In arterial occlusive disease autoantibodies against ETAR and AT1R correlate with each other but are not associated with classical cardiovascular risk factors

Abstract

Background: Autoantibodies (Abs) against angiotensin-II type 1 (AT1R) and endothelin-1 type A receptors (ETAR) are investigated in the present study as B-cell originated humoral factors that may activate the respective receptors on endothelial cells. The prevalence of the Abs was determined in patients with peripheral arterial occlusive disease (PAD). Patients and methods: In a prospective observational study 200 patients undergoing angiography and proven advanced PAD were enrolled. Serum samples, clinical data and laboratory values for classical cardiovascular risk factors were collected. Autoantibody titers for AT1R and ETAR were determined by solid-phase ELISA and correlative analyses with laboratory parameters and clinical data for common cardiovascular risk factors were performed. Results: Anti-ETAR antibody titers were detected in 57 % of the patients, elevated anti-AT1R titers in 61.5 %. About 50 % were positive for both Abs. A strong intercorrelation between ETAR and AT1R titers was present (r2 0.79). In patients with positive titers for both Abs females presented significantly higher titers for ETAR (p = 0.045) and AT1R (p = 0.02). Autoantibody titers directed against surface receptors ETA and AT1 are highly correlated in PAD. Titers were independent from classical risk factors in any patient subgroup. Conclusions: This study opens a new perspective on the involvement of the immune system, hereby represented by functional autoantibodies, in the atherosclerotic pathophysiology, leaving behind the common background of classical risk factors.