Did you know that there are more microbes living inside you than there are stars in the Milky Way? The Museum’s upcoming exhibition The Secret World Inside You will look at this incredible diversity of life, known collectively as the human microbiome.
Before the exhibition opens, we’re offering weekly primers on the microbiome and the research surrounding it from Curators Rob DeSalle and Susan Perkins, as well as from other scientists who are working in this exciting field.
Our first post comes from microbiologist Dr. Martin Blaser. Dr. Blaser, who is the Muriel and George Singer Professor of Translational Medicine and a Professor of Microbiology at New York University, is also the author of Missing Microbes: How the Overuse of Antibiotics is Fueling Our Modern Plague.
Studying Microbes in Mice and Infants
In my lab at NYU, we’re asking fundamental questions about the microbes that call us home: for example, how do they get there in the first place? How do microbes acquired early in life help animals—including humans –develop normally?
We already know several important points that provide a starting place. For example, we know that the diversity of microbes and their numbers in each of us are enormous. We also know that the makeup of the microbiome in very young children is not the same as in adults, but that eventually they become the same. The big questions for us are how and why this occurs.
We’re learning about this change in humans by first studying it in mice. To do this, we expose some very young mice to antibiotics and examine how that exposure affects the microbes living in and on the mice, as well as how they develop compared to mice not exposed to antibiotics. In some experiments, we expose the mice to the same level of antibiotics that human children would be prescribed for ear or throat infections. This gives us an idea of the effects that those antibiotics might have on children.
Our findings show that antibiotics do indeed affect microbial populations in these mice, leading some species to thrive while others are suppressed. These altered compositions interact with the cells in the intestinal wall in ways that are different from normal, and can make mice develop abnormally in a variety of ways. Some become fatter; others demonstrate altered immune responses. While it’s important to remember that mice are not people, these experiments suggest something similar might be happening to some human children who receive antibiotics.
To learn more about that, we’re currently studying how microbial populations change in babies born here in New York. We’re following a group of more than 40 children from before birth (sampling their mothers) to above the age of two, using specimens that the moms give us about every month. These ongoing samples let us examine how several factors—birth by Caesarean section, antibiotic use, and a diet dominated by formula—may change the way a baby’s microbiome develops. This ongoing work allows us to make comparisons with the studies we have already done in mice and may help us draw new conclusions about the origins and role of the human microbiome.