Kit (W-sh) mice develop earlier and more severe experimental autoimmune encephalomyelitis due to absence of immune suppression.

Mast cells (MCs) have been thought to play a pathogenic role in the development of autoimmune diseases, including experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis. However, an immunoregulatory function of these cells has recently been suggested. We investigated the role of MCs in EAE using the W(-sh) mouse strain, which is MC deficient. W(-sh) mice developed earlier and more severe clinical and pathological disease with extensive demyelination and inflammation in the CNS. The inflammatory cells were mainly composed of CD4(+) T cells, monocyte/macrophages, neutrophils, and dendritic cells. Compared with wild-type mice, MC-deficient mice exhibited an increased level of MCP-1/CCR2 and CD44 expression on CD4(+) T cells in addition to decreased production of regulatory T cells, IL-4, IL-5, IL-27, and IL-10. We also found that levels of IL-17, IFN-γ, and GM-CSF were significantly increased in peripheral lymphocytes from immunized W(-sh) mice compared with those in peripheral lymphocytes from wild-type mice. Reconstitution of W(-sh) mice downregulated susceptibility to EAE, which correlated with MC recruitment and regulatory T cell activation in the CNS. These findings indicate that responsiveness is not required in the pathogenesis of inflammatory demyelination in the CNS and that, in the absence of MCs, increased MCP-1, CCR2, IL-17, IFN-γ, CD44, and other inflammatory molecules may be responsible for increased severity of EAE.

Cutting edge: critical role for PYCARD/ASC in the development of experimental autoimmune encephalomyelitis.

Multiple sclerosis is an autoimmune disease in which self-reactive T cells attack oligodendrocytes that myelinate axons in the CNS. Experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis, is dependent on caspase-1; however, the role of Nod-like receptors upstream of caspase-1 is unknown. Danger- and pathogen-associated molecular patterns activate Nod-like receptor 3, which activates caspase-1 through the adaptor protein, apoptosis-associated speck-like protein containing CARD (ASC). We report that the progression of EAE is dependent on ASC and caspase-1 but not Nod-like receptor 3. ASC(-/-) mice were even more protected from the progression of EAE than were caspase-1(-/-) mice, suggesting that an inflammasome-independent function of ASC contributes to the progression of EAE. We found that CD4(+) T cells deficient in ASC exhibited impaired survival; accordingly, ASC(-/-) mice had fewer myelin oligodendrocyte glycoprotein-specific T cells in the draining lymph nodes and CNS.

Systemic inflammatory response reactivates immune-mediated lesions in rat brain.

The potential association between microbial infection and reactivation of a multiple sclerosis (MS) lesion is an important issue that remains unresolved, primarily because of the absence of suitable animal models and imaging techniques. Here, we have evaluated this question in an empirical manner using immunohistochemistry and magnetic resonance imaging (MRI), before and after the induction of a systemic inflammatory response in two distinct models of MS. In a pattern-II-type focal myelin oligodendrocyte glycoprotein-experimental autoimmune encephalomyelitis model, systemic endotoxin injection caused an increase in regional cerebral blood volume (rCBV) around the lesion site after 6 h, together with a reduction in the magnetization transfer ratio of the lesioned corpus callosum. These changes were followed by an increase in the diffusion of tissue water within the lesion 24 h after endotoxin challenge and new leukocyte recruitment as revealed both immunohistochemically and by MRI tracking of ultrasmall superparamagnetic iron oxide-labeled macrophages. Importantly, we detected in vivo expression of E- and P-selectin in quiescent lesions by MRI-detectable glyconanoparticles conjugated to sialyl Lewis(X). This finding may explain, at least in part, the ability of quiescent MS lesions to rapidly reinitiate the cell recruitment processes. In a pattern-I-type delayed-type hypersensitivity response model, a similar effect of endotoxin challenge on rCBV was observed, together with delayed breakdown of the blood-brain barrier, showing that systemic infection can alter the pathogenesis of MS-like lesions regardless of lesion etiology. These findings will have important implications for the management and monitoring of individuals with MS.

Pattern of axonal injury in murine myelin oligodendrocyte glycoprotein induced experimental autoimmune encephalomyelitis: implications for multiple sclerosis.

