The purpose of this study is to examine whether there are higher levels of cysteinyl leukotrienes in obese subjects than in non-obese subjects. Cysteinyl leukotrienes are pro-inflammatory substances that cause asthma by narrowing the airways of the lung. The investigators want to see if subjects with increased fat stores and therefore increased leptin, which is a fat-related protein that regulates leukotrienes, have increased levels of leukotrienes in the blood, lung and urine. The investigators would also like to determine the relationship between cysteinyl leukotrienes and exhaled nitric oxide levels in asthmatics with and without obesity. Nitric oxide is anti-inflammatory and suppresses leukotriene synthesis.
This is a cross-sectional observational study to characterize the association between obese asthmatics and the inflammatory mediators cysteinyl leukotrienes. Our hypothesis is that altered adipokine levels in obesity result in augmented cysteinyl leukotriene synthesis that play a significant role in the pathogenesis of asthma in these subjects.
Study Type
OBSERVATIONAL
Enrollment
117
University of Michigan
Ann Arbor, Michigan, United States
Plasma Leptin
Measurement of plasma leptin in obese and non obese asthmatics and non-asthmatic subjects from a single blood draw.
Time frame: Observational: one time point from a blood draw after more than 6 hours fasting
Exhaled Nitric Oxide (FeNO)
Exhaled breath nitic oxide ppb (averaged values from 2 exhalations per participant)
Time frame: Observational: Two exhalations within 1 minute
Urine Cysteinyl Leukotriene Per Creatinine
Urine inflammatory mediators measured from a single urine sample
Time frame: sample taken over 5 minutes or less
Ratio U Cys-LT/FeNO
Responsiveness to leukotriene modifier medication by measuring the urine cysteinyl leukotriene/exhaled nitric oxide ratio
Time frame: sample taken over 5 minutes or less
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