Anti-myelin basic protein and anti-proteolipid protein specific forms of multiple sclerosis

Role of Specific Autoantibodies in Neurodegenerative Diseases: Pathogenic Antibodies or Promising Biomarkers for Diagnosis

Neurodegenerative diseases (NDDs) affect millions of people worldwide. They develop due to the pathological accumulation and aggregation of various misfolded proteins, axonal and synaptic loss and dysfunction, inflammation, cytoskeletal abnormalities, defects in DNA and RNA, and neuronal death. This leads to the activation of immune responses and the release of the antibodies against them. Recently, it has become clear that autoantibodies (Aabs) can contribute to demyelination, axonal loss, and brain and cognitive dysfunction. This has significantly changed the understanding of the participation of humoral autoimmunity in neurodegenerative disorders. It is crucial to understand how neuroinflammation is involved in neurodegeneration, to aid in improving the diagnostic and therapeutic value of Aabs in the future. This review aims to provide data on the immune system's role in NDDs, the pathogenic role of some specific Aabs against molecules associated with the most common NDDs, and their potential role as biomarkers for monitoring and diagnosing NDDs. It is suggested that the autoimmune aspects of NDDs will facilitate early diagnosis and help to elucidate previously unknown aspects of the pathobiology of these diseases.

Immune Regulatory Functions of Macrophages and Microglia in Central Nervous System Diseases

Macrophages can be characterized as a very multifunctional cell type with a spectrum of phenotypes and functions being observed spatially and temporally in various disease states. Ample studies have now demonstrated a possible causal link between macrophage activation and the development of autoimmune disorders. How these cells may be contributing to the adaptive immune response and potentially perpetuating the progression of neurodegenerative diseases and neural injuries is not fully understood. Within this review, we hope to illustrate the role that macrophages and microglia play as initiators of adaptive immune response in various CNS diseases by offering evidence of: (1) the types of immune responses and the processes of antigen presentation in each disease, (2) receptors involved in macrophage/microglial phagocytosis of disease-related cell debris or molecules, and, finally, (3) the implications of macrophages/microglia on the pathogenesis of the diseases.

Exploring the Gut-Brain Axis for the Control of CNS Inflammatory Demyelination: Immunomodulation by Bacteroides fragilis' Polysaccharide A

The symbiotic relationship between animals and their resident microorganisms has profound effects on host immunity. The human microbiota comprises bacteria that reside in the gastrointestinal tract and are involved in a range of inflammatory and autoimmune diseases. The gut microbiota's immunomodulatory effects extend to extraintestinal tissues, including the central nervous system (CNS). Specific symbiotic antigens responsible for inducing immunoregulation have been isolated from different bacterial species. Polysaccharide A (PSA) of Bacteroides fragilis is an archetypical molecule for host-microbiota interactions. Studies have shown that PSA has beneficial effects in experimental disease models, including experimental autoimmune encephalomyelitis (EAE), the most widely used animal model for multiple sclerosis (MS). Furthermore, in vitro stimulation with PSA promotes an immunomodulatory phenotype in human T cells isolated from healthy and MS donors. In this review, we discuss the current understanding of the interactions between gut microbiota and the host in the context of CNS inflammatory demyelination, the immunomodulatory roles of gut symbionts. More specifically, we also discuss the immunomodulatory effects of B. fragilis PSA in the gut-brain axis and its therapeutic potential in MS. Elucidation of the molecular mechanisms responsible for the microbiota's impact on host physiology offers tremendous promise for discovering new therapies.

Anti-Myelin Proteolipid Protein Peptide Monoclonal Antibodies Recognize Cell Surface Proteins on Developing Neurons and Inhibit Their Differentiation

Using a panel of monoclonal antibodies (mAbs) to myelin proteolipid protein (PLP) peptides, we found that in addition to CNS myelin, mAbs to external face but not cytoplasmic face epitopes immunostained neurons in immature human CNS tissues and in adult hippocampal dentate gyrus and olfactory bulbs, that is neural stem cell niches (NSCN). To explore the pathobiological significance of these observations, we assessed the mAb effects on neurodifferentiation in vitro. The mAbs to PLP 50-69 (IgG1κ and IgG2aκ), and 178-191 and 200-219 (both IgG1κ) immunostained live cell surfaces and inhibited neurite outgrowth of E18 rat hippocampal precursor cells and of PC12 cells, which do not express PLP. Proteins immunoprecipitated from PC12 cell extracts and captured by mAb-coated magnetic beads were identified by GeLC-MS/MS. Each neurite outgrowth-inhibiting mAb captured a distinct set of neurodifferentiation molecules including sequence-similar M6 proteins and other unrelated membrane and extracellular matrix proteins, for example integrins, Eph receptors, NCAM-1, and protocadherins. These molecules are expressed in adult human NSCN and are implicated in the pathogenesis of many chronic CNS disease processes. Thus, diverse anti-PLP epitope autoantibodies may inhibit neuronal precursor cell differentiation via multispecific recognition of cell surface molecules thereby potentially impeding endogenous neuroregeneration in NSCN and in vivo differentiation of exogenous neural stem cells.

B-Cell Therapies in Multiple Sclerosis

B cells play a vital function in multiple sclerosis (MS) pathogenesis through an array of effector functions. All currently approved MS disease-modifying therapies alter the frequency, phenotype, or homing of B cells in one way or another. The importance of this mechanism of action has been reinforced with the successful development and clinical testing of B-cell-depleting monoclonal antibodies that target the CD20 surface antigen. Ocrelizumab, a humanized anti-CD20 monoclonal antibody, was approved by the Food and Drug Administration (FDA) in March 2017 after pivotal trials showed dramatic reductions in inflammatory disease activity in relapsing MS as well as lessening of disability progression in primary progressive MS. These and other clinical studies place B cells at the center of the inflammatory cascade in MS and provide a launching point for development of therapies that target selective pathogenic B-cell populations.

Immunotherapy of multiple sclerosis: the state of the art

It is widely accepted that the main common pathogenetic pathway in multiple sclerosis (MS) involves an immune-mediated cascade initiated in the peripheral immune system and targeting CNS myelin. Logically, therefore, the therapeutic approaches to the disease include modalities aiming at downregulation of the various immune elements that are involved in this immunologic cascade. Since the introduction of interferons in 1993, which were the first registered treatments for MS, huge steps have been made in the field of MS immunotherapy. More efficious and specific immunoactive drugs have been introduced and it appears that the increased specificity for MS of these new treatments is paralleled by greater efficacy. Unfortunately, this seemingly increased efficacy has been accompanied by more safety issues. The immunotherapeutic modalities can be divided into two main groups: those affecting the acute stages (relapses) of the disease and the long-term treatments that are aimed at preventing the appearance of relapses and the progression in disability. Immunomodulating treatments may also be classified according to the level of the 'immune axis' where they exert their main effect. Since, in MS, a neurodegenerative process runs in parallel and as a consequence of inflammation, early immune intervention is warranted to prevent progression of relapses of MS and the accumulation of disability. The use of neuroimaging (MRI) techniques that allow the detection of silent inflammatory activity of MS and neurodegeneration has provided an important tool for the substantiation of the clinical efficacy of treatments and the early diagnosis of MS. This review summarizes in detail the existing information on all the available immunotherapies for MS, old and new, classifies them according to their immunologic mechanisms of action and proposes a structured algorithm/therapeutic scheme for the management of the disease.