Axonal damage is a correlate for increasing disability in multiple sclerosis. Animal models such as experimental autoimmune encephalomyelitis (EAE) may help to develop better therapeutical neuroprotective strategies for the human disease. Here we investigate the pattern of axonal injury in murine myelin oligodendrocyte glycoprotein peptide 35-55 (MOG) induced EAE. Inflammatory infiltration, axonal densities and expression of amyloid precursor protein (APP), neurofilaments (SMI31 and 32) as well as expression of sodium channels were quantified in lesions, the perilesional area and normal appearing white matter (NAWM). Quantification of T cells and macrophages revealed a significant reduction of inflammatory infiltration at later disease stages despite an increase of demyelinated areas and persistent clinical disability. In lesions, axonal density was already significantly reduced early and throughout all investigated disease stages. A significant axonal loss was also seen in the grey matter and at later time points in the perilesion as well as NAWM. Numbers of axons characterized by non-phosphorylated neurofilaments and re-distribution of sodium channels 1.2 and 1.6 increased over the course of MOG-EAE whilst APP positive axons peaked at the maximum of disease. Finally, double-labeling experiments revealed a strong colocalization of sodium channels with APP, neurofilaments and the axonal nodal protein Caspr, but not glial and myelin markers in actively demyelinating lesions. In summary, progressive axonal loss distant from lesions is mainly associated with changes in neurofilament phosphorylation, re-distribution of sodium channels and demyelination. This axonal loss is dissociated from acute inflammatory infiltration and markedly correlates with clinical impairment. Consequently, therapeutic intervention may be promising at early stages of EAE focusing on inflammation, or later in disease targeting degenerative mechanisms.

Novel role for SLPI in MOG-induced EAE revealed by spinal cord expression analysis.

BACKGROUND: Experimental autoimmune encephalomyelitis (EAE) induced by myelin oligodendrocyte protein (MOG) in female Dark Agouti (DA) rats is a chronic demyelinating animal model of multiple sclerosis (MS). To identify new candidate molecules involved in the evolution or repair of EAE-lesions we used Affymetrix oligonucleotide microarrays to compare the spinal cord transcriptome at the peak of EAE, during remission and at the first relapse with healthy DA rats. METHODS: Untreated DA rats and DA rats immunised with MOG protein were sacrificed at defined time points. Total RNA was isolated from spinal cord tissue and used for hybridization of Affymetrix rat genome arrays RG U34 A-C. Selected expression values were confirmed by RealTime PCR. Adult neural stem cells were incubated with recombinant secretory leukocyte protease inhibitor (SLPI). Proliferation was assessed by BrdU incorporation, cyclin D1 and HES1 expression by RealTime PCR, cell differentiation by immunofluorescence analysis and I kappa B alpha degradation by Western blot. RESULTS: Among approximately 26,000 transcripts studied more than 1,100 were differentially regulated. Focussing on functional themes, we noticed a sustained downregulation of most of the transcripts of the cholesterol biosynthesis pathway. Furthermore, we found new candidate genes possibly contributing to regenerative processes in the spinal cord. Twelve transcripts were solely upregulated in the recovery phase, including genes not previously associated with repair processes. Expression of SLPI was upregulated more than hundredfold during EAE attack. Using immunohistochemistry, SLPI was identified in macrophages, activated microglia, neuronal cells and astrocytes. Incubation of adult neural stem cells (NSC) with recombinant SLPI resulted in an increase of cell proliferation and of differentiation towards oligodendrocytes. These processes were paralleled by an upregulation of the cell-cycle promotor cyclin D1 and a suppression of the cell differentiation regulator HES1. Finally, SLPI prevented the degradation of I kappa B alpha, which may explain the suppression of the cell differentiation inhibitor HES1 suggesting a possible mechanism of oligodendroglial differentiation. CONCLUSION: We identified novel features of gene expression in the CNS during EAE, in particular the suppression of genes of cholesterol biosynthesis and a strong upregulation of SLPI, a gene which is for the first time associated with autoimmune inflammation. The capacity of SLPI to increase proliferation of adult NSC and of oligodendroglial differentiation suggests a novel role for SLPI in the promotion of tissue repair, beyond its known functions in the prevention of tissue damages by protease inhibition damage and modulation of inflammatory reactions.

Depletion of autoreactive B-lymphocytes by a recombinant myelin oligodendrocyte glycoprotein-based immunotoxin.

