IgG subclass switching is associated with the severity of experimental autoimmune encephalomyelitis induced with myelin oligodendrocyte glycoprotein peptide in NOD mice

Genistein prevention of hyperglycemia and improvement of glucose tolerance in adult non-obese diabetic mice are associated with alterations of gut microbiome and immune homeostasis

Although studies have linked soy phytoestrogen 4,7,4-trihydroxyisoflavone genistein (GEN) to reduced type 1 diabetes (T1D) risk, the mechanism of dietary GEN on T1D remains unknown. In our studies, adult non-obese diabetic (NOD) mouse model was employed to investigate the effects of GEN exposure on blood glucose level (BGL), glucose tolerance, gut microbiome, and immune responses. Adult male and female NOD mice were fed with either soy-based or casein-based diet, and received GEN at 20mg/kg body weight by gavage daily. The BGL and immune responses (represented by serum antibodies, cytokines and chemokines, and histopathology) were monitored, while the fecal gut microbiome was sequenced for 16S ribosomal RNA to reveal any alterations in gut microbial communities. A significantly reduced BGL was found in NOD males fed with soy-based diet on day 98 after initial dosing, and an improved glucose tolerance was observed on both diets. In addition, an anti-inflammatory response (suggested by reduced IgG2b and cytokine/chemokine levels, and alterations in the microbial taxonomy) was accompanied by an altered β-diversity in gut microbial species. Among the NOD females exposed to GEN, a later onset of T1D was observed. However, the profiles of gut microbiome, antibodies and cytokines/chemokines were all indicative of pro-inflammation. This study demonstrated an association among GEN exposure, gut microbiome alteration, and immune homeostasis in NOD males. Although the mechanisms underlying the protective effects of GEN in NOD mice need to be explored further, the current study suggested a GEN-induced sex-specific effect in inflammatory status and gut microbiome.

Cytokine production profiles in chronic relapsing-remitting experimental autoimmune encephalomyelitis: IFN-γ and TNF-α are important participants in the first attack but not in the relapse

Multiple sclerosis (MS) is a chronic demyelinating disease often displaying a relapsing-remitting course of neurological manifestations that is mimicked by experimental autoimmune encephalomyelitis (EAE) in animal models of MS. In particular, NOD mice immunized with myelin oligodendrocyte glycoprotein peptide 35-55 develop chronic relapsing-remitting EAE (CREAE). To elucidate the mechanisms that cause MS relapse, we investigated the histopathology and cytokine production of spleen cells and mRNA expression levels in the central nervous system (CNS) of CREAE mice. During the first attack, inflammatory cell infiltration around small vessels and in the subarachnoid space was observed in the spinal cord. Spleen cell production and mRNA expression in the CNS of several cytokines, including IFN-γ, TNF-α, IL-6, IL-17, and CC chemokine ligand 2 (CCL2), were higher in CREAE mice than in controls. Afterwards, parenchymal infiltration and demyelination were observed histologically in the spinal cord and corresponded with the more severe clinical symptoms of the first and second relapses. IL-17 and CCL2, but not IFN-γ, TNF-α, or IL-6, were also produced by spleen cells during recurrences. Our results suggested that the immune mechanisms in relapses were different from those in the first attack for CREAE. Further investigation of CREAE mechanisms may provide important insights into successful therapies for human relapsing-remitting MS.

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

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

RNA interference targeting Bcl-6 ameliorates experimental autoimmune myasthenia gravis in mice

Follicular helper T (Tfh) cells are dedicated to providing help to B cells and are strongly associated with antibody-mediated autoimmune disease. B cell lymphoma 6 (Bcl-6) is a key transcription factor of Tfh cells, and IL-21 is known to be a critical cytokine produced by Tfh cells. We silenced Bcl-6 gene expression using RNA interference (RNAi) delivered by a lentiviral vector, to evaluate the therapeutic role of Bcl-6 short hairpin RNAs (shRNAs) in experimental autoimmune myasthenia gravis (EAMG). Our data demonstrate that CD4(+)CXCR5(+)PD-1(+) Tfh cells, Bcl-6 and IL-21 were significantly increased in EAMG mice, compared with controls. In addition, we found that frequencies of Tfh cells were positively correlated with the levels of serum anti-AChR Ab. In-vivo transduction of lenti-siRNA-Bcl6 ameliorates the severity of ongoing EAMG with decreased Tfh cells, Bcl-6 and IL-21 expression, and leads to decreased anti-AChR antibody levels. Furthermore, we found that siRNA knockdown of Bcl-6 expression increases the expression of Th1(IFN-γ, T-bet) and Th2 markers (IL-4 and GATA3), but failed to alter the expression of Th17-related markers (RORγt, IL-17) and Treg markers (FoxP3). Our study suggests that Tfh cells contribute to the antibody production and could be one of the most important T cell subsets responsible for development and progression of EAMG or MG. Bcl-6 provides a promising therapeutic target for immunotherapy not only for MG, but also for other antibody-mediated autoimmune diseases.

