Normally, a spiderweb-like “net” of cells swoops in to trap and kill infectious bacteria, but newborn babies don’t have this capability. Therefore, more infants die than adults from infection every year.
Christian Yost, a pediatrics professor at the U School of Medicine, said they discovered this in a recent U study, which in time might help them discover medication to fight off bacteria with a similar disease-fighting mechanism.
The study developed when Yost, who cares for babies in the Newborn Intensive Care Unit, noticed that newborns, especially ones born prematurely, have a more difficult time fighting off infection. When a study from researchers in Berlin announced that the nets were important to fighting infection, Yost and other researchers wondered whether newborns exhibited this process.
“We encounter some fungal infections but mostly bacterial in the newborn care unit,” said Yost, the lead researcher on the study. “E. coli and others can be pretty significant infections, and when they get in the blood, they can cause infants to become very sick and die.”
And for an unknown reason, babies less than a year old don’t have nets, which are a combination of proteins and enzymes, to fight bacterial infections.
“It’s like a fishing net that has these devices to kill bacteria,” Yost said. “DNA is a very sticky molecule. You can actually see how dense and complex this net is through microscopes.”
Researchers said infants have a deficiency in biochemical mechanisms for about a year, making their immune systems incapable of fighting certain bacteria with these nets.
About 15 premature babies out of 1,000 are infected with bacteria every year, compared to about five full-term infants. Premature babies are born anywhere between 23 to 30 weeks of term, a few weeks short of full-term.
Researchers believe that bacterial infection triggers a certain white blood cell to die, which then causes proteins to mix with nearby enzymes to form the disease-fighting net.
Yost said the research team used two types of microscopes to study blood cells and that the pathway that directs the white blood cells to form nets from DNA, proteins, and enzymes isn’t fully developed in infants.
“It turns out that the ability to make nets is also deficient in full-term babies,” said Guy Zimmerman, an internal medicine professor and director of the U’s human molecular biology and genetics program. “But the deficiency is more profound in premature babies.”
Sometime within the first year, most healthy babies develop the ability to form the nets.
Yost was funded through a five-year grant from the National Institutes of Health for about $100,000 a year and has entered the fourth year of funding. They are in the process of applying for additional funding, but in the meantime, are studying how and why infants don’t develop this capability until later.
“If we come to understand this pathway well enough, we could use a medication to help newborn infants begin to make these nets,” Yost said.
He warns that researchers are years away from discovering how newborns could fight infection in a similar way.