding of cuprizone's mode of action, as well as a safer handling of this toxin. We therefore performed experiments with the aim to inactivate cuprizone by thermal heating, since it was suggested in the past that cuprizone is heat sensitive. C57BL/6J mice were fed for 4 weeks with 0.2% cuprizone, either thermally pretreated (60, 80, 105, 121 °C) or not heated. In addition, primary rat oligodendrocytes, as a known selective toxic target of cuprizone, were incubated with 350 μM cuprizone solutions, which were either thermally pretreated or not. Our results demonstrate that none of the tested thermal pretreatment conditions could abrogate or restrict the toxic and demyelinating effects of cuprizone, neither in vitro nor in vivo. In conclusion, the current study rebuts the hypothesis of cuprizone as a heat-sensitive compound, as well as the assumption that heat exposure is a reason for an insufficient demyelination of cuprizone-containing pellets.

Prospect of brain-machine interface in motor disabilities: the future support for multiple sclerosis patient to improve quality of life

Multiple sclerosis (MS) is an autoimmune neurological disorder, which has impacted health related quality of life (HRQoL) more intensively than any other neurological disorder. The approaches to improve the health standard in MS patient are still a subject of primary importance in medical practice and seek a lot of experimental exploration. The present review briefly explains the anomaly in neuron anatomy and dysfunction in signal transmission arising in the context with the chronic cerebrospinal venous insufficiency (CCSVI), a recent hypothesis related with MS pathophysiology. Subsequently, it insights brain-machine interface (BMI) as an alternative approach to improve the HRQoL of MS subjects. Information sources were searched from peer-reviewed data bases (Medline, BioMed Central, PubMed) and grey-literature databases for data published in 2000 or later. We also did systemic search in edited books, articles in seminar papers, reports extracted from newspapers and scientific magazines, articles accessed from internet; mostly using PubMed, Google search engine and Wikipedia. Out of approximately 178, 240 research articles obtained using selected keywords, those articles were included in the present study which addresses the latest definitions of HRQol and latest scientific and ethical developments in the research of MS and BMI. The article presented a brief survey of CCSVI mediated MS and BMI-approach as a treatment to serve the patients suffering from disabilities as a result of MS, followed by successful precedence of BMI approach. Apart from these, the major findings of selected research articles including the development of parameters to define HRQoL, types and development of BMIs and its role in interconnecting brain with actuators, along with CCSVI being a possible cause of MS have formed the foundations to conclude the findings of the present review article. We propose a perspective BMI approach and promises it holds for future research to improve HRQoL in MS patients. In addition, we propose that brain-computer interfaces will be the core of new treatment modalities in the future for MS disabilities.

Basic principles of intravenous immunoglobulin (IVIg) treatment

The original rationale for the therapeutic application of immunoglobulins was prevention and treatment of infectious diseases. With the description of agammaglobulinemia, substitution therapy became the primary indication for the use of immunoglobulins. Limitations and side effects of the intramuscular administration of immunoglobulins led to the development of preparations for intravenous use (IVIg). In the early 1980s an immunomodulatory effect of IVIg was described. Since then, the efficacy of IVIg has been established in controlled trials for diseases like idiopathic thrombocytopenic purpura, Kawasaki disease, Guillain-Barré syndrome, dermatomyositis, and many others. There is a large body of evidence that IVIg can modulate an immune reaction at the level of T cells, B cells, and macrophages, interferes with antibody production and degradation, modulates the complement cascade, and has effects on the cytokine network. However, the precise mechanism of action is not yet clear.

Modulation of rat oligodendrocyte precursor cells by the chemokine CXCL12

Migration, proliferation, and differentiation of oligodendrocyte precursor cells are essential for the assembly of myelin in the central nervous system. Knowledge on the regulation of these precursor cells is therefore of great importance for the understanding of developmental myelination and remyelination in demyelinating diseases. Here, we show that primary rat oligodendrocyte precursor cells express the chemokine receptor CXCR4. Stimulation with the ligand CXCL12 (SDF-1 alpha) leads to intracellular Ca elevation. Furthermore, 10 ng/ml CXCL12 augmented differentiation of precursors into mature oligodendrocytes. Migration toward growth factor conditioned medium was inhibited by CXCL12, while proliferation was only slightly modulated. The effect of CXCL12 on both migration and differentiation was blocked using a G protein antagonist. These data suggest a role for CXCL12 and oligodendroglial CXCR4 receptors during developmental myelination and repair in demyelinating diseases of the central nervous system.

