Bradykinin and oxidative stress in patients with hereditary angioedema due to C1 inhibitor deficiency

Introduction Hereditary angioedema (HAE) is a rare autosomal dominant disease caused by genetic dysfunction of C1 inhibitor (C1‑INH) due to mutations in the SERPING1 gene. The disorder is mediated mainly by bradykinin. The clinical course of the disease is varied and not related to genetic changes. Objectives We aimed to evaluate redox homeostasis of peripheral blood mononuclear cells (PBMCs) in patients with HAE due to C1‑INH deficiency (C1‑INH‑HAE) by measuring the levels of reactive oxygen species (ROS) of PBMCs as well as plasma advanced glycation end products (AGEs) and advanced oxidation protein products (AOPPs). We also aimed to assess the effect of bradykinin on ROS levels. Patient s and methods We enrolled 30 adults with C1‑INH‑HAE and 15 healthy individuals. The levels of ROS were measured by flow cytometry, while the plasma levels of AGEs and AOPPs were determined spectrophotometrically by enzyme‑linked immunosorbent assays. Result s Basal and hydrogen peroxide (H2O2)–induced ROS levels were higher in patients with HAE when compared with controls (P = 0.002 and P = 0.001, respectively), indicating abnormalities in redox homeostasis. Plasma AOPP and AGE levels were similar in both groups. Bradykinin reduced basal and H2O2‑induced ROS generation in PBMCs only in patients with HAE (P = 0.03). Conclusions The higher basal and H2O2‑induced ROS levels in patients with C1‑INH‑HAE indicate redox imbalance. However, by reducing basal and H2O2‑induced ROS levels, bradykinin shows antioxidant action in this disorder.