Induction of a multiple sclerosis-like disease in mice with an immunodominant epitope of myelin oligodendrocyte glycoprotein

MOG CNS Autoimmunity and MOGAD

At one time considered a possible form of neuromyelitis optica (NMO) spectrum disorder (NMOSD), it is now accepted that myelin oligodendrocyte glycoprotein (MOG) antibody (Ab)-associated disorder (MOGAD) is a distinct entity from either NMO or multiple sclerosis (MS) and represents a broad spectrum of clinical phenotypes. Whereas Abs targeting aquaporin-4 (AQP4) in NMO are pathogenic, the extent that anti-MOG Abs contribute to CNS damage in MOGAD is unclear. Both AQP4-specific Abs in NMO and MOG-specific Abs in MOGAD are predominantly IgG1, a T cell-dependent immunoglobulin (Ig) subclass. Key insights in neuroimmunology and MOGAD pathogenesis have been learned from MOG experimental autoimmune encephalomyelitis (EAE), described 2 decades before the term MOGAD was introduced. MOG-specific T cells are required in MOG EAE, and while anti-MOG Abs can exacerbate EAE and CNS demyelination, those Abs are neither necessary nor sufficient to cause EAE. Knowledge regarding the spectrum of MOGAD clinical and radiologic presentations is advancing rapidly, yet our grasp of MOGAD pathogenesis is incomplete. Understanding both the humoral and cellular immunology of MOGAD has implications for diagnosis, treatment, and prognosis.

The neuropathobiology of multiple sclerosis

Chronic low-grade inflammation and neuronal deregulation are two components of a smoldering disease activity that drives the progression of disability in people with multiple sclerosis (MS). Although several therapies exist to dampen the acute inflammation that drives MS relapses, therapeutic options to halt chronic disability progression are a major unmet clinical need. The development of such therapies is hindered by our limited understanding of the neuron-intrinsic determinants of resilience or vulnerability to inflammation. In this Review, we provide a neuron-centric overview of recent advances in deciphering neuronal response patterns that drive the pathology of MS. We describe the inflammatory CNS environment that initiates neurotoxicity by imposing ion imbalance, excitotoxicity and oxidative stress, and by direct neuro-immune interactions, which collectively lead to mitochondrial dysfunction and epigenetic dysregulation. The neuronal demise is further amplified by breakdown of neuronal transport, accumulation of cytosolic proteins and activation of cell death pathways. Continuous neuronal damage perpetuates CNS inflammation by activating surrounding glia cells and by directly exerting toxicity on neighbouring neurons. Further, we explore strategies to overcome neuronal deregulation in MS and compile a selection of neuronal actuators shown to impact neurodegeneration in preclinical studies. We conclude by discussing the therapeutic potential of targeting such neuronal actuators in MS, including some that have already been tested in interventional clinical trials.

Active Induction of a Multiple Sclerosis-Like Disease in Common Laboratory Mouse Strains

Experimental autoimmune encephalomyelitis (EAE) is a neuroinflammatory disease with facets in common with multiple sclerosis (MS). It is induced in susceptible mammalian species, with rodents as the preferred hosts, and has been used for decades as a model to investigate the immunopathogenesis of MS as well as for preclinical evaluation of candidate MS therapeutics. Most commonly, EAE is generated by active immunization with central nervous system (CNS) antigens, such as whole CNS homogenate, myelin proteins, or peptides derived from these proteins. However, EAE actually represents a spectrum of diseases in which specific combinations of host/CNS antigen exhibit defined clinical profiles, each associated with unique immunological and pathological features. Similar to MS, EAE is a complex disease where development and progression are also modulated by environmental factors; therefore, the establishment of any given EAE variant can be challenging and requires careful optimization. Here, we describe protocols for three EAE variants, successfully generated in our laboratory, and provide additional information as to how to maintain their unique features and reproducibility.

Astrocytes Undergo Metabolic Reprogramming in the Multiple Sclerosis Animal Model

Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system that presents a largely unknown etiopathology. The presence of reactive astrocytes in MS lesions has been described for a long time; however, the role that these cells play in the pathophysiology of MS is still not fully understood. Recently, we used an MS animal model to perform high-throughput sequencing of astrocytes' transcriptome during disease progression. Our data show that astrocytes isolated from the cerebellum (a brain region typically affected in MS) showed a strong alteration in the genes that encode for proteins related to several metabolic pathways. Specifically, we found a significant increase in glycogen degradation, glycolytic, and TCA cycle enzymes. Together with these alterations, we detected an upregulation of genes that characterize "astrocyte reactivity". Additionally, at each disease time point we also reconstructed the morphology of cerebellum astrocytes in non-induced controls and in EAE animals, near lesion regions and in the normal-appearing white mater (NAWM). We found that near lesions, astrocytes presented increased length and complexity compared to control astrocytes, while no significant alterations were observed in the NAWM. How these metabolic alterations are linked with disease progression is yet to be uncovered. Herein, we bring to the literature the hypothesis of performing metabolic reprogramming as a novel therapeutic approach in MS.

mRNA expression profile reveals differentially expressed genes in splenocytes of experimental autoimmune encephalomyelitis model

Experimental autoimmune encephalomyelitis (EAE) is a mouse model that can be used to investigate aetiology, pathogenesis, and treatment approaches for multiple sclerosis (MS). A novel integrated bioinformatics approach was used to understand the involvement of differentially expressed genes (DEGs) in the spleen of EAE mice through data mining of existing microarray and RNA-seq datasets. We screened differentially expressed mRNAs using mRNA expression profile data of EAE spleens taken from Gene Expression Omnibus (GEO). Functional and pathway enrichment analyses of DEGs were performed by Database for Annotation, Visualization, and Integrated Discovery (DAVID). Subsequently, the DEGs-encoded protein-protein interaction (PPI) network was constructed. The 784 DEGs in GSE99300 A.SW PP-EAE mice spleen mRNA profiles, 859 DEGs in GSE151701 EAE mice spleen mRNA profiles, and 646 DEGs in GSE99300 SJL/J PP-EAE mice spleen mRNA profiles were explored. Functional enrichment of 55 common DEGs among 3 sub-datasets revealed several immune-related terms, such as neutrophil extravasation, leucocyte migration, antimicrobial humoral immune response mediated by an antimicrobial peptide, toll-like receptor 4 bindings, IL-17 signalling pathway, and TGF-beta signalling pathway. In the screening of 10 hub genes, including MPO, ELANE, CTSG, LTF, LCN2, SELP, CAMP, S100A9, ITGA2B, and PRTN3, and in choosing and validating the 5 DEGs, including ANK1, MBOAT2, SLC25A21, SLC43A1, and SOX6, the results showed that SLC43A1 and SOX6 were significantly decreased in EAE mice spleen. Thus this study offers a list of genes expressed in the spleen that might play a key role in the pathogenesis of EAE.

