TGF beta 2 in embryos with inborn anomalies: Effect of maternal immunopotentiation

PROBLEM: TGF betas are among the main immunoregulatory molecules contributi ng to successful embryonic development. Besides, our and other studies reve aled that maternal immunopotentiation has a potential to increase the resis tance of the embryo to the teratogenic insult. This work was designed to ev aluate: (1) whether the formation of teratogen-induced anomalies is accompa nied by an altered pattern of TGF beta2 expression in embryonic cells and ( 2) whether maternal immunopotentiation modifies the pattern of TGF beta2 ex pression in embryos responding to the teratogenic insult. METHOD OF STUDY: Experiments were performed in embryos of ICR mice exposed to 15 and 40 mg/kg of a reference teratogen, cyclophosphamide (CP) on day 1 2 of gestation. A group of mice was immunopotentiated with xenogeneic rat s plenocytes 21 hr before the beginning of mating. Embryos were examined for the occurrence of gross structural anomalies 24 and 72 hr after CP treatmen t. Then, immunohistochemistry and in situ hybrydization assays were used to evaluate the expression of TGF beta2 protein and mRNA in the brain, face, limbs and liver of these embryos. RESULTS: No external anomalies were observed in embryos examined 24 hr afte r CP treatment. Embryos examined 72 hr after CP treatment at 40mg/kg exhibi ted agnathia, micrognathia, kinky tail, phocomelia, but no signs of dismorp hogenesis were observed in the liver at the organ level. A significant incr ease in the expression of TGF beta2 mRNA was observed in cells, residing in the brain, face and limbs but not in the liver of CP-exposed embryos teste d 24 hr after CP injection in both doses. The level of TGF beta2 protein in these embryos did not differ from that of controls. In embryos tested 72 h r after CP injection in the high dose both TGF beta2 protein and mRNA expre ssion were found to be elevated. Maternal immunopotentiation while enhancin g the embryo's resistance to CP practically abolished an elevated expressio n of the TGF beta2 mRNA detected in tested organ structures of embryos of n on-immunopotentiated CP treated mice 24 hr after CP injection in both the l ow and the high doses. Also, a significant decrease in the level of TGF bet a2 mRNA expression was observed in embryos of immunopotentiated mice examin ed 72 hr after CP treatment. CONCLUSIONS: The results of this work show a possible involvement of TGF be ta2 in the formation of teratogen-induced structural anomalies and suggest that the stimulation of the maternal immune system may realize its protecti ve effect by normalizing the level of TGF beta2 expression in teratogen-tar geted embryonic structures.