Induction of surfactant protein A expression by cortisol facilitates prostaglandin synthesis in human chorionic trophoblasts.

CONTEXT: Surfactant protein A (SP-A) may be an important link between the maturation of fetal organs and the initiation of parturition. However, the local expression of SP-A and the effect of SP-A on prostaglandin synthesis in human fetal membranes have not been resolved. OBJECTIVE: Our objective was to examine SP-A expression and the effect of SP-A on prostaglandin synthesis in human fetal membranes. DESIGN: SP-A expression was examined with immunohistochemistry and PCR. The effect of SP-A on prostaglandin synthesis was investigated in cultured human chorionic trophoblasts. PATIENTS: Patients were normal-term pregnant women undergoing elective cesarean sections. RESULTS: Both SP-A protein and mRNA were present in amnion epithelial cells, fibroblasts, and chorionic trophoblasts. Cortisol (10(-7) and 10(-6) M, 24 h) induced SP-A expression in cultured chorionic trophoblasts, which could be blocked by the glucocorticoid receptor antagonist RU486. Treatment of chorionic trophoblasts with SP-A (10-100 microg/ml, 24 h) caused a dose-dependent increase of prostaglandin E2 release and an induction of cyclooxygenase type 2 but not cytosolic phospholipase A2 and microsomal prostaglandin E synthase expression. CONCLUSIONS: SP-A can be synthesized locally in human fetal membranes, which can be induced by glucocorticoids. SP-A appeared to induce prostaglandin E2 synthesis in chorionic trophoblasts via induction of cyclooxygenase type 2 expression.

Expression and localization of adipophilin and perilipin in human fetal membranes: association with lipid bodies and enzymes involved in prostaglandin synthesis.

Lipid storage droplets (LSDs) are subcellular storage depots for triglycerides (TGs) and cholesterol esters surrounded by specific populations of proteins that are necessary for their formation. We have previously described the appearance of LSDs in human fetal membranes with advancing gestation and labor. Perilipin and adipophilin are functional/structural proteins located on the surfaces of intracellular LSDs. Adipophilin and perilipin were both immunolocalized to the amnion epithelium and amnion fibroblasts in human fetal membranes. Adipophilin was also localized to the choriodecidual layer, whereas perilipin was localized to the chorion trophoblasts. Although immunohistochemical data show an apparent increase in adipophilin, but not perilipin, expression in fetal membranes with advancing gestation and labor, Western analysis of tissue homogenate supernatant revealed no significant changes in adipophilin and perilipin expression. However, Western analysis of the floating lipid-rich layer from the tissue homogenate revealed an abundance of adipophilin and perilipin as well as other enzymes (cytosolic phospholipase A2, prostaglandin endoperoxide, and microsomal-associated prostaglandin E synthase-1) involved in prostaglandin synthesis. The association of these enzymatically active proteins with LSDs suggests that LSDs may be foci for signaling via the arachidonic acid cascade in fetal membranes. The structural and functional roles of adipophilin and perilipin in gestation and labor remain to be determined.

Differences in the proteome profile in placenta from normal term and preeclamptic preterm pregnancies.

The aim of this study was to use proteomic approaches to examine differences in protein expression in placentae from normal term and preterm preeclamptic pregnancies and to validate the data thus obtained by other independent methods. Using 2-DE we found that 80% of the proteins were present in both normal and preeclamptic placentae. However, 26 proteins in the normal term placentae were not matched in the preterm preeclamptic group. Six proteins showed increased intensity and one protein was down-regulated in preeclampsia. Four of the seven proteins that were altered in preeclampsia were further analyzed by Western blot and immunohistochemistry. Identification by MS techniques revealed these proteins to be involved in regulatory pathways activated by stress. This is significant because preeclampsia is a multisystem disorder in human pregnancies that results in considerable oxidative and nitrative stress. Three proteins identified by MS to be Hsp27, catalase, and glucose-regulated protein were confirmed by Western blot analysis to be significantly up-regulated in preeclampsia. Endothelial monocyte-activating polypeptide was shown to be down-regulated in preeclampsia by 2-DE and MS.

