T cell and antibody responses in remitting–relapsing experimental autoimmune encephalomyelitis in (C57BL/6×SJL) F1 mice

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.

Comprehensive Analysis of the Immune and Stromal Compartments of the CNS in EAE Mice Reveal Pathways by Which Chloroquine Suppresses Neuroinflammation

Multiple sclerosis (MS) and experimental autoimmune encephalomyelitis (EAE) are neuroinflammatory diseases of the central nervous system (CNS), where leukocytes and CNS resident cells play important roles in disease development and pathogenesis. The antimalarial drug chloroquine (CQ) has been shown to suppress EAE by modulating dendritic cells (DCs) and Th17 cells. However, the mechanism of action by which CQ modulates EAE is far from being elucidated. Here, we comprehensively analyzed the CNS of CQ and PBS-treated EAE mice to identify and characterize the cells that are affected by CQ. Our results show that leukocytes are largely modulated by CQ and have a reduction in the expression of inflammatory markers. Intriguingly, CQ vastly modulated the CNS resident cells astrocytes, oligodendrocytes (OLs) and microglia (MG), with the latter producing IL-10 and IL-12p70. Overall, our results show a panoramic view of the cellular components that are affect by CQ and provide further evidence that drug repurposing of CQ will be beneficial to MS patients.

Regulatory T Cell Dysfunction Acquiesces to BTLA+ Regulatory B Cells Subsequent to Oral Intervention in Experimental Autoimmune Encephalomyelitis

Regulatory T cells (Tregs) induced during autoimmunity often become quiescent and unable to resolve disease, suggesting inadequate activation. Resolution of established experimental autoimmune encephalomyelitis (EAE) can be achieved with myelin oligodendrocyte glycoprotein (MOG) fused to reovirus protein σ1 (MOG-pσ1), which activates Tregs, restoring protection, but requiring other regulatory cells to revitalize them. B cells have a dichotomous role in both the pathogenesis and recovery from EAE. Although inflammatory B cells contribute to EAE's pathogenesis, treatment of EAE mice with MOG-pσ1, but not OVA-pσ1, resulted in an influx of IL-10-producing B220(+)CD5(+) B regulatory cells (Bregs) enabling Tregs to recover their inhibitory activity, and in turn, leading to the rapid amelioration of EAE. These findings implicate direct interactions between Bregs and Tregs to facilitate this recovery. Adoptive transfer of B220(+)CD5(-) B cells from MOG-pσ1-treated EAE or Bregs from PBS-treated EAE mice did not resolve disease, whereas the adoptive transfer of MOG-pσ1-induced B220(+)CD5(+) Bregs greatly ameliorated EAE. MOG-pσ1-, but not OVA-pσ1-induced IL-10-producing Bregs, expressed elevated levels of B and T lymphocyte attenuator (BTLA) relative to CD5(-) B cells, as opposed to Tregs or effector T (Teff) cells, whose BTLA expression was not affected. These induced Bregs restored EAE Treg function in a BTLA-dependent manner. BTLA(-/-) mice showed more pronounced EAE with fewer Tregs, but upon adoptive transfer of MOG-pσ1-induced BTLA(+) Bregs, BTLA(-/-) mice were protected against EAE. Hence, this evidence shows the importance of BTLA in activating Tregs to facilitate recovery from EAE.

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.

Defining a new biomarker for the autoimmune component of Multiple Sclerosis: Th40 cells

