An intrauterine injection of lipopolysaccharide (LPS) was administered to CD1 mice at embryonic day 16, ± CRTH2 agonist/vehicle controls. Mice were killed at 4.5 hr to assess fetal wellbeing and to harvest myometrium and pup brain for analysis of NF-κB, and T helper type 1/2 interleukins. To examine the effects of the CRTH2 agonist on LPS-induced preterm labour, mice were allowed to labour spontaneously. Direct effects of the CRTH2 agonist on uterine PD-1/PD-L1 targets contractility were examined ex vivo on contracting myometrial strips. The CRTH2 agonist increased fetal survival from 20 to 100% in LPS-treated mice,

and inhibited circular muscle contractility ex vivo. However, it augmented LPS-induced labour and significantly increased myometrial NF-κB, IL-1β, KC-GRO, interferon-γ and tumour necrosis factor-α. This suggests that the action of 15dPGJ2 is not via CRTH2 and therefore small molecule CRTH2 agonists are not likely to be beneficial for the prevention of inflammation-induced preterm labour. Preterm labour is one of the most challenging complications of human pregnancy. Its incidence in the western world remains between 6 and 15% depending on the geography and demographics of the population.[1] It

is a heterogeneous condition,[2] with the only firm causal link being that of infection.[3] Despite the increased awareness of the association between infection and inflammation and preterm labour,[4] there have been limited advances in the treatment and prevention of preterm labour. Currently, there is a drive to develop anti-inflammatory therapies to not only delay preterm labour, Sunitinib purchase but to prevent the long-term neurological damage thought to be a

result of the impact of pro-inflammatory factors on fetal inflammatory response syndrome. The transcription factor nuclear factor-κB (NF-κB), which is classically associated with inflammation, is central to regulating the biochemical pathways involved in both term labour and preterm labour.[5] The oxytocin receptor and cyclo-oxygenase-2 (COX-2) genes contain NF-κB response elements in their promoter regions.[6, 7] The oxytocin receptor mediates oxytocin-induced myometrial contractions through activation of phospholipase C and downstream calcium release from intracellular Niclosamide stores.[8] The COX-2 enzyme is the rate-limiting step for prostaglandin synthesis, which is responsible for uterine contractions and cervical dilatation. NF-κB is also involved in the transcriptional regulation of matrix metalloproteinases, including matrix metalloproteinase-9, which are required for remodelling of the extracellular matrix,[9] leading to cervical ripening and fetal membrane rupture. A positive feed-forward loop also exists from activation of NF-κB by the pro-inflammatory cytokines and subsequently their transcriptional activation, including tumour necrosis factor-α (TNF-α) and interleukin-1β (IL-1β).