The role of the ICOS/B7RP-1 T cell costimulatory pathway in murine experimental autoimmune uveoretinitis

ICOS/B7RP-1 is a new member of the CD28/B7 family of costimulatory molecules and plays differential roles in autoimmune diseases. In this study, we examined the role of ICOS/B7RP-1 pathway in the pathogenesis of mouse experimental autoimmune uveoretinitis (EAU), an animal model of human autoimmune uveitis. ICOS expression was found on infiltrating CD4+ T cells in the region of the retina in EAU-induced mice. The anti-B7RP-1 monoclonal antibody (mAb)-treated or ICOS-deficient mice showed a substantial reduction of disease scores. Blockade of ICOS/B7RP-1 interaction during the effector phase ameliorated the disease, whereas its blockade during the induction phase exhibited no significant effect. Moreover, administration of anti-B7RP-1 mAb effectively ameliorated the disease induced by adoptive transfer of pathogenic T cells. The anti-B7RP-1 mAb treatment inhibited the expansion and/or effector function of pathogenic T cells, given that proliferative response and IFN-gamma production by lymph node cells were reduced upon restimulation with the antigen peptide in vitro. These results suggest that the ICOS/B7RP-1 interaction plays a critical role in the pathogenesis of uveitis. We also indicated that ICOS-mediated costimulation plays differential roles in EAU and experimental autoimmune encephalomyelitis, which is also a Th1 disease induced in the same manner as EAU.     

Epicutaneous (EC) immunization with myelin basic protein (MBP) induces TCRalphabeta+ CD4+ CD8+ double positive suppressor cells that protect from experimental autoimmune encephalomyelitis (EAE)

Multiple sclerosis (MS) is a central nervous system (CNS) chronic inflammatory autoimmune disease with limited treatment modalities. Oral tolerance is one of the experimental methods that protects from autoimmune diseases. However, this method failed to be therapeutic in clinical trials. In our previous work we found that epicutaneous (EC) immunization with protein antigen induced a state of profound immunosuppression that inhibited inflammatory response in contact sensitivity, in experimental autoimmune encephalomyelitis (EAE) and in allogeneic skin graft rejection. In our current work, we precisely determined the phenotype of EC induced T suppressor (Ts) cells that reduce the progress of EAE. Employing TCRdelta-/-, CD1d-/- mice, we showed that EC induced Ts cells do not belong either to the population of TCRgammadelta cells or CD1d restricted NKT cells. Moreover, we noticed that a lack of CD1d-/- restricted NKT lymphocytes resulted in the induction of much stronger suppression of EAE than in wild type mice. This might suggest that NKT cells could interfere with the induction of Ts cells. Using beta2m-/- mice, negative selection and positive selection of EC induced Ts cells, we showed that Ts cells protecting from EAE belong to the population of TCRalphabeta+ CD4+ CD8+ double positive lymphocytes.     

Cytokine shifts and tolerance in experimental autoimmune encephalomyelitis

Cytokines play an important role in the pathogenesis of both multiple sclerosis and experimental autoimmune encephalomyelitis (EAE). Effective treatments for both diseases have been shown to alter cytokines in the central nervous system and in activated mononuclear cells. EAE is an animal model that mimics many aspects of multiple sclerosis, and has been widely used to study the mechanisms of disease and therapeutic approaches to multiple sclerosis. Cytokines play an important role in regulation of disease expression in EAE, and in tolerance to disease induction. In this review, we will summarize the current findings on the role of cytokine shifts in the induction of tolerance in EAE. In addition, we will discuss modulation of EAE by altered expression of members of the cytokine-regulated Jak/STAT intracellular signaling pathway.     