We report the construction of a fusion protein comprising the extracellular domain of myelin oligodendrocyte glycoprotein (MOG) and a truncated version of Pseudomonas aeruginosa exotoxin A (ETA'). The chimeric immunotoxin targeted MOG-reactive B-lymphocytes by binding selectively to the appropriate receptors, leading to internalization and apoptosis of the target cells. The functionality of the immunotoxin was tested on a MOG-sensitive murine hybridoma cell line and ex vivo on freshly isolated splenocytes from transgenic IgH(MOG) mice. These data demonstrate, for the first time, the specific cytotoxicity of a MOG-containing recombinant immunotoxin expressed in bacteria towards MOG-reactive B-lymphocytes.

Temporal expression and cellular origin of CC chemokine receptors CCR1, CCR2 and CCR5 in the central nervous system: insight into mechanisms of MOG-induced EAE.

BACKGROUND: The CC chemokine receptors CCR1, CCR2 and CCR5 are critical for the recruitment of mononuclear phagocytes to the central nervous system (CNS) in multiple sclerosis (MS) and other neuroinflammatory diseases. Mononuclear phagocytes are effector cells capable of phagocytosing myelin and damaging axons. In this study, we characterize the regional, temporal and cellular expression of CCR1, CCR2 and CCR5 mRNA in the spinal cord of rats with myelin oligodendrocyte glycoprotein-induced experimental autoimmune encephalomyelitis (MOG-EAE). While resembling human MS, this animal model allows unique access to CNS-tissue from various time-points of relapsing neuroinflammation and from various lesional stages: early active, late active, and inactive completely demyelinated lesions. METHODS: The expression of CCR1, CCR2 and CCR5 mRNA was studied with in situ hybridization using radio labelled cRNA probes in combination with immunohistochemical staining for phenotypic cell markers. Spinal cord sections from healthy rats and rats with MOG-EAE (acute phase, remission phase, relapse phase) were analysed. In defined lesion stages, the number of cells expressing CCR1, CCR2 and CCR5 mRNA was determined. Data were statistically analysed by the nonparametric Mann-Whitney U test. RESULTS: In MOG-EAE rats, extensive up-regulation of CCR1 and CCR5 mRNA, and moderate up-regulation of CCR2 mRNA, was found in the spinal cord during episodes of active inflammation and demyelination. Double staining with phenotypic cell markers identified the chemokine receptor mRNA-expressing cells as macrophages/microglia. Expression of all three receptors was substantially reduced during clinical remission, coinciding with diminished inflammation and demyelination in the spinal cord. Healthy control rats did not show any detectable expression of CCR1, CCR2 or CCR5 mRNA in the spinal cord. CONCLUSION: Our results demonstrate that the acute and chronic-relapsing phases of MOG-EAE are associated with distinct expression of CCR1, CCR2, and CCR5 mRNA by cells of the macrophage/microglia lineage within the CNS lesions. These data support the notion that CCR1, CCR2 and CCR5 mediate recruitment of both infiltrating macrophages and resident microglia to sites of CNS inflammation. Detailed knowledge of expression patterns is crucial for the understanding of therapeutic modulation and the validation of CCR1, CCR2 and CCR5 as feasible targets for therapeutic intervention in MS.

Epitope spread is not critical for the relapse and progression of MOG 8-21 induced EAE in Biozzi ABH mice.

Emerging autoimmunity (epitope-spreading) generated as a consequence of myelin damage is suggested to underlie the relapses in multiple sclerosis (MS). Myelin oligodendrocyte glycoprotein (MOG 8-21) induces relapsing EAE in ABH mice characterized by broadening of the autoimmune reportoire. Despite epitope spreading tolerance to the priming antigen, but not emerging epitope reactivities, resulted in long-term inhibition of clinical relapse. In contrast, spinal cord homogenate induced EAE was dominated by a proteolipid protein (PLP 56-70) autoreactivity despite the plethora of CNS antigens in the immunogen. This data suggests that during relapsing-remitting demyelinating disease the pathogenic process is dominated by the initiating antigen, with only a minor role played by emerging T-cell populations. These findings may have important implications for the efficacy of antigen-based immune therapies in autoimmune disorders.

Treatment with chimeric anti-human CD40 antibody suppresses MRI-detectable inflammation and enlargement of pre-existing brain lesions in common marmosets affected by MOG-induced EAE.

