Abstract
BackgroundSmoking is the leading cause of preventable death worldwide and has been shown to increase the risk of multiple diseases including coronary artery disease (CAD). We sought to identify genes whose levels of expression in whole blood correlate with self-reported smoking status.MethodsMicroarrays were used to identify gene expression changes in whole blood which correlated with self-reported smoking status; a set of significant genes from the microarray analysis were validated by qRT-PCR in an independent set of subjects. Stepwise forward logistic regression was performed using the qRT-PCR data to create a predictive model whose performance was validated in an independent set of subjects and compared to cotinine, a nicotine metabolite.ResultsMicroarray analysis of whole blood RNA from 209 PREDICT subjects (41 current smokers, 4 quit ≤ 2 months, 64 quit > 2 months, 100 never smoked; NCT00500617) identified 4214 genes significantly correlated with self-reported smoking status. qRT-PCR was performed on 1,071 PREDICT subjects across 256 microarray genes significantly correlated with smoking or CAD. A five gene (CLDND1, LRRN3, MUC1, GOPC, LEF1) predictive model, derived from the qRT-PCR data using stepwise forward logistic regression, had a cross-validated mean AUC of 0.93 (sensitivity=0.78; specificity=0.95), and was validated using 180 independent PREDICT subjects (AUC=0.82, CI 0.69-0.94; sensitivity=0.63; specificity=0.94). Plasma from the 180 validation subjects was used to assess levels of cotinine; a model using a threshold of 10 ng/ml cotinine resulted in an AUC of 0.89 (CI 0.81-0.97; sensitivity=0.81; specificity=0.97; kappa with expression model = 0.53).ConclusionWe have constructed and validated a whole blood gene expression score for the evaluation of smoking status, demonstrating that clinical and environmental factors contributing to cardiovascular disease risk can be assessed by gene expression.
Highlights
Smoking is the leading cause of preventable death worldwide and has been shown to increase the risk of multiple diseases including coronary artery disease (CAD)
Maximum coronary artery stenosis, age, and neutrophil count were all significantly associated with smoking status (Table 1). 5096 probes mapping to 4214 unique genes were significantly associated with smoking status in a sex- and age-adjusted logistic regression model (p < 0.05, Additional file 1: Table S1); of the 4214 genes, 39% (1649) were down-regulated in response to smoking status whereas 61% (2565) were up-regulated
The most significant associations with smoking status were observed in two up-regulated genes (LRRN3, CLDND1) both of which remained significant after adjusting for multiple testing (p < 1.22 × 10-6)
Summary
Smoking is the leading cause of preventable death worldwide and has been shown to increase the risk of multiple diseases including coronary artery disease (CAD). By both active and passive means, contributes to the increased risk and development of numerous diseases, including asthma, chronic obstructive pulmonary disease (COPD), and several types of cancer [2]. Changes in gene expression in peripheral blood cells correlate with a number of systemic inflammatory and immune-related disorders, including cardiovascular disease [4,5,6,7,8]. We have recently described the development and validation of a peripheral blood gene expression score (GES) for the assessment of the likelihood of obstructive CAD in non-diabetic patients [7,9]. The GES is related to the current likelihood of obstructive CAD [7,9]
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
