Airway Microbiome and Host Interact Differently in Children with Severe Asthma
The Mount Sinai study showed that airway microbes interact with inflammatory genes differently in healthy versus asthmatic children.
A collaboration between allergists, pulmonologists, and systems biologists at the Icahn School of Medicine at Mount Sinai has led to major new insights about how the microbiome interacts with the respiratory system in children with asthma. The study, published March 12 in JCI Insight, showed that the airway microbiome interacts with the host differently in children with severe asthma compared to healthy children. It also revealed differences between the microbiome of the upper and lower airways within individual asthmatic children.
“Asthma is affected by genetics and environment, including the microbiome. In trying to understand the dynamics of asthma, examining both together can give you very different insights compared to studying asthma from just one perspective,” said the study’s senior author, Dr. Supinda Bunyavanich, MD, MPH, Professor of Genetics and Genomic Sciences and Pediatrics and at the Icahn School of Medicine at Mount Sinai.
Many studies have attempted to understand the roles of genetics and the microbiome in patients with asthma, but not necessarily how the two interact with one another. Moreover, many studies focus only on the upper airways because of accessibility. In order to obtain samples from the lungs, patients must undergo bronchoscopies — invasive procedures requiring anesthesia.
The Bunyavanich Lab collaborated with Mount Sinai pulmonologists, who perform bronchoscopies as a part of their clinical care of some children with severe persistent asthma, to collect a series of samples from the upper and lower airways from 27 children with severe asthma. For comparison, the researchers also took two samples from the upper airways of 27 healthy children.
Dr. Bunyavanich’s team then used these samples not only to analyze the microbiomes of the upper and lower airways, but also the matching transcriptomes for these sites. Transcriptomics measures the collection of RNA molecules produced by genes, telling scientists about biologic functioning of the human body.
“The unique angle of our study was that we could study not only the presence of various microbiota, but also link these microbiota to what's happening to the person,” said Dr. Bunyavanich.
The group found that among the children with asthma, the upper and lower airways were each home to distinct microbiomes and transcriptomes.
But one of the more surprising findings, according to Dr. Bunyavanich, is that while the nasal passages of both healthy children and those with asthma contained overlapping microbes, some of those microbes seemed to be interacting differently with their hosts. “Similar genes and similar microbiota might be present in children with asthma and those who don't have asthma,” she said. “But an important difference is in how they associate with one another.”
A particular microbe, Corynebacterium, which was present in the nasal passages of both asthmatic and healthy children, seemed to be dampening inflammation more strongly in healthy children compared to children with asthma. The microbe may be playing a protective role in healthy children but doing so less effectively in those with asthma.
“Our study was an important first step to figuring out relationships between host and microbiota in the airways of children with asthma. The next step is to figure out the causal directions for these relationships,” said Dr. Bunyavanich.
About the Mount Sinai Health System
The Mount Sinai Health System is New York City's largest academic medical system, encompassing eight hospitals, a leading medical school, and a vast network of ambulatory practices throughout the greater New York region. Mount Sinai is a national and international source of unrivaled education, translational research and discovery, and collaborative clinical leadership ensuring that we deliver the highest quality care—from prevention to treatment of the most serious and complex human diseases. The Health System includes more than 7,200 physicians and features a robust and continually expanding network of multispecialty services, including more than 400 ambulatory practice locations throughout the five boroughs of New York City, Westchester, and Long Island. The Mount Sinai Hospital is ranked No. 14 on U.S. News & World Report's "Honor Roll" of the Top 20 Best Hospitals in the country and the Icahn School of Medicine as one of the Top 20 Best Medical Schools in country. Mount Sinai Health System hospitals are consistently ranked regionally by specialty and our physicians in the top 1% of all physicians nationally by U.S. News & World Report.