Current research shows that obesity greatly increases the risk of developing asthma.
Although the two conditions are clearly related, experts do not fully understand why they
are linked. Some researchers believe that hormones released in the fat cells (adipokines)
play a role. Others believe that excess weight pressing on the lungs triggers the
hyperreactive response in the airways that is typical of asthma.
The goal of the Asthma-Bariatric Surgery Study is to determine how weight loss affects lung
function and various biological parameters. Bariatric (weight loss) surgery refers to the
various surgical procedures performed to treat obesity. Specifically, this study is designed
to answer the following questions:
- Does bariatric surgery help patients control their asthma?
- How much asthma control can be achieved through weight loss?
- How does weight loss influence lung function?
Participants in this observational research study will be asked to complete study visits at
enrollment, 1 month, 6 months, and 12 months. Questionnaires, pulmonary function tests, and
blood samples will be required at each time point.
This research study is observational only; it does not cover the cost of (or provide)
bariatric surgery. Optional genetic and bronchoscopy substudies are included as well.
This study is designed to explain the unexpected effects of obesity on NO bioavailability in
the airways of asthmatics: Specifically, that obesity induces systemic oxidative stress in
part through increased production of reactive oxygen species (ROS) in adipose tissue and, in
parallel (or as a consequence), increased systemic levels of tumor necrosis factor
(TNF-α)and 8-isoprostanes. Furthermore, it creates an imbalance in the regulation of
protective anti-oxidant thiol/disulfide pairs such as glutathione/glutathione disulfide. We
hypothesize that in asthmatics, the lung is a target-organ of this obesity-related systemic
oxidative stress. This is manifested as increased oxidation of airway NO into nitrate and
reactive nitrogen species (RNS) including peroxynitrate and nitrotyrosine, thereby reducing
NO bioavailability and exhaled NO levels. NO has many key physiological properties including
bronchodilation, anti-tumoral/bactericidal activity, and anti-inflammatory and
anti-oxidative activity. Thus, reduced NO bioavailability in obese asthmatics could favor
increased bronchoconstriction and impair the lung's ability to respond to further oxidative
or inflammatory challenges. Therefore, we hypothesize that: 1) obesity causes redox stress
in the airway, which in turn decreases the bioavailability of NO by shunting it into RNS, 2)
that weight loss will decrease systemic oxidative stress and thereby increase NO
bioavailability due to decreased oxidation into RNS, and 3) that by decreasing systemic
oxidative stress, weight loss will reduce bronchial hyper-reactivity.
- Non-smoker, or a limited smoking history
- Meet criteria for bariatric surgery according to NIH guidelines
- Illicit drug use
- Greater than 10 pack-year history of cigarette smoking
- Other significant lung pathology
- Other significant non-pulmonary co-morbidities