Impaired neural stem/progenitor cell proliferation in streptozotocin-induced and spontaneous diabetic mice

Diabetes mellitus is associated with adverse complications in many organ systems including the brain. Accumulating evidence indicates that diabetes, regardless of its type, impairs adult neurogenesis in the dentate gyrus (DG) of the hippocampus (HPC). However, the effects of the disease on neurogenesis in the subventricular zone (SVZ) are not well established. We induced diabetes in male NOD/SCID (non-obese diabetic/severe combined immunodeficiency) mice and C57BL/6 mice with a single intraperitoneal injection of streptozotocin (STZ). On day 7 or day 21 after STZ injection mice received the thymidine analog 5-bromo-2'-deoxyuridine (BrdU) for labeling of proliferative cells. Mice were sacrificed 24h later and brain coronal sections were stained with anti-BrdU antibodies. Neural stem/progenitor cell (NSC/NPC) proliferation, as revealed by BrdU-labeled cells, was markedly decreased in the subgranular zone of the DG in STZ-treated diabetic mice. A similar reduction of NSC/NPC proliferation was seen in the SVZ. Reduced DG and SVZ cell proliferation was also found in diabetic NOD mice, a model of spontaneous diabetes, and the reduction was attenuated by bilateral adrenalectomy (Adx). Adx did not alter blood glucose or insulin levels in either prediabetic or diabetic NOD mice, but Adx partly increased mRNA levels of hippocampal and SVZ brain-derived neurotrophic factor (BDNF), a crucial regulator of NSC/NPC proliferation. Moreover, NOD and NOD/SCID mice showed a more rapid reduction of NSC/NPC proliferation than C57BL/6 mice in response to diabetes. Thus, we conclude that diabetes inhibits cell proliferation in both the SVZ and HPC, and inhibition was associated with elevated glucocorticoid levels and reduced BDNF expression.

Interaction between Gonadal Steroids and Neuroimmune System in Acute Experimental Autoimmune Encephalomyelitis (EAE) in Wistar Rats

Experimental autoimmune encephalomyelitis (EAE) is an inflammatory disease of the CNS mediated by autoreactive T lymphocytes directed against myelin antigens. Since neuroendocrine-immune dysfunction appears to contribute to the pathogenesis of autoimmune diseases, the present work was designed to study the effect of changes in the endocrine system on the development of acute EAE and the immune response against myelin basic protein (MBP). Intact and sham males and intact female Wistar rats showed the most severe clinical symptoms (acute period) 12-14 days post-inoculation (dpi). Then, they began gradually to recover, regaining the total ability to walk by 15-17 dpi. Male Wistar rats with altered levels of gonadal hormones by surgical castration showed an onset of the symptoms retarded 2-3 days with respect to the other EAE groups, showing neuropathological symptoms up to 27-28 dpi, and remaining with lower body weight even at 40 dpi. The castrated animals exhibited a specific delay in MBP-stimulated DTH reactivity that correlates with the delay in the onset of the clinical symptoms. Also significant lymphocyte proliferation to MBP was still present at 35 dpi that was absent in the sham group. The distribution of the IgG subclasses indicated that at 35 dpi castrated animals have a higher IgG2b/IgG1 ratio (35.1) in comparison to that presented by sham rats (4.8). Considering that at this time the castrated animals were not completely recuperated, these results could indicate an ongoing inflammatory immune response associated with Th1 activity in these animals. Also castrated animals developed antibodies to a diversity of MBP epitopes in comparison to sham rats, which presented a dominance of antibodies to MBP peptide p96-128. These results indicate that sex hormones levels regulate cell-mediated immunity and the specificity of anti-MBP antibodies related to the induction and development of acute EAE.

