Modification of lupus-associated 60-kDa Ro protein with the lipid oxidation product 4-hydroxy-2-nonenal increases antigenicity and facilitates epitope spreading

Free Radic Biol Med. 2005 Mar 15;38(6):719-28. doi: 10.1016/j.freeradbiomed.2004.11.001.

Abstract

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease with autoantibodies as a near universal feature of the disease. The Ro ribonucleoprotein particle, composed of a 60-kDa protein noncovalently associated with human cytoplasmic RNA, is the target of antibodies in 25-40% of lupus patients. Purified human 60-kDa Ro was found to be oxidatively modified. Earlier investigations from our laboratory revealed increased oxidative damage in SLE patients. Therefore we hypothesized that oxidation by-products, such as 4-hydroxy-2-nonenal (HNE), could lead to neoantigens like HNE-modified 60-kDa Ro, which could in turn initiate autoimmunity or drive epitope spreading. To test this hypothesis we immunized rabbits with either HNE-modified 60-kDa Ro or the unmodified Ro. Intramolecular epitope spreading within the Ro molecule and intermolecular epitope spreading to La, double-stranded DNA, nRNP, and Sm occurred preferentially in HNE-Ro-immunized animals. Nonspecific anti-HNE antibody, generated by immunization with HNE-keyhole limpet hemocyanin conjugate, did not significantly bind to these autoantigens. These data may suggest a hitherto unappreciated mechanism by which oxidative stress facilitates epitope spreading in SLE.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Aldehydes / pharmacology
  • Animals
  • Antigens / chemistry
  • Autoantigens / chemistry*
  • Autoimmunity
  • Cattle
  • DNA / chemistry
  • Electrophoresis, Polyacrylamide Gel
  • Enzyme-Linked Immunosorbent Assay
  • Epitopes / chemistry
  • HeLa Cells
  • Hemocyanins / chemistry
  • Humans
  • Immunoblotting
  • Lipid Peroxidation*
  • Lupus Erythematosus, Systemic / blood*
  • Lupus Erythematosus, Systemic / immunology*
  • Microscopy, Fluorescence
  • Oxidative Stress
  • Oxygen / chemistry
  • Oxygen / metabolism
  • Peptides / chemistry
  • Plasmids / metabolism
  • Proteins / chemistry
  • RNA, Small Cytoplasmic / chemistry*
  • Rabbits
  • Ribonucleoproteins / chemistry*
  • Time Factors

Substances

  • Aldehydes
  • Antigens
  • Autoantigens
  • Epitopes
  • Peptides
  • Proteins
  • RNA, Small Cytoplasmic
  • Ribonucleoproteins
  • TROVE2 protein, human
  • DNA
  • Hemocyanins
  • keyhole-limpet hemocyanin
  • 4-hydroxy-2-nonenal
  • Oxygen