MS Abstracts: 3c-2g

Chronic Relapsing Experimental Allergic EncephaloMyelitis (CREAE) is an AutoImmune model of Multiple Sclerosis.

Although both these diseases are typified by Relapsing/Remitting paralytic episodes, after CREAE induction by sensitization to Myelin Antigens Biozzi ABH mice also develop Spasticity and Tremor.

These symptoms also occur during Multiple Sclerosis and are difficult to control. This has prompted some patients to find alternative medicines, and to perceive benefit from Cannabis use.

Although this benefit has been backed up by small clinical studies, mainly with non-quantifiable outcomes, the value of Cannabis use in Multiple Sclerosis remains anecdotal.

Here we show that CannaBinoid (CB) receptor agonism using R(+)-WIN 55,212, delta9-TetrahydroCannaBinol, Methanandamide and JWH-133 (ref. 8) quantitatively ameliorated both Tremor and Spasticity in diseased mice.

The exacerbation of these signs after antagonism of the CB1 and CB2 receptors, notably the CB1 receptor, using SR141716A and SR144528 (ref. 8) indicate that the endogenous CannaBinoid system may be tonically active in the control of Tremor and Spasticity.

This provides a rationale for patients' indications of the therapeutic potential of Cannabis in the control of the symptoms of Multiple Sclerosis, and provides a means of evaluating more selective CannaBinoids in the future.

We assessed Axonal Loss in the Normal-Appearing White Matter of the Corpus Callosum in postmortem Brains of patients with Multiple Sclerosis, using quantitative measures of both Axonal Density and White Matter Atrophy.

The calculated total number of Axons was reduced significantly (mean +/- SD, 5.4 x 10(7) +/- 3.1 x 10(7)) compared with normal controls (11.6 x 10(7) +/- 2.2 x 10(7), p = 0.001) with a reduction both in Axonal density (median, 34%; range, 16-56%; p = 0.004) and area (mean +/- SD: Multiple Sclerosis, 584 +/- 170 mm2; controls, 871 +/- 163 mm2; p = 0.004).

These results confirm substantial Axonal loss in the Normal-Appearing White Matter and demonstrate that measures of both Axonal density and White Matter volume are necessary to appreciate the full extent of Axonal loss.

Several reports have suggested an association of Human HerpesVirus 6 (HHV-6) and Multiple Sclerosis (MS), based on ImmunoHistoChemical demonstration of HHV-6 Antigens in inflammatory lesions, detection of increased HHV-6 specific Serum AntiBody titers, and amplification of HHV-6 DNA from Sera and CerebroSpinal Fluid of MS patients but not in controls.

Characterization of the Cellular Immune Response of MS patients to HHV-6 may further clarify the role of HHV-6 in MS and provide insight into the PathoGenesis of this Immune-mediated Disease.

We have compared LymphoProliferative responses to HHV-6A (U1102)-, HHV-6B (Z29)-, and HHV-7 (H7SB)-infected Cell Lysates in healthy controls and patients with MS.

Most healthy controls (71%) proliferated to HHV-6B Lysate, and fewer (33%) responded to the HHV-6A lysate. In contrast, 67% of MS patients had a LymphoProliferative response to HHV-6A, which is a significant increase in comparison with healthy controls.

A similar frequency of LymphoProliferative response (78%) to HHV-6B was demonstrated in MS patients. LymphoProliferation to HHV-7 Lysate was demonstrated in 23% of healthy controls and 28% of MS patients.

These results indicate that the LymphoProliferative response to the HHV-6A variant, which was recently reported to have greater NeuroTropism, is increased in MS patients.

HLA-DM (DM) plays a critical role in Antigen presentation through Major Histocompatibility Complex (MHC) Class II molecules.

DM functions as a molecular chaperone by keeping Class II molecules competent for Antigenic Peptide loading and serves as an editor by favoring presentation of high-stability Peptides.

Until now, DM has been thought to exert these activities only in late Endosomal/ compartments of Antigen Presenting Cells. Here we show that a subset of DM resides at the cell surface of B-Cells and immature Dendritic Cells.

Surface DM engages in complexes with putatively empty Class II molecules and controls presentation of those Antigens that rely on loading on the cell surface or in early Endosomal recycling compartments.

For example, Epitopes derived from Myelin Basic Protein that are implicated in the AutoImmune Disease Multiple Sclerosis are down-modulated by DM, but are presented in the absence of DM.

Thus, this novel concept of functional DM on the surface may be relevant to both protective Immune Responses and AutoImmunity.

The environment in which the encounter of Antigen with the Immune System occurs determines whether Tolerance, infectious Immunity, or AutoImmunity results. Geographical areas with low supplies of Vitamin D (for example Scandinavia) correlate with regions with high incidences of Multiple Sclerosis, Arthritis, and Diabetes.

The active form of Vitamin D has been shown to suppress the development of AutoImmunity in experimental animal models. Furthermore, Vitamin D deficiency increases the severity of at least Experimental AutoImmune EncephaloMyelitis (mouse Multiple Sclerosis).

Targets for Vitamin D in the Immune System have been identified, and the mechanisms of Vitamin D-mediated ImmunoRegulation are beginning to be understood.

