The human CMV-UL86 peptide 981–1003 shares a crossreactive T-cell epitope with the encephalitogenic MOG peptide 34–56, but lacks the capacity to induce EAE in rhesus monkeys

Complete Freund's adjuvant as a confounding factor in multiple sclerosis research

Complete Freund's adjuvant (CFA) is used as a standard adjuvant for the induction of experimental autoimmune encephalomyelitis (EAE), the most commonly used animal model in multiple sclerosis studies. Still, CFA induces glial activation and neuroinflammation on its own and provokes pain. In addition, as CFA contains Mycobacteria, an immune response against bacterial antigens is induced in parallel to the response against central nervous system antigens. Thus, CFA can be considered as a confounding factor in multiple sclerosis-related studies performed on EAE. Here, we discuss the effects of CFA in EAE in detail and present EAE variants induced in experimental animals without the use of CFA. We put forward CFA-free EAE variants as valuable tools for studying multiple sclerosis pathogenesis and therapeutic approaches.

Infections and schizophrenia

This paper provides a critical review of the literature, demonstrating a certain pathogenetic role of various infections, primarily viruses from the herpes and chlamydia groups, in the development and progression of schizophrenia, including published results of the authors’ own long-term studies.

A plausible contributor to multiple sclerosis; presentation of antigenic myelin protein epitopes by major histocompatibility complexes

BACKGROUND

Multiple sclerosis (MS) can be induced upon successful presentation of myelin antigens by MHC I/II. Antigenic similarity between the myelin and viral proteins may worsen the immunological responses.

METHODOLOGY

Antigenic regions within myelin proteins; PLP1, MBP, MOG, and MAG were analyzed using SVMTrip and EMBOSS. Homology search identified sequence similarity between the predicted host epitopes and viral proteins. NetMHCpan predicted MHC I/II binding followed by peptide-protein docking through the HPEPDOCK server. Thereafter we analyzed conformational flexibility and stability of 15 protein-peptide complexes based on high docking scores. The binding free energy was calculated using conventional (MD) and Gaussian accelerated molecular dynamics simulation.

RESULTS

PLP1, MBP, MAG and MOG contained numerous antigenic epitopes. MBP and MOG epitopes had sequence similarity to HHV-6 BALF5; EBNA1 and CMV glycoprotein M (gM), and EBV LMP2B, gp350/220; HHV-8 ORFs respectively. Many herpes virus proteins like tegument, envelope glycoproteins, and ORFs of EBV, CMV, HHV-6, and HHV-8 demonstrated sequence similarity with MAG and PLP1. Some antigenic peptides were also linear B-cell epitopes and influenced cytokine production by T-cell. MHC I allele HLA-B*57:01 bound to PLP1 peptide and HLA-A*68:02 bound to a MAG peptide strongly. MHC II alleles HLA-DRB1*04:05 and HLA-DR1*01:01 associated with MAG- and MOG-derived peptides, respectively, demonstrating high HPEPDOCK scores. MD simulations established stable binding of certain peptides with the MHC namely HLA-B*51:01-MBP(DYKSAHKGFKGVDAQGTLSKIFKL), HLA-B*57:01-PLP1(PDKFVGITYALTVVWLLVFACSAVPVYIYF), HLA-DR1*01:01-MOG(VEDPFYWVSPGVLVLLAVLPVLLLQITVGLVFLCLQYR) and HLA-DRB1*04:05-MAG(TWVQVSLLHFVPTREA).

CONCLUSIONS

Cross-reactivity between self-antigens and pathogen derived immunodominant epitopes may induce MS. Our study supported the role of specific MHC alleles as a contributing MS risk factor.

Guillain-Barré syndrome: expanding the concept of molecular mimicry

Guillain-Barré syndrome (GBS) is a rapidly progressive, monophasic, and potentially devastating immune-mediated neuropathy in humans. Preceding infections trigger the production of cross-reactive antibodies against gangliosides concentrated in human peripheral nerves. GBS is elicited by at least five distinct common bacterial and viral pathogens, speaking to the notion of polymicrobial disease causation. This opinion emphasizes that GBS is the best-supported example of true molecular mimicry at the B cell level. Moreover, we argue that mechanistically, single and multiplexed microbial carbohydrate epitopes induce IgM, IgA, and IgG subclasses in ways that challenge the classic concept of thymus-dependent (TD) versus thymus-independent (TI) antibody responses in GBS. Finally, we discuss how GBS can be exemplary for driving innovation in diagnostics and immunotherapy for other antibody-driven neurological diseases.

Extensive longitudinal myelitis due to cytomegalovirus infection

Neurological cytomegalovirus (CMV) infections especially extensive longitudinal myelitis are extremely rare in immunocompetent adults. However, we hereby report a case of cervical, thoracic, and lumbosacral myelitis caused by CMV infection in a healthy adult patient. The patient was treated properly and had a good outcome. The etiopathogenesis and the prognostic factors for this affection are not well established and are still being debated by authors. Further clinical data would contribute to a better understanding of this pathology in order to provide a better prognosis.

