Breast milk is known to be highly beneficial for newborns; it provides nutrients, good microbes, and antibodies, including those that are generated when women are vaccinated. It is worth noting, of course, that breast milk does not provide all nutrients, and not all mothers can breastfeed, making formula a feasible alternative. New research has shown that there is a specific set of antibodies that are produced by beneficial gut microbes, and those antibodies can be given to babies through breast milk. The antibodies seem to protect infants from diarrhea caused by infection, and infants may get improved protection from bacterial pathogens that cause infection and gastrointestinal illness. The findings have been reported in Science Immunology.
The antibodies identified in this study are called IgGs, and they can help eliminate pathogenic bacteria and viruses from the body. In this study, the researchers used a mouse model to see how mice were protected from a pathogen that is similar to infectious E. coli, called Citrobacter rodentium, which can cause gastrointestinal infections in rodents.
"We found that these IgG antibodies were protective against gut infection in the babies and that we could enhance this protection," said senior study author Dr. Melody Zeng, an assistant professor at Weill Cornell Medicine.
The researchers created a vaccine that could help protect the mice from the C. rodentium infections. The vaccine was generated from components of gut bacteria, and triggered the production of IgG antibodies that can move from breast milk into young mice. Female mice were given the vaccine before they got pregnant.
The IgG antibodies then stopped the pathogenic bacteria from attaching themselves to the intestinal walls of infant mice, which is one of the first steps in a gut infection. The IgG also interacted with other, beneficial gut microbes, which are an important part of a healthy microbiome.
Research has suggested that the microbiome is related to the development of the immune system in young children. Good microbes may help teach the immune system about what pathogens look like, for example.
In mice that never got protective IgG antibodies from their mothers, abnormal gut microbiomes developed, and their immune systems were impacted. The researchers determined that in these mice, there were more immune cells in the gut that generate an inflammatory cytokine called IL-17. When they grew to adulthood, these mice were more vulnerable to inflammation that mimics inflammatory bowel disorder.
Children under five are particularly at risk of gastrointestinal illness, which is a leading cause of death for that age group.
"Our findings really underscore the benefits of breastfeeding, both immediately and for the long-term development of the immune system in the offspring," Zeng noted.
