MS Abstracts 12b-2g

Although classical NeuroPhysiological doctrine rested on the concept of the Sodium Channel, it is now clear that there are nearly a dozen Sodium Channel Genes, each encoding a molecularly distinct channel.

Different repertoires of channels endow different types of Neurons with distinct transduction and encoding properties.

Sodium Channel expression is highly dynamic, exhibiting plasticity at both the transcriptional and post-transcriptional levels.

In some types of Neurons within the normal Nervous System, e.g. HypoThalamic MagnoCellular NeuroSecretory Neurons, changes in Sodium Channel Gene expression occur in association with the transition from a quiescent to a bursting state.

These changes are accompanied by the insertion of a different set of Sodium Channel subtypes in the cell membrane, a form of molecular plasticity which results in altered ElectroGenic properties.

Dysregulation of Sodium Channel Genes has been observed in a number of disease states.

For example, transection of the Peripheral Axons of Spinal Sensory Neurons triggers down-regulation of some Sodium Channel Genes.

And up-regulation of other Sodium Channel Genes; the resultant changes in Sodium Channel expression contribute to HyperExcitability that can lead to Chronic Pain.

There is also evidence, in experimental models of DeMyelination and in post-mortem tissue from patients with Multiple Sclerosis, for dysregulation of Sodium Channel Gene expression in the cell bodies of some Neurons whose Axons have been DeMyelinated.

Suggesting that an acquired Channelopathy may contribute to the PathoPhysiology of DeMyelinating Diseases such as Multiple Sclerosis.

The dynamic nature of Sodium Channel Gene expression makes it a complex topic for investigation, but it also introduces therapeutic opportunities, since subtype-specific Sodium Channel modulating drugs may soon be available.

Multiple Sclerosis, an inflammatory, DeMyelinating Disease of the CNS currently lacks an effective therapy.

We show here that CNS inflammation and clinical disease in Experimental AutoImmune EncephaloMyelitis, an experimental model of Multiple Sclerosis, could be prevented completely by a replication-defective AdenoVirus Vector.

Expressing the anti-inflammatory Cytokine IL-10 (replication-deficient AdenoVirus expressing human IL-10), but only upon inoculation into the CNS where local infection and high IL-10 levels were achieved.

High circulating levels of IL-10 produced by i.v. infection with replication-deficient AdenoVirus expressing human IL-10 was ineffective, although the Immunological pathways for disease are initiated in the periphery in this disease model.

In addition to this protective activity, IntraCranial injection of replication-deficient AdenoVirus expressing human IL-10 to mice with active disease blocked progression and accelerated disease remission.

In a Relapsing/Remitting disease model, IL-10 Gene transfer during remission prevented subsequent relapses.

These data help explain the varying outcomes previously reported for systemic delivery of IL-10 in Experimental AutoImmune EncephaloMyelitis.

And show that, for optimum therapeutic activity, IL-10 must either access the CNS from the peripheral circulation or be delivered directly to it by strategies including the Gene transfer described here.

Certain cells within the CNS, Microglial Cells and PeriVascular Macrophages, develop from hemopoietic MyeloMonocytic lineage progenitors in the Bone Marrow (BM).

Such BM-derived cells function as CNS APCs during the development of T-Cell-mediated paralytic inflammation in diseases such as Experimental AutoImmune EncephaloMyelitis and Multiple Sclerosis.

We used a novel, interspecies, rat-into-mouse T-Cell and/or BM cell-transfer method to examine the development and function of BM-derived APC in the CNS.

Activated rat T-Cells, specific for either Myelin or NonMyelin Ag, entered the SCID mouse CNS within 3-5 days of cell transfer and caused an accelerated recruitment of BM-derived APC into the CNS.

Rat APC in the mouse CNS developed from transferred rat BM within an 8-day period and were entirely sufficient for induction of CNS inflammation and paralysis mediated by Myelin-specific rat T-Cells.

The results demonstrate that T-Cells modulate the development of BM-derived CNS APCs in an Ag-independent fashion.

This previously unrecognized regulatory pathway, governing the presence of functional APC in the CNS, may be relevant to PathoGenesis in Experimental AutoImmune EncephaloMyelitis, Multiple Sclerosis, and/or other CNS Diseases involving MyeloMonocytic lineage cells.

