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Adiposity linked to HIV–associated asthma

An asthma phenotype correlated with adiposity and adipose-associated inflammation in HIV–infected patients with obstructive lung disease, according to recent research.

“Airflow obstruction, which encompasses several phenotypes, is common among HIV–infected individuals. Obesity and adipose-related inflammation are associated with both chronic obstructive pulmonary disease (fixed airflow obstruction) and asthma (reversible airflow obstruction) in HIV–uninfected persons, but the relationship to airway inflammation and airflow obstruction in HIV–infected persons is unknown,” Julia H. Barton, fellow in the department of medicine at the University of Pittsburgh, and colleagues wrote.

Barton and colleagues performed a cross-sectional analysis to determine the association between adiposity and airway obstructive phenotypes, such as asthma and COPD, in patients with HIV. A total of 121 HIV–infected individuals were enrolled.

Pulmonary function testing was conducted, as well as CT imaging of the chest to measure airway wall thickness, or wall area percent (WA%). Mediastinal and subcutaneous adipose tissue volumes and markers of inflammation for HIV and adipose were calculated and identified.

The researchers classified the patients into two categories: those with the COPD phenotype defined as post-bronchodilator FEV1/FVC less than the lower limit of normal and those with the asthma phenotype defined as asthma diagnosed by a doctor or bronchodilator response.

They used Pearson correlation coefficients to find the relationship between WA% and pulmonary function. The researchers used multivariable logistic regression to ascertain if participant characteristics, adipose measures and inflammatory markers were associated with COPD phenotype or asthma phenotype of the airflow obstruction. They used linear regression to identify the relationship between airflow obstruction phenotype and WA%.

Nineteen percent (n = 23) of participants had the COPD phenotype, and 27% (n = 33) had the asthma phenotype.

Patients with and without the COPD phenotype had similar BMI scores (mean [SD] 27 kg/m2 [7.9] vs. 27.8 kg/m2 [6.1]). However, those with asthma had higher BMI scores than those without (mean [SD] 30.7 kg/m2 [8.1] vs. 26.5 kg/m2 [5.3], P = 0.008).

Overall, WA% was associated with higher BMI (r = 0.55, P < 0.001), subcutaneous adipose tissue volume (r = 0.40; P < 0.001) and mediastinal adipose tissue volume (r = 0.25; P = 0.005).

Additionally, data indicated that greater age and a heavier smoking history was associated with the COPD phenotype, while younger age, female gender and lower adiponectin levels were associated with the asthma phenotype.

“There are different features associated with the COPD phenotype versus the asthma phenotype of obstructive lung disease in HIV–infected persons,” Barton and colleagues concluded. “These differences point out that there is likely not a single mechanism of airway obstruction in HIV, and a better understanding of the airway disease phenotypes and their pathogenesis is needed to optimize treatment of airflow obstruction in HIV.” – by Alaina Tedesco

Disclosure: The researchers report funding from the NIH and the University of Pittsburgh.