Evidence for Interleukin‐10‐Mediated Inhibition of Cyclo‐ oxygenase‐2 Expression and Prostaglandin Production in Preterm Human Placenta

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Abstract
Problem  Interleukin‐10 (IL‐10) is thought to be a key cytokine for the maintenance of pregnancy. Here we examined the expression profiles of IL‐10 and cyclo‐oxygenase‐2 (COX‐2), and the effect of IL‐10 on COX‐2 expression and prostaglandin release in the human placenta from preterm labor deliveries associated with chorioamnionitis.Method of study  Placental tissues from preterm labor and term labor deliveries were processed for ex vivo placental explant culture system. IL‐10 expression was assessed by enzyme‐linked immunosorbent assay (ELISA) and immunohistochemical (IHC) analysis. COX‐2 expression was evaluated by IHC, Western blotting and reverse transcriptase‐polymerase chain reaction. Prostaglandin E2 (PGE2) release was measured by ELISA.Results  IL‐10 was significantly reduced in chorioamnionitis‐associated preterm labor as well as in term labor placental tissues compared with second trimester normal pregnancy samples obtained from elective terminations. Similar results were obtained with freshly isolated cytotrophoblasts from these deliveries. As expected, COX‐2 mRNA was detected at significant levels in tissues from term and preterm labor deliveries compared with no labor term deliveries. Importantly, IL‐10 inhibited COX‐2 expression in cultured placental explants from preterm labor deliveries, but not from term labor samples. Inhibition of COX‐2 expression coincided with reduced PGE2 release.Conclusion  These results demonstrate the importance of IL‐10 in countering inflammation associated with preterm labor, and suggest that term and preterm parturition may, in part, represent different conditions.