Mechanistic underpinning of an inside-out concept for autoimmunity in multiple sclerosis

The neuroinflammatory disease multiple sclerosis is driven by autoimmune pathology in the central nervous system. However, the trigger of the autoimmune pathogenic process is unknown. MS models in immunologically naïve, specific‐pathogen‐free bred rodents support an exogenous trigger, such as an infection. The validity of this outside–in pathogenic concept for MS has been frequently challenged by the difficulty to translate pathogenic concepts developed in these models into effective therapies for the MS patient. Studies in well‐validated non‐human primate multiple sclerosis models where, just like in humans, the autoimmune pathogenic process develops from an experienced immune system trained by prior infections, rather support an endogenous trigger. Data reviewed here corroborate the validity of this inside–out pathogenic concept for multiple sclerosis. They also provide a plausible sequence of events reminiscent of Wilkin’s primary lesion theory: (i) that autoimmunity is a physiological response of the immune system against excess antigen turnover in diseased tissue (the primary lesion) and (ii) that individuals developing autoimmune disease are (genetically predisposed) high responders against critical antigens. Data obtained in multiple sclerosis brains reveal the presence in normally appearing white matter of myelinated axons where myelin sheaths have locally dissociated from their enwrapped axon (i.e., blistering). The ensuing disintegration of axon–myelin units potentially causes the excess systemic release of post‐translationally modified myelin. Data obtained in a unique primate multiple sclerosis model revealed a core pathogenic role of T cells present in the normal repertoire, which hyper‐react to post‐translationally modified (citrullinated) myelin–oligodendrocyte glycoprotein and evoke clinical and pathological aspects of multiple sclerosis.

Herpesviruses and the hidden links to Multiple Sclerosis neuropathology

Herpesviruses like Epstein-Barr virus, human herpesvirus (HHV)-6, HHV-1, VZV, and human endogenous retroviruses, have an age-old clinical association with multiple sclerosis (MS). MS is an autoimmune disease of the nervous system wherein the myelin sheath deteriorates. The most popular mode of virus mediated immune system manipulation is molecular mimicry. Numerous herpesvirus antigens are similar to myelin proteins. Other mechanisms described here include the activity of cytokines and autoantibodies produced by the autoreactive T and B cells, respectively, viral déjà vu, epitope spreading, CD46 receptor engagement, impaired remyelination etc. Overall, this review addresses the host-parasite association of viruses with MS.

Guillain-Barré syndrome after adoptive cell therapy with tumor-infiltrating lymphocytes

BACKGROUND

Adoptive cell therapy (ACT) using tumor-infiltrating lymphocytes (TILs) is a promising experimental immunotherapy that has shown high objective responses in patients with melanoma. Current protocols use a lymphodepletive chemotherapy before infusion of ex vivo expanded TILs, followed by high-dose interleukin-2 (IL-2). Treatment-related toxicities are mainly attributable to the chemotherapy regimen and to the high-dose IL-2 and are generally reversible. Neurological side effects have rarely been described. Nevertheless, due to improvements in cell production techniques and due to combinations with other immunomodulating molecules, side effects not previously described may be encountered.

CASE PRESENTATION

We report the case of a 53-year-old heavily pretreated patient with melanoma who developed Guillain-Barré syndrome (GBS) 19 days after ACT using autologous TILs, given in the context of a phase I trial. He presented with dorsal back pain, unsteady gait and numbness in hands and feet. Lumbar puncture showed albuminocytological dissociation, and nerve conduction studies revealed prolonged distal motor latencies in median, ulnar, tibial and peroneal nerves, compatible with a GBS. The patient was treated with intravenous immunoglobulins and intensive neurological rehabilitation, with progressive and full recovery at 21 months post-TIL-ACT. Concomitant to the onset of GBS, a cytomegalovirus reactivation on immunosuppression was detected and considered as the most plausible cause of this neurological side effect.

CONCLUSION

We describe for the first time a case of GBS occurring shortly after TIL-ACT for melanoma, even though we could not identify with certainty the triggering agent. The report of such rare cases is of extreme importance to build on the knowledge of immune cellular therapies and their specific spectrum of toxicities.

Seroprevalence of human cytomegalovirus among pregnant women who had undergone abortion(s) attending El-Damazin Hospital for Obstetrics and Gynecology, Sudan: A cross-sectional study

Background: Human cytomegalovirus (HCMV) is a major cause of congenital infections. It is more widespread in developing countries and communities with low socioeconomic status. The infection can cause pregnancy loss or spontaneous abortion. Tests are available for the detection of HCMV IgG and IgM antibodies. Many pregnant women in Blue Nile State, Sudan, have suffered from recurrent pregnancy loss, and currently there is no available data concerning the prevalence of HCMV in Blue Nile state. This study aimed to determine HCMV antibodies (IgG and IgM) among pregnant women, who had undergone abortion(s), attending El-Damazin Hospital for Obstetrics and Gynecology.   Methods: This was a descriptive, cross-sectional hospital-based study. 270 pregnant women, who had undergone abortion(s) and who attended El-Damazin Hospital for Obstetrics and Gynecology, were included in the study from September to December 2018. Personal and clinical data were collected directly from each participant into a predesigned questionnaire. Serum samples were separated and stored at -20˚C until used. Samples were analyzed for HCMV IgG and IgM using enzyme-linked immune-sorbent assay (ELISA). Results: Participants were categorized into three age groups: 15-25 years (33.7%; 91/270); 26-40 years (62.2%; 168/270); and >41 years (4.1%; 11/270). The majority of the participants had IgG antibodies to HCMV (74.8%; 202/270), while only 13.3% (36/270) had IgM antibodies to HCMV. Most abortion cases were documented in the first trimester (85.6%; 231/270) and this had a significant relationship with IgG level (P=0.003). Low socioeconomic status was recorded in 84.8% (229/270) of participants and showed significant correlation with IgG level (P=0.025), whereas illiteracy was reported in 41.9% (113/270) of participants and did not have a significant relationship.   Conclusions: Seroprevalence of HCMV in this study population was 74.8% for IgG antibodies. There was an association between HCMV IgG level and first trimester abortion and low socioeconomic status among the studied women.

