Fat Deposition in Lungs of Obese People May Up Asthma Risk

Fat accumulation in the walls of the lungs occurs in obese individuals. This can change the structure of the airways, thereby increasing the risk of asthma. However, this could be prevented by maintaining a healthy body weight.

Highlights:

Fatty tissue can deposit on the walls of the lungs in overweight and obese people
This alters the structure of the airways and increases the risk of respiratory disorders like asthma
Reducing body weight and maintaining a low body mass index (BMI) can prevent excess fat build up in the lungs and keep asthma at bay

Fatty tissue accumulation in the airway walls of the lungs, especially in overweight and obese individuals has been reported for the first time in a study conducted by a team of researchers in Australia.

Although it has been observed for a long time that respiratory disorders such as asthma are more prevalent in overweight and obese individuals, the exact reason was not known, until now. This new study indicates that fatty tissue deposition alters the structure of the airways of the lungs, thereby increasing the risk of asthma.

The study, published in the European Respiratory Journal, was led by John Elliot, who is a Senior Research Officer at the Sir Charles Gairdner Hospital in Perth, Western Australia. The senior author of the paper was Dr. Peter Noble, BSc, PhD, who is an Associate Professor and Director of Research at the School of Human Sciences, University of Western Australia in Perth, Western Australia.

Elliot notes: “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.”

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‘Fat accumulates in the lungs of obese people and alters the structure of the airways. This could significantly lead to an increased risk of developing respiratory problems such as asthma. Therefore, losing weight and maintaining a healthy body weight could be the cornerstone in the fight against asthma in obese and overweight individuals.’
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Salient Features of the Study

First study to show fat accumulation in the walls of the lungs and airways
Structure of the lungs and airways was studied to find any changes in patients with asthma
Correlation between fat accumulation in the airways and body mass index (BMI) was investigated
52 post-mortem lung tissue samples from the Airway Tissue Biobank were used in the study, which included the following:

15 samples were obtained from individuals who didn’t have asthma
21 samples were obtained from asthma patients who had died of other causes
16 samples were obtained from asthma patients who had died of asthma

Structures of 1,373 airways were studied by microscopy
Fat accumulation in the tissue samples was detected and quantified
Quantity of fat deposition was compared to the BMI of each individual
The amount of fat deposition increased with increasing BMI
Increased fat deposition altered the airways that led to inflammation in the lungs

Noble explains: “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.”

He adds: “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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Future Plans

The research team plans to develop new ways to detect and quantitate fatty tissue deposited in the lungs and confirm its link with respiratory diseases and whether the pathologic changes could be reversed by weight loss therapy.

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Concluding Remarks

Professor Thierry Troosters, President of the European Respiratory Society, who was not involved in the study, says: “This is an important finding on the relationship between body weight and respiratory disease because it shows how being overweight or obese might be making symptoms worse for people with asthma. This goes beyond the simple observation that patients with obesity need to breathe more with activity and exercise hence adding to their ventilatory burden. The observation points at true airway changes that are associated with obesity."

He concludes: “We need to investigate this finding in more detail and particularly whether this phenomenon can be reversed with weight loss. In the meantime, we should support asthma patients to help them achieve or maintain a healthy weight.”

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Funding Source

The study was funded by the Sir Charles Gairdner Hospital, the Osborne Park Health Care Group Research Advisory Committee, the Western Australian Department of Health, and the National Health and Medical Research Council of Australia.

Reference:

Fatty Airways: Implications for Obstructive Disease - (http://dx.doi.org/10.1183/13993003.00857-2019)

Source-Medindia