Effects of Five Coumarins and Standardized Extracts from Tagetes lucida Cav. on Motor Impairment and Neuroinflammation Induced with Cuprizone

Multiple sclerosis (MS) is an autoimmune disease of the central nervous system (CNS) with no curative treatment, and the available therapies aim to modify the course of the disease. It has been demonstrated that extracts of Tagetes lucida have immunomodulatory and neuroprotective effects. This work induced motor damage and neuroinflammation in male BALB/c mice by oral administration of cuprizone (CPZ) (40 mg/kg) for five weeks. In addition, the extracts and coumarins of Tagetes lucida (25 mg/kg) were used to control these damage variables; during the experiment, animals were subject to behavioral tests, and at the end of 5 weeks, mice from each group were used to measure the integrity of biological barriers (brain, kidneys, and spleen) through the extravasation test with blue Evans dye. In another group of animals, the ELISA method measured the brain concentrations of IL-1β, IL-4, IL-10, and TNF-α. The results presented here allow us to conclude that the extracts and coumarins IC, HN, PE, DF, and SC of Tagetes lucida exert a neuroprotective effect by controlling the motor damage and neuroinflammation by increasing the expression of IL-4 and IL-10 and decreasing IL-1β and TNF-α; notably, these treatments also protect organs from vascular permeability increase, mainly the BBB, in mice with CPZ-induced experimental encephalomyelitis (VEH * p < 0.05). However, more studies must be carried out to elucidate the molecular mechanisms of the pharmacological effects of this Mexican medicinal plant.

Impact of histone modifier-induced protection against autoimmune encephalomyelitis on multiple sclerosis treatment

Multiple sclerosis is a progressive demyelinating central nervous system disorder with unknown etiology. The condition has heterogeneous presentations, including relapsing-remitting multiple sclerosis and secondary and primary progressive multiple sclerosis. The genetic and epigenetic mechanisms underlying these various forms of multiple sclerosis remain elusive. Many disease-modifying therapies approved for multiple sclerosis are broad-spectrum immunomodulatory drugs that reduce relapses but do not halt the disease progression or neuroaxonal damage. Some are also associated with many severe side effects, including fatalities. Improvements in disease-modifying treatments especially for primary progressive multiple sclerosis remain an unmet need. Several experimental animal models are available to decipher the mechanisms involved in multiple sclerosis. These models help us decipher the advantages and limitations of novel disease-modifying therapies for multiple sclerosis.

Experimental Autoimmune Encephalomyelitis in the Mouse

This article details the materials and methods required for both active induction and adoptive transfer of experimental autoimmune encephalomyelitis (EAE) in the SJL mouse strain using intact proteins or peptides from the two major myelin proteins: proteolipid protein (PLP) and myelin basic protein (MBP). Additionally, active induction of EAE in the C57BL/6 strain using myelin oligodendrocyte glycoprotein (MOG) peptide is also discussed. Detailed materials and methods required for the purification of both PLP and MBP are described, and a protocol for isolating CNS-infiltrating lymphocytes in EAE mice is included. Modifications of the specified protocols may be necessary for efficient induction of active or adoptive EAE in other mouse strains. © 2021 Wiley Periodicals LLC. Basic Protocol: Active induction of EAE with PLP, MBP, and MOG protein or peptide Alternate Protocol: Adoptive induction of EAE with PLP-, MBP-, or MOG-specific lymphocytes Support Protocol 1: Purification of proteolipid protein Support Protocol 2: Purification of myelin basic protein Support Protocol 3: Isolation of CNS-infiltrating lymphocytes.

MHC class II tetramers engineered for enhanced binding to CD4 improve detection of antigen-specific T cells

The ability to identify T cells that recognize specific peptide antigens bound to major histocompatibility complex (MHC) molecules has enabled enumeration and molecular characterization of the lymphocytes responsible for cell-mediated immunity. Fluorophore-labeled peptide:MHC class I (p:MHCI) tetramers are well-established reagents for identifying antigen-specific CD8+ T cells by flow cytometry, but efforts to extend the approach to CD4+ T cells have been less successful, perhaps owing to lower binding strength between CD4 and MHC class II (MHCII) molecules. Here we show that p:MHCII tetramers engineered by directed evolution for enhanced CD4 binding outperform conventional tetramers for the detection of cognate T cells. Using the engineered tetramers, we identified about twice as many antigen-specific CD4+ T cells in mice immunized against multiple peptides than when using traditional tetramers. CD4 affinity-enhanced p:MHCII tetramers, therefore, allow direct sampling of antigen-specific CD4+ T cells that cannot be accessed with conventional p:MHCII tetramer technology. These new reagents could provide a deeper understanding of the T cell repertoire.

Modulation by Anisakis simplex antigen of inflammatory response generated in experimental autoimmune encephalomyelitis

The impact of immunization with Anisakis simplex larval antigen on the occurrence and progression of experimental autoimmune encephalomyelitis (EAE) induced in mice was studied. C57BL/6J mice were immunized with the MOG_35-55 peptide and one batch was treated with A. simplex total larval antigen on days 1, 8, 10 and 12 after EAE induction. Significantly higher values were obtained in the EAE clinical parameters of the antigen-treated group. Likewise, there was a significant decrease in the weights of the animals. Anisakis-treatment produced a significant decrease in anti-MOG_35-55 specific IgG1 on day 21. On day 14 there was an increase in serum IL-2, IL-6, IL-10, IL-17A, and TGF-β in the treated group. On day 21, a decrease in IL-4, IL-6, TNF-α, TGF-β was observed. All brain determinations were made on day 21. The treatment decreased values of IL-6, IL-10, IL-17A and TNF-α. A. simplex antigen caused a significantly higher incidence of EAE and an advance in the appearance of the disease manifestations. However, treatment with the antigen was able to cause a decrease in proinflammatory cytokines (IL-6, IL-17A, and TNF-α) in nervous tissue that could establish a future preventive scenario for myelin damage.