This review discusses the possibility that Vitamin D status is an environmental factor, which by shaping the Immune System affects the prevalence rate for AutoImmune Diseases such as Multiple Sclerosis, Arthritis, and Juvenile Diabetes.

It has been hypothesized that increased expression of ProInflammatory Cytokines mediate a variety of Central Nervous System Disorders such as Multiple Sclerosis, Alzheimer's Disease, Cerebral Ischemia, Spinal Cord Injury, HIV Encephalopathy and Chronic Pain.

In order to further examine the central role of Tumor Necrosis Factor (TNF) in NeuroPathic Pain, transgenic mice were used in which expression of murine TNF was targeted to Astrocytes using a Glial Fibrillary Acidic Protein (GFAP)-TNF fusion gene.

Spinal Nerve (L5) transection was performed in either the GFAP-TNF transgenic or wild type mice. Mechanical Allodynia was significantly enhanced in the GFAP-TNF transgenic mice compared with the wild type mice.

These data support a central role of Glial expression of TNF in the generation of NeuroPathic Pain.

The human population is exposed to both the UltraViolet A (UVA) and B (UVB) regions of the solar spectrum. UVB induces mainly Dipyrimidine photoproducts in DNA by a direct photochemical mechanism, whereas UVA is absorbed by other cellular constituents and induces mainly Oxidative damage indirectly.

The proportions of the different Dipyrimidine photoproducts, and the ratio of Dipyrimidine to Oxidative damage depend on the exact Spectral output of a UV source.

Irradiation of human epidermal Keratinocytes induces release of Cytokines, with CycloButane Pyrimidine dimers playing a significant role in the process. These Cytokines may then modulate the activity of cells of the Immune System.

Freshly isolated human Lymphocytes are exquisitely sensitive to UVB irradiation, because of their low DeoxyriboNucleotide pools. They also have a separate defect in removal of CycloButane Pyrimidine dimers from their DNA.

We have observed that frequencies of mutations at the hprt locus in human T-Lymphocytes and translocations involving the bcl2 locus in B-Lymphocytes appear to be associated with sunlight levels over the period before the blood sample was taken.

This may be an indirect Cytokine-mediated effect, and may be relevant to the possible link between Non-Hodgkin's Lymphoma and sunlight. On the other hand, sunlight can have beneficial effects, and may protect against AutoImmune Diseases including type I Diabetes and Multiple Sclerosis.

Serial MRI and clinical testing was performed on 45 well-defined untreated Multiple Sclerosis patients in different categories of Disease (Relapsing/Remitting, progressive, stable).

Up to 24 MRIs were scheduled over a 1-year period for each patient. Clinical evaluation was performed monthly and at times of attacks using the Expanded Disability Status Scale (EDSS) and the Ambulation Index (AI).

MRI scans were performed both with and without Gadolinium enhancement. MRI lesion volume was determined by computerized analysis and Gadolinium-enhancing lesions were counted by Radiologists.

We observed an increase in lesion volume over 1 year in all patient groups except those classified clinically as stable.

In Relapsing/Remitting patients there were correlations between increases in the number of Gadolinium enhancing lesions and increases in EDSS and the occurrence of attacks.

In Chronic/Progressive patients, increases in lesion volume were correlated with both increases in EDSS and AI.

These results demonstrate a linkage between MRI and clinical disease that depends both on the stage of MS and the MRI measures used and support the use of MRI as a surrogate marker of clinical disability in the study of Multiple Sclerosis.

To investigate the ImmunoGenicity and Encephalitogenicity of Oligodendrocyte-Specific Protein (OSP), recombinant soluble mouse OSP (smOSP) was produced from a synthetic Gene engineered to lack the sequences coding for the hydrophobic transmembrane domains of the native molecule.

SmOSP was ImmunoGenic and Encephalitogenic for SJL/J, C3H.SW and C57BL/6J mice, but not PL/J or BALB/c mice. SmOSP-specific T-Cells from SJL/J, C3H.SW and C57BL/6J mice induced severe chronic clinical Experimental AutoImmune EncephaloMyelitis upon transfer.

These findings indicate that AutoImmune T-Cell responses to OSP should be investigated in the context of Multiple Sclerosis.

Several findings indicate that infectious events play a role in the PathoGenesis of Multiple Sclerosis (MS). At the same time, T-Cell AutoImmunity to Myelin Antigens is widely believed to be crucial to the development of MS lesions.

Several mechanisms have been put forward to explain the presumed link between microbial infections and Myelin-directed AutoImmunity. These include Molecular Mimicry, bystander activation including Epitope spreading and superantigenic activation of T-Cells.

Evidence that either one of these mechanisms actually occurs in MS patients, however, is still weak. Also, none of the above mechanisms explain why MS is unique to humans.

We propose an alternative link between Microbial infection and Myelin AutoImmunity, which we refer to as *mistaken self*.

In this mechanism, peripheral Microbial infections of Lymphoid Cells prime the human T-Cell repertoire not only to Microbial Antigens but also to the Stress Protein alphaB-Crystallin that is expressed de novo in infected Lymphoid Cells.

Subsequently, stress-induced accumulation of this self Antigen in Oligodendocytes/Myelin can provoke pro-inflammatory responses as the recruited Memory T-Cell repertoire then mistakes the self protein for a Microbial Antigen.