Cigarette smoking is the major cause of chronic obstructive pulmonary disease (COPD), the 4th cause of mortality in the US. Central to COPD pathogenesis is "ciliopathy", dysfunction of the airway ciliated cells that mediate transport of mucus to remove inhaled pathogens. The COPD ciliopathy leads to mucus accumulation, impaired host defense and recurrent infections. Using a state-of-the-art platform for global metabolite profiling and unique cohorts with serum and lung biologic samples, our deliverables are to identify a metabolome focused on biomarkers related to airway ciliopathy in COPD, and use the observed metabolic changes to: (1) direct mechanistic studies to define ciliopathy at a molecular level; (2) identify novel targets for therapeutic intervention in COPD; and (3) identify smokers at high risk for COPD. Preliminary metabolic data led to our first clues - COPD smokers have decreased serum citrulline levels, consistent with a deficiency in lung nitric oxide synthase (NOS) activity, and thus lung nitric oxide (NO) deficiency. This, together with supporting data of a smoking-induced NOS/NO-related ciliopathy, and knowledge that smokers have significant oxidant-related changes in the airway epithelial transcriptome, led to our aims, combining metabolomics of defined cohorts, murine and human mechanistic studies and computational / statistical integration.