Multiple Sclerosis (MS) is a chronic inflammatory, neurodegenerative disease. Diagnosis is very difficult requiring defined symptoms and multiple CNS imaging. A complicating issue is that almost all symptoms are not disease specific for MS. Autoimmunity is evident, yet the only immune-related diagnostic tool is cerebral-spinal fluid examination for oligoclonal bands. This study addresses the impact of Th40 cells, a pathogenic effector subset of helper T cells, in MS. MS patients including relapsing/remitting MS, secondary progressive MS and primary progressive MS were examined for Th40 cell levels in peripheral blood and, similar to our findings in autoimmune type 1 diabetes, the levels were significantly (p<0.0001) elevated compared to controls including healthy non-autoimmune subjects and another non-autoimmune chronic disease. Classically identified Tregs were at levels equivalent to non-autoimmune controls but the Th40/Treg ratio still predicted autoimmunity. The cohort displayed a wide range of HLA haplotypes including the GWAS identified predictive HLA-DRB1*1501 (DR2). However half the subjects did not carry DR2 and regardless of HLA haplotype, Th40 cells were expanded during disease. In RRMS Th40 cells demonstrated a limited TCR clonality. Mechanistically, Th40 cells demonstrated a wide array of response to CNS associated self-antigens that was dependent upon HLA haplotype. Th40 cells were predominantly memory phenotype producing IL-17 and IFNγ with a significant portion producing both inflammatory cytokines simultaneously suggesting an intermediary between Th1 and Th17 phenotypes.

Effects of peptide fraction and counter ion on the development of clinical signs in experimental autoimmune encephalomyelitis

The most commonly used immunogen to induce experimental autoimmune encephalomyelitis is MOG35-55 , a 21-residue peptide derived from myelin oligodendrocyte glycoprotein (MOG). In most studies, mice exhibit a chronic disease; however, in some studies mice show a transient disease. One variable that is not often controlled for is the peptide fraction of the purified MOG material, which can vary from less than 50% to over 90%, with the remainder of mass primarily comprised of the counter ion used for peptide purification. We compared the development of clinical signs in female C57Bl6 mice immunized with two commercially available MOG35-55 peptides of similar purity but different peptide fraction (MOG-A being 45%; MOG-B being 72%). A single immunization with MOG-A induced a chronic disease course with some recovery at later stages, whereas immunization with MOG-B induced a similar course of disease but with significantly lower average clinical scores despite a higher peptide content. The addition of a booster immunization significantly increased clinical severity with both preparations, and significantly reduced the average day of onset using MOG-A. To determine if the counter ion could influence disease, we compared MOG-B-containing trifluoroacetate with MOG-B-containing acetate. Although disease incidence and severity were similar, the average day of disease onset occurred approximately 5 days earlier with the use of MOG-B-containing trifluoroacetate. These results demonstrate that differences in peptide fraction influence the course of encephalomyelitis disease, which may be due in part to the levels of counter ions present in the purified material. These findings underscore the fact that a knowledge of peptide fraction is as critical as knowledge of peptide purity when using peptides from different sources.

In trans T cell tolerance exacerbates experimental allergic encephalomyelitis by interfering with protective antibody responses

F1 (SJL/J×C57BL/6) mice with MOG35-55-induced EAE recover from disease when treated with Ig-MOG carrying MOG35-55 peptide. However, Ig-PLP1, carrying PLP139-151, induced reduction of anti-MOG antibodies and exacerbated EAE. Herein, we show that Ig-PLP1 specifically reduces the frequency of B cells producing protective IgG2a/b anti-MOG antibodies. Surprisingly, these cells were marginal zone (MZ), rather than follicular (FO) or newly formed (NF), B cells and transfer of MZ B cells into sick mice nullified disease exacerbation by Ig-PLP1 in a complement dependent manner. These findings reveal a potential self-limiting regulatory mechanism involving auto-antibodies in MOG EAE.

Targeting T cells responsive to the priming epitope prevent the relapsing phase of experimental autoimmune encephalomyelitis

Upon recovery from the initial episode of experimental autoimmune encephalomyelitis (EAE), virtually all SJL mice develop relapsing/remitting episodes of disease. These relapses may occur due to the reactivation of memory T cells initially stimulated as part of the disease-inducing protocol or naïve T-cell populations stimulated by distinct encephalitogens derived from the inflammatory disease process (epitope spread). We have used encephalitogen-specific non-linear peptide octamers to modify the course of relapsing EAE (rEAE) in SJL mice immunized with an oliogodendrocyte-specific protein peptide (OSP 55-71). Our studies show that the peptide-octamers, which target the T cells stimulated by the priming encephalitogen, but not other candidate encephalitogens, prevent rEAE.

