How breast milk antibodies impact infant immunity

How breast milk antibodies impact infant immunity | Image Credit: © Panithan - © Panithan - stock.adobe.com.

Below is a transcript from an interview completed by our sister publication, Contemporary OB/GYN®.

Contemporary OB/GYN:

Hi, I'm Celeste Krewson with Contemporary OB/GYN and I'm here with Dr. Hand to discuss a recent study on the association between breast milk antibodies and infant immunity. Do you want to introduce yourself?

Timothy Hand, PhD:

Hi, I'm Tim Hand, I'm an associate professor here at the UPMC Children's Hospital in Pittsburgh, where we work on the immune response to colonization of the intestine with bacteria.

Contemporary OB/GYN:

So, how do breast milk antibodies impact infant immunity?

Hand:

Sure, so most of the work in my lab has been focused on preterm infants. And in our work, we've been discovering that antibodies actually have a very important function in promoting the maturation of the intestinal microbiome, these are the bacteria that live within your intestine and help you to digest your food amongst many other things. And so what is supposed to happen is that after delivery, the microbiome is supposed to mature towards, you know, what you would have, for lack of a better word, I would say, a state of better health, where you have more sort of anaerobic bacteria that help you to digest, in this case, the metabolites that are coming to you through breast milk and away from the torganisms that are sort of coming out of your environment that are all around you. And so, it seems like from our research, and from the research of many others, that antibodies, what they're really doing is tamping down the sort of more aggressive and inflammatory bacteria that are of your environment, and really supporting the growth of the more health supporting organisms that you really want in the infant intestine.

Contemporary OB/GYN:

So, why is it important to study this association?

Hand:

Sure, one of the reasons that we think it's most important is that if you are, especially for preterm infants, if the sort of a delay in the maturation of the microbiome has been associated with the development of this terrible disease called necrotizing enterocolitis. So, this is a disease where, you know, the microbiome is not held in check with the intestine, you can begin to invade the intestinal epithelium and induce a disease that can cause massive damage to the small intestine of an infant, in some cases requiring surgery that can actually in some very severe cases, lead to the death of the infant, and in other cases, can cause long term repercussions.

Contemporary OB/GYN:

Can you talk a bit about the results of the study, go a bit more into detail on them?

Hand:

Sure. So, because of the importance of these antibodies, we got really interested in testing the idea that the reactivity of antibodies might differ between donors, or mothers in this case, so you know, the idea being that not all antibodies are the same. So as you probably know, hopefully everyone got a COVID vaccine, right? When you get vaccinated against COVID, right, you're inducing antibodies that are specific to COVID, that will help you should you reencounter COVID, to fight it off, or maybe not be infected at all. But those antibodies won't help you if you're encountering flu, right, you need flu-specific antibodies. So, the same is true for the bacteria that are going to be in the intestine, or in this case, the bacteria that will be in the infant's intestine, that are going to be bound by the antibodies that are secreted into breast milk, right? So, we got interested in the idea that if there were differences in the antibacterial binding properties, or what we call the reactivity of antibodies that are present in breast milk, that might have an effect on the infant. So, we went to measure it. So, what we did was we built an array, essentially, we just put all different kinds of bacteria into a plate, and then isolated antibodies from breast milk, and then measure the ability of those antibodies to bind the different bacteria in the array. And by doing that we could do is really measure differences in the antibacterial activity between different donors. And, you know, it allowed us to look at this in a way that no one had ever done before.

Contemporary OB/GYN:

That's all really interesting. Were there any results of the study that surprised you?

Hand:

Sure. There were 2 results that, 1 result that didn't surprise, we should start with results that didn't surprise us at all right? So, the first result was that every different donor that we tested had completely distinct antibacterial reactivity, right? And this is not, the reason this is no surprises that I'm an immunologist, any immunologist will tell you that people live very long and diverse lives. You know, they're getting infected with different bacteria in their intestine they're gonna get infected with different things, the antibodies that are going to be present in breast milk are going to be very different between different people, right? It just has to do with life history. The thing that was fascinating to us is that these antibodies were incredibly stable over time within a donor, meaning that, you know, each donor has antibodies that were distinct to that donor, but they seem to keep the same antibodies over time. Right, so the antibodies that they had, that they were feeding their infant, in the first days of their infants’ lives, were the same antibodies at a month and the same antibodies again at almost 100 days. And then what really sort of surprised us the most was when we were able to look at samples between 2 different sequential infants, we even noticed similarities there. So, it seemed like the same antibodies were being put into breast milk over long periods of time.

Contemporary OB/GYN:

Thank you. We're just about ready to wrap up. Is there anything you want to add first?

Hand:

Yeah, sure, you know, and with all this stuff, you know, the work we do here can only be done with the support of grant support. In this case, the March of Dimes was incredibly helpful and steadfast in their support of this project. And they stood by us through some very sort of difficult times in the pandemic in being able to collect samples, and be able to do the work actually, like physically do the work in the lab. And I want to thank them for that. I also want to thank, you know, the donors, and the, you know, the Mid Atlantic Mother's Milk Bank here in Pittsburgh, as well as the Mother's Milk Bank in San Diego, that have been our partners and collaborators for all this work. Without them, you know, we couldn't have done any of this and we're just tremendously thankful for their support.