BACTERIAL-ENDOTOXIN INCREASES TYPE-II PHOSPHOLIPASE A(2) IMMUNOREACTIVE CONTENT AND PHOSPHOLIPASE A(2) ENZYMATIC-ACTIVITY IN HUMAN CHORIODECIDUA

The aim of this study was to establish the effect of bacterial endotox in lipopolysaccharide (LPS) on type II phospholipase A(2) (PLA(2)) con tent and in vitro net PLA(2) enzymatic activity in human choriodecidua . More particularly, the objective was to ascertain whether an increas e in ripe II PLA(2) tissue content and PLA(2) enzymatic activity is as sociated with the previously documented stimulatory effect of LPS on p rostaglandin E(2) (PGE(2)) release from choriodecidua. Choriodecidua e xplants were incubated in RPMI 1640 (control) or RPMI 1640 containing LPS (0.1 ng/ml to 10 mu g/ml) for up to 24 h. Under the incubation con ditions utilized, LPS (1 mu g/ml) stimulated the release of PGE(2) 3-f old (p < 0.001, n = 4 tissues), in a time-dependent manner (p < 0.005) . Tissue immunoreactive (ir)-type II PLA(2) content and PLA(2) enzymat ic activity were determined by monoclonal antibody sandwich ELISA and radiolabeled enzyme assay procedures, respectively. The tissue content of type II PLA(2) immunoreactivity in choriodecidua obtained from wom en (n = 7) at term but not in labor averaged 155 +/- 24 ng/mg DNA. PLA (2) enzymatic activity averaged 29.8 +/- 5.1 pmol phosphatidylethanola mine (PE)/mg DNA/h LPS at a concentration of 1 mu g/ml increased immun oreactive type II PLA(2) tissue content by 180% of the control value ( p < 0.05, n = 7) within 1 h of exposure and remained significantly ele vated for 18 h when compared to controls (174% of control, p < 0.01, n = 7). This increase in type II PLA(2) tissue content was associated w ith a significant increase in PLA(2) enzymatic activity at both 1 h an d 18 h of incubation (140% of control, p < 0.02, n = 7 and 180% of con trol, P < 0.01, n = 7, respectively). These data establish type II PLA (2) as a locus of action of LPS in human choriodecidua and support an etiological role for LPS in the increased phospholipid metabolism and eicosanoid formation that occur in human gestational tissues at the ti me of bacterial infection-associated preterm labor.