Roles of claudin-5 and von Willebrand factor in patients with rheumatoid arthritis.

Rheumatoid arthritis (RA) is a chronic inflammatory disorder that affects approximately 1% of the world's population. The pathogenesis of RA is not understood fully. It is assumed that endothelial function is associated with the proinflammatory state of RA. Endothelial dysfunction/activation reflects the increased level of von Willebrand factor (vWF) and a shift toward prothrombotic activity of the endothelium. The present study was performed to investigate the possible relationships between vWF and claudin-5 and the level of disease activity in patients with RA. The study population was divided into four groups according to the disease activity score in 28 joints (DAS28): remission group (RG), 18 patients (DAS28 < 2.6); low disease activity group (LDAG), 23 patients (DAS28 > 2.6-3.2); moderate disease activity (MDAG), 23 patients (DAS28 > 3.2-5.1); high disease activity group (HDAG), 14 patients (DAS28 > 5.1); and control group (CG), 10 healthy subjects. Claudin-5 and vWF assessment were derived from serum samples gathered from the patients known to have RF and anti-CCP titers in the normal ranges. A high positive association of claudin-5 and vWF with the MDAG was observed (P < 0.001). The results of our study indicated that the relationship between vWF and claudin-5, which are indicators of endothelial cell dysfunction and tight junction activity, may be a predictor of disease activity. Further studies are required to investigate these pathways to shed light on the roles of claudin-5 and vWF in the progression of inflammation and other vascular conditions.