Obesity and asthma

Abstract

Obesity is a vast public health problem and both a major risk factor and disease modifier for asthma in children and adults. Obese subjects have increased asthma risk, and obese asthmatic patients have more symptoms, more frequent and severe exacerbations, reduced response to several asthma medications, and decreased quality of life. Obese asthma is a complex syndrome, including different phenotypes of disease that are just beginning to be understood. We examine the epidemiology and characteristics of this syndrome in children and adults, as well as the changes in lung function seen in each age group. We then discuss the better recognized factors and mechanisms involved in disease pathogenesis, focusing particularly on diet and nutrients, the microbiome, inflammatory and metabolic dysregulation, and the genetics/genomics of obese asthma. Finally, we describe current evidence on the effect of weight loss and mention some important future directions for research in the field.

Obesity and severe asthma

“…Weight loss, whether by diet and exercise or by surgical intervention, improves lung function, asthma control, and asthma-related quality of life (see (141) for review). For example, Pakhale et al (142) studied 22 massively obese asthmatics assigned to either a diet or control group for 3 months.…”

Understanding Asthma Phenotypes, Endotypes, and Mechanisms of Disease

“…The prototypical patient with obesity-associated asthma is the non-atopic, middle-aged woman with severe symptoms despite a moderately preserved lung function. While the obese-asthma syndrome is complex and multifaceted, the bulk of evidence points toward non-eosinophilic inflammatory mechanisms at the molecular level [71]. Interestingly, obesity biases CD4 cells toward Th1 differentiation, which is associated with steroid refractory asthma [72].…”

“…Additional innate immune responses involving Th17 pathways and ILCs have also been implicated. Uniquely, it is the type 3 ILCs (ILC3) that express both IL-17 and IL-22 that have been associated with obesity-related asthma [71]. …”

Infant growth and childhood respiratory health: how long is the road to preventive measures?

“…Several possible biological mechanisms have been suggested and the consistency of the association with the temporal and dose-response link have been replicated in a wide variety of settings, including different age groups, cultural, ethnic, socioeconomic and geographic backgrounds. Nowadays, it is largely recognised that obesity is implicated in asthma development,1 but the road to the identification of environmental and behavioural modifiable risk factors and quantification of health benefits related to obesity prevention is still steep and long.…”

“…It was reasonable to assume that biologically plausible mechanisms proposed for childhood and adulthood obesity1 could be extended also to the effect of fetal and infant weight on lung development and its later function. These include inflammatory and immune responses, obesity-related reductions in pulmonary compliance and limitations in airflow, and, more recently, disrupted microbiota 1…”