Multiple Sclerosis Bulk Abstracts

Th1-polarized CD4⁺ T-Cells are considered central to the development of a number of target-directed AutoImmune disorders including Multiple Sclerosis.

The APC-derived Cytokine IL-12 is a potent inducer of Th1 polarization in T-Cells. Inhibition of IL-12 in vivo blocks the development of Experimental Allergic EncephaloMyelitis, the animal model for Multiple Sclerosis.

Based on previous work that suggests that the production of IL-12 by activated human Central Nervous System derived Microglia is regulated by autocrine TNF-.

We wanted to determine whether inhibition of TNF could induce a reduction of Th1 responses by its impact on systemic APCs.

We found that soluble TNFR p75-IgG fusion protein (TNFR:Fc) inhibited production of IFN- by allo-Ag-activated blood-derived human CD4 T-Cells.

We documented reduced IL-12 p70 production by APCs in the MLR. By adding back combinant IL-12, we could rescue IFN- production, indicating that TNFR:Fc acts on APC-derived IL-12.

Consistent with an inhibition of the Th1 polarization, we found a decreased expression of IL-12R-beta2 subunit on the T-Cells.

Furthermore, the capacity of T-Cells to secrete IFN- upon restimulation when previously treated with TNFR:Fc is impaired, whereas IL-2 secretion was not altered.

Our results define a TNF-dependent Cytokine network that favors development of Th1 Immune Responses.

The synthetic random Amino Acid Copolymer Copolymer 1 (Cop-1, Copaxone, Glatiramer Acetate) suppresses Experimental AutoImmune EncephaloMyelitis, slows the progression of disability, and reduces relapse rate in Multiple Sclerosis (MS).

Cop-1 binds to various Class II Major Histocompatibility Complex (MHC) molecules and inhibits the T-Cell responses to several Myelin Antigens.

In this study we attempted to find out whether, in addition to MHC blocking, Cop-1, which is Immunologically cross-reactive with Myelin Basic Protein (MBP), inhibits the response to this AutoAntigen by T-Cell Receptor (TCR) antagonism.

Two experimental systems, "prepulse assay" and "split APC assay," were used to discriminate between competition for MHC molecules and TCR antagonism.

The results in both systems using T-Cell lines/clones from mouse and human origin indicated that Cop-1 is a TCR antagonist of the 82-100 Epitope of MBP.

In contrast to the broad specificity of the MHC blocking induced by Cop-1, its TCR antagonistic activity was restricted to the 82-100 determinant of MBP and could not be demonstrated for Proteolipid Protein Peptide or even for other MBP Epitopes.

Yet, it was shown for all the MBP 82-100-specific T-Cell lines/clones tested that were derived from mice as well as from an MS patient.

The ability of Cop-1 to act as altered peptide and induce TCR antagonistic effect on the MBP p82-100 Immunodominant determinant response elucidates further the mechanism of Cop-1 therapeutic activity in Experimental AutoImmune EncephaloMyelitis and MS.

Experimental Allergic EncephaloMyelitis (EAE) and Theiler's Murine EncephaloMyelitis Virus (TMEV) disease are two DeMyelinating Diseases of the Central Nervous System (CNS) that serve as animal models for Multiple Sclerosis.

Th1 cells are thought to play a role in the PathoGenesis of CNS DeMyelination in both these diseases. We show here the differential influence of InterLeukin 12, a critical Cytokine for the development of Th1 cells in EAE and TMEV disease.

IL-12 is a Macrophage-derived heterodimeric Cytokine, capable of inducing proliferation, Cytokine production, and cytotoxic activity of NK Cells and T-Cells, and is critical for the development of Th1 responses.

TGF-ß is an ImmunoSuppressive Cytokine that inhibits IL-12-mediated responses in NK and T-Cells. To determine the mechanism of action of TGF-ß, we examined its inhibitory effect on IL-12 signal-transduction pathway in T-Cells.

Stimulation of activated T-Cells with IL-12 leads to Tyrosine Phosphorylation and activation of Jak-2 and Tyk-2 kinases and STAT3 and STAT4 transcription factors.

Treatment of activated T-Cells with TGF-ß blocked IL-12-induced Tyrosine Phosphorylation and activation of both Jak-2 and Tyk-2 kinases.

Furthermore, inhibition of Jak kinases by TGF-beta was associated with a decrease in Tyrosine Phosphorylation of STAT3 and STAT4 proteins.

Abrogation of IL-12-induced Jak-Stat pathway by TGF-ß resulted in decreased T-Cell proliferation and IFN- production, and increased Apoptotic Cell Death.

