Selective immuno-modulatory effect of prolactin upon pro-inflammatory response in human fetal membranes

During pregnancy, prolactin (PRL) is a neuro-immuno-cytokine that contributes actively to the crosstalk between the immune and endocrine systems and, thus, to the creation of an immune-privileged milieu. This work aims to analyze the capacity of PRL to modulate the synthesis and secretion of pro-inflammatory markers associated with labor. Studies were conducted using human fetal membranes at term mounted in a model of two independent chambers. The choriodecidual region was stimulated with 500-ng/mL lipopolysaccharide (LPS), and the amnion and choriodecidual region were co-simulated with different concentrations of PRL that can arise during pregnancy: 250, 500, 1000, and 4000ng/mL. Following these co-treatments, the tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6, and IL-10 levels were measured in both compartments. As expected, treatment with LPS induced all cytokines to increase. Co-stimulation with the highest tested concentration of PRL induced significant decreases in TNF-α in the choriodecidual region and IL-1β in both regions of the fetal membranes. PRL did not modified the IL-6 and IL-10 secretion profile. These findings, coupled with clinical evidence, suggest that the high level of PRL in the amniotic cavity is involved the mechanism by which the fetal-placental unit regulates the equilibrium between pro- and anti-inflammatory modulators.