Fatty Airways Could Contribute to Lung Disease in Obese Asthmatic Patients

By Reuters Staff

November 26, 2019

NEW YORK (Reuters Health) - Accumulation of adipose tissue within airway walls in obese individuals is linked to greater wall thickness and airway inflammation, according to a postmortem study.

Previous studies have tied obesity to abnormal respiratory function, particularly asthma, but the mechanism underlying this association has yet to be established.

Dr. John G. Elliott of Sir Charles Gairdner Hospital, in Nedlands, and the University of Western Australia, in Crawley, and colleagues examined transverse airway sections from postmortem lungs of 15 controls, 21 cases of nonfatal asthma, and 16 cases of fatal asthma to determine the relationship between adipose tissue within the airway wall and BMI.

They identified adipose tissue in the airways from all subject groups. This tissue was limited to the outer airway wall and was observed predominantly in large- to medium-sized airways.

The ratio of adipose tissue area to perimeter of the airway basement membrane (Pbm) directly correlated with BMI in all groups, the team reports in the European Respiratory Journal, online October 17.

Among controls and nonfatal asthma cases, adipose tissue area/Pbm and BMI also correlated positively with total airway wall thickness, but among fatal asthma cases, there was no relationship between total wall thickness and adipose tissue area/Pbm or BMI.

For a given BMI, there appeared to be no difference in the deposition of adipose tissue in the airways, and the relationship between adipose tissue area/Pbm and BMI appeared to be the same regardless of asthma severity.

In multiple linear regression analysis, when airway wall thickness was used as the dependent variable, BMI and asthma were the explanatory variables for airway adipose tissue in all airway size groups.

When BMI was replaced in the model with adipose tissue/Pbm, adipose tissue area/Pbm and asthma emerged as the explanatory variable for airway wall thickness in all airway sites groups.

Adipose tissue area/Pbm correlated with the densities of eosinophils and neutrophils in large airways from fatal asthma cases and with the density of neutrophils in small airways from control cases.

"These results support a new mechanism of increased airway wall thickness associated with increased BMI, which may contribute to excessive airway narrowing and exacerbate symptoms in patients with existing disease," the researchers conclude.

Dr. Elliot did not respond to a request for comments.

SOURCE: https://bit.ly/2ouD8ix

Eur Respir J 2019.

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