Tumor necrosis factor receptor 2 as a possible marker of COPD in smokers and ex-smokers.

Introduction: Oxidative stress and systemic inflammation are higher in smokers and patients with COPD; however, markers that may help differentiate between smokers and patients with COPD have not yet been identified. We hypothesized that tumor necrosis factor-alpha receptor (TNFR) and soluble form of the receptor for advanced glycation end products (sRAGE) can be indicators of COPD in asymptomatic patients.

Patients And Methods: We evaluated 32 smokers (smoking history >10 pack-years), 32 patients with mild/moderate COPD (smokers and ex-smokers), and 32 never smokers. Concentrations of C-reactive protein (CRP), interleukin (IL)-6, TNFR1 and TNFR2, advanced glycation end products (AGEs), and the sRAGE were measured in serum.

Results: There were higher CRP and AGEs concentrations in smokers and in patients with COPD (<0.001 and =0.01, respectively) compared to controls, without statistical difference between smokers and patients with COPD. Concentrations of sRAGE, IL-6, and TNFR1 did not differ between study groups. TNFR2 was significantly higher in patients with COPD than in smokers (=0.004) and controls (=0.004), and the presence of COPD (=0.02) and CRP (=0.001) showed a positive association with TNFR2. Positive associations for smoking (=0.04), CRP (=0.03), and IL-6 (=0.03) with AGEs were also found. The interaction variable (smoking × COPD) showed a positive association with IL-6.

Conclusion: Our data suggest that TNFR2 may be a possible marker of COPD in asymptomatic smokers and ex-smokers. Although smokers and patients with early COPD presented other increased systemic inflammation markers (eg, CRP) and oxidative stress (measured by AGEs), they did not differentiate smokers from COPD.