CSF1R signaling is a regulator of pathogenesis in progressive MS

Microglia serve as the innate immune cells of the central nervous system (CNS) by providing continuous surveillance of the CNS microenvironment and initiating defense mechanisms to protect CNS tissue. Upon injury, microglia transition into an activated state altering their transcriptional profile, transforming their morphology, and producing pro-inflammatory cytokines. These activated microglia initially serve a beneficial role, but their continued activation drives neuroinflammation and neurodegeneration. Multiple sclerosis (MS) is a chronic, inflammatory, demyelinating disease of the CNS, and activated microglia and macrophages play a significant role in mediating disease pathophysiology and progression. Colony-stimulating factor-1 receptor (CSF1R) and its ligand CSF1 are elevated in CNS tissue derived from MS patients. We performed a large-scale RNA-sequencing experiment and identified CSF1R as a key node of disease progression in a mouse model of progressive MS. We hypothesized that modulating microglia and infiltrating macrophages through the inhibition of CSF1R will attenuate deleterious CNS inflammation and reduce subsequent demyelination and neurodegeneration. To test this hypothesis, we generated a novel potent and selective small-molecule CSF1R inhibitor (sCSF1R_inh) for preclinical testing. sCSF1R_inh blocked receptor phosphorylation and downstream signaling in both microglia and macrophages and altered cellular functions including proliferation, survival, and cytokine production. In vivo, CSF1R inhibition with sCSF1R_inh attenuated neuroinflammation and reduced microglial proliferation in a murine acute LPS model. Furthermore, the sCSF1R_inh attenuated a disease-associated microglial phenotype and blocked both axonal damage and neurological impairments in an experimental autoimmune encephalomyelitis (EAE) model of MS. While previous studies have focused on microglial depletion following CSF1R inhibition, our data clearly show that signaling downstream of this receptor can be beneficially modulated in the context of CNS injury. Together, these data suggest that CSF1R inhibition can reduce deleterious microglial proliferation and modulate microglial phenotypes during neuroinflammatory pathogenesis, particularly in progressive MS.

Investigation of type 1 diabetes in NOD mice knockout for the osteopontin gene

OBJECTIVE

Type 1 diabetes onset is preceded by a pre-inflammatory stage leading to insulitis and followed by targeted destruction of the insulin-producing beta cells of the pancreas. Osteopontin (OPN) is a secreted phosphoprotein with cytokine properties, implicated in many physiological and pathological processes, including infection and autoimmunity. We have previously identified up-regulated osteopontin transcripts in the pancreatic lymph nodes of the NOD (Non-Obese Diabetic) mouse at the pre-diabetic stages. Investigating the underlined disease initiating mechanisms may well contribute to the development of novel preventive therapies. Our aim was to construct opn null mice in a NOD autoimmune-prone genetic background and address the pathogenic or protective role of the osteopontin molecule in the early stages of type 1 diabetes.

METHODS

We generated opn null mutant mice in a NOD genetic background by serial backcrossing to the existing C57BL/6 opn knockout strain. The presence of opn wild type or null alleles in the congenic lines was evaluated by PCR amplification. We used NOD opn-null mice to assess the phenotypic evolution of type 1 diabetes. The presence of OPN in the serum was evaluated by ELISA and by immunostaining on the mouse tissues. The primary gene structure of the NOD opn encoding gene and protein sequences were compared to the known alleles of other mouse strains. Evaluation of Single Nucleotide Polymorphisms (SNPs) variation between opn alleles of the opn gene is reported.

RESULTS

In the absence of OPN, type 1 diabetes is accelerated, suggesting a protective role of this cytokine on the insulin-producing cells of the pancreatic islets. Conversely, in the presence of the opn gene, an increase of the OPN protein in the serum of young NOD mice indicates that this molecule might be involved in the immune regulatory events taking place at early stages, prior to disease onset. Our data support that OPN acts as a positive regulator of the early islet autoimmune damage, possibly by a shift of the steady-state of T1D pathogenesis. We report that the OPN protein structure of the NOD/ShiLtJ strain corresponds to the a-type allele of the osteopontin gene. Comparative analysis of the single nucleotide polymorphisms between the a-type and b-type alleles indicates that the majority of variations are within the non-coding regions of the gene.

CONCLUSIONS

The construction of opn null mice in an autoimmune genetic background (NOD.B6.Cg-spp1^-/-) provides important tools for the study of the implication of the OPN in type 1 diabetes, offering the possibility to address the significance of this molecule as an early marker of the disease and as a therapeutic agent in preclinical studies.

Assessing the anterior visual pathway in optic neuritis: recent experimental and clinical aspects

PURPOSE OF REVIEW

Multiple sclerosis (MS) and related autoimmune disorders of the central nervous system such as neuromyelitis optica spectrum disorders (NMOSD) are characterized by chronic disability resulting from autoimmune neuroinflammation, with demyelination, astrocyte damage, impaired axonal transmission and neuroaxonal loss. Novel therapeutics stopping or reversing the progression of disability are still urgently warranted. This review addresses research on optic neuritis in preclinical experimental models and their translation to clinical trials.

RECENT FINDINGS

Optic neuritis can be used as paradigm for an MS relapse which can serve to evaluate the efficacy of novel therapeutics in clinical trials with a reasonable duration and cohort size. The advantage is the linear structure of the visual pathway allowing the assessment of visual function and retinal structure as highly sensitive outcome parameters. Experimental autoimmune encephalomyelitis is an inducible, inflammatory and demyelinating central nervous system disease extensively used as animal model of MS. Optic neuritis is part of the clinicopathological manifestations in a number of experimental autoimmune encephalomyelitis models. These have gained increasing interest for studies evaluating neuroprotective and/or remyelinating substances as longitudinal, visual and retinal readouts have become available.

SUMMARY

Translation of preclinical experiments, evaluating neuroprotective or remyelinating therapeutics to clinical studies is challenging. In-vivo readouts like optical coherence tomography, offers the possibility to transfer experimental study designs to clinical optic neuritis trials.

Development and optimisation of an animal model for the study of ganglion cells in degenerative diseases of the retina and optic nerve

INTRODUCTION

Multiple sclerosis is an autoimmune, chronic and inflammatory disease of the central nervous system with axonal demyelination, gliosis and neurodegeneration. It is considered a frequent cause of neurological disability in young adults. In this work, an Experimental Autoimmune Encephalomyelitis (EAE) model was optimised by injecting a myelin oligodendrocyte glycoprotein (MOG_35-55). The ophthalmological effects were studied, as well as its use as an experimental model in other studies of retinal ganglion cell degeneration (RGC) and optic nerve (ON).

MATERIAL AND METHODS

The study included 16 mice of 10 weeks that were placed into 2 study groups: a control group of 10 animals and another group of 6 animals with EAE that were injected with MOG_35-55. The animals of the EAE model were monitored using motor disability scales. The retinas and optic nerves were processed for morphological examination by optical microscopy and ultrastructure studies.

RESULTS

The animal models presented with motor symptoms of spinal cord injury, with the first symptoms appearing between the 7th and 19th day post-injection, with a maximum disability mean of 3.5 points. In the retina, the mean RGC in the EAE group was 0.0891μm, compared with 0.1678μm of the control group (p=.0003). The ON was strongly affected with reactive gliosis, increased axonal damage and decreased density axonal (control group 0.38038 axons/μm² versus EAE group 0.16 axons/μm², p=.00032).

CONCLUSIONS

In this work an animal model of EAE has been characterised and detailed for the study of demyelinating alterations in the retina and the ON. Its characteristics make it an excellent tool for the study of neurodegenerative ophthalmic diseases.

