Early exposure to antibiotics kills healthy bacteria in the digestive tract and can trigger asthma and allergies, new research suggests.
A study published in Mucosal immunologyprovided the most compelling evidence that the long-observed association between early childhood antibiotic exposure and the later development of asthma and allergy is causal.
“The practical implication is simple: Avoid antibiotic use in young children if possible because it can increase the risk of serious long-term problems with allergies and/or asthma,” said senior author Martin Blaser, director of the Center for Advanced Biotechnology. and Medicine at Rutgers.
In the study, scientists from Rutgers, New York and Zurich universities noted that antibiotics, “one of the most commonly used drugs in children, affect the gut microbiome and metabolic functions. These changes in the structure of the microbiota can affect the host’s immunity.”
In the first part of the experiment, five-day-old mice received water, azithromycin or amoxicillin. After the mice grew older, the researchers exposed them to a common allergen derived from house dust mites. Mice that received any of the antibiotics, especially azithromycin, showed increased rates of immune reactions – that is, allergies.
The second and third parts of the experiment tested the hypothesis that early exposure to antibiotics (but not later exposure) causes allergies and asthma by killing some of the healthy gut bacteria that support the proper development of the immune system.
For the first time, lead author Timothy Borbet transferred bacteria-rich stool samples from the first group of mice to a second group of adult mice without prior exposure to any bacteria or microbes. Some obtained samples from mice that were given azithromycin or amoxicillin during infancy. Others obtained normal samples from mice that received water.
Mice that received samples with altered antibiotics were no more likely to develop an immune response to house dust mites than other mice, just as humans who take antibiotics as adults are no more likely to develop asthma or allergies than in those who do not accept.
However, things were different for the next generation. The offspring of mice that received antibiotic-altered samples were more reactive to house dust mites than those whose parents received non-antibiotic-altered samples, just as mice that initially received antibiotics as infants were more reactive to the allergen than those that received water.
“It was a carefully controlled experiment,” Blazer said. “The only variable in the first part was exposure to antibiotics. The only variable in the second two parts was whether the antibiotics affected the mix of gut bacteria. Everything else in the mice was identical.
Blaser added that “these experiments provide strong evidence that antibiotics cause the development of adverse immune responses through their effects on gut bacteria, but only if the gut bacteria were altered in early childhood.”
Story source:
Materials is provided Rutgers University. The original was written by Andrew Smith. Note: Content can be edited for style and length.
