Multiple Sclerosis Abstracts

A major question relevant to the initiation and progression of inflammation and AutoImmune processes within the Central Nervous System (CNS) is whether resident Microglia or only infiltrating Macrophage can productively interact with T-Cells that enter the CNS.

Either actively through extravasation or passively through defects in the Blood-Brain Barrier (BBB).

We isolated Microglia and Macrophage from the Brains of healthy adult mice and transgenic mice that displayed many features of Multiple Sclerosis and HIV LeukoEncephalopathy.

Due to the Astrocytic expression of InterLeukin-3 (IL-3) and compared their Antigen-Presenting Cell (APC) functions.

We found that unactivated Microglia isolated from healthy nontransgenic mice and activated Microglia isolated from transgenic siblings are relatively weak stimulators of naive T-Cell proliferation compared to Macrophage populations.

The APC function of activated, but not unactivated, Microglia could be increased by treatment acutely with LipoPolySaccharide (LPS)/Interferon gamma (IFN-).

However, this treatment also induced the apparent production of PostaGlandins, which reduced T-Cell proliferation when Indomethacin was absent from the assay cultures.

Strikingly, even in the absence of stimulated T-Cell proliferation, both unactivated and activated Microglia stimulated the differentiation of naive T-Cells into Th1 Effector Cells.

Although neither Microglial population was a more effective inducer than Macrophages or Splenic APCs. Thus, while Microglia are clearly capable of productively interacting with naive T-Cells, Macrophages have a more robust APC function.

Microglia, the resident Macrophages of the Central Nervous System, are the primary cells to respond to injury in the Brain, both in inflammation, e.g., in Multiple Sclerosis, and trauma.

Chemokines are potential mediators of Microglial cell recruitment to sites of injury; thus, the ability of Microglia to migrate in response to a number of Chemokines was assessed.

The Chemokines Monocyte ChemoAttractant protein 1, Macrophage Inflammatory Protein 1, Macrophage Inflammatory Protein 1beta, RANTES (regulated upon activation normal T-Cell expressed and secreted), InterLeukin 8, and IP-10 (Interferon inducible protein-10), induce migration and changes in the distribution of f-actin in adult rat Microglia and a human Microglial Cells line, CHME3, in vitro.

Both cell types show a significant migration response, above control levels, to all the chemokines tested in a typical dose-dependent manner. These Chemokines also induced a reorganization of the actin cytoskeleton of the cells.

This study indicates that Chemokines play an important role in the recruitment of Microglia to areas of Central Nervous System inflammation.

Objectives
To compare Action Tremor (AT) during manual tracking in normal subjects and patients with Multiple Sclerosis with Tremor (MS-Tremor group) and without Tremor (MS-no Tremor group).

And, to differentiate Tremor occurring predominantly around the distal joint from that involving the proximal joints of the arm.

Methods
Subjects performed both a visually guided ramp tracking task using wrist flexion/extension and a whole arm circle tracking task using shoulder movement.

Action Tremor at the wrist or shoulder was computed as the SD of the tracking velocity.

The ratio of wrist:arm Tremor was then calculated to differentiate distal from proximal Tremor in the tested arm. Frequency spectra of the records were also examined.

Results
During wrist tracking, AT in patients with Multiple Sclerosis contained a major frequency component at 4-5 Hz; the frequency was slightly lower during whole arm tracking.

The ratio of wrist:arm Tremor was significantly higher in the MS-Tremor group.

Of 12 tested arms, eight had Tremor significantly weighted towards the distal joint, only one towards the proximal joint, and three had a ratio inside the control range.

Conclusions
AT in the arms of patients with Multiple Sclerosis can be effectively differentiated into proximal or distal using these two different tracking tasks.

Despite the variability of the effects of Multiple Sclerosis, most of the AT was distal rather than proximal in this group of patients. Possibly Conduction Block along the CorticoCerebelloCortical pathways caused this distal Tremor.