Enhanced insight into the autoimmune component of glaucoma: IgG autoantibody accumulation and pro-inflammatory conditions in human glaucomatous retina

BACKGROUND

There is accumulating evidence that autoimmune components, such as autoantibodies and autoantibody depositions, play a role in the pathogenesis of neurodegenerative diseases like Alzheimeŕs disease or Multiple Sclerosis. Due to alterations of autoantibody patterns in sera and aqueous humor, an autoimmune component is also assumed in the pathogenesis of glaucoma, a common reason for irreversible blindness worldwide. So far there has been no convincing evidence that autoantibodies are accumulated in the retina of glaucoma patients and that the local immune homeostasis might be affected.

METHODS AND RESULTS

Six human glaucomatous donor eyes and nine samples from donors with no recorded ocular disease were included. Antibody microarrays were used to examine the patterns of pro-inflammatory proteins and complement proteins. Analysis of TNF-α and interleukin levels revealed a slight up-regulation exclusively in the glaucomatous group, while complement protein levels were not altered. IgG autoantibody accumulations and/or cellular components were determined by immunohistology (n = 4 per group). A significantly reduced number of retinal ganglion cells was found in the glaucomatous group (healthy: 104±7 nuclei/mm, glaucoma: 67±9 nuclei/mm; p = 0.0007). Cell loss was accompanied by strong retinal IgG autoantibody accumulations, which were at least twice as high as in healthy subjects (healthy: 5.0±0.5 IgG deposits/100 cells, glaucoma: 9.4±1.9 IgG deposits/100 cells; p = 0.004). CD27(+) cells and CD27(+)/IgG(+) plasma cells were observed in all glaucomatous subjects, but not in controls.

CONCLUSION

This work provides serious evidence for the occurrence of IgG antibody deposition and plasma cells in human glaucomatous retina. Moreover, the results suggest that these IgG deposits occurred in a pro-inflammatory environment which seems to be maintained locally by immune-competent cells like microglia. Thereby, glaucoma features an immunological involvement comparable to other neurodegenerative diseases, but also shows a multifactorial pathomechanism, which diverges and might be linked to the specific nature of both eye and retina.

Pathogenic and physiological autoantibodies in the central nervous system

In this article, we review the current knowledge on pathological and physiological autoantibodies directed toward structures in the central nervous system (CNS) with an emphasis on their regulation and origin. Pathological autoantibodies in the CNS that are associated with autoimmunity often lead to severe neurological deficits via inflammatory processes such as encephalitis. In some instances, however, autoantibodies function as a marker for diagnostic purposes without contributing to the pathological process and/or disease progression. The existence of naturally occurring physiological autoantibodies has been known for a long time, and their role in maintaining homeostasis is well established. Within the brain, naturally occurring autoantibodies targeting aggregated proteins have been detected and might be promising candidates for new therapeutic approaches for neurodegenerative disorders. Further evidence has demonstrated the existence of naturally occurring antibodies targeting antigens on neurons and oligodendrocytes that promote axonal outgrowth and remyelination. The numerous actions of physiological autoantibodies as well as their regulation and origin are summarized in this review.

B cells in multiple sclerosis: connecting the dots

Over the past two decades B cells have increasingly moved into the spotlight in multiple sclerosis (MS) research. This interest was fuelled by growing understanding and acceptance of pathological involvement of B cells and antibodies in MS. Data derived from animal models of MS, human histopathological studies, and analyses of B cells in the peripheral blood and cerebrospinal fluid (CSF) have permitted the integration of B cells in our overall picture of MS immunopathogenesis. The as yet strongest direct evidence for a central role of B cells in MS autoimmunity was the demonstration that peripheral B cell depletion leads to a rapid decline of disease-activity in MS. While lending formidable impact to peripheral blood B cells as mediators of disease activity, the effects of anti-CD20 treatment also seemingly challenged the paradigm of a role of antibodies in targeted central nervous system (CNS) myelin destruction. This review shall attempt to provide an overview of our current understanding of B cell and antibody mediated mechanisms relevant to MS. We will include findings from, both, human studies, and animal models to highlight the complexity of B cell function as it pertains to MS. B cells appear to be effective drivers of inflammatory activity in MS by way of a diverse toolset of cellular functions. These functions appear to be closely linked to B cells that can be found in the periphery. However, by serving as the source of antibodies, B cells offer a direct humoral response that may target the CNS and lead to tissue specific destruction. Therefore, B cells participate in MS pathogenesis on both sides of the blood-brain barrier.

B cells as a target of immune modulation

B cells have recently been identified as an integral component of the immune system; they play a part in autoimmunity through antigen presentation, antibody secretion, and complement activation. Animal models of multiple sclerosis (MS) suggest that myelin destruction is partly mediated through B cell activation (and plasmablasts). MS patients with evidence of B cell involvement, as compared to those without, tend to have a worse prognosis. Finally, the significant decrease in new gadolinium-enhancing lesions, new T2 lesions, and relapses in MS patients treated with rituximab (a monoclonal antibody against CD20 on B cells) leads us to the conclusion that B cells play an important role in MS and that immune modulation of these cells may ameliorate the disease. This article will explore the role of B cells in MS and the rationale for the development of B cell-targeted therapeutics. MS is an immune-mediated disease that affects over 2 million people worldwide and is the number one cause of disability in young patients. Most therapeutic targets have focused on T cells; however, recently, the focus has shifted to the role of B cells in the pathogenesis of MS and the potential of B cells as a therapeutic target.