Experimental autoimmune encephalomyelitis in the common marmoset: a translationally relevant model for the cause and course of multiple sclerosis

Aging Western societies are facing an increasing prevalence of chronic autoimmune-mediated inflammatory disorders (AIMIDs) for which treatments that are safe and effective are scarce. One of the main reasons for this situation is the lack of animal models, which accurately replicate clinical and pathological aspects of the human diseases. One important AIMID is the neuroinflammatory disease multiple sclerosis (MS), for which the mouse experimental autoimmune encephalomyelitis (EAE) model has been frequently used in preclinical research. Despite some successes, there is a long list of experimental treatments that have failed to reproduce promising effects observed in murine EAE models when they were tested in the clinic. This frustrating situation indicates a wide validity gap between mouse EAE and MS. This monography describes the development of an EAE model in nonhuman primates, which may help to bridge the gap.

CD28 null CD4 T-cell expansions in autoimmune disease suggest a link with cytomegalovirus infection

Immunosenescence is thought to contribute to the increase of autoimmune diseases in older people. Immunosenescence is often associated with the presence of an expanded population of CD4 T cells lacking expression of CD28 (CD28 ^null). These highly cytotoxic CD4 T cells were isolated from disease-affected tissues in patients with rheumatoid arthritis, systemic lupus erythematosus, multiple sclerosis, or other chronic inflammatory diseases and their numbers appeared to be linked to disease severity. However, we recently demonstrated that the common herpes virus, cytomegalovirus (CMV), not ageing, is the major driver of this subset of cytotoxic T cells. In this review, we discuss how CMV might potentiate and exacerbate autoimmune disease through the expansion of CD28 ^null CD4 T cells.

A B Cell-Driven Autoimmune Pathway Leading to Pathological Hallmarks of Progressive Multiple Sclerosis in the Marmoset Experimental Autoimmune Encephalomyelitis Model

The absence of pathological hallmarks of progressive multiple sclerosis (MS) in commonly used rodent models of experimental autoimmune encephalomyelitis (EAE) hinders the development of adequate treatments for progressive disease. Work reviewed here shows that such hallmarks are present in the EAE model in marmoset monkeys (Callithrix jacchus). The minimal requirement for induction of progressive MS pathology is immunization with a synthetic peptide representing residues 34–56 from human myelin oligodendrocyte glycoprotein (MOG) formulated with a mineral oil [incomplete Freund’s adjuvant (IFA)]. Pathological aspects include demyelination of cortical gray matter with microglia activation, oxidative stress, and redistribution of iron. When the peptide is formulated in complete Freund’s adjuvant, which contains mycobacteria that relay strong activation signals to myeloid cells, oxidative damage pathways are strongly boosted leading to more intensive pathology. The proven absence of immune potentiating danger signals in the MOG34–56/IFA formulation implies that a narrow population of antigen-experienced T cells present in the monkey’s immune repertoire is activated. This novel pathway involves the interplay of lymphocryptovirus-infected B cells with MHC class Ib/Caja-E restricted CD8+ CD56+ cytotoxic T lymphocytes.

Cytomegalovirus infection exacerbates autoimmune mediated neuroinflammation

Cytomegalovirus (CMV) is a latent virus which causes chronic activation of the immune system. Here, we demonstrate that cytotoxic and pro-inflammatory CD4⁺CD28^null T cells are only present in CMV seropositive donors and that CMV-specific Immunoglobulin (Ig) G titers correlate with the percentage of these cells. In vitro stimulation of peripheral blood mononuclear cells with CMVpp65 peptide resulted in the expansion of pre-existing CD4⁺CD28^null T cells. In vivo, we observed de novo formation, as well as expansion of CD4⁺CD28^null T cells in two different chronic inflammation models, namely the murine CMV (MCMV) model and the experimental autoimmune encephalomyelitis (EAE) model for multiple sclerosis (MS). In EAE, the percentage of peripheral CD4⁺CD28^null T cells correlated with disease severity. Pre-exposure to MCMV further aggravated EAE symptoms, which was paralleled by peripheral expansion of CD4⁺CD28^null T cells, increased splenocyte MOG reactivity and higher levels of spinal cord demyelination. Cytotoxic CD4⁺ T cells were identified in demyelinated spinal cord regions, suggesting that peripherally expanded CD4⁺CD28^null T cells migrate towards the central nervous system to inflict damage. Taken together, we demonstrate that CMV drives the expansion of CD4⁺CD28^null T cells, thereby boosting the activation of disease-specific CD4⁺ T cells and aggravating autoimmune mediated inflammation and demyelination.

Murine Cytomegalovirus Infection Induces Susceptibility to EAE in Resistant BALB/c Mice

In contrast to C57BL/6 mice, BALB/c mice are relatively resistant to the induction of experimental autoimmune encephalomyelitis (EAE) after challenge with MOG_35–55 peptide. Here, we provide the first evidence that infection with murine cytomegalovirus (MCMV) in adulthood abrogates this resistance. Infected BALB/c mice developed clinical and histological signs similar to those seen in susceptible C57BL/6 mice. In addition to CD4⁺ cells, large proportion of cells in the infiltrate of diseased BALB/c mice was CD8⁺, similar with findings in multiple sclerosis. CD8⁺ cells that responded to ex vivo restimulation with MOG_35–55 were not specific for viral epitopes pp89 and m164. MCMV infection favors proinflammatory type of dendritic cells (CD86⁺CD40⁺CD11c⁺) in the peripheral lymph organs, M1 type of microglia in central nervous system, and increases development of Th1/Th17 encephalitogenic cells. This study indicates that MCMV may enhance autoimmune neuropathology and abrogate inherent resistance to EAE in mouse strain by enhancing proinflammatory phenotype of antigen-presenting cells, Th1/Th17, and CD8 response to MOG_35–55.

