Biomarkers of Systemic Inflammation in Stable and Exacerbation Phases of COPD

Apart from the deleterious effects on the lungs, chronic obstructive pulmonary disease (COPD) should be considered a complex, systemic disease involving several organs and systems. The nature and course of systemic inflammation in COPD is important since there is a potential for anti-inflammatory therapy. The objective of the current study was to assess biomarkers of systemic inflammation in stable and exacerbation phases of COPD patients as compared to healthy controls. We also investigated the course of these biomarkers after COPD exacerbation to evaluate their usefulness for disease monitoring. Eighty-three stable patients with moderate to very severe COPD, 20 patients in exacerbation phase, and 30 subjects with normal pulmonary function were included. Serum tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), and nitric oxide (NO) levels were measured once in stable COPD patients and controls and three times in the COPD exacerbation group during follow-up. TNF-α and IL-6 levels were higher than in controls in both stable and exacerbation groups. Although NO was not higher in the stable COPD group than in controls, it was higher in the exacerbation group. In follow-up after the exacerbation period, significant alteration was not detected in cytokine or NO levels compared to admission. Raised serum levels of TNF-α and IL-6 support their use as biomarkers of the systemic inflammatory response in stable COPD patients. However, the circulating biomarkers we have studied are not found to be useful either as indicators of COPD exacerbation or for monitoring recovery after exacerbation.