myelin-oligodendrocyte-glycoprotein-(35-55) and Nerve-Degeneration

Semaphorin 7A (sema7A) is classified as an immune semaphorin with dual functions in the immune system and in the central nervous system (CNS). These molecules are of interest due to their potential role in multiple sclerosis (MS), which is a chronic demyelinating and neurodegenerative disease of autoimmune origin. In this study, we elucidated the role of sema7A in neuroinflammation using both in vitro and in vivo experimental models. In an in vitro model of neuroinflammation, using cerebellar organotypic slice cultures, we observed that challenge with lipopolysaccharide (LPS) endotoxin did not affect demyelination or cell death in sema7A-deficient cultures compared to wild-type cultures. Moreover, the in vivo outcome of experimental autoimmune encephalomyelitis (EAE) in sema7A-deficient mice was altered in an antigen- and adjuvant-dose-dependent manner, while no differences were observed in the wild-type counterparts. Altogether, these results indicate that sema7A is involved in peripheral immunity and CNS inflammation in MS pathogenesis. Indeed, these data suggest that sema7A might be a potential therapeutic target to treat MS and autoimmune conditions.

Topics: Adjuvants, Immunologic; Animals; Antigens, CD; Cell Proliferation; Cerebellum; Disease Susceptibility; Encephalomyelitis, Autoimmune, Experimental; Immunization; Inflammation; Mice, Inbred C57BL; Mice, Knockout; Models, Biological; Molecular Targeted Therapy; Multiple Sclerosis; Myelin Sheath; Myelin-Oligodendrocyte Glycoprotein; Nerve Degeneration; Peptide Fragments; Semaphorins

Data from multiple sclerosis (MS) and the MS rodent model, experimental autoimmune encephalomyelitis (EAE), highlighted an inflammation-dependent synaptopathy at the basis of the neurodegenerative damage causing irreversible disability in these disorders. This synaptopathy is characterized by an imbalance between glutamatergic and GABAergic transmission and has been proposed to be a potential therapeutic target. Siponimod (BAF312), a selective sphingosine 1-phosphate1,5 receptor modulator, is currently under investigation in a clinical trial in secondary progressive MS patients. We investigated whether siponimod, in addition to its peripheral immune modulation, may exert direct neuroprotective effects in the central nervous system (CNS) of mice with chronic progressive EAE.. Minipumps allowing continuous intracerebroventricular (icv) infusion of siponimod for 4 weeks were implanted into C57BL/6 mice subjected to MOG35-55-induced EAE. Electrophysiology, immunohistochemistry, western blot, qPCR experiments, and peripheral lymphocyte counts were performed. In addition, the effect of siponimod on activated microglia was assessed in vitro to confirm the direct effect of the drug on CNS-resident immune cells.. Siponimod administration (0.45 μg/day) induced a significant beneficial effect on EAE clinical scores with minimal effect on peripheral lymphocyte counts. Siponimod rescued defective GABAergic transmission in the striatum of EAE, without correcting the EAE-induced alterations of glutamatergic transmission. We observed a significant attenuation of astrogliosis and microgliosis together with reduced lymphocyte infiltration in the striatum of EAE mice treated with siponimod. Interestingly, siponimod reduced the release of IL-6 and RANTES from activated microglial cells in vitro, which might explain the reduced lymphocyte infiltration. Furthermore, the loss of parvalbumin-positive (PV+) GABAergic interneurons typical of EAE brains was rescued by siponimod treatment, providing a plausible explanation of the selective effects of this drug on inhibitory synaptic transmission.. Altogether, our results show that siponimod has neuroprotective effects in the CNS of EAE mice, which are likely independent of its peripheral immune effect, suggesting that this drug could be effective in limiting neurodegenerative pathological processes in MS.