Activated microglia stimulate transcriptional changes in primary oligodendrocytes via IL-1beta

No therapy currently exists to repair demyelinated lesions in multiple sclerosis. However, the use of IgM antibodies may provide a valuable therapeutic avenue for evoking such repair. Unfortunately, the mechanism of immunoglobulin action in CNS repair is currently unknown but may depend upon complex interactions between multiple cell types rather than upon direct activation of a single cell type. Using rat mixed glial cultures containing oligodendrocytes, microglia, and astrocytes, we found that the Fc portion of human IgM shifts microglia to an activated phenotype, reduces glial proliferation, upregulates a variety of immediate early genes, including JunB, Egr-1, and c-Fos, and stimulates microglial production and release of IL-1beta. Microglia-derived IL-1beta consequently triggers transcriptional upregulation of immediate early genes such as c-Jun, Egr-1, and c-Fos in the mixed glial cultures, and stimulates the upregulation of late response genes such as lipocalin in purified oligodendrocytes. Treatment with an IL-1beta receptor antagonist abrogates the effects of Fcmu on glial proliferation and prevents the upregulation of lipocalin in response to Fcmu, but does not prevent Fcmu-mediated upregulation of IL-1beta, suggesting that IL-1beta mediates at least some of the downstream effects of Fcmu in mixed glial cultures. We hypothesize that Fcmu-stimulated IL-1beta-induced upregulation of immediate early and late response genes in oligodendrocytes may promote CNS repair.

Cerebrospinal fluid immunoglobulin G promotes oligodendrocyte progenitor cell migration

Multiple sclerosis (MS) is characterized by demyelination of the CNS with associated neurological deficits. Remyelination can occur but is often incomplete. The process of myelin repair requires the proliferation and migration of oligodendrocyte progenitor cells (OPC) into the lesion from the neighboring areas. OPC migration is altered by several factors, including antibodies that bind to OPC surface proteins. We have previously reported elevated anti-OSP/claudin-11 antibodies in the cerebrospinal fluid (CSF) of MS patients and that anti-OSP/claudin-11 antibodies generated in rabbits can inhibit OPC migration. In the study presented here, we investigated the effect of CSF IgG from MS patients and controls on OPC migration in culture. Rat OPC cultured with CSF from MS patients tended to migrate more than those cultured with control CSF, but this did not reach statistical significance. To determine whether the IgG fraction in the CSF influenced migration, we removed it using protein-A sepharose. A dramatic decrease in OPC migration was found in both MS (45 +/- 24 vs.16 +/- 9) and control (40 +/- 19 vs. 22 +/- 13) samples after IgG was removed (P <.05). Anti-OSP/claudin-11 antibody concentration did not significantly correlate with OPC migration. These data demonstrate that CSF IgG promotes OPC migration. Identification of the specific IgG fraction responsible for this effect could lead to novel therapies to promote recovery in MS.

Rat oligodendroglial cell lines express a functional receptor for the chemokine CCL3 (macrophage inflammatory protein-1alpha)

Regulation of migration, proliferation and differentiation of oligodendrocyte precursor cells is central for the accurate assembly of myelin in the CNS. The recent demonstration that oligodendrocyte precursors express chemokine receptors suggests that chemokines are candidates to play a role in the regulation of migration, since they are important molecules involved in the trafficking of other cell types. Since the chemokine CCL3 (macrophage inflammatory protein-1alpha) is expressed in various CNS diseases, we have used the oligodendrocyte precursor cell lines CG4 and OLN-93 to study the expression of receptors for CCL3 and the influence of CCL3 on oligodendrocyte precursor behaviour. Oligodendroglial cells express the receptor CCR1, but not CCR5. CCL3 induced an intracellular rise in Ca(2+), a typical signalling event of G protein-coupled receptors. Migration of cells was slightly inhibited by CCL3, while proliferation was not affected. The implications on CNS development, during which expression of chemokines and their receptors occurs, and on inflammatory demyelinating diseases of the CNS, like multiple sclerosis, are discussed.

