Recombinant TCR ligand reverses clinical signs and CNS damage of EAE induced by recombinant human MOG.

Increasing evidence suggests that in addition to T cell-dependent effector mechanisms, autoantibodies are also involved in the pathogenesis of MS, including demyelinating antibodies specific for myelin oligodendrocyte glycoprotein (MOG). Our previous studies have demonstrated that recombinant T cell receptor ligands (RTLs) are very effective for treating T cell-mediated experimental autoimmune encephalomyelitis (EAE). In order to expand the scope of RTL therapy in MS patients, it was of interest to study RTL treatment of EAE involving a demyelinating antibody component. Therefore, we evaluated the therapeutic effects of RTL551, specific for T cells reactive to mouse (m)MOG-35-55 peptide, on EAE induced with recombinant human (rh)MOG in C57BL/6 mice. We report that RTL551 therapy can reverse disease progression and reduce demyelination and axonal damage induced by rhMOG without suppressing the anti-MOG antibody response. This result suggests that T cell-mediated inflammation and associated blood-brain barrier dysfunction are the central contributors to EAE pathogenesis and that successful regulation of these key players restricts potential damage by demyelinating antibodies. The results of our study lend support for the use of RTL therapy for treatment of MS subjects whose disease includes inflammatory T cells as well as those with an additional antibody component.

Fragment 101-108 of myelin oligodendrocyte glycoprotein: a possible lead compound for multiple sclerosis.

Multiple Sclerosis (MS) is a highly invalidating autoimmune disease of the central nervous system, leading to progressive paralysis and, sometimes, to premature death. One of the potential targets of the autoimmune reaction is the myelin protein MOG (Myelin Oligodendrocyte Glycoprotein). Since the 101-108 fragment of MOG plays a key role in the interaction with the MS-autoantibody 8-18C5, we performed an analysis of the equilibrium conformations of this peptide using the Replica Exchange Molecular Dynamics technique in conjunction with the Generalized Born continuum solvent model. Four variants of the peptide, stabilized by a disulfide bond, were also studied. We found that a significant fraction of the equilibrium population retains the original beta-hairpin conformation, and the amount of crystal-like conformations increases in the disulfide-closed analogues. When the equilibrium structures were used in docking simulations with the 8-18C5 autoantibody, we discovered the existence of a docking funnel whose bottom is populated by stable complexes where the peptide occupies the same region of space that was occupied in the crystal. It follows that the MOG 101-108 fragment represents a promising starting point for the design of a drug capable of blocking the 8-18C5 antibody. The molecule may also be used for the development of a diagnostic assay for multiple sclerosis.

Axonal protective effects of the myelin-associated glycoprotein.

Progressive axonal degeneration follows demyelination in many neurological diseases, including multiple sclerosis and inherited demyelinating neuropathies, such as Charcot-Marie-Tooth disease. One glial molecule, the myelin-associated glycoprotein (MAG), located in the adaxonal plasmalemma of myelin-producing cells, is known to signal to the axon and to modulate axonal caliber through phosphorylation of axonal neurofilament proteins. This report establishes for the first time that MAG also promotes resistance to axonal injury and prevents axonal degeneration both in cell culture and in vivo. This effect on axonal stability depends on the RGD domain around arginine 118 in the extracellular portion of MAG, but it is independent of Nogo signaling in the axon. Exploiting this pathway may lead to therapeutic strategies for neurological diseases characterized by axonal loss.

Myelin-associated glycoprotein reduces axonal branching and enhances functional recovery after sciatic nerve transection in rats.

The mature peripheral nervous system (PNS) generally shows better regeneration of injured axons as opposed to the central nervous system (CNS). However, complete functional recovery is rarely achieved even in the PNS although morphologically good axonal regeneration often occurs. This mainly results from aberrant reinnervation due to extensive branching of cut axons with consequent failure of synchronized movements of the muscles. Myelin-associated glycoprotein (MAG), a well-characterized molecule existing both in the CNS and PNS myelin, is considered to be a potent inhibitor of axonal regeneration especially in the CNS. In the present study, we investigated whether MAG has any effects not only on axonal elongation, but also on axonal branching. We show herein that MAG minimized branching of the peripheral axons both in vitro and in vivo via activation of RhoA. Furthermore, after sciatic nerve transection in rats, focal and temporary application of MAG to the lesion dramatically enhanced the functional recovery. Using double retrograde labeling and preoperative/postoperative labeling of spinal neurons, reduced hyperinnervation and improved accuracy of target reinnervation was confirmed, respectively. In conclusion, as MAG significantly improves the quality of axonal regeneration, it can be used as a new therapeutic approach for peripheral nerve repair with possible focal and temporary application.

