Research Concerning The Relationship Between ICAM-1, PECAM-1 And Delivery Onset

ObjectiveDelivery is a complicate process mediated by many factors. There are many hypothesis about delivery onset including neuromediator hypothesis, machine hypothesis , hormonal control hypothesis, ripen of cervix and formation of lower uterine segment hypothesis and immunity hypothesis. Recently, accumulating evidences suggest that parturition in the human represents an inflammatory process involving a wide variety of mediators, in which leukocytes and cell adhesion molecules now are recognized to play a crucial role. In uterus, cervix and amni-otic tissues of women delivered by spontaneous labor, the concentrations of the mediums including interleukin - 6, interleukin - 8, and interleukin - 1 β increase greatly, which lead to high expression of cell adhesion molecules, then increase the activation and infiltration of leukocytes. The transfer and activation of immune cells is part of the initial mechanism that promotes ripening of the cervix, enhances uterine contractility, and then initiates parturition. Along with the development of studies, people pay more and more attention to the role of cell adhesion molecules in the initiation of parturition.Cell adhesion molecules, a kind of glucoproteins, are introduced by many kinds of cells. They recognize and combine with their special ligands and make important contribution in many pathological and physiological procedures. As members of immunoglobulin superfamily, intercellular adhesion molecule - 1 (ICAM - 1) and platelet - endothelial cell adhesion molecule - 1 ( PECAM -1) are important cell surface receptors. ICAM - 1 can be expressed by endothelial cells, epithelial cells, fibroblasts, activated T lymphocytes, neutrophile granulocytes and natural killer cells, especially blood vessel endothelial cellswhen stimulated by pro - inflammatory cytokines such as IL - 1 ,IFN -γ,TNF -α and so on. PEC AM -1 can be expressed by endovascular cells such as platelet , leukocytes include monocytes and neutrophiles. PECAM - 1 is predominantly produced by endothelial cells and localize in intercellular spaces. They all have significant roles in the course of leukocytes sticking and passing through the vessel endothelial cells to infiltrate the tissues.In this study, we examined the expression of ICAM - 1 and PECAM - 1 in fetal membranes obtained from pregnant women who delivered by caesarean section before the onset of labor and following spontaneous vaginal delivery. We also examined the expression of ICAM - 1 and PECAM - 1 in fetal membranes obtained from pregnant women who delivered by caesarean section before the onset of labor and following spontaneous vaginal delivery with premature rupture of membranes during pregnancy then analysed their relationships with delivery and their potential roles in this inflammatory process.Materials and methods1. Tissue sampleSamples of fetal membranes were obtained from pregnant women who delivered by caesarean section before the onset of labor (n = 20) , following spontaneous vaginal delivery ( n = 20) , delivered by caesarean section with premature rupture of membranes during pregnancy ( n = 20) and following spontaneous vaginal delivery with premature rupture of membranes during pregnancy (n = 20) in the Second Affiliated Hospital of China Medical University in 2004. The study population did not have any complications during pregnancy and their age ranged from 20 to 36 years, and gestational age ranged from 36 to 41 weeks. All samples were fixed in 10% buffered formalin for more than 24 hours.2. Paraffin sectionsAll samples were dehydrates by gradient alcohol, transparenced by dimethyl benzene, immerse in paraffin, and embedded in paraffin, then cut into 4μm sections.3. ImmunohistochemistryCell adhesion molecules were identified using primary antibodies directed a-gainst ICAM - 1 and PECAM - 1 by S - P method on samples of paraffin - embedded amnion and chorion obtained from 80 pregnant women after parturition.Statistics analysisSPSS 10.0 was employed for data analysis. Using independent - sampled T test and oneway ANOVA analysis to analyse data from tissue samples and P -value of less than 0.05 was considered statistically significant.Results1. In amnion, ICAM - 1 predominatly localized to amniotic epithelial cells, infiltrating leukocytes and fibroblasts. In chorion, ICAM - 1 localized to the vascular endothelial cells, trophoblasts and leukocytes.2. In amnion, PECAM - 1 predominatly localized to infiltrating leukocytes, but negative in amniotic epithelial cells. In chorion, PECAM - 1 localized to the vascular endothelial cells and leukocytes.3. In the group without premature rupture of membranes, the expression of ICAM - 1 in the tissues of following vaginal delivery after spontaneous labour was greater than that in the caesarean section population ( P < 0. 01). In the group with premature rupture of membranes, the expression of ICAM - 1 in the chorions of following vaginal delivery after spontaneous labour was greater than that in the caesarean section population ( P <0.05) , however, there was no significant difference between amnions of them (P >0.05). The group with premature rupture of membranes had more dramatical increase of the expression of ICAM - 1 than that without premature rupture of membranes ( P <0. 01).4. PECAM - 1 was expressed in the vascular endothelial cells in all samples , however, there was no significant difference( P <0.05).5. In the caesarean section group without premature rupture of membranes, the expressions of ICAM - 1 and PECAM -1 did not significantly differ among different gestational age cases. (P > 0.05).