Human breast milk, which provides essential nutrients and antibodies to newborns, also serves as a reservoir for bio-molecules that help clear infections, reduce inflammation, combat pain and heal wounds.
"Finding a reservoir of these inflammation-resolving molecules at bioactive levels was a big surprise for us," said co-corresponding author Charles Serhan from Brigham and Women's Hospital (BWH) in Boston, US.
Using a comprehensive profiling technique, the team was able to uncover a milieu of molecules known as specialised pro-resolving mediators (SPMs) in human breast milk and found that each of these molecules helped resolve inflammation and stimulate immune response in preclinical models.
The team uncovered a profiling signature consisting of 20 molecules with pro-resolving properties.
Certain SPMs have been detected in breast milk before, but this is the first time that such a wide variety of bioactive molecules have been uncovered, the researchers said.
The team also tested human milk samples from participants with mastitis, an infection of the breast tissue that causes pain and inflammation.
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They found that SPM levels were much lower in milk from mastitis and did not resolve inflammation and infection to the degree that breast milk from non-mastitis samples did.
The team also tested cow's milk and infant formula where they could not detect SPM levels.
"Our results suggest a role for SPM in modulating inflammation, infection and stimulating resolution during early immune development, and further reinforce the importance of human breast milk for infants," Serhan explained.
The study was published in the journal Mucosal Immunology.