Common marmosets, a Neotropical monkey species, are protected against clinical and neuropathological consequences of experimentally induced autoimmune encephalomyelitis (EAE) by prophylactic treatment with ch5D12, a humanized antagonist antibody against human CD40. In the current study we have tested whether ch5D12 acts therapeutically against the enlargement and inflammatory activity of existing (brain) white matter lesions using serial magnetic resonance imaging (MRI). The results show in all PBS treated monkeys (n=4) a rapid enlargement of T2 lesions together with an increment of the T2 signal intensity due to inflammatory edema. Treatment with ch5D12 delayed the enlargement of T2 lesions in 2 out of 3 tested monkeys while in 3 out of 3 monkeys the T2 signal increment of lesions was suppressed. In conjunction with previously published data on the clinical benefit of anti-CD40 treatment in the marmoset EAE model, the current findings support antibody-mediated blockade of CD40 interaction with its ligand CD154 as a potential treatment of MS.

Targeting fibroblast growth factor-inducible-14 signaling protects from chronic relapsing experimental autoimmune encephalomyelitis.

The TNF-related weak inducer of apoptosis (TWEAK) is a TNF family member mediating proinflammatory effects by its receptor fibroblast growth factor-inducible-14 (Fn14). We studied the role of TWEAK/Fn14 in experimental autoimmune encephalomyelitis (EAE) by protein vaccination with TWEAK and Fn14 and recombinant TWEAK-DNA, respectively. TWEAK-DNA vaccination worsened the clinical course of EAE and increased central nervous system (CNS) inflammation. TWEAK increased the secretion of CCL2 [monocyte chemotactic protein-1 (MCP-1)] by CNS endothelial cells and astrocytes in vitro, suggesting CCL2 as a critical mediator of TWEAKs proinflammatory effects. Vaccination with the extracellular domain of TWEAK or with Fn14 resulted in the induction of specific inhibitory antibodies and an amelioration of EAE signs in two different models in rats and mice. Spinal cord inflammatory infiltrates were significantly diminished. Purified IgG from TWEAK- or Fn14-vaccinated rats prevented TWEAK-induced production of CCL2 by endothelial cells. Blocking Fn14 signaling represents a novel approach with potential for the treatment of CNS autoimmunity.

Analysis of gene expression in MOG-induced experimental autoimmune encephalomyelitis after treatment with a novel brain-penetrating antioxidant.

Accumulating data from experimental studies indicate that oxidative stress has a major role in the pathogenesis of multiple sclerosis (MS). It has been suggested that local production of reactive oxygen species, probably by macrophages, mediates axonal damage in both MS patients and the mouse model experimental autoimmune encephalomyelitis (EAE). We have shown previously that our novel brain-penetrating antioxidant, N-acetylcysteine amide (AD4), reduces the clinical and pathological symptoms, including inflammation and axonal damage in myelin oligodendrocyte glycoprotein (MOG)-induced chronic EAE in mice. The aim of this study was to examine the molecular mechanism by which AD4 exerts protection in MOG-induced EAE mice. Therefore, we analyzed gene-expression profile in the spinal cords of MOG-induced chronic EAE mice and compared them with MOG-induced mice treated with AD4, using a cDNA microarray. We found that MOG treatment up-regulated genes encoding growth factors, cytokines, death receptors, proteases, and myelin structure proteins, whereas MOG- and AD4-treated mice demonstrated gene expression profiles similar to that seen in naive healthy mice. In conclusion, our study shows that chronic AD4 administration suppresses the induction of various pathological pathways that play a role in EAE and probably in MS.

B cell recognition of myelin oligodendrocyte glycoprotein autoantigen depends on immunization with protein rather than short peptide, while B cell invasion of the CNS in autoimmunity does not.

We develop a new fusion protein reagent (MOGtag), based on the extracellular domain of mouse myelin oligodendrocyte glycoprotein (MOG1-125), designed to induce autoimmune responses in mice that incorporates both T and B cell recognition of antigen. Reports of similar reagents, primarily based on foreign MOG proteins, rely largely on disease incidence and severity, with little analysis of the underlying immune response or pathology. We characterize the immune response and central nervous system autoimmune disease elicited by MOGtag in mice and find that it results in the formation of a T cell-dependent germinal center B cell response. Unlike immunization with the short MOG35-55 peptide, this response incorporated B cells able to recognize MOG protein. The autoimmune disease resulting from immunization with MOGtag was chronic with clear evidence of an ongoing immune response and active white and gray matter infiltration by T cells as well as formation of B cell clusters in the meninges. Interestingly, development of B cell clusters was not absolutely dependent on the ability of B cells to recognize MOG protein, as they were also present in mice immunized with short peptide and in mice with a mutant B cell receptor specific for an irrelevant antigen.

