title: Protein S deposition at placenta: a possible role of protein S other than anticoagulation.
abstract: Protein S is an antithrombotic cofactor for protein C that also has multifunctional anti-inflammatory, cellular protective, apoptotic and mitogenic properties. Protein S levels are thought to decrease during pregnancy, but the underlying mechanism remains unknown. We compared protein S concentrations throughout normal pregnancy with those of nonpregnant women and measured plasma C4b-binding protein levels in nonpregnant women and in pregnant women at the 40th gestational week. We also examined protein S and C4b-binding protein in the placenta by immunohistochemical staining at early (20th gestational week) and late (40th gestational week) stages of pregnancy. Plasma protein S activity and free protein S-antigen levels significantly decreased from the 10th gestational week and total protein S antigen decreased from the 20th. C4b-binding protein levels between pregnant and nonpregnant women did not significantly differ. The stainable portion of protein S was located at the fetomaternal interface, particularly at degenerative villi. C4b-binding protein was weakly stained at the same areas as protein S. Neither protein S nor C4b-binding protein were stained at normal villi. These results indicated that protein S can protect or restore damaged villi via a physiological effect in addition to its anticoagulation properties.
authors.affiliation: Department of Obstetrics and Gynecology, Osaka City University Graduate School of Medicine, 1-4-3 Asahi-machi, Abeno-ku, Osaka, Japan. m-0508@med.osaka-cu.ac.jp
authors.forename: Makiko
authors.initials: M
authors.lastname: Matsumoto
authors.forename: Daisuke
authors.initials: D
authors.lastname: Tachibana
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Nobeyama
authors.forename: Akemi
authors.initials: A
authors.lastname: Nakano
authors.forename: Yuichiro
authors.initials: Y
authors.lastname: Nakai
authors.forename: Masahiro
authors.initials: M
authors.lastname: Nakayama
authors.forename: Osamu
authors.initials: O
authors.lastname: Ishiko
mesh_terms: D001777:Blood Coagulation / Q000502:physiology; D050716:Complement C4b-Binding Protein; D005260:Female; D006649:Histocompatibility Antigens / Q000097:blood / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D010920:Placenta / Q000378:metabolism*; D011247:Pregnancy / Q000097:blood / Q000378:metabolism*; D017293:Protein S / Q000378:metabolism*
chemical_list: C055609:C4BPA protein, human; D050716:Complement C4b-Binding Protein; D006649:Histocompatibility Antigens; D017293:Protein S