Antibodies to myelin oligodendrocyte glycoprotein are not involved in the severity of chronic non-remitting experimental autoimmune encephalomyelitis

To elucidate the role of antibodies in development of chronic non-remitting experimental autoimmune encephalomyelitis (EAE) in C57BL/6 mice, which is a well-established Th1-mediated autoimmune disease, and the involvement of activation-induced cytidine deaminase (AID) in Th1-mediated function, we have investigated the myelin oligodendrocyte glycoprotein (MOG)-induced EAE in mice deficient of AID, which is absolutely required for class switching and somatic hypermutation. Following immunization with MOG, AID(-/-) had completely same levels of clinical and pathological severity of EAE when compared with AID(+/-) and AID(+/+), although AID(-/-) did not produce IgG and anti-MOG IgG. Similar levels of T cell proliferation and a modest increase of anti-MOG IgM synthesis were found in spleen cells of AID(-/-) stimulated with MOG. These results indicate that antibodies are not involved in development of EAE in C57BL/6 mice.

Altered susceptibility to EAE in congenic NOD mice: Altered processing of the encephalitogenic MOG35-55 peptide by NOR/LtJ mice

NOD mice (H-2 g7) naturally develop autoimmune diabetes, while the congenic NOR/LtJ mice (H-2 g7) are resistant. To determine if defective immune regulation renders NOD susceptible to autoimmune disease, we compared MOG35-55-induced EAE in NOD mice to that of NOR/LtJ. In two of three immunization protocols, the NOR/LtJ mice developed significantly reduced indices and severity of clinical disease, in spite of an exaggerated autoimmune response to MOG35-55. Characterization of the responding T cell repertoires revealed that V beta 8+ Th cells directed toward the MOG42-55 core epitope were dominant in both strains. Interestingly, CD8+ CTL were absent or significantly reduced in MOG35-55 lymphoblasts from NOR/LtJ mice, which poorly processed the MOG39-47 CTL epitope from MOG35-55. Thus, while particular MHC class II alleles may be associated with increased risk, molecules involved in the processing of key epitopes may be influential in the progression of autoimmune disease.

Induction of Complement-Fixing Autoantibodies against Type VII Collagen Results in Subepidermal Blistering in Mice

Experimental models reproducing an autoimmune response resulting in skin blistering in immunocompetent animals are lacking. Epidermolysis bullosa acquisita (EBA) is a bullous skin disease caused by autoantibodies to type VII collagen. In this study, we describe an active disease model of EBA by immunizing mice of different strains with murine type VII collagen. All mice developed circulating IgG autoantibodies that recognized type VII collagen and bound to the lamina densa of the dermal-epidermal junction. Importantly, subepidermal blisters developed in 82% of SJL-1, 56% of BALB/c mice, and 45% of Fc gammaRIIb-deficient mice, but not in SKH-1 mice. In susceptible animals, deposits of IgG1, IgG2, and complement C3 were detected at the dermal-epidermal junction. In contrast, in the nondiseased mice, tissue-bound autoantibodies were predominantly of the IgG1 subclass and complement activation was weak or absent. This active disease model reproduces in mice the clinical, histopathological, and immunopathological findings in EBA patients. This robust experimental system should greatly facilitate further studies on the pathogenesis of EBA and the development of novel immunomodulatory therapies for this and other autoimmune diseases.

Chronic expression of monocyte chemoattractant protein-1 in the central nervous system causes delayed encephalopathy and impaired microglial function in mice

Increased central nervous system (CNS) levels of monocyte chemoattractant protein 1 [CC chemokine ligand 2 (CCL2) in the systematic nomenclature] have been reported in chronic neurological diseases such as human immunodeficiency virus type 1-associated dementia, amyotrophic lateral sclerosis, and multiple sclerosis. However, a pathogenic role for CCL2 has not been confirmed, and there is no established model for the effects of chronic CCL2 expression on resident and recruited CNS cells. We report that aged (>6 months) transgenic (tg) mice expressing CCL2 under the control of the human glial fibrillary acidic protein promoter (huGFAP-CCL2hi tg+ mice) manifested encephalopathy with mild perivascular leukocyte infiltration, impaired blood brain barrier function, and increased CD45-immunoreactive microglia, which had morphologic features of activation. huGFAP-CCL2hi tg+ mice lacking CC chemokine receptor 2 (CCR2) were normal, showing that chemokine action via CCR2 was required. Studies of cortical slice preparations using video confocal microscopy showed that microglia in the CNS of huGFAP-CCL2hi tg+ mice were defective in expressing amoeboid morphology. Treatment with mutant CCL2 peptides, a receptor antagonist and an obligate monomer, also suppressed morphological transformation in this assay, indicating a critical role for CCL2 in microglial activation and suggesting that chronic CCL2 exposure desensitized CCR2 on microglia, which in the CNS of huGFAP-CCL2hi tg+ mice, did not up-regulate cell-surface expression of major histocompatibility complex class II, CD11b, CD11c, or CD40, in contrast to recruited perivascular macrophages that expressed enhanced levels of these markers. These results indicate that huGFAP-CCL2hi tg+ mice provide a useful model to study how chronic CNS expression of CCL2 alters microglial function and CNS physiology.