The Short and Long-Term Effects of Pregnancy on Multiple Sclerosis and Experimental Autoimmune Encephalomyelitis

The role of pregnancy in multiple sclerosis (MS) is of importance because many patients with MS are young women in the childbearing age who require information to inform their reproductive decisions. Pregnancy is now well-known to be associated with fewer relapses of MS and reduced activity of autoimmune encephalomyelitis (EAE). However, in women with multiple sclerosis, this benefit is not always sufficient to protect against a rebound of disease activity if disease-modulating therapy is ceased for pregnancy. There is concern that use of assisted reproductive therapies can be associated with relapses of MS, but more data are required. It is thought that the beneficial effects of pregnancy are due to the pregnancy-associated changes in the maternal immune system. There is some evidence of this in human studies and studies of EAE. There is also evidence that having been pregnant leads to better long-term outcome of MS. The mechanism for this is not fully understood but it could result from epigenetic changes resulting from pregnancy or parenthood. Further studies of the mechanisms of the beneficial effects of pregnancy could provide information that might be used to produce new therapies.

The epigenetic drug Trichostatin A ameliorates experimental autoimmune encephalomyelitis via T cell tolerance induction and impaired influx of T cells into the spinal cord

Multiple sclerosis is a T cell mediated chronic demyelinating disease of the central nervous system. Although currently available therapies reduce relapses, they do not facilitate tolerization of myelin antigen-specific T lymphocytes to ensure prolonged protection against multiple sclerosis. Here, we show that treatment of NOD mice with the histone deacetylase inhibitor, Trichostatin A affords robust protection against myelin peptide induced experimental autoimmune encephalomyelitis, a mouse model of multiple sclerosis. Protection was accompanied by histone hyperacetylation, and reduced inflammation and axonal damage in the spinal cord. Drug treatment diminished the generation of CD4⁺ memory T cells and induced tolerance in CD4⁺ T cells recognizing the immunizing myelin peptide. During the early immunization period, CD4⁺ T cells producing GM-CSF+IFN-γ, GM-CSF+IL-17A, as well as those expressing both IL-17A+IFN-γ (double-producers) were detected in the secondary lymphoid organs followed by the appearance of cells producing IFN-γ and GM-CSF. On the other hand, IFN-γ producing Th1 cells appear first in the spinal cord followed by cells producing IL-17A and GM-CSF. Treatment with Trichostatin A substantially reduced the frequencies of all T cells secreting various lymphokines both in the periphery and in the spinal cord. These data indicate that epigenetic modifications induced by histone hyperacetylation facilitates T cell tolerance induction in the periphery leading to reduced migration of T cells to the spinal cord and mitigation of neuronal damage and improved clinical outcome. These results suggest that epigenetic modulation of the genome may similarly offer benefits to multiple sclerosis patients via abrogating the function of encephalitogenic T lymphocytes without exerting severe side effects associated with currently used disease-modifying therapies.

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.

Lymphatics in Neurological Disorders: A Neuro-Lympho-Vascular Component of Multiple Sclerosis and Alzheimer's Disease?

Lymphatic vasculature drains interstitial fluids, which contain the tissue's waste products, and ensures immune surveillance of the tissues, allowing immune cell recirculation. Until recently, the CNS was considered to be devoid of a conventional lymphatic vasculature. The recent discovery in the meninges of a lymphatic network that drains the CNS calls into question classic models for the drainage of macromolecules and immune cells from the CNS. In the context of neurological disorders, the presence of a lymphatic system draining the CNS potentially offers a new player and a new avenue for therapy. In this review, we will attempt to integrate the known primary functions of the tissue lymphatic vasculature that exists in peripheral organs with the proposed function of meningeal lymphatic vessels in neurological disorders, specifically multiple sclerosis and Alzheimer's disease. We propose that these (and potentially other) neurological afflictions can be viewed as diseases with a neuro-lympho-vascular component and should be therapeutically targeted as such.

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.

Epitope mapping of anti-myelin oligodendrocyte glycoprotein (MOG) antibodies in a mouse model of multiple sclerosis: microwave-assisted synthesis of the peptide antigens and ELISA screening

The role of pathologic auto-antibodies against myelin oligodendrocyte glycoprotein (MOG) in multiple sclerosis is a highly controversial matter. As the use of animal models may enable to unravel the molecular mechanisms of the human disorder, numerous studies on multiple sclerosis are carried out using experimental autoimmune encephalomyelitis (EAE). In particular, the most extensively used EAE model is obtained by immunizing C57BL/6 mice with the immunodominant peptide MOG(35-55). In this scenario, we analyzed the anti-MOG antibody response in this model using the recombinant refolded extracellular domain of the protein, MOG(1-117). To assess the presence of a B-cell intramolecular epitope spreading mechanism, we tested also five synthetic peptides mapping the 1-117 sequence of MOG, including MOG(35-55). For this purpose, we cloned, expressed in Escherichia coli and on-column refolded MOG(1-117), and we applied an optimized microwave-assisted solid-phase synthetic strategy to obtain the designed peptide sequences. Subsequently, we set up a solid-phase immunoenzymatic assay testing both naïve and EAE mice sera and using MOG protein and peptides as antigenic probes. The results obtained disclose an intense IgG antibody response against both the recombinant protein and the immunizing peptide, while no response was observed against the other synthetic fragments, thus excluding the presence of an intramolecular epitope spreading mechanism. Furthermore, as the properly refolded recombinant probe is able to bind antibodies with greater efficiency compared with MOG(35-55), we hypothesize the presence of both linear and conformational epitopes on MOG(35-55) sequence.

Analysis of the direct injury effector of oligodendroglia cells or myelin sheath in an experimental allergic encephalomyelitis model induced by the MOG35-55 peptide

The aim of the present study was to investigate the possible role of cytotoxic T lymphocytes (CTL) and mononuclear macrophages in the pathogenic processes of experimental animals. To construct a chronic experimental allergic encephalomyelitis (EAE) model, an artificially synthesized myelin oligodendrocyte glycoprotein (MOG)35‑55 peptide was used to induce C57BL/6 mice. Subsequently, the experimental animals were investigated at the level of their nervous function, and histopathological, immunohistochemical and fluorescence immunohistochemical experiments were performed at different time points following immunization. The expression of immune molecules and cytokines associated with the activation of the mononuclear macrophages and CTL during the different stages was assessed by western blotting and reverse transcription‑quantitative polymerase chain reaction. As a result, the MOG35‑55 peptide was identified as being successful at inducing C57BL/6 mice for the development of the EAE model. A modest level of mononuclear macrophage and lymphocyte infiltration was observed in the central nervous system (CNS), although no infiltration of neutrophils was observed. A sporadic flaky deletion of the myelin sheath was also identified. The activation and proliferation of mononuclear macrophages, including microglia cells, was clearly demonstrated. Furthermore, the expression levels of major histocompatibility complex class I and II molecules and interleukin‑12 in the brain, which is associated with the activation and proliferation of mononuclear macrophages, increased over the duration of the experiment compared with less pronounced changes in the expression levels of interferon (IFN)‑γ, Fas and perforin in the CNS, which are associated with the function of CTL. The secretion of IFN‑γ in the spleen increased during the morbidity peak, however, any noticeable activation and proliferation of CD8+ T cells was absent. These results demonstrated that the induced immune response mediated by mononuclear macrophages made a more important contribution compared with CTL towards the pathological process of myelin sheath injury. Mononuclear macrophages are therefore, identified as being one of the most significant effector cell types to directly injure the myelin sheath in the CNS.

