Adhesion Molecules In Multiple Sclerosis

Adhesion Molecules are likely to play a critical role in the ImmunoPathoGenesis of Multiple Sclerosis (MS).

"The interaction of the Vascular Cell Adhesion Molecule-1 (VCAM-1) with its Lymphocyte Ligand Very Late Antigen-4 (VLA-4) may mediate migration of Lymphocytes into the CNS.

We have previously demonstrated that soon after initiation of treatment with Interferon-ß, MS patients have a significant increase in soluble VCAM-1 (sVCAM-1), and this effect correlated with the resolution of contrast-enhancing MRI Lesions.

We studied the cell surface expression of VLA-4 by flow cytometry in 10 MS patients before and during IFN-ß treatment. We found a significant decrease in mean VLA-4 fluorescence of MS patients' Lymphocytes on treatment and no change in untreated controls.

In vitro treatment of Lymphocytes with IFN-ß did not reproduce this effect, but the addition of sVCAM-1 did result in a decrease in VLA-4 expression.

These data indicate that the previously identified increase in sVCAM-1 may lead to a decrease in VLA-4 expression and that this effect may partially explain the mechanism of action of IFN-ß.

Interferon-beta-1b (IFN-ß-1b) (Betaseron) has been recently shown to alter the course of Multiple Sclerosis (MS), an inflammatory DeMyelinating disease of the Central Nervous System (CNS).

Where migration of activated Lymphocytes across the Blood-Brain Barrier (BBB) is a critical step in the PathoGenesis of this disease.

Magnetic Resonance Imaging (MRI) studies performed on patients treated with IFN-ß-1b showed a remarkable effect on the BBB.

As determined by a reduction in the number of Gadolinium enhancing lesions, a measure of BBB leakiness.

Since Adhesion Molecules (AM) induced on Endothelial Cells (EC) play an important role in T-Cell migration into the CNS.

The objective of this study was to examine the effect of IFN-ß-1b on the expression of the AM, ICAM-1, V-CAM and E-Selection induced on EC by IFN-, TNF-, or IL-1 ß.

Primary cultures of Human Umbilical Vein EC (HUVEC) were used, which under basal conditions expressed low levels of AM.

IFN-ß-1b (1-1000IU/ml) had minimal effect on basal expression of AM on HUVEC, but AM could be substantially upregulated by IFN-, IL-1 ß or TNF-.

The effect of IFN-ß-1b on AM expression induced by IFN-, IL-1 ß or TNF- was slightly additive.

It is concluded that IFN-ß-1b does not downregulate the inducible expression of ICAM-1, V-CAM or E-Selectin on HUVEC.

These findings suggest alternate mechanisms for the effect of IFN-ß-1b on the BBB in MS.

The levels of Serum-Soluble IntraCellular Adhesion Molecule-1 and soluble Endothelial-Leukocyte Adhesion Molecule-1, and the Gadolinium-enhanced T₁-weighted MRI were studied.

In a group of patients with Relapsing/Remitting Multiple Sclerosis treated with Interferon-beta-1b (IFN-ß-1b) and compared to a non-treated control group.

The levels of Serum-Soluble IntraCellular Adhesion Molecule-1 and soluble Endothelial-Leukocyte Adhesion Molecule-1 increased, after three months treatment, as compared to baseline and the non-treated MS patients.

A significant correlation was found in the treated group between Serum-Soluble Endothelial-Leukocyte Adhesion Molecule-1 and the lesion area in the Gadolinium-enhancing (T₂ weighted scan) MRI.

Objectives
To determine levels of Adhesion Molecules in blood and CerebroSpinal Fluid (CSF) samples from patients with different subtypes and activities of Multiple Sclerosis (MS).

And, to assess the effect of intravenous MethylPrednisolone sodium succinate treatment on the levels of soluble Adhesion Molecules.

Design
The expressions of Very Late Activation Antigen 4 (VLA-4), Lymphocyte function associated Antigen 1 (LFA-1), Vascular Cell Adhesion Molecule 1 (VCAM-1), and InterCellular Adhesion Molecule 1 (ICAM-1) were determined ImmunoCytoChemically.

And, levels of soluble VCAM-1, ICAM-1, and E-Selectin, by means of Enzyme Immunoassay technique.

