Regulation of sPLA2-IID in Human Decidua: Insights Into the Complexity of the Prostaglandin Pathway in Labor

Abstract

Prostaglandins are implicated in the labor process, yet the precise role and regulation of the prostaglandin pathway remains to be elucidated. The first step in the pathway is cleavage of membrane phospholipids by phospholipase A 2 (PLA 2 ). Previous work demonstrated upregulation of secretory PLA 2 (sPLA 2 )-IIA with labor in human myometrium, and recent evidence shows that there are numerous PLA 2 isoforms. The present study investigates the potential of additional sPLA 2 isoforms during pregnancy and labor. Real-time reverse transcriptase-polymerase chain reaction (RT-PCR), Western blotting, and immunohistochemistry were used to determine sPLA 2 expression and localization. Results show the presence of sPLA 2 -IID in amnion, chorion, placenta, decidua, and myometrium. Expression of sPLA 2 -IID in decidua was significantly decreased in term labor compared to nonlabor patients, whereas no significant labor-associated changes were observed in other gestational tissues. Secretory PLA 2 -IID was localized within chorion fibroblasts, placenta trophoblasts, decidual cells, and in myometrial smooth muscle cells. In primary decidual cell cultures, interleukin (IL) 10 (IL-10) increased sPLA 2 -IID messenger RNA (mRNA) expression, while IL-1b had no effect on sPLA 2 -IID mRNA expression. In conclusion, decreased expression of sPLA 2 -IID in the decidua at labor indicates that it is unlikely to contribute to increased prostaglandin production during labor. However, increased expression of sPLA 2 -IID, induced by IL-10, suggests that sPLA 2 -IID may play an important anti-inflammatory role at the maternal-fetal interface. Nevertheless, precise functions of sPLA 2 -IID within the human uterus remain to be determined.