An essential role of virus-infected B cells in the marmoset experimental autoimmune encephalomyelitis model

Infection with Epstein–Barr virus (EBV) has been associated with an enhanced risk of genetically susceptible individuals to develop multiple sclerosis (MS). However, an explanation for the contrast between the high EBV infection prevalence (60–90%) and the low MS prevalence (0.1%) eludes us. Here we propose a new concept for the EBV–MS association developed in the experimental autoimmune encephalomyelitis model in marmoset monkeys, which are naturally infected with the EBV-related γ1-herpesvirus CalHV3. The data indicate that the infection of B cells with a γ1-herpesvirus endows them with the capacity to activate auto-aggressive CD8+ T cells specific for myelin oligodendrocyte glycoprotein.

Cytomegalovirus-associated encephalomyelitis in an immunocompetent adult: a two-stage attack of direct viral and delayed immune-mediated invasions. case report

Background

It is clinically rare to find cytomegalovirus (CMV)-associated encephalomyelitis in immunocompetent adults. Here, we present the case of an adult patient who developed acute transverse myelitis that was followed by immune-mediated disseminated encephalomyelitis.

Case presentation

A 38-year-old man developed acute paraplegia with paresthesia below the level of the T7-8 dermatome. Both brain and spinal cord MRIs performed at admission appeared normal. Corticosteroid therapy was initiated, with the later addition of high-dose intravenous immunoglobulins. After polymerase chain reaction analysis indicated the presence of CMV DNA in his cerebrospinal fluid (CSF), anti-viral therapy was added. Forty days after symptom onset, despite an initial positive response to this therapy, he developed dysarthria and truncal ataxia. Repeated magnetic resonance imaging scans demonstrated progressively expanding lesions involving not only the spinal cord but also the cerebral white matter, suggestive of extensive immune-mediated demyelination involving the central nervous system (CNS), as is observed in acute disseminated encephalomyelitis (ADEM).

Conclusion

This case report underscores the importance of careful patient observation following the initial diagnosis of a CMV-associated CNS infection, such as transverse myelitis, on the possibility that post-infectious ADEM may appear.

B cells of multiple sclerosis patients induce autoreactive proinflammatory T cell responses

Antibody-independent B cell functions play an important role in multiple sclerosis (MS) pathogenesis. In this study, B cell antigen presentation and costimulation in MS were studied. Peripheral blood B cells of MS patients showed increased expression of costimulatory CD86 and CD80 molecules compared with healthy controls (HC). In MS cerebrospinal fluid (CSF), 12-fold and 2-fold increases in CD86⁺ and CD80⁺ B cells, respectively, were evidenced compared with peripheral blood. Further, B cells from MS patients induced proinflammatory T cells in response to myelin basic protein (MBP). Immunomodulatory treatment restored B cell costimulatory molecule expression and caused significantly reduced B cell induced T cell responses. Together, these results demonstrate the potential of B cells from MS patients to induce autoreactive proinflammatory T cell responses. Immunomodulatory therapy abrogated this effect, emphasizing the importance of B cell antigen presentation and costimulation in MS pathology.

The common marmoset (<i>Callithrix jacchus</i>): a relevant preclinical model of human (auto)immune-mediated inflammatory disease of the brain

Abstract. The increasing prevalence of chronic autoimmune-mediated inflammatory disorders (AIMIDs) in aging human populations creates a high unmet need for safe and effective medications. However, thus far the translation of pathogenic concepts developed in animal models into effective treatments for the patient has been notoriously difficult. The main reason is that currently used mouse-based animal models for the pipeline selection of promising new treatments were insufficiently predictive for clinical success. Regarding the high immunological similarity between human and non-human primates (NHPs), AIMID models in NHPs can help to bridge the translational gap between rodent and man. Here we will review the preclinical relevance of the experimental autoimmune encephalomyelitis (EAE) model in common marmosets (Callithrix jacchus), a small-bodied neotropical primate. EAE is a generic AIMID model projected on the human autoimmune neuro-inflammatory disease multiple sclerosis (MS).

Immune profile of an atypical EAE model in marmoset monkeys immunized with recombinant human myelin oligodendrocyte glycoprotein in incomplete Freund's adjuvant

Background

Experimental autoimmune encephalomyelitis (EAE) in the common marmoset monkey (Callithrix jacchus) is a relevant preclinical model for translational research into immunopathogenic mechanisms operating in multiple sclerosis (MS). Prior studies showed a core pathogenic role of T and B cells specific for myelin oligodendrocyte glycoprotein (MOG). However, in those studies, the quality of the response against MOG epitopes was strongly biased by bacterial antigens in the complete Freund’s adjuvant (CFA), in which the immunizing recombinant human (rh) MOG protein had been formulated. In response to the need of a more refined EAE model, we have tested whether disease could also be induced with rhMOG in incomplete Freund’s adjuvant (IFA).

Method

Marmosets were immunized with rhMOG emulsified in IFA in the dorsal skin. Monkeys that did not develop neurological deficit were given booster immunizations at 28-day interval with the same antigen preparation. In a second experiment, three marmoset twin pairs were sensitized against MOG peptides in IFA to study a possibility for suppressive activity towards pathogenic T cells directed against the encephalitogenic epitope MOG40-48.