Regional expression of prostaglandin E2 and F2alpha receptors in human myometrium, amnion, and choriodecidua with advancing gestation and labor.

The change from uterine quiescence to enhanced contractile activity may be due to the differential expression of prostaglandin receptors within the myometrium and fetal membranes, in a temporal and topographically distinct manner. To address this question, we determined the localization and expression of the PGE2 receptor subtypes (PTGER1-4) and the PGF2alpha receptor (PTGFR) in paired upper and lower segment myometrium, amnion, and choriodecidual samples throughout human pregnancy, with and without labor. All receptor subtypes were found throughout the muscle layers in both the upper and lower uterine segments, colocalizing with alpha smooth muscle actin. A change in intracellular localization was observed at term labor, where PTGER1 and PTGER4 were predominately associated with the nucleus. Minimal changes in the expression of the PGE2 and PGF2alpha receptor subtypes were observed with gestational age, labor, or between the upper and lower myometrial segments. Receptor expression in maternal and fetal tissues differed between the receptor subtypes; PTGER1 and PTGER4 were predominately expressed in the fetal membranes, PTGER2 was greatest in the myometrium, whereas PTGER3 and PTGFR were similarly expressed in the myometrium and fetal membranes. Myometrial activation through the prostaglandin receptors is perhaps more subtle and may be mediated by a balance between one or several of the prostaglandin receptor subtypes together with other known contraction associated proteins. Lack of coordination in receptor expression between the myometrium and fetal membranes may indicate different regulatory mechanisms between these tissues, or it may suggest a function for these receptors in the amnion and choriodecidua that is independent of that seen in the myometrium.

Heat shock protein-70 and 4-hydroxy-2-nonenal adducts in human placental villous tissue of normotensive, preeclamptic and intrauterine growth restricted pregnancies.

OBJECTIVE: The purpose of this study was to compare immunohistochemical expression of heat shock protein-70 (hsp70), a marker for oxidative stress, and 4-hydroxy-2-nonenal adducts (HNE), a marker for lipid peroxidation, in placental villous tissue of normotensive, preeclampsia, and intrauterine growth restricted (IUGR) pregnancies. STUDY DESIGN: Placentas were collected and flash frozen in liquid nitrogen after delivery from normotensive pregnancies (n=5), and pregnancies complicated by preeclampsia (n=5), IUGR (n=5), and preeclampsia plus IUGR (n=4). Cryosections were cut and immunostained with polyclonal anti-hsp70 and monoclonal anti-HNE antibodies using Vectastain Elite ABC kit. Normal rabbit serum or mouse IgG were used as negative controls. Three independent observers, blinded to identity of tissue, examined each slide to identify cellular localization and intensity of the immunostaining. Western blot analysis and scanning densitometry were used to quantify and compare the amount of hsp70 and HNE adducts present in tissue homogenates. RESULTS: Positive immunostaining for both antibodies was observed in cytoplasm of syncytiotrophoblasts, extravillous trophoblasts, vascular smooth muscle, and endothelial cells for all groups. Expression of hsp70 and HNE adducts was reported as observers' mean stained intensity. Overall, kappa showed good agreement between observers. Immunostaining intensity was similar in all tissue types for each group with the exception that immunostaining was significantly more intense in the vascular endothelium of the preeclamptic group for HNE adducts (P=.02) and significantly less intense in the IUGR group for hsp70 (P=.013). Scanning densitometric analysis of the Western blots showed no significant difference in total hsp70 and HNE adducts expression in all 4 tissue groups. CONCLUSION: Immunohistochemistry showed local changes for oxidative stress and lipid peroxidation in the vascular endothelium from placentas of preeclamptic and IUGR pregnancies. However, these changes were masked when studying tissue homogenates.