T cells specific for the myelin oligodendrocyte glycoprotein mediate an unusual autoimmune inflammatory response in the central nervous system

Delimiting MOGAD as a disease entity using translational imaging

The first formal consensus diagnostic criteria for myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) were recently proposed. Yet, the distinction of MOGAD-defining characteristics from characteristics of its important differential diagnoses such as multiple sclerosis (MS) and aquaporin-4 antibody seropositive neuromyelitis optica spectrum disorder (NMOSD) is still obstructed. In preclinical research, MOG antibody-based animal models were used for decades to derive knowledge about MS. In clinical research, people with MOGAD have been combined into cohorts with other diagnoses. Thus, it remains unclear to which extent the generated knowledge is specifically applicable to MOGAD. Translational research can contribute to identifying MOGAD characteristic features by establishing imaging methods and outcome parameters on proven pathophysiological grounds. This article reviews suitable animal models for translational MOGAD research and the current state and prospect of translational imaging in MOGAD.

The Potential Pathogenicity of Myelin Oligodendrocyte Glycoprotein Antibodies in the Optic Pathway

BACKGROUND

Myelin oligodendrocyte glycoprotein (MOG) antibody-associated disease (MOGAD) is an acquired inflammatory demyelinating disease with optic neuritis (ON) as the most frequent clinical symptom. The hallmark of the disease is the presence of autoantibodies against MOG (MOG-IgG) in the serum of patients. Whereas the role of MOG in the experimental autoimmune encephalomyelitis animal model is well-established, the pathogenesis of the human disease and the role of human MOG-IgG is still not fully clear.

EVIDENCE ACQUISITION

PubMed was searched for the terms "MOGAD," "optic neuritis," "MOG antibodies," and "experimental autoimmune encephalomyelitis" alone or in combination, to find articles of interest for this review. Only articles written in English language were included and reference lists were searched for further relevant papers.

RESULTS

B and T cells play a role in the pathogenesis of human MOGAD. The distribution of lesions and their development toward the optic pathway is influenced by the genetic background in animal models. Moreover, MOGAD-associated ON is frequently bilateral and often relapsing with generally favorable visual outcome. Activated T-cell subsets create an inflammatory environment and B cells are necessary to produce autoantibodies directed against the MOG protein. Here, pathologic mechanisms of MOG-IgG are discussed, and histopathologic findings are presented.

CONCLUSIONS

MOGAD patients often present with ON and harbor antibodies against MOG. Furthermore, pathogenesis is most likely a synergy between encephalitogenic T and antibody producing B cells. However, to which extent MOG-IgG are pathogenic and the exact pathologic mechanism is still not well understood.

Oxygen treatment reduces neurological deficits and demyelination in two animal models of multiple sclerosis

AIMS

The objective of the study is to explore the importance of tissue hypoxia in causing neurological deficits and demyelination in the inflamed CNS, and the value of inspiratory oxygen treatment, using both active and passive experimental autoimmune encephalomyelitis (EAE).

METHODS

Normobaric oxygen treatment was administered to Dark Agouti rats with either active or passive EAE, compared with room air-treated, and naïve, controls.

RESULTS

Severe neurological deficits in active EAE were significantly improved after just 1 h of breathing approximately 95% oxygen. The improvement was greater and more persistent when oxygen was applied either prophylactically (from immunisation for 23 days), or therapeutically from the onset of neurological deficits for 24, 48, or 72 h. Therapeutic oxygen for 72 h significantly reduced demyelination and the integrated stress response in oligodendrocytes at the peak of disease, and protected from oligodendrocyte loss, without evidence of increased oxidative damage. T-cell infiltration and cytokine expression in the spinal cord remained similar to that in untreated animals. The severe neurological deficit of animals with passive EAE occurred in conjunction with spinal hypoxia and was significantly reduced by oxygen treatment initiated before their onset.

CONCLUSIONS

Severe neurological deficits in both active and passive EAE can be caused by hypoxia and reduced by oxygen treatment. Oxygen treatment also reduces demyelination in active EAE, despite the autoimmune origin of the disease.

Imperative role of glycosylation in human MOG-HLA interaction: molecular insights of MOG-Ab associated demyelination

Myelin oligodendrocyte glycoprotein is a transmembrane protein found on the outer lamella of the myelin sheath. The autoimmune attack on the MOG leads to demyelination which differs from normal multiple sclerosis. MOG has three epitope regions MOG_1-22, MOG_35-55, and MOG_92-106 in the extracellular region, and the crucial MOG_35-55 epitope and Human Leukocyte Antigen (HLA) interaction is the initial step for autoantibody generation. To study the effective role of glycosylation in MOG-HLA interaction, we performed molecular dynamics simulations of the complex where HLA interacts with three MOG epitopes both in the absence and presence of glycan. The results projected that the epitope MOG_1-22 is decisive for the HLA interaction in the absence of glycan and HLA interacts with the epitope MOG_35-55 irrespective of glycan existence. The residues Arg9, Arg46, and Arg66 were found to interact strongly with HLA even in the presence of glycan. The glycan increased the flexibility of hMOG and enhanced the interaction of MOG with water molecules.

Characterization of Asparagine Deamidation in Immunodominant Myelin Oligodendrocyte Glycoprotein Peptide Potential Immunotherapy for the Treatment of Multiple Sclerosis

Mannan (polysaccharide) conjugated with a myelin oligodendrocyte glycoprotein (MOG) peptide, namely (KG)5MOG35-55, represents a potent and promising new approach for the immunotherapy of Multiple Sclerosis (MS). The MOG35-55 epitope conjugated with the oxidized form of mannan (poly-mannose) via a (KG)5 linker was found to inhibit the symptoms of MOG35-55-induced experimental autoimmune encephalomyelitis (EAE) in mice using prophylactic and therapeutic vaccinated protocols. Deamidation is a common modification in peptide and protein sequences, especially for Gln and Asn residues. In this study, the structural solution motif of deaminated peptides and their functional effects in an animal model for MS were explored. Several peptides based on the MOG35-55 epitope have been synthesized in which the Asn53 was replaced with Ala, Asp, or isoAsp. Our results demonstrate that the synthesized MOG peptides were formed to the deaminated products in basic conditions, and the Asn53 was mainly modified to Asp. Moreover, both peptides (wild type and deaminated derivative) conjugated with mannan (from Saccharomyces cerevisiae) independently inhibited the development of neurological symptoms and inflammatory demyelinating spinal cord lesions in MOG35-55-induced EAE. To conclude, mannan conjugated with a deamidated product did not affect the efficacy of the parent peptide.

Astrocytes directly clear myelin debris through endocytosis pathways and followed by excessive gliosis after spinal cord injury

Persisted myelin debris inhibit axon regeneration and contribute to further tissue damage after spinal cord injury (SCI). The traditional view is that myelin debris is mainly cleared by microglia and macrophages, while astrocytes cannot directly engulf myelin debris because they are absent from lesion core. Here, we definitely showed that astrocytes could directly uptake myelin debris both in vitro and in vivo to effectively complement the clearance function. Therefore, it can be shown that astrocytes can exert myelin clearance effect directly and indirectly after spinal cord injury. The damaged myelin debris was transported to lysosomes for degradation through endocytosis pathways, finally resulting in excessive gliosis. This process may be a potential target for regulating neural tissue repair and excessive glia scar formation after SCI.