Skeletal muscle myosin is the autoantigen for experimental autoimmune myositis

Experimental autoimmune myositis (EAM) is a rodent model for human inflammatory muscle disease (IMD). It can be induced by immunization of rodents with skeletal muscle homogenate and adjuvant. The specific myositogenic autoantigen has not been clearly identified although some evidence points to skeletal muscle myosin. In this report we strengthen this evidence, showing that Lewis rats immunized with purified skeletal muscle myosin develop EAM with the same pattern and severity as EAM induced by whole rabbit skeletal muscle homogenate (WRM). Multiple inflammatory lesions are detected histopathologically in the biceps, quadriceps, and gastrocnemius muscles. Myosin-reactive T cells from animals immunized either with myosin or with WRM have similar patterns of antigen-induced proliferation. The results show that myosin, a component of skeletal muscle, is at least one autoantigen in EAM.     

Complexities of applying nasal tolerance induction as a therapy for ongoing relapsing experimental autoimmune encephalomyelitis (EAE) in DA rats

EAE is an autoimmune disease of the central nervous system (CNS) that serves as an experimental model for the human inflammatory demyelinating disease multiple sclerosis (MS). Antigen-based immunotherapy including soluble antigen administration via feeding has been shown to be successful in treating EAE in rodents. In the present study, we explore nasal administration of small amounts of myelin basic protein (MBP) as a potential means of treatment of protracted, relapsing EAE (PR-EAE) in a novel DA rat system. We found that nasal administration of MBP prevented EAE induced with whole spinal cord homogenate + Freund's incomplete adjuvant (FIA), and strongly down-regulated levels of MBP-reactive interferon-gamma (IFN-γ)-secreting Th1-like cells. However, in rats with ongoing PR-EAE receiving the same regimen of MBP, a trend of aggravated disease was recorded, in conjunction with augmented levels of MBP-reactive IFN-γ-secreting Th1-like splenocytes during the acute phase of EAE. These data have implications for the clinical application of nasal tolerance to autoimmune diseases.     

T cells in multiple sclerosis and experimental autoimmune encephalomyelitis

Multiple sclerosis (MS) is a demyelinating inflammatory disorder of the central nervous system (CNS), which involves autoimmune responses to myelin antigens. Studies in experimental autoimmune encephalomyelitis (EAE), an animal model for MS, have provided convincing evidence that T cells specific for self‐antigens mediate pathology in these diseases. Until recently, T helper type 1 (Th1) cells were thought to be the main effector T cells responsible for the autoimmune inflammation. However more recent studies have highlighted an important pathogenic role for CD4⁺ T cells that secrete interleukin (IL)‐17, termed Th17, but also IL‐17‐secreting γδ T cells in EAE as well as other autoimmune and chronic inflammatory conditions. This has prompted intensive study of the induction, function and regulation of IL‐17‐producing T cells in MS and EAE. In this paper, we review the contribution of Th1, Th17, γδ, CD8⁺ and regulatory T cells as well as the possible development of new therapeutic approaches for MS based on manipulating these T cell subtypes.     

Transplantation of autoimmune regulator-encoding bone marrow cells delays the onset of experimental autoimmune encephalomyelitis

The autoimmune regulator (AIRE) promotes "promiscuous" expression of tissue-restricted antigens (TRA) in thymic medullary epithelial cells to facilitate thymic deletion of autoreactive T-cells. Here, we show that AIRE-deficient mice showed an earlier development of myelin oligonucleotide glycoprotein (MOG)-induced experimental autoimmune encephalomyelitis (EAE). To determine the outcome of ectopic Aire expression, we used a retroviral transduction system to over-express Aire in vitro, in cell lines and in bone marrow (BM). In the cell lines that included those of thymic medullary and dendritic cell origin, ectopically expressed Aire variably promoted expression of TRA including Mog and Ins2 (proII) autoantigens associated, respectively, with the autoimmune diseases multiple sclerosis and type 1 diabetes. BM chimeras generated from BM transduced with a retrovirus encoding Aire displayed elevated levels of Mog and Ins2 expression in thymus and spleen. Following induction of EAE with MOG(35-55), transplanted mice displayed significant delay in the onset of EAE compared with control mice. To our knowledge, this is the first example showing that in vivo ectopic expression of AIRE can modulate TRA expression and alter autoimmune disease development.     

