Abstract 16797: Identification of Malondialdehyde-Acetaldehyde-Modified Proteins From Affected Tissues in Rheumatoid Arthritis and Cardiovascular Disease
Introduction: We have shown that MAA-modified proteins co-localize with citrullinated antigen in rheumatoid arthritis (RA) synovium. Although both MAA-adducts and citrullinated antigen have been identified separately in atheromas of patients with cardiovascular disease (CVD), it is unknown whether these modifications conspire to promote atherogenesis. Thus, we sought to first characterize macromolecules that are MAA-modified in RA and/or CVD tissues and thus might play a role in shared disease processes.
Methods: We examined synovial tissues from ACPA positive RA and osteoarthritis (OA) patients as well as atheromas from CVD patients without RA and unaffected cardiac tissues. Tissues were homogenized and incubated with rabbit anti-MAA polyclonal antiserum. Antigen-antibody complexes were isolated using Protein-G Sepharose magnetic beads, separated by SDS-PAGE, and visualized using silver staining. Bands that appeared to be unique to RA and/or CVD were analyzed using NanoLC-MS/MS for protein/peptide sequence determination, and identified using SwissProt or EMBL (Applied Biomics).
Results: MAA antibody immunoprecipitated RA synovial tissues demonstrated a number of proteins that were not detected in OA synovial tissues (not shown). Two of these proteins were identified: A) Phosphatidylcholine transfer protein; and, B) Ig gamma-1 C region. Using MAA antibody immunoprecipitated lysates of atheromas, we identified a number of MAA-modified proteins that were not observed in normal cardiac tissue: Lysozyme, S-100 heat shock protein, Albumin, and Ig gamma-1 C region. These proteins were confirmed by Western blot using specific commercial antibodies. MAA-modified Ig gamma-1 C region protein was common to both RA synovial tissues and atheromas.
Conclusions: These experiments were designed to begin determining the specific antigens that are MAA-modified and/or citrullinated, and suspected to be involved in the shared pathogenesis of RA and CVD. As expected, there were multiple proteins present in synovial tissues and/or atheromas harboring MAA-modifications. We have identified 1 protein (Ig gamma-1 C region) common to both types of tissues and studies are underway to evaluate its potential role in RA-related CVD.
Author Disclosures: M.J. Duryee: None. D.L. Clemens: None. L.W. Klassen: None. T.R. Mikuls: None. M.C. Pomplun: None. D.R. Anderson: None. G.M. Thiele: None.
- © 2017 by American Heart Association, Inc.