Age-related changes in the development of experimental autoimmune encephalomyelitis

A prominent feature of multiple sclerosis is its high incidence of onset in the third decade of life and its relatively rare onset in persons older than 50 years. In order to study age-related restriction of clinical expression, a comparative biochemical, immunological and histological study was undertaken during development of experimental autoimmune encephalomyelitis (EAE) in young (7 weeks) and middle-aged (15 months) Wistar rats. Young rats showed characteristic clinical signs 12-16 days postinduction, and then they spontaneously recuperated. In middle-aged rats, the incidence of clinical signs was significantly reduced, with a later onset of the disease. Similar biochemical and histological alterations were detected in both age groups, but they were present in a later stage in middle-aged animals. However, cellular and humoral immune responses to myelin basic protein (MBP) were observed 15 days postinduction in all EAE animals. The study of anti-MBP IgG isotype pattern in 7-week-old animals indicated a predominant Th1-type immune response during the acute stage of EAE, with antibodies predominantly recognizing the MBP 96-128 peptide. In contrast, 15-month-old animals showed a less prominent Th1 response, without any epitope dominance. The changes in immune function found in middle-aged animals may account for the different susceptibility and expression of EAE, and may also be relevant to the different clinical expression observed in multiple sclerosis with maturation.

Is innervation an early target in autoimmune diabetes?

In the non-obese diabetic (NOD) mouse, a spontaneous model of type 1 diabetes (T1D), recent evidence suggests that Schwann cells (Scs) and neurons surrounding insulin-producing beta cells of the islets of Langerhans are destroyed before beta cells. During normal perinatal development, macrophages (MPhi) are involved in phagocytosis of apoptotic neurons. Pertinently, MPhi are already present at birth in NOD pancreata. Their possible abnormal control of nerve phagocytosis, together with transient beta-cell hyperactivity and lymphocyte anomalies, might conjointly participate in T1D pathogenesis.

Specificity of autoantibodies to epitopes of myelin proteins in multiple sclerosis

An autoimmune response to one or more myelin-protein components is thought to be part of the pathogenesis of multiple sclerosis (MS). The immunodominant-autoantibody epitope may be localized on a linear peptide segment, on a conformation-sensitive epitope, or on an epitope resulting from post-translational modifications. Primary, secondary, and tertiary structures of myelin proteins may determine the specific site for binding of autoantibodies. A myelin protein-specific autoantibody can bind to either a linear or conformational epitope, whereas all of the T cell epitopes are linear. At present, the conformational epitopes of myelin proteins have not been identified; most of the methods used to identify the myelin-protein epitopes corresponding to the pathogenesis of multiple sclerosis are involved in the linear epitope mapping. Polymorphism or mutations may cause inappropriate expression of the myelin proteins with alterations to their linear and/or conformational epitopes, and make them susceptible to autoantibody binding, especially if these changes occur at the surface of the protein. This review focuses on the specificity of autoantibodies to the epitopes of myelin proteins and correlates this to the structures of proteins. Factors that influence the expression of myelin-protein epitopes such as the alpha-helical or beta-sheet structure of the protein, the tri-proline site, and the post-translational modifications as well as physicochemical properties of amino acid changed are included.

