W. Farrugia et al., Effect of bacterial endotoxin on the in vitro release of type II phospholipase-A(2) and prostaglandin E-2 from human placenta, J ENDOCR, 160(2), 1999, pp. 291-296
The aim of this study was to establish the effect of bacterial endotoxin li
popolysaccharide (LPS) on the release of Type II phospholipase-A(2) (PLA(2)
) and prostaglandin E-2 (PCE2) from late-pregnant human placental tissue in
cubated in vitro. Under basal conditions, immunoreactive Type II PLA(2) and
PGE(2) were released from tissue explants in a time-dependent manner (up t
o 24 h, ANOVA, P<0.0001, n=6). The release of these mediators was not assoc
iated with a loss of cell membrane integrity, as indicated by concentration
s of the intracellular enzyme, lactate dehydrogenase (LDH), in the incubati
on medium. Incubation of explants in the presence of LPS (0.001-100 mu g LP
S/ml) significantly decreased PLA(2) tissue content (P<0.02, n=6) and incre
ased the accumulation of PLA(2) and PGE(2) in the incubation medium (P<0.00
01, n=6). The data obtained in this study indicated that Type II PLA(2) and
PGE(2) are released from term placenta under basal conditions and that LPS
stimulated their release. The associated decrease in PLA(2) tissue content
is consistent with the hypothesis that LPS induces the release of stored P
LA(2). This study identifies one pathway by which products of bacterial inf
ection may induce the release of a pro-inflammatory, extracellularly active
PLA(2) from intrauterine tissues that may promote the formation of phospho
lipid metabolites involved in the process of labour and delivery (e.g. the
prostaglandins).