Research shows a causal relationship between neonatal antibody production and maternal microbiota

A healthy system of gut bacteria, or microbiota, is essential for health: Gut bacteria not only help with digestion, but also play an important role in the body’s immune response. Babies, however, are not born with a fully concentrated gut microbiota, which makes it difficult for them to fight off intestinal diseases.

Although we have little information about how the immune system develops during childhood, new research from the Department of Biomedical Sciences and Pathobiology of the Virginia-Maryland College of Medicine sheds new light on the subject.

A research team from Xin Luo’s main laboratory used rodent subjects to reveal a causal relationship between newborn antibody production and maternal microbiota. The team’s paper, “Control of Neonatal IgA Production by the Maternal Microbiota,” was recently published Proceedings of the National Academy of Sciences (PNAS), the official journal of the National Academy of Sciences.

Our study identifies maternal microbiota – harmless bacteria that live in breast milk, for example – as an educational source for the baby ‘s antibody response. In particular, we have found that the most abundant antibody in the human body that protects us from disease, IgA, can be educated by a special bacterium in mama’s milk, Lactobacillus reuteri, which is also a probiotic commonly used. “

Xin Luo, Associate Professor of Psychology, Department of Biomedical Sciences and Pathobiology

Studies of IgA production typically focus on adult subjects, without addressing the effects of maternal microbiota on the development of the immune response. On the other hand, this study examined the nursing of newborn mice from dams with different microbiotas and measured the changes in neonatal IgA production of newborn mice.

Using organism-free mice from the college’s veterinary gnotobiotic rodent, the researchers concluded that L. reuteri is one of the bacteria that causes neonatal IgA in the mother’s microbiota. At the same time, if IgA production could induce infants through L. reuteri there may be a stronger immune response to pathogens. Specifically since a strain of L. reuteri isolated from human breast milk was used for the study, the findings have the potential to translate into human medicine.

“It will be interesting to see if mice have similar mechanisms of human maternal microbiota in educating neonatal immune response, especially mucosal immunity,” said first author Qinghui Mu (Ph.D. ’18), a westerner graduate of Stanford University School of Medicine and former doctoral student in Luo laboratory. “IgA is essential for the prevention of enteric pathogens, and inducible IgA bacteria may be added as probiotics to prevent infant enteric infections.”

The next step is to determine the effect of these new antibodies on the neonatal immune response. “Early disturbance of microbiota is linked to autoimmune diseases. It is not entirely clear whether the observed immunological changes may affect the development of autoimmunity, but whether we can identify microbes that contribute to early immunity without deactivating self-reactivity, we could use them to protect babies from disease, ”said first author Brianna Swartwout, Ph.D. candidate in biology, medicine and health translation graduate program and member of Luo laboratory.

The aim of the research, Luo said, is to better understand the benefits of microbes to suggest solutions, such as probiotics, that could strengthen the newborn’s immune system. These efforts could lead to new strategies in treatment – and healthier children.