THE EFFECT OF INTERLEUKIN-1-BETA (IL-1-BETA) ON THE REGULATION OF IL-1 RECEPTOR-TYPE-I MESSENGER-RIBONUCLEIC-ACID AND PROTEIN-LEVELS IN CULTURED HUMAN ENDOMETRIAL STROMAL AND GLANDULAR CELLS

Because we hypothesize that the interleukin-1 (IL-1) system may be important in the dialogue between mother and embryo during the implantation process, we have analyzed the effect of IL-1 beta, a secretory product of the human embryo and human endometrium, on the mRNA and protein levels of IL-1 receptor type I (IL-1R tI) in the human endometrium. For this purpose, endometrial epithelial cells (EEC) and stromal cells (ESC) were isolated and cultured with progesterone (3.18 mu g/mL) and epidermal growth factor (20 ng/mL) for 8 days in the presence or absence of hrIL-1 beta (20 pg/mL). EEC from proliferative and secretory endometrium expressed high levels of IL-1R tI mRNA compared to ESC, and these levels were not modulated by IL-1 beta. However, prostaglandin E(2) levels peaked on day 4 in EEC treated with progesterone, epidermal growth factor, and IL-1 beta (208.7 +/- 92 ng/10(7) cells), whereas no prostaglandin E(2) was detectable in cells not treated with IL-1 beta, indicating that these cells responded to IL-1 beta. With regard to ESC from secretory endometrium, IL-1 beta increased its own receptor mRNA levels (4 +/- 0.5-fold increase) after 8 days in culture. However, when ESC were isolated from proliferative endometrium, an up-regulation of IL-1R tI (3.5 +/- 0.5-fold increase) was observed on days 6 and 8 of culture regardless of the presence or absence of IL-1 beta. Immunoreactive IL-1R tI was identified in cultured EEC and ESC, and patterns similar to those of mRNA were observed. The constitutive presence of IL-1R tI in EEC, which was not affected by IL-1 beta, and the up-regulation of IL-1R tI mRNA by its ligand IL-1 beta in ESC isolated during the luteal phase suggest a role for the IL-1 system in human implantation.