title: Immunohistochemical distribution of Toll-like receptor 4 in term and preterm human placentas from normal and complicated pregnancy including chorioamnionitis.
abstract: Recently discovered Toll-like receptors (TLRs) are essential for the induction of innate immune responses. One member of the TLR family, TLR4 mediates lipopolysaccharide (bacterial endotoxin)-induced inflammatory responses. Although the innate immune system appears to be important in the pathogenesis of infection-induced preterm delivery, the distribution of TLRs in human placenta is poorly understood. Here we investigated the expression of TLR4 protein in 43 human placentas obtained from normal and complicated pregnancies delivered in the second and third trimesters, using immunohistochemistry. TLR4 was localized to the extravillous trophoblasts, intermediate trophoblasts/X cells in the degenerative villi, and villous Hofbauer cells of all preterm and term placentas examined and to the inflammatory cells in placentas with chorioamnionitis (CAM). The villous Hofbauer cells of preterm CAM placentas demonstrated increased TLR4 immunoreactivity compared with those of preterm placentas without CAM or those of term placentas with or without CAM. These results suggest an important role of the villous Hofbauer cells in the activation of innate immune system in response to infectious pathogens in preterm placentas. Elucidation of biological functions of placental TLR4 under physiological conditions requires further investigation.
authors.affiliation: Department of Molecual Medicine, Osaka Medical Center and Research Institute for Maternal and Child Health, Osaka, Japan.
authors.forename: Kaori
authors.initials: K
authors.lastname: Kumazaki
authors.forename: Masahiro
authors.initials: M
authors.lastname: Nakayama
authors.forename: Itaru
authors.initials: I
authors.lastname: Yanagihara
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Suehara
authors.forename: Yoshinao
authors.initials: Y
authors.lastname: Wada
mesh_terms: D002821:Chorioamnionitis / Q000150:complications / Q000378:metabolism* / Q000473:pathology; D002824:Chorionic Villi / Q000378:metabolism / Q000473:pathology; D005260:Female; D019084:Fluorescent Antibody Technique, Indirect; D006801:Humans; D007124:Immunoenzyme Techniques; D008562:Membrane Glycoproteins / Q000378:metabolism*; D007752:Obstetric Labor, Premature / Q000209:etiology / Q000378:metabolism* / Q000473:pathology; D010920:Placenta / Q000378:metabolism* / Q000473:pathology; D011247:Pregnancy; D011262:Pregnancy Trimester, Second; D011263:Pregnancy Trimester, Third; D011956:Receptors, Cell Surface / Q000378:metabolism*; D051197:Toll-Like Receptor 4; D051193:Toll-Like Receptors; D014327:Trophoblasts / Q000378:metabolism / Q000473:pathology
chemical_list: D008562:Membrane Glycoproteins; D011956:Receptors, Cell Surface; C495345:TLR4 protein, human; D051197:Toll-Like Receptor 4; D051193:Toll-Like Receptors