Expression of the neonatal Fc-receptor in placental-fetal endothelium and in cells of the placental immune system. (March 2019)

• Record Type: Journal Article
• Authors: Kiskova, Terezia; Mytsko, Yuliya; Schepelmann, Martin; Helmer, Hanns; Fuchs, Renate; Miedl, Heidi; Wadsack, Christian; Ellinger, Isabella
• Is Part Of: Placenta. Volume 78(2019)
• Page Start: 36
• Page End: 43
• Publication Date: 2019-03
• Subjects: Human placenta -- FcRn -- Syncytiotrophoblast -- Placental-fetal endothelial cells -- Placental macrophages -- IgG transport; Human neonatal Fc receptor FcRn -- Syncytiotrophoblast STB -- Placental-fetal endothelial cells pFEC -- Human placental arterial endothelial cells HPAEC -- Human placental venous endothelial cells HPVEC; Placenta -- Periodicals; Reproduction -- Periodicals; Placenta -- Periodicals; Placenta -- Périodiques; Reproduction -- Périodiques; 612.63
• DOI: 10.1016/j.placenta.2019.02.012
• Languages: English
• ISSNs: 0143-4004

Abstract

Abstract: Introduction: Starting from the second trimester of pregnancy, passive immunity is provided to the human fetus by transplacental transfer of maternal IgG. IgG transfer depends on the neonatal Fc receptor, FcRn. While FcRn localization in the placental syncytiotrophoblast (STB) has been demonstrated unequivocally, FcRn expression in placental-fetal endothelial cells (pFECs), which are part of the materno-fetal barrier, is still unclear. Therefore, this study aimed to elucidate the spatio-specific expression pattern of FcRn in placental tissue. Methods: FcRn expression was investigated by western blotting in term placentas and in isolated human placental arterial and venous endothelial cells (HPAEC, HPVEC) using a validated affinity-purified polyclonal anti-peptide antibody against the cytoplasmic tail of FcRn α-chain. In situ localization of FcRn and IgG was studied by immunofluorescence microscopy on tissue sections of healthy term placentas. Results: FcRn expression was demonstrated in placental vasculature particularly, in HPAEC, and HPVEC. FcRn was localized in cytokeratin 7 + STB and in CD31 + pFECs in terminal as well as stem villi in situ . Additionally, CD68 + placental macrophages exhibited FcRn expression in situ . Endogenous IgG partially co-localized with FcRn in STB, pFECs, and in placental macrophages. Discussion: Placental FcRn expression in endothelial cells and macrophages is analogous to the expression pattern in other organs. FcRn expression in pFECs suggests an involvement of FcRn in IgG transcytosis and/or participation in recycling/salvaging of maternal IgG present in the fetal circulation. FcRn expression in placental macrophages may account for recycling of monomeric IgG and/or processing and presentation of immune complexes. Graphical abstract: Image 1 Highlights: FcRn is expressed in placental-fetal endothelial cells in situ . FcRn is expressed in cultured primary placental endothelial cells. FcRn co-localizes with IgG in placental endothelial cells in situ . FcRn is expressed in placental macrophages in situ .