ORLANDO, Fla. — The increasing reliance on antibiotics in pregnancy and early childhood is influencing long-term physiology through microbiotic changes, altering key “conversations” with stem cell populations and guiding early cellular development of adipocytes, immunocytes, muscle and bone, according to a speaker here.
“The microbiome in early life is a critical determinant of normal human metabolic and immunological development,” Martin J. Blaser, MD, director of the human microbiome program and professor of microbiology at the NYU School of Medicine told Endocrine Today. “We have been substantially impacting the early life microbiota through such practices as the extensive use of antibiotics and C-sections. Work in animal models show that antibiotic impacts that change the microbiome have effects on host tissues, which affect disease outcomes, including obesity and type 1 diabetes.”
Diseases like obesity have grown rapidly in recent decades, Blaser noted: In 1989, there was no state in the U.S. where more than 14% of adults were obese. By 2010, there was no state where less than 20% of adults had obesity.
“This is happening everywhere, and the distance between the first map and the last map is only 21 years,” Blaser said, speaking during the presidential plenary session at ENDO 2017. “This is also happening all over the world. So, where might this be coming from?”
Over generations, changes in the ancient relationships between microbes and their human hosts have likely played a key role in diseases seen today, Blaser said. Humans begin life in a sterile womb, and babies historically have been exposed to microbes as they descend the birth canal of the mother and through their mother’s breast milk, forming the foundation of the GI tract.
“But now, moms are not the same as they used to be,” Blaser said. “They live in an environment with antisepsis. They’ve taken antibiotics, often during pregnancy, before the intergenerational transfer. They have a diet with antibacterial substances. And babies aren’t the same either. They may be born by Caesarean section and miss that passage through the birth canal. Babies are bathed extensively, they have formula that only superficially resembles breast milk, and, of course, they get a lot of antibiotics.”
Based on these ideas, Blaser said, he has proposed what he calls the “disappearing microbiota hypothesis.”
“This hypothesis has two major tenets,” Blaser said. “First, the changed human ecology has altered the transmission and maintenance of our ancestral microbes, and this affects the composition of the microbiota. Second, especially important are microbes usually acquired in life, since they affect a developmentally critical stage.”