Antibodies to N-homocysteinylated albumin in patients with systemic lupus erythematosus

Abstract

Introduction. Hyperhomocysteinemia is known to predispose to atherosclerosis and occurs more commonly in patients with systemic lupus erythematosus (SLE) than in the general population. It has been shown that elevated plasma total homocysteine (tHcy) results in protein N-homocysteinylation and production of autoantibodies against N-homocysteinylated (N-Hcy) proteins.

Objectives. The aim of the study was to investigate whether anti-N-Hcy-albumin antibodies occur in patients with SLE and identify factors that determine these antibodies in such population.

Patients and methods. In 50 subjects with SLE and 50 age- and sex-matched healthy controls, we determined serum IgG antibodies to N-Hcy-albumin using an in-house enzyme linked immunosorbent assay.

Results. Patients had higher plasma tHcy and C-reactive protein (CRP) than controls, while serum folate and witamin B12 were lower in patients. Levels of anti-N-Hcy-albumin were higher in patients with SLE than in controls (medians: 0.31; vs 0.19; P <0.0001). In SLE patients, levels of anti- N-Hcy-albumin antibodies correlated with tHcy (r = 0.83; P <0.0001), CRP (r = 0.33; P = 0.02) and the duration of the disease (r = 0.3; P = 0.04). Seropositivity to anti-N-Hcy-albumin antibodies was more frequent in SLE patients than in controls (50% vs 10%; P <0.001). In SLE patients tHcy and CRP concentrations, along with the duration of the disease were independent predictors of anti-N-Hcy-albumin antibodies level. There were no associations between a type or levels of antinuclear antibodies patent’s, or age with anti-N-Hcy-albumin antibodies.

Conclusions. Compared with healthy controls, in SLE patients levels of anti-N-Hcy-albumin antibodies are significantly higher and are largely determined by tHcy, CRP and the disease duration. This novel autoimmune response might contribute to increased risk of vascular events in SLE patients.