Parturition is an inflammatory process involving leukocyte infiltration of gestational tissues and cytokine release from the gestational membranes (GMs) (Young et al. 2002). It is proposed that the inflammatory response of post-labour GMs will differ from their naive pre-labour counterparts. This study examined the effect of labour on GM baseline cytokine release and potential secretory capacity (the difference between lipopolysaccharide (LPS)-stimulated and baseline profiles).
Placentas were obtained from women delivering at term after uncomplicated spontaneous vaginal delivery (n = 10) and clinically comparable women undergoing term elective caesarean sections (n = 10). Local ethical approval was obtained. Six mm GM discs were excised with a tissue punch, washed in Hank’s balanced salts solution (HBSS), and incubated in a 1:1 ratio of Dulbecco’s modified Eagle medium (DMEM) and Ham’s F12 nutrient mixture supplemented with 5 % fetal calf serum in the presence/absence of 10 µg/ml LPS under a humidified 5 % CO2 atmosphere at 37 °C. Serial supernatant samples collected at 0, 3 and 24 h were assayed for tumour necrosis factor (TNF)-α, interferon (IFN)-λ, interleukin (IL)-6, IL-8 and IL-10 levels by multiplex cytokine immunoassay. Cytokine profiles were expressed as pg/ml/mg wet tissue ( ± S.E.M.) and statistical analysis was performed by Mann-Whitney-U tests.
Baseline IL-6 and IL-10 release was significantly higher from post-labour membranes than their pre-labour counterparts at 3 h (1, 215 ± 86 vs. 287 ± 14 and 0.190 ± 0.027 vs. 0.001 ± 0.001 pg/ml/mg wet weight, respectively; P < 0.05), while baseline levels of IL-8 and IL-10 were higher at 24 h (2, 057 ± 254 vs. 1, 417 ± 223 and 0.683 ± 0.120 vs. 0.024 ± 0.001 pg/ml/mg wet weight, respectively; P < 0.05). IFN-λ release did not differ between both groups (23.38 ± 2.89 vs. 13.21 ± 4.87 pg/ml/mg wet weight at 24 h) Post-labour GMs also had a greater TNF-α secretory capacity at 3 h (161.81 ± 21.12 vs. 70.62 ± 12.83 pg/ml/mg wet weight; P < 0.01), while that of other cytokines was unaffected. Term labour enhanced GM baseline release of IL-6, IL-8 and IL-10, likely as a result of inflammatory priming. Furthermore, labour also enhanced pro-inflammatory TNF-α secretory capacity, probably as a result of leukocyte infiltration of the GMs. These responses differed from published data for isolated amnion and chorion, suggesting that there is significant paracrine interaction between these layers, and that a representative in vitro GM model cannot be inferred from data derived from isolated layers.
This work was supported by Cerebra..