The potential role of prolactin as a modulator of the secretion of proinflammatory mediators in chorioamniotic membranes in term human gestation.

To test the effect of prolactin (PRL) on expression of proinflammatory cytokines and matrix metallopeptidase 9 (MMP-9) in vitro. Tissue explants were incubated from 4 to 48 hours alone or in the presence of 500 ng/mL PRL, and mRNA expression in tissues and secretion of interleukin (IL)-1β, tumor necrosis factor alpha (TNF-α), MMP-2, and MMP-9 was quantified. Fetal membranes secreted IL-1β, TNF-α, and MMP-9 in culture with consistent low concentration during the first 24 hours and then increased progressively. The presence of PRL during explant incubation significantly decreased the patterns of IL-1β, TNF-α and MMP-9 secretion along culture (P < .001). MMP-2 secretion was unaffected by PRL. The relative basal expression of IL-1β mRNA (1.2 ± 0.87) was reduced by 80% in the presence of PRL after 32 hours of incubation of the membranes (P = .001). The expression of the TNF-α mRNA was not modified by the presence of PRL (0.06 ± 0.01) compared with the basal expression levels (0.05 ± 0.01). MMP-9 mRNA basal expression (0.018 ± 0.008) was significantly reduced (P = .001) in the presence of PRL after 32 hours (0.002 ± 0.0005). PRL may be a potential candidate as a key signal controlling the expression of signals related to the proinflammatory reaction associated with human labor.