The volumes of T₂- and T₁-weighted MS plaques and Brain Atrophy were determined by means of the semiautomatic Magnetic Resonance Imaging (MRI) segmentation technique.

Setting & Patients
A university hospital in Finland. One hundred subjects (71 patients with MS and 29 healthy control subjects).

The subtypes of MS were Relapsing/Remitting (RRMS [n=26]), Secondary/Progressive (SPMS [n=20]), and Primary/Progressive (PPMS [n=25]).

Results
In patients with RRMS and SPMS, the expressions of VLA-4 and LFA-1 on Immune Cells from blood were at least 1.5- to 3-fold higher.

Than in controls (RRMS, P=.002 and P<.001, respectively; SPMS, P=.03 and P=.001, respectively).

In RRMS, LFA-1 and ICAM-1 expression in blood was more up-regulated than in SPMS (P=.03 and P=.01, respectively).

The expressions of Adhesion Molecules on CSF Lymphocytes in RRMS and SPMS were of similar magnitude.

But, the proportions of CSF VLA-4 and LFA-1 expressing Lymphocytes were 3- to 4-fold higher than in controls (P=.04 and P=.008, respectively).

The levels of Serum soluble VCAM-1 were higher in SPMS than in RRMS (P=.005) or PPMS (P=.04).

Intravenous MethylPrednisolone treatment of patients with RRMS in exacerbation caused a significant reduction in the Serum levels of soluble VCAM-1 and E-Selectin (P<.001).

In SPMS, the volumes of T₂-weighted plaques correlated with the Serum level of soluble ICAM-1 (r = 0.64; P = .03).

Conclusions
Up-regulated Adhesion Molecules in blood and CSF indicate sustained potential for inflammation in the CNS throughout the clinical spectrum of MS.

Therapies interfering with Cell Adhesion may be of key importance in suppressing MS.

Cellular Adhesion Molecules were initially defined as cell surface structures mediating cell-cell and cell-ExtraCellular Matrix (ExtraCellular Matrix) interactions.

1. Selectins
2. ImmunoGlobulin (Ig) Superfamily
3. Integrins

It has been well documented that Adhesion Molecules of these family members (E-Selectin, ICAM-1, and VCAM-1) are expressed on Brain MicroVessel Endothelial Cells in active lesions of Multiple Sclerosis (MS) Brain.

In addition, accumulating data show that Glial Cells can express some of these Adhesion Molecules upon activation: Astrocytes can express ICAM-1, VCAM-1, and E-Selectin, and Microglia express ICAM-1 and VCAM-1.

In vitro studies show that these Adhesion Molecules are actively regulated by several Cytokines which have relevance to MS or Experimental AutoImmune EncephaloMyelitis (EAE).

In addition, soluble forms of Adhesion Molecules have been found in the Serum and CerebroSpinal Fluid (CSF) of MS patients, and may be useful diagnostically.

Experimental therapy of EAE using AntiBodies against several Adhesion Molecules clearly shows that Adhesion Molecules are critical for the PathoGenesis of EAE.

Thus far, the function of Adhesion Molecule expression on Brain Endothelial and Glial Cells has not been clearly elucidated.

Studies on the possible role of Adhesion Molecules on Brain Endothelial and Glial Cells will be helpful in understanding their involvement in Immune Responses in the Central Nervous System (CNS).

The distribution and lineage of Vascular Cell Adhesion Molecule-1 (VCAM-1)-positive cells was investigated in 43 lesions from the Brain tissue of patients with Multiple Sclerosis (MS).

Numerous VCAM-1-positive Macrophages/Microglia were detected at the edges of MS lesions.

Quantitative analysis of 6 active, 7 chronic active, and 4 chronic inactive MS lesions identified most VCAM-1-positive cells at the actively DeMyelinating borders of active (102/mm3) and chronic active (29/mm3) lesions, but rarely in chronic inactive lesions (4/mm3).

Further, approximately 17% of the VCAM-1-positive cells closely apposed or surrounded Oligodendrocyte Perikarya at the edges of active and chronic active lesions that were sites of ongoing DeMyelination.

Endothelial Cells were VCAM-1-negative in both lesion and non-lesion MS Brain tissue.

