Study of Antiphospholipid Antibodies in Patients with Arterial Hypertension

Antiphospholipid syndrome (APS) is a multifactorial, autoantibody-mediated disease. Antiphospholipid antibodies (aPL) directed against negatively charged phospholipids or various combinations of phospholipid-binding proteins seem to be an independent pathogenic factor that plays a critical role in APS. Unfortunately, their role in hypertension is not fully elucidated. The aim of our study was to determine aPL titers in hypertension patients and investigate the association of aPL with renal impairment parameters. Forty-seven patients with arterial hypertension (22 males, 46.8% and 25 females, 53.2%), aged 41⁻85 years old (mean 65.9 ± 10.1 years), and 21 age-sex-matched subjects without severe hypertension as control group (8 males, 13 females, 38.1% vs. 61.9%), mean age 61 ± 11.3 years, were enrolled in this study. Patients with other risk factors like Rheumatoid Arthritis and Systematic Lupus Erythematosus (SLE), both viral and bacterial acute infections, and cancer were excluded from the study. The aPL (anticardiolipin (ACA) and anti-b2GPI antibodies, IgG and IgM) were measured by ELISA (Aesculisa, Aesku Diagnostics, Wendelsheim, Germany) with a cutoff of 15 GPL/MPL for ACA and 15 U/mL for b2GPI. Serum Neutrophil gelatinase-associated lipocalin (sNGAL) was measured by ELISA kits (BioVendor, Brno, Czech Republic). Biochemical analysis such as serum creatinine (Cr), were measured by automated analyzer and finally estimated glomerular filtration rate (e-GFR) was calculated by the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI). Fifteen patients were positive for ACA IgG (31.9%), two for anti-b2GPI IgM (4.2%), and three for anti-b2GPI IgG (6.3%). Furthermore, three persons from control group were positive in anti-b2GPI IgG (14.27%). The serum level of anti-b2GPI IgG was significantly higher in patients compared to healthy controls (p = 0.013). The level of sNGAL (59.63 ± 41.5 ng/mL vs. 45.5 ± 21.5 ng/mL, p = 0.14) was not higher in hypertensive patients than in the age-sex-matched control group. Additionally, the sNGAL level was found to be directly and positively correlated in patients with positive ACA IgG (r² = 0,945, p < 0.0001). These results demonstrate that autoimmunity may be one of the pathogenetic factors of hypertension and aPL antibodies might be a potential marker of renal involvement.