IgG glycan hydrolysis by EndoS inhibits experimental autoimmune encephalomyelitis

Studies in experimental autoimmune encephalomyelitis (EAE), a mouse model of multiple sclerosis, have shown that B cells markedly influence the course of the disease, although whether their effects are protective or pathological is a matter of debate. EndoS hydrolysis of the IgG glycan has profound effects on IgG effector functions, such as complement activation and Fc receptor binding, suggesting that the enzyme could be used as an immunomodulatory therapeutic agent against IgG-mediated diseases. We demonstrate here that EndoS has a protective effect in myelin oligodendrocyte glycoprotein peptide amino acid 35–55 (MOG_35-55)-induced EAE, a chronic neuroinflammatory demyelinating disorder of the central nervous system (CNS) in which humoral immune responses are thought to play only a minor role. EndoS treatment in chronic MOG_35-55-EAE did not impair encephalitogenic T cell priming and recruitment into the CNS of mice, consistent with a primary role of EndoS in controlling IgG effector functions. In contrast, reduced EAE severity coincided with poor serum complement activation and deposition within the spinal cord, suggesting that EndoS treatment impairs B cell effector function. These results identify EndoS as a potential therapeutic agent against antibody-mediated CNS autoimmune disorders.

Tissue concentration changes of amino acids and biogenic amines in the central nervous system of mice with experimental autoimmune encephalomyelitis (EAE)

We have characterized the changes in tissue concentrations of amino acids and biogenic amines in the central nervous system (CNS) of mice with MOG(35-55)-induced experimental autoimmune encephalomyelitis (EAE), an animal model commonly used to study multiple sclerosis (MS). High performance liquid chromatography was used to analyse tissue samples from five regions of the CNS at the onset, peak and chronic phase of MOG(35-55) EAE. Our analysis includes the evaluation of several newly examined amino acids including d-serine, and the inter-relations between the intraspinal concentration changes of different amino acids and biogenic amines during EAE. Our results confirm many of the findings from similar studies using different variants of the EAE model as well as those examining changes in amino acid and biogenic amine levels in the cerebrospinal fluid (CSF) of MS patients. However, several notable differences were observed between mice with MOG(35-55)-induced EAE with findings from human studies and other EAE models. In addition, our analysis has identified strong correlations between different amino acids and biogenic amines that appear to change in two distinct groups during EAE. Group I analyte concentrations are increased at EAE onset and peak but then decrease in the chronic phase with a large degree of variability. Group II is composed of amino acids and biogenic amines that change in a progressive manner during EAE. The altered levels of these amino acids and biogenic amines in the disease may represent a critical pathway leading to neurodegenerative processes that are now recognized to occur in EAE and MS.

IDO upregulates regulatory T cells via tryptophan catabolite and suppresses encephalitogenic T cell responses in experimental autoimmune encephalomyelitis

Experimental autoimmune encephalomyelitis (EAE) is a Th1 and Th17 cell-mediated autoimmune disease of the CNS. IDO and tryptophan metabolites have inhibitory effects on Th1 cells in EAE. For Th17 cells, IDO-mediated tryptophan deprivation and small molecule halofuginone-induced amino acid starvation response were shown to activate general control nonrepressed 2 (GCN2) kinase that directly or indirectly inhibits Th17 cell differentiation. However, it remains unclear whether IDO and tryptophan metabolites impact the Th17 cell response by mechanisms other than the GCN2 kinase pathway. In this article, we show that IDO-deficient mice develop exacerbated EAE with enhanced encephalitogenic Th1 and Th17 cell responses and reduced regulatory T cell (Treg) responses. Administration of the downstream tryptophan metabolite 3-hydroxyanthranillic acid (3-HAA) enhanced the percentage of Tregs, inhibited Th1 and Th17 cells, and ameliorated EAE. We further demonstrate that Th17 cells are less sensitive to direct suppression by 3-HAA than are Th1 cells. 3-HAA treatment in vitro reduced IL-6 production by activated spleen cells and increased expression of TGF-β in dendritic cells (DCs), which correlated with enhanced levels of Tregs, suggesting that 3-HAA-induced Tregs contribute to inhibition of Th17 cells. By using a DC-T cell coculture, we found that 3-HAA-treated DCs expressed higher levels of TGF-β and had properties to induce generation of Tregs from anti-CD3/anti-CD28-stimulated naive CD4(+) T cells. Thus, our data support the hypothesis that IDO induces the generation of Tregs via tryptophan metabolites, such as 3-HAA, which enhances TGF-β expression from DCs and promotes Treg differentiation.