The role of subclass switching in the pathogenesis of endemic pemphigus foliaceus

Endemic pemphigus foliaceus, like the sporadic form seen in the developed world, is mediated by IgG antibodies to desmoglein-1. We studied an endemic focus in Limao Verde, Brazil, where disease prevalence is 3.4%. We previously detected IgG antibodies to desmoglein-1 in 97% of patients, but also in 55% of normal subjects in the endemic focus, with progressively lower levels in normal subjects in surrounding areas. An environmental trigger is hypothesized to explain these and other findings. In this study we sought to determine if patients and enzyme-linked-immunosorbent-assay-positive normal subjects in Limao Verde differ in IgG subclass response to desmoglein-1. We developed a sensitive and specific subclass enzyme-linked immunosorbent assay using recombinant desmoglein-1 and standardized the assay to enable comparability between the four subclasses. We found that normal subjects have an IgG1 and IgG4 response, whereas patients have similar levels of IgG1 but a mean 19.3-fold higher IgG4 response. Patients in remission have a weak IgG4 response, and a 74.3-fold higher IgG4 response is associated with active disease. Finally, in five patients in whom we had blood samples from both before and after the onset of clinical disease, a mean 103.08-fold rise in IgG4 was associated with onset of clinical disease, but only a mean 3.45-fold rise in IgG1. These results suggest that the early antibody response in normal subjects living in the endemic area and in patients before the onset of clinical disease is mainly IgG1. Acquisition of an IgG4 response is a key step in the development of clinical disease.

Increased astrocyte reactivity in the hippocampus of murine models of type 1 diabetes: the nonobese diabetic (NOD) and streptozotocin-treated mice

Diabetes can be associated with cerebral dysfunction in humans and animal models of the disease. Moreover, brain anomalies and alterations of the neuroendocrine system are present in type 1 diabetes (T1D) animals, such as the spontaneous nonobese diabetic (NOD) mouse model and/or the pharmacological streptozotocin (STZ)-induced model. Because of the prevalent role of astrocytes in cerebral glucose metabolism and their intimate connection with neurones, we investigated hippocampal astrocyte alterations in prediabetic and diabetic NOD mice and STZ-treated diabetic mice. The number and cell area related to the glial fibrillary acidic protein (GFAP)-immunoreactive astrocytes were quantified in the stratum radiatum region of the hippocampus by computerized image analysis in prediabetic (2, 4 and 8 weeks of age) and diabetic (16-week-old) NOD female mice, age and sex-matched lymphocyte-deficient NODscid and C57BL/6 control mice and, finally, STZ-induced diabetic and vehicle-treated nondiabetic 16-week-old C57BL/6 female mice. Astrocyte number was higher early in life in prediabetic NOD and NODscid mice than in controls, when transient hyperinsulinemia and low glycemia were found in these strains. The number and cell area of GFAP(+) cells further increased after the onset of diabetes in NOD mice. Similarly, in STZ-treated diabetic mice, the number of GFAP(+) cells and cell area were higher than in vehicle-treated mice. In conclusion, astrocyte changes present in genetic and pharmacological models of T1D appear to reflect an adaptive process to alterations of glucose homeostasis.

Granulocyte macrophage colony-stimulating factor: a new putative therapeutic target in multiple sclerosis

Experimental autoimmune encephalomyelitis (EAE), a model for multiple sclerosis, can be induced by immunization with a number of myelin antigens. In particular, myelin oligodendrocyte glycoprotein, a central nervous system (CNS)-specific antigen expressed on the myelin surface, is able to induce a paralytic MS-like disease with extensive CNS inflammation and demyelination in several strains of animals. Although not well understood, the egress of immune cells into the CNS in EAE is governed by a complex interplay between pro and antiinflammatory cytokines and chemokines. The hematopoietic growth factor, granulocyte macrophage colony-stimulating factor (GM-CSF), is considered to play a central role in maintaining chronic inflammation. The present study was designed to investigate the previously unexplored role of GM-CSF in autoimmune-mediated demyelination. GM-CSF(-/)- mice are resistant to EAE, display decreased antigen-specific proliferation of splenocytes, and fail to sustain immune cell infiltrates in the CNS, thus revealing key activities for GM-CSF in the development of inflammatory demyelinating lesions and control of migration and/or proliferation of leukocytes within the CNS. These results hold implications for the pathogenesis of inflammatory and demyelinating diseases and may provide the basis for more effective therapies for inflammatory diseases, and more specifically for multiple sclerosis.

