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Premature babies gain protective gut bacterium through breast-feeding, researchers find

By Doug Bennett

A novel beneficial bacterium found in breast-fed babies has been shown to protect newborn mice from a dangerous intestinal disease that also affects premature infants, University of Florida Health researchers have found.

The bacterium works by reducing inflammation that leads to necrotizing enterocolitis, which destroys intestinal tissue and kills 20 to 30 percent of premature infants who get the disease. Understanding the role of human breast milk and the bacterium’s protective effect is an important step in fighting the disease, the researchers said. Their findings were published Sept. 25 in the Journal of Clinical Investigation.

The researchers collected gut microorganisms from 40 premature infants, evenly divided between premature infants who received breast milk and those who received baby formula. The premature babies who got breast milk had substantially more of a strain of Propionibacterium, said Mansour Mohamadzadeh, Ph.D., a professor in the UF colleges of Medicine and Veterinary Medicine.

When the human gut microorganisms were transplanted into mouse models, the results in newborn mice were striking: The breast-fed infants’ microbes produced a protective effect, increasing the number of infection-fighting cells and sustaining the regulatory cells that limit chronic inflammatory disease. The microbes from formula-fed infants produced a much different reaction in mouse models — more inflammation along with fewer infection-fighting and regulatory cells.

Similar results were found when the Propionibacterium was tested against listeria, a disease-causing bacteria that disproportionately affects pregnant women, infants and the elderly. Listeriosis can result in miscarriage or newborn death.

The novel, infection-fighting strain of bacterium cultured by the researchers was named P. UF1. Taken together, the findings support the idea that human breast milk, along with its related bacteria such as P. UF1 and bacterial products, are crucial to controlling the inflammation that can lead to necrotizing enterocolitis, researchers said.

“We studied the immune responses and saw tremendous immune regulation in the mice whose mothers were given P. UF1,” Mohamadzadeh said.

Finding a way to prevent necrotizing enterocolitis is crucial because it is a leading cause of death among premature infants and is extremely difficult to treat after onset, said Josef Neu, M.D., a professor in the UF College of Medicine’s department of pediatrics and a co-author of the study. Harnessing the potential of a beneficial bacteria is one way to do that.

“As we begin to show that inflammatory responses resulting in devastating diseases such as necrotizing enterocolitis can be altered, that offers some real promise in terms of blunting inflammation before it starts,” Neu said.

Because the beneficial bacterium can be cultured, Neu and Mohamadzadeh said it may have the potential to someday be used as a probiotic supplement that could be given to pregnant women or premature infants along with human breast milk to bolster the baby’s immune system. Ultimately, the bacterium may be able to help shape a stable, healthy gut for premature infants by redirecting the inflammation that leads to necrotizing enterocolitis and perhaps similar diseases, Mohamadzadeh said. Further research and approval from the U.S. Food and Drug Administration will be needed before the bacterium can be studied in infants, Neu said.

Researchers from Loyola University Chicago and the Emory University School of Medicine collaborated on the project. The research was supported by grants from the National Institutes of Health and the Gatorade Trust.