Enhanced reactivity to malondialdehyde-modified proteins by systemic lupus erythematosus autoantibodies

Evaluation of the reactivity of autoantibodies of systemic lupus erythematosus (SLE) patients directed against malondialdehyde (MDA)-modified catalase, superoxide dismutase (SOD), and different Hep2 protein fractions (hydrophobic, hydrophilic, and nuclear).Thiol groups and MDA-protein adducts were first assessed among 65 SLE patients and 60 healthy controls. Then, the reactivities of SLE immunoglobulin (Ig)G autoantibodies towards MDA-modified and unmodified proteins were compared using a standard enzyme-linked immunosorbent assay (ELISA).An increase in the levels of MDA-modified proteins and a decrease in the concentration of thiol groups among SLE patients (p0.05) were observed. IgG circulating autoantibodies in the sera of SLE patients exhibited a significant enhanced reactivity (p0.05) against catalase and SOD-modified proteins. The same data were observed in the different protein fractions extracted from cultured cells (p0.05).These data reinforce the role of oxidative stress and especially lipid peroxidation products in the progression of SLE disease.