Antigen-driven tissue-specific suppression following oral tolerance: Orally administered myelin basic protein suppresses proteolipid protein-induced experimental autoimmune encephalomyelitis in the SJL mouse

Immunomodulatory treatment paradigms have been applied to animal models of T cell-mediated autoimmune diseases in an attempt to develop an immunospecific and non-toxic form of therapy which can be applied to humans. These treatment paradigms are often directed to T cells with a restricted T cell receptor repertoire or that react with dominant peptide determinants. Experimental data, however, suggests that even if the initial T cell response is restricted to a specific self-protein in the target organ, spreading autoimmunity may develop with broadening of T cell autoreactivity to additional epitopes of the same autoantigen or to different autoantigens in the target organ. Thus, multiple autoantigens may become targets of the autoimmune response. This makes immunotherapeutic strategies based on suppressing responses to restricted proteins or clones of cells problematic. We have previously shown that suppression of experimental autoimmune encephalomyelitis (EAE) in the Lewis rat by oral myelin basic protein (MBP) is mediated by the release of transforming growth factor-β after triggering by the oral tolerogen. Here, we report that in the SJL model of EAE oral administration of an autoantigen from the target tissue suppresses disease independent of whether it is or is not the inciting antigen. Thus, orally administered MBP or MBP peptides suppress proteolipid protein (PLP)-induced EAE, whereas intravenously administered MBP does not. Both oral and intravenous PLP, however, suppressed PLP disease. These findings have important implications for the use of oral tolerance as a therapeutic approach for the treatment of T cell-mediated inflammatory autoimmune diseases in man in which the inciting autoantigen is unknown or in which there is autoreactivity to multiple autoantigens in the target tissue.     

Galectin isolated from parasite inhibits remission of experimental autoimmune encephalomyelitis by up‐regulating autoantibody

Recently, parasite infections or parasite‐derived products have been suggested as a therapeutic strategy with suppression of immunopathology, which involves the induction of regulatory T cells or/and T helper type 2 (Th2) responses. In a recent study, researchers reported that constructed recombinant galectin (rTl‐gal) isolated from an adult worm of the gastrointestinal nematode parasite Toxascaris leonina attenuated clinical symptoms of inflammatory bowel disease in mice treated with dextran sulphate sodium. Noting the role of rTl‐gal in inflammatory disease, we attempted to investigate the effect of the parasite via its rTl‐gal on neuronal autoimmune disease using experimental autoimmune encephalomyelitis (EAE), a mouse inflammatory and demyelinating autoimmune disease model of human multiple sclerosis. In this model, rTl‐gal‐treated experimental autoimmune encephalomyelitis (EAE) mice failed to recover after the peak of the disease, leading to persistent central nervous system (CNS) damage, such as demyelination, gliosis and axonal damage. Further, rTl‐gal‐treated EAE mice markedly increased the number of CD45R/B220⁺ B cells in both infiltrated inflammation and the periphery, along with the increased production of autoantibody [anti‐myelin oligodendrocyte glycoprotein (MOG)_35–55] in serum at chronic stage. Upon antigen restimulation, rTl‐gal treatment affected the release of overall cytokines, especially interferon (IFN)‐γ and tumour necrosis factor (TNF)‐α. Our results suggest that galectin isolated from a gastrointestinal parasite can deliver a harmful effect to EAE contrary to its beneficial effect on inflammatory bowel disease.     

Diagnosis and assessment of preclinical and clinical autoimmune encephalomyelitis using peripheral blood lymphocyte TCR

In organ-specific autoimmune diseases, T cells involved in the disease development bear a particular type of TCR and infiltrate the target organ predominantly. However, it is difficult to identify disease-inducing T cells in peripheral blood lymphocytes (PBL) because such T cells are very few in number in a large pool of unrelated T cells. In the present study, we demonstrate that CDR3 spectratyping can identify experimental autoimmune encephalomyelitis (EAE)-specific patterns (oligoclonal expansion of Vβ8.2 with the shortest CDR3) in PBL at the preclinical and clinical stages of acute EAE. Analysis of nucleotide and predicted amino acid sequences of Vβ8.2 CDR3 of spectratype-derived clones revealed that CASSDSSYEQYFGPG, which is one of the representative sequences of encephalitogenic T cell clones, constituted the predominant population in both PBL and spinal cord T cells. In chronic relapsing EAE, the EAE-specific spectratype pattern in PBL was observed during the 1st and 2nd attacks, but not at the remission and full recovery stage. These findings indicate that the spectratyping pattern in PBL reflects the disease activity of acute and chronic relapsing EAE. Thus, CDR3 spectratyping using PBL can be used for diagnosis and assessment of T cell-mediated autoimmune diseases and is applicable to human autoimmune diseases.     

