BIOBRAD Study: The Search for Biomarkers of Bradykinin-Mediated Angio-Oedema Attacks

The aetiology of angio-oedema (AE) is difficult to determine; however, it is essential in emergency situations when two major contexts may be present: mast cell-mediated AE and bradykinin-mediated AE. Different forms of AE are currently distinguished based on clinical criteria (spontaneous duration of the attack, presence of concomitant or late-appearing superficial urticaria, history of atopy, and others), but specific biomarkers could improve patient management.

In this prospective study, potential biomarkers have been identified, and their statistical characteristics were examined.

Samples were taken on day 0 (D0) and D7 for 3 patient groups (n = 11 each): bradykinin-mediated AE [peripheral site of attack, ear, nose, throat (ENT), and abdominal involvement], mast cell-mediated AE, and non-bradykinin-mediated abdominal pain.

Assay of the potential biomarkers revealed no significant differences in C1 inhibitor and C4 levels. In contrast, D-dimer levels peaked during bradykinin-mediated AE attacks (median 2.2 mg/l at D0 vs. 0.52 mg/l at D7; p < 10-3) as well as during mast cell-mediated AE attacks (1.97 vs. 0.65 mg/l; p = 0.04) and were high in bradykinin-mediated AE compared to the control group (0.69 mg/l; p = 0.01). A threshold value of 0.62 mg/l was found to have a negative predictive value of 100% for bradykinin-mediated AE compared to other causes of abdominal pain (group 3). Circulating VE-cadherin levels were also increased during an attack (1,990 at D0 vs. 1,566 ng/ml at D7; p = 0.01), but could not distinguish between bradykinin-mediated and mast cell-mediated AE, like D-dimers.

Exploration of changes in fibrinolysis-related markers (particularly D-dimers) is thus promising for the diagnosis of AE attacks in difficult-to-diagnose abdominal forms, although it was not able to differentiate between bradykinin and mast cell-mediated AE.