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.

Damage to the optic chiasm in myelin oligodendrocyte glycoprotein-experimental autoimmune encephalomyelitis mice

Optic chiasm lesions in myelin oligodendrocyte glycoprotein (MOG)–experimental autoimmune encephalomyelitis (EAE) mice were characterized using magnetic resonance imaging (MRI) and validated using electron microscopy (EM). MR images were collected from 3 days after induction to remission, approximately 20 days after induction. Hematoxylin and eosin, solochrome cyanin–stained sections, and EM images were obtained from the optic chiasms of some mice approximately 4 days after disease onset when their scores were thought to be the highest. T₂-weighted imaging and apparent diffusion coefficient map hyperintensities corresponded to abnormalities in the optic chiasms of EAE mice. Mixed inflammation was concentrated at the lateral surface. Degeneration of oligodendrocytes, myelin, and early axonal damage were also apparent. A marked increase in chiasm thickness was observed. T₂-weighted and diffusion-weighted MRI can detect abnormalities in the optic chiasms of MOG-EAE mice. MRI is an important method in the study of this model toward understanding optic neuritis.

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.

Multiple sclerosis-induced neuropathic pain: pharmacological management and pathophysiological insights from rodent EAE models

In patients with multiple sclerosis (MS), pain is a frequent and disabling symptom. The prevalence is in the range 29-86 % depending upon the assessment protocols utilised and the definition of pain applied. Neuropathic pain that develops secondary to demyelination, neuroinflammation and axonal damage in the central nervous system is the most distressing and difficult type of pain to treat. Although dysaesthetic extremity pain, L'hermitte's sign and trigeminal neuralgia are the most common neuropathic pain conditions reported by patients with MS, research directed at gaining insight into the complex mechanisms underpinning the pathobiology of MS-associated neuropathic pain is in its relative infancy. By contrast, there is a wealth of knowledge on the neurobiology of neuropathic pain induced by peripheral nerve injury. To date, the majority of research in the MS field has used rodent models of experimental autoimmune encephalomyelitis (EAE) as these models have many clinical and neuropathological features in common with those observed in patients with MS. However, it is only relatively recently that EAE-rodents have been utilised to investigate the mechanisms contributing to the development and maintenance of MS-associated central neuropathic pain. Importantly, EAE-rodent models exhibit pro-nociceptive behaviours predominantly in the lower extremities (tail and hindlimbs) as seen clinically in patients with MS-neuropathic pain. Herein, we review research to date on the pathophysiological mechanisms underpinning MS-associated neuropathic pain as well as the pharmacological management of this condition. We also identify knowledge gaps to guide future research in this important field.

Molecular grafting onto a stable framework yields novel cyclic peptides for the treatment of multiple sclerosis

Multiple sclerosis (MS) is an inflammatory disease of the central nervous system (CNS) and is characterized by the destruction of myelin and axons leading to progressive disability. Peptide epitopes from CNS proteins, such as myelin oligodendrocyte glycoprotein (MOG), possess promising immunoregulatory potential for treating MS; however, their instability and poor bioavailability is a major impediment for their use clinically. To overcome this problem, we used molecular grafting to incorporate peptide sequences from the MOG_35–55 epitope onto a cyclotide, which is a macrocyclic peptide scaffold that has been shown to be intrinsically stable. Using this approach, we designed novel cyclic peptides that retained the structure and stability of the parent scaffold. One of the grafted peptides, MOG3, displayed potent ability to prevent disease development in a mouse model of MS. These results demonstrate the potential of bioengineered cyclic peptides for the treatment of MS.

Nogo-receptor 1 deficiency has no influence on immune cell repertoire or function during experimental autoimmune encephalomyelitis

The potential role of Nogo-66 Receptor 1 (NgR1) on immune cell phenotypes and their activation during neuroinflammatory diseases such as multiple sclerosis (MS) and its animal model, experimental autoimmune encephalomyelitis (EAE), is unclear. To further understand the function of this receptor on haematopoietically-derived cells, phenotypic and functional analyses were performed using NgR1-deficient (ngr1-/-) animals. Flow cytometry-based phenotypic analyses performed on blood, spleen, thymus, lymph nodes, bone marrow and central nervous-system (CNS)-infiltrating blood cells revealed no immunological defects in naïve ngr1-/- animals versus wild-type littermate (WTLM) controls. EAE was induced by either recombinant myelin oligodendrocyte glycoprotein (rMOG), a model in which B cells are considered to contribute pathogenically, or by MOG_35–55 peptide, a B cell-independent model. We have demonstrated that in ngr1-/- mice injected with MOG_35–55, a significant reduction in the severity of EAE correlated with reduced axonal damage present in the spinal cord when compared to their WTLM controls. However, despite a reduction in axonal damage observed in the CNS of ngr1-/- mice at the chronic stage of disease, no clinical differences could be attributed to a specific genotype when rMOG was used as the encephalitogen. Following MOG_35–55-induction of EAE, we could not derive any major changes to the immune cell populations analyzed between ngr1-/- and WTLM mice. Collectively, these data demonstrate that NgR1 has little if any effects on the repertoire of immune cells, their activation and trafficking to the CNS.

Proteome analysis of post-transplantation recovery mechanisms of an EAE model of multiple sclerosis treated with embryonic stem cell-derived neural precursors

Multiple sclerosis (MS) is a chronic inflammatory and progressive disorder of the central nervous system (CNS), which ultimately causes demyelination and subsequent axonal injury. Experimental autoimmune encephalomyelitis (EAE) is a well-characterized animal model to study the etiology and pathogenesis of MS. This model can also be used to investigate various therapeutic approaches for MS. Herein; we have treated a score 3 EAE mouse model with an embryonic stem cell-derived neural precursor. Clinical analysis showed recovery of the EAE model of MS following transplantation. We analyzed the proteome of spinal cords of healthy and EAE samples before and after transplantation. Proteome analysis revealed that expressions of 86 spinal cord protein spots changed in the EAE or transplanted mouse compared to controls. Mass spectrometry resulted in identification of 72 proteins. Of these, the amounts of 27 differentially expressed proteins in EAE samples returned to sham levels after transplantation, suggesting a possible correlation between changes at the proteome level and clinical signs of EAE in transplanted mice. The recovered proteins belonged to various functional groups that included disturbances in ionic and neurotransmitter release, apoptosis, iron hemostasis, and signal transduction. Our results provided a proteomic view of the molecular mechanisms of EAE recovery after stem cell transplantation.