Results

Despite the absence of strong danger signals in the rhMOG/IFA inoculum, all monkeys developed clinically evident EAE symptoms. Moreover, in all monkeys, demyelinated lesions were present in the white matter and in two cases also in the cortical grey matter. Immune profiling at height of the disease showed a dominant T cell response against the overlapping peptides 14–36 and 24–46, but reactivity against the pathogenically most relevant peptide 34–56 was conspicuously absent. In the second experiment, there was an indication for a possible suppressive mechanism.

Conclusions

Immunization of marmoset monkeys with rhMOG in IFA elicits clinical EAE in all animals. Moreover, rhMOG contains pathogenic and regulatory epitopes, but the pathogenic hierarchy of rhMOG epitopes is strongly influenced by the adjuvant in which the protein is formulated.

Electronic supplementary material

The online version of this article (doi:10.1186/s12974-015-0378-5) contains supplementary material, which is available to authorized users.

Acute disseminated encephalomyelitis progressing to multiple sclerosis: are infectious triggers involved?

Acute disseminated encephalomyelitis (ADEM) and multiple sclerosis (MS) are demyelinating disorders affecting the central nervous system. An autoimmune aetiology has been proposed for both. ADEM principally affects adolescents following acute infection by a variety of pathogens and has also been reported to occur following vaccination. ADEM typically resolves following medical treatment, whereas MS follows a more relapsing and remitting course. The pathogenesis of MS remains unclear, but it is thought that a combination of infectious and non-infectious environmental factors and host genetics act synergistically to cause disease. A variety of viruses, including Epstein Barr virus, cytomegalovirus, herpes simplex virus and varicella zoster virus, have been implicated as possible infectious triggers. The similar clinical and pathological presentation of ADEM and MS presents a diagnostic challenge for distinguishing ADEM from a first episode of MS. Some cases of ADEM progress to MS for reasons that are not currently clear. This review examines the evidence for infectious agents as triggers for ADEM progressing to MS and suggests potential methods that may facilitate identification of infectious agents that may be responsible for the pathogenesis of ADEM to MS.

The translational value of non-human primates in preclinical research on infection and immunopathology

The immune system plays a central role in the defense against environmental threats - such as infection with viruses, parasites or bacteria - but can also be a cause of disease, such as in the case of allergic or autoimmune disorders. In the past decades the impressive development of biotechnology has provided scientists with biological tools for the development of highly selective treatments for the different types of disorders. However, despite some clear successes the translation of scientific discoveries into effective treatments has remained challenging. The often-disappointing predictive validity of the preclinical animal models that are used in the selection of the most promising vaccine or drug candidates is the Achilles heel in the therapy development process. This publication summarizes the relevance and usage of non-human primates as pre-clinical model in infectious and autoimmune diseases, in particular for biologicals, which due to their high species-specificity are inactive in lower species.

The primate autoimmune encephalomyelitis model; a bridge between mouse and man

Introduction

Multiple sclerosis (MS) is an enigmatic autoimmune-driven inflammatory/demyelinating disease of the human central nervous system (CNS), affecting brain, spinal cord, and optic nerves. The cause of the disease is not known and the number of effective treatments is limited. Despite some clear successes, translation of immunological discoveries in the mouse experimental autoimmune encephalomyelitis (EAE) model into effective therapies for MS patients has been difficult. This translation gap between MS and its elected EAE animal model reflects the phylogenetic distance between humans and their experimental counterpart, the inbred/specific pathogen free (SPF) laboratory mouse.

Objective

Here, we discuss that important new insights can be obtained into the mechanistic basis of the therapy paradox from the study of nonhuman primate EAE (NHP-EAE) models, the well-validated EAE model in common marmosets (Callithrix jacchus) in particular.

Interpretation

Data presented in this review demonstrate that due to a considerable immunological and pathological overlap with mouse EAE on one side and MS on the other, the NHP EAE model can help us bridge the translation gap.

Selective blockade of CD28-mediated T cell costimulation protects rhesus monkeys against acute fatal experimental autoimmune encephalomyelitis

Costimulatory and coinhibitory receptor-ligand pairs on T cells and APC control the immune response. We have investigated whether selective blockade of CD28-CD80/86 costimulatory interactions, which preserves the coinhibitory CTLA4-CD80/86 interactions and the function of regulatory T (Treg) cells, abrogates the induction of experimental autoimmune encephalomyelitis (EAE) in rhesus monkeys. EAE was induced by intracutaneous immunization with recombinant human myelin oligodendrocyte glycoprotein (rhMOG) in CFA on day 0. FR104 is a monovalent, PEGylated-humanized Fab' Ab fragment against human CD28, cross-reactive with rhesus monkey CD28. FR104 or placebo was administered on days 0, 7, 14, and 21. FR104 levels remained high until the end of the study (day 42). Placebo-treated animals all developed clinical EAE between days 12 and 27. FR104-treated animals did not develop clinical EAE and were sacrificed at the end of the study resulting in a significantly prolonged survival. FR104 treatment diminished T and B cell responses against rhMOG, significantly reduced CNS inflammation and prevented demyelination. The inflammatory profile in the cerebrospinal fluid and brain material was also strongly reduced. Recrudescence of latent virus was investigated in blood, spleen, and brain. No differences between groups were observed for the β-herpesvirus CMV and the polyomaviruses SV40 and SA12. Cross-sectional measurement of lymphocryptovirus, the rhesus monkey EBV, demonstrated elevated levels in the blood of FR104-treated animals. Blocking rhesus monkey CD28 with FR104 mitigated autoreactive T and B cell activation and prevented CNS pathology in the rhMOG/CFA EAE model in rhesus monkeys.

Cytomegalovirus seropositivity is negatively associated with multiple sclerosis

BACKGROUND

Epidemiological data suggest a role for common viruses in the pathogenesis of multiple sclerosis (MS), and recent data showed a negative association of past cytomegalovirus (CMV) infection on pediatric MS risk.