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.

Autoimmune-induced preferential depletion of myelin-associated glycoprotein (MAG) is genetically regulated in relapsing EAE (B6 x SJL) F1 mice

Background

Experimental autoimmune encephalomyelitis (EAE) is commonly used to investigate mechanisms of autoimmune-mediated damage to oligodendrocytes, myelin, and axons in multiple sclerosis (MS). Four distinct autoimmune mechanisms with subsequently distinct patterns of demyelination have been recognized in acute MS lesions. EAE correlates for those distinct patterns of MS lesions are unknown. An excessive loss of myelin-associated glycoprotein (MAG), as a result of distal oligodendrogliopathy, is found exclusively in the subtype III lesion. We sought to answer if types of demyelination in acute lesions during onset and relapse of EAE can replicate the specific patterns observed in MS acute lesions.

Methods

In parental H-2^b (C57BL/6, B6) and hybrid H-2^b/s [(B6 × SJL) F1] EAE mice, we examined spinal cord levels of MOG, MAG, and myelin basic protein (MBP), and compared to levels of axonal neurofilament (NF160) to assess axonal function, and levels of PARPp85 as an indicator of irreversible apoptosis.

Results

During disease onset, levels of MOG significantly dropped in both strains, although more profoundly in H-2^b/s mice. Levels of MOG recovered in relapsing mice of both strains. Regulation of MAG was dissimilar to MOG. Modest loss of MAG was found at disease onset in both strains of mice. Unexpectedly, in relapsing H-2^b/s mice, a major depletion of MAG and NF160, accompanied with sharp elevation of PARPp85 levels, was measured. PARPp85 immunoreactivity was observed in cytoplasm and nuclei of some MBP containing cells.

Conclusion

Taken together, our results show genetically controlled distinct patterns of MOG and MAG depletion, in MOG_35–55 induced EAE in H-2^b and H-2^b/s mice. The data also suggest distinctive immune regulation of acute lesions that develop in relapsing compared to disease onset. A profound depletion of MAG, concomitant with marked depletion of axonal NF160, and sharp elevation of PARPp85 levels, occurred exclusively in relapsing H-2^b/s mice. Our findings suggest concurrence of sharp decrease of MAG levels, axonal dysfunction and irreversible apoptosis with severe relapsing disease in H-2^b/s mice. We propose that MOG-induced EAE in H-2^b/s mice may prove as a useful model in studying mechanisms, which govern autoimmune-induced preferential loss of MAG, and its impact on oligodendroglial pathology.

Allogeneic bone marrow transplantation in models of experimental autoimmune encephalomyelitis: evidence for a graft-versus-autoimmunity effect

Autologous hematopoietic stem cell transplantation (HSCT) is being explored in the treatment of severe multiple sclerosis (MS), and is based on the concept of "resetting" the immune system. The use of allogeneic HSCT may offer additional advantages, such as the replacement of the autoreactive immune compartment by healthy allogeneic cells and development of a graft-versus-autoimmunity (GVA) effect. However, in clinical practice, the genetic susceptibility to MS of allogeneic stem cell donors is generally unknown, and GVA may therefore be an important mechanism of action. Experimental autoimmune encephalomyelitis (EAE)-susceptible and -resistant mouse strains were used to determine the roles of genetic susceptibility, level of donor-chimerism, and alloreactivity in the therapeutic potential of syngeneic versus allogeneic bone marrow transplant (BMT) for EAE. After transplantation and EAE induction, animals were evaluated for clinical EAE and ex vivo myelin oligodendrocyte glycoprotein-specific proliferation. Early after BMT, both syngeneic and allogeneic chimeras were protected from EAE development. On the longer term, allogeneic but not syngeneic BMT conferred protection, but this required high-level donor-chimerism from EAE-resistant donors. Importantly, when EAE-susceptible donors were used, robust protection from EAE was obtained when active alloreactivity, induced by donor lymphocyte infusions, was provided. Our findings indicate the requirement of a sufficient level of donor-chimerism from a nonsusceptible donor in the therapeutic effect of allogeneic BMT. Importantly, the data indicate that, independently of genetic susceptibility, active alloreactivity is associated with a GVA effect, thereby providing new evidence to support the potential role of allogeneic BMT in the treatment of MS.