Myelin oligodendrocyte glycoprotein revisited-sensitive detection of MOG-specific T-cells in multiple sclerosis

Autoreactive CD4+ T-cells are believed to be a main driver of multiple sclerosis (MS). Myelin oligodendrocyte glycoprotein (MOG) is considered an autoantigen, yet doubted in recent years. The reason is in part due to low frequency and titers of MOG autoantibodies and the challenge to detect MOG-specific T-cells. In this study we aimed to analyze T-cell reactivity and frequency utilizing a novel method for detection of antigen-specific T-cells with bead-bound MOG as stimulant. Peripheral blood mononuclear cells (PBMCs) from natalizumab treated persons with MS (n = 52) and healthy controls (HCs) (n = 24) were analyzed by IFNγ/IL-22/IL-17A FluoroSpot. A higher number of IFNγ (P = 0.001), IL-22 (P = 0.003), IL-17A (P < 0.0001) as well as double and triple cytokine producing MOG-specific T-cells were detected in persons with MS compared to HCs. Of the patients, 46.2-59.6% displayed MOG-reactivity. Depletion of CD4+ T-cells or monocytes or blocking HLA-DR completely eliminated the MOG specific response. Anti-MOG antibodies did not correlate with T-cell MOG-responses. In conclusion, we present a sensitive method to detect circulating autoreactive CD4+ T-cells producing IFNγ, IL-22 or IL-17A using MOG as a model antigen. Further, we demonstrate that MOG-specific T-cells are present in approximately half of persons with MS.

The clinical spectrum of anti-MOG associated acquired demyelinating disorders: Three case-reports

BACKGROUND

The spectrum of differential diagnosis of acquired demyelinating disorders of the central nervous system has been recently broadened. There is now growing evidence that supports anti-myelin oligodendrocyte antibodies associated demyelination as a distinct disease entity, with some clinical characteristics that somehow overlap those of Multiple Sclerosis (MS) and anti-AQP4+ Neuromyelitis Optica Spectrum Disorders (AQP4+NMOSD) but different pathogenesis and treatment strategies.

SUMMARY

We hereby present 3 cases of anti-MOG+ patients with different disease courses - ranging from mild to severe - all presenting with Optic neuritis (ON) at the onset. Optic neuritis (ON) is a common manifestation of different central nervous system (CNS) inflammatory disorders and can represent the first clinical event of MS and NMOSD. ON is also the most common presentation of antiMOG demyelinating disorders, followed by - and sometimes associated with - myelitis, most commonly extended over more than 2 spinal cord segments and defined as longitudinally extended transverse myelitis (LETM). All the three patients tested negative for oligoclonal bands in CSF and anti-AQP4 Ab in serum, had a relapsing disease course characterized by prominent involvement of the optic nerve and spinal cord, with good recovery after treatment with high-dose corticosteroids. However, they had a different disease course at follow-up and underwent different treatment approaches.

CONCLUSIONS

Since anti-MOG+ patients can have a multiphasic disease course and accumulate disability over time, a high degree of suspicion and early diagnosis are of critical importance for treatment decision-making in clinical practice.

AIM

The aim of this case report is to enhance focus on an emerging disease spectrum among acquired CNS demyelinating disorders.

The Severity of Spinal Cord Injury Determines the Inflammatory Gene Expression Pattern after Immunization with Neural-Derived Peptides

Previous studies revealed that the intensity of spinal cord injury (SCI) plays a key role in the therapeutic effects induced by immunizing with neural-derived peptides (INDP), as severe injuries abolish the beneficial effects induced by INDP. In the present study, we analyzed the expression of some inflammation-related genes (IL6, IL12, IL-1β, IFNɣ, TNFα, IL-10, IL-4, and IGF-1) by quantitative PCR in rats subjected to SCI and INDP. We investigated the expression of these genes after a moderate or severe contusion. In addition, we evaluated the effect of INDP by utilizing two different peptides: A91 and Cop-1. After moderate injury, both A91 and Cop-1 elicited a pattern of genes characterized by a significant reduction of IL6, IL1β, and TNFα but an increase in IL10, IL4, and IGF-1 expression. There was no effect on IL-12 and INFɣ. In contrast, the opposite pattern was observed when rats were subjected to a severe spinal cord contusion. Immunization with either peptide caused a significant increase in the expression of IL-12, IL-1β, IFNɣ (pro-inflammatory genes), and IGF-1. There was no effect on IL-4 and IL-10 compared to controls. After a moderate SCI, INDP reduced pro-inflammatory gene expression and generated a microenvironment prone to neuroprotection. Nevertheless, severe injury elicits the expression of pro-inflammatory genes that could be aggravated by INDP. These findings correlate with our previous results demonstrating that severe injury inhibits the beneficial effects of protective autoimmunity.

Lewis Rat Model of Experimental Autoimmune Encephalomyelitis

In this unit, we describe in detail the most common methods used to break immunological tolerance for central myelin antigens and induce experimental autoimmune encephalomyelitis (EAE) in Lewis rats as an animal model of multiple sclerosis. The resulting disease course ranges from an acute monophasic disease to a chronic relapsing or chronic progressive course, which strongly resembles the human disease. These models enable the study of cellular and humoral autoimmunity against major antigenic epitopes of the myelin basic protein, myelin oligodendrocyte glycoprotein, or proteolipid protein. We provide an overview of common immunization protocols for induction of active and passive EAE, assessment and analysis of clinical score, preparation and purification of myelin basic protein, and derivation of neuroantigen-specific rat T cell lines. Finally, we describe the major clinical characteristics of these models. © 2017 by John Wiley & Sons, Inc.

Myelin Oligodendrocyte Glycoprotein: Deciphering a Target in Inflammatory Demyelinating Diseases

Myelin oligodendrocyte glycoprotein (MOG), a member of the immunoglobulin (Ig) superfamily, is a myelin protein solely expressed at the outermost surface of myelin sheaths and oligodendrocyte membranes. This makes MOG a potential target of cellular and humoral immune responses in inflammatory demyelinating diseases. Due to its late postnatal developmental expression, MOG is an important marker for oligodendrocyte maturation. Discovered about 30 years ago, it is one of the best-studied autoantigens for experimental autoimmune models for multiple sclerosis (MS). Human studies, however, have yielded controversial results on the role of MOG, especially MOG antibodies (Abs), as a biomarker in MS. But with improved detection methods using different expression systems to detect Abs in patients' samples, this is meanwhile no longer the case. Using cell-based assays with recombinant full-length, conformationally intact MOG, several recent studies have revealed that MOG Abs can be found in a subset of predominantly pediatric patients with acute disseminated encephalomyelitis (ADEM), aquaporin-4 (AQP4) seronegative neuromyelitis optica spectrum disorders (NMOSD), monophasic or recurrent isolated optic neuritis (ON), or transverse myelitis, in atypical MS and in N-methyl-d-aspartate receptor-encephalitis with overlapping demyelinating syndromes. Whereas MOG Abs are only transiently observed in monophasic diseases such as ADEM and their decline is associated with a favorable outcome, they are persistent in multiphasic ADEM, NMOSD, recurrent ON, or myelitis. Due to distinct clinical features within these diseases it is controversially disputed to classify MOG Ab-positive cases as a new disease entity. Neuropathologically, the presence of MOG Abs is characterized by MS-typical demyelination and oligodendrocyte pathology associated with Abs and complement. However, it remains unclear whether MOG Abs are a mere inflammatory bystander effect or truly pathogenetic. This article provides deeper insight into recent developments, the clinical relevance of MOG Abs and their role in the immunpathogenesis of inflammatory demyelinating disorders.