BIOLOGICAL SIGNIFICANCE

In this study, we applied proteomics to analyze the changes in proteome pattern of EAE mouse model after embryonic stem cell-derived neural precursor transplantation. Our proteome results clearly showed that the expression levels of several differentially expressed proteins in EAE samples returned to sham levels after transplantation, which suggested a possible correlation between changes at the proteome level and decreased clinical signs of EAE in transplanted mice. These results will serve as a basis to address new questions and design new experiments to elucidate the biology of EAE and recovery after transplantation. A thorough understanding of stem cell-mediated therapeutic mechanisms might result in the development of more efficacious therapies for MS than are currently available.

Gene expression in the spinal cord in female lewis rats with experimental autoimmune encephalomyelitis induced with myelin basic protein

Background

Experimental autoimmune encephalomyelitis (EAE), the best available model of multiple sclerosis, can be induced in different animal strains using immunization with central nervous system antigens. EAE is associated with inflammation and demyelination of the nervous system. Micro-array can be used to investigate gene expression and biological pathways that are altered during disease. There are few studies of the changes in gene expression in EAE, and these have mostly been done in a chronic mouse EAE model. EAE induced in the Lewis with myelin basic protein (MBP-EAE) is well characterised, making it an ideal candidate for the analysis of gene expression in this disease model.

Methodology/Principal Findings

MBP-EAE was induced in female Lewis rats by inoculation with MBP and adjuvants. Total RNA was extracted from the spinal cords and used for micro-array analysis using AffimetrixGeneChip Rat Exon 1.0 ST Arrays. Gene expression in the spinal cords was compared between healthy female rats and female rats with MBP-EAE. Gene expression in the spinal cord of rats with MBP-EAE differed from that in the spinal cord of normal rats, and there was regulation of pathways involved with immune function and nervous system function. For selected genes the change in expression was confirmed with real-time PCR.

Conclusions/Significance

EAE leads to modulation of gene expression in the spinal cord. We have identified the genes that are most significantly regulated in MBP-EAE in the Lewis rat and produced a profile of gene expression in the spinal cord at the peak of disease.

Heligmosomoides polygyrus: EAE remission is correlated with different systemic cytokine profiles provoked by L4 and adult nematodes

Primary exposure of mice to gastrointestinal nematode infection with Heligmosomoides polygyrus reduces inflammation in an experimental model of multiple sclerosis. In this study, we aimed to evaluate the ability of H. polygyrus L4 larvae and adults infection to reduce the symptoms of ongoing experimental autoimmune encephalomyelitis (EAE) in female C57Bl/6 mice. EAE was induced by myelin oligodendrocyte glycoprotein MOG(p35-55) and after 21 days mice were orally infected with 200 infective larvae (L3) of H. polygyrus. Reduction in EAE symptoms was observed from 2 days post infection and the symptoms were almost completely inhibited at 6 days post infection. This effect was associated with limited total protein content in the cerebrospinal fluid; CSF, and significant decreased pro-inflammatory IL-12p40 concentration and increased concentration of the regulatory cytokines IL-10, TGF-β and IL-6 in the CSF and in the serum. The reduction of EAE symptoms in the enteral phase was associated with higher IL-12p40 concentration in the CSF and very low concentrations of IL-17A and IL-2 in the serum. The fourth stage of gastrointestinal nematode can reverse systemic inflammation in animal models of multiple sclerosis by reducing IL-12 and promoting regulatory cytokines production. The mechanism induced by adult nematodes which sustained EAE inhibition can be provoked by regulatory mechanism connected with reduce IL-17A concentration.

Early intervention with gene-modified mesenchymal stem cells overexpressing interleukin-4 enhances anti-inflammatory responses and functional recovery in experimental autoimmune demyelination

Mesenchymal stem/stromal cells (MSCs) can be isolated from most adult tissues and hold considerable promise for tissue regenerative therapies. Some of the potential advantages that MSCs have over other adult stem cell types include: (1) their relative ease of isolation, culture and expansion; (2) their immunomodulatory properties; (3) they can provide trophic support to injured tissues; (4) they can be transduced by retroviral vectors at a high efficiency; (5) they have an ability to home to sites of inflammation and injury. Collectively these characteristics suggest that MSCs are attractive vehicles for cell and gene therapy applications. In the current study, we investigated whether transplantation of human adipose-derived MSCs (Ad-MSCs) engineered to overexpress the anti-inflammatory cytokine interleukin (IL)-4 was efficacious in experimental autoimmune encephalomyelitis (EAE). Ad-MSCs transduced with a bicistronic lentiviral vector encoding mouse IL-4 and enhanced green fluorescent protein (Ad-IL4-MSCs) stably expressed, relatively high levels of both transgenes. Importantly the phenotypic and functional attributes of Ad-IL4-MSCs, such as the expression of homing molecules and differentiation capacity, was not altered by the transduction process. Notably, the early administration of Ad-IL4-MSCs in mice with EAE at the time of T-cell priming attenuated clinical disease. This protective effect was associated with a reduction in peripheral MOG-specific T-cell responses and a shift from a pro- to an anti-inflammatory cytokine response. These data suggest that the delivery of Ad-MSCs genetically engineered to express anti-inflammatory cytokines may provide a rational approach to promote immunomodulation and tissue protection in a number of inflammatory and degenerative diseases including multiple sclerosis.

Amniotic epithelial cells from the human placenta potently suppress a mouse model of multiple sclerosis

Human amniotic epithelial cells (hAEC) have stem cell-like features and immunomodulatory properties. Here we show that hAEC significantly suppressed splenocyte proliferation in vitro and potently attenuated a mouse model of multiple sclerosis (MS). Central nervous system (CNS) CD3(+) T cell and F4/80(+) monocyte/macrophage infiltration and demyelination were significantly reduced with hAEC treatment. Besides the known secretion of prostaglandin E2 (PGE2), we report the novel finding that hAEC utilize transforming growth factor-β (TGF-β) for immunosuppression. Neutralization of TGF-β or PGE2 in splenocyte proliferation assays significantly reduced hAEC-induced suppression. Splenocytes from hAEC-treated mice showed a Th2 cytokine shift with significantly elevated IL-5 production. While transferred CFSE-labeled hAEC could be detected in the lung, none were identified in the CNS or in lymphoid organs. This is the first report documenting the therapeutic effect of hAEC in a MS-like model and suggest that hAEC may have potential for use as therapy for MS.