OBJECTIVE

Our aim was to analyze the association of CMV infection with MS risk in an adult case-control material. A meta-analysis was performed to validate our findings.

METHODS

Epidemiological Investigation in MS (EIMS) is a case-control study with incident cases and population-based controls. Anti-CMV antibody titers were measured with ELISA, and HLA-A and DRB1 genotyping was performed with SSP-PCR, in 658 MS cases, who all fulfilled the McDonald criteria for MS, and 786 controls.

RESULTS

CMV seropositivity was associated with a decreased MS risk, OR = 0.73 (0.58-0.92 95% CI), p = 0.005, adjusted for index age, gender, smoking, sun exposure, EBNA1 IgG titer and HLA-A*02 and DRB1*15. When we removed all cases and controls younger than 18 years at index, the protective effect was still apparent.

CONCLUSIONS

CMV is negatively associated with adult-onset MS pathology, consistent with results from a study on pediatric MS cases. It remains to be shown whether this negative association is due to a true protective effect of CMV infection on MS risk.

Induction of encephalitis in rhesus monkeys infused with lymphocryptovirus-infected B-cells presenting MOG(34-56) peptide

The overlapping epidemiology of multiple sclerosis (MS) and Epstein-Barr virus (EBV), the increased risk to develop MS after infectious mononucleosis (IM) and the localization of EBV-infected B-cells within the MS brain suggest a causal link between EBV and MS. However, the underlying mechanism is unknown. We hypothesize that EBV-infected B-cells are capable of eliciting a central nervous system (CNS) targeting autoimmune reaction. To test this hypothesis we have developed a novel experimental model in rhesus monkeys of IM-like disease induced by infusing autologous B-lymphoblastoid cells (B-LCL). Herpesvirus papio (HVP) is a lymphocryptovirus related to EBV and was used to generate rhesus monkey B-LCL. Three groups of five animals were included; each group received three intravenous infusions of B-LCL that were either pulsed with the encephalitogenic self peptide MOG_34–56 (group A), a mimicry peptide (981–1003) of the major capsid protein of cytomegalovirus (CMVmcp_981–1003; group B) or the citrullinated MOG_34–56 (cMOG_34–56; group C). Groups A and B received on day 98 a single immunization with MOG_34–56 in incomplete Freund’s adjuvant (IFA). Group C monkeys were euthanized just prior to day 98 without booster immunization. We observed self-peptide-specific proliferation of T-cells, superimposed on similar strong proliferation of CD3⁺CD8⁺ T-cells against the B-LCL as observed in IM. The brains of several monkeys contained perivascular inflammatory lesions of variable size, comprising CD3⁺ and CD68⁺ cells. Moreover, clusters of CD3⁺ and CD20⁺ cells were detected in the meninges. The only evident clinical sign was substantial loss of bodyweight (>15%), a symptom observed both in early autoimmune encephalitis and IM. In conclusion, this model suggests that EBV-induced B-LCL can elicit a CNS targeting inflammatory (auto)immune reaction.

Induction of experimental autoimmune encephalomyelitis with recombinant human myelin oligodendrocyte glycoprotein in incomplete Freund's adjuvant in three non-human primate species

The experimental autoimmune encephalitis (EAE) model is used for preclinical research into the pathogenesis of multiple sclerosis (MS), mostly in inbred, specific pathogen free (SPF)-raised laboratory mice. However, the naive state of the laboratory mouse immune system is considered a major hurdle in the translation of principles from the EAE model to the MS patient. Non-human primates (NHP) have an immune system harboring T- and B-cell memory against environmental antigens, similar as in humans. We sought to further refine existing NHP EAE models, which may help to bridge the gab between mouse EAE models and MS. We report here on new EAE models in three NHP species: rhesus monkeys (Macaca mulatta), cynomolgus monkeys (Macaca fascicularis) and common marmosets (Callithrix jacchus). EAE was induced with recombinant human myelin oligodendrocyte glycoprotein extracellular domain (1–125) (rhMOG) formulated in incomplete Freund’s adjuvant (IFA). IFA lacks the bacterial antigens that are present in complete Freund’s adjuvant (CFA), which are notorious for the induction of discomforting side effects. Clinically evident EAE could be induced in two out of five rhesus monkeys, six out of six cynomolgus monkeys and six out of six common marmosets. In each of these species, the presence of an early, high anti-rhMOG IgM response is correlated with EAE with an earlier onset and more severe disease course. Animals without an early high IgM response either did not develop disease (rhesus monkeys) or developed only mild signs of neurological deficit (marmoset and cynomolgus monkeys).

The Primate EAE Model Points at EBV-Infected B Cells as a Preferential Therapy Target in Multiple Sclerosis

The remarkable clinical efficacy of anti-CD20 monoclonal antibodies (mAb) in relapsing-remitting multiple sclerosis points at the critical involvement of B cells in the disease. However, the exact pathogenic contribution of B cells is poorly understood. In this publication we review new data on the role of CD20+ B cells in a unique experimental autoimmune encephalomyelitis (EAE) model in common marmosets (Callithrix jacchus), a small-bodied neotropical primate. We will also discuss the relevance of these data for MS. Different from rodent EAE models, but similar to MS, disease progression in marmosets can develop independent of autoantibodies. Progressive disease is mediated by MHC class Ib (Caja-E) restricted cytotoxic T cells, which are activated by γ-herpesvirus-infected B cells and cause widespread demyelination of cortical gray matter. B-cell directed monoclonal antibody therapies (anti-CD20 versus anti-BLyS and anti-APRIL) have a variable effect on EAE progression, which we found associated with variable depletion of the Epstein Barr virus (EBV)-like γ-herpesvirus CalHV3 from lymphoid organs. These findings support an important pathogenic role of CD20+ B cell in MS, especially of the subset infected with EBV.