Topics: Animals; Antigens, CD; Azetidines; Benzyl Compounds; Calcium-Binding Proteins; Cell Line, Transformed; Cerebral Cortex; Cytokines; Disease Models, Animal; Encephalomyelitis, Autoimmune, Experimental; Freund's Adjuvant; Mice; Microfilament Proteins; Myelin-Oligodendrocyte Glycoprotein; Nerve Degeneration; Neural Conduction; Neuroglia; Neurons; Neuroprotective Agents; Peptide Fragments; Synapses; Synaptic Potentials; T-Lymphocytes; White Matter

Nicotine has been shown to attenuate experimental autoimmune encephalomyelitis (EAE) through inhibiting inflammation in microglial populations during the disease course. In this study, we investigated whether nicotine modified the regenerative process in EAE by examining nestin-expressing neural stem cells (NSCs) in the spinal cord, which is the primary area of demyelination and inflammation in EAE. Our results show that the endogenous neurogenic responses in the spinal cord after EAE are limited and delayed: while nestin expression is increased, the proliferation of ependymal cells is inhibited compared to healthy animals. Nicotine application significantly reduced nestin expression and partially allowed for the proliferation of ependymal cells. We found that reduction of ependymal cell proliferation correlated with inflammation in the same area, which was relieved by the administration of nicotine. Further, increased numbers of oligodendrocytes (OLs) were observed after nicotine treatment. These findings give a new insight into the mechanism of how nicotine functions to attenuate EAE.

Topics: Animals; Antigens; Autophagy-Related Proteins; Doublecortin Domain Proteins; Encephalomyelitis, Autoimmune, Experimental; Glial Fibrillary Acidic Protein; Inflammation; Intracellular Signaling Peptides and Proteins; Ki-67 Antigen; Leukocyte Common Antigens; Mice; Mice, Inbred C57BL; Microtubule-Associated Proteins; Myelin-Oligodendrocyte Glycoprotein; Nerve Degeneration; Nestin; Neural Stem Cells; Neurogenesis; Neuropeptides; Nicotine; Nicotinic Agonists; Peptide Fragments; Proteoglycans; Spinal Cord; Time Factors

Multiple sclerosis involves demyelination and axonal degeneration of the central nervous system. The molecular mechanisms of axonal degeneration are relatively unexplored in both multiple sclerosis and its mouse model, experimental autoimmune encephalomyelitis. We previously reported that targeting the axonal growth inhibitor, Nogo-A, may protect against neurodegeneration in experimental autoimmune encephalomyelitis; however, the mechanism by which this occurs is unclear. We now show that the collapsin response mediator protein 2 (CRMP-2), an important tubulin-associated protein that regulates axonal growth, is phosphorylated and hence inhibited during the progression of experimental autoimmune encephalomyelitis in degenerating axons. The phosphorylated form of CRMP-2 (pThr555CRMP-2) is localized to spinal cord neurons and axons in chronic-active multiple sclerosis lesions. Specifically, pThr555CRMP-2 is implicated to be Nogo-66 receptor 1 (NgR1)-dependent, since myelin oligodendrocyte glycoprotein (MOG)(35-55)-induced NgR1 knock-out (ngr1(-)(/)(-)) mice display a reduced experimental autoimmune encephalomyelitis disease progression, without a deregulation of ngr1(-)(/)(-) MOG(35-55)-reactive lymphocytes and monocytes. The limitation of axonal degeneration/loss in experimental autoimmune encephalomyelitis-induced ngr1(-)(/)(-) mice is associated with lower levels of pThr555CRMP-2 in the spinal cord and optic nerve during experimental autoimmune encephalomyelitis. Furthermore, transduction of retinal ganglion cells with an adeno-associated viral vector encoding a site-specific mutant T555ACRMP-2 construct, limits optic nerve axonal degeneration occurring at peak stage of experimental autoimmune encephalomyelitis. Therapeutic administration of the anti-Nogo(623-640) antibody during the course of experimental autoimmune encephalomyelitis, associated with an improved clinical outcome, is demonstrated to abrogate the protein levels of pThr555CRMP-2 in the spinal cord and improve pathological outcome. We conclude that phosphorylation of CRMP-2 may be downstream of NgR1 activation and play a role in axonal degeneration in experimental autoimmune encephalomyelitis and multiple sclerosis. Blockade of Nogo-A/NgR1 interaction may serve as a viable therapeutic target in multiple sclerosis.