Myelin basic protein and myelin oligodendrocyte glycoprotein T-cell repertoire in childhood and juvenile multiple sclerosis

Multiple sclerosis (MS) is usually a disease of young adulthood, its clinical onset occurring between 20 and 40 years of age; however, today there is general consensus that MS can also occur in children, adolescents and even in infants. In order to gain further insight into the T-cell repertoire present in this particular group of patients myelin basic protein (MBP)-, MBP exon-2- and myelin oligodendrocyte glycoprotein (MOG)Igd-specific T-cell lines (TCLs) were isolated from 18 patients whose symptoms had started before the age of 16. Epitope specificity was established by measuring proliferative responses, and interferon-g (IFN-g) secretion by using a panel of overlapping synthetic peptides. For MOGIgd, the T-cell response was focused on three main immunodominant epitopes comprising residues 1-26, 36-60 and 63-87. For MBP the predominant immune responses were directed against peptides 83-102, 139-153 and 146-162. When compared to those observed in adult-onset MS patients, anti-MOGIgd specificity and anti-MBP responses showed similar results. Moreover, the number of MBP exon-2 TCLs isolated, and the magnitude of the specific IFN-g secretion induced were similar, both in childhood/juvenile-onset and adult-onset MS patients. Thus, despite differences in the clinical and neuroimaging manifestations of MS, these results would seem to indicate that both the spectrum of MBP found, as well as the MOGIgd epitopes recognized by peripheral blood T cells in MS, appear to be similar for childhood/juvenile-onset and adult-onset patients.

Use of the 2-chlorotrityl chloride resin for microwave-assisted solid phase peptide synthesis

A fast and efficient microwave (MW)-assisted solid-phase peptide synthesis protocol using the 2-chlorotrityl chloride resin and the Fmoc/tBu methodology, has been developed. The established protocol combines the advantages of MW irradiation and the acid labile 2-chlorotrityl chloride resin. The effect of temperature during the MW irradiation, the degree of resin substitution during the coupling of the first amino acids and the rate of racemization for each amino acid were evaluated. The suggested solid phase methodology is applicable for orthogonal peptide synthesis and for the synthesis of cyclic peptides.

Autoantibody-boosted T-cell reactivation in the target organ triggers manifestation of autoimmune CNS disease

Multiple sclerosis (MS) is caused by T cells that are reactive for brain antigens. In experimental autoimmune encephalomyelitis, the animal model for MS, myelin-reactive T cells initiate the autoimmune process when entering the nervous tissue and become reactivated upon local encounter of their cognate CNS antigen. Thereby, the strength of the T-cellular reactivation process within the CNS tissue is crucial for the manifestation and the severity of the clinical disease. Recently, B cells were found to participate in the pathogenesis of CNS autoimmunity, with several diverse underlying mechanisms being under discussion. We here report that B cells play an important role in promoting the initiation process of CNS autoimmunity. Myelin-specific antibodies produced by autoreactive B cells after activation in the periphery diffused into the CNS together with the first invading pathogenic T cells. The antibodies accumulated in resident antigen-presenting phagocytes and significantly enhanced the activation of the incoming effector T cells. The ensuing strong blood-brain barrier disruption and immune cell recruitment resulted in rapid manifestation of clinical disease. Therefore, myelin oligodendrocyte glycoprotein (MOG)-specific autoantibodies can initiate disease bouts by cooperating with the autoreactive T cells in helping them to recognize their autoantigen and become efficiently reactivated within the immune-deprived nervous tissue.

Blocking stroke-induced immunodeficiency increases CNS antigen-specific autoreactivity but does not worsen functional outcome after experimental stroke

Stroke-induced immunodepression (SIDS) is an essential cause of poststroke infections. Pharmacological inhibition of SIDS appears promising in preventing life-threatening infections in stroke patients. However, SIDS might represent an adaptive mechanism preventing autoreactive immune responses after stroke. To address this, we used myelin oligodendrocyte glycoprotein (MOG) T-cell receptor transgenic (2D2) mice where >80% of peripheral CD4(+) T cells express a functional receptor for MOG. We investigated in a murine model of middle cerebral artery occlusion the effect of blocking SIDS by inhibiting body's main stress axes, the sympathetic nervous system (SNS) with propranolol and the hypothalamic-pituitary-adrenal axis (HPA) with mifepristone. Blockade of both stress axes robustly reduced infarct volumes, decreased infection rate, and increased long-term survival of 2D2 and C57BL/6J wild-type mice. Despite these protective effects, blockade of SIDS increased CNS antigen-specific Type1 T helper cell (Th1) responses in the brains of 2D2 mice 14 d after middle cerebral artery occlusion. One month after experimental stroke, 2D2 mice developed signs of polyradiculitis, which were diminished by SIDS blockade. Adoptive transfer of CD4(+) T cells, isolated from 2D2 mice, into lymphocyte-deficient Rag-1KO mice did not reveal differences between SIDS blockade and vehicle treatment in functional long-term outcome after stroke. In conclusion, inhibiting SIDS by pharmacological blockade of body's stress axes increases autoreactive CNS antigen-specific T-cell responses in the brain but does not worsen functional long-term outcome after experimental stroke, even in a mouse model where CNS antigen-specific autoreactive T-cell responses are boosted.

Decreased Frequency of Circulating Myelin Oligodendrocyte Glycoprotein B Lymphocytes in Patients with Relapsing-Remitting Multiple Sclerosis

Although there is no evidence for a role of anti-MOG antibodies in adult MS, no information on B lymphocytes with MOG-committed BCR is available. We report here on the frequency of anti-MOG B cells forming rosettes with polystyrene beads (BBR) covalently bound to the extracellular domain of rhMOG in 38 relapsing-remitting patients (RRMS) and 50 healthy individuals (HI). We show a substantial proportion of circulating anti-MOG-BBR in both RRMS and HI. Strikingly, MOG-specific B cells frequencies were lower in MS than in HI. Anti-MOG antibodies measured by a cell-based assay were not different between MS patients and controls, suggesting a specific alteration of anti-MOG B cells in MS. Although anti-MOG-BBR were higher in CNS fluid than in blood, no difference was observed between MS and controls. Lower frequency of MOG-BBR in MS was not explained by an increased apoptosis, but a trend for lower proliferative capacity was noted. Despite an efficient B cell transmigration across brain derived endothelial cells, total and anti-MOG B cells transmigration was similar between MS and HI. The striking alteration in MOG-specific B cells, independent of anti-MOG antibody titers, challenges our view on the role of MOG-specific B cells in MS.

