Fat accumulates in airways, contributes to respiratory illness

People who experience overweight or obesity often struggle with respiratory problems, with previous research finding asthma more common and often harder to treat in this patient population.
 
Researchers have hypothesised whether this risk may relate to issues such as the increased pressure of carrying excess weight on the lungs.
 
Now new research offers another potential cause: the development of fatty tissue within airway walls. Not only did the researchers discover that fatty tissue builds up in airway walls, but also that the higher a person’s body mass index (BMI), the greater the amount of fat that accumulates.
 
The study’s co-author, Dr Peter Noble, said that experiencing overweight or obesity has already been linked to asthma or having worse asthma symptoms than in people with a healthy weight.
 
‘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 said.
 
‘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.’
 
To come to these conclusions, researchers analysed lung samples collected post-mortem from 52 lungs donated for research.
 
Of the samples, 15 had not had asthma, 21 had asthma but died of unrelated causes, and 16 died due to asthma-related causes.
 
The researchers studied the structure of 1373 airways for the presence and amount of fatty tissue, and looked at data regarding each donor’s BMI.
 
‘These data show that adipose tissue is present within the airway wall and is related to BMI, wall thickness and the number of inflammatory cells,’ the authors wrote.
 
‘The accumulation of airway adipose tissue in overweight individuals may therefore contribute to airway pathophysiology.’
 
According to the Australian Institute of Health and Welfare, 67% of adults were living with overweight or obesity in 2017–18.
 
The RACGP’s 2019 General Practice: Health of the Nation report asked GPs to rank the three top health policy issues on which they believe the Federal Government should focus. In response, 9% listed obesity as the highest priority, 12% listed it as the second-highest priority and a further 9% listed it in third position.

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