The development of Multiple Sclerosis is most likely influenced by AutoImmune responses to Central Nervous System Myelin proteins as well as by infections with common Viruses such as EBV and Human HerpesVirus-6. However, much remains to be established on how these factors interact.

In this study, we show that upon EBV infection, human B-Cells start to express alphaB-Crystallin, a small stress protein that was identified previously as an Immunodominant Ag of CNS Myelin in Multiple Sclerosis patients.

EBV-induced expression of alphaB-Crystallin in B-Cells leads to HLA-DR-restricted presentation of the protein and to activation of proinflammatory alphaB-Crystallin-specific Th cells.

While alphaB-Crystallin is present in EBV-infected human B-Cells, the protein is absent from human Lymphoid tissues under normal conditions.

This is in sharp contrast to other stress proteins such as Heat-Shock Protein (hsp)27 and hsp60 that are ubiquitously expressed in these tissues.

In addition, the absence of alphaB-Crystallin from Lymphoid tissues in humans is unique as compared with other mammals.

All other species examined, including rodents, sheep, and primates, showed constitutive expression of alphaB-Crystallin in secondary Lymphoid tissues and sometimes even in the Thymus.

Since constitutive Lymphoid expression most likely results in Immunologic tolerance, such a state of tolerance to alphaB-Crystallin can be expected for all of these species, but not for humans.

When taken together, our data provide evidence for a novel mechanism by which common Viral infections can trigger Myelin-directed AutoImmunity in a way that is unique for humans.

In susceptible mouse strains, the wild-type Daniel's (wt-DA) strain of Theiler's Murine EncephaloMyelitis Virus induces a persistent Central Nervous System (CNS) infection with chronic DeMyelination.

The Virus is cleared from resistant mice with no resulting DeMyelination. We characterized the role of the DA L* protein in late DeMyelination and persistent infection. The DA genome has two alternative reading frames, encoding the virus polyprotein and L*, respectively.

The mutant virus DAL*-1 fails to synthesize L* and does not persist in the CNS of wt-DA-susceptible SJL/J or B10.S mice.

Since Class I-restricted CytoToxicity has been shown to determine resistance to virus persistence and DeMyelination in this model, virus-specific CytoToxicity in the CNS of DA-resistant (B6 or B10) and -susceptible (SJL/J and B10.S) mice during the acute stage of DA and DAL*-1 infection was characterized.

Following IntraCerebral inoculation with DAL*-1, virus-specific Db- and Kb-restricted CTLs were demonstrated in the CNS of resistant B10 mice, whereas only Db-restricted CTL were found in wt-DA-inoculated mice.

CTLs specific to wt-DA or DAL*-1 recognized Class I-presented peptides from either of the viruses.

Of particular interest, Ks-restricted virus-specific CytoToxicity-restricted CTLs were identified in the CNS of susceptible SJL/J (H-2s) and B10.S (H-2s) mice inoculated with DAL*-1.

In contrast, no virus-specific CTLs were identified in the CNS of SJL/J and B10.S mice inoculated with wt-DA.

We propose that L* inhibits the generation of H-2K-restricted Virus-specific CytoToxicity in the CNS, permitting a persistent infection in susceptible strains, with subsequent inflammatory DeMyelination in the CNS similar to that in human Multiple Sclerosis.

Myelin Oligodendrocyte Glycoprotein (MOG) is a quantitatively minor component of CNS Myelin whose function remains relatively unknown.

As MOG is an AutoAntigen capable of producing a DeMyelinating Multiple Sclerosis-like disease in mice and rats, much of the research directed toward MOG has been Immunological in nature.

Although the function of MOG is yet to be elucidated, there is now a relatively large amount of biochemical and molecular data relating to MOG.

Here we summarize this information and include our recent findings pertaining to the cloning of the marsupial MOG gene.

On the basis of this knowledge we suggest three possible functions for MOG:
1. Cellular Adhesive Molecule
2. Regulator of Oligodendrocyte MicroTubule stability
3. Mediator of interactions between Myelin and the Immune System, in particular, the Complement cascade

Given that AntiBodies to MOG and to the Myelin-specific Glycolipid GalactoCerebroside (Gal-C) both activate the same signaling pathway leading to MBP degradation, we propose that there is a direct interaction between the membrane-associated regions of MOG and Gal-C.

