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Could Human Breast Milk Balance Your Gut Microbiome?

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Many individuals suffer with diseases related to imbalances in their gut microbiome, such as Crohn’s disease and inflammatory bowel disease (IBD). However, introducing new, helpful bacteria to create a healthy balance can be difficult without antibiotics – which remove all bacteria and can allow unhealthy shifts to take place – as the gut microbiome is somewhat resistant to colonization.

When infants are weaned off human breast milk, a bacteria known to have positive influences on the gut microbiome disappears. But what if we were able to reintroduce this bacterium in adults with an imbalanced gut microbiome (gut dysbiosis), without the use of antibiotics? A recent study published in Cell Host & Microbe suggests this might be possible.

Technology Networks had the pleasure of talking to Gregory J. McKenzie, PhD, vice president of product innovation at Prolacta Bioscience and study author, to learn more about the impact of antibiotics, introducing new bacteria into the microbiome and the potential of human breast milk-based therapeutics.

Kate Robinson (KR): Can you briefly explain how a disequilibrium of the gut microbiome can cause disease?

Gregory J. McKenzie (GJM): There are well-documented connections between the microbes that reside in our gut and various disease states, including infectious, metabolic, inflammatory and neurological diseases. Our gut microbes have a somewhat predictable influence on newly arriving microbes, whether they are disease-causing or not, and a well-balanced gut microbiome is typically fairly resistant to colonization by these new species. We no longer consider our microbes to be passive commensal organisms. They influence our bodies and our health in many important ways.

KR: How is the gut microbiome affected by antibiotics?

GJM: Although antibiotics are a life-saving therapeutic in many situations, their use is a brute force method of knocking down bacterial populations without distinguishing the good from the bad. Once the overall number of microbes in the gut has decreased, the gut can be repopulated with any number of new species. If beneficial species become re-established, a healthy state can be recovered; but there is also opportunity for unhealthy shifts in the community.

KR: What inspired you to study human breast milk-based therapeutics?

GJM: Prolacta Bioscience produces human milk-based products to feed critically ill, preterm infants, and we became enamored with a component that has no nutritional value to the baby – HMO (human milk oligosaccharides). HMO doesn’t feed baby; it exists entirely to feed the microbes that live within baby’s gut. We know that HMO plays a huge role in the colonization of the baby’s microbiome and predicted that it might be able to shape the microbiome in adults as well.

The newborn gut microbiome is fascinating in that it is essentially established from scratch, taking babies through this tremendously vulnerable developmental period and most of the time establishing the microbiome into a healthy community of organisms. Because human milk is a natural food source that encourages the growth of particular bacteria that play a key role in this critical process, we are interested in replicating and taking advantage of these complex interactions to restore damaged microbiomes in adults.

For this reason, we refer to our synbiotic of Bifidobacterium infantis (B. infantis) and HMO as Nature’s Microbiome Starter Kit™.

KR: What is the role of B. infantis in the microbiome?

GJM: B. infantis is more specifically a subspecies of Bifidobacterium longum, and although other bifidobacteria species are known to have positive influences on the gut microbiome, B. infantis itself preferentially utilizes the sugars in human milk. It has an intriguing role because it is specific to the newborn gut community and disappears once a baby is weaned off human milk, meaning that during its fleeting presence, it encourages a collection of other healthful microbes to become established.

Beyond influencing microbial communities, there is evidence that B. infantis plays an important role in several other aspects of infant development, including maturation of the intestinal tract itself and appropriate maturation of immune system responses. This was a clue that temporary, directed treatment with a synbiotic of B. infantis and HMO could be an effective therapy that shifts microbiome communities in the right direction.

KR: Can you give an overview of the results of the current study?

GJM: An important finding of our study was that we could introduce B. infantis into healthy adult microbiomes without first “making space” by killing off existing microbes with antibiotics. We introduced B. infantis specifically by including HMO as the unique food source for this species and were able to show that as long as HMO was continuously provided, B. infantis joined the community, or “engrafted,” at tremendously high levels. And then, similar to when infants are weaned from human milk, after the HMO was removed from the diet of the adults, B. infantis disappeared, meaning that none of the therapeutic microbe was left behind. This level of control of the engraftment (and de-engraftment!) of a target microbe in a healthy adult has not been demonstrated previously.

We were able to recapitulate these results in a mouse model and establish B. infantis in both infant and imbalanced human microbiomes, in addition to healthy adult microbiomes. And finally, we presented evidence that B. infantis itself can feed other beneficial members of the microbiome, leading to them producing butyrate – a molecule made in healthy microbiomes that both trains the immune system and improves gut barrier function.

KR: Do you envision this research improving therapeutics for diseases such as Crohn’s disease?

GJM: This therapeutic has potential for many diseases that are influenced by an imbalance in the microbiome, which means that it’s possible it could have a role in the treatment of Crohn’s disease, but we don’t have an answer to that yet. The imbalanced microbiomes we tested in the current study were from adults who had a bone marrow transplant (hematopoietic cell transplant or HCT) as treatment for blood cancer. We know that during this procedure, patients have damaged microbiomes that can lead to infection or graft-vs-host disease (GvHD). Our results in mice that had been colonized with these perturbed adult microbiomes provide evidence that the presence of B. infantis positively influenced the microbial community in a way that has great potential to shift the unbalanced communities back to a more healthy, functioning state. This positive result encourages us to pursue this as a therapeutic for allo-HCT patients, and eventually more broadly in other patients with damaged microbiome.

Dr. Gregory J. McKenzie was speaking to Kate Robinson, Editorial Assistant for Technology Networks.