These findings highlight that TGF-ß inhibits IL-12-mediated responses by blocking IL-12 signal transduction in T-Cells.

The Multiple Sclerosis associated retroVirus (MSRV) isolated from Plasma of MS patients was found to be phylogenetically and experimentally related to Human Endogenous RetroViruses (HERVs).

To characterize the MSRV-related HERV family and to test the hypothesis of a replication-competent HERV, we have investigated the expression of MSRV-related sequences in healthy tissues.

The expression of MSRV-related transcripts restricted to the placenta led to the isolation of overlapping cDNA clones from a cDNA library. These cDNAs spanned a 7.6-kb region containing gag, pol, and env Genes; RU5 and U3R flanking sequences; a polypurine tract; and a primer binding site (PBS).

As this PBS showed similarity to avian retroVirus PBSs used by tRNATrp, this new HERV family was named HERV-W. Several genomic elements were identified, one of them containing a complete HERV-W unit, spanning all cDNA clones.

Elements of this multicopy family were not replication competent, as gag and pol open ading frames (ORFs) were interrupted by frameshifts and stop codons.

A complete ORF putatively coding for an envelope protein was found both on the HERV-W DNA prototype and within an RU5-env-U3R polyadenylated cDNA clone.

Placental expression of 8-, 3.1-, and 1.3-kb transcripts was observed, and a putative splicing strategy was described. The apparently tissue-restricted HERV-W long terminal repeat expression is discussed with respect to physiological and pathological contexts.

Although the etiology of Multiple Sclerosis (MS) is not known, several factors play a role in this disease: Genetic contributions, Immunologic elements, and environmental factors.

Viruses and Virus infections have been associated with the initiation and/or enhancement of exacerbations in MS.

Theiler's Murine EncephaloMyelitis Virus (TMEV) infection of mice is one of the animal models used to mimic MS. In other animal model systems, DNA vaccination has been used to protect animals against a variety of Virus infections.

To explore the utility of DNA vaccination, we have constructed Eukaryotic expression vectors encoding the TMEV capsid proteins VP1, VP2, and VP3. SJL/J mice were vaccinated intramuscularly once, twice, or three times with the different capsid protein cDNAs.

This was followed by IntraCerebral TMEV infection to determine the effects of DNA vaccination on the course of TMEV-induced Central Nervous System (CNS) DeMyelinating disease.

We found that vaccination of mice three times with cDNA encoding VP2 led to partial protection of mice from CNS DeMyelinating disease as determined by a decrease in clinical symptoms and HistoPathology.

Vaccination of mice with cDNA encoding VP3 also led to a decrease in clinical symptoms.

In contrast, mice vaccinated with cDNA encoding VP1 experienced a more severe disease with an earlier onset of clinical signs and enhanced HistoPathology compared with control mice. There was no correlation between anti-TMEV AntiBody titers and disease course.

These results indicate that DNA immunization can modify chronic Virus-induced DeMyelinating disease and may eventually lead to potential treatments for illnesses such as MS.

The role of various MHC Genes in determining the progression of Multiple Sclerosis (MS) remains controversial.

The HLA-DR3 Gene has been associated with Benign Relapsing MS in some Genetic epidemiologic studies, but with disease progression in others.

We induced DeMyelination in highly susceptible B10.M and B10.Q mice expressing the DR3 (HLA-DRB1*0301) transgene to determine directly the effects of a human transgene by infecting them with Theiler's Murine EncephaloMyelitis Virus (TMEV).

DR3+ mice experienced a dramatic reduction in the extent and severity of DeMyelination compared with DR3- littermate controls, whereas anti-TMEV AntiBody titers, delayed-type hypersensitivity responses, and levels of infectious Virus, Virus Antigen, and Virus RNA were similar in both groups.

To address a possible mechanism of how the human transgene is reducing Virus-induced DeMyelination, we analyzed Cytokine expression in the lesions and also determined whether B10.M mice can respond to peptides derived from the DR3 molecule.

Intense staining for IFN- and IL-4, T-Helper (TH) 1 and TH2 Cytokines, respectively, was found in the lesions of TMEV-infected DR3- mice but not in the DR3+ transgenic mice at day 21 after infection.

DR3 peptides elicited strong proliferative responses in B10.M mice but not in B10.M (DR3+) mice.

These experiments are the first to demonstrate that a human Class II DR Gene can alter the severity of DeMyelination in an animal model of MS without influencing Viral load.