Interleukin-8 Release from Human Gestational Tissue Explants: Effects of Gestation, Labor, and Chorioamnionitis1

Abstract

Interleukin-8 (IL-8) is a chemotactic cytokine that has been implicated in the process of human parturition, including the processes of cervical ripening and rupture of fetal membranes. In this study, the in vitro release of IL-8 from human amnion, choriodecidua, and placenta tissues obtained before and after spontaneous labor onset both at term and preterm, was assessed. The effect of chorioamnionitis on IL-8 release was also established. All tissue explants examined released IL-8; however, IL-8 release from choriodecidual explants was significantly (p < 0.02) greater than that observed from amnion and placenta. Furthermore, choriodecidual IL-8 release was significantly (p < 0.001) greater from term tissues (850 +/- 134.4 ng/mg DNA, n = 18) than from preterm tissues (458 +/- 68.8 ng/mg DNA, n = 17). Spontaneous onset of labor, irrespective of the eventual mode of delivery, was not associated with any significant changes in IL-8 release from human gestational tissues compared to not-in-labor tissues, both at term and preterm. IL-8 release from gestational tissues was not significantly different in the absence or presence of chorioamnionitis. These data are in contrast to the previously reported stimulatory effects of bacterial endotoxin on IL-8 release from human gestational tissues. The data are consistent, however, with the suggestion that IL-8 release is an early event in chorioamnionitis that precedes the appearance of clinically overt symptoms.

An introduction to Toll‐like receptors and their possible role in the initiation of labour

“…A similar proinflammatory process takes place in the fetal membranes—the production of IL‐8, TNF‐α, IL‐6 and IL‐1β increases in the membranes with preterm and term labour, 12–15 and this is associated with an increase in the production of prostaglandins and MMP, such as MMP8 (neutrophil collagenase) 16 . Sources of cytokines include infiltrating leucocytes, which occur at a greater density in the zone of altered morphology that overlies the cervix, 17 cells of the maternal decidua and fetal amniochorion, such as decidual stromal cells and amnion epithelial cells.…”

Changes of leukocyte counts and expression of pro‐ and anti‐inflammatory cytokines in peripheral leukocytes in periparturient dairy cows with retained fetal membranes

“…The expression of IL‐8, a chemoattractant associated with neutrophil migration, was decreased in PMNs, which might reflect the impaired migration of neutrophils to the uterus. Furthermore, IL‐8 is also known to initiate dilatation of the cervix (Laham, Brennecke, & Rice,) and increase collagenase secretion (Luo et al., ) which accelerates the separation of fetal cotyledon from maternal caruncle (Eiler & Hopkins, ). Therefore, decreased expression of IL‐8 gene is associated with the delayed placental separation in RFM cows.…”

Cytokines and the Initiation of Parturition

“…irIL-8 is present in amniotic fluid in the absence of infection and increases with labor [82,83]. Amniotic fluid concentrations are markedly increased in association with intra-amniotic infection [68,84].…”