Interleukin 8 expression in human myometrium: changes in relation to labor onset and with gestational age.

PROBLEM: Preterm labor remains the major cause of perinatal mortality and morbidity in normally formed babies. The mechanisms involved in the onset of preterm labor are poorly understood, mainly because the mechanisms initiating term labor remain ill-defined.

METHOD OF STUDY: Human myometrial samples were collected at cesarean delivery from preterm (26-36 weeks gestation) and term (37-41 weeks) women. Women at term were either non-laboring or laboring. The expressions of interleukin-8 (IL-8) mRNA and protein were measured by reverse transcriptase-polymerase chain reaction and enzyme-linked immunosorbent assay, respectively.

RESULTS

The expression of both IL-8 mRNA and protein significantly increased in the term laboring group, compared with either the term non-laboring or preterm groups. Levels of IL-8 expression did not alter with advancing gestational age.

CONCLUSIONS

The increased expression of IL-8 in laboring myometria at term supports the hypothesis that up-regulation of IL-8 has a role in the initiation of labor in association with an influx of neutrophils and the release of their collagenolytic enzymes into uterine tissues.