Session Type: ACR Poster Session C
Session Time: 9:00AM-11:00AM
Systemic lupus erythematosus (SLE) is a chronic, complex disease and autoantibodies to self-antigens are a characteristic feature of the disorder. Our group and others have observed free radical mediated oxidative damage in SLE. Our previous data implicated red cell membrane catalase as a target of 4-hydroxy-2-nonenal (HNE; a by-product of oxidative damage) modification in SLE subjects. Here, we tested the hypothesis that HNE- or malondialdehyde- (MDA) modification occurs in the sera of SLE subjects and that antibodies to HNE would be present in SLE sera, and may precede lupus autoantibodies.
Serum proteins from 8 SLE subjects and 8 age and sex-matched normal subjects were analyzed for HNE- or MDA protein-adducts by ELISA. Three additional SLE subjects, who had sera collected longitudinally for 12- 15 years, were tested for the presence of anti-HNE antibodies by ELISA. One SLE subject developed anti-Ro60 under observation and another developed anti-P similarly (after disease diagnosis). The third SLE subject had anti-Sm from time of diagnosis. Ro60, Sm and a multiple antigen peptide synthesized from the P autoantigen were coated on ELISA plates, HNE-modified and used as substrate for anti-HNE ELISA. Unmodified Ro60, Sm and P multiple antigen peptide served as control. To test for HNE or MDA-protein adducts in sera from SLE subjects or normal controls, the sera were coated on ELISA plates as antigen. HNE or MDA adducts in sera was determined with rabbit anti-HNE or anti-MDA antibodies. HNE-modified proteins in sera from SLE or normal controls were also studied by immunoblotting.
We found significantly increased oxidative damage in the sera of SLE subjects compared to normal controls by ELISA and immunoblotting. There was significantly more HNE-protein adducts in SLE sera compared to controls as determined by ELISA (0.084 ± 0.022 versus 0.055 ± 0.012, p=0.0044; average OD±SD). But, we did not observe any significant difference in MDA-modified proteins between SLE subjects and controls. Analysis of SLE sera by immunoblotting showed HNE modification of two proteins migrating at 24 kD and 38 kD respectively. Anti-HNE P autoantibodies preceded anti-P autoantibodies in the SLE subject that developed anti-P antibodies several months after SLE diagnosis. Anti-HNE P antibodies developed strongly in the anti-P SLE subject in the 68th month (1.2 OD), while anti-P response developed only by month 112. Anti-P response was strong by 125th month (1.7 OD). Anti-HNE P response at this time point was 3.0 OD, almost twice as the anti-P response. Anti-HNE Ro60 response preceded anti-Ro60 antibody response by 20 months in the subject developing anti-Ro60 under observation. Anti-HNE Ro60 response correlated with anti-Ro60 response in this subject for the rest of the dates for which samples were available for testing. However, there was no difference in anti-Sm or anti-HNE Sm antibody levels over time for the subject that had anti-Sm autoantibodies right from the time of diagnosis.
Increased HNE-modified protein occur in sera of SLE subjects. Anti-HNE antibody may precede anti-Ro60 or anti-P autoantibodies in SLE. HNE-products are potential neoantigens and thus could be involved in the pathogenesis of SLE.
To cite this abstract in AMA style:Kurien BT, Scofield RH. 4-Hydroxy-2-Nonenal Serum Protein-Adducts and Anti-4-Hydroxy-2-Nonenal-Protein Adduct Antibodies in SLE [abstract]. Arthritis Rheumatol. 2017; 69 (suppl 10). http://acrabstracts.org/abstract/4-hydroxy-2-nonenal-serum-protein-adducts-and-anti-4-hydroxy-2-nonenal-protein-adduct-antibodies-in-sle/. Accessed October 21, 2017.
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