Preserved ex vivo inflammatory status in decidual cells from women with preterm labor and subclinical intrauterine infection

Abstract

Objective: To compare the inflammatory response preserved ex vivo by decidual cells isolated from women who experienced preterm labor with and without subclinical intrauterine infection.

Methods: Fetal membranes were obtained after cesarean section from 35 women who delivered before 37 weeks of gestation following spontaneous preterm labor, with no clinical evidence of intrauterine infection. Decidua was microbiologically tested and cultured. Concentrations of anti-inflammatory cytokines (IL-2, IL-4, IL-10), pro-inflammatory cytokines (IL-6, IL-8, IL-1β and TNF-α), and matrix metalloproteinases (MMP-1, MMP-2, MMP-3, MMP-7, MMP-8, MMP-9) were measured in the supernatants using Bio-Plex, and prostaglandin E(2) (PGE(2)) was measured by enzyme immunoassay.

Results: Subclinical infection was confirmed in 10 women (28.5%). Microorganisms isolated were Ureaplasma urealyticum (4), group B streptococci (3), Gardnerella vaginalis (1), and Escherichia coli (2). We found a significant increase of pro-inflammatory cytokines and a significant decrease of anti-inflammatory cytokines in supernatants from decidual cells obtained from women with preterm labor and subclinical intrauterine infection compared to women without infection. Secretion of MMP-1, MMP-8, MMP-9 and PGE(2) was significantly higher in infected women. Secretion of IL-8 by decidual cells from infected women persisted upon repeated in vitro culture passages.

Conclusions: Almost 30% of idiopathic preterm labor cases were associated with subclinical intrauterine infection, and decidual cells isolated from these cases preserved an ex vivo inflammatory status after in vivo bacterial exposure.

Figure 1. Neutrophil infiltration and extracellular matrix damage in amniochorion from a woman with subclinical intrauterine infection.

Representative immunohistochemistry of the fetal membranes from a woman with preterm labor and subclinical intrauterine infection. Open arrows show neutrophil infiltration, and filled arrows indicate damage to the extracellular matrix arrangement in amnion (A), chorion (C), and decidua (D). Light microscopy, hematoxilin stain.

Figure 2. Profiles of cytokines secreted by cultured decidual cells from women with and without subclinical intrauterine infection.

Concentrations of: a) anti-inflammatory cytokines, b) pro-inflammatory cytokines, and c) IL-8 in the supernatants of decidual cell cultures from women with preterm labor (PTL), with (n = 10) or without subclinical intrauterine infection (n = 25). Data in c) represent concentrations of IL-8 in the supernatants of progressive culture passages. Data are presented as mean ± SD; experiments were performed in duplicate. ***P<0.001, **P<0.005, *P<0.05 as compared to passage 1 for each group.

Figure 3. Profiles of matrix metalloproteinases secreted by cultured decidual cells from women with and without subclinical intrauterine infection.

Concentrations of matrix metalloproteinases in the supernatants of decidual cells from women with preterm labor (PTL), with (n = 10) or without subclinical intrauterine infection (n = 25). Data are presented as mean±SD; experiments were performed in duplicate. ***P<0.001, **P<0.005, *P<0.05 as compared to PTL without infection.

Figure 4. Prostaglandin E₂ secreted by cultured decidual cells from women with and without subclinical intrauterine infection.

Concentrations of prostaglandin E₂ in the supernatants of decidual cell cultures from women with preterm labor (PTL), with (n = 10) or without subclinical intrauterine infection (n = 25). Data are presented as mean±SD; experiments were performed in duplicate. ***P<0.001.