Micrograph showing fat cells (fat) in lung tissue samples. Credits: European Respiratory Journal

We've known for a long time that fat accumulation in the arteries can increase the risk of developing heart problems, but researchers have now discovered that the same type of clogging can occur in the lungs, which could be linked to the development of asthma.It is known that overweight people have a higher risk of developing asthma, but to date, it has been thought that this link may be due to additional pressure on the lungs, or additional inflammation in the body. However, in a new study by researchers at the University of Western Australia, it has been shown that fatty deposits can also play a role.Using samples collected from a previous study, scientists examined lung tissue from 52 people who died: 15 without reported asthma, 21 with reported asthma but died for another cause, and 16 died because of asthma.With the help of dyes to highlight the structures of the airways, nearly 1400 samples were analyzed. What they discovered was surprising: fat had accumulated (fat cells) in the walls of the airways. The study was published in the European Respiratory Journal.In addition, the amount of adipose tissue correlated with the body mass index (BMI) of the individual. In other words, the higher the weight of the person, the more fat accumulated on the walls.We found that excess fat accumulates in the walls of the airways, where it takes up space and appears to increase inflammation in the lungs, " says physiologist Peter Noble , of the University of California. Western Australia. " We think this causes a thickening of the airways, which limits the flow of air into and out of the lungs and could, at least in part, explain an increase in asthma symptoms ."This is the first time that fatty deposits are found in the lungs, although it is already known that they can appear in other organs than the heart, including the liver.And while this does not preclude previous assumptions about the possibility that a larger weight makes asthma more likely, this could be another factor to consider. It seems that fat really modifies the structure of the airways and increases inflammation, which is well linked to the symptoms of asthma.The exact mechanism at the origin of the appearance of fat in the airways is unclear at the moment. To better understand it, it will be necessary to wait for the results of subsequent research. It will also be important to test more people (the current study sample is only 52 people).Another question is whether the effects could be reversed with possible weight loss. It will therefore be necessary to determine whether, with regular exercise and a healthy diet, the fat levels in the lungs decrease or not, as the body weight decreases." This is an important finding on the relationship between body weight and respiratory disease, as it shows how overweight or obesity could worsen the symptoms of people with asthma, " says Thierry Troosters , president of the European Respiratory Society, which did not participate in the study." It goes beyond the simple observation that obese patients need to breathe more with exercise. This study makes it possible to visualize the true modifications of the airways associated with obesity, "he adds.