Effects of obesity and bariatric surgery on airway hyperresponsiveness, asthma control, and inflammation

Abstract

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.