Autoantibodies to myelin basic protein (MBP) in healthy individuals and in patients with multiple sclerosis: a role in regulating cytokine responses to MBP

Anti-myelin basic protein (-MBP) autoantibodies have generally been considered to be absent from sera from healthy individuals, but to be detectable in sera from some patients with multiple sclerosis (MS). However, their pathogenic role is uncertain. We demonstrate the presence of MBP-reactive autoantibodies in sera from 17 healthy individuals and 17 MS patients. The addition of MBP to the sera caused a dose-dependent deposition of MBP and co-deposition of immunoglobulin M (IgM) and fragments of complement component 3 (C3) on allogeneic monocytes. Calcium chelation abrogated the immunoglobulin deposition, indicating that formation of complement-activating immune complexes played a role in the binding process. Furthermore, MBP elicited tumour necrosis factor (TNF)-alpha and interleukin (IL)-10 production by normal mononuclear cells in the presence of serum from both patients and controls. Mononuclear cells from MS patients responded to MBP with the production of interferon (IFN)-gamma, IL-4 and IL-5, in addition to TNF-alpha and IL-10. The production of IFN-gamma and IL-5 was increased when MS serum was added rather than normal serum. Denaturation of MBP strongly inhibited MBP deposition and the MBP-induced IgM deposition and cytokine production, indicating that these events were facilitated by autoantibodies recognizing conformational epitopes on MBP. We infer that MBP-elicited TNF-alpha and IL-10 responses are promoted to equal extents by naturally occurring MBP autoantibodies and autoantibodies contained in MS sera. However, the latter seem to be more efficient in facilitating the production of IFN-gamma and IL-5.

Role of B Cells in Pathogenesis of Multiple Sclerosis

Despite the current limited understanding of the etiology of multiple sclerosis (MS), genetic susceptibility and environmental influences are known driving factors. MS is considered a T-cell-mediated disease given the prevalence of T cells in plaques. Plaque formation is characteristic of this disease attributable to immune mechanisms, triggered by an autoimmune attack aimed at antigens in the myelin sheath or oligodendrocyte proteins. The attack consists of the following: The role of the B cells is twofold: first, as autoreactive B cells they produce autoantibodies, secrete cytokines, clonally replicate memory B cells, and long-living plasma cells which serve to advance the diseased state by their constant production of autoantibodies. Second, as antigen-presenting cells they activate the autoreactive T cells. For this reason, the stipulation that T cell is the cornerstone of MS must be reevaluated. Various studies on pathogenesis of MS have indicated that B cells, as the humoral component of the adaptive immune system, are active participants in pathogenesis and lesion maintenance throughout the disease process. The active role of B cells and autoantibodies makes them an encouraging therapeutic target. Advances in the understanding of B-cell development and activity would allow for an enhanced strategy in the design of autoimmune treatment. For this reason, further investigation is necessary to determine whether depletion of B cells or antibodies may restore immune function.

A Tale of Two Citrullines—Structural and Functional Aspects of Myelin Basic Protein Deimination in Health and Disease

Myelin basic protein (MBP) binds to negatively charged lipids on the cytosolic surface of oligodendrocyte membranes and is responsible for adhesion of these surfaces in the multilayered myelin sheath. The pattern of extensive post-translational modifications of MBP is dynamic during normal central nervous system (CNS) development and during myelin degeneration in multiple sclerosis (MS), affecting its interactions with the myelin membranes and with other molecules. In particular, the degree of deimination (or citrullination) of MBP is correlated with the severity of MS, and may represent a primary defect that precedes neurodegeneration due to autoimmune attack. That the degree of MBP deimination is also high in early CNS development indicates that this modification plays major physiological roles in myelin assembly. In this review, we describe the structural and functional consequences of MBP deimination in healthy and diseased myelin.

Monoclonal antibodies to distinct regions of human myelin proteolipid protein simultaneously recognize central nervous system myelin and neurons of many vertebrate species

Myelin proteolipid protein (PLP), the major protein of mammalian CNS myelin, is a member of the proteolipid gene family (pgf). It is an evolutionarily conserved polytopic integral membrane protein and a potential autoantigen in multiple sclerosis (MS). To analyze antibody recognition of PLP epitopes in situ, monoclonal antibodies (mAbs) specific for different regions of human PLP (50-69, 100-123, 139-151, 178-191, 200-219, 264-276) were generated and used to immunostain CNS tissues of representative vertebrates. mAbs to each region recognized whole human PLP on Western blots; the anti-100-123 mAb did not recognize DM-20, the PLP isoform that lacks residues 116-150. All of the mAbs stained fixed, permeabilized oligodendrocytes and mammalian and avian CNS tissue myelin. Most of the mAbs also stained amphibian, teleost, and elasmobranch CNS myelin despite greater diversity of their pgf myelin protein sequences. Myelin staining was observed when there was at least 40% identity of the mAb epitope and known pgf myelin proteins of the same or related species. The pgf myelin proteins of teleosts and elasmobranchs lack 116-150; the anti-100-123 mAb did not stain their myelin. In addition to myelin, the anti-178-191 mAb stained many neurons in all species; other mAbs stained distinct neuron subpopulations in different species. Neuronal staining was observed when there was at least approximately 30% identity of the PLP mAb epitope and known pgf neuronal proteins of the same or related species. Thus, anti-human PLP epitope mAbs simultaneously recognize CNS myelin and neurons even without extensive sequence identity. Widespread anti-PLP mAb recognition of neurons suggests a novel potential pathophysiologic mechanism in MS patients, i.e., that anti-PLP antibodies associated with demyelination might simultaneously recognize pgf epitopes in neurons, thereby affecting their functions.

Multiple sclerosis

Multiple sclerosis (MS) is a complex genetic disease associated with inflammation in the central nervous system (CNS) white matter and is thought to be mediated by autoimmune processes. Clonal expansion of B cells, their antibody products, and T cells, hallmarks of inflammation in the CNS, are found in MS. The association of the disease with major histocompatibility complex genes, the inflammatory white matter infiltrates, similarities with animal models, and the observation that MS can be treated with immunomodulatory and immunosuppressive therapies support the hypothesis that autoimmunity plays a major role in the disease pathology. This review discusses the immunopathology of MS with particular focus given to regulatory T cells and the role of B cells and antibodies, immunomodulatory therapeutics, and finally new directions in MS research, particularly new methods to define the molecular pathology of human disease with high-throughput examination of germline DNA haplotypes, RNA expression, and protein structures that will allow the generation of a new series of hypotheses that can be tested to develop better understandings and therapies for this disease.

Immunology of multiple sclerosis

Multiple sclerosis (MS) develops in young adults with a complex predisposing genetic trait and probably requires an inciting environmental insult such as a viral infection to trigger the disease. The activation of CD4+ autoreactive T cells and their differentiation into a Th1 phenotype are a crucial events in the initial steps, and these cells are probably also important players in the long-term evolution of the disease. Damage of the target tissue, the central nervous system, is, however, most likely mediated by other components of the immune system, such as antibodies, complement, CD8+ T cells, and factors produced by innate immune cells. Perturbations in immunomodulatory networks that include Th2 cells, regulatory CD4+ T cells, NK cells, and others may in part be responsible for the relapsing-remitting or chronic progressive nature of the disease. However, an important paradigmatic shift in the study of MS has occurred in the past decade. It is now clear that MS is not just a disease of the immune system, but that factors contributed by the central nervous system are equally important and must be considered in the future.

