CELLULAR SPECIFICITY OF INTERLEUKIN-1-BETA-STIMULATED EXPRESSION OF TYPE-2 PROSTAGLANDIN-H SYNTHASE IN HUMAN AMNION CELL-CULTURES

Interleukin-1 beta (IL-1 beta) has been shown in numerous studies to i ncrease prostaglandin output by cultures of human amnion cells. This i s due to an increase in the expression of type-2 prostaglandin H synth ase (PGHS-2), the inducible form of the enzyme, in these cultures. Amn ion consists of an epithelial layer of cells and a subepithelial mesen chymal layer of cells. The purpose of the present study was to determi ne the cell-type(s) responsible for the IL-1 beta-induced PGHS-2 expre ssion in amnion cultures. Amnion was obtained at term after elective C esarean section or vaginal delivery. Tissues were dispersed with colla genase, and cells were plated in multichamber culture slides and cultu red for 7 days in media supplemented with 10% fetal bovine serum. Cell types were characterized with antisera to keratin (epithelial cells) and vimentin (mesenchymal cells). Cultures contained both cell types, and the proportion of these varied considerably from one culture to an other. Cells were treated with various concentrations of IL-1 beta for 6 or 24 h and were then fixed in 4% paraformaldehyde. The fixed cells were permeabilized with Triton and examined by immunohistochemistry f or PGHS-2 protein using specific antisera, and PGHS-2 mRNA was localiz ed by in situ hybridization using a specific oligonucleotide probe. Th e cell type(s) expressing PGHS-2 was characterized using double labeli ng with antisera to keratin (epithelial cell marker) and vimentin (mes enchymal cell marker). IL-1 beta was found to increase expression of i mmunoreactive PGHS-2 and PGHS-2 mRNA. This increased expression was fo und to occur only in the vimentin-positive cells and not the epithelia l cells. These results highlight the potential importance of the subep ithelial cells in the mesenchymal layer of amnion in the formation of prostaglandins during pregnancy and possibly in preterm labor with inf ection.