One of the serious complications that can occur during late pregnancy happens when the amniotic sac (also called the bag of waters) breaks too early, which can allow bacterial infections to cause dangerous tissue inflammation around the placenta.

This condition, called chorioamnionitis, occurs in about 4% of pregnancies that reach full term. But it’s even more common in preterm deliveries, where it happens in 25-40% of preterm deliveries.

Infant deaths from chorioamnionitis are rare, but aggressive use of antibiotics to prevent infections is common in suspected cases. Unfortunately, those antibiotic treatments also can interfere with the formation of tiny vital air sacs called alveoli and disrupt formation of the lungs’ immune defenses. As a result, newborns treated for chorioamnionitis face higher risks of developing bronchopulmonary dysplasia (BPD). As survivors grow, they also face higher risks of developing asthma and struggling with other lung infections later in life.  

Now, experts may have discovered a way to prevent lung damage linked to chorioamnionitis. The researchers report, based on animal models, that the combined use of two drugs known to block cell signals that trigger inflammation in other conditions also blocked inflammation damage related to chorioamnionitis.

Details were published in Science Translational Medicine.

“Our finding that IL1 and TNF blockade protects the lung from injury…provides proof of principle that anti-inflammatory therapies could be used in the future to treat infants. These data support the idea that future therapies targeting the immune system may hold promise for treatment of multiple kinds of perinatal inflammation,” the co-authors state.

The drugs used in the study were anakinra, a potent IL1 receptor antagonist used to treat arthritis, and adalimumab, an anti-TNF monoclonal antibody used to treat ulcerative colitis. But these drugs may not be the medications that ultimately prove best for human therapy. More study is needed, co-authors say.

“This finding has significant relevance as a roadmap for new therapies for chorioamnionitis to protect the lungs of infants and hopefully prevent BPD or other neonatal lung disease,” the senior author says. “These data are unique in that little is understood about the lung in the third trimester of pregnancy in humans, so beyond the therapy implications we define important biology about lung development that is directly relevant to human infants."

The team broke new ground just by detailing the molecular activities involved in developmental lung injury and chorioamnionitis. That work including building an “atlas” of the processes involved in developing lung tissue at a cell-by-cell level, all the way down to gene expression patterns and complex molecular signaling. The work then went on to evaluate potential ways to mitigate the lung damage. Going forward, more studies are needed to confirm that the anti-inflammatory approach can work in people, which medications would be safest, and at what points during pregnancy they would be most effective, the senior author says.

https://www.science.org/doi/10.1126/scitranslmed.abl8574