Polyclonal IgM influence oligodendrocyte precursor cells in mixed glial cell cultures: implications for remyelination

Polyclonal immunoglobulins for intravenous use (IVIg) are a potent immunomodulator and have been shown to be effective in several immune-mediated diseases. This includes inflammatory demyelinating diseases of the central nervous system (CNS) like multiple sclerosis (MS). Besides their immunomodulatory function, IVIg have been proposed to enhance remyelination based on studies in the animal model of Theiler's murine encephalomyelitis virus (TMEV). Disappointingly, recent treatment trials in patients with MS have failed to demonstrate repair of longstanding deficits. Since the clinical trials have used IVIg that contained nearly exclusively IgG, whereas the most pronounced effect in TMEV was seen with IgM, this could be a possible explanation for the negative outcome in the MS trials. Here we have examined the effects of a new polyclonal IgM preparation (IVIgM) on cultured oligodendrocyte precursor cells (OPCs). To achieve successful remyelination, OPCs proliferate, migrate, and differentiate into mature myelinating oligodendrocytes. IVIgM and commercial IVIg preparations had no influence on proliferation and differentiation of either isolated OPCs or OPCs in coculture with microglia. In contrast, IVIgM inhibited the proliferation of OPCs in mixed glial cultures containing astrocytes and microglia. This was not seen in cultures treated with IVIg, albumin, or interferon-gamma (IFN-gamma), suggesting that this is a specific effect of IVIgM. Differentiation was slightly delayed by IVIgM in mixed glial cultures, but this was not statistically significant and interferon-gamma had a similar effect. These results underline the importance of IgM in influencing OPCs and corroborate the in vivo findings that polyclonal IgM are more potent than IgG in their capacity to influence remyelination. The exact mechanism of how this modulation of OPCs is achieved remains unknown, but a complex interaction among all cells present in the CNS has to be postulated.

Therapeutic approaches in multiple sclerosis: lessons from failed and interrupted treatment trials

The therapy for multiple sclerosis (MS) has changed dramatically over the past decade. Recent immunobiological findings and current pathophysiological concepts together with advances in biotechnology, improvements in clinical trial design and development of magnetic resonance imaging have led to a variety of evaluable therapeutic approaches in MS. However, in contrast to the successfully introduced and established immunomodulatory therapies (e.g. interferon-beta and glatiramer acetate), there have been a remarkable number of therapeutic failures as well. Despite convincing immunological concepts, impressive data from animal models and promising results from phase I/II studies, the drugs and strategies investigated showed no benefit or even turned out to have unexpectedly severe adverse effects. Although to date there is no uniformly accepted model for MS, there is agreement on the significance of inflammatory events mediated by autoreactive T cells in the CNS. These can be modified therapeutically at the individual steps of a hypothetical pathogenetic cascade. Crucial corners like: the prevalence and peripheral activation of CNS-autoreactive T cells in the periphery;adhesion and penetration of T cells into the CNS;local activation and proliferation and;de- and remyelination processes can be targeted through their putative mediators. Like a 'specificity pyramid', therapeutic approaches therefore cover from general immunosuppression up to specific targeting of T-cell receptor peptide major histocompatibility (MHC) complex. We discuss in detail clinical MS trials that failed or were discontinued for other reasons. These trials include cytokine modulators [tumour necrosis factor (TNF)-alpha antagonists, interleukin-10, interleukin-4, transforming growth factor-beta2], immunosuppressive agents (roquinimex, gusperimus, sulfasalazine, cladribine), inducers of remyelination [intravenous immunoglobulins (IVIg)], antigen-derived therapies [oral tolerance, altered peptide ligands (APL), MHC-Peptide blockade], T cell and T-cell receptor directed therapies (T cell vaccination, T-cell receptor peptide vaccination), monoclonal antibodies against leucocyte differentiation molecules (anti-CD3, anti-CD4), and inactivation of circulating T cells (extracorporeal photopheresis). The main conclusions that can be drawn from these 'negative' experiences are as follows. Theoretically promising agents may paradoxically increase disease activity (lenercept, infliximab), be associated with unforeseen adverse effects (e.g. roquinimex) or short-term favourable trends may reverse with prolonged follow-up (e.g. sulfasalzine). One should not be too enthusiastic about successful trials in animal models (TNFalpha blockers; oral tolerance; remyelinating effect of IVIg) nor be irritated by non-scientific media hype (deoxyspergualine; bone marrow transplantation). More selectivity can imply less efficacy (APL, superselective interventions like T-cell receptor vaccination) and antigen-related therapies can stimulate rather than inhibit encephalitogenic cells. Failed strategies are of high importance for a critical revision of assumed immunopathological mechanisms, their neuroimaging correlates, and for future trial design. Since failed trials add to our growing understanding of multiple sclerosis, 'misses' are nearly as important to the scientific process as the 'hits'.

