title: Toll-like receptor 2 and class B scavenger receptor type I are required for bacterial uptake by trophoblast giant cells.
abstract: Trophoblast giant (TG) cells, components cells of the mouse placenta, exhibit phagocytic activity, and participate in the placental defense system by extracellular bacterial antigen uptake via phagocytosis. However, the bacterial uptake mechanisms by TG cells remain to be entirely understood. In an attempt to understand these mechanisms, in this study, we investigated the pattern recognition receptors (PRRs) involved in phagocytosis by TG cells. PRRs such as Toll-like receptors (TLRs) and scavenger receptors play a critical role in the immune response to bacterial pathogens. Among these, we selected TLR2 and class B scavenger receptor type I (SR-BI) and then evaluated their properties in TG cells. TLR2 and SR-BI expression is higher in TG cells than in trophoblast stem (TS) cells. Although interferon-gamma treatment activated bacterial uptake in a concentration-dependent manner, it did not induce TLR2 or SR-BI expression. Depletion of TLR2 and SR-BI by siRNA reduced the bacterial uptake ability of TG cells, which was also affected by treatment with the TLR2 agonist triacylated lipopeptide. These results suggested that the phagocytic activity of TG cells is mediated by both TLR2 and SR-BI.
authors.affiliation: Department of Veterinary Public Health, Faculty of Agriculture, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan.
authors.forename: Kenta
authors.initials: K
authors.lastname: Watanabe
authors.forename: Eun-Kyung
authors.initials: EK
authors.lastname: Shin
authors.forename: Masanori
authors.initials: M
authors.lastname: Hashino
authors.forename: Masato
authors.initials: M
authors.lastname: Tachibana
authors.forename: Masahisa
authors.initials: M
authors.lastname: Watarai
mesh_terms: D000818:Animals; D001419:Bacteria / Q000276:immunology*; D002478:Cells, Cultured; D015726:Giant Cells / Q000276:immunology*; D007371:Interferon-gamma / Q000494:pharmacology; D051379:Mice; D010587:Phagocytosis; D051122:Scavenger Receptors, Class B / Q000502:physiology*; D051195:Toll-Like Receptor 2 / Q000502:physiology*; D014327:Trophoblasts / Q000276:immunology*
chemical_list: C454739:Scarb1 protein, mouse; D051122:Scavenger Receptors, Class B; C493486:Tlr2 protein, mouse; D051195:Toll-Like Receptor 2; D007371:Interferon-gamma