Study to Evaluate the Effects of Weight Loss on Airway Inflammation and Mechanics in Subjects With Asthma (Asthma-Bariatric Surgery Study)

Study to Evaluate the Effects of Weight Loss on Airway Inflammation and Mechanics in Subjects With Asthma

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.

Study Overview

• Status: Completed
• Conditions: Asthma

Detailed Description

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.

• Study Type: Observational
• Enrollment (Anticipated): 80

Contacts and Locations

Study Locations

• United States
  • Georgia
    • Atlanta, Georgia, United States, 30308
      • Emory University, Emory Crawford Long Hospital, Clinical Research Center

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 70 years (Adult, Older Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

• Sampling Method: Non-Probability Sample

Study Population

Obese asthmatics

Description

Inclusion Criteria:

• Non-smoker, or a limited smoking history
• Meet criteria for bariatric surgery according to NIH guidelines

Exclusion Criteria:

• Illicit drug use
• Greater than 10 pack-year history of cigarette smoking
• Other significant lung pathology
• Other significant non-pulmonary co-morbidities

Study Plan

How is the study designed?

Number of groups / cohorts

2

Cohorts and Interventions

Group / Cohort
Surgical cases; Subjects who are undergoing bariatric surgery
Controls; Subjects who qualify for bariatric surgery but do not undergo the procedure

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Time Frame
To measure levels of exhaled nitric oxide, reactive nitrogen species, exhaled biomarkers of lipid peroxidation, asthma quality of life, airway function (spirometry and response to methacholine), and degree of asthma control	Enrollment, 1 month, 6 months, and 1 year
To measure systemic markers of redox stress and inflammation, including plasma levels of adipokines, adiposity-related cytokines (IL-6, TNF-α), GSH/GSSG, 8-isoprostanes, and leukotrienes	Enrollment, 1 month, 6 months, and 1 year

Collaborators and Investigators

• Sponsor: Emory University
• Collaborators: National Institutes of Health (NIH)

Study record dates

Study Major Dates

• Study Start: July 1, 2006
• Primary Completion (Actual): September 1, 2008
• Study Completion (Actual): September 1, 2008

Study Registration Dates

• First Submitted: February 4, 2008
• First Submitted That Met QC Criteria: February 4, 2008
• First Posted (Estimate): February 14, 2008

Study Record Updates

• Last Update Posted (Estimate): July 31, 2013
• Last Update Submitted That Met QC Criteria: July 30, 2013
• Last Verified: July 1, 2013

More Information

Terms related to this study

• Keywords: Asthma, obesity, bariatric
• Additional Relevant MeSH Terms: Pathologic Processes; Respiratory Tract Diseases; Immune System Diseases; Lung Diseases; Hypersensitivity, Immediate; Bronchial Diseases; Body Weight; Lung Diseases, Obstructive; Respiratory Hypersensitivity; Hypersensitivity; Body Weight Changes; Inflammation; Asthma; Weight Loss
• Other Study ID Numbers: IRB00000064