Mouse models of multiple sclerosis: experimental autoimmune encephalomyelitis and Theiler's virus-induced demyelinating disease

Experimental autoimmune encephalomyelitis (EAE) and Theiler's Murine Encephalitis Virus-Induced Demyelinating Disease (TMEV-IDD) are two clinically relevant murine models of multiple sclerosis (MS). Like MS, both are characterized by mononuclear cell infiltration into the CNS and demyelination. EAE is induced by either the administration of myelin protein or peptide in adjuvant or by the adoptive transfer of encephalitogenic T cell blasts into naïve recipients. The relative merits of each of these protocols are compared. Depending on the type of question being asked, different mouse strains and peptides are used. Different disease courses are observed with different strains and different peptides in active EAE. These variations are also addressed. Additionally, issues relevant to clinical grading of EAE in mice are discussed. In addition to EAE induction, useful references for other disease indicators such as DTH, in vitro proliferation, and immunohistochemistry are provided. TMEV-IDD is a useful model for understanding the possible viral etiology of MS. This section provides detailed information on the preparation of viral stocks and subsequent intracerebral infection of mice. Additionally, virus plaque assay and clinical disease assessment are discussed. Recently, recombinant TMEV strains have been created for the study of molecular mimicry which incorporate various 30 amino acid myelin epitopes within the leader region of TMEV.

Vaginally administered PEGylated LIF antagonist blocked embryo implantation and eliminated non-target effects on bone in mice

Female-controlled contraception/HIV prevention is critical to address health issues associated with gender inequality. Therefore, a contraceptive which can be administered in tandem with a microbicide to inhibit sexually transmitted infections, is desirable. Uterine leukemia inhibitory factor (LIF) is obligatory for blastocyst implantation in mice and associated with infertility in women. We aimed to determine whether a PEGylated LIF inhibitor (PEGLA) was an effective contraceptive following vaginal delivery and to identify non-uterine targets of PEGLA in mice.

Vaginally-applied ¹²⁵I-PEGLA accumulated in blood more slowly (30 min vs 10 min) and showed reduced tissue and blood retention (24 h vs 96 h) compared to intraperitoneal injection in mice. Vaginally-applied PEGLA blocked implantation. PEGLA administered by intraperitoneal injection inhibited bone remodelling whereas vaginally-applied PEGLA had no effect on bone. Further, PEGLA had no effect in an animal model of multiple sclerosis, experimental auto-immune encephalomyelitis, suggesting PEGLA cannot target the central nervous system.

Vaginally-administered PEGLA is a promising non-hormonal contraceptive, one which could be delivered alone, or in tandem with a microbicide. Vaginal application reduced the total dose of PEGLA required to block implantation and eliminated the systemic effect on bone, showing the vagina is a promising site of administration for larger drugs which target organs within the reproductive tract.

CCR4 contributes to the pathogenesis of experimental autoimmune encephalomyelitis by regulating inflammatory macrophage function

Chemokines and their receptors play a critical role in orchestrating the immune response during experimental autoimmune encephalomyelitis (EAE). Expression of CCR4 and its ligand CCL22 has been observed in ongoing disease. Here we describe a role for CCR4 in EAE, illustrating delayed and decreased disease incidence in CCR4(-/-) mice corresponding with diminished CNS infiltrate. Peripheral T cell responses were unaltered in CCR4(-/-) mice; rather, disease reduction was related to reduced CD11b(+)Ly6C(hi) inflammatory macrophage (iMϕ) numbers and function. These results provide evidence that CCR4 regulates EAE development and further supports the involvement of CCR4 in iMϕ effector function.

Critical appraisal of animal models of multiple sclerosis

Experimental autoimmune encephalomyelitis (EAE) is a spectrum of neurological disorders in laboratory animals that is used to model multiple sclerosis (MS). However, few agents have translated from efficacy in EAE to the treatment of human disease. Although this may reflect species differences in pathological disease mechanisms, importantly it may also relate to the practice of how drugs and models are currently used. This often bears very little resemblance to the clinical scenarios where treatments are investigated, such that lack of appreciation of the biology of disease may doom drugs to failure. The use of EAE is critically appraised with the aim of provoking thought, improving laboratory practise and aiding researchers and reviewers to address quality issues when undertaking, reporting and interpreting animal studies related to MS research. This is important as many researchers using EAE could and should do more to improve the quality of the studies.

Female-biased incidence of experimental autoimmune encephalomyelitis reflects sexually dimorphic expression of surface CTLA-4 (CD152) on T lymphocytes

BACKGROUND

Autoimmune reactions occur naturally and in most cases are controlled by regulatory mechanisms. However, unwanted autoimmune responses still appear in 5% to 7% of the population, in strikingly greater frequencies in women compared with men. The chronic inflammation characteristic of autoimmune diseases is mainly initiated and maintained by autoreactive CD4(+) T lymphocytes. Costimu-lation is required for an optimal response of T lymphocytes: CD28 is a T-cell activator, whereas CTLA-4 (cytotoxic T-lymphocyte antigen 4, also known as CD152) downregulates T-cell activity. Together these costimulatory molecules provide a balance in T-cell immune response.

OBJECTIVE

The aim of this study was to elucidate the role of the inhibitory receptor CTLA-4 in the quality of sex-specific immune responses.

METHODS

At the German Rheumatism Research Center (DRFZ), Berlin, Germany, between 2006 and 2010, we tested mouse strains commonly used for the development of experimental autoimmune encephalomyelitis, the animal model of multiple sclerosis (MS). The SJL mouse strain not only mimics MS pathogenesis, but also exhibits the female predominance that occurs in patients with MS.

RESULTS

Cells derived from SJL females revealed increased proliferation and a doubled frequency of T-helper (Th)1- and Th2-like cytokines, compared with their male counterparts. Moreover, activated Th cells from male mice express significantly higher frequencies (61%) of CTLA-4 expressed at the cell surface in comparison with those of females (46%). Accordingly, close to 50% reduction of CTLA-4 expression occurred in cells of both sexes after the addition of estrogen. We observed that interferon (IFN)-γ(high) production in females occurred in a higher frequency in CD4(+) T cells cultured under neutral conditions (24.6% in females, 15.9% in males). Moreover, we observed that the IFN-yhigh producers were mainly present in females (4.5% vs 0.4% in males).

CONCLUSION

Our results suggest that induction of CTLA-4 expression could serve as a target for an immunomodulatory strategy to downregulate immune responses in sexually dimorphic autoimmune diseases.

Proteome analysis of brain in murine experimental autoimmune encephalomyelitis

Multiple sclerosis is considered a prototype inflammatory autoimmune disorder of the CNS. Experimental autoimmune encephalomyelitis (EAE) induced by myelin oligodendrocyte glycoprotein is one of the best-characterized animal models of multiple sclerosis. Comprehensive understanding of gene expression in EAE can help identify genes that are important in drug response and pathogenesis. We applied a 2-DE-based proteomics approach to analyze the protein expression pattern of the brain in healthy and EAE samples. Of more than 1000 protein spots we analyzed, 70 showed reproducible and significant changes in EAE compared to controls. Of these, 42 protein spots could be identified using MALDI TOF-TOF-MS. They included mitochondrial and structural proteins as well as proteins involved in ionic and neurotransmitter release, blood barriers, apoptosis, and signal transduction. The possible role of these proteins in the responses of mice to animal models of multiple sclerosis is discussed.