Frequency, heterogeneity and encephalitogenicity of T cells specific for myelin oligodendrocyte glycoprotein in naive outbred primates

Auto-reactive T cells present in healthy subjects remain in a state of unresponsiveness, but may trigger autoimmunity under various situations. Although myelin oligodendrocyte glycoprotein (MOG) is a potential target antigen in multiple sclerosis (MS), MOG-reactive T cell responses are present in the blood of both healthy subjects and MS-affected individuals. To investigate the disease-inducing potential and regulation of these autoreactive T cells in healthy outbred populations, we have characterized MOG-reactive T cell clones obtained by limiting dilution from peripheral blood of unimmunized C. jacchus marmosets. We report an extraordinarily high prevalence of circulating MOG-reactive T cells in these naive animals (2.6 +/- 1.4 / 10(5) PBMC), and a broadly diverse repertoire of epitope recognition encompassing at least three regions within the extracellular domain of MOG. Adoptive transfer of a MOG21-40-specific T cell clone resulted in mild clinical experimental allergic encephalomyelitis, characterized pathologically by rare foci of inflammation and minimal demyelination. We conclude that MOG-reactive T cells are present in healthy primates at a highly prevalent frequency, and are potentially capable of triggering central nervous system autoimmunity. Expansion of these autoreactive T cells must be tightly controlled to maintain immune homeostasis in healthy individuals.

Brain-derived gangliosides suppress the chronic relapsing-remitting experimental autoimmune encephalomyelitis in NOD mice induced with myelin oligodendrocyte glycoprotein peptide

Chronic relapsing-remitting experimental autoimmune encephalomyelitis (CREAE) induced with myelin oligodendrocyte glycoprotein peptides 35-55 (MOG(35-55)) in NOD mice was successfully treated with brain-derived gangliosides (GA). The GA treatment suppressed the development and severity of CREAE, both clinically and histologically. Spleen cells from the GA-treated mice displayed markedly inhibited levels of MOG(35-55) specific proliferation and interferon-gamma production. Delayed-type hypersensitivity reactions to MOG(35-55) were suppressed by the GA treatment. GA modulate various T cell effector functions in CREAE and may be an effective therapeutic agent for autoimmune demyelinating diseases such as multiple sclerosis.

Requirement for leptin in the induction and progression of autoimmune encephalomyelitis

Recent evidence indicates that leptin modifies T cell immunity, and may provide a key link between nutritional deficiency and immune dysfunction. To study the influence of leptin on autoimmunity, susceptibility to experimental autoimmune encephalomyelitis induced by immunization with a myelin-derived peptide was examined in leptin-deficient, C57BL/6J-ob/ob mice, with or without leptin replacement, and in wild-type controls. Leptin replacement converted disease resistance to susceptibility in the C57BL/6J-ob/ob mice; this was accompanied by a switch from a Th2 to Th1 pattern of cytokine release and consequent reversal of Ig subclass production. Our findings suggest that leptin is required for the induction and maintenance of an effective proinflammatory immune response in the CNS.

Absence of monocyte chemoattractant protein 1 in mice leads to decreased local macrophage recruitment and antigen-specific T helper cell type 1 immune response in experimental autoimmune encephalomyelitis

Monocyte chemoattractant protein (MCP)-1 plays a critical role in innate immunity by directing the migration of monocytes into inflammatory sites. Recent data indicated a function for this chemokine in adaptive immunity as a regulator of T cell commitment to T helper cell type 2 (Th2) effector function. Studies in a Th1-dependent animal model, experimental autoimmune encephalomyelitis (EAE), showed that MCP-1 was highly expressed in the central nervous system (CNS) of affected rodents, and MCP-1 antibodies could block relapses of the disease. Mice deficient for the major MCP-1 receptor, CC chemokine receptor (CCR)2, did not develop EAE after active immunization but generated effector cells that could transfer the disease to naive wild-type recipients. We analyzed EAE in mice deficient for MCP-1 to define the relevant ligand for CCR2, which responds to murine MCP-1, MCP-2, MCP-3, and MCP-5. We found that C57BL/6 MCP-1-null mice were markedly resistant to EAE after active immunization, with drastically impaired recruitment of macrophages to the CNS, yet able to generate effector T cells that transferred severe disease to naive wild-type recipients. By contrast, adoptive transfer of primed T cells from wild-type mice into naive MCP-1-null recipients did not mediate clinical EAE. On the SJL background, disruption of the MCP-1 gene produced a milder EAE phenotype with diminished relapses that mimicked previous findings using anti-MCP-1 antibodies. There was no compensatory upregulation of MCP-2, MCP-3, or MCP-5 in MCP-1-null mice with EAE. These results indicated that MCP-1 is the major CCR2 ligand in mice with EAE, and provided an opportunity to define the role of MCP-1 in EAE. Compared with wild-type littermates, MCP-1-/- mice exhibited reduced expression of interferon gamma in draining lymph node and CNS and increased antigen-specific immunoglobulin G1 antibody production. Taken together, these data demonstrate that MCP-1 is crucial for Th1 immune responses in EAE induction and that macrophage recruitment to the inflamed CNS target organ is required for primed T cells to execute a Th1 effector program in EAE.

