The accumulation of airway adipose tissue in overweight individuals may contribute to excessive airway narrowing and exacerbate symptoms in patients with existing asthma, according to study results published in the European Respiratory Journal.1
Epidemiologic studies have demonstrated that individuals with asthma who are overweight or obese have more severe disease than individuals who are of a healthy weight, possibly due to a relationship between adipose tissue within the airway wall and body mass index (BMI).2-4
Therefore, researchers conducted the first quantitative estimation of adipose tissue within the airways of individuals with and without asthma by sampling transverse airway sections from postmortem lungs of 15 controls and 21 cases of nonfatal and 16 cases of fatal asthma.1 BMI ranged from 15 to 45 kg/m2 and was greater in patients with nonfatal asthma (P <.05). Adipose tissue was found in the outer wall of large airways but rarely in small airways.
The researchers found that adipose tissue area correlated positively with BMI and airway wall thickness in all groups. The airway adipose tissue area was consistently greater in men compared with women at any given BMI. In addition, the density of neutrophils correlated with adipose tissue area in controls and both neutrophils (r=0.85; P <.001) and eosinophils (r=0.74; P =.009) in patients with fatal asthma.
“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,”1 the researchers concluded. “The accumulation of airway adipose tissue in overweight individuals may therefore contribute to airway pathophysiology.”
1. Elliot JG, Donovan GM, Wang KCW, Green FHY, James AL, Noble PB. Fatty airways: implications for obstructive disease [published online October 17, 2019]. Eur Respir J. doi:10.1183/13993003.00857-2019
2. Beuther DA, Sutherland ER. Overweight, obesity, and incident asthma: a meta-analysis of prospective epidemiologic studies. Am J Respir Crit Care Med. 2007;175(7):661-666.
3. Farah CS, Salome CM. Asthma and obesity: A known association but unknown mechanism. Respirology. 2012;17:412.
4. Dixon AE, Poynter ME. Mechanisms of asthma in obesity: Pleiotropic aspects of obesity produce distinct asthma phenotypes. Am J Respir Cell Mol Biol. 2016;54(5):601.