Topics: Adult; Analysis of Variance; Animals; Antibodies; Axons; CD3 Complex; Cell Line, Tumor; Demyelinating Diseases; Disease Models, Animal; Encephalomyelitis, Autoimmune, Experimental; Female; Gene Expression Regulation; Glycoproteins; GPI-Linked Proteins; Green Fluorescent Proteins; Humans; Immunoprecipitation; Intercellular Signaling Peptides and Proteins; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Middle Aged; Multiple Sclerosis; Mutation; Myelin Proteins; Myelin-Oligodendrocyte Glycoprotein; Nerve Degeneration; Nerve Tissue Proteins; Neuroblastoma; Neurofilament Proteins; Nogo Receptor 1; Optic Nerve; Peptide Fragments; Phosphorylation; Receptors, Cell Surface; Retinal Ganglion Cells; Severity of Illness Index; Silver Staining; Spinal Cord; tau Proteins; Time Factors; Transduction, Genetic; Tubulin

In the present study, we demonstrate that the histopathologic features of myelin oligodendrocyte glycoprotein (MOG) peptide 35-55-induced experimental autoimmune encephalomyelitis (EAE) in C57BL/6 mice closely mirror the hallmarks of MS pathology. On the one hand, we depict a time-dependent transition from acute inflammation to chronic neurodegeneration in spinal cord histopathology and provide distinct criteria (i.e. parenchymal edema, cellular infiltration and perivascular inflammatory infiltrates) by which acute and chronic stages of the disease can be distinguished. On the other hand, we assessed the extent of spinal cord plaque formation in relation to the total white matter area and we demonstrate a strong correlation with the clinical disease severity. Additionally, we report on the involvement of different spinal cord regions, focusing on the anterolateral, posterior and pyramidal tract. Our results help to further characterize histopathology of MOG peptide 35-55-induced EAE and reinforce the importance of this model for structural and functional studies of MS features.

Topics: Animals; Disease Models, Animal; Encephalomyelitis, Autoimmune, Experimental; Female; Glycoproteins; Mice; Mice, Inbred C57BL; Multiple Sclerosis; Myelin-Oligodendrocyte Glycoprotein; Nerve Degeneration; Peptide Fragments; Spinal Cord

Although demyelination is a cardinal feature in multiple sclerosis, axonal injury also occurs. We tested whether a delay in axonal degeneration could affect the disease severity in two models for multiple sclerosis: experimental autoimmune encephalomyelitis (EAE) and Theiler's murine encephalomyelitis virus (TMEV) infection. We compared wild-type C57BL/6 (B6) mice with C57BL/Wld(s) (Wld) mice, which carry a mutation that delays axonal degeneration. In EAE, both mouse strains were sensitized with myelin oligodendrocyte glycoprotein (MOG)(35-55) peptide and showed a similar disease onset, MOG-specific lymphoproliferative responses, and inflammation during the acute stage of EAE. However, during the chronic stage, B6 mice continued to show paralysis with a greater extent of axonal damage, demyelination, and MOG-specific lymphoproliferative responses compared with Wld mice, which showed complete recovery. In TMEV infection, only Wld mice were paralyzed and had increased inflammation, virus antigen-positive cells, and TMEV-specific lymphoproliferative responses versus infected B6 mice. Because TMEV can use axons to disseminate in the brain, axonal degeneration in B6 mice might be a beneficial mechanism that limits the virus spread, whereas slow axonal degeneration in Wld mice could favor virus spread. Therefore, axonal degeneration plays contrasting roles (beneficial versus detrimental) depending on the initiator driving the disease.

Topics: Animals; Antigens, Viral; Cardiovirus Infections; Demyelinating Diseases; Disease Models, Animal; Disease Progression; Encephalomyelitis, Autoimmune, Experimental; Female; Glycoproteins; Mice; Mice, Inbred C57BL; Multiple Sclerosis; Mutation; Myelin-Oligodendrocyte Glycoprotein; Nerve Degeneration; Peptide Fragments; Species Specificity; Theilovirus; Time Factors