Effect of maternal immunopotentiation on apoptosis-associated molecules expression in teratogen-treated embryos

Problem: Potentiation of the maternal immune system was shown by us to affect the embryonic response to teratogenic insults. In order to understand better the mechanisms underlying that phenomenon, we explored the effect of maternal immunopotentiation by rat splenocytes on the early stages of the embryonic response to cyclophosphamide (CP). Method of study: Immunopotentiated CP-treated embryos were analysed for cell cycle changes by flow cytometry, while cell proliferation and apoptosis were assessed by 5′-bromo-2′-deoxyuridine (BrdU) incorporation and terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-biotin nick-end labeling (TUNEL) respectively. The expression of the p65 subunit of NF-γB, IγBα, Bax, bcl-2 and p53 was assessed by flow cytometry. Results: Exposure to CP resulted in significant growth retardation and in the appearance of cellular damage, a reduction in cell proliferation and the appearance of apoptotic cells, which were all found to be delayed in immunopotentiated embryos. In parallel, CP-treated embryos demonstrated a reduction in the percentage of p65- or IγBα-positive cells, while the percentage of bcl-2- or p53-positive cells increased initially and decreased later. Those changes were normalized by maternal immunopotentiation when tested at 24 hrs after exposure to the teratogen. Conclusion: Our data implicate maternal immunopotentiation to protect the embryo against teratogenic insults, possibly through its effect on the expression of p65, bcl-2 or p53.