Antagonizing the α4β1 integrin, but not α4β7, inhibits leukocytic infiltration of the central nervous system in rhesus monkey experimental autoimmune encephalomyelitis

The immune system is characterized by the preferential migration of lymphocytes through specific tissues (i.e., tissue tropism). Tissue tropism is mediated, in part, by the α(4) integrins expressed by T lymphocytes. The α(4)β(1) integrin mediates migration of memory T lymphocytes into the CNS, whereas the α(4)β(7) integrin mediates migration preferentially into gastrointestinal tissue. This paradigm was established primarily from investigations in rodents; thus, the objective of this investigation was to determine if blocking the α(4)β(7) integrin exclusively would affect migration of T lymphocytes into the CNS of primates. The effects of the dual α(4)β(1) and α(4)β(7) antagonist natalizumab were compared with those of the α(4)β(7) antagonist vedolizumab on experimental autoimmune encephalomyelitis in the rhesus monkey. Animals received an initial i.v. bolus of placebo, natalizumab (30 mg/kg), or vedolizumab (30 mg/kg) before intracutaneous immunization with recombinant human myelin oligodendrocyte glycoprotein and then Ab once weekly thereafter. Natalizumab prevented CNS inflammation and demyelination significantly (p < 0.05), compared with time-matched placebo control animals, whereas vedolizumab did not inhibit these effects, despite saturating the α(4)β(7) integrin in each animal for the duration of the investigation. These results demonstrate that blocking α(4)β(7) exclusively does not inhibit immune surveillance of the CNS in primates.

Chronic autoimmune-mediated inflammation: a senescent immune response to injury

The increasing prevalence of chronic autoimmune-mediated inflammatory diseases (AIMIDs) in ageing western societies is a major challenge for the drug development industry. The current high medical need for more-effective treatments is at least in part caused by our limited understanding of the mechanisms that drive chronic inflammation. Here, we postulate a role for immunosenescence in the progression of acute to chronic inflammation via a dysregulated response to primary injury at the level of the damaged target organ. A corollary to this notion is that treatment of acute versus chronic phases of disease might require differential targeting strategies.

Unravelling the T-cell-mediated autoimmune attack on CNS myelin in a new primate EAE model induced with MOG34-56 peptide in incomplete adjuvant

Induction of experimental autoimmune encephalomyelitis (EAE) has been documented in common marmosets using peptide 34-56 from human myelin/oligodendrocyte glycoprotein (MOG(34-56) ) in incomplete Freund's adjuvant (IFA). Here, we report that this EAE model is associated with widespread demyelination of grey and white matter. We performed an in-depth analysis of the specificity, MHC restriction and functions of the activated T cells in the model, which likely cause EAE in an autoantibody-independent manner. T-cell lines isolated from blood and lymphoid organs of animals immunized with MOG(34-56) displayed high production of IL-17A and specific lysis of MOG(34-56) -pulsed EBV B-lymphoblastoid cells as typical hallmarks. Cytotoxicity was directed at the epitope MOG(40-48) presented by the non-classical MHC class Ib allele Caja-E, which is orthologue to HLA-E and is expressed in non-inflamed brain. In vivo activated T cells identified by flow cytometry in cultures with MOG(34-56,) comprised CD4(+) CD56(+) and CD4(+) CD8(+) CD56(+) T cells. Furthermore, phenotypical analysis showed that CD4(+) CD8(+) CD56(+) T cells also expressed CD27, but CD16, CD45RO, CD28 and CCR7 were absent. These results show that, in the MOG34-56/IFA marmoset EAE model, a Caja-E-restricted population of autoreactive cytotoxic T cells plays a key role in the process of demyelination in the grey and white matter.

EAE: imperfect but useful models of multiple sclerosis

The high failure rate of immunotherapies in multiple sclerosis (MS) clinical trials demonstrates problems in translating new treatment concepts from animal models to the patient. One main reason for this 'immunotherapy gap' is the usage of immunologically immature, microbiologically clean and genetically homogeneous rodent strains. Another reason is the artificial nature of the experimental autoimmune encephalomyelitis model, which favors CD4+ T cell driven autoimmune mechanisms, whereas CD8+ T cells are prevalent in MS lesions. In this paper, we discuss preclinical models in humanized rodents and non-human primates that are genetically closer to MS. We also discuss models that best reproduce specific aspects of MS pathology and how these can potentially improve preclinical selection of promising therapies from the discovery pipeline.

Preclinical models of multiple sclerosis in nonhuman primates

Biotechnology has enabled the development of specifically acting therapies for immune-mediated inflammatory disorders (IMIDs) based on biological molecules. The high species specificity precludes safety and effectivity testing in lower species (mice and rats), thus creating a need for valid experimental models in nonhuman primates (NHPs). Here, we review the creation of relevant NHP model(s) for multiple sclerosis (MS), an IMID of the human CNS. We will also discuss how the model(s) can help in the translation of a scientific principle developed in lower species into a therapy for MS.

Experimental autoimmune encephalomyelitis in the common marmoset, a bridge between rodent EAE and multiple sclerosis for immunotherapy development

The attrition rate of new drugs for central nervous system diseases including multiple sclerosis (MS) is very high. A widely recognized bottleneck in the selection of promising central nervous system drug candidates from the development pipeline is the lack of sufficiently predictive animal models. Here, we review how the experimental autoimmune encephalomyelitis (EAE) model in the Neotropical primate "common marmoset" can help to bridge the gap between rodent EAE models and MS. The EAE model in the marmoset closely resembles MS in the clinical as well as pathological presentation and can be used for fundamental research into immunopathogenic mechanisms and for therapy development. We discuss recent insights arising from this model, both on novel therapeutics and immunopathogenesis.