Antigen-specific therapies for the treatment of multiple sclerosis: a clinical trial update

Within the past year a host of antigen-specific therapies for multiple sclerosis (MS) progressed along the path from IND submission to FDA approval. The Immune Response Corporation vaccinated patients with a Vbeta6 peptide, demonstrating that the vaccine was immunogenic, well tolerated, and reduced the number of Vbeta6+ T-cells in the cerebrospinal fluid (CSF). Connetics Corp. conducted a Phase I/II trial on chronic progressive MS patients vaccinated with CDR2 peptides from TCR Vbeta55.2 and found that patients with a measurable response to the vaccine remained clinically stable for a year. A study at the University of Alberta MS Patient Care and Research Clinic demonstrated that intrathecal injection of a B cell/T cell epitope of myelin basic protein (MBP) decreased the level of antiMBP antibody, but iv. administration did not decrease the relapse rate. AutoImmune Inc. completed a Phase III trial of oral myelin in the spring of 1997 which failed to show a statistical difference between those patients fed placebo and those fed daily capsules of myelin protein (Myoral). Three phase I trials of iv. myelin antigen(s) were initiated: MP4 (Alexion Pharmaceuticals, Inc.), a recombinant fusion of myelin basic protein and proteolipid protein; AG284 (Anergen, Inc.), a solubilised HLA-DR2:MBP peptide complex; and NBI-5788 (Neurocrine Biosciences, Inc.), an altered peptide ligand of an immunodominant MBP T-cell epitope. Following the conclusion of a successful Phase III clinical trial, TEVA Pharmaceutical Industries LTD received FDA approval to market Copaxone (glatiramer acetate) for the treatment of relapsing-remitting MS in December of 1996 and launched the product in 1997. The recent preclinical research and clinical trial status of these antigen-specific MS therapeutics are summarized in this review.

Autoantibodies against heterogeneous nuclear ribonucleoprotein B1 in CSF of MS patients

Heterogeneous nuclear ribonucleoproteins (hnRNPs) play an important role as the autoantigens in certain autoimmune disorders including neurological diseases such as HTLV-1-associated myelopathy/tropical spastic paraparesis and paraneoplastic neurological syndromes. To clarify their implication in multiple sclerosis (MS), we assayed antibodies (Abs) against hnRNP A and B proteins in sera and cerebrospinal fluid (CSF) of MS patients and compared the results with 25 patients with other neurological diseases (ONDs). Using recombinant hnRNP A1, A2, and B1 proteins and Western blotting for the assay, we found Abs against hnRNP B1 in CSF from 32 of 35 MS patients (91.4%) but not in any sera or CSF of the 25 OND patients. Most notably, no Abs against hnRNP B1 were found in sera of all 22 MS patients examined. Although Abs against hnRNP A1 and A2 were concomitantly found in CSF reacting with B1, their incidence and immunoreactivity were lower or weaker than those of anti-hnRNP B1 Abs. There was no correlation between the reactivity of CSF with hnRNP B1 and CSF parameters-such as the number of the cells and the IgG level-or clinical parameters-such as duration of illness and disease activity. The selective generation of Abs against hnRNP B1 in CSF was shown to be highly specific for MS, which makes them a disease marker.

Immunomodulation by the copolymer glatiramer acetate

Glatiramer acetate (GA; Copaxone, also known as Copolymer 1 or Cop-1), a copolymer of amino acids, is very effective in the suppression of experimental autoimmune encephalitis (EAE), the animal model for multiple sclerosis (MS), in various species including primates. The immunological cross-reaction between the myelin basic protein and GA serves as the basis for the suppressive activity of GA in EAE, by the induction of antigen-specific suppressor cells. The mode of action of GA is by initial strong promiscuous binding to major histocompatibility complex class II molecules and competition with MBP and other myelin proteins for such binding and presentation to T cells. Suppressor T cells induced by GA are of the Th2 type, migrate to the brain and lead to in situ bystander suppression. Clinical trials with GA, both phase II and phase III, were performed in relapsing-remitting MS (RRMS) patients, and demonstrated efficacy in reducing the relapse rate, decreasing MRI-assessed disease activity and burden and slowing progression of disability. GA is generally well tolerated and is not associated with influenza-like symptoms and formation of neutralizing antibodies seen with beta-interferons. It exerts its suppressive effect primarily by immunomodulation, and has recently shown ameliorating effect in a few additional autoimmune disorders as well as in graft rejection. At present GA is considered a valuable first-line treatment option for patients with RRMS.

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.

Antibodies to glatiramer acetate do not interfere with its biological functions and therapeutic efficacy

Glatiramer acetate (GA) previously known as Copolymer 1 (Cop 1), a synthetic amino acid copolymer, suppresses experimental autoimmune encephalomyelitis (EAE) and shows a beneficial effect in relapsing-remitting type of multiple sclerosis (MS). GA acts as a specific immunomodulator by binding to MHC Class II molecules, inducing specific T suppressor (Ts) cells and interfering with T cell responses to myelin antigens. MS patients treated with GA developed GA reactive antibodies, which peaked at three months and decreased at six months. In order to find out whether anti-GA antibodies may neutralize the therapeutic effect of GA, we tested both polyclonal (mouse and human) and monoclonal GA specific antibodies for their ability to interfere with the biological activity of GA in several assay systems. None of the antibodies interfered with GA activities either in vitro (binding to MHC molecules and T cell stimulation) or in vivo (blocking of EAE). Furthermore, 53 samples of sera obtained from 34 MS patients that participated in the open label trial in Israel, and all developed GA specific antibodies, were tested for their ability to inhibit the proliferation response of GA specific Ts cell clone and to interfere with GA competitive inhibition of the response to peptide 84-102 of myelin basic protein (MBP). None of the sera inhibited and some even enhanced the in vitro activities of GA. Furthermore, representative MS sera with high titer of GA reactive antibodies did not neutralize the biological activities of GA and did not inhibit Th2 cytokine secretion by human GA specific clone. These results are consistent with the findings that the therapeutic effect of GA is not affected by GA reactive antibodies and is sustained upon long term treatment.

B cells in multiple sclerosis

The most common laboratory abnormality in multiple sclerosis (MS) is an increased amount of cerebrospinal fluid IgG and the presence of oligoclonal bands. Despite studies of the humoral response that suggest the involvement of an infectious agent or autoantigen in disease, the major targets of the oligoclonal response are still unknown. Identification of these targets will reveal valuable insights into the cause and pathogenesis of MS and is likely to lead to effective treatment.