Involvement of regulatory T cells in the experimental autoimmune encephalomyelitis-preventive effect of dendritic cells expressing myelin oligodendrocyte glycoprotein plus TRAIL.

We previously reported the protection from myelin oligodendrocyte glycoprotein (MOG)-induced experimental autoimmune encephalomyelitis (EAE) by the adoptive transfer of genetically modified embryonic stem cell-derived dendritic cells (ES-DC) presenting MOG peptide in the context of MHC class II molecules and simultaneously expressing TRAIL (ES-DC-TRAIL/MOG). In the present study, we found the severity of EAE induced by another myelin autoantigen, myelin basic protein, was also decreased after treatment with ES-DC-TRAIL/MOG. This preventive effect diminished, if the function of CD4(+)CD25(+) regulatory T cells (Treg) was abrogated by the injection of anti-CD25 mAb into mice before treatment with ES-DC-TRAIL/MOG. The adoptive transfer of CD4(+)CD25(+) T cells from ES-DC-TRAIL/MOG-treated mice protected the recipient mice from MOG- or myelin basic protein-induced EAE. The number of Foxp3(+) cells increased in the spinal cords of mice treated with ES-DC-TRAIL/MOG. In vitro experiments showed that TRAIL expressed in genetically modified ES-DC and also in LPS-stimulated splenic macrophages had a capacity to augment the proliferation of CD4(+)CD25(+) T cells. These results suggest that the prevention of EAE by treatment with ES-DC-TRAIL/MOG is mediated, at least in part, by MOG-reactive CD4(+)CD25(+) Treg propagated by ES-DC-TRAIL/MOG. For the treatment of organ-specific autoimmune diseases, induction of Treg reactive to the organ-specific autoantigens by the transfer of DC-presenting Ags and simultaneously overexpressing TRAIL therefore appears to be a promising strategy.

Neurogenesis and neuroprotection induced by peripheral immunomodulatory treatment of experimental autoimmune encephalomyelitis.

Brain insults such as the autoimmune inflammatory process in multiple sclerosis (MS) and experimental autoimmune encephalomyelitis (EAE) induce a measure of neurogenesis, but its regenerative therapeutic consequence is limited, because it fails to regenerate functional neurons and compensate the damage. Here, we investigated whether peripheral immunomodulatory treatment for MS/EAE, glatiramer acetate (GA), can enhance neurogenesis and generate neuroprotection in the CNS of EAE-inflicted mice. EAE was induced by myelin oligodendrocyte glycoprotein peptide, either in yellow fluorescent protein (YFP) 2.2 transgenic mice, which selectively express YFP on their neuronal population, or in C57BL/6 mice. The in situ effect of GA was studied in various brain regions; neuroprotection and neurogeneration were evaluated and quantified by measuring the expression of different neuronal antigens and in vivo proliferation markers. The results demonstrated that in EAE-inflicted mice, neuroproliferation was initially elevated after disease appearance but subsequently declined below that of naive mice. In contrast, GA treatment in various stages of the disease led to sustained reduction in the neuronal/axonal damage typical to the neurodegenerative disease course. Moreover, three processes characteristic of neurogenesis, namely cell proliferation, migration, and differentiation, were augmented and extended by GA treatment in EAE mice compared with EAE-untreated mice and naive controls. The newborn neuroprogenitors manifested massive migration through exciting and dormant migration pathways, into injury sites in brain regions, which do not normally undergo neurogenesis, and differentiated to mature neuronal phenotype. This suggests a direct linkage between immunomodulation, neurogenesis, and an in situ therapeutic consequence in the CNS.

Immunization with myelin or recombinant Nogo-66/MAG in alum promotes axon regeneration and sprouting after corticospinal tract lesions in the spinal cord.

