Preterm birth (PTB) is the single largest cause of death in infants and young children. The prevalence of preterm birth is however, significantly higher in pregnancies carrying male babies. Inflammation has long been implicated as a key mediator in the onset of parturition. Therefore, we propose that in pregnancies carrying male babies, there is increased expression of pro-inflammatory cytokines in the decidua, and an increased cytokine response to infection, placing male babies at increased risk of preterm birth.
Term non-labouring choriodecidual explants were treated with lipopolysaccharide (LPS, 5μg/ml, O55:B5) for 24h and culture medium was collected for cytokine analysis (n=5/sex). Levels of Interleukin (IL)-1β, IL-6, and IL-10 as well as tumour necrosis factor (TNF) was measured via a BD Cytometric Bead Array (CBA) Human Inflammatory Cytokines Kit.
Baseline levels of TNF were significantly higher in ‘female’ choriodecidual explants (p=0.03) compared with ‘male’ explants whereas levels of IL-1β, IL-6 and IL-10 were not significantly different between ‘male’ and ‘female’ explants. Treatment with LPS significantly increased the secretion of pro-inflammatory cytokines: IL-1β, IL-6 and TNF but only from ‘male’ choriodecidual explants (p=0.0004, 0.0001 and 0.03 respectively). The anti-inflammatory cytokine IL-10 was not affected by treatment with LPS in ‘male’ or ‘female’ explants.
These data show that term non-labouring choriodecidua from ‘male’ pregnancies are more sensitive to induced inflammation by LPS when compared with ‘female’ choriodecidua. This suggests that ‘male’ decidua may have a higher inflammatory response to infection and, therefore, increased susceptibility to preterm labour.