Combination of electroacupuncture and grafted mesenchymal stem cells overexpressing TrkC improves remyelination and function in demyelinated spinal cord of rats

This study attempted to graft neurotrophin-3 (NT-3) receptor (TrkC) gene modified mesenchymal stem cells (TrkC-MSCs) into the demyelinated spinal cord and to investigate whether electroacupuncture (EA) treatment could promote NT-3 secretion in the demyelinated spinal cord as well as further enhance grafted TrkC-MSCs to differentiate into oligodendrocytes, remyelination and functional recovery. Ethidium bromide (EB) was microinjected into the spinal cord of rats at T10 to establish a demyelinated model. Six groups of animals were prepared for the experiment: the sham, PBS, MSCs, MSCs+EA, TrkC-MSCs and TrkC-MSCs+EA groups. The results showed that TrkC-MSCs graft combined with EA treatment (TrkC-MSCs+EA group) significantly increased the number of OPCs and oligodendrocyte-like cells differentiated from MSCs. Immunoelectron microscopy showed that the oligodendrocyte-like cells differentiated from TrkC-MSCs formed myelin sheaths. Immunofluorescence histochemistry and Western blot analysis indicated that TrkC-MSCs+EA treatment could promote the myelin basic protein (MBP) expression and Kv1.2 arrangement trending towards the normal level. Furthermore, behavioural test and cortical motor evoked potentials detection demonstrated a significant functional recovery in the TrkC-MSCs+EA group. In conclusion, our results suggest that EA treatment can increase NT-3 expression, promote oligodendrocyte-like cell differentiation from TrkC-MSCs, remyelination and functional improvement of demyelinated spinal cord.

The Charcot Lecture | beating MS: a story of B cells, with twists and turns

Autoimmune B cells play a major role in mediating tissue damage in multiple sclerosis (MS). In MS, B cells are believed to cross the blood-brain barrier and undergo stimulation, antigen-driven affinity maturation and clonal expansion within the supportive CNS environment. These highly restricted populations of clonally expanded B cells and plasma cells can be detected in MS lesions, in cerebrospinal fluid, and also in peripheral blood. In phase II trials in relapsing MS, monoclonal antibodies that target circulating CD20-positive B lymphocytes dramatically reduced disease activity. These beneficial effects occurred within weeks of treatment, indicating that a direct effect on B cells--and likely not on putative autoantibodies--was responsible. The discovery that depletion of B cells has an impact on MS biology enabled a paradigm shift in understanding how the inflammatory phase of MS develops, and will hopefully lead to development of increasingly selective therapies against culprit B cells and related humoral immune system pathways. More broadly, these studies illustrate how lessons learned from the bedside have unique power to inform translational research. They highlight the essential role of clinician scientists, currently endangered, who navigate the rocky and often unpredictable terrain between the worlds of clinical medicine and biomedical research.

Modelling MS: Chronic-Relapsing EAE in the NOD/Lt Mouse Strain

Modelling complex disorders presents considerable challenges, and multiple sclerosis (MS) is no exception to this rule. The aetiology of MS is unknown, and its pathophysiology is poorly understood. Moreover, the last two decades have witnessed a dramatic revision of the long-held view of MS as an inflammatory demyelinating white matter disease. Instead, it is now regarded as a global central nervous system (CNS) disorder with a neurodegenerative component. Currently, there is no animal model recapitulating MS immunopathogenesis. Available models are based on autoimmune-mediated demyelination, denoted experimental autoimmune encephalomyelitis (EAE) or virally or chemically induced demyelination. Of these, the EAE model has been the most commonly used. It has been extensively improved since its first description and now exists as a number of variants, including genetically modified and humanized versions. Nonetheless, EAE is a distinct disease, and each variant models only certain facets of MS. Whilst the search for more refined MS models must continue, it is important to further explore where mechanisms underlying EAE provide proof-of-principle for those driving MS pathogenesis. EAE variants generated with the myelin component myelin oligodendrocyte glycoprotein (MOG) have emerged as the preferred ones, because in this particular variant disease is associated with both T- and B-cell effector mechanisms, together with demyelination. MOG-induced EAE in the non-obese diabetic (NOD) mouse strain exhibits a chronic-relapsing EAE clinical profile and high disease incidence. We describe the generation of this variant, its contribution to the understanding of MS immune and pathogenetic mechanisms and potential for evaluation of candidate therapies.

Rational design and synthesis of altered peptide ligands based on human myelin oligodendrocyte glycoprotein 35-55 epitope: inhibition of chronic experimental autoimmune encephalomyelitis in mice

Experimental autoimmune encephalomyelitis (EAE) is a demyelinating disease of the central nervous system and is an animal model of multiple sclerosis (MS). Although the etiology of MS remains unclear, there is evidence T-cell recognition of immunodominant epitopes of myelin proteins, such as the 35–55 epitope of myelin oligodendrocyte glycoprotein (MOG), plays a pathogenic role in the induction of chronic EAE. Cyclization of peptides is of great interest since the limited stability of linear peptides restricts their potential use as therapeutic agents. Herein, we have designed and synthesized a number of linear and cyclic peptides by mutating crucial T cell receptor (TCR) contact residues of the human MOG_35–55 epitope. In particular, we have designed and synthesized cyclic altered peptide ligands (APLs) by mutating Arg⁴¹ with Ala or Arg⁴¹ and Arg⁴⁶ with Ala. The peptides were synthesized in solid phase on 2-chlorotrityl chloride resin (CLTR-Cl) using the Fmoc/t-Bu methodology. The purity of final products was verified by RP-HPLC and their identification was achieved by ESI-MS. It was found that the substitutions of Arg at positions 41 and 46 with Ala results in peptide analogues that reduce the severity of MOG-induced EAE clinical symptoms in C57BL/6 mice when co-administered with mouse MOG_35–55 peptide at the time of immunization.

From classic to spontaneous and humanized models of multiple sclerosis: impact on understanding pathogenesis and drug development

Multiple sclerosis (MS), a demyelinating disease of the central nervous system (CNS), presents as a complex disease with variable clinical and pathological manifestations, involving different pathogenic pathways. Animal models, particularly experimental autoimmune encephalomyelitis (EAE), have been key to deciphering the pathophysiology of MS, although no single model can recapitulate the complexity and diversity of MS, or can, to date, integrate the diverse pathogenic pathways. Since the first EAE model was introduced decades ago, multiple classic (induced), spontaneous, and humanized EAE models have been developed, each recapitulating particular aspects of MS pathogenesis. The advances in technologies of genetic ablation and transgenesis in mice of C57BL/6J background and the development of myelin-oligodendrocyte glycoprotein (MOG)-induced EAE in C57BL/6J mice yielded several spontaneous and humanized EAE models, and resulted in a plethora of EAE models in which the role of specific genes or cell populations could be precisely interrogated, towards modeling specific pathways of MS pathogenesis/regulation in MS. Collectively, the numerous studies on the different EAE models contributed immensely to our basic understanding of cellular and molecular pathways in MS pathogenesis as well as to the development of therapeutic agents: several drugs available today as disease modifying treatments were developed from direct studies on EAE models, and many others were tested or validated in EAE. In this review, we discuss the contribution of major classic, spontaneous, and humanized EAE models to our understanding of MS pathophysiology and to insights leading to devising current and future therapies for this disease.

