Interesting new research on the relationship between the maternal microbiome and the immune system in infants was just published by in the Proceedings of the National Academy of Science[i]. Using a mouse model, scientists from the Virginia-Maryland College of Veterinary Medicine found that the particular probiotic bacterium Lactobacillus reuteri is largely responsible for raising the level of IgA antibodies in pups.
Gut bacteria can translocate to the mammary gland via the lymph system and blood. Using a germ-free mouse model, the researchers found that “…Enrichment of certain maternal microbiota–derived bacterial taxa leads to early enhanced IgA production in the intestines, or what we refer to as IgA superinduction. In particular, L.reuteri was identified as a specific microbe derived from the maternal microbiota that colonizes the neonatal gastrointestinal tract to induce IgA.” It’s likely other bacteria do the same, but more research is needed to determine this.
IgA is produced mostly in the gut and is found at high levels there. It’s the most prevalent type of antibody in humans and is largely responsible for protecting us from enteric (gut) pathogens; supplementing with it may protect infants from infection. Because babies are born with only an innate immune system (the adaptive one – the one with memory, that involves antibodies to particular pathogens – develops over time), it’s important that they receive good immunity from their moms: “Infants are prone to enteric infections due to an underdeveloped immune system. The maternal microbiota, through shaping the neonatal microbiota, helps establish a strong immune system in infants.” One member of the research team states, “It’s not completely clear whether the observed immunological changes could affect autoimmune development, but if we can identify microbes that enhance early defenses without setting off self-reactivity, then we could potentially use them to protect infants from infections…”[ii]
Considering that L.reuteri seems to be pretty important as a potential probiotic for those with a wide variety of issues including autism, PTSD, and autoimmune diseases (look here and here, for just a couple of examples of posts on the topic), it may be highly significant that it plays such a critical role in the early formation of the immune system. In fact, you should really take the time to check out this post on the role L. reuteri may play in teaching the body immune tolerance (i.e. how to distinguish self from non-self, and pathogen from not-pathogen). I have to believe this is somehow all related.
In fact, in one of those coincidences that I love so much, as I was writing this post, I saw an article on using probiotics to increase intestinal diversity in preterm babies.[iii] These babies often suffer from life-threatening inflammation of the gut called necrotizing enterocolitis (NEC), which leads to the death of parts of the intestine – and often the death of the baby. Prior research had shown that L. reuteri can reduce the risk of NEC in moderately preterm babies, and now, researchers in Sweden found that it can do the same in extremely preterm infants, born between 23 and 28 weeks of pregnancy. They tested this in 132 babies, none of whom weighed more than a kilogram (about 2 pounds), and found that those who received the probiotic (as opposed to the placebo) were less likely to be infected by pathogenic bacteria like Klebsiella an Staphyloccus, which can lead to NEC. At this point, the evidence is strong enough that probiotics are now fairly routinely given to preterm infants. L. reuteri just seems like a pretty good idea for moms and their new babies.