Oligodendrocytes are Myelin forming cells in Mammalian Central Nervous System. About 50% of Oligodendrocytes (OLGs) undergo cell death in normal development.

In addition, OLG cell deaths have been observed in DeMyelinating Diseases including Multiple Sclerosis (MS).

Clinical observations and in vitro cell culture studies have suggested that Cytokines mediate OLG cell damage in Multiple Sclerosis (MS).

Among the Cytokines, Tumor Necrosis Factor (TNF) is thought to be one of the mediators responsible for the damage of OLGs in MS.

The administration of TNF-alpha to primary cultures of OLGs induced DNA fragmentation, and significantly decreased the number of live OLGs.

Chemical inhibitors Ac-YVAD-CHO (a specific inhibitor of Caspase-1 (ICE)-like proteases) enhanced the survival of TNF-alpha treated OLGs better than Ac-DEVD-CHO (a specific inhibitor of Caspase-3 (CPP32)-like proteases).

These results indicate that caspase-1-mediated cell-death pathway are activated in TNF-induced OLG cell death. Caspase-11 is involved in activation of caspase-1.

Oligodendrocytes from Caspase-11-deficient mice are partially resistant to TNF-induced OLG cell death. Our results suggest that the inhibition of Caspase-1 sufamily may be a novel therapeutic approach to treat MS.

Development of NeuroProtective therapies for Multiple Sclerosis is dependent on defining the precise mechanisms.

Whereby Immune Effector Cells and molecules are able to induce relatively selective injury of Oligodendrocytes (OLs) and their Myelin membranes.

The selectivity of this injury could be conferred either by the properties of the Effectors or the targets.

The former would involve Antigen specific recognition by either AntiBody or T-Cell Receptor of the Adaptive Immune System.

OLs are also susceptible to non Antigen restricted injury mediated by components of the Innate Immune System including Macrophages/Microglia and NK T-Cells.

Target related selectivity could reflect the expression of death inducing Surface Receptors (such as Fas or TNFR-1) required for interaction with Effector mediators and subsequent IntraCellular signaling pathways, including the Caspase cascade.

Development of therapeutic delivery systems, which would reach the site of disease activity within the CNS, will permit the administration of inhibitors either of the cell death pathway or of Effector target interaction and opens new avenues to NeuroProtection approach.

The CNS has an inherent capacity to generate ReMyelinating Cells following episodes of Myelin loss. However, persistent DeMyelination is the major pathology of Multiple Sclerosis and the LeucoDystrophies, and is also a feature of Spinal Cord trauma.

There are potentially two approaches for achieving ReMyelination in situations where it fails; enhancement of the inherent ReMyelinating capacity of the CNS, or transplantation of an exogenous source of Myelin forming cells.

In experimental animals it is possible to ReMyelinate DeMyelinated CNS Axons by transplanting cultures containing Central or Peripheral Myelinogenic Cells.

Glial Cell transplantation may thus provide a therapeutic strategy for ReMyelinating areas of chronic DeMyelination as well as for stimulating Axon regeneration.

This presentation will review four issues that have to be addressed before Glial transplantation can be undertaken in humans: is the procedure safe, what cells would be used, where would the cells come from, and can we predict how much ReMyelination will be achieved?

It concludes that the most promising approach will be to use multipotent Neural Precursor Cells that have been committed to Oligodendrocyte lineage differentiation prior to implantation.

However, even with such preparations, which have considerable myelinating potential, the extent of remyelination that would be achieved can not yet be predicted with any degree of certainty.

Motor Neurons are among some of the most unusual cells in the body becaue of their immense size and their role as the critical link between the Motor Centers of the Brain and the muscles.

In addition to their intrinsic biological interest, it is vital that we gain a better understanding of these cells and their pathology, since Motor Neuron Degenerative Diseases are lethal disorders that affect young and old and are relatively common.

For example, one form of Spinal Muscular Atrophy (SMA) is the most common Genetic killer of children in the developed world.

Amyotrophic Lateral Sclerosis (ALS), another form of Motor Neuron degeneration, is the third most common NeuroDegenerative cause of adult death, after Alzheimer's Disease and Parkinson's Disease, and is significantly more common than Multiple Sclerosis (Motor Neuron Disease Association 1998).