Characterization of relapsing-remitting and chronic forms of experimental autoimmune encephalomyelitis in C57BL/6 mice

Multiple sclerosis (MS) is an autoimmune, demyelinating disease of the central nervous system (CNS). Like MS, the animal model experimental autoimmune encephalomyelitis (EAE) is characterized by CNS inflammation and demyelination and can follow a relapsing-remitting (RR) or chronic (CH) disease course. The molecular and pathological differences that underlie these different forms of EAE are not fully understood. We have compared the differences in RR- and CH-EAE generated in the same mouse strain (C57BL/6) using the same antigen. At the peak of disease when mice in both groups have similar clinical scores, CH-EAE is associated with increased lesion burden, myelin loss, axonal damage, and chemokine/cytokine expression when compared with RR-EAE. We further showed that inflammation and myelin loss continue to worsen in later stages of CH-EAE, whereas these features are largely resolved at the equivalent stage in RR-EAE. Additionally, axonal loss at these later stages is more severe in CH-EAE than in RR-EAE. We also demonstrated that CH-EAE is associated with a greater predominance of CD8(+) T cells in the CNS that exhibit MOG(35-55) antigen specificity. These studies therefore showed that, as early as the peak stage of disease, RR- and CH-EAE differ remarkably in their immune cell profile, chemokine/cytokine responses, and histopathological features. These data also indicated that this model of CH-EAE exhibits pathological features of a chronic-progressive disease profile and suggested that the sustained chronic phenotype is due to a combination of axonal loss, myelin loss, and continuing inflammation.

Experimental autoimmune encephalomyelitis in the mouse

This unit details the materials and methods required for both active induction and adoptive transfer of experimental autoimmune encephalomyelitis (EAE) in the SJL mouse strain using intact proteins or peptides from the two major myelin proteins: proteolipid protein (PLP) and myelin basic protein (MBP). Detailed materials and methods required for the purification of both PLP and MBP are also described. A protocol for isolating CNS-infiltrating lymphocytes in EAE mice is included. Modifications of the specified protocols may be necessary for efficient induction of active or adoptive EAE in other mouse strains.

Variable effects of cyclophosphamide in rodent models of experimental allergic encephalomyelitis

In this study, we have evaluated the effects of cyclophosphamide on the development of experimental allergic encephalomyelitis (EAE) in four EAE rodent models: monophasic EAE in Lewis rats, protracted relapsing (PR)-EAE in DA rats, myelin oligodendrocyte protein (MOG)-induced EAE in C57Bl/6 mice and proteolipid protein (PLP)-induced EAE in Swiss/Jackson Laboratory (SJL) mice. Cyclophosphamide, administered either prophylactically or therapeutically, suppressed most strongly the clinical symptoms of PR-EAE in DA rats. Treated rats in this group also exhibited the lowest degree of inflammatory infiltration of the spinal cord, as well as the lowest levels of nuclear factor kappa B, interleukin-12 and interferon-gamma. Cyclophosphamide prophylactically, but not therapeutically, also delayed significantly the onset of EAE in Lewis rats. In contrast, regardless of the treatment regimen used, was unable to influence the clinical course of EAE in either MOG-induced EAE in C57Bl/6 mice or PLP-induced EAE in SJL mice. This heterogeneous pharmacological response to cyclophosphamide suggests that significant immunopathogenic differences exist among these EAE rodent models that must be considered when designing preclinical studies. In addition, the effectiveness of cyclophosphamide in dark Agouti (DA) rats with PR-EAE suggests that this may be a particularly useful model for studying novel therapeutic approaches for refractory and rapidly worsening multiple sclerosis in human patients.

Greatly attenuated experimental autoimmune encephalomyelitis in aquaporin-4 knockout mice

Background

The involvement of astrocyte water channel aquaporin-4 (AQP4) in autoimmune diseases of the central nervous system has been suggested following the identification of AQP4 autoantibodies in neuromyelitis optica, an inflammatory demyelinating disease.

Results

We investigated the involvement of AQP4 in disease severity in an established mouse model of experimental autoimmune encephalomyelitis (EAE) produced by immunization with myelin oligodendrocyte glycoprotein (MOG_35–55) peptide. EAE was remarkably attenuated in AQP4 null mice compared to identically treated wildtype mice. Whereas most wildtype mice developed progressive tail and hindlimb paralysis, clinical signs were virtually absent in AQP4 null mice. Brain and spinal cords from AQP1 null mice showed greatly reduced mononuclear cell infiltration compared to wildtype mice, with relatively little myelin loss and axonal degeneration.

Conclusion

The reduced severity of autoimmune encephalomyelitis in AQP4 deficiency suggests AQP4 as a novel determinant in autoimmune inflammatory diseases of the central nervous system and hence a potential drug target.

Prospects of cell therapy for disorders of myelin

Recent advances in stem cell biology have raised expectations that both diseases of, and injuries to, the central nervous system may be ameliorated by cell transplantation. In particular, cell therapy has been studied for inducing efficient remyelination in disorders of myelin, including both the largely pediatric disorders of myelin formation and maintenance and the acquired demyelinations of both children and adults. Potential cell-based treatments of two major groups of disorders include both delivery of myelinogenic replacements and mobilization of residual oligodendrocyte progenitor cells as a means of stimulating endogenous repair; the choice of modality is then predicated upon the disease target. In this review we consider the potential application of cell-based therapeutic strategies to disorders of myelin, highlighting the promises as well as the problems and potential perils of this treatment approach.

Transplantation of bone marrow transduced to express self-antigen establishes deletional tolerance and permanently remits autoimmune disease

Autoimmune diseases are incurable. We have hypothesized that these diseases can be cured by the transplantation of bone marrow (BM) stem cells that have been genetically engineered to express self-Ag. Here we have tested this hypothesis in experimental autoimmune encephalomyelitis (EAE) induced by the self-Ag myelin oligodendrocyte glycoprotein (MOG). We show that, in mice, transplantation of BM genetically modified to express MOG prevented the induction and progression of EAE, and combined with antecedent corticosteroid treatment, induced long-term remission of established disease. Mice remained resistant to EAE development upon subsequent rechallenge with MOG. Transfer of BM from these mice rendered recipients resistant to EAE. Splenocytes from these mice failed to proliferate or produce IL-17, IFN-gamma, and GM-CSF in response to MOG(35-55) peptide stimulation and they failed to produce MOG autoantibody. Mechanistically, we demonstrated in vivo reduction in development of CD4(+) MOG(35-55)-specific thymocytes, indicative of clonal deletion with no evidence for selection of Ag-specific regulatory T cells. These findings validate our hypothesis that transplantation of genetically modified BM expressing disease-causative self-Ag provides a curative approach by clonal deletion of disease-causative self-reactive T cells.