Anti-beta-2 glycoprotein I antibodies affect Bcl-2 and Bax trophoblast expression without evidence of apoptosis.
Antiphospholipid antibodies (aPLs) reacting with beta-2 glycoprotein I (beta2GPI) have been associated with recurrent fetal loss and pregnancy complications. The aim of the study was to investigate whether aPLs with anti-beta2GPI specificity induce apoptosis of human trophoblasts in vitro. To this end, human anti-beta2GPI monoclonal IgM derived from a patient with antiphospholipid syndrome and a human irrelevant monoclonal IgM were incubated with human trophoblast cell cultures for 24, 48, and 72 h. In all the cultures we evaluated: (i) Bcl-2 and Bax mRNA and protein expression by Western blot and reverse transcription polymerase chain reaction (RT-PCR), respectively; (ii) DNA fragmentation by a commercial ELISA kit and by agarose gel electrophoresis; and (iii) the percentage of cells reactive with the monoclonal antibody (MAb) M30 by indirect immunofluorescence. The results were: Bcl-2/Bax ratio increased in untreated trophoblast cells during the time of culture, showing the highest values detectable after 72 h (2.68 and 2.28 at protein and mRNA levels, respectively). Cell incubation with anti-beta2GPI MAbs induced a significant Bcl-2/Bax ratio reduction in comparison with untreated cells (1.22 and 1.28 at protein and mRNA levels, respectively, after 72 h incubation). No significant difference was detected after cell exposure to irrelevant MAbs. However, neither DNA fragmentation nor increase in cells positive for the caspase-cleaved epitope of cytokeratin 18 cytoskeletal protein (M30) was found. In Conclusion, anti-beta2GPI antibodies react with trophoblast cells and reduce the Bcl-2/Bax ratio, but without any clear apoptotic effect.
di Simone
Nicoletta
N
Department of Obstetrics and Gynecology, Università Cattolica de Sacro Cuore, Rome, Italy.
Castellani
Roberta
R
Raschi
Elena
E
Borghi
M Orietta
MO
Meroni
Pier Luigi
PL
Caruso
Alessandro
A
D000906:Antibodies / Q000276:immunology*; D017209:Apoptosis; D002478:Cells, Cultured; D015870:Gene Expression; D006023:Glycoproteins / Q000276:immunology*; D006801:Humans; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics; D014327:Trophoblasts / Q000166:cytology* / Q000276:immunology / Q000378:metabolism*; D051028:bcl-2-Associated X Protein / Q000235:genetics / Q000378:metabolism*; D053482:beta 2-Glycoprotein I
D000906:Antibodies; D006023:Glycoproteins; D019253:Proto-Oncogene Proteins c-bcl-2; D012333:RNA, Messenger; D051028:bcl-2-Associated X Protein; D053482:beta 2-Glycoprotein I