Deletion of both the C3a and C5a receptors fails to protect against experimental autoimmune encephalomyelitis

Multiple sclerosis (MS) is an autoimmune disease in which inflammation, leukocyte infiltration, and ultimately, demyelination occur as a result of innate and adaptive immune-mediated mechanisms. The pathophysiological role of the complement system, a major component of innate immunity, in the development and progression of experimental autoimmune encephalomyelitis (EAE), the animal model for MS has been extensively examined. Previous studies from our lab have shown that the complement receptor for the anaphylatoxin C3a, but not for C5a plays an important role in EAE. Based on the important contributions of the complement anaphylatoxin receptors to other inflammatory conditions in the CNS, we reasoned that deletion of both receptors may reveal underlying interactions between them that are important to EAE pathology. We performed EAE in C3aR/C5aR double knockout mice (C3aR/C5aR^−/−) and observed delayed onset of disease but no attenuation of disease severity compared to wild type mice. Interestingly there was trend toward greater infiltration of CD4⁺, but not CD8⁺ T cells, in C3aR/C5aR^−/− mice with EAE, suggesting altered trafficking of these cells. Antigen-specific T cells isolated from C3aR/C5aR^−/− mice during acute EAE produced elevated levels of TNF-α, but markedly reduced levels of IFN-γ and IL-12 compared to wild type mice. It remains unclear how the changes in these disease parameters contribute to the loss of the protective effect seen in C3aR^−/− mice, however our data indicate a level of cross-modulation between the C3aR and C5aR during EAE.     

Development of an improved animal model of experimental autoimmune myositis

Multiple animal models of experimental autoimmune myositis (EAM) have been developed. However, these models vary greatly in the severity of disease and reproducibility. The goal of this study was to test whether vaccination twice with increased dose of rat myosin and pertussis toxin (PT) could induce EAM with severer disease in mice. BALB/c mice were injected with 1 mg rat myosin in 50% complete Freund’s adjuvant (CFA) weekly for four times and one time of PT (EAM) or twice with 1.5 mg myosin in CFA and PT (M-EAM). In comparison with that in the CFA and PT injected controls, vaccination with rat myosin and injection PT significantly reduced the muscle strength and EMG duration, elevated serum creatine kinase levels, promoted inflammatory infiltration in the muscle tissues, leading to pathological changes in the muscle tissues, demonstrating to induce EAM. Interestingly, we found that vaccination twice with the high dose of myosin and PT prevented EAM-related gain in body weights and caused significantly less muscle strength in mice. More importantly, all of the mice receiving high dose of myosin and PT survived while 3 out of 16 mice with four times of low dose of myosin died. Finally, vaccination with high dose of myosin promoted CD4⁺ and CD8⁺ T cell infiltration in the muscle tissues and up-regulated MHC-I expression in the muscle tissues of mice. Hence, the new model of EAM is a time-saving, efficient and easily replicable tool for studying autoimmune myositis.     

Chronic relapsing experimental autoimmune encephalomyelitis with a delayed onset and an atypical clinical course,induced in PL/J mice by myelin oligodendrocyte glycoprotein (MOG)-derived peptide: Preliminary analysis of MOG T cell epitopes