Such an interaction may have important consequences regarding the membrane topology and function of both molecules. Finally, we examine how polymorphisms and/or mutations to the MOG Gene could contribute to the PathoGenesis of Multiple Sclerosis.

Purpose
To determine how sensitive and specific the Magnetic Resonance (MR) Imaging finding of SubCallosal striations is for Multiple Sclerosis (MS).

Materials & Methods
In 18 patients with clinically suspected MS and 32 age-matched patients without MS, sagittal 2-mm fast Fluid-Attenuated Inversion-Recovery (FLAIR) imaging was added to the routine MR studies of the Brain.

The images were reviewed for the presence of SubCallosal striations, that is, linear, 1-mm-thick foci of HyperIntensity perpendicular to the Ependyma, like a stack of coins.

The images were masked to exclude the Hemispheric White Matter and were interpreted without knowledge of patient age or medical history.

Results
Seventeen patients with clinical MS had SubCallosal striations (beneath the Corpus Callosum); one did not. Of the 32 patients without MS, five had SubCallosal striations and 27 did not.

SubCallosal striations were highly associated (P < .001) with clinical MS.

Conclusion
SubCallosal striations are thought to represent PeriVenular DeMyelination, that is, the same process that later produces the "ovoid" lesions visible on routine MR images.

SubCallosal striations are not seen on routine axial MR images and can be seen only on 2-mm Sagittal FLAIR images.

It has been suggested that Nitric Oxide (NO) could be implicated in the PathoGenesis of Multiple Sclerosis (MS). Recently, two groups reported increased CerebroSpinal Fluid (CSF) Nitrate levels (Oxidation product that provides an indirect estimation of NO) in MS patients.

However, another group did not confirm these findings. We studied the CSF and Plasma levels of nitrate with a kinetic cadmium reduction method in 11 MS patients and 25 matched controls.

The CSF Nitrate levels and the CSF/plasma Nitrate ratio did not differ significantly between the two study groups. Plasma Nitrate levels were nearly significantly lower in MS patients.

CSF and Plasma Nitrate levels did not correlate with age at onset and duration of the disease in the patient group. These data suggest that measurement of CSF levels of Nitrate is not a marker of the activity of MS.

Experimental AutoImmune EncephaloMyelitis (EAE) is an Inflammatory AutoImmune Disease of the Central Nervous System that serves as a model for the human disease Multiple Sclerosis. Paralysis is "induced" by CD4⁺ T-Cells of the Th1 phenotype.

Tumor Necrosis Factor (TNF ), a Th1 type Cytokine, has been shown to be upregulated in the CNS during the onset of EAE, and systemic manipulations of TNF have had substantial effects on disease progression.

However, the precise role of TNF in EAE has been called into question by recent experiments utilizing TNF and LymphoToxin knockout mice.

We demonstrate here that the local delivery of TNF by Myelin Basic Protein (MBP)-specific T-Cells, RetroVirally transduced to express TNF , exacerbated MBP-induced disease following adoptive transfer into syngeneic mice.

Copyright 1999 Academic Press.

Elevations in temperature may produce conduction block in DeMyelinated Neurons. A well-described phenomenon in Multiple Sclerosis, it has also been reported in some patients with inflammatory DeMyelinating PolyNeuropathies.

We used Carpal Tunnel Syndrome (CTS) as a model to study the effect of heat on nerves with focal DeMyelination secondary to chronic compression.

Compound Motor and Sensory responses were measured in 12 CTS patients and 12 normal subjects at 32 degrees C and with heating to 42 degrees C. Changes in relative motor response amplitude and area were similar for both normal subjects and CTS patients.

In CTS patients, however, Sensory response amplitude and area decreased 34.3% and 48.9%, significantly more than the 25.2% and 39.1% reductions in normal subjects (P=0.021 and P=0.018 respectively).