TROPHOBLASTIC APOPTOSIS IN MICE WITH PRETERM DELIVERY AND ITS SUPPRESSION BY URINARY TRYPSIN-INHIBITOR

Objective: To investigate histopathologic changes of the placenta in m ice with preterm delivery induced by lipopolysaccharide and the effect of urinary trypsin inhibitor. Methods: Female C3H/HeN mice impregnate d by male B6D2F1 mice were treated with lipopolysaccharide (50 mu g/kg , intraperitoneally) or lipopolysaccharide plus urinary trypsin inhibi tor (25 x 10(4) U/kg, intraperitoneally). At 3, 6, 9, and 18 hours aft er the second dose of lipopolysaccharide, and at delivery in the contr ol and urinary trypsin inhibitor-treated groups, the concentrations of interleukin-1 alpha and tumor necrosis factor-alpha were determined i n serum and amniotic fluid. Subsequently, the placentas were examined. In the same manner, we examined mice treated with interleukin-1 alpha (250 mu g/kg, subcutaneously) on day 15 of pregnancy and intact mice on days 15 and 18 of pregnancy as well as at delivery. To assess the d irect action of cytokines, we cultured placental slices with tumor nec rosis factor-alpha, interleukin-1 alpha, or tumor necrosis factor-alph a plus urinary trypsin inhibitor and examined them morphologically. Re sults: Control mice were characterized by trophoblastic apoptosis and increased serum levels of tumor necrosis factor-alpha and interleukin- 1 alpha. In contrast, urinary trypsin inhibitor-treated mice showed su ppression of apoptosis and lower cytokine levels. Interleukin-1 alpha induced trophoblastic apoptosis and increased the serum level of tumor necrosis factor-alpha. The in vitro study showed that tumor necrosis factor-alpha directly induced trophoblastic apoptosis in placental sli ces. Conclusion: We demonstrated that trophoblastic apoptosis occurs i n the placentas of a mouse model with preterm delivery induced by lipo polysaccharide. We postulated that apoptosis may lead to placental abr uption, and its development may be prevented by treatment with urinary trypsin inhibitor. (C) 1997 by The American College of Obstetricians and Gynecologists.