Currently, approximately 1 in 500 people in England and Wales who die have a form of Motor Neuron Disease (Motor Neuron Disease Association 1998). Each year, 5000 Americans are diagnosed with ALS, and of these, 10% are under 40 years old.

Mouse models of Motor Neuron degeneration are essential for understanding the causes and mechanisms of Motor Neuron pathology. These mice are yielding important information that will ultimately lead to treatments and potentially cures for these diseases.

Optic-Spinal form of Multiple Sclerosis (OS-MS) and HTLV-1 Associated Myelopathy/Tropical Spastic Paraparesis (HAM/TSP) are two Immune-mediated Myelopathy relatively common in Japan.

Transverse Myelitis, once seen in 60% of MS, mostly OS-MS, 30 years ago, drastically decreased (5%) recently in Japan.

In contrast, frequency of conventional form of MS (C-MS) increased during this period of time. But unlike C-MS in white patients, Cerebellar Hemispheric lesions are uncommon in Japanese C-MS.

These findings emphasize influence of changes in exogenous factors on manifestations of MS and distinct Genetic factors related to MS in Japanese and white patients.

To clarify the reason of high HTLV-I proviral load in HAM/TSP, we studied Cellular Immune surveillance against HTLV-I.

And found that significant CytoToxic T-Lymphocyte activity, suppressed Natural Killer activity, and AntiBody-dependent Cell-mediated CytoToxicity in the patients.

These altered Immune surveillance may be associated with the spread of HTLV-1 infection and the PathoGenesis of HAM/TSP.

The CC Chemokine Receptor-1 (CCR1) is a prime therapeutic target for treating AutoImmune Diseases.

Through high capacity screening followed by chemical optimization, we identified a novel non-Peptide CCR1 antagonist, R-N-[5-Chloro-2-[2-[4-[(4-fluorophenyl)methyl] -2-methyl-1-piperazinyl]-2-oxoethoxy]phenyl] Urea Hydrochloric Acid Salt (BX 471).

Competition binding studies revealed that BX 471 was able to displace the CCR1 Ligands, MIP-1, RANTES and MCP-3, with high affinity (Ki ranged from 1 nM to 5.5 nM).

BX 471 was a potent functional antagonist based on its ability to inhibit a number of CCR1-mediated effects including Ca²⁺ mobilization, increase in ExtraCellular acidification rate, CD11b expression and Leukocyte migration.

BX 471 demonstrated a greater than 10,000 fold selectivity for CCR1 compared with 28 G-protein coupled Receptors. Pharmacokinetic studies demonstrated that BX 471 was orally active with a bioavailability of 60% in dogs.

Furthermore, BX 471 effectively reduces disease in a rat Experimental Allergic EncephaloMyelitis model of Multiple Sclerosis.

This study is the first to demonstrate that a non-Peptide Chemokine Receptor antagonist is efficacious in an animal model of an AutoImmune Disease.

In summary, we have identified a potent, selective and orally available CCR1 antagonist which may be useful in the treatment of Chronic Inflammatory Diseases.

NeuroPsychological deficits and the relationship to Brain Pathology were examined in 13 Primary/Progressive (PP) and 12 Secondary/Progressive (SP) Multiple Sclerosis patients with a similar duration of the Progressive phase and comparable physical Disability.

A battery of NeuroPsychological tests to assess Attention, Short-Term and Working Memory was administered to the patients, and their performance was compared to that of 20 healthy controls matched for age and premorbid IQ.

Total Cerebral lesion load on T₂-weighted Magnetic Resonance Imaging was measured in the patients. Both PP and SP patients performed significantly worse than controls in most of the NeuroPsychological tests.

There were only subtle differences between SP and PP on the Working Memory task although Magnetic Resonance Imaging Lesion Load was significantly higher in SP than in PP patients.

In this exploratory study only subtle differences in Cognitive Impairment were detected between SP and PP patients matched for physical Disability and relevant illness features.

The results also suggest that the severity of Cognitive Impairment cannot be fully explained by the extent of abnormalities detected on conventional T₂-weighted Magnetic Resonance Images.

And that other Pathological abnormalities such as in Normal-Appearing White Matter are likely to be involved.