The role od adhesion molecules in the pathogenesis of Graves ophthalmopathy

Graves' ophthalmopathy (GO) is an autoimmune condition characterized by mononuclear cell infiltration of the extraocular muscles and/or orbital connective tissue. Adhesion molecules play an important role in the initiation and maintenance of the inflammatory immune process. Cellular activation and local expression of adhesion molecules lead to leucocyte recruitment, migration to inflammatory sites and targeting in the extravascular space. Vascular endothelium in retroocular connective tissues of patients with GO is strongly positive for EMAL-1 and VCAM-1, whereas VCAM-1 immunoreactivity is minimal and ELAM-1 immunoreactivity is generally absent in normal retroocular tissue. Interactions between matched activated T lymphocytes and orbital endothelial cells are mediated by integrin dependent ICAM-1/LFA-1 and VCAM-1/VLA-4 pathways and reveal marked differences when comparing GO orbital endothelial cells to normal ones. Higher soluble ICAM-1 volumes in patients with Graves' disease with GO than those in patients with Graves' disease without ophthalmopathy can reflect the degree of inflammatory activity. Increased soluble ELAM-1 concentration only in patients with GO suggests that soluble ELAM-1 could be a specific marker of endothelium activation in GO.