Neural stem cells: a potential source for remyelination in neuroinflammatory disease.

In multiple sclerosis, the central nervous system is lesioned through invasion of plaque-forming inflammatory cells, primarily contributing to immune attack of myelin and oligodendrocytes. In this report we address the possible activation and differentiation of central nervous system stem cells following such immunological insults in a well-characterized rat model of multiple sclerosis characterised by spinal cord pathology. Dye-labeled central nervous system stem cells, residing within the ependymal layer of the central canal responded to the multiple sclerosis-like conditions by proliferation, while some of the migrating stem cell-derived cells expressed markers typical for oligodendrocytes (04) and astrocytes (glial fibrillary acidic protein, GFAP) in the demyelinated area. Our results indicate that regenerative stem cell activation following immunoactivity is different from that after trauma, exemplified by the slower time course of stem cell proliferation and migration of progeny, in addition to the ability of the stem cell-derived cells to express oligodendrocyte markers. Finally, deleterious effects of macrophages on the stem cell population were evident and may contribute to the depletion of the stem cell population in neuroinflammatory disorders.

Effector stage CC chemokine receptor-1 selective antagonism reduces multiple sclerosis-like rat disease.

We have studied the role of the chemokine receptor CCR1 during the effector stage of myelin oligodendrocyte glycoprotein-induced experimental autoimmune encephalomyelitis in DA rats. In situ hybridization histochemistry revealed local production of the CCR1 ligands CCL3 (MIP-1 alpha) and CCL5 (RANTES), as well as large numbers of CCR1 and CCR5 expressing cells within inflammatory brain lesions. A low-molecular weight CCR1 selective antagonist potently abrogated both clinical and histopathological disease signs during a 5-day treatment period, without signs of peripheral immune compromise. Thus, we demonstrate therapeutic targeting of CCR1-dependent leukocyte recruitment to the central nervous system in a multiple sclerosis (MS)-like rat model.

TBI and sex: crucial role of progesterone protecting the brain in an omega-3 deficient condition.

We assessed whether the protective action of progesterone on traumatic brain injury (TBI) could be influenced by the consumption of omega-3 fatty acids during early life. Pregnant Sprague-Dawley rats were fed on omega-3 adequate or deficient diet from 3rd day of pregnancy and their female offspring were kept on the same diets up to the age of 15 weeks. Ovariectomy was performed at the age of 12 weeks to deprive animals from endogenous steroids until the time of a fluid percussion injury (FPI). Dietary n-3 fatty acid deficiency increased anxiety in sham animals and TBI aggravated the effects of the deficiency. Progesterone replacement counteracted the effects of TBI on the animals reared under n-3 deficiency. A similar pattern was observed for markers of membrane homeostasis such as 4-Hydroxynonenal (HNE) and secreted phospholipases A2 (sPLA2), synaptic plasticity such as brain derived neurotrophic factor (BDNF), syntaxin (STX)-3 and growth associated protein (GAP)-43, and for growth inhibitory molecules such as myelin-associated glycoprotein (MAG) and Nogo-A. Results that progesterone had no effects on sham n-3 deficient animals suggest that the availability of progesterone is essential under injury conditions. Progesterone treatment counteracted several parameters related to synaptic plasticity and membrane stability reduced by FPI and n-3 deficiency suggest potential targets for therapeutic applications. These results reveal the importance of n-3 preconditioning during early life and the efficacy of progesterone therapy during adulthood to counteract weaknesses in neuronal and behavioral plasticity.

Distinct spatiotemporal pattern of CNS lesions revealed by USPIO-enhanced MRI in MOG-induced EAE rats implicates the involvement of spino-olivocerebellar pathways.

