beta-endorphin inhibits the production of interleukin-8 by human chorio-decidual cells in culture

Interleukin-8 (IL-8) is produced by human decidual cells in culture, and ma y play a role in the initiation of parturition. beta-endorphin is released in significant amounts into the maternal and fetal circulation during labou r. The effect of beta-endorphin on IL-8 production by human chorio-decidual cells in culture was investigated. Mixed cells were obtained from the deci dual surfaces of 35 term placentas. The cells were plated out at 10x10(6) c ells per well in Roswell Park Memorial Institute 1640 culture medium. After 48 h the cells were washed and incubated with either plain culture medium (control), 1 mu mol/l progesterone, 1-100 nmol/l beta-endorphin or 1 nmol/l N-acetyl beta-endorphin. After 48 h, IL-8 concentrations were measured in the supernatants by enzyme-linked immunosorbent assay (ELISA). Experiments were repeated in the presence of naloxone (1 mu mol/l) and using calcium-de ficient culture medium. Progesterone (P < 0.0002) and beta-endorphin (P < 0 .0005) significantly inhibited the production of IL-8. The inhibitory effec t of beta-endorphin was blocked by naloxone and by using calcium-deficient medium. N-acetyl beta-endorphin had no significant effect on IL-8 productio n. These findings suggest that beta-endorphin has an inhibitory effect on I L-8 production by decidual cells, and that the effect is mediated via opioi d receptors and is calcium-dependent.