LOCALIZATION OF TRANSFORMING GROWTH-FACTOR-BETA AND ITS NATURAL INHIBITOR DECORIN IN THE HUMAN PLACENTA AND DECIDUA THROUGHOUT GESTATION

Transforming growth factor beta (TGF beta) produced at the human fetom aternal interface has been shown to play a crucial role in controlling trophoblast invasion of the uterus. Decorin, a naturally occurring ch ondroitin-dermatan sulphate proteoglycan which binds TGF beta can inhi bit its activity. lit this study, immunohistochemical techniques were used to determine the locations of TGF beta and decorin within the hum an placenta and decidua throughout normal gestation. In addition, site s of TGF beta(1) mRNA synthesis were identified in early and late plac enta by in situ hybridization. Results revealed the presence of immuno reactive TGF beta in the cytoplasm of villous syncytiotrophoblast and extravillous trophoblast cells throughout gestation. TGF beta immunost aining was absent from villous cytotrophoblast at all gestational ages examined. The extracelluar matrix (ECM) of the villous core at all st ages of gestation and cells of the cytotrophoblastic shelf of the term placenta were immunoreactive for TGF beta. Within decidual tissue, TG F beta was primarily localized in the ECM during the first trimester a nd only a small proportion of decidual cells exhibited intracellular l abelling. At Inter gestational ages the majority of decidual cells sho wed intracellular labelling accompanied by a decrease nt ECM staining. This switch may reflect increased TGF beta synthesis by the decidual cells, decreased release, or altered TGF beta binding to one or move E CM proteins. In sia hybridization indicated that TGF beta(1) mRNA was primarily localized to the syncytiotrophoblast cell layer with low int ensity signals present in extravillous trophoblast cells, in trophobla st cell columns, and in large decidual cells. At term, TGF beta(1) mRN A was located in both the syncytiotrophoblast and villous mesenchymal cells. Decorin was immunolocalized to the ECM of the mesenchymal core of the chorionic villi throughout gestation and no immunoreactivity wa s observed in either villous or extravillous trophoblast. In the first trimester decidua, decorin was localized to the ECM whereas decidual cells, decidual leucocytes, and the uterine epithelium mere negative. At later gestational ages, the ECM as well as a few decidual cells dis played weak immunoreactivity. A strong co-localization of TGF beta and decorin in the ECM of first trimester decidual tissue suggests that d ecorin may aid TGF beta storage or limit its activity in the ECM.