Immunodominant T-cell epitopes of MOG reside in its transmembrane and cytoplasmic domains in EAE

Objective:

Studies evaluating T-cell recognition of myelin oligodendrocyte glycoprotein (MOG) in multiple sclerosis (MS) and its model, experimental autoimmune encephalomyelitis (EAE), have focused mostly on its 117 amino acid (aa) extracellular domain, especially peptide (p) 35-55. We characterized T-cell responses to the entire 218 aa MOG sequence, including its transmembrane and cytoplasmic domains.

Methods:

T-cell recognition in mice was examined using overlapping peptides and intact full-length mouse MOG. EAE was evaluated by peptide immunization and by adoptive transfer of MOG epitope-specific T cells. Frequency of epitope-specific T cells was examined by ELISPOT.

Results:

Three T-cell determinants of MOG were discovered in its transmembrane and cytoplasmic domains, p119–132, p181–195, and p186–200. Transmembrane MOG p119-132 induced clinical EAE, CNS inflammation, and demyelination as potently as p35-55 in C57BL/6 mice and other H-2^b strains. p119-128 contained its minimal encephalitogenic epitope. p119-132 did not cause disease in EAE-susceptible non-H-2^b strains, including Biozzi, NOD, and PL/J. MOG p119-132–specific T cells produced Th1 and Th17 cytokines and transferred EAE to wild-type recipient mice. After immunization with full-length MOG, a significantly higher frequency of MOG-reactive T cells responded to p119-132 than to p35-55, demonstrating that p119-132 is an immunodominant encephalitogenic epitope. MOG p181-195 did not cause EAE, and MOG p181-195–specific T cells could not transfer EAE into wild-type or highly susceptible T- and B-cell–deficient mice.

Conclusions:

Transmembrane and cytoplasmic domains of MOG contain immunodominant T-cell epitopes in EAE. A CNS autoantigen can also contain nonpathogenic stimulatory T-cell epitopes. Recognition that a myelin antigen contains multiple encephalitogenic and nonencephalitogenic determinants may have implications for therapeutic development in MS.

Novel pathogenic epitopes of myelin oligodendrocyte glycoprotein induce experimental autoimmune encephalomyelitis in C57BL/6 mice

Myelin oligodendrocyte glycoprotein (MOG), a minor protein of the central nervous system myelin, is recognized as a potential target in multiple sclerosis and neuromyelitis optica. The extracellular domain of MOG is commonly used in a wide range of mouse strains and other animals to induce experimental autoimmune encephalomyelitis (EAE), an autoimmune animal model of multiple sclerosis, because it is a target for antibody-mediated attack. Previous studies, using selected peptides, have indicated that MOG(35-55) peptide is an encephalitogenic epitope in C57BL/6 (H-2(b)) mice. A more systematic analysis of both T-cell and B-cell responses following immunization of C57BL/6 mice with either recombinant extracellular mouse MOG protein (1-116) or with overlapping peptides spanning the whole sequence of MOG, before assessment of responses to 15 mer and 23 mer peptides was undertaken. The studies identified T-cell responses within the MOG(35-55) (extracellular domain) but also two new immunogenic and encephalitogenic T-cell epitopes within residues MOG(113-127), MOG(120-134) (localized in the transmembrane region) and MOG(183-197) (in the second hydrophobic MOG domain). In addition, residue MOG(113-127) was found to be a B-cell epitope, suggesting that this may be a useful adjunct for the induction of EAE as well as for immunological studies in C57BL/6 mice, which are increasingly being used to study immune function through the use of transgenic and gene knockout technology.

Early loss of oligodendrocytes in human and experimental neuromyelitis optica lesions

Neuromyelitis optica (NMO) is a chronic, mostly relapsing inflammatory demyelinating disease of the CNS characterized by serum anti-aquaporin 4 (AQP4) antibodies in the majority of patients. Anti-AQP4 antibodies derived from NMO patients target and deplete astrocytes in experimental models when co-injected with complement. However, the time course and mechanisms of oligodendrocyte loss and demyelination and the fate of oligodendrocyte precursor cells (OPC) have not been examined in detail. Also, no studies regarding astrocyte repopulation of experimental NMO lesions have been reported. We utilized two rat models using either systemic transfer or focal intracerebral injection of recombinant human anti-AQP4 antibodies to generate NMO-like lesions. Time-course experiments were performed to examine oligodendroglial and astroglial damage and repair. In addition, oligodendrocyte pathology was studied in early human NMO lesions. Apart from early complement-mediated astrocyte destruction, we observed a prominent, very early loss of oligodendrocytes and oligodendrocyte precursor cells (OPCs) as well as a delayed loss of myelin. Astrocyte repopulation of focal NMO lesions was already substantial after 1 week. Olig2-positive OPCs reappeared before NogoA-positive, mature oligodendrocytes. Thus, using two experimental models that closely mimic the human disease, our study demonstrates that oligodendrocyte and OPC loss is an extremely early feature in the formation of human and experimental NMO lesions and leads to subsequent, delayed demyelination, highlighting an important difference in the pathogenesis of MS and NMO.

Apoptosis of oligodendrocytes in the central nervous system results in rapid focal demyelination

OBJECTIVE

Multiple sclerosis (MS) is a demyelinating disease of the central nervous system that presents with variable pathologies that may reflect different disease-causing mechanisms. Existing animal models of MS induce pathology using either local injection of gliotoxins or stimulation of the immune system with myelin-related peptides. In none of these models is the primary cellular target well characterized, and although demyelination is a hallmark pathological feature in MS, it is unclear to what extent this reflects local oligodendrocyte loss. To unambiguously identify the effects of oligodendrocyte death in the absence of inflammatory stimulation, we developed a method for experimentally inducing programmed cell death selectively in mature oligodendrocytes and assessed the effects on demyelination, immunological stimulation, and gliosis. The resulting pathology is discussed relative to observed MS pathologies.

METHODS

Oligodendrocyte apoptosis was induced in the adult rat brain using a lentivirus to express experimentally inducible caspase 9 (iCP9) cDNA under transcriptional control of the promoter for myelin basic protein, which is oligodendrocyte-specific. Activation of iCP9 was achieved by distal injection of a small molecule dimerizer into the lateral ventricle resulting in localized, acute oligodendrocyte apoptosis.

RESULTS

Induced oligodendrocyte apoptosis resulted in rapid demyelination and robust, localized microglial activation in the absence of peripheral immune cell infiltration. Lesion borders showed layers of preserved and degraded myelin, whereas lesion cores were demyelinated but only partially cleared of myelin debris. This resulted in local proliferation and mobilization of the oligodendrocyte progenitor pool.

INTERPRETATION

This approach provides a novel model to understand the pathological changes that follow from localized apoptosis of myelinating oligodendrocytes. It provides the first direct proof that initiation of apoptosis in oligodendrocytes is sufficient to cause rapid demyelination, gliosis, and a microglial response that result in lesions sharing some pathological characteristics with a subset of MS lesions.

