Plasma thrombomodulin as a marker of vascular injuries in collagen vascular diseases

Thrombomodulin, a thrombin receptor on the vascular endothelial cell surface, is released into circulating blood. The plasma concentrations in patients with collagen vascular diseases, including systemic lupus erythematosus (SLE), rheumatoid arthritis, juvenile rheumatoid arthritis, Sjögren's syndrome, systemic sclerosis, polymyositis and/or dermatomyositis (PM/DM), Behçet's disease, and Wegener's granulomatosis, were measured and compared with those of healthy persons. The mean plasma thrombomodulin concentrations in patients with juvenile rheumatoid arthritis, systemic sclerosis, PM/DM, Wegener's granulomatosis, and active states of SLE, rheumatoid arthritis, and Beçhet's disease were significantly higher than those in the control group. Patients with Wegener's granulomatosis showed the highest mean value. The mean values in patients with inactive states of the diseases and Sjögren's syndrome were not significantly different from the values in the control group. In cases of juvenile rheumatoid arthritis, systemic sclerosis, PM/DM, and Wegener's granulomatosis, patients with active interstitial pneumonitis or extensive pulmonary lesions frequently showed higher values of plasma thrombomodulin than those without overt pulmonary involvement. Elevated plasma thrombomodulin values were decreased along with amelioration of the diseases by treatment. These results may indicate that plasma thrombomodulin measurement may be helpful for evaluating vascular injury in patients with collagen diseases.