Antinuclear antibodies recognize cellular autoantigens driven by apoptosis.
OBJECTIVE
Present study addresses the issue whether cellular antigens recognised by antinuclear autoantibodies are driven by apoptosis.


METHODS
HEp-2 cells were committed to apoptosis by camptothecin; DNA fragmentation and FasL and Bax expression monitored apoptosis. Autoantigens were probed by indirect immunofluorescence and Western blot with autoantibodies or monoclonals against: DNA, Ro60, La, U1-RNP, CENP-B, DNA Topoisomerase I, Jo-1 and NuMA. A comparison of antinuclear antibody reactivity between living and apoptotic cells was performed by ELISA.


RESULTS
Apoptotic changes such as chromatin fragmentation, blebs and apoptotic bodies were induced with 20 mM camptothecin. Autoantigens were better detected in apoptotic cells. U1-RNP, Jo1, DNA-Topoisomerase I, CENP-B and NuMA exhibited fragmentation and redistribution as a consequence of apoptosis; in contrast, Ro60 and La ribonucleoproteins did not show proteolysis. Additionally the ELISA titers of antinuclear antibodies were higher in apoptotic cells than in normal cells.


CONCLUSIONS
Apoptosis induces molecular changes in different autoantigens, this modification increases the antigen-driven response of autoantibodies such as anti-RNP, anti-DNA Topoisomerase I, anti-CENP-B and anti-Jo1. Apoptotic changes would contribute to break down the tolerance in autoimmune connective tissue disease.
Ramírez-Sandoval
Roxana
R
Department of Molecular Biology, Centro de Biología Experimental, Universidad Autónoma de Zacatecas, Chepinque 306, Col. Lomas de la Soledad, 98040, Zacatecas, Mexico.
Sánchez-Rodríguez
Sergio H
SH
Herrera-van Oostdam
David
D
Avalos-Díaz
Esperanza
E
Herrera-Esparza
Rafael
R
D000974:Antibodies, Antinuclear / Q000276:immunology*; D017209:Apoptosis / Q000187:drug effects / Q000276:immunology*; D001324:Autoantigens / Q000276:immunology* / Q000378:metabolism; D015153:Blotting, Western; D002166:Camptothecin / Q000494:pharmacology; D002460:Cell Line; D053938:DNA Fragmentation; D004847:Epithelial Cells / Q000187:drug effects / Q000276:immunology / Q000473:pathology; D053222:Fas Ligand Protein; D019084:Fluorescent Antibody Technique, Indirect; D006801:Humans; D008562:Membrane Glycoproteins / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2; D017412:Ribonucleoprotein, U1 Small Nuclear / Q000276:immunology; D051028:bcl-2-Associated X Protein
D000974:Antibodies, Antinuclear; D001324:Autoantigens; C494826:BAX protein, human; C505661:FASLG protein, human; D053222:Fas Ligand Protein; D008562:Membrane Glycoproteins; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D017412:Ribonucleoprotein, U1 Small Nuclear; D051028:bcl-2-Associated X Protein; D002166:Camptothecin