Designed glucopeptides mimetics of myelin protein epitopes as synthetic probes for the detection of autoantibodies, biomarkers of multiple sclerosis

We previously reported that CSF114(Glc) detects diagnostic autoantibodies in multiple sclerosis sera. We report herein a bioinformatic analysis of myelin proteins and CSF114(Glc), which led to the identification of five sequences. These glucopeptides were synthesized and tested in enzymatic assays, showing a common minimal epitope. Starting from that, we designed an optimized sequence, SP077, showing a higher homology with both CSF114(Glc) and the five sequences selected using the bioinformatic approach. SP077 was synthesized and tested on 50 multiple sclerosis patients' sera, and was able to detect higher antibody titers as compared to CSF114(Glc). Finally, the conformational properties of SP077 were studied by NMR spectroscopy and structure calculations. Thus, the immunological activity of SP077 in the recognition of specific autoantibodies in multiple sclerosis patients' sera may be ascribed to both the optimized design of its epitopic region and the superior surface interacting properties of its C-terminal region.

Bystander-mediated stimulation of proteolipid protein-specific regulatory T (Treg) cells confers protection against experimental autoimmune encephalomyelitis (EAE) via TGF-β

To assess the potency of regulatory T (Treg) cells induced against an irrelevant Ag, mice were orally vaccinated with Salmonella expressing Escherichia coli colonization factor antigen I fimbriae. Isolated CD25⁺ and CD25⁻CD4⁺ T cells were adoptively transferred to naive mice, and Treg cells effectively protected against experimental autoimmune encephalomyelitis (EAE), unlike Treg cells from Salmonella vector-immunized mice. This protection was abrogated upon in vivo neutralization of TGF-β, resulting in elevated IL-17 and loss of IL-4 and IL-10 production. Thus, Treg cells induced to irrelevant Ags offer a novel approach to treat autoimmune diseases independent of auto-Ag.

Increased frequencies of myelin oligodendrocyte glycoprotein/MHC class II-binding CD4 cells in patients with multiple sclerosis

Multiple sclerosis (MS) is an autoimmune disease characterized by infiltration of pathogenic immune cells in the CNS resulting in destruction of the myelin sheath and surrounding axons. We and others have previously measured the frequency of human myelin-reactive T cells in peripheral blood. Using T cell cloning techniques, a modest increase in the frequency of myelin-reactive T cells in patients as compared with control subjects was observed. In this study, we investigated whether myelin oligodendrocyte glycoprotein (MOG)-specific T cells could be detected and their frequency was measured using DRB1*0401/MOG(97-109(107E-S)) tetramers in MS subjects and healthy controls expressing HLA class II DRB1*0401. We defined the optimal culture conditions for expansion of MOG-reactive T cells upon MOG peptide stimulation of PMBCs. MOG(97-109)-reactive CD4(+) T cells, isolated with DRB1*0401/MOG(97-109) tetramers, and after a short-term culture of PMBCs with MOG(97-109) peptides, were detected more frequently from patients with MS as compared with healthy controls. T cell clones from single cell cloning of DRB1*0401/MOG(97-109(107E-S)) tetramer(+) cells confirmed that these T cell clones were responsive to both the native and the substituted MOG peptide. These data indicate that autoantigen-specific T cells can be detected and enumerated from the blood of subjects using class II tetramers, and the frequency of MOG(97-109)-reactive T cells is greater in patients with MS as compared with healthy controls.

An experimental electro-acupuncture study in treatment of the rat demyelinated spinal cord injury induced by ethidium bromide

Oligodendrocyte precursor cells (OPCs) are one of the potential treating tools for multiple sclerosis (MS). Therefore, the cell number and differentiation of OPCs in a demyelinated spinal cord are crucial for improvement of reparative process. In the present study, we investigated whether "Governor Vessel (GV)" electro-acupuncture (EA) could efficiently promote increase in cell number and differentiation of OPCs into oligodendrocytes, remyelination and functional recovery in the demyelinated spinal cord. The spinal cord of adult Sprague-Dawley rats was microinjected with ethidium bromide (EB) at T10, to establish a demyelinated model. Six groups of animals were performed for the experiment. After 15 days EA treatment, neurotrophin-3 (NT-3) level and number of NG2-positive OPCs were significantly increased. Compared with the sham group, more NG2-positive OPCs were distributed between neurofilament (NF)-positive nerve fibres or closely associated with them in the lesion site and nearby tissue. In rats given longer EA treatment for 30 days, the number of adenomatous polyposis coli (APC)-positive oligodendrocytes was increased. Concomitantly, the number of newly formed myelins was increased. This was coupled by increase in endogenous oligodendrocyte involved in myelin formation. Furthermore, behavioural test and spinal cord evoked potential detection demonstrated a significant functional recovery in the EA+EB day 30 group. Our results suggest EA treatment can promote NT-3 expression, increase the cell number and differentiation of endogenous OPCs, and remyelination in the demyelinated spinal cord as well as the functional improvement of demyelinated spinal cord.

Treatment of experimental autoimmune encephalomyelitis in SJL/J mice with a replicative HSV-1 vector expressing interleukin-5

Experimental autoimmune encephalomyelitis (EAE) is an autoimmune inflammation of the central nervous system and is used as the experimental model of multiple sclerosis (MS). The exact mechanism behind the disease is still unknown, but interleukin (IL)-17 expressing T cells are thought to mediate the disease. Toll-like receptors (TLRs) are known to have a role in the innate immune response against pathogens, and several TLRs have also a role in the disease course of EAE. Here, we show that treatment with a herpes simplex virus type 1 vector expressing the Th2 cytokine IL-5 ameliorates EAE and decreases the numbers of infiltrating lymphocytes in the brain. The effect involves downregulation of TLR 2, 3 and 9 mRNA expression and upregulation of type I interferons (IFNs) in brains during onset of disease. The elevated expression of type I IFNs was also observed during recovery.

Antigen processing and presentation in multiple sclerosis

CD4(+) T cells play a central role in the pathogenesis of multiple sclerosis (MS). Generation, activation and effector function of these cells crucially depends on their interaction with MHC II-peptide complexes displayed by antigen presenting cells (APC). Processing and presentation of self antigens by different APC therefore influences the disease course at all stages. Selection by thymic APC leads to the generation of autoreactive T cells, which can be activated by peripheral APC. Reactivation by central nervous system APC leads to the initiation of the inflammatory response resulting in demyelination. In this review we will focus on how MHC class II antigenic epitopes are created by different APC from the thymus, the periphery and from the brain, and will discuss the relevance of the balance between creation and destruction of such epitopes in the context of MS. A solid understanding of these processes offers the possibility for designing future therapeutic strategies.

Prostaglandins in pathogenesis and treatment of multiple sclerosis

Multiple sclerosis (MS) is a chronic inflammatory demyelinating disease of the central nervous system (CNS) characterized by inflammation, demyelination, axonal loss, and gliosis. The inflammatory lesions are manifested by a large infiltration and a heterogeneous population of cellular and soluble mediators of the immune system, such as T cells, B cells, macrophages, and microglia, as well as a broad range of cytokines, chemokines, antibodies, complement, and other toxic substances. Prostaglandins (PGs) are arachidonic acid-derived autacoids that have a role in the modulation of many physiological systems including the CNS, respiratory, cardiovascular, gastrointestinal, genitourinary, endocrine, and immune systems. PG production is associated with inflammation, a major feature in MS that is characterized by the loss of myelinating oligodendrocytes in the CNS. With respect to the role of PGs in the induction of inflammation, they can be effective mediators in the pathophysiology of MS. Thus use of agonists or antagonists of PG receptors may be considered as a new therapeutic protocol in MS. In this review, we try to clarify the role of PGs in immunopathology and treatment of MS.