Multiple sclerosis - a response-to-damage model

According to a widely supported but unproven concept, the autoimmune mechanisms that drive neuroinflammation in multiple sclerosis (MS) are triggered by virus infection. However, a direct viral trigger of MS has not been identified. MS models in non-human primates suggest that lifelong asymptomatic infection with certain herpesviruses (e.g. cytomegalovirus) creates a repertoire of potentially autoreactive memory T cells. When these are exposed to antigens released after central nervous system injury as a consequence of an unknown pathogenic event, they are reactivated and induce autoimmune neurological disease. This response-to-damage of antiviral memory cells can take place years after the initiating infection. Consequently, elucidating the anti-herpesvirus T-cell repertoire might provide new targets for preventive diagnosis and therapy.

Clinical, pathological, and immunologic aspects of the multiple sclerosis model in common marmosets (Callithrix jacchus)

The efficacy of many new immunomodulatory therapies for multiple sclerosis (MS) patients has often been disappointing, reflecting our incomplete understanding of this enigmatic disease. There is a growing awareness that, at least in part, there may be limited applicability to the human disease of results obtained in the widely studied MS model experimental autoimmune encephalomyelitis in rodents. This review describes the experimental autoimmune encephalomyelitis model developed in a small neotropical primate, the common marmoset (Callithrix jacchus). The model has features including clinicopathologic correlation patterns, lesion heterogeneity, immunologic mechanisms, and disease markers that more closely mimic the human disease. Several unique features of experimental autoimmune encephalomyelitis in marmosets, together with their outbred nature and close genetic and immunologic similarities to humans, create an attractive experimental model for translational research into MS, particularly for the preclinical evaluation of new biologic therapeutic molecules that cannot be investigated in rodents because of their species specificity. Moreover, this model provides new insights into possible pathogenetic mechanisms in MS.

Fast progression of recombinant human myelin/oligodendrocyte glycoprotein (MOG)-induced experimental autoimmune encephalomyelitis in marmosets is associated with the activation of MOG34-56-specific cytotoxic T cells

The recombinant human (rh) myelin/oligodendrocyte glycoprotein (MOG)-induced experimental autoimmune encephalomyelitis (EAE) model in the common marmoset is characterized by 100% disease incidence, a chronic disease course, and a variable time interval between immunization and neurological impairment. We investigated whether monkeys with fast and slow disease progression display different anti-MOG T or B cell responses and analyzed the underlying pathogenic mechanism(s). The results show that fast progressor monkeys display a significantly wider specificity diversification of anti-MOG T cells at necropsy than slow progressors, especially against MOG(34-56) and MOG(74-96). MOG(34-56) emerged as a critical encephalitogenic peptide, inducing severe neurological disease and multiple lesions with inflammation, demyelination, and axonal injury in the CNS. Although EAE was not observed in MOG(74-96)-immunized monkeys, weak T cell responses against MOG(34-56) and low grade CNS pathology were detected. When these cases received a booster immunization with MOG(34-56) in IFA, full-blown EAE developed. MOG(34-56)-reactive T cells expressed CD3, CD4, or CD8 and CD56, but not CD16. Moreover, MOG(34-56)-specific T cell lines displayed specific cytotoxic activity against peptide-pulsed B cell lines. The phenotype and cytotoxic activity suggest that these cells are NK-CTL. These results support the concept that cytotoxic cells may play a role in the pathogenesis of multiple sclerosis.

CD4+CD28null T cells in autoimmune disease: pathogenic features and decreased susceptibility to immunoregulation

To determine the role of expanded CD4(+)CD28(null) T cells in multiple sclerosis and rheumatoid arthritis pathology, these cells were phenotypically characterized and their Ag reactivity was studied. FACS analysis confirmed that CD4(+)CD28(null) T cells are terminally differentiated effector memory cells. In addition, they express phenotypic markers that indicate their capacity to infiltrate into tissues and cause tissue damage. Whereas no reactivity to the candidate autoantigens myelin basic protein and collagen type II was observed within the CD4(+)CD28(null) T cell subset, CMV reactivity was prominent in four of four HC, four of four rheumatoid arthritis patients, and three of four multiple sclerosis patients. The level of the CMV-induced proliferative response was found to be related to the clonal diversity of the response. Interestingly, our results illustrate that CD4(+)CD28(null) T cells are not susceptible to the suppressive actions of CD4(+)CD25(+) regulatory T cells. In conclusion, this study provides several indications for a role of CD4(+)CD28(null) T cells in autoimmune pathology. CD4(+)CD28(null) T cells display pathogenic features, fill up immunological space, and are less susceptible to regulatory mechanisms. However, based on their low reactivity to the autoantigens tested in this study, CD4(+)CD28(null) T cells most likely do not play a direct autoaggressive role in autoimmune disease.

Preclinical models of arthritic disease in non-human primates

The costs for the development of new drugs have increased dramatically over the past 30 years. One of the main reasons for this increase is the low success rate of new drugs being approved for patient use, which is, in part, a consequence of the common use of rodent models for preclinical validation of efficacy. Especially in the development of biologicals, which are now successfully used in the treatment of rheumatoid arthritis, the selection of the right animal model is pivotal. Non-human primates could help to bridge the evolutionary gap between rodent models and human patients.