Endothelial cell activation during edematous attacks of hereditary angioedema types I and II.

Hereditary angioedema (HAE) caused by C1-inhibitor (C1-INH) deficiency (HAE-C1-INH) is a potentially life-threatening rare disease caused by the decreased activity of C1-INH. Lack of C1-INH leads to overproduction of bradykinin, a potent vasoactive peptide. Although angioedema is induced by bradykinin, the function and activation of endothelial cells (ECs), the targets of bradykinin, have not yet been studied during HAE attacks. We studied whether EC function is altered during HAE attacks in comparison with attack-free intervals. Forty-six consecutive samples obtained during attacks from 18 patients with HAE-C1-INH were compared with inter-attack samples of the same patients. The patients' sera were tested for von Willebrand factor (VWF) antigen, VWF collagen-binding activity, soluble E-selectin, and endothelin-1 levels by using ELISA and BRAHMS Kryptor technologies. Levels of all 4 EC markers (VWF antigen, VWF collagen-binding activity, soluble E-selectin, and endothelin-1) were significantly increased during HAE attacks. Their increases were even more obvious in the subgroup of patients without any pre-existing risk factors for endothelial dysfunction. In this study we demonstrated that ECs are activated during HAE attacks. Our results might suggest the need for revising the knowledge on the pathogenesis of HAE-C1-INH and for reconsidering the role of ECs as a possible novel therapeutic target in patients with this disease.