Delineating the impact of neuroantigen vs genetic diversity on MP4-induced EAE of C57BL/6 and B6.129 mice

MBP-PLP fusion protein (MP4)-induced experimental autoimmune encephalomyelitis (EAE) is a model for multiple sclerosis (MS) that encompasses both a time-dependent attack on central nervous system (CNS) regions and a B cell component, mirroring important features of human multiple sclerosis. Comparing C57BL/6 with B6.129 mice immunized with MP4, we point out similarities regarding these hallmarks and thus propose that they are largely dependent on the nature of the MP4 antigen itself, while differences between the two strains suggest that additional fine-tuning is brought about by the genetic repertoire of the animal. Overall, our data imply that (i) the interplay between both the antigenic trigger and genetic variables can define the outcome of MP4-induced autoimmune encephalomyelitis in C57BL/6 and B6.129 mice and (ii) that MP4 is not only a strong neuroantigen when it comes to reproducing the dynamics in effector mechanisms as is typical of the disease but also a promising agent for studying interindividual heterogeneity derived from genetic diversity in EAE/MS.

The PEPvIII-KLH (CDX-110) vaccine in glioblastoma multiforme patients

Conventional therapies for glioblastoma multiforme (GBM) fail to target tumor cells exclusively, resulting in non-specific toxicity. Immune targeting of tumor-specific mutations may allow for more precise eradication of neoplastic cells. EGFR variant III (EGFRvIII) is a tumor-specific mutation that is widely expressed in GBM and other neoplasms and its expression enhances tumorigenicity. This in-frame deletion mutation splits a codon, resulting in a novel glycine at the fusion junction producing a tumor-specific epitope target for cellular or humoral immunotherapy. We have previously shown that vaccination with a peptide that spans the EGFRvIII fusion junction (PEPvIII-KLH/CDX-110) is an efficacious immunotherapy in syngeneic murine models. In this review, we summarize our results in GBM patients targeting this mutation in multiple, multi-institutional Phase II immunotherapy trials. These trials demonstrated that a selected population of GBM patients who received vaccines targeting EGFRvIII had an unexpectedly long survival time. Further therapeutic strategies and potential pitfalls of using this approach are discussed.

Antioxidant therapy in multiple sclerosis

Reactive oxygen species (ROS) play an important role in various events underlying multiple sclerosis pathology. In the initial phase of lesion formation, ROS are known to mediate the transendothelial migration of monocytes and induce a dysfunction in the blood-brain barrier. Although the pathogenesis of MS is not completely understood, various studies suggest that reactive oxygen species contribute to the formation and persistence of multiple sclerosis lesions by acting on distinct pathological processes. The detrimental effects of ROS in the central nervous system are endowed with a protective mechanism consisting of enzymatic and non-enzymatic antioxidant. Antioxidant therapy may therefore represent an attractive treatment of MS. Several studies have shown that antioxidant therapy is beneficial in vitro and in vivo in animal models for MS. Since oxidative damage has been known to be involved in inflammatory and autoimmune-mediated tissue destruction in which, modulation of oxygen free radical production represents a new approach to the treatment of inflammatory and autoimmune diseases. Several experimental studies have been performed to see whether dietary intake of several antioxidants can prevent and or reduce the progression of EAE or not. Although a few antioxidants showed some efficacy in these studies, little information is available on the effect of treatments with such compounds in patients with MS. In this review, our aim is to clarify the therapeutic efficacy of antioxidants in MS disease.

Contactin-2/TAG-1-directed autoimmunity is identified in multiple sclerosis patients and mediates gray matter pathology in animals

Gray matter pathology is increasingly recognized as an important feature of multiple sclerosis (MS), but the nature of the immune response that targets the gray matter is poorly understood. Starting with a proteomics approach, we identified contactin-2/transiently expressed axonal glycoprotein 1 (TAG-1) as a candidate autoantigen recognized by both autoantibodies and T helper (Th) 1/Th17 T cells in MS patients. Contactin-2 and its rat homologue, TAG-1, are expressed by various neuronal populations and sequestered in the juxtaparanodal domain of myelinated axons both at the axonal and myelin sides. The pathogenic significance of these autoimmune responses was then explored in experimental autoimmune encephalitis models in the rat. Adoptive transfer of TAG-1-specific T cells induced encephalitis characterized by a preferential inflammation of gray matter of the spinal cord and cortex. Cotransfer of TAG-1-specific T cells with a myelin oligodendrocyte glycoprotein-specific mAb generated focal perivascular demyelinating lesions in the cortex and extensive demyelination in spinal cord gray and white matter. This study identifies contactin-2 as an autoantigen targeted by T cells and autoantibodies in MS. Our findings suggest that a contactin-2-specific T-cell response contributes to the development of gray matter pathology.

Experimental autoimmune encephalomyelitis in the rat

There are several diverse rat models of experimental autoimmune encephalomyelitis (EAE) that can be used to investigate the pathogenesis and regulation of autoimmunity against CNS myelin. The disease course of these models ranges from an acute monophasic disease with limited demyelination to a chronic relapsing or chronic progressive course marked by severe demyelination. These models enable the study of encephalitogenic T cells and demyelinating antibody specific for major neuroantigens such as myelin basic protein (MBP), myelin oligodendrocyte glycoprotein (MOG), or proteolipid protein (PLP), among other important CNS autoantigens. Overall, this unit provides an overview of common methods for induction of active and passive EAE, assessment and analysis of clinical disease, preparation and purification of myelin basic protein, and derivation of neuroantigen-specific rat T cell lines. This unit also provides a brief discussion of the basic characteristics of these models.

Animal models of multiple sclerosis

Since its first description, experimental autoimmune encephalomyelitis, originally designated experimental allergic encephalitis (EAE), has been proposed as animal model to investigate pathogenetic hypotheses and test new treatments in the field of central nervous system inflammation and demyelination, which has become, in the last 30 years, the most popular animal model of multiple sclerosis (MS). This experimental disease can be obtained in all mammals tested so far, including nonhuman primates, allowing very advanced preclinical studies. Its appropriate use has led to the development of the most recent treatments approved for MS, also demonstrating its predictive value when properly handled. Some of the most exciting experiments validating the use of neural precursor cells (NPCs) as a potential therapeutic option in CNS inflammation have been performed in this model. We review here the most relevant immunological features of EAE in the different animal species and strains, and describe detailed protocols to obtain the three most common clinical courses of EAE in mice, with the hope to provide both cultural and practical basis for the use of this fascinating animal model.

