Asthma in Obesity and Diabetes: Novel Mechanisms and Effects of Bariatric Surgery

While the association of asthma with obesity and type 2 diabetes has been known for some time, the underlying pathogenic mechanisms have not been sufficiently determined. Reduced lung volume due to the elevation of the diaphragm is one likely factor, but only recently has it been recognized that the state of chronic inflammation in obesity and type 2 diabetes may also be associated with an increase in the expression of specific factors related to asthma. Weight loss is known to reduce oxidative and inflammatory stress in obese persons; marked weight loss following bariatric surgery reduces it dramatically. With the reversal of inflammation in general, there is also a reduction in the expression/concentration of asthma-related factors. Consistent with this, there is also a reversal of bronchopulmonary abnormalities in morbidly obese patients with asthma, including bronchoconstrictive responses to methacholine. Bariatric surgery also results in fewer acute exacerbations of asthma.