PROBLEM: Infection-mediated preterm labor results in the production of infl
ammatory cytokines, including interleukin-1 beta (IL-1 beta) and interleuki
n-6 (IL-6). Oxytocin (OT) plays a key role in the process of labor. This st
udy investigates the effect of IL-1 beta and IL-6 on intra-and extracellula
r OT in human smooth muscle cells and evaluates IL-1 beta induced changes i
n IL-6 production.
METHOD OF STUDY: Primary cultures of human myometrium, obtained from term p
regnant women (n = 7) were incubated with either IL-1 beta or IL-6 for 0-24
hr. Intra- and extracellular OT peptide concentrations were measured by ra
dioimmunoassay and IL-6 mRNA and protein were evaluated by reverse transcri
ption polymerase chain reaction and enzyme-linked immunosorbent assay.
RESULTS: Both, IL-1 beta and IL-6 led to an increase in OT secretion, which
was accompanied by a reduction of the intracellular OT peptide pool. IL-1
beta significantly induced IL-6 mRNA expression and protein secretion, whic
h did not further enhance IL-1 beta induced OT secretion.
CONCLUSIONS: The induction of OT secretion by proinflammatory cytokines in
human myometrium in vitro, supports the concept of a thus regulated infecti
on-triggered preterm labor process in vivo.