Serum neopterin and IL-6 as biomarkers in patients with COPD

The pteridine compound, neopterin, is considered as an early biomarker of the cellular immune response. It is produced in interferon-γ activated macrophages and dendritic cells via breaking down of GTP to 7,8-dihydroneopterin, a reaction catalyzed by GTP cyclohydrolase I. Since there are evidences for accumulation of macrophages in airways in chronic obstructive pulmonary disease (COPD), we aimed to explore the possible role of serum neopterin and the well known inflammatory mediators IL-6 as biomarkers in this disease. We assessed neopterin and IL-6 in serum of 66 patients (43 males and 23 females) and 24 control individuals (11 males and 13 females) using ELISA method. The serum levels of neopterin in COPD patients were significantly higher (median of 2.58 ng/ml) than controls (1.47ng/ml, p<0.0001, Mann-Whitney test). Based on the ROC curves we found that the value of 2.00 ng/ml can determines COPD with 77.8% sensitivity and 65% specificity (p=0.001). The serum levels of IL-6 in COPD patients tended to be elevated than in controls (median of 2.08 pg/ml vs. 1.26 pg/ml, p=0.096), especially when only GOLD stage II patients were analyzed (median 2.95 pg/ml, p=0.005). The concentrations of both inflammatory markers significantly correlated in controls (Rho=0.700, p=0.003), as well as in patients with advanced disease (GOLD stage III/IV, Rho=0.510, p=0.037), but not in patients with early stage (GOLD II, p =0.695). Based on the current findings, we confirm that neopterin can be considered as non-specific biomarker for inflammatory process in COPD, while IL-6 is marker only in early stage of the disease. This work was supported by project 4/2014, MF, TrU and COST Action CA15129.