The lung microbiome plays a significant role on asthma severity and patients’ response to treatment, according to researchers at the University of Illinois at Chicago (UIC) College of Medicine.
The study reporting their findings, “Atopic asthmatic immune phenotypes associated with airway microbiota and airway obstruction,” was published in the journal PLOS One.
The impact of the lungs’ microbiome (the community of microbes present in the lungs) on lung disease has largely been ignored by the research community. Dr. Patricia Finn, the study’s senior author and the Earl M. Bane Professor of Medicine at the university, saw this as something that needed to be investigated.
“The microbiome is the ecosystem of good and bad bacteria living in the body,” Finn said in a press release. “Because the lungs continuously and automatically draw air, and any number of environmental agents, into the body, the composition and balance of microbes in the lungs may have a profound effect on many respiratory conditions,” she said.
The lung microbiome makes up a complex variety of microbes found in the respiratory system and on the mucus layer of the lungs. These microbes include bacteria, fungi, viruses, and bacteriophages, and some are known to cause respiratory disorders under particular conditions, like Streptococcus pneumoniae.
To study the impact of the lung microbiome in asthma, Finn and her team analyzed asthma patients with clinically similar profiles. All patients had mild-to-moderate atopic asthma and were ages 18 to 30.
By assessing the patients’ microbiome and airway inflammation, the team identified asthma phenotypes one and two — AP1 and AP2. When the team compared the two groups, they found that patients performed differently on pulmonary function tests.
AP1 was linked to normal pulmonary function tests, less severe asthma, decreased levels of pro-inflammatory cytokines (molecules that promote inflammation), and increased enterococcus bacteria. And AP2 was associated with decreased pulmonary function tests, more severe asthma, increased levels of pro-inflammatory cytokines, and increased levels of Streptococcus pneumoniae bacteria.
In both phenotypes, the associations between the lung microbiome and specific inflammatory cytokines were decreased after treatment with an inhaled corticosteroid asthma therapy.
“This tells us the microbiome has relevance beyond the gut, and that it is a potential biomarker for asthma,” said David Perkins, a professor at UIC who jointly operates the research team with Finn.
In a different study, Finn and Perkins showed that even before birth, exposure to specific bacteria could trigger inflammatory immune responses that could predispose individuals to asthma.
“The data suggest that further study of the microbiome may help to develop more personalized treatment recommendations for patients with asthma,” Finn said.
“If we can better understand how the individual’s lung microbiome affects asthma and identify likely microbial culprits, we may get to a point where we can predict and control asthma development and severity by shifting the microbiome early in life. This could be as simple as diet, probiotics or medication,” she concluded.