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.

There is a major epidemic of obesity, and many obese patients suffer with respiratory symptoms and disease. The overall impact of obesity on lung function is multifactorial, related to mechanical and inflammatory aspects of obesity. Areas covered: Obesity causes substantial changes to the mechanics of the lungs and chest wall, and these mechanical changes cause asthma and asthma-like symptoms such as dyspnea, wheeze, and airway hyperresponsiveness. Excess adiposity is also associated with increased production of inflammatory cytokines and immune cells that may also lead to disease. This article reviews the literature addressing the relationship between obesity and lung function, and studies addressing how the mechanical and inflammatory effects of obesity might lead to changes in lung mechanics and pulmonary function in obese adults and children. Expert commentary: Obesity has significant effects on respiratory function, which contribute significantly to the burden of respiratory disease. These mechanical effects are not readily quantified with conventional pulmonary function testing and measurement of body mass index. Changes in mediators produced by adipose tissue likely also contribute to altered lung function, though as of yet this is poorly understood.

The 2020 Focused Updates to the Asthma Management Guidelines: A Report from the National Asthma Education and Prevention Program Coordinating Committee Expert Panel Working Group was coordinated and supported by the National Heart, Lung, and Blood Institute (NHLBI) of the National Institutes of Health. It is designed to improve patient care and support informed decision making about asthma management in the clinical setting. This update addresses six priority topic areas as determined by the state of the science at the time of a needs assessment, and input from multiple stakeholders: Fractional Exhaled Nitric Oxide Testing Indoor Allergen Mitigation Intermittent Inhaled Corticosteroids Long-Acting Muscarinic Antagonists Immunotherapy in the Treatment of Allergic Asthma Bronchial Thermoplasty A rigorous process was undertaken to develop these evidence-based guidelines. The Agency for Healthcare Research and Quality’s (AHRQ) Evidence-Based Practice Centers conducted systematic reviews on these topics, which were used by the Expert Panel Working Group as a basis for developing recommendations and guidance. The Expert Panel used GRADE (Grading of Recommendations, Assessment, Development and Evaluation), an internationally accepted framework, in consultation with an experienced methodology team for determining the certainty of evidence and the direction and strength of recommendations based on the evidence. Practical implementation guidance for each recommendation incorporates findings from NHLBI-led patient, caregiver, and clinician focus groups. To assist clincians in implementing these recommendations into patient care, the new recommendations have been integrated into the existing Expert Panel Report-3 (EPR-3) asthma management step diagram format.

Background Asthma in obese individuals is poorly understood, these patients are often refractory to standard therapy. Objectives To gain insights into the pathogenesis and treatment of asthma in obese individuals by determining how obesity and bariatric surgery affect asthma control, airway hyperresponsiveness and markers of asthmatic inflammation. Methods A prospective study of (i) asthmatic and non-asthmatic bariatric surgery patients compared at baseline, and (ii) asthmatic patients followed for 12 months after bariatric surgery. Results We studied 23 asthmatic and 21 non-asthmatic patients undergoing bariatric surgery. At baseline, asthmatics had lower FEV1 and FVC, and lower levels of lymphocytes in bronchoalveolar lavage. Following surgery, asthmatic participants experienced significant improvements in asthma control (asthma control score 1.55 to 0.74, p < 0.0001) and asthma quality of life (4.87 to 5.87, p < 0.0001). Airways responsiveness to methacholine improved significantly (PC20 3.9 to 7.28, p = 0.03). There was a statistically significant interaction between IgE status and change in airways responsiveness (p for interaction term = 0.01), improvement in AHR was significantly related to change in BMI in those with normal IgE (p = 0.02, R2 = 0.46). The proportion of lymphocytes in bronchoalveolar lavage and production of cytokines from activated peripheral blood CD4+ T cells increased significantly. Conclusions Bariatric surgery improves airway hyperresponsiveness in obese asthmatics with normal serum IgE. Weight loss has dichotomous effects on airway physiology and T cell function typically involved in the pathogenesis of asthma, suggesting that obesity produces a unique phenotype of asthma that will require a distinct therapeutic approach.