Hippocampal gene expression changes during age-related cognitive decline

As humans age, cognitive performance decreases differentially across individuals. This age-related decline in otherwise healthy individuals is likely due to the interaction of multiple factors including genetics and environment. We hypothesized that altered spatial memory performance in genetically similar mice could be in part due to differential gene expression patterns in the hippocampus. To investigate this we utilized Morris water maze (MWM) testing in a group of young (3 months) and aged (24 months) C57BL/J male mice. Two sub-groups were identified in the aged animals; one in which MWM performance was not significantly different when compared to the young animals (aged-unimpaired; "AU") and one in which performance was significantly different by 1.5 standard deviations from the mean (aged-impaired; "AI"). One week after testing was completed the entire hippocampus was collected from six each of AU, AI and young mice and their gene expression profiles were compared using Affymetrix microarrays. Benjamini and Hochberg FDR correction at p<0.05 identified 18 genes differentially expressed between the AI and AU mice. The correlation between behavioral deficits and gene expression patterning allows a better understanding of how altered gene expression in the hippocampus contributes to accelerated age-related cognitive decline and delineates between gene expression changes associated with normal aging vs. memory performance.

Tumor-specific immunotherapy targeting the EGFRvIII mutation in patients with malignant glioma

Conventional therapies for malignant gliomas (MGs) fail to target tumor cells exclusively, such that their efficacy is ultimately limited by non-specific toxicity. Immunologic targeting of tumor-specific gene mutations, however, may allow more precise eradication of neoplastic cells. The epidermal growth factor receptor variant III (EGFRvIII) is a consistent tumor-specific mutation that is widely expressed in MGs and other neoplasms. This mutation encodes a constitutively active tyrosine kinase that enhances tumorgenicity and migration and confers radiation and chemotherapeutic resistance. This in-frame deletion mutation splits a codon resulting in the creation of a novel glycine at the fusion junction between normally distant parts of the molecule and producing a sequence re-arrangement which creates a tumor-specific epitope for cellular or humoral immunotherapy in patients with MGs. We have previously shown that vaccination with a peptide that spans the EGFRvIII fusion junction is an efficacious immunotherapy in syngeneic murine models, but patients with MGs have a profound immunosuppression that may inhibit the ability of antigen presenting cells (APCs), even those generated ex vivo, to induce EGFRvIII-specific immune responses. In this report, we summarize our results in humans targeting this mutation in two consecutive and one multi-institutional Phase II immunotherapy trials. These trials demonstrated that vaccines targeting EGFRvIII are capable of inducing potent T- and B-cell immunity in these patients, and lead to an unexpectedly long survival time. Most importantly, vaccines targeting EGFRvIII were universally successful at eliminating tumor cells expressing the targeted antigen without any evidence of symptomatic collateral toxicity. These studies establish the tumor-specific EGFRvIII mutation as a novel target for humoral- and cell-mediated immunotherapy in a variety of cancers. The recurrence of EGFRvIII-negative tumors in our patients, however, highlights the need for targeting a broader repertoire of tumor-specific antigens.

IFN-gamma and IL-17 production in experimental autoimmune encephalomyelitis depends on local APC-T cell complement production

IFN-gamma- and IL-17-producing T cells autoreactive across myelin components are central to the pathogenesis of multiple sclerosis. Using direct in vivo, adoptive transfer, and in vitro systems, we show in this study that the generation of these effectors in myelin oligodendrocyte glycoprotein(35-55)-induced experimental autoimmune encephalomyelitis depends on interactions of locally produced C3a/C5a with APC and T cell C3aR/C5aR. In the absence of the cell surface C3/C5 convertase inhibitor decay-accelerating factor (DAF), but not the combined absence of DAF and C5aR and/or C3aR on APC and T cells, a heightened local autoimmune response occurs in which myelin destruction is markedly augmented in concert with markedly more IFN-gamma(+) and IL-17(+) T cell generation. The augmented T cell response is due to increased IL-12 and IL-23 elaboration by APCs together with increased T cell expression of the receptors for each cytokine. The results apply to initial generation of the IL-17 phenotype because naive CD62L(high) Daf1(-/-) T cells produce 3-fold more IL-17 in response to TGF-beta and IL-6, whereas CD62L(high) Daf1(-/-)C5aR(-/-)C3aR(-/-) T cells produce 4-fold less.

Immunotherapy of malignant brain tumors

Despite aggressive multi-modality therapy including surgery, radiation, and chemotherapy, the prognosis for patients with malignant primary brain tumors remains very poor. Moreover, the non-specific nature of conventional therapy for brain tumors often results in incapacitating damage to surrounding normal brain and systemic tissues. Thus, there is an urgent need for the development of therapeutic strategies that precisely target tumor cells while minimizing collateral damage to neighboring eloquent cerebral cortex. The rationale for using the immune system to target brain tumors is based on the premise that the inherent specificity of immunologic reactivity could meet the clear need for more specific and precise therapy. The success of this modality is dependent on our ability to understand the mechanisms of immune regulation within the central nervous system (CNS), as well as counter the broad defects in host cell-mediated immunity that malignant gliomas are known to elicit. Recent advances in our understanding of tumor-induced and host-mediated immunosuppressive mechanisms, the development of effective strategies to combat these suppressive effects, and a better understanding of how to deliver immunologic effector molecules more efficiently to CNS tumors have all facilitated significant progress toward the realization of true clinical benefit from immunotherapeutic treatment of malignant gliomas.

Combined treatment with atorvastatin and minocycline suppresses severity of EAE

Multiple sclerosis (MS) is the most common inflammatory demyelinating disorder of the central nervous system (CNS). An approach to improve MS treatment is to identify a rational combination of new medications or existing therapies that impact different aspects of the disease process. Statins are effective in the treatment of MS animal models and are promising candidates for future treatment. Minocycline ameliorates clinical severity of experimental autoimmune encephalomyelitis (EAE) and exhibits several anti-inflammatory and neuroprotective activities. In this study, we tested whether the combination of these two drugs could produce beneficial effects in EAE mice immunized with myelin oligodendrocyte protein (MOG). Our findings show that combined treatment, compared to using the medications alone, resulted in a significant reduction in disease severity, in both the acute and chronic phases of the disease, along with attenuation of inflammation, demyelination and axonal loss. Stereological analysis revealed that the combined treatment significantly guarded against neuroinflammation and neurodegeneration. Moreover, a significant suppression of anti-MOG antibody production in animals treated with the two medications was found. In conclusion, our findings prove that this combination of drugs is neuroprotective and suppresses the severity of EAE. Furthermore, this pharmacological approach appears to be promising as a future therapeutic strategy to control MS.

TNF-related apoptosis-inducing ligand (TRAIL)/Apo2L suppresses experimental autoimmune encephalomyelitis in mice

Studies have suggested that endogenous TNF-related apoptosis-inducing ligand (TRAIL)/Apo2L may suppress the induction of some autoimmune diseases in mice. Here, we show that TRAIL/Apo2L suppresses autoimmune damage in relapsing-remitting, and non-remitting models of experimental autoimmune encephalomyelitis (EAE). TRAIL/Apo2L-deficient mice and wild-type mice treated with neutralizing anti-TRAIL/Apo2L antibody displayed enhanced clinical score, increased T-cell proliferative responses to myelin oligodendrocyte glycoprotein (MOG), and increased numbers of inflammatory lesions in the spinal cord and central nervous system. TRAIL neutralization immediately before disease onset was most effective at exacerbating disease score. More importantly, therapeutic intervention with recombinant soluble TRAIL/Apo2L delayed the onset and reduced the severity of MOG-induced EAE. These data are the first to illustrate the potential therapeutic value of recombinant TRAIL/Apo2L in suppressing T-cell-mediated autoimmune diseases.