Invasive trophoblasts stimulate vascular smooth muscle cell apoptosis by a fas ligand-dependent mechanism.
During pregnancy, trophoblasts migrate from the placenta into uterine spiral arteries, transforming them into wide channels that lack vasoconstrictive properties. In pathological pregnancies, this process is incomplete. To define the fundamental events involved in spiral artery remodeling, we have studied the effect of trophoblasts on vascular smooth muscle cells (SMCs). Here we demonstrate for the first time that apoptosis of SMCs can be initiated by invading trophoblasts. When trophoblasts isolated from normal placenta (primary trophoblasts) or conditioned medium was perfused into spiral or umbilical artery segments, apoptosis of SMCs resulted. Culture of human aortic SMCs (HASMCs) with primary trophoblasts, primary trophoblast-conditioned medium, or a trophoblast-derived cell line (SGHPL-4) also significantly increased SMC apoptosis. Fas is expressed by spiral artery SMCs, and a Fas-activating antibody triggered HASMC apoptosis. Furthermore, a Fas ligand (FasL)-blocking antibody significantly inhibited HASMC apoptosis induced by primary trophoblasts, SGHPL-4, or trophoblast-conditioned medium. Depleting primary trophoblast-conditioned medium of FasL also abrogated SMC apoptosis in vessels in situ. These results suggest that apoptosis triggered by the release of soluble FasL from invading trophoblasts contributes to the loss of smooth muscle from the walls of spiral arteries during pregnancy.
Harris
Lynda K
LK
Maternal and Fetal Health Research Centre, Division of Human Development, University of Manchester, St. Mary's Hospital, Manchester, UK.
Keogh
Rosemary J
RJ
Wareing
Mark
M
Baker
Philip N
PN
Cartwright
Judith E
JE
Aplin
John D
JD
Whitley
Guy St J
GS
D017209:Apoptosis; D001158:Arteries / Q000166:cytology; D017077:Culture Media, Conditioned; D053222:Fas Ligand Protein / Q000378:metabolism*; D005260:Female; D006801:Humans; D009131:Muscle, Smooth, Vascular / Q000166:cytology*; D011247:Pregnancy; D013997:Time Factors; D014327:Trophoblasts / Q000166:cytology / Q000473:pathology*; D019014:fas Receptor / Q000378:metabolism
D017077:Culture Media, Conditioned; C491901:FAS protein, human; D053222:Fas Ligand Protein; D019014:fas Receptor