This report is the first to document direct Microglial interaction with Oligodendrocytes in MS.

Background
The expression of soluble cell Adhesion Molecules (AM) in CerebroSpinal Fluid (CSF) and blood and their significance as measures of disease activity has been extensively studied in patients with Multiple Sclerosis (MS).

In previous studies, we found that cell surface bound AM on MonoNuclear Cells (MNCs) in CSF and blood might be useful markers of clinical disease activity in MS patients.

Objective
To analyze the correlation of cell surface bound and soluble AM in CSF and blood with Magnetic Resonance Imaging (MRI) markers of subclinical disease severity and activity in patients with MS.

Methods
Expression levels of cell surface bound AM on peripheral blood and CSF MNCs were determined by flow cytometry analysis in 77 (CSF: 33) MS patients.

Concentration levels of the soluble forms of AM were measured by Enzyme-Linked ImmunoSorbent Assay (ELISA).

In corresponding Cerebral Gadolinium (Gd)-enhanced MRI scans, we determined both measures of subclinical disease severity and subclinical disease activity.

Results
The expression levels of cell surface bound AM in peripheral blood correlated inversely with parameters for subclinical disease severity and activity on Cerebral MRI scans as well as with the disease duration.

Furthermore, we found significant correlations between Serum levels of soluble AM and patient age but not with disease duration.

Conclusions
Our results suggest that subclinical disease progression may be associated with a decrease of the expression of cell surface bound AM on peripheral blood MNCs. This might be a result of activated MNC migration into the CNS.

Multiple Sclerosis is affecting approximately 1 out of every 1000 individuals in the western world. After Axons are denuded of Myelin in the early stages of the disease.

ReMyelination occurs, but eventually this process fails, and permanent disability is the result.

During development, the PolySialylated form of the Neural Cell Adhesion Molecule NCAM, PSA-NCAM, is expressed at the Axonal surface.

And, acts as a negative regulator of Myelination, presumably by preventing Myelin-forming cells from attaching to the Axon.

Removal of PSA-NCAM from the Axonal surface is a prerequisite for the initiation of Myelination.

We questioned whether, in Multiple Sclerosis, re-expression of PSA-NCAM by Axons could occur, and therefore account for the failure of ReMyelination.

Forty Multiple Sclerosis lesions from 24 different post-mortem Multiple Sclerosis cases were selected by Histological methods and analyzed by ImmunoHistoChemistry.

DeMyelinated lesions and partially ReMyelinated lesions (shadow plaques) were studied.

Controls consisted of post-mortem Brain tissue from patients with Amyotrophic Lateral Sclerosis and without Neurological Disease.

We showed that PSA-NCAM, normally absent from adult Brain, is re-expressed on DeMyelinated Axons in the plaques. Within shadow plaques, ReMyelinated Axons do not express PSA-NCAM.

Re-expression of PSA-NCAM could act as an inhibitor of ReMyelination and participate in disease progression in Multiple Sclerosis.

Close relationship between Neurons and Oligodendrocytes seems to be of the greatest importance during Oligodendrocyte maturation and Myelin formation within Central Nervous System.

Two major factors are likely to play the decisive role in CNS Myelination - Adhesion Molecules and Electrical Activity.

It has been shown, both in vitro and in vivo, that blocking or stimulating Electrical Activity may inhibit or induce Myelination respectively.

The fact that even in culture Oligodendrocytes Myelinate solely Axons and not other cellular processes present within CNS, as well as the finding that normal Myelin sheath compaction is encountered only around Axons.

Suggest that close interaction between Oligodendrocytes and Neurons is required for normal Myelin formation.

Adhesion Molecules are most likely involved in this interaction by not only bringing the Axon and the Glial Cell close to each other but also by transducing signals to initiate Myelination.

The Neural Cell Adhesion Molecule (NCAM) is a candidate molecule that could regulate Axon/Glial Cell interaction. It is abundantly present in all growing Fiber Tracts of the developing CNS.

Since its PolySialylated from (PSA-NCAM) has been shown to disappear from Axonal surface as Myelination progresses.

And, that its removal increases 4 to 5 fold Myelination, it is thought to be a negative factor for Myelin formation.

These observations may have important implications in therapeutic strategies in DeMyelinating Disorders like Multiple Sclerosis.