The cyclopentenone 15-deoxy-delta 12,14-prostaglandin J(2) delays lipopolysaccharide-induced preterm delivery and reduces mortality in the newborn mouse

Intrauterine infection is a common trigger for preterm birth and is also a risk factor for the subsequent development of neurodevelopmental abnormalities in the neonate. Bacterial lipopolysaccharide (LPS) binds to toll-like receptor-4 (TLR-4) to activate proinflammatory signaling pathways, which are implicated in both preterm delivery and antenatal brain injury. The transcription factor nuclear factor-kappaB (NF-kappaB) is a key player in the orchestration of the inflammatory response and has a central role in parturition. Here we show that intrauterine administration of TLR-4-specific LPS to pregnant mice results in the activation of NF-kappaB in the maternal uterus and the fetal brain, up-regulation of proinflammatory proteins cyclooxygenase-2, chemokine ligand 1, ChemoKine (C-C motif) ligand 2, and cytosolic phospholipase A(2) in myometrium, and induction of preterm delivery. 15-Deoxy-Delta(12,14)-prostaglandin J(2) (15d-PGJ(2)) is an antiinflammatory prostaglandin that plays a role in promoting the resolution of inflammation. We report that coadministration of 15d-PGJ(2) and LPS to pregnant mice delays LPS-induced preterm delivery and confers protection from LPS-induced fetal mortality. This is associated with inhibition of myometrial NF-kappaB, cytosolic phospholipase A(2), and c-Jun N-terminal kinase activation, and of inflammatory protein synthesis. Therefore 15d-PGJ(2) has anti-inflammatory effects via inhibition of multiple aspects of inflammation-driven TRL-4 signaling pathway. Thus, 15d-PGJ(2) or compounds with similar antiinflammatory functions may have potential as therapeutic agents in the management of preterm labor with the added advantage of preventing detrimental effects to the fetus that may result from infection/inflammation.

Histone deacetylase inhibitors exert time-dependent effects on nuclear factor-kappaB but consistently suppress the expression of proinflammatory genes in human myometrial cells

Premature activation of the inflammatory processes that mediate human parturition leads to preterm birth, a major clinical problem associated with neonatal morbidity and mortality. Histone deacetylase inhibitors (HDACi) are currently in clinical trials for the treatment of inflammatory disorders. Recent evidence suggests that there may be a therapeutic use for HDACi in the management of preterm birth, with administration of HDACi to pregnant mice shown to delay delivery. Because NF-kappaB is a key orchestrator of the inflammatory response and plays a pivotal role in parturition, it is important to understand how administration of HDACi might affect NF-kappaB activity in human uterine tissues. We show here that the effects of HDACi on nuclear factor-kappaB (NF-kappaB) in human myometrial cells are time-dependent. Short-term exposure to HDACi enhanced interleukin (IL)-1beta-induced NF-kappaB activity as a result of potentiating IkappaB kinase (IKK)beta activity, thereby leading to persistent turnover of IkappaBalpha/epsilon proteins and prolonging NF-kappaB phosphorylation, nuclear localization, and DNA binding. Conversely, long-term HDACi treatments resulted in repression of NF-kappaB DNA binding. Nevertheless, both short- and long-term HDACi treatments inhibited the expression of four labor-associated proinflammatory genes (COX-2, IL-8, IL-6, and RANTES), and this was associated with repression of the proinflammatory transcription factor c-Jun. Together, our data indicate that HDACi exert anti-inflammatory effects in human myometrium and may thus be useful in achieving a myometrial gene expression profile that favors uterine quiescence. However, coadministration of an IKKbeta inhibitor may be both necessary and sufficient to circumvent potential induction of labor-associated pathways that could result from HDACi-induced augmentation of NF-kappaB activity.

The role of nuclear factor kappa B in human labour

Preterm birth remains the leading cause of perinatal mortality and morbidity, largely as a result of a poor understanding of the precise mechanisms controlling labour onset in humans. Inflammation has long been recognised as a key feature of both preterm and term labour, with an influx of inflammatory cells into the uterus and elevated levels of pro-inflammatory cytokines observed during parturition. Nuclear factor kappa B (NF-κB) is a transcription factor family classically associated with inflammation. Accumulating evidence points to a role for NF-κB in the physiology and pathophysiology of labour. NF-κB activity increases with labour onset and is central to multiple prolabour pathways. Premature or aberrant activation of NF-κB may thus contribute to preterm labour. The current understanding of NF-κB in the context of human labour is discussed here.

15-Deoxy-{delta}12,14-prostaglandin j2 inhibits interleukin-1{beta}-induced nuclear factor-{kappa}b in human amnion and myometrial cells: mechanisms and implications

Proinflammatory cytokines and prostaglandins play key roles in term and preterm human labor. The expression of the prostaglandin synthetic enzyme cyclooxygenase (COX)-2 and cytokines IL-1beta and IL-8 increases within the uterus at the time of labor, and each is regulated by the transcription factor nuclear factor-kappaB (NF-kappaB). In addition to its role in driving inflammation, COX-2 may also synthesize 15-deoxy-Delta (12, 14)-prostaglandin J(2) (15d-PGJ(2)), an antiinflammatory cyclopentenone prostaglandin (cyPG), which acts in some cells as an agonist of peroxisome proliferator-activated receptors (PPARs). We found that PPARalpha and -gamma proteins are expressed in both amnion epithelial and myometrial cells, but synthetic PPAR agonists could not inhibit NF-kappaB activity or COX-2 expression. 15d-PGJ(2) inhibited NF-kappaB activity and COX-2 expression in both cell types. This was unaffected by a PPAR antagonist and could be mimicked by the cyPG PGA(1) but not 9,10-dihydro-15d-PGJ(2) in which the cyclopentenone ring is disrupted. This shows that, in amnion and myometrium, inhibition of NF-kappaB activity and COX-2 expression by 15d-PGJ(2) is independent of PPARs and requires the cyclopentenone ring. We further show that 15d-PGJ(2) acts at multiple levels in the NF-kappaB pathway: blocking inhibitor of kappaBalpha degradation by repressing inhibitor of kappaB kinase activation and the 26S proteasome and also repressing NF-kappaB DNA binding and phosphorylation. Our data suggest that PPARs are unlikely to play a role in the regulation of either NF-kappaB or COX-2 in human amnion and myometrium. Targeting of NF-kappaB is a potential therapeutic strategy in preterm labor. PPAR agonists are unlikely to be effective in this context, but cyPGs may have potential.