An immunodominant epitope of myelin basic protein is an amphipathic alpha-helix

Myelin basic protein is a candidate autoantigen in multiple sclerosis. One of its dominant antigenic epitopes is segment Pro85 to Pro96 (human sequence numbering, corresponding to Pro82 to Pro93 in the mouse). There have been several, contradictory predictions of secondary structure in this region; either beta-sheet, alpha-helix, random coil, or combinations thereof have all been proposed. In this paper, molecular dynamics and site-directed spin labeling in aqueous solution indicate that this segment forms a transient alpha-helix, which is stabilized in 30% trifluoroethanol. When bound to a myelin-like membrane surface, this antigenic segment exhibits a depth profile that is characteristic of an amphipathic alpha-helix, penetrating up to 12 A into the bilayer. The alpha-helix is tilted approximately 9 degrees, and the central lysine is in an ideal snorkeling position for side-chain interaction with the negatively charged phospholipid head groups.

Specificity of autoantibodies to epitopes of myelin proteins in multiple sclerosis

An autoimmune response to one or more myelin-protein components is thought to be part of the pathogenesis of multiple sclerosis (MS). The immunodominant-autoantibody epitope may be localized on a linear peptide segment, on a conformation-sensitive epitope, or on an epitope resulting from post-translational modifications. Primary, secondary, and tertiary structures of myelin proteins may determine the specific site for binding of autoantibodies. A myelin protein-specific autoantibody can bind to either a linear or conformational epitope, whereas all of the T cell epitopes are linear. At present, the conformational epitopes of myelin proteins have not been identified; most of the methods used to identify the myelin-protein epitopes corresponding to the pathogenesis of multiple sclerosis are involved in the linear epitope mapping. Polymorphism or mutations may cause inappropriate expression of the myelin proteins with alterations to their linear and/or conformational epitopes, and make them susceptible to autoantibody binding, especially if these changes occur at the surface of the protein. This review focuses on the specificity of autoantibodies to the epitopes of myelin proteins and correlates this to the structures of proteins. Factors that influence the expression of myelin-protein epitopes such as the alpha-helical or beta-sheet structure of the protein, the tri-proline site, and the post-translational modifications as well as physicochemical properties of amino acid changed are included.

Optic neuritis in multiple sclerosis

PURPOSE

To review the clinical features, natural history, potential pathogenic mechanisms, differential diagnosis, and management of optic neuritis in multiple sclerosis.

METHODS

Relevant literature regarding optic neuritis in multiple sclerosis from 1970 to the present was reviewed.

RESULTS

Optic neuritis is an acute inflammatory optic neuropathy. It is the most common type of optic neuropathy causing acute visual loss in young adults (peak age at 30-40 years), especially among women. Patients usually present with an acute reduction of visual acuity, orbital pain exacerbated by eye movements, dyschromatopsia, and an afferent papillary defect, with or without swelling of the optic nerve head. Visual field testing most often reveals central defects, but others, such as centrocecal, can also occur. Magnetic resonance image (MRI) scanning of the brain should be undertaken in all cases of acute optic neuritis for diagnostic and prognostic purposes. The brain lesions of multiple sclerosis are commonly seen as T2 ovoid high-signal white matter lesions on MRI scans of the brain located in perivenular regions perpendicular to ventricles with variable enhancement. For atypical presentations of optic neuritis, additional laboratory tests, such as cerebrospinal fluid analysis, serologic tests, and visual evoked potentials, prove to be useful in the diagnosis and subsequent management of the patient. The recommended treatment for optic neuritis is intravenous steroids, as shown in the Optic Neuritis Treatment Trial (ONTT).

CONCLUSION

Optic neuritis is often the initial presentation of multiple sclerosis. Recent advances in the understanding of the immune basis for multiple sclerosis has led to earlier and more effective treatment of this disease.

Virus-induced autoimmunity: potential role of viruses in initiation, perpetuation, and progression of T-cell-mediated autoimmune disease

Virus infections have been implicated in the initiation of multiple human autoimmune diseases. This article focuses on reviewing the role of viruses in initiation, progression, and perpetuation of autoimmune diseases. Various mechanisms by which virus infections can induce autoimmune responses including molecular mimicry, epitope spreading, direct bystander activation, and release of cryptic epitopes are discussed. Evidence implicating virus infections in the pathogenesis of various human autoimmune diseases is reviewed. Last, the characteristics of animal models that have been developed for the study of the potential role of viruses in the initiation and progression of autoimmune disease are reviewed.

Interferon beta-1b modulates MCP-1 expression and production in relapsing-remitting multiple sclerosis

Monocyte chemoattractant protein-1 (MCP-1) seems to be involved in the pathogenesis of multiple sclerosis (MS). We found that in unstimulated (PHA(-)) and PHA-stimulated (PHA(+)) peripheral blood mononuclear cells (PBMC), MCP-1 and TNFalpha levels are higher in stable untreated MS patients. Interferon gamma (IFNgamma) is higher in relapsing patients in PHA(-) cultures and in stable patients in PHA(+) cultures. Chronic IFNbeta-1b treatment down-regulates TNFalpha, IFNgamma and MCP-1 production except for TNFalpha in relapsing patients. IFNbeta-1b, in vitro, increases MCP-1, TNFalpha and IFNgamma spontaneous production in all patients. Multivariate analysis suggests that MCP-1 production is dependent from clinical status and not from TNFalpha and IFNgamma production. Logistic regression analysis shows that MCP-1 production is significantly modified by treatment. Further studies are needed to clarify the role of MCP-1 in MS.

No evidence to support CTLA-4 as a susceptibility gene in MS families: the Canadian Collaborative Study

Two polymorphisms of the CTLA-4 gene were genotyped in 232 sibling pairs affected with multiple sclerosis (MS) from 185 families. The CTLA-4 polymorphisms genotyped were a 3' untranslated (AT)(n) microsatellite and an alanine/threonine RFLP of exon 1. There was no evidence observed for linkage by either identity-by-descent (ibd) or identity-by-state (ibs) methods. A transmission disequilibrium test (TDT) was performed and no preferential transmission of alleles was observed. Upon stratification of patients, there was no preferential transmission observed based upon gender, by presence or absence of HLA*DRB1*15, by ethnicity or by clinical course of the disease. CTLA-4 does not appear to be a major MS susceptibility locus in Canadian multiplex families.