We have shown previously that immunization with myelin in incomplete Freund's adjuvant (IFA) is able to promote robust regeneration of corticospinal tract fibers in adult mice. In the present study the effectiveness of such immunization with myelin was compared to that of a combination of two axon growth inhibitors in myelin, Nogo-66 (the 66-amino-acid inhibitory region of Nogo-A) and myelin-associated glycoprotein (MAG). The effectiveness of two adjuvants, IFA and aluminum hydroxide (Alum), was also compared, the latter being one that can be used in humans. In addition, larger dorsal overhemisections were made at the lower thoracic level, which resulted in a larger scar. These studies were carried out in SJL/J mice, a mouse strain that is susceptible to autoimmune experimental allergic encephalomyelitis (EAE). None of the immunized mice developed EAE. Long-distance axon regeneration and sprouting of the corticospinal tract was seen in myelin and Nogo-66/MAG immunized mice. Alum was as effective or better than IFA as the adjuvant. Overall, the robustness of axon growth and sprouting was greater in mice immunized with myelin. The abundance of this growth was less than in our earlier work in which smaller lesions were made, pointing to the possible influence of inhibitors in the scar. This work shows, however, that axon growth inhibitors in myelin can be selectively blocked using this immunization approach to promote long-distance axon regeneration in the spinal cord.

Treatment of depression is associated with suppression of nonspecific and antigen-specific T(H)1 responses in multiple sclerosis.

OBJECTIVE: To examine the relationship between depression, treatment of depression, and interferon gamma (IFN-gamma) production by peripheral blood mononuclear cells in patients with comorbid diagnoses of relapsing-remitting multiple sclerosis (MS) and major depressive disorder. DESIGN: A randomized comparative outcome trial of three 16-week treatments for depression. Assessments were conducted at baseline, week 8, and treatment cessation. SETTING: An academic outpatient treatment and clinical research center. PATIENTS: Fourteen patients who met the criteria for relapsing-remitting MS and major depressive disorder. INTERVENTIONS: Individual cognitive behavioral therapy, group psychotherapy, or sertraline therapy. MAIN OUTCOME MEASURES: Depression was assessed using the Beck Depression Inventory. Interferon gamma production by peripheral blood mononuclear cells was measured following stimulation with OKT3 or recombinant human myelin oligodendrocyte glycoprotein (MOG). Variability in immune assays was controlled using 8 nondepressed healthy subjects who were enrolled at times corresponding with the enrollment of MS patients. RESULTS: Results of the Beck Depression Inventory were significantly related to IFN-gamma production stimulated with OKT3 or MOG at baseline (P< or = .03 for all). Level of depression, OKT3-stimulated IFN-gamma production, and MOG-stimulated IFN-gamma production all declined significantly over the 16-week treatment period (P< or = .03 for all). Among controls, there were no significant changes over time in OKT3- or MOG-stimulated IFN-gamma, or in depression (P> or = .25 for all). CONCLUSIONS: These findings suggest that the production of the proinflammatory cytokine IFN-gamma by autoaggressive T cells in relapsing-remitting MS is related to depression and that treatment of depression may decrease IFN-gamma production. Thus, treatment of depression may provide a novel disease-modifying therapeutic strategy as well as a symptomatic treatment for patients with MS.

Induction of EAE in mice with recombinant human MOG, and treatment of EAE with a MOG peptide.

Myelin oligodendrocyte glycoprotein (MOG) is a transmembrane glycoprotein expressed on the surface of central nervous system (CNS) myelin membranes, which has been shown to induce experimental autoimmune encephalomyelitis (EAE) in rodents. Here we describe the induction of EAE in SJL and (PLJ X SJL)F1 mice with truncated human recombinant MOG (thr-MOG, amino acids 1-120) which has been expressed in insect cells in soluble form. We show that in SJL mice, immunization with thr-MOG produces an immune response to the 1-30 and the 81-110 regions of the MOG molecule. We also demonstrate effective treatment of thr-MOG-induced EAE in SJL mice with intravenous injections of a single peptide, MOG 91-110. These results support the possibility of treating MS using an antigen dependent approach.