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Prostaglandins and cytokines are generated in gestational membranes and serve as important signaling messengers for the onset of preterm and term parturition. A tissue culture system using intact human gestational membranes mounted on TranswellMoreProstaglandins and cytokines are generated in gestational membranes and serve as important signaling messengers for the onset of preterm and term parturition. A tissue culture system using intact human gestational membranes mounted on Transwell frames was designed to investigate prostaglandin and cytokine responses to inflammatory stimuli. This system allowed measurement of secreted products from distinct chambers on the amnion or choriodecidual side of the membranes. Following optimization of the experimental model, secreted prostaglandins and cytokines were measured in culture medium from both sides of the gestational membranes after exposure to the model inflammatory stimulus lipopolysaccharide (LPS). Prostaglandin E2 (PGE2) was secreted from the amnion side, whereas prostaglandin F2alpha, (PGE2) was secreted from both sides of the gestational membranes. Side-specific differences in prostaglandin release for LPS-stimulated concentration-response, time-course, and prostaglandin species profiles indicated relative independence of the amnion and choriodecidua responses. Immunohistochemistry of the gestational membranes revealed stimulus-dependent expression of the rate-limiting enzyme in prostaglandin synthesis, prostaglandin endoperoxide H synthase-2, on only the side of the membranes treated with LPS. Distinct patterns of response were seen for individual cytokines. In particular, TNF-alpha, IL-1beta and IL-6 concentrations were significantly increased on both the amnion and choriodecidual side of the membranes after an 8-h LPS exposure. In contrast, IL-8 and IL-10 were increased only on the choriodecidual side of the membranes. The ex vivo side-specific cytokine responses to LPS are similar to the tissue specificity of previously reported cytokine production in vivo under term and preterm laboring conditions. To research potential effects of environmental toxicants on gestational membranes, prostaglandin and cytokine secretion was measured following 2,4,5,2,4,5-hexachlorinated biphenyl (PCB 153) exposure. After 1, 4 or 8 h of PCB treatment no effect on PGE2, PGF 2alpha or IL-6 secretion was detected from either side of the gestational membranes. Additionally, PCB 153 had no effect on LPS-stimulated inflammatory responses. In conclusion, the Transwell culture system provided distinct advantages as an experimental model for studying mechanisms of inflammation in human gestational membranes, allowing discrimination of side-specific responses. A model was proposed in which selective inflammatory signaling across the gestational membranes initiates responses that contribute to parturition onset.