Antibody responses to Acinetobacter spp. and Pseudomonas aeruginosa in multiple sclerosis: prospects for diagnosis using the myelin-acinetobacter-neurofilament antibody index

Antibody responses to Acinetobacter (five strains), Pseudomonas aeruginosa, Escherichia coli, myelin basic protein (MBP), and neurofilaments were measured in sera from 26 multiple sclerosis (MS) patients, 20 patients with cerebrovascular accidents (CVA), 10 patients with viral encephalitis, and 25 healthy blood donors. In MS patients, elevated levels of antibodies against all strains of Acinetobacter tested were present, as well as antibodies against P. aeruginosa, MBP, and neurofilaments, but not antibodies to E. coli, compared to the CVA group and controls. The myelin-Acinetobacter-neurofilament antibody index appears to distinguish MS patients from patients with CVAs or healthy controls. The relevance of such antibodies to the neuropathology of MS requires further evaluation.

Serum autoantibody responses to myelin oligodendrocyte glycoprotein and myelin basic protein in X-linked adrenoleukodystrophy and multiple sclerosis

We analyzed the sera of 51 patients with various phenotypes of X-linked adrenoleukodystrophy (X-ALD), 20 patients with multiple sclerosis (MS) and 22 healthy volunteers for the presence of autoantibodies specific for the recombinant extracellular immunoglobulin-like domain of human myelin oligodendrocyte glycoprotein (rhMOG(Igd)) and myelin basic protein (MBP). Anti-rhMOG(Igd) autoantibodies were significantly more frequent in X-ALD and MS patients as opposed to healthy individuals (p<0.05). Anti-MBP autoantibodies were present in about one-fourth of X-ALD and MS patients but in less than 10% of healthy individuals. Anti-rhMOG(Igd) autoantibody responses were not accompanied by increased T cell reactivity against rhMOG(Igd). These findings may have important implications for the understanding of humoral anti-myelin immunoreactivity in demyelinating diseases of the central nervous system such as X-ALD and MS.

Novel monoclonal antibodies against proteolipid protein peptide 139-151 demonstrate demyelination and myelin uptake by macrophages in MS and marmoset EAE lesions

Experimental autoimmune encephalomyelitis (EAE) induced by immunization of mice with epitopes of the proteolipid protein (PLP), a major myelin constituent, forms a useful model for the study of multiple sclerosis (MS). In addition, MS patients display PLP-specific T- and B-cell responses, suggesting that PLP reactivity is relevant to pathogenesis.Here, the generation and characterization of a panel of mouse monoclonal antibodies (Mab) against PLP139-151, the prominent encephalitogenic sequence in SJL/J mice is described. Five Mab were generated by conventional immunization of an SJL/J mouse and hybridoma generation. These Mab reacted well with the PLP139-151 peptide in ELISA and belonged to the IgG2a and IgG2b subclasses, consistent with CD4+ T helper 1-cell-supported antibody formation. The Mab also efficiently detected PLP peptide-BSA conjugates in Western blot, confirming their multi-assay applicability. The Mab were subsequently used to determine the occurrence of demyelination in brains of MS patients and marmoset monkeys with EAE. Immunohistochemistry on both paraffin and frozen sections demonstrated a homogeneous expression of PLP139-151 in normal myelin, and a complete absence in lesions containing demyelinated areas, confirming that the Mab can be used as a general myelin marker. In active demyelinating MS lesions, the Mab visualized the peptide in the cytoplasm of macrophages containing phagocytosed myelin. In conclusion, this panel of Mab against the encephalitogenic PLP139-151 epitope forms a useful tool for further study of autoantigen expression, demyelination/remyelination and the staging of lesional activity in MS patients, as well as in EAE models in distinct animal species.

Genetic linkage analysis of the antibody responses to myelin basic protein and myelin oligodendrocyte glycoprotein in rats immunized with rat spinal cord homogenate

The genetic control of the antibody response to myelin basic protein (MBP) and myelin oligodendrocyte glycoprotein (MOG) was analysed in F1 and F2 crosses of DA and E3 rats, immunized with rat spinal chord homogenate. The DA rats were highly susceptible to encephalomyelitis and made antibody responses to both MBP and MOG, whereas the E3 rats were disease-resistant and responded only to MOG. The anti-MBP response was mainly controlled by the disease-promoting MHC region of the DA strain together with several disease loci outside MHC. In contrast, the anti-MOG response was associated with loci not related to or actually conferring resistance to disease.

Humoral and cellular immune responses to Copolymer 1 in multiple sclerosis patients treated with Copaxone

Humoral and cellular immune responses were followed in multiple sclerosis patients treated with Copolymer 1 (Cop1, glatiramer acetate, Copaxone) who participated in three different clinical trials. All patients (130) developed Cop1 reactive antibodies, which peaked at 3 months after initiation of treatment, decreasing at 6 months and remaining low. IgG1 antibody levels were 2-3-fold higher than those of IgG2. The proliferative response of Peripheral Blood Mononuclear Cells (PBMC) to Cop1 was initially high and gradually decreased during treatment. Antibodies and T cell responses to MBP were low and did not change significantly during the treatment. The humoral and cellular immunological responses to Cop1 do not correlate with the side effects and do not affect its therapeutic activity. The preferential production of IgG1 over IgG2 antibodies may indicate that Th2 responses are involved in mediating the clinical effect of Cop1.

The neuroimmunology of multiple sclerosis: possible roles of T and B lymphocytes in immunopathogenesis

Multiple sclerosis (MS) is an inflammatory disease of the central nervous system white matter. The association of the disease with MHC genes, the inflammatory white matter infiltrates, similarities with animal models, and the observation that MS can be treated with immunomodulatory and immunosuppressive therapies support the hypothesis that autoimmunity plays a major role in the disease pathology. Evidence supports activated CD4+ myelin-reactive T cells as major mediators of the disease. In addition, a renewed interest in the possible contribution of B cells to MS immunopathology has been sparked by nonhuman primate and MS pathological studies. This review focuses on the immunopathology of MS, outlining the hypothetical steps of tolerance breakdown and the molecules that play a role in the migration of autoreactive cells to the CNS. Particular focus is given to autoreactive T cells and cytokines as well as B cells and autoantibodies and their role in CNS pathogenesis in MS.

