Smoking and FOS expression from blood leukocyte transcripts in patients with coronary artery disease

Analysis of the leukocyte transriptome, in particular the Finkel-Biskis-Jinkins Osteosarcoma (c-Fos) gene, which has a prominent role in inflammation, provides new insights into atherosclerosis mechanisms. Although smoking is a major risk factor, the links between smoking status and coronary artery disease (CAD) remains unclear. We aimed to analyze the relationship between smoking status and c-Fos expression in circulating leukocytes of patients with CAD.

c-Fos expression was measured by RT-Q-PCR, from blood leukocytes of 239 consecutive patients after acute myocardial infarction (MI). The patients were asked about their smoking status and stratified into 3 groups: current smokers (CS) (N = 85), past smokers (PS) (N = 78) and never smokers (NS) (N = 76).

NS had a higher risk profile including hypertension, and CS were younger than PS and NS (-13 years and 17 years respectively). There was only a trend towards lower CRP levels in NS and PS than in CS. The mean c-Fos transcript level was slightly higher in CS than in PS and NS (0.924 vs. 0.908 and 0.861 AU, respectively; p = 0.005). By univariate analysis, neither age, nor sex, nor CRP nor white blood cell count was associated with c-Fos transcript levels. By multivariate analysis, CS (vs. PS + NS) was the strongest predictor of the c-Fos transcript level, (B = 0.042 ± 0.014, p = 0.003), even after adjustment for confounding factors (i.e. hypertension, chronic medication, family history of CAD, and prior MI).

Our work suggests that c-Fos transcript level in blood leukocyte could be considered a cumulative biomarker of smoking. As the c-Fos gene has been put forward as a new factor in the progression and severity of atherosclerosis, it could be considered a novel potential pathway of tobacco toxicity in coronary artery disease.