When scientists from Australia were looking at lung samples from dead people, they found something they had not seen before. Lungs that belonged to obese and overweight people had more fat accumulation. And this was more pronounced in those who had asthma, leading scientists to suggest that fat accumulation in the lungs could be one reason why these people face an increased risk of asthma.
Previous studies have investigated whether asthma is more common among obese people and found that the prevalence of obesity was more in the asthma group than the non-asthma group.
In this study, the Australian scientists were more interested in studying how different the airway structure in the lungs looked in people with respiratory disease. And in that attempt, they found fat in these structures. "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," study author John Elliot, a senior research officer at Sir Charles Gairdner Hospital in Perth, Western Australia, said.
To do so, the researchers examined 52 people whose post-mortem lung samples were donated for research. Of the 52, 15 had no reported asthma, 21 had asthma but died of other causes, and 16 died of asthma.
The team visualized fat buildup using dyes and made notes after which they compared this data with each person's body mass index (BMI). They saw that the amount of fat present increased with an increase in BMI. This fat buildup, the researchers say, may be causing inflammation in the lungs, seen in asthma patients.
Explaining further, Dr Peter Noble, associate professor at the University of Western Australia and co-author of the study, said, "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."
In the future, the team will substantiate their findings by trying to study and measure fatty tissue in the lungs and confirm their relationship with respiratory disease. They are also interested in investigating whether fat accumulation can be reversed by weight loss therapy.
The study was published in the European Respiratory Journal.