According to a new study published in the European Respiratory Journal, fatty tissue accumulates within the airway walls of people who are overweight or obese; it also alters the structure of airways and could be the reason behind the increased risk of asthma.
Elliot et al show that fatty tissue is present within the airway wall and is related to BMI, wall thickness and the number of inflammatory cells. The accumulation of airway fatty tissue in overweight individuals may therefore contribute to airway pathophysiology. Image credit: Kalhh.
“We study the structure of the airways within our lungs and how these are altered in people with respiratory disease,” said study’s senior author John Elliot, a researcher at Sir Charles Gairdner Hospital and the University of Western Australia.
“Looking at samples of lung, we spotted fatty tissue that had built up in the airway walls.”
“We wanted to see if this accumulation was correlated with body weight.”
Elliot and colleagues examined samples of lung that had been donated for research and stored in the Airway Tissue Biobank.
The scientists studied samples from 52 people, including 15 who had no reported asthma, 21 who had asthma but died of other causes and 16 who died of asthma.
Using dyes to help visualize the structures of 1,373 airways under a microscope, they identified and quantified any fatty tissue present.
They then compared the data with each person’s body mass index (BMI).
The study showed that fatty tissue accumulates in the walls of the airways and that the amount of fat present increases in line with increasing BMI.
It also suggests that this increase in fat alters the normal structure of the airways and leads to inflammation in the lungs.
“Being overweight or obese has already been linked to having asthma or having worse asthma symptoms,” said co-author Dr. Peter Noble, from the University of Western Australia.
“Researchers have suggested that the link might be explained by the direct pressure of excess weight on the lungs or by a general increase in inflammation created by excess weight.”
“This study suggests that another mechanism is also at play. We’ve found that excess fat accumulates in the airway walls where it takes up space and seems to increase inflammation within the lungs. We think this is causing a thickening of the airways that limits the flow of air in and out of the lungs, and that could at least partly explain an increase in asthma symptoms.”
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John G. Elliot et al. Fatty Airways: Implications for Obstructive Disease. European Respiratory Journal, published online October 16, 2019; doi: 10.1183/13993003.00857-2019
