International Journal of COPD (Jun 2017)
Anti-p-benzoquinone antibody level as a prospective biomarker to identify smokers at risk for COPD
Abstract
Santanu Banerjee,1 Parthasarathi Bhattacharyya,2 Subhra Mitra,3 Somenath Kundu,4 Samiran Panda,5 Indu B Chatterjee1 1Department of Biotechnology and Dr B C Guha Centre for Genetic Engineering and Biotechnology, University College of Science and Technology, University of Calcutta, 2Institute of Pulmocare and Research, 3Department of Pulmonary Medicine, Calcutta National Medical College, 4Department of Chest Medicine, Institute of Post Graduate Medical Education and Research, 5National Institute of Cholera and Enteric Diseases, Kolkata, India Background and objective: Identification of smokers having predisposition to COPD is important for early intervention to reduce the huge global burden of the disease. Using a guinea pig model, we have shown that p-benzoquinone (p-BQ) derived from cigarette smoke (CS) in the lung is a causative factor for CS-induced emphysema. p-BQ is also derived from CS in smokers and it elicits the production of anti-p-BQ antibody in humans. We therefore hypothesized that anti-p-BQ antibody might have a protective role against COPD and could be used as a predictive biomarker for COPD in smokers. The objective of this study was to compare the serum anti-p-BQ antibody level between smokers with and without COPD for the evaluation of the hypothesis. Methods: Serum anti-p-BQ antibody concentrations of current male smokers with (n=227) or without (n=308) COPD were measured by an indirect enzyme-linked immunoabsorbent assay (ELISA) developed in our laboratory. COPD was diagnosed by spirometry according to Global Initiative for Chronic Obstructive Lung Disease (GOLD) guidelines.Results and discussion: A significant difference was observed in the serum anti-p-BQ antibody level between smokers with and without COPD (Mann–Whitney U-test =4,632.5, P=0.000). Receiver operating characteristic (ROC) curve analysis indicated that the ELISA had significant precision (area under the curve [AUC] =0.934, 95% confidence interval [CI]: 0.913–0.935) for identifying smokers with COPD from their low antibody level. The antibody cutoff value of 29.4 mg/dL was constructed from the ROC coordinates to estimate the risk for COPD in smokers. While 90.3% of smokers with COPD had a low antibody value (≤29.4 mg/dL), the majority (86.4%) of smokers without COPD had a high antibody value (>29.4 mg/dL); 13.6% of current smokers without COPD having an antibody level below this cutoff value (odds ratio [OR] =59.3, 95% CI: 34.15–101.99) were considered to be at risk for COPD.Conclusion and future directions: Our results indicate that serum anti-p-BQ antibody level may be used as a biomarker to identify asymptomatic smokers at risk for COPD for early intervention of the disease. Keywords: COPD, cigarette smoke, biomarker, anti-p-benzoquinone antibody, enzyme-linked immunosorbent assay (ELISA)
