Adhesion Molecule Profile and the Effect of Anti-VLA-4 mAb Treatment in Experimental Autoimmune Encephalomyelitis, a Mouse Model of Multiple Sclerosis

In the course of multiple sclerosis (MS) and its animal model, experimental autoimmune encephalomyelitis (EAE), the infiltration of lymphocytes and other inflammatory cells across the blood–brain barrier is associated with interactions between adhesion molecules expressed by infiltrating cells and vascular endothelium. Monoclonal antibodies (mAb) against the α4 subunit of α4-β1 integrin (VLA-4) show beneficial effects in both MS and EAE. (1) Background: The aim of this study was to examine the expression of selected adhesion molecules: VLA-4, VCAM-1, LFA-1, ICAM-1 and PECAM-1 in the successive phases of EAE and the effect of anti-VLA-4 mAb treatment on that expression. (2) Methods: EAE was induced in C57BL/6 mice by immunization with MOG_35–55 peptide. The animals were killed in three successive phases of the disease: onset (day 13), peak (day 18) and chronic (day 28). Frozen sections of the lumbar spinal cord were examined by quantitative immunofluorescence microscopy. The expression of the studied molecules was quantified as the percentage of the cross-sectioned spinal cord lesion area occupied by immunopositive structures. (3) Results: The expression of the studied molecules showed two temporal patterns: (1) an increase in the onset phase, a maximum in the peak phase and a decrease in the chronic phase, which corresponded to the temporal pattern of the clinical score, the number of lesions and the inflammation level (ICAM-1, LFA-1 and PECAM-1), and (2) an increase in the peak phase and no significant change or further increase in the chronic phase (VCAM-1, VLA-4). Among the molecules studied, ICAM-1 and LFA-1 exhibited the highest expression levels in the peak phase of EAE. Anti-VLA-4 mAb inhibited the expression of not only VLA-4 but also other adhesion molecules. (4) Conclusions: The interactions of adhesion molecules governing the migration of leukocytes across the blood–brain barrier change in the successive phases of EAE. The therapeutic mechanism of anti-VLA-4 mAb treatment seems to include a complex influence on a variety of adhesion molecules expressed by infiltrating cells and vascular endothelium.