16/09/2026
What sets off labour when a baby is ready to be delivered has long been a mystery, but now it seems that the immune system pulls the trigger. The uterus appears to start contracting after immune cells transfer energy to its muscle cells via tiny tubes.
“By understanding all the steps along the road, we’re getting closer to identifying therapeutics for preventing preterm birth,” says Stephen Lye at Mount Sinai Hospital in Toronto, Canada.
Lye and his colleagues previously found that, towards the end of pregnancy, the human uterus releases signalling molecules called cytokines and chemokines into the bloodstream. These usher immune cells called monocytes from the blood into the uterus. The monocytes accumulate in the muscle tissue of the uterus and turn into other immune cells called macrophages.
In the latest study, the team investigated the role of these macrophages by incubating them with muscle cells from uterus biopsies collected from pregnant women undergoing Caesarean sections at full term. “Remarkably, we found that the macrophages made these little tube-like structures that attached to the muscle cells,” says Lye.
Even more remarkably, the researchers could see the macrophages sending mitochondria through these tiny tubes into the muscle cells. “In the images we took, you can see tons and tons of these mitochondria passing into the muscle cells,” says Lye.
Read more: https://www.newscientist.com/article/2588577-immune-cells-donate-their-mitochondria-to-womb-muscle-to-kick-start-birth/
Image: An illustration of a macrophage immune cell releasing proteins called cytokines, a process that may be involved in initiating childbirth
SCIENCE PHOTO LIBRARY/Getty Images
