Expression of metallothioneins in placental and fetal tissues in undisturbed and PGM-Zn treated syngeneic pregnancy

Metallothioneins (MTs) are cysteine-rich proteins, which have been implicated in regulation of physiological processes, such as cell growth, repair, differentiation, apoptosis and immunoregulation, as well as in the protection against heavy metals, oxidant damages, inflammation and other stressful conditions. To investigate their roles in physiological and detoxification processes at the maternal-fetal interface and in fetal organogenesis we examined the tissue expression of MT I/II isoforms in undisturbed syngeneic pregnancy and after the treatment with peptidoglycan monomer linked with zinc (PGM-Zn). The data showed that in undisturbed pregnancy the MTs were highly expressed at junctional zone of placenta, on endovascular trophoblast giant cells, glycogen cells and spongiotrophoblast cells, as well as on villous trophoblast cells. In the fetus they were found predominantly in the liver and in epithelial tissues, such as intestine, pancreas and kidney. Treatment with PGM-Zn markedly enhanced the intensity of MT staining both at the maternal-fetal interface and in fetal organs. The data imply that MTs are involved in the protection of trophoblast cells against the pregnancy-induced deregulation of redox and neuro-immuno-endocrine homeostasis, in transport and storage of essential metals required for fetal organogenesis, as well as in the protection of fetus against bacterial toxins.