Modification of lupus-associated 60-kDa Ro protein with the lipid oxidation product 4-hydroxy-2-nonenal increases antigenicity and facilitates epitope spreading.
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.
Scofield
R Hal
RH
Arthritis and Immunology Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA. hal-scofield@omrf.ouhsc.edu
Kurien
Biji T
BT
Ganick
Samantha
S
McClain
Micah T
MT
Pye
Quentin
Q
James
Judith A
JA
Schneider
Rebecca I
RI
Broyles
Robert H
RH
Bachmann
Michael
M
Hensley
Kenneth
K
D000447:Aldehydes / Q000494:pharmacology; D000818:Animals; D000941:Antigens / Q000737:chemistry; D001324:Autoantigens / Q000737:chemistry*; D015551:Autoimmunity; D002417:Cattle; D004247:DNA / Q000737:chemistry; D004591:Electrophoresis, Polyacrylamide Gel; D004797:Enzyme-Linked Immunosorbent Assay; D000939:Epitopes / Q000737:chemistry; D006367:HeLa Cells; D006433:Hemocyanins / Q000737:chemistry; D006801:Humans; D015151:Immunoblotting; D015227:Lipid Peroxidation; D008180:Lupus Erythematosus, Systemic / Q000097:blood* / Q000276:immunology*; D008856:Microscopy, Fluorescence; D018384:Oxidative Stress; D010100:Oxygen / Q000737:chemistry / Q000378:metabolism; D010455:Peptides / Q000737:chemistry; D010957:Plasmids / Q000378:metabolism; D011506:Proteins / Q000737:chemistry; D020733:RNA, Small Cytoplasmic / Q000737:chemistry*; D011817:Rabbits; D012261:Ribonucleoproteins / Q000737:chemistry*; D013997:Time Factors; D000099207:SS-A Antigen
D000447:Aldehydes; D000941:Antigens; D001324:Autoantigens; D004247:DNA; D000939:Epitopes; D006433:Hemocyanins; D010100:Oxygen; D010455:Peptides; D011506:Proteins; D020733:RNA, Small Cytoplasmic; D012261:Ribonucleoproteins; C116006:RO60 protein, human; D000099207:SS-A Antigen; C032808:keyhole-limpet hemocyanin; C027576:4-hydroxy-2-nonenal