Kinetic profiles of cerebrospinal fluid anti-MBP in response to intravenous MBP synthetic peptide DENP(85)VVHFFKNIVTP(96)RT in multiple sclerosis patients

Multiple sclerosis [MS], a demyelinating disease of the central nervous system associated with inflammation and gliosis, may be an autoimmune disease with T lymphocytes and autoantibodies to myelin protein(s). This study deals exclusively with B cell autoimmunity to myelin basic protein (MBP). T lymphocytes and anti-MBP share a common MBP epitope located between P(85) and P(96) which contains the essential contact residues H(88)FFK(91) for the trimolecular complex. The purpose of this Phase I open label clinical study was to monitor CSF anti-MBP in patients with chronic progressive MS subsequent to IV administration of synthetic peptide (sp) MBP82-98 namely DEN(85)VVHFFKNIVTP(96)RT. Fifty-six patients who participated in this project were assigned to two groups: a 'control group' of 15 patients who received IV saline injections every 6 months for the first 2 years of the study and a 'peptide group' of 41 patients who received IV spMBP82-98 from the beginning of the study and then infrequently subsequent to a rise of their CSF anti-MBP. In the control group antibody levels remained persistently elevated during the 2 year period. Patients in the 'peptide group' segregated into four kinetic profiles: Cohort A (15 patients) illustrated prolonged anti-BMP suppression into the normal range. Cohort B (10 patients) illustrated significant anti-MBP suppression into the normal range for shorter durations. Cohort C (eight patients) showed significant CSF anti-MBP suppression after the initial injection but lost the ability to suppress the autoantibody titer following subsequent injections. Cohort D (eight patients) failed to show significant CSF anti-MBP suppression. In conclusion the B cell tolerizing effect of spMBP82-98 segregated into four kinetic profiles; this molecular variability should be considered in attempts to develop specific 'peptide therapies' for the broad range of clinical profiles currently diagnosed as 'multiple sclerosis'. Multiple Sclerosis (2000) 6 300 - 311

Intrathecal IgG synthesis and autoantibody-secreting cells in multiple sclerosis

We studied intrathecal IgG synthesis and autoantibody-secreting cells in 148 patients with possible onset symptoms of MS (POSMS) or clinically definite MS (CDMS). In POSMS intrathecal synthesis of IgG oligoclonal bands and abnormalities on T2-weighted magnetic resonance imaging were associated but the former were more prevalent. The cerebrospinal fluid (CSF) leukocyte count and the number of anti-protelipid protein antibody-secreting cells in cerebrospinal fluid (CSF) correlated with disease activity in POSMS. Intrathecal IgG synthesis levels and the number of anti-myelin basic protein antibody-secreting cells in CSF correlated with disease activity in CDMS. Our results support recent reports of pathogenetic heterogeneity and a pathogenetic role of the antibody response in MS.

B-cell responses to myelin basic protein and its epitopes in autoimmune encephalomyelitis induced by Semple rabies vaccine

Semple rabies vaccine is composed of rabies virus-infected sheep or goat brain inactivated with phenol and is administered daily after exposure for 14-21 days. Semple rabies vaccine-induced autoimmune encephalomyelitis (SAE) has clinico-pathological findings of demyelination similar to experimental autoimmune encephalomyelitis (EAE) caused by injection of central nervous system tissue or purified myelin proteins into experimental animals and frequently studied as a model for the human demyelinating disease, multiple sclerosis (MS). T-cell-mediated immune responses play a major role in induction of EAE, and antibody responses enhance disease severity. We studied the antibody responses to myelin basic protein (MBP) in 24 Thai patients with SAE and 77 control individuals to define the linear epitopes in human MBP that are encephalitogenic. Antibody levels were assessed by ELISA using native human MBP or synthetic MBP peptides of 20 amino acids. The major B-cell epitope was MBP61-80 and a minor epitope was MBP106-140 in SAE while in MS the major B-cell epitope is MBP84-96. MBP61-80-specific IgG1 and IgG3 levels were significantly higher in patients than controls while IgG2 and IgG4 were not. The data support the hypothesis that autoreactive Th1 cells induce SAE. The difference in B-cell epitope recognition may be due to differences in the genetic backgrounds of the populations studied or may reflect underlying differences in the pathogenesis of SAE and MS.

Demyelination in primate autoimmune encephalomyelitis and acute multiple sclerosis lesions: a case for antigen-specific antibody mediation

Neuropathological and ultrastructural features of central nervous system demyelination were compared in marmoset experimental autoimmune encephalomyelitis (EAE) induced with myelin/oligodendrocyte glycoprotein (MOG), and in 3 cases of multiple sclerosis (MS) displaying recent lesions. At the edges of EAE and MS lesions, a zone of myelin vacuolation was common, whereas in the lesion proper, myelin sheaths were consistently transformed into vesiculated membranous networks. These networks became dissociated from axons by cell processes from macrophages. Oligodendrocytes were remarkably spared and evidence of myelin repair was present but not prominent. Axonal pathology was more common in the MS material than in marmoset EAE. Immunocytochemistry, using gold-labeled encephalitogenic peptides of MOG and silver enhancement to detect MOG autoantibodies, revealed the presence of MOG-specific autoantibodies over vesiculated myelin networks. Gold-labeled antibody to IgG also gave a positive reaction. Gold-labeled peptide of myelin basic protein did not react with MOG/EAE tissue, but the same conjugate gave positive staining in MS (and in marmoset EAE induced by whole white matter), perhaps indicating broader spectrum immunoreactivity or sensitization to myelin antigens. Thus, vesicular disruption of myelin was a constant feature in these evolving, highly active lesions in primate EAE and MS and appeared causally related to the deposition of antigen-specific autoantibodies.

Candidate autoantigens in multiple sclerosis

Multiple sclerosis is an inflammatory demyelinating CNS disease of putatively autoimmune origin. Novel models of experimental autoimmune encephalomyelitis (EAE) have demonstrated that T cells specific for various myelin and even nonmyelin proteins are potentially encephalitogenic. The encephalitogenic T cell response directed against different CNS antigens not only determines the lesional topography of CNS inflammation but also the composition of the inflammatory infiltrates. The heterogeneity of the lesional distribution seen in EAE might therefore be useful for the understanding of the various clinical subtypes seen in MS. In this review the possible candidate autoantigens in MS are discussed with special regard to the human T cell and B cell responses against various myelin and nonmyelin proteins.

Effector pathways in immune mediated central nervous system demyelination

Multiple sclerosis is generally regarded to be a primarily T-cell driven disease. Recent evidence has refocused interest on antibodies. Adhesion molecules, matrix metalloproteinases, chemokines and cytokines, and nitric oxide and oxygen metabolites all participate in the amplification and effector stages of the disease.

Autoimmunity in multiple sclerosis: study of a wide spectrum of autoantibodies

The aim of this study was to assess the frequency of organ- and nonorgan-specific autoantibodies in MS patients and evaluate whether the presence of autoantibodies is an indicator of disease activity and/or a prognosis factor. One hundred and five definite MS patients in different stages and with different course and 75 blood donors were tested for the autoantibodies TgA, TMA/TPO-A, PCA, ANA, aCl, SMA, AMA and ANCA. All patients were screened for the LAC. Autoantibodies to at least one autoantigen were found in 66.6% MS patients and in 13.3% controls (P < 0.001). The frequency of TgA, TMA/TPO-A, ANA, aCl and SMA was statistically higher in patients than in controls. Circulating ANCAs were found in seven MS, a never reported finding. An early onset of MS (< 20 years) was associated with a lower autoantibody frequency (P < 0.01) Primary and secondary progressive MS had a higher antibody frequency than relapsing-remitting (P < 0.05) or benign (P < 0.001) MS. Up to 86% of patients were autoantibody-positive during the acute stage, but only 30% of them remained positive during the remission stage (P < 0.001). A generalised immune dysregulation occurs in MS patients, mostly during the acute stages and in the progressive courses, involving activation of both autoreactive Th1-cells (mainly linked to CNS lesions) and B-cells via Th2 cells.

