Interleukin-1 is induced in the human placenta by endotoxin and isolation procedures for trophoblasts.
Although freshly obtained placenta contains little or no interleukin-1 (IL-1) mRNA, placenta and isolated trophoblast have been reported to produce significant quantities of bioactive IL-1 in vitro. The present study was designed to determine if endotoxin, a common contaminant of culture medium, and trophoblast isolation procedures could induce IL-1 expression in the placenta. Tissue-extractable IL-1 alpha and IL-1 beta immunoreactive proteins were readily detected in fresh placental membranes, but not placental villi. As little as 10 ng/mL endotoxin were found to induce the expression of IL-1 alpha and IL-1 beta mRNA in intact placental villi cultured in vitro. Intact placenta cultured in the presence of 1.0 microgram/mL endotoxin demonstrated expression of IL-1 alpha and IL-1 beta mRNA and cumulative production and release of immunoreactive IL-1 alpha and IL-1 beta into the medium during 24 h of culture. Placenta incubated in endotoxin-free medium, however, exhibited no detectable IL-1 alpha or IL-1 beta mRNA expression and little or no release of IL-1 alpha or IL-1 beta immunoreactive protein into the medium. When trophoblast cells were freshly isolated by enzymatic digestion, followed by Percoll separation at reduced temperatures to inhibit cell activation, no IL-1 alpha or IL-1 beta mRNA expression was initially detectable. However, IL-1 alpha and IL-1 beta mRNA in isolated trophoblast cells were induced after 30 min of culture in endotoxin-free medium, with maximal induction at 4 h. These results suggest that normally the placenta produces very little, if any, IL-1, and that endotoxin and trophoblast isolation procedures induce IL-1 expression in placental tissues cultured in vitro.
Kauma
S W
SW
Department of Obstetrics and Gynecology, Virginia Commonwealth University, Medical College of Virginia, Richmond 23298.
Walsh
S W
SW
Nestler
J E
JE
Turner
T T
TT
D002469:Cell Separation / Q000379:methods*; D003470:Culture Media; D004731:Endotoxins / Q000494:pharmacology*; D005260:Female; D006801:Humans; D007375:Interleukin-1 / Q000096:biosynthesis* / Q000235:genetics; D010920:Placenta / Q000378:metabolism*; D011247:Pregnancy; D012333:RNA, Messenger / Q000378:metabolism; D011863:Radioimmunoassay; D014327:Trophoblasts / Q000166:cytology*
D003470:Culture Media; D004731:Endotoxins; D007375:Interleukin-1; D012333:RNA, Messenger