The myelin oligodendrocyte glycoprotein (MOG): a model for antibody-mediated demyelination in experimental autoimmune encephalomyelitis and multiple sclerosis

The myelin oligodendrocyte glycoprotein (MOG) is a major target for autoantibody mediated demyelination in experimental autoimmune encephalomyelitis (EAE). In the current review we discuss the epitope specificity of this antibody response, in particular evidence suggesting that pathogenic anti-MOG antibodies are preferentially directed against conformation-dependent epitopes present on the extracellular immunoglobulin domain of the protein. Surprisingly, recent data suggest that this autoimmune response is in part regulated by polymorphisms in the MOG gene itself, an observation that may have important implications for the genetic and immunological stratification of patients with multiple sclerosis.

Screening of several H-2 congenic mouse strains identified H-2(q) mice as highly susceptible to MOG-induced EAE with minimal adjuvant requirement

We identified H-2(q) as a susceptible genotype for MOG-induced EAE by systematic screening of a series of H-2 congenic B10 mouse strains. A series of H-2(q)-bearing strains with divergent gene backgrounds were subsequently investigated. DBA/1 mice were highly susceptible to MOG(1-125)- and MOG(79-96)-induced EAE in the absence of pertussis toxin. Immunisation with MOG(1-125) and MOG(79-96) induced an autoreactive T-cell response in DBA/1 mice. Brain histopathology revealed T-cell and macrophage-infiltrated lesions with associated demyelination. The important features which make this an appropriate model of human disease are high sensitivity to MOG and dependence of an immunodominant peptide region homologous to that implicated in multiple sclerosis.

Mast cells are essential for early onset and severe disease in a murine model of multiple sclerosis

In addition to their well characterized role in allergic inflammation, recent data confirm that mast cells play a more extensive role in a variety of immune responses. However, their contribution to autoimmune and neurologic disease processes has not been investigated. Experimental allergic encephalomyelitis (EAE) and its human disease counterpart, multiple sclerosis, are considered to be CD4(+) T cell-mediated autoimmune diseases affecting the central nervous system. Several lines of indirect evidence suggest that mast cells could also play a role in the pathogenesis of both the human and murine disease. Using a myelin oligodendrocyte glycoprotein (MOG)-induced model of acute EAE, we show that mast cell-deficient W/W(v) mice exhibit significantly reduced disease incidence, delayed disease onset, and decreased mean clinical scores when compared with their wild-type congenic littermates. No differences were observed in MOG-specific T and B cell responses between the two groups, indicating that a global T or B cell defect is not present in W/W(v) animals. Reconstitution of the mast cell population in W/W(v) mice restores induction of early and severe disease to wild-type levels, suggesting that mast cells are critical for the full manifestation of disease. These data provide a new mechanism for immune destruction in EAE and indicate that mast cells play a broader role in neurologic inflammation.

Anti-IL-12 antibody prevents the development and progression of multiple sclerosis-like relapsing--remitting demyelinating disease in NOD mice induced with myelin oligodendrocyte glycoprotein peptide

Treatment with monoclonal anti-IL-12 antibody injected on day 0, 7 and 10 after immunization with myelin oligodendrocyte glycoprotein (MOG) peptide 35-55 in NOD mice resulted in significant suppression of the development and the severity of the chronic relapsing-remitting experimental autoimmune encephalomyelitis (EAE) both clinically and histologically. The spleen cells from anti-IL-12 antibody treated mice displayed markedly inhibited MOG35-55 specific proliferation and IFN-gamma production. MOG35-55 specific antibody production was enhanced by anti-IL-12 antibody treatment. These results suggest that IL-12 is critically involved in the pathogenesis of MOG-induced EAE and that antibody to IL-12 could be an effective therapeutic agent in the clinical treatment of autoimmune demyelinating diseases such as multiple sclerosis (MS).