Credit: Andrew Mann, Virginia Tech.
A healthy system of gut bacteria is essential to health: not only do gut bacteria aid in digestion, but they also play an important role in the body’s immune response. However, babies are not born with complete gut microbes, which makes it difficult for them to fight intestinal infections.
Although little is known about how the immune system developed during childhood, new research from the Department of Biomedical Sciences and Pathology at Virginia Maryland College of Veterinary Medicine sheds important new light on the topic.
A research team from principal investigator Xin Luo’s lab used rodent subjects to show a causal relationship between the production of newborn antibodies and maternal microbes. The team’s recent paper, “Regulation of Neonatal IgA Production by Maternal Microbiota”, was recently published in Proceedings of the National Academy of Sciences (PNAS), The official journal of the National Academy of Sciences.
Our study identifies maternal microorganisms – which are harmless bacteria that live in breast milk, for example – as a source for educating the infant’s antibody response. In particular, we have found that the most abundant antibody in the human body that protects us from infection, IgA, can be educated by a specific bacterium in breast milk, Lactobacillus reuteri, which is also a commonly used probiotic, ”said Lu, assistant professor of immunology in the department of science. Biomedical and Pathology.
Studies of IgA production typically focus on adults, without addressing the effects of the maternal microbiota on developing the immune response. Conversely, this study examined newborn mice nursing from dams with different microbiota and measured changes in IgA production in neonatal mice.
Using germ-free mice from the Veterinary College’s neotbiotic rodent facility, the researchers determined that L. reuteri is one of the neonatal bacteria that induce IgA in the mother’s microbiota. In contrast, elevating the production of IgA in the infant through L. reuteri might induce a stronger immune response to pathogens. Particularly due to the use of a strain of L. reuteri isolated from human breast milk for the study, the results have potential to be translated into human medicine.
“It will be interesting to see if human maternal microbes have similar mechanisms with mice in educating the neonatal immune response, especially mucosal immunity,” said first author Chingwei Mu (PhD 18), a postdoctoral fellow at Stanford University College at Stanford University. Medicine and former doctoral student in Lu Lab. “IgA A is vital for preventing intestinal pathogens, and IgA-inducing bacteria can be supplemented as a probiotic to prevent the infant’s intestinal infections.”
The next step is to determine the effects these newly produced antibodies have on the newborn’s immune response. Early disruption of microbes is associated with autoimmune diseases. It is not entirely clear whether the observed immune changes can influence the development of autoimmunity, but if we can identify the microbes that boost early defenses without triggering a self-reaction, we can use them to protect children from infection, ”said first author Brianna Swartoot, Ph.D. Candidate of the Graduate Program in Biology, Medicine and Health and a member of the Lu Lab.
Luo said the aim of the research is to better understand the benefits of microbes in order to recommend solutions, such as probiotics, that can strengthen the immune system of newborns. These efforts could lead to new strategies in medicine – and healthier children.