IgG subclass switching is associated with the severity of experimental autoimmune encephalomyelitis induced with myelin oligodendrocyte glycoprotein peptide in NOD mice

We have recently shown that a single dose of the myelin oligodendrocyte glycoprotein (MOG) peptide 35-55 produces a relapsing-remitting demyelinating disease similar to multiple sclerosis (MS) in Lewis rats. In this study we have assessed the possibility that a subclass of anti-MOG35-55 antibodies influences the clinical outcome of these diseases by examining the classes and isotypes of anti-MOG35-55 antibody produced during the course of MOG35-55-induced demyelinating disease in NOD mice. Following immunization, 7 of the 21 injected mice had only mild diseases, while the 14 others had severe progressive and/or relapsing-remitting diseases. There were no differences in anti-MOG35-55 IgG, IgA, IgM, IgG1, IgG2a, and IgG3 antibody titers between the severe and mild symptoms groups. High levels of IgG2b antibody to MOG35-55 were detected in all mice with severe symptoms. In contrast, none of the mice which contracted a mild disease produced anti-MOG35-55 IgG2b. These results suggest that in NOD mice, the IgG2b antibody response to MOG35-55 is associated with the severity of this MS-like demyelinating disease.

Clonal expansion and somatic hypermutation of V(H) genes of B cells from cerebrospinal fluid in multiple sclerosis

The cerebrospinal fluid (CSF) of multiple sclerosis (MS) patients is characterized by increased concentrations of immunoglobulin (Ig), which on electrophoretic analysis shows restricted heterogeneity (oligoclonal bands). CSF Ig is composed of both serum and intrathecally produced components. To examine the properties of intrathecal antibody-producing B cells, we analyzed Ig heavy-chain variable (V(H)) region genes of B cells recovered from the CSF of 12 MS patients and 15 patients with other neurological diseases (OND). Using a PCR technique, we could detect rearrangements of Ig V(H) genes in all samples. Sequence analysis of complementarity-determining region 3 (CDR3) of rearranged VDJ genes revealed expansion of a dominant clone or clones in 10 of the 12 MS patients. B cell clonal expansion was identified in 3 of 15 OND. The nucleotide sequences of V(H) genes from clonally expanded CSF B cells in MS patients demonstrated the preferential usage of the V(H) IV family. There were numerous somatic mutations, mainly in the CDRs, with a high replacement-to-silent ratio; the mutations were distributed in a way suggesting that these B cells had been positively selected through their antigen receptor. Our results demonstrate that in MS CSF, there is a high frequency of clonally expanded B cells that have properties of postgerminal center memory or antibody-forming lymphocytes.

Antagonistic Action of IFN-β and IFN-γ on High Affinity Fcγ Receptor Expression in Healthy Controls and Multiple Sclerosis Patients

Monocyte-macrophage activation by IFN-γ is characterized by a pronounced increase of high affinity Fc receptors for IgG (FcγRI), capable of triggering respiratory burst, phagocytosis, Ab-dependent cytotoxicity, and release of proinflammatory cytokines. In view of the antagonism of IFN-β on IFN-γ action, of interest in the chronic inflammatory disorder multiple sclerosis, we examined the possible effect of IFN-β on IFN-γ induction of FcγRI gene expression. We found that IFN-β significantly down-regulated IFN-γ-induced FcγRI surface expression in peripheral blood monocytes from healthy donors, in a dose- and time-dependent manner. This down-regulation of FcγRI surface levels did not correspond to a decrease in FcγRI mRNA, suggesting a posttranscriptional effect of IFN-β. Down-regulation of FcγRI surface expression correlated with diminished cellular signaling through FcγRI, since the IFN-γ-induced increase in Fcγ receptor-triggered respiratory burst was nearly completely abrogated by simultaneous addition of IFN-β. Finally, the same antagonism between both IFNs on FcγRI surface expression was observed in peripheral blood monocytes derived from multiple sclerosis patients; inhibition by IFN-β was even increased (82 ± 11%), as compared with healthy controls (67 ± 4%). These results may partially help explain the beneficial effect of IFN-β in multiple sclerosis.

Linkage and association analysis of genes encoding cytokines and myelin proteins in multiple sclerosis

Several genetic factors are likely to play a role in the etiology of multiple sclerosis (MS). We used a candidate gene strategy in a study of polymorphic markers within or close to genes encoding cytokines (interferon-gamma (IFN-gamma), interleukin-2 (IL-2), IL-4, IL-4 receptor (IL-4R), IL-10, transforming growth factor-beta1 and -beta2) and myelin proteins (2',3'-cyclic-nucleotide 3'-phosphohydrolase (CNP:ase), myelin associated glycoprotein, oligodendrocyte myelin glycoprotein, proteolipid protein) in 34 Swedish multiplex MS families and in 147 sporadic MS patients and 95 healthy controls. No evidence for linkage was observed in two-point linkage analysis. However, a slightly positive LOD score of 0.88 (theta = 0.01) for IFN-gamma was found. Affected pedigree member (APM) analysis indicated a possible linkage with TGF-beta2 (p = 0.008) and IL-4R (p = 0.043). None of the cytokine markers were associated with MS in case-control analysis. Our results suggest a possible importance of the TGF-beta2, IL-4R and IFN-gamma genes in MS.

MBP, anti-MBP and anti-PLP antibodies, and intrathecal complement activation in multiple sclerosis

Intrathecal immunoglobulin synthesis and activation of the complement cascade occurs in patients with multiple sclerosis (MS). The present study aimed at further studying the relation between intrathecal immunoglobulin synthesis and complement activation. We compared total intrathecal synthesis of IgA, IgG, and IgM, the number of cells secreting anti-myelin basic protein (MBP) and anti-proteolipid protein (PLP) antibodies of the IgG isotype and intrathecal activation of the complement cascade in patients with possible onset symptoms of MS (n = 18) or clinically definite MS (n = 30). Early activation of the complement cascade correlated with intrathecal synthesis of IgM. Intrathecal IgG, IgA and IgM synthesis also correlated weakly with the presence of cells secreting anti-MBP or anti-PLP autoantibodies. Full activation of the complement cascade did not correlate with any measures of intrathecal antibody synthesis. These findings suggest a complex relation between different immunoglobulin isotypes and complement activation which may have similarly complex roles in the pathogenesis of MS.