USPIO-enhanced MRI allows non-invasive visualization of mononuclear cell infiltration into CNS lesions in MS and EAE. Herein, we show a distinct spatiotemporal pattern of CNS lesions that reveals the involvement of spino-olivocerebellar pathways in MOG-induced EAE rats using USPIO-enhanced MRI. Specifically, lesions of the inferior olives were observed primarily in the acute phase whereas lesions of cerebellum or spinal cord/brainstem were observed during the relapse phase. Further, behavioral deficits observed from these animals are consistent with the functional role of spino-olivocerebellar pathways in coordination and movement. Collectively, our results provide new insights into the pathophysiology of this animal model of MS.

Effect of MOG sensitization on somatosensory evoked potential in Lewis rats.

Myelin oligodendrocyte glycoprotein (MOG) is commonly used as an immunogen to induce an immune response against endogenous myelin, thereby modeling multiple sclerosis in rodents. When MOG is combined with complete Freund's adjuvant (CFA), multifocal, multiphasic disease ensues; whereas when MOG is combined with incomplete Freund's adjuvant (IFA), clinical disease is usually absent. MOG-IFA immunized animals can be induced to have neurological disease after intraspinal injections of cytokines and ethidium bromide (EtBr). In this study, we investigated whether MOG-IFA immunized rats exhibited subclinical injury as defined by somatosensory evoked potential (SEP) recordings. The titration of anti-MOG-125 antibodies showed robust peripheral mounting of immune response against myelin in MOG-immunized rats. However the SEP measures showed no significant change over time. Upon injecting cytokine-EtBr in the spinal cord after MOG sensitization, the SEP recordings showed reduced amplitude and prolonged latency, suggestive of axonal injury and demyelination in the dorsal column, respectively. These findings were later confirmed using T2-weighted MRI and histological hematoxylin-eosin stain of the spinal cord. This report establishes that MOG-IFA immunization alone does not alter neuronal conduction in SEP-related neural-pathways and that longitudinal in-vivo SEP recordings provide a sensitive read-out for focal myelitis (MOG-IFA and intraspinal cytokine-EtBr) in rats.

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.

IL-23 is critical in the induction but not in the effector phase of experimental autoimmune encephalomyelitis.

Experimental autoimmune encephalomyelitis (EAE), a T cell-mediated inflammatory disease of the CNS, is a rodent model of human multiple sclerosis. IL-23 is one of the critical cytokines in EAE development and is currently believed to be involved in the maintenance of encephalitogenic responses during the tissue damage effector phase of the disease. In this study, we show that encephalitogenic T cells from myelin oligodendrocyte glycopeptide (MOG)-immunized wild-type (WT) mice caused indistinguishable disease when adoptively transferred to WT or IL-23-deficient (p19 knockout (KO)) recipient mice, demonstrating that once encephalitogenic cells have been generated, EAE can develop in the complete absence of IL-23. Furthermore, IL-12/23 double-deficient (p35/p19 double KO) recipient mice developed EAE that was indistinguishable from WT recipients, indicating that IL-12 did not compensate for IL-23 deficiency during the effector phase of EAE. In contrast, MOG-specific T cells from p19KO mice induced EAE with delayed onset and much lower severity when transferred to WT recipient mice as compared with the EAE that was induced by cells from WT controls. MOG-specific T cells from p19KO mice were highly deficient in the production of IFN-gamma, IL-17A, and TNF, indicating that IL-23 plays a critical role in development of encephalitogenic T cells and facilitates the development of T cells toward both Th1 and Th17 pathways.

A critical role of LFA-1 in the development of Th17 cells and induction of experimental autoimmune encephalomyelytis.

The alphaLbeta2 integrin adhesion molecule LFA-1 is believed to be involved in the migration of autoreactive T cells to the central nervous system across the endothelial blood-brain barrier in experimental autoimmune encephalomyelitis (EAE). Here, we demonstrate that the incidence and clinical scores of EAE in LFA-1-/- mice induced by the immunization with the myelin oligodendrocyte glycoprotein (MOG)-peptide antigen were significantly lower than those in wild type mice. Further studies demonstrated that lymphocytes recruitment to the draining lymph nodes (dLN) after the immunization with the MOG-peptide was severely suppressed in LFA-1-/- mice. Moreover, generation of the MOG-specific IL-17-producing helper T (Th17) cells in the dLN was impaired in LFA-1-/- mice. These results suggest that LFA-1 may play an important role for the generation of MOG-specific Th17 cells in the dLN as well as the immigration of MOG-specific naïve CD4+ T cells to the dLN.