Myelin basic protein (MBP) and proteolipid protein (PLP), the most abundant proteins of central nervous system (CNS) myelin, have been extensively studied as possible primary target antigens in multiple sclerosis (MS), a primary demyelinating autoimmune disease of the CNS. However, there is increasing evidence to suggest that autoimmune reactivity against the quantitatively minor myelin component, myelin oligodendrocyte glycoprotein (MOG), can also play a role in the pathogenicity of MS. We recently demonstrated a predominant response to MOG by peripheral blood lymphocytes from patients with MS tested for their reactivity against various myelin antigens, including MBP and PLP. To ascertain whether or not T cell reactivity to MOG in MS is a potentially pathogenic response, we have tested the ability of synthetic MOG peptides (pMOG) representing potential T cell epitopes, to induce neurological disease in mice. Both strains of mice tested (SJL/J and PL/J mice) were able to mount a primary T cell response to some of the five MOG peptides synthesized, pMOG 1–21, 35–55, 67–87, 104–117 and 202–218. T cell lines could be raised in both strains to pMOG 35–55 and 67–87, but epitope definition revealed that each strain recognized a different minimal epitope within these two peptides. T cell lines to pMOG 1–21 and 202–218 could also be raised in SJL/J and PL/J mice, respectively. T cell reactivity to pMOG 104–117 was not observed in either mouse strain. None of the peptides tested induced detectable clinical signs in SJL/J mice. In contrast, an MS-like chronic relasping-remitting disease could be induced in PL/J mice with pMOG 35–55. The disease presented with a delayed onset and with clinical signs which differed significantly in their progression and expression from the typical ascending paralysis of experimental autoimmune encephalomyelitis induced with other myelin components, such as MBP and PLP. Histological examination of CNS tissue from mice injected with pMOG 35–55 revealed only mild neuropathological signs with few inflammatory foci in brain and spinal cord. Some myelin splitting and edema were detected upon electron microscopic examination in the spinal cord and cerebellum. Transfer of pMOG 35–55 reactive T cells into naive PL/J mice resulted in pathological changes characterized by inflammatory foci in the brain and spinal cord. This passively induced disease was clinically silent, as was also reported for Lewis rats injected with T cells specific for the same MOG peptide. These data, which demonstrate unequivocally the encephalitogenic activity of MOG, support our contention that MOG may be as important as MBP or PLP in disease pathogenesis and could be a primary target antigen in autoimmune diseases of the CNS.     

A New Targeted Model of Experimental Autoimmune Encephalomyelitis in the Common Marmoset

Multiple sclerosis (MS) is the most common cause for sustained disability in young adults, yet treatment options remain very limited. Although numerous therapeutic approaches have been effective in rodent models of experimental autoimmune encephalomyelitis (EAE), only few proved to be beneficial in patients with MS. Hence, there is a strong need for more predictive animal models. Within the past decade, EAE in the common marmoset evolved as a potent, alternative model for MS, with immunological and pathological features resembling more closely the human disease. However, an often very rapid and severe disease course hampers its implementation for systematic testing of new treatment strategies. We here developed a new focal model of EAE in the common marmoset, induced by myelin oligodendrocyte glycoprotein (MOG) immunization and stereotactic injections of proinflammatory cytokines. At the injection site of cytokines, confluent inflammatory demyelinating lesions developed that strongly resembled human MS lesions. In a proof‐of‐principle treatment study with the immunomodulatory compound laquinimod, we demonstrate that targeted EAE in marmosets provides a promising and valid tool for preclinical experimental treatment trials in MS research.     

Application of nanomedicine for crossing the blood–brain barrier: Theranostic opportunities in multiple sclerosis

Multiple sclerosis (MS) is an autoimmune neurodegenerative disease characterized with immunopathobiological events, including lymphocytic infiltration into the central nervous system (CNS), microglia activation, demyelination and axonal degeneration. Although several neuroprotective drugs have been designed for the treatment of MS, complete remission is yet matter of debate. Therefore, development of novel therapeutic approaches for MS is of a high priority in immunological research. Nanomedicine is a recently developed novel medical field, which is applicable in both diagnosis and treatment of several cancers and autoimmune diseases. Although there is a marked progress in neuroimaging through using nanoparticles, little is known regarding the therapeutic potential of nanomedicine in neurological disorders, particularly MS. Moreover, the majority of data is limited to the MS related animal models. In this review, we will discuss about the brain targeting potential of different nanoparticles as well as the role of nanomedicine in the diagnosis and treatment of MS and its animal model, experimental autoimmune encephalomyelitis.     