Remyelinating strategies for the treatment of multiple sclerosis

Demyelination is the pathological hallmark of multiple sclerosis (MS) lesions. The concept of remyelination has gained acceptance in recent years, but naturally occurring remyelination is incomplete. To improve repair processes, a number of strategies have been explored experimentally and clinical trials are being carried out. In principle, remyelination can be achieved by either promoting endogenous repair mechanisms or by providing an exogenous source of myelinating cells via transplantation. Both approaches have been successful in animal models of demyelination. Besides, many studies have elucidated principal mechanisms of oligodendrocyte biology and remyelination in the central nervous system (CNS). This progress in knowledge also allowed for more specific interventions. First clinical trials to enhance endogenous remyelination have been performed, unfortunately with disappointingly negative results. This illustrates that experimental data cannot be easily transferred to human disease, and more detailed knowledge on the regulatory mechanisms of remyelination in MS is required. Recently, the first MS patient received a transplant of autologous Schwann cells. Many other cell types are being studied experimentally, including stem cells. Despite the ethical problems associated with an embryonic cell source, new developments in stem cell biology indicate that adult stem cells or bone marrow-derived cells may substitute for embryonic cells in the future. In this review, we describe the current views on oligodendrocyte biology, myelination and remyelination, and focus on recent developments leading to reconstructing, remyelinating strategies in MS.

Why does remyelination fail in multiple sclerosis?

Multiple sclerosis is a common cause of neurological disability in young adults. The disease is complex -- its aetiology is multifactorial and largely unknown; its pathology is heterogeneous; and, clinically, it is difficult to diagnose, manage and treat. However, perhaps its most frustrating aspect is the inadequacy of the healing response of remyelination. This regenerative process generally occurs with great efficiency in experimental models, and sometimes proceeds to completion in multiple sclerosis. But as the disease progresses, the numbers of lesions in which demyelination persists increases, significantly contributing to clinical deterioration. Understanding why remyelination fails is crucial for devising effective methods by which to enhance it.

Cell transplantation, myelin repair, and multiple sclerosis

A decade ago, therapeutic strategies to remyelinate the CNS in diseases such as multiple sclerosis had much experimental appeal, but translation of laboratory success into clinical treatments appeared to be a long way off. Within the past 12 months, however, the first patients with multiple sclerosis have received intracerebral implants of autologous myelinating cells. Here we review the clinical and biological problems presented by multiple sclerosis disease processes, and the background to the development of myelin-repair strategies. We attempt to highlight those areas where difficulties have yet to be resolved, and draw on various experimental findings to speculate on how remyelinating therapies are likely to develop in the foreseeable future.

