Effect of oxygen tension on bacteria-stimulated cytokine production by fetal membranes.

AIM: Tissue culture studies indicate that bacterial products stimulate the production of proinflammatory cytokines by reproductive tissues. However, most of these studies have been performed under room air conditions, supplemented with 5% CO₂. In this study, we tested whether O₂ tension affects bacteria-stimulated cytokine production by extra-placental fetal membranes.

METHODS

Cultures of full-thickness membranes, isolated choriodecidua, and isolated amnion were exposed to bacteria and incubated under 21% (room air) or 5% O₂ for 18 h. Cytokine concentrations in conditioned medium was quantified by immunoassay.

RESULTS

Culture under 5% O₂ increased production of interleukin (IL)-1β and tumor necrosis factor (TNF)-α, but reduced IL-10 and IL-6 production by full membranes. Isolated choriodecidua responded to 5% O₂ with increased IL-1β production and reduced IL-6 production, but had no effect on TNF-α and IL-10 production was not detected. No effect of O₂ tension on IL-1β or IL-6 production by isolated amnion was detected, however, Escherichia coli-stimulated IL-10, TNF-α and IL-8 production was enhanced by culture under 5% O₂.

CONCLUSIONS

Increased oxygen tension reduces the pro-inflammatory responsiveness of cell cultures to E. coli and promotes an anti-inflammatory cytokine profile. Differential effects of O₂ tension on choriodecidua and amnion suggests a network of paracrine factors that regulate cytokine levels in response to changes in O₂ tension.