Obesity and Asthma: A Missing Link

Abstract

Obesity and asthma are two chronic conditions that affect millions of people. Genetic and lifestyle factors such as diet, physical activity, and early exposure to micro-organisms are important factors that may contribute to the escalating prevalence of both conditions. The prevalence of asthma is higher in obese individuals. Recently, two major phenotypes of asthma with obesity have been described: one phenotype of early-onset asthma that is aggravated by obesity, and a second phenotype of later-onset asthma that predominantly affects women. Systemic inflammation and mechanical effect, both due to the expansion of the adipose tissue, have been proposed as the main reasons for the association between obesity and asthma. However, the mechanisms involved are not yet fully understood. Moreover, it has also been suggested that insulin resistance syndrome can have a role in the association between these conditions. The intestinal microbiota is an important factor in the development of the immune system, and can be considered a link between obesity and asthma. In the obese state, higher lipopolysaccharide (LPS) serum levels as a consequence of a microbiota dysbiosis have been found. In addition, changes in microbiota composition result in a modification of carbohydrate fermentation capacity, therefore modifying short chain fatty acid (SCFA) levels. The main objective of this review is to summarize the principal findings that link obesity and asthma.

Lung ventilation impairment in asthma patients with obesity

“…The research results show that oxygen consumption in obese patients at rest is 25 % higher than in patients with normal body weight. Metabolism in overweight individuals requires higher lung ventilation both for oxygen supply to tissues and carbon dioxide elimination [11]. In our study, oxygen consumption in obese patients was not as high as in the sources mentioned.…”

“…In our study, a more pronounced bronchial obstruction was in obese asthmatics with FEV 1 67.8 ± 2.1 % compared to those without obesity 74.9 ± 2.4 %, P < 0.05 that can be explained by a higher degree of bronchial hyperreactivity in BA-obesity phenotype [10]. The literature indicates that even obese non-asthma tics may have a significant airway obstruction due to small airway collapse when lung volume is reduced [11].…”

Immunologic and Non-Immunologic Mechanisms Leading to Airway Remodeling in Asthma

“…Obesity is another unexplainable risk factor for asthma, which is especially important during childhood, with reduced physical activity [140]. Obesity as a risk factor for asthma has consequences for therapy and patients should be treated cautiously with steroids, which are known to increase accumulation of body fat [141].…”

Obesity and Asthma: Key Clinical Questions

“…When dealing with complex and heterogeneous diseases such as asthma and obesity, our traditional reductionist approach should give way to other strategies that, based upon systems biology, provide us with wider perspectives [31,32]. In fact, Gómez-Llorente et al [33] review the pathophysiological mechanisms shared by obesity and asthma and suggest that the relationship between both conditions would also imply other systemic inflammatory syndromes, insulin resistance, and alterations in microbiota. The authors propose that both asthma and obesity participate in a more complex syndrome and represent part of the total phenotype of this syndrome.…”