Antigen presentation in autoimmunity and CNS inflammation: how T lymphocytes recognize the brain

The central nervous system (CNS) is traditionally viewed as an immune privileged site in which overzealous immune cells are prevented from doing irreparable damage. It was believed that immune responses occurring within the CNS could potentially do more damage than the initial pathogenic insult itself. However, virtually every aspect of CNS tissue damage, including degeneration, tumors, infection, and of course autoimmunity, involves a significant cellular inflammatory component. While the blood–brain barrier (BBB) inhibits diffusion of hydrophilic (immune) molecules across brain capillaries, activated lymphocytes readily pass the endothelial layer of postcapillary venules without difficulty. In classic neuro-immune diseases such as multiple sclerosis or acute disseminated encephalomyelitis, it is thought that neuroantigen-reactive lymphocytes, which have escaped immune tolerance, now invade the CNS and are responsible for tissue damage, demyelination, and axonal degeneration. The developed animal model for these disorders, experimental autoimmune encephalomyelitis (EAE), reflects many aspects of the human conditions. Studies in EAE proved that auto-reactive encephalitogenic T helper (Th) cells are responsible for the onset of the disease. Th cells recognize their cognate antigen (Ag) only when presented by professional Ag-presenting cells in the context of major histocompatibility complex class II molecules. The apparent target structures of EAE immunity are myelinating oligodendrocytes, which are not capable of presenting Ag to invading encephalitogenic T cells. A compulsory third party is thus required to mediate between the attacking T cells and the myelin-expressing target. This review will discuss the recent advances in this field of research and we will discuss the journey of an auto-reactive T cell from its site of activation into perivascular spaces and further into the target tissue.     

New insights into cell responses involved in experimental autoimmune encephalomyelitis and multiple sclerosis

Animal models of autoimmune diseases such as experimental autoimmune encephalomyelitis (EAE) are inflammatory demyelinating diseases which comprise a heterogeneous group of disorders that affect the peripheral and central nervous systems. EAE presents close similarities with multiple sclerosis (MS), a chronic inflammatory disease affecting central nervous system (CNS) white matter. Many studies have shown EAE to be a particularly useful animal model for the understanding of both the mechanisms of immune-mediated CNS pathology and the progressive clinical course of multiple sclerosis. Previous data has underlined the importance of CD4+ T cell involvement in mediating the autoimmune processes associated with the destruction of myelin and the role of the T helper 1 (Th1) pattern of cytokine secretion. However, EAE studies have also demonstrated that other cells involved in innate and/or adaptive immune responses may also play a critical role in the early and progressive events of the immune reaction leading to inflammation and CNS damage. In this review, we present such new data and discuss their potent implication for future new therapeutical approaches.     

The influence and impact of ageing and immunosenescence (ISC) on adaptive immunity during multiple sclerosis (MS) and the animal counterpart experimental autoimmune encephalomyelitis (EAE)

The human ageing process encompasses mechanisms that effect a decline in homeostasis with increased susceptibility to disease and the development of chronic life-threatening illness. Increasing age affects the immune system which undergoes a progressive loss of efficiency, termed immunosenescence (ISC), to impact on quantitative and functional aspects of innate and adaptive immunity. The human demyelinating disease multiple sclerosis (MS) and the corresponding animal model experimental autoimmune encephalomyelitis (EAE) are strongly governed by immunological events that primarily involve the adaptive arm of the immune response. MS and EAE are frequently characterised by a chronic pathology and a protracted disease course which thereby creates the potential for exposure to the inherent, on-going effects and consequences of ISC. Collective evidence is presented to confirm the occurrence of established and unendorsed biological markers of ISC during the development of both diseases. Moreover, results are discussed from studies during the course of MS and EAE that reveal a premature upregulation of ISC-related biomarkers which indicates untimely alterations to the adaptive immune system. The effects of ISC and a prematurely aged immune system on autoimmune-associated neurodegenerative conditions such as MS and EAE are largely unknown but current evaluation of data justifies and encourages further investigation.