Human monoclonal antibodies reactive to oligodendrocytes promote remyelination in a model of multiple sclerosis

Promoting remyelination, a major goal of an effective treatment for demyelinating diseases, has the potential to protect vulnerable axons, increase conduction velocity, and improve neurologic deficits. Strategies to promote remyelination have focused on transplanting oligodendrocytes (OLs) or recruiting endogenous myelinating cells with trophic factors. Ig-based therapies, routinely used to treat a variety of neurological and autoimmune diseases, underlie our approach to enhance remyelination. We isolated two human mAbs directed against OL surface antigens that promoted significant remyelination in a virus-mediated model of multiple sclerosis. Four additional OL-binding human mAbs did not promote remyelination. Both human mAbs were as effective as human i.v. Ig, a treatment shown to have efficacy in multiple sclerosis, and bound to the surface of human OLs suggesting a direct effect of the mAbs on the cells responsible for myelination. Alternatively, targeting human mAbs to areas of central nervous system (CNS) pathology may facilitate the opsonization of myelin debris, allowing repair to proceed. Human mAbs were isolated from the sera of individuals with a form of monoclonal gammopathy. These individuals carry a high level of monoclonal protein in their blood without detriment, lending support to the belief that administration of these mAbs as a therapy would be safe. Our results are (i) consistent with the hypothesis that CNS-reactive mAbs, part of the normal Ig repertoire in humans, may help repair and protect the CNS from pathogenic immune injury, and (ii) further challenge the premise that Abs that bind OLs are necessarily pathogenic.

Oligodendroglia are protected from antibody-mediated complement injury by normal immunoglobulins ("IVIg")

High-dose intravenous immunoglobulin (IVIg) treatment has become a promising immune therapy that can modulate the immune system at several levels, including the complement cascade. In relation to inflammatory demyelinating disease, there is some clinical evidence for the suppression of disease activity by IVIg, while a role in promoting remyelination after experimental myelin damage has been described. Antibody and complement deposition have been implicated in the immune attack in some cases of multiple sclerosis (MS), and to investigate the mechanisms of action of IVIg, we studied the effect of IVIg using the model of complement-mediated cell injury on oligodendroglia in vitro. There was no effect on direct complement lysis of the oligodendroglial cell line CG4, but antibody-dependent complement damage was inhibited in a dose-dependent manner by IVIg. These results were confirmed with primary cultures of oligodendrocyte precursor cells (OPC) and oligodendrocytes. The addition of excess C1, C3, and C4 did not influence the inhibitory effect of IVIg, implying that binding of these complement components does not play a role, in contrast to other experimental models of complement damage. F(ab')2 immunoglobulin fragments were at least partially responsible for the effect. We conclude that IVIg may be protective in antibody-mediated complement injury of oligodendrocytes and their progenitors, and that this effect is likely to be mediated via antibody binding, rather than interference with complement activation. Inhibition of inflammatory mechanisms, as opposed to a direct effect on remyelinating cells, may underlie the role of IVIg in promoting myelin repair in experimental models.

Therapeutic strategies in multiple sclerosis. II. Long-term repair

Spontaneous myelin repair in multiple sclerosis (MS) provides a striking example of the brain's inherent capacity for sustained and stable regenerative tissue repair--but also clearly emphasizes the limitations of this capacity; remyelination ultimately fails widely in many patients, and disability and handicap accumulate. The observation of endogenous partial myelin repair has raised the possibility that therapeutic interventions designed to supplement or promote remyelination might have a useful and significant impact both in the short term, in restoring conduction, and in the long term, in safeguarding axons. Therapeutic remyelination interventions must involve manipulations to either the molecular or the cellular environment within lesions; both depend crucially on a detailed understanding of the biology of the repair process and of those glia implicated in spontaneous repair, or capable of contributing to exogenous repair. Here we explore the biology of myelin repair in MS, examining the glia responsible for successful remyelination, oligodendrocytes and Schwann cells, their 'target' cells, neurons and the roles of astrocytes. Options for therapeutic remyelinating strategies are reviewed, including glial cell transplantation and treatment with growth factors or other soluble molecules. Clinical aspects of remyelination therapies are considered--which patients, which lesions, which stage of the disease, and how to monitor an intervention--and the remaining obstacles and hazards to these approaches are discussed.

Treatment of multiple sclerosis: recent trials and future perspectives

In the past year, further evidence establishing the usefulness of beta interferons and glatiramer in the treatment of relapsing-remitting multiple sclerosis has been advanced. Interferon-beta-1b was also shown to be efficacious in secondary progressive multiple sclerosis. This and other trials of symptomatic treatments are reviewed. Based on an appraisal of recent experimental studies, future promising approaches to intervene in the chain of immunopathogenetic events are discussed.