A model of experimental autoimmune encephalomyelitis (EAE) in C57BL/6 mice for the characterisation of intervention therapies

Multiple sclerosis (MS) and its different forms are studied in the animal model experimental autoimmune encephalomyelitis (EAE). Relapsing-remitting MS, the most common form of the disease can be induced in mice where clinical symptoms fluctuate in severity over time. However, the animal model does not experience periods of recovery where clinical signs are absent, unlike the human disease. We have developed a novel model of relapsing-remitting EAE in C57BL/6 mice immunised with myelin oligodendrocyte glycoprotein (MOG) peptide and Quil A as adjuvant. These animals have relapses that are followed by periods of recovery, during which time the animals do not exhibit illness. Furthermore, administration of the PPARgamma agonist pioglitazone prior to a predicted relapse prevents the expected development of symptoms in a dose-dependent fashion. Immune cell infiltration into white matter of the CNS and decreased production of inflammatory cytokine IFN-gamma in treated animals were also observed. Our model will be a valuable tool in assessing intervention therapies for RR-MS sufferers.

Neural precursors attenuate autoimmune encephalomyelitis by peripheral immunosuppression

OBJECTIVE

Intracerebroventricular or intravenous (IV) injection of neural precursor cells (NPCs) attenuates experimental autoimmune encephalomyelitis (EAE), the animal model of multiple sclerosis. Although stem cell therapy was introduced initially for cell replacement, we examine here whether NPCs possess immunomodulatory effects.

METHODS

We examined the effects of systemic administration of NPCs on central nervous system (CNS) inflammation in EAE and the interactions between NPCs and T cells in vitro and in vivo.

RESULTS

IV NPC therapy decreased significantly CNS inflammation and tissue injury and attenuated the clinical severity of EAE. IV-injected NPCs could not be found in the CNS but were detected in lymphoid organs. Coculture experiments showed that NPCs inhibited the activation and proliferation of lymph node-derived T cells in response to CNS-derived antigens and to nonspecific polyclonal stimuli. The relevance of NPC/lymph node cell interactions in vivo was further demonstrated when lymph node cells obtained from IV NPC-treated mice exhibited poor encephalitogenicity on transfer to naive mice and caused a markedly milder EAE compared with those obtained from nontreated mice.

INTERPRETATION

IV administration of neural precursors inhibits EAE by a peripheral immunosuppressive effect. Our findings suggest a profound bystander inhibitory effect of NPCs on T-cell activation and proliferation in the lymph nodes, leading to amelioration of EAE.

In vivo administration of plasmid DNA encoding recombinant immunotoxin DT390-IP-10 attenuates experimental autoimmune encephalomyelitis

Experimental autoimmune encephalomyelitis (EAE) is a T-cell-mediated autoimmune demyelinating disease. The expression of chemokine receptor CXCR3 on activated T cells is crucial to direct the migration of effector cells into the inflammatory sites and initiate EAE. In this study we tested the effect of a novel recombinant immunotoxin targeting CXCR3(+) cells for EAE prevention. The immunotoxin construct DT390-IP-10-SRalpha consisted of interferon gamma-inducible protein 10 (IP-10), a ligand of CXCR3, as the targeting moiety, and a truncated diphtheria toxin (DT390) as the toxic moiety. In vitro transfection of DT390-IP-10-SRalpha into NIH3T3 cells resulted in expression of DT390-IP-10 which proved highly toxic to activated T cells. To evaluate the effect of DT390-IP-10-SRalpha on EAE prevention in vivo, cationic liposome-embedded DT390-IP-10-SRalpha was injected into the muscle of hind limbs of C57BL/6 mice immunized by myelin basic protein (MBP). DT390-IP-10-SRalpha-treated mice showed a delayed onset of EAE and milder symptoms compared to the mice treated with empty control plasmid or PBS alone. Immunohistochemical staining detected significantly reduced infiltrating CXCR3(+) cells in the inflammatory lesions of CNS from immunotoxin treated mice as compared to the controls. This study suggests that targeting CXCR3(+) T cells with recombinant immunotoxin could be achieved in vivo to delay and ameliorate murine EAE.

Diversified serum IgG response involving non-myelin CNS proteins during experimental autoimmune encephalomyelitis

We sequentially analyzed the serum IgG response against normal mouse brain during experimental autoimmune encephalomyelitis in SJL/J mice injected with CFA, Bordetella pertussis toxin (BPT) and proteolipid protein 139-151 peptide, compared with mice that received CFA and BPT or were uninjected. Dynamic changes were observed from day 0 to day 28 in the 3 groups. Six highly discriminant antigenic bands (kappa=0.974) were identified. Three non-myelin proteins were characterized (mitochondrial aconitase hydratase 2, phosphoglycerate mutase 1, brain specific pyruvate deshydrogenase). The IgG response against two of them was less frequent in EAE whereas it was associated with multiple sclerosis in our previous work.

Identification and Functional Validation of Novel Autoantigens in Equine Uveitis

The development, progression, and recurrence of autoimmune diseases are frequently driven by a group of participatory autoantigens. We identified and characterized novel autoantigens by analyzing the autoantibody binding pattern from horses affected by spontaneous equine recurrent uveitis to the retinal proteome. Cellular retinaldehyde-binding protein (cRALBP) had not been described previously as autoantigen, but subsequent characterization in equine recurrent uveitis horses revealed B and T cell autoreactivity to this protein and established a link to epitope spreading. We further immunized healthy rats and horses with cRALBP and observed uveitis in both species with typical tissue lesions at cRALBP expression sites. The autoantibody profiling outlined here could be used in various autoimmune diseases to detect autoantigens involved in the dynamic spreading cascade or serve as predictive markers.

Deficient p75 low-affinity neurotrophin receptor expression does alter the composition of cellular infiltrate in experimental autoimmune encephalomyelitis in C57BL/6 mice

We have shown earlier that induction of experimental autoimmune encephalomyelitis (EAE)-a model for the human disease multiple sclerosis-in C57BL/6 wild-type mice resulted in the expression of the p75 low-affinity neurotrophin receptor (p75NTR) in endothelial cells in the CNS. In comparison to the clinical manifestation of EAE observed in wild-type C57BL/6 mice, C57BL/6 mice deficient for p75NTR (p75NTR knockout mice) developed a more severe or even lethal disease and concomitant increased levels of inflammation in the CNS. In order to elucidate the role of endothelial p75NTR in cellular infiltration under these pathological circumstances, we have performed a more detailed, quantitative examination of the composition of the cellular infiltrate invading the CNS in EAE wild-type and EAE p75NTR knockout mice. We compared spinal cords of EAE wild-type with those of EAE p75NTR knockout mice of the same clinical score (3.5) using immunohistochemical markers for the cell types present in the infiltratory cuffs in EAE: T-cells, B-cells, monocytes, microglia, resident and infiltrating macrophages and polymorphonuclear cells. Interestingly, we detected that the proportion of B-cells, cells of the monocyte-macrophage lineage and polymorphonuclear cells in the infiltratory cuff of EAE-p75NTR knockout mice was decreased at the account of the proportion of T-cells which appeared to be almost doubled in comparison to the EAE wild-type mice. The altered composition of the infiltrate in p75NTR deficient mice argues for an involvement of endothelial p75NTR in the interaction between the inflamed endothelium and the activated cells of the immune system, in particular the T-cells, in EAE.