Washington: A recent study found that fat accumulates in the airway walls within the lungs causing wheezing and asthma in overweight or obese people. Scientists already know that people who are overweight or obese are more likely to suffer from wheezing and asthma, but the reasons for this have not been completely explained.
The new study, published in the European Respiratory Journal, suggests that this fatty tissue alters the structure of people's airways and it could be one reason behind the increased risk of asthma. "Our research team studies the structure of the airways within our lungs and how these are altered in people with respiratory disease," said the study's author John Elliot, a senior research officer at Sir Charles Gairdner Hospital in Perth, 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," added Elliot. The researchers examined post-mortem samples of the lung that had been donated for research and stored in the Airway Tissue Biobank. They 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 visualise the structures of 1373 airways under a microscope, they identified and quantified any fatty tissue present. They compared this data with each person's body mass index (BMI).
For the first time, the study showed that fatty tissue accumulates in the walls of the airways. The analysis revealed that the amount of fat present increases in line with increasing BMI. The research 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. 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," said co-author, Dr. Peter Noble, an associate professor at the University of Western Australia in Perth.
"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, “Dr. Peter Noble added.
