Asthma affects 20 million people in the United States. It can be caused by many factors, including exposure to tobacco smoke, infections, and other allergens. Recent research suggests that there may be a relationship between obesity and asthma. It is not fully understood how these two conditions are linked, but inflammation may play a role. Obesity-related inflammation may increase the risk of airway inflammation, thereby elevating the risk of developing asthma. Increased inflammation related to obesity may also reduce the effectiveness of inhaled steroid asthma medications, including glucocorticoids. Compared with people of normal weight, people who are overweight or obese may have a higher risk of developing glucocorticoid insensitivity, resulting in intolerance to glucocorticoid medications. The purpose of this study is to examine the effect that obesity has on glucocorticoid insensitivity and inflammation. This study will also examine differences in the response to asthma steroid medications between people who are overweight or obese and those who are not.~This study will use previously collected data from participants in two clinical trials of the NHLBI-funded Asthma Clinical Research Network (ACRN): the Best Adjustment Strategy for Asthma in Long Term (BASALT) study (NCT00495157) and the Tiotropium Bromide as an Alternative to Increased Inhaled Corticosteroid in Patients Inadequately Controlled on a Lower Dose of Inhaled Corticosteroid (TALC) study. There will be no additional study visits specifically for this study. Researchers will examine blood samples collected at participants' first BASALT or TALC study visit to analyze levels of inflammation biomarkers (including tumor necrosis factor-alpha [TNF-α], interleukin-6 [IL-6], and leptin) and proinflammatory cytokines levels, which influence glucocorticoid insensitivity. Additional BASALT and TALC study data, including lung function, asthma symptoms, and asthma exacerbations, will also be analyzed.
Asthma is a common, long-term disease that is caused by inflammation of the airways. Inflammation also plays a role in obesity and may affect the way a person responds to asthma medication